Improved electrical model of aluminum electrolytic capacitor with anomalous diffusion for health monitoring

Aluminum electrolytic capacitors are the most cost effective solution for DC-link decoupling design in comparison to other technologies such as tantalum ones. However they are also the weakest part of static power converters. Thus, a lot of studies have been made in order to estimate their aging particularly through the Equivalent Series Resistance value (ESR) i.e. the real part of the impedance. Nowadays, aluminum electrolytic capacitor manufacturers have successfully created more sustainable high temperature components especially for automotive applications. In this context, most of electrical models found in the literature are not accurate over a broad frequency range. Furthermore, some studies show that the ESR is not always representative of the capacitor lifetime. As a consequence, an improved impedance model with the add of a diffusive element is proposed in this paper. Its purpose is to bring an efficient tool to quantify the evolution during the aging of each impedance part and not only the global real part for automotive dedicated DC-link capacitors.