Research On Segment Fractional Order Modeling And SOH Estimation Of Lithium Power Battery

With the rapid development of the new energy electric vehicle industry,automotive lithium-ion power batteries and battery management systems received widespread attention.However,the research and application of lithium-ion power batteries and battery management technologies are immature,which greatly limits the development of new energy electric vehicles and lithium-ion power batteries and other related industries.Accurate estimation of the state of the lithium-ion power battery can effectively improve the reliability of the electric vehicle battery management system.Accurate estimation of the state of the lithium-ion power battery can also make driving safer and efficient.This paper research on battery modeling,the estimate state of charge and the estimate state of health.The main contents as follows:(1)The experimental research on the charge and discharge characteristics of lithium-ion batteries for EV.Carry out experimental research on lithium-ion power batteries and collect data based on the BTS battery test system.According to the experimental results,the characteristics of battery are analyzed.Laid the foundation for battery modeling and state estimation.(2)Establish a segmented fractional-order equivalent circuit model of lithium-ion power battery by analyzing and comparing the characteristics of different lithium-ion power battery modeling methods.Identify model parameters through HPPC pulse test experiment and identify fractional order through particle swarm optimization algorithm.The experimental results verify the accuracy and effectiveness of the built model.The built model handle the trade-off between the accuracy of battery model and computational complexity,laid the foundation for state estimation.(3)Setting up the lithium-ion battery SOC based on fractional Kalman filter algorithm.The state-space equation of piecewise fractional equivalent circuit model is established.The SOC estimation of the lithium-ion power battery is realized by using the fractional order Kalman filter algorithm.The experimental results show the effectiveness of the algorithm and our algorithm is more accurate than the extended Kalman filter algorithm.(4)Building the estimation SOH of lithium-ion battery based on battery internal resistance equivalent model.Research on battery ageing test of lithium-ion battery and collect the data based on BTS battery test system.Analyzing the cell capacity,the internal resistance and the model parameters changes with the number of charge and discharge cycles by the results.Establish the state-space equation of the ohmic resistance of lithium-ion battery based on the established model.Account the internal resistance by using the extended Kalman filter algorithm.The result of our model shows the effectiveness of internal resistance model.The change trend of the average value of ohmic internal resistance of lithium-ion power battery is analyzed.The way of average value of internal resistance calculates the SOH is chosen.