After a thorough literature survey, it was found that there are many battery pack equalization strategies developed, but the systematic review and classification are missing. Some studies simply classify the equalization strategies based on the equalization variable, such as voltage, SOC, and capacity.
The equalization strategy is embedded in a real BMS for practical application analysis. Lithium-ion battery pack capacity directly determines the driving range and dynamic ability of electric vehicles (EVs). However, inconsistency issues occur and decrease the pack capacity due to internal and external reasons.
Battery pack equalization strategy based on UCCVC hypothesis is proposed. The convergence of equalization is obtained in different inconsistent conditions. The equalization strategy is simulated in fresh and aged scenarios. The equalization strategy is embedded in a real BMS for practical application analysis.
Finally, the results of simulation and experiment both show that the equalization strategy not only maximizes pack capacity, but also adapts to different consistency scenarios. Pack capacity and consistency in the fresh or aged state are significantly improved after battery equalization.
L. Dung proposed a charging equalization method that adapts itself to the aging conditions. It used the voltage difference among cells to adjust the equalization current, which not only maximized the total capacity but also slowed down the battery pack aging rate.
Based on the above analysis, this paper proposes an active equalization method for series-parallel battery pack based on an inductor. The main contributions are described below. The energy storage device responsible for energy transfer requires only one inductor and the topology is simple and low cost.