Patent ID: 8019507

Claim:
An electric power steering control system, comprising: a torque detection means that detects a steering torque caused by a driver; a torque controller that computes an auxiliary torque current, which assists the steering torque, using the output of the torque detection means; a motor that generates a torque which assists the steering torque; a current detection means that detects a current value to be conducted to the motor; a rotating speed estimation means that estimates the rotating speed of the motor; and a damping controller that computes a damping current, which is added to the auxiliary torque current, using the estimate value of the rotating speed of the motor estimated by the rotating speed estimation means, wherein: the rotating speed estimation means includes: a motor current steering component removal means that removes a component caused by steering from the output of the current detection means; a torque steering component removal means that removes a component caused by steering from the output of the torque detection means; and a rotating speed observer that computes the estimate value of the rotating speed of the motor using the current which has the steering component thereof removed by the motor current steering component removal means, and the steering torque outputted from the torque steering component removal means; and at least one of a motor current phase lead reducer that diminishes a phase lead caused by the motor current steering component removal means, and a torque phase lead reducer that diminishes a phase lead caused by the torque steering component removal means is included.