| 摘要 |
PROBLEM TO BE SOLVED: To prevent increase of harmonics of a power supply current waveform resulting from a temperature characteristic of a magnetron. SOLUTION: It has a booster transformer 13, which supplies high-voltage electric power to the magnetron 12, an inverter circuit 15, which rectifies alternate current power supply voltage 14, converts it into alternate current having predetermined frequency, and supplies it to the booster transformer 13, and an output setting means 16. The inverter circuit 15 has a modulation part 17, a driver part 18, and a semiconductor-switching element 19. The modulation part 17 makes a modulation signal from a power supply voltage detection means 20 detecting the voltage of the power supply, from which the inverter circuit 15 obtains electric power, a magnetron state detection means 21 detecting information on the output and the time when the magnetron 12 is operating, and an output setting means 16. The driver part 18 is constituted to determine a pulse signal for driving the semiconductor switching element 19 based on the modulation signal and the signal from the output setting means 16.
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