Research On Electronic Differential Control Of Independent Driving Hub Motor Of Electric Vehicle

Independent drive electric vehicle is different from fuel vehicle,it has no complex transmission structure,but it has the advantages of energy saving and body lightweight,and it’s the main object of new energy vehicle research and development.More and more research institutes and high-tech enterprises carry out technology research and product development of independent drive electric vehicle.The electronic differential control(EDC)technology is used to coordinate the driving attitude of each independent driving wheel synchronously,which makes the differential control more complex.And the independent drive electric vehicle has higher requirements for EDC under multiple driving conditions,such as steering,driving anti-skid,anti lock braking,yaw control,ramp start and stop,so as to prevent the vehicle body from being unbalanced due to sliding and ensure driving safety.Therefore,the research on EDC technology of independent drive electric vehicle has important theoretical and application significance for improving the driving safety and stability of electric vehicle.In order to improve the effect of differential control,this paper studies the active disturbance rejection of EDC of electric vehicle.(1)The working principle,mathematical model and the control strategy of permanent magnet BLDCM are described.And a more mature hysteresis comparator is used to act on the current loop,and a first-order nonlinear ADRC is used to act on the speed loop.Then the first-order nonlinear ADRC based on the speed is designed.The classical PID control link and the first-order nonlinear ADRC link are respectively embedded in the speed loop,and the Matlab / Simulink simulation model of the permanent magnet BLDCM control system is built;Availability of simulation model of double closed loop control built by Simulation Research Institute,and the result shows that compared with the classical PID controller,the first-order nonlinear ADRC has the advantages of compatibility,rapidity and stability.(2)An EDC strategy based on Active Disturbance Rejection Control(ADRC)is proposed for electric vehicles with front wheel rotation and rear wheel drive.The strategy embeds ADRC in slip rate control module and yaw motion control module respectively.In order to prevent wheel offset and ensure the handling stability of the vehicle in the steering process,a second-order nonlinear ADRC based on the slip rate is designed,and the parameters of ADRC are adjusted by the chaos particle swarm optimization(CPSO)algorithm to achieve the control of ADRC.And In order to prevent vehicle attitude imbalance and ensure vehicle driving safety,a first-order linear ADRC based on yaw rate is designed.CPSO is used to adjust the parameters of the first-order ADRC to realize the control of yaw motion.Finally,the real-time values of the output driving torque and yaw moment are taken as the input,and the torque coordination control module is built.Because the slip and yaw are controlled by ADRC,the torque distribution of the internal and external driving wheels is more reasonable when the car turns.(3)The eight degree of freedom dynamic model and the ideal two degree of freedom dynamic model of the whole vehicle are built.Based on the tire model,the road identification model is designed and built.Based on the active disturbance rejection algorithm,the first and second order ADRC models are built;Combining motor model,double closed-loop control strategy and EDC strategy with active disturbance rejection,the system simulation model of electric vehicle with permanent magnet BLDCM is built in MATLAB/ SIMULINK;Under different road conditions(such as smooth road,butt road and split road)or loads,the simulation monitors the actual slip rate,yaw rate and driving wheel torque,and verifies the anti-interference effect of the designed EDC strategy.The designed control strategy can have a very good identification of the changes of the external complex road conditions,ensure the handling stability and safety of the car when turning,and improve the differential control effect in the steering process.(4)A 5kW controller is built with TMS320F28069,which is the controller chip of TI company.The designed electronic differential controller is compiled into a library file and loaded into the vehicle controller using CCS5.5 software platform.Experiments are carried out on smooth road surface,butt joint road surface and split road surface.The experimental results are analyzed to demonstrate the feasibility of the designed electronic differential control strategy and verify the correctness of the theoretical model.