Dynamic Simulation of Battery/Supercapacitor Hybrid Energy Storage System for the Electric Vehicles

One of the most efficient options for enhancing energy use by electric vehicles is through hybridization using supercapacitors (SCs). A supercapacitor has many beneficial features especially its high efficiency, capacity to store large amounts of energy, a simpler charging system and quick delivery of charge. The objective of this paper was to highlight the benefits and demonstrate the feasibility of using SCs in combination with parallel battery in EVs by employing a modelling and simulation method. A semi-active topology which employed a single DC/DC converter was selected, and the performance of the battery/SC hybrid energy storage system (HESS) was evaluated for possible reduction in stress and extended battery life. The HESS was modelled based on generic battery, SC and converter models within Simscape Power Systems in Matlab-Simulink and ADVISOR. The HESS model was validated by data from the literature and showed a good compatibility. This implies that the model used in the present study is reliable and have a high probability of deriving an accurate prediction of the HESS performance. Dynamic simulations were performed for Tesla S70 electric car. The results relating to hybridization showed a significant reduction in battery charge. The SC power contribution and the range extension in the HESS was estimated to be in average 21.5% and 80 kin for the USC06 driving cycle, respectively. The simulation results presented a range of verified benefits attributed to the HESS: by deploying transient currents during acceleration and deceleration which greatly reduces battery stress, there is significant enhancement of system performance; an appreciable reduction in the number of cycles/year has a direct positive impact on battery aging process; there is a striking increase in vehicle range; and finally, it provides insulation for the battery pack at very cold ambient air temperatures. Moreover, the hybridization could allow reducing the size of the primary power source or the EV battery.