Numerical modeling of hybrid supercapacitor battery energy storage system for electric vehicles

Electric vehicle (EV) has been steadily gaining attention and as a viable alternative to mitigate pressing global energy crisis and environmental issues caused by conventional internal combustion engine vehicles. Nonetheless, the dynamic operation of EV encompassing high charging and discharging currents generated from regenerative braking and acceleration, respectively, may adversely affect the cycle life of the conventional energy storage system. Hence, incorporation of supercapacitors into the energy storage system is recommended in view of its superior cycle efficiency and high power density, which aids in relieving the battery's stress and thus extends its cycle life. In this study, a hybrid energy storage system (HESS) comprising Li-ion batteries and supercapacitors are modeled to evaluate its electrical and thermal performances under different driving cycles. The results obtained reveal that the dynamic stress, peak power demand and thermal performance of the battery have been significantly improved by incorporating supercapacitors into the battery pack in HESS. In comparison with the conventional battery energy storage system, the peak current demands of the battery in HESS for UDDS and US06 cycles have been reduced by 63%, 72.9% and 71.7%, respectively. This approach has shown to be effective in extending the battery's lifespan and is able to improve the safety and reliability of the conventional battery energy storage system. (C) 2019 The Authors. Published by Elsevier Ltd.