power conversion system and method for detecting filter capacitor degradation in an active front end motor drive

摘要

methods and apparatus for detecting active front end filter capacitor degradation. apparatus and methods are provided for detecting degradation of triangle connected filter capacitors in an active front end power converter (afe), in which triangle circuit capacitor leg currents are calculated based on measured branch circuit currents. , and filter capacitor impedance values are computed based on the calculated leg currents as well as the measured line-to-line voltages and corresponding phase angles for comparison with one or more thresholds to selectively detect the degradation of the capacitors. filter. Additional apparatus and methods are provided for detecting the degradation of star connected filter capacitors by computing fundamental frequency rms impedance values such as rms capacitor voltage ratios and rms circuit branching currents, and comparing the calculated rms impedance values. with one or more thresholds.