Flatness-based Powertrain Control for Engine Start Applications in Hybrid Dual-Clutch Transmissions

This article considers the transition between pure electrical driving and hybrid driving in a hybrid dual-clutch transmission powertrain while following a prescribed vehicle speed reference. The key aspect here is a fast and smooth engine start without interruption of the demanded driving torque and minimum jerk. A two-degree-of-freedom controller with a flatness-based feedforward control and an asymptotic tracking control is presented for solving this task. We use a scheduled control structure to cope with the switched dynamical characteristics of the internal combustion engine while being started traversing sticktion, cranking and combustion. The control scheme switches from a torque-based control for the break-free of the engine to a speed-based control for the tracking of a reference engine speed trajectory. We illustrate the performance of the control scheme by means of meaningful simulations.