| Out of concern for the energy crisis,the use of new energy sources has increased globally,and for this reason China is vigorously promoting the use of new energy sources with lithium-ion batteries as the power source.Lithium-ion batteries are widely favored by the market for their safety and high charging efficiency,however,the inconsistency of lithium-ion batteries causes the deterioration of battery health and greatly reduces the performance of the whole battery pack or even causes accidents.To address the problem of inconsistency in existing Li-ion battery packs,the use of equalization control circuit modules can greatly change the phenomenon of battery pack imbalance.The adopted control strategy can effectively solve the battery pack inconsistency problem,shorten the equalization time and improve the overall equalization efficiency of the battery pack.The main research contents of this paper are:1.In this paper,the selected Sanyo lithium-ion battery is used as the experimental research object,the lithium-ion battery characteristics are analyzed and the secondorder circuit model is selected to describe the dynamic characteristics of the battery operation,the equivalent parameters within the selected battery are identified through the experimental platform,and the lithium-ion physical model of the identified battery parameters is built through the software Matlab to check the accuracy of the identified parameters.In the estimation of the lithium-ion SOC algorithm,the extended Kalman estimation of the battery SOC is selected for the actual situation of the battery,and the experimental results show that the deviation of the selected algorithm estimation is within 1.25%,and the experimental results are more accurate and provide the criteria for the balanced judgment of the battery pack.2.The active equalization circuit with bi-directional energy transfer based on Buck-Boost topology is introduced,and the energy transfer between adjacent cells in the battery pack is realized by mean-difference algorithm simulation to verify the feasibility that the selected equalization circuit topology can reduce the inconsistency of the battery pack.The article introduces the fuzzy algorithm and then the fuzzy PID algorithm,and finally proposes the variable-domain fuzzy PID as the equalization control strategy,and builds the simulation in Matlab/Simulink and compares the results with the fuzzy PID algorithm,the results show that the battery pack has a certain degree of reduction in the charging and discharging as well as the shelving equalization time,thus confirming that the variable-domain fuzzy PID-based PID algorithm,the circuit equalization time can be greatly reduced and the equalization rate of the battery pack can be further improved.3.The hardware circuit is designed according to the active equalization circuit structure.The whole includes the main control module and the data acquisition module:voltage,current and temperature data acquisition,equalization control circuit module,communication module,etc.Finally,the software of the equalization system is introduced,and each subroutine is presented in the form of a flowchart.Finally,the experimental platform is built,and the designed active equalization system is verified through experimental tests to be able to solve the inconsistency problem of the battery pack and achieve the expected results.Figure[55]table[9]reference[76]... |
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