Study On The Control Strategy Of Regenerative Braking Of Four In-Wheel-Motor Actuated Vehicle

With hundreds of years of modernization,the auto industry continues to thrive.The dependence of traditional automobiles on fossil fuels has resulted in huge energy consumption,and exhaust emissions have also caused air pollution.With the promotion of national energy conservation and emission reduction policies and the awareness of people’s environmental protection,the electrification trend of automobiles is unstoppable.The four in-wheel-motor actuated electric vehicle is an advanced driving form of electric vehicle,and has many advantages in terms of dynamic control and transmission efficiency.Over the years,short driving range has always been a huge obstacle to the development of electric vehicles.In the short term,improving energy efficiency is an effective means to solve this problem under the constraints of battery technology.Braking-energy recovery technique can achieve the recovery of energy in the braking process and improve energy utilization.Compared with the traditional electric vehicle,the four in-wheel-motor actuated electric vehicle can independently control four wheel braking torque,so the energy recovery effect is better,and the research on its regenerative braking system is of great significance.In this paper,the regenerative braking control strategy of electric vehicle driven by four in-wheel-motor is studied.By analyzing the structural characteristics of the four in-wheel-motor actuated electric vehicle,the energy flow transmission process of the regenerative braking,and the influencing factors of the braking energy recovery,it is ensured that the braking energy recovery can be maximized on the basis of ensuring the safety of the vehicle brake.Based on the model predictive control method,the braking force distribution control strategy of the regenerative braking system is designed by considering the braking safety performance and energy recovery effect of the vehicle.By analyzing regenerative braking control system,the electric braking force and friction braking force of front and rear axles in regenerative braking process are taken as control objects.Based on vehicle dynamics theory,a three degree-of-freedom vehicle braking state prediction model is established.Vehicle speed-following,braking energy recovery effect and torque fluctuation in the process of vehicle braking are taken as optimization indexes in the control process.In the process ofregenerative braking,firstly,the braking strength,battery SOC,and motor speed are used as the external constraints of regenerative braking to judge braking mode.Then the motor maximum torque and tire slip is used as an internal constraint to solve the optimization process.Finally,the control of the regenerative braking system is realized by the rolling optimization calculation in the control process.The co-simulation platform for regenerative braking system of the four in-wheel-motor actuated electric vehicle was established by Carsim and MATLAB/Simulink software,and simulated under typical braking conditions and NEDC cycle conditions.The simulation results show that the designed regenerative braking control strategy has better control effect and good energy recovery effect.