An Optimal Torque Distribution Strategy For Distributed Drive Electric Vehicles Based On Energy Efficiency

Compared with centralized drive electric vehicles,distributed drive electric vehicles have attracted more and more attention because of their flexible structure layout,larger passenger compartment space,high transmission efficiency,and flexible control.The short cruising range on a single charge is a limiting factor in the development of various electric vehicles today.Optimizing the energy utilization efficiency(energy efficiency)of the electric vehicle drive system is one of the effective ways to solve this problem.In order to optimize the energy efficiency of the entire vehicle when electric vehicles are running,and to extend the range of a single charge,the distributed drive electric vehicle was taken as the research object,and an optimal torque distribution strategy based on energy efficiency was designed.In view of the different driving conditions of the vehicle,the distribution of the driving torque of the distributed drive electric vehicle under the straight driving condition and the steering condition was analyzed,and the optimal torque distribution strategy for the purpose of improving energy efficiency under different working conditions was proposed.Aiming at the problem of torque distribution under straight driving conditions,it was transformed into a constrained target optimization problem,and the torque distribution coefficient matrix under straight driving conditions was solved by genetic algorithm optimization method,which can distribute the torque to each driving wheel according to the different driving conditions of the vehicle,and improve the energy efficiency of the whole vehicle.Aiming at the problem of torque distribution under steering driving conditions,a layered control method was adopted.The upper layer is yaw stability control,and the lower layer is torque distribution control based on energy efficiency,which improves the energy efficiency of the vehicle when the vehicle is steering while ensuring the stability of the vehicle.Based on Carsim and MATLAB/Simulink co-simulation platform,a complete vehicle model of a distributed drive electric vehicle was built,and the effect of the proposed optimal torque distribution strategy was verified: Comparison between the average torque distribution strategy and the optimal torque distribution strategy based on energy efficiency under straight driving conditions shows that,under the NEDC test cycle,the vehicle energy consumption is reduced by 6.9%;under the CLTC-P test cycle,the vehicle energy consumption is reduced by6.0%;under the WLTC test cycle,the vehicle energy consumption is reduced by 5.9%;under the HWFET test cycle,the vehicle energy consumption is reduced by 7.6%;under the US06 test cycle,the vehicle energy consumption is reduced by 4.5%.Comparison between the Torque distribution strategy based on axle load ratio and the optimal torque distribution strategy based on energy efficiency under steering conditions shows that,under the set step steering condition,the vehicle energy consumption is reduced by 5.2%;under the set single lane change condition,the vehicle energy consumption is reduced by 3.9%;under the set double lane change condition,the vehicle energy consumption is reduced by 4.4%;and the vehicle can maintain driving stability under the three steering conditions.The above simulation results show that the proposed optimal torque distribution strategy can effectively improve the energy efficiency of the vehicle during driving.