JP5340026B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker.

  Conventionally, there has been an induction heating cooker that can also heat an aluminum pan using a high frequency of 50 kHz or more as a drive frequency of an inverter circuit. This is because a high frequency current of 50 kHz or more is caused to flow through a heating coil connected to the inverter circuit to increase the frequency of an alternating magnetic field that generates an induced eddy current in the pan to 50 kHz or more, and a material such as aluminum having a low electrical resistance value is used. Even in the pan, the effective resistance value is increased by the skin effect to enable induction heating (see, for example, Patent Document 1).

JP 59-49187 (first page, FIG. 1)

However, there is a problem that the switching loss increases because the number of times of switching per unit time increases as the drive frequency of the switch element increases as in a conventional induction heating cooker.
In addition, switch elements may be connected in parallel to increase the capacity of the output current of the inverter circuit to increase the output. However, there is a bias in the output current flowing through the switch elements due to variations in switching speed between the switch elements. In particular, when driving at high frequency, the conduction time of the switch elements is shortened, and the effect of variations in switching speed between the switch elements is increased, so that the bias of the output current is increased and the effect of connecting the switch elements in parallel is lost. There was also a problem.

  The present invention has been made to solve the above-described problems, and reduces the loss of the switch element of the inverter circuit driven at a high frequency and suppresses the temperature rise of the switch element to prevent the inverter circuit from being thermally destroyed. Another object of the present invention is to obtain an induction heating cooker capable of avoiding the occurrence of heat destruction due to the current concentrated on a specific switch element connected in parallel to the inverter circuit.

An induction heating cooker according to the present invention converts a DC power supply circuit that rectifies an AC power supply into a DC voltage, a load circuit that includes a capacitor together with a heating coil, and converts DC power of the DC power supply circuit into high-frequency power. Yes an inverter circuit for outputting to the load circuit, in the induction heating cooker having an inverter driver circuit for controlling the inverter circuit in order to adjust the heating power, the inverter circuit includes a plurality of switching elements connected in parallel and, the inverter driver circuit, among the plurality of switching elements of the inverter circuit, the turn on prior one switching element, is intended to sequentially alternating the one switch element to be turned on by its predecessor.

  In the present invention, since the inverter drive circuit is turned on while sequentially switching one switch element among the plurality of switch elements of the inverter circuit, the switching frequency is lowered, so that the switching loss is reduced and the specific switch element is reduced. It is also possible to prevent the heat generation from concentrating only on the current flow.

The circuit block diagram of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. The wave form diagram of the drive signal of the inverter circuit of the induction heating cooking appliance. The flowchart of the to-be-heated container discrimination | determination process in the induction heating cooking appliance. The graph which shows the relationship between the output electric current with respect to the pan of various materials for the drive signal selection in the induction heating cooking appliance, and input electric power. The wave form diagram of the drive signal of the inverter circuit of the induction heating cooking appliance which concerns on Embodiment 2 of this invention. The circuit block diagram of the induction heating cooking appliance which concerns on Embodiment 3 of this invention. The wave form diagram of the high frequency drive signal of the inverter circuit of the induction heating cooking appliance. The wave form diagram of the low frequency drive signal of the inverter circuit of the induction heating cooking appliance. The wave form diagram of the high frequency drive signal of the inverter circuit of the induction heating cooking appliance which concerns on Embodiment 4 of this invention. The circuit block diagram of the induction heating cooking appliance which concerns on Embodiment 5 of this invention. The wave form diagram of the drive signal of the inverter circuit of the induction heating cooking appliance. The wave form diagram of the low frequency drive signal of the inverter circuit of the induction heating cooking appliance which concerns on Embodiment 6 of this invention.

Embodiment 1 FIG.
FIG. 1 is a circuit configuration diagram of an induction heating cooker according to Embodiment 1 of the present invention, and FIG. 2 is a waveform diagram of a drive signal of an inverter circuit of the induction heating cooker.
In FIG. 1, a DC power supply circuit 2 that converts commercial AC power of a commercial AC power supply 1 into DC power includes a rectifier diode bridge 3, a choke coil 4, and a smoothing capacitor 5.
The input current and input voltage of the DC power supply circuit are detected by the input current detector 6 and the input voltage detector 7, respectively.
The output side of the DC power supply circuit 2 is connected to the inverter circuit 8, and the DC power of the DC power supply circuit 2 is converted into high-frequency power by the inverter circuit 8 and supplied to the load circuit 9.

The inverter circuit 8 includes an upper switch element group 10 and a lower switch element group 11 connected in series between the output side buses of the DC power supply circuit 2.
The upper switch element group 10 includes three upper switch elements 10a to 10c connected in parallel, and three diodes 12a to 12c connected in reverse parallel to the upper switch elements 10a to 10c, respectively. The element group 11 includes three lower switch elements 11a to 11c connected in parallel, and three diodes 13a to 13c connected to the lower switch elements 11a to 11c in antiparallel.

If any one of the upper switch elements 10a to 10c is turned on, the high potential of the DC power supply circuit 2 is output from the output of the inverter circuit 8, and any one of the lower switch elements 11a to 11c is turned on. Then, the low potential of the DC power supply circuit 2 is output from the output of the inverter circuit 8.
The load circuit 9 connected to the output side of the inverter circuit 8 includes a heating coil 14 and a capacitor 15 connected in series to the heating coil 14. Reference numeral 16 denotes an output current detector that detects a current flowing through the load circuit 9. Reference numeral 17 denotes an inverter drive circuit that alternately turns on and off the upper switch elements 10a to 10c and the lower switch elements 11a to 11c of the inverter circuit 8, and 18 denotes a control circuit that controls the entire induction heating cooker.

2 shows a drive signal of the inverter circuit of the induction heating cooker according to the first embodiment. FIG. 2A shows a drive signal (high frequency drive signal) when the inverter circuit 8 is driven from the inverter drive circuit 17 at a high frequency. ), One of the lower switch elements 11a to 11c is turned on with a delay with respect to one of the upper switch elements 10a to 10c, and the remaining upper switch element and lower switch element are sequentially switched to each other. By similarly turning on, the inverter circuit 8 as a whole can output high-frequency power without excessively switching the switching frequency of each switch element.
FIG. 2B shows a waveform of a drive signal (low frequency drive signal) when the inverter circuit 8 is driven at a lower frequency compared to FIG. 2A, and the upper switch elements 10a to 10c connected in parallel. Are simultaneously turned on and off, the lower switch elements 11a to 11c are simultaneously turned on when the upper switch elements 10a to 10c are turned off, and the lower switch elements 11a to 11c are simultaneously turned off when the upper switch elements 10a to 10c are turned on.

When the inverter circuit 8 is driven at a high frequency, the conduction time of the switch elements is shortened, and even if the switch elements connected in parallel are driven at the same time, the effect of the difference in switching speed between the switch elements increases, The bias of the flowing current increases. Therefore, loss concentrates on a specific switch element, and the temperature of the switch element rises.
Therefore, in the first embodiment, as shown in FIG. 2A, when one of the upper switch elements 10a to 10c in the upper switch element group 10 is turned on, the lower switch elements 11a to 11a in the lower switch element group 11 are turned on. 11c is turned on with a delay, and the remaining upper switch element and lower switch element are sequentially switched and turned on in the same manner as described above, thereby reducing the switching frequency of each switch element and reducing the switching loss. By switching the switch elements through which the output current flows in a time-sharing manner, heat generation (loss) in the individual switch elements is dispersed, and the output current is always concentrated only on a specific switch element, and the element temperature is prevented from increasing.

  On the other hand, when the bias of the current flowing through each switch element due to the difference in switching speed between the switch elements connected in parallel at a relatively low frequency is small, as shown in FIG. By simultaneously driving the upper switch elements 10a to 10c and the lower switch elements 11a to 11c in the lower switch element group 11, the output current is shunted to the switch elements, and the loss in each switch element is suppressed and distributed. Can be made.

As described above, whether the inverter circuit 8 is driven at a high frequency or a low frequency is determined by performing a heated container discrimination process.
Usually, the output current varies depending on the type of pan, and the magnitude of the output current depends on the frequency of the drive signal, so it is necessary to know the type of pan to be cooked before cooking. Next, the heated container discrimination process is performed before cooking.
This heated container discrimination process will be described based on the flowchart of FIG. 3 and the graph showing the relationship between the output current and the input power for the pots of various materials for selecting the drive signal in the induction heating cooker of FIG.
First, as shown in FIG. 3, when a start button (not shown) of the heated container determination process is turned on, the inverter drive circuit 17 outputs a predetermined drive signal to the inverter circuit 8 to operate (step S1). .
Here, the predetermined drive signal when discriminating the heated container is set to a frequency higher than the resonance frequency of the heating coil and the resonant capacitor when a low impedance pan such as an aluminum pan is installed.

Next, an input voltage and an input / output current are detected using the input current detector 6, the input voltage detector 7, and the output current detector 16 (step S2), and these detected values are input to the control circuit 18. .
The control circuit 18 determines the heated container from the input current value and the output current value (step S3).
As can be seen from the graph of FIG. 4, when the input current is smaller than the predetermined value, there is no load or a small item such as a spoon or fork is erroneously placed, the input current is larger than the predetermined value, and the output When the current is large, the nonmagnetic material pan is placed. When the input current is larger than the predetermined value and the output current is relatively small, the magnetic pan is placed. I understand.

Therefore, if the input current is smaller than the predetermined value, the control circuit 18 determines that there is no load or a state where small objects such as spoons and forks are erroneously placed, and instructs the inverter drive circuit 17 to stop the drive signal. The inverter drive circuit 17 stops the drive signal to the inverter circuit 8 (step S4).
Further, when the input current is larger than the predetermined value and the output current is large, the control circuit 18 determines that the nonmagnetic pan is placed and issues a high frequency drive signal command to the inverter drive circuit 17. The inverter drive circuit 17 drives the inverter circuit 8 with the high-frequency drive signal shown in FIG. 2A (step S5), and increases the effective resistance value of the nonmagnetic pan and disperses the heat generated by the switching element.

Further, when the input current is larger than a predetermined value and the output current is relatively small, the control circuit 18 determines that the magnetic pan is placed and issues a low frequency drive signal command to the inverter drive circuit 17. The inverter drive circuit 17 drives the inverter circuit 8 with the low-frequency drive signal shown in FIG. 2B (step S5), and reduces the output current to match the magnetic pot.
As for the input current and output current thresholds shown in the graph of FIG. 4, the values of the input current and output current are the induction circuit type, drive signal, number of turns of the heating coil, capacity of the resonant capacitor, etc. Depending on the design and operating conditions, the value will vary greatly even for the same load (pan). These threshold values are set based on actually measured values when various pans are installed and operated with a predetermined drive signal.

In the first embodiment, switching of the switch element to be turned on in one switch element in the upper switch element group 10 and one switch element in the lower switch element group 11 is turned on once in the first embodiment. However, the number of switch elements to be turned on at a time may be driven not only one but two at a time.
When driving at a relatively low frequency, as shown in FIG. 2B, the three switch elements of the upper switch element group 10 and the three switch elements of the lower switch element group 11 are simultaneously turned on. However, only predetermined switch elements may be driven, or the switch elements connected in parallel may be sequentially switched as in the case of high-frequency driving.

Embodiment 2. FIG.
FIG. 5 is a waveform diagram of a drive signal of the inverter circuit of the induction heating cooker according to the second embodiment of the present invention. In addition, since the circuit structure of the induction heating cooking appliance in this Embodiment 2 is the same structure as FIG. 1 of Embodiment 1, it abbreviate | omits a figure.
In the first embodiment, in the upper switch elements 10a to 10c and the lower switch elements 11a to 11c connected in parallel constituting the inverter circuit 8, the lower switch elements 11a to 11c are turned on when one of the upper switch elements 10a to 10c is turned on. One of these is turned on with a delay, and the remaining upper switch element and lower switch element are sequentially switched and turned on in the same manner as described above, thereby switching the switch element through which the output current flows in a time-sharing manner and causing a loss ( In the second embodiment, there is a difference in the timing for driving the switch elements connected in parallel. Is provided so that the output current is not always concentrated on a specific switch element.

That is, in the second embodiment, in FIG. 5A showing the waveform of the drive signal in the high frequency drive state, at the timing T1, among the upper switch elements, the switch element 10a is replaced with the other upper switch element 10b, Since it is turned on prior to 10c and turned on immediately, more current flows than the other upper switch elements.
At the timing T2, the switch element 10b among the upper switch elements is turned on prior to the other upper switch elements 10a and 10c, and the switch element 10c among the upper switch elements is other at the timing T3. The upper switch elements 10a and 10b are turned on prior to the upper switch elements 10a and 10b, and more current flows through the upper switch elements 10b and 10c than the other upper switch elements, respectively.

The lower switch element is turned on when the upper switch element is turned off, but the same applies to the lower switch element. At the timing of T4, the lower switch element 11c, at the timing of T5, the lower switch element 11a, and at the timing of T6, the lower switch element is turned down. The switch element 11b is turned on prior to the other lower switch elements.
By driving in this way, it is possible to avoid that the output current always concentrates on a specific switch element.

  In FIG. 5B showing the waveform of the drive signal in a relatively low frequency drive state, the lower switch element is turned on when the upper switch element is turned off, but in the high frequency drive state shown in FIG. Similar to the waveform of the drive signal, one of the switch elements connected in parallel is turned on first, and then the other parallel switch element is turned on. While avoiding the concentration of loss due to a current that always flows larger than the element, current is shunted by energizing in parallel to suppress the loss.

  In the case of driving at a relatively low frequency, the parallel switch elements may be simultaneously turned on / off as in the first embodiment. In the first and second embodiments, three switch elements are connected in parallel. However, two or four or more switch elements may be connected in parallel.

Embodiment 3 FIG.
6 is a circuit configuration diagram of the induction heating cooker according to Embodiment 3 of the present invention, FIG. 7 is a waveform diagram of a drive signal in the high frequency driving state of the inverter circuit of the induction heating cooker, and FIG. 8 is the induction heating cooking. It is a wave form diagram of the drive signal in the comparatively low frequency drive state of the inverter circuit of a condenser. In addition, the inverter circuit of the induction heating cooking appliance of this Embodiment 3 is a full bridge structure.
In FIG. 6, the same or corresponding parts as those of the circuit configuration of the first embodiment shown in FIG.
As shown in FIG. 6, a full-bridge inverter circuit 8 is connected to the output of the DC power supply circuit 2.
The inverter circuit 8 having a full bridge configuration includes a first arm 8A including a first upper switch element group 10A and a first lower switch element group 11A connected in series between buses on the output side of the DC power supply circuit 2. And a second arm 8B composed of a second upper switch element group 10B and a second lower switch element group 11B.
A load circuit 9 including a heating coil 14 and a capacitor 15 connected in series to the heating coil 14 includes a connection point between the upper switch element group 10A and the lower switch element group 11A that are output points of the first arm 8A. The upper switch element group 10B and the lower switch element group 11B, which are output points of the second arm 8B, are connected.

The first upper switch element group 10A includes switch elements 10d and 10e connected in parallel and diodes 12d and 12e connected in antiparallel to them, and the first lower switch element group 11A is connected in parallel. Switch elements 11d and 11e, and diodes 13d and 13e connected in antiparallel to them.
The second upper switch element group 10B includes switch elements 10f and 10g connected in parallel and diodes 12f and 12g connected in antiparallel to them, and the second lower switch element group 11B is connected in parallel. And switch elements 11f and 11g connected to each other and diodes 13f and 13g connected in antiparallel to them.
The first inverter drive circuit 17A alternately turns on and off the first upper switch element group 10A and the first lower switch element group 11A, and the second inverter drive circuit 17B The group 10B and the second lower switch element group 11B are alternately turned on / off. The waveforms of the drive signals of the first and second drive circuits 17A and 17B are shown in FIGS.

FIG. 7 shows the waveform of the drive signal in the high frequency drive state, and the heating output is adjusted by controlling the phase difference between the high frequency output of the first arm 8A and the high frequency output of the second arm 8B.
The high-frequency output of the first arm 8A is performed by alternately turning on the upper switch element group 10A and the lower switch element group 11A at a high frequency. The upper switch element group 10A is turned on by the switch elements 10d and 10e connected in parallel. Any one switch element is turned on alternately, and the lower switch element group 11A is turned on by alternately turning on any one of the switch elements 11d and 11e connected in parallel.
Therefore, the switching frequency of the switch elements 10d, 10e, 11d, and 11e constituting the first arm 8A can be made half the output frequency of the first arm 8A. The high-frequency output of the second arm 8B is the same as that of the first arm 8A, and the switching frequency of the switch elements 10f, 10g, 11f, and 11g constituting the second arm 8B is half of the high-frequency output frequency of the second arm 8B. .
The output potential of the first arm 8A and the second arm 8B is such that the potential on the high potential side of the DC bus is output when the upper switch is on and the potential on the low potential side of the DC bus is output when the lower switch is on. The voltage applied to the circuit 9 is the difference between the output potential of the first arm 8A and the output potential of the second arm 8B, that is, the DC bus voltage is applied in both positive and negative directions.

FIG. 8 shows a waveform of a relatively low frequency drive signal. The drive signal of the upper switch elements 10d and 10e of the first arm 8A, the drive signal of the lower switch elements 11d and 11e of the first arm 8A, and the second arm The drive signals for the upper switch elements 10f and 10g of 8B and the drive signals for the lower switch elements 11f and 11g of the second arm 8B are shown.
In the case of a relatively low frequency, the same drive signal is output to the switch elements connected in parallel and turned on in parallel, thereby diverting the output current and reducing the level of current flowing through one switch element, resulting in loss. Suppress.

  As described above, in the third embodiment, the full-bridge inverter circuit 8 connected to the output side of the DC power supply circuit 2 is connected in series between the buses on the output side of the DC power supply circuit 2. The upper switch element group 10A, the first arm 8A composed of the first lower switch element group 11A, and the second arm 8B composed of the second upper switch element group 10B and the second lower switch element group 11B. The load circuit 9 includes a connection point between the upper switch element group 10A and the lower switch element group 11A, which are output points of the first arm 8A, and an upper switch element group 10B and a lower switch element, which are output points of the second arm 8B. The first inverter drive circuit 17A is alternately connected to the connection point of the group 11B, and alternately turns on and off the first upper switch element group 10A and the lower switch element group 11A. Inverter drive circuit 17B is designed so as to drive on and off the second upper switching element group 10B and the lower switching element group 11B alternately.

In this case, the first upper switch element group 10A in the first arm 8A is turned on by alternately turning on one of the switch elements 10d and 10e connected in parallel. The element group 11A is also turned on by alternately turning on any one of the switch elements 11d and 11e connected in parallel, and the second arm 8B is also the same. The drive frequency of the switch element can be halved of the output frequency of the inverter circuit, the switching frequency of each switch element can be lowered to suppress the switching loss, and the characteristics of the switch elements vary. Thus, it is possible to avoid the concentration of the loss only on the specific switch element.
In the third embodiment, two switch elements are connected in parallel, but three or more switch elements may be arranged in parallel. In this case, the drive frequency of each switch element is the output frequency of the inverter circuit. 1/3 or less.

Embodiment 4 FIG.
FIG. 9 is a waveform diagram of a high frequency drive signal of the inverter circuit of the induction heating cooker according to the fourth embodiment of the present invention. In addition, since the circuit structure of the induction heating cooking appliance in this Embodiment 4 is the same as that of FIG. 6 of Embodiment 3, a figure is abbreviate | omitted.
In the fourth embodiment, when the inverter circuit having the full bridge configuration shown in FIG. 6 is used, a difference is provided in the timing for driving the switch elements connected in parallel, and the output current is always concentrated on a specific switch element. It is intended to avoid doing.

That is, in the fourth embodiment, the high frequency output of the first arm 8A is performed by alternately turning on the upper switch element group 10A and the lower switch element group 11A at a high frequency, and the high frequency output of the second arm 8B is also This is done by alternately turning on the switch element group 10B and the lower switch element group 11B at a high frequency. Both the first arm 8A and the second arm 8B, as shown in FIG. 9, are connected in parallel to the switch elements 10d and 10e. , 11d and 11e, 10f and 10g, and 11f and 11g, the turn-on timing is shifted.
As in the fourth embodiment, both the first arm 8A and the second arm 8B turn on the switching elements 10d and 10e, 11d and 11e, 10f and 10g, and 11f and 11g that are connected in parallel alternately. As a result, it is avoided that the output current is always concentrated only on a specific switch element due to the variation in characteristics of the switch element, and the loss (heat generation) in the switch element is increased.
Further, the current flowing in the switch element that is turned on in advance is shunted and reduced by energizing in parallel, and the loss in the switch element is suppressed.

Embodiment 5 FIG.
FIG. 10 is a circuit configuration diagram of an induction heating cooker according to Embodiment 5 of the present invention, and FIG. 11 is a waveform diagram of a drive signal of an inverter circuit of the induction heating cooker.
In FIG. 10, the same or corresponding parts as those of the circuit configuration of the first embodiment shown in FIG.
As shown in FIG. 10, a voltage resonance type inverter circuit 8 and a load circuit 9 are connected in series on the output side of the DC power supply circuit 2.
The load circuit 9 includes a heating coil 14 and a capacitor 15 connected in parallel to the heating coil 14.
The inverter circuit 8 includes switch elements 19a and 19b connected in parallel and diodes 20a and 20b connected in reverse parallel to the switch elements 19a and 19b, respectively.

When the inverter circuit 8 is driven at a high frequency, even if the switch elements 19a and 19b connected in parallel are driven at the same time, the bias of the current flowing through each switch element increases due to the difference in switching speed between the switch elements. Loss concentrates on the element, and the temperature of the switch element rises.
Therefore, in the fifth embodiment, as shown in FIG. 11 (a), the switching elements 19a and 19b connected in parallel are turned on while being alternately switched, thereby reducing the switching frequency of each switching element. In addition to reducing switching loss and switching the switch elements through which the output current flows in a time-sharing manner, the heat generation (loss) in each switch element is dispersed, and the output current is always concentrated only on a specific switch element, so that the element temperature Avoid getting high.
FIG. 11B is an example of a drive signal when the inverter circuit 8 is driven at a lower frequency than that in FIG. 11A. The switch elements 19a and 19b connected in parallel are simultaneously turned on / off. However, the bias of the current flowing through each switch element due to the difference in switching speed between the switch elements is relatively small. By simultaneously driving each switch element, the output current is shunted to each switch element, and the loss ( Heat generation) can be reduced.

  When the inverter circuit 8 is driven at a high frequency, as shown in FIG. 11A, the switching elements 19a and 19b connected in parallel are alternately turned on at intervals, thereby switching the individual switching elements. High frequency power can be output as the entire inverter circuit 8 without excessively high frequency.

Embodiment 6 FIG.
FIG. 12 is a waveform diagram of the low frequency drive signal of the inverter circuit of the induction heating cooker according to the sixth embodiment of the present invention. In addition, since the circuit structure of the induction heating cooking appliance in this Embodiment 6 is the same as that of FIG. 10 of Embodiment 5, a figure is abbreviate | omitted.
Even when the voltage resonance type inverter circuit shown in FIG. 10 is used, a difference is provided in the timing of driving the switch elements connected in parallel so that the output current is not always concentrated on a specific switch element. It is a thing.

That is, in the sixth embodiment, as shown in FIG. 12, the turn-on timing of the switch elements 19a and 19b connected in parallel is shifted. The switch element 19a is turned on in advance at the timing of T11, and the switch element 19b is turned on in advance of the switch element 19a at the timing of T12, so that the switch elements 19a and 19b connected in parallel are alternately turned on. By turning on before the switching element, it is possible to avoid that the output current is always concentrated only on a specific switch element due to variations in the characteristics of the switch element, and the loss (heat generation) in the switch element is increased.
In addition, it is possible to divert and reduce the output current flowing in the switch element that is turned on in advance by energizing in parallel, and to suppress loss in the switch element.

  DESCRIPTION OF SYMBOLS 1 Commercial AC power supply, 2 DC power supply circuit, 6 Input current detector, 7 Input voltage detector, 8 Inverter circuit, 9 Load circuit, 10 Upper switch element group, 10a-10c Upper switch element, 11 Lower switch element group, 11a ˜11c Lower switch element, 14 heating coil, 15 resonant capacitor, 16 output current detector, 17 inverter drive circuit, 18 control circuit.

Claims (5)

A DC power supply circuit that rectifies and converts the AC power supply to DC, a load circuit including a capacitor together with a heating coil, an inverter circuit that converts DC power of the DC power supply circuit into high-frequency power and outputs the high-frequency power to the load circuit; In an induction heating cooker provided with an inverter drive circuit for controlling the inverter circuit to adjust the heating output,
The inverter circuit includes a plurality of switches element connected in parallel,
The inverter driver circuit,
An induction heating cooker characterized in that, among the plurality of switch elements of the inverter circuit, one switch element is turned on in advance and the one switch element that is turned on in advance is sequentially replaced. When the inverter drive circuit drives the inverter circuit at a frequency lower than a predetermined frequency, a plurality of switching elements connected in parallel at the same time, or wherein the turning on at least one switching element according to claim 1 The induction heating cooker described. A DC power supply circuit that rectifies and converts the AC power supply to DC, a load circuit including a capacitor together with a heating coil, an inverter circuit that converts DC power of the DC power supply circuit into high-frequency power and outputs the high-frequency power to the load circuit; In an induction heating cooker provided with an inverter drive circuit for controlling the inverter circuit to adjust the heating output,
The load circuit is composed of a series circuit of a heating coil and a capacitor,
The inverter circuit,
The load circuit is connected in series between the buses on the output side of the DC power supply circuit, and includes an upper switch element group in which a plurality of switch elements are connected in parallel and a lower switch element group in which a plurality of switch elements are connected in parallel And
The inverter driver circuit,
One switch element of the upper switch element group is turned on in advance of the other switch elements, and then sequentially switched one switch element that is turned on in advance,
An induction heating cooker , wherein the lower switch element group is turned on in the same manner as the upper switch element group when the upper switch element group is turned off . The inverter circuit is
Having two arms connected in parallel between the output buses of the DC power supply circuit;
Each said arm
It is composed of an upper switch element group in which a plurality of switch elements are connected in parallel and a lower switch element group in which a plurality of switch elements are connected in parallel.
The inverter drive circuit is
Turn on one switch element of the upper switch element group of each arm in advance of the other switch elements, and then sequentially switch one switch element to be turned on in advance,
The lower switch element group of each arm is turned on in the same manner as the upper switch element group when the upper switch element group is turned off.
The induction heating cooker according to claim 3. The inverter driver circuit,
When the inverter circuit is driven at a frequency lower than a predetermined frequency, a plurality of switch element groups connected in parallel are simultaneously turned on, or at least one switch element of each switch element group is simultaneously turned on. The induction heating cooking appliance of Claim 3 or Claim 4 .

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