Torque Distribution Research For Multi-objective Optimization Of Distributed Drive Pure Electric Vehicles

The rapid development of the automobile industry has aggravated the consumption of non-renewable energy,while the large amount of automobile exhaust emissions aggravate atmospheric pollution,so it is necessary to transform and upgrade traditional fuel vehicles.New energy vehicles driven by electric energy have the advantages of low carbon and energy saving,so they have entered a rapid development stage and become the new direction of transformation and development for many traditional automobile enterprises.With the advantages of short drive chain,high transmission efficiency,fast response,large space inside the vehicle and independent control of four-wheel torque,four-wheel independent drive electric vehicles with hub motors have become a hot spot in the research and manufacturing industries at home and abroad.In order to make full use of the four-wheel drive performance,minimize the vehicle energy loss and improve the stability and range of the vehicle,the design of torque distribution control strategies for four-wheel independent drive electric vehicles under different operating conditions has become a hot research topic.In this paper,we focus on the composite control torque distribution strategy for four-wheel independent drive electric vehicles from the perspectives of reducing energy consumption,improving stability and increasing range.First,according to the target design value,power demand and driving range demand of the vehicle,the drive motor and power battery are selected and matched with parameters;then,a four-wheel independent drive electric vehicle simulation platform is built,which mainly contains the vehicle seven degrees of freedom model,wheel model and speed-following driver model,while the drive motor and power battery models are established according to the basic characteristics of each drive component;finally,the whole vehicle simulation platform is formed according to the logical relationship,which provides a reliable simulation platform for the subsequent design of torque optimization distribution strategy.Second,this paper takes four-wheel independent drive electric vehicle as the research object,takes reducing vehicle energy consumption,improving vehicle stability and increasing range as the research objectives,adopts a hierarchical control structure,the upper controller is the drive torque determination layer,uses fuzzy control to get the total demand torque and desired transverse swing torque of the vehicle,the lower controller is the drive torque distribution layer,on the basis of analyzing vehicle energy consumption and tire loading rate,designs a multi-objective optimal drive torque distribution strategy,uses the multi-objective weight coefficient method to solve for the torque distribution.The multi-objective optimal drive torque allocation strategy is designed based on the analysis of the vehicle energy consumption and tire load rate,and the multi-objective weight coefficient method is used to solve the torque allocation;the multi-objective optimal drive torque allocation strategy mainly focuses on the vehicle energy consumption and stability,and the strategy can realize the flexible adjustment of the torque allocation target according to the changes of the vehicle state,when the vehicle makes a sudden turn,the drive torque allocation is mainly to improve the stability,and when the vehicle keeps driving in a straight line,the driving torque allocation is mainly to reduce the operating The drive torque allocation strategy can be carried out according to the change of the vehicle state.In order to verify the effectiveness of the multi-objective optimized drive torque distribution strategy,simulation analysis was carried out under the low adhesion road conditions and high adhesion road conditions,and the simulation results showed that the multi-objective optimized torque distribution scheme has improved the energy consumption and stability of the whole vehicle.Third,in order to expand the space of energy saving of the whole vehicle,the braking torque distribution strategy of four-wheel independent drive electric vehicle is studied,and the parallel braking energy recovery structure is adopted,including the desired transverse moment decision layer,the braking force distribution layer and the condition constraint layer.In order to verify the effectiveness of the composite control torque distribution strategy in terms of energy consumption,vehicle stability and vehicle range,a torque distribution strategy control model was built in MATLAB/Simulink and combined with the vehicle simulation platform to compare the multi-objective The optimized torque distribution strategy and the composite control torque distribution strategy are simulated and compared under the cycle conditions of the new European automobile regulations,the driving conditions of Chinese light vehicles and the cycle conditions of the world light vehicle test,respectively.The simulation results show that the composite control torque distribution strategy can effectively reduce the energy consumption of the vehicle,improve the stability of the vehicle under sudden steering and increase the range of the vehicle when running the above three conditions.In summary,the composite control torque distribution strategy proposed in this paper can effectively reduce the energy consumption of the whole vehicle,improve the range and the energy-saving level of the whole vehicle,and maximize the energy-saving potential of the electric vehicle while ensuring the stable driving of the vehicle.