CONTROL DEVICE FOR ELEVATOR DOOR

PURPOSE:To reduce a magnetic sound by providing a zero voltage switching gate circuit which invalidates a gate signal generator circuit of a thyristor while outputs a gate-on signal synchronizing with a change of power source voltage in every quantity of predetermined cycle when an elevator door is fully closed or opened. CONSTITUTION:An elevator door is detected for its full closing or full opening by a door position detecting circuit 6a, while its detecting signal is output to a zero voltage switching gate circuit 9. Then the zero voltage switching gate circuit 9 invalidates a gate signal generator circuit 8 of a thyristor, stopping a torque control of an electric motor by a phase control. Simultaneously by switching an AC control element 1 by zero voltage to be turned on one time per several cycles, the circuit 9 generates equivalent torque in the electric motor M2, reducing a magnetic sound caused by a torque ripple in a high frequency component.