JPH0878149A - Electromagnetic cooker - Google Patents

Abstract

PURPOSE: To prevent the interruption to the receipt of a public radio by judging whether the frequency of a switching signal is coincident to a specified frequency or not, and controlling and generating an output frequency, avoiding the band of the specified frequency. CONSTITUTION: When a heating set value Wset corresponding to the heating power of an inverter circuit 2 is set from an input device 7, a microcomputer 4 converts an output frequency f0 from the heating set value, and determines an output frequency N times a standard frequency. The input current value Iin inputted to the circuit 2 under dielectric heating is detected by a current detecting circuit 5, and the microcomputer 4 reads the current value Iin as a heating output value Wout and compares it with the set value Wset . The numerical value N is raised or lowered according to the magnitude to raise or lower the inverter operating frequency, and the heating output is changed to conform the set value Wset to the output value Wout . A frequency control means 4a sets and controls the set value Wset avoiding the band of a frequency forming a radio fault stored in a switching memory means 4b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic cooker which drives an electromagnetic induction coil by an inverter circuit to induction-heat an object to be heated in a cooking pot.

[0002]

2. Description of the Related Art Conventionally, in the output control of an electromagnetic cooker, when a high frequency current is applied to an electromagnetic induction coil by an inverter circuit, the current value input to the inverter circuit during induction heating is detected and input by an input device. This is done by adjusting the frequency of the switching signal supplied to the inverter circuit so that the heating power corresponds to the set heating value.

FIG. 6 is a block diagram showing a circuit configuration of a conventional electromagnetic cooker. As shown in FIG. 6, 61 is an electromagnetic induction coil that induction-heats a cooking pot, and 62 is an inverter circuit. The inverter circuit 62 includes a resonance capacitor 62a added to the electromagnetic induction coil 61, a power transistor 62b for switching driving, a diode bridge 62c for smoothing an alternating current, a choke coil 62d, and a smoothing capacitor 62e. The current value input to the inverter circuit 62 during induction heating is the current detection circuit 63.
The current value detected by the current transformer CT of No. 1 is A / D converted by the A / D conversion circuit 64 as a heating output value and then taken into the microcomputer 65. Then, the microcomputer 65 compares the heating set value input by the input device 66 with the A / D converted heating output value, and if the heating output value is small, raises the heating output, and conversely the heating output value. If is larger, the instruction value was output to the D / A conversion circuit 67 so as to lower the heating output.

The heating output instruction value is D / A converted by a D / A conversion circuit 67 and input to a VCO circuit (voltage controlled oscillation circuit) 68. The rectangular wave signal output from the VCO circuit 68 is amplified by the drive circuit 69 and output as a switching signal that drives the power transistor 62b of the inverter circuit 62 for switching. Here, since the heating output and the output frequency of the inverter circuit 62 are inversely proportional to each other, the output frequency of the rectangular wave signal of the VCO circuit 68 is inversely proportional to the input control voltage thereof. That is, V
The larger the heating output instruction value (input control voltage) given to the CO circuit 68, the lower the output frequency of the VCO circuit 68 and the higher the heating output of the inverter circuit 62. Also,
If the inverter circuit 62 changes the maximum induction heating to the minimum induction heating with a stable heating output against fluctuations in the power supply voltage, the output frequency of the VCO circuit 68 should be changed continuously in the frequency band from about 20 KHz to 50 KHz. Need to control.

Further, conventionally, in an electromagnetic cooker of this type, a current detection circuit for detecting a current value input to an inverter circuit during induction heating, and a heating set value in which the detected current value is set as a heating output value. By comparison, the PLL circuit that controls the output frequency with the VCO circuit and the like, and the frequency discriminating means that discriminates the resonance frequency band due to the material of the cooker pan, the positional deviation, etc., from 15 KHz to 80 KHz by the cooker pan material, There has been proposed an electromagnetic cooker that detects a position shift or the like to notify the user or stop the induction heating output (see Japanese Patent Laid-Open No. 60-150580).

[0006]

However, in this type of electromagnetic cooker, the frequency band (long wave) of 20 KHz to 50 KHz used for driving the electromagnetic induction coil is
May interfere with reception of public radio waves. For example, the standard radio wave emission station in Ibaraki Prefecture, JG2AS, oscillates 40.0 radio waves.
It is 00 KHz. Since the electromagnetic cooker normally operates with a large electric power of several KW, considerable noise is generated in the fundamental wave component of its output frequency, and public electric waves (for example, 40.000K) are generated.
However, even in the electromagnetic cooker disclosed in Japanese Patent Laid-Open No. 60-150580, the material of the cooking pot, the positional deviation, etc. are detected by discriminating the frequency, but by discriminating the frequency band of public radio waves. It does not have a configuration for controlling while avoiding the frequency band.

The present invention has been made in consideration of the above circumstances. By pre-storing frequencies used in the public and driving the inverter circuit while avoiding the frequencies, the reception of public radio waves is disturbed. No electromagnetic cooker is provided.

[0008]

FIG. 1 is a block diagram showing the basic configuration of the present invention. In FIG. 1, the present invention includes an electromagnetic induction coil 101 that induction-heats a cooking pot, and an electromagnetic cooking that includes a resonance capacitor 102a added to the electromagnetic induction coil 101 and an inverter circuit 102 that is switching-driven to generate a high-frequency current. In the heater, an input means 103 for inputting a heating set value corresponding to the heating power of the inverter circuit 102, and a switching signal generation means 104 for generating a switching signal and supplying the switching signal to the inverter circuit 102.
A current detecting means 105 for detecting a current value input to the inverter circuit 102 during induction heating; and an input means 103.
The frequency control means 106 for controlling the frequency of the switching signal by comparing the heating set value input in step S1 with the heating output value corresponding to the current value detected by the current detecting means, and the specific frequency causing the radio wave interference in advance. And a specific frequency storage means 107 for storing the frequency control means 106.
Indicates that the frequency of the switching signal is the specific frequency storage means 1
The electromagnetic cooker has a function of determining whether or not it matches the specific frequency stored in 07, and controls the output frequency of the switching signal generating means while avoiding the band of the specific frequency.

The switching signal generating means 104 is
Reference frequency oscillation circuit 1041 that oscillates a reference frequency signal
And the output frequency is divided into 1 / N by the program, 1 / N
Programmable frequency dividing circuit 1042 and phase comparison circuit 10 for synchronizing the output frequency divided by 1 / N with the reference frequency
43 and a voltage controlled oscillator circuit 10 for generating a rectangular wave signal having an output frequency of a switching signal from a synchronized signal.
It is preferable to have a configuration including a PLL circuit 104a having 44 and a drive circuit 104b for amplifying / shaping the rectangular wave signal output from the PLL circuit 104a.

The frequency control means 106 includes the heating set value input by the input means 103 and the current detection means 1
By determining a numerical value that is N times the reference frequency from the heating output value corresponding to the current value detected in 05, and supplying the numerical value N to the 1 / N programmable frequency dividing circuit 1042 in the switching signal generating means 104. It is preferable that the frequency of the switching signal be controlled.

It is preferable that the reference frequency signal is stored in the specific frequency storage means 107 as a frequency division value M which is 1 / M frequency division of the specific frequency as the specific frequency.

In the present invention, the electromagnetic induction coil 1
01 is connected to the resonance capacitor 102a, and high frequency current is generated by the inverter circuit 102 to generate magnetic flux, which causes eddy current loss in the cooking pot to heat it. The inverter circuit 102 includes a resonance capacitor 102a added to the electromagnetic induction coil 101, a power transistor 102b for switching and driving these, a diode bridge for smoothing an alternating current, a choke coil,
It consists of a smoothing capacitor.

A keyboard, a touch panel or the like is used as the input means 103. Further, as the switching signal generating means 104, a reference frequency oscillating circuit 1041 for oscillating a reference frequency signal and an output frequency of 1 by a program
1 / N programmable frequency dividing circuit 104 for dividing to / N
2. A phase comparison circuit 1043 for synchronizing the output frequency divided into 1 / N with a reference frequency, and a voltage controlled oscillator circuit (VCO circuit) 1044 for generating a rectangular wave signal having an output frequency of a switching signal from the synchronized signal. PLL
The circuit 104a and the drive circuit 104b for amplifying / shaping the rectangular wave signal output from the PLL circuit 104a are provided, and a hybrid IC or LSI having circuits having respective functions is used.

A current transformer, a Hall IC or the like is used as the current detecting means 105. For example, the current value detected by the current transformer by an A / D conversion circuit or the like is A /
It is D-converted and input to the frequency control means 106 as a heating output value. As the frequency control means 106 and the specific frequency storage means 107, a microcomputer including a CPU, a RAM, a ROM and an I / O port is used. Also,
The ROM therein is used as the specific frequency storage means 107. Further, the ROM includes an inverter circuit control program of the present invention, a specific frequency monitoring program,
Further, a heating output control program for controlling the cooking pot to a set heating output, a signal processing program for processing a current detection signal, etc. are stored.

[0015]

According to the structure of the present invention, in FIG. 1, when the heating set value corresponding to the heating power of the inverter circuit 102 is input from the input means 103, the switching signal generating means 104 generates a switching signal to generate the switching signal.
Supply to 2. When the inverter circuit 102 performs switching driving of the electromagnetic induction coil 101 and the resonance capacitor 102a added to the electromagnetic induction coil 101 to generate a high frequency current, a magnetic flux is generated in the electromagnetic induction coil 101, and the electromagnetic induction coil 101 has a magnetic flux. An eddy current loss occurs in the cooking pot placed on top and it is heated. Then, the current value input to the inverter circuit 102 during the induction heating is detected by the current detection means 105, and the frequency control means 106 is the heating set value input by the input means 103 and the current detection means 1
The heating output value corresponding to the current value detected at 05 is compared to control the frequency of the switching signal. At this time,
The specific frequency storage means 107 stores in advance a specific frequency that causes radio interference, so the frequency control means 10
6 can control whether or not the frequency of the switching signal matches the specific frequency and control the output frequency of the switching signal generating means 104 while avoiding the band of the specific frequency.

The switching signal generating means 104 is
Reference frequency oscillation circuit 1041 that oscillates a reference frequency signal
And the output frequency is divided into 1 / N by the program, 1 / N
Programmable frequency dividing circuit 1042 and phase comparison circuit 10 for synchronizing the output frequency divided by 1 / N with the reference frequency
43 and a voltage controlled oscillator circuit 10 for generating a rectangular wave signal having an output frequency of a switching signal from a synchronized signal.
44, and the drive circuit 104b for amplifying / shaping the rectangular wave signal output from the PLL circuit 104a, the frequency control means 106 has a value that is N times the reference frequency. The frequency of the switching signal supplied to the inverter circuit 102 can be controlled only by determining

The frequency control means 106 includes the heating set value input by the input means 103 and the current detection means 1.
Switching is performed by determining a numerical value which is N times the reference frequency from the heating output value corresponding to the current value detected in 05 and supplying the numerical value to the 1 / N programmable frequency dividing circuit 1042 in the switching signal generating means 104. If the frequency control means 106 is configured to control the frequency of the signal, the frequency of the switching signal is determined by the frequency control means 106 only by determining a value that is N times the reference frequency, and the heating output of the inverter circuit 102 can be controlled. it can.

The reference frequency signal is one of the specific frequencies.
If the frequency division value M that results in / M division is stored in the specific frequency storage means 107 as the specific frequency, the frequency control means 106 causes the specific frequency storage means 10 to operate.
If the integral multiple M of the reference frequency stored in 7 is not set, it is possible to avoid the specific frequency that causes radio interference.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. The present invention is not limited to this. INDUSTRIAL APPLICABILITY The present invention is mainly suitable for use in an electromagnetic cooker that drives an electromagnetic induction coil by an inverter circuit to induction-heat an object to be heated in a cooking pot, and each constituent element "does not generate a specific frequency that causes radio interference. In addition to achieving "providing an electromagnetic cooker", the invention can be applied to all electric appliances including a microcomputer that controls using a frequency including a specific frequency that causes radio interference.

FIG. 2 is a block diagram showing an embodiment of the electromagnetic cooker of the present invention. FIG. 2 shows the relationship between the inverter circuit and the PLL circuit applied to the electromagnetic cooker of the present invention. A PLL (Phase Locked Loop) circuit is used to control the frequency of the switching signal of the inverter circuit. Figure 2
In the figure, 1 is an electromagnetic induction coil that induction-heats a cooking pot, and 2 is an inverter circuit that drives the electromagnetic induction coil 1 for switching. In addition, the inverter circuit 2 includes a resonance capacitor 2 a added to the electromagnetic induction coil 1 and a power transistor 2 that drives the electromagnetic induction coil 1 for switching.
b, diode bridge 2 for smoothing alternating current
c, a choke coil 2d, and a smoothing capacitor 2e. Reference numeral 3 denotes a switching signal generation circuit, which includes a PLL circuit 3a that generates a switching signal and this PLL.
It is composed of a drive circuit 3b for amplifying / shaping the switching signal output from the circuit 3a.

Further, the PLL circuit 3a is a reference frequency oscillating circuit 3 which oscillates a reference frequency signal fr (250 Hz).
1. Output frequency fo is divided into 1 / N by the program 1
/ N programmable frequency dividing circuit 32, 1 divided by 1 / N
/ N A phase comparison circuit 33 that synchronizes the output frequency fv with the reference frequency fr, an LPF circuit (low-pass filter circuit) 34 that smoothes the synchronized signal and converts it into a voltage value, and a rectangle that converts the converted voltage value into an output frequency fo. It is composed of a VCO circuit (voltage controlled oscillator circuit) 35 that generates a switching signal of waves. Further, the reference frequency oscillator circuit 31
Is a very accurate 1.024MHz crystal oscillator circuit 31
a and a 1/4096 frequency divider 31b, and oscillates at a reference frequency of 250 KHz. A small transistor and a driver IC are used for the drive circuit 3b.

Reference numeral 4 denotes a microcomputer including a CPU, RAM, ROM and I / O port. The microcomputer 4 includes a circuit functioning as a frequency control circuit 4a for controlling the frequency of the switching signal of the PLL circuit 3a. Be done. Also, the ROM of the micro computer 4
Includes a specific frequency memory 4b area for storing a specific frequency that causes radio interference, an inverter circuit control program of the present invention, a specific frequency monitoring program, and a heating output control program for controlling the cooking pot to a set heating output. , A program memory area for storing various programs such as a signal processing program for processing the current detection signal. Further, the micro computer 4 controls all functions of the electromagnetic cooker by various programs.

Reference numeral 5 is a current detection circuit, for example, a current transformer CT is used as a current detection means, is provided in an input portion of the inverter circuit 2 connected to the AC power supply AC, and is input to the inverter circuit 2 during induction heating. Detected current value. Reference numeral 6 denotes an A / D conversion circuit, which converts the current value detected by the current detection circuit 5 into a heating output value by A / D conversion using a peak voltage circuit, an A / D conversion voltage generation circuit, a comparator and the like. The A / D conversion circuit 6 can also be configured in the micro computer 4. Reference numeral 7 is an input device for inputting a heating set value corresponding to the heating power of the inverter circuit 2, and a keyboard, a touch panel or the like is used.

Regarding the control of the frequency of the PLL circuit 3a,
More specifically, the output frequency fv obtained by dividing the output frequency of the VCO circuit 35 into 1 / N by an arbitrary numerical value N and the reference frequency fr (250 Hz) are compared by the phase comparison circuit 33.
When the rising phases of the reference frequency fr and the 1 / N output frequency fv are equal and fr = fv, the output of the phase comparison circuit 33 becomes high impedance. Also, fv
When the phase advances> fr or fv, the H level is output. The output signal of the phase comparison circuit 33 is supplied to the LPF circuit 34.
If the output voltage f of the VCO circuit 35 is smoothed and the voltage value is supplied as the input control voltage signal of the VCO circuit 35,
o is controlled so that fo = fr × N = 250N.

Therefore, by arbitrarily changing the numerical value N by the frequency control circuit 4a in the microcomputer 4, the fo is as accurate as the crystal oscillator circuit 31a.
Can be obtained in units of 250 Hz. In the VCO circuit 35 in this case, the input control voltage signal and the oscillation frequency are proportional. In addition, the rectangular switching signal output from the VCO circuit 35 is amplified / shaped by the drive circuit 3b, and the power transistor 2 of the inverter circuit 2 is amplified.
If it is supplied to b and driven, the microcomputer 4 accurately recognizes and controls the switching frequency of the inverter circuit 2 even in the case of open-loop frequency control.

Since the heating output of the inverter circuit 2 and the output frequency fo are inversely proportional to each other, the VCO circuit 35
The output frequency of the square wave signal of is inversely proportional to its input voltage. That is, the larger the heating output, the VCO circuit 3
The output frequency of 5 decreases and the heating output of the electromagnetic cooker increases. In addition, the electromagnetic cooker is a VCO circuit that continuously changes in a frequency band range of about 20 KHz to 50 KHz if it changes from maximum induction heating to minimum induction heating with a stable heating output against fluctuations in power supply voltage. The output frequency fo of 35 is controlled. That is, the normal microcomputer 4 decreases the numerical value N to decrease the operating frequency of the switching signal when it is necessary to increase the heating output, and increases the numerical value N when decreasing the heating output to increase the output frequency f.
o is controlled within the range of 20 KHz <fo (= 250 N) <50 KHz.

The output frequency fo = N × fr = 25
If 0N becomes a frequency (N = 160) that interferes with public radio waves (40.000 KHz, for example), the specific frequency (40.000
KHz) or the frequency division value M = 160 is stored and the output frequency fo may be controlled so as not to fall within the range of 40.000 KHz ± 500 Hz. Here, the change of the heating output fo is slightly discontinuous, but since it is in the range of about 1 KHz, there is no practical problem in controlling the heating output.

FIG. 3 is a circuit diagram showing an example of a circuit when the PLL synthesizer IC is applied to a PLL circuit. As shown in FIG. 3, the PLL synthesizer IC (MC14516
3) 30 is a reference signal oscillation circuit 31 (crystal oscillation circuit 31
a, 1/4096 frequency divider circuit 31b), a 1 / N programmable frequency divider circuit 32, and a phase comparison circuit 33 (see FIG. 2). By setting the input terminals P1 and P2 to H level, the reference oscillation signal 1.024 MHz is 1/40
The reference frequency fr of the reference signal oscillation circuit 31 is divided by 96.
= 250 Hz.

The output frequency fo output from the VCO circuit 35 is input as the input frequency fin of the PLL synthesizer IC, and the input frequency fin is divided by 1 / N to obtain a numerical value N.
It was set in the range of 10 ⁰ ~10 ^3, BCD microcomputer 4
(Binary code) output terminals O _{0 to} O ₁₅ to PLL
Input to the input terminals I _{0 to} I ₁₅ of the synthesizer IC, and the 1 / N programmable frequency divider 32 (not shown) outputs the frequency fv.
, Fv and fr are compared in the phase comparison circuit 33, and the output signal is output to the LPF circuit 34 and becomes the input control voltage of the VCO circuit 35.

The numerical value N can be set as a 4-digit numerical value from the microcomputer 4, and if the input / output characteristics of the VCO circuit 35 allow it, 750H.
It is possible to obtain frequencies at intervals of 250 Hz from z to 1024 KHz, but since only about 20 KHz to 50 KHz is actually required, the relationship between the output frequency fo and the input control voltage Vin of the VCO circuit 35 is about 15 as shown in FIG.
Design in the range of KHz to 60 KHz. Figure 4 is a VCO
It is explanatory drawing which shows the input / output characteristic of a circuit. Also, this VC
The O circuit is the same as that shown in FIG. 3, but the internal configuration of the VCO circuit can be the same as that of the conventional one, and therefore its explanation is omitted. Further, the LPF circuit 34 shown in FIG. 3 has an appropriate CR value (time constant) so that the response time is not too delayed and the response is too fast to make the operation of the VCO circuit 35 unstable.

FIG. 5 is a flow chart showing the frequency control processing of the frequency control circuit of the present invention. In FIG. 5, step S01: When the heating set value Wset corresponding to the heating power of the inverter circuit 2 is set from the input device 7, the microcomputer 4 converts the output frequency fo from the heating set value to N times the reference frequency. The output frequency is determined, and the numerical value N is initialized. Step S02: The input current value Iin input to the inverter circuit 2 during the induction heating is detected by the current detection circuit 5, and the microcomputer 4 takes this input current value Iin as the heating output value Wout and heats it with the heating output value Wout. The set value Wset is compared.

Step S03: If the heating output value Wout is larger than the heating set value Wset, the numerical value N is incremented (N ← N + 1) to increase the inverter operating frequency and increase the heating output. Step S04: If the heating output value Wout is smaller than the heating set value Wset, the numerical value N is decremented (N ← N-1) to decrease the operating frequency of the inverter circuit 2 and increase the heating output. Step S05: The operating frequency of the inverter circuit 2 is 2
If 50N = 40 KHz, that is, if N = 160, the value of N is set to 162 (N ← N + 2) and the output frequency is slightly shifted. In this step S05,
The specific frequency with N = 160 is stored in the specific frequency memory 4b of the microcomputer 4, and is constantly monitored by the frequency control circuit 4a.

Step S06: The output frequency fo output from the VCO circuit 35 is 20 KHz <fo (= 250
N) <50 KHz (80 <N <200). That is, when N exceeds 200 (MAX),
If N = 199 is set and N exceeds 80 (MIN),
Set N = 79. In step S05,
Frequency range where N = 158-162 (39.500K
(Hz to 40.500 KHz) may be avoided. That is, 80 <N <158, 162 <N <20
The value of N is determined in the range of 0. Step S07: The determined numerical value N is output to the 1 / N programmable frequency dividing circuit 32, the process returns to step S02, and the processes of steps S02 to S07 are repeated. Therefore, the electromagnetic induction coil does not generate an interfering radio wave by switching the inverter circuit while avoiding a specific frequency used for public radio waves such as broadcasting.

[0034]

According to the present invention, an electromagnetic cooker is provided in which frequencies used in the public are stored in advance and the inverter circuit is driven while avoiding the frequencies so as to prevent reception of public radio waves. It is a thing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram showing an embodiment of an electromagnetic cooker of the present invention.

FIG. 3 is a circuit diagram showing an example of a circuit when the PLL synthesizer IC is applied to a PLL circuit.

FIG. 4 is an explanatory diagram showing input / output characteristics of a VCO circuit.

FIG. 5 is a flowchart showing a frequency control process of the frequency control circuit of the present invention.

FIG. 6 is a block diagram showing a circuit configuration of a conventional electromagnetic cooker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic induction coil 2 Inverter circuit 3 Switching signal generation circuit 4 Microcomputer 5 Current detection circuit 6 A / D conversion circuit 7 Input device 2a Resonance capacitor 2b Power transistor 2c Diode bridge 2d Choke coil, 2e Smoothing capacitor, 3a PLL circuit 3b Drive circuit 4a Frequency control circuit 4b Specific frequency memory 31 Reference frequency oscillation circuit 32 1 / N programmable frequency dividing circuit 33 Phase comparison circuit 34 LPF circuit 35 VCO circuit

Claims (4)

[Claims] 1. An electromagnetic cooker equipped with an electromagnetic induction coil for inductively heating a cooking pot, and an inverter circuit for adding a resonance capacitor to the electromagnetic induction coil for switching driving to generate a high-frequency current. Input means for inputting a heating set value corresponding to electric power, switching signal generating means for generating a switching signal and supplying the same to the inverter circuit, and current detecting means for detecting a current value input to the inverter circuit during induction heating, Frequency control means for controlling the frequency of the switching signal by comparing the heating set value input by the input means and the heating output value corresponding to the current value detected by the current detection means, and a specific frequency that causes radio interference Specific frequency storage means stored in advance, the frequency control means, the frequency of the switching signal is a specific frequency Electromagnetic range and controls the output frequency of the switching signal generating means to avoid the bandwidth of the specific frequency has determining whether feature matches the stored specific frequency in the storage means. 2. The switching signal generation means includes a reference frequency oscillating circuit for oscillating a reference frequency signal, a 1 / N programmable frequency dividing circuit for frequency-dividing an output frequency into 1 / N by a program, and a frequency division into 1 / N. And a PLL circuit having a phase control circuit for synchronizing the output frequency with a reference frequency and a voltage controlled oscillation circuit for generating a rectangular wave signal having an output frequency of a switching signal from the synchronized signal, and the PLL circuit.
The electromagnetic cooker according to claim 1, further comprising a drive circuit for amplifying / shaping a rectangular wave signal output from the circuit. 3. The frequency control means determines a numerical value that is N times the reference frequency from a heating output value corresponding to the heating set value input by the input means and the current value detected by the current detecting means. 3. The electromagnetic cooker according to claim 2, wherein the frequency of the switching signal is controlled by supplying the numerical value N to a 1 / N programmable frequency dividing circuit in the switching signal generating means. 4. The electromagnetic cooking device according to claim 2, wherein a dividing value M, which makes the reference frequency signal a 1 / M frequency division of the specific frequency, is stored in the specific frequency storage means as the specific frequency. vessel.