Comparison of counting algorithms and empiric lifetime models to analyze the load-profile of an IGBT power module in a hybrid car

In the recent years various models and counting algorithms to estimate the lifetime of an IGBT power module were publicized. Primarily they differ in the number of parameters used to specify a temperature cycle. Generally a temperature cycle is defined with its amplitude, its absolute temperature and its heating time. In this paper the impact of these parameters onto the lifetime calculation is investigated by analyzing the load-profile of a hybrid car with different empiric lifetime models and cycle counting algorithms. The considered load-profile incorporates active and passive temperature cycles over a time span of one year. It is found, that a cycle specific absolute temperature and also a cycle specific heating time have major influence on the estimated lifetime. Moreover passive temperature cycles contribute noticeable to the module lifetime so that a cycle counting algorithm has to be capable of extracting and parameterizing them correctly. The comparison of established counting algorithms shows, that an accurate cycle extraction demands the usage of a Rainflow algorithm.