Degradation mechanisms-based reliability modeling for metallized film capacitors under temperature and voltage stresses

As a key component in power electronic systems, the accurate reliability assessment of metallized film capacitors (MFC) is very critical to assure the system reliability and safety. In most operating conditions, the gradual capacitance decrease induced by dielectric film aging and the accumulation of each sudden capacitance loss by random self-healing events under elevated temperature and voltage are the main degradation mechanisms of MFC. However, most investigations tend to directly fit the MFC degradation data by some statistical means, which ignores the specific degradation mechanisms. Such treatments for degradation data often perform a lower modeling accuracy, which may also bring an obvious deviation of reliability assessment result. In this article, we design a degradation mechanisms-based reliability modeling approach for MFC under temperature and voltage stresses. The dielectric film aging is characterized by Wiener process, where the aging rate is dependent with temperature. The compound Poisson process is developed to capture the random self-healing events, where the arrival rate and each sudden capacitance loss are related to the operating voltage as well as the dielectric film aging rate. Finally, an ADT with temperature and voltage acceleration for MFC is conducted to validate the effectiveness of the proposed approach.