A new deterioration model for electrolytic capacitors in direct current to direct current (DC-DC) converters

The output filter aluminum electrolytic capacitor is one of the key components that determine the life of direct current to direct current (DC-DC) converters, and so, establishing a deterioration model for the electrolytic capacitor is the basis for analyzing the impact on the converters’ performances. Generally, the main parasitic parameters that indicate the electrolytic capacitor deterioration such as capacitance (C) and equivalent series resistance (ESR) are separately considered when building the model. However, taking the Buck-Boost converter as the research object, this paper discussed the impact of the two kinds of parasitic parameters simultaneous degradation on the DC-DC converters. Firstly, according to the electrolytic capacitor failure mechanisms, a joint degradation model for the C and ESR-a new deterioration model for the electrolytic capacitor was established. On the basis, this paper discussed the impact on the system pole-zero of the parasitic parameters degradation, analyzed the electrolytic capacitor deterioration on how to affect the performances of the DC-DC converter, and verified the theoretical analysis results through the software simulation experiments. The new model provides the theoretical basis for monitoring the health state of DC-DC converters.