Patent ID: 9726725
Date: 2017-08-08
CPC Classifications: B60L,G01R,H01H,H02J,H02M,Y02T

Claim:
1. A power circuit abnormality detection method for being applicable to a power circuit and for detecting whether or not an abnormality in a power source relay exists, the power circuit which comprises: the power source relay which opens and closes a connection between a direct current power source which drives an electric motor and a motor drive circuit which includes a plurality of switching elements and which supplies a drive current to the electric motor; a smoothing condenser which is connected between a power source wire between the power source relay and the motor drive circuit and a ground wire to absorb ripples in current; a pre-charge circuit which opens and closes a connection between the direct current power source and the smoothing condenser by bypassing the power source relay to pre-charge the smoothing condenser; and a discharge circuit, including a discharge switch and a discharge resistance, which is connected between the power source wire and the ground wire in parallel to the smoothing condenser and which discharges electric charges stored in the smoothing condenser via the discharge resistance when the discharge switch is closed, the power circuit abnormality detection method comprising: detecting whether or not an open-contacts abnormality in the power source relay exists based on whether or not a charge voltage of the smoothing condenser is reduced when a predetermined period of time has elapsed since the pre-charge circuit is actively opened after both the discharge circuit and the power source relay are closed.