JPH11341711A - Noncontact power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact power supply circuit which is able to suppress the supply of a large power to a load at no-load or a light load time, to avoid overheating and to improve safety. SOLUTION: A pulse-type load signal current, corresponding to a load current, is applied to a signal transmission load circuit 21 connected to a secondary winding 4b side of an output transformer 4, by superposing the signal current upon the own current of the circuit 21 for transmitting the load signal current to a primary winding 4a side of the output transformer 4 through electromagnetic induction coupling. The load signal current is applied to the primary winding 4a, a diode 9 and a resistor 7 and detected by a current detection circuit 10. An oscillation frequency variable circuit 11 is made to vary the oscillation frequency of an oscillation circuit 12, in accordance with the detected value of the current detection circuit 10 so as to vary the switching period of a MOS transistor 6 and hence the chopping period of a DC voltage on the primary side. With this constitution, a small power is supplied to a secondary side at no-load or a light load time and a large power is supplied to the secondary side, when the load signal current from the secondary side is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting the presence or absence of a change to a primary side in a non-contact manner in response to a change in a load current on a secondary side of a power supply circuit. The present invention relates to a non-contact power supply circuit which is set to a low power or intermittent power mode in a high power mode and when there is no notification of a change.

[0002]

2. Description of the Related Art In a conventional power supply device for transmitting primary power to a secondary side by electromagnetic induction coupling using a transformer, generally, a primary coil and a secondary coil are respectively wound around an iron core. , The primary coil and the secondary coil are electromagnetically coupled,
In a state where electric energy can be transmitted from the primary side to the secondary side by electromagnetic induction, the primary coil and the secondary coil are insulated from each other and surrounded by an envelope. In the power supply device having such a configuration, electric energy is transmitted by electromagnetic induction, not by contact of the conductor pieces, so that a contact failure or the like can be prevented beforehand. First, a predetermined output is always obtained on the secondary side. Therefore, problems such as heating occur.

In order to solve this problem, a load fluctuation is transmitted to the primary side according to a change in the load current on the secondary side, and the power supply to the secondary load is controlled according to the load fluctuation. In addition, detection of fluctuation of the load current on the secondary side or one of the load fluctuations
Means of communication to the next side are taken. Among these examples, as a first method, for example, a secondary-side load current is caused to flow through a coil to generate a magnetic flux, and the magnetic flux and a magnet are magnetically coupled to change the secondary side from the secondary side to the primary side. There is a method of transmitting load current fluctuation.

As a second method, a mechanical switch is provided between the secondary side and the primary side, and the mechanical switch is turned on and off by thermal expansion of a metal piece generated according to the secondary side load current. Thus, there is a method of transmitting the fluctuation of the load current on the secondary side from the secondary side to the primary side. In addition, the third
As a method, a method using an optical sensor is employed. In the case of this optical sensor, a light emitting element is provided at a predetermined position on the secondary side, a light receiving element is arranged on the primary side in opposition to the light emitting element, and the light emitting element is caused to emit light in accordance with the secondary side load current,
There is a method of transmitting the fluctuation of the load current on the secondary side from the secondary side to the primary side by receiving the light with the light receiving element on the primary side.

However, in each of the first to third methods, when the secondary load current is a small current, a measure is taken to appropriately switch the power supplied from the primary side to the secondary side to the small power. There is no problem. That is, if the current continues to flow irrespective of the load current, there is a problem that the iron core (core) heats up when there is no load, and the parts around the core also become hot. Accordingly, the magnets, mechanical switches, light-emitting elements, light-receiving elements, and the like serving as the detection means may be damaged.

Therefore, as an approximation technique of the present invention described later, for example, Japanese Patent Application Laid-Open No. 03-239137 discloses
The primary coil and the secondary coil of the output transformer are insulated and isolated by an envelope, a parallel circuit of a switch current limiting element and a switch is connected in series to the primary coil, and the secondary coil is connected to the load side. It is disclosed that a detection circuit for detecting an output state is provided, and a switch is opened and closed by an output of the detection circuit. In the case of this publication, when there is no load, a change in the impedance of the load circuit is detected by the detection circuit as a change in the output frequency of the inverter. The output of the inverter is reduced to reduce the current of the secondary coil.

[0007]

However, in the case of this publication, a switch and a current-limiting element are provided on the primary side, and when a load is applied, power is supplied to the current-limiting element. Yes, a reduction in efficiency is inevitable. In addition, a switch is provided on the secondary side to transmit a control signal from the secondary side to the primary side when the switch is turned on or off when control is performed so that the load current on the secondary side flows by a predetermined amount. In this case, it is necessary to generate a pulse-like signal in a circuit through which a secondary-side main current flows. If a high-power control is performed by generating a pulse signal on the secondary side, the voltage on the secondary side fluctuates according to ON and OFF, which affects each circuit connected to the secondary side. Will have an effect.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. When the control signal is not transmitted from the secondary side to the primary side, the secondary side power is reduced to a small power or When the power is set to intermittent power and the control signal is transmitted from the secondary side to the primary side in a non-contact manner, the secondary side power can be controlled to a large power. There is no need to worry about heating, safety can be ensured, and at the time of large power supply, there is no effect on each circuit connected to the secondary side, and signal transmission from the secondary side to the primary side An object of the present invention is to provide a contactless power supply circuit that can be easily performed.

[0009]

In order to achieve the above object, a contactless power supply circuit of the present invention chops a DC current supplied to a primary winding by a switching means and supplies an AC voltage to a secondary winding. Transformer, an oscillating circuit for supplying a switching signal to the switching means, a rectifying means for rectifying an output voltage of the secondary winding, and supplying or interrupting a rectified voltage obtained by the rectifying means to a load. And a rectifying current obtained by the rectifying means is supplied, and a current of a load signal according to the state of the load is superimposed thereon, and the current of the load signal is generated by electromagnetic induction coupling of the output transformer. And a signal transmission load circuit that transmits the signal to the primary winding, and detects a change in the output voltage of the rectifier in accordance with the state of the load to detect the signal transmission load circuit and the secondary side. Secondary-side control means for performing on / off control of the switch circuit; current detection means for detecting the current of the load signal transmitted to the primary winding; Upon detection, the oscillation circuit performs frequency control on the secondary winding so that the switching means switches in a low power mode or intermittent operation, and the current detection means detects the current of the load signal when the oscillation circuit detects the current. And a primary-side control unit for performing frequency control on the secondary winding so that the switching unit switches in a high power mode. According to the present invention, the load signal can be easily transmitted from the secondary side to the primary side, and when there is no load signal transmitted from the secondary side to the primary side of the power supply circuit, the power of the secondary side can be reduced. Is small power or intermittent power, an unnecessary current does not flow to the load at no load or light load, and heating of the metal part by the current is prevented.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a contactless power supply circuit according to an embodiment of the present invention. FIG.
FIG. 1 is a block diagram showing a configuration of a first embodiment according to the present invention. In FIG. 1, an AC power supply is connected to the input terminals 1a and 1b, and the input terminals of the full-wave rectifier circuit 2 are connected to the input terminals 1a and 1b. A smoothing capacitor 3 is connected between the positive output terminal and the negative output terminal of the full-wave rectifier circuit 2. This negative output terminal is grounded.

The output terminal on the positive side of the full-wave rectifier circuit 2 is connected to one end of a primary winding 4a of the output transformer 4. The other end of the primary winding 4a is grounded via a capacitor 5, and is connected to the drain of a MOS transistor 6 as switching means. The source of the MOS transistor 6 is a resistor 7 and a capacitor 8 for detecting a primary current.
And grounded through a parallel circuit. The resistor 7 is used as a current detecting means. A diode 9 is connected between the drain and the source of the MOS transistor 6. The bulk and source of the MOS transistor 6 are directly connected.

One end of the resistor 7 is connected to an input terminal of the current detection circuit 10. The current detection circuit 10 receives a voltage corresponding to the current flowing through the diode 9 and the resistor 7, and applies the input to the input terminal of the oscillation frequency variable control circuit 11. The output terminal of the oscillation frequency variable control circuit 11 is connected to the oscillation circuit 12. The oscillation frequency variable control circuit 11 varies the oscillation frequency of the oscillation circuit 12 according to the output voltage of the current detection circuit 10. The output terminal of the oscillation circuit 12 is connected to the gate of the MOS transistor 6. Thus, the diode 9, the resistor 7, and the current detection circuit 10 constitute a current detection means, and the oscillation frequency variable control circuit 11 and the oscillation circuit 1
2 and the MOS transistor 6, the primary side control means 1
3.

Next, the configuration of the secondary side will be described. The output transformer 4 has a primary winding 4a and a secondary winding 4b electromagnetically coupled. A series circuit of the diode 14 and the capacitor 15 (constituting rectifying means) is connected between both ends of the secondary winding 4b. The other end of the secondary winding 4b is grounded. One end of the secondary winding 4b is connected to an output terminal 19 via diodes 16 and 17 and a switch circuit 18.
a. The diode 16 is a rectifying diode, and the cathode of the diode 17 is connected to an output terminal 19b via a smoothing capacitor 20.
A load (not shown) is connected between the output terminals 19a and 19b.

A signal transmission load circuit 21 is connected between the cathode of the diode 16 and the output terminal 19b.
2 is connected to the input terminal of the secondary side control circuit 23. The secondary side control circuit 23 performs on / off control of the switch circuit 18 and the signal transmission load circuit 21 in accordance with the fluctuation of the voltage obtained by rectifying the voltage of the secondary winding 4b by the diode 14. The power supply circuit 22 includes the secondary control circuit 2
3 is a circuit for supplying an operating voltage to the circuit 3.

A signal transmission load circuit 21 and a power supply circuit 22
And the secondary side control circuit 23, the secondary side control means 24
Is composed. The secondary side control means 24 generates ON / OFF signals corresponding to the load fluctuations to transmit the load fluctuations to the primary side of the power supply circuit without contact, and further controls ON / OFF of the switch circuit 18. By doing so, the power supply to the load can be interrupted.

Next, the operation of the first embodiment configured as described above will be described. Input terminals 1a, 1b
An AC power supply (not shown) is connected between the
It is assumed that a load such as a charger (not shown) is connected between 9a and 19b. In this state, the voltage of the AC power supply is full-wave rectified by the full-wave rectifier circuit 2 and smoothed by the capacitor 3, and the DC voltage is applied to the primary winding 4 of the output transformer 4.
a is applied to one end. At the same time, the oscillation circuit 12 oscillates according to the time constant determined by the oscillation frequency variable control circuit 11 of the primary side control circuit 13, and the oscillation circuit 1
MOS transistor 6 according to the oscillation output frequency of
Turns on and off repeatedly.

Thus, the output and the DC voltage applied to the primary winding 4a of the transformer 4 are converted into an AC voltage, and the AC voltage is transformed by the output transformer 4, and
A predetermined AC voltage is generated at both ends of the next winding 4b. This AC voltage is rectified by the diode 14 and the capacitor 1
5, and is applied to the load via the diodes 16 and 17 and the switch circuit 18. The voltage across the secondary winding 4b changes depending on whether this load is light or heavy. That is, the potential of the cathode of the diode 14 changes.

If the load is light or no load, a large current does not need to flow through the secondary side of the output transformer 4. In such a state, the voltage across the secondary winding 4b is substantially the rated voltage, and therefore, there is no large change in the cathode potential of the diode 14, and it is within a predetermined rated allowable range. Therefore, the secondary-side control circuit 23 does not control the operation of turning on and off the load circuit 21 for signal transmission. Thus, the current flowing to the secondary winding 4b does not fluctuate due to ON / OFF.

If the current on the secondary side does not fluctuate, even if the primary winding 4a and the secondary winding 4b of the output transformer 4 are electromagnetically inductively coupled, the secondary winding 4b is turned on and off. Is not transmitted to the primary winding 4a side. Therefore, on the primary side of the output transformer 4, there is no change in the current flowing through the current detection circuit 10, and thus the oscillation frequency variable control circuit 11 of the primary side control means 13 changes the frequency with respect to the oscillation circuit 12. No control is performed.

As a result, an output signal of a predetermined oscillation frequency is output from the oscillation circuit 12 to the MOS transistor 6
And the MOS transistor 6 is turned on and off at the oscillation frequency. Thereby, the primary winding 4a,
As a result, the secondary winding 4b is provided with the secondary current I shown in FIG.
, And a predetermined steady-state current, that is, a small current Is flows in the first embodiment, and a small power PS is supplied to the secondary side. You. At this time, by performing the intermittent control by turning on and off the switch circuit 18 by the secondary side control circuit 23, the load current can be further reduced.

Therefore, when the load is light or no load, the load current is extremely small, so that heat generation due to the load current can be suppressed, and the heat transfer member disposed at or near the iron core of the output transformer 4. Of the primary winding 4a and the secondary winding 4b due to the generation of heat, it is possible to prevent the deterioration of the insulating properties of the interlayer insulating material and the deterioration of the characteristics of the other parts. Heating can be prevented.

Next, the operation for increasing the load current on the secondary side of the output transformer 4 will be described. When a large current of a predetermined value or more flows through the load, the voltage across the secondary winding 4b of the output transformer 4 decreases. Along with this, the potential of the cathode of the diode 14 also decreases, and the lowering of the potential is received by the power supply circuit 22, and the secondary-side control circuit 23 controls the on / off operation of the load circuit 21 for signal transmission. At the same time, the switch circuit 18 is turned off. When the signal transmission load circuit 21 turns on and off, the current on the secondary side of the output transformer 4 turns on and off. Accordingly, the current flowing through the primary winding 4a of the output transformer 4 that is electromagnetically inductively coupled also changes, and a current of one polarity corresponding to the change flows through the diode 9 and the resistor 7.

The voltage at both ends of the resistor 7 changes according to the current change, and the change is detected by the current detection circuit 10. This change in voltage is output by the oscillation frequency variable control circuit 12 of the primary side control means 13, and the oscillation frequency of the oscillation circuit 12 is varied according to the output value. In this case, the diode 9
And the larger the current flowing through the resistor 7 is,
Is controlled such that the lower the potential at one end of the device becomes, the lower the oscillation frequency becomes. According to the oscillation frequency, the MOS transistor 6 also turns on and off.

In this case, when the oscillation frequency of the oscillation circuit 12 decreases, the time during which the MOS transistor 6 is turned on increases, and the current flowing through the drain-source of the MOS transistor 6 increases accordingly. Therefore, the current flowing through the primary winding 4a of the output transformer 4 is also increased, and the magnetic flux crossing the secondary winding 4b is increased. As shown by the large power PL in FIG. Can be supplied. As described above, in the first embodiment, when there is no signal transmitted from the secondary side of the power supply circuit to the primary side at light load or no load, the secondary side power is set to small power or intermittent power. Further, since the current flowing to the secondary side is reduced, it is possible to prevent heat generation due to the current when the load is light or no load.

As a result, it is possible to prevent the deterioration of the insulation due to heat generation and the deterioration of various characteristics of the parts.
On the other hand, at the time of a large current, a necessary current can be supplied to the secondary side, so that there is no problem as a power supply circuit. In FIG. 1, the case where the element indicated by reference numeral 9 is configured by a diode has been described, but the present invention is not limited to this, and a transistor or other one-way control element may be used. Further, the diode 17 can be omitted. Further, the input terminal of the power supply circuit 22 may be connected to a connection point between the diode 17 and the capacitor 20. In this case, the diode 14 and the capacitor 1 shown in FIG.
5 can be omitted.

Next, a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of the second embodiment. 3, in the description of the configuration, the same parts as those in FIG. 1 are denoted by the same reference numerals to avoid redundant description, and the description will focus on the parts different from FIG. As is clear from comparison of FIG. 3 with FIG. 1, FIG. 3 shows the configuration of the primary side control means 13 on the primary side of the output transformer 4 and the configuration of the secondary side control means 24 on the secondary side. Further, a portion using the transistor 26 as the switch circuit 18 is different from the first embodiment.

That is, in the primary side control means 13,
Two operational amplifiers 28 and 29 are added in place of the primary side current detection circuit 10. Operational amplifiers 28, 2
9 is connected to one end of the resistor 7, that is, M
It is connected to the source side of OS transistor 6. The non-inverting input terminals of the operational amplifiers 28 and 29 are grounded. The operational amplifier 29 is connected to the resistor 7 via the primary winding 4a.
Small in current I ₁ flows in, and outputs it to the control circuit 30 the voltage corresponding thereto is generated.

Similarly, the operational amplifier 28 is connected to the primary winding 4
When a large current Is flows through the resistor 7 via a, a voltage corresponding to the large current Is is generated and output to the signal receiving circuit 31. The signal receiving circuit 31 receives the output voltage of the operational amplifier 28, outputs the signal when the output voltage is equal to or higher than a predetermined value, and activates the control circuit 30. The control circuit 30 varies the oscillation frequency of the oscillation circuit 11 according to the output voltages of the operational amplifiers 28 and 29. 1
The changes to FIG. 1 on the next side are as described above.

The secondary-side control means 24 comprises a secondary-side control circuit 23 and a signal transmission load circuit 21. The signal transmission load circuit 21 includes a transistor 32 and a resistor 33.
This is a case where it is composed of Transistor 3
The output terminal of the secondary side control circuit 23 is connected to the base 2. The emitter of the transistor 32 is connected to the output terminal 19b. The collector of the transistor 32 is a resistor 3
2 is connected to a connection point between the diodes 16 and 17.

A transistor 26 is used as the switch circuit 18. The emitter of the transistor 26 is connected to the cathode of the diode 17, and the collector is connected to the output terminal 19a. Transistor 2
6 is connected to the output terminal of the secondary side control circuit 23. A capacitor 27 is connected between the output terminals 19a and 19b. This capacitor 27 discharges to the load until the transistor 26 of the switch circuit 18 turns off and turns on, so that the output terminal 19a
And a capacitor for preventing the operation of a load (not shown) connected between the first and the second terminals 19b from being affected.
A time constant that satisfies this condition, that is, a capacity is selected. Other configurations are the same as those in FIG.

Next, the operation of the second embodiment will be described. As in the case of the first embodiment, when the load is in a no-load state, it is not necessary to supply a large current to the secondary side of the output transformer 4. In such a state, the voltage between both ends of the secondary winding 4b is almost the rated voltage, and therefore, there is no large change in the cathode potential of the diode 14, and as described in the first embodiment, The current is within a predetermined allowable range, and the current flowing to the secondary winding 4b does not fluctuate due to ON and OFF.

As a result, on the primary side of the output transformer 4, there is no change in the current of one polarity flowing through the diode 9 and the current input to the operational amplifiers 28 and 29, and the control of the primary side control means 13 does not change. The circuit 30 does not control the oscillation circuit 12 to change the frequency. As a result, an output signal of a predetermined oscillation frequency is applied from the oscillation circuit 12 to the gate of the MOS transistor 6, and the MOS transistor 6 is turned on and off at the oscillation frequency, so that the secondary winding 4b of the output transformer 4 As shown in FIG. 4 (where the horizontal axis indicates the output current Iout flowing to the secondary side and the vertical axis indicates the input current Iin flowing to the primary image), the change in the power on the secondary side at this time is almost zero. It is close to.

From this state, when the secondary side current starts to increase gradually, the cathode potential of the diode 14 changes accordingly, and a voltage corresponding to the change is supplied to the power supply circuit 22.
Is applied to the secondary side control circuit 22 and the secondary side control circuit 23
Switches the transistor 32 of the signal transmission load circuit 21. In accordance with the switching of the transistor 32, a switching current flows from the cathode of the diode 16 to the output terminal 19b through the resistor 33, and the secondary current fluctuates. Accordingly, the secondary current of the output transformer 4 changes from the secondary side to the primary side. It is transmitted by electromagnetic induction coupling without contact.

With this electromagnetic induction coupling, on the primary side of the output transformer 4, a primary current flows through the diode 9 to the resistor 7, causing a voltage drop across the resistor 7. The voltage at one end of the resistor 7 is applied to each input terminal of the operational amplifiers 28 and 29. However, the current flowing through the resistor 7 is no much change during the no-load state until the I _1, as shown in FIG. 4, the power of the secondary side has not been so high. From this state, on the secondary side of the output transformer 4, the load current gradually increases, so that the potential of the cathode of the diode 14 starts to decrease. Accordingly, the secondary side control circuit 23 also switches the transistor 32 of the signal transmission load circuit 21.
Gradually decrease the switching frequency.

This switching action is transmitted to the primary winding 4a in accordance with the switching action of the transistor 32 due to the decrease in the frequency.
Incrementally current flowing in is equal to or current I ₁ as shown in FIG. 4, the potential of one end of the resistor 7 is also decreased, the potential is applied to the input of the operational amplifier 29, the current from the output terminal of the operational amplifier 29 A voltage corresponding to I ₁ is applied to the control circuit 30. Thereby, the control circuit 30 changes the oscillation frequency of the oscillation circuit 12 based on the applied voltage. That is, it is lowered from the steady state. The MOS transistor 6 performs the switching operation at the reduced oscillation frequency, and the current flowing through the MOS transistor 6 increases by the reduction of the switching frequency.

Therefore, the current flowing through the primary winding 4a is also increased, and the power supplied to the secondary side becomes like the small power PS1 in FIG. That is, power can be supplied to the secondary side in the small power mode. In this power saving mode, the switch circuit 18 is controlled by the secondary side control circuit 23.
, The secondary side power can be intermittently supplied to the load. In the switching operation of the transistor 26, the capacitor 27 is charged during the ON period and discharged to the load during the OFF period.
7, the power is supplied to the load by the discharge, and thus the operation of the load is not affected. That is,
Voltage is constantly applied to the load.

As described above, the load current gradually increases from the state where the current I ₁ is detected by the operational amplifier 29, and the potential of the cathode of the diode 14 further decreases. When the switching speed of the transistor 32 of the signal transmission load circuit 21 decreases, the current of the secondary winding 4b also gradually increases, and the primary winding 4
a, the voltage applied to the input terminal of the operational amplifier 28 corresponding to the current flowing through the resistor 7 through the diode 9 also gradually increases. When the current flowing through the resistor 7 exceeds the current Is, the voltage at the input terminal of the operational amplifier 28 also changes in the same manner as described above, and a voltage corresponding to the current Is is generated at the output terminal of the operational amplifier 28. Applied to the control circuit 30.

The control circuit 30 uses this voltage to control the oscillation circuit 1
2, the MOS transistor 6 is switched at the reduced oscillation frequency, and the switching current of the MOS transistor 6 is increased by an amount corresponding to the reduction of the switching cycle. As a result, the output transformer 4
As shown in FIG. 4, the current supplied to the secondary winding of the output transformer 4 also gradually increases in the small power mode. In this case, as in the above case, the operation of the capacitor 27 is charged when the transistor 26 is turned on, and is discharged to the load when the transistor 26 is turned off.

Next, the operation in the high power mode will be described. The basic operation is the same as that in the low power mode, except that the load current on the secondary side is further increased, and the voltage across the secondary winding 4b is reduced by that much. Of the cathode is further reduced from the above. The secondary-side control circuit 21 having received the decrease in the cathode potential of the diode 14 causes the transistor 24 of the signal transmission load circuit 20 to perform a lower-speed switching operation.

In response to this low-speed switching operation, 1
This switching action is transmitted to the next winding 4a side, and the current flowing through the operational amplifier 28 increases and becomes equal to or greater than the current IS as shown in FIG. 4, and the output terminal of the operational amplifier 28 responds to the increased current. The voltage is received by the signal receiving circuit 31, and the output of the signal receiving circuit 31 is applied to the control circuit 30. This allows the control circuit 30 to operate in the same manner as described above.
Lowers the oscillation frequency of the oscillation circuit 12 and causes the MOS transistor 6 to switch with the lowered oscillation signal. Accordingly, the current flowing through the primary winding 4a increases, and a large amount of power PL is supplied to the secondary side of the power supply circuit as shown in FIG.

As is clear from the above, also in the second embodiment, when there is no load or light load, a signal having a high signal frequency is transmitted from the secondary side without contact, and the power supplied to the secondary side is reduced. When the power is reduced and the load becomes heavy, a low-frequency signal is transmitted to the primary side in a contactless manner to supply large power from the primary side to the secondary side. Sometimes, power is saved, so that wasteful power consumption and heat generation are prevented, as in the first embodiment.
Deterioration of components due to heat generation can be prevented. In FIG. 3, the diode 17 can be replaced by a transistor. In this case, the transistor is turned on by a signal from the secondary side control circuit 23.

Next, a third embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of the third embodiment. In the third embodiment, the secondary side of the output transformer 4 has the same configuration as that of the second embodiment, in contrast to the configuration of the second embodiment shown in FIG. Is different from the second embodiment. That is, in the third embodiment, the oscillation circuit 12 has a single function as the oscillation circuit for the inverter, and the intermittent operation of the inverter depends on the conduction angle control of the thyristor.

Accordingly, the primary side control means 13 is different from that of FIG. In FIG. 5, the capacitor 5 shown in FIG. 3 is omitted, and operational amplifiers 28 and 29 are connected to the connection point between the resistor 7 and the source of the MOS transistor 6.
Are connected to each other. Operational amplifiers 28, 29
Are connected to ground. When the load on the secondary side of the output transformer 4 becomes heavy, the signal generated on the secondary side is received by the primary winding 4a of the output transformer 4 and the diode 9
Through the resistor 7, a voltage drop occurs across the resistor 7. The potential at one end of the resistor 7 fluctuates according to this voltage drop. This fluctuation of the potential causes the operational amplifier 28,
29 is applied to the inverting input terminal. The operational amplifier 28 outputs a voltage corresponding to the potential applied to the inverting input terminal to the signal receiving circuit 31, and the operational amplifier 29 outputs a voltage to the on-operation stop circuit 37 according to the input voltage. It has become. The operational amplifiers 28 and 29, the diode 9, and the resistor 7 constitute current detecting means.

When the output voltage of the operational amplifier 28 is input to the signal receiving circuit 31, the signal is output to the ON operation circuit 34. This ON operation circuit 34 is a signal receiving circuit 3
The thyristor 3 serving as a main component of a switching circuit 35 to be described later for the control circuit 30 by inputting the output of the thyristor 3
6 is fired in the normal state from the intermittent operation and 2
The power supply to the next side is set to the high power mode.
When a current smaller than the current flowing through the operational amplifier 28 flows through the resistor 9 to the resistor 7, the operational amplifier 29 supplies a voltage corresponding to the current to the ON operation stop circuit 37.
Output. ON operation stop circuit 3
7, when the output voltage of the operational amplifier 29 is input to the ON operation circuit 34, the control circuit 30
The ignition control by the intermittent operation is performed from the normal ignition of No. 6.

The ON operation circuit 34 and the ON operation stop circuit 37 can be realized by performing a switching operation using a transistor or the like. The output of the intermittent operation circuit 38 is input to the control circuit 30. The intermittent operation circuit 38 is configured such that a pulse signal is generated intermittently by a flip-flop circuit, a sawtooth wave generating circuit, or the like. During the period in which the pulse is generated intermittently, that is, only during the turn-on period of the thyristor, which will be described later, the primary voltage is transformed by the output transformer 4 so as to perform the inverter operation at the oscillation frequency of the oscillation circuit 12 so as to perform the secondary operation. Side is supplied with power. At this time, the low power mode is set.

The control circuit 30 controls the intermittent operation circuit 3 while the ON operation signal is not being input from the ON operation circuit 34.
The thyristor 36 is controlled to fire by intermittent operation in response to an intermittent operation pulse signal from the control unit 8. The primary control unit 13 is configured by the ON operation circuit 34, the ON operation stop circuit 37, the signal receiving circuit 31, and the intermittent operation circuit 38. The anode of the thyristor 35 is connected to the positive output terminal of the full-wave rectifier circuit 2. The cathode of the thyristor 35 is connected to one end of the primary winding 4a of the output transformer 4. The control circuit 3 is connected to the gate of the thyristor 35.
By applying the intermittent signal from the intermittent operation circuit 38 to the gate under the control of 0, the thyristor 35 can perform the switching operation by the intermittent operation. That is,
The output voltage of the full-wave rectifier circuit 2 is applied to the primary winding 4a of the output transformer 4 only during the ON period of the thyristor 36, and the electric power supplied to the primary winding 4a correspondingly during normal thyristor ignition control Is reduced.

When the thyristor 36 is turned on, the output current of the full-wave rectifier circuit 2 becomes the primary winding 4a of the output transformer 4.
Will be energized. By controlling the phase of the output signal of the control circuit 30 applied to the gate, the conduction angle of the thyristor 35 is controlled, thereby controlling the primary winding 4a.
The control of the cycle of the switching current flowing through the switch, and thus the primary winding current, is performed. FIG. 6 shows a switching circuit 35 mainly composed of the thyristor 36 and a control circuit 30.
FIG. 3 is a circuit diagram showing a circuit configuration of a part of FIG.

In FIG. 6, the switching circuit 35
Thyristor 3 is connected between the positive output terminal of full-wave rectifier circuit 2 and one end of primary winding 4a of output transformer 4 as described above.
5 is connected. A resistor 39 is connected between the gate and the anode of the thyristor 36, and a resistor 40 is connected between the gate and the cathode. The gate is connected to the collector of the transistor 42 of the control circuit 30 through the resistor 41.

A series circuit of resistors 43 and 44 is connected between the cathode of the thyristor 36 and the ground. The connection point between the resistors 43 and 44 is grounded via a series circuit of a constant voltage diode 45 and a resistor 46. A connection point between the constant voltage diode 45 and the resistor 46 is connected to the base of the transistor 42 via a resistor 47. The emitter of the transistor 42 is grounded. The output of the ON operation circuit 34 shown in FIG. 5 is applied to the base of the transistor 48. The collector of transistor 48 is connected to the base of transistor 42. The emitter of transistor 48 is grounded.

Next, the operation of the third embodiment will be described. The AC voltage of the AC power supply connected to the input terminals 1a and 1b is full-wave rectified by the full-wave rectifier circuit 2, and
(A) A full-wave rectified voltage as shown at the positive output terminal of the full-wave rectifier circuit 2 is applied to the anode of the thyristor 36. In this state, while the ON operation signal is not being input from the ON operation circuit 34 to the control circuit 30, that is, the current of the load signal is small, and the ON operation stop circuit 37 turns ON the ON operation circuit 34 by the output of the operational amplifier 29. While the output of the operation signal is stopped, a pulse signal is input from the intermittent operation circuit 38 to the control circuit 30 at regular intervals. Every time this pulse signal is input to the control circuit 30, the control circuit 30 applies the pulse signal to the gate of the thyristor 36 as an ignition signal to perform an intermittent operation of the thyristor 36.

As a result, the thyristor 36 performs an intermittent operation, and as shown in FIG. 7B, the output voltage of the full-wave rectifier circuit 2 is applied to the primary winding of the output transformer 4 only while the thyristor 36 is turned on. 4a. This FIG.
(B) As is clear, the output voltage of the full-wave rectifier circuit 2 is applied to the primary winding 4a only during the period of the pulse width Δt output from the intermittent operation circuit 38. Even in this state, the MOS transistor 6 is switched by the output signal of the oscillation circuit 12, and the output voltage of the thyristor 36 is chopped at the switching frequency to change DC power to AC power.

FIG. 7C shows an enlarged view of one conduction period of the thyristor 36, that is, only one output pulse of the intermittent operation circuit 38, and only the period of the pulse width Δt of this output pulse. The oscillation frequency of the oscillation circuit 12 is M
The power is converted into AC power by switching of the OS transistor 6. Only during the period of the pulse width Δt is converted into AC power, the AC voltage transformed by the output transformer 4 is rectified by the diodes 14 and 16, and the DC voltage smoothed by the capacitor 15 is applied to the power supply circuit 22. Then, the secondary side control circuit 23 operates to turn on the switch circuit 18.

Thus, the rectified voltage on the secondary side is applied to the load connected between the output terminals 19a and 19b through the switch circuit 18. At the same time, the transistor 32 of the signal transmission load circuit 21 is turned on by the output of the secondary side control circuit 23, and a current flows through the resistor 33 during the on operation. The current flowing through the resistor 33 is shown in FIG. FIG. 7D and FIG.
As can be seen from (c), the current flowing through the resistor 33 is in each conduction period of the thyristor 36, in other words, the thyristor 3
6 is a current during a period in which electric power is supplied from the primary side to the secondary side while turning.

The current of the resistor 33 is constant even in the no-load state, the current of the load signal corresponding thereto is superimposed, and the current of the resistor 33 also changes according to the change of the load.
FIG. 7D shows a state where the current of the pulse-shaped load signal is superimposed. The current of the pulse-shaped load signal is transmitted to the primary side without contact by the electromagnetic induction coupling between the primary side and the secondary side by the output transformer 4. In response to the load signal current generated in the signal transmission load circuit 21 shown in FIG. 7D, a pulse-like current is applied from the secondary side to the primary side by electromagnetic induction coupling as shown in FIG. 7E. A signal is transmitted.

A current corresponding to the current of the load signal transmitted to the primary side flows through the diode 9 and the resistor 7. The potential at one end of the resistor 7 changes in accordance with the current flowing through the resistor 7, and the changed potential is also applied to the inverting input terminals of the operational amplifiers 28 and 29, as shown in FIG. Of the load signal is detected in accordance with the current flowing through the load signal. That is, when the load is light or no load, the resistance 7
, The voltage drop across it is small, and the voltage applied to each inverting input terminal of the operational amplifiers 28 and 29 is small.

Therefore, the operational amplifier 28 for detecting a large current
Does not generate an output voltage, the signal receiving circuit 31 is in a non-operation state, and the ON operation circuit 34 is also in a non-operation state. At this time, the input voltage of the operational amplifier 29 is also low, the output voltage is not generated, and the on-operation stop circuit 37 is in a non-operating state. In other words, the entire circuit is in the same state as the initial state, and the thyristor 36 is controlled to be conductive by the control circuit 30 at regular intervals of the pulse output from the intermittent operation circuit 38.

FIG. 8A shows the output voltage waveform of the full-wave rectifier circuit 2 at this time, and FIG. ), Indicating that the firing phase angle has not been shifted. As shown in FIG. 8C, the output voltage of the thyristor 36 at this time is such that the power supplied to the load is in the low power mode.

Next, the operation when the load current is increased and the mode is set to the high power mode will be described. In this case, the amplitude of the pulse-like load signal current superimposed on the current flowing through the resistor 33 shown in FIG. The detection current also increases, and the current flowing through one end of the resistor 7 increases. Therefore, the voltage drop of the resistor 7 increases, and the voltage is applied to the inverting input terminals of the operational amplifiers 28 and 29. When the load current increases and the voltage at the inverting input terminal of the operational amplifier 28 increases by a predetermined amount or more, the output voltage of the operational amplifier 28
1 operates to drive the ON operation circuit 30, whereby an output signal is sent to the control circuit 30.

The control circuit 30 is configured as shown in FIG. 6. The ON signal is output from the ON operation circuit 30 and the resistor 43 is connected to the base of the transistor 42 until the ON signal is applied to the base of the transistor 48. Thyristor 3 at 44
The voltage obtained by dividing the output voltage of No. 6 is made constant by the constant voltage diode 5, applied through the resistor 47, and the transistor 42 is turned on. That is, the base potential of the transistor 42 is kept constant,
2 keeps the ON state, and the gate of the thyristor 36 has a resistor 39 at every half cycle of the output voltage of the full-wave rectifier circuit 2.
The turn is repeated at a phase determined by ~ 41.
That is, an intermittent operation is performed. FIGS. 8B and 9A show the state at this time.

From this state, the output of the operational amplifier 28 causes the signal receiving circuit 31 to increase due to an increase in the load signal current.
Is driven to operate the ON operation circuit 34 to apply an ON signal to the base of the transistor 48.
8 turns on, the base potential of the transistor 42 becomes the ground potential, and the transistor 42 turns off. Therefore, the ignition phase shift control of the thyristor 36 is stopped, and FIG.
(B), as shown in FIGS. 8 (c) and 9 (a), the intermittent operation is eliminated and the voltage E0 on the cathode side of the thyristor 36 is eliminated.
As shown in FIG. 9 (a), the constant height E0 = EV, and as shown in FIG. 9 (b), the output voltage waveform of the thyristor 36 becomes a full-wave sine wave with a constant conduction angle. . As a result, the power supplied from the primary side to the secondary side of the output transformer 4 enters the high power mode.

When the mode is changed from the high power mode to the low power mode again, the transistor 32 of the signal transmission load circuit 21 is turned on under the control of the secondary side control circuit 23 and the resistor 33 is turned on.
7D, a voltage corresponding to the current flowing from the primary winding 4a of the output transformer 4 through the diode 9 to the resistor 7 is applied to the inverting input terminal of the operational amplifier 29. You. When the input voltage reaches a predetermined voltage, the on-operation stop circuit 37 is driven by the output voltage of the operational amplifier 29.

As a result, the operation of the ON operation circuit 34 is stopped. As a result, the transistor 48 in the control circuit 30 shown in FIG. 6 is turned off, the transistor 42 is turned on, and the thyristor 36 is turned on in FIG. , FIG. 9 (a)
The operation in the state of is performed. Also in the third embodiment, the second
The same effects as in the embodiment can be obtained. That is, at the time of light load or no load, large power is not supplied from the primary side to the secondary side, so that generation of heat due to large power can be prevented,
Deterioration due to high temperature of the parts can be prevented.

Next, a fourth embodiment of the present invention will be described. FIG. 10 is a block diagram showing a configuration on the secondary side in the fourth embodiment. In the fourth embodiment, the configuration of the primary side is the same as that of the third embodiment shown in FIG. In the description of the configuration of the secondary side, the same parts as those in FIG. A capacitor 50 is connected between both ends of the secondary winding 4b of the output transformer 4. One end of the secondary winding 4b is connected to diodes 16, 17
Is connected to the emitter of the transistor 26 of the switch circuit 18. The collector of the transistor 26 is connected to the output terminal 19a.

The multi-terminal of the secondary winding 4b is grounded and connected to the output terminal 19b. The output terminals 19a,
A load 49 is connected between 19b. This load 4
9 corresponds to, for example, a charger or a set load. A charge / discharge capacitor 54 is connected between the cathode of the diode 17 and the output terminal 19b. A secondary side control circuit 23 is connected between the cathode of the diode 17 and the output terminal 19b, that is, in parallel with the capacitor 20.

The cathode of the diode 16 and the output terminal 19
b, a signal transmission load circuit 21 is connected. This signal transmission load circuit 21 is configured by connecting a resistor 33 and a transistor 32 in series. The output of the secondary-side control circuit 23 is input to the base of the transistor 32, and the output of the secondary-side control circuit 23 performs an on / off switching operation.

Further, the base of the transistor 26 of the switch circuit 18 is connected to the transistor 5 of the stop circuit 51.
2 collectors are connected. The emitter of the transistor 52 is connected to the output terminal 19b via the resistor 53. The output of the secondary control circuit 23 is applied to the base of the transistor 52. That is,
The stop circuit 51 includes a transistor 52 and a resistor 53. The transistor 52 is turned on when the output of the secondary side control circuit 23 is applied, thereby turning on the transistor 26 of the switch circuit 18, The power supply to the load 49 is enabled. Note that both output terminals 19
The charge / discharge capacitor 54 is charged between a and 19b while the switch circuit 18 is on. When the switch circuit 18 is turned off, the capacitor 54 is discharged to the load 49 until the switch circuit 18 turns from off to on. , The operation state of the load 49 is maintained.

With this configuration, when power is transmitted from the primary side (not shown) to the secondary winding 4b of the output transformer 4, the voltage is transformed by the secondary winding 4b and the diode 1
It is rectified by 6 and 17 and smoothed by the capacitor 20. When the DC voltage at both ends of the capacitor 20 is applied to the secondary control circuit 23, the secondary control circuit 23 becomes operable. In this state, when the transistor 52 of the stop circuit 51 is turned on by the output of the secondary side control circuit 23, the transistor 26 of the switch circuit 18 is turned on, and the DC voltage smoothed by the capacitor 20 is applied to the load 49. .

Also, the output of the secondary side control circuit 23
When the transistor 32 of the signal transmission load circuit 21 is turned on, a current always flows through the resistor 33 and the transistor 32 through the signal transmission load circuit 21. In this state,
The power is supplied to the load 49, and the signal transmission load circuit 21 is supplied to the signal transmission load circuit 21 in accordance with the load current of the load 49.
In addition to the current itself, a pulse-like load signal current corresponding to the load current is superimposed as shown in FIG. When transmitting this load signal to the primary side as in the above-described embodiments, the transistor 52 of the stop circuit 51 is turned off by the secondary side control circuit 23.

As a result, the load signal of the signal transmission load circuit 21 is coupled to the output transformer 4 by electromagnetic induction coupling.
It can be transmitted to the next winding side. Hereinafter, the operation on the primary side is the same as that of the third embodiment. While the transistor 26 of the switch circuit 18 is off, the capacitor 54 is discharging to the load 49, and the secondary side control circuit 23 again controls the transistor 52 of the stop circuit 51.
Is turned on and the switch circuit 18 is turned on, the capacitor 54 starts charging. This switch circuit 18
Is turned on, the capacitor 54 starts charging and the transmission of the load signal of the signal transmission load circuit 21 to the primary side is stopped. The above operation is repeated.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a block diagram showing the configuration of the fifth embodiment. In FIG. 11, the same parts as those in the embodiments shown in FIGS. 1, 3 and 5 are denoted by the same reference numerals. Input terminals 1a, 1
b, an AC power supply is connected, and between the input terminals 1a and 1b,
The input terminal of the full-wave rectifier circuit 2 is connected via the switch 55. A smoothing capacitor 3 is connected between the positive output terminal and the negative output terminal of the full-wave rectifier circuit 2, and the positive output terminal is connected to a switching circuit via a primary winding 4 a of an output transformer 4. 56.

As described in the above embodiments, the switching circuit 56 corresponds to a circuit including a MOS transistor, a diode connected in parallel to the MOS transistor, and a current detecting resistor connected in series to the diode. . The switching circuit 56 performs switching in accordance with the oscillation frequency of the oscillation circuit 12, converts the DC voltage into an AC voltage by chopping the DC voltage generated at both ends of the capacitor 3 and flowing through the primary winding 4 a of the output transformer 4. In addition, the oscillation circuit 12, the switching circuit 56, and the output transformer 4 function as an inverter. Also,
As described in the above embodiments, the switching circuit 56 also allows the current of the load signal transmitted from the secondary side by contactless electromagnetic coupling to the series circuit of the diode and the resistor. .

This load signal is detected by the current detection circuit 57. The detection result by the current detection circuit 57 is received by the signal reception circuit 31. As the signal receiving circuit 31, for example, it is possible to make a determination according to the input level by using the switching action of a transistor. Signal receiving circuit 3
1 is input to the control circuit 30. The control circuit 30 controls the oscillation frequency variable circuit 11 according to the output of the signal receiving circuit 31. The signal receiving circuit 31 changes the oscillation frequency of the oscillation circuit 11 under the control of the control circuit 30.

Next, the configuration of the secondary side will be described. One end of the secondary winding 4b of the output transformer 4 is connected to a diode 16,
It is connected to the output terminal 19a through the switch circuit 18. The other end of the secondary winding 4b is connected to the output terminal 19b. The signal transmission load circuit 21 and the switch circuit 58 are connected between the output terminal 19b and the cathode of the diode 16. As the switch circuit 58, a switch circuit such as the switch circuit 18 can be used.

A signal generation circuit 59 is provided. The signal generating circuit 59 receives a signal from the load 49. As the load 49, for example, a temperature detector, a charge stop signal generator, a load of the contactless power supply circuit itself, and the like are applicable. When the signal from the load 49 is input to the signal generation circuit 59, the operation of the switch circuit 58 and the operation of the stop circuit 51 are controlled. The stop circuit 51 is the same as the stop circuit of the fourth embodiment. The stop circuit 51 performs on / off control of the switch circuit 18.
The signal generation circuit 59, the stop circuit 51, and the switch circuit 58 constitute secondary side control means similar to the secondary side control means in the first to fourth embodiments.

Next, the operation of the fifth embodiment will be described with reference to the flowchart of FIG. First, when the switch 55 is turned on (step S1), the switch 5
The voltage of the AC power supply is applied to the full-wave rectifier circuit 2 through 5, where it is full-wave rectified and smoothed by the capacitor 3.
The DC voltage smoothed by the capacitor 3 is applied to the primary winding 4a of the output transformer 4. At the same time, the switching circuit 56 switches in the low power mode at the oscillation frequency of the oscillation circuit 12 to convert a DC voltage to an AC voltage, and the AC voltage induced by the output transformer 4 and induced in the secondary winding 4b is a diode 16 , 17 rectified switch circuit 1
8 and applied to the load 49 (step S2).

In this state, the switch circuit 58 is off, and the stop circuit 51 is inactive. Therefore, no current flows to the signal transmission load circuit 21 through the switch circuit 58. In the low power mode, when the load 49 is a charge stop circuit or the like, an output signal is output from the load 49 to the signal generation circuit 5.
9 is not output. Thereby, the signal generation circuit 59
Stops the operation of the stop circuit 51, that is, turns off. As a result, the switch circuit 18 turns off (Step S3).

When the switch circuit 18 is turned off, the supply of power to the load 49 is cut off, and a signal is output from the load 49 to the signal generation circuit 59 (step S4).
At the same time, the switch circuit 58 is turned on by the signal from the load 49 to the signal generation circuit 59 (step S5).
As a result, the switch circuit 58 is switched through the switch circuit 58.
The current flows through the load circuit 21 for signal transmission, and the load signal corresponding to the load current is superimposed on the load circuit 21 for signal transmission. This load signal is generated by electromagnetic induction coupling of the output transformer 4,
It is transmitted from the secondary side to the primary side. This load signal flows from the primary winding 4a of the output transformer 4 to the current detection circuit 57 via the diode of the switching circuit 56, and the current on the primary side is detected (step S6).

If the detected current is not the current due to the secondary side or the transmitted load signal (step S
7), the process returns to step S2. When the detection result is a current based on a load signal, the output of the current detection circuit 57 is received by the signal reception circuit 37 and output to the control circuit 30. The control circuit 30 that has received the output of the signal receiving circuit 37 controls the oscillation frequency variable circuit 11 to lower the oscillation frequency of the oscillation circuit 12. That is, a large current is caused to flow through the primary winding 4a (step S8).

Thus, the secondary winding 4 of the output transformer 4
A large current starts to flow through b, and a high power mode operation is performed (step S9). Next, the operation of the switch circuit 58 is stopped by the signal generation circuit 59. That is, it is turned off (step S10). When the switch circuit 58 is turned off, no current flows through the load circuit 21 for signal transmission, and accordingly, no load signal flows.

The stop circuit 51 is turned on by the signal generation circuit 59, and the switch circuit 18 is turned on by the stop circuit 51 (step S11). Since then
Similarly to the processing of step S6, the current flowing to the primary winding 4a side is detected (step S12).
The process returns to step S12. That is, detection of this current is continued. If the result of the current detection determination in step S13 is that the current value is the reference value, the process returns to step S2.

Next, a sixth embodiment of the present invention will be described. FIG. 13 is a block diagram showing the configuration of the sixth embodiment. In FIG. 13, the same parts as those of the fifth embodiment shown in FIG. In FIG. 13, the configuration of the secondary side is the same as that of FIG. 10 except that the load 49 is not shown.

On the primary side, a switch 55,
A full-wave rectifier circuit 2, a capacitor 3, a primary coil 4a, an oscillation circuit 12, a switching circuit 56, a current detection circuit 57,
Are the same as those in FIG. The following points are shown in FIG.
Is a different part. That is, the output of the current detection circuit 57 is output to the signal receiving circuit 31 and also to the switch circuit off intermittent operation circuit 60. The output of the switch circuit off intermittent operation circuit 60 is output to the switch circuit on operation circuit 61 and the simple operation circuit 62. The output of the signal receiving circuit 31 is output to the intermittent operation stop circuit 63 and the switch circuit control operation circuit 61.

The intermittent operation stop circuit 63 receives the output of the signal receiving circuit 31 and outputs it to the intermittent operation circuit 62. The intermittent operation circuit 62 outputs the intermittent operation signal to the switch circuit 64 when the intermittent operation signal from the switch circuit off intermittent operation circuit 60 is input, and receives the stop signal from the intermittent operation stop circuit 63. Then, the intermittent operation is stopped and the switch circuit 64 is turned on. Switch circuit 64
Perform an intermittent operation, and when a switch circuit off signal from the switch circuit off intermittent operation circuit 60 is input, the switch circuit 64 is turned off. The primary side control means 13 is constituted by the current detection circuit 57, the signal reception circuit 31, the intermittent operation stop circuit 63, the switch circuit ON operation circuit 61, the switch circuit OFF intermittent operation circuit 60, and the intermittent operation circuit 62.

Next, the operation of the sixth embodiment will be described with reference to the flowchart of FIG. When the switch 55 is turned on in step S21, the AC voltage from the AC power supply is full-wave rectified by the full-wave rectifier circuit 2 through the switch 55, and is smoothed by the capacitor 3. Next, the intermittent operation circuit 62 operates by the output of the switch circuit off intermittent operation circuit 60, and causes the switch circuit 64 to perform an intermittent operation (step S22).

When the switch circuit 64 performs the intermittent operation, the full-wave rectified by the full-wave rectifier circuit 2, and the DC voltage smoothed by the capacitor 3 passes through the switch circuit 64 intermittently, and the voltage of the output transformer 4 It flows to the next winding 4a. At this time, by switching the switching circuit 56 according to the oscillation frequency of the oscillation circuit 12, the DC voltage is converted to an AC voltage, and the AC voltage transformed by the output transformer 4 is generated at both ends of the secondary winding 4b. . This AC voltage is rectified by the diode 16, smoothed by the capacitor 20, and supplied intermittently to the load (not shown) through the switch circuit 18 in response to the intermittent operation of the switch circuit 64.

In this state, the stop circuit 51 is operated by the signal generation circuit 59 to turn off the switch circuit 18 (step S23). At the same time, when the switch circuit 58 is turned on by the signal generation circuit 59, the DC current smoothed by the capacitor 20 flows through the switch circuit 58 to the signal transmission load circuit 21, and as shown in FIG. A load signal is superimposed (step S24). This load current is induced on the primary winding 4a side by the electromagnetic induction coupling of the output transformer 4, and flows through the switching circuit 56 and the current detection circuit 57.

The load signal current flowing through the switching circuit 56 is detected by the current detection circuit 57 (step S25). It is determined whether or not the detection result of the current detection circuit 57 is a load signal current (step S26). If the result of this determination is not a load signal current, the process returns to step S22. If the result of the determination is the current detection circuit 57,
The signal receiving circuit 31 outputs to the intermittent operation circuit 60. As a result, the intermittent operation stop circuit 63
And the intermittent operation circuit 62 stops the intermittent operation of the switch circuit 64 (step S27).

Simultaneously with the stop of the decision operation of the switch circuit 64, the output of the signal receiving circuit 31 drives the switch-on operation circuit 61, whereby the switch circuit 6
4 performs an ON operation (step S28). When the switch circuit 64 performs the ON operation, the DC power full-wave rectified by the full-wave rectifier circuit 2 supplies a large amount of power to the secondary side via the output transformer 4. At the same time when the switch circuit 64 is turned on, the signal generation circuit 59 causes the switch circuit 5 to operate.
Turning off 8 turns off the signal transmission load circuit 21. As a result, the load signal becomes 1 from the secondary side.
The transmission to the next side is stopped (step S29).

The stop circuit 51 is driven by the signal generation circuit 59 at the same time when the switch circuit 58 is turned off. By driving the stop circuit 51, the stop circuit 51
Turns on the switch circuit 18 (step S30).
When the switch circuit 18 is turned on, a large amount of power is supplied to the load. In this way, by performing the above-described series of processing, it is possible to perform transmission control of the load signal, detection processing thereof, intermittent supply of power to the secondary side, and switching control of continuous and large power supply. Steps S21 to S3
When a series of processes up to 0 is completed, a load signal transmitted from the secondary side to the primary side is detected in step S31 in the same manner as in step S25 again. If the signal is equal to or less than the predetermined reference (step S32), the process returns to step S22. If not, the process returns to step S29.

Next, a seventh embodiment of the present invention will be described. FIG. 15 is a block diagram showing the configuration of the seventh embodiment. In FIG. 15, the same portions as those in the above embodiments are denoted by the same reference numerals and described. FIG.
, The AC voltage of the AC power supply is full-wave rectified by the full-wave rectifier circuit 2 and applied to one end of the primary winding 4a of the output transformer 4 via the thyristor 36 of the switching circuit 35. The other end of the primary winding 4a is grounded via a parallel circuit of a MOS transistor 6, a resistor 7 and a capacitor 8, as in the first to third embodiments.

The diode 9 is connected between the drain and the source of the MOS transistor 6, and the capacitor 5 is connected between the drain and the ground. A voltage corresponding to the current of the load signal generated at one end of the resistor 7 is applied to the input terminal of the current detection circuit 57. The output of the current detection circuit 57 is output to the signal receiving circuit 31. The output of the signal receiving circuit 31 is output to the phase control circuit 65. Phase control circuit 65
Is output to the control circuit 30.

A timer 66 is provided, and the output of the timer 66 is sent to the 1 o'clock stop circuit 67. The timer 66 sets the time Δt
The operation is set to stop only for the time, and is a timer for setting the time for stopping the supply of power from the primary side to the secondary side for this At time. The timer 66 drives the 1 o'clock stop circuit 67 simultaneously with the start of the setting of the time Δt. The output of the 1 o'clock stop circuit 67 is sent to the oscillation circuit 12. The output of the one-time stop circuit 67 is
The oscillation circuit 12 stops the oscillating operation while being supplied to the oscillating circuit. The primary side control means 13 is composed of the current detection circuit 57, the signal reception circuit 31, the phase control circuit 65, the timer 66, the 1 o'clock stop circuit 67, and the control circuit 30.

Next, the configuration of the secondary side will be described. A diode 14 and a capacitor 1 are connected between both ends of the secondary winding 4b.
5, and a series circuit of a diode 68 and a capacitor 69 is connected in parallel. A circuit power supply 70 is connected to a connection point between the diode 68 and the capacitor 69. The circuit power supply 70 is provided for applying a predetermined operating voltage to another circuit using a DC voltage rectified and smoothed by the diode 68 and the capacitor 69 as an input voltage.

The diode 14 has a cathode connected to a load 49 such as a charger through the switch circuit 18. A detection circuit 71 is connected between the cathode of the diode 14 and the ground. The detection circuit 71 is provided to detect whether or not the secondary-side circuit has stopped operating during the time set by the timer 66.

The output of the detection circuit 71 is sent to an on / off control circuit 72. The on / off control circuit 72 receives the output of the detection circuit 71,
The on / off control of the switch circuit 18 is performed. A signal transmission load circuit 21 is connected between the cathode of the diode 14 and the ground. The signal generation circuit 59 controls the operation of the signal transmission load circuit 21, that is, controls whether the load signal is supplied or cut off.

Next, the operation of the seventh embodiment will be described with reference to the flowchart of FIG. In step S41, an AC voltage of an AC power supply is applied to the full-wave rectifier circuit 2. At the beginning of the startup, the switching circuit 35 fired by the control circuit irrespective of the phase control circuit 65
DC voltage rectified through the thyristor 36 is smoothed by the capacitor 3, and the primary winding 4a of the output transformer 4 is
Is applied to At this time, the timer 66 is in a non-operating state, and the 1 o'clock stop circuit 67 is not restricted by the timer 66, so that the operation stop operation of the oscillation circuit 12 is not performed.

Therefore, oscillation circuit 12 causes MOS transistor 6 to perform a switching action at a predetermined oscillation frequency. As a result, the output voltage of the thyristor 36 is chopped, DC power is converted to AC power, and is transformed by the output transformer 4 to generate an AC voltage at both ends of the 2 o'clock winding 4b. As described above, the thyristor 36 is in the high power mode when the phase control by the phase control circuit 65 is not performed (step S42). In the high power mode, the DC voltage rectified on the secondary side by the diode 14 and smoothed by the capacitor 15 is supplied to the detection circuit 7.
1 indicates that the high power mode operation is being performed, and the on / off control circuit 72 sets the switch circuit 18 to the on state.

Therefore, power is supplied to the load 49 through the switch circuit 18 in the large power mode.
In this high power mode, the timer 6 starts operating (step S43), and when the time t has elapsed (step S43).
44), so that the operation is stopped for Δt time (Step S
45) The timer 66 drives the 1 o'clock stop circuit 67. As a result, the 1 o'clock stop circuit 67 is
And the control circuit 30 turns off the thyristor 36 only at the time Δt.

At the same time, the one-time stop circuit 67 stops the oscillation operation of the oscillation circuit 12 for the time Δt. FIG. 17 shows this state. In this way, when the operations of the thyristor 36 and the oscillation circuit 12 are stopped, the supply of power from the primary side to the secondary side is stopped for Δt. When the supply of power to the secondary side is stopped, the detection circuit 71 detects this (step S46).

As a result of this detection, it is determined whether or not the voltage on the secondary side, that is, the voltage across the capacitor 15 is a zero volt voltage (step S47). As a result of this judgment,
If the voltage is not zero volt, the process returns to step S46 again. If the result of the determination is zero volt, the detection circuit 71 drives the on / off control circuit 72. Thereby, the on / off control circuit 72 turns off the switch circuit 18 (step S48). Next, when the time Δt set by the timer 66 elapses, the operation of stopping the operation of the control circuit 30 and the oscillation circuit 12 by the primary stop circuit 67 is released.

At the same time, the thyristor 36 is turned by the control circuit 30 and the oscillation circuit 12 restarts oscillating. And a predetermined AC voltage is generated at both ends of the secondary winding 4b. This AC voltage is rectified by diodes 14 and 68 and smoothed by capacitors 15 and 69, respectively. The cathode voltage of the diode 14 is
1 is detected. Since a voltage is generated at the cathode of the diode 14, the output signal of the detection circuit 71 drives the on / off control circuit 72.

When the on / off control circuit 72 is driven, the switch circuit 18 is turned on, power is supplied to the load 49 through the switch circuit 18, and the load 49 is driven in the small power mode (step S49). In this state, if the load 49 is a charger, a signal from the load 49 is input to the signal generation circuit 59 in a no-load state due to the end of charging or a light load state. By driving the signal transmission load circuit 21, the signal transmission load circuit 21 is connected between the cathode of the diode 14 and the ground, and is turned on. Therefore, the load of the signal transmission load circuit 21 is loaded with its own current.
9 is a load signal corresponding to the load current flowing through the circuit 9 in FIG.
(Step S50).

This load signal is induced in the primary winding 4a of the output transformer 4 and flows through the diode 9 and the resistor 7. When a load signal flows through the resistor 7, a voltage is generated at both ends of the load signal. This voltage is applied to the input terminal of the current detection circuit 57. The current detection circuit 57 detects a load signal from this voltage (step S51). The current detection circuit 57 determines whether or not the voltage applied to the current detection circuit 57 is due to the load signal current. If it is determined that the voltage is not due to the load signal current (step S52), the current detection circuit 57 Outputs an output to the signal receiving circuit 31.

The signal receiving circuit 31 uses the current detecting circuit 57
Is input (step S52), the phase control circuit 65 is driven. Thereby, the phase control circuit 65 controls the control circuit 3
0, the firing phase control of the thyristor 36 is performed,
The DC output voltage and current of the full-wave rectifier circuit 2 are varied (step S53).

Therefore, the non-contact power supply circuit performs the intermittent operation in the low power mode (step S5).
4), the process returns to step S48. If it is determined that the detection result by the current detection circuit 57 is not a signal current due to the load signal, it is not the low power mode, and the process proceeds to the high power mode processing in step S42. Also in the seventh embodiment, in the low power mode, the small power can be supplied to the load on the secondary side in the low power mode as in each of the above embodiments. Can be secured.

Next, an eighth embodiment of the present invention will be described. FIG. 18 is a block diagram showing the configuration of the eighth embodiment. The configuration on the secondary side is the same as that of the seventh embodiment shown in FIG.
This is the same as the secondary side in the configuration of the embodiment, and is not shown in FIG. In FIG. 18, the same portions as those in FIG. An AC power supply (not shown) is connected to the input terminals 1a and 1b of the full-wave rectifier circuit 2. The positive output terminal of the full-wave rectifier circuit 2 includes a thyristor 36 of a switching circuit 35, a primary winding 4a of an output transformer 4, a MOS transistor 6,
It is grounded via a parallel circuit of a resistor 7 and a capacitor 8. The negative output terminal of the full-wave rectifier circuit 2 is grounded. The cathode of the thyristor 36 is grounded via the capacitor 3.

The diode 9 is connected between the drain and the source of the MOS transistor 6, and the capacitor 5 is connected between the drain and the ground. A current detection circuit 57 is connected in parallel with a parallel circuit of the resistor 7 and the capacitor 8. The output of the current detection circuit 57 is output to the signal analysis circuit 73. Signal analysis circuit 73
Analyzes whether the power supplied to the secondary side from the load signal transmitted from the secondary side to the primary side by inputting the output of the current detection circuit 57 is set to the small power mode or the large power mode. It is a circuit to perform.

The output of the signal analysis circuit 73 is output to a voltage up / down control circuit 74, a frequency variable control circuit 75, and a signal type determination circuit 77. The voltage up / down control circuit 74 controls the control circuit 30 by inputting the output of the signal analysis circuit 73, and outputs the signal to the signal generation circuit 76. The control circuit 30 functions as a phase control circuit for controlling the firing phase of the thyristor 36.

The frequency variable control circuit 75 receives the output of the signal analysis circuit 73,
And a circuit for outputting the signal to the signal generation circuit 76. Further, the signal type determination circuit 77 receives the output of the signal analysis circuit 73 to determine whether the temperature of the load is high, whether the power mode to be supplied to the secondary side should be in the low power mode, whether charging should be stopped, The frequency variable control circuit 75, the signal generation circuit 76, the voltage up / down control circuit 7
4 is output. The signal generation circuit 76 outputs the output of the frequency variable control circuit 75 and the signal type determination circuit 77.
And the output of the voltage up / down control circuit 74, a signal for performing a display such as "high temperature", "small power mode", and "charging stop" is generated on display means (not shown). Things. These current detection circuits 5
7, the signal analysis circuit 73, the voltage up / down control circuit 74, the frequency variable control circuit 75, the signal generation circuit 76, and the signal type determination circuit 77 constitute the primary side control means 13.

Next, the operation of the eighth embodiment will be described with reference to the flowchart shown in FIG. On the primary side, the AC voltage of the AC power supply connected to the input terminals 1a and 1b is full-wave rectified by the full-wave rectifier circuit 2, and the full-wave rectified voltage is applied to the thyristor 36. The thyristor 36 is fired at a predetermined phase by the control circuit 30 and generates a DC voltage on its cathode side. This DC voltage is smoothed by the capacitor 3. The smoothed voltage generated at both ends of the capacitor 3 is applied to the primary winding 4a of the output transformer 4, and a DC current flows through the primary winding 4a.

At the same time, the MOS transistor 6 is switched at the oscillation frequency of the oscillation circuit 12, and the DC current of the primary winding 4a of the output transformer 4 is converted into AC power by chopping. The voltage is transformed by the run 4, and a predetermined AC voltage is generated at both ends of the secondary winding 4b. The voltage across the secondary winding is rectified and smoothed in the same manner as in the seventh embodiment, and DC power is supplied to a load such as a charger via a switch circuit. At this time, on the secondary side, a load signal current corresponding to the load current is superimposed on the signal transmission load circuit in addition to the current of the load itself.

The load signal current is transmitted to the primary winding 4a of the output transformer 4 in a contactless manner by electromagnetic induction coupling by the output transformer 4, and flows from the primary winding 4a through the diode 9 and the resistor 7. As a result, a voltage is generated at both ends of the resistor 7. This voltage is applied to the input terminal of the current detection circuit 57 as an input voltage for current detection. The current detection circuit 57 outputs the signal to the signal analysis circuit 73 according to the input voltage. Upon receiving the output of the current detection circuit 73, the signal analysis circuit 73 should control the voltage applied to the primary winding 4a of the output transformer 4 up or down, or use a charger as a secondary load. (Step S61), whether the charging should be stopped or the power supply from the primary side to the secondary side should be set to the low power mode.

As a result of the analysis by the signal analysis circuit 73,
If it is determined that the voltage applied to the primary winding of the output transformer 4 needs to be changed up and down (step S6).
2) Output from the signal analysis circuit 73 to the voltage up / down control circuit 74 The voltage up / down control circuit 74 is a signal
By instructing the control circuit 30 to shift the firing phase of the thyristor 36 (step S62). The control circuit 30 receiving this instruction controls the firing phase angle of the thyristor 36 (Step S).
63) The voltage applied to the primary winding of the output transformer 4 is increased or decreased.

As the voltage applied to the primary winding of output transformer 4 rises or falls, the voltage induced in secondary winding 4b also rises or falls. At the same time, the voltage up / down control circuit 74 outputs to the signal generation circuit 76. By inputting the voltage up / down control circuit 74, the signal generating circuit 76 displays on the display means that the voltage applied to the primary winding has been increased or decreased (step S6).
4). The display on the display means allows the user to visually recognize the current control state.

When the signal analysis circuit 73 analyzes that the temperature of the load is high (step S65), the analysis result is output to the signal type determination circuit 77. The signal type determination circuit 77 needs to reduce the load current because the load temperature is high upon receiving the output of the signal analysis circuit 73. Therefore, the signal type determination circuit 77 includes a frequency variable control circuit 75 and a signal generation circuit. 76 and the voltage up / down control circuit 7
4 and output. The frequency variable control circuit 75 controls the time constant of the oscillation circuit 12 to perform variable control of the oscillation frequency of the oscillation circuit 12 by inputting the output of the signal type determination circuit 77 (step S66) (step S6).
7).

In this case, since it is necessary to lower the temperature of the load, the oscillation frequency of the oscillation circuit 12 is increased to reduce the amount of current flowing through the MOS transistor 6. Further, the voltage up / down control circuit 74 causes the control circuit 30 to perform the phase shift control of the ignition so that the conduction of the thyristor 36 is reduced and the output voltage is reduced. By doing so, the power supplied from the primary side to the secondary side can be set to the low power mode. At the same time, the signal generation circuit 76 sends a signal for display to the display means to display "charge stop", "low power mode", "oscillation frequency rise", and the like.

As is clear from the above description, in the eighth embodiment, a load signal generated according to the load state on the secondary side is induced to the primary side, and the load signal is analyzed to analyze the primary signal. It is possible to control the rise and fall of the voltage on the side, control the oscillation frequency of the oscillating circuit, control the conversion of the power mode to the low power mode, etc. The user can visually recognize the current usage status.

[0118]

As described above, according to the present invention, the load signal is transmitted to the primary side without contact by the electromagnetic induction coupling of the output transformer. When the primary side detects that the load signal is not transmitted to the secondary side or that the load signal is small, the power supply from the primary side to the secondary side is set to the low power mode, or the intermittent power supply is performed. Mode, and when the primary side detects that the load signal is transmitted from the secondary side to the primary side, power is supplied from the primary side to the secondary side in the high power mode. Therefore, it is possible to easily transmit the load signal from the secondary side to the primary side, and it is possible to prevent the unnecessary current from flowing to the load at the time of no load or light load, and to prevent the metal part from being heated by the current. be able to. Therefore, it is possible to prevent a decrease in insulation properties, temperature characteristics, and other deterioration due to a rise in the temperature of the component.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a contactless power supply circuit according to the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of the contactless power supply circuit of FIG. 1 and showing a relationship between a small power mode corresponding to a magnitude of a load signal and a large power mode in output voltage-output voltage characteristics.

FIG. 3 is a block diagram showing a configuration of a contactless power supply circuit according to a second embodiment of the present invention;

FIG. 4 is an explanatory diagram illustrating a relationship between a small power mode and a large power mode corresponding to a magnitude relationship between a load signal current and an output current versus an input current for explaining an operation of the contactless power supply circuit of FIG. 3;

FIG. 5 is a block diagram showing a configuration of a contactless power supply circuit according to a third embodiment of the present invention.

6 is a circuit diagram showing a detailed configuration of a switching circuit and a control circuit in the contactless power supply circuit of FIG. 5;

7 is a signal waveform diagram of each section for explaining the operation of the contactless power supply circuit of FIG. 5;

8 is a signal waveform diagram of each section for explaining the operation of the contactless power supply circuit of FIG.

9 is a waveform diagram at the time of intermittent operation and non-intermittent operation of the output side of the switching circuit in the contactless power supply circuit of FIG. 6;

FIG. 10 is a block diagram showing a configuration of a secondary side of a contactless power supply circuit according to a fourth embodiment of the present invention.

FIG. 11 is a block diagram showing the configuration of a contactless power supply circuit according to a fifth embodiment of the present invention.

12 is a flowchart showing an operation flow of the contactless power supply circuit of FIG.

FIG. 13 is a block diagram showing a configuration of a contactless power supply circuit according to a sixth embodiment of the present invention.

FIG. 14 is a flowchart showing a flow of operation of the contactless power supply circuit of FIG.

FIG. 15 is a block diagram showing a configuration of a contactless power supply circuit according to a seventh embodiment of the present invention.

16 is a flowchart showing a flow of an operation of the contactless power supply circuit of FIG.

FIG. 17 is an explanatory diagram illustrating a relationship between a change in a high power mode and a change in a low power mode over time for explaining the operation of the contactless power supply circuit in FIG. 15;

FIG. 18 is a block diagram showing a primary-side configuration of an eighth embodiment of a contactless power supply circuit according to the present invention.

FIG. 19 is a flowchart showing the operation flow of the contactless power supply circuit of FIG. 18;

[Explanation of symbols]

2, full-wave rectifier circuit, 3, 5, 8, 15, 20, 27,
50, 54, 69 ... capacitor, 4 ... output transformer, 4a ... primary winding, 4b ... secondary winding, 6 ... MO
S transistor, 7, 33, 39 to 41, 43, 44,
46, 47, 53 ... resistance, 9, 14, 16, 17, 6
8 Diode, 10, 57 Current detection circuit, 11
... Oscillation frequency variable circuit, 13... Primary side control means, 1
8, 58, 64 switch circuit, 21 load circuit for signal transmission, 22 power supply circuit, 23 secondary control circuit, 24 secondary control means, 26, 32, 48 Transistors, 28, 29 ... operational amplifier, 30 ... control circuit, 31 ... signal receiving circuit, 34 ... ON operation circuit,
35, 56 switching circuit, 36 thyristor, 37 on-operation stop circuit, 38, 62 intermittent operation circuit, 45 constant voltage diode, 49 load, 51 stop circuit, 55 ... switch, 59,
76: a signal generation circuit, 60: a switch circuit off intermittent operation circuit, 61: a switch circuit on operation circuit, 63
... intermittent operation stop circuit, 65 ... phase shift control circuit, 6
6: Timer, 67: 1 o'clock stop circuit, 70: Circuit power supply, 71: Detection circuit, 72: ON / OFF control circuit, 73: Signal analysis circuit, 74: Voltage up / down control circuit, 75 ... Frequency variable control circuit, 76 signal generation circuit, 77 signal type determination circuit.

Claims (16)

[Claims] An output transformer for inducing an AC voltage in a secondary winding by chopping a DC current supplied to a primary winding by a switching means; an oscillation circuit for supplying a switching signal to the switching means; Rectifying means for rectifying the output voltage of the secondary winding; a secondary-side switch circuit for supplying or interrupting the rectified voltage obtained by the rectifying means to a load; and rectifying current obtained by the rectifying means being supplied. The current of the load signal according to the state of the load is superimposed, and the current of the load signal is reduced by the electromagnetic induction coupling of the output transformer.
A signal transmission load circuit to be transmitted to a next winding, and detecting a change in an output voltage of the rectifier according to a state of the load to turn on / off the signal transmission load circuit and the secondary-side switch circuit. Secondary side control means for performing control; current detection means for detecting the current of the load signal transmitted to the primary winding; and the oscillation circuit when the current detection means does not detect the current of the load signal. On the other hand, frequency control is performed on the secondary winding so that the switching means switches in a low power mode or an intermittent operation, and the current detection means performs the secondary control on the oscillation circuit when the current of the load signal is detected. A non-contact power supply circuit comprising: a primary side control unit that performs frequency control on a winding so that the switching unit switches in a high power mode. 2. The non-contact power supply circuit according to claim 1, wherein said primary side control means is an oscillation frequency variable circuit which varies an oscillation frequency of said oscillation circuit by an output of said current detection means. 3. A one-way control element for supplying a current of the load signal induced in the primary winding for a half cycle, and a current detecting means connected in series with the one-way control element. And a current detection circuit that detects a voltage at one end of the first resistor generated when the current of the load signal flows through the resistor and outputs the voltage to the primary-side control unit in accordance with a detected value. The contactless power supply circuit according to claim 1, wherein: 4. The load circuit for signal transmission is connected in series with a second resistor between a positive output terminal and a negative output terminal of the rectifying means, and is controlled on and off by the secondary side control means. 2. The contactless power supply circuit according to claim 1, comprising a transistor that superimposes a load signal current corresponding to the load in addition to a DC current supplied by the rectifier. 5. The contactless power supply circuit according to claim 1, wherein a DC voltage is intermittently supplied to the primary winding by a primary-side switch circuit. 6. The one-way control element for supplying a current of the load signal induced in the primary winding for a half cycle, and a current detecting means connected in series with the one-way control element. A first operational amplifier that detects a voltage equal to or lower than a predetermined value at one end of the first resistor and is output according to the detected value; 2. The second operational amplifier, comprising: a second operational amplifier that detects a voltage equal to or higher than a predetermined value at one end of the first resistor generated by a current flowing through the resistor and outputs the voltage in accordance with the detected value. Contactless power supply circuit. 7. A signal receiving circuit to which an output of the second operational amplifier is inputted and which does not output the output of the second operational amplifier unless the output of the second operational amplifier is equal to or more than a predetermined value. A control circuit that controls to lower the oscillation frequency of the oscillation circuit at the time of input, and controls to increase the oscillation frequency of the oscillation circuit at the time of input of the output of the first operational amplifier. The contactless power supply circuit according to claim 6. 8. A signal receiving circuit to which an output of the second operational amplifier is inputted and which does not output unless the output of the second operational amplifier is equal to or more than a predetermined value; An on-operation circuit for outputting a signal for firing the switch circuit on the primary side when input, an on-operation stop circuit for stopping the operation of the on-operation circuit by an output of the first operational amplifier; 1 to supply small power from the side to the secondary side
An intermittent operation circuit for generating a signal of an intermittent operation cycle of a switching circuit on the next side; and The primary-side switching circuit is configured to perform ignition control of a primary-side switching circuit, and to supply large power from the primary side to the secondary side when an ON signal is input from the ON operation circuit. The non-contact power supply circuit according to claim 5, further comprising: a control circuit configured to switch from switching by the intermittent operation to normal ignition. 9. A first transistor which is turned on when an on-operation signal from the on-operation circuit is input, and is turned off when the on-operation signal is not input, and wherein the first transistor is turned on. A second transistor that is turned off at the time to stop the thyristor from operating intermittently, and is turned on when the first transistor is turned off to perform the intermittent operation at the thyristor. 8. The contactless power supply circuit according to 8. 10. The secondary-side control means turns off the secondary-side switch circuit when transmitting the load signal superimposed on the current of the signal-transmitting load circuit to the primary side. 2. The non-contact power supply circuit according to claim 1, wherein the supply of the secondary DC power to the power supply is stopped. 11. The load is supplied with the DC power on the secondary side through the switch circuit on the secondary side when the switch circuit on the secondary side is on, and the switch circuit on the secondary side is turned off. 11. The non-contact power supply circuit according to claim 10, wherein power is supplied by discharging the charging / discharging capacitor charged when the secondary side switch circuit is turned on in the case of (1). 12. The secondary side control means includes: a first switch circuit for turning on and off the signal transmission load circuit; and a secondary side switch for transmitting the load signal to the primary side. A stop circuit for turning off a circuit, and a signal generation for driving and controlling the stop circuit to turn off the first switch circuit when receiving a signal from the load and to turn off the secondary-side switch circuit. The non-contact power supply circuit according to claim 1, further comprising: a circuit. 13. The primary-side control means includes: a current detection circuit for detecting the load signal transmitted from a secondary side; and the primary-side control means when the small power is supplied from the primary winding to the secondary winding. An intermittent operation circuit for intermittently turning on a primary-side switch circuit for intermittently applying a DC voltage to the winding; and an intermittent operation circuit for supplying large power from the primary winding to the secondary winding. An intermittent operation stop circuit for stopping the operation of the switch, and a switch circuit on operation circuit for switching the primary side switch circuit from an intermittent operation to a normal on operation when a small power is supplied from the primary winding to the secondary winding. A signal receiving circuit for stopping the operation of the switch-on operation circuit and operating the intermittent operation circuit with respect to the intermittent operation stop circuit when the output of the current detection circuit is in the low power supply state; The electric And a switch circuit-off intermittent operation circuit that activates the switch circuit-on operation circuit and stops the operation of the intermittent operation circuit when the output of the detection circuit is in the large power supply state. 2. The contactless power supply circuit according to 1. 14. A control circuit for turning on and off a primary-side switch circuit so as to intermittently apply a DC voltage to the primary winding; A current detection circuit for detecting the load signal transmitted from the power supply to the primary side, and when a detection output from the current detection circuit is input and it is determined that the detection output is not a load signal, power supplied to the load is reduced to a low power mode. A signal receiving circuit that outputs as not being; a phase control circuit that causes the control circuit to perform a firing phase control of the primary-side switch circuit based on an output of the signal receiving circuit; A timer that starts operation when a large amount of power is supplied to the power supply and stops operation for a predetermined time after a lapse of a predetermined time. Contactless power supply circuit according to claim 1, wherein the and a 1:00 stop circuit for stopping the operation for a predetermined time. 15. The secondary-side control means includes: a secondary-side switch circuit for turning on / off the power supply to the load; and an on / off for controlling on / off of the secondary-side switch circuit. A control circuit, a detection circuit for detecting the voltage on the secondary side, and turning off the switch circuit on the secondary side to the on / off control circuit when zero of the voltage on the secondary side is detected; The non-contact power supply circuit according to claim 1, further comprising: a signal generation circuit that inputs a signal from the load during a load or no load state and controls the signal transmission load circuit to an operation state. 16. The primary side control means includes: a current detection circuit for detecting the load signal transmitted from the secondary side to the primary side; A signal analysis circuit that analyzes whether the power supplied to the secondary side is in a low power mode or a high power mode; and when the analysis result of the signal analysis circuit is the low power mode, the primary side Of the switch circuit on the primary side with respect to the control circuit so that the output voltage of the switch circuit on the primary side increases in the high power mode. A voltage up / down control circuit for performing off control, and controlling the oscillation frequency of the oscillation circuit to be high when the analysis result of the signal analysis circuit is the low power mode,
And a frequency variable control circuit that controls the oscillation frequency of the oscillation circuit to be low when the analysis result of the signal analysis circuit is the high power mode; and a signal of the load state from the analysis result of the signal analysis circuit. The voltage up / down control circuit that determines the type of the signal, a signal type determination circuit that drives the frequency variable control circuit, the voltage up / down control circuit, the frequency variable control circuit,
The non-contact power supply circuit according to claim 1, further comprising: a signal generation circuit that receives an output from the signal type determination circuit and generates a signal for displaying the output status on a display unit.