A motor control apparatus having a function of calculating the amount of cogging torque compensation

摘要

A motor control device (500) for controlling a motor used in a machine tool, comprising: a torque command monitoring unit (530) configured to monitor a torque command when the motor is caused to operate at a constant speed; an approximation computation unit (540) configured to approximate an approximate component of the torque command from the torque command monitored by the torque command monitor (530) over an interval equal to an integer multiple of a detent torque period of the engine, the interval being determined by a motor position monitor (570). based on the output of an encoder (592) can be determined; a second torque command calculation unit (550) configured to calculate a second torque command by subtracting the approximate component of the torque command calculated by the approximate calculation unit (540) from the torque command monitored by the torque command monitoring unit (530); a second torque command frequency analyzer (560) configured to extract frequency components at every integer multiple of a fundamental frequency of the cogging torque by performing a frequency analysis of the second torque command calculated by the second torque command calculating unit (550); and a cogging torque amount calculating unit (504) configured to calculate the amount of cogging torque compensation from the amplitude and the phase of the frequency components extracted by the second torque command frequency analyzing unit (560).