CONTROLLER FOR ELECTRIC POWER STEERING SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a controller for an electric power steering system that avoids a sudden variation in steering force just about an output limit of a motor when a characteristic with a high assist gain is adopted as in hydraulic power steering. SOLUTION: The controller for an electric power steering system controls the motor for applying steering assist force to a steering mechanism, on the basis of a current control value computed from a steering assist command value computed by an arithmetic means on the basis of steering torque generated on a steering shaft, and from a current value of the motor. A function is provided to detect that the motor approaches an output limit from a motor current, a motor terminal voltage and a motor angular velocity, and to multiply the steering assist command value by a coefficient gradually decreasing with approach to the output limit. COPYRIGHT: (C)2003,JPO