| 摘要 |
PCT No. PCT/JP88/00479 Sec. 371 Date Mar. 13, 1989 Sec. 102(e) Date Mar. 13, 1989 PCT Filed May 20, 1988 PCT Pub. No. WO88/09584 PCT Pub. Date Dec. 1, 1988.A control system for an alternating current motor, such as an elevator hoisting induction motor, in response to failure of power supply, such as service interruption, phase open and so forth, performs in a first emergency control mode and in a second emergency control mode. In the first emergency control mode operation, dynamic braking is used to decelerate the motor. On the other hand, in the second emergency mode, triggered while the motor is driven in regeneration mode to recirculate regenerated power to decelerate the motor, a mechanical brake is applied. During second emergency control mode operation, power supply condition is monitored to detect failure of the power supply for switching control mode from the second emergency control mode to the first emergency control mode. Switching from the second emergency control mode to the first emergency control mode assures synchroneous operation of an inverter and the motor after resumption of power supply to the motor in cases where the power failure is short in duration.
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