| 摘要 |
PURPOSE:To control the current of an AC motor so as not to exceed the maximum rated value at the power drive and regenerative time by providing a function of limiting a reference current value. CONSTITUTION:A comparator 20 obtains a difference between a detecting speed omegad and a reference speed omegas, and judges whether an AC motor 1 is operated in power drive or regenerative state from the polarity of the deviation. A correcting circuit 21 selects a constant in accordance with the judged result form the comparator 20 to obtain a corrected reference current signal iSC. The signal iSC is input to multipliers 22u, 22v, 22w, respectively multiplied by current signals iu, iv, iw from a phase generator 23, thereby obtaining reference current signals iUS, iVS, iWS corrected so as not to bring the maximum rated value higher than that of the motor 1. |
