Benchmarking of the blended control strategy in Plug-in Hybrid Electric Vehicles and energy efficiency analysis in real-world conditions

Nowadays the reduction of greenhouse gases (GHG) in the transport sector plays a crucial role in the European Union regulations. Plug-in Hybrid Electric Vehicles (PHEVs) represent a valid solution to immediately decrease vehicle tailpipe CO2 emissions combining the advantages of conventional vehicles and battery electric ones. However the complexity of PHEVs is higher because of the presence of more on-board sources of power, so an appropriate Energy Management System (EMS) is needed. The standard control consists in implementing first the charge depleting (CD) strategy which uses electric energy from the battery to achieve pure electric driving and later the charge sustaining (CS) strategy which is mainly internal combustion engine (ICE) assisted. The aim of this thesis is to analyse the experimental data acquired from real-world trips of a C-segment PHEV in order to assess the operation and the possible advantages of a specific EMS control strategy: the blended mode. In this mode the electric motor (EM) and the ICE are used together along the trip with the aim of improving the overall fuel economy of the trip. The real-world approach is important because this strategy cannot be efficiently evaluated only within type approval scenarios. This work has been conducted in cooperation with the Sustainable Transport Unit of the European Commission’s Joint Research Centre (JRC) in Ispra (Italy). Different users have used the PHEV under consideration for a period of time carrying out several real-world trips according to their private schedule. The real-time data about the vehicle operation were registered during the trips using the On-board Diagnostics (OBD) and the Unified Diagnostic Services (UDS). This thesis firstly proposes a literature review to examine fuel consumption (FC) in type approval tests and real-world trips, to figure out some examples about the operation of the blended control strategies and to assess the real-world CO2 emissions in PHEVs. In the following parts, the real-world trips were categorised, the blended trips were compared with similar ones where the more classic charge depleting and charge sustaining (CD-CS) strategy was used and the two control strategies were analysed.