| 摘要 |
PURPOSE:To allow driving of an induction motor at a highest efficiency point at all times by controlling the slip frequency for correcting the torque of the induction motor depending on a voltage command to be applied to the induction, motor. CONSTITUTION:A slip frequency signal 10 is initially set at a constant f0. The slip frequency 10 is shifted by a slight amount fX to a frequency f1 during an interval when a speed command signal 13 is shifted to a predetermined value which is sustained until the rotational speed of an induction motor 1 is sufficiently settled. Although r.p.m. of the induction motor 1 is varied to cause variation of a speed feedback signal 9, the speed feedback signal 9 is controlled to be identical with the speed command signal 13 so that the induction motor 1 has r.p.m. corresponding to the speed command signal 13. This constitution allows the induction motor to be driven at a highest efficiency point at all times. |
