Research And Design Of Master-Slave Battery Management System For Mini Van Logistic Vehicle

Shanxi province is a major province of coal and an important energy base in the country.Changing the “one coal alone” industrial structure,promoting the energy revolution,and achieving economic restructuring are urgent issues at present.So Shanxi province proposed the development strategy of cultivating and expanding the new energy automobile industry and accelerating the promotion and application of new energy vehicles.In March 2017,the Shanxi Economic and Information Technology Commission issued the “New Energy Vehicle Industry Development in Shanxi Province in 2017”.The plan focuses on the expansion of the scale of the new energy automotive industry and the promotion of key projects.In recent years,with the rapid development of e-commerce,the demand for pure electric logistics vehicles has continuously increased.E-commerce traditional logistics vehicles mainly are diesel and gasoline-type vans.With the rapid development of China's new energy vehicles,pure electric logistics vehicles have also become a new type of transport vehicle that Shanxi provincial government and new energy vehicle companies vigorously promote and develop.At present,special research and development for mini-van pure electric logistics vehicles are few,which leads to the driving range and battery life of such models not achieving optimal results.In view of this situation,this paper combines the car battery layout and comprehensive driving conditions of a mini van-type pure electric vehicle,and studies and designs the state of charge(SOC)estimation algorithm and battery management system for lithium batteries.This paper mainly completes the following work:(1)Designed an anti-diffusion SOC estimation algorithm based on extended kalman filter algorithm.Based on the extended kalman filter algorithm,considering the effects of system noise and measurement noise,a noise estimator is added;And introducing the divergence criterion,when the estimation error of the state variable becomes larger and diverges,an adaptive exponential freezing factor is constructed for the kalman gain matrix to ensure that the estimation error is within the required accuracy range.(2)Completed modeling of vehicle lithium battery and identification of model parameters.Using the recursive least squares method,the resistance and capacitance parameters in the battery model are obtained under different charge and discharge rates;And fit the polynomial formula between the open circuit voltage(OCV)of the battery and the battery SOC through the charge and discharge curve of the battery.(3)Designed the one-master multi-slave mode battery management system framework.Combined with the use of batteries in the mini-van pure electric logistics vehicles,the function and topology of the battery management system are analyzed in depth.The battery management system is set as a master-slave topology of a central module unit(CMU)and multiple acquisition module units(AMU)to monitor each battery.(4)Completed part of the battery management system module circuit design.Mainly designed the motherboard power module circuit,control module circuit,battery voltage acquisition circuit,equalization circuit,communication circuit.The mainboard adopts Freescale's MC9S12XS128 chip to control the system.The LTC6802-2 chip from Linear Technology is used to complete the collection and equalization of battery cell voltage,current,and temperature.