Research On Modeling And State Estimation Method Of Lithium-ion Battery For Electric Vehicle

The goal of "carbon peak and carbon neutralization" brings great opportunities for the development of electric vehicles and energy storage technology.The core of electric vehicle is battery,and its reliability depends on battery management technology,which is based on state estimation.Therefore,accurate estimation of lithium-ion battery state is of great significance to improve the performance of battery management system.However,there are many factors that affect the state of charge,health state and peak power state of lithium-ion battery,which brings great challenges to state estimation.Aiming at the modeling problem of lithium-ion battery,a fractional order model is established.Firstly,the working principle of lithium-ion battery is explored and the test system is built;Then the fractional order battery model is established combined with fractional calculus;Finally,the model parameters are identified by experiments,adaptive genetic algorithm and polynomial fitting tool.The results show that the fractional order model has higher accuracy,the average error of output voltage is 0.46×10-2 V,and the maximum error is 3.25 × 10-2 V.Aiming at the estimation of state of charge and health of lithium-ion battery,a collaborative estimation method of state of charge and health is established.Firstly,the state of charge estimation method is established based on adaptive extended Kalman filter algorithm;Then,the health state estimation method is established based on the adaptive unscented Kalman filter algorithm;Finally,combined with the fractional order model,the state variables of the two state space equations are updated iteratively to realize the collaborative estimation of charged state and health state.The results show that the collaborative estimation method has higher accuracy.The average estimation errors of charged state and healthy state are 0.63%and 0.23%,and the maximum estimation errors are 1.49%and 0.45%.Aiming at the problem of peak power state estimation of lithium-ion battery,a peak power state estimation method based on multiple constraints is established.Firstly,multiple constraints are established by current terminal voltage,state of charge and design limit;Then,the continuous charge discharge peak current is obtained based on multiple constraints;Finally,combined with the terminal voltage,the continuous charge discharge peak power under multiple constraints is determined.The results show that the estimation method based on multiple constraints has high accuracy.Under the three durations,the average estimation error of charge state is less than 5 W and the average estimation error of discharge state is less than 15 W.The model and state estimation method established in this paper can effectively improve the state estimation accuracy of lithium-ion battery.This paper enriches the theoretical basis of battery management technology,and has certain practical significance for accelerating the development of new energy vehicle industry and promoting social and economic construction.Figure [56] Table [16] Reference [103]...