Research And Design Of Power Battery Management Systerm For Pure Electric Vehicle

Considering the crisis of energy and environment and the requirement to revitalize domestic automobile manufacturing industry,the government has paid more attention to developing electric vehicle industry in recent years.As the key components,power battery and its management system are increasingly being taken seriously.However,due to the highly non-linearity of battery,the complex coupling relationship with working conditions and the lack of battery's group application technology,the performance of battery management system is not satisfactory.There are still many problems,such as the poor accuracy of State-of-charge(SOC)estimation,the phenomenon of over-charging or over-discharging for improper control method,the short mileage,and so on.The equivalent circuit model of the experimental battery was established based on the research on the characteristic of NCM Lithium-Ion battery,whose parameters of charging and discharging direction were obtained by fitting the experimental data of pulse charge / discharge experiment,and the high simulation precision was verified by correcting the modified HPPC experimental data.According to the equivalent circuit model,then the state equation and the observation equation of the EKF algorithm were created.And then,the algorithm was achieved by using S function in Simulink.At last the algorithm was tested by the HPPC and custom dynamic operating conditions,which proved that the estimation error of SOC was less than ±3% and the algorithm had good convergence.Based on the functional requirements of the battery management system,the software and hardware of each function module of the system were designed.On the basis of the equivalent circuit model of the single cell,the incremental model was presented in this paper to simulate the non-consistency of the battery pack.With the dSPACE simulator,a set of hardware-in-the-loop test system was built,which was composed of the complete simulation environment and the software and hardware testing platform.Then the test for BMS was completed by using this test system.The result showed that,the BMS designed in this paper realized the measurement of the voltage,current,and temperature and the effective control for the charging and discharging process.The error of the estimation of state of charge(SOC)was less than ± 5%,and the accuracy satisfied the industry requirement that prescribed the estimation error was less than ±8%.