Patent ID: 8125175

Claim:
An electric steering system comprising: a steering torque detection unit which detects a steering torque acting on the shaft; a brushless motor which includes a rotor and a stator having multi-phase stator coils, and generates an assisting torque for assisting the steering torque; a current supply switching unit which drives the brushless motor by switching a current supply between each phase stator coil; a rotary angle estimation unit which estimates a rotary angle of the rotor of the brushless motor and outputs an estimated rotary angle; a determination unit which determines whether the estimated rotary angle is appropriate by comparison with a direction of the steering torque detected by the steering torque detection unit; and a steering control unit which drives the brushless motor in accordance with the estimated rotary angle determined to be appropriate by the determination unit to control generation of the assisting torque, wherein the determination unit which determines whether the estimated rotary angle is appropriate by determining whether a steering direction input by a driver is the same as a direction of the assisting torque output from the brushless motor.