Motor drive device, electric oil pump, and method for detecting failure of motor drive device

Abstract

Provided is a motor drive device including a motor having a rotor and a stator, an inverter electrically connected to the motor, and a control device for controlling the inverter. The control device includes: an impedance observer that estimates at least an amount of variation in impedance of the motor on the basis of a voltage command value, a current command value, and an actual current flowing between the inverter and the motor; a comparator that calculates a difference between the current command value and the actual current flowing between the inverter and the motor; and a failure detection unit that outputs a failure flag when the amount of variation in impedance exceeds or falls below a predetermined threshold, or when the difference calculated by the comparator exceeds or falls below a predetermined threshold.

Dependencies are inferred from the claim text.