| In order to solve the problems of reducing fossil energy and increasing the difficulty of mining and environmental pollution,governments have gradually increased their investment in the clean energy industry,especially in the clean energy automobile industry.At present,the main power source of clean energy vehicles is electric energy.As the main power supplier,power battery,its related research has attracted much attention from the industry and academia.However,the research of power battery spans many disciplines,such as electrochemistry,condensed matter physics,automation,mathematics and so on.It has become a research hotspot and difficulty.Especially in the research of power battery modeling theory,the traditional integer order method is mostly used at present,but the model accuracy is low.In fact,power battery is a typical fractional-order system in essence.Only by studying fractional-order modeling method can the accuracy of battery model be improved effectively.So the research focus of this paper is as follows:Firstly,taking lithium-iron phosphate battery and ternary lithium battery as research objects,the external characteristic parameters are analyzed,the charging and discharging test scheme of power battery is designed,and the relevant test platform is built,and the test data of battery at 25℃ are obtained.This data provides abundant raw data support for the next step of power battery modeling,state estimation and comprehensive evaluation software design.Secondly,the fractional equivalent circuit modeling method of power battery is studied,and fractional order calculus theory is used to identify the fractional-order of the equivalent circuit model.That is to say,by analyzing the time constant of the circuit,the fractional-order is determined by the method of interval quadratic partition,and then the model parameters are fitted by the non-linear least squares algorithm.The experimental results show that the fractional-order model has higher accuracy than the integer order model.Then,the upper computer software of battery model parameter identification and state estimation is designed and integrated into the comprehensive evaluation software of power battery.The comprehensive battery evaluation software based on Lab VIEW programming language is designed,and the joint programming of embedded MATLAB language is realized,which greatly improves the computing ability of the software.At the same time,MySQL database with strong recording ability and high portability is used to design database architecture with excellent real-time access performance.The comprehensive evaluation software for power battery can realize automatic matching of battery data and algorithm,display the evaluation results in intuitive radar graphics,and finally complete one-click comprehensive evaluation of battery performance. |
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