The Design Of The Equalization Management System Of Electric Vehicle Battery

The problems of the energy depletion and environmental pollution have become the urgent needs to deal with in the current society,and electric vehicles are widely used by people with the advantages of energy saving and environmental protection.So the electric vehicle industry is developing rapidly.The efficiency of the use of battery packs has become a key factor in its endurance.The inconsistency in battery's process of production,storage and use affects the overall performance of electric vehicles.And the inconsistency will be further aggravated by the battery's various variables.Then the phenomenon of the deterioration of vehicle's overall performance has appeared.The introduction of equalization technology can improve the problem of the inconsistency between each cell batteries effectively.The equalization module in the equalization management system can monitor the performance of battery pack in real-time,and analyze the data collecting from each indicator,and make warning and alarm timely,and then discover the damaged cell in the pack timely.This method can discover the overall performance of the pack by the damaged cell monomer,and improve the battery efficiency in the process of battery charging and discharging.The main work of this paper is as follows:1.The reasons of the inconsistencies between each battery and their further intensification are analyzed from three aspects of battery ' s process production,storage and use.And the effects of inconsistency on battery performance are pointed.This article selects the equalization technique as a method to eliminate the inconsistency between batteries and introduces active equalization method and passive equalization method after the introduction of several methods to eliminate the inconsistency.2.The selection and the function of the micro-controller,the charge control module and thecollection,display and storage module of the data of battery and other module has been introduced detailedly.The circuit of the bi-direction topology equalization structure is established based on the energy storage element.After then,a completed equalization management system is established.3.The cell charging voltages(CCVs)based equalization method and the State of Charge(SOC)based equalization method are compared by a certain type of battery.This article selects the SOC based equalization method after the comparison of the advantages and disadvantages of these two kinds of equalization method.On this basis,cell and battery pack models is established.And SOC is estimation by the algorithm of the particle filter(PF).4.Accuracy of SOC-PF method.Under the same conditions and with the same object,simulation experiments are carried out with the method of the extended kalman filter and particle filter especially.According to the experiment,the performance of these two equalization methods is analyzed by the root-mean square error(RMSE)and the maximum absolute error(MAE).The results show that the PF has a relatively higher accuracy of SOC estimation than the EKF method.5.The first high-SOC cell discharge and first low-SOC cell charge equalization algorithms are proposed based on the PF-SOC,which are applicable.