Simple Energy-Based Method for Estimating the Equivalent Circuit Parameters of Electrolytic Capacitors

A simple method based on the energy conservation principle is proposed for the estimation of the equivalent circuit parameters of electrolytic capacitors. A series R-L-C circuit model is chosen to describe the real behaviour of these components, which are increasingly used in power converters to realize the DC-bus and filter the generated electromagnetic interference (EMI). The proposed method allows electrolytic capacitors to be characterised in any operating condition and requires only the measurement of the voltage and current waveforms of the capacitor under test.