Patent ID: 8878477

Claim:
An electric motor driving apparatus having a failure detection circuit, the electric motor driving apparatus comprising: a bridge circuit which drives an electric motor and is composed of high-potential-side arms and low-potential-side arms; a PWM control circuit which generates a voltage instruction for driving the electric motor; a PWM signal generation circuit which generates a PWM signal from the voltage instruction; a DC current detection circuit which detects DC current on a DC side of the bridge circuit; a phase current calculation circuit which calculates output phase current of the bridge circuit, based on the DC current and the PWM signal; and a failure detection circuit which detects failure of the DC current detection circuit, wherein the failure detection circuit determines failure of the DC current detection circuit from the DC current detected values in a zero voltage vector period in which the high-potential-side arms of the bridge circuit are all ON and in a zero voltage vector period in which the low-potential-side arms of the bridge circuit are all ON.