Patent ID: 9488686
Filing Date: 2016-11-08
CPC Classification: G01R,H02M

Claim Text:
1. A method for detecting capacitor degradation in a filter circuit, the method comprising: measuring a plurality of filter circuit branch currents associated with the filter circuit; measuring a plurality of filter circuit voltages associated with the filter circuit; computing a plurality of nominal filter circuit branch currents using the measured plurality of filter circuit voltages, a filter operating frequency, and at least one nominal capacitance value; computing a plurality of current change values representing deviations of individual measured filter circuit branch currents from a corresponding nominal filter circuit branch currents; selectively identifying a filter capacitor degradation condition in the filter circuit at least partially according to the current change values; computing root-mean-square (RMS) circuit branch current values using the measured plurality of filter circuit branch currents; computing root-mean-square (RMS) nominal filter circuit branch current values using the nominal filter circuit branch currents; and computing individual current change values as a difference between a corresponding RMS nominal filter circuit branch current value and a corresponding RMS circuit branch current value.