Patent ID: 9470739
Filing Date: 2016-10-18
CPC Classification: B60L,G01R,Y02T

Claim Text:
1. A method of detecting deterioration of a DC link capacitor between a DC source and an inverter load, comprising the steps of: establishing an initial 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 at a constant current; 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, wherein the initial charge and a difference between the second and first times are selected so that the link capacitor is not fully discharged by the second time; 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 the 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.