| With the energy crisis and environmental pollution,electric vehicles have received more and more attention.Lithium batteries have been widely used in the field of power batteries due to their excellent performance.However,because of inconsistencies in the application process,the overall performance and service life of the battery packs are seriously affected,and even the battery packs are exposed to fire and explosion.The equalization technology in battery management is an important means to solve the above problems.Based on the existing results,this paper aims to design a balanced scheme with high comprehensive performance.Firstly,its are analyzed that the main factors affecting the inconsistency of the battery pack and its influence The advantages and disadvantages of different equalization indicators for equalization control are discussed.The SOC is selected as the equilibrium index.Then the advantages and disadvantages of the main SOC estimation methods are compared and analyzed,and the SOC estimation based on Kalman filter is selected to realize the Kalman filter SOC estimation algorithm based on the second-order RC equivalent circuit model.Secondly,the detailed analysis of each type of equilibrium topology is carried out,and the evaluation indexes of eight equilibrium topologies are extracted as the evaluation indicators of the balanced topology fuzzy comprehensive evaluation method according to the characteristics of the topology.Then,the improved analytic hierarchy process is used to determine the weights of each evaluation index,and their membership functions are established respectively.Finally,the optimal equilibrium topology of the series-battery optimal balanced topology of any series of cells is selected.Then,the equalization scheme is designed from two aspects: equalization topology and equalization strategy.The Cuk circuit is selected as an equalizer to design an active equalization scheme for any single-cell energy transfer type.The equilibrium topology and the equilibrium state of the Cuk circuit are analyzed.On the basis of improving the Cuk equalization circuit,the equalization strategy between the battery pack and the module based on the equilibrium center threshold method is finally formulated.Finally,the proposed equalization strategy is tested by integrating the equalization topology and equalization control algorithm into the experimental platform.The performance of the optimized equalization strategy algorithm is evaluated by the SOC distribution of the battery pack during charging and discharging process and at the end of charging and discharging.It shows that the equalization strategy designed in this paper effectively improves the energy efficiency of the battery pack and reduces the inconsistency of the battery pack under high efficiency and low cost. |
