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Simulation and Optimization of the
Longitudinal Dynamics of Parallel Hybrid
Railway Vehicles
Maik Leska, Robert Prabel, Andreas Rauh, and Harald Aschemann
Chair of Mechatronics, University of Rostock
Justus-von-Liebig-Weg 6, 18059 Rostock, Germany
{Maik.Leska, Robert.Prabel, Andreas.Rauh, Harald.Aschemann}
@uni-rostock.de
Abstract. In this paper, a basic simulation of the longitudinal dy-
namics of parallel hybrid railway vehicles is presented, which is used
for an optimization of the operating strategy. An internal combus-
tion engine, the primary power source, is supported by an electrical
energy storage system with motor and generator allowing for joint
usage of both energy sources. For the main components of the power
train, interface variables representing power flow and energy, are de-
fined. A combined quadratic performance index is introduced for a
system optimization. Here, an optimization of fuel consumption and
emissions is considered for a parallel hybrid structure to minimize the
chosen performance index.
Keywords: Hybrid Railway Vehicles, Emissions, Optimization, Fuel, Con-
sumption, longitudinal Dynamics
1
Introduction
Not only in automotive applications but also at railway vehicles, hybrid sys-
tems have a promising potential to reduce fuel consumption and exhaust
gas emissions by essentially improving the energy eciency. Railway system
suppliers worldwide invest in the research and development of such systems.
Generally, a hybrid propulsion system uses more than one power source. The
choices of energy storage devices, further system components, and the overall
system structure depend on the vehicle's duty cycle and other issues such as
cost effectiveness and serviceability. The energy savings mainly depend on the
duty cycle and on the capacity and time constants of the available energy stor-
age device. For instance, for shunting vehicles, a large peak power is required
only for a short time span that is followed by an extended period of idling.
This suggests downsizing the conventional engine by using a powerful energy
storage device. In passenger applications, the majority of energy savings does
not originate from the engine downsizing but rather from energy savings re-
sulting from recuperation of braking energy and its reuse during subsequent
