| 摘要 |
PROBLEM TO BE SOLVED: To perform surely and stably in a shortest time the pull-in drive of an AC motor in the course of its free running. SOLUTION: In a motor controller, when after bringing an AC motor 6 driven by an inverter 5 into a free-running state the pull-in drive of the AC motor 6 in the course of its free running is restarted at the timing of its terminal voltage becoming not larger than a predetermined value, there are provided first means 80, 81 for sensing the fact that the sensed current quantity of the AC motor 6 has become not larger than the predetermined value after restarting its drive, a second means 48a for cutting off by the output of the first means 80, 81 a corrective signal giving a predetermined bias to the frequency reference of a pull-in transient time, which is the output signal of a speed sensor 7 of the AC motor 6, a timer means 81a for sensing the lapse of a predetermined time after the second means 48a is opened, and a third means comprising changeover means 47, 48 for operating by the output of the timer means 81a and changing over the frequency command of the inverter 5 into a preset frequency reference used in a usual driving time. |
