| 摘要 |
PURPOSE:To secure a phase contol quick in response which is not to impair stability of an AC motor system against fluctuation of an AC bus frequency by a method wherein frequency of an AC bus voltage is detected and then given to a frequency converter as a frequency command signal through a delay follow-up circuit. CONSTITUTION:When a change-over switch 3 and a switch 12 are closed, a speed command signal in proportional to a voltage of an AC bus 1 is given to a delay follow-up circuit 13 from a frequency detector 10. The delay follow-up circuit 13 gives an operation pattern to accelerate an AC motor 5 in optimal condition to a frequency converter 2. When the acceleration is over, a zero retaining switch 17 is opened, and a phase difference between an output voltage of the frequency converter 2 and a voltage of the AC bus 1 is given to the frequency converter 2 from a phase difference detector 15. Upon completion of synchronization, a switch 4 is closed and the change-over switch 3 and the switch 12 are opened. |
