Independent Torque Distribution Method Of 4 In-Wheel Motor Drive Electric Vehicle For Steering

Now all cars are almost driven by internal combustion engine, however, with the outbreak of oil crisis in the last century, energy security had caused great attention of countries. Meanwhile, more and more internal combustion engine vehicles have caused serious pollution because of its emission that has brought great threat to people's health. As people's awareness of environmental protection, there is an urgent need for more environmentally friendly, safe means of transportation. The development of electric vehicle gets more and more people's attention. As a special form of EV, four in-wheel-motor drive electric cars have more advantages, such as simple structure, high transmission efficiency and space utilization. Four in-wheel-motor drive electric vehicle is directly driven by four motors, when it steers, the four wheels travel different distance, so the torque of each motor has to control separately.To study the method of steering torque distribution of the four-wheel independent drive electric vehicle, this paper has established a seven DOF nonlinear vehicle model which including vehicle longitudinal motion, lateral motion, yaw motion and four wheels turning. In order to make vehicle model better reflect the state of the car, then a "Magic Formula" tire model has been established. For the special structure of the hub motor, this paper has researched the motor and built a brushless DC motor model. Because of the brushless DC motor model is controlled by speed but what I need is torque, so this paper has established a simplified model of the DC motor, and the motor parameters were calculated according to the parameters and the dynamic performance of the vehicle.Aiming at steering conditions, this paper has analyzed three toque distribution methods and simulated them under the condition of straight forward, constant speed steering and shifting lane on MATLAB/Simulink.