Lifetime evaluation of high energy density capacitor based experimental investigations

The high energy density capacitors (HEDC) made of metallized polypropylene film possess characteristics of high reliability and is widely used in the pulsed power systems. In order to achieve a long life characteristic, the HEDC should be designed to age gracefully with a predictable lifetime. Thus there is an urgent demand in evaluating and predicting the lifetime of the HEDC. Lifetime evaluation of HEDC prototype in design is carried out by lifetime test of the HEDC element under relatively high electric field to reduce costs and shorten time. But experimental data show that the lifetime of HED prototype is far shorter than that of the element even under the same conditions. This paper firstly analyzes the different operational factors influencing lifetime performance based on Weibull distribution, such as the voltage, temperatures and so on. Empirically derived functions of lifetime scaling about operational factors are presented. Then lifetime relationship between the HEDC element and prototype is investigated by reliability analysis. At last, the lifetime prediction model is established with the consideration of operational factors and reliability.