Research And Design Of BMS Based On Improved EKF Algorithm For Estimating SOC

With the rapid development of new energy vehicles,the sales volume of new energy vehicles has increased rapidly,and the incidence of failures has also increased.The analysis of the causes of the failures has been mainly caused by the power battery pack.As one of the important characterization parameters of the power battery pack,SOC is especially important for ensuring the safe use of the battery pack.Accurate online estimation of SOC is the research focus of battery management system,and has important practical significance for the development of electric vehicles.In this paper,the DMC principle is used to identify the OCV parameters of the battery,and the equivalent circuit model parameters of the battery are corrected.Then,the extended CAMELL filter algorithm is used to estimate the battery SOC in real time.Finally,the software and hardware of the battery management system were developed and designed,and the following research work was carried out:The battery equivalent circuit model based on the second-order RC network is established.The OCV-SOC curve is identified through experiments.The relevant parameters of Ro,R1,C1,R2 and C2 in the equivalent circuit model are identified by HPPC experiments.The Simulink simulation platform was used to build a single-cell battery simulation model,and the accuracy of the model was verified by the measured data.The established battery simulation model is the basis of simulation research.Using Simulink to build an extended Kalman filter algorithm to estimate the SOC simulation model.Combined with the battery simulation model,the effects of systematic error and Gaussian white noise on the estimated SOC are analyzed under different working conditions.The simulation results verify that the Gaussian noise of voltage and current has a weak influence on the estimation accuracy,and the system deviation will have a greater impact on the estimation accuracy.Based on this,the sampling accuracy of the designed battery management system is established.The simulation model is used to simulate the influence of the OCV-SOC curve on the estimated SOC.The DMC algorithm is used to identify the OCV value online and update the model parameters in the extended Kalman algorithm to improve the estimation accuracy.Modeling and analysis of DMC,using the voltage in RC network as the output,using step response to describe the RC network in the battery model,linearizing the battery equivalent model,using the least squares method to linearize the system model The OCV identification is performed,the algorithm is simplified,and combined with the extended Kalman filter algorithm,the SOC estimation accuracy is improved.Hardware design of the battery management system according to system requirements.The design of each module circuit of the main control board and the voltage acquisition slave board is completed.Improve the anti-interference ability of hardware from multiple aspects in PCB design.Based on the designed hardware,the corresponding software design is completed,and the corresponding communication protocol is developed to realize the estimated SOC algorithm based on the DMC principle.Debug and experiment with the designed system hardware and software to verify its function and reliability.Experiments show that the SOC estimation accuracy is less than 5%,which proves the effectiveness of the battery management system based on the DMC principle for estimating SOC.