Reliability Modeling of Multistate Degraded Power Electronic Converters With Simultaneous Exposure to Dependent Competing Failure Processes

Depending on the application in which power electronic converters (PECs) are deployed, failure processes may endanger the desirable performance of PECs. This paper offers holistic insights on reliability modeling of PECs considering dependencies in two simultaneous failure processes, namely gradual wearing-out degradation and vibration sudden degradation. While sudden and gradual degradation processes may individually affect the useful lifetime of PECs, their mutual interdependencies could significantly accelerate the aging mechanisms. A new analytical model for reliability assessment of PECs is proposed that can capture such mutual interdependence of simultaneous failure processes. The proposed analytics are applied to a DC-DC boost converter in a hybrid electric vehicle exposed to both gradual wearing-out and vibration sudden degradations. Monte Carlo-aided numerical results will demonstrate how critical it is to take into account the mutual interdependence in the failure processes when assessing the reliability performance of PECs, failure to do which may lead to inaccurate useful lifetime estimations and the corresponding maintenance and replacement decisions.