Research On Equalization Method Of Power Battery Pack Based On Remaining Available Energy

After years of research,battery equalization technique has developed rapidly.This technique mainly forms two research hotspots,namely battery equalization topology development and equalization control algorithm research.Aiming at the problems existing in the current common equalization judgment indicators such as SOC and battery terminal voltage,this dissertation proposes a new battery pack equalization method by making remaining available energy and equalization time of the battery pack.as a comprehensive balancing target.Firstly,the performance parameters of lithium battery characteristics are studied.The causes and effects of battery inconsistency are analyzed.Based on the knowledge of statistical indicators,the quantitative analysis method of single cell inconsistency is proposed.The characteristics of common inconsistency evaluation indicators and the solutions to the inconsistency are analyzed.The advantages and disadvantages of the common battery equivalent circuit models are analyzed and summarized.The equivalent circuit model is selected for SOC estimation and the circuit model state equation is established.The open circuit voltage and polarization related parameters of this model are identified through the improved HPPC experiment.An improved extended Kalman filter SOC estimation algorithm is proposed and it is used for the SOC estimation process to obtain the precise SOC value required for this dissertation.Then,based on the research of traditional active equalization circuit,a modular grouped equalization circuit combining the Cuk circuit with the Buck-Boost circuit is proposed.Based on analyzing the advantages and disadvantages of the existing equalization judgment indicators,the concept of remaining available energy is proposed based on SOC from the energy perspective.The particle swarm optimization algorithm is used to to optimize the equalization energy transfer path.The specific step of optimizing energy transfer path is that the combination of the remaining available energy of the battery module and equalization time is used as objective function.Under the premise of ensuring that the equalization objective function is maximized,different battery equalization transfer energy array is taken as the research object and it is optimized.After the final equalization transfer energy array is obtained,the corresponding optimized equalization time array and the direction of energy transfer can be obtained to optimize the equalization process.Finally,the comparison experiments are carried out,which includes the SOC estimation algorithm precision comparison experiment and the equalization effect experiment.The SOC estimation algorithm precision comparison experiment result shows that the accuracy of the proposed improved extended Kalman filter SOC estimation algorithm is higher than that of the traditional extended Kalman filter SOC estimation algorithm.The equalization effect experiment results shows that the proposed equalization method is feasible and has certain advantages,which can effectively reduce the equalization time,improving the remaining available energy in the battery pack and the energy utilization rate of the battery pack.