| 摘要 |
PURPOSE:To reliably perform a stable pull-in operation even in case of an AC motor having high deceleration by holding a slip when the motor is inverter operation pulled-in at a low value from voltage reapplication time. CONSTITUTION:A frequency correction signal is led to a multiplier 40, which outputs a voltage signal V multiplied by a constant magnification. The signal V is input through an analog switch 41 to the primary delay element 42, combined with a frequency correction signal by an adder 43, added at the output with the output of an integrator 23, and supplied as an inverter frequency command to an oscillator 28. Thus, when a voltage is reapplied by an inverter, it is attenuated by the primary delay in the amount corresponding to the decrease in the rotating speed until a motor torque is established, thereby reliably stably restarting by maintaining the slip at the pulling-in time low. |
