Torque Lever-Based Gear-Shifting Strategy of a Novel Three-Speed Transmission for Electric Vehicles

Although multispeed transmissions (MSTs) in electric vehicles (EVs) offer advantages over the single-speed ones, they can also introduce shifting problems. To achieve higher shifting quality and streamline the development, this study investigates the torque lever-based gear-shifting strategy of a novel three-speed transmission for EVs. Initially, a novel powertrain based on a three-speed Ravigneaux transmission is proposed as the foundation for the transient analysis of gear shifting. Meanwhile, the equivalence of the idealized gear arrangements in Ravigneaux gearsets is demonstrated. Based on the analysis, we employ the torque lever approach (TLA) to design three power-on shift control strategies according to different torque controls. This approach features less theory computation than algebra. Subsequently, the hardware-in-the-loop (HiL) validates all the strategies for upshift and downshift between adjacent and nonadjacent gears. The results show the effectiveness of the strategies designed by TLA, and their features are discussed in these shifting conditions.