Patent ID: 8013564

Claim:
A multi-phase AC motor driving device comprising: an inverter circuit including pairs of upper and lower arms provided in association with respective phases of a motor, the inverter circuit being constituted such that the respective arm has a switching device for driving a multi-phase AC motor and a reflux diode connected in parallel to the device, and a voltage for driving the motor is extracted from a connection point of the upper and lower arms of the respective phases; a current detecting section, arranged in the lower arm of the respective phase of the inverter circuit, for detecting a phase current of the motor; a control section for controlling ON/OFF operation of each switching device of the inverter circuit; and a first determining section for determining occurrence of a failure based on a current value detected by the current detecting section; the multi-phase AC motor driving device further comprising: a second determining section for determining whether or not there is a possibility that current flows through the current detecting section due to an induction voltage generated in the multi-phase AC motor; wherein the first determining section does not make a determination on the occurrence of the failure when the second determining section determines that there is a possibility that current flows and when all the switching devices of the lower arms of the respective phases are turned OFF; and the first determining section makes a determination on the occurrence of the failure when the second determining section determines that there is no possibility that current flows and when all the switching devices of the lower arms of the respective phases are turned OFF.