Patent ID: 7226069
Filing Date: 2007-06-05
Classification: B62D,H02P

Abstract:
1. A power-assisted steering system for providing an auxiliary steering force to a steering mechanism of a vehicle by driving a brushless motor having first, second, and third phases and terminals based on a target current value determined in accordance with an operation for steering the vehicle, the power-assisted steering system comprising: first and second current detectors that detect current flowing to the first and second phases, respectively, of the brushless motor and output detected current values, the current detectors respectively including inherent gain values, one of the current detectors constituting a reference; a correcting unit that corrects the detected current values output from the first and second current detectors so as to compensate a difference in gain between the current detectors; and a motor driving driver that drives the brushless motor based on a deviation between the target current value and the detected current values which are corrected by the correcting unit, wherein when the same current flows to the phase in which the current flowing thereto is detected by the reference current detector and the phase in which the current flowing thereto is detected by the other current detector, the correcting unit calculates a gain correcting coefficient for compensating for a gain difference of the other current detector relative to the reference current detector based on a detected current value of the reference current detector and a detected current value of the other current detector, and corrects the detected current value of the other current detector based on the calculated gain correcting coefficient.