Performance Evaluation of Hybrid Battery–Supercapacitor-Based Energy Storage Systems for Urban-Driven Electric Vehicles

Abstract

Boosting the performance of energy management systems (EMSs) of electric vehicles (EVs) helps encourage their mass adoption by addressing range anxiety concerns. Acknowledging the higher power densities of supercapacitors (SCs) compared to those of the Lithium-ion (Li-ion) batteries used in EVs, this work proposes an optimal sizing and energy management strategy of a hierarchical hybrid energy storage system (H-HESS). In this system, the SCs are voltage-controlled to solely provide the current requirements of an EV motor during urban driving cycles with frequent accelerations and decelerations, while the EV battery recharges the depleted SCs. The proposed H-HESS is modeled and simulated on MATLAB/Simulink, and its performance is compared to that of a traditional battery-only energy storage system (BESS). Simulation results reveal that this H-HESS system offers a 55.7% peak current reduction and ≈+2% improvement in battery loss of capacity in comparison with BESS. A pulsed battery discharge current profile is imposed by the proposed H-HESS, while C-rate control is implemented. This improves the battery aging by reducing the formation of the solid electrolytic film (SEI) that otherwise decreases its capacity.