| 摘要 |
PURPOSE:To secure the normal travel even if one phase gets out of order by detecting a current at each phase of an elevator cage driving three-phase induction motor and performing a job for supply current control while, when something is wrong with one detector, making it so as to be controlled with the remaining two-phase detection currents. CONSTITUTION:Trouble in current detectors 15-17 detecting each phase current of a three-phase induction motor 5 is detected by a trouble detector 31, and according to the troubled phase, each of trouble detection signals 31a-31c is outputted to a current control circuit 14. When these trouble detection signals 31a-31c are inputted, a microcomputer, constituting this current control circuit 14, operates a pulse-width-modulation(PWM) signal with the remaining two-phase detection current, outputting it to an inverter 4. Thus, normal operation can be done even if one-phase detector gets out of order. |
