Patent ID: 8972113
Filing Date: 2015-03-03
Classification: B62D

Abstract:
1. An electric power steering system, comprising: an electric steering assist motor that applies an assist force to a steering mechanism; a steering angle detector that detects a steering angle of a steering wheel; a target steering torque setting unit that sets a target steering torque of the steering wheel according to a detection result of the steering angle detecting means detector; an actual steering torque detector that detects an actual steering torque applied to the steering wheel by a vehicle operator; a steering torque difference computing unit that computes a difference between the target steering torque and the actual steering torque as a steering torque difference; an effective steering torque difference determination unit that determines and produces an effective steering torque difference, such that the effective steering torque difference is given as zero when the actual steering torque is greater than the target steering torque in a steering angle advancing direction by more than a prescribed value and otherwise the effective steering torque difference is given as the steering torque difference computed by the steering torque difference computing unit; a target drive current setting unit that sets a target drive current according to the effective steering torque difference; and a motor drive circuit that drives the steering assist motor according to the target drive current.