Electro-dynamic braking device for universal motor, has winding fed over triacs during brake operation, where motor operation during brake operation is sufficient for commutation at motor collector and is not sufficient to drive armature

摘要

The device has a field winding (3) fed over a set of triacs (1, 1') from a network during brake operation. Universal motor operation is performed at a short-time within a half cycle during the brake operation. The brake operation is performed when one of the triacs is controlled with a predetermined time delay. The time delay for controlling the triac is selected such that the motor operation in the half cycle during the brake operation is sufficient for brush-saving commutation at a collector of the motor and is not sufficient for driving an armature (2).