Abstract: An electric power steering apparatus may be employed to assist steering of a motor vehicle by conferring torque generated by an electric motor to a steering mechanism. The apparatus may include a steering controller that receives signals representative of vehicle velocity and torque applied to a steering wheel and a rotor position signal to derive a target motor torque, a motor controller that receives the target motor torque from the steering controller and transfers the target motor torque into target voltages expressed in a coordinate system fixed to a stator, and an inverter that transforms the target voltages into motor currents. The apparatus may further include a ripple compensation unit that compensates the target voltages for a (n?1)-th harmonic current by adding compensation voltages to the target voltages.

Abstract: An electric power steering apparatus may be employed to assist steering of a motor vehicle by conferring torque generated by an electric motor to a steering mechanism. The apparatus may include a steering controller that receives signals representative of vehicle velocity and torque applied to a steering wheel and a rotor position signal to derive a target motor torque, a motor controller that receives the target motor torque from the steering controller and transfers the target motor torque into target voltages expressed in a coordinate system fixed to a stator, and an inverter that transforms the target voltages into motor currents. The apparatus may further include a ripple compensation unit that compensates the target voltages for a (n?1)-th harmonic current by adding compensation voltages to the target voltages.