Patent ID: 7138782

Claim:
A motor control system comprising: a motor controller for generating a motor control output according to a reference signal and a first signal; a compensating device including: a low pass filter (LPF) for averaging and filtering the motor control ouputs sequentially, so as to obtain a corresponding estimated DC value; a compensating offset generator for receiving an initial compensating offset and for sequentially generating a corresponding estimated compensating offset to be a second signal according to the estimated DC value; and an adder for adding up the motor control output and the estimated compensating offset sequentially to output a corresponding motor control output for further controlling the motor device; wherein the low pass filter, the compensating offset generator, and the adder are situated on a second feedback path, and the second signal generated by the compensating offset generator compensates the motor control output received by the compensating device via the second feedback path, so as to obtain the corresponding compensated motor control output; and wherein the compensating device utilizes the compensated motor control output to reduce a steady-state phase error between the first signal and the reference signal.