| With the increasingly serious energy and environmental problems,vigorously promoting the electric vehicle industry is not only an effective solution to the energy crisis,but also a powerful measure to promote China's green development.In practical application,considering the demand of electric vehicle for the performance of power battery,the single battery is usually divided into series and parallel groups.When the series battery pack is applied to electric vehicle,the key problem to be solved is the inconsistency of parameters among the single battery,and the equalization technology is an important method to optimize the consistency of the battery pack.This article focuses on the charge equalization technology for series lithium battery pack.The main research content is as follows:(1)From the perspective of primary inconsistency and secondary inconsistency,the causes,manifestations,and solutions of battery pack inconsistency problems are analyzed.According to the selection of equalization variables,test experiment of the battery pack parameter performance is performed to compare the advantages and disadvantages of the open circuit voltage,the working voltage and the state of charge,and the working voltage is selected as the object of charge equalization.(2)The advantages and disadvantages of the single battery model are analyzed and compared.Based on the Partnership for a New Generation of Vehicles(PNGV)model of single cell and the statistical method to generate battery pack model parameters,the simplified PNGV model of the series battery pack is constructed.The modeling of any series battery pack is realized.(3)The flyback power converter based equalization circuit is selected.In the discontinuous mode,the equalization simulation circuit is designed and the accuracy of the parameters is verified.Based on the inconsistency evaluation criteria,the relative voltage range is used as the condition for the equalization control strategy to be turned on and off,and the corresponding equalizationthreshold is set.The charge equalization control strategy is verified with the simulation circuit model.(4)The experimental platform for charge equalization of three series lithium battery pack is built and the voltage data of single battery are collected in real time to verify the feasibility of the equalization control strategy. |
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