Modeling And Research On Hybrid Energy Storage System And Control Theory For Electric Vehicle

In recent years,the Chinese government takes environmental protection as a national critical development strategy,vigorously promote the research of electric vehicles and its popularity.However,the development of electric vehicles is restricted by the performance of on-board batteries,which leading to poor dynamic performance,limited driving range and high-maintenance cost.In this background,this paper puts forward a Hybrid Energy Storage System(HESS),which combining with batteries and ultra-capacitors,and design a power distribution strategy.A reasonable hybrid energy storage system can make up for the deficiency of batteries and improve the driving performance of electric vehicles.This paper focuses on the analysis of the charging characteristics,discharge characteristics and the capacity of batteries and ultra-capacitors.Moreover,this paper studies the differences between the two batteries in the process of charging and discharging.Based on this,it improves the structure of the traditional single battery and proposes the semi-active structure between the battery and the super-capacitor.This way can effectively solve the problem that the traditional single battery cannot be actively controlled.On the basis of this structure,combining with the technical requirements on EVs in New Pure Electric Passenger Car Enterprise Management Regulations,and composite of pure electric vehicle drive motor power supply parameters matching.Then we can determine the drive motor voltage,power requirements,as well as the related parameter of lithium-ion battery monomer and super-capacitor monomers,such as voltage,capacity,power,and so on.Afterwards,a corresponding model is established in the ADVISOR software.In order to effectively solve the problem of power distribution between the battery and the ultra-capacitor,a bi-directional DC/DC converter module and a power bus module are established and added.On this basis,this paper designs a velocity-based fuzzy control system,which can identify the different models between power supply and power bus braking.In order to make more reasonable composite power control and more rational distribution of power flow,the system has two work modes,and each working mode has different fuzzy control rules.Through in-depth research on the secondary redevelopment of ADVISOR software,the simulation platform of a pure electric vehicle supplied with embedded ultra-capacitor hybrid energy storage system is established.Moreover,reasonable vehicle cycle conditions were designed,and simulate the complete vehicle in this paper.Compared with the traditional single power supply system,the simulation results show that: the ultra-capacitors distinct improve the charging and discharging performance of the battery,slow down the decline rate of battery SOC.In addition,hybrid energy storage system significantly improved the vehicle acceleration performance reach up to 17.65%,and driving range increase 24.95%,so as to make up for the battery power shortage and extended its cycle lifetime.