CONTROL SYSTEM OF INDUCTION MOTOR BY PWM INVERTER

摘要

PURPOSE:To prevent operating mode from being changed into deceleration mode unnecessarily during power running, by controlling the operating point of a three-value hysteresis comparator, generating a torque increase and decreasing signal, variably. CONSTITUTION:A three-value hysteresis comparator is incorporated in a block 812 and the operating point T1 of the lower half of a torque command T is changed into TS, sent from the block 804, when the code of the torque command T is positive while the operating point T1 of the upper half of the same command T is changed into TS when the code of the torque command T is negative. The operating point of the block 812 is changed in such a manner, thereafter, the block 812 sends out the control flag (ftau) of a torque while deciding from a torque difference, sent from the block 702. According to this operation, frequency, in which the operation of an induction motor jumps into the hysteresis loop of regenerative side during power running, becomes very small and frequency, in which the operation of the same motor jumps into the hysteresis loop of power running side during regenerative operation, becomes very small in the same manner.