DC-link electrolyte capacitor lifetime analysis for a PV boost converter

A lifetime analysis was performed on the DC-link capacitor of a photovoltaic power-processing system composed of a boost converter in the first stage. It was investigated how the switching frequency and ripple current design choice affect the capacitor lifetime. Through an electro-thermal modeling, the capacitor operating condition was obtained for various levels of power processing, based on a real photovoltaic mission profile built for ten years period of weather data. The lifetime of three different designs of electrolyte capacitor bank was analyzed and discussed. Analyzed results showed that the increase of the converter's current ripple diminishes much the of capacitor's lifetime. A discussion is presented about the tradeoff between choosing capacitors with low equivalent series resistance and increasing the number of capacitors on the DC-link.