A policy-oriented vehicle simulation approach for estimating the CO2 emissions from Hybrid Light Duty Vehicles

Pollutants emissions and fuel economy tests for passenger cars differ from region to region of the world, since different driving condition and vehicle fleet characterize different geographical areas. In particular, the European type approval procedure for passenger cars uses as reference cycle the New European Driving Cycle (NEDC), which is nowadays not representative of real driving conditions. Therefore, the European Commission has planned to introduce the Worldwide Harmonized Light Duty Test Procedure (WLTP) from September 2017. As a consequence, the CO2 emissions target should be adapted, since the current 2020 goals are based on NEDC assessment. The European Commission and the Joint Research Centre (JRC) are therefore developing a simulation tool called CO2MPAS (CO2 Module for Passenger and commercial vehicles Simulation) for the correlation of CO2 emissions from WLTP to NEDC, which will be used for the type approval of European passenger cars from 2017, avoiding expensive duplicate test campaigns for car manufactures. However, the implementation of CO2MPAS has so far involved solely conventional light duty vehicles. Within this context, a research project has been carried out in closed collaboration between Politecnico di Torino and JRC for the development of CO2MPAS for Hybrid Electric Vehicles (HEVs) and Plug-In Hybrid Electric Vehicles (PHEVs). The correlation model is based on a unique simplified physical approach, which should be able to detect the powertrain behavior along the NEDC cycle from the physical measurements along the new driving cycle, estimating with a good accuracy the CO2 emissions (within ± 3 g/km).