| 摘要 |
PURPOSE: To resume the operation of a voltage-type inverter in a stable state while an induction motor is being run freely. CONSTITUTION: A first comparator 21, a second comparator 22, a timer circuit 23, a base cutoff circuit 24, a rotational-speed detection circuit 25 and a limiter circuit 26 are added to a control circuit for a voltage-type inverter. The base cutoff circuit 24 detects a rotational speed on the basis of the residual voltage of an induction motor 4 when a base signal is turned off, and the inverter is operated by a frequency set value corresponding to the rotational speed when the base signal is turned on again. |
