Control apparatus of electric power steering

A control apparatus of an electric power steering system coupled to a steering wheel, wherein the electric power steering system includes a motor and a circuit related to control of the motor, wherein the motor generates assist force for reducing steering force of the steering wheel, the apparatus comprising:

• calculating means, which calculates an assist current value that corresponds to the assist force based on steering torque of the steering wheel;
• controlling means, which executes assist control of the motor based on the assist current value such that the motor generates the assist force;
• determining means for determining an abnormality in the circuit;
• suppressing means, which suppresses the assist control when an abnormality in the circuit is determined, wherein, if the determination of an abnormality has continued longer than a predetermined time since the suppression of the assist control, the suppressing means opens relay means that permits electric power to be supplied to the motor;
• and
• canceling means, wherein, when it is determined that the circuit returns to normal with the assist control suppressed, the canceling means cancels the suppression of the assist control.