Fault detection in AC traction motors using DC bus leakage current hardware

摘要

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