Patent ID: 8310187

Claim:
A motor drive device comprising: a drive unit for driving a motor based on an ON/OF operation of a switching element by a PWM (Pulse Width Modulation) signal; a current detection unit for detecting a current value of current flowing to the drive unit at a predetermined current detection timing, and obtaining an actual measurement current value of current flowing to each of phases of the motor; an application voltage generation unit for obtaining an application voltage value of the motor based on the actual measurement current value obtained by the current detection unit and a current command value indicating a target value of the current to be flowed to the motor inputted from outside; a PWM signal generation unit for generating the PWM signal and outputting to the drive unit based on the application voltage value obtained by the application voltage generation unit; and an abnormality detection unit for detecting abnormality from the application voltage value of each of the phases and the actual measurement current value of each of the phases; wherein the abnormality detection unit includes: an application voltage value storage portion for storing the application voltage value of each of the phases obtained by the application voltage generation unit for every current detection timing in the current detection unit, a corrected voltage value generation portion for obtaining a corrected voltage value, in which the application voltage value is corrected, based on the application voltage value stored in the application voltage value storage portion, a current detection cycle which is a time necessary from the current detection timing of the previous time to the current detection timing of this time in the current detection unit, and a time necessary until the voltage of the application voltage value obtained by the application voltage generation unit is applied to the motor from when the current detection is performed at a certain current detection timing, a current-voltage conversion portion for converting the actual measurement current value obtained by the current detection unit to the actual measurement voltage value, and an abnormality determination portion for determining abnormality by comparing the corrected voltage value obtained by the corrected voltage value generation portion and the actual measurement voltage value obtained by the current-voltage conversion portion.