Application based modified reliability tests and their physical correlation with lifetime assessment models

摘要

Lifetime assessment models for IGBT based power modules used in electric drive applications are extremely useful for preliminary dimensioning and selection of the associated system. Failure estimation is usually modeled on the basis of data from multiple sets of characteristic stress tests like power cycling (PC), thermal cycling (TC) and thermal shock (TST). During real application environment the overall load/stress is usually a combination of these tests with varied durations. Consequently fundamental understanding of the mapping between reliability tests and field application is extremely important. In this paper we have verified the necessity of different parameters used in lifetime assessment models and their limitations. Finite element analysis and analytical models were used to understand such models using laboratory assessable simplified drive cycle stress tests.