JP3249294B2 - Inverter for induction heating cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for an induction heating cooker provided with an inverter circuit comprising a resonance circuit.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional inverter device of an induction heating cooker. As shown in FIG. 1, a DC power supply circuit 105 including a rectifier circuit 102, a choke coil 103, and a smoothing capacitor 104 is connected to an AC power supply 101.
The output circuit 05 is connected to an inverter circuit 106. The inverter circuit 106 is connected to the resonance coil 10 shown in FIG.
7, a resonance capacitor 108, a switching element 109, and a rectifying element 110 connected in anti-parallel to the switching element 109. As is well known, the inverter circuit 106 performs a resonance operation to convert the DC output of the DC power supply circuit 105 to a high frequency.

[0003]

By the way, in the conventional induction heating cooker, when a lightning surge is applied, a surge voltage for preventing destruction of the switching element 109 and the like is detected, and the inverter circuit 106 is controlled. The one which stops the operation is provided. In this case, FIG.
The output voltage VK of the DC power supply circuit 105 is detected, and when the output voltage VK exceeds a predetermined reference voltage, it is detected that a surge voltage has been applied, and the inverter circuit 106 is stopped. I have to.

However, in this case, the output voltage V
The following phenomenon may occur before K exceeds a predetermined reference voltage. That is, when the lightning surge voltage is applied, the smoothing capacitor 104 is charged by the surge current, and the input voltage of the inverter circuit 106 sharply increases. Also, the lightning surge voltage rises very quickly, at several μsec, and rises faster than the oscillation frequency of induction heating. Further, the voltage VK resonates with the choke coil 103 and the smoothing capacitor 104, and becomes a high-voltage DC voltage on which a high frequency is also superimposed.

For this reason, the value of the current flowing through the resonance coil 107 when the switching element 109 is turned on is several times larger than the normal value, and becomes larger than the resonance voltage when the switching element 109 is turned off. The voltage fluctuates, and the inverter circuit 106 operates abnormally or is broken. Further, when the voltage of the AC power supply 101 temporarily rises to, for example, about 20 V, this cannot be detected, and the inverter circuit 106 is destroyed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an induction heating cooker which can quickly detect a lightning surge and stop the operation of an inverter circuit, thereby preventing the inverter circuit from being destroyed . To provide an inverter device .

[0007]

A first means is a DC power supply circuit having a rectifier circuit, a choke coil, and a smoothing capacitor to obtain a DC output from an AC power supply, and a DC output of the DC power supply circuit is converted to a high-frequency power. A resonance coil, a resonance capacitor that forms a resonance circuit together with the resonance coil, a switching element connected in series between the output terminals of the DC power supply circuit via the resonance coil, An inverter circuit having a rectifying element connected in anti-parallel to the element, and a drive circuit for controlling the switching element to turn on and off to operate the inverter circuit , wherein a positive output of the rectifying circuit of the DC power supply circuit is provided. A capacitor and a resistor are connected between the positive output terminal and the negative output terminal in this order from the positive output terminal side. A support <br/> over edge detection circuit surge absorption was also included in the rectifier circuit that outputs a surge detection signal from the connection point of the capacitors and resistors, said inverter circuit based on the surge detection signal from the surge detecting circuit the characterized in that provided a stop means for outputting a signal for stopping the operation
A (invention of claim 1).

The second means is provided with a DC power supply circuit having a rectifier circuit, a choke coil, and a smoothing capacitor to obtain a DC output from an AC power supply, and for converting the DC output of the DC power supply circuit into high-frequency power. A resonance coil, a resonance capacitor forming a resonance circuit together with the resonance coil, a switching element connected in series with the resonance coil between output terminals of the DC power supply circuit, and anti-parallel connected to the switching element. An inverter circuit including a rectifying element, and a drive circuit that operates the inverter circuit by controlling on / off of the switching element.
In those equipped with, between the input terminals of the rectifier circuit of the DC power source circuit is constructed by connecting a resistor and a capacitor, surge of the rectifier circuit that outputs a surge detection signal from the connection point between the resistor and the capacitor The present invention is characterized in that a surge detection circuit including absorption and a stop means for outputting a signal for stopping the operation of the inverter circuit based on a surge detection signal from the surge detection circuit are provided. Invention).

A third means is the first means or the second means, wherein operation restart means for outputting a signal for restarting driving of the inverter circuit after a predetermined time delay after the inverter circuit is stopped is provided. (The invention of claim 3).

[0010] A fourth means is the first means or the second means, wherein the drive of the inverter circuit is restarted when the output voltage of the DC power supply circuit returns to a normal voltage after the inverter circuit is stopped by the stop means. The present invention is characterized in that operation restart means for outputting a signal for performing the operation is provided.
Invention).

A fifth means is the third means or the fourth means, wherein the storage means and the driving control status of the inverter circuit before the detection of the surge voltage are stored in the storage means. When the operation is restarted, an operation control means for driving the inverter circuit in the drive control state stored in the storage means is provided (the invention of claim 5).

[0012]

In the first means, a capacitor and a resistor are connected between the positive output terminal and the negative output terminal of the rectifier circuit of the DC power supply circuit in order from the positive output terminal side, and Since the surge detection circuit including the surge absorption of the rectifier circuit that outputs the surge detection signal from the connection point with the resistor is provided, the differential waveform signal is output from the connection point that is the output terminal, and the surge voltage becomes sharp. Rising can be detected quickly. And, since the stop means for outputting a signal for stopping the operation of the inverter circuit based on the surge detection signal from the surge detection circuit is provided, the operation of the inverter circuit can be stopped based on the quick surge detection, and the operation of the inverter circuit can be stopped. Destruction can be prevented. In addition, the surge detection circuit including the capacitor and the resistor acts as a snubber circuit for the rectifier circuit, and can protect the rectifier circuit.

[0013] In the second means, direct current between the power supply circuit input terminal of the rectifier circuit, the rectifier circuit is constituted by connecting a resistor and a capacitor and outputs a surge detection signal from the connection point between the resistor and the capacitor Since the surge detection circuit including the surge absorption is provided, a differential waveform signal is output from the connection point, which is an output terminal, so that a steep rising of the surge voltage can be quickly detected. And
Since a stop means for outputting a signal for stopping the operation of the inverter circuit based on the surge detection signal from the surge detection circuit is provided, the operation of the inverter circuit can be stopped based on the quick surge detection, and the inverter circuit is destroyed. Can be prevented. Also, from the capacitor and the resistor
The configured surge detection circuit snubbers the rectifier circuit.
The rectifier circuit acts as a path to protect the rectifier circuit.

In the third means, the operation restart means for outputting a signal for restarting the drive of the inverter circuit after a predetermined time delay after the inverter circuit is stopped is provided, so that the influence of the surge voltage is eliminated. Later, the inverter circuit can be driven, which can further contribute to preventing the inverter circuit from being destroyed.

In the fourth means, the operation restart means for outputting a signal for restarting the drive of the inverter circuit when the output voltage of the DC power supply circuit returns to the normal voltage after the inverter circuit is stopped by the stop means. Is provided, the inverter circuit can be driven after the inverter circuit can operate normally, which can further contribute to the prevention of the destruction of the inverter circuit.

In the fifth means, the drive control status of the inverter circuit before the detection of the surge voltage is stored in the storage means, and when the operation of the inverter circuit is restarted by the operation restart means, the drive control state stored in the storage means is stored. Since the operation control means for driving the inverter circuit in the situation is provided, even if the operation of the inverter circuit is temporarily stopped by the detection of the surge voltage, the operation is not restarted from the beginning, which is convenient.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 showing the electrical configuration
1, the output terminal of the AC power supply 1 is connected between both terminals of the input capacitor 2 and is connected between the AC input terminals of a rectifier circuit 3 of a full-wave rectification type in which diodes are bridge-connected. The positive output terminal 3a of the rectifier circuit 3 is connected to the DC power supply line 5a via the choke coil 4, and the negative output terminal 3b is connected to the DC power supply line 5b. A smoothing capacitor 6 is connected between the DC power supply lines 5a and 5b. The rectifier circuit 3, the choke coil 4, and the smoothing capacitor 6 constitute a DC power supply circuit 7.

The heating coil 8 as a resonance coil constitutes a resonance circuit 10 together with the resonance capacitor 9, and the resonance circuit 10 and an IGBT (insulated gate bipolar transistor) as a switching element.
a bipolar transistor) 11 and a flywheel diode 12 as a rectifying element.
Is configured. A stainless steel pot A for cooking is placed on the heating coil 8 via a top plate (not shown), and an induction current is applied to the stainless steel pot A by a high-frequency current supplied to the heating coil 8. Flows, and the stainless steel pot A is heated by the resistance loss. The DC power supply line 5a is connected to the DC power supply line 5b via the heating coil 8 and the IGBT 11, the resonance capacitor 9 is connected in parallel to the heating coil 8, and the flywheel diode 12 is connected to the IGBT 11
Are connected in anti-parallel.

The input control unit 14 is provided with a current transformer 15 for detecting an input current. The input current from the commercial power supply 1 is detected by the current transformer 15 and a predetermined input current is detected. The difference from the level (heating intensity) is calculated and output to the output side as an input control signal. The drive circuit 16 is provided with a current transformer 17 as a phase detecting means, and changes the phase of the resonance current of the resonance capacitor 9 to the current transformer 1.
7, the ON timing and the ON time of the IGBT 11 are set based on the phase detection and the input control signal, and an ON signal St is output to be given to the gate of the IGBT 11.

The surge detection circuit 18 is connected between the positive output terminal 3a and the negative output terminal 3b of the rectifier circuit 3 of the DC power supply circuit 7, and a capacitor 19 and a resistor 20 are connected in order from the positive output terminal 3a. And a surge detection signal is output from a connection point 18a between the capacitor 19 and the resistor 20. This surge detection circuit 18
Is supplied to a stop / restart circuit 21 which also serves as a stop means and an operation restart means.

The stop / restart circuit 21 comprises a pulse amplifier circuit 22 and a Schmitt circuit 23, as shown in FIG. The pulse amplification circuit 22 includes a resistor 24,
It comprises a diode 25, a resistor 26, an NPN transistor 27 for amplification, and a delay circuit 28. The delay circuit 28 is configured by connecting a resistor 28a and a capacitor 28b in series between the DC power supply Vcc and the ground. Output V from connection point 18a of surge detection circuit 18
f is supplied to the base of the transistor 27 via the resistor 24. The collector of the transistor 27 is connected to the resistor 28a and the capacitor 28b of the delay circuit 28.
Is connected to the connection point.

The Schmitt circuit 23 is constructed by connecting NPN transistors 29, 30 and 31 and resistors 32 to 38 as shown in the figure. A signal Sk for stopping and restarting the driving is output.

The control circuit 39, which is an operation control means, includes a microcomputer and the like. The control circuit 39 includes a heating cooking time setting switch, a heating intensity setting switch, a cooking start switch, a cooking end switch, and the like. , A display 41 for displaying during the heating operation, the set heating intensity and the like, and a non-volatile memory 42 as storage means.

The output signal St of the drive circuit 16 and the output signal Sk of the stop / control circuit 21 are given to respective input terminals of an AND circuit 43. The output terminal of the AND circuit 43 is connected to the base of the IGBT 11. In addition, stop
The output signal Sk of the control circuit 21 is also supplied to the control circuit 39.

The operation of the above configuration will be described. Now, when the start switch is operated after setting the heating intensity and the cooking time with the various switches 40, the drive circuit 16 outputs a signal St for turning on the IGBT 11. In this case, during normal operation, the output signal Sk of the stop / restart circuit 21 is at a high level, and the IGBT 11 is turned on / off according to this signal St. That is, IGBT11
When a signal St (gate voltage) is applied to the gate of
The GBT 11 is turned on, and the heating coil 8 and the IGBT 1 are turned on.
The current IB of FIG. At time t0, the IGBT 11 is turned off, the heating coil 8 and the resonance capacitor 10 resonate, and a current IC (resonant current) shown in FIG.

On the other hand, the voltage of the heating coil 8 is
When 1 is on, the input voltage VDC is directly applied, and when the IGBT 11 is off, an attenuated resonance waveform due to L, C, and R resonances occurs, and the voltage value is the difference between the collector voltage VDC and the input voltage VDC.

Thereafter, when VD becomes smaller than VDC, the current of the heating coil 8 is reduced by the smoothing capacitor 6 and the flywheel diode 1 as shown by the current IB 'in FIG.
2, the heating coil 8 and the resonance capacitor 9
Becomes almost the same value as the input voltage VDC again. Thereafter, the current IB ′ becomes “0” at time t4 in FIG. 3, but at time t3 between times t2 and t4, the signal S
t is given to the gate of the IGBT 11 and again the IGBT 11
11 turns on and the current IB flows through the heating coil 8. Thus, the inverter circuit 13 operates, and the stainless steel pot A is induction-heated. During normal operation of the inverter circuit 13, a full-wave rectified waveform voltage is applied to the surge detection circuit 18 at the frequency of the AC power supply 1 of the rectifier circuit 3. The differential waveform does not appear.

During the operation of the inverter circuit 13, the control circuit 39 counts the elapsed time from the start of the operation, and stops the drive of the drive circuit 16 when the counted time reaches the set cooking time. I have to.

Here, when a lightning surge voltage is applied to both ends of the AC power supply 1, a surge voltage as shown in FIG. The first wave of the voltage Vb in FIG. 4B is a waveform in which a surge voltage is charged to the smoothing capacitor 6 via the choke coil 4, and the second wave is a reverse voltage waveform by the choke coil 4 after being charged by the surge current. is there.

When the surge voltage is applied, in the surge voltage detecting circuit 18, the capacitor 19 and the resistor 2 are connected.
With 0, a voltage Vf obtained by differentiating the output waveform of the rectifier circuit 3 is output. That is, a change in the surge voltage is detected. This output Vf is applied to the base of the transistor 27 of the pulse amplifier circuit 22 of the stop / restart circuit 21. The transistor 27 is turned on to amplify Vf, discharge the charge stored in the capacitor 28b of the delay circuit 28, and invert the transistors 29, 30, and 31 so that the respective collector voltages are reduced as shown in FIG. It changes like (I) and (J). As a result, the collector voltage of the transistor 31 in the output stage, that is, the output signal Sk changes to low level. As a result, the output of the AND circuit 43 becomes low level regardless of the output of the signal St from the drive circuit 16, that is, the base voltage becomes "0", the IGBT 11 is forcibly turned off, and the operation of the inverter circuit 13 stops. .

Here, when the surge voltage is detected, in other words, when the output voltage Sk of the stop / restart circuit 21 becomes low level, the control circuit 39 drives the inverter circuit 13 based on this when the surge voltage is detected. The control state, for example, the set heating intensity, the set heating cooking time, and the elapsed time from the start of the operation are stored in the nonvolatile memory 42.

Thereafter, when the change in the surge voltage stops, the transistor 27 is turned off, the capacitor 28b is charged by the resistor 28a, and when a time (predetermined time) determined by the time constant elapses, the voltage becomes the predetermined voltage, and each transistor 2b is turned off.
The output signals Sk become high level by the inversion operation of 9, 30, 31 and the driving of the inverter circuit 13 can be restarted. At this time, the control circuit 39 controls the nonvolatile memory 42
A command signal corresponding to the drive control situation stored in the inverter circuit 13 is output to the input control unit 14 and the drive circuit 16.
Drive. The predetermined time is set in advance to a time sufficient for the output voltage VDC of the DC power supply circuit 7 to return to the normal voltage.

According to this embodiment, the capacitor 19 is provided between the positive output terminal 3a and the negative output terminal 3b of the rectifier circuit 3 of the DC power supply circuit 7 in order from the positive output terminal 3a side.
And a resistor 20, and a surge detection circuit 18 for outputting a surge detection signal from a connection point 18a between the capacitor 19 and the resistance 20 is provided. Therefore, a differential waveform signal is output from the connection point 18a which is an output terminal. As a result, a steep rise of the surge voltage can be quickly detected. Then, a stop / restart circuit 21 is provided which functions as a stop means for outputting a signal (low level of the output signal Sk) for stopping the operation of the inverter circuit 13 based on the surge detection signal from the surge detection circuit 18. Therefore, based on the quick surge detection, the inverter circuit 1
3 can be stopped to prevent the inverter circuit 13 from being destroyed. Moreover, the surge detecting circuit 18 is composed of a capacitor 19 resistor 20. The rectifier circuit 3 Sir
This also acts as a snubber circuit for the rectifier circuit 3 to protect the rectifier circuit 3.

In particular, according to the present embodiment, the stop / restart circuit 2
1 is also functioned as operation restart means for outputting a signal (high level of the output signal Sk) for restarting the drive of the inverter circuit 13 with a delay of a predetermined time after the inverter circuit 13 stops. Therefore, the inverter circuit 13 can be driven after the influence of the surge voltage is eliminated, which can further contribute to preventing the inverter circuit 13 from being broken.

Further, according to this embodiment, the control circuit 39 stores the drive control status of the inverter circuit 13 before the detection of the surge voltage in the nonvolatile memory 42 as storage means.
When the operation of the inverter circuit 13 is restarted, the inverter circuit 13 is driven in the drive control state stored in the nonvolatile memory 42. Therefore, the operation of the inverter circuit 13 is temporarily stopped by detecting the surge voltage. However, it is convenient that driving is not restarted from the beginning.

FIGS. 5 and 6 show a second embodiment of the present invention. In this embodiment, a surge detecting circuit 5 is shown.
1 is different from the first embodiment. That is, the surge detection circuit 51 has the following configuration. A capacitor 52, a diode 53 having an anode connected to the capacitor 52, and a resistor 54 connected to a cathode of the diode 53 are connected between input terminals of the rectifier circuit 3 of the DC power supply circuit 7. The light emitting diode 55 is connected in anti-parallel. The light emitting diode 55 and the phototransistor 56 constitute a photocoupler 57.

In such a surge detection circuit 51, the light emission of the light emitting diode 55 corresponding to the connection point between the capacitor 52 and the resistor 54 is used as a surge detection signal, based on which the phototransistor 56 is turned on / off. The Schmitt circuit 23 operates in the same manner as in the first embodiment via the delay circuit 28 of the stop / restart circuit 58 by turning on / off the phototransistor 56.
That is, when the surge voltage is applied, a differential waveform voltage is generated in the light emitting diode 55 located at the connection point between the capacitor 52 and the resistor 54 of the surge detection circuit 51, and this emits light. As a result, the phototransistor 56 is turned on, and the charge stored in the capacitor 28b of the delay circuit 28 is discharged, and the transistors 29, 30, and 31 perform an inversion operation.
The collector voltage of the transistor 31 in the output stage, that is, the output signal Sk changes to low level. As a result, the driving circuit 1
Regardless of the output of the signal St from No. 6, the output of the AND circuit 43 becomes low level, that is, the base voltage becomes “0”, the IGBT 11 is forcibly turned off, and the operation of the inverter circuit 13 stops.

The second embodiment has the same effects as the first embodiment. That is, a capacitor 52, a diode 53, a light emitting diode 55, and a resistor 54 are connected between input terminals of the rectifier circuit 3 of the DC power supply circuit 7 to form a surge detection circuit 51, and a connection point between the capacitor 52 and the resistor 52 is provided. The surge detection signal is output from the light emitting diode 55 existing in the above, so that a steep rising of the surge voltage can be detected quickly. Also, a first embodiment
Similarly to the above, the capacitor 52 and the resistor 53
The surge detection circuit 51 also absorbs the surge of the rectifier circuit 3.
That is, the rectifier circuit 3 is configured as a snubber circuit.
To protect the rectifier circuit 3.

FIGS. 7 and 8 show a third embodiment of the present invention, which differs from the first embodiment in the following points. That is, in the first embodiment, the operation of the inverter circuit 13 is restarted a predetermined time after the detection of the surge voltage, but in the third embodiment, the output voltage VDC of the DC power supply circuit 7 is normal. After returning to the voltage, the operation of the inverter circuit 13 is restarted. That is, the control circuit 61 functioning as operation restart means includes:
A voltage detection circuit 62 for detecting the output voltage VDC of the DC power supply circuit 7 is connected. The stop circuit 63 serving as a stop means temporarily sets the output signal Sk to a low level at the time of detecting a surge voltage.
There is no delay function as in the restart circuit 21. The output signal Sk of the stop circuit 63 is also provided to the control circuit 61.

When the surge voltage is detected and the output signal Sk of the stop circuit 63 temporarily changes to a low level (returns to a high level immediately), the IGBT 11 is turned off. At the same time, the output signal Sk is
As shown in FIG. 8, the control circuit 61 sets the output signal Ss to the three-input AND circuit 64 to a low level based on the input of the low-level output signal Sk, The reading of the detection voltage VDC from 62 is started (step S1), and a determination is made as to whether or not the detection voltage VDC has returned to the normal voltage (step S2). Then, when the control circuit 61 determines that the detection voltage VDC from the voltage detection circuit 62 has returned to the normal voltage, it changes the output signal Ss to a high level (step S3), and restarts the operation of the inverter circuit 13.

According to the third embodiment, when the output voltage VDC of the DC power supply circuit 7 returns to the normal voltage after the stoppage of the inverter circuit 13 due to the detection of the surge voltage, the control circuit 61 starts the control circuit 61. 13, the signal Ss for restarting the drive of the inverter circuit 13 is output.
The inverter circuit 13 can be driven after the normal operation of the inverter circuit 3, which further contributes to prevention of the inverter circuit 13 from being destroyed.

[0042]

As apparent from the above description, the present invention has the following effects. According to the first aspect of the present invention, a capacitor and a resistor are connected between the positive output terminal and the negative output terminal of the rectifier circuit of the DC power supply circuit in order from the positive output terminal side. Surge absorption of rectifier circuit that outputs surge detection signal from connection point with
Because provided a surge detection circuit including, made from the output terminal serving as the connection point to the differential waveform signal is outputted, it can quickly detect a sharp rise in the surge voltage. And, since the stop means for outputting a signal for stopping the operation of the inverter circuit based on the surge detection signal from the surge detection circuit is provided, the operation of the inverter circuit can be stopped based on the quick surge detection, and the operation of the inverter circuit can be stopped. Destruction can be prevented. Further, the surge detection circuit including the capacitor and the resistor acts as a snubber circuit for the rectifier circuit, and can protect the rectifier circuit.

According to the second aspect of the present invention, a capacitor and a resistor are connected between input terminals of a rectifier circuit of a DC power supply circuit, and a surge detection signal is output from a connection point between the capacitor and the resistor. Since the surge detection circuit including the surge absorption of the rectifier circuit is provided, a differential waveform signal is output from the connection point, which is an output terminal, so that a steep rising of the surge voltage can be detected quickly. And, since the stop means for outputting a signal for stopping the operation of the inverter circuit based on the surge detection signal from the surge detection circuit is provided, the operation of the inverter circuit can be stopped based on the quick surge detection, and the operation of the inverter circuit can be stopped. Destruction can be prevented. In addition, surge detection consisting of a capacitor and a resistor
The output circuit acts as a snubber circuit for the rectifier circuit,
The rectifier circuit can be protected.

In the third means, the operation restart means for outputting a signal for restarting the drive of the inverter circuit after a predetermined time delay after the stop of the inverter circuit is provided, so that the influence of the surge voltage is eliminated. Later, the inverter circuit can be driven, which can further contribute to preventing the inverter circuit from being destroyed.

In the fourth means, the operation restart means for outputting a signal for restarting the drive of the inverter circuit when the output voltage of the DC power supply circuit returns to the normal voltage after the stop of the inverter circuit by the stop means. Is provided, the inverter circuit can be driven after the inverter circuit can operate normally, which can further contribute to the prevention of the destruction of the inverter circuit.

In the fifth means, the drive control status of the inverter circuit before the surge voltage is detected is stored in the storage means, and when the operation of the inverter circuit is restarted by the operation restart means, the drive control state stored in the storage means is stored. Since the operation control means for driving the inverter circuit in the situation is provided, even if the operation of the inverter circuit is temporarily stopped by the detection of the surge voltage, the operation is not restarted from the beginning, which is convenient.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an electric circuit diagram of a main part.

FIG. 3 is a current / voltage waveform diagram of each part.

FIG. 4 is a current / voltage waveform diagram of each part when a surge occurs.

FIG. 5 is an electric circuit diagram showing a second embodiment of the present invention.

FIG. 6 is an electric circuit diagram of a main part.

FIG. 7 is an electric circuit diagram showing a third embodiment of the present invention.

FIG. 8 is a flowchart showing control contents of a control circuit.

FIG. 9 is an electric circuit diagram showing a conventional example.

[Explanation of symbols]

1 is an AC power supply, 3 is a rectifier circuit, 4 is a choke coil, 6
Is a smoothing capacitor, 7 is a DC power supply circuit, 8 is a heating coil (resonant coil), 9 is a resonant capacitor, 10 is a resonant circuit, 11 is an IGBT (switching element), 12 is a flywheel diode (rectifying element), and 13 is an inverter. Circuit, 16 is a drive control circuit, 18 is a surge detection circuit, 1
9 is a capacitor, 20 is a resistor, 21 is a stop / restart circuit (stop means, operation restart means), 28 is a delay circuit, 39 is a control circuit (operation control means), 42 is a non-volatile memory (storage means), 51 is A surge detection circuit, 52 is a capacitor,
53 is a diode, 54 is a resistor, 55 is a light emitting diode, 56 is a phototransistor, 61 is a control circuit (operation control means, operation restart means), 62 is a voltage detection circuit, and 63 is a stop circuit (stop means).

Continuation of the front page (56) References JP-A-5-326122 (JP, A) JP-A-5-258886 (JP, A) JP-A-6-123748 (JP, A) JP-A-4-21192 (JP) , U) Hikaru Hei 1-159326 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/537 H02H 7/122 H02M 7/48 H05B 6/12

Claims (5)

(57) [Claims] 1. A DC power supply circuit having a rectifier circuit, a choke coil, and a smoothing capacitor to obtain a DC output from an AC power supply, a DC power supply circuit for converting a DC output of the DC power supply into high-frequency power, A resonance capacitor that forms a resonance circuit together with the resonance coil, a switching element connected in series between the output terminals of the DC power supply circuit through the resonance coil, and a rectification element connected in anti-parallel to the switching element. an inverter circuit having a smell that the switching element on-off controlled by and a driving circuit for operating the inverter circuit
Between the positive output terminal and the negative output terminal of the rectifier circuit of the DC power supply circuit, a capacitor and a resistor are connected in order from the positive output terminal side, and a surge is generated from a connection point between the capacitor and the resistor. Surge absorption of the rectifier circuit that outputs a detection signal
Yield even a surge detection circuit including, an induction heating cooker is characterized by providing a stop means for outputting a signal for stopping the operation of the inverter circuit based on the surge detection signal from the surge detecting circuit
Inverter device. 2. A DC power supply circuit having a rectifier circuit, a choke coil, and a smoothing capacitor to obtain a DC output from an AC power supply, a DC power supply circuit configured to convert a DC output of the DC power supply into high-frequency power, A resonance capacitor that forms a resonance circuit together with the resonance coil, a switching element connected in series between the output terminals of the DC power supply circuit through the resonance coil, and a rectification element connected in anti-parallel to the switching element. an inverter circuit having a smell that the switching element on-off controlled by and a driving circuit for operating the inverter circuit
A capacitor and a resistor are connected between input terminals of the rectifier circuit of the DC power supply circuit, and a surge detection signal is output from a connection point between the capacitor and the resistor .
Induction cooking, wherein the surge detection circuit, including the surge absorption, by comprising a stop means for outputting a signal for stopping the operation of the inverter circuit based on the surge detection signal from the surge detecting circuit vessel
Inverter device. 3. An operation restarting means for outputting a signal for restarting driving of the inverter circuit after a predetermined time delay after the inverter circuit is stopped by the stopping means. Induction heating cooker in
Barta equipment. 4. An operation restart means for outputting a signal for restarting driving of the inverter circuit when the output voltage of the DC power supply circuit returns to a normal voltage after the inverter circuit is stopped by the stop means. The inverter device for an induction heating cooker according to claim 1 or 2, wherein: 5. The storage means, wherein the drive control status of the inverter circuit before the detection of the surge voltage is stored in the storage means, and the drive control stored in the storage means when the operation of the inverter circuit is restarted by the operation restart means. 5. An inverter for an induction heating cooker according to claim 3, further comprising an operation control means for driving an inverter circuit in a situation.
Data device.