A novel fusion model based online state of power estimation method for lithium-ion capacitor

Abstract

Lithium-ion capacitors (LICs) show promising applications in renewable energy integration and transportation electrification, due to their excellent performance in terms of energy density, power density and cycle life. Modeling and state of power (SOP) estimation are the keys to exploit advantages of LICs. Unlike electrochemical double-layer capacitors (EDLCs) and lithium-ion batteries (LIBs), LICs involve both insertion/desertion and adsorption/desorption reactions. To better describe the behavior of LICs, we propose a novel multi-model fusion equivalent circuit model (MMF-ECM). The order of the model is determined by the Akaike information criterion (AIC). Moreover, the forgetting factor recursive extended least squares (FFRELS) algorithm is adopted to identify the model parameters online. On this basis, a model-based online SOP estimation algorithm is developed, considering voltage and current limits. The simulation and experimental results validate the accuracy and reliability of the proposed algorithm.