Abstract:  The inductor was used as the energy storage component and the equalization circuit was built based on the principle of step-up and step-down chopping to reduce the current equilibrium time and the balance energy loss. The K-nearest neighbor genetic algorithm was employed to realize the equalization control of the battery pack and it was compared with the mean equalization strategy. Simulations were performed in MATLAB/Simulink of self-equalization, charging and discharging in 3 balanced conditions. The results show that the equilibrium speed under the 3 conditions is improved by 26.70%, 22.70% and 24.80%, respectively. The reduction of switching operations can reduce the energy loss of the battery pack, and the energy conversion rate is increased by 5.06%. Therefore, the proposed equilibrium strategy has a good balance effect, which can effectively improve the inconsistency among battery packs and reduce the equilibrium time and the balance energg loss.

Key words: battery equalization, K nearest neighbor genetic algorithm, equalization circuit, equilibrium speed