Fractional techniques to characterize non-solid aluminum electrolytic capacitors for power electronic applications

Non-solid aluminum electrolytic capacitors are one type of reliability-critical components, and they are widely adopted in power electronic converters. The capacitance and equivalent series resistance of these components have significant effects on the performance and reliability of power electronic systems. In this work, by exploring the electrochemical principles of aluminum electrolytic capacitors, the fractional-order (FO) characteristics of the capacitors are revealed, according to which the frequency-dependent parameters of this kind of components are expressed by FO models, while the parameters of the models are estimated by a multi-objective optimization algorithm. Under the same conditions such as the number of arguments supplied and optimization algorithm, the proposed models perform better. Additionally, to show further applications of fractional techniques, a brief example on the output ripple analysis of DC–DC converters is offered, in which one of the proposed FO models of the capacitor is adopted. The effectiveness and superiority of the techniques for predicting the states of the converters are confirmed by comparison with traditional models.