Patent ID: 8508160

Claim:
A device that performs position control of a servo motor by feedback control, the servo motor position control device comprising: a position controller that derives and outputs a velocity instruction signal corresponding to a target velocity of the servo motor by proportional control from a position deviation in which a position signal corresponding to an actual position of the servo motor is subtracted from a position instruction signal corresponding to a target position in driving the servo motor; a velocity controller that derives and outputs a current instruction signal corresponding to a current value to be applied to the servo motor by proportional-integral control from a velocity deviation in which a velocity signal corresponding to an actual velocity of the servo motor is subtracted from the velocity instruction signal; and a q-axis current controller that derives and outputs a q-axis voltage instruction signal corresponding to a voltage applied to a q-axis of the servo motor by proportional-integral control from a current deviation in which a q-axis current signal corresponding to a current value passed actually with respect to the q-axis of the servo motor is subtracted from the current instruction signal, wherein integral control in the q-axis current controller is stopped when the servo motor reaches the target position to eliminate the position deviation.