Research On Four-wheel Drive Electric Vehicle Four-wheel Drive Control Based On Drive Torque Distribution

As the main mode of transportation in the future,electric vehicle driven by electric power has attracted more and more attention in the world due to its excellent zeroemission and environment-friendly characteristics.At the same time,the response speed of the driving motor is fast and the control is accurate.Through the wheel side arrangement of the motor,the driving force distribution of the vehicle can be realized flexibly,and the accurate control effect of each wheel torque can be achieved.In this paper,the former rear-axle motor driven electric vehicle as the research object,the front and rear axle drive torque distribution mode and drive anti-slip technology were studied,in order to ensure the longitudinal acceleration ability of the vehicle and improve the vehicle resistance to lateral interference ability.In this paper,multiple vehicle models and different simulation conditions provided by CARSIM software are used to jointly develop the control system of electric vehicles with Simulink software,and the established control model is verified by offline simulation and tested by HIL.The main research contents are as follows:(1)Based on the vehicle dynamics model architecture,the key component models that CARSIM could provide were matched with real vehicle parameters,and the motor and driver models that CARSIM could not provide were built in Simulink.Finally,through the simulation test of the vehicle model,the results show that the vehicle model can meet the expected requirements.(2)Based on the requirement of four-wheel drive control system,the architecture of vehicle four-wheel drive control system was built.When the vehicle is driving in a straight line,based on the most efficient distribution method of the driving system,a set of optimal distribution coefficient diagrams of the motor torque of the front and rear axles are obtained,which makes the motor work in the optimal efficiency range and improves the driving economy of the vehicle;Under steering conditions,the torque distribution coefficient of front and rear axle motor is obtained by PID control of the deviation of expected and actual yaw rate to restore the stable operation of the vehicle.(3)The five-degree-of-freedom vehicle model and wheel rolling dynamics model of electric vehicle were established,and the adhesion characteristics between tires and road surface were analyzed when the wheel skidded.The logic threshold control strategy is selected from several typical driving anti-slip control strategies and based on this,the driving anti-slip algorithm is developed.Finally,dynamic control is carried out on the drive anti-skid output torque.When yaw motion control and drive anti-skid control function at the same time,the front and rear axles are coordinated to control the torque distribution to ensure the safe running of the vehicle.(4)The typical conditions were selected from CARSIM to carry out offline simulation and verification of yaw rate control strategy and drive anti-slip control strategy.The simulation results show that the designed anti-skid control strategy can achieve a better control effect under different linear driving conditions and reduce wheel slip.The yaw rate control under steering condition can ensure the normal steering of the vehicle and improve the lateral stability of the vehicle.(5)Based on the completed LABCAR HIL platform test environment,the semiphysical simulation of the driving anti-slip control strategy and the yaw rate control strategy was carried out.The experimental results show that the developed algorithm has a good control effect under some typical working conditions.