Cumulative Degradation Modeling of Electrolytic Capacitors Considering Stress Interactions in Industrial Applications

Electrolytic capacitors are vital to the functionality of power electronic converters, with their degradation significantly affecting the safety and reliability of these devices. Capacitors typically operate under dynamic rather than constant stress levels in industrial applications. Quantifying the degradation under dynamic stress is challenging, as it requires consideration of the potential stress interactions. Although such interactions can profoundly affect degradation paths, they are often overlooked, leading to significant deviations between reliability predictions and engineering practices. This article introduces a cumulative degradation model that considers stress interactions to enhance the accuracy of degradation prediction under dynamic stress. This article not only identifies the existence of path dependence in the degradation of electrolytic capacitor parameters but also, building upon this, presents a method for integrating stress interactions with the existing foundation of degradation modeling under constant stress conditions. A path adjustment factor is introduced to enhance prediction accuracy and provide a detailed methodology for the experimental and data analysis required for its estimation. Experimental evidence confirms the practical applicability and accuracy of the method. Compared to conventional models, the proposed method considerably enhances computational accuracy.