| Battery management system（BMS）is the control unit of electric vehicle battery pack.It can detect the parameters of battery pack,balance management of battery pack,state of charge（SOC）estimation and state of Health（soh）estimation in real time.The design of a high-performance BMS is of great significance to protect the safety of the battery pack and improve the range of electric vehicles.After analyzing and comparing the traditional BMS,this paper finds out the shortcomings of the existing design and makes improvements.By comparing different lithium battery models,the second-order RC equivalent circuit is selected as the battery model.After the charge and discharge experiments of the battery model,the simulation circuit is built to verify the accuracy of the second-order RC equivalent model.In this paper,the unscented Kalman filter（UKF）algorithm is improved,and the improved unscented Kalman filter（iukf）algorithm is formed to estimate SOC and SOH.After the algorithm design is completed,the algorithm simulation is carried out to prove the accuracy of the algorithm.Then,a reliable and fully functional hardware circuit of slave control unit is designed,and the software development environment is selected to write the BMS software.In view of the difficulty of upgrading the traditional battery management system software,a fast software update program is designed to make the update program more convenient.After the hardware and software design is completed,the BMS test platform is built to test the design.The experimental results show that the current acquisition error of BMS is less than ±0.5A,the temperature acquisition error is less than ±0.5℃,the SOC estimation error is less than 4%,the SOH estimation error is less than 3%,the battery balance management is fast and accurate,and the software update program can be used to upgrade the software quickly.The physical slave control unit meets the requirements of this design. |
