WO2014064932A1 - Induction heating device - Google Patents

Abstract

An induction heating device has a configuration in which a controller controls a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch and thereby selectively switches between a simultaneous heating mode in which high-frequency power is simultaneously supplied to a first heating coil and a second heating coil, a first single heating mode in which high-frequency power is supplied to the second heating coil, a second single heating mode in which high-frequency power is supplied to the first heating coil, an alternate heating mode for alternately enabling the first single heating mode and the second single heating mode, and a step-down simultaneous heating mode in which high-frequency power is simultaneously supplied to the first heating coil and the second heating coil.

Description

Induction heating device

The present disclosure relates to an induction heating apparatus including an induction heating cooking apparatus that performs heating of an object to be heated using induction heating by a high frequency magnetic field.

A conventional induction heating apparatus will be described with reference to the drawings. FIG. 38 is a diagram showing a circuit configuration of a conventional induction heating apparatus. A conventional induction heating apparatus includes an AC power source 101 that is a commercial power source, a rectifier circuit 102 that rectifies the commercial power source, a choke coil 104 that smoothes a rectified voltage from the rectifier circuit 102, and a smoothing capacitor 105. A circuit 130, a first inverter 114 that converts the output of the smoothing capacitor 105 into high-frequency power and supplies the high-frequency power to the first heating coil 106, and a second inverter that converts the output of the smoothing capacitor 105 into high-frequency power. A second inverter 115 that supplies high-frequency power to the heating coil 107, an input current detection unit 103 that detects an input current from the AC power supply 101, and a control unit 113 are included. The control unit 113 is configured by a microcomputer or the like, and controls the operation state of the semiconductor switches in the first inverter 114 and the second inverter 115 so that the detection value of the input current detection unit 103 becomes a set value. .

In the conventional induction heating apparatus configured as described above, since the rectifier circuit 102, the choke coil 104, and the smoothing capacitor 105 are shared by the two inverters 114 and 115, the circuit can be reduced in size. .

The operation of the conventional induction heating apparatus configured as described above will be described. The control unit 113 includes the first inverter 114 and the first inverter 114 so that the input current value detected by the input current detection unit 103 configured by a current transformer or the like from the AC power supply 101 becomes a preset current value. The conduction time of the semiconductor switch in the two inverters 115 is controlled. When the control unit 113 performs the control as described above, a necessary high-frequency current is supplied to the first heating coil 106 and the second heating coil 107 connected to the first inverter 114 and the second inverter 115. .

The high-frequency current supplied to the first heating coil 106 and the second heating coil 107 generates a high-frequency magnetic field from the first heating coil 106 and the second heating coil 107, and the heating coils 106 and 107 are magnetically coupled. A high-frequency magnetic field is applied to a load such as a pan that is coupled to the target.

As described above, an eddy current is generated in the load by the high-frequency magnetic field applied to the load such as the pan, and the pan itself generates heat due to the eddy current and the skin resistance of the pan itself.

In addition, the control unit 113 changes the input current to the first inverter 114 and the second inverter 115 in order to adjust the heating amount of a load such as a pan, so that the detection value of the input current detection unit 103 becomes the target. The operating frequency and the conduction ratio of the semiconductor switches of the first inverter 114 and the second inverter 115 are controlled so as to be values (see, for example, Patent Documents 1 and 2).

Furthermore, in the conventional induction heating device, when heating a load such as a pan placed on the top surface made of crystallized glass or the like, in order to efficiently heat loads of various shapes, a plurality of A configuration using a heating coil has been proposed. As a shape of the heating coil, a configuration in which a plurality of heating coils are arranged on a concentric circle, a configuration in which a plurality of auxiliary heating coils having different central positions are arranged around the heating coil, or a plurality of heating coils having a small shape in a matrix shape A configuration to be arranged has been proposed.

On the other hand, when different electric power is supplied to each of the plurality of heating coils, an inverter is provided for each heating coil. Therefore, there is a problem that the mounting area of the inverter is increased and the shape of the device is increased. Moreover, in the structure using a some heating coil, since a some inverter operate | moves with a different operating frequency, the interference sound resulting from an operating frequency difference generate | occur | produces.

US Patent Application Publication No. 2007/135037 Japanese Patent Application Laid-Open No. 09-251888

In the conventional induction heating apparatus, a semiconductor switch is required in an inverter that drives each of the first heating coil and the second heating coil. For this reason, the conventional induction heating device requires a semiconductor switch and its drive circuit for each inverter, requires a mounting area corresponding to the drive circuit, and makes it difficult to further reduce the size of the device. is doing.

Further, when the first heating coil and the second heating coil operate simultaneously, a method of driving each heating coil at the same frequency in order to suppress the generation of interference sound due to the difference in operating frequency, or There has been proposed a method of operating with a frequency difference greater than the audible range. However, depending on the type of load, the operating frequency may not be the same, and interference noise may occur. Further, the above method has problems such as complicated control of the semiconductor switch and difficulty in circuit design.

In order to solve these problems, three semiconductor switches disclosed in Japanese Patent Laid-Open No. 09-251888 are connected in series, and two heating coils are controlled in a time-sharing manner. And the control method which switches the heating operation of each heating coil for every fixed time is proposed.

However, even in such a conventional induction heating device, when the material of the load to be heated is different, the impedance such as the inductance and resistance value of the heating coil coupled to the load changes due to the difference in the electrical characteristics of the load. For this reason, the resonance characteristic determined by the value of the resonance capacitor connected to the heating coil changes. Therefore, in the conventional induction heating apparatus, there is an apparatus that adopts a method of adjusting the power supplied to the load by changing the operating frequency according to the resonance characteristics.

However, when adjusting the power supply by such a method, if the loads of different materials are heated at the same time, there will be a difference in the operating frequency between the loads, and the interference caused by the difference in the operating frequency. There was a problem that sound was generated and noise during operation increased.

Further, as disclosed in Japanese Patent Application Laid-Open No. 09-251888, in a control method in which two heating coils are alternately heated in a time-division manner for a certain period of time, switching is performed in a method in which the heating coils are alternately switched every certain period of time. During the pause period, the feeling of boiling periodically disappears, and during the heating operation period, a large amount of electric power is supplied to one heating coil, and the cooked food is easily burnt. It was.

In addition, in a conventional induction heating apparatus in which a plurality of heating coils having a small shape are arranged in a matrix, a plurality of heating coils are driven according to the shape of a load to be heated. Impedance changes greatly. As a result, it is very difficult to adjust the power supplied to the load at the same operating frequency. In addition, when the load is simultaneously heated by the adjacent heating coils, there are problems such that the operating frequency is different, an interference sound is generated due to the difference in the operating frequency, and the noise is increased.

The present disclosure solves various conventional problems, and even when high-frequency power is supplied to a plurality of heating coils, there is no interference sound and has excellent cooking performance according to the state of the load. An object of the present invention is to provide an induction heating device with a small number of points, a small circuit mounting area, and a low manufacturing cost.

The induction heating device of the first aspect according to the present disclosure is:
A series connection of a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch connected to a power source;
A series connection of a first heating coil and a first resonant capacitor connected in parallel to the first semiconductor switch and magnetically coupled to a load;
A series connection of a second heating coil and a second resonant capacitor connected in parallel to the third semiconductor switch and magnetically coupled to a load;
A controller that controls the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch;
The control unit always turns on the first semiconductor switch, turns on the second semiconductor switch and the third semiconductor switch alternately, and supplies high-frequency power to the second heating coil. Single heating mode,
A second single heating mode in which the third semiconductor switch is always turned on, the first semiconductor switch and the second semiconductor switch are turned on alternately, and high frequency power is supplied to the first heating coil;
The second semiconductor switch is always turned on, and the first semiconductor switch and the third semiconductor switch are turned on alternately to supply high-frequency power simultaneously to the first heating coil and the second heating coil. It is configured to selectively drive according to the simultaneous heating mode and the load.

The induction heating apparatus of the present disclosure has no interference sound even when high-frequency power is supplied to a plurality of heating coils, has excellent cooking performance according to the state of the load, has a small number of parts, and has a circuit mounting area. A small induction heating apparatus with low manufacturing cost can be provided.

The figure which shows the circuit structure of the induction heating apparatus of Embodiment 1 which concerns on this indication. The wave form diagram which shows the 1st single heating mode in the induction heating apparatus of Embodiment 1. FIG. The wave form diagram which shows the 2nd single heating mode in the induction heating apparatus of Embodiment 1. FIG. The wave form diagram which shows the simultaneous heating mode in the induction heating apparatus of Embodiment 1. The wave form diagram which shows the alternate heating mode in the induction heating apparatus of Embodiment 1. The figure which shows the structure of the induction heating apparatus of Embodiment 1. FIG. The figure which shows another structure of the induction heating apparatus of Embodiment 1. FIG. The figure which shows the circuit structure of the induction heating apparatus of Embodiment 2 which concerns on this indication. The wave form diagram which shows the 1st single heating mode in the induction heating apparatus of Embodiment 2. FIG. The wave form diagram which shows the 2nd single heating mode in the induction heating apparatus of Embodiment 2. FIG. The wave form diagram which shows the alternate heating mode in the induction heating apparatus of Embodiment 2. Waveform diagram at the time of switching operation between the first single heating mode and the second single heating mode in the alternate heating mode of the induction heating device of the second embodiment The figure explaining the electric power characteristic in the induction heating apparatus of Embodiment 2. The figure explaining the electric power characteristic in the induction heating apparatus of Embodiment 2. The figure which shows the electric power characteristic of the alternate heating mode in the induction heating apparatus of Embodiment 2. The figure which shows the structure of the induction heating apparatus of Embodiment 2. FIG. The figure which shows another structure of the induction heating apparatus of Embodiment 2. FIG. The figure which shows the circuit structure of Embodiment 3 which concerns on this indication. The figure which shows the structure of the induction heating apparatus of Embodiment 3. The figure which shows another structure of the induction heating apparatus of Embodiment 3. FIG. The figure which shows another structure of the induction heating apparatus of Embodiment 3. FIG. The wave form diagram which shows the simultaneous heating mode in the induction heating apparatus of Embodiment 3. The wave form diagram which shows the 1st single heating mode in the induction heating apparatus of Embodiment 3. The wave form diagram which shows the 2nd single heating mode in the induction heating apparatus of Embodiment 3. The wave form diagram which shows the alternate heating mode in the induction heating apparatus of Embodiment 3. In the induction heating apparatus of Embodiment 3, the figure which shows the relationship between the conduction time of the semiconductor switch in the difference in load, and the resonant voltage which generate | occur | produces in a resonant capacitor The figure which shows the change of the input electric power which generate | occur | produces in the conduction | electrical_connection time in the load difference in the induction heating apparatus of Embodiment 3. The wave form diagram which shows the pressure | voltage fall simultaneous heating mode in the induction heating apparatus of Embodiment 4 which concerns on this indication The figure which shows the circuit structure of the induction heating apparatus of Embodiment 5 which concerns on this indication. In the induction heating apparatus of Embodiment 5, the figure which shows the characteristic of the input electric power in each heating mode with respect to conduction | electrical_connection time The figure which shows the circuit structure of the induction heating apparatus of Embodiment 6 which concerns on this indication. The top view which shows the structural example which arranged the several heating coil element which comprises a heating coil group in the matrix form in the induction heating apparatus of Embodiment 6. FIG. The top view which shows the structural example which arranged the several heating coil element which comprises a heating coil group in the matrix form in the induction heating apparatus of Embodiment 6. FIG. In the induction heating apparatus of Embodiment 6, the figure which shows the relationship between the conduction time of a semiconductor switch and the resonant voltage which generate | occur | produces in a resonant capacitor with the material of load The wave form diagram which shows the simultaneous heating mode in the induction heating apparatus of Embodiment 6, The figure which shows operation | movement of the 1st operation mode of 1st Embodiment of this indication. The wave form diagram which shows the 1st single heating mode in the induction heating apparatus of Embodiment 6. The wave form diagram which shows the 2nd single heating mode in the induction heating apparatus of Embodiment 6. FIG. The wave form diagram which shows the alternate heating mode in the induction heating apparatus of Embodiment 6. The figure which shows the characteristic of the input electric power in each heating mode with respect to conduction | electrical_connection time in the induction heating apparatus of Embodiment 6. FIG. Waveform diagram showing the step-down simultaneous heating mode in the induction heating apparatus according to the seventh embodiment of the present disclosure The figure which shows the characteristic of the input electric power in each heating mode with respect to conduction | electrical_connection time in the induction heating apparatus of Embodiment 7. FIG. The top view which shows the structural example which arranged the several heating coil element which comprises a heating coil group in the matrix form in the induction heating apparatus of Embodiment 8 which concerns on this indication. The figure which shows the circuit structure of the conventional induction heating apparatus

Specific examples of the configuration of the induction heating device according to the present disclosure will be described in detail in Embodiments 1 to 8 to be described later. The induction heating device according to the present disclosure has a configuration having the following modes.

The induction heating device of the first aspect according to the present disclosure is:
A series connection of a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch connected to a power source;
A series connection of a first heating coil and a first resonant capacitor connected in parallel to the first semiconductor switch and magnetically coupled to a load;
A series connection of a second heating coil and a second resonant capacitor connected in parallel to the third semiconductor switch and magnetically coupled to a load;
A controller that controls the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch;
The control unit always turns on the first semiconductor switch, turns on the second semiconductor switch and the third semiconductor switch alternately, and supplies high-frequency power to the second heating coil. Single heating mode,
A second single heating mode in which the third semiconductor switch is always turned on, the first semiconductor switch and the second semiconductor switch are turned on alternately, and high frequency power is supplied to the first heating coil;
The second semiconductor switch is always turned on, and the first semiconductor switch and the third semiconductor switch are turned on alternately to supply high-frequency power simultaneously to the first heating coil and the second heating coil. It is configured to selectively drive according to the simultaneous heating mode and the load.

The induction heating apparatus according to the first aspect configured as described above can supply high-frequency power to a plurality of heating coils at the same time, and even if high-frequency power is supplied to the plurality of heating coils, interference noise is generated. Since it does not occur, has excellent cooking performance, and has a small number of parts, an inexpensive induction heating apparatus with a small circuit mounting area can be provided.

In the induction heating device according to the second aspect of the present disclosure, a resonance frequency generated in a first resonance circuit including the first heating coil and the first resonance capacitor in the first aspect; A resonance frequency generated in a second resonance circuit including the second heating coil and the second resonance capacitor is configured to be the same.

The induction heating apparatus according to the second aspect configured as described above can supply high-frequency power to each load substantially uniformly from each heating coil when the same load is heated by a plurality of heating coils. it can. For this reason, in the induction heating apparatus of a 2nd aspect, to-be-heated objects, such as a cooking item, can be finished uniformly, and it becomes an easy-to-use heating apparatus.

The induction heating device according to a third aspect of the present disclosure is the control unit when supplying high-frequency power to both the first heating coil and the second heating coil in the first or second aspect. However, by changing the ratio of the period for the simultaneous heating mode and the period for the first single heating mode or the second single heating mode, both the first heating coil and the second heating coil The first semiconductor switch, the second semiconductor switch, and the third semiconductor switch are controlled so that the average power supplied to the target value becomes a target value.

Since the induction heating device of the third aspect configured as described above can supply different high-frequency power to the load on each heating coil, delicate power adjustment is possible, which is easy to use. A heating device can be realized.

In the induction heating apparatus according to the fourth aspect of the present disclosure, in the first aspect, when the high-frequency power is supplied to both the first heating coil and the second heating coil, the control unit includes: An alternate heating mode in which each of the first single heating mode and the second single heating mode is repeated in a short cycle of 1 second or less is performed, and the same is applied to both the first heating coil and the second heating coil. It is configured to supply high-frequency power to.

The induction heating apparatus of the fourth aspect configured as described above has no cooking noise even when high frequency power is supplied to a plurality of heating coils, has excellent cooking performance, and has a small number of parts. Therefore, an inexpensive induction heating device with a small circuit mounting area can be realized.

In the fourth aspect of the induction heating device according to the present disclosure, the state transition between the first single heating mode and the second single heating mode in the alternate heating mode is the fourth mode. The second semiconductor switch is configured to be performed when it is in a non-conductive state.

In the induction heating apparatus of the fifth aspect configured as described above, it is not necessary to provide a special rest period when switching between the first single heating mode and the second single heating mode, and high-frequency power can be generated at high speed. The heating coil that supplies can be switched. As a result, the device user can feel the cooking situation equivalent to the case where each of the plurality of loads is continuously heated, and according to the induction heating device of the present disclosure, the cooking performance that is easy to use is realized. be able to.

In the induction heating apparatus according to a sixth aspect of the present disclosure, in the fourth or fifth aspect, the control unit supplies high-frequency power to both the first heating coil and the second heating coil. And controlling the ratio between the continuous operation time of the first single heating mode and the continuous operation time of the second single heating mode in the alternate heating mode to be the same, the first single heating mode and 2 in the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch for supplying high-frequency power to the first heating coil and the second heating coil in the second single heating mode. The input power is controlled by changing the operating frequency or conduction time of the two semiconductor switches.

In the induction heating apparatus of the sixth aspect configured as described above, since the power can be finely adjusted, an induction heating apparatus that is easy to use can be realized.

In the induction heating apparatus according to a seventh aspect of the present disclosure, in the fourth or fifth aspect, the control unit supplies high-frequency power to both the first heating coil and the second heating coil. The first heating switch and the first semiconductor switch for supplying high-frequency power to the second heating coil in the first single heating mode and the second single heating mode in the alternate heating mode, The continuous operation time of the first single heating mode and the continuous operation of the second single heating mode, with the operating frequency or conduction time of the two semiconductor switches in the second semiconductor switch and the third semiconductor switch being constant. The input power is controlled by changing the ratio with time.

In the induction heating apparatus of the seventh aspect configured as described above, since a larger range of power adjustment can be performed, an easy-to-use induction heating apparatus can be realized.

In an induction heating apparatus according to an eighth aspect of the present disclosure, in the first aspect, the first heating coil includes a plurality of first heating coil elements, and the first resonant capacitor includes a plurality of A plurality of series-connected bodies each composed of a first resonant capacitor element, wherein the plurality of first heating coil elements are respectively connected to the plurality of first resonant capacitor elements and connected in parallel to the first semiconductor switch. Is configured,
The second heating coil includes a plurality of second heating coil elements, the second resonance capacitor includes a plurality of second resonance capacitor elements, and the plurality of second heating coil elements includes the plurality of second heating coil elements. A plurality of series-connected bodies respectively connected to the second resonant capacitor element and connected in parallel to the third semiconductor switch,
The control unit switches the first semiconductor to switch between an alternate heating mode in which the first single heating mode and the second single heating mode are alternately repeated, and the simultaneous heating mode according to a material of a load. The switch, the second semiconductor switch, and the third semiconductor switch are configured to be controlled.

In the induction heating apparatus of the eighth aspect configured as described above, in the case where the same load is heated using a plurality of heating coils, the simultaneous heating is performed when the impedance of the load coupled to the heating coil is large. When the first to third semiconductor switches are operated in the mode and the impedance of the load coupled to the heating coil is reduced, the materials are different by operating the first to third semiconductor switches in the alternate heating mode. Even in this case, the impedance can be made close. For this reason, in the induction heating device of the present disclosure, even if the material of the load changes, the input power required at a constant frequency can be given to the load, no interference noise is generated, and the induction heating device has excellent controllability. Can be realized.

An induction heating device according to a ninth aspect of the present disclosure is the eighth aspect, in which the control unit causes the first semiconductor switch and the third semiconductor switch to perform the same on / off operation, and the first The step-down operation of alternately supplying the high-frequency power to the first heating coil and the second heating coil by alternately performing the on-off operation of the semiconductor switch and the third semiconductor switch and the on-off operation of the second semiconductor switch. With simultaneous heating mode,
The controller is configured to selectively switch between the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode according to the material of the load.

In the induction heating apparatus of the ninth aspect configured as described above, in the case where the same load is heated using a plurality of heating coils, when the impedance of the load combined with the heating coil is made of a material, simultaneous heating is performed. When the first to third semiconductor switches are operated in the mode and the impedance of the load coupled to the heating coil is reduced, the materials can be changed by operating the first to third semiconductor switches in the step-down simultaneous heating mode. Even when they are different, the impedance can be made close. For this reason, in the induction heating device of the present disclosure, even if the material of the load changes, the required input power can be supplied to the load at a constant frequency, and there is no interference sound and an induction heating device with excellent controllability is realized. can do.

The induction heating device according to a tenth aspect of the present disclosure is the presence of a heatable load in the vicinity of each of the first heating coil element and the second heating coil element in the eighth or ninth aspect. A plurality of first contacts that are connected to and separated from a current-carrying path that connects the first heating coil element and the series connection body of the first resonance capacitor element in parallel to the first semiconductor switch. A plurality of second opening / closing elements connected to and away from the energization path connecting the series connection bodies of the second heating coil element and the second resonant capacitor element in parallel to the third semiconductor switch. A component element,
The control unit includes the first opening / closing part element and / or the second opening / closing part corresponding to the first heating coil element and / or the second heating coil element, in which the load detection part detects a load nearby. The element is configured to be in contact.

In the induction heating apparatus of the tenth aspect configured as described above, the first heating coil and the second heating coil are configured only by the heating coil element in the vicinity of the load. In addition, a desired high-frequency power can be supplied to the load by an appropriate heating coil. As a result, according to the induction heating device of the present disclosure, it is possible to realize a heating device with high heating efficiency by heating with a uniform heating distribution with respect to the load.

The induction heating apparatus according to an eleventh aspect of the present disclosure is the presence of a heatable load in the vicinity of each of the first heating coil element and the second heating coil element in the eighth or ninth aspect. A plurality of first contacts that are connected to and separated from a current-carrying path that connects the first heating coil element and the series connection body of the first resonance capacitor element in parallel to the first semiconductor switch. A plurality of second opening / closing elements connected to and away from the energization path connecting the series connection bodies of the second heating coil element and the second resonant capacitor element in parallel to the third semiconductor switch. A component element,
The control unit includes the first opening / closing part element and / or the second opening / closing part corresponding to the first heating coil element and / or the second heating coil element, in which the load detection part detects a load nearby. The simultaneous heating mode and the alternate heating are controlled according to the number of the first heating coil element and / or the second heating coil element that controls the elements in a contact state and the load detection unit detects a load in the vicinity. The mode and the step-down simultaneous heating mode are selectively switched.

The induction heating apparatus of the eleventh aspect configured as described above can supply predetermined input power to the load at a constant frequency even if the number of heating coils changes, and has excellent controllability without interference noise. An induction heating device can be realized. In addition, since the induction heating device of the eleventh aspect can change the impedance and applied voltage of the heating coil group according to the number of heating coil elements constituting the first heating coil and the second heating coil, The power can be adjusted even when the frequency is kept constant. Furthermore, the induction heating apparatus of the eleventh aspect executes the simultaneous heating mode when the number of heating coil elements is small and the impedance is large, and when the number of heating coil elements is large and the impedance is small, the alternate heating mode is performed. By implementing the above, it is possible to supply a predetermined input power to the load at a constant frequency even if the number of heating coil elements to be connected changes, and to realize an induction heating device having no control noise and excellent controllability. Can do.

An induction heating apparatus according to a twelfth aspect of the present disclosure is the eighth or ninth aspect, wherein the plurality of first heating coil elements constituting the first heating coil and the second heating coil. The plurality of second heating coil elements constituting the are alternately arranged in a planar heating region.

The induction heating device of the twelfth aspect configured as described above can supply high-frequency power evenly from each element heating coil to the load, and thus forms an excellent heating distribution for the load. Can be realized.

Hereinafter, an induction heating apparatus according to an embodiment of the present disclosure will be described with reference to the accompanying drawings.

Hereinafter, an induction heating cooker will be described as an embodiment according to the induction heating device of the present disclosure with reference to the attached drawings. In addition, the induction heating apparatus of this indication is not limited to the structure of the induction heating cooking appliance described in the following embodiment, The technical idea equivalent to the technical idea demonstrated in the following embodiment is used. It is intended to include a device constructed based on the above.

(Embodiment 1)
An induction heating apparatus that is the induction heating cooker according to the first embodiment of the present disclosure will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a circuit configuration of the induction heating apparatus according to the first embodiment. As shown in FIG. 1, an induction heating apparatus according to Embodiment 1 includes an AC power source 1, a rectifier circuit 2 that rectifies the AC power source 1, a choke coil 4 that smoothes the current and voltage of the rectifier circuit 2, and a smoothing capacitor 5. A smoothing circuit 30 having the first semiconductor switch 10, the second semiconductor switch 11, and the third semiconductor switch 12 connected in parallel to the smoothing capacitor 5 that operates as a DC power source; A series connection body of a first heating coil 6 and a first resonance capacitor 8 connected in parallel to the semiconductor switch 10, and a second heating coil 7 and a second resonance connected in parallel to the third semiconductor switch 12. A series connection body of capacitors 9, an input current detection unit 3 that detects a current flowing from the AC power supply 1 to the rectifier circuit 2 with a current transformer, and the like so that the detection value of the input current detection unit 3 becomes a set value. A control unit 13 for controlling to third semiconductor switches 10, 11, 12, more constructed.

In addition, as a target value of the control unit 13 in the induction heating device of the present disclosure, the current and / or voltage of the heating coils 6 and 7 can be used in addition to the input current, and the present disclosure is not particularly limited. .

The semiconductor switch in the induction heating device of the present disclosure is often configured by a power semiconductor (semiconductor switch element) such as IGBT or MOSFET and a diode connected in parallel to each power semiconductor in the reverse direction. Each of the first to third semiconductor switches 10, 11, and 12 includes an IGBT power semiconductor and a diode connected in parallel to each power semiconductor in the opposite direction. Further, in many cases, a snubber capacitor that suppresses a rapid voltage rise when shifting from the on-state to the off-state is connected in parallel between the collectors and emitters of the first to third semiconductor switches 10, 11, and 12, In the configuration of the first embodiment, an example in which a snubber capacitor is connected in parallel to the first semiconductor switch 10 and the third semiconductor switches 10 and 12 is shown.

《Alternate heating mode》
About the induction heating apparatus of Embodiment 1 comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. 2A and 2B are waveform diagrams illustrating an operation (alternate heating mode) in the induction heating apparatus according to the first embodiment of the present disclosure. The alternating heating mode is a heating mode in which a first single heating mode and a second single heating mode described later are alternately repeated in a short cycle. FIG. 2A is a waveform diagram showing a first single heating mode in which high-frequency power is supplied to the second heating coil 7, and gate voltage waveforms (a) of the first to third semiconductor switches 10, 11, and 12 are shown. (C) and the current waveform (d) of the second heating coil 7 are shown. FIG. 2B is a waveform diagram showing a second single heating mode in which high-frequency power is supplied to the first heating coil 6, and the gate voltage waveforms (a) of the first to third semiconductor switches 10, 11, and 12 are shown. (C) and the current waveform (d) of the first heating coil 6 are shown.

<< First single heating mode >>
First, the first single heating mode for supplying high-frequency power to the second heating coil 7 shown in FIG. 2A will be described.

In the first single heating mode, in order to supply high-frequency power to the second heating coil 7, the control unit 13 always turns on the first semiconductor switch (Q1a) 10 and the second semiconductor switch ( Q1b) 11 and the third semiconductor switch (Q1c) 12 are controlled to be in a conductive state / non-conductive state (on state / off state). In the section A shown in FIG. 2A, the control unit 13 sets the second semiconductor switch (Q1b) 11 to the conductive state (ON state) and sets the third semiconductor switch (Q1c) 12 to the non-conductive state (OFF state). . As a result, a path of the smoothing capacitor 5 → the first semiconductor switch (Q1a) 10 → the second semiconductor switch (Q1b) 11 → the second heating coil 7 → the second resonance capacitor 9 is formed, and the second Electric power is supplied to the heating coil 7.

In the section A of FIG. 2A, the control unit 13 sets only the second semiconductor switch (Q1b) 11 in a non-conduction state during a conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value ( End of section A). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, a path of the second resonance capacitor 9 → the second heating coil 7 → the third semiconductor switch (Q1c) 12 is formed, and electric power is supplied to the second heating coil 7. Thereafter, the control unit 13 sets the third semiconductor switch (Q1c) 12 in a non-conduction state during the conduction time (section B) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (section). End of B).

After that, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state after a predetermined transition time (section Y) has elapsed (section A). As described above, the control unit 13 continues the operations in the section A and the section B through the transition time (X or Y) as illustrated in FIG. 2A.

As described above, in the first single heating mode, the control unit 13 keeps the first semiconductor switch (Q1a) 10 in the conductive state, and the second semiconductor switch (Q1b) 11 and the third semiconductor switch. By alternately turning on (Q1c) 12, a high frequency current of about 20 kHz to 60 kHz can be supplied to the second heating coil 7. A high-frequency magnetic field is generated from the second heating coil 7 by the high-frequency current supplied in this way, and the high-frequency magnetic field is supplied to a load such as a pan that is an object to be heated. Thus, an eddy current is generated on the surface of the pan or the like by the high-frequency magnetic field supplied to the load such as the pan, and the load of the pan or the like is induction-heated and generates heat by the eddy current and the high-frequency resistance of the load such as the pan. .

<< Second single heating mode >>
Next, a second single heating mode for supplying high-frequency power to the first heating coil 6 will be described with reference to FIG. 2B.

In order to supply high-frequency power to the first heating coil 6 in the second single heating mode, the control unit 13 always keeps the third semiconductor switch (Q1c) 12 in a conductive state, and the first semiconductor switch (Q1a). 10 and the second semiconductor switch (Q1b) 11 are controlled to be on / off (on / off). In the section A shown in FIG. 2B, when the second semiconductor switch (Q1b) 11 is turned on, the control unit 13 makes the smoothing capacitor 5 → the first resonant capacitor 8 → the first heating coil 6 → the second A path from the semiconductor switch (Q1b) 11 to the third semiconductor switch (Q1c) 12 is formed, and power is supplied to the first heating coil 6.

2B, only the second semiconductor switch (Q1b) 11 is brought into a non-conduction state in the conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value in the section A of FIG. 2B. End of section A). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the first semiconductor switch (Q1a) 10 into a conductive state. As a result, electric power is supplied to the first heating coil 6 through the path of the first resonant capacitor 8 → the first semiconductor switch (Q1a) 10 → the first heating coil 6 (section B). Thereafter, the control unit 13 puts the first semiconductor switch (Q1a) 10 in a non-conduction state during the conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section B). .

After that, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state after a predetermined transition time (section Y) has elapsed (section A). As described above, the control unit 13 continues the operations in the section A and the section B through the transition time (X or Y) as illustrated in FIG. 2B.

As described above, in the second single heating mode, the control unit 13 keeps the third semiconductor switch (Q1c) 12 in the conductive state, and the first semiconductor switch (Q1a) 10 and the second semiconductor switch. By alternately turning on (Q1b) 11, a high frequency current of about 20 kHz to 60 kHz can be supplied to the first heating coil 6. A high-frequency magnetic field is generated from the first heating coil 6 by the high-frequency current supplied in this manner, and the high-frequency magnetic field is supplied to a load such as a pan that is an object to be heated. Thus, the high frequency magnetic field supplied to the load such as the pan causes the load such as the pan to be induction-heated to generate heat.

《Simultaneous heating mode》
FIG. 3 is a waveform diagram showing an operation in the simultaneous heating mode in the induction heating apparatus according to the first embodiment of the present disclosure. 3, (a) to (c) are the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is the current waveform of the first heating coil 6, and ( e) is a current waveform of the second heating coil 7.

In the simultaneous heating mode, the control unit 13 always supplies the second semiconductor switch (Q1b) 11 to the first heating coil 6 and the second heating coil 7, so that the second semiconductor switch (Q1b) 11 is always in the conductive state. The semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 are controlled to be on / off (on / off).

In the section A shown in FIG. 3, when the first semiconductor switch (Q1a) 10 is turned on (on state) and the third semiconductor switch (Q1c) 12 is controlled to be non-conductive (off state), the smoothing capacitor 5 → first semiconductor switch (Q1a) 10 → second semiconductor switch (Q1b) 11 → second heating coil 7 → second resonant capacitor 9 is supplied with electric power to the second heating coil 7 The mode in which power is supplied to the first heating coil 6 simultaneously occurs in the path of the mode and the first resonance capacitor 8 → the first semiconductor switch (Q1a) 10 → the first heating coil 6.

The control unit 13 sets only the first semiconductor switch (Q1a) 10 in a non-conducting state during the conduction time in which the current value detected by the input current detecting unit 3 indicates a predetermined current value (end of section A in FIG. 3). ).

After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, in the path of the smoothing capacitor 5 → the first resonance capacitor 8 → the first heating coil 6 → the second semiconductor switch (Q1b) 11 → the third semiconductor switch (Q1c) 12, the first heating coil 6 The operation of supplying power and the operation of supplying power to the second heating coil 7 in the path of the second resonance capacitor 9 → the second heating coil 7 → the third semiconductor switch (Q1c) 12 occur simultaneously. To do.

The control unit 13 sets only the third semiconductor switch (Q1c) 12 in a non-conduction state during the conduction time (section B) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (in FIG. 3). End of section B). Thereafter, the control unit 13 sets the first semiconductor switch (Q1a) 10 in the conductive state again after a predetermined transition time (section Y) has elapsed.

As described above, in the simultaneous heating mode, the control unit 13 keeps the second semiconductor switch (Q1b) 11 in the conductive state, and the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c). By alternately bringing 12 into the conductive state, a high-frequency current of about 20 kHz to 60 kHz can be simultaneously supplied to both the first heating coil 6 and the second heating coil 7. As a result, in the induction heating apparatus of the first embodiment, the high frequency magnetic field generated from the heating coil supplied with the high frequency current is supplied to a load such as a pan.

In the induction heating apparatus of the first embodiment, by appropriately using each heating mode of the first single heating mode, the second single heating mode, and the simultaneous heating mode according to the state of load (material, etc.) Electric power can be supplied independently to the loads existing on the first heating coil 6 and the second heating coil 7, respectively, or electric power can be supplied simultaneously without interference noise. At this time, the resonance frequency constituted by the first heating coil 6 and the first resonance capacitor 8 and the resonance frequency constituted by the second heating coil 7 and the second resonance capacitor 9 are made substantially the same. When the same load is heated by the two heating coils 6 and 7 at the same time, there is an advantage that heating can be performed uniformly.

FIG. 4 is a waveform diagram showing an operation using a plurality of heating modes in the induction heating apparatus according to the first embodiment of the present disclosure. FIG. 4 shows an operation when supplying high frequency power to the first heating coil 6 and the second heating coil 7 at the same time and supplying different power to the heating coils 6 and 7. In the induction heating device of the first embodiment, the first heating coil 6 is set to have a larger supply power than the second heating coil 7.

First, the control unit 13 sets the first heating coil 6 and the second heating coil 6 with the set value of the first heating coil 6 having the larger supply power of the first heating coil 6 and the second heating coil 7. The heating coil 7 is controlled to operate in the simultaneous heating mode (see FIG. 3) for supplying power.

Next, the control unit 13 does not supply power to the second heating coil 7 with less supply power, and enters the second single heating mode in which power is supplied only to the first heating coil 6 (see FIG. 2B). Transition operation. Thereafter, when the non-conduction time determined by the average power supplied to the second heating coil 7 has elapsed, the control unit 13 causes the second independent heating mode to shift to the simultaneous heating mode again.

Here, by shortening the switching time between the respective heating modes, the user does not feel a great sense of incongruity, and the load existing on the two types of heating coils 6.7 is generated without causing an interference sound. Heating with electric power becomes possible.

In the first embodiment, the configuration in which the power supplied to the first heating coil 6 is greater than the power supplied to the second heating coil 7 has been described. However, the power supplied to the second heating coil 7 is equal to that of the first heating coil 6. In the case of a configuration that is larger than the supplied power, desired power is appropriately applied to the first heating coil 6 and the second heating coil 7 by alternately repeating the simultaneous heating mode and the first single heating mode. The same effects as those of the above-described configuration can be obtained.

FIG. 5 is a diagram illustrating an external configuration of the induction heating apparatus according to the first embodiment of the present disclosure, in which (a) on the upper side is a plan view and (b) on the lower side is disposed on the user side. It is the longitudinal cross-sectional view cut | disconnected by the approximate center part of the 1st heating coil 6 made. As shown in FIG. 5, in the induction heating apparatus of the first embodiment, the first heating coil 6 and the second heating coil 7 are arranged below the top plate 18 made of crystallized glass or the like. . On the first heating coil 6 and the second heating coil 7, loads such as pans for putting food are placed, respectively, and according to the operation from the operation / display unit 17, the plurality of heating modes (first Necessary electric power is appropriately supplied to the heating coils 6 and 7 by appropriately using the single heating mode, the second single heating mode, and the simultaneous heating mode.

In the induction heating apparatus according to the first embodiment, by performing the operations in the above-described plurality of heating modes (the first single heating mode, the second single heating mode, and the simultaneous heating mode), each cooking is performed. Cooking with electric power can be performed.

FIG. 6 is a diagram illustrating another configuration example of the induction heating apparatus according to the first embodiment of the present disclosure. In the induction heating apparatus shown in FIG. 6, an elliptical first heating coil 6 and second heating coil are provided below one heating region H shown on the top plate 18 made of crystallized glass or the like. 7 is provided, and one load such as a pan can be simultaneously heated by the two heating coils 6 and 7. In the induction heating apparatus shown in FIG. 6, the elliptical heating coils 6 and 7 are arranged in parallel so that the long diameters are on a line extending from the user side to the back side of the apparatus. In FIG. 6, (a) on the upper side is a plan view, and (b) on the lower side is a longitudinal sectional view cut at a substantially central portion of the first heating coil 6 and the second heating coil 7. In the induction heating apparatus shown in FIG. 6, when heating is performed using a plurality of heating coils with respect to a single load, it becomes possible to perform cooking with uniform heating distribution without interference noise. .

As described above, in the first embodiment, a plurality of resonance circuits including a heating coil and a resonance capacitor for inductively heating a load are connected to three semiconductor switches connected in series. One semiconductor switch is always in a conductive state (on state) as a semiconductor switch that determines a heating coil that supplies power, and the remaining semiconductor switch is in a conductive state / non-conductive state (on / off state) to supply high-frequency power to the heating coil. In addition to the operation in the single heating mode used as a semiconductor switch controlled by (2), a simultaneous heating mode in which the second semiconductor switch is always in a conductive state is used. As described above, by using the single heating mode and the simultaneous heating mode, the induction heating apparatus of the first embodiment can supply power to a plurality of heating coils at the same time, and supply high-frequency power to the plurality of heating coils. Even without interference sound, it has excellent cooking performance. In addition, since the configuration of the first embodiment has a small number of parts, the circuit mounting area is small and the heating apparatus is inexpensive.

(Embodiment 2)
An induction heating apparatus that is an induction heating cooker according to a second embodiment of the present disclosure will be described with reference to the drawings. The induction heating apparatus according to the second embodiment is useful when the operating frequency is different due to the different materials of the load such as the pan in the two heating coils, or when the load impedance is small. In the induction heating apparatus according to the second embodiment, the interference sound is generated in the alternate heating mode in which the first single heating mode and the second single heating mode described in the first embodiment are appropriately switched in a short time. It is the structure which prevents. In the description of the second embodiment, elements having substantially the same functions and configurations as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 7 is a diagram illustrating a circuit configuration of the induction heating device according to the second embodiment of the present disclosure. As shown in FIG. 7, the induction heating device of the second embodiment has a circuit configuration similar to that of the induction heating device of the first embodiment, and includes an AC power source 1, a rectifier circuit 2, and a smoothing circuit. 30, a series connection of the first to third semiconductor switches 10, 11, 12; a series connection of the first heating coil 6 and the first resonance capacitor 8; the second heating coil 7; The resonance capacitor 9 is connected in series, the input current detection unit 3, and the control unit 13.

Also in the induction heating apparatus of the second embodiment, the first to third semiconductor switches 10, 11, and 12 are connected in parallel to power semiconductors (semiconductor switch elements) such as IGBTs and MOSFETs and the respective power semiconductors in the reverse direction. Made up of diodes. In addition, a snubber capacitor may be connected in parallel between the collectors and emitters of the first to third semiconductor switches 10, 11, and 12 in order to suppress a rapid voltage rise when shifting from the on state to the off state. . In the second embodiment, a snubber capacitor is connected in parallel between the collector and emitter of the first semiconductor switch 10 and the third semiconductor switch 12.

The operation and action of the induction heating apparatus according to Embodiment 2 configured as described above will be described below. 8A and 8B are waveform diagrams illustrating an operation (alternate heating mode) in the induction heating apparatus according to the second embodiment of the present disclosure. FIG. 8A is a waveform diagram showing a first single heating mode in which high-frequency power is supplied to the second heating coil 7, and the gate voltage waveforms (a) of the first to third semiconductor switches 10, 11, and 12 are shown. (C) and the current waveform (d) of the second heating coil 7 are shown. FIG. 8B is a waveform diagram showing a second single heating mode in which high-frequency power is supplied to the first heating coil 6, and the gate voltage waveforms (a) of the first to third semiconductor switches 10, 11, and 12 are shown. (C) and the current waveform (d) of the first heating coil 6 are shown.

In order to supply high-frequency power to the second heating coil 7, the control unit 13 always keeps the first semiconductor switch (Q1a) 10 in a conductive state, and the second semiconductor switch (Q1b) 11 and the third semiconductor switch ( Q1c) Controls the conduction / non-conduction state (on state / off state) of 12. In the section A shown in FIG. 8A, the control unit 13 turns on the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 and turns on the third semiconductor switch (Q1c) 12. Is in a non-conductive state (off state). As a result, a path of the smoothing capacitor 5 → the first semiconductor switch (Q1a) 10 → the second semiconductor switch (Q1b) 11 → the second heating coil 7 → the second resonance capacitor 9 is formed, and the second Electric power is supplied to the heating coil 7.

The control unit 13 sets only the second semiconductor switch (Q1b) 11 in a non-conduction state during the conduction time (Tb) in which the current value detected by the input current detection unit 3 indicates a predetermined current value. After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, a path of the second resonance capacitor 9 → the second heating coil 7 → the third semiconductor switch (Q1c) 12 is formed, and electric power is supplied to the second heating coil 7. Thereafter, the control unit 13 sets the third semiconductor switch (Q1c) 12 in a non-conduction state during a conduction time (Tc) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (section B). End).

After that, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state after a predetermined transition time (section Y) has elapsed (section A). As described above, the control unit 13 continues the operations in the sections A and B alternately through the transition time (X or Y).

As described above, the control unit 13 alternately turns on the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 while keeping the first semiconductor switch (Q1a) 10 on. Thus, a high frequency current of about 20 kHz to 60 kHz can be supplied to the second heating coil 7. The high frequency magnetic field generated from the second heating coil 7 by the high frequency current supplied in this way is supplied to a load such as a pan.

Thus, an eddy current is generated on the surface of the load such as the pan by the high frequency magnetic field supplied to the load such as the pan, and the load such as the pan is induction-heated by the eddy current and the high frequency resistance of the load such as the pan itself to generate heat. To.

Next, a second single heating mode for supplying high-frequency power to the first heating coil 6 will be described with reference to FIG. 8B.

In order to supply high-frequency power to the first heating coil 6 in the second single heating mode, the control unit 13 always keeps the third semiconductor switch (Q1c) 12 in a conductive state, and the first semiconductor switch (Q1a). 10 and the second semiconductor switch (Q1b) 11 are controlled to be on / off (on / off). When the second semiconductor switch (Q1b) 11 is turned on in the section A shown in FIG. 8B, the control unit 13 makes the smoothing capacitor 5 → the first resonance capacitor 8 → the first heating coil 6 → the second heating switch. A path from the semiconductor switch (Q1b) 11 to the third semiconductor switch (Q1c) 12 is formed, and power is supplied to the first heating coil 6.

In the section A of FIG. 8B, the control unit 13 turns off only the second semiconductor switch (Q1b) 11 during the conduction time (Tb) in which the current value detected by the input current detection unit 3 indicates a predetermined current value. (End of section A in FIG. 8B). After the elapse of a predetermined transition time (section X), the control unit 13 brings the first semiconductor switch (Q1a) 10 into a conductive state.

As a result, a path of the first resonance capacitor 8 → the first semiconductor switch (Q1a) 10 → the first heating coil 6 is formed, and electric power is supplied to the first heating coil 6. Thereafter, the control unit 13 sets the first semiconductor switch (Q1a) 10 in a non-conduction state during a conduction time (Ta) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (in FIG. 8B). End of section B).

After that, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state after a predetermined transition time (section Y) has elapsed (section A). As described above, the control unit 13 continues the operations in the section A and the section B through the transition time (X or Y). As described above, in the second single heating mode, the control unit 13 keeps the third semiconductor switch (Q1c) 12 in the conductive state, and the first semiconductor switch (Q1a) 10 and the second semiconductor switch. By alternately turning on (Q1b) 11, a high frequency current of about 20 kHz to 60 kHz can be supplied to the first heating coil 6. The high frequency magnetic field generated from the heating coil by the high frequency current thus supplied is supplied to a load such as a pan.

FIG. 9 is a waveform diagram showing the operation in the alternate heating mode in the induction heating apparatus of the second embodiment. The alternating heating mode is an operation when heating a plurality of loads by alternately using the first single heating mode and the second single heating mode. 9, (a) to (c) are gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is a current waveform of the second heating coil 7, and ( e) is a current waveform of the first heating coil 6. In the alternate heating mode in the induction heating apparatus of the second embodiment, the operation time of the first single heating mode is T2, and the operation time of the second single heating mode is T1. Therefore, in the second embodiment, the operation time T1 and the operation time T2 are set to a very short cycle. For example, each of the operation time T1 and the operation time T2 is set within 1 second, and one cycle (T1 + T2) of the alternate heating mode is set to a very short cycle within 2 seconds.

As shown in FIG. 9, in the alternate heating mode, the load placed on the second heating coil 7 by alternately operating the first single heating mode and the second single heating mode in a short cycle. The heating operation can be performed substantially simultaneously with respect to the load placed on the first heating coil.

This is due to the fact that the controller 13 can change the heating coil that supplies power only by changing the operating states of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c).

The switching operation between the first and second individual heating modes in the alternate heating mode maintains the boiling state when boiling water is maintained by switching the heating modes within approximately one second. can do. For this reason, even if it compares with the case where it heats simultaneously with a some heating coil, it becomes possible to obtain an equivalent performance.

FIG. 10 is a waveform diagram at the time of switching operation between the first single heating mode and the second single heating mode in the alternate heating mode of the induction heating apparatus of the second embodiment. The operation state at the time of switching the heating coil which supplies electric power from the 1st single heating mode to the 2nd single heating mode at high speed is shown.

As shown in the waveform diagram of FIG. 10, when switching from the first single heating mode to the second single heating mode, the control unit 13 is configured such that when the third semiconductor switch (Q1c) 12 is in a conductive state, When the second semiconductor switch (Q1b) is in a non-conductive state, the first semiconductor switch (Q1a) is set in a non-conductive state and switched to the second single heating mode.

By switching in the above state, overvoltage or the like is not applied to the second semiconductor switch (Q1b) 11. For this reason, it is possible to smoothly switch from the first single heating mode to the second single heating mode without applying stress to each semiconductor switch.

On the other hand, when switching from the second single heating mode to the first single heating mode, the control unit 13 sets the second semiconductor switch (Q1b) when the first semiconductor switch (Q1a) 10 becomes conductive. When 11 is in a non-conductive state, the third semiconductor switch (Q1a) 12 is set in a non-conductive state to switch to the first single heating mode.

As described above, in the non-conduction period of the second semiconductor switch (Q1b) 11, by switching from the second single heating mode to the first single heating mode, the heating coil to be supplied with power smoothly in a short time It is possible to switch.

In the alternate heating mode described above, since the first heating coil 6 and the second heating coil 7 are alternately heated, the generation of interference sound due to the difference in operating frequency can be eliminated.

11A and 11B are diagrams for explaining the power characteristics in the induction heating apparatus according to the second embodiment. The characteristics when changing the amount of power supplied to the first heating coil 6 and the second heating coil 7 are shown. Show. FIG. 11A is a characteristic diagram showing characteristics of the conduction time [μsec] and input power [W] (constant operating frequency) of the semiconductor switch. FIG. 11B is a characteristic diagram showing characteristics of the operating frequency [KHz] and input power [W] (constant ON time ratio) of the semiconductor switch.

When controlling to supply power to the first heating coil 6 and the second heating coil 7 substantially at the same time, the heating is performed in order to continuously perform heating. It is necessary to shorten the transition time between modes.

Therefore, it is desirable to fix the transition time to a fixed time and change the conduction time of each semiconductor switch (see the characteristic diagram in FIG. 11A) or the operating frequency (see the characteristic diagram in FIG. 11B).

In the conduction time of the semiconductor switch, when the conduction time of the two semiconductor switches performing the high frequency operation is the same, the supply power becomes the largest (Ta = Tb, Tb = Tc). As the conduction time of one semiconductor switch decreases and the conduction time of the other semiconductor switch increases, that is, as the duty ratio falls from 1: 1, the supplied power decreases.

When the operating frequency is changed, since the operation is performed at a frequency higher than the resonance frequency of the series resonance circuit composed of the heating coil and the resonance capacitor that are normally coupled to the load, as the frequency increases, FIG. As shown, the input power decreases.

FIG. 12 is a diagram showing power characteristics in the alternate heating mode in the induction heating apparatus of the second embodiment. In the alternate heating mode, the amount of electric power supplied to the first heating coil 6 and the second heating coil 7 when the conduction time ratio (T1 / TL) of the second single heating mode in one cycle (TL) is changed. It shows a change.

As shown in FIG. 12, when the first heating coil 6 and the second heating coil 7 are heated substantially at the same time in the alternate heating mode, the first heating coil 6 and the second heating coil 7 are supplied. Each electric power to be applied is determined by a conduction time ratio when electric power is supplied to the respective heating coils 6 and 7. Therefore, when increasing the power supplied to one heating coil, it is necessary to change the conductive time ratio for supplying power to each heating coil. At this time, in the alternate heating mode, it is desirable to change only the conduction time ratio while keeping the period at the time of the alternate heating mode constant so that the user does not feel uncomfortable with the actual simultaneous heating.

FIG. 13 is a diagram illustrating an external configuration of the induction heating device according to the second embodiment of the present disclosure, in which (a) on the upper side is a plan view and (b) on the lower side is disposed on the user side. It is the longitudinal cross-sectional view cut | disconnected by the approximate center part of the 1st heating coil 6 made. As shown in FIG. 13, in the induction heating apparatus according to the second embodiment, the first heating coil 6 and the second heating coil 7 are arranged below the top plate 18 made of crystallized glass or the like. Loads of different materials and shapes are placed on the first heating coil 6 and the second heating coil 7, and necessary power is supplied to the heating coils 6, 7 according to the operation from the operation / display unit 17. It is the structure supplied with respect to it.

In the induction heating apparatus of the second embodiment, no interference sound is generated even when the control unit 13 is operated at an optimal operating frequency according to the material of the load and the necessary power set by the user. As a result, the first to third semiconductor switches 10, 11, and 12 in the induction heating apparatus according to the second embodiment are reduced in loss, and the cooling parts such as the radiation fins can be downsized. It becomes composition.

FIG. 14 is a diagram illustrating another configuration example of the induction heating apparatus according to the second embodiment of the present disclosure. In the induction heating apparatus shown in FIG. 14, an elliptical first heating coil 6 and second heating coil are provided below one heating region H shown on the top plate 18 made of crystallized glass or the like. 7 is arranged, and one load such as a pan is heated simultaneously by two heating coils 6 and 7. In the induction heating device shown in FIG. 14, the elliptical heating coils 6 and 7 are arranged in parallel so that the long diameter is on a line extending from the user side to the back side of the device. In FIG. 14, (a) on the upper side is a plan view, and (b) on the lower side is a vertical cross-sectional view cut at a substantially central portion of the first heating coil 6 and the second heating coil 7.

In the induction heating apparatus shown in FIG. 14, when heating is performed using a plurality of heating coils for a single load, it is possible to perform heating without interference noise regardless of the pan mounting state. It becomes. In this case, only a necessary heating coil can be energized in accordance with the shape and amount of the load, so that efficient heating can be performed.

As described above, in the second embodiment, a plurality of resonance circuits composed of a heating coil and a resonance capacitor for inductively heating a load are connected to three semiconductor switches connected in series, and the three of the three semiconductor switches are connected. One semiconductor switch is always in a conductive state (on state) as a semiconductor switch that determines a heating coil that supplies power, and the remaining semiconductor switch is in a conductive state / non-conductive state (on / off state) to supply high-frequency power to the heating coil. The alternate heating mode used as a semiconductor switch controlled by the above is used. By using the alternate heating mode in this way, the induction heating apparatus of the second embodiment has no interference sound even if the heating coil that supplies power at high speed is switched and high-frequency power is supplied to the plurality of heating coils. Excellent cooking performance. In addition, since the configuration of the second embodiment has a small number of parts, an inexpensive induction heating device with a small circuit mounting area can be realized.

(Embodiment 3)
An induction heating apparatus that is an induction heating cooker according to a third embodiment of the present disclosure will be described with reference to the drawings. In the description of the third embodiment, elements having substantially the same functions and configurations as those of the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 15 is a diagram illustrating a circuit configuration of the induction heating apparatus according to the third embodiment. As shown in FIG. 15, the induction heating device of the third embodiment has a circuit configuration similar to that of the induction heating device of the first embodiment, and includes an AC power supply 1, a rectifier circuit 2, and a smoothing circuit. 30, a series connection of the first to third semiconductor switches 10, 11, 12; a series connection of the first heating coil 6 and the first resonance capacitor 8; the second heating coil 7; The resonance capacitor 9 is connected in series, the input current detection unit 3, and the control unit 13.

Also in the induction heating apparatus of the third embodiment, the first to third semiconductor switches 10, 11, and 12 are connected in parallel to power semiconductors (semiconductor switch elements) such as IGBTs and MOSFETs and the respective power semiconductors in the reverse direction. Made up of diodes. In addition, a snubber capacitor may be connected in parallel between the collectors and emitters of the first to third semiconductor switches 10, 11, and 12 in order to suppress a rapid voltage rise when shifting from the on state to the off state. . In the third embodiment, a snubber capacitor is connected in parallel between the collector and emitter of the first semiconductor switch 10 and the third semiconductor switch 12.

In the induction heating apparatus of the third embodiment configured as described above, the plurality of heating coils are configured to heat loads of substantially the same material, and in particular, the same load is formed by the plurality of heating coils. Used when heating.

In the induction heating apparatus according to the third embodiment, as shown in FIG. 16, when two heating coils 6 and 7 are used, two heating coils 6 are arranged substantially concentrically within one heating region. , 7 are arranged. Moreover, as another structure in the induction heating apparatus of Embodiment 3, as shown in FIG. 17, two heating coils 6 and 7 whose planar shape is elliptical are adjacent to each other in one heating region. There is a configuration to arrange. The configuration of the induction heating apparatus according to the third embodiment includes a configuration in which one load is heated using a plurality of heating coils having different circle centers. Therefore, as shown in FIG. 18, in the configuration of the induction heating apparatus of the third embodiment, a plurality of heating coils 6, 7 are arranged in a matrix shape over almost the entire area of the top plate, and the plurality of heating coils 6, 7 are used. Configurations such as heating one load are included.

In the induction heating apparatus according to the third embodiment, when a plurality of loads (indicated by reference numeral 25 in FIGS. 16 to 18) are heated at the same time, the operating frequency of the high-frequency power supplied to the load 25 differs in most cases. ing. In such a case, when the difference in operating frequency is in the audible range, an interference sound resulting from the operating frequency difference is generated, and the user feels that the noise is loud. Therefore, it is necessary to make it possible to perform a heating operation with a constant operating frequency even if the material of the load 25 changes, and to have a configuration that does not generate interference sound.

It should be noted that the inductance values of the first heating coil 6 and the second heating coil 7 for heating one load 25 shown in FIGS. 16 to 18 are substantially the same values so that the amount of electric power is less likely to be biased. It is desirable to become.

Next, the operation of the induction heating apparatus according to the third embodiment will be described. FIG. 19 is a waveform diagram showing an operation state of the simultaneous heating mode in the induction heating apparatus of the third embodiment. 19, (a) to (c) are the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is the current waveform of the first heating coil 6, and ( e) is a current waveform of the second heating coil 7.

In the simultaneous heating mode, the control unit 13 always supplies the second semiconductor switch (Q1b) 11 to the first heating coil 6 and the second heating coil 7, so that the second semiconductor switch (Q1b) 11 is always in the conductive state. The semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 are controlled to be on / off (on / off).

In section A shown in FIG. 19, when the first semiconductor switch (Q1a) 10 is turned on (on state) and the third semiconductor switch (Q1c) 12 is turned off (off state), the smoothing capacitor 5 → first semiconductor switch (Q1a) 10 → second semiconductor switch (Q1b) 11 → second heating coil 7 → second resonant capacitor 9 is supplied with electric power to the second heating coil 7 The mode in which power is supplied to the first heating coil 6 simultaneously occurs in the path of the mode and the first resonance capacitor 8 → the first semiconductor switch (Q1a) 10 → the first heating coil 6.

The control unit 13 causes only the first semiconductor switch (Q1a) 10 to be in a non-conduction state during the conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section A). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, in the path of the smoothing capacitor 5 → the first resonance capacitor 8 → the first heating coil 6 → the second semiconductor switch (Q1b) 11 → the third semiconductor switch (Q1c) 12, the first heating coil 6 The operation of supplying power and the operation of supplying power to the second heating coil 7 in the path of the second resonance capacitor 9 → the second heating coil 7 → the third semiconductor switch (Q1c) 12 occur simultaneously. To do.

The control unit 13 sets only the third semiconductor switch (Q1c) 12 in a non-conduction state during the conduction time (section B) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (in section B). End). After the end of the section B, the control unit 13 makes the first semiconductor switch (Q1c) 10 conductive again after a predetermined transition time (section Y) has elapsed (section A).

As described above, in the simultaneous heating mode, the control unit 13 keeps the second semiconductor switch (Q1b) 11 in the conductive state, and the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c). By alternately turning on 12, a high-frequency current of about 20 kHz to 60 kHz can be simultaneously supplied to both the first heating coil 6 and the second heating coil 7. As a result, in the induction heating apparatus of the third embodiment, a desired high frequency magnetic field generated from the heating coil supplied with the high frequency current is supplied to a load such as a pan.

In addition, the induction heating apparatus according to Embodiment 3 is configured to be able to execute the alternate heating mode.

FIG. 20A is a waveform diagram showing a first single heating mode in which high-frequency power is supplied to the second heating coil 7. 20A, (a) to (c) show the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, and (d) shows the current waveform of the second heating coil 7. In FIG.

In the first single heating mode shown in FIG. 20A, the control unit 13 always keeps the first semiconductor switch (Q1a) 10 in a conductive state in order to supply high-frequency power to the second heating coil 7, and the second semiconductor The conduction state / non-conduction state (on state / off state) of the switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 is controlled. In the section A shown in FIG. 20A, the control unit 13 sets the second semiconductor switch (Q1b) 11 to the conductive state (ON state) and sets the third semiconductor switch (Q1c) 12 to the non-conductive state (OFF state). . As a result, in the path of the smoothing capacitor 5 → the first semiconductor switch (Q1a) 10 → the second semiconductor switch (Q1b) 11 → the second heating coil 7 → the second resonance capacitor 9, the second heating coil 7 Power is supplied.

The control unit 13 sets only the second semiconductor switch (Q1b) 11 in the non-conduction state during the conduction time (Tb) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section A). ). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, electric power is supplied to the second heating coil 7 in the path of the second resonance capacitor 9 → the second heating coil 7 → the third semiconductor switch 12. Thereafter, the control unit 13 sets the third semiconductor switch (Q1c) 12 in a non-conduction state during a conduction time (Tc) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (section B). End).

Then, after a predetermined transition time (section Y) has elapsed, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state (section A). As described above, the control unit 13 continues to operate the operations in the section A and the section B alternately through the transition time (X or Y).

As described above, the control unit 13 alternately turns on the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 while keeping the first semiconductor switch (Q1a) 10 on. Thus, a high frequency current of about 20 kHz to 60 kHz can be supplied to the second heating coil 7. The high frequency magnetic field generated from the second heating coil 7 by the high frequency current supplied in this way is supplied to a load such as a pan.

Thus, an eddy current is generated on the surface of the load such as the pan by the high frequency magnetic field supplied to the load such as the pan, and the load such as the pan is induction-heated by the eddy current and the high frequency resistance of the load such as the pan itself to generate heat. To.

Next, a second single heating mode for supplying high-frequency power to the first heating coil 6 will be described with reference to FIG. 20B.

In order to supply high-frequency power to the first heating coil 6 in the second single heating mode, the control unit 13 always keeps the third semiconductor switch (Q1c) 12 in a conductive state, and the first semiconductor switch (Q1a). 10 and the second semiconductor switch (Q1b) 11 are controlled to be on / off (on / off). When the second semiconductor switch (Q1b) 11 is turned on in the section A shown in FIG. 20B, the control unit 13 makes the smoothing capacitor 5 → the first resonant capacitor 8 → the first heating coil 6 → the second In the path from the semiconductor switch (Q1b) 11 to the third semiconductor switch (Q1c) 12, electric power is supplied to the first heating coil 6.

In the section A of FIG. 20B, the control unit 13 is in a non-conduction state only in the second semiconductor switch (Q1b) 11 during the conduction time (Tb) in which the current value detected by the input current detection unit 3 indicates a predetermined current value. (End of section A). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the first semiconductor switch (Q1a) 10 into a conductive state. As a result, electric power is supplied to the first heating coil 6 in the path of the first resonance capacitor 8 → the first semiconductor switch (Q1a) → the first heating coil 6. Thereafter, the control unit 13 sets the first semiconductor switch (Q1a) 10 in a non-conduction state during a conduction time (Ta) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (section B). End).

After that, the control unit 13 sets the second semiconductor switch (Q1b) 11 in the conductive state after a predetermined transition time (section Y) has elapsed (section A). The operation in the section B is continued through the transition time (X or Y). As described above, in the second single heating mode, the control unit 13 always keeps the third semiconductor switch (Q1c) 12 in the conductive state, and the first semiconductor switch (Q1a) 10 and the second semiconductor switch. By alternately turning on the switch (Q1b) 11, a high frequency current of about 20 kHz to 60 kHz can be supplied to the first heating coil 6. The high frequency magnetic field generated from the heating coil by the supplied high frequency current is supplied to a load such as a pan.

FIG. 21 is a waveform diagram showing the operation in the alternate heating mode in the induction heating apparatus of the third embodiment. The alternate heating mode is an operation when heating a plurality of loads by alternately using the first single heating mode shown in FIG. 20A and the second single heating mode shown in FIG. 20B. In FIG. 21, (a) to (c) are gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is a current waveform of the second heating coil 7, and ( e) is a current waveform of the first heating coil 6. In the alternate heating mode in the induction heating apparatus of the third embodiment, the operation time of the first single heating mode is T2, and the operation time of the second single heating mode is T1. Therefore, in the third embodiment, the operation time T1 and the operation time T2 are each set to a very short time within 1 second, and one cycle (T1 + T2) of the alternate heating mode is set within 2 seconds. .

Note that the switching operation between the first single heating mode and the second single heating mode in the alternate heating mode of the induction heating device of the third embodiment is the same as the control described with reference to FIG. 10 in the second embodiment. The same control is performed, and a highly efficient switching operation is performed in a short time.

As shown in FIG. 21, in the alternate heating mode, the first single heating mode and the second single heating mode are alternately operated in a short period periodically without impairing the heating distribution for each load. It becomes possible to heat the load simultaneously. In particular, in the induction heating device of the third embodiment, by reducing the switching time between the first single heating mode and the second single heating mode to 2 seconds or less, without reducing the average power, Uneven heating for each load can be reduced.

FIG. 22 is a diagram showing the relationship between the conduction time of the semiconductor switch and the resonance voltage generated in the resonance capacitor depending on the material of the load. A resonance circuit composed of a first heating coil 6 and a first resonance capacitor 8 magnetically coupled to a load, or a resonance circuit composed of a second heating coil 7 and a second resonance capacitor 9, The resonance frequency changes depending on the material.

When there is no load, the inductance is the largest and the resonance frequency is low. On the other hand, when a load is disposed in the vicinity of the heating coil and the load is magnetically coupled to the heating coil, the inductance decreases and the resonance frequency increases.

When the load is arranged in the vicinity of the heating coil, the inductance decreases in the load 25B such as non-magnetic stainless steel compared to the load 25A such as iron or magnetic stainless steel, so that the resonance frequency increases. Moreover, in the load which shows the characteristic between magnetic stainless steel and nonmagnetic stainless steel, the resonance frequency is between both.

Therefore, the control unit 13 can determine the type of load by detecting a resonance voltage generated at a predetermined operating frequency and conduction time. A load 25B having a low inductance and an operating frequency close to the resonance frequency has a high resonance voltage, and a load 25A having a characteristic in which the inductance is high and the operating frequency is away from the resonance frequency has a low resonance voltage. Further, in the case of no load, the resonance voltage decreases in the order of load 25B, load 25A, and no load. For this reason, it is possible to determine the material of the load and the presence or absence of the load by detecting the resonance voltage generated at a predetermined operating frequency and conduction time.

In the configuration of the third embodiment, if the operating frequency is constant in order to prevent the interference sound with the adjacent load, as shown in FIG. 23, there is a large difference in the input power generated in the conduction time depending on the material of the load. Occurs. For this reason, depending on the load, the input power cannot be reduced sufficiently, and the control width of the power control must be increased, which may result in a user-friendly heating device.

Therefore, in the case of a load 25A composed of a magnetic material, the inductance is high and the operating frequency is sufficiently separated from the resonance frequency, for example, the first heating coil 6 and the second heating coil 7 are connected in parallel. The operation is performed in the simultaneous heating mode (see FIG. 19). On the other hand, in the case of a load 25B made of a non-magnetic material, the inductance is low, the operating frequency is close to the common frequency, and the input power easily enters, for example, the first heating coil 6 and the second heating coil. The coils 7 are operated in an alternate heating mode (see FIGS. 20A and 20B) in which the coils 7 are connected separately. If the load 25B is also activated in the simultaneous heating mode as in the case of the load 25A, the resonance frequency is close to the operating frequency, so that input power is easily input. Therefore, as shown by the arrows in FIG. 23, in the case of the load 25B, the circuit configuration is changed to the alternate heating mode so that the circuit impedance is increased to prevent input power from entering.

In the alternate heating mode, the number of heating coils connected in parallel is halved compared to the simultaneous heating mode, so the impedance of the heating coil connected to the semiconductor switch is doubled, and as a result, the current to the heating coil And the input power can be reduced.

As described above, in the induction heating device of the third embodiment, in the induction heating device configured to heat the same load using a plurality of heating coils, the load is induction heated to three semiconductor switches connected in series. In the case of a load made of a load material having a large equivalent resistance value by connecting a plurality of resonance circuits composed of a heating coil and a resonance capacitor, the second semiconductor switch is always turned on, and the first and third semiconductor switches Are operated alternately in a simultaneous heating mode in which electric power is supplied simultaneously to the first heating coil and the second heating coil (see FIG. 19).

On the other hand, in the case of the load 25B made of a material having a small equivalent resistance, the first semiconductor switch is always turned on, the second and third semiconductor switches are turned on alternately, and high frequency power is supplied to the second heating coil. The operation of the first single heating mode to be supplied, the second semiconductor switch is always turned on, the first and second semiconductor switches are turned on alternately, and high frequency power is supplied to the first heating coil. The operation in the single heating mode is performed in the alternate heating mode that is alternately repeated in a short cycle (see FIGS. 20A and 20B).

In the induction heating device of the third embodiment, since the heating control is performed as described above, it is possible to give a predetermined input power to the load at a constant frequency even if the type of the load is changed, and there is no interference sound. An induction heating apparatus having excellent controllability can be realized.

(Embodiment 4)
An induction heating apparatus that is an induction heating cooker according to a fourth embodiment of the present disclosure will be described with reference to the drawings. In the description of the fourth embodiment, elements having substantially the same functions and configurations as those of the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted.

The configuration of the induction heating device of the fourth embodiment has the same configuration as the induction heating device of the first to third embodiments, and the heating operation control method for the heating coil is different. The induction heating apparatus of the fourth embodiment has a mode for heating a plurality of heating coils in the simultaneous heating mode, and this simultaneous heating mode is the simultaneous heating described in the above-described third embodiment with reference to FIG. It is the same operation as the mode. Further, the induction heating apparatus of the fourth embodiment has a step-down simultaneous heating mode described later in addition to the simultaneous heating mode.

Next, the operation of the induction heating apparatus according to the fourth embodiment will be described. FIG. 24 is a waveform diagram showing an operating state of the step-down simultaneous heating mode in the induction heating apparatus of the fourth embodiment. 24, (a) to (c) are the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is the current waveform of the first heating coil 6, and ( e) is a current waveform of the second heating coil 7.

《Step-down simultaneous heating mode》
In the step-down simultaneous heating mode, the control unit 13 supplies high-frequency power to the first heating coil 6 and the second heating coil 7 simultaneously, so that the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b ) 11 and the third semiconductor switch (Q1c) 12 are controlled to be in a conductive state / non-conductive state (on state / off state).

For example, in the section B shown in FIG. 24, the control unit 13 makes the first semiconductor switch (Q1a) 10 non-conductive (off state), the second semiconductor switch (Q1b) 11 conductive (on state), When the third semiconductor switch (Q1c) 12 is controlled to be in a non-conductive state (off state), the smoothing capacitor 5 → the first resonance capacitor 8 → the first heating coil 6 → the second semiconductor switch (Q1b) 11 → Electric power is simultaneously supplied to the first heating coil 6 and the second heating coil 7 in the path from the second heating coil 7 to the second resonance capacitor 9.

In this case, the series circuit of the first heating coil 6 and the first resonance capacitor 8 and the series circuit of the second heating coil 7 and the second resonance capacitor 9 are connected in series to the smoothing capacitor 5. . For this reason, a divided voltage is applied to each series circuit. In particular, when each series circuit has substantially the same circuit constant, approximately a half voltage is applied.

Next, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a non-conduction state during the conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section B). . After a lapse of a predetermined transition time (section Y) from the end of section B, the control unit 13 sets the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 to the conductive state (section A). As a result, power is supplied to the first heating coil 6 in the path of the first resonance capacitor 8 → the first semiconductor switch (Q 1 a) 10 → the first heating coil 6, and the second resonance capacitor 9. In the path of the second heating coil 7 → the third semiconductor switch (Q1c) 12, an operation for supplying electric power to the second heating coil 7 occurs simultaneously.

The control unit 13 turns off the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 during the conduction time (section A) in which the current value detected by the input current detection unit 3 indicates a predetermined current. A conduction state is set (end of section A). After the end of the section A, the control unit 13 makes the second semiconductor switch (Q1b) 11 conductive again after a predetermined transition time (section X) has elapsed (section B).

As described above, in the step-down simultaneous heating mode, the control unit 13 includes the second semiconductor switch (Q1b) 11, the set of the first semiconductor switch (Q1a) 10, and the third semiconductor switch (Q1c) 12. By alternately controlling the conductive state / non-conductive state, a high-frequency current of about 20 kHz to 60 kHz can be simultaneously supplied to both the first heating coil 6 and the second heating coil 7. As a result, in the induction heating apparatus of the fourth embodiment, a desired high-frequency magnetic field generated from the heating coil supplied with the high-frequency current is supplied to a load such as a pan.

As described in the third embodiment, in the induction heating apparatus of the fourth embodiment, the control unit 13 is connected to the heating coil by detecting the resonance voltage generated at a predetermined operating frequency and conduction time. It has a configuration capable of determining the type of load to be combined and the presence or absence of the load.

In the configuration of the fourth embodiment, if the operating frequency is constant in order to prevent the interference sound with the adjacent load, as in the third embodiment (see FIG. 23), the input power generated during the conduction time depending on the material of the load. A big difference occurs. For this reason, depending on the load, the input power cannot be sufficiently reduced, and there are cases where the heating device is inconvenient such that the control width of power control is increased.

Therefore, in the case of the load 25A having a characteristic in which the inductance is high and the operating frequency is sufficiently away from the resonance frequency, the simultaneous heating mode in which the first heating coil 6 and the second heating coil 7 are connected in parallel is performed. Make it work. On the other hand, in the case of the load 25B having a characteristic that the inductance is low and the operating frequency is close to the common frequency and the input power easily enters, the voltage applied to each of the first heating coil 6 and the second heating coil 7 decreases. Operate in the step-down simultaneous heating mode (1/2 under the same conditions). By operating in this step-down simultaneous heating mode, the input power can be sufficiently reduced. If the voltage applied to each heating coil is halved, the electric power is ¼ under the same operating conditions (operating frequency and conduction time).

Note that the induction heating device of the fourth embodiment may have a configuration having the alternate heating mode (FIGS. 20A and 20B) described in the third embodiment. Thus, in the configuration having the simultaneous heating mode, the step-down simultaneous heating mode, and the alternate heating mode, when the load is induction-heated under the same operating conditions (operating frequency and conduction time), the magnitude of the input power is the simultaneous heating. In many cases, the order decreases in the order of mode, alternate heating mode, and step-down simultaneous heating mode. For this reason, in the configuration having the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode, three types of heating modes are selected according to conditions such as the material of the load, the simultaneous heating mode → the alternate heating mode and the step-down simultaneous heating mode. It is also possible to select the heating mode appropriate for the load by switching in order.

As described above, in the induction heating device according to the fourth embodiment, in the induction heating device configured to heat the same load using a plurality of heating coils, the load is induction heated to three semiconductor switches connected in series. In the case of a load made of a load material having a large equivalent resistance value by connecting a plurality of resonance circuits composed of a heating coil and a resonance capacitor, the second semiconductor switch is always turned on, and the first and third semiconductor switches Are alternately conducted to operate in a simultaneous heating mode in which power is simultaneously supplied to the first heating coil and the second heating coil.

On the other hand, in the case of a load made of a material having a small equivalent resistance, the second semiconductor switch and the first semiconductor switch and the third semiconductor switch group are alternately conducted, and the first heating coil High-frequency power is simultaneously supplied to the second heating coil, and the operation is performed in the step-down simultaneous heating mode that can reduce the voltage applied to each heating coil.

In the induction heating apparatus of the fourth embodiment, since the heating control is performed as described above, it is possible to give a predetermined input power to the load at a constant frequency even if the type of the load changes, and there is no interference sound. An excellent controllable induction heating apparatus can be realized.

(Embodiment 5)
The induction heating apparatus which is the induction heating cooking appliance of Embodiment 5 which concerns on this indication is demonstrated, referring drawings. In the description of the fifth embodiment, elements having substantially the same functions and configurations as those of the first to fourth embodiments are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 25 is a diagram illustrating a circuit configuration in the induction heating cooker according to the fifth embodiment of the present disclosure. The difference between the induction heating device of the fifth embodiment and the induction heating device of the third and fourth embodiments is that the first heating coil 6 is composed of a plurality of first heating coil elements 6a, 6b, 6c. It is comprised by the heating coil group, and the 2nd heating coil 7 is the point comprised by the heating coil group of several 2nd heating coil elements 7a, 7b, 7c. Each of the heating coil elements 6a, 6b, 6c includes a first resonance capacitor element 8a, 8b, 8c constituting the first resonance capacitor 8 and a first opening / closing part constituting the first opening / closing part 20. Each of the partial elements 20a, 20b, and 20c is connected in series. Similarly, in each of the heating coil elements 7a, 7b, 7c, the second resonance capacitor elements 9a, 9b, 9c constituting the second resonance capacitor 9 and the second opening / closing part 21 constituting the second resonance capacitor element 9 are provided. Each of the opening / closing part elements 21a, 21b, and 21c is connected in series. Furthermore, in the induction heating apparatus of the fifth embodiment, a load detection unit 22 that detects the presence of a load in the vicinity of the first heating coil elements 6a, 6b, 6c and the second heating coil elements 7a, 7b, 7c. The provided point is different from the induction heating apparatus of the third embodiment and the fourth embodiment described above.

In addition, in the induction heating device of the fifth embodiment, the first heating coil 6 and the second heating coil 7 that are the heating coil group are described as an example configured by three heating coil elements, Each heating coil only needs to be composed of two or more heating coil elements, and the number is not particularly limited in the present disclosure.

The first opening / closing part elements 20a to 20c constituting the first opening / closing part 20 and the second opening / closing part elements 21a to 21c constituting the second opening / closing part 21 are heating coils such as electromagnetic relays and semiconductor switches. Any configuration may be used as long as the element can be brought into and out of contact with the power supply circuit. In the present disclosure, the configuration of the opening / closing portion element is not particularly limited.

Next, the operation of the induction heating device according to the fifth embodiment of the present disclosure will be described.
Upon receiving an operation start command from an operation unit (not shown), the control unit 13 first closes the first opening / closing unit elements 20a to 20c and the second opening / closing unit elements 21a to 21c to perform the heating operation. A predetermined high-frequency current smaller than the high-frequency current is passed through each heating coil, and the load detection unit 22 detects whether or not a load exists in the vicinity of each heating coil element.

In this detection operation, the load detection unit 22 detects a control value such as a conduction time and an operation frequency from the control unit 13, a voltage value of each resonance capacitor, a current value of each heating coil element, and an input current detection unit 3. The presence / absence of a load, the material of the load, etc. are determined from the measured current value.

For the heating coil element that the load detection unit 22 has determined that there is no load in the vicinity, the control unit 13 opens the open / close unit element connected to the heating coil element to open the first semiconductor switch 10 or the third The connection state with the semiconductor switch 12 is released.

On the other hand, the control unit 13 closes the open / close unit element connected to the heating coil element with respect to the heating coil element that the load detection unit 22 has determined that there is a load in the vicinity, and the first semiconductor switch 10 or The third semiconductor switch 12 is connected. The control unit 13 selects an appropriate heating mode from the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode according to the number of heating coil elements to which the opening / closing unit elements are connected. Operate the semiconductor switch. Since the number of connected heating coil elements depends on the shape of the load, the heating operation is performed using more heating coil elements in the case of a load having a large shape. As a result, in the induction heating apparatus of the fifth embodiment, a good heating distribution can be obtained and the cooking performance can be improved.

FIG. 26 is a diagram showing characteristics of input power in each heating mode with respect to conduction time. As shown in FIG. 26, in the induction heating apparatus of the fifth embodiment, the simultaneous heating mode is operated when a load of the same material is heated by two heating coil elements.

On the other hand, when heating a large load made of substantially the same material, for example, when heating with four heating coil elements, when the simultaneous heating mode is operated, the heating coil element combined with the load connected in parallel Is approximately ½ compared to the case of heating with two heating coil elements. Therefore, in the case of heating with four heating coil elements, the result is that the input power increases in the same conduction time as compared with the case of heating with two heating coil elements.

Therefore, in the case of heating with four heating coil elements, the control unit 13 can not reduce the power to the required input power, or the resolution is deteriorated, and appropriate power control is performed under a condition where the operating frequency is constant. The problem that cannot be done arises. Therefore, for example, when heating is performed with four heating coil elements, the number of heating coil elements connected in parallel with the load is reduced by using the alternate heating mode when operating simultaneously. As described above, in the induction heating apparatus of the fifth embodiment, the operation is performed so as not to reduce the impedance of the heating coil in parallel with the load according to the number of connected heating coil elements to which high-frequency power is supplied. The input power characteristics are not changed.

Note that it is possible to change the characteristics of the input power with respect to the conduction time by using the step-down simultaneous heating mode according to the number of connected heating coil elements. In that case, it is desirable to execute the optimum heating mode by sequentially selecting the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode according to the load material and the number of connected heating coil elements.

As described above, according to the induction heating device according to the fifth embodiment of the present disclosure, according to the number of connected heating coil elements that form the first heating coil and the second heating coil to which high-frequency power is supplied. Even if the number of heating coil elements to be driven changes by selecting the heating mode from among the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode, the predetermined input power at a constant frequency Can be applied to the load, and there is no interference sound, and an induction heating device having excellent controllability can be realized.

(Embodiment 6)
The induction heating apparatus which is the induction heating cooking appliance of Embodiment 6 which concerns on this indication is demonstrated, referring drawings. In the description of the sixth embodiment, elements having substantially the same functions and configurations as those of the first to fifth embodiments are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 27 is a diagram illustrating a circuit configuration of the induction heating device according to the sixth embodiment of the present disclosure. Similar to the induction heating devices of the first to fifth embodiments, the induction heating device of the sixth embodiment includes an AC power source 1, a rectifier circuit 2, a smoothing circuit 30 including a choke coil 4 and a smoothing capacitor 5, and A series connection body of a first semiconductor switch 10, a second semiconductor switch 11, and a third semiconductor switch 12 connected in parallel to the smoothing capacitor 5 is provided. Further, the induction heating device of the sixth embodiment is similar to the induction heating device of the fifth embodiment shown in FIG. 25, and the first heating coil 6 and the first heating coil 6 connected in parallel to the first semiconductor switch 10. The series connection body of the resonance capacitor 8 and the first opening / closing part 20, and the second heating coil 7, the second resonance capacitor 9, and the second opening / closing part 21 connected in parallel to the third semiconductor switch 12. And a connecting body.

In the induction heating apparatus of the sixth embodiment, the first heating coil 6 is composed of a plurality of heating coil groups of first heating coil elements 6a, 6b, 6c, 6d, and the second heating coil 7 A plurality of second heating coil elements 7a, 7b, 7c, and 7d are configured as a heating coil group. Each of the first heating coil elements 6a, 6b, 6c, and 6d includes a first resonant capacitor element 8a, 8b, 8c, and 8d that constitutes the first resonant capacitor 8, and a first opening / closing part 20. The first opening / closing section elements 20a, 20b, 20c, and 20d constituting the are respectively connected in series. Similarly, each of the second heating coil elements 7a, 7b, 7c, 7d includes a second resonant capacitor element 9a, 9b, 9c, 9d constituting the second resonant capacitor 9, and a second opening / closing part. 2nd opening / closing part element 21a, 21b, 21c, 21d which comprises 21 is respectively connected in series.

Further, the induction heating apparatus of the sixth embodiment is configured to detect a current flowing from the AC power supply 1 to the rectifier circuit 2 and a load detection unit 22 that detects whether there is a load that can be heated in the vicinity of each heating coil element. The input current detection unit 3 that is detected by a transformer or the like, and the first to third semiconductor switches 10, 11, and 12 are controlled so that the detection value of the input current detection unit 3 becomes a set value, and the load detection unit 22 And a control unit 13 that controls the open / close state of the first open / close unit 20 and the second open / close unit 21 based on the detected value.

In the induction heating apparatus of the sixth embodiment, the first heating coil 6 and the second heating coil 7 which are heating coil groups are described as examples each including four heating coil elements ( 27), each heating coil may be composed of two or more heating coil elements, and the number is not particularly limited in the present disclosure.

The target value of the control unit 13 includes the current and voltage of the heating coil in addition to the input current, and is not particularly limited in the configuration of the sixth embodiment.

Also in the induction heating apparatus of the sixth embodiment, the first to third semiconductor switches 10, 11, and 12 are connected in parallel to power semiconductors (semiconductor switch elements) such as IGBTs and MOSFETs and the respective power semiconductors in the reverse direction. Made up of diodes. In addition, a snubber capacitor may be connected in parallel between the collectors and emitters of the first to third semiconductor switches 10, 11, and 12 in order to suppress a rapid voltage rise when shifting from the on state to the off state. . In the sixth embodiment, a snubber capacitor is connected in parallel between the collector and emitter of the first semiconductor switch 10 and the third semiconductor switch 12.

28 and 29 are plan views showing a configuration in which a plurality of heating coil elements constituting the heating coil group are arranged in a matrix. In the configuration shown in FIG. 28, a plurality of heating coil elements are arranged vertically and horizontally in the region below the top plate 15 on which the load is placed, except for the operation / display unit 16 provided on the user side. Arranged in a shape.

In the induction heating apparatus of the sixth embodiment configured as described above, as shown in FIG. 28, for example, when a small load 14a having a round pan bottom is placed on the top plate 15, two heating coil elements The first heating coil 6 is formed by 6b and 6c, the second heating coil 7 is formed by the two heating coil elements 7b and 7c, and only the heating coil elements 6b, 6c, 7b and 7c are provided. In this configuration, a high-frequency current is supplied. Further, for example, when a large load 14b is placed with a square pan bottom, a high-frequency current is supplied to more corresponding heating coil elements.

As described above, by selecting the heating coil element to be driven according to the shape of the load, the heating distribution is good with respect to the load, and efficient heating can be performed. As for the planar shape of the heating coil element, it is desirable that the circular diameter of the planar shape be about φ30 to φ120 mm in consideration of heating a load having a pan bottom diameter of about φ160 to φ240 mm with a plurality of heating coil elements. . However, in the present disclosure, the planar shape of the heating coil element is not particularly limited to the above shape.

Further, in the configuration in which a plurality of heating coil elements are arranged in a matrix in the lower region of the top plate 15, in order to arrange the heating coil elements as densely as possible, they are arranged so as to form staggered lattices. . That is, in the arrangement shown in FIG. 29, a plurality of heating coil elements are arranged on a vertical line extending from the user's near side (operation / display unit side) to the back side, and adjacent vertical line heating coil elements are arranged. Are staggered. In this arrangement, the number of heating coil elements is increased, but the gap between the heating coil elements is reduced. Therefore, it is possible to obtain a better heating distribution than the arrangement shown in FIG. it can.

In addition, it is desirable that the inductance value of each heating coil element is substantially the same value and the shape is also the same so that the electric energy is not biased.

As shown in FIG. 28, when the load 14a and the load 14b having different pot bottom shapes are placed on the top plate 15, for example, in the case of the load 14a, four heating coil elements are driven, and the load 14b In this case, it is desirable to drive eight heating coil elements.

When a large number of heating coil elements are combined into a small number of heating coils as a single heating group, parallel connection increases in one heating coil and impedance decreases. As a result, it becomes easier for current to flow to one heating coil, and the generated power increases with respect to the conduction time of each semiconductor switch. As a result, problems such as the inability to reduce the input power or increase in the element loss of the semiconductor switch occur.

In order to improve the power control performance, it is conceivable to increase the operating frequency when heating the load 14b heated by many heating coil elements so that the input power can be reduced. However, when the load 14a heated by a small number of heating coil elements and the load 14b heated by a large number of heating coil elements are heated at the same time, a frequency difference occurs between the respective operating frequencies, and interference noise is generated. Will occur.

Therefore, in the control unit 13 in the induction heating apparatus of the sixth embodiment, the heating mode is changed according to the number of connected heating coil elements used when heating the load. That is, the control unit 13 controls the conduction states of the first semiconductor switch 10, the second semiconductor switch 11, and the third semiconductor switch 12 in a state adapted to each heating mode. Thus, the voltage applied to the first heating coil 6 and the second heating coil 7 by the control unit 13 changing the conduction state of each semiconductor switch 10, 11, 12 according to the number of heating coils to be connected. Can be changed.

As a result, even if the number of heating coil elements to be used changes, power control can be performed with the operating frequency kept constant.

Next, the operation in the induction heating apparatus of the sixth embodiment will be described.
When the heating start signal is input from the operation / display unit 16, the control unit 13 detects whether there is a load on the top plate 15 by the load detection unit 22.

In this case, the load detection unit 22 operates the semiconductor switch to determine the presence / absence of a load, the type of load, the number of loads, and the like for each heating coil element, and the current, voltage, and input generated in the heating coil element. The detection value of the current detection unit 3 is used.

FIG. 30 shows an example of a load detection method, and is a diagram showing the relationship between the conduction time of the semiconductor switch and the resonance voltage generated in the resonance capacitor depending on the material of the load. The resonance frequency of the resonance circuit composed of the heating coil element magnetically coupled to the load and the resonance capacitor varies depending on the material of the load. In the absence of a load, the inductance is the largest and the resonance frequency is low.

On the other hand, when a load is disposed in the vicinity of the heating coil and the load is magnetically coupled to the heating coil, the inductance decreases and the resonance frequency increases. When the load is arranged in the vicinity of the heating coil, the inductance decreases in the load 14b such as non-magnetic stainless steel compared to the load 14a such as magnetic stainless steel, so that the resonance frequency increases.

Therefore, the control unit 13 can determine the type of load by detecting the resonant voltage generated at a predetermined operating frequency and conduction time. The load 14b whose operating frequency is close to the resonant frequency has a high resonant voltage, and the load 14a whose operating frequency is low away from the resonant frequency has a low resonant voltage. Further, in the case of no load, the detected value of the resonance voltage decreases in the order of the load 14b, the load 14a, and no load. For this reason, it is possible to determine the material of the load by detecting the resonance voltage generated at a predetermined operating frequency and conduction time.

In the induction heating device according to the sixth embodiment, among the heating coil elements that have detected the load, the heating coil elements that are mounted and assembled substantially simultaneously are determined to have the same load mounted, and the heating that has detected the load is detected. The coil element is connected to the first semiconductor switch 10 and the third semiconductor switch 12, respectively, with the corresponding first opening / closing element and second opening / closing element being closed. And the control part 13 performs operation | movement of simultaneous heating mode or alternate heating mode according to the number of connection of a heating coil element.

FIG. 31 is a waveform diagram showing an operation state of the simultaneous heating mode in the induction heating apparatus of the sixth embodiment. In FIG. 31, (a) to (c) are gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, and (d) is a current waveform of the heating coil element in the first heating coil 6. And (e) is a current waveform of the heating coil element in the second heating coil 7.

In the simultaneous heating mode, the control unit 13 supplies high-frequency power simultaneously to the first heating coil 6 having a plurality of heating coil elements and the second heating coil 7 having a plurality of heating coil elements. The second semiconductor switch (Q1b) 11 is always in a conducting state, and the conduction state / non-conduction state (on state / off state) of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 is controlled. To do.

In the section A shown in FIG. 31, when the first semiconductor switch (Q1a) 10 is turned on (on state) and the third semiconductor switch (Q1c) 12 is turned off (off state), the smoothing capacitor 5 → first semiconductor switch 10 → second semiconductor switch (Q1b) 11 → second heating coil 7 (corresponding second heating coil element) → second resonance capacitor 9 (corresponding second resonance capacitor) Element) → the operation of supplying electric power to the second heating coil 7 (corresponding second heating coil element) in the path of the second opening / closing part 21 (corresponding second opening / closing element), Resonance capacitor 8 (corresponding first resonance capacitor element) → first switch 20 (corresponding first switch element) → first semiconductor switch (Q1a) 10 → first heating coil 6 (corresponding First The first heating coil 6 in the path of the heating coil element) (operation first heating power to the coil elements) corresponding is supplied occur simultaneously.

The control unit 13 causes only the first semiconductor switch (Q1a) 10 to be in a non-conduction state during the conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section A). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, the smoothing capacitor 5 → the first switching unit 20 (corresponding first switching unit element) → the first resonance capacitor 8 (corresponding first resonance capacitor element) → the first heating coil 6 (corresponding) Power is supplied to the first heating coil 6 (corresponding first heating coil element) in the path of the first heating coil element) → second semiconductor switch (Q1b) 11 → third semiconductor switch (Q1c) 12. Operation, second resonance capacitor 9 (corresponding second resonance capacitor element) → second heating coil 7 (corresponding second heating coil element) → third semiconductor switch (Q1c) 12 → second The operation of supplying power to the second heating coil 7 (corresponding second heating coil element) simultaneously occurs in the path of the two opening / closing parts 21 (corresponding second opening / closing element).

The control unit 13 sets only the third semiconductor switch (Q1c) 12 in a non-conductive state during a conduction time (section B) in which the current value detected by the input current detection unit 3 becomes a predetermined current value. After the end of the section B, the control unit 13 makes the first semiconductor switch (Q1c) 10 conductive again after a predetermined transition time (section Y) has elapsed.

As described above, in the simultaneous heating mode, the control unit 13 keeps the second semiconductor switch (Q1b) 11 in the conductive state, and the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c). By alternately bringing 12 into a conductive state, a high-frequency current of about 20 kHz to 60 kHz is simultaneously supplied to the corresponding heating coil elements in the first heating coil 6 and the second heating coil 7, and the corresponding high-frequency current is applied. A high frequency magnetic field generated from the heating coil element is supplied to a load such as a pan.

Further, the induction heating device of the sixth embodiment is configured to be able to execute the alternate heating mode.

FIG. 32A is a waveform diagram showing a first single heating mode in which high-frequency power is supplied to the corresponding second heating coil element in the second heating coil 7. 32A, (a) to (c) show the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, and (d) shows the current waveform of the second heating coil 7. In FIG.

In the first single heating mode shown in FIG. 32A, the control unit 13 supplies the first semiconductor switch (Q1a) 10 to supply high-frequency power to the corresponding second heating coil element in the second heating coil 7. The second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 are controlled to be in a conduction state / non-conduction state (on state / off state). In the section A shown in FIG. 32A, the control unit 13 sets the second semiconductor switch (Q1b) 11 to the conductive state (ON state) and sets the third semiconductor switch (Q1c) 12 to the non-conductive state (OFF state). . As a result, the smoothing capacitor 5 → the first semiconductor switch (Q1a) 10 → the second semiconductor switch (Q1b) 11 → the second heating coil 7 (corresponding second heating coil element) → the second resonance capacitor 9 Power is supplied to the second heating coil 7 (corresponding second heating coil element) in the path of (corresponding second resonance capacitor element) → second switching part 21 (corresponding second switching element). Is done.

The control unit 13 sets only the second semiconductor switch (Q1b) 11 in the non-conduction state during the conduction time (Tb) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section A). ). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the third semiconductor switch (Q1c) 12 into a conductive state. As a result, the second resonance capacitor 9 (corresponding second resonance capacitor element) → second heating coil 7 (corresponding second heating coil element) → third semiconductor switch 12 (Q1c) 12 → second Electric power is supplied to the second heating coil 7 (corresponding second heating coil element) in the path of the opening / closing part 21 (corresponding second opening / closing element). Thereafter, the control unit 13 sets the third semiconductor switch (Q1c) 12 in a non-conduction state during a conduction time (Tc) in which the current value detected by the input current detection unit 3 indicates a predetermined current value (section B). End).

After that, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state after a predetermined transition time (section Y) has elapsed (section A). As described above, the control unit 13 continues the operations in the sections A and B alternately through the transition time (X or Y).

As described above, the control unit 13 alternately turns on the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 while keeping the first semiconductor switch (Q1a) 10 on. Thus, a high-frequency current of about 20 kHz to 60 kHz is supplied to the corresponding second heating coil element in the second heating coil 7, and the corresponding second heating coil in the second heating coil 7 is supplied by this high-frequency current. A high-frequency magnetic field generated from the element is supplied to a load such as a pan.

Thus, an eddy current is generated on the surface of the load such as the pan by the high frequency magnetic field supplied to the load such as the pan, and the load such as the pan is induction-heated by the eddy current and the high frequency resistance of the load such as the pan itself to generate heat. To.

Next, the second single heating mode for supplying high-frequency power to the corresponding heating coil element in the first heating coil 6 will be described with reference to FIG. 32B.

In the second single heating mode, the controller 13 supplies the high-frequency power to the first heating coil element in the first heating coil 6 so that the third semiconductor switch (Q1c) 12 is always in a conductive state. The conduction state / non-conduction state (on state / off state) of the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 are controlled. When the second semiconductor switch (Q1b) 11 is turned on in the section A shown in FIG. 32B, the control unit 13 makes the smoothing capacitor 5 → the first switching unit 20 (corresponding first switching unit element) → First resonance capacitor 8 (corresponding first resonance capacitor element) → first heating coil 6 (corresponding first heating coil element) → second semiconductor switch (Q1b) 11 → third semiconductor switch ( Q1c) Electric power is supplied to the first heating coil 6 (corresponding first heating coil element) in the route of 12.

In the section A of FIG. 32B, the control unit 13 makes only the second semiconductor switch (Q1b) 11 non-conductive during the conduction time (Tb) in which the current value detected by the input current detection unit 3 indicates a predetermined current value. (End of section A). After a lapse of a predetermined transition time (section X) from the end of section A, the control unit 13 brings the first semiconductor switch (Q1a) 10 into a conductive state. As a result, the first resonant capacitor 8 (corresponding first resonant capacitor element) → the first opening / closing part 20 (corresponding first opening / closing part element) → first semiconductor switch (Q1a) → first heating In the path of the coil 6 (corresponding first heating coil element), electric power is supplied to the first heating coil 6 (corresponding first heating coil element). Thereafter, the control unit 13 sets the first semiconductor switch (Q1a) 10 in a non-conduction state during the conduction time (Ta) indicating the predetermined current value detected by the input current detection unit 3 (end of section B). .

Then, after a predetermined transition time (section Y) has elapsed, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a conductive state (section A). As described above, the control unit 13 continues to operate the operations in the section A and the section B alternately through the transition time (X or Y).

As described above, the control unit 13 alternately turns on the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 while keeping the third semiconductor switch (Q1c) 12 in a conductive state. Thus, a high-frequency current of about 20 kHz to 60 kHz can be supplied to the corresponding first heating coil element in the first heating coil 6, and the first heating is performed by the supplied high-frequency current. A high-frequency magnetic field generated from the corresponding second heating coil element in the coil is supplied to a load such as a pan.

FIG. 33 is a waveform diagram showing the operation in the alternate heating mode in the induction heating apparatus of the sixth embodiment. The alternating heating mode is an operation when heating a plurality of loads by alternately using the first single heating mode shown in FIG. 32A and the second single heating mode shown in FIG. 32B. 33, (a) to (c) are the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is the current waveform of the second heating coil 7, and ( e) is a current waveform of the first heating coil 6. In the alternate heating mode in the induction heating device of the sixth embodiment, the operation time of the first single heating mode is T2, and the operation time of the second single heating mode is T1. Therefore, in the sixth embodiment, the operation time T1 and the operation time T2 are each set to a very short cycle within 1 second, and one cycle (T1 + T2) of the alternate heating mode is set within 2 seconds. ing.

The switching operation between the first single heating mode and the second single heating mode in the alternate heating mode of the induction heating device of the sixth embodiment is the same as the control described with reference to FIG. 10 in the second embodiment. The same control is performed, and a highly efficient switching operation is performed in a short time.

As shown in FIG. 33, in the alternate heating mode, the first single heating mode and the second single heating mode are alternately operated in a short period periodically without impairing the heating distribution for each load. It becomes possible to heat the load simultaneously. In particular, in the induction heating device of the sixth embodiment, the switching time between the first single heating mode and the second single heating mode is shortened to approximately 2 seconds or less without reducing the average power. , Heating unevenness for each load can be reduced. In addition, even if the alternate heating mode is used in the induction heating device of the sixth embodiment, the user feels the uncomfortable feeling that the user feels when heating a plurality of loads alternately, which has been a problem in the conventional induction heating device. It will be a safe control.

In the induction heating apparatus of the sixth embodiment, in order to prevent the interference sound with the adjacent load, if the operating frequency is constant, as shown in FIG. 34, the conduction is made depending on the number of heating coil elements to which high-frequency power is supplied. There may be large differences in input power generated over time. For this reason, depending on the shape (size) of the load, the input power cannot be sufficiently reduced, and the usability may be deteriorated, for example, the control width of power control is increased.

Therefore, in the case of a load having a small number of connected heating coil elements and a large impedance, for example, the first load 14a (four heating coil elements), the first heating coil 6 and the second heating coil 6 The operation is performed in the simultaneous heating mode in which the coils 7 are connected in parallel. On the other hand, in the case of a large number of connected heating coil elements and a load with low impedance, for example, the second load 14b (eight heating coil elements), the number of heating coil elements is halved. It is operated in an alternate heating mode that is connected.

As a result, in the alternate heating mode, the number of heating coil elements connected in parallel is halved compared to the simultaneous heating mode, so the impedance of the heating coil connected to the semiconductor switch is doubled. As a result, the current to the heating coil can be suppressed, and the input power can be reduced.

As described above, in the induction heating apparatus according to the sixth embodiment configured to heat the same load using a plurality of heating coil elements, resonance occurs with the heating coil element that induction-heats the load to the three semiconductor switches connected in series. In the case of a load with a small number of connections of heating coil elements that increase impedance, the second semiconductor switch 11 is always turned on by connecting a plurality of resonance circuits composed of capacitors, and the first and third The semiconductor switches 10 and 12 are alternately turned on to operate in a simultaneous heating mode in which power is supplied to the first heating coil 6 and the second heating coil 7 simultaneously.

On the other hand, in the case of a load having a large number of connected heating coil elements with low impedance, the first semiconductor switch 10 is always turned on, and the second and third semiconductor switches 11 and 12 are turned on alternately. The operation of the first single heating mode for supplying high-frequency power to the heating coil 7 and the third semiconductor switch 12 are always turned on, the first and second semiconductor switches 10 and 11 are turned on alternately, The operation of the second single heating mode for supplying high-frequency power to one heating coil 6 is operated in an alternate heating mode that is alternately repeated at a constant interval for a short time. By supplying power to the first heating coil 6 and the second heating coil 7 in this way, even if the number of heating coil elements to be used changes, predetermined input power can be given to the load at a constant operating frequency. It is possible to realize an induction heating device having no interference noise and excellent controllability.

(Embodiment 7)
An induction heating apparatus that is an induction heating cooker according to a seventh embodiment of the present disclosure will be described with reference to the drawings. In the description of the seventh embodiment, elements having substantially the same functions and configurations as those of the first to sixth embodiments are denoted by the same reference numerals, and the description thereof is omitted.

The configuration of the induction heating device of the seventh embodiment is the same as the configuration of the induction heating device of the sixth embodiment shown in FIG. 27, and the control method of the heating operation for the heating coil is different. The induction heating apparatus of the seventh embodiment has a mode for heating a plurality of heating coils in the simultaneous heating mode. This simultaneous heating mode is the simultaneous heating described with reference to FIG. 31 in the aforementioned sixth embodiment. It is the same operation as the mode. Further, the induction heating apparatus of the seventh embodiment has a step-down simultaneous heating mode in addition to the simultaneous heating mode.

Next, the operation of the induction heating apparatus according to the seventh embodiment will be described. FIG. 35 is a waveform diagram showing an operation state in the step-down simultaneous heating mode in the seventh embodiment. 35, (a) to (c) are the gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) is the current waveform of the first heating coil 6, and ( e) is a current waveform of the second heating coil 7.

In the step-down simultaneous heating mode, the control unit 13 supplies high-frequency power simultaneously to the first heating coil 6 and the second heating coil 7 which are heating coil groups composed of a plurality of heating coil elements. The conduction state / non-conduction state (on state / off state) of the first semiconductor switch (Q1a) 10, the second semiconductor switch (Q1b) 11, and the third semiconductor switch (Q1c) 12 is controlled.

For example, in the section B shown in FIG. 35, the control unit 13 makes the first semiconductor switch (Q1a) 10 non-conductive (off state), the second semiconductor switch (Q1b) 11 conductive (on state), When the third semiconductor switch (Q1c) 12 is controlled to be in a non-conductive state (off state), the smoothing capacitor 5 → the first opening / closing part 20 (corresponding first opening / closing part element) → the first resonance capacitor 8 ( Corresponding first resonant capacitor element) → first heating coil 6 (corresponding first heating coil element) → second semiconductor switch (Q1b) 11 → second heating coil 7 (corresponding second heating) Coil element) → second resonance capacitor 9 (corresponding second resonance capacitor element) → first heating coil which is a heating coil group in the path of the second opening / closing part 21 (corresponding second opening / closing part element) 6 and At the same time power is supplied to the second heating coil 7.

In this case, the series circuit of the first heating coil 6 and the first resonance capacitor 8 and the series circuit of the second heating coil 7 and the second resonance capacitor 9 are connected in series to the smoothing capacitor 5. . For this reason, a divided voltage is applied to each series circuit. In particular, when each series circuit has substantially the same circuit constant, approximately a half voltage is applied.

Next, the control unit 13 sets the second semiconductor switch (Q1b) 11 in a non-conduction state during the conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value (end of section B). . After a lapse of a predetermined transition time (section Y) from the end of section B, the control unit 13 sets the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 to the conductive state (section A). As a result, the first resonant capacitor 8 (corresponding first resonant capacitor element) → the first switching unit 20 (corresponding first switching unit element) → the first semiconductor switch (Q1a) 10 → first In the path of the heating coil 6 (corresponding first heating coil element), power is supplied to the first heating coil 6 as a heating coil group, and the second resonance capacitor 9 (corresponding second resonance capacitor). Element) → second heating coil 7 (corresponding second heating coil element) → third semiconductor switch (Q1c) 12 → second opening / closing part 21 (corresponding second opening / closing part element) The operation of supplying power to the second heating coil 7 that is a coil group occurs simultaneously.

The control unit 13 puts the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 into a non-conduction state in a conduction time in which the current value detected by the input current detection unit 3 indicates a predetermined current value. To do. After the end of the section A, the control unit 13 sets the second semiconductor switch (Q1b) 11 in the conductive state again after a predetermined transition time (section X) has elapsed.

As described above, in the step-down simultaneous heating mode, the control unit 13 includes the second semiconductor switch (Q1b) 11, the set of the first semiconductor switch (Q1a) 10, and the third semiconductor switch (Q1c) 12. By alternately controlling the conduction state / non-conduction state, a high frequency current of about 20 kHz to 60 kHz is simultaneously supplied to both the first heating coil 6 and the second heating coil 7 which are the heating coil group. Can do. As a result, in the induction heating apparatus of the seventh embodiment, a desired high frequency magnetic field generated from the heating coil supplied with the high frequency current is supplied to a load such as a pan.

Note that the control unit 13 detects the resonance voltage generated at a predetermined operating frequency and conduction time with respect to the presence / absence and material of the load coupled to the heating coil in the same manner as in the above-described sixth embodiment. Presence / absence and / or type of load can be determined.

In the configuration of the seventh embodiment, assuming that the operating frequency is constant in order to prevent the interference sound with the adjacent load, as shown in FIG. 36, the continuity depends on the number of connected heating coil elements to which a high frequency current is supplied. There may be large differences in input power generated over time. For this reason, depending on the shape (size) of the load, the input power cannot be sufficiently reduced, and there are cases where the heating device is inconvenient such that the control range of power control is increased.

Therefore, as shown in FIG. 36, when the shape of the load is small and the number of connected heating coil elements is small, for example, when the number of connected heating coil elements is four (first heating coil 6 Simultaneous heating mode in which the first heating coil 6 and the second heating coil 7 are connected in parallel when two heating coil elements are connected to each other in the second heating coil 7). Operate with.

On the other hand, when the number of heating coil elements to be connected is large, for example, when the number of heating coil elements to be connected is ten (in the first heating coil 6 and the second heating coil 7, respectively) When five heating coil elements are connected), that is, when there are many heating coil elements connected in parallel and the load has a small impedance, the load impedance becomes too small when operated in the simultaneous heating mode. Therefore, a situation where the current of the connected heating coil element easily flows occurs, and a situation occurs where the input power is excessively supplied during the conduction time. In FIG. 36, as shown in the characteristic example when 10 heating coil elements are operated in the simultaneous heating mode, the line has a high input power.

Therefore, in the case of a load having a large number of heating coil elements connected in a large shape, the load is operated in the step-down simultaneous heating mode. In the step-down simultaneous heating mode, the input voltage applied to the first heating coil and the second heating coil that are the heating coil group is lowered, so that it is possible to create a situation in which the input current hardly flows even when the impedance is lowered. For example, if the number of heating coil elements of the first heating coil 6 and the second heating coil is the same, the input voltage is halved. In FIG. 36, as shown in the characteristic example when 10 heating coil elements are operated in the step-down simultaneous heating mode, the input power is a low line.

For example, if the voltage applied to each heating coil element is halved, the power is ¼ under the same operating conditions (operating frequency and conduction time).

In the configuration of the seventh embodiment, in addition to the simultaneous heating mode and the step-down simultaneous heating mode, a configuration having the alternate heating mode described with reference to FIGS. 32A and 32B in the above-described sixth embodiment may be employed. Under the same conditions, the input power with respect to the conduction time decreases in the order of simultaneous heating mode → alternate heating mode → step-down simultaneous heating mode in accordance with the impedance in the load. For this reason, in the structure of Embodiment 7, the system which switches sequentially according to conditions, such as the number of connections of a heating coil element, is also possible.

As described above, in the induction heating apparatus according to the seventh embodiment configured to heat the same load using a plurality of heating coil elements, resonance is performed with the heating coil element that induction-heats the load to three semiconductor switches connected in series. In the case of a load with a small number of connections of heating coil elements that increase impedance, the second semiconductor switch 11 is always turned on by connecting a plurality of resonance circuits composed of capacitors, and the first and third The semiconductor switches 10 and 12 are alternately turned on to operate in a simultaneous heating mode in which power is supplied to the first heating coil 6 and the second heating coil 7 simultaneously.

On the other hand, in the case of a load having a large number of connections of heating coil elements with low impedance, the second semiconductor switch, the first semiconductor switch and the third semiconductor switch group are alternately conducted, and the first The high-frequency power is simultaneously supplied to the heating coil 6 and the second heating coil 7 to operate in the step-down simultaneous heating mode for reducing the voltage applied to each heating coil. By supplying power to the first heating coil 6 and the second heating coil 7 in this way, predetermined input power can be given to the load at a constant operating frequency even if the number of connected heating coil elements changes, An induction heating device with no interference noise and excellent controllability can be realized.

(Embodiment 8)
The induction heating apparatus which is the induction heating cooking appliance of Embodiment 8 which concerns on this indication is demonstrated, referring drawings. In the description of the eighth embodiment, elements having substantially the same functions and configurations as those of the first to seventh embodiments are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 37 is a plan view showing a heating coil group having a plurality of heating coil elements provided immediately below the top plate 15 in the configuration of the induction heating apparatus according to the eighth embodiment of the present disclosure. In the induction heating apparatus according to the eighth embodiment, the differences from the sixth and seventh embodiments described above are the heating coil elements constituting the first heating coil 6 that is the heating coil group, and the heating coil group. The heating coil elements constituting the second heating coil 7 are alternately arranged on the same plane.

In the induction heating apparatus of the eighth embodiment shown in FIG. 37, the first heating coil 6 is composed of twelve heating coil elements 6a to 6l, and the second heating coil 7 is twelve heating coils. It consists of elements 7a to 7l. In the arrangement example shown in FIG. 37, 24 heating coil elements 6a to 6l and 7a to 7l are arranged in a zigzag state in a state of 4 rows × 6 columns. The heating coil elements 7a to 7l of the second heating coil 7 are arranged in rows and columns adjacent to the rows and columns in which the heating coil elements 6a to 6l of the first heating coil 6 are arranged.

By arranging a plurality of heating coil elements as described above, the number of connections of the heating coil elements in the first heating coil 6 is the same regardless of the position of the load placed in the heating area of the top plate 15. There is no significant difference in the number of connected heating coil elements in the second heating coil 7. Therefore, since the control unit 13 can operate each semiconductor switch symmetrically in each heating mode, it can perform simple control with high reliability and form a good heating distribution with respect to the load. be able to.

As described above, in the configuration of the induction heating apparatus according to the eighth embodiment, the number of connected heating coil elements forming the first heating coil 6 and the second heating coil 7 are formed in any heating mode. By alternately arranging the heating coil elements in order to reduce the difference in the number of connected heating coil elements, electric power can be evenly supplied from each heating coil element to the load. For this reason, according to the structure of the induction heating apparatus of Embodiment 8, the heating apparatus which can form the favorable heating distribution with respect to a load is realizable.

In the induction heating device of the present disclosure, the control unit includes the first semiconductor switch and the second semiconductor switch according to the state of the load when the load is placed in the heating region, for example, the material and size of the load. An appropriate heating mode is selected and executed by controlling the semiconductor switch and the third semiconductor switch. The heating mode executed in the induction heating device of the present disclosure includes a simultaneous heating mode in which high-frequency power is simultaneously supplied to the first heating coil and the second heating coil, and a first mode in which high-frequency power is supplied to the second heating coil. The single heating mode, the second single heating mode for supplying high-frequency power to the first heating coil, the alternating heating mode for alternately performing the first single heating mode and the second single heating mode, and the first heating. There is a step-down simultaneous heating mode in which high-frequency power can be supplied simultaneously to the coil and the second heating coil in a step-down state. The induction heating device of the present disclosure is configured to select an appropriate heating mode for the detected load from these heating modes and to induction heat the load. In addition, in the induction heating device of the present disclosure, when the selected heating mode is executed for the detected load, the heating mode that suppresses the input power when an inconvenient state such as the input power becomes too high occurs. You may comprise so that it may switch sequentially.

In the induction heating device of the present disclosure, as one embodiment, a first semiconductor switch connected to a power source, a second semiconductor switch, a series connection body of a third semiconductor switch, and the first semiconductor switch The first heating coil connected in parallel and the first heating coil magnetically coupled to the load and the first resonant capacitor, and the second heating coupled in parallel to the third semiconductor switch and magnetically coupled to the load A series connection body of a coil and a second resonance capacitor, and a control unit for controlling the first to third semiconductor switches; The control unit performs a first single heating operation in which the first semiconductor switch is always turned on, and the second and third semiconductor switches are alternately turned on to supply high-frequency power to the second heating coil. And a second single heating mode in which the third semiconductor switch is always turned on and the first and second semiconductor switches are turned on alternately to supply high-frequency power to the first heating coil. It is equipped with. In the present disclosure, each of the first to third semiconductor switches includes a first diode, a second diode, and a third diode that are connected in antiparallel to the semiconductor switch element.

When the control unit configured as described above supplies power to the load by both the first heating coil and the second heating coil, the control unit performs the first single heating mode and the second single heating mode. By executing the alternate heating mode that repeats in a short cycle, the average high frequency power can be supplied to both the first heating coil and the second heating coil equally at the same time.

As described above, a plurality of resonance circuits including a heating coil and a resonance capacitor for inductively heating a load are connected to three semiconductor switches connected in series, and one semiconductor switch of the three semiconductor switches is connected. As a semiconductor switch that determines a heating coil to be supplied with high-frequency power as a conductive state, the remaining semiconductor switch is used as a semiconductor switch that is driven on and off to supply high-frequency power of the heating coil, and the heating coil to be supplied with high-frequency power By switching the semiconductor switch for determining the high frequency power, the high frequency power is supplied to the plurality of heating coils substantially simultaneously. In this way, even with a configuration in which high-frequency power is supplied to a plurality of heating coils at the same time, there is no interference sound, cooking performance is excellent, and the number of components is small and the circuit mounting area is small and inexpensive induction heating. An apparatus can be provided.

In another embodiment of the induction heating device of the present disclosure, as another embodiment, a series connection body of first to third semiconductor switches connected to a smoothing capacitor that operates as a DC power source and a parallel connection to the first semiconductor switch are provided. A series connection of a first heating coil and a first resonant capacitor having at least one heating coil element magnetically coupled to the load, and connected in parallel to the third semiconductor switch, and magnetically coupled to the load A series connection body of a second heating coil and a second resonance capacitor having at least one heating coil element to be coupled, and a control unit for controlling the first to third semiconductor switches. The controller supplies the high frequency power to the first heating coil and the second heating coil by alternately conducting the first and third semiconductor switches while the second semiconductor switch is conducting. Simultaneous heating mode is provided. In addition, the control unit supplies the high-frequency power to the second heating coil by alternately conducting the second semiconductor switch and the third semiconductor switch while the first semiconductor switch is conducting. In the first operation (first single heating mode) and during conduction of the third semiconductor switch, the first semiconductor switch and the second semiconductor switch are alternately conducted to provide a first heating coil. The second operation (second single heating mode) for supplying high-frequency power to the alternating operation mode is alternately repeated. As described above, the control unit having the simultaneous heating mode and the alternate heating mode controls the first to third semiconductor switches so as to switch the heating mode according to the material of the load.

According to another embodiment configured as described above, in the induction heating apparatus that heats the same load using a plurality of heating coils, in the case of a material that increases the impedance of the load coupled to the heating coil. The simultaneous heating mode is executed, and in the case of a material having a low load impedance, the alternate heating mode is executed, so that the impedance can be made close to each other even when the load is made of different materials. For this reason, even if the material of the load changes, it is possible to supply necessary input power to the load at a constant frequency, and it is possible to provide an induction heating device that has no interference noise and has excellent controllability.

In yet another embodiment of the induction heating device of the present disclosure, as a further embodiment, a series connection body of first to third semiconductor switches connected to a smoothing capacitor operating as a direct current power source and the first connection arranged in a matrix form are provided. A plurality of first heating coil elements connected in parallel to the semiconductor switch, a plurality of second heating coil elements connected in parallel to the third semiconductor switch, and a series of each of the plurality of first heating coil elements A plurality of first resonant capacitor elements connected, a plurality of second resonant capacitor elements connected in series to each of the plurality of second heating coil elements, and the plurality of first and second heating coils A load detection unit that detects the presence of a heatable load in the vicinity of each of the elements. Moreover, in the induction heating device of this another embodiment, a plurality of first opening / closing section elements that cut off the supply of high-frequency power to each of the plurality of first heating coil elements (first heating coils); And an opening / closing section having a plurality of second opening / closing section elements for cutting off the supply of high-frequency power to each of the plurality of second heating coil elements (second heating coils). In the induction heating apparatus according to another embodiment configured as described above, when heating the same load, the first and second heating coil elements in which the nearby load is detected by the load detection unit are first and second. The first and third heating elements are controlled so as to be supplied with high-frequency power, and an appropriate heating mode is selected according to the number of connected heating coil elements to which high-frequency power is supplied. The operation of the semiconductor switch is controlled.

According to the induction heating device of still another embodiment configured as described above, according to the number of connected heating coil elements in the first heating coil and the second heating coil configured in the heating coil group, By switching the operations of the first to third semiconductor switches, it is possible to change the respective impedances and applied voltages in the first heating coil and the second heating coil. For this reason, in the induction heating apparatus of another embodiment, it is possible to perform power adjustment even with the operating frequency kept constant.

As a result, even when high-frequency power is supplied to a plurality of heating coil elements, there is no interference sound, cooking performance is excellent, and the number of parts is small, so that an inexpensive induction heating apparatus with a small circuit mounting area can be provided.

In addition, although the induction heating apparatus of this indication has demonstrated as an example the induction heating cooker which induction-heats loads, such as a pan which cooks foodstuffs, in addition to an induction heating cooker, it is the usual induction heating apparatus. In addition, application as a power feeding device to a non-contact power feeding device including a power receiving coil is also possible.

Although the present disclosure has been described in each embodiment with a certain degree of detail, the disclosure content of these embodiments should be changed in the details of the configuration, and the combination and order of elements in each embodiment should be changed. Changes may be made without departing from the scope and spirit of the claimed disclosure.

The induction heating device according to the present disclosure has no interference sound even when high-frequency power is supplied to a plurality of heating coils, has excellent cooking performance, and has a small circuit mounting area and can be realized at low cost. Therefore, it is effective in various induction heating equipment applications.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Input current detection part 4 Choke coil 5 Smoothing capacitor 6 1st heating coil 7 2nd heating coil 8 1st resonance capacitor 9 2nd resonance capacitor 10 1st semiconductor switch 11 2nd Semiconductor switch 12 Third semiconductor switch 13 Control unit 14a, 14b Load 15 Top plate 16 Operation / display unit 17 Operation / display unit 18 Top plate 20 First opening / closing unit 21 Second opening / closing unit 22 Load detection unit 25A, 25B load

Claims (12)

A series connection of a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch connected to a power source;
A series connection of a first heating coil and a first resonant capacitor connected in parallel to the first semiconductor switch and magnetically coupled to a load;
A series connection of a second heating coil and a second resonant capacitor connected in parallel to the third semiconductor switch and magnetically coupled to a load;
A controller that controls the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch;
The control unit always turns on the first semiconductor switch, turns on the second semiconductor switch and the third semiconductor switch alternately, and supplies high-frequency power to the second heating coil. Single heating mode,
A second single heating mode in which the third semiconductor switch is always turned on, the first semiconductor switch and the second semiconductor switch are turned on alternately, and high frequency power is supplied to the first heating coil;
The second semiconductor switch is always turned on, and the first semiconductor switch and the third semiconductor switch are turned on alternately to supply high-frequency power simultaneously to the first heating coil and the second heating coil. An induction heating apparatus configured to be driven selectively according to a simultaneous heating mode and a load. A resonance frequency generated in a first resonance circuit constituted by the first heating coil and the first resonance capacitor, and a second resonance circuit constituted by the second heating coil and the second resonance capacitor. The induction heating apparatus according to claim 1, wherein resonance frequencies generated in the same are configured to be the same. When supplying high-frequency power to both the first heating coil and the second heating coil, the control unit sets the period for the simultaneous heating mode and the first single heating mode or the second single heating. The first semiconductor switch and the second semiconductor switch are changed so that the average power supplied to both the first heating coil and the second heating coil becomes a target value by changing the ratio to the mode period. The induction heating device according to claim 1, wherein the induction heating device is configured to control a semiconductor switch and the third semiconductor switch. When supplying high frequency power to both the first heating coil and the second heating coil, the control unit sets each of the first single heating mode and the second single heating mode within 1 second. The induction heating apparatus according to claim 1, wherein the induction heating apparatus is configured to perform an alternating heating mode that is repeated in a short cycle to supply high-frequency power equally to both the first heating coil and the second heating coil. The state transition between the first single heating mode and the second single heating mode in the alternate heating mode is configured to be performed when the second semiconductor switch is in a non-conduction state. Induction heating device. When the control unit supplies high-frequency power to both the first heating coil and the second heating coil, the controller operates continuously in the first single heating mode in the alternate heating mode and the second single coil. The ratio of the heating mode to the continuous operation time is controlled to be the same, and in the first single heating mode and the second single heating mode, a high frequency is applied to the first heating coil and the second heating coil. Claims configured to control input power by changing operating frequencies or conduction times of two semiconductor switches in the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch that supply power. Item 6. The induction heating apparatus according to Item 4 or 5. When the control unit supplies high-frequency power to both the first heating coil and the second heating coil, in the first single heating mode and the second single heating mode in the alternate heating mode, Operating frequency or conduction time of two semiconductor switches in the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch that supply high-frequency power to the first heating coil and the second heating coil The input power is controlled by changing the ratio between the continuous operation time in the first single heating mode and the continuous operation time in the second single heating mode, with the constant being constant. The induction heating apparatus described. The first heating coil includes a plurality of first heating coil elements, the first resonance capacitor includes a plurality of first resonance capacitor elements, and the plurality of first heating coil elements includes the plurality of first heating coil elements. A plurality of series-connected bodies respectively connected to the first resonant capacitor element and connected in parallel to the first semiconductor switch,
The second heating coil includes a plurality of second heating coil elements, the second resonance capacitor includes a plurality of second resonance capacitor elements, and the plurality of second heating coil elements includes the plurality of second heating coil elements. A plurality of series-connected bodies respectively connected to the second resonant capacitor element and connected in parallel to the third semiconductor switch,
The control unit switches the first semiconductor to switch between an alternate heating mode in which the first single heating mode and the second single heating mode are alternately repeated, and the simultaneous heating mode according to a material of a load. The induction heating apparatus according to claim 1, wherein the induction heating apparatus is configured to control a switch, the second semiconductor switch, and the third semiconductor switch. The controller causes the first semiconductor switch and the third semiconductor switch to perform the same on / off operation, and the on / off operation of the first semiconductor switch and the third semiconductor switch. A step-down simultaneous heating mode in which on / off operations are alternately performed and high-frequency power is simultaneously supplied to the first heating coil and the second heating coil;
The induction heating device according to claim 8, wherein the control unit is configured to selectively switch between the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode according to a material of a load. A load detector for detecting the presence of a heatable load in the vicinity of each of the first heating coil element and the second heating coil element; and the first heating coil element and the first resonant capacitor element. Each of the plurality of first opening / closing section elements connected to and away from the energization path connecting the respective series connection bodies in parallel with the first semiconductor switch, the second heating coil element, and the second resonance capacitor element A plurality of second opening / closing section elements that are in contact with and away from an energization path that connects the series connection body in parallel with the third semiconductor switch;
The control unit includes the first opening / closing part element and / or the second opening / closing part corresponding to the first heating coil element and / or the second heating coil element, in which the load detection part detects a load nearby. The induction heating device according to claim 8 or 9, wherein the element is configured to bring the element into contact. A load detector for detecting the presence of a heatable load in the vicinity of each of the first heating coil element and the second heating coil element; and the first heating coil element and the first resonant capacitor element. Each of the plurality of first opening / closing section elements connected to and away from the energization path connecting the respective series connection bodies in parallel with the first semiconductor switch, the second heating coil element, and the second resonance capacitor element A plurality of second opening / closing section elements that are in contact with and away from an energization path that connects the series connection body in parallel with the third semiconductor switch;
The control unit includes the first opening / closing part element and / or the second opening / closing part corresponding to the first heating coil element and / or the second heating coil element, in which the load detection part detects a load nearby. The simultaneous heating mode and the alternate heating are controlled according to the number of the first heating coil element and / or the second heating coil element that controls the elements in a contact state and the load detection unit detects a load in the vicinity. The induction heating device according to claim 8 or 9, wherein the induction heating device is configured to selectively switch between a mode and the step-down simultaneous heating mode. The plurality of first heating coil elements constituting the first heating coil and the plurality of second heating coil elements constituting the second heating coil are alternately arranged in a planar heating region. The induction heating apparatus according to claim 8 or 9.

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