Research On Electro-hydraulic Composite Braking System Of Four-wheel Hybrid Electric Vehicle With Brake Electronic Booster

As a unique product of new energy vehicles,the electro-hydraulic composite braking system,which retains the safety and reliability of the traditional braking system,adds braking energy recovery technology,and becomes a key technology in the way of energy saving and emission reduction of new energy vehicles.Regenerative braking system recycles and reuses the kinetic energy and potential energy in the braking process of vehicles,which plays an important role in energy saving and emission reduction of vehicles and improving the endurance mileage.Decoupled electronic booster braking system is beneficial for hybrid electric vehicle regenerative braking system to achieve active braking,better coordination of electro-hydraulic composite braking,and ensure the efficiency of braking energy recovery.In this paper,a decoupled electronic booster with failure protection is designed for a CVT hybrid electric vehicle driven by front and rear axles with two motors.Aiming at the goal of braking performance and braking energy recovery efficiency,the braking system of the vehicle and the braking force distribution strategy of electro-hydraulic composite braking are theoretically analyzed and parameters are set up.Design,vehicle modeling,simulation analysis,braking performance and braking energy recovery effect evaluation provide reference for the in-depth study of hybrid electric vehicle braking system.The research contents of this paper are as follows:(1)According to the characteristics of the target vehicle,the traditional brake booster is analyzed,and a new decoupled electronic booster is designed.According to the analysis of the boost characteristics of the traditional vacuum booster and the braking requirements,the parameters of the relevant components of the electronic booster are designed.The structural design of the electro-hydraulic composite braking system is carried out around the braking safety and braking energy recovery requirements of the vehicle.(2)Using sliding mode variable structure control method,the pedal position corresponding to the motor demand torque conversion controller is designed,and the motor vector controller is established by vector control method to control the motor input signal and realize the motor torque stable output,so that the vehicle hydraulic braking system can realize the regenerative braking process,and the hydraulic braking force can be dynamically adjusted according to the motor braking force.The dynamic model of key components of hydraulic braking system is established.(3)According to the vehicle dynamics analysis and the characteristics of the target vehicle,the braking force controller model such as braking force distribution strategy is built in Simulink environment,the vehicle model and the complete hydraulic braking system model are built in AMEsim environment,and the simulink-AMEsim joint simulation platform is built.(4)In the joint simulation model,the braking performance and energy recovery effect of vehicle braking system under typical working conditions are simulated and analyzed.The simulation results show that the braking system meets the requirements of vehicle braking safety,and the braking energy recovery efficiency is high.Hydraulic braking force can be adjusted dynamically according to the changes of motor braking force and braking demand.The braking performance of the system is verified under ABS control,which provides a reference for the optimization and in-depth study of hybrid electric vehicle electro-hydraulic braking system.