Patent ID: 7511448

Claim:
A motor control device comprising: a velocity calculation unit that calculates an actual velocity from a detected position that is a position of a motor or of a load connected to the motor, the detected position being detected by a detector; a velocity control unit that performs velocity control to cause the actual velocity to follow a velocity command and outputs a q-axis current command; a uvw/dq coordinate converting unit that receives a three-phase current detected in an inverter, performs coordinate conversion from a uvw three-phase coordinate system at rest into a dq synchronous rotation coordinate system, and outputs a d-axis current detection value and a q-axis current detection value; a current control unit that receives a d-axis current command, the q-axis current command, the d-axis current detection value, and the q-axis current detection value, performs current control so that a dq-axis current detection value coincides with a dq-axis current command, and outputs a d-axis voltage command and a q-axis voltage command; a dq/uvw coordinate converting unit that receives the d-axis voltage command, the q-axis voltage command, and the detected position, performs coordinate conversion from the dq synchronous rotation coordinate system into the uvw three-phase coordinate system at rest, and outputs a three-phase voltage command; an inverter that receives the three-phase voltage command, applies an actual three-phase voltage to the motor, and drives the motor at a variable velocity; a superimposed signal generating unit that outputs a superimposed signal of a repetitive waveform, such as a triangular wave or a sine wave; a d-axis current command generating unit that adds the superimposed signal generated by the superimposed signal generating unit to a d-axis current command nominal value and outputs the d-axis current command; and an axial misalignment detecting unit that receives the d-axis current command and the q-axis current command output from the velocity control unit and outputs an axial misalignment angle estimation value.