Drive-Cycle-Based Configuration Design and Energy Efficiency Analysis of Dual-Motor 4WD System With Two-Speed Transmission for Electric Vehicles

The development of energy-saving technology is important to the promotion of electric vehicles (EVs). In the design process of EVs, the drive configuration is generally determined first, and then, the energy management strategy is studied. However, this process does not design the drive configuration with higher energy saving potential from the economic perspective of vehicle driving conditions but directly determines the drive configuration. So, in this article, the characteristics of the vehicle’s driving conditions are analyzed first, and then, based on the analysis results, a new dual-motor four-wheel-drive (4WD) EV configuration with higher energy saving potential is proposed, which only has a two-speed transmission in the rear axle. Then, the parameters of the proposed driving configuration are calculated to meet the vehicle dynamic or economic needs of various driving conditions. Then, an energy management strategy is developed for the judgment of optimal torque distribution of the front and rear axle motors and gear shifting logic. Finally, the comparison simulations are conducted, and the results show that, in worldwide light-duty test procedure (WLTC), dual-motor 4WD configuration with a two-speed transmission (DM-2ST) can reduce vehicle energy consumption by 9.13% and 4.84%, respectively, compared to DM with the fixed proportional torque distribution strategy (DM-FTD) and DM with the efficiency optimal torque distribution strategy (DM-OTD). In UDDS, DM-2ST can reduce vehicle energy consumption by 11.04% and 5.77%, respectively, compared to DM-FTD and DM-OTD.