Equalization of series connected Lithium-ion battery based on state of charge in Electric Vehicle

Battery equalization is the key technology in battery management system, and many equalization circuits and arithmetics have been researched to improve equalization effectiveness. This paper puts forward a non-dissipative equalization program based on fuzzy logic control (FLC) to improve the inconsistency of Lithium-ion batteries connected in series. The bidirectional equalization circuit with energy transferring inductors is designed to achieve the equalization of cell to cell. The equalization based on the state of charge (SOC) is proposed, and temperature-dependent battery model is designed for SOC estimation. For effective equalization, the FLC is proposed to reduce energy consumption and equalization time. A comparison of the proposed FLC based on the mean-difference arithmetic is carried out to validate the advantages of the proposed program. The simulation results show that energy and time effectiveness can be significantly raised during battery equalization.