Patent ID: 7224141

Claim:
A motor position controller comprising: a position detection unit for detecting a position of a motor to be controlled; a speed calculation unit for calculating a speed of the motor; a position control unit for performing a position control by outputting a speed command so that the motor position fed back from the position detection unit is consistent with a position indicated by a position command; a speed control unit for performing a speed control based on a proportional-integral control by outputting a torque command so that the speed fed back from the speed calculation unit is consistent with the speed indicated by the speed command; and a torque control unit for performing a torque control based on the torque command; wherein the speed control unit comprises: a delay compensation low-pass filter in the speed control unit having a transfer function corresponding to a delay of a speed control system; an integral control system including a speed integrator, the speed integrator being adapted to integrate a speed difference between a speed indicated by a delay speed command and the speed of the motor, the delay speed command being obtained by inputting the speed command into the delay compensation low-pass filter in the speed control unit; a proportional control system for outputting a command proportional to a difference between the speed indicated by the speed command and the speed of the motor; an addition means for adding an output of the integral control system and an output of the proportional control system; and a multiplication means for multiplying an output of the addition means by a speed proportional gain to produce the torque command.