KR0152111B1 - Induction Heating Cooker - Google Patents

Abstract

The present invention relates to an induction heating cooker for cooking by supplying a constant resonant current to a heating coil, comprising: zero voltage detecting means for detecting a zero potential of a commercial AC voltage input from an AC power input terminal; Control means for controlling the entire operation in synchronization with the zero potential of the commercial AC voltage detected by the controller; variable frequency oscillation means for varying the oscillation frequency according to the control of the control means; and a switch according to the oscillation frequency from the variable frequency oscillation means. An inverter driving means for outputting a driving signal to drive the sub-element, an inverter means for receiving a DC voltage input from the rectifying means according to a driving signal output from the inverter driving means, and generating a high frequency signal, and driving by the inverter means Current detecting means for detecting an amount of current variation input to the heating coil; Characterized by comprising comparison means for comparing the input current and the change amount is set based on the amount of current flowing in the heating coil is detected by the current detector means.

Description

Induction Heating Cooker

1 is a schematic control circuit diagram of a conventional induction heating cooker.

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

3 is a detailed circuit diagram of an induction heating cooker according to an embodiment of the present invention.

4 is an output waveform diagram in each part of FIG.

4A is an AC input waveform diagram at point A of FIG. 3,

4b is an output waveform diagram at point B of FIG.

4C is an output waveform diagram at point C of FIG. 3 when the operation switch is turned on.

4d is an output waveform diagram at point D of FIG. 3 when the operation switch is turned on.

Fig. 4E is an output waveform diagram at point E of Fig. 3 when the operation switch is on.

4f is an output waveform diagram at point C of FIG.

4G is an output waveform diagram at point D in FIG. 3 at the time of operation switch off.

* Explanation of symbols for main parts of the drawings

1: AC power input terminal 10: rectification means

20: zero voltage detection means 30: control means

40: variable frequency oscillation means 41: frequency oscillator

42: normal frequency holding unit 43: lowest frequency holding unit

50: inverter driving means 60: inverter means

65 heating coil 70 current detecting means

71: resonant current detector 73: input current detector

80: load setting means 90: comparison means

The present invention relates to an induction heating cooker for cooking by supplying a constant resonance current to the heating coil.

In general, a conventional induction heating cooker is Japanese Patent Laid-Open No. 56-123686.

As shown in FIG. 1, the induction heating cooking apparatus disclosed in the publication has a rectifying means 100 for full-wave rectifying a commercial alternating voltage input from the AC power input terminal 1, and from the rectifying means 100. The drive unit 110 generates a high frequency signal by receiving the output DC voltage, and outputs a driving signal to turn on / off the switching element TR1 of the inverter unit 110, as well as the induction heating. Inverter control means 120 for controlling the overall operation of the cooker, and the alternating current that is changed when the heating coil 65 is driven to sense the current input to the heating coil 65 driven by the inverter means 110 The input current detecting means 130 detects the input current of the power input terminal 1 and outputs it to the inverter control means 120.

In the induction heating cooker configured as described above, when the user turns on the operation switch (not shown), the commercial AC voltage input from the AC power input terminal (1) by the bridge rectifier 101 of the rectifying means (100) Full-wave rectified by

The ripple component included in the DC voltage full-wave rectified by the bridge rectifier 101 is filtered through the smoothing capacitor C1, and the filtered DC voltage is charged in the smoothing capacitor C1.

At this time, when the synchronous control signal output from the inverter control means 120 is applied to the base terminal of the switching element TR1 of the inverter means 110, the switching element TR1 is turned on and the smoothing capacitor ( Due to the voltage charged in C1), the current flows through the heating coil 65 through the switching element TR1 to the resonance capacitor C2, thereby forming a closed circuit.

Therefore, as the resonant current flows through the heating coil 65, an eddy current is generated on the surface of the cooking vessel 66 mounted on the heating coil 65 by this current, and the cooking vessel 66 begins to heat.

However, in such an induction heating cooker, since a high resonance voltage is generated by driving a heating coil using one switching element in the inverter means, when the commercial AC voltage input from the AC power input terminal is 220V, the switching is performed. As the switching speed of the device is slowed down, the internal pressure is increased, and the switching device may not only be damaged but also the safety of the device may not be guaranteed.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to detect a current fluctuation amount input to a heating coil by a current detecting means, so that a constant resonant current is constant in the heating coil even when the input power supply voltage is changed. It is to provide an induction heating cooker capable of cooking by supplying.

Another object of the present invention is to reduce the rush current flowing through the switching element through the switching element during the initial operation of the induction heating cooker to prevent damage to the switching element and the heating coil and at the same time to ensure the safety of the device To provide a guaranteed induction cooker.

Still another object of the present invention is to provide an induction heating cooker capable of safely driving a device by varying an oscillation frequency and stabilizing output power when using a nonmetallic cooking container by detecting a resonance current flowing in a heating coil by a resonance current detector. have.

In order to achieve the above object, the induction heating cooker according to the present invention comprises rectifying means for full-wave rectifying the commercial AC voltage input from the AC power input terminal into a DC voltage, and detecting the zero potential of the commercial AC voltage input from the AC power input terminal. A control means for controlling the overall operation of the induction heating cooker in synchronization with the zero potential of the zero voltage detection means, the commercial alternating voltage detected by the zero voltage detection means, and receiving a control signal output from the control means to generate an oscillation frequency. Variable frequency oscillating means for outputting, inverter driving means for outputting a driving signal to drive a switching element in accordance with the oscillation frequency output from the variable frequency oscillating means, and from the rectifying means in accordance with a driving signal from the inverter driving means. Generates high frequency signal by receiving output DC voltage Is an inverter means, current detecting means for detecting a current variation input to the heating coil to supply a constant resonance current to the heating coil driven by the inverter means, and an input current of the heating coil detected by the current detecting means. And a comparison means for outputting a comparison voltage signal to the variable frequency oscillation means so as to vary the oscillation frequency by comparing the variation amount and the reference current amount set by the load setting means.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the rectifying means 10 performs full-wave rectification of a commercial alternating voltage input from the AC power input terminal 1 by direct current, so that the rectifying means 10 is the AC power input terminal 1. The bridge rectifier 11 for full-wave rectification of the commercial alternating voltage from the filter, and the ripple component contained in the direct-current rectified voltage by the bridge rectifier 11 are filtered, and the full-wave rectified DC voltage is charged. A smoothing capacitor C1 connected to the output terminal of the bridge rectifier 11 and one side thereof are connected to the bridge rectifier 11 so as to increase the rectifying efficiency of the bridge rectifier 11, and the other side of the smoothing capacitor ( It consists of the choke coil L1 connected to C1).

The zero voltage detection means 20 detects the zero potential of the commercial AC voltage input from the AC power input terminal 1, and the control means 30 receives the zero voltage detection signal output from the zero voltage detection means 20. The induction heating cooker is turned on or off in synchronization with the zero potential of a commercial AC voltage as well as a microcomputer that controls the overall operation of the induction cooker.

In addition, the variable frequency oscillation means 40 receives the control signal output from the control means 30 so as to vary the oscillation frequency according to the heating coil 65, and oscillates a constant variable frequency. 40 receives a synchronous control signal output from the control means 30 and generates a frequency oscillation portion 41 generated according to the heating coil 65, and a synchronous control signal output from the control means 30 Received from the stationary frequency maintenance unit 42 and the frequency oscillation unit 41 to lower the voltage input to the frequency oscillator 41 so that the oscillation frequency generated in the frequency oscillator 41 maintains the normal frequency state The oscillation frequency is composed of a lowest frequency holding part 43 which maintains the lowest frequency of the oscillation frequency to prevent the oscillation frequency from falling below the audible frequency.

In addition, the inverter driving means 50 switches the switching elements TR1 and TR2 of the inverter means described later according to the variable frequency oscillated from the variable frequency oscillating means 40 to alternately turn on or turn off the switching. A drive signal is output to the base terminals of the elements TR1 and TR2.

In addition, the inverter means 60 receives the DC voltage input from the rectifying means 10 according to the drive signal output from the inverter driving means 50 and generates a high frequency signal. Switching elements TR1 and TR2 which alternately turn on / off to receive a driving signal output from the inverter driving means 50 to generate a resonance current in the heating coil 65, and the switching element TR1. Parallel connection to the switching elements TR1 and TR2 to form a voltage source while charging and charging the voltage applied to the smoothing capacitor C1 of the rectifying means 10 during the turn-on / turn-off operation of TR2. The inrush current flowing through the resonant capacitors C2 and C3 during the initial turn-on operation of the resonant capacitors C2 and C3 and the switching elements TR1 and TR2, thereby reducing the switching elements TR1 and TR2. And the resonant capacitors C2 and C3 to protect the heating coil 65. A switching element for protecting the switching elements TR1 and TR2 by bypassing the divided resistors R1 and R2 connected in parallel with each other and the counter electromotive force generated during the turn-off operation of the switching elements TR1 and TR2. It consists of protective diodes D1 and D2 connected in parallel to the collector terminals and the emitter terminals of TR1 and TR2, respectively.

On the other hand, the heating coil 65 generates an eddy current in the cooking vessel 66 in accordance with the sinusoidal alternating current generated by the turn-on / turn-off operation of the switching elements (TR1, TR2) in the cooking vessel 66 One side is connected to the connection point of the switching elements TR1 and TR2 so as to heat the food, and the other side is connected in series to the connection point of the resonance capacitors C2 and C3.

Then, the current detecting means 70 detects the amount of current variation input to the heating coil 65 driven by the inverter means 60, so that the current detecting means 70 is connected to the inverter means 60. A resonance current detector 71 for detecting a varying resonance current of the heating coil 65 to supply a constant resonance current to the heating coil 65 driven by the heating coil 65, and the cooking vessel 66 mounted on the heating coil 65; ) Is composed of an input current detection unit 73 which detects the amount of change in current of the AC power input terminal 1 and outputs it to the control means 30 so as to determine whether or not is a proper container.

The resonant current detection unit 71 includes a current transformer CT1 for detecting a resonance current variation amount of the heating coil 65 driven by the inverter means 60, and a resonance current variation amount detected by the current transformer CT1. A resistor R3 connected in parallel to the secondary side of the current transformer CT1, a diode D3 for receiving a voltage signal converted by the resistor R3, and performing half-wave rectification, and by the diode D3. A resistor R6 and a capacitor C4 having one side connected to the cathode terminal of the diode D3 and the other side grounded to filter the ripple component included in the half-wave rectified DC voltage.

In addition, the input current detector 73 receives a commercial AC voltage output from the AC power input terminal 1 and detects an input current fluctuation amount of the AC power input terminal 1 that changes when the heating coil 65 is driven. CT2, a resistor R4 connected in parallel to the secondary side of the current transformer CT2 so as to convert an input current variation detected by the current transformer CT2 into a voltage, and a voltage converted by the resistor R4. A bridge rectifier 731 for full-wave rectifying the signal by direct current, and a resistor connected in parallel to the output terminal of the bridge rectifier 731 to filter the ripple component included in the direct-current rectified voltage by the bridge rectifier 731 ( R5) and capacitor C5.

Further, the load setting means 80 is a variable resistor VR for setting a current limit which is a reference current amount of the heating coil 65 to supply a constant resonance current to the heating coil 65 driven by the inverter means 60. This load setting means 80 sets the current limit in accordance with the product specification by the designer.

In addition, in the drawing, the comparing means 90 receives a voltage signal proportional to the amount of current variation input to the heating coil 65 detected by the current detecting means 70 at the non-inverting terminal (+) and simultaneously It is a comparator for receiving a reference voltage signal having a current limit set by the load setting means 80 from the inverting terminal (-) and comparing the input voltage to the variable frequency oscillation means 40 to vary the voltage.

On the other hand, reference numeral 5 is an operation switch for turning on or off the induction heating cooker.

4 is an output waveform diagram at each part of FIG. 3, FIG. 4a is an AC input waveform diagram at point A of FIG. 3, FIG. 4b is an output waveform diagram at point B of FIG. 3, and FIG. Output waveform diagram at point C in FIG. 3 when the operation switch is on, and FIG. 4d is output waveform diagram at point D in FIG. 3 when the operation switch is on, and FIG. 4f is an output waveform diagram at point C in FIG. 3 at the time of operation switch off, and FIG. 4g is an output waveform diagram at point D in FIG. 3 at the time of operation switch off.

Hereinafter, the effect of the induction cooker configured as described above will be described.

First, when power is supplied to the induction heating cooker, a commercial AC input voltage represented by the waveform of FIG. 4A (AC input waveform diagram at point A of FIG. 3) is supplied from the AC power input terminal 1 to the rectifying means 10. do.

The commercial AC voltage (waveform shown in FIG. 4A) supplied to the rectifying means 10 is full-wave rectified by the DC rectifier through the bridge rectifier 11, and the ripple component included in the full-wave rectified DC voltage is a smoothing capacitor ( The filtered DC voltage is charged to the smoothing capacitor C1 while filtering through C1).

The voltage charged in the smoothing capacitor C1 is divided by the voltage dividing resistors R1 and R2 of the inverter means 60 and is applied to the resonant capacitors C2 and C3 by 1/2.

On the other hand, the zero voltage detecting means 20 detects the zero potential of the commercial AC voltage (waveform of FIG. 4A) supplied from the AC power input terminal 1, and outputs the waveform of FIG. 4B (waveform output at point B of FIG. 3). The zero voltage detection signal indicated by) is output to the control means 30.

At this time, when the user turns on the operation switch 5, the switch-on signal represented by the waveform of FIG. 4C (output waveform diagram at point C of FIG. 3) is input to the control means 30. FIG.

Therefore, the control means 30 receives the zero voltage detection signal (waveform of FIG. 4b) output from the zero voltage detection means 20 when the switch-on signal (waveform of FIG. In order to operate the induction heating cooker in synchronism with the zero potential, a synchronous control signal represented by the waveform of FIG. Output to the frequency holding unit 42.

Accordingly, the frequency oscillator 41 receives the synchronous control signal (waveform in FIG. 4d) output from the control means 30 to generate an oscillation frequency for driving the heating coil 65.

The oscillation frequency generated by the frequency oscillator 41 is the waveform of FIG. 4e input to the frequency oscillator 41 when the synchronous control signal (waveform in FIG. 4e) from the control means 30 is input (in FIG. 3). Output waveform at point E).

That is, when the voltage inputted to the frequency oscillator 41 (waveform of FIG. 4e) increases, the oscillation frequency also increases. When the voltage inputted to the frequency oscillator 41 (waveform of FIG. 4e) decreases, the oscillation frequency also decreases. The oscillation frequency (approximately, 20 to 30 KHz), which is thereby varied, is input to the inverter driving means 50.

At this time, the stationary frequency maintenance unit 42 receives the synchronous control signal (waveform of FIG. 4d) output from the control means 30 and converts the voltage (waveform of FIG. 4e) into the frequency oscillation unit 41 with a high voltage. By lowering to a low voltage in the oscillation frequency generated in the frequency oscillator 41 to maintain a normal frequency state.

When the oscillation frequency (about 20-30 KHz) generated by the frequency oscillator 41 is input to the inverter driving means 50, the inverter driving means 50 is heated in accordance with the oscillation frequency generated by the frequency oscillating portion 41. A drive signal for driving the coil 65 is output to the inverter means 60.

Accordingly, the inverter means 60 receives the drive signal output from the inverter driving means 50 from the base terminal of the switching elements TR1 and TR2, and the switching elements TR1 and TR2 are alternately turned on or off. Turn off operation.

When the switching element TR1 is turned on, a current is caused by the voltage charged in the smoothing capacitor C1 of the rectifying means 10 through the switching element TR1 and the heating coil 65 and the current transformer CT1. ) Flows through the resonant capacitor (C3).

At this time, the resonance current supplied to the heating coil 65 increases and decreases by a time constant determined by the heating coil 65 and the resonance capacitor C3, and the current amount determined by the time constant is zero (0). The switching element TR2 is turned on when the switching element TR1 is turned off.

When the switching element TR1 is turned on, current flows due to the voltage charged in the smoothing capacitor C1 of the rectifying means 10 through the resonant capacitor C2 and the heating coil C1. 65 flows to the switching element TR2.

At this time, the resonance current supplied to the heating coil 65 increases and decreases by a time constant determined by the heating coil 65 and the resonance capacitor C2, and the current amount determined by the time constant is zero (0). The switching element TR1 is turned on when the switching element TR2 is turned off.

By the turn-on / turn-off alternating operation of the switching elements TR1 and TR2 as described above, a sinusoidal AC current of 20 to 30 KHz flows through the heating coil 65, and the cooking placed on the heating coil 65 by this current is performed. As the eddy current is generated on the surface of the container 66, the cooking vessel 66 begins to heat.

On the other hand, during the initial turn-on operation of the switching elements TR1 and TR2, the half voltage of the voltage charged in the smoothing capacitor C1 is applied to the resonant capacitors C2 and C3, respectively. The inrush current flowing through the capacitors C2 and C3 is reduced to prevent breakage of the switching elements TR1 and TR2 and the heating coil 65.

At this time, the resonant current fluctuation amount that is changed at the time of driving the heating coil 65 according to the turn-on / turn-off alternating operation of the switching elements TR1 and TR2 is detected by the current transformer CT1 of the resonant current detector 71. The detected resonance current variation amount is converted into the voltage variation amount by the resistor R3.

The voltage signal converted into the voltage variation by the resistor R3 is inputted to the non-inverting terminal (+) of the comparison means 90 while being half-wave rectified through the diode D3.

In addition, the current transformer of the input current detector 73 changes the input current fluctuation amount of the AC power input terminal 1 which is changed when the heating coil 65 is driven in accordance with the turn-on / turn-off alternate operation of the switching elements TR1 and TR2. Detected at CT2, the detected input current fluctuation amount is converted into a voltage fluctuation amount through resistor R4.

The voltage signal converted into the voltage variation by the resistor R4 is inputted to the non-inverting terminal (+) of the comparison means 90 while being full-wave rectified to DC voltage through the bridge rectifier 731 and at the same time the control means 30. ) Is entered.

Therefore, the comparing means 90 is the resonance current fluctuation amount of the heating coil 65 detected by the resonance current detection unit 71 and the input current of the AC power input terminal 1 detected by the input current detection unit 73. A voltage signal proportional to the amount of change is received at the non-inverting terminal (+) and at the same time, a reference voltage signal having a current limit set by the load setting unit 80 is received at the inverting terminal (-) and compared.

The voltage signal compared by the comparing means 90 is fed back to the frequency oscillator 41 to vary the oscillation frequency.

At this time, the lowest frequency holding unit 43 prevents the falling of the voltage signal input to the frequency oscillator 41 so that the comparison voltage signal variable by the comparison means 90 is too low so that the oscillation frequency does not fall below the audible frequency. As shown in the waveform of Fig. 4E, the lowest frequency is maintained.

On the other hand, the control means 30 receives the voltage signal proportional to the input current of the AC power input terminal 1 detected by the input current detector 73, the cooking vessel 66 mounted on the heating coil (65) Is the appropriate load.

If the cooking vessel 66 is not placed on the heating coil 65 or a spoon, chopsticks, or the like is placed on the heating coil 65, excessive current flows momentarily through the switching elements TR1 and TR2, but the AC power input terminal ( The fluctuation amount of current input from 1) is very small to be negligible.

Therefore, the input current detection unit 73 detects the changing input current of the AC power input terminal 1 through the current transformer CT2 and outputs it to the control means 30.

Accordingly, the control means 30 displays an operation error indicating that the cooking vessel 66 mounted on the heating coil 65 is not a proper vessel through display means (not shown).

In the control means 30, the synchronous control indicated by the waveform of FIG. 4g (output waveform diagram at D point in FIG. 3) in synchronization with the zero potential of the commercial AC voltage detected by the zero voltage detecting means 20. FIG. By outputting a signal to the variable frequency oscillation means 40, the operation of the induction cooker is stopped to protect the circuit safely.

In addition, when the cooking vessel 66 mounted on the heating coil 65 is a non-metal cooking vessel and an aluminum cooking vessel, the impedance is lowered to increase the resonant current of the heating coil 65. The current is detected by the current transformer CT1 of 71 and output to the comparison means 90.

The comparison means 90 compares a voltage signal proportional to the resonance current detected by the resonance current detection unit 71 with a reference voltage signal set by the load setting means 80 to convert the voltage signal into a frequency oscillator 41. )

Therefore, the frequency oscillator 41 receives the voltage signal varied by the comparing means 90 and changes the oscillation frequency according to the state of the heating coil 65 which changes. (About, 60 to 70 KHz)

Accordingly, the inverter driving means 50 outputs a drive signal for driving the switching elements TR1 and TR2 to the inverter means 60 in accordance with the oscillation frequency varied by the frequency oscillation portion 41, thereby producing a metal container. The equipment can be safely protected by supplying stabilized output power even for non-metal cooking containers.

If the user turns off the operation switch 5 during the operation of the induction heating cooker as described above, the control means 30 displays the switch-off signal represented by the waveform of FIG. 4f (output waveform diagram at point C of FIG. 3). Is entered.

Accordingly, the control means 30 receives the zero voltage detection signal (waveform shown in FIG. 4b) output from the zero voltage detection means 20 at the time of inputting the switch-off signal (waveform shown in FIG. 4f). In synchronization with the zero potential, a synchronous control signal represented by a waveform of FIG. 4g (output waveform diagram at point D in FIG. 3) is output to the variable frequency oscillation means 40. FIG.

Accordingly, the variable frequency oscillation means 40 receives the synchronous control signal (waveform of FIG. 4g) output from the control means 30 to stop the oscillation.

When the frequency oscillation is stopped by the frequency oscillation means 40, the inverter driving means 50 no longer outputs a drive signal to the base terminals of the switching elements TR1 and TR2, and thus the switching elements TR1 and TR2. ) Is turned off.

Accordingly, the switching elements TR1 and TR2 are turned off in synchronization with the zero potential of the commercial AC voltage supplied from the AC power input terminal 1 to induce when the current flowing through the switching elements TR1 and TR2 is minimum. By stopping the heating cooker, the switching elements TR1 and TR2 are protected.

As described above, according to the induction heating cooker according to the present invention, the current detecting means detects the amount of current input to the heating coil to supply a constant resonant current to the heating coil to cook even when the input power voltage changes. It is possible to reduce the inrush current flowing through the switching element through the switching element during the initial operation of the induction heating cooker to prevent damage to the switching element and the heating coil and at the same time ensure the safety of the device. By detecting the resonant current flowing through the heating coil by the resonant current detection unit, when the nonmetallic cooking vessel is used, the oscillation frequency is varied to stabilize the output power so that the device can be safely driven.

Claims (6)

Rectifying means for full-wave rectifying the commercial AC voltage input from the AC power input terminal into DC voltage, zero voltage detecting means for detecting the zero potential of the commercial AC voltage input from the AC power input terminal, and the zero voltage detecting means Control means for controlling the overall operation of the induction heating cooker in synchronization with the zero potential of the commercial alternating current voltage, variable frequency oscillation means for receiving the control signal output from the control means and outputting an oscillation frequency from the variable frequency oscillation means. Inverter drive means for outputting a drive signal to drive a switching element according to the oscillation frequency output; inverter means for generating a high frequency signal by receiving a DC voltage input from the rectifying means according to a drive signal output from the inverter drive means; And a heating nose driven by the inverter means. The current detection means for detecting the amount of current variation input to the heating coil to supply a constant resonant current to the work, the input current fluctuation amount of the heating coil detected by the current detection means and the reference current amount set by the load setting means An induction heating cooker comprising: comparing means for outputting a comparison voltage signal to the variable frequency oscillating means so as to vary the oscillation frequency. The frequency oscillating unit of claim 1, wherein the variable frequency oscillating unit receives a control signal output from the control unit and generates an oscillation frequency, and the oscillation frequency generated from the frequency oscillating unit receives a control signal output from the control unit. Normal frequency holding unit for lowering the voltage input to the frequency oscillator to maintain the normal frequency state, and the lowest frequency to maintain the lowest frequency of the oscillation frequency to prevent the oscillation frequency generated from the frequency oscillator to fall below the audible frequency Induction heating cooker, characterized in that consisting of the holding portion. The switching device of claim 1, wherein the inverter means receives the driving signal output from the inverter driving means and alternately turns on / off the switch to generate a resonance current in the heating coil, and the switch. Resonance connected in parallel to the switching elements TR1 and TR2 to form a voltage source while charging and discharging the voltage charged in the smoothing capacitor CI during the turn-on / turn-off operation of the sub-elements TR1 and TR2. During the initial turn-on operation of the capacitors C2 and C3 and the switching elements TR1 and TR2, the inrush current flowing through the resonant capacitors C2 and C3 is reduced to reduce the switching elements TR1 and TR2 and the heating coil. The switching by bypassing the divided resistors R1 and R2 connected in parallel to the resonant capacitors C2 and C3 and the counter electromotive force generated during the turn-off operation of the switching elements TR1 and TR2 so as to protect the circuit. To protect the elements TR1 and TR2, the collector terminals of the switching elements TR1 and TR2 An induction heating cooker comprising protective diodes (D1, D2) connected to the meter terminals, respectively. 2. The cooking vessel according to claim 1, wherein the current detecting means comprises: a resonant current detecting unit detecting a resonant current of the heating coil so that a change in the heating coil supplies a constant air current to the heating coil driven by the inverter means; And an input current detector for detecting a changing input current of the AC power input terminal so as to determine whether the proper container is a proper container. The current transformer CTI of claim 4, wherein the resonance current detector detects a change in resonance current of the heating coil driven by the inverter means, and converts the amount of resonance current detected by the current transformer CT1 into a voltage. A resistor R3 connected in parallel to the secondary side of the current transformer CTI, a diode D3 for half-wave rectifying the voltage signal converted by the resistor R3, and a half-wave rectified by the diode D3. An induction heating cooker comprising: a resistor (R6) and a capacitor (C4) having one side connected to the cathode terminal of the diode (D3) and the other side grounded to filter the ripple component included in the DC voltage. The current transformer CT2 of claim 4, wherein the pressure current detection unit receives a commercial AC voltage output from the AC power input terminal and detects an input current fluctuation amount of the AC power input that changes when the heating coil is driven. Rectifier R4 connected in parallel to the secondary side of the current transformer CT2 to convert the current variation detected by CT2) into a voltage, and a bridge rectifier for full-wave rectifying the voltage signal converted by the resistor R4 into direct current. And a resistor (R5) and a capacitor (C5) connected in parallel to the output terminal of the bridge rectifier to filter the ripple component contained in the DC voltage rectified by the bridge rectifier. .