Torque Distribution And Control Of Distributed Driving Electric Vehicles Under Different Operating Conditions

Distributed drive vehicles usually use in-wheel-hub motors to drive directly.Compared with the complex power systems of traditional cars,using in-wheel motors can not only simplify the mechanical structure of the vehicle,reduce the weight of the vehicle,improve the driving experience,but also facilitate the implementation of intelligent and active control of electric vehicles due to the advantages of rapid torque response of in-wheelhub motors and independent control of motor torque.Aiming at the problem of torque distribution and control of distributed driving vehicles,a torque optimal distribution and control strategy is designed to realize differential control of steering and anti-slip control of straight driving.Firstly,a simple model of EV driven by four-in-wheel hub motors is established,and the seven-degree-of-freedom model is used to analyze the dynamics of the body,steering system and drive wheel modules.Secondly,according to the idea of modular design and control,the problem of torque distribution under different conditions such as steering and straight driving is studied because the vehicle needs to adapt to different driving requirements.In order to meet the requirements of steering maneuverability and steering stability under steering driving conditions,wheel drive torque control strategies are developed according to different vehicle speeds.Reference to ideal steering relationship at low speed,wheel drive torque is controlled to achieve electronic differential;at high speed,vehicle drive torque is optimized to achieve lateral stability.The control strategy coordinates the torque control from two aspects to adapt to different vehicle speed conditions.When the vehicle is traveling in a straight line,considering wheel slip condition and the coordination between the wheels,a driving anti-slip control strategy is developed.Based on sliding mode control,by monitoring the relationship between wheel longitudinal force and speed,the timing of wheel slip out of control is obtained,and wheel drive anti-slip control is started timely,so as to achieve the purpose of driving anti-slip by reducing the longitudinal force.Joint simulation models of Car Sim and MATLAB/Simulink are built to meet the research requirements,offline simulation is carried out,and experimental platform of double-in-wheel-hub motor is built to verify the control strategy of torque optimal distribution by hardware-in-loop simulation.The simulation results show that the realtime torque optimization strategy can guarantee the real-time requirements of motor torque control and vehicle steering stability when the vehicle is traveling at high speed.A distributed electric vehicle test vehicle driven by four-wheel hub motors was built,and the vehicle test was carried out to verify the control effect of torque distribution strategy under steering conditions.The results show that the control strategy based on electronic differential torque control designed in this paper can achieve better differential effect through torque coordination control.