Research On Drive Control Strategy Of Four-wheel Independent Driven Electric Vehicle

Both in energy and environmental pressures, electric vehicle has become the development trend of automobile industry, Among which, the four-wheel independent driving electric vehicle becomes hot research topic in related fields, It involves many core technology, such as vehicle engineering, motor drive technology, computer control technology, battery technology, etc. The development of this technology obtained vigorously promote by large research institutions at domestic and abroad, and many achievements also have been introduced, combining the research situation at home and abroad, by analyzing the key technology of four-wheel independent driving vehicle, this paper has been doing some Related research in four-wheel independent driver electric vehicle control strategy, the torque control and antiskid vehicle control will be a starting point.By the vehicle parameters and power requirements, we first calculate the motor power, speed and other key indicators, Determined based on actual driving method, we can select motor and carry out a simple power matching, eventually build the four-wheel independent drive electric vehicle control system model. For the vehicle dynamics model, we take the vehicle longitudinal, lateral and yaw around the z-axis movement and four wheel rotation freedom, establish 7 degrees-of-freedom vehicle model. The drive motor use in the model can be simplified by dc motor model, Tires can use uniform exponent model, the half experience model can more easily get longitudinal and lateral force and slip rate, at the same time the connection between tire model, vehicle and control system can be easier.For control system, we mainly focus on electronic differential control system, which based on the torque control and antiskid control. The torque control which aim at steering stability is the key of vehicle precise control, according to the current throttle and steering wheel signal, we use torque closed-loop PID control to realize the vehicle driving torque distribution differential. Optimizing targets of antiskid control is minimizing vehicle slip rate, through dynamic compensation distribution drive torque, improve the energy distribution vehicle process, in order to achieve the purpose of energy-saving and vehicle slippery.This paper also introduces emphatically on yaw-rate control which aim at stability driving. By taking the vehicle yaw rate error as criterion, we can estimate the vehicle pose, coordinated by four-wheel torque distribution, guarantee the stability of vehicle driving.Finally we make simulation of the control system. Simulation software is a powerful Simulink software, we first establish the various subsystems in Simulink models, through connection, operation, complete vehicle dynamic simulation and debugging, it can be achieved in the model, by steering angle and accelerator pedal input, the system accurately reflect the vehicle's path and posture, and achieve coordinated control of torque, which take stability as the goal of driving.By analysis the four-wheel independent drive electric vehicle system dynamic performance, handling and stability, and differential performance. We concluded that:four-wheel independent drive is an ideal practical driving program; In this paper, the simulation model of reasonable and practical; in torque control and driving under the influence of anti-skid control system, there is better control effect, raise the car power performance and handling stability.