Plug-In Hybrid Electrical Commercial Vehicle: Energy Flow Control Strategies

Abstract

Nowadays, the greatest part of the efforts to reduce pollutant emissions is directed toward the hybridization of automotive drive trains. Plug-in Hybrid Electric Vehicle (PHEV) seems to be a good short term solution for replacing the conventional combustion engine propelled vehicles, in order to improve fuel economy and reduce pollution emissions. Such topic has a particular relevance while looking at vehicles that operate in urban environment, like light commercial vehicles used for goods delivering even in limited traffic areas. In order to obtain a wide range, full performance, high efficiency vehicle and, at the same time, reduce pollutant emissions, the most feasible solution, at present, is the PHEV, which combines batteries (that can be charged during the night or enough long stops directly from the electric power grid) that feed electrical drive together with a standard Internal Combustion Engine (ICE). In fact today Full Electric Vehicles can not assure the basic requirements of driving range, performance and load capability needed for a commercial vehicle operating in urban environments, mainly because of the low energy density of actually available batteries. Considering the average daily mission of a commercial vehicle delivering goods in urban environments, PHEV can cover even long distances from the hub to the city centre, exploiting the hybrid driving mode (which can increase the efficiency with respect to standard ICEVs) and then use its pure electric driving range (30-60 km) to deliver goods inside the city centre. Since the PHEV has two on-board engines (electric and endothermic) and two energy storage systems (the electrochemical batteries and the fuel tank), energy control strategies have to be developed and introduced in order to find out the most efficient one. The full energetic model of a Plug-In Hybrid Electric Commercial Vehicle, presented in previous papers [1] and already validated exploiting experimental tests performed on a prototype developed at the Mechanical Engineering Department of Politecnico di Milano, will be used in this paper. It will be used to develop energy flows control strategies able to allow the commercial vehicle to perform its daily mission in hybrid and pure electric driving modes.