Research On Charging And Discharging Characteristics As Well As Thermal Behavior Of Traction Lithium-ion Batteries

The increasingly serious energy crisis and environmental problems make the new energy technology a hot topic nowadays.As an ideal new energy source,traction lithium-ion batteries have been widely used in new energy vehicles.The advanced traction lithium-ion battery management system is very crucial to the efficiency,safety and reliability of the new energy vehicle' traction lithium-ion battery system under the complex vehicle condition,and the research on the modeling method,charge discharge performance and thermal behavior of the traction lithium-ion battery is the basis for the establishment of advanced BMS.At present,the battery modeling method of vehicle' BMS is limited to the equivalent circuit method.However,The equivalent circuit method of the concentrated parameters can not accurately describe the real time condition of the power battery in the complex vehicle condition.Therefore,it is very important to establish a high fidelity battery numerical model and reflect the dynamic lithium ion state under the real time condition.At the same time,the traction lithium-ion batteries will show different characteristics under different conditions.In order to achieve the effective control of the safety,reliability and high efficiency of the battery system,it is necessary to study the charging and discharging characteristics of the traction lithium-ion battery under different conditions.In addition,the thermal behavior of traction lithium-ion battery is the key to influence the safety of traction lithium-ion battery.The study of the thermal behavior of traction lithium-ion battery is the key technology to improve the safety of traction lithium-ion batteries.In this paper,a series of researches are carried out on the problems of traction lithium-ion batteries mentioned above based on the research status of the traction lithium-ion battery.Based on the electrochemical mechanism and the thermodynamic principle,a high-fidelity electrochemical-thermo-coupling model was established.The characteristics and thermal behavior of lithium ion battery under cyclic charge and discharge were analyzed by electrochemical-thermo-coupling model and the experiment.Its main work and research results are as follows:(1)A high A high fidelity electrochemical thermal coupling model for a new lithium ion battery lithium ion battery powered by a new energy vehicle is established.In order to ensure the accuracy of the model,the electrochemical thermal coupling model comprehensively considers the influence of the dynamic change of the model parameters on the model precision,and makes some correction.The electrochemical model compensates the model internal resistance under a charge discharge.The model's side reaction is considered in the cycle charge and discharge conditions.Influence? The coupled electrochemical thermal coupling model was tested by the Urban Dynamometer Driving Schedule(UDDS)experiment.The experimental results proved that the results of the numerical model were true and reliable.(2)The battery characteristics of power lithium ion batteries under cyclic charge and discharge were studied.Based on the electrochemical thermal coupling model,the capacity characteristics,polarization voltage characteristics and open circuit voltage characteristics of power lithium ion batteries under cyclic working conditions were analyzed.The internal resistance characteristics of the power lithium ion battery were analyzed by the HPPC experiment,and the micro particle characteristics of the power lithium ion battery were analyzed by adjusting the parameters of the electrochemical thermal coupling model.(3)The thermal behavior of lithium ion battery is simulated.The thermal behavior of the traction lithium-ion battery was analyzed based on the electrochemical-thermal coupling model.The temperature distribution of the dynamic lithium ion battery was calculated by the finite element method,and the temperature distribution of different charging and discharging states was analyzed...