Ac traction motor fault detection using dc bus leakage hardware

Abstract

An electrified vehicle has first and second DC buses and a chassis ground. A leakage detector has a detector switch and detector resistor in series between the first bus and chassis ground. A voltage measured across the detector resistor is proportional to a leakage resistance between the second bus and chassis. An inverter has a plurality of phase legs, each having first and second phase switches coupled between the buses. An AC traction motor has phases coupled to the phase legs. An inverter control circuit receives data messages having a predetermined latency period from the detector identifying a measured leakage resistance. Switching events are detected during which a phase switch is closed for a duration greater than the latency period. An electrical short is indicated if the measured leakage resistance in a data message received during a detected switching event is less than a predetermined threshold.