JP2013191519A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an induction heating cooker which can make an interference sound generated when a plurality of heating coils are driven be hard to be perceived by a user.SOLUTION: In the induction heating cooker, when a difference frequency between drive frequencies of two or more inverters which are driven is included in a frequency region preset as a low-frequency region among audible frequencies, at least one inverter which is in a halt condition is driven so as to continuously change a drive frequency of the inverter from a lower limit to an upper limit of a predetermined frequency region included in the low-frequency region.

Description

  The present invention relates to an induction heating cooker having a plurality of heating coils.

In an induction heating cooker, when driving a plurality of heating coils at different driving frequencies, if the frequency of the difference between the driving frequencies is 15 kHz or less, which is a human audible frequency range, the user hears it as an interference sound. For example, as shown in FIG. 7, when two heating coils are driven at 22.3 kHz and 27.3 kHz, the difference frequency makes the user feel an unpleasant high frequency sound.
In order to suppress the occurrence of such interference noise, in a conventional induction heating cooker, for example, “In an electromagnetic cooker having a plurality of electromagnetic cooking units that perform heating by a current induced in a heated object by magnetic induction. A cooling fan having a frequency band provided in the vicinity of the plurality of electromagnetic cooking units and including a frequency band of interference sound generated by a difference in frequency of a high-frequency current applied to the plurality of electromagnetic cooking units; and the interference sound And a setting unit for setting the loudness of the cooling fan to be larger than the loudness of the interference sound so as to prevent the sound from being heard (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 3-088293 (Claim 1)

  In the technique of Patent Document 1, it is necessary to control the sound pressure of the cooling fan to be larger than the interference sound. Therefore, when the rotation speed of the cooling fan is limited, the cooling of the equipment is hindered, or the cooling is performed more than necessary. There is a problem that wasteful power may be consumed.

  In addition, in induction heating, the difference in the driving frequency of multiple heating coils is not included in the cooling fan noise frequency range due to the type of material to be heated and the difference in the configuration of the inverter circuit. However, there is a problem that it is sometimes impossible to make the interference sound generated by the difference in the driving frequency inaudible due to the noise of the cooling fan.

  The present invention has been made to solve the above-described problems, and obtains an induction heating cooker that makes it difficult for a user to recognize interference sounds generated when driving a plurality of heating coils. It is.

  The induction heating cooker according to the present invention includes a plurality of heating coils that induction-heats an object to be heated, a plurality of inverter circuits that output high-frequency power to the heating coil, and a drive frequency of the inverter circuit, Control means for controlling the output power of each of the plurality of inverter circuits, wherein the control means has two or more of the inverter circuits in a driving state and one or more of the inverter circuits in a stopped state. In this case, when the difference frequency between the drive frequencies of the two or more inverter circuits in the drive state is included in a frequency range preset as a low frequency region in the audible frequency region, the inverter circuit in the stop state At least one of the inverter circuit and the drive frequency of the inverter circuit is increased from a lower limit of a predetermined frequency range included in the low frequency region. Until those for continuously changing.

  In the present invention, when the difference frequency between the drive frequencies of two or more inverter circuits in the drive state is included in the low frequency region, the inverter circuit in the stop state is driven, and the lower limit of the predetermined frequency range included in the low frequency region Thus, the interference sound generated when driving the plurality of heating coils can be made difficult to be recognized by the user by the driving sound of the heating coil driven by the inverter circuit.

It is a block diagram which shows the structure of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is a perspective view which shows the induction heating cooking appliance main body which concerns on Embodiment 1 of this invention. It is a flowchart which shows the operation | movement of the heating output control process which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the induction heating cooking appliance which concerns on Embodiment 2 of this invention. It is a perspective view which shows the induction heating cooking appliance main body which concerns on Embodiment 2 of this invention. It is a flowchart which shows the operation | movement of the heating output control process which concerns on Embodiment 2 of this invention. It is a figure which shows the example of the frequency analysis of the sound pressure of the conventional induction heating cooking appliance.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing the configuration of the induction heating cooker according to Embodiment 1 of the present invention.
FIG. 2 is a perspective view showing the induction heating cooker body according to Embodiment 1 of the present invention.
In FIG. 1, the induction heating cooker includes heating coils 8, 9, and 10 (hereinafter simply referred to as “heating coils” when not distinguished from each other) that induction-heats an object to be heated.
The heating coils 8, 9, and 10 are connected in series with the resonant capacitors 14, 15, and 16, respectively.
As shown in FIG. 2, the heating coil 8 is disposed below the heating port 20 on the left front side of the housing 23, and the heating coil 9 is disposed below the heating port 21 on the center back side of the housing 23, The heating coil 10 is disposed below the heating port 22 on the right front side of the housing 23.

The inverter L5, the inverter C6, and the inverter R7 (hereinafter simply referred to as “inverter” when not distinguished from each other) convert input DC power into high-frequency power and output it when the switching element is on / off controlled. .
The inverter L5 is connected to the heating coil 8 and the resonant capacitor 14 as a load circuit. The switching element is ON / OFF controlled by a control signal from the control unit L2, and the drive frequency fswL is controlled.
The inverter C6 is connected to the heating coil 9 and the resonant capacitor 15 as a load circuit. The switching element is on / off controlled by a control signal from the control unit C3, and the drive frequency fswC is controlled.
The inverter R7 is connected to the heating coil 10 and the resonance capacitor 16 as a load circuit. The switching element is ON / OFF controlled by a control signal from the control unit R4, and the drive frequency fswR is controlled.

  In the present embodiment, as an example, a case where one heating coil is provided in each of three heating ports and an inverter is provided for each heating coil will be described. However, the present invention is not limited to this. Any configuration that includes at least three heating coils and can individually vary the drive frequency by three or more inverters may be used.

The control unit 1 receives a heating port selection operation and setting information of a heating power command value from an operation unit (not shown), detects the heating port selected by the user's operation, and outputs a heating power command corresponding to the detected heating port. To the control unit L2, the control unit C3, and the control unit R4.
The control unit L2, the control unit C3, and the control unit R4 control the output power of the inverter by varying the drive frequency of the corresponding inverter based on a command from the control unit 1.
In addition, the control unit 1 detects the current flowing through each heating coil by the current sensors 11, 12, and 13, and detects the voltage applied to each load circuit by the voltage sensors 17, 18, and 19. The control unit 1 detects the driving frequency of each heating coil from electric signals acquired from the current sensors 11, 12, 13 and voltage sensors 17, 18, 19 (hereinafter referred to as “each sensor”).

The control unit 1, the control unit L2, the control unit C3, and the control unit R4 constitute “control means” in the present invention.
In the present embodiment, a configuration will be described in which the control units L2, C3, and R4 that control the inverter and the control unit 1 that transmits a control command to these control units are provided. The present invention is not limited to this, and a plurality of inverters may be controlled by a single control unit.

Next, the operation of the first embodiment will be described using the flowchart of FIG.
FIG. 3 is a flowchart showing the operation of the heating output control process according to Embodiment 1 of the present invention. Hereinafter, a description will be given based on each step of FIG.

(Step 1)
The control unit 1 determines whether or not a heating start instruction is input from the operation unit, and when there is an input, proceeds to step 2.
At this time, the control unit 1 transmits the set thermal power command value to the control unit corresponding to the heating port selected by the user among the control unit L2, the control unit C3, and the control unit R4. The control unit L2, the control unit C3, and the control unit R4 start driving the corresponding inverter based on a command from the control unit 1, and vary the drive frequency so that the set thermal power (electric power) is obtained.
The control unit 1 performs the above operation every time a new heating start instruction is input, and drives the heating coils corresponding to the plurality of heating ports selected by the user.
In addition, the control part 1 calculates | requires the output electric power to a heating coil with the current sensors 11, 12, and 13 and the voltage sensors 17, 18, and 19, and it is an inverter so that it may become the thermal power (electric power) which the user set. Power feedback control may be performed to adjust the driving frequency.

(Step 2)
The control part 1 acquires the signal from each sensor, and detects the drive frequency of the heating coil in drive.
The detection of the drive frequency is not limited to this. For example, a control signal to the inverter may be acquired from the control unit L2, the control unit C3, and the control unit R4, and the drive frequency may be detected based on the control signal.

(Step 3)
The control unit 1 determines whether or not two heating ports are used. That is, it is determined whether or not two of the heating ports 20, 21, and 22 are in use (driving state) and one is not in use (stopped state).
In the case of the configuration in which one inverter is provided for each of the three heating ports as in the present embodiment, it may be determined whether or not the two heating ports are used. When providing four or more inverters, such as when providing a plurality of inverters for a single heating port, two or more inverters are in a drive state, and one or more inverters are provided. It is determined whether or not the vehicle is stopped.
If the above condition is satisfied, there is a possibility that an interference sound may be generated, and the process proceeds to Step 4. If not satisfied, the process proceeds to Step 8 because there is no possibility that an interference sound is generated, and the normal heating operation is continued.

(Step 4)
The control unit 1 calculates a difference frequency between the drive frequencies of the two inverters that are in the drive state. Then, it is determined whether or not the difference frequency is included in the audible frequency region (15 kHz or less).
If the difference frequency is 15 kHz or less, the process proceeds to step 5. On the other hand, if the difference frequency exceeds 15 kHz, the user cannot hear it as an interference sound, so the process proceeds to step 8 and the normal heating operation is continued.

(Step 5)
The control unit 1 determines whether or not the difference frequency is included in the low frequency region (5 kHz or less).
In this low frequency region, a frequency range of 5 kHz or less, which is a frequency of a sound that is difficult for humans to feel uncomfortable, is preset in the audible frequency region (15 kHz or less).
Here, the high frequency sound (keen sound) whose frequency is in the range of 5 to 15 kHz makes the user uncomfortable and irritating. On the other hand, the low frequency sound of 5 kHz or less is somewhat audible because it is in the user's audible range, but it is a frequency band that is about the normal speaking voice, so it has a less harsh audibility than the high frequency sound. It is known that when the frequency exceeds 15 kHz, the frequency is higher than the user's audible range, so that the user hardly hears it.
It should be noted that the above audibility classification is rough and does not limit the numerical values.

(Step 6)
When the difference frequency is not included in the low frequency region (difference frequency> 5 kHz), that is, when the difference frequency is included in the audible frequency region and not included in the range of the low frequency region (above 5 kHz and not more than 15 kHz). The two inverters in the drive state are driven and controlled so that the difference frequency is included in the range of the low frequency region.
For example, the drive frequency of either one or both of the two inverters in the drive state is changed to control the difference frequency to be 5 kHz or less. At this time, in order to suppress the variation of the thermal power (electric power) due to the change of the drive frequency, the duty control may be performed together so as to obtain a desired thermal power. For example, when the output power is lowered by increasing the drive frequency of the inverter, control is performed to increase the output power by increasing the duty ratio and maintain the thermal power set by the thermal power command.

(Step 7)
When the difference frequency is included in the low frequency region (difference frequency ≦ 5 kHz), the inverter that is in the stopped state is driven, and the drive frequency of the inverter is continuously changed from the lower limit to the upper limit of the predetermined frequency range (sweep drive).
This predetermined frequency range is a frequency range included in the low frequency region (5 kHz or less). For example, 1 kHz to 5 kHz is set as the predetermined frequency range, and the drive frequency is continuously changed from 1 kHz to 5 kHz.
When four or more inverters are provided, such as when four or more heating ports are provided, or when a plurality of inverters are provided for one heating port, at least one of the inverters in a stopped state is driven. Then, this inverter is driven to sweep.

In the example of FIG. 1, for example, when the heating port 20 and the heating port 22 are selected and a heating start instruction is input, a thermal power command is transmitted from the control unit 1 to the control units L2 and R4, and from the control units L2 and R4 A drive signal is sent to inverter L5 and inverter R7. As a result, the heating coil 8 is driven at the drive frequency fswL, and the heating coil 10 is driven at the drive frequency fswR. In this case, the difference frequency is | fswL−fswR |.
If the difference frequency is 5 kHz or less, the control unit 1 sends an interference noise suppression operation command (sweeping drive command) to the control unit C3, and the control unit C3 continuously drives the inverter C6 at 1 kHz to 5 kHz. As a result, the heating coil 9 is swept at a drive frequency of 1 to 5 kHz.

As described above, the heating coil that sweeps at a frequency in the low frequency region generates vibration sound (driving sound) due to a continuous change in the driving frequency, and the frequency region of the vibration sound is the same low frequency region as the interference sound. It becomes.
Here, as shown in FIG. 7, it is known that the background noise rises exponentially as the sound pressure level generated in the induction heating cooker becomes lower. For this reason, the level of the background noise can be further increased by driving the coil that is stopped in the low frequency region, and it is difficult for the user to recognize the interference sound in the low frequency region. (Masking effect can be obtained).

In the above-described sweep drive, the period of continuous change from the lower limit to the upper limit of the predetermined frequency range is set to be shorter than the period of the drive frequency of two or more inverters in the drive state.
For example, when the drive frequency of the inverter in the drive state is 20 kHz, the cycle is 50 milliseconds. In this case, the time (cycle) for changing the drive frequency from 1 kHz to 5 kHz is shorter than 50 milliseconds.
It is preferable to operate the sweep drive as fast as possible within the range allowed by the microcomputer as the control unit. Desirably, 1 microsecond or less is preferable. This is because the drive sound by the sweep drive is within a range that can be recognized by a person as a continuous sound.

  In the sweep drive, the output power of the inverter circuit is set to a power of about several watts (less than 10 watts). The purpose of the sweep drive is to generate a drive sound, and an effect sufficient to mask the interference sound can be obtained even with a few watts. For example, it is about 1 watt. As a result, it is possible to reduce power loss due to the sweep drive.

(Step 8)
The control unit 1 determines whether or not a heating stop instruction is input from the operation unit. If there is no input, the control unit 1 returns to step 3 and repeats the above operation. On the other hand, if there is an input of a heating stop instruction, the process proceeds to step 9.

(Step 9)
When there is an input of a heating stop instruction, the control unit 1 transmits a stop command for stopping the drive of the inverter to the control units L2, C3, R4, and the control units L2, C3, R4 drive the inverter The output of the signal is stopped, and the energization to the heating coil is stopped. And it returns to step 1 and repeats the said operation | movement.

As described above, in the present embodiment, when two or more inverters are in a driving state and one or more inverters are in a stopped state, the difference frequency of the driving frequency of the inverter in the driving state is When it is included in the low frequency region (5 kHz or less) of the audible frequency region, at least one of the inverters in a stopped state is driven, and the drive frequency of this inverter is increased from the lower limit to the predetermined frequency range included in the low frequency region. Continuously (from 1 kHz to 5 kHz) (sweep drive).
For this reason, it is possible to make it difficult for the user to recognize the interference sound generated when driving the plurality of heating coils by the driving sound of the heating coils driven by the inverter that has been stopped.

Further, in the present embodiment, the cycle of the sweep drive that is continuously changed from the lower limit to the upper limit of the predetermined frequency range included in the low frequency region is shorter than the cycle of the drive frequency of the two or more inverter circuits that are in the drive state. It's time.
For this reason, the vibration sound of the heating coil by the sweep drive can be made difficult to be recognized by the user as noise.

Further, in the present embodiment, when the difference frequency between the drive frequencies of the two or more inverters in the drive state is included in the audible frequency range and not included in the low frequency range, the difference frequency is low. Two or more inverters in a driving state are driven and controlled so as to be included in the range of the frequency region.
For this reason, when the interference sound is generated at the frequency of the sound that the person feels uncomfortable, the masking effect by the sweep drive can be obtained by setting the difference frequency to the low frequency region.

In the present embodiment, when driving the inverter circuit in a stopped state, the output power of the inverter is set to a power of less than 10 watts (for example, 1 watt).
Thereby, an increase in power loss due to the sweep drive can be suppressed while obtaining a masking effect by the sweep drive.

Embodiment 2. FIG.
In the second embodiment, a case where a plurality of heating coils corresponding to one heating port is configured will be described.
In addition, the same code | symbol is attached | subjected to the part similar to Embodiment 1, and description is abbreviate | omitted.

FIG. 4 is a block diagram showing the configuration of the induction heating cooker according to Embodiment 2 of the present invention.
FIG. 5 is a perspective view showing an induction heating cooker body according to Embodiment 2 of the present invention.
As shown in FIG. 5, in the second embodiment, a circular heating coil 8 and four oval heating coils 32 arranged around it are arranged below the heating port 36 on the left front side of the housing 23. Has been.
As shown in FIG. 4, the inverter La30 is connected with a heating coil 32 and four resonant capacitors 35, in which four oval coils are connected in series, as a load circuit. The switching element is controlled by a control signal from the control unit L2. Is turned on / off, and the drive frequency fswLa is controlled.
The inverter Lb31 is connected to the heating coil 8 and the resonant capacitor 14 as a load circuit. The switching element is on / off controlled by a control signal from the control unit L2, and the drive frequency fswLb is controlled.
Thus, the heating coil 8 and the heating coil 32 arranged below the heating port 36 are driven by separate inverters, and the driving frequency can be arbitrarily set.

  In the present embodiment, as an example, a case where one of the three heating ports is provided with a plurality of heating coils and two inverters are provided for the heating port will be described. However, the present invention is not limited to this. Absent. As long as it has at least three heating coils as a whole, the driving frequency can be varied individually by three or more inverters.

The control unit 1 receives a heating port selection operation, a heating coil selection operation, and setting information of a heating power command value from an operation unit (not shown), detects the heating port and the heating coil selected by the user's operation, and detects them. The heating power command corresponding to the heating port and the heating coil is transmitted to the control unit L2, the control unit C3, and the control unit R4.
The control unit L2, the control unit C3, and the control unit R4 control the output power of the inverter by varying the drive frequency of the corresponding inverter based on a command from the control unit 1.
Further, the control unit 1 detects the current flowing through each heating coil by the current sensors 11, 12, 13, and 33, and detects the voltage applied to each load circuit by the voltage sensors 17, 18, 19, and 34. To do. The control unit 1 detects the driving frequency of each heating coil from electrical signals acquired from the current sensors 11, 12, 13, 33 and the voltage sensors 17, 18, 19, 34 (hereinafter referred to as “each sensor”).

In the present embodiment, the heating coil 8 and the heating coil 32 are arranged very close to each other. In such a configuration, the interference sound due to the leakage magnetic field is likely to be generated. In the conventional induction heating cooker, in order to suppress the generation of the interference sound between the heating coils arranged in the vicinity as described above, the drive frequencies are set to be the same or the difference frequency is equal to or higher than the audible frequency (for example, 15 kHz or higher). It was necessary to set the drive frequency so that
Also in the cooking device according to the present embodiment, the difference frequency of the driven inverter is set to a low frequency region, and the stopped inverter is swept to mask the interference sound.

Next, the operation of the second embodiment will be described with reference to the flowchart of FIG.
FIG. 6 is a flowchart showing the operation of the heating output control process according to Embodiment 2 of the present invention. Hereinafter, based on each step of FIG. 6, it demonstrates centering on difference with the said Embodiment 1. FIG.

(Steps 10 and 11)
The control unit 1 determines whether or not a heating start instruction is input from the operation unit. If there is an input, the control unit 1 proceeds to step 12 to acquire a signal from each sensor and detect the driving frequency of the heating coil being driven. To do.
(Step 12)
The control unit 1 determines whether or not two or more heating coils are energized and one or more heating coils are stopped. That is, it is determined whether or not two or more inverters among the four inverters La30, Lb31, C6, and R7 are in a driving state and one or more inverters are in a stopped state.
If the above condition is satisfied, there is a possibility that an interference sound may be generated, so the process proceeds to Step 13. If not, the process proceeds to Step 17 because there is no possibility that an interference sound is generated, and the normal heating operation is continued.

When it is determined that two or more coils are energized, it is determined that there is a possibility that interference sound is generated, and the difference frequency is determined (steps 13 and 14). The difference frequency is determined to be higher than 15 kHz. If it is determined that the interference sound is not heard outside the human audible range, the normal heating operation is continued.
If the difference frequency is 15 kHz or less and 5 kHz or more, the drive frequency of each coil is controlled and set to be above 15 kHz or below 5 kHz (step 15).

(Steps 13 and 14)
The control unit 1 calculates the difference frequency of the drive frequency of the inverter in the drive state, and determines whether or not the difference frequency is included in the audible frequency region (15 kHz or less).
If the difference frequency exceeds 15 kHz, the process cannot proceed to step 16 because the user cannot hear it as an interference sound. On the other hand, if the difference frequency is 15 kHz or less, the process proceeds to step 14 to determine whether or not the difference frequency is included in the low frequency region (5 kHz or less).

(Step 15)
When the difference frequency is not included in the low frequency region (difference frequency> 5 kHz), that is, when the difference frequency is included in the audible frequency region and not included in the range of the low frequency region (above 5 kHz and not more than 15 kHz). Similarly to the first embodiment, the two inverters in the drive state are driven and controlled so that the difference frequency is included in the range of the low frequency region.

(Step 16)
When the difference frequency is included in the low frequency region (difference frequency ≦ 5 kHz), the inverter that is in the stopped state is driven, and the drive frequency of the inverter is continuously changed from the lower limit to the upper limit of the predetermined frequency range (sweep drive).

In the example of FIG. 4, for example, when the heating coil 8 and the heating coil 32 of the heating port 36 are selected and a heating start instruction is input from the operation unit, the heating coil selected from the control unit 1 to the control unit L2 A thermal power command is transmitted, and a drive signal is transmitted from the control unit L2 to the inverter La30 and the inverter Lb31. As a result, the four oval coils of the heating coil 32 are driven at the drive frequency fswLa, and the heating coil 8 is driven at the drive frequency fswLb. In this case, the difference frequency is | fswLa−fswLb |.
If this difference frequency is 5 kHz or less, the control unit 1 sends a command (sweeping drive command) for interference sound suppression operation to the control unit C3 or the control unit R4, and the control unit C3 or R7 Is continuously varied from 1 kHz to 5 kHz. As a result, the heating coil 9 or 10 is swept at a drive frequency of 1 to 5 kHz.

Thus, also in the present embodiment, as in the first embodiment, the heating coil that performs the sweep drive at a frequency in the low frequency region generates vibration sound (drive sound) due to continuous change of the drive frequency, The frequency region of the vibration sound is the same low frequency region as the interference sound.
The setting of the sweep drive cycle and output power is the same as in the first embodiment.

(Steps 17 and 18)
As in the first embodiment, the control unit 1 determines whether or not a heating stop instruction is input from the operation unit. If there is no input, the control unit 1 returns to step 12 and repeats the above operation. On the other hand, when there is an input of a heating stop instruction, the process proceeds to step 18 to stop the output of the drive signal to each inverter and stop the energization of the heating coil. And it returns to step 10 and repeats the said operation | movement.

As described above, also in the present embodiment, the same effect as in the first embodiment can be obtained.
In addition, the driving frequency of the heating coils 8 and 32 is desirably the same because interference sound is generated by the difference frequency. However, both coils have different constants such as impedance due to the difference in coil shape, and the heating frequency is large due to the same frequency limitation. There are restrictions.
For this reason, even when a plurality of heating coils provided close to one heating port are driven at different driving frequencies, the difference frequency is set as a low frequency region, and the inverter that has been in a stopped state is used. Interference sound can be masked by sweep driving, and the difference frequency of the plurality of heating coils provided in one heating port can be allowed to vary within the low frequency range (1 to 5 kHz). Become.

In the first and second embodiments, when the wide band gap semiconductor such as silicon carbide (SiC), gallium nitride-based material (gallium nitride; GaN), or diamond is used for the switching element constituting the arm of each inverter. good.
Since the switching element formed of such a wide band gap semiconductor has low power loss, it is possible to suppress a reduction in efficiency even when driving with a short drive period.
In addition, switching elements formed of wide bandgap semiconductors have high voltage resistance and high allowable current density, so that the switching elements can be miniaturized. By using these miniaturized switching elements, It is possible to reduce the size of a semiconductor module incorporating the above element. Further, since the heat resistance is high, the heat radiation fins of the heat sink can be downsized and the water cooling part can be air cooled, so that the semiconductor module can be further downsized.

  Note that the switching element is not limited to a wide band gap semiconductor, and the effects of the present invention can also be achieved by using IGBTs, power MOSFETs, other insulated gate semiconductor devices, and bipolar transistors.

  DESCRIPTION OF SYMBOLS 1 Control part, 2 Control part L, 3 Control part C, 4 Control part R, 5 Inverter L, 6 Inverter C, 7 Inverter R, 8 Heating coil, 9 Heating coil, 10 Heating coil, 11 Current sensor, 12 Current sensor , 13 Current sensor, 14 Resonance capacitor, 15 Resonance capacitor, 16 Resonance capacitor, 17 Voltage sensor, 18 Voltage sensor, 19 Voltage sensor, 20 Heating port, 21 Heating port, 22 Heating port, 23 Housing, 30 Inverter La, 31 Inverter Lb, 32 heating coil, 33 current sensor, 34 voltage sensor, 35 resonance capacitor, 36 heating port.

Claims (7)

A plurality of heating coils for induction heating the object to be heated;
A plurality of inverter circuits for outputting high-frequency power to the heating coil;
Control means for controlling the output power of each of the plurality of inverter circuits by varying the drive frequency of the inverter circuit;
The control means includes
When two or more of the inverter circuits are in a driving state and one or more of the inverter circuits are in a stopped state,
When the difference frequency of the driving frequency of the two or more inverter circuits in the driving state is included in a frequency range preset as a low frequency region of the audible frequency region,
Induction heating, wherein at least one of the inverter circuits in a stopped state is driven, and the drive frequency of the inverter circuit is continuously changed from a lower limit to an upper limit of a predetermined frequency range included in the low frequency region. Cooking device. The period of continuously changing from the lower limit to the upper limit of the predetermined frequency range included in the low frequency region,
The induction heating cooker according to claim 1, wherein the time is shorter than a period of a driving frequency of the two or more inverter circuits in a driving state. The control means includes
When two or more of the inverter circuits are in a driving state and one or more of the inverter circuits are in a stopped state,
When the difference frequency of the drive frequency of the two or more inverter circuits in the drive state is included in the audible frequency region and not included in the range of the low frequency region,
The induction heating cooker according to claim 1 or 2, wherein the two or more inverter circuits that are in a driving state are driven and controlled so that the difference frequency is included in a range of the low frequency region. The low frequency region is 5 kHz or less,
The induction heating cooker according to any one of claims 1 to 3, wherein the predetermined frequency range is 1 kHz or more and 5 kHz or less. The control means includes
When driving the inverter circuit in a stopped state and continuously changing the drive frequency of the inverter circuit from the lower limit to the upper limit of the predetermined frequency range,
The induction heating cooker according to any one of claims 1 to 4, wherein the output power of the inverter circuit is set to a power of less than 10 watts. The inverter circuit is
The induction heating cooker according to any one of claims 1 to 5, wherein the switching element is formed of a wide band gap semiconductor. The induction heating cooker according to claim 6, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.

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