Patent ID: 7531982
Filing Date: 2009-05-12
Classification: B60L,H02P,Y02T

Abstract:
1. A motor drive apparatus comprising: a permanent magnet motor; and a controller that: estimates an amount of demagnetization of the permanent magnet motor based on a voltage control amount of a q axis applied under control of the permanent magnet motor using a d-q axis transformation; and limits an output of the permanent magnet motor when the estimated amount of demagnetization is larger than a predetermined value, wherein the controller (i) obtains a reference value that is the voltage control amount of only the q axis among the respective voltage control amount of the q axis and a d axis in a case where the permanent magnet motor is not demagnetized, according to a current and a motor revolution number of the permanent magnet motor being controlled, and (ii) estimates the amount of demagnetization based on a comparison between the reference value and an actual value under the control of the voltage control amount of only the q axis among the respective voltage control amount of the q axis and the d axis.