JP3436094B2 - High frequency heating equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus using a magnetron, and more particularly to power control of a power supply for driving a magnetron. 2. Description of the Related Art As shown in FIG. 9, a conventional high-frequency heating apparatus uses a circuit configuration called a one-piece voltage resonance type circuit. 1 is a commercial power supply, 2 is a diode bridge composed of full-wave rectification, which rectifies the commercial power supply to form a DC power supply. The choke coil 3 smoothes the fluctuation of the current, and the smoothing capacitor 4 smoothes the fluctuation of the voltage. The rectifying filter unit 5 composed of a low-pass filter circuit including these inductors and capacitors is configured to supply a unidirectional voltage to a subsequent circuit. Energy is accumulated from the rectifying filter unit 5 to the winding of the leakage type step-up transformer 7. The primary winding 28 of the step-up lance 7 and the resonance capacitor 6 arranged in parallel with it constitute a tank circuit and resonate with energy stored in the winding of the step-up transformer 7. Switching means comprising a semiconductor switching element 8 and a diode 9 arranged in parallel with the semiconductor switching element 8 are connected in series to the tank circuit. The commercial frequency AC power is converted to a high frequency power by the inverter 11 constituted by the tank circuit and the switching means shown here. The secondary side of the step-up transformer 7 has a secondary winding 29
And a tertiary winding 30. The voltage induced in the secondary winding 29 includes capacitors 14, 15 and diodes 12, 1
3 is converted into a DC high voltage by a high voltage circuit 16 which functions as a full-wave voltage doubler rectifier circuit, and a high voltage of about -4 kV is applied to the anode and cathode. The inverter power supply circuit 18 is configured as described above. A current transformer 17 is a magnetron 24
And the other current flowing in each branch of the high-voltage circuit 16 are detected as voltages generated at both ends of the secondary side, and transmitted to the inverter control unit 11 for controlling the inverter. Here, the current transformer includes a high-voltage circuit 16 having a chassis ground 26 connected to the equipment chassis and having a ground potential, and an inverter control unit 11 having a ground 27 having a ground 27 formed by an emitter line of the transistor 8 at a ground potential. It functions to transmit signals with electrical insulation. An average current of about several hundred mA flows as a detection current on the primary side of the current transformer 17. The inverter control unit 11 controls the on time of the transistor 8 so that the signal from the secondary side of the current transformer 17 becomes constant, and controls the power transmitted from the inverter unit 10 to the secondary side of the step-up transformer 7. are doing. Further, a signal transmitted from the device control circuit 25 is electrically insulated from the inverter control unit 11 by using a photocoupler 19. FIG. 10 shows a configuration in which the current transformer 17 detects an input current input to the rectifying filter 5.
In this case, the current transformer 17 is connected to the inverter power supply circuit 1
The inverter control unit 1 detects the current input to the inverter 8 as a voltage generated across the secondary side thereof and controls the inverter.
Transmit to 1. Here, the current transformer 17 functions to electrically insulate the inverter control unit 11 having a ground 27 having a ground potential formed by an input line of a power supply and an emitter line of the transistor 8 and transmitting a signal. I have.
The detection current on the primary side of the current transformer 17 is several A
An average current of about 10 to several tens A flows. On the other hand, FIG. 11 detects a current flowing through the diode 13 of the high voltage circuit 16 via the current transformer 17. The voltage at both ends of the secondary output of the current transformer 17 is supplied to the device control circuit 2 via the first connector 21.
5 is transmitted. Here, the device control circuit 25 uses the same control rule as the inverter control unit 11 to control the voltage across the secondary side output of the current transformer 17, that is, the diode 1.
3 is controlled to be constant. However, in the conventional inverter power supply circuit 18 shown in FIGS. 9 and 10, it is general that the power control is self-contained only by the inverter control unit 11. Only an open-loop control command signal for setting the high-frequency output and stopping / operating the inverter power supply 18 was transmitted from the control circuit 25. Therefore, it is necessary for the inverter control unit 11 to completely and completely execute the power control of the inverter power supply circuit 18, and the scale of the control circuit has to be increased. However, in FIG. 11, since the closed loop negative feedback power control in which the feedback is applied to the device control circuit 25 is realized through the device control circuit 25, the device control circuit 25 partially shares the control work. , There is a possibility that the function and circuit scale of the inverter control unit 11 can be reduced. However, when negative feedback control is performed by a microcomputer, a magnitude relationship between a feedback signal to be controlled and a reference value for determining a high-frequency output is determined. When the feedback signal is large, the binary operation signal of the other signal that reduces the feedback signal is reduced. For this reason, information on the magnitude of the difference between the feedback signal to be controlled and the reference value for determining the high-frequency output was not taken into account, and the control response was optimized according to the magnitude of the change when the setting of the high-frequency output was changed. It was difficult to convert. For example, when changing the setting of the high frequency output from the low output to the high output, when the difference is large, the response is slow,
It takes time to reach the target control value, which is an obstacle to realizing a cooking heating pattern based on detailed time management. On the other hand, if the amount of the operation signal is increased to avoid this, the overshoot continues for a long time due to the relationship between the control response of the inverter control unit 11 and the negative feedback control by the microcomputer, and it takes a long time to stabilize. There has been a major problem in terms of control stability, such as maintaining a state in which vibration has occurred. In order to solve the above-mentioned problems, the present invention comprises a circuit including a microcomputer, and as a result of controlling the output of the secondary side of the current transformer to a constant value, an inverter control unit. Has a device control circuit that sends a control command signal for the microwave output of the magnetron and controls the entire high-frequency heating device, and the microcomputer that converts the output of the current transformer from an analog value to a digital value in its microcomputer. D conversion unit, derive a negative feedback control is applied so that each predetermined correction value in accordance with a predetermined parameter range group a reduced Ji values the output of the a / D converter from a reference value for setting a high-frequency output as an argument And a PWM signal section that converts the output of the integration section that accumulates and adds the output of the conversion function section into a pulse width modulation signal. The inverter control unit is controlled by an operation signal converted into a WM signal, and the conversion function unit sets the correction value to:
If the argument value obtained by subtracting the output of the A / D converter from the reference value is positive
If the value is positive or negative, the value is assumed to be negative
If the argument value is positive, the same absolute value
The absolute value of the correction value is smaller than the negative value and the argument value is negative.
In the case of, the absolute value of the correction value is
It is designed to be larger . According to the present invention, a plurality of range groups are provided for the magnitude of the value obtained by subtracting the output of the A / D converter from the reference value, and different correction values are accumulated by the integrating section in accordance with the magnitude. Since addition is possible, it is possible to create a correction value that takes into account information on the magnitude of the difference between the feedback signal to be controlled (the output of the secondary side of the current transformer) and the reference value that determines the high-frequency output. Optimization of control response and securing of stability can be realized. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a magnetron which emits microwaves and has an anode at the same potential as an equipment chassis.
A rectifying filter unit for performing full-wave rectification of commercial power and removing high-frequency components to convert the commercial power into DC power; an inverter unit for turning on / off at least one semiconductor switching element to increase the frequency of the DC power; A step-up transformer that boosts high-frequency power, a high-voltage circuit that rectifies or multiplies the output of the step-up transformer to convert it to a high-voltage DC voltage, and applies a high-voltage DC voltage to the magnetron, and a current or input current that flows through a branch of the high-voltage circuit , An inverter control unit for turning on / off the semiconductor switching element, and a control command signal for the microwave output of the magnetron to the inverter control unit as a result of controlling the output of the secondary side of the current transformer to be constant. It consists of a circuit including a microcomputer that controls the feed and the entire high-frequency heating device Device control circuit and a photocoupler to electrically insulate the control command signal of the device control circuit and send it to the inverter control unit.The device control circuit uses a microcomputer to convert the output of the current transformer from analog value to digital. an a / D converter for converting a value, the output of the a / D converter from a reference value for setting a high-frequency output
A conversion function unit negative feedback control derives the predetermined correction value so as according in accordance with a predetermined parameter range group a reduced Ji values as arguments, an integrating unit for cumulatively adding the output of the conversion function section, the integrator Has a PWM signal section that converts the output to a pulse width modulated signal
The conversion function unit converts the correction value into an A / D conversion value.
Positive if the argument value obtained by subtracting the output from the reference value is positive, negative if the argument value is negative.
The larger the absolute value of the argument range group, the larger the correction value.
If the argument value is positive, the absolute value is the same as the negative value.
Same when the absolute value of the correction value is small and the argument value is negative
The absolute value of the correction value will be larger than when the absolute value is positive.
It is intended to Unishi. A plurality of range groups are provided for the magnitude of the value obtained by subtracting the output of the A / D converter from the reference value, and different integrating values are cumulatively added by the integrating section according to the magnitude. This makes it possible to create a correction value that takes into account information on the magnitude of the difference between the feedback signal to be controlled (the output of the secondary side of the current transformer) and the reference value that determines the high-frequency output, and optimizes the control response. And stability can be realized. Further, when the absolute value of the argument value obtained by subtracting the reference value, the output of the A / D conversion unit is large, that the negative feedback to stabilize at early reference value when the controlled object and the reference value is greatly deviated By increasing the correction value, a quick control response can be obtained. Further, when the value approaches the reference value, the correction amount is reduced, and overshoot occurs.
Unstable control called hunting can be avoided. Further , when the output of the A / D conversion unit to be controlled (comparable to high-frequency output) is large, the correction amount can be increased and the output can be narrowed down quickly. It is possible to quickly return to the low output state from that state and avoid it. On the other hand, when the output of the A / D converter is small,
That is, when the high-frequency output is low, the correction amount is made small and the output is increased relatively slowly, so that overshoot,
Unstable control called hunting can be avoided. Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a circuit diagram of a magnetron driving power supply according to an embodiment of the present invention. In FIGS. 9, B and C, the same functions and the same parts have the same numbers and their explanations are omitted. The difference from the conventional example is that the load resistor 32 is arranged in parallel with the current transformer 17 for detecting the current of the diode 13 of the high voltage circuit 16. The voltage at both ends shows a voltage waveform that matches the AC component of the current flowing on the primary side of the current transformer 17. This is full-wave rectified by the diode bridge 19, and a smooth average waveform in which high-frequency components are removed by a low-pass filter 36 formed by a resistor 34 and a capacitor 35 is obtained at both ends of the capacitor 35. Incidentally, the discharge resistor 37 discharges the charge of the capacitor 36. The voltage across the capacitor 36 is coupled to the second connector 21 and input to the device control circuit 25.
Here, the terminal (b) is a signal. (C) The terminal serves as a base line and is connected to the GND line of the device control circuit 25. (A) The terminal is signal-processed by the device control circuit 25 and the photo-coupler 19
And a control signal line for driving the inverter control unit 11 through the control signal line. Here, the device control circuit 25 performs negative feedback control and power control so that the signal (b) substantially matches the reference value existing inside. The device control circuit 25 is a control unit that controls the entire device, and performs this power control as one of its functions. In recent years, control by a microcomputer has become mainstream, and control using a microcomputer is also described in the embodiment in the present invention. By doing so, since the entire power control function is included as a program in the microcomputer, the circuit scale (mounting area) does not increase at all by transferring the function of the inverter control unit 11 to the device control circuit 25. Breakthrough effects can be found. First, the power control of the present invention in the device control circuit 25 including the microcomputer will be described with reference to FIG. The AC current flowing through the current transformer 17 is converted into a voltage by a resistor 32 at both ends of the secondary winding with a predetermined gain. Low-pass filter 36 and discharge resistor 38
As a result, the high-frequency component of the ripple is removed, and a voltage having a fluctuation in the power supply cycle is input to the A / D converter 38 of the microcomputer 43 in the device control circuit 25, and the average value of the signal is read. The output of the A / D converter 38 is Vi
ad. On the other hand, the reference value 39 for determining the magnitude of the microwave output is expressed as Vref. The microcomputer 43 performs the operation of (Vfef-Viad), and the operation result is input to the conversion function unit 40. The conversion function unit 40 calculates a small fluctuation value d from (Vfef-Viad).
D is calculated, converted and output. Time resolution of integration is Via
Since d reads the average value, and the input of the A / D converter 38 has a half cycle of the power supply cycle, the calculation is performed every half power cycle. The calculation result Idd (∫dDdt) is PWM
The signal section 42 converts the signal into a signal having a duty ratio τ according to Idd. FIG. 3 shows τ shown here and the behavior as a device. (A) is a diagram showing the relationship between the integration output Idd output from the integration unit 41 and the duty ratio τ of the PWM signal output from the PWM signal unit 42, which is proportional. Next, FIG. 2B shows the relationship between the duty ratio τ of the PWM signal and the current to be controlled (current flowing in the branch of the high voltage circuit or input current). This is also in a proportional relationship. Therefore, the current, that is, the power (high-frequency output) handled by the inverter power supply circuit 18 changes in proportion to the output of the integration unit 41. For example, if (Vref-Viad) is positive, the output dD of the conversion function unit 38 becomes +1 and (Vref-Vad).
There is also provided a non-changing area of -1 if iad) is negative, and 0 between positive and negative. FIG. 5 shows a time-series change of each parameter in the microcomputer 43 when such a conventional conversion function is used. (A) When Vref changes from the low level to the high level as shown in the figure, (c) the correction amount dD as shown in the figure
For a while, the increasing state of +1 continues for a while, and the integrated output Idd increases monotonically as shown in FIG. The duty ratio τ of the PWM signal proportional to the integral output Idd also increases monotonically as shown in FIG. Although the inverter control unit 11 and the inverter power supply circuit 18 normally cause a time delay, the A / Ds to be controlled are
Both the output Viad of the converter 38 and the diagram (b) in FIG.
When it reaches, it stabilizes there. FIG. 4 is a diagram showing the relationship between the input and output of the conversion function section 38. (A) The figure shows (Vref-Via
A plurality of range groups are provided for the argument d). When the argument is -2 or less, the function output dD is -2, and the argument is -2.
The value is set to -1 when the argument is -1; 0 when the argument is -1 to +1; +1 when the argument is +1 to +2; and +2 when the argument is +2 or more. As described above, the output values are weighted for the respective range groups. FIG. 6 shows a time-series change of each parameter in the microcomputer 43 when this conversion function is used. When the Vref of the reference value 39 for determining the high-frequency output changes at a certain timing, it shows how each parameter changes accordingly. When (Vref-Viad) is large, the amount of negative feedback is large, so that the parameter Viad representing the high-frequency output approaches the target value more quickly than in the case of FIG. (Embodiment 2) Further, the case where a conversion function as shown in FIG. 4B is used in the diagram showing the input / output relationship of the conversion function unit 38 in FIG. 4 will be described. (B) The feature that the figure is remarkably different from the figure (a) is a part where the argument is large in a plurality of range groups provided for the argument (Vref-Viad).
(B) In the figure, when (Vref-Viad) is greatly different from the reference value, ie, −4 or less and +4 or more, the correction value dD is extremely increased when Viad is far from the reference value. A description will be given of a time-series change of each parameter in the microcomputer 43 when this conversion function is used. FIG. 7 shows that, when Vref of the reference value 39 for determining the high-frequency output changes at a certain timing,
It shows how each parameter changes accordingly. As the value of (Vref-Viad) increases, the amount of negative feedback increases. Therefore, the parameter Viad representing the high-frequency output approaches the target value more quickly than in the case of FIGS. You can see that.
In addition, since there is a gradation that the correction value dD is reduced as the value converges to the reference value, the configuration is such that there is no control problem such as overshoot or hunting. (Embodiment 3) Further, a case where a conversion function as shown in FIG. 4C is used in the diagram showing the input / output relationship of the conversion function unit 38 in FIG. 4 will be described. (C) The characteristic that the figure is significantly different from the figures (a) and (b) is that in a plurality of range groups provided for the argument (Vref-Viad), the argument is minus, that is, Viad (high-frequency output) If is large, return immediately. On the other hand, in the case of plus, ie, Viad
When (high-frequency output) is small, it is slowly returned. By adopting such an asymmetric conversion function pattern, in the event that a high-frequency output is excessively input as a transient phenomenon, the high-output state quickly decreases without being maintained for a long time. Conversely, when shifting from a low output to a high output, it is configured to carefully and slowly raise the output. That is, a fail-safe behavior is obtained in which the output is high from high output to low output and is low from low output to high output. A description will be given of a time-series change of each parameter in the microcomputer 43 when this conversion function is used. FIG. 8 shows such a case. When Vref of the reference value 39 for determining the high-frequency output changes at a point (a) from a high level to a low level, the output quickly shifts to a low level as shown in FIG. 8 (c). It is greatly reduced, and the amount of reduction is reduced as the reference value is approached, so that a control problem such as overshoot or hunting does not occur quickly. Next, when the Vref of the reference value 39 which determines the high-frequency output at the point (b) changes from a low level to a high level, a small correction value dD as shown in FIG. Then, the reference value is approached as shown in FIG. Accordingly, the movement is made to reduce the amount of increase, and the shift is made slowly so that control problems such as overshoot and hunting do not occur. As described above, according to the present invention, a magnetron which radiates microwaves and has an anode at the same potential as the equipment chassis, and a DC power source which rectifies full-wave commercial power and removes high-frequency components. A rectifying filter unit for converting to a power supply, an inverter unit for turning on / off at least one semiconductor switching element to increase the frequency of the DC power supply, a boosting transformer for boosting the high-frequency power of the inverter unit, and rectifying the output of the boosting transformer. Or a high voltage circuit that rectifies the voltage and converts it to a high voltage DC voltage and applies the high voltage DC voltage to the magnetron;
A current transformer for detecting a current or an input current flowing in a branch of the high voltage circuit; an inverter control unit for controlling on / off of the semiconductor switching element; and an inverter control unit as a result of controlling the output of the secondary side of the current transformer to be constant. And a device control circuit comprising a circuit including a microcomputer that sends a control command signal of the microwave output of the magnetron and controls the entire high-frequency heating device, and electrically insulates the control command signal of the device control circuit. and a photocoupler to send to the inverter control unit Te, device control circuit before the a / D converter for converting the output of the current transformer to a digital value from an analog value by the microcomputer, from a reference value for setting a high-frequency output
Cumulative conversion function unit, the output of the conversion function unit for deriving a serial A / D converter unit negative feedback control is applied so that the predetermined correction value in accordance with a predetermined parameter range group reduced Ji and the value output as an argument and an integration unit for adding, a configuration consisting of a PWM signal for converting the output of the integration unit into a pulse width modulated signal, the converting function portion
Subtracts the correction value from the reference value of the output of the A / D converter.
If the argument value is positive, it is positive, if it is negative, it is negative and the absolute value is large.
The correction value increases as the number range group increases, and the argument value is positive.
In this case, the absolute value of the correction value is smaller than the negative case of the same absolute value.
If the argument value is negative, the ratio is
Since the absolute value of the correction value is increased ,
A plurality of range groups are provided for the value of the value obtained by subtracting the output of the / D conversion unit from the reference value, and different correction values can be cumulatively added by the integration unit according to the size. It is possible to create a correction value that takes into account information on the magnitude of the difference between the feedback signal (the output of the secondary side of the current transformer) and the reference value that determines the high-frequency output, thereby optimizing the control response and ensuring stability. Can be easily realized. Since the output value of the A / D converter is subtracted from the reference value, the argument range group having a larger absolute value of the argument value has a conversion function unit for increasing the correction value. When the absolute value of the argument value obtained by subtracting the output from the reference value is large,
That is, when there is a large difference between the control target and the reference value, the correction value, which is the amount of negative feedback, is increased in order to quickly stabilize at the reference value, so that quick control response can be obtained. further,
When the value approaches the reference value, the correction amount is reduced, and the unstable control such as overshoot and hunting can be avoided. On the other hand, when the output of the A / D converter is small, that is, when the high-frequency output is low, the correction amount is made small and the output is increased relatively slowly, so that unstable control such as overshoot and hunting can be avoided. . The output of the A / D converter is converted from a reference value to a correction function which decreases the correction value when the argument value is positive and increases the correction value when the argument value is negative. When the output of the barrel A / D converter (comparable to high-frequency output) is large, it is possible to increase the correction amount and quickly narrow the output. Even in the case of an excessive output state, the output is quickly reduced from that state. Has the effect of being able to return to and avoid the state. On the other hand, when the output of the A / D converter is small,
That is, when the high-frequency output is low, the correction amount is made small and the output is increased relatively slowly, so that overshoot,
This has the effect that unstable control called hunting can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an inverter power supply circuit of a high-frequency heating device according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a control configuration in the device control circuit. FIG. 4B is a diagram showing the relationship between the duty ratio of the PWM signal and the integral output. FIG. 4B is a diagram showing the relationship between the current to be controlled and the duty ratio of the PWM signal. FIG. 4A is a diagram showing the correction values dD and (Vref−Viad).
(B) is a diagram showing an embodiment of a timing chart showing a time transition of (b) and FIG. (C) is a diagram showing another embodiment of a timing chart showing a time transition of (Vref-Viad). FIG. 5 is a diagram showing another embodiment of a timing chart showing a time transition of (Vref-Viad). FIG. 5A is a timing chart showing a time transition of a reference value Vref. FIG. 5B is an output Via of a conventional A / D converter. (C) A timing chart showing a time transition of the output dD of the conversion function section (d) A timing chart showing a time transition of the output Idd of the integration section (e) The output τ of the PWM signal section 6A is a timing chart showing a time transition of the reference value Vref, and FIG. 6B is a timing chart showing an output Viad of the A / D converter in the first embodiment. (C) A timing chart showing a time transition of the output dD of the conversion function unit. (D) A timing chart showing a time transition of the output Idd of the integration unit. (E) An output τ of the PWM signal unit. FIG. 7A is a timing chart showing a time transition of a reference value Vref. FIG. 7B is a timing chart showing a time transition of an output Viad of an A / D converter according to the second embodiment. (D) A timing chart showing a time transition of the output dD of the function section, (d) a timing chart showing a time transition of the output Idd of the integration section, (e) a timing chart showing a time transition of the output τ of the PWM signal section. a) A timing chart showing a time transition of the reference value Vref. (b) A timing chart showing a time transition of the output Viad of the A / D converter of the third embodiment. Chart (c) a timing chart showing the time transition of the output dD of the conversion function section; (d) a timing chart showing the time transition of the output Idd of the integration section; and (e) a timing chart showing the time transition of the output τ of the PWM signal section. Chart [Fig. 9] Circuit diagram of inverter power supply circuit of conventional high frequency heating device [Fig. 10] Circuit diagram of inverter power supply circuit of other conventional high frequency heating device [Fig. 11] Inverter power circuit of other conventional high frequency heating device [Description of References] 1 Commercial power supply 2 Diode bridge 5 Rectifying filter unit 7 Step-up transformer 8 Semiconductor switching element 10 Inverter unit 11 Inverter control unit 16 High voltage circuit 17 Current transformer 19 Photocoupler 24 Magnetron 25 Equipment control circuit 38 A / D Conversion unit 39 Reference value 40 Conversion function unit 41 Integration unit 42 PW Signal unit 43 microcomputer 44 integrator output converter unit

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenji Yasui 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-7-245963 (JP, A) JP-A-6-68972 (JP, A) JP-A-11-87046 (JP, A) JP-A-11-87047 (JP, A) Japanese Patent Application Laid-Open No. H10-1772749 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 6/68 H05B 6/66

Claims (1)

(57) [Claims 1] A magnetron that emits microwaves and has an anode at the same potential as the equipment chassis, and a full-wave rectified commercial power supply and removes high-frequency components to convert it to a DC power supply. A rectifying filter section, an inverter section for turning on / off at least one semiconductor switching element to increase the frequency of the DC power supply, a step-up transformer for stepping up the high-frequency power of the inverter section, and rectifying or multiplying the output of the step-up transformer. A high-voltage circuit for converting the voltage to a high-voltage DC voltage and applying the high-voltage DC voltage to the magnetron; a current transformer for detecting a current flowing through a branch of the high-voltage circuit or an input current; and turning on / off the semiconductor switching element An inverter control unit for controlling the current transformer;
A device control circuit comprising a circuit including a microcomputer that sends a control command signal of the microwave output of the magnetron to the inverter control unit as a result of controlling the output of the secondary side to a constant value and controls the entire high-frequency heating device. A photocoupler for electrically insulating the control command signal of the device control circuit and sending the control command signal to the inverter control unit, wherein the device control circuit converts the output of the current transformer from an analog value to a digital value by the microcomputer. an a / D converter for converting the predetermined said reduced Ji value, the output of the a / D conversion section as the negative feedback control is applied in accordance with a predetermined parameter range group as the arguments from a reference value for setting a high-frequency output A conversion function unit for deriving the correction value of the conversion function unit, an integration unit for cumulatively adding the outputs of the conversion function unit, and a pulse width modulation signal for the output of the integration unit. And formed from a PWM signal portion into a configuration, the transform function section, the correction value, A / D converter
If the argument value obtained by subtracting the output of the part from the reference value is positive,
The correction value is increased as the argument range group is negative and the absolute value is large,
And if the argument value is positive, the same absolute value is negative,
If the absolute value of the correction value is smaller and the argument value is negative,
Increase the absolute value of the correction value compared to when the absolute value is positive
As the high-frequency heating apparatus.