SOP And SOE Estimation And Hardware In The Loop Simulation Verification Of Lithium-ion Batteries

Due to the shortage of global oil resources,automobile technology is gradually developing towards the direction of energy saving and environmental protection.Therefore,China actively encourages the development and use of new energy vehicles.Battery model and state estimation are the research hotspots of power battery technology.The state of power(SOP)and state of energy(SOE)are closely related to the acceleration braking and driving range of electric vehicles,and the online accurate estimation is the key problem of battery management system.This project relies on the National Key R&D Program of China " Research on key technologies of high precision and high reliability battery management system ".This paper focuses on the on-line identification of model parameters based on fractional model and the joint online estimation method of SOP and SOE,and applies it to d SPACE for engineering verification.The full text is summarized as follows:Firstly,the integer order equivalent circuit model and the fractional order equivalent circuit model are introduced respectively.The extended Kalman filter(EKF)algorithm,the fractional extended Kalman filter(FEKF)algorithm and the fractional recursive least squares method with forgetting factor(FFRLS)algorithm are introduced.The online parameter identification method based on three algorithms is established,and the advantages and disadvantages of the three methods are compared by using three kinds of dynamic condition tests under different conditions.The results show that the overall error and maximum error of FEKF algorithm are better than the other two methods in wide temperature range,large magnification and full SOC range.Secondly,the three off-line peak power test methods are introduced,and the defects of off-line test methods are analyzed.The dynamic peak power test method is proposed.Taking the dynamic peak power test method as the benchmark,the SOP online estimation based on fractional order model is carried out to verify the accuracy of the estimation method under different conditions and the estimation error is within 40 W.Taking peak power as the core evaluation index,a performance evaluation method of lithium-ion battery was proposed.Four batteries in different states are used to illustrate the feasibility of the evaluation method.Then,the principle of SOE estimation based on FEKF algorithm is introduced,and the state space equation of SOE estimation based on FEKF algorithm is derived.Based on the fractional order model,double Extended Kalman Filter algorithm is used to estimate the model parameters and SOE online.The estimation results of SOE under different memory length and model order are compared,and the values of memory length and model order with better estimation effect are determined.The estimation results of SOE of fractional order model and integer order model are compared under different temperature and different magnification conditions.The results show that the stability and accuracy of the fractional order model are better than that of the integer order model in wide temperature range,large magnification and full SOC range,and the estimation accuracy of fractional order model is less than 4%.Finally,the online simulation model of Li-ion battery model parameters,SOC,SOP and SOE based on fractional order model is constructed,and the algorithm is transplanted to d SPACE to verify the applicability and stability of the estimation method under complex conditions.