Research On Coordinated Control Of Differential Drive And Differential Braking For Distributed Drive Electric Vehicle

The driving and braking torque of each wheel of the distributed drive electric vehicle is independently controllable,and it has the advantage of flexible longitudinal force distribution,which creates favorable conditions for the advanced control of the vehicle.Relying on the National Natural Science Foundation of China(51675257),this thesis takes distributed drive electric vehicles as the research object,makes full use of its advantages,and studies the coordinated control of differential drive and differential braking for its stability problems.The main research contents and methods of the thesis are as follows:First,carry out the modeling of distributed drive electric vehicles.Select the reference car model in CarSim and modify it based on the reference car model,including the modification of the transmission form and the modification of some parameters.The in-wheel motor model is established in Matlab/Simulink.CarSim and Matlab/Simulink are combined to establish the vehicle simulation model.Choose two simulation condition verifies the validity of the model.Secondly,carry on the research of differential drive control.Design a differential drive control strategy.According to the vehicle speed and front wheel angle information,based on the two-degree-of-freedom vehicle model,the expected values of the yaw rate and the side slip angle of the center of mass are calculated.The difference between the actual value and the expected value of the two parameters is used as the input of the fuzzy controller to calculate the required additional yaw moment.Formulate the drive torque rule distribution strategy,and select two simulation conditions to verify the effectiveness of the differential drive control.Third,the coordinated control of differential drive and differential braking is studied.Using the quadratic programming theory in optimal control,with the minimum tire load rate as the optimization goal,the road adhesion conditions,the maximum output torque of the motor,and the vehicle’s power and stability are constraints,and the longitudinal torque of each wheel is calculated.The driving torque is only produced by the motor,and the braking torque is produced by its reversal.The excess part is produced by the wire-controlled hydraulic brake system.Through the coordinated control of differential drive and differential braking,the stability of the vehicle is improved.At the same time,the response delay problem of the motor and the pressure delay problem of the hydraulic system are considered.And select the serpentine and double shifting working conditions for constant speed and variable speed simulation verification.Finally,the driving simulator hardware-in-the-loop simulation experiment is verified.The DLC and serpentine working conditions are selected,and the hardware-in-the-loop simulation experiment is carried out.The simulation verifies the effectiveness and real-time performance of the control strategy.The research results show that the researched distributed drive electric vehicle differential drive and differential braking coordinated control strategy can effectively improve the stability of the vehicle and ensure good real-time performance.