Patent ID: 8538632

Claim:
An electric power steering apparatus using a three-phase brushless motor to generate a steering assist force, comprising: a motor driving circuit for supplying electric power to the three-phase brushless motor; a relay that can open or close contacts interposed between the motor and the motor driving circuit and respectively inserted to at least current paths of two phases among current paths of three phases for supplying electric power from the motor driving circuit to the three-phase brushless motor; a current detector for detecting respective phase currents flowing in the current paths having the contact inserted; and a controller for controlling the relay and the motor driving circuit, the controller starting a conduction check process for the closed contacts, prior to an assist control by the motor, to make a continuous condition that no current flows in the current path of one of three phases whereas currents on driving current waveform for the motor having an identical absolute value with positive and negative signs different from each other flow in the current paths of the other two phases at one energization angle on the driving current waveform, the controller performing a conduction check process under the aforementioned condition by the current detector actually detecting current flowing in at least one phase of current paths having the contact inserted.