Electric assist steering system having an improved motor current controller with notch filter

摘要

A motor controller includes a summing circuit (186) for summing a motor current command signal (i.sub.rcmd) with a motor current feedback signal (i.sub.s) and for providing an error current command signal (. DELTA.i.sub.cmd) having a value functionally related to the difference between the motor current command signal and the motor current feedback signal. A notch filter (200) filters the error current command signal and provides a filtered current command signal. The notch filter (200) is adapted to notch out frequencies from the error current command signal about the resonant frequency of a motor (28). A drive circuit (120, 204) energizes the motor (28) in response to the filtered current command signal. A motor current sensor (97) is used for sensing motor current and providing the motor current feedback signal (i.sub.s).