Comparative Study of Battery Aging on Battery Electric Vehicle and Battery-Ultracapacitor Hybrid Energy Storage Systems

Hybrid energy storage system (HESS) consisting of battery and ultracapacitor is a promising solution for range anxiety of battery electric vehicle (BEV) and the life of batteries. In this paper, a comparative study is made on BEV and HESS, considering energy consumption and aging. HESS architecture is selected such that ultracapacitor is connected to the dc bus through a DC-DC converter, so the power flow between battery and the ultracapacitor can be controlled. Control is implemented using a low pass filter, ensuring high-frequency currents are handled by the ultracapacitor and the rest of the currents are handled by the battery, thereby reducing stress on the battery. Performance is evaluated for different drive cycles, and filter cut-off frequency is selected according to drive cycle requirement. The aging model is developed using the Arrhenius equation, and a comparison of the battery state of health (SOH) is done on BEV and HESS models for various drive cycles. It is found that battery in HESS ages slower than that of BEV.