An improved ultracapacitor equivalent circuit model for the design of energy storage power systems

As a new device in energy storage systems, ultracapacitor has drawn more and more attention recently. Many equivalent circuit models have been proposed to analyze its characteristics. However, for the design of energy storage systems, more insights are needed to analyze the transient response for many design aspects, such as the design of the voltage balance circuit, the optimization of the energy management scheme, etc. In this paper, an improved ultracapacitor equivalent circuit model is proposed, and the parameter identification algorithm based on nonlinear least-squares fitting of time response data is designed. The experimental results are presented and some important parameters regarding the proposed equivalent circuit model are discussed in detail.