Patent ID: 7880425
Filing Date: 2011-02-01
Classification: B60L,H02P,Y02T

Abstract:
1. An electric motor drive system comprising: an inverter adapted to generate, based on inverter control inputs, a total number, N, of phase current waveforms, and to provide the N phase current waveforms to a same number, N, of motor input terminals; a phase current sampling apparatus having the same number, N, of current sensors, wherein each of the N current sensors is adapted to receive one of the N phase current waveforms that are provided to the N motor input terminals, and wherein the N current sensors are adapted simultaneously to sample the N phase current waveforms and to generate N digital values representing amplitudes of the N phase current waveforms; and a controller adapted to receive the N digital values representing the amplitudes of the N phase current waveforms, to perform an evaluation of the N digital values, and to generate the inverter control inputs based on the evaluation, wherein the controller is adapted to perform the evaluation, at least in part, by determining reference frame currents as a function of all of the N digital values, and wherein the controller is further adapted to measure the phase current waveforms prior to motor operations to produce initial offsets, and to store the initial offsets.