Position controller of motor

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, the integral control system multiplying an operand in the control system by a speed proportional gain to produce an output;
• a proportional control system for producing a command by multiplying a difference, between the speed indicated by the speed command and the speed of the motor, by the speed proportional gain;
• and
• an addition means for adding an output of the integral control system and an output of the proportional control system.