JPH0837085A - Induction heating device - Google Patents

Abstract

PURPOSE:To surely protect the switching element of an induction heating/ oscillating circuit from breakage against the occurrence of an abnormally high voltage on an induction heating/oscillating power circuit by providing an abnormally high voltage signal generating means and an abnormally high voltage detecting means. CONSTITUTION:Commercial AC power is fed from a commercial power source 1 to an induction heating (IH)/oscillating power circuit 2 and a control circuit power circuit 3 respectively. When an abnormally high voltage occurs on the circuit 2, an abnormally high voltage detecting means 94 detects it via an abnormally high voltage signal generating means 11, and a heating control means 96 stops the oscillation drive of an IH oscillating circuit 4 by an IH driving circuit 5 via an IH drive temporary stopping means 95. When the occurrence of the abnormally high voltage is stopped, no abnormally high voltage signal is outputted from the means 11, however the means 96 stops the oscillation drive of the circuit 4 by the circuit 5 for a fixed time thereafter. The output of the circuit 2 is sufficiently reduced from the high voltage output state, and the breakage of elements of the circuit 4 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating device applied to a cooker, for example.

[0002]

2. Description of the Related Art An induction heating apparatus, for example, an induction heating cooker, electromagnetically induction-heats an object to be heated, that is, a cooking container, which is partially or entirely made of a conductor, by supplying high frequency power to an induction heating coil. It is configured.

In such an induction heating cooker, if an abnormally high voltage is generated in the induction heating oscillation power supply circuit that supplies power to the induction heating oscillation circuit, the switching element in the induction heating oscillation circuit may be destroyed. When an abnormally high voltage is generated, it is necessary to detect it and stop the induction heating operation.

[0004]

By the way, when the induction heating operation is stopped when an abnormally high voltage is generated in the induction heating oscillation power supply circuit, even if the generation of the high voltage is stopped, discharge is restricted. In the case where the voltage does not drop immediately but gradually drops, if the heating operation is restarted immediately when the abnormal high voltage falls below the detection level, the output of the induction heating oscillation power supply circuit is near the abnormal high voltage level. Therefore, a large stress is applied to the switching element in the oscillation circuit, and the element may be broken in some cases.

The present invention has been made in order to solve such a problem, and ensures the switching element of the induction heating oscillation circuit from being destroyed against the occurrence of an abnormally high voltage in the induction heating oscillation power supply circuit. Provided is an induction heating device which can be protected.

[0006]

SUMMARY OF THE INVENTION The present invention comprises an induction heating oscillation power supply circuit in which a smoothing capacitor is connected to a commercial power supply via a diode rectifier circuit and a filter coil, an induction heating coil and a resonance capacitor. An induction heating oscillation circuit which has a resonance circuit and which is connected to a smoothing capacitor of a power supply circuit via a switching element, a drive circuit which oscillates and drives this induction heating oscillation circuit, and controls the operation of this drive circuit An abnormal high voltage signal generating means for detecting an abnormal high voltage of the heating control means and the power supply circuit for induction heating oscillation and outputting an abnormal high voltage signal, and responding to the abnormal high voltage signal from this abnormal high voltage signal generating means. The heating control means to control to stop the oscillation drive of the induction heating oscillation circuit by the drive circuit, and the abnormal high voltage signal from the abnormal high voltage signal generating means. But also lost force is provided an induction heating drive temporary stop means to continue oscillation drive stop control to the constant time heating control means.

[0007]

In the present invention having such a structure, when an abnormal high voltage is generated in the induction heating oscillation power supply circuit, the abnormal high voltage signal generating means detects it and outputs the abnormal high voltage signal. Then, in response to the abnormal high voltage signal, the heating control means controls the driving circuit to stop the oscillation drive of the induction heating oscillation circuit. Then, when the generation of the abnormal high voltage is stopped thereafter, the output of the abnormal high voltage signal from the abnormal high voltage signal generating means disappears. However, the heating control means controls the oscillation driving of the induction heating oscillation circuit by the driving circuit for a certain period of time thereafter. As a result, the output of the induction heating oscillation power supply circuit is sufficiently lowered from the high voltage output state.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration. Reference numeral 1 is a commercial power source, and commercial AC power is induction-heated from the commercial power source 1 (hereinafter referred to as IH = induction heating) oscillation power supply circuit 2 and control circuit power supply. It is supplied to each circuit 3.

The IH oscillation power supply circuit 2 rectifies commercial AC power, converts it into DC, and supplies it to the IH oscillation circuit 4. The IH oscillation circuit 4 is driven to oscillate by an IH drive circuit 5.

The power supply circuit 3 for the control circuit rectifies commercial AC power and converts it to DC, and supplies it to the power supply circuit 6 for microcomputer and the energization signal generating means 7, respectively. The microcomputer power supply circuit 6 outputs a stabilized DC voltage and supplies it to the microcomputer 9 via the microcomputer power supply switching means 8. On the other hand, a backup power supply 10 is provided, and when a power failure occurs, the microcomputer power supply switching means 8 performs a switching operation to connect the backup power supply 10 to the microcomputer 9 instead of the microcomputer power supply circuit 6.

The energizing signal generating means 7 detects the voltage state of the control circuit power supply circuit 3, outputs an energizing signal when the voltage state exceeds a preset predetermined level, and the voltage state is below a predetermined level. The output of the energization signal is stopped when the voltage drops to.

When an abnormal high voltage is generated in the IH oscillation power supply circuit 2, the abnormal high voltage signal generating means 11 detects it and supplies the abnormal high voltage signal to the microcomputer 9.

Further, the input voltage to the IH oscillation power supply circuit 2 is detected by the input voltage signal generating means 12 to supply a voltage detection signal to the microcomputer 9, and the input to the IH oscillation power supply circuit 2 is performed. The input current signal generating means 13 detects a current and supplies a current detection signal to the microcomputer 9.

The microcomputer 9 has an internal I
An H control unit 91 and a power failure detection unit 92 are provided, and the IH control unit 91 is further configured by an input power adjustment unit 93, an abnormal high voltage detection unit 94, an IH drive temporary stop unit 95, and a heating control unit 96.

The power failure detection means 92 checks the signal from the energization signal generation means 7, operates the IH control means 91 as long as the energization signal is input, and stops the input of the energization signal. The occurrence of a power failure is detected and the operation of the IH control means 91 is interrupted.

When the operation of the IH control means 91 is interrupted, the prohibiting means 15 is operated by the input power adjusting means 93. At this time, the microcomputer 9 switches the microcomputer power supply switching means 8 to the backup power supply 1
Although the mode is switched to the 0 side to shift to the low power consumption mode, the operating current of the prohibiting means 15 causes the microcomputer power supply circuit 6 to operate.
The voltage of 2 rapidly drops to the voltage of the backup power supply 10, and the microcomputer power supply switching means 8 advances the timing of switching the power supply to the backup power supply 10.

When the energization signal generating means 7 outputs the energization signal again due to the recovery from the power failure, the heating control means 96 restarts the control before the power failure.

When the abnormal high voltage detecting means 94 receives the abnormal high voltage signal from the abnormal high voltage signal generating means 11, the abnormal high voltage detecting means 94 performs an abnormal high voltage detecting operation to operate the IH drive temporary stopping means 95. The IH drive temporary stop means 95
Makes a temporary stop request to the heating control means 96.

When the temporary stop request is input from the IH drive temporary stop means 95, the heating control means 96 controls the input power adjusting means 93. As a result, the input power adjusting means 93 stops the operation of the drive signal generating means 14 to stop the operation of the IH drive circuit 5 and supplies a signal to the inhibiting means 15, even if the drive signal generating means 14 malfunctions. Even in such a case, the operation of the IH drive circuit 5 can be surely stopped.

While the abnormal high voltage is detected, the IH drive temporary stop means 95 makes a temporary stop request to the heating control means 96 to stop the operation of the IH drive circuit 5 to stop the abnormal high voltage. Even if is not detected, the temporary stop request to the heating control means 96 is continued for a further fixed time, and then a request signal for restarting the heating control is output to the heating control means 96. In addition,
The fixed time during which the temporary stop request is continued is set to a time sufficient for the output voltage of the IH oscillation power supply circuit 2 to surely drop to the original normal voltage after the generation of the abnormal high voltage is stopped.

When the heating request signal is generated from the heating control means 96, the input power adjusting means 93 uses the input voltage signal from the input voltage signal generating means 12 and the input current signal from the input current signal generating means 13. The current input power is calculated, and a power adjustment signal from the heating control means 96 that matches the required power is supplied to the drive signal generation means 14
Output to.

The drive signal generation means 14 converts the power adjustment signal from the input power adjustment means 93 into a drive signal and outputs it to the IH drive circuit 5. The IH drive circuit 5
Adjusts the oscillation frequency of the IH oscillating circuit 4 by the drive signal from the drive signal generating means 14 to adjust the input power.

The IH oscillation power supply circuit 2, the IH oscillation circuit 4, the input current signal generating means 13 and the drive signal generating means 1
4 is specifically configured as shown in FIG. That is, the IH oscillation power supply circuit 2 includes a full-wave rectifier circuit 21 including a diode bridge, and the full-wave rectifier circuit 21.
A smoothing capacitor 23 is connected to the output terminal of the filter via a filter coil 22.

In the IH oscillation circuit 4, an insulated gate bipolar transistor (IGBT) 43 is connected to the output terminal of the IH oscillation power supply circuit 2 via a parallel resonance circuit of an induction heating coil 41 and a resonance capacitor 42. There is. A constant voltage diode 44 is connected between the gate and the emitter of the transistor 43, and a diode 45 is connected in parallel between the collector and the emitter with a reverse polarity.

In the IH oscillation power supply circuit 2, in order to detect an abnormal high voltage, a series circuit of resistors 24, 25, 26 is connected between the output terminals of the full-wave rectifier circuit 21, and the central resistor 25 is connected. A capacitor 27 is connected in parallel with.

Further, in the IH oscillation power supply circuit 2, in order to detect an input current, a capacitor 28 and a resistor 29 are provided between the output terminals of the full-wave rectification circuit 21 via the coil 22.
Of the diode 2 connected to the resistor 29.
10 is reversed in polarity and connected in parallel.

To the IH oscillation circuit 4, a series circuit of a capacitor 46 and a resistor 47 is connected in parallel with the transistor 43 in order to extract a synchronizing signal with the oscillation circuit. The drive signal generating means 14 comprises a trigger section 141, an oscillating section 142 and an on-time control section 143. The trigger section 141 responds to a voltage change at a connection point between the capacitor 46 and the resistor 47 of the IH oscillation circuit 4. To generate a trigger signal and supply the trigger signal to the oscillating unit 142. The oscillator 142 oscillates in response to the trigger signal and outputs a sawtooth voltage. The on-time control unit 143 is provided with a comparator 144, and the comparator 144 compares the level of the power adjustment signal input from the ladder circuit described later via the terminal X with the level of the sawtooth voltage input from the oscillator 142. Then, the on-time drive signal is output to the IH drive circuit 5 by setting the time until the sawtooth wave voltage exceeds the power adjustment signal level as the on-time.

The input current signal generating means 13 has the I
The current flowing in the series circuit of the capacitor 28 and the resistor 29 of the H oscillation power supply circuit 2 is smoothed by the capacitor 133 via the resistor 131 and the diode 132, and then output as an input current signal via the resistor 134.

The control circuit power supply circuit 3, the microcomputer power supply circuit 6, the energization signal generating means 7 and the input voltage signal generating means 12 are specifically constructed as shown in FIG. The control circuit power supply circuit 3 connects the commercial power supply 1 to the input terminal of a full-wave rectifier circuit 32 formed of a diode bridge via a step-down transformer 31, and the smoothing capacitor 33 is connected to the output terminal of the full-wave rectifier circuit 32. And another smoothing capacitor 35 is connected in parallel to the smoothing capacitor 33 via the collector and emitter of the transistor 34. A constant voltage diode 36 is connected between the base of the transistor 34 and the negative terminal of the smoothing capacitor 33. The control voltage VP is output from both ends of the smoothing capacitor 35.

The microcomputer power supply circuit 6 has a smoothing capacitor 62 connected in parallel to both ends of the smoothing capacitor 35 of the control circuit power supply circuit 3 via a collector and an emitter of a transistor 61, and a collector and an emitter of a transistor 63. Another smoothing capacitor 64 is connected in parallel via the, and a constant voltage diode 65 is connected between the bases of the transistors 61 and 63 and the negative terminal of the smoothing capacitor 35. Then, microcomputer voltages VCCA and VCCB having different voltages are output from both ends of the smoothing capacitor 62 and both ends of the smoothing capacitor 64, respectively.

The energization signal generating means 7 connects the collector of the transistor 71 to the positive terminal of the smoothing capacitor 64 of the microcomputer power supply circuit 6 and connects the emitter of the transistor 71 to the negative terminal via the resistor 72. The base of the transistor 71 is connected to the collector of another transistor 73 via a resistor 74, the emitter of the transistor 71 is connected to the emitter of the transistor 73 via the resistor 72, and the base of the transistor 73 is connected to the base of the transistor 73. A constant voltage diode 76 is connected via a resistor 75 to the positive terminal of the smoothing capacitor 33 of the control circuit power supply circuit 3.

The energizing signal generating means 7 extracts an energizing signal from the connection point between the emitter of the transistor 71 and the resistor 72 and supplies it to the power failure detecting means 92 of the microcomputer 9.

The input voltage signal generating means 12 connects a parallel circuit of a resistor 123 and a capacitor 124 to the commercial power source 1 via a diode 121 and a resistor 122, and a smoothing capacitor 126 via a diode 125 to the parallel circuit. Are connected in parallel. Then, an input voltage signal is taken out from both ends of the smoothing capacitor 126 and supplied to the input power adjusting means 93 of the microcomputer 9.

The abnormal high voltage signal generating means 11 is specifically constructed as shown in FIG. That is, a series circuit of resistors 112 and 113 is connected via a constant voltage diode 111 between a connection point between the resistors 25 and 26 connected to the IH oscillation power supply circuit 2 and a ground point. The NPN transistor 1 is connected to the connection point of the resistors 112 and 113.
14 bases are connected.

The transistor 114 has an emitter grounded, a collector connected to a VP terminal via a resistor 115 and a base of another NPN transistor 117 via a resistor 116. The transistor 11
A capacitor 118 is connected in parallel between the collector and the emitter of No. 4.

The transistor 117 has an emitter grounded via a resistor 120, a collector connected to a VP terminal via a resistor 119, and a collector connected to the base of another NPN transistor 122 via a resistor 121. Together with another NPN transistor 1 via the resistor 123
It is connected to 24 bases.

The transistor 122 has an emitter grounded via the resistor 120 and a collector connected to the VP terminal via a resistor 125. The transistor 12
4 has an emitter grounded and a collector connected to a VP terminal via a resistor 126.

This circuit constitutes a kind of one-shot circuit. An abnormal high voltage signal having a predetermined time width is taken out from the collector of the transistor 124 and supplied to the abnormal high voltage detecting means 94 of the microcomputer 9.

FIG. 5 shows the prohibiting means 15 and the ladder circuit 1.
6 is a circuit diagram showing a specific configuration of No. 6, the prohibiting means 15 is provided with a transistor 151, the collector of the transistor 151 is connected to the above-mentioned terminal X (terminal X shown in FIG. 2) via a resistor 152, and the emitter is connected. Is grounded, and the base is connected to the input power adjusting means 93 of the microcomputer 9 through the resistor 153.

In the ladder circuit 16, a series circuit of a large number of resistors 161, ... Is connected between the terminal X and ground, and the connection point of each resistor 161 is adjusted via the resistor 162 to adjust the input power of the microcomputer 9. It is connected to the means 93.

When the induction heating operation is stopped, the input power adjusting means 93 outputs a high level signal to the base of the transistor 151 of the prohibiting means 15 to turn on the transistor 151 to change the voltage level output to the terminal X. Drop to about 0V.

The input power adjusting means 93 is responsive to the required power from the heating control means 96 for the ladder circuit 16
A high-level or low-level signal is selectively output to each of the resistors 162, and various levels of the power adjustment signal output to the terminal X are set. Further, the input power adjusting means 93 sets all output signals to the resistors 162 of the ladder circuit 16 to a low level when stopping the induction heating operation.

In the embodiment having such a structure, when the commercial power supply 1 is turned on, the power supply to the IH oscillation power supply circuit 2, the control circuit power supply circuit 3 and the microcomputer power supply circuit 6 is started, and the microcomputer power supply switching means 8 is provided. Backup power supply 1
0 is disconnected and the microcomputer 9 is connected to the microcomputer power supply circuit 6.

At this time, the constant voltage diode 76 of the energization signal generation means 7 connected to the control circuit power supply circuit 3 becomes conductive, an energization signal is generated from the energization signal generation means 7, and the power failure detection means 92 is in the energized state. Recognize. Thus, the IH control means 91 starts its operation.

On the other hand, the input voltage signal generating means 12 has an IH
A signal corresponding to the voltage value of the oscillation power supply circuit 4 is supplied to the microcomputer 9, and the input current signal generating means 13 outputs I
A signal corresponding to the value of the current flowing through the H oscillation power supply circuit 4 is supplied to the microcomputer 9.

When the heating request signal is generated from the heating control means 96, the input power adjusting means 93 determines the current input power from the input voltage signal from the input voltage signal generating means 12 and the input current signal from the input current signal generating means 13. A signal that is calculated and matches the required power from the heating control means 96 is output. That is, a high level or low level signal is selectively output to each resistor 162 of the ladder circuit 16,
The voltage level of the power adjustment signal supplied to the drive signal generation means 14 is set.

The drive signal generating means 14 converts the power adjustment signal into a drive signal and then operates the IH drive circuit 5 to operate the IH drive circuit.
The input power is adjusted by adjusting the oscillation frequency of the oscillator circuit 4.

When a stop request is issued from the heating control means 96 or a stop request is issued from the IH drive temporary stop means 95, the input power adjusting means 93 causes the resistors 1 of the ladder circuit 16 to operate.
A low-level signal is output to all 62 to stop the operation of the drive signal generating means 14 and stop the operations of the IH drive circuit 5 and the IH oscillation circuit 4. At this time, the input power adjusting means 93 also outputs a signal to the prohibiting means 15,
Even if the drive signal generating means 14 malfunctions, IH
The oscillation operation of the oscillator circuit 4 is surely stopped. That is,
The transistor 151 of the prohibiting means 15 is turned on to forcibly set the voltage level of the signal supplied to the drive signal generating means 14 to substantially 0 level.

Further, when a power failure occurs in the commercial power supply 1 during operation, the constant voltage diode 76 of the energization signal generation means 7 becomes non-conductive before the microcomputer power supply switching means 8 operates, and the output of the energization signal is stopped. It

Therefore, the power failure detecting means 92 detects the power failure state, the control operation of the IH control means 91 is interrupted, the input power adjusting means 93 operates the prohibiting means 15, and the oscillation operation of the IH oscillation circuit 4 is stopped. It That is, the energization signal generating means 7 includes the control circuit power supply circuit 3 and the microcomputer power supply circuit 6
Before the output voltage fluctuates, the voltage drop across the smoothing capacitor 33 on the input side of the control circuit power supply circuit 3 is detected, and the power failure detection means 92 detects the power failure condition. Then, the heating control means 96 controls the input power adjusting means 93, controls the ladder circuit 16 by the input power adjusting means 93, and operates the prohibiting means 15.

In this way, when the power supply voltage of the commercial power supply 1 changes due to a power failure or the like, the oscillation operation of the IH oscillation circuit 4 can be stopped before the output voltages of the control circuit power supply circuit 3 and the microcomputer power supply circuit 6 change. Therefore, the destruction of the elements of the IH oscillation circuit 4 can be prevented.

When the power failure detecting means 92 detects the power failure state, the microcomputer 9 shifts to the low power consumption mode by the backup power source 10. Further, the microcomputer power supply circuit 6 quickly drops to the backup power supply voltage due to the operating current of the prohibiting means 15, and the microcomputer power supply switching means 8
This accelerates the timing of switching to the backup power supply 10.

When the commercial power supply 1 recovers from a power failure in this state,
The energization signal generation unit 7 outputs the energization signal again, and the power failure detection operation of the power failure detection unit 92 is stopped. Accordingly, in the IH control means 91, the heating control means 96 makes the same heating request to the input power adjusting means 93 as before the power failure, and the input power adjusting means 93 controls the drive signal generating means 14 to control the IH.
The oscillation circuit 4 restarts the operation with the same output as before the power failure.

When the input voltage becomes an abnormal high voltage, the abnormal high voltage signal generating means 11 supplies the abnormal high voltage signal to the microcomputer 9. That is, when an abnormal high voltage is generated in the abnormal high voltage signal generating means 11, the constant voltage diode 111 becomes conductive and the transistor 1
14 is turned on. As a result, the transistor 117
Turns off and the transistors 122 and 124 turn on.

In this way, a low level abnormal high voltage signal is output from the collector of the transistor 124 and supplied to the microcomputer 9. In this circuit, the abnormal high voltage is generated in a very short time, and even if the constant voltage diode 111 is immediately turned off and the transistor 114 is turned off, the transistor 117 is not turned on immediately, and the resistance value of the resistor 115 is equal to that of the resistor 115. When the voltage level of the capacitor 118 reaches a predetermined level according to the time constant determined by the capacity of the capacitor 118, the transistor 117 is turned on.

In this way, when an abnormal high voltage is generated, the collector of the transistor 124 outputs an abnormal high voltage signal of a predetermined time width and supplies it to the microcomputer 9. In the microcomputer 9, the abnormal high voltage detection means 94 detects the generation of the abnormal high voltage signal and outputs a detection signal to the IH drive temporary stop means 95 in order to prevent the transistor 43 of the IH oscillation circuit 4 from being destroyed. Accordingly, the IH drive temporary stop means 95 makes a temporary stop request to the heating control means 96.

In this way, the heating control means 96 suspends the induction heating operation. The IH drive temporary stop means 95 holds the temporary stop request state for a certain time even if the detection signal from the abnormal high voltage detection means 94 disappears, and thereafter outputs a request signal to the heating control means 96 to restart the heating control. To do.

For example, as shown in FIG. 6A, when the voltage of the IH oscillation power supply circuit 2 is normally 141V, 220V
When an abnormal high voltage exceeding 10 is generated, the abnormal high voltage signal generating means 11 outputs an abnormal high voltage signal of a low time for a predetermined time width as shown in FIG. 6 (b).

In the IH oscillation power supply circuit 2, for example, an abnormal high voltage exceeding 220V is returned to the original 141V, for example, 30
If 0 msec is required, the IH drive temporary stop means 95 keeps the state of the temporary stop request for another 500 msec, for example, after the detection signal is no longer input.

By doing so, when the IH drive temporary stop means 95 outputs a heating request to the heating control means 96, the voltage state of the IH oscillation power supply circuit 2 is reliably restored to the normal voltage state. , The transistor 43 of the IH oscillation circuit 4 is not stressed by the abnormally high voltage generated by the counter electromotive force of the coil when the IH oscillation circuit 4 stops the oscillation operation, and the transistor 43 is reliably protected from damage. be able to.

Although the insulated gate bipolar transistor is used as the switching element of the IH oscillation circuit in the above embodiment, the invention is not limited to this, and another transistor may be used.

[0062]

As described in detail above, according to the present invention, it is possible to reliably protect the switching element of the induction heating oscillation circuit from being destroyed against the abnormal high voltage generation in the induction heating oscillation power supply circuit. A heating device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a specific circuit configuration of an IH oscillation power supply circuit, an IH oscillation circuit, an input current signal generation means, and a drive signal generation means of the embodiment.

FIG. 3 is a diagram showing a specific circuit configuration of a control circuit power supply circuit, a microcomputer power supply circuit, an energization signal generating means, and an input voltage signal generating means of the embodiment.

FIG. 4 is a diagram showing a specific circuit configuration of an abnormal high voltage signal generating means of the embodiment.

FIG. 5 is a diagram showing a specific circuit configuration of a prohibition unit and a ladder circuit according to the embodiment.

FIG. 6 is a signal waveform diagram showing an example of an abnormal high voltage signal and a temporary stop request when an abnormal high voltage is generated in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Commercial power supply 2 ... IH (induction heating) oscillation power supply circuit 21 ... Full-wave rectification circuit 22 ... Filter coil 23 ... Smoothing capacitor 4 ... IH (induction heating) oscillation circuit 41 ... Induction heating coil 42 ... Resonance capacitor 43 Insulated gate bipolar transistor (IGBT) 5 ... IH (induction heating) drive circuit 9 ... Microcomputer 95 ... IH (induction heating) drive temporary stop means 96 ... Heating control means 11 ... Abnormal high voltage signal generation means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukichi Abe 2570, Gosuda, Kamo City, Niigata Prefecture 1 Toshiba Home Techno Co., Ltd.

Claims (1)

[Claims] 1. An induction heating oscillation power supply circuit in which a smoothing capacitor is connected to a commercial power supply via a diode rectifier circuit and a filter coil, and a resonance circuit including an induction heating coil and a resonance capacitor, the resonance of which is provided. An induction heating oscillation circuit having a circuit connected to a smoothing capacitor of the power supply circuit via a switching element, a drive circuit for oscillating and driving the induction heating oscillation circuit, heating control means for controlling the operation of the drive circuit, and the induction circuit. Abnormal high voltage signal generating means for detecting an abnormal high voltage of the heating oscillation power supply circuit and outputting an abnormal high voltage signal, and to the heating control means in response to the abnormal high voltage signal from the abnormal high voltage signal generating means. Control of stopping the oscillation drive of the induction heating oscillation circuit by the drive circuit and output of an abnormal high voltage signal from the abnormal high voltage signal generating means. An induction heating apparatus comprising: an induction heating drive temporary stop means for continuing the oscillation drive stop control to the heating control means for a certain period of time even when power is lost.