Research On The Compound Power System Of Pure Electric Vehicle And Its Energy Management Strategy

Facing the problem of petroleum resources storage reducing day by day and increasingly strict emission standards of vehicles,the advantages of electric vehicles in energy saving and emission reduction have become more and more prominent compared with traditional fuel vehicles.However,as far as the market scale of development of electric vehicles is concerned,the vehicle's battery still many shortcomings in power density,cycle life and replacement cost.As a new energy storage device,ultracapacitor has the characteristics of higher power density,long service life and fast charging and discharging,which can complement the advantages of vehicle's battery.Combining battery and ultracapacitor into a hybrid energy storage system(HESS),which can exert the respective performance advances of the two energy storage devices,makes up for the shortage of a single power supply,and provides a new technical solution for the current power storage system of electric vehicles.The design of a scientific and reasonable HESS and its energy management control strategy can not only ensure the efficient performance of the HESS,but also minimize the total cost of the HESS.This paper focuses on the research of HESS equipped with an electric vehicle,including: structural selection of the HESS,component characteristics analysis,performance parameter matching design,energy management control strategy formulation and experimental simulation results analysis,etc.The research contents are as follows:(1)Based on the analysis of the common HESS topological structure and component characteristic of the HESS,the equivalent model of each component and the corresponding Simulink model of the HESS are established.According to the design requirements of the vehicle and combined with the cycle driving conditions,the performance requirements of the vehicle power system were analyzed firstly,and the performance requirements of the vehicle power system under cyclic driving conditions were calculated.Then,a method of matching the performance parameters of the HESS based on the typical cycle driving conditions was designed.The significance of this method is to make the matching of the parameters of HESS with good condition adaptability.(2)In order to control the energy distribution of HESS reasonably and effectively,the working mode and control target of HESS are analyzed firstly,and then the energy management strategy of HESS based on fuzzy control is designed.Because fuzzy control depends on expert experience in the design process,it has some problems such as strong subjectivity.A cuckoo search algorithm is proposed to optimize the fuzzy controller.The method keeps the rule of fuzzy control unchanged.the cuckoo search algorithm is used to optimize the fuzzy membership function to improve the performance of the fuzzy controller,so as to obtain the global optimal control.(3)Based on the MATLAB/ADVISOR platform,the simulation model of the original single-power electric vehicle is redeveloped and applied firstly,and the simulation model of the composite power electric vehicle is built.Then the parameter matching and its energy management strategy of HESS are simulated.The results show that compared with single power electric vehicle,the electric vehicle with HESS can improve the power performance of the vehicle;compared with the traditional fuzzy control strategy,the proposed method in this paper help the ultracapacitor to better exert its working performance potential,effectively reduce the input and output power of the battery,avoid the damage to the battery caused by frequent high current,and improve the economics of the vehicle's energy consumption.