Electromotive power steering controller

An electromotive power steering controller for performing power-assisted steering by applying to a steering mechanism torque generated by a motor, the controller comprising:

• a d-q command value setting unit for determining, for current to be applied to the motor, d-axis and q-axis current command values in a d-q coordinate system;
• a current detector for detecting a phase current actually flowing in the motor;
• a three-phase/d-q coordinate transformer for transforming each of phase-current detection values detected by the current detector into a d-axis current detection value and a q-axis current detection value in the d-q coordinate system;
• a voltage controller for controlling a voltage applied to the motor, based on the d-axis current command value and the q-axis current command value determined by the d-q command value setting unit, and on the d-axis current detection value and the q-axis current detection value outputted from the three-phase/d-q coordinate transformer;
• and
• a malfunction determining unit for determining that malfunction has occurred in the control system if at least one of the phase-current detection values is out of a permissible range according to first predetermination.