Patent ID: 8395339
Filing Date: 2013-03-12
Classification: H02P

Abstract:
1. A motor control device that controls an AC motor in a vector space with a d-axis, which is in a direction of a magnetic field generated by a permanent magnet disposed in a rotor of the AC motor, and a q-axis orthogonal to the d-axis, comprising: a current control block that computes voltage commands in the vector space on the basis of current commands in the vector space, and feedback currents that have detection values of currents, which flow into respective stator coils of the AC motor, coordinate-transformed into the vector space and fed back; an observation command impress block that impresses a predetermined high-frequency component as an observation command on the current command on a d-axis or the voltage command on the d-axis, and positively and negatively symmetrically impresses thereon a DC bias component, which takes on a certain value over a predetermined period and has a magnitude that causes the motor to be magnetically saturated, as the observation command; and a polarity identification section that identifies the polarity of a magnetic pole of the permanent magnet on the basis of a relationship of large and small magnitudes between a first amplitude, which is attained during a period during which the DC bias component takes on a positive certain value, among amplitudes of the high-frequency component contained in a d-axis response voltage computed based on the feedback current respondent to the observation command, and a second amplitude attained during a period during which the DC bias component takes on a negative certain value.