Patent ID: 8120296

Claim:
A motor magnetic pole position detecting device which detects a magnetic pole position of a permanent magnet motor having a magnetic saliency, the device comprising: a detection current command generation unit which generates a detection AC current command for detection of the magnetic pole position; a current detection section which detects a current flowing into the motor; a coordinate conversion unit which vector-converts the current detected by the current detection section into an excitation component and a torque component both represented by a d-q orthogonal coordinate system based on a phase angle obtained at any rotational frequency; a current control unit which generates and delivers a voltage command to current-control the motor based on the detection current command and the current converted by the coordinate conversion unit; an inductance calculation unit which calculates an inductance of the motor based on the voltage command and the current converted by the coordinate conversion unit; and a magnetic pole position detection section which calculates a frequency and phase of the inductance calculated by the inductance calculation unit, thereby converting the phase of the inductance into a magnetic pole position of the motor.