An impedance-based approach to predict the state-of-charge for carbon-based supercapacitors

The impedance behavior of supercapacitors is not only a key issue for the parameterize modeling of the supercapacitor, but also an important factor for the design processes of an intelligent energy-management system which monitors the state of the supercapacitor and predicts its performance. In this paper, a simple equivalent circuit model and convolution algorithm based on impedance analysis were presented to assess state-of-charge, terminal voltage and charge/discharge capability of supercapacitors. Furthermore, an impedance function based on the equivalent impedance model was established to simulate the dynamic performance of a supercapacitor. The results can be used to control the reliable prediction of supercapacitors performance in electric vehicles, hybrid electric vehicles, fuel cell vehicles and classical automotive applications.