Modeling and Simulation of a Hybrid Dual-Clutch Transmission Powertrain

Abstract

More and more modern passenger cars use hybrid electric propulsion sources that combine the advantages of internal combustion engines (ICE) and electric machines (EM). There exists a wide variety of different hybrid electric vehicle topologies and realizations. To compete in this market, Magna Transmission Systems (2015) has presented the 7HDT300, a hybridized dual-clutch transmission (DCT). In this transmission, an EM is connected side-by-side to one of the two sub-transmissions via a gear reduction set. This allows a considerably smaller highspeed EM, which is lighter and more cost-effective, without affecting the powertrain length. Furthermore, the EM and the ICE can use different gears, so that both can work within their optimal efficiency range.This contribution introduces a complete model of a hybrid DCT using a flexible multibody approach for the drivetrain, including the clutch actuation and all torques occurring in the powertrain, based on physical models. With this, the most common driving use cases can be simulated, e.g. acceleration from stillstand, driving with either the ICE or the EM, shifting gears, and starting the ICE with the EM using the clutch. Especially the latter scenario obliges an accurate model of the ICE, including the starting behavior and extending beyond the often used engine maps, which are only valid for a running engine. With a suitable set of parameters, the proposed model shows a physically reasonable behavior, making it possible to perform simulations of real vehicles. Moreover, the model is the basis for simplifications towards a model-based control design.