Research On Torque Distribution Strategy Of Wheel Motor Driven Electric Vehicle Steering

Environmental pollution and the energy crisis have forced people to seek efficient,clean green cars.pure electric vehicles emerged as the times require,and the wheel motor drive electric vehicle gets a lot of attention because of its high transmission efficiency,space utilization and great potential in improving the active safety and that its four wheels can achieve independent control.However,the wheel motor drives electric vehicles have no mechanical differentials,and each wheel can drive the vehicle independently,so the need for differential control to coordinate the wheel torque,to avoid tire wear too fast.At the same time,when the vehicle turning at high speed,it will not only need to coordinate the wheel speed,to avoid excessive tire wear,but also to avoid sideslip,tail flick,spin and other horizontal instability.In order to solve the above problem,firstly,this paper summarizes the development of wheel motor drive electric vehicle,and analyzes the research status of experts and scholars at home and abroad in electronic difference control and lateral stability control.According to the theory of vehicle dynamics,the paper established dynamic model of vehicle with seven degrees of freedom and verified the dynamic response under the steering condition.Then,the paper proposed a multi mode electronic differential control strategy that is suitabled for different speed and driving conditions aiming at the shortcomings of the electronic differential control strategy that is aiming at the wheel speed.The control strategy has the advantages of simple and wide adaptability to speed.It not only realizes the adjustment of the internal and external wheel torque,but also realizes the switching of the four-wheel drive mode and the two-wheel drive mode timely,and it validates the proposed control by numerical simulation analysis.In order to solve the problem of high speed steering instability,this paper adopts the hierarchical control structure to realize lateral stability control and improve vehicle handling stability.Firstly,the paper designed a H? vehicle stability controller that based on observation to calculate the direct yaw moment of adjusting the vehicle attitude.Combined with the characteristics of distributed drive,the paper put forward a torque distribution strategy of direct yaw moment with integrated differential braking and differential drive.The proposed control strategy can ensure the vehicle handling stability at high speed steering conditions through the numerical simulation.