MOTOR-DRIVEN POWER STEERING DEVICE

摘要

PROBLEM TO BE SOLVED: To enable a device to supply stabilized steering assist torque from a motor even in case of slowly performing steering operation, also in the case such as steering a steering system is steered to a maximum steering angle position, prevent an excessive current from being supplied to the motor. SOLUTION: In a steering speed arithmetic part 22, based on a motor current IM and motor voltage EM, a rotational speed of a motor is calculated, an arithmetic result is output as a steering speed VM. In an overload preventing control part 51, the motor current IM corresponding to steering force acting in a steering system is a first prescribed value or more, and when the steering speed VM is detected to be a prescribed value or less, for instance, a 0.5 multiplication coefficient is supplied to a multiplier 52, a correction target current ITH supplied to a motor drive part 24 is decreased. In the overload preventing control part 51, when the electric motor current IM is a second prescribed value or more smaller than the first prescribed value, and when a condition of the steering speed VM in a prescribed value or less is continued for a prescribed time, a current supplied to the motor drive part 24 is decreased.