SMES/battery hybrid energy storage system for electric buses

This paper proposes a novel use of superconducting magnetic energy storage (SMES) hybridized with the battery into the electric bus (EB) with the benefit of extending battery lifetime. A new power control algorithm, which integrates a power grading strategy with the filtration control method, is introduced in this paper, achieving further improvement of battery lifetime. To demonstrate the performance of the SMES/battery hybrid energy storage system (HESS), a dynamic EB system is described with the advantage of considering more factors into the driving patterns. Simulation results show that the proposed HESS has successfully combined the SMES with the battery forming an optimal system that has the advantages of primary energy storage systems while complementing the disadvantages of each system. This paper also does the quantitative analysis of battery lifetime extension in the battery-only system, the filtration-based HESS, and the novel control-based HESS.