Analysis Of Tire Energy Consumption And Vehicle Energy-Saving Control Of Distributed Drive Electric Vehicles

In recent years,the problems of environmental pollution and energy shortage caused by the large-scale use of fossil energy have become increasingly serious,and the widespread use of traditional fuel vehicles has exacerbated this phenomenon.Therefore,more and more researchers and enterprises engaged in automobile related work have focused on electric vehicles,among which the research on distributed drive electric vehicles has become a research hotspot at home and abroad.Compared with traditional fuel vehicles,distributeddrive electric vehicles do not require a transmission system for power transmission,but four independent motors directly provide torque to the wheels,which not only makes the vehicle have more controllable degrees of freedom,but also greatly improves its efficiency and response speed,so it can better realize the four-wheel torque distribution and achieve the purpose of improving the energy-saving effect of the vehicle.Therefore,this paper has done the following work for distributed drive electric vehicles:Firstly,analyzing the mechanism of tire slip energy consumption.Considering that reducing tire slip energy consumption is also a way to achieve energy saving of the vehicle,the tire discrete simulation model is established to analyze the mechanical properties of the tire under different working conditions,and the mechanism of tire slip energy consumption is analyzed by using the characteristic distribution of tread elements in the tire contact patch.On this basis,the Uni Tire semi-empirical slip energy model was established.The simulation results verified the accuracy of the model,which was used as the basis for subsequent work.Secondly,taking the distributed drive electric vehicle based on in-wheel motor as the research object and establishing the vehicle dynamics model of the controlled vehicle.The car body model is established by Car Sim,and the models of wheel,motor,battery,driving resistance and tire are established by Matlab / Simulink.The results obtained from the cosimulation under the China Light-duty vehicle Test Cycle-Passenger（CLTC-P）condition are compared with the vehicle test data to verify the accuracy of the built model and use it as a follow-up Simulation and verification platform for control strategies.Then,in order to improve the energy-saving level of electric vehicles under longitudinal working conditions,an energy-saving control strategy based on Model Predictive Control（MPC）algorithm is proposed.The wheel dynamics model is selected as the prediction model.On this basis,the model prediction controller is designed,which can centrally optimize the motor energy saving control,tire slip energy consumption control and vehicle handling control.Among them,reducing the driving power of the motor and increasing the regenerative braking energy are the main ways to improve the energy-saving level of the motor.According to this,two energy-saving control strategies,offline optimization and online optimization,are proposed.The simulation results show that the proposed strategy can effectively reduce the motor energy consumption and tire slip energy consumption,and improve the energy saving level of the whole vehicle.Finally,an integrated control strategy that combines vehicle stability and energy saving is proposed.Under lateral conditions,if energy saving is the only control objective,the vehicle may become unstable.Therefore,the dual-track model is selected as the prediction model to improve the prediction accuracy of the vehicle state.Combined with the energy-saving control strategy,the stability control objective is incorporated into the cost function for multi-objective centralized optimization,so as to ensure the stability of the vehicle and improve the energy efficiency of the entire vehicle.level.The simulation results of the double lane-shifting condition show that the proposed control strategy can achieve the purpose of improving the energy-saving performance and stability of the vehicle.To sum up,this paper establishes the Uni Tire semi-empirical slip energy model through the analysis of the tire slip energy consumption mechanism,and takes the distributed drive electric vehicle based on the in-wheel motor as the research object,using its rich controllable degrees of freedom,successively.The vehicle energy-saving control strategy and the vehicle stability and energy-saving integrated control strategy are designed.The final simulation results show that the proposed control strategy can effectively achieve the goals of motor energy saving,reducing tire slip energy consumption and ensuring vehicle stability.