| 摘要 |
PURPOSE:To eliminate a switching shock by controlling a torque on the basis of the first inverter control command generator for controlling the torque of an induction motor even if a slip frequency command signal becomes from positive to negative when a speed command signal or a speed signal has the prescribed value or lower. CONSTITUTION:A switching unit 18c receives as inputs the output of a compensating element 14, i.e., a slip frequency command signal 14a and a speed command signal 12. If the signal 12 has the prescribed value or lower, even if the signal 14a becomes from positive to negative, it is ignored so that the unit 18c does not switch from the contact (a) side of contactors 18a, 18b to a contact (b) side. Accordingly, in this case, an inverter controller 21 controls a switching element of an inverter 45 on the basis of a voltage command signal 16a and a frequency command signal 17a, and generates an induction motor 6 corresponding to the signal 14a. |
