| With the rapid development of the automotive industry,the problem of environmental pollution brought about by more and more serious.Electric vehicles as a representative of energy conservation and environmental protection are favored by the majority of people.Among them,low-speed electric vehicles stand out due to their superior economic performance and convenient charging.This subject takes low-speed electric vehicle lithium battery as the research object,and conducts in-depth research on its management system hardware design,software design and key technology SOC estimation.The main work is as follows:(i)Aiming at the problem of estimating the influence of the initial value of SOC in the previous period and estimating the influence of the influence factor in the traditional estimation method,this paper proposes an improved method for estimating the AH integration method.The OCV-SOC curve obtained by the open circuit voltage method is first corrected,and then the accurate SOC initial value is obtained by the open circuit voltage method;then the temperature influence factor and the discharge current influence factor are added to the conventional ampere-hour integration method to achieve the battery SOC.The dynamic estimation;Finally,experiments show that the improved algorithm has a significant improvement in the estimation accuracy.(ii)For the problem of estimating the accumulative error in the later period for the Amgen integral method,a modified estimation strategy for the extended Kalman filter algorithm is proposed.First analyze the current battery model in depth,choose the battery model that is suitable for the research,and model the battery;analyze the idea of the extended Kalman filter algorithm and use Kalman filter’s "prediction-correction-re-prediction-recorrection" idea The SOC estimation was performed on the battery,and the error of the improved AH integration method was corrected and verified by experiments.The proposed method can effectively correct the cumulative error of the Ah-total integration method.(iii)Based on the idea of embedded hardware component and the principle of embedded software design,a battery management system is proposed and designed with NXP Semiconductors MKE06Z64 as the main control chip and Rom ML5238 as the battery acquisition chip.Complete the battery management system hardware design,including battery voltage acquisition circuit,battery current acquisition circuit,battery equalization circuit,CAN bus circuit,and software design,including information acquisition module,SOC calculation module,battery equalization module,etc.;finally completed in C# Lithium battery management system PC monitoring software design.It can be found through the experimental results that the SOC estimation algorithm designed in this project can achieve high precision in the designed battery management system,and can keep the estimation error within a small constant range.At the same time,the lithium battery management system designed by this project is also available.No matter in voltage detection or current detection,high detection accuracy can be achieved. |
