| 摘要 |
PURPOSE:To transfer an operation of an inverter to a synchronous operation when a phase difference falls within a predetermined range by providing a circuit for detecting the output of a circuit for detecting the phase difference with the output of an inverter and an AC power source is an inverter control circuit. CONSTITUTION:An inverter control circuit 5 produces a clock pulse signal 10 to an inverter controlling synchronous oscillator through a phase difference detecting circuit 13, a controlling amplifier 14 and a voltage controlled oscillator 16 on the basis of the feedback signal 8 of the inverter output and the phase reference signal 9 of the AC power source. In an asynchronous operation, a switch 25 is closed so that the output of the controlling amplifier 14 becomes zero. When a switch 18 is closed to transfer to the synchronous operation, a pulse of the width responsive to the phase difference of signals 8, 9 is generated at the output terminal C, D of the phase difference detecting circuit 13, where C is positive and D is negative, and when the phase difference detected by the pulse width detecting circuits 20-1, 20-2 becomes lower than a predetermined value, the switch 25 is opened, and is transferred to the state of synchronous operation. |
