| 摘要 |
PROBLEM TO BE SOLVED: To simplify the configuration of an apparatus to further reduce the size thereof, and to improve operation efficiency by eliminating the need for adjustment or design which depends on types of magnetrons. SOLUTION: An input current fed to an inverter circuit is detected at a shunt resistor 71 and converted to an input current waveform through an input current signal amplifier 72. On the other hand, a reference waveform responsive to the magnitude of the input current waveform is obtained through a gain variable amplifier circuit 91 from an AC power supply voltage waveform obtained from an AC power supply voltage. A waveform error detection circuit 92 obtains a waveform error signal by making a comparison between the input current waveform and the reference waveform. A comparator circuit 74 obtains a current error signal by making a comparison between the input current waveform and an input current reference signal obtained from an output setting part 75 for obtaining a desired high frequency output. Then, a mix-and-filter circuit 81 adds the waveform error signal to the current error signal to obtain a power control signal for driving a switching transistor 39 of the inverter circuit. Here, the reference waveform is generated only on the basis of the AC power supply voltage waveform and a feedback signal of the waveform error signal. COPYRIGHT: (C)2007,JPO&INPIT
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