Electrical failure mode and effect analysis of a 3.3 kW onboard vehicle battery charger

Abstract

Reliability is one important aspect for further improvement of power electronic converters. The improvement trend is towards a higher power density, and a higher efficiency with a lower price. Those performance indices are normally in contradiction with the reliability. A failure mode and effect analysis (FMEA) of a 3.3 kW onboard battery charger is presented for the electrical part of the charger. The FMEA results are used to prioritize, investigate and analyze important fault cases in semiconductors, dc bus capacitors and sensors. Possible reasons of each fault, appropriate fault detection methods, possible mitigation algorithms and some design improvements are shortly presented. The calculated risk numbers confirm that the reliability of the charger is considerable improved consequently.