Stress-lifetime joint distribution model for performance degradation failure

The high energy density self-healing metallized film pulse capacitor has been applied to all kinds of laser facilities for their power conditioning systems under several stress levels, such as 23kV, 30kV and 35kV, whose reliability performance and maintenance costs are affected by the reliability of capacitors. Due to the costs and time restriction, how to assess the reliability of highly reliable capacitors under a certain stress level as soon as possible becomes a challenge. Accelerated degradation test provides a way to predict its lifetime and reliability effectively. A model called stress-lifetime joint distribution model and an analysis method based on accelerated degradation data of metallized film pulse capacitors are described in this paper. Also described is a method for estimating the distribution of time to failure. The estimators of the unknown parameters in the model are given respectively. Both the failure probability density function (pdf) and the cumulative distribution function (cdf) can be presented by the model. Based on these estimators and the pdf/cdf, the reliability model of metallized film pulse capacitors is obtained. According to the reliability model, the probability of capacitors under stress 23kV that survive to 20000 shots is presented. Then the Kolmogorov-Smirnov test is performed to validate the model. The result shows that the reliability of capacitors under a certain stress level can be assessed as soon as possible by using the model, once the estimators of the unknown parameters in the model are obtained.