Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (6): 1946-1956.doi: 10.19799/j.cnki.2095-4239.2023.0088

• Energy Storage Test: Methods and Evaluation • Previous Articles     Next Articles

NSGA-II genetic algorithm-based optimization of the lithium battery equalization index

Yuling LIU1(), Jinhao MENG1(), Qiao PENG1, Tianqi LIU1, Yang WANG2, Yongxiang CAI2   

  1. 1.School of Electrical Engineering, Sichuan University, Chengdu 610065, Sichuan, China
    2.Institute of Electric Power Science, Guizhou Power Grid Co. , Ltd, Guiyang 550002, Guizhou, China
  • Received:2023-02-21 Revised:2023-03-05 Online:2023-06-05 Published:2023-06-21
  • Contact: Jinhao MENG E-mail:llyl202207@163.com;jinhao@scu.edu.cn

Abstract:

Lithium-ion battery equalization systems are primarily used to address inconsistencies during battery pack operation. However, existing studies lack a theoretical basis for selecting the equalization threshold when considering multiple equalization metrics. To address this problem, the paper proposes a computational framework based on the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to optimize the equalization metrics of the Li-ion battery equalization system. First, the equalization threshold (ΔV ) is used as the problem parameter, and the equalization speed, the number of switching actions, and SOCconsistency are considered as multiple equalization indicators to establish the objective function. A method for determining the relationship between the threshold and equalization indicators is given to establish the problem model for optimizing Li-ion battery equalization indicators. Then, the NSGA-II algorithm is used to optimize the multiple equalization indicators and design the corresponding decision strategy. Finally, the effectiveness of the proposed algorithm is verified under New European Driving Cycle (NEDC) and Highway Fuel Economy Test (HWFET) conditions. The results show that the switching frequency of the optimal threshold ΔV = 0.0232 is 42% of the empirical threshold ΔV =0.01 for the NEDC condition, with similar battery pack consistency and equalization speed. Similarly, the switching frequency of the optimal threshold ΔV =0.0156 is 43.6% of the empirical threshold ΔV =0.01 for the HWFET condition. The proposed method in this paper addresses the challenge of determining the equalization threshold and enables a more scientific and effective design of equalization systems.

Key words: NSGA-II algorithm, multiobjective optimization, lithium battery equalizationequalization, equalization index, equalization thresholds

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