Conceptual Design and Analytic Assessment of 48V Electric Hybrid Powertrain Architectures for Passenger Cars

To meet the requirements in relation to pollutants, CO2-emissions, performances, comfort and costs for 2025 timeframe, many technology options for the powertrain, that plays a key role in the vehicle, are possible. Beside the central aspect of reducing standard cycle consumption levels and emissions, consumer demands are also growing with respect to comfort and functionality. In addition, there is also the challenge of finding cost efficient ways of integrating technologies into a broad range of vehicles with different levels of hybridization. High degrees of electrification simultaneously provide opportunities to reduce the technology content of the internal combustion engines (ICE), resulting in a cost balancing compromise between combustion engine and hybrid technology. The design and optimization of powertrain topologies, functionalities, and components require a complex development process. To face the complexity of goal, in this work a methodology of powertrain conceptual definition has been proposed with the aim of the design, objective assessment and optimization of the key parameters of an hybridized powertrains. A methodology able to define ICE, Transmission and Electric Traction Drive specifications has been developed and used in this study. The focus is on Low Voltage 48V electric hybrid architectures, that represent attractive alternatives to High Voltage hybrid systems. The 48V systems offer on the one hand already attractive performance potential for different levels of hybridization, on the other hand, opportunities open up for the electrification of the internal combustion engine and its auxiliaries. The design methodology has been applied to two vehicles of different classes, C-Segment and SUV, with the aim to assess the capability of 48V hybridization to meet the new challenging requirements. The results confirm the potential of Low Voltage systems to implement cost effective full hybrid architectures