Patent ID: 6504336
Filing Date: 2003-01-07
Classification: B62D

Abstract:
A motor controller for an electric power steering system which performs a steering assist operation by applying a torque generated by an electric motor to a steering mechanism, the motor controller comprising:a current command value setting circuit for setting a current command value indicative of an electric current to be applied to the electric motor; a d-q command value setting circuit for setting a d-axis current command value and a q-axis current command value in a d-q coordinate system on the basis of the current command value set by the current command value setting circuit; a voltage controlling circuit for controlling a voltage to be applied to the electric motor on the basis of the d-axis current command value and the q-axis current command value set by the d-q command value setting circuit; a current detecting circuit for detecting three-phase alternating currents actually flowing through the electric motor; and a three-phase AC/d-q coordinate transformation circuit for converting the three-phase alternating currents detected by the current detecting circuit into a d-axis current and a q-axis current in the d-q coordinate system; wherein the voltage controlling circuit feedback-controls the voltage applied to the electric motor on the basis of the d-axis current command value and the q-axis current command value set by the d-q command value setting circuit, and the d-axis current and the q-axis current outputted from the three-phase AC/d-q coordinate transformation circuit.