Passive high-voltage DC bus discharge circuit for a vehicle

摘要

A vehicle includes a rechargeable energy storage system (RESS), an electric traction motor, a traction power inverter module (TPIM), a high-voltage direct current (HVDC) bus that electrically connects the RESS to the TPIM, a passive discharge circuit connected across the positive and negative rails of the bus, and a microprocessor. The circuit includes a semiconductor switch. The microprocessor provides an output signal at a first voltage level that opens the switch and prevents discharge of the HVDC bus when the microprocessor is operating normally, and at a default second voltage level that closes the switch in the presence of a predetermined vehicle condition to thereby discharge the HVDC bus. An optocoupler may receive the output signal, and a zener diode may be in electrical parallel with an output side of the optocoupler. The switch may be an insulated gate bipolar transistor or a thyristor in different embodiments.

主权项

1. A vehicle comprising:
a rechargeable energy storage system (RESS); an electric traction motor having an output shaft, wherein the traction motor draws energy from the RESS and outputs drive torque to the output shaft to propel the vehicle; a high-voltage component; a high-voltage direct current (HVDC) bus that electrically connects the RESS to the high-voltage component, wherein the HVDC bus includes a positive rail and a negative rail; a passive discharge circuit that is electrically connected across the positive and negative rails, wherein the passive discharge circuit includes:
an optocoupler having a photodiode;a zener diode in electrical parallel with the optocoupler;a diode having an anode and a cathode;a discharge resistor connected to the positive rail and to the cathode of the diode;a semiconductor switch with a switching gate, a collector, and an emitter, wherein the discharge resistor is connected to the positive rail and to the collector of the semiconductor switch, the emitter is connected to the anode of the diode, and the cathode of the diode is connected between the collector and the discharge resistor; and a microprocessor in electrical communication with the passive discharge circuit wherein the photodiode of the optocoupler is connected between the processor and electrical ground; wherein the microprocessor provides an output signal at a first voltage level of 5VDC to the optocoupler that opens the semiconductor switch and prevents discharge of the HVDC bus across the discharge resistor when the microprocessor is operating normally, and at a default second voltage level of 0VDC to the optocoupler that closes the semiconductor switch, which is held closed via the zener diode, to activate the passive discharge circuit only in the presence of a predetermined vehicle condition to thereby passively discharge the HVDC bus across the discharge resistor, and wherein the predetermined vehicle condition is a condition in which a 12VDC auxiliary voltage is temporarily lost aboard the vehicle.