Reliability Assessment of Switching Mode Power Supply considering Capacitor Degradation

The reliability of switching mode power supply (SMPS) has an extremely important impact on the safe operation of power electronic systems. Most of faults or failures are caused by the degradation of its key components. However, current research has not made sufficient use of component-level degradation information yet. This paper proposes a reliability assessment method for SMPS based on the film capacitor degradation. Firstly, the working principle of the SMPS is analyzed. The capacitance of the film capacitor is selected as a sensitive parameter affecting the output voltage ripple of the SMPS using multi-parameter sensitivity analysis and a Saber simulation model. Then, by analyzing the failure mechanism of the film capacitor, an accelerated degradation test (ADT) of the film capacitor was carried out using both voltage and temperature as accelerated stresses. Subsequently, the test data of the film capacitors is substituted into the SMPS Saber simulation model to obtain the degradation trajectory of the output voltage ripple. Finally, a random effect Wiener process, which considers the individual variability of the samples, is used to establish the degradation model of the output voltage ripple. The reliability of the SMPS is assessed. And this reliability assessment framework may also be available for other electronic systems.