Patent ID: 7414425
Filing Date: 2008-08-19
Classification: H02M,H02P

Abstract:
1. A method for measuring current by a sensor in a three-phase motor operating in a damping mode, drive current to the three-phase motor switched by an upper bank of switches and a lower bank of switches controlled by a plurality of pulse width modulation signals, the method comprising the steps of: determining when mechanical feedback into the motor exceeds a predetermined threshold; closing all of the switches of one of the upper and lower bank of switches to provide damping of the mechanical feedback; after the closing step, periodically switching selected switches necessary to measure the current in at least one phase of the motor; sampling the current of the phase selected in the switching step by the sensor; repeating the switching and sampling steps until the sampled current in the sampling step indicates that the mechanical feedback into the motor has fallen below the predetermined threshold; and exiting the damping mode.