Parameter Identification Of Electrothermal Coupling Model Of Lithium Battery

The battery is one of the three major components of the battery electric vehicles drive system,and its operating state directly affects the performance of battery electric vehicles.Therefore,it is very important to study its model and parameter identification.Combined with the needs of the project,the lithium battery was taken as the research object.Based on the basic working principle of battery,the electrothermal coupling model was studied.The chaotic particle swarm optimization algorithm was used to identify the model parameters.The main work is as follows:(1)Based on the analysis of the working principle and important performance parameters of lithium battery,the heat generation mechanism and heat transfer characteristics were studied.Then,the common equivalent model of lithium battery was introduced,and the advantages and disadvantages of the corresponding model were analyzed and summarized.Finally,the secondorder RC circuit was selected as the electrical sub-model.The electrothermal coupling model of lithium battery was established by coupling the two-state thermal model with the heating and temperature dependence of the circuit parameters.(2)Based on the theory of model parameter identification,the particle swarm optimization algorithm was analyzed.The chaotic particle swarm optimization algorithm was studied based on chaotic sequences.Then,the Rosenbrock function was used as the test object to verify the optimization performance of the chaotic particle swarm optimization algorithm.The results showed that the chaotic particle swarm optimization algorithm had good robustness and strong convergence,and could better meet the requirements of global optimization.(3)Identified the electrical sub-model parameters and thermal model parameters by the pulse charge-discharge cycle experiment under constant temperature conditions and the constant current discharge experiment under different state of charge.Then based on the chaotic particle swarm optimization algorithm,the coupled model parameters of the obtained electrical submodel and thermal model parameters are identified.Finally,the obtained coupling model was experimentally verified under constant current charge-discharge conditions and DST conditions.The results showed that the voltage estimation error of the electrothermal coupling model is small,which can better capture the battery voltage characteristics,and verify the accuracy and effectiveness of the proposed electrothermal coupling model and parameter identification method.