Analyse gesamtsystemischer Zusammenhänge von hybriden Antriebsstrangkonzepten bezüglich kundenrelevanter Anforderungen

System-level design of hybrid electric vehicles focuses on the analysis and optimization of hybrid powertrains within a high-dimensional solution space with regard to the variety of variants and requirements. Existing methodical approaches are based on the identification of optimal system designs with regard to predefined powertrain requirements. In this thesis, the possibility of substituting certain engine-power classes of the product portfolio with hybrid concepts whose system performance is largely defined by the electric drive system is investigated. A significant reduction of the combustion engine power within the overall system compared to conventional drives requires a verification of the original powertrain requirements in the context of customer relevance.

In contrast to previous investigations, the method presented in this thesis identifies for the first time the demands in power and energy sizing of the electric drive system and the electric energy storage, which result from the fulfillment of original powertrain requirements. The additional influence on driving comfort spans a region of conflict between powertrain efficiency, performance and driving comfort, in which the relevant overall systemic relationships for decision-making are analysed. For this purpose, systemic influencing factors such as a reduction of the maximum velocity requirement are identified and their influence on a customer-relevant powertrain design is evaluated. In the course of this work, visualization techniques from the field of machine learning provide a comprehensible and transparent basis for substantiated decision-making. Furthermore, well-known optimization-based operating strategy approaches are extended by methods of fuzzy logic with regard to the solution of the problem. The latter is mainly enabled by considering a timeframe-based analysis for the complete characterization of the performance requirements of the electrical components.