Research On Matching And Torque Distribution Of In-wheel Motor Drive System For Wire Controlled Chassis

In recent years,with the rapid development of artificial intelligence and modern control technology,intelligent driving has become a research hotspot in the field of automobile.As the bottom implementation system of intelligent driving,wire-controlled chassis also needs to follow the development of technology.In-wheel motor is one of the distributed wire-controlled drive technologies.Compared with the traditional centralized drive system,it has many advantages such as high degree of freedom and high transmission efficiency.The combination of in-wheel motor and wire-controlled chassis will be the new trend of the development of new intelligent chassis.Based on this,this paper focuses on the in-wheel motor drive system for the wire-controlled chassis,and the main contents are as follows.Firstly,the longitudinal kinematics of the vehicle is analyzed theoretically,and the power balance equation of the vehicle is determined.Combined with the driving conditions and applicable requirements,referring to the basic parameters of the pure electric vehicle,the dynamic and economic indexes of the vehicle are designed,and the types of common drive motors and power batteries are compared and analyzed.According to the power system matching theory of the pure electric vehicle,the in-wheel motors and power batteries are selected and matched.Finally,the vehicle model is built in AVL CRUISE,and the correctness of the matching design is verified by simulation.Secondly,through theoretical analysis,it is found that when the total output power of the drive system is constant,the optimal torque distribution problem of the in-wheel motor drive system can become the problem of the minimum total loss power of the drive system.The equivalent circuit of PMSM considering loss is established and mathematical analysis is carried out.According to the mathematical model of PMSM considering loss,the motor loss model in steady state is established.When the pure electric vehicle is equipped with four in-wheel motors with the same parameters,the mathematical model of the loss of the distributed motor drive system is established.Then,how to control the torque distribution of the four wheels to minimize the loss of the drive system under the straight driving condition without yaw control and ignoring the tire slip rate is studied.Mathematical analysis shows that the average distribution of total required torque to four wheels may minimize the loss power of the whole drive motor system.Finally,aiming at the problem that the analysis accuracy based on the system loss model is not enough,under the premise of considering the system loss,the optimization objective function is established based on the system efficiency MAP diagram.The data in the efficiency MAP diagram are input as the optimization variables,and the results are output in the form of offline optimization through the conditional constraints on the relevant variables.The results are compared with the torque distribution results without considering the no-load loss of the motor.Then,the model was built in MATLAB / Simulink,and the model was compiled and transformed into dll file.The ECE cycle condition was selected,and the power consumption of the torque distribution strategy considering loss and the torque distribution strategy without loss under the same condition was analyzed and compared.The simulation results show that the torque distribution strategy considering loss makes the distributed drive motor work in a high efficiency range,and the power consumption under ECE driving condition is reduced by 3.4 %,which optimizes the energy efficiency of the in-wheel motor distributed drive vehicle.