JP4065865B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to a power supply control system for an induction heating cooker.

  Conventional induction heating cookers of this type generate eddy currents in a metal load (pan) placed in the vicinity of a heating coil that passes high-frequency current, and the load itself self-heats due to its Joule heat, thereby heating efficiently. In recent years, the replacement of cooking utensils using gas stoves and electric heaters has been advanced due to their excellent safety and temperature controllability.

  In addition, efforts are being made to save energy, such as reducing power consumption during standby by devising a power supply path to the control circuit of the induction heating cooker and the inverter circuit that generates high-frequency current.

  The technology of the power supply control system that devised such a power supply path is specifically when an auxiliary contact is provided in the power switch, a relay is connected in parallel to the power switch, and the power switch is disconnected. The burner can be operated and the cooling fan can be operated, and even if the top plate on which the pan is placed is hot after the cooking is finished, the fan can be cooled while the burner warning is continued even if the power switch is turned off. It is safe for a person and can reduce standby power (see, for example, Patent Document 1).

JP 2003-59633 A

  However, the above prior art has the following problems.

  First, an inverter circuit that outputs a high-frequency current is likely to generate noise in order to perform high-frequency frequency conversion, and it is necessary to insert a large-capacity filter in the power supply unit in order to suppress noise generation. When the power switch is turned on, a very large inrush current is generated, which easily causes contact welding of the power switch and relay, and a large inductive noise is generated due to the inrush current. There is a risk of interference or malfunction of the control circuit of the induction cooking device. That is, FIG. 6 shows an example of the prior art of the power supply control system. In FIG. 6, a noise prevention capacitor 101 and a rectifying stack 102 are connected from a commercial power source 1 via a switch 100, and a choke coil 103 and a smoothing capacitor 104 are connected to the output side, and then an inverter unit 105 is connected. Since the capacitors 101 and 104 use relatively large capacitors in order to absorb noise components having the fundamental frequency of the operating frequency of the inverter unit 105, the series impedance from the commercial power supply is very low at the moment when the switch 100 is turned on. Since the charging current for the capacitors 101 and 104 flows in the state, the current has a very large peak value (about several hundred A). As a result, contact welding of the switch 100 is caused or inductive noise due to a large current is generated.

  Secondly, when the power switch is not turned off after the cooking, the standby power cannot be reduced by the power consumed by the control circuit because the power supply path supplied to the control circuit is not cut off.

  Third, when the power switch shares the power path of the inverter unit and the power path of the control power circuit, the power switch is disconnected and the control time is delayed until the control circuit stops the operation of the inverter unit. Since all current including inverter load current flows through a small-capacity relay arranged in parallel with the power switch, the contact capacity may be far exceeded and welding may occur.

  Fourthly, since an auxiliary contact linked to the power switch is necessary, a special structure is required for the switch itself, which causes an increase in cost.

  Fifth, if there are multiple induction heating units or electric heating units such as cooking heaters in the same housing, and the number of combinations varies depending on the lineup or the rated power differs, a control means is created for each model. Since it had to be divided, the development man-hours became longer, which caused the cost to increase.

  The present invention has been made to solve the above-mentioned problem. In claim 1, the first control means, the inverter means for driving the heating coil, and the inverter means for receiving the control information of the first control means. A second control means for controlling the operation, an operation means, a first switch means for turning on / off the power of the first control means, and the first switch means controlled by the first control means. A second switch means connected in parallel, a third switch means for turning on / off the power supply of the second control means, a fourth switch means for turning on / off the power supply of the inverter means, and a third switch means, A current suppressing element for connecting the load side and the load side of the fourth switch means, and after operating the first switch means, the first control means turns on the second switch means. The third switch means is turned on, and the fourth switch means is turned on prior to the start of energization of the heating coil by the inverter means, and then turned off after a lapse of a predetermined time after the operation of the inverter means is stopped, and the first switch means is turned off. Then, the second switch means is turned off by the first control means after the predetermined holding condition is released.

  According to a second aspect of the present invention, the first switch means is a momentary type.

  According to a third aspect of the present invention, the first control means includes the second switch when the temperature detection means has a temperature detection means and the first switch means is turned off, and the temperature detected by the temperature detection means is a predetermined temperature or higher. The on-operation of the means is held.

  According to a fourth aspect of the present invention, when the operating means is not operated for a predetermined time after the first control means outputs the control information for stopping the driving of the heating coil to the second control means, the first control means After the third switch means is turned off, the second switch means is turned off.

  The induction heating cooker of the present invention is configured as described above, so that the initial charging of the filter of the inverter means with a low current is performed by turning on the third switch means before the fourth switch means is turned on. Therefore, the occurrence of inrush current is reduced, and there is no possibility of contact welding of the fourth switch means, generation of inductive noise, and malfunction of the control circuit due to the inductive noise.

  Further, since the first control means is activated after the first switch means to be the power switch is turned on and the second switch means is turned on, the first control means is continued even if the power switch is turned off. All the power paths can be shut off by turning off the second switch means by itself after the predetermined holding condition is released, and the standby power can be made zero.

  Further, since the second switch means for turning on / off the power supply of the first control means is not shared with the power supply path of the inverter means, the load current of the inverter means does not flow to the small capacity relay of the second switch means, There is no such thing as exceeding the contact capacity and welding.

  Further, the third switch means can suppress the inrush current to the inverter means, and can also serve as a power supply path for the second control means, thereby reducing the required number of switch means and reducing the cost. You can hold up.

  Further, since the power supply of the second control means is turned on after the third switch means is turned on, the power supply of the second control means is not turned on when the third switch means fails in the off state. Since the operation of the means is stopped and the OFF failure of the third switch means can be detected with certainty, the safety is high.

  Furthermore, the second control means for controlling the inverter means is provided, and the control information such as the set power from the first control means is received by the second control means so as to control the inverter means. Even if there are multiple induction heating units and electric heater units in the same housing as shown above, and the number of combinations varies depending on the lineup or the rated power is different, it can be easily adapted by adding inverter means as appropriate. Since there is no need to create a separate control means for each, the development man-hours can be greatly reduced and the cost can be reduced.

  An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of an induction heating cooker showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation sequence of the switch means, FIG. 3 is a detailed block diagram of the inverter means, and FIG. FIG. 5B is a diagram for explaining the operation sequence of the switch means. FIG. 5 is a diagram illustrating the power supply current flowing through the inverter means in the conventional power-on sequence, FIG.

  In FIG. 1, 1 is a commercial power source, 2 is a first control means, and 3 is a second control means, which receives control information from the first control means 2 and transmits necessary information to the first control means 2. is doing.

  Reference numerals 4 and 4b denote inverter means that convert the power of the commercial power source 1 into a high-frequency output, output it to the heating coils 4a and 4c, and load such as a pan placed on the top plate (not shown) of the induction heating cooker. Is to heat. The inverter means 4 is controlled by the second control means 3.

  Reference numeral 5 denotes an operation unit including a key input unit and a display unit for the user to set the operating state of the induction heating cooker, and performs input / output to the first control unit 2.

  Reference numeral 6 denotes a first switch means, which is a switch for the user to turn on / off the power source of the induction heating cooker, and supplies power to the first control means 2 via the first switch means 6. .

  The second switch means 7 is connected in parallel with the first switch means 6 and supplies power to the first control means. The second switch means 7 comprises a relay and is controlled to be turned on and off by the first control means 2. .

  Reference numeral 8 denotes a third switch means, which is constituted by a relay and is on / off controlled by the first control means 2, and supplies power to the second control means 3 via the third switch means 8.

  Reference numerals 9 and 9a denote fourth and fifth switch means, which are constituted by relays and are controlled to be turned on and off by the first control means 2 and the second control means 3, and the fourth and fifth switch means 9 and 9a. Power is supplied to the inverter means 4 and 4b via the.

  Reference numerals 10 and 10a denote current suppressing elements, which are constituted by resistors or the like, and connect the load sides of the third switch means 8 and the fourth and fifth switch means 9 and 9a to each other.

  Reference numeral 11 denotes a temperature detection means for detecting the temperature of a top plate on which a load is placed or a structural part that may be touched by a user, or the temperature of a part inside the device, and transmitting the detected temperature to the first control means 2. It is.

  The second control means 3 receives control information such as the set power of each of the inverter means 4 and 4b from the first control means 2 and controls the inverter means 4 and 4b, and the operation of the inverter means 4 and 4b. The state is detected, and necessary information is transmitted to the first control means 2, whereby information such as “the first control means 2 energize the heating coil 4 a with the heating power 5” is transmitted to the second control means 3. , The second control means 3 issues a drive signal to the inverter means 4 and controls the energized power corresponding to the heating power 5 to be applied to the heating coil 4a while detecting the operating state of the inverter means 4.

  Further, when the second control means 3 tries to energize a no-load energization or a load that cannot be heated, the detection result is transmitted to the first control means 2, and the first control means 2 is in the operation means 5. Display or warn the user.

  The configuration of the fifth switch means 9a, inverter means 4b, heating coil 4c, and current suppression element 10a shown on the right side of the broken line at the right end of FIG. 1 is an extension method when a plurality of heating coils are provided in the same casing. If only one heating coil is required, these are not necessary. If three or more heating coils are required, the configuration shown on the right side of the broken line may be added in the same manner. Further, when an electric heater is provided instead of the heating coil, the inverter means may be an electric current supply means for the electric heater, and may be additionally installed with the same configuration.

  Next, the operation sequence of the switch means in FIG. 2 will be described.

  FIG. 2 is a time chart showing the on / off states of the first to fourth switch means 6, 7, 8, 9.

  In the present embodiment, it is assumed that the first switch means 6 functions as a switch for performing power operation of the induction heating cooker itself. That is, it becomes a trigger to turn on / off the power connection state of the device by an operation equivalent to a normal power switch.

  When the user turns on the first switch means 6 at time T1, the first control means 2 is powered on and the first control means 2 is activated. When the first control means 2 detects that the ON state of the first switch means 6 has continued for a predetermined time or more, the first control means 2 turns on the relay of the second switch means 7 at time T2. The power supply path is secured by itself and the power-on operation is maintained.

  The first switch means 6 may be a seesaw type switch or a momentary type switch. However, by using a momentary type switch, the second switch means 7 becomes a power supply path to the first control means 2, and Needless to say, since the power supply path can be automatically cut when the user forgets to turn off the power because the user can forcibly turn off the power, the first switch means 6 is momentary in FIG. The case of a type switch is indicated by a solid line, and the case of a seesaw type switch is indicated by a dotted line, but the following description will be given for the case of using a momentary type switch).

  Even if the first switch means 6 is turned off at time T3, the operation continues because the second switch means 7 secures the power supply path.

  At time T4 when a predetermined time has elapsed from time T2, the first control means 2 turns on the third switch means 8 in order to secure the power supply path of the second control means 3, and the second control means 3 Starts.

  At time T5, when the user gives an instruction to energize the inverter means 4 by the operation means 5, the first control means 2 or the second control means 3 turns on the fourth switch means 9 and then the inverter means 4 The energization operation for the heating coil 4a is started.

  At time T6, the first control means 2 gives the second control means 3 control information for stopping the driving of the heating coil 4a, and after the heating of the inverter means 4 is stopped, the fourth switch means 9 is turned off. The power supply path to the inverter means 4 is cut off.

  Thereafter, at time T7, when the user performs an operation of turning off the power of the device by the first switch means 6 (on again for a momentary switch, off for a seesaw switch), the third switch While the means 8 is turned off and the temperature detected by the temperature detecting means 11 does not exceed the predetermined temperature, the second switch means 7 is turned off and the power supply path of the first control means 2 is cut by itself. When the temperature detected by the temperature detecting means 11 exceeds a predetermined temperature, the ON operation of the second switch means 7 is maintained until the temperature falls to the predetermined temperature or a predetermined time elapses, and a burn warning or the like is maintained. Is displayed by the operation means 5 and the second switch means 7 is turned off after those conditions are released.

  Therefore, when a burn warning or the like is necessary, even if the user performs an operation to turn off the power switch, the power supply path of the first control means 2 is secured until the release condition is satisfied, and thereafter all Since the power supply path is cut off, standby power can be reduced to zero.

  Next, the operation parts of the third switch means 8 and the fourth switch means 9 will be described with reference to FIGS.

  FIG. 3 shows the connection configuration of the third switch means 8 and the fourth switch means 9 and the second control means 3 and the inverter means 4. FIG. 4 shows the third and fourth switch means 8 and 9. It shows the state of the power supply current by the operation of. T4 and T5 indicate the same timing as the time chart in FIG.

  In FIG. 3, the inverter means 4 is connected to the commercial power supply 1 side with a noise prevention capacitor 41, connected to a rectifying stack 42, converted into a DC power supply, smoothed by a choke coil 43 and a smoothing capacitor 44, and then converted into an inverter. The circuit 45 is connected.

  FIG. 4 shows the difference in power supply current (b) between the power-on sequence (a) of the conventional example and the power-on sequence of the present embodiment in the connection state of FIG.

  The conventional example (a) is equivalent to the case where the third switch means 8 and the fourth switch means 9 are turned on at the same time (time T4 and T5 are simultaneous), and the element that suppresses the current flowing through the capacitor 41 and the capacitor 44. Is almost zero (since the inrush current blocking capability of the choke coil 43 is small), the power supply current shows a high peak value.

  In this embodiment (b), the third switch means 8 is turned on at time T4, and the capacitor 44 is charged with the current whose peak is suppressed by the current suppressing element 10. Thereafter, the fourth switch means 9 is turned on at time T5, but since the capacitor 44 has already been charged halfway, the peak value of the remaining charging current is also suppressed.

  Therefore, it is possible to suppress the contact welding of the fourth switch means 9 and the generation of inductive noise that may occur due to a high charge current peak.

  Next, in FIG. 5, after the first switch means 6 is turned on at time T1, the first control means 2 outputs control information for stopping the heating coil 4a to the second control means 3 at time T6. The sequence is the same as that in FIG. 2 until the heating by the inverter means 4 is completed.

  Thereafter, when the user forgets to turn off the power switch, or when the operation means 5 has not been operated for a predetermined time, when the predetermined time has elapsed and the time T10 is reached, the first control means 2 By turning off the second switch means 7 after turning off the third switch means 8, all power supply paths can be shut off.

  At this time, if the detection result of the temperature detection means 11 exceeds a predetermined temperature, a burn warning or the like is issued by the operation means 5 until the temperature falls to the predetermined temperature or until a predetermined time elapses. The safety for the user can be secured by turning off the second switch means 7 after the above condition is released.

  Further, for example, in an induction heating cooker having a cooking timer function, all power supply paths can be automatically cut by using this configuration after performing cooking by using a cooking timer.

  Thus, since the initial charge to the filter of the inverter means 4 is performed at a low current by turning on the third switch means 8 before the fourth switch means 9 is turned on, the occurrence of an inrush current occurs. This eliminates the possibility of contact welding of the fourth switch means 9, generation of inductive noise, and malfunction of the control circuit due to the inductive noise.

  Further, since the first control means 2 is activated after the first switch means 6 to be a power switch is turned on and the second switch means 7 is turned on, the first control means 2 is turned on even if the power switch is turned off. Can be operated continuously, and after the predetermined holding condition is released, all the power supply paths can be cut off by turning off the second switch means 7 by itself, and the standby power is made zero. be able to.

  Further, since the second switch means 7 for turning on / off the power supply of the first control means 2 is not shared with the power supply path of the inverter means 4, the load of the inverter means 4 is connected to the small capacity relay of the second switch means 7. No current flows, and there is no such thing as exceeding the contact capacity and welding.

  Further, the third switch means 8 can reduce the necessary number of switch means by suppressing the inrush current to the inverter means 4 and also serving as the power supply path of the second control means 3. Yes, cost increase can be suppressed.

  Further, since the power supply of the second control means 3 is turned on after the third switch means 8 is turned on, the power supply of the second control means 3 is turned on when the third switch means 8 fails in the off state. Therefore, the operation of the inverter unit 4 is stopped, and an off-fault of the third switch unit 8 can be reliably detected, so that safety is high.

  Furthermore, the second control means 3 for controlling the inverter means 4 is provided, and the second control means 3 receives control information such as the set power from the first control means 2 to control the inverter means 4. Thus, even when there are a plurality of induction heating units and electric heating units such as cooking heaters in the same casing, and the number of combinations differs depending on the lineup or the rated power is different, the inverter means 4 is connected to the right end of FIG. The configuration described on the right side of the broken line can be easily adapted by adding as appropriate, and it is not necessary to create a control means for each model, so that the development man-hour can be greatly reduced and the cost can be reduced.

It is a block diagram of the induction heating cooking appliance which shows one Example of this invention. It is a figure explaining the operation | movement sequence of a switch means similarly. It is a detailed block diagram of an inverter means similarly. (A) is a figure which shows the power supply current which flows into the inverter means in the power-on sequence of a prior art example, (b) is a figure which shows the power supply current which flows into the inverter means of an Example. It is a figure explaining the operation | movement sequence of the switch means which shows one Example of this invention. (A) is a block diagram of the conventional induction heating cooking appliance, (b) is a figure which shows the waveform of a power supply current.

Explanation of symbols

2 1st control means 3 2nd control means 4 Inverter means 4a Heating coil 6 1st switch means 7 2nd switch means 8 3rd switch means 9 4th switch means 10 Current suppression element 11 Temperature detection means

Claims (4)

First control means (2);
Inverter means (4) for driving the heating coil (4a);
Second control means (3) for receiving control information from the first control means (2) and controlling the inverter means (4);
Operating means (5);
First switch means (6) for turning on and off the power supply of the first control means (2);
The second switch means (7) connected in parallel to the first switch means (6) controlled by the first control means (2) and the power source of the second control means (3) are turned on and off. A fourth switch means (9) for turning on and off the power supply of the third switch means (8) and the inverter means (4);
A current suppressing element (10) connecting the load side of the third switch means (8) and the load side of the fourth switch means (9);
After operating the first switch means (6), the first control means (2) turns on the second switch means (7), turns on the third switch means (8), and further turns on the inverter means (4 ), The fourth switch means (9) is turned on prior to the start of energization of the heating coil (4a). When operated, the second switch means (7) is turned off by the first control means (2) after a predetermined holding condition is released. The induction heating cooker according to claim 1, characterized in that the first switch means (6) is of a momentary type. If the temperature detection means (11) has a temperature detected by the temperature detection means (11) when the first switch means (6) is turned off when the first switch means (6) is turned off, the first control means (2) The induction heating cooker according to claim 1 or 2, wherein the ON operation of the second switch means (7) is maintained. After the first control means (2) gives the second control means (3) control information for stopping the driving of the heating coil (4a), when the operation means (5) is not operated for a predetermined time, 4. The induction heating cooker according to claim 1, wherein the control means (2) turns off the second switch means (7) after turning off the third switch means (8).

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