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SOC Estimation Of Li-ion Battery And Research On Variable Current Equalization Control

Posted on:2021-04-30Degree:MasterType:Thesis
Country:ChinaCandidate:M X GongFull Text:PDF
GTID:2392330602487796Subject:Control engineering
Abstract/Summary:PDF Full Text Request
In recent years,with the development of science and technology,the improvement of battery assembly technology and the generalization of extensive automatic production technology,the performance of.battery management system is improving.Among them,the estimation of state of charge(SOC)of lithium-ion battery and the balance control of battery pack are considered as the core technologies of battery management system.In this paper,the SOC estimation and battery equalization control of lithium-ion battery were studied with the lithium-ion battery.The main research work is as follows:(1)In view of the influence of environmental temperature and battery aging on the modeling of lithium-ion battery,through the battery capacity data at different temperatures,ohmic internal resistance change data,the advantages and disadvantages of various equivalent circuit models were analyzed,structural improvement and capacity compensation are carried out on the traditional PNGV model.According to the standard HPPC experimental data and the dynamic characteristics of lithium-ion battery,the parameters of the improved PNGV model are identified.The simulation results show that the dynamic characteristics of lithium-ion batteries has been well simulated by the improved PNGV model.(2)The advantages and disadvantages of various Kalman filtering algorithms in estimating SOC of Li-ion battery are analyzed in detail.In view of the problem that the tracking ability of the cubature Kalman filter algorithm is poor when the noise statistical characteristic changes,the model mismatches,and the filtering result jitters,the strong tracking algorithm and the smooth filtering algorithm are introduced,the RTS strong tracking cubature Kalman filter algorithm(RTS-STCKF)is designed.The new algorithm forces the residual sequence to be orthogonal through the fading factor,so as to modify the final filtering value in the smoothing process,the anti-interference ability in SOC estimation was improved.The simulation results show that the RTS strong tracking cubature Kalman filter algorithm has better tracking performance and anti-interference ability in SOC estimation of Li-ion battery.(3)In order to solve the problem of balancing current jitter and long equilibrium time,a variable current double-layer balancing control strategy is designed.In the variable current double-layer equalization control strategy,the safety and rapidity of the battery pack in the charging process are fully considered.The improved buck circuit model is selected as the main circuit of the inductive equalization control,and the variable current charging equalization control scheme is established with the SOC of the battery pack as the equalization criterion.In the process of charging,DMC algorithm is used to adjust the balance current dynamically,and the optimal charging current is calculated by combining the ampere hour integral method and Mas law,so as to realize the fast and safe equalization control of battery pack.The simulation results show that the problems of current jitter and long equilibrium time can be:effectively solved by the double-layer equalization control strategy(4)The experiment of equalization control system is designed.The experiment consists of hardware and software design.The hardware design contains the design of key circuits and the selection of core components.The software design contains the design of system control process,communication service subprogram and LABVIEW software program.After the completion of all the system design and construction.The balanced control of the battery group has been realized by the six lithium-ion battery arrays are simulated.The experimental results show that' the battery model,SOC estimation algorithm and equalization system architecture designed in this paper have certain reliability and authenticity.
Keywords/Search Tags:Lithium ion battery, SOC, Cubature Kalman filter, The laws of mas, Equalization
PDF Full Text Request
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