Patent ID: 7240761
Filing Date: 2007-07-10
Classification: B62D,H02P

Abstract:
1. An electric power steering apparatus for giving steering auxiliary power to a steering mechanism of a vehicle by driving, by introducing d-q coordinates as a rotary coordinate system having a d-axis as a direction of magnetic flux of a rotary field system of the motor and a q-axis perpendicular to the d-axis, a cylindrical permanent magnet synchronous motor which is a driving source in response to a value on the d-q coordinates of a motor driving current command value, the apparatus comprising: a d-axis current control unit which calculates a d-axis voltage command value for driving the motor by a control operation based on a d-axis component of the motor driving current command value; a q-axis current control unit which calculates a q-axis voltage command value for driving the motor by a control operation based on a q-axis component of the motor driving current command value; a coordinate transformation unit which transforms the d-axis voltage command value and the q-axis voltage command value to voltage command values in corresponding phases of the motor; and a motor driving circuit which drives the motor according to the voltage command values in the corresponding phases, wherein: control parameters of the d-axis current control unit are set on the basis of the d-axis inductance of the motor; and control parameters of the q-axis current control unit are set on the basis of the q-axis inductance of the motor.