The Estimation Of SOC And The Design Of Thermal Management System Of The Lithiun-Ion Battery Pack For EV

With traditional energy resources are becoming scarcer and scarcer and the environment is getting worse and worse,the auto industry is transformed to the new energy direction.The pure electric vehicle as the main force is striving to develop.What's more,the battery pack is the power source and it's carrier,which has been the foundation of Commercialization of electric vehicles.Battery management system is the main center of the battery pack,which has aggregated the function of monitor,management,and control.And to some extent,it has been the key factor to the quality of battery electric vehicle.Estimation of State of Charge(SOC),and thermal management system as the core of battery management system are the key to the reflection of battery status and improvement of battery performance and prolong battery circulation life cycle.So,Iron phosphate-lithium power battery is the object of this paper.And this paper optimizes the relevant parameters that influence the compound model of the estimation of SOC.Then using the state-variable which has been optimized to estimate extended Kalman Filter.And designing the high conductivity cooling system or parallel air cooling integrated heat management system,which has optimized the traditional tandem passive air cooling system.Firstly,this paper introduces the development of the electric vehicle and the key technology of the battery management system.And this paper uses the Li-battery's basic composition and working principle as the start point,through it,analyzing the characters of the Li-battery's charging and discharging and internal and external factors that affect the estimation of SOC.Based on this,leading on the theory of kalman filtering algorithm,and introducing the extended kalman filtering algorithm as a calculation process to the status variable.Analyzing the different kinds of battery,then list the state space model of the simplified model,Thevenin model and compound model.And by testing the factors of temperature,charge and discharge,self-discharge rate,recycling use,make a fitting of corresponding compensation curve.And the aim is to get simulation analysis of the output-curve of SOC which has been optimized.At last,this paper is based on the tandem passive air cooling and heating management system,and figuring out a optimal design of high conductivity heat dissipating material/parallel air-cooling integrated system.And it is a pressure cooling system that the high conductivity heat dissipating material sticks to the battery shell so that the battery cells can be linked with.This paper sets up a simulation model of cooling system.In the meanwhile,testing the system practically so that the data can be compared with the simulated data.After that,we can analyse and check the validity and the accuracy of the model.By designing the cell spacing rationally,we can optimize the model.And in this way we can solve the problems of the low efficiency and large temperature difference of the cells that the traditional air cooling caused.