Research On Regenerative Braking Control Strategy For Electric Vehicle Based On Mass And Road Slope Estimation

Facing the current severe energy crisis and environmental pollution problem,pure electric vehicle,as a new modern transportation tool,is highly sought after by all vehicle companies for its zero emissions,pollution-free and no need to rely on traditional energy sources.However,influenced by the research technology of power battery,the unsatisfactory driving range of pure electric vehicle has seriously affecting its large-scale promotion.Therefore,extending the driving mileage is the key problem to be solved for the current pure electric vehicle.The technology of regenerative braking can transform the kinetic energy of the vehicle when it is braking to electric energy stored in power battery to increase the SOC of battery,so as to extend the driving range of vehicle.Considering the influence of geographical factors and development trend in China,it is of great significance to research the regenerative braking control technology based on mass and road grade estimation for the development of pure electric vehicles.The subject of a precursor of pure electric vehicle as the research object,through the estimation of brake mass and road slope angle of the vehicle when driving a vehicle at the front and rear axle construction strategy of braking force distribution and regenerative braking control,the vehicle braking process and the braking stability and braking safety under the premise,increase the regenerative braking energy recovery.The main contents of this paper are as follows:(1)Design and implement a vehicle CAN bus quality and road gradient angle estimation algorithm based on RLS(Recursive Least Squares).Firstly,the vehicle travel equation is analyzed and derived,then the CAN bus data and the vehicle inherent attribute parameters are extracted or set in the ASM model.Finally,the obtained mass and slope angle are filtered by the RLS algorithm.(2)Design and implement a dynamic optimal allocation algorithm for front and rear axle braking force in braking process of pure electric vehicles based on different braking strengths and different road slope angles.First of all on the slopes of vehicle front and rear axle braking force analysis,and then put forward the ideal braking force distribution,the proportion of fixed proportion and the proportion of three kinds of variable distribution,finally the braking needs to meet ECE R13 braking regulations,the rationality and validity of the verification of variable proportion optimization allocation algorithm.(3)Design and implement a regenerative braking control strategy based on downhill section.First,considering the regenerative braking characteristics of motor,the redistribution of front axle braking force is made,so that the vehicle regenerative braking can recover the most energy under the premise of meeting the motor characteristics and battery characteristics,and then extend the vehicle’s mileage.(4)The mass and road slope angle estimation algorithm and the regenerative braking control strategy based on the downgrade section are simulated.In the MATLAB/Simulink simulation environment based on ASM model,we first built the mass and road slope angle estimation model,and carried out the simulation test on fixed road slopes,which verified the effectiveness of the estimation method.Then the regenerative braking control strategy model was built,and the simulation experiment was carried out under the UDDS city road cycle condition and the different fixed slope angle.The experimental results show that the design and construction of the regenerative braking control strategy model based on mass and road gradient estimation is more efficient in braking energy recovery,and the effectiveness and feasibility of the strategy are verified.