Electric power steering system

An electric power steering system operative to decide a target current value of an electric motor according to an operation of a steering member and to provide steering assist by applying a power of the motor to a steering mechanism, comprising:

• torque-ripple compensation decision means which uses rotational position information on the electric motor and the decided target current value to thereby decide a compensation value for current high-order-component for canceling torque ripple caused by predetermined high-order components of the current flowing through the motor;
• correction means for correcting the decided target current value by using the compensation value supplied from the torque-ripple compensation decision means;
• and
• feedback control means for providing feedback control of the electric motor based on the target current value corrected by the correction means.