A Study of Degradation Modeling and Lifetime Estimation of Capacitors

Abstract

The degradation of capacitors under accelerated stress conditions occurs in a monotonic and non-linear fashion. Several efforts have been made to model the degradation behavior of capacitor considering either physics-of-failure models or statistical models and subsequently estimate its reliability and lifetime parameters. But most of these models fail to reflect the physical properties of the degradation path, which varies according to several intrinsic and extrinsic factors. These factors introduce random and temporal uncertainty among the population of capacitors. The Gamma stochastic process can model both type of uncertainties among the population of capacitors. In this thesis, we model the capacitor degradation by non-homogeneous Gamma stochastic process in which both the model parameters (shape and scale) are dependent on stress variables. The model parameters are estimated using the maximum likelihood estimation approach. Two case studies have been presented and the life of capacitors has been estimated using Gamma process model.