Research On Lithium Battery SOC Estimation And Battery Pack Balance Strategy

In recent years,due to the increasingly prominent problems of resource shortage and environmental pollution,electric vehicles are being actively developed around the world,and lithium batteries are widely used in the electric vehicles rely on their excellent performance and safety.About the search and develop of electric vehicles.,the most critical issue is to solve the problems of battery life,cost and safety performance.Therefore,the study of lithium battery state of charge(SOC)estimation and battery pack balancing strategy is particularly important.In this paper,the ternary lithium battery is studied,and the internal structure and functional principle of the lithium battery are first introduced,and the main characteristics of the lithium-ion battery are described on the basis of the established experimental platform.Offline confirmation of model parameters based on secondary RC equivalent circuit,and a simulation model was built for accuracy verification;the model parameters were identified online using the recursive least square method,and the online identification model parameters were more accurate through comparison..Introduces and analyzes the calculation process of extended Kalman filter(EKF)and unscented Kalman filter(UKF)used in battery SOC estimation.Both algorithms cannot update and correct system noise in real time during the calculation process.So improve and introduce the adaptive unscented Kalman filter algorithm(AUKF)to estimate the SOC.By comparing the SOC estimation and robustness of the three algorithms under pulse discharge and U.S.Urban Circulation System(UDDS)operating conditions,the comparison results show that the SOC estimation accuracy and robustness under the AUKF algorithm are both excellent Based on EKF and UKF algorithms,it is more suitable for realizing battery SOC estimation in complex situations.In the research of battery pack balancing strategy,this article first analyzes the reasons for the inconsistency of the battery pack,and focuses on the working principle of the inductive balancing circuit.Based on this circuit,this article proposes a hierarchical balancing control strategy,and the balance is divided.Analyze the principle of hierarchical equalization circuit.Select the working voltage as the balance variable.Two types of equalization circuit simulation models are built in Matlab/Simulink to simulate the equalization function of the battery pack in charging,discharging and standby states.Comparison of results with conventional induced balance method,the proposed hierarchical equilibrium control strategy has a faster equilibrium speed,this shows the superiority of the strategy.Finally,the efficiency of the proposed balanced circuit is verified by related experiments,that is,the proposed hierarchical equalization strategy can effectively improve the inconsistency of single cells.Figure[67]Table[16]Reference[81]...