Patent ID: 7392879

Claim:
A motor-driven power steering apparatus using a brushless motor as an electric motor, having a coil winding around a slot of a stator core and capable of supplying a driving current to the coil winding by a motor drive means, when converting a rotation of the electric motor into a stroke of a rack shaft by a power transmission mechanism, and assisting a steering of a tire wheel connected to the rack shaft, wherein a main coil winding and an auxiliary coil winding are wound around the same slot of the stator core in parallel, and wherein the motor drive means has a main driver arranged to feed at least to the main coil winding and an auxiliary driver feeding only to the auxiliary coil winding, the main driver being actuatable so as to be capable of assisting the steering under normal conditions of a control system of the electric motor, and the auxiliary driver being actuatable so as to execute an assist control corresponding to a motor friction torque under abnormal conditions of the control system of the electric motor.