Patent ID: 7503421

Claim:
An electric power steering apparatus comprising: a motor for generating steering assist power; a torque sensor for detecting steering torque; a storing part for storing a relationship between steering torque and basic assist torque; a controller for controlling said motor so that the steering assist power is generated in accordance with the basic assist torque corresponding to the steering torque detected by the torque sensor; a phase control element for the output signal of said torque sensor; and a steering state judgment element for judging whether the steering state is a return steering state in which a steering wheel is steered in the direction toward a straight-forward steering position or a positive steering state in which the steering wheel is steered in the direction away from the straight-forward steering position; wherein the phase control characteristic of said phase control element is altered in accordance with the judgment result of said steering state judgment element so that the gain in the higher frequency band in the frequency response characteristic of the output to input of said torque sensor is reduced in the return steering state in comparison to the positive steering state.