| 摘要 |
PURPOSE:To control the overcurrent of an inverter by providing an induction motor (IM) overload protecting circuit added to a sensorless vector controller for detecting the torque overcurrent of the IM to feed back it to a speed command to prevent the overload current of the inverter. CONSTITUTION:An overload current of an IM input circuit generated by the overload operation of the IM is detected as the overcurrents of a magnetic flux current Iid' and torque current Iiq' of a circuit 1. A torque current Iiq' is fed back to a speed command as an angular velocity omegaSM of an overtorque element in means 12 via means 10 and 11, and a speed command omegar1* is subtracted by omegaSM to become a new speed command omega<r>*. As a result, primary voltage elements U*, V*, W* to a PWM inverter driver 4 are varied, an inverter 5 is abruptly controlled to prevent the overload current of the inverter, thereby preventing the releasing operation of a thermal relay, an AC breaker. |
