A reliability prediction method considering degradation self-acceleration effect in DC-link electrolytic capacitor

The reliability of DC-link electrolytic capacitors is crucial to ensure the quality of power supply systems. The degradation of capacitor parameters may lead to a higher temperature and thus accelerate degradation as a self-accelerating effect. In this article, an improved reliability prediction method for DC-link electrolytic capacitors is proposed, as existing methods have not adequately accounted for the self-acceleration effect. The degradation under dynamic stress is obtained by cumulative computations and the stress is updated according to the degraded parameters. The degradation models are converted into degradation rate models to overcome the computational challenges associated with small-step iterations that may make traditional methods unaffordable. The proposed method for developing the degradation rate model is widely applicable and achieves satisfactory accuracy. To demonstrate the practicality of the proposed method, a case study of a boost motor drive system is presented. The appropriate iteration step can be determined by comparing the results of the lifetime distributions obtained using different iteration steps. Degradation paths considering self-acceleration effects can be obtained, enabling more precise system quality analysis and reliability prediction.