From vehicle drive cycle to reliability testing of Power Modules for hybrid vehicle inverter

In hybrid electrical vehicles (HEV) the battery, motor and inverter are the core elements of the electric drive train. In the inverter power semiconductors, usually packaged in a module, are used. To qualify such power modules for the use in HEV amongst others Power cycling and Thermal cycling tests have to be performed. These tests mainly ensure the reliability of the module regarding thermal stress conditions over the vehicle lifetime. This paper discusses the requirements on such power semiconductor modules in terms of reliability, and lifetime in HEV. A general approach is presented to evaluate duty cycles and thermal conditions and estimate required test cycles. Based on a water cooled Power module this approach is performed and test cycles are calculated.