KR100961812B1 - Inverter switching control circuit of induction heater - Google Patents

Abstract

The present invention relates to an inverter switching control circuit for controlling an inverter switching element of an induction heater, and more particularly to a switching control circuit of an induction heating cooker having a single-stage voltage resonant inverter.

In the conventional single seat type electromagnetic induction heating method, the switching element is controlled. The existing method detects the resonance voltage and the input voltage and turns the inverter switching element on and off. In operation, a switching on signal is generated, which causes a problem that the switching device is damaged or the switching operation is stopped.

In the present invention, in order to solve the problems of the conventional single-stage voltage resonant inverter switching control circuit having such a problem, the inverter switching control oscillation circuit is used in combination with the self-expression and the steering equation, so that the inverter switching is controlled more stably than the conventional oscillation circuit. It is to provide a single type voltage resonance type electromagnetic induction heating switching control circuit.

Induction Heating Cooker, Single Stone Voltage Resonant Inverter, Inverter Switching Control Circuit, Induction heater, High Frequency Induction Heating Cooker

Description

Inverter switching control circuit of induction heater

The present invention relates to an inverter switching control circuit for controlling an inverter switching element of an induction heater, and more particularly, to a switching control circuit of an induction heating cooker having a single-stage voltage resonant inverter.

Induction heating cooker by switching the commercial DC voltage applied to the coil (ON / OFF) and the back electromotive force generated when the commercial voltage is turned off (working) by forming a strong magnetic field in the working coil, A magnetic container placed on a coil is heated to cook food.

Representative inverter switching control circuit in such an induction heating cooker uses a 1-stage voltage resonant type and a 2-seat type half bridge method, and the 1-stage voltage resonant type means that the oscillation output unit is composed of one. It can be seen that the output part is composed of two upper and lower parts, and an inverter switching control circuit which alternately outputs the upper output part and the lower output part.

According to the present invention, when a resonance occurs in a conventional single-station voltage resonant inverter switching control circuit, or when noise occurs in an AC input voltage, a trigger circuit operates in a resonance section so that a switching element is turned on. It was developed to solve the problem that the switching element is broken.

In an induction heating cooker or induction heating device, the inverter switching control circuit is the most important configuration and should be operated automatically according to the resonance time constant whose oscillation phase is determined by the work coil and the resonance capacitor. However, even if the L value of the work coil and the C value of the resonance capacitor in the induction heating cooker are constant, the resonance value and the resonance time constant change frequently according to the load, that is, the state of the cooking vessel.

On the other hand, as a method of controlling the output of the induction heating cooker, the resonance time constant and the oscillation timing of the oscillation means are controlled using a method of controlling the switching operation by using a phase detecting means for detecting a phase difference signal across the resonant circuit of the induction heating apparatus. By using the phase difference signal detected by the phase detection means in synchronization, a trigger signal that the oscillation means continuously oscillates is supplied.

However, the oscillation using the phase difference signal starts oscillation only when the trigger signal is received from the external, that is, the start signal generation means at the initial stage, and the oscillation timing of the oscillation means and the resonance time constant are not synchronized when the trigger signal is not supplied every oscillation period Oscillation is stopped.

In addition, when a high voltage is generated due to noise in the process of supplying a trigger signal, the switching element is damaged due to deformation of the gate waveform.

The first-stage voltage resonant inverter switching control circuit of the conventional induction heating cooker senses the switching on time by using the AC input voltage and the resonant voltage, and controls the switching element ON and OFF. When noise occurs in the AC input voltage, the trigger circuit operates in the resonance period, and the switching device is turned on, thereby causing the switching device to be broken. The present invention is intended to solve such a problem. It was developed.

Among the technical literatures related to induction heating cookers, the conventional patents and utility model documents relating to inverter switching control circuits can be seen as follows.

Patent Registration No. 10-279873

Name of invention: Switching element drive circuit of induction heating cooker

Patent Registration No. 10-261143

Title of the Invention: Switching Click Generation Circuit of Induction Heating Cooker

The two patents are invented by the inventor of the present invention.

Also

Patent Registration No. 10-529900

Name of Invention: Inverter Control Circuit of Induction Heating Electric Rice Cooker

Patent Registration No. 10-292382

Name of invention: pulse width modulation and inverter drive using the same

Patent Registration No. 10-546911

Name of Invention: Induction Heating Device

Patent Registration No. 10-714558

Name of invention: high frequency induction cooker

Patent Registration No. 10-628084

Name of Invention: Inverter Control Circuit of Induction Heating Cooker

Patent Registration No. 10-518167

Name of Invention: Induction Heating Cooker Using Self-Generated Half-Bridge Driver Integrated Circuit

Among the inverter switching control circuits of the conventional induction heating cooker, the inverter switch control circuit adopting the first type electromagnetic induction heating method uses two switching elements (IGBT) by using only one Insulate Gate Bipolar Transistor (IGBT). The circuit is simpler than the two-seat half-bridge type, and the switching circuit is used to provide an economical circuit. However, in the conventional single-seat electromagnetic induction heating method, the switching element is controlled. In this method, the switching device generates a switching ON signal in the resonance section when the noise is generated at the resonance voltage or the AC input voltage when the switching device is operated.

Therefore, the present invention is to solve the problem of the inverter switching control circuit of the electromagnetic induction heating cooker adopting the conventional first-seat type electromagnetic induction heating method, switching the self-resonant resonance time control circuit in the configuration of the inverter switching control circuit By combining a special circuit incorporating an off-time control circuit and a resonance trigger circuit which is a type resonance resonance control voltage detection circuit, a stable switching oscillation is outputted. Circuits) and other circuits (trigger circuits, which are resonance zero voltage detection circuits), complement the disadvantages of each other and provide the advantages to the inverter switching control circuit so that the inverter oscillation circuit is operated stably to operate the inverter switching element. It is to provide a single-stage voltage resonant electromagnetic induction heating switching control circuit.

The present invention is a heating coil (working coil) 15 and the resonance capacitor 16 and the heating coil 15 and the switching element (IGBT) (Q ₁₎ and the switching element (IGBT for switching the resonant capacitor (16) ) in the first seokhyeong voltage resonance type inverter using a single switching element (Q ₁₎ which consists of a switching device (IGBT) for controlling the drive circuit (Q _1),

The switching element Q ₁ detects the phase difference between the input voltage Iv and the resonance voltage Rv by detecting the input voltage Iv and the resonance voltage Rv at both ends of the heating coil 15 and the resonance capacitor 16. Resonant trigger circuit 11 that sets the time point of the off time and the on time of?) To generate the zero resonant voltage, and the input voltage Iv and the resonant voltage Rv A self-contained switching off time fixing circuit 12 which provides a resonance time control means for preventing the switching element Q ₁ from operating when the voltage Rv is higher than the input voltage Iv.

The triggered resonance trigger circuit 11 and the self-powered switching off-time fixing circuit 12 for detecting the resonance zero voltage are connected to the inverter oscillation circuit 6 so that an abnormal oscillation voltage or noise occurs during resonance. 6) to provide an inverter switching control circuit of an induction heating cooker to control the switching element (Q1) by controlling the rule.

In the above, the operation of the switching off time fixing circuit 12 is configured such that the output of the inverter oscillation circuit 6 and the inverter switching on / off time (switching operating frequency) are controlled by the resonance trigger circuit 11. .

In the above, when the ON signal of the inverter oscillation circuit 6 is switched on, the resonance voltage Rv of the resonance trigger circuit 11 is sinked to zero the resonance voltage Rv, thereby resonating. The trigger circuit 11 is prevented from operating so that the ON time stabilization circuit 13 stabilizes the ON time of the switching element Q ₁ .

1 is a circuit block diagram of a conventional single-stage voltage resonant type electromagnetic induction heating cooker. In the conventional electromagnetic induction heating cooker, a rectifier circuit 1 for rectifying power sources AC ₁ and AC ₂ , and an input power compensation circuit 2 are provided. And output compensation circuit (3), input current sensing circuit (4), load sensing circuit (5), inverter oscillation circuit (6), overcurrent protection circuit (7), switching element (IGBT) drive circuit (8) inverter on It consists of a microprocessor (MCU) 21, an overvoltage protection circuit 10, a switching element Q ₁ , a heating coil 15, and a resonance capacitor 16. .

Since such a configuration is a basic configuration of a known high frequency induction heating cooker or a high frequency induction heating apparatus, a detailed description of the circuit is omitted.

According to the present invention, in the above-mentioned high frequency induction heating cooker circuit, an inverter oscillation circuit 6 for outputting an oscillation signal for operating the heating coil 15 and an oscillation signal output of the inverter oscillation circuit 6 are controlled. It has a switching off time fixing circuit 12, the self-switching switching off time fixing circuit 12 is to be operated in conjunction with the punching type resonance trigger circuit 11 for detecting the resonance control voltage.

The organic operation relationship between the resonance trigger circuit 11, the inverter oscillation circuit 6, and the switching off type fixed circuit 12 of the present invention will be described in detail as follows.

As shown in Fig. 3, the switching off time fixed circuit 12 converts the analog input into a digital signal in the comparator IC54 when the oscillation control voltage is input to the terminal of the comparator IC54 in the initial inverter switching oscillator circuit 6. Is input to + of comparator IC55.

The signal input to + of comparator IC55 begins to charge capacitor C473 up to the voltage divided by resistors R103 and R104 connected to the-terminal of comparator IC55.

At this time, the output of the comparator IC55 is output from the comparator IC55 until the voltage level input at the initial + is greater than the voltage level charged at-, and the switching element Q1 is turned on for this output time.

When the switching element Q1 is turned off, a resonance voltage is generated by the heating coil 15 and the resonance capacitor 16. When the resonance voltage Rv of the resonance capacitor 16 is smaller than the level of the input voltage Iv. The switching element Q1 should be turned on again, and it is the triggered resonance trigger circuit 11 that controls it.

In the present invention, the resonant trigger circuit 11 for detecting the resonant zero voltage is input with the reference signal of the comparator IC53A and the resonant voltage is input through the resistors R1, R592, R591, and R590 at the terminal.

When the resonance trigger circuit 11 operates by comparing the gain signal in the comparator IC53A, the oscillation control voltage and the signal filled in the negative terminal of the comparator IC55 are discharged to prevent the switching oscillation circuit operation.

After that, when the resonance trigger circuit 11 is turned off, the inverter oscillation circuit 6 operates again and outputs a signal from the comparator IC55 to operate the switching element Q1.

The switching element Q1 is operated continuously in the same manner as described above to heat the load (heating pot) by the heating coil 15 and the resonant capacitor 16.

In the operation as described above, when noise is introduced into the input voltage Iv from the signal input to the resonant voltage Rv and the comparator IC53 + terminal, the resonance trigger circuit 11 operates in the generation region of the resonance voltage Rv. The inverter oscillation circuit 6 is operated.

At this time, if the switching element Q ₁ operates at a point where the resonance voltage is high, the switching element Q ₁ is damaged.

In order to make up for this drawback, the switching-off type fixing circuit 12, which is a self-oscillating circuit for controlling the resonance time so that the inverter generation circuit 6 does not operate unconditionally during the resonance time after the switching element Q ₁ operates, In addition, to control the inverter oscillation circuit (6).

Referring to such a configuration in more detail as follows.

The inverter oscillation circuit 6 has a resistor R109 and a capacitor C210 connected to the + terminal of the comparator IC54, an oscillation control voltage is input, connected to R104 and the + terminal of the comparator IC55 at the output of the comparator IC54. A resistor R103 and a R105 capacitor C473 are connected to the terminal, a diode D1 is connected in the forward direction between the negative terminal and the + terminal of the comparator IC55, and the resistors R102 and R101 are connected to the output of the comparator IC55.

The initial inverter oscillation circuit 6 is operated to generate the output of the comparator IC55. The output comparator IC56 and the comparator IC57 of the switching off time fixing circuit 12 initialize the switching off time fixing circuit 12 by this output.

In other words, the comparator IC56 is operated by the output signal of the comparator IC55, and the voltage charged to the + terminal of the comparator IC57 is discharged to the comparator IC56 like the signal divided by the -terminal resistors R305 and R306 via the diode D1.

When the output of the comparator IC55 is turned off, the switching element Q1 of FIG. 2 is also turned off to generate a resonance voltage at the heating coil 15 and the resonance capacitor 16. During the resonance time, the switching off time fixing circuit of FIG. (12) is operated so that a signal having a constant voltage divided by the resistors R305 and R306 is input to the negative terminal of the comparator IC57, and the voltage begins to be charged by the capacitor C575 at the positive terminal. The inverter oscillation circuit 6 is not operated until the signal charged in the capacitor C575 becomes larger than the signal input to the negative terminal of the comparator IC57.

The triggered resonance trigger circuit 11 performs an operation of detecting that the resonance voltage Rv becomes zero volts.

 The diode D704 is connected in the reverse direction to the + terminal of the comparator IC53A, the resistor R710 is connected, and the resistors R1, R592, R591, R590 and capacitor C691, the diode D518 are connected to the negative terminal of the comparator IC53A, and the comparator IC53A is connected. The output terminal of has a circuit configuration connected to the + terminal of the inverter oscillation circuit 6 and the output terminal of the off-time fixing circuit 12.

In this type of resonance trigger circuit 11, the switching element Q ₁ is prevented from being turned on until the resonance voltage drops to zero voltage in the OFF state. (The resonance trigger circuit 11 which operates as described above). May be referred to as a resonant zero voltage sensing circuit.)

This type of resonant trigger circuit 11 and the self-switching switching off time fixing circuit 12 controlling the switching off time simultaneously control the inverter oscillation circuit 6 so that an abnormality occurs in the input voltage Iv or when the resonance occurs. When the noise of the input voltage is generated, the inverter switching oscillation control circuit 6 is prevented from malfunctioning during the resonance time, thereby preventing the switching element Q1 from being damaged.

In the switching-off time fixing circuit 12, resistors R305 and R306 are connected to the comparator IC57 terminal, and the divided voltages of the resistors R305 and R306 are input.

A resistor R304 and a capacitor C575 are connected to the comparator IC57 + terminal, a diode D1 is connected in the forward direction of the negative terminal of the + terminal of the comparator IC57, a comparator IC56 output is connected to the comparator IC57-terminal, and a resistor is connected to the comparator IC56 + terminal. R3 is connected to R302,

The comparator IC56 terminal has a circuit configuration in which an inverter switching on / off output signal is connected to the comparator IC56 terminal via a diode D2.

Resistor R305 and R306 are connected to the comparator IC57 terminal, the divider voltage of resistors R305 and R306 are input, resistor R304 and capacitor C575 are connected to the comparator IC57 + terminal, and the + terminal of the comparator IC57 is connected in the forward direction of the-terminal. The diode D1 is connected, the negative terminal of the comparator IC 57 is connected to the collector C of TR (Q7), the resistor R1 is connected to the base (B) terminal of the TR (Q7), and the inverter oscillation circuit 6 It has a circuit configuration to which an output is input.

The switching off time fixing circuit 12 may be referred to as an inverter switching oscillation monitoring circuit by sensing the inverter oscillation circuit 6 to operate the inverter oscillation circuit 6.

The on time stabilization circuit 13 has a resistor R2 and R3 connected to the + terminal of the comparator IC11, the output of the inverter oscillation circuit 6 is connected to the-terminal, and the output portion of the comparator IC11 is a resonance trigger circuit 11. Has a circuit configuration connected to the negative terminal of the comparator IC53A.

The on time stabilization circuit 13 serves to stabilize the output of the inverter oscillation circuit 6 by preventing the resonance voltage of the resonance trigger circuit 11 from operating during the on time of the inverter switching device. .

That is, when the signal of the initial inverter oscillation circuit 6 is input to the-terminal of the comparator IC11, the voltage becomes higher than the + terminal, so that the signal of the resonance voltage sensing unit of the resonance trigger circuit 11 sinks and the inverter oscillation circuit 6 This stabilizes the output of switching, ie the switching on time.

The switching control circuit of the existing single-stage voltage resonant inverter consists of the oscillation control circuit only by the AC input voltage and the resonant voltage. Therefore, the AC input voltage is switched due to noise generation depending on the usage environment (other home appliances or high power consumption products). An abnormal operation of the oscillation circuit may cause the inverter switching element to be damaged or the switching operation may be stopped.

The present invention solves the above problems and obtains the resonance time after switching on, and then resonates with the switching off time control circuit so that the inverter oscillation control circuit can be normally controlled even if noise is generated in the input voltage during the high resonance voltage generation time. It has the effect of controlling the stable inverter switching operation by using the self-feeding type and the punching type oscillating circuit incorporating the trigger circuit.

Prior to describing the details for the implementation of the present invention, the problems of the inverter oscillation circuit of the electromagnetic induction heating cooker will be described through the waveform diagram comparing the waveform of the present invention with the waveform of the present invention.

FIG. 5 shows waveforms of a single-stone resonant voltage type inverter induction heating switch operation, where waveform 1 is an ON waveform of inverter switching element Q ₁ and waveform 2 is switched off when switching element Q ₁ is loaded. This is the resonance voltage (Rv) waveform generated from the resonant capacitor.

As shown in the waveforms 1 and 2, it can be seen that the inverter oscillation circuit for operating the switching element Q ₁ operates to some extent when there is a load.

The reason is that the capacity of load R, heating coil L and resonant capacitor is fixed, so that the inverter generation circuit can be operated (ON / OFF) by calculating the resonance time by calculating the resonance time and the conventional inverter. The switching oscillation circuit is controlled.

As a means for controlling the existing inverter oscillation circuit, a switching off time fixed circuit can be used. The switching off time fixed circuit is shown in waveform 3 when there is no load or when the load container is heated. As the temperature rises, the R value of the load, the resistance value of the heating coil, and the capacitance value of the resonant capacitor change, and the resonance time increases as shown in the waveform 3 when the container R, which is the load R, is lifted during the inverter switching operation.

At this time, since the switching operation time is fixed to an integer value of R and C, the off-time fixed circuit turns ON the switching element so that the switching element operates at the point D of the waveform 3 despite the increase in the resonance time as shown in the waveform 3. ON) signal is forced out.

This inverter switching operation waveform is shown in (B) of Waveform 1.

Therefore, when the switching element is operated in the induction heating cooker using the conventional single-stage voltage resonant inverter, the inverter switching operation can be performed to some extent when the heating coil is loaded, but this is the inverter oscillation that performs the operation of the switching element perfectly. It does not provide a circuit.

Because, as shown in waveform 3, there is no load (container) or the temperature rises, the L value of the heating coil and the capacitance value of the resonant capacitor change, so the resonance time is longer than when the load (container) is present. When the inverter (switching) oscillation control is performed by the off-time fixed circuit in the inverter oscillation circuit used, as shown in waveform 1 at the point D of the waveform 3, the ON signal goes out at the (n-) point. At this time, as shown in the waveform 3D point, the resonance time is long, and the switching element is turned on at the point where the resonance voltage Rv is higher than the input voltage Iv.

At this time, when the switching element is operated, a short current flows and the switching element is damaged.

In order to solve the problems of the conventional inverter oscillation circuit, the present invention incorporates a resonant trigger circuit method, which is a target inverter switching oscillation circuit, to control an inverter (switching) oscillation circuit.

When the switching operation of the single-stage voltage resonant inverter is compared with the conventional control method,

Adds a switching off-time control circuit to operate the switching operation stably without damaging the inverter switching element even if the change in the heating coil and the change in the heating coil due to the temperature increase and the resonance capacitor capacity change to some extent, regardless of the load variation or container presence. The inverter switching oscillator circuit is controlled so that the (inverter) switching element is turned on at the point where the resonance voltage is lower than the input power.

The present invention as such

Integrating the switching off time fixing circuit 12 and the resonance trigger circuit 11 into the inverter switching circuit 6 to control the switching operation of the inverter switching element Q ₁ .

When there is a load, when a resonance phenomenon occurs after the switching element Q ₁ is turned off, the switching off time fixing circuit 12 is primarily operated.

When the resonance voltage is high or when the input voltage is high, the inverter oscillation circuit 6 is not forcibly operated during the time when resonance occurs, and while the secondary voltage is configured with or without a load. Increasing or decreasing the resonance time due to the change in the value of its own element into a physical phenomenon due to the temperature rise of the switching element Q ₁ .

When the input voltage Iv input to the resonance trigger circuit 11 becomes larger than the resonance voltage Rv, the inverter oscillation circuit 6 is operated to resonate the inverter switching oscillation circuit operation that reduces switching loss of the switching element. By using the capacitor C691 in the resonance voltage sensing unit so that the voltage operates near the zero voltage, the switching element is damaged by delaying the time that is turned on until the resonance voltage Rv becomes the zero voltage. The loss can be reduced, thereby extending the life of the switching element (Q ₁ ).

The present invention uses the switching off time fixed circuit and the resonant trigger circuit as shown in Waveform 3 and Waveform 1 to solve the problem that the complete inverter switching operation cannot be controlled by the conventional off time fixed circuit alone. Inverter switching to control single-stage voltage inverter switching operation that allows the switching operation to switch at zero voltage, whether the resonant time increases or decreases even when the value of the device changes due to load fluctuations or temperature rise by applying the oscillation control circuit. It is to provide an oscillation control circuit.

1 is a block diagram of a conventional induction heating cooker

2 is a block diagram of an induction heating cooker according to the present invention

3 is a specific circuit diagram of the present invention.

4 is a circuit diagram of another embodiment of the present invention.

Figure 5 is a waveform diagram showing the problem of the existing circuit and the waveform of the operation of the present invention to solve it

<Explanation of symbols for the main parts of the drawings>

1 Rectifier circuit 2 Input voltage compensation circuit

3 Output compensation circuit 4 Input current sensing circuit

5 Load sensing circuit 6 Inverter oscillating circuit

7 Overvoltage Protection Circuit 8 IGBT Drive Circuit

9 Inverter ON / OFF control circuit 10 Trigger circuit

11 Resonant Trigger Circuit Q1 Switching Element

12 Switching off-time fixing circuit 12-1 Other embodiment of switching-off-time fixing circuit

13 On-time stabilization circuit 15 Work coil

16 resonant capacitor

21 microprocessor (MCU)

Rv resonant voltage

Iv input voltage

Claims (8)

A heating element 15 and a resonant capacitor 16, a switching element IGBT Q ₁ for switching the heating coil 15 and the resonant capacitor 16, and the switching element IGBT Q _1. In the electromagnetic induction heating method of the single-stone voltage resonant inverter type using the one switching element (Q ₁ ) composed of a switching element (IGBT) drive circuit for controlling The switching element Q ₁ detects the phase difference between the input voltage Iv and the resonance voltage Rv by detecting the input voltage Iv and the resonance voltage Rv at both ends of the heating coil 15 and the resonance capacitor 16. ), The resonance-type resonant trigger circuit 11 which makes the time of the OFF time and the ON time, and the input voltage Iv and the input voltage Iv and the resonant voltage Rv At higher time points, the self-contained switching-off time fixing circuit 12 which prevents the switching element Q ₁ from operating. The percussion resonance trigger circuit 11 and the self-contained switching off time fixing circuit 12 are connected to the inverter oscillation circuit 6 to protect the switching element Q1 by controlling them when an abnormal voltage or noise occurs. Inverter switching control circuit of an induction heating cooker characterized in that. The resonance trigger circuit (11) of claim 1, wherein the resonance voltage (Rv) of the resonance trigger circuit (11) is sinked in the switching ON signal of the inverter oscillator circuit (6) to zero the resonance voltage. Inverter switching control circuit of the induction heating cooker, characterized in that it has an ON TIME stabilization circuit (13) for stabilizing the ON time by preventing the operation. 2. The inverter switching of the induction heating cooker according to claim 1, wherein the operation of the switching off time control circuit 12 is controlled by the output of the inverter oscillation circuit 6 and the switching off time by the resonance trigger circuit 11. Control circuit. The inverter oscillator circuit 6 has a resistor R109 and a capacitor C210 connected to the + terminal of the comparator IC54, an oscillation control voltage is input, and an output of the comparator IC54 to R104 and a + terminal of the comparator IC55. The resistor R103, R105 capacitor C473 is connected to the negative terminal of the comparator IC55, the diode D1 is connected in the forward direction between the negative terminal and the + terminal of the comparator IC55, and the resistors R102 and R101 are connected to the output of the comparator IC55. Inverter switching control circuit of the induction heating cooker characterized in that. 2. The resonance trigger circuit (11) according to claim 1, wherein the diode D704 is connected in the reverse direction to the + terminal of the comparator IC53A, and the resistor R710 is connected. Resistor R1, R592, R591, R590 and capacitor C691, diode D518 for voltage down are connected to the negative terminal of the comparator IC53A, and the output terminal of the comparator IC53A is the + terminal of the inverter oscillator circuit 6 and the off time fixing circuit 12. Inverter switching control circuit of the induction heating cooker, characterized in that connected to the output terminal of the. The switching-off time fixing circuit 12 has resistors R305 and R306 connected to the comparator IC57-terminal, and the divided voltages of the resistors R305 and R306 are input. A resistor R304 and a capacitor C575 are connected to the comparator IC57 + terminal, a diode D1 is connected in the forward direction of the negative terminal of the + terminal of the comparator IC57, a comparator IC56 output is connected to the comparator IC57-terminal, and a resistor R3 to the comparator IC56 + terminal. This R302 is connected, An inverter switching control circuit of an induction heating cooker having a circuit structure in which an inverter switching on / off output signal is connected to a comparator IC56 terminal via a diode D2. The switching-off time fixing circuit 12 has resistors R305 and R306 connected to the comparator IC57-terminal, and the divided voltages of the resistors R305 and R306 are input. The resistor R304 and the capacitor C575 are connected to the comparator IC57 + terminal, the diode D1 is connected in the forward direction of the negative terminal of the + terminal of the comparator IC57, and the negative terminal of the comparator IC 57 is connected to the collector C of TR (Q7). Inverter switching control circuit of the induction heating cooker, characterized in that the TR (Q7) is connected to the resistor (R10) to the base (B) terminal and the output of the inverter oscillation circuit (6). 3. The on-time stabilization circuit 13 according to claim 2, wherein the resistors R2 and R3 are connected to the + terminal of the comparator IC11, the output of the inverter oscillation circuit 6 is connected to the-terminal, and the output of the comparator IC11 is a resonance trigger circuit. An inverter switching control circuit for an induction heating cooker, characterized in that it is connected to the negative terminal of the comparator IC53A of (11).

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