Patent ID: 8862330

Claim:
An electric power steering system comprising: an assist mechanism that applies assist torque from a motor to a vehicle steering mechanism; and a control portion that controls driving of the motor based on an assist command value, wherein the control portion includes: a first assist component computation portion that computes a first assist component based on steering torque transmitted to the vehicle steering mechanism; a steered angle command value computation portion that computes a steered angle command value, which serves as a target value of a steered angle of steered wheels, based on the steering torque; a second assist component computation portion that computes a second assist component by performing steered angle feedback control that matches the steered angle of the steered wheels with the steered angle command value; an assist command value computation portion that computes the assist command value based on a value obtained by adding the second assist component to the first assist component; and an adjusting portion that adjusts an absolute value of the second assist component contained in the assist command value so that the absolute value of the second assist component is decreased, based on a given condition, and wherein the first assist component computation portion computes the first assist component in accordance with a degree of adjustment of the second assist component when the second assist component is adjusted by the adjusting portion, the degree of adjustment decreasing as a vehicle speed increases.