Electric machine and battery sizing for hybrid electric heavy-duty vehicles

Medium- to heavy duty vehicles make a major contribution to freight transportation and are expected to keep growing continuously. In order to reduce the CO2 emissions and avoid climate change, ambitious regulations have been introduced. To fulfill these requirements, aerodynamic drag and vehicle mass reduction, more efficient conventional internal combustion engines (ICE) and alternative powertrain architectures are being developed. Hybrid electric vehicles (HEVs) are one of the solutions with the highest potential for fuel economy improvement, provided that all the subsystems at play are correctly sized. In this work, a power based approach is used to define the electric machine (EM) and battery size by considering the power request in braking and technology constraints in the battery and power electronics. The hybrid layouts under study are P0, P1, and P2 parallel applied to a 35 Ton vehicle whose model is developed in a Matlab/Simulink environment using the velocity profile from the European Union Commission simulation tool (VECTO). The Equivalent Consumption Minimization Strategy is used as an energy management system to provide optimal torque references to ICE and EM. The regional delivery and long haul driving cycles, which are the official driving cycles for the certification of heavy duty vehicles in the EU, were used to evaluate the performance of hybrid solutions with respect to conventional pure ICE.