A Four-Wheel-Drive Fully Electric Vehicle Layout with Two-Speed Transmissions

This paper presents a novel fully electric vehicle layout, consisting of two drivetrains, each of them including a two-speed transmission, for improving vehicle acceleration and gradeability performance. The adoption of two-speed transmissions allows eight different gear state combinations, increasing the possibility of selecting a high-efficiency state for each operating condition. A torque-fill controller is developed for the compensation of the torque gap during gearshift through the variation of the torque on the other axle. Finally, a simulation-based analysis of the acceleration, gradeability and gearshift performance of this vehicle layout is discussed, in comparison with alternative fully electric vehicle configurations.