Experimental Validation of Capacitor Damage Accumulation in Varying Operating Conditions

Capacitors and semiconductor devices are reliability critical components in power electronic converters, therefore understanding the failure mechanisms and predicting the expected lifetime is of interest. The lifetime analysis of capacitors under dynamic operation conditions is based on their accumulated damage, i.e., lifetime consumption under each stress level. A linear damage accumulation model, i.e., Miner’s rule, is widely used. However, there is a lack of comprehensive experimental validation of damage accumulation models in the literature. Through accelerated capacitor tests under different temperature and humidity conditions the accuracy of linear damage accumulation is validated. The results indicate that the decrease of capacitance can be approximated by the summation of capacitance drop in different stress profiles, however the increase of ESR depends on the stress level chronology. Thus, a linear accumulation model will not correctly approximate the accumulated damage during a specific mission profile.