• hybrid vehicle
• railway vehicle
• dual-mode
• battery

Hybrid propulsion systems for land vehicles have been widely studied for
decades, as systems that combine conventional and electric propulsion
architectures, with the main aim of fuel consumption and pollution
emissions reduction.
As far as road vehicles are concerned, both four-wheel vehicles, such as
buses or cars, and two wheelers, such as scooters or motorcycles, have
been studied, prototyped, and, in some cases, made commercially
available.
In particular the use of hybrid vehicle for the local transport of
passengers or goods is very interesting, due to the growing necessity to
have cleaner and more economic transportation systems.
In the railways sector the introduction of hybrid propulsion is also
possible, in case of small trains with a behaviour similar to urban road
vehicles, with mission profiles consisting of frequent acceleration /
brakings and stops, for example regional trains used for passengers
transport and switching locomotives.
In this thesis the studies carried out on the hybrid propulsion system for
land vehicles are reported in a systematic way, and the main related
issues are discussed.
More in detail, in chapter 1 the concept of hybrid propulsion is
introduced, definitions and classifications are provided and there are
also some examples of their realization listed.
Chapter 2 approaches the problem of optimising energy consumption
onboard hybrid vehicles in a general way, considering the main issues to
be solved in their conceptuality, and therefore often abstracted from the
actual structure of the particular drive-train considered.
Chapter 3 shows the results of experimental tests carried out on
samples of batteries for hybrid-electric vehicles of different technologies
(Lead-acid, Nickel Metal Hydride, and Lithium ion) to evaluate their
energy efficiencies, when subjected to small cycles like a real operating
condition on hybrid vehicles.
Chapter 4 describes a hybrid drive train simulation program with a userfriendly
man machine interface, developed in Matlab-Simulink™
environment. The program is able to simulate series-hybrid drive trains of either road vehicles or trains. The simulator is certainly a necessary
tool in the design phase for the choice of architecture and dimensioning
of the various subsystems which to test the energy behaviour of vehicles
as a result of different control strategies implemented.
Chapter 5 shows the possibility of using hybrid drive-trains for propulsion
of small electric trains. The study is based on a project commissioned by
Trenitalia (the main Italian rail transport company), regarding regional
trains (ALn668) operating in non-electrified lines, and shunter
locomotives (D141) operating in the main rail stations.
Finally, in chapter 6 the study of a dual-mode propulsion system for
railway vehicles is showed; technical and economical analyses of
regional passenger dual-mode trains in the Italian railway network are
also expounded.