DC LINK CAPACITANCE MEASUREMENT FOR ELECTRIC VEHICLE DRIVETRAIN

摘要

In order to detect deterioration of a DC link capacitor between a DC source and an inverter load in an electric propulsion vehicle, capacitance of the link capacitor must be accurately measured during in-service use. A charge is established on the link capacitor. The capacitor is isolated from the source and the inverter load. A constant current circuit is activated to discharge the capacitor. A first voltage is measured across the capacitor at a first time during the discharging. A second voltage is measured across the capacitor at a second time during the discharging. A discharge current flowing from the capacitor is measured during the discharging. The capacitance is calculated in response to the discharge current multiplied by a ratio of a difference between the second and first times to a difference between the first and second voltages. The calculated capacitance is monitored for a decline indicative of a failure.

主权项

1. A method of detecting deterioration of a DC link capacitor between a DC source and an inverter load, comprising the steps of:
establishing a charge on the link capacitor; isolating the link capacitor from the source and the inverter load; activating a constant current circuit to discharge the link capacitor; measuring a first voltage across the link capacitor at a first time during the discharging; measuring a second voltage across the link capacitor at a second time during the discharging; measuring a discharge current flowing from the link capacitor during the discharging; calculating the capacitance in response to the discharge current multiplied by a ratio of a difference between the second and first times to a difference between the first and second voltages; and monitoring the calculated capacitance for a decline indicative of a failure.