| 摘要 |
PURPOSE: To provide exact speed control even after a speed sensor-less vector controller is operated with low excitation. CONSTITUTION: A current control computation part 5 computes and outputs voltage command values v1d *, v1q * so as to make detected current values i1d , i1q equal to the primary current of an induction motor 2. An inverter 1 sends, to the induction motor 2, the primary current iu , iv , iw corresponding to the primary voltage control commands vu , vv , vw into which the voltage command values v1d *, v1q * are converted by mean of coordinate conversion and conversion of 3-phase into 2-phase. An estimated motor speed value ωr # is estimatedly- computed by a same dimension flux observer 8 and a speed adaptive mechanism 9. When the exciting shaft current command value i1d * is made smaller than the rated value, namely i1dw , for low excitation operation, an input value conversion part 22 converts voltage command values v1dw *, v1qw * and the detected current values i1d , i1q into the value at the time of rated operation and sends them to the same dimension flux observer 8. |
