Optimal Design of an Electrified Rigid Truck based on Pollutant Emissions and Total Cost of Ownership

The recent updates of the European Union regulations concerning emissions from heavy-duty vehicles greatly tightened CO2 emission limits and widened the groups of vehicles that must withstand these thresholds to most of the subgroups defined within the VECTO methodology. To meet these regulations, manufacturers are introducing fully electrified powertrains for trucks or alternative-fueled internal combustion engines, while heavy-duty hybrid systems are not common in constructors’ catalogs. The aim of this analysis is to investigate and assess the effectiveness of a diesel-electric P2P4 series architecture for emission reduction purposes, in both full and plug-in hybrid configuration, while also considering techno-economic aspects. The first step of this work was to select a suitable test case; a rigid truck belonging to VECTO group 3 was identified and the design space for the most relevant hybrid powertrain components was defined. All of the resulting configurations were tested on the VECTO Regional mission using a dedicated simulation tool. The tool was also used to develop a suitable optimization-based energy management strategy for the hybrid powertrain. A first optimization based on CO2 emissions only resulted in a very large reduction in CO2 for both FHEV and PHEV configurations (up to 75% for the PHEV). However, this also resulted in an ineffective thermal management of the SCR catalyst which subsequently operated at low efficiency, thus resulting in an increase of NOx emissions. Therefore, a second optimization was set up to target both CO2 and NOx emissions, and several trade-offs were investigated for each architecture in order to minimize CO2 emissions while meeting EU type-approval emission limits for NOx emissions. In the second step, the architectures were analyzed from a total cost of ownership and social impact approach over a 10-year period. The result of this analysis enabled the evaluation of the optimized powertrains’ sustainability and advantages of optimized powertrains from both a customer-oriented and a societal perspective.