Electric Vehicle Battery Management System And Its Control Strategies

The problems of exhaust emissions and resource consumption brought by traditional fuel vehicles have become increasingly serious.As a kind of green transportation,electric vehicles have become the focus of technological research in various countries.Electric vehicles are powered by batteries,so battery management systems are a very important part of EV technology.Battery management system with battery status information,balanced management,battery SOC(State of Charge)estimates and other functions,can extend battery life and improve battery utilization,to ensure safe and stable operation of the battery.In this paper,we first design a battery SOC estimation method,through the comparison of different battery SOC estimation methods,using extended Kalman filter to estimate the battery power.Extended Kalman filter with high precision,good convergence and other advantages.In view of the highly nonlinear characteristic of Li-ion battery during its use,this paper considers the factors of battery polarization and other factors,and uses extended Kalman filter to improve the accuracy of SOC estimation.By building the model in Matlab / Simulink and simulating it,the extended Kalman filter method can accurately estimate the battery SOC.Second,this paper designed a battery active balancing control strategy.Batteries in the production process will have individual differences,different working environment will lead to increased battery inconsistencies,thereby shortening the battery life and reduce the battery utilization.In order to ensure the consistency of the battery,after comparing a variety of battery equalization methods,this paper uses constant current source charging initiative balanced.The battery simulation model and the equilibrium simulation model are built in Matlab / Simulink.The simulation results show the efficiency of the equilibrium strategy.The experiments show that the equilibrium strategy in this paper can operate reliably and steadily in practice.Finally,the BMS platform is built around the SOC estimation and active equalization of lithium-ion battery.The hardware and software components of the BMS are designed.The functional tests of the designed system are carried out through experiments.Detection circuit and acquisition unit detection circuit to ensure the balance,acquisition and other functions of the stable operation.Through hardware and software joint commissioning and on-board experiments,verify that the battery management system in this paper can run stably on electric vehicles.