Concept Study of a 48V-Hybrid-Powertrain for L-Category Vehicles with Longitudinal Dynamic Simulation and Design of Experiments

The demand for high efficiency powertrains in automotive engineering is further increasing, with hybrid powertrains being a feasible option to cope with new legislations. So far hybridization has only played a minor role for L-category vehicles. Focusing on an exemplary high-power L-category on-road vehicle, this research aims to show a new development approach, which combines longitudinal dynamic simulation (LDS) with “Design of Experiments” (DoE) in course of hybrid electric powertrain development. Furthermore, addressing the technological aspect, this paper points out how such a vehicle can benefit from 48V-hybridization of its already existing internal combustion powertrain. A fully parametric LDS model is built in Matlab/Simulink, with exchangeable powertrain components and an adaptable hybrid operation strategy. Beforehand, characterizing decisions as to focus on 48V and on parallel hybrid architecture are made. Simulative investigations in this paper focus on pure electric driving. First acceleration performance in electric mode is investigated and based on these findings further decisions regarding the powertrain are taken. However, even with additional limitations the number of possible variation parameters is still very high. With the method of “Design of Experiments” the number of simulation runs is reduced significantly by finding mathematical and statistical coherences between variation parameters and simulation results. Furthermore, this method allows to find local and global minima configurations within the variation space using software integrated solver functions (e.g., combinations of 2-speed gear ratios and E-motor speed dependent shifting points). DoE analysis findings of eDrive acceleration simulations are the basis for eDrive cycle analysis. WMTC simulations focus on average cycle efficiency, showing the possible advantages of different electric powertrain configurations for the considered vehicle.