Cost-effective design of a hybrid electrical energy storage system for electric vehicles

A comprehensive economic feasibility analysis and a cost-driven design methodology are essential to the successful application of hybrid electrical energy storage (HEES) systems in electric vehicles (EVs). This paper thus focuses on designing a cost-effective and high-performance HEES system for EVs, comprising of a supercapacitor bank and a lithium-ion (Li-ion) battery bank. In particular, the paper formulates the capacity provisioning problem for the EV HEES system so as to minimize the total system cost, utilizing accurate models of the battery cycle efficiency and state of health, characteristics of the supercapacitor bank, and dynamics of the EV. The aforesaid problem is subsequently solved by combining a gradient descent-based approach with a simulated annealing-based algorithm. Simulation results show that the proposed EV HEES system achieves 21% lower total cost per day and 30% higher fuel economy compared to a baseline homogeneous electrical energy storage system comprised of Li-ion batteries only.