SOC Estimation Method Research Of Power Battery Based On Improved PNGV Equivalent Model

With the depletion of fossil fuels and the increasingly serious environmental pollution problems,Promote and develop new energy vehicles is the inevitable trend of future development,Therefore,the electric vehicles has become a new direction of development of urban transport.Power battery is the power source of electric vehicles,which directly affect the mileage of electric vehicles,and restricts the development of electric vehicles.The mileage and life Electric vehicle are much lower than the ordinary fuel vehicles,so that the development of electric vehicles become one of the bottlenecks.There are two ways to break the power battery limit.The first is to develop new battery technics and technology.The second is make the use of battery management system to optimize the battery charge and discharge process supervision in the application phase,give full play to the battery performance and extend battery life.In this dissertation,the author focuses on powered lithium batteries,the SOC of the battery is studied in terms of both the battery model and the SOC state estimation algorithm.For the study of the battery model,the accuracy of the lithium battery model is the key to improve the accuracy of SOC estimation.A precise battery model provides precise data for the battery management system to control.This dissertation first introduced the electrochemical principle and basic characteristics of lithium iron phosphate battery,obtained experimentally analyzed the factors affecting battery characteristics through battery charge and discharge data.For the actual operating environment of the power battery,the dynamic PNGV model is established to carry on the thorough research,introduces the temperature,the remaining electric quantity to revises the model parameter,The parameters of the battery-temperature-SOC model were established to identify the relevant parameters of the model and to build the simulation model in Matlab / Simulink to verify the rationality of the model.For the battery SOC estimation algorithm,the article first introduced the principle and method of commonly used algorithm.On the basis of the established battery model,the Extended Kalman filter algorithm based on capacity compensation is studied,and Simulink model is established to simulate the experimental data and verify the rationality of the algorithm.In this dissertation,use GuoXuan IFR32132 cylindrical lithium iron phosphate battery as study object,use constant temperature and humidity test chamber and charge and discharge cabinet to build experimental conditions.Designed the group temperature and the different conditions of the charge and discharge experiments.According to the experimental data,the R-SOC-T mathematical model,OCV-SOC model and capacity compensation model are established.The PNGV model is used in the battery SOC estimation.The simulation results show that the dynamic PNGV model can effectively improve the accuracy of SOC estimation and achieve the expected purpose.