Lifetime Prediction of Metallized Film Capacitors Based on Capacitance Loss

Metallized film capacitors possess characteristics of self-healing, high reliability, and long lifetime. Lifetime and reliability of capacitors are the key factors that ensure the stability of the electromagnetic launch system. In the capacitor lifetime test, it is a time-consuming work to get enough capacitance loss (CL) data to characterize the performance of the capacitor. Thus, it is necessary to analyze experimental data by effective lifetime prediction model (LPM). This paper first introduces the characteristics of CL in lifetime test. Then, it introduces traditional LPMs such as least square method (LSM) and Weibull distribution model (WDM). LSM is only appropriate when CL is uniform and steady, and it cannot analyze the lifetime reliability. WDM works best when large quantities of lifetime experiment data are acquired. In this paper, some new LPMs such as Birnbaum-Saunders distribution model and Poisson distribution model are introduced. New LPMs fully use CL in each shot, and it could faithfully reflect the work conditions of the capacitor. The analysis methods and steps of each model are put forward. In order to fully introduce these models, lifetime calculations are carried out based on the aforementioned LPMs.