Motor-driven power steering apparatus

A motor-driven power steering apparatus driving an electric motor by a motor driving means, converting a rotation of the electric motor into a linear stroke of a rack shaft by a power transmission mechanism, and steering and assisting a wheel coupled to the rack shaft, comprising:

• a reference output characteristic memory which stores a reference output characteristic expressing a corresponding relation to be targeted between a driving current of the electric motor and an output torque corresponding to the driving current;
• a correction coefficient computing circuit which calculates a ratio TO/TM between an output torque TM of the electric motor actually detected at a time of actually applying a predetermined driving current IM to the electric motor, and an output torque value TO corresponding to the driving current IM in the reference output characteristic as an output correction coefficient;
• and
• a current control computing means which calculates a corrected current control signal by multiplying the current control signal of the electric motor computed on the basis of a steered condition of a vehicle by the output correction coefficient, and outputs the drive control signal based on the corrected current control signal to the motor driving means.