Lifetime investigation and prediction of metallized polypropylene film capacitors

Metallized polypropylene film capacitors (MPPFCs) possess characteristics of high reliabilities and high energy densities, so they are widely used in the pulse power systems. MPPFC prototypes with high voltage and large capacitance are composed of a number of cylindrical MPPFC elements connecting in series or in parallel. The experimental data show that the lifetime of MPPFC prototypes is far shorter than that of MPPFC elements under the same voltage stress. This paper analyses operational factors that affect influence the lifetime of MPPFCs, and predicts the lifetime under various operational factors based on the experimental results. The relationship between MPPFC elements and MPPFC prototypes in terms of lifetime is presented with a reliability analysis of the Weibull distribution, and is validated through experiments. Finally this paper presents a lifetime prediction model. The results suggest that the predicted data could match well with experimental results. This paper is devoted more to the lifetime analysis under various operational factors and less to theoretical physical analysis.