The development of electric and hybrid electric vehicles is motivated by the high prices of fossil fuels, the need for better efficiency and the minimization of pollutants and greenhouse gas emissions. There are several possible technologies for these vehicles but Plug-in Hybrid Electric Vehicles (PHEV) and Fully Electric Vehicles (FEV) are becoming popular. They both require advanced energy storage and management systems. In the design of these powertrains it is of capital importance to evaluate, not only the required traction energy, but also the energy involved in braking and that has the possibility of being regenerated, in real-world routes and traffic conditions. Type-approval driving cycles are insufficient for this purpose, as they do not include parameters that substantially affect the vehicle dynamics, such as road slope and additional friction due to road winding. This work presents a methodology for the energy characterization of driving cycles, based on the numerical integration of specific power, including new parameters such as specific traction and braking energies, cumulative uphill and downhill slopes and cornering friction energy, as well as energy-power distributions. The methodology will help in the comparison of the available type-approval driving cycles and in the definition of more realistic ones that can be used for better assessment of fuel consumption and emissions of vehicles. With input data from real routes, the procedure will be useful in the design of advanced electrical or hybridized powertrain systems, both to size the components and to define appropriate energy management strategies, with the final goal of an improved efficiency. The methodology will also be valuable in the energy classification of European roads. The paper describes the mathematical model, which allows the quantification of all the important energy flows involved in the evolution of a reference vehicle, following a route. This model was developed in the MatLab/Simulink environment and was applied to the characterization of three type-approval cycles and to three real routes. The results indicate that the type-approval cycles are too soft to adequately emulate present day aggressive traffic conditions. Driving cycles simulating significant road slopes and sinuosity should be used in the future, both for consumption and emissions certification and in the development of new powertrains.
Cold Start SI Passenger Car Emissions from Real World Urban Congested Traffic
