US 2016/0258993 A1 · 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.

Claims10

Dependent claims

An electrified vehicle comprising:

first and second DC buses connectable to a DC power source;
a chassis ground distributed within the vehicle;
a DC bus leakage detector circuit having a detector switch and a detector resistor in series between the first bus and the chassis ground wherein a voltage measured across the detector resistor is proportional to a leakage resistance between the second bus and the chassis ground;
an inverter having a plurality of phase legs, each phase leg having first and second phase switches coupled between the first and second buses;
an AC traction motor having a plurality of phases coupled to the phase legs;
and
an inverter control circuit coupled to the leakage detector circuit and to the phase legs, wherein the control circuit is adapted to a) receive data messages according to a predetermined latency period from the detector circuit identifying a measured leakage resistance, b) detect switching events during which a phase switch is closed for a duration greater than the latency period, and c) indicate an electrical short of the motor to the chassis ground if the measured leakage resistance in a data message received during a detected switching event is less than a predetermined threshold.

4 more elements

A method of detecting electrical shorts of an AC traction motor in an electrified vehicle, comprising the steps of:

controllably switching a plurality of phase legs in an inverter, wherein each phase leg has first and second phase switches coupled between first and second DC buses, wherein an AC traction motor has a plurality of phases coupled to the phase legs, wherein the first and second buses are connected to a DC power source, and wherein switching of the phase legs drives rotation of the motor;
repeatedly sampling a voltage across a detector resistor of a DC bus leakage detector circuit having a detector switch in series with the detector resistor between the first bus and a chassis ground, wherein the voltage is proportional to a leakage resistance between the second bus and the chassis ground, wherein the chassis ground is distributed within the vehicle, and wherein a plurality of sampled voltages are generated at a predetermined latency;
detecting the occurrence of switching events during which a phase switch is closed for a duration greater than the latency period;
in response to a detected switching event, comparing a leakage resistance for a respective sampled voltage with a predetermined threshold and indicating an electrical short of the motor to chassis ground if the leakage resistance is less than the predetermined threshold.

1 more element

Dependencies are inferred from the claim text.

Ac traction motor fault detection using dc bus leakage hardware

Life of this patent

Ac traction motor fault detection using dc bus leakage hardware

Life of this patent

Abstract

Claims10