Torque coordinated control of no-power interruption gear shifting for multimode hybrid electric vehicles equipped with a two-speed dedicated hybrid transmission

This paper investigates the power interruption and torque impact issues of a multimode hybrid electric vehicle (HEV) equipped with a dedicated hybrid transmission (DHT) during gear shifting. Such interruption and impact can significantly result in a deterioration in power performance and comfort of the vehicle. First, the main challenges in the uninterrupted power shifting process are analyzed, and a multi-phase dynamic model of the shifting process is established. Then, drawing on the configuration characteristics of the DHT-HEV power system, a shifting control architecture that maintains power continuity is proposed. Based on this control architecture, a finite time disturbance observer (FTDO) is designed to estimate the random torque disturbances of the engine during the torque phase of shifting process, and a nonsingular fast terminal sliding mode controller (NFT-SMC) is developed to dynamically coordinate the output torque of engine and traction motor (TM). The simulation and bench test results show that this method not only achieves non-power interruption shifting, but also effectively suppresses torque impact during shifting and improves driving comfort.