An Active Cell Equalization Technique for Lithium Ion Batteries Based on Inductor Balancing

Abstract

This paper presents the concept of active cell balancing mechanism for Lithium Ion (Li-ion) batteries for Electrical Vehicles (EV) based on inductor balancing method. It equalizes eight number of cells in a series. Voltage differences always exist between cells, therefore a battery management system (BMS) is required to ensure that all cells are equally charged or discharged and it increases the life cycle of the battery. An equalizing method is essential to achieve the best performance. A number of cell balancing method have been presented. Among them, inductor based balancing is faster compared to other methods such as Switched Capacitor Converter (SCC). The problem of conventional inductor based balancing method occurs when the energy transfers from the first cell to the last one and causes long time equalization, because the energy transfer is cell by cell. An alternative topology is proposed in this paper to improve the equalization time and the simulation results are performed to verify the feasibility of the system.