Research And Simulation Analysis Of Regenerative Braking Control Method Of Electric Vehicle Based On Fuzzy Control

The development of electric vehicles has become an inevitable trend in the world.Compared with traditional internal combustion engine vehicles,the problem of short endurance mileage has become a key problem to limit the development of electric vehicles.In 2019,the newly introduced subsidy for new energy vehicles in China fell sharply.According to the subsidy standard of pure electric passenger vehicles,not only the endurance mileage standard required by the subsidy had been greatly improved,but also the energy density requirement of battery pack had been increased.The technical bottleneck of power battery can not be broken in a short period of time.The energy density potential of ternary lithium battery had been almost exploited.The mass production of graphene battery still needed a long time.So the technology of regenerative braking had become an effective method to improve the range of electric vehicle.In this paper,FSAE electric vehicle driven by axle is the research object,in order to achieve the coordinated control of mechanical braking system and motor braking system when the electric vehicle is braked,and improve the range.For the control strategy of regenerative braking system,the main research contents and achievements are as follows:Describes the basic principle of electric vehicle,and the studies relationship between the realization process of regenerative braking and the energy of electric vehicle.This paper introduces the structure of regenerative braking system,and analyzes the mechanical braking system,driving motor and battery energy storage system of electric vehicle.The driving condition,the electric vehicle itself and the control strategy are studied.It is found that the brake control strategy is the key factor to affect the regenerative braking under the condition of meeting the constraints of the battery and the motor.The dynamic analysis of vehicle braking process is carried out,and the traditional braking force model and the 7-DOF non-linear geometric simplified model of vehicle suspension are established.The influence of non-linear deformation of suspension on front and rear axle loads during braking of electric vehicle is considered.Based on the vehicle braking dynamic model,the braking force distribution of front and rear axles during braking is analyzed.To ensure the braking stability of the vehicle,the front and rear axle brake distribution must meet the I curve.Further,to ensure the safety of vehicle braking,the braking force distribution of front and rear axles should meet the requirements of ECE regulation on car braking.Combining ADVISOR2002 regenerative braking strategy,parallel braking force distribution strategy and coordinated braking force distribution strategy,this paper puts forward a regenerative braking strategy based on dynamic axle load.This strategy puts forward a calculation method based on dynamic axle load of wheels and a calculation method based on optimal slip for road adhesion coefficient,which utilizes the dynamic axle load of wheels and road adhesion system.The braking force of front and rear axle wheels is calculated numerically to distribute the braking force between the front and rear axles of an electric vehicle.A fuzzy logic control model with braking strength,speed and battery charging state(SOC)as input variables and expected regenerative braking force coefficient as output variables is established to distribute the mechanical friction braking force on the drive shaft and the regenerative braking force of the motor.The models of each system of the electric vehicle are built in ADVISOR,and the forward and backward simulation regenerative braking models of the regeneration strategy proposed in this paper are built in MATLAB/Simulink environment.Embedding the regenerative braking model of electric vehicle into ADVISOR2002,three kinds of cyclic working conditions,UDDS,EUDC and 1015,are selected for simulation,and compared with ADVISOR’s own control strategy.Finally,the simulation results under three cycle conditions show that the regenerative braking strategy improved in this paper is effective.Finally,through the study of regenerative braking control strategy for electric vehicle,the theoretical basis for the practical application of regenerative braking technology on FSAE electric vehicle is provided.