Optimierte Auslegung von ottomotorischen Hybridantriebssträngen unter realen Fahrbedingungen

The design of Hybrid Powertrains involves great complexity due to the possibility of various component combinations. In this thesis, the investigations of the FVV research program „Optimierte Auslegung von Ottomotoren für Hybridantriebsstränge“ were enlarged to a wide range of customer relevant driving conditions to investigate the influence of the powertrain layout and to carry out an optimization. The simulation approach was extended to real driving conditions with focus on the parametric description of the combustion engine. Due to the relevance of higher accelerations and higher vehicle speed in the customer relevant driving cycles, the fuel enrichment for component protection was implemented in the simulation approach. Additional the warm-up behaviour of the combustion engine and the transmission, catalyst heating and the modelling of the transmission efficiency were extended the full operation range of real world conditions.The investigations were done with the parallel hybrid powertrain, a mixed hybrid powertrain and a series hybrid powertrain. For all powertrains also plug-in variants were optimized to the combination of minimized CO2-emissions and electric power consumption.The influence of the combustion engine decreases with higher degree of electrification. The potential to reduce CO2-emissions, with downsizing and turbocharging of the combustion engine, decreases in the used driving cycles due to stronger accelerations and higher vehicle speeds. The influence of fuel enrichment in the investigated driving cycles is low.The results of the simulations shows, that hybridization of various powertrains under real driving conditions has a high potential for CO2-emission reduction. Plug-in hybrid systems have advantages mainly in urban driving situations.Under the boundary condition of the average European electric energy mix with 400 g/kWh CO2-emission per kWh, a CO2-emission reduction of up to 60% can be archived in the simulated driving cycles. In driving cycles with full electric driving of plug-in hybrid powertrains, the parallel hybrid and mixed hybrid powertrain are the best concepts.The comparison of series plug-in hybrid and mixed plug-in hybrid in long distance driving cycles (approx. 100 km), shows only 7% higher CO2-emissions of the series hybrid. In the Artemis motorway driving cycle that cannot be driven pure electric the mixed hybrid and the series hybrid has nearly the same CO2-emissions. The optimal operation of the combustion engine in the series hybrid compensates the most of the additional losses of the electric system with multiple energy conversion.The combustion engines with Atkinson concept and downsized Turbo-DI concept shows the lowest CO2-emissions in the investigated vehicles and driving cycles. The Atkinson engine has advantages in driving cycles with high power demand and the Turbo-DI engine has advantages in low load driving cycles.The presented simulation methodology shows a good possibility to optimize hybrid powertrains and components in a concept phase. For the simulation approach detailed data of the components are not necessary and the scaling approach can show influences of driving profiles, components and operation strategy in any driving situation to layout a complete powertrain