Research On Coordinated Control Of Mechanical And Electrical Compound Brake System For Electric Vehicle

With the environmental and energy issues getting increasingly severe,energy-saving and environmentally friendly electric vehicles have greatly developed in the automotive industry.Among the key technologies of electric vehicles,regenerative braking can effectively improve the fuel economy of vehicles by recovering kinetic energy during deceleration or braking.In order to achieve higher regenerative efficiency and ensure the braking safety of vehicles,regenerative braking should be used in coordination with hydraulic braking.Based on a full analysis of the research status on the electromechanical composite braking system from home and abroad,this paper takes the pure electric vehicle with the front-wheel drive as the research subject and conducts the research on the electromechanical composite system under two different braking conditions,normal braking and emergency braking.The main contents of the work completed are as follows:(1)The structure of the electronic hydraulic braking system is optimized according to the performance requirements of the electromechanical composite braking system of the pure electric vehicle.The simulation models required for control are established,including the EHB model of electronic hydraulic braking system,1/4 vehicle dynamics model and sliding rate calculation module,battery model,and tire model.The braking mode discrimination strategy is designed catering to different braking conditions.(2)A composite braking torque distribution control strategy is designed based on the concept of layered control for normal braking.The upper layer is based on the ideal braking force distribution curve.The braking torque of the front and rear axles of the pure electric vehicle is redistributed according to ECE R13 braking regulations,in order to meet the requirements of braking safety.Targeted at the braking energy recovery efficiency,the lower layer adopts the fuzzy control algorithm for the composite braking torque distribution of the front axle.(3)Based on the model predictive control method,the sliding rate tracking controller under emergency conditions is designed to coordinate the control of the electromechanical composite braking system of pure electric vehicle.Road adhesion conditions are used to identify and estimate the optimal sliding rate in real time.The braking torques of the front and rear axles are taken as the control input,and the wheel sliding rate is tracked to optimize the optimal braking torque that meets the constraint conditions,so as to realize the distribution of the braking torque of the front and rear axles of the pure electric vehicle.A braking torque distribution strategy with braking energy recovery as the goal is designed to complete the composite braking torque distribution of the front axle of the pure electric vehicle.(4)Based on the established simulation model and the electromechanical braking control strategy designed under different braking modes,the simulation experiments are carried out in the automotive simulation software Advisor and Matlab/Simulink to verify the control strategy in this paper.