Reliability Analysis Framework for Structural Redundancy in Power Semiconductors

Parallel and standby configurations can be applied to semiconductor switches to improve the reliability of power electronic converters in mission-critical applications. In this paper, the reliability models of both configurations are developed based on the Markov process. The mean time to failure (MTTF) of each configuration is derived in terms of the underlying parameters. It is demonstrated that there is a boundary condition in which both configurations have the same MTTF. This boundary condition is expressed in terms of the junction temperature of the semiconductor switch in the steady state. The temperature range in which the parallel configuration is more reliable is formulated for different types of power semiconductor switches including MOSFETs, bipolar junction transistors, SCRs, triacs, regular diodes, and Schottky diodes. Case studies are presented to determine the more reliable configuration for a laboratory-scale buck converter.