| 摘要 |
The object of the invention is not only to simplify the structure of a high frequency dielectric heating power control apparatus and reduce the size of the apparatus but also to eliminate the need for control and design corresponding to the kind of a magnetron and thus enhance the running efficiency of the apparatus. An input current to an inverter circuit is detected by a shunt resistor 71 and is converted to an input current wave form through an input current signal amplifier 72. On the other hand, based on an alternating current power supply voltage wave form from an alternating power supply voltage, there is obtained through a gain variable amplifier 91 a reference wave form following the size of the input current wave form. A wave form error detect circuit 92 compares the input current wave form with the reference wave form to obtain a wave form error signal. A comparison circuit 74 compares the input current wave form with an input current reference signal obtained from an output setting part 75 for obtaining a desired high frequency output to thereby obtain a current error signal. And, a mix and filter circuit 81 adds the wave form error signal and the current error signal to obtain a power control signal for driving a switching transistor 39 of the inverter circuit. Here, the reference wave form is generated based only on the alternating current power supply voltage wave form and on the feedback signal of the wave form error signal.
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