Safe Failure Modelling and Lifetime Prediction of DC Film Capacitors Using Standards-Compliant Reliability Analysis

Abstract:
The pursuit of compact, high-efficiency power converters has accelerated interest in DC-link film capacitors that offer enhanced reliability and energy density. despite the availability of both physics-of-failure (PoF) models and international qualification standards, these tools are often applied independently, limiting their usefulness in real-world reliability assurance. This work proposes a unified validation framework for metallized polypropylene (MKP) DC-link capacitors that integrates process-level quality control, standards-based testing, and predictive modeling. A 21,000 muF, 750 VDC prototype capacitor featuring segmented heavy-edge metallization and vacuum impregnation was produced and tested according to IEC 61071 qualification procedures, including surge, endurance, and thermal stability evaluations. Empirical results were used to calibrate a multistress PoF lifetime model combining electrical, thermal, and humidity acceleration factors. The calibrated model estimates a B10 lifetime greater than 180,000 hours, aligning closely— within 5%—with measured degradation trends. The proposed approach establishes a practical route to validate and forecast capacitor reliability, bridging the gap between standardized qualification and lifetime prediction for high-reliability applications such as traction systems and smart grids.