| 摘要 |
PURPOSE:To allow a motor to continue its operation without stopping an inverter in case large systematic oscillation is caused to a power source, by giving small oscillation speed command to an inverter control circuit as the speed command of an induction motor when an AC power source is in oscillation. CONSTITUTION:Oscillation detecting signals of an AC power source oscillation detection circuit 23 are given to a command discrimination circuit 24 and a speed command circuit 25. When the oscillation detecting signal is inputted, the command discrimination circuit closes (b) of a changeover switch 26. On the other hand, with the oscillation detecting signal the speed command circuit 25 adds the speed command value in oscillation SL to a voltage-frequency command circuit 10 with which a motor 3 can stably be operated even if there occurs voltage fluctuation to the input power from the AC power source 2. |
