Research On Coordinated Control Strategy Of 4WID All Electric Vehicle Wheel Drive Motor

Four-wheel independent drive(4-Wheels Independent Drive,4WID)electric vehicles use four hub motors as the source of driving force.When the vehicle is turning,the wheel speed of each hub motor is directly controlled based on the Ackerman steering model to achieve electronic differential(Electronic Differential,ED).However,the traditional electronic differential speed control is difficult to coordinate the speed and torque of each motor when the vehicle load changes and load disturbances,which affects driving safety and stability.Therefore,this article aims to improve the coordination of 4WID electric vehicle wheel drive motors,and conducts research on the 4WID electric vehicle electronic differential algorithm:First of all,it discusses the development status of electric vehicles at home and abroad,analyzes the problems existing in the traditional structure and control of electric vehicles,and explains the outstanding advantages of 4WID all-electric vehicles in terms of such problems,combined with the synchronous control of multiple motors.Research status,determine the research plan for the coordinated control of 4WID all-electric automobile in-wheel motors.Secondly,according to the actual vehicle parameters of "Daqin No.2",the car model structure parameters and transmission system in Carsim were modified,and the 3 degrees of freedom 4WID all-electric vehicle dynamics model and 4 degrees of freedom wheel dynamics were constructed based on the MATLAB/Simulink simulation platform.model.Based on the CarSim/Simulink co-simulation,the accuracy and validity of the established 4WID all-electric vehicle model is verified under the double-line shifting condition.Third,for the speed-type electronic differential control four-wheel independent traction all-electric vehicle,the ability to coordinate and control the wheel torque is poor,and the torque drag problem of the front and rear traction wheels may be caused during the steering process,and a "virtual motor" is proposed.Speed control strategy combined with electronic differential speed.The torque disturbance of the inner and outer wheels is fed back to the virtual motor through the wheel coupling coefficient,and the output speed of the virtual motor is adjusted in real time according to the magnitude of the torque disturbance.The simulation and experimental results show that the improved control strategy improves the coordination of the speed electronic differential to the torque The control ability solves the torque drag problem of the front and rear traction motors.Then,by analyzing the basic principles of the multi-motor deviation coupling control algorithm,aiming at the fact that the traditional deviation coupling control structure cannot meet the differential speed requirements of the four wheels when the 4WID all-electric vehicle is steering,an improved deviation coupling based on the Ackerman steering principle is proposed.The control strategy uses the Ackerman steering model to extract the differential speed coefficient to improve the synchronization error compensator of the deviation coupling structure,and realizes the reasonable distribution of the wheel speed during the vehicle steering process.Finally,based on the hierarchical control system structure of the CAN bus,the power circuit and the control circuit of the whole vehicle,a real-vehicle experimental platform of the"Daqin Ⅱ" 4WID all-electric vehicle is built,and the proposed control strategy is verified by experiments based on DSP TMS320F28335 and RT Box,Which shows the correctness and effectiveness of the proposed control strategy.