Research and Design of Active Equalization System for Multi-stage Series Li-ion Battery

Abstract In view of the obvious phenomenon of the difference between the single cells of the series battery pack after multiple cycles of recycling, it is necessary to adopt balanced control to extend the working life of the battery pack, improve the energy utilization rate, and ensure the safety and stability of the battery pack. This paper proposes a single battery voltage as the control variable, adopts staged equalization, charge-discharge two-level equalization protection and isolated flyback converter circuit to realize the active equalization of battery pack energy, and designs the corresponding equalization control circuit. Through the comparison of a variety of control methods, the application of this system can achieve the final voltage balance. Tests show that the proposed equilibrium system can make full use of the larger capacity monomers, quickly improve the energy imbalance in the battery pack, and can effectively extend the working life of the battery pack and improve energy utilization.