In the European Union trucks, busses and coaches produce around 25 % of the CO2-emissions from road transport. Because of increased road freight traffic, the CO2-emissions rose by 36 % between 1990 and 2010. Therefore, it is planned to also limit and certify the CO2-emissions of new heavy duty vehicles (HDV). One solution to reduce the CO2-emissions of a HDV is to electrify the powertrain. Depending on the driving cycle, different fuel consumption improvements can be achieved with electrification of the powertrain. For a series hybrid bus, up to 33 % of improvement has already been demonstrated. For the fleet operator the potential fuel savings that can be achieved with an alternative powertrain on a daily route is crucial for the selection of the right type of vehicle. For the vehicle manufacturer knowledge about the expected driving cycles is important to size the powertrain parameters appropriate. Hence, different aspects have to be considered when designing hybrid powertrains. To exemplify an advanced development approach, considering the requirements of, both, the operator and the OEM to find a best cost/benefit solution, this paper demonstrates the optimization of an electric powertrain for a hybrid electric distribution vehicle. All components of the electrical powertrain, like high-voltage battery and electric machine are scalable in the simulation model. By means of design of experiments, not only a best compromise between fuel consumption and cost will be determined, but also the requested vehicle performance targets like acceleration from 0 to 50 km/h and climbing capacity will be taken into account. The simulation study will compare the results of a conventional powertrain on at least two different typical routes with a series hybrid and parallel hybrid powertrain.
Autor: Johannes Maiterth
Co-Autoren:
Dipl.-Ing. Peter Methfessel, VKA, RWTH Aachen University,
Dr.-Ing. Edoardo Pietro Morra, FEV GmbH, Aachen
Electro-mobility plays an increasingly decisive role in urban public transportation. Public bus services in particular are in focus because bus fleets around the world currently consist almost exclusively of vehicles with combustion engines. Implementing alternative drive systems for buses will reduce pollution and improve the air in cities. New demands on the vehicle dynamics of buses arise due to the electric traction motors, energy converters and sys-tems for fast charging. Consider the possibility of driving torque applied in opposite directions for each rear wheel. This simple example is only possible for a configuration where an electric motor is applied to each wheel and non-exist in conventional vehicles. Due to the lack of experience in this area, extensive tests are necessary to ensure functional safety. This presentation will present the methodology as well as the results with which Bombardier ensured functional safety for an electric bus where test drives are supplemented by the use of simulation. The single components of the city bus are modelled as a complete mechatronic system. The validation of the model and model data via comparison with measured data constitutes the starting point of the investigation. Potential electrical and mechanical errors can be applied to the system at any point and their effects can be analysed. Via this approach, the test matrix can be greatly extended, e.g. by injection of incorrect error torques in the electric drive system. A systematic test procedure for different error patterns considering variation of driving situations, environmental conditions and vehicle parameters is thus possible. Through these variations and exploring critical vehicle conditions in safety (for example, driving on ice), the classic road tests at perfectly augment this stage. The overall process is supported by an automatic analysis of the results, which is imperative due to the high number of simulations, to provide a clear summary and to emphasize critical parameters for the developer. The results confirm the functional safety of the examined PRIMOVE city bus and the contribution shows how real driving tests are complemented by virtual driving tests.
Autor: Tobias Oeser
Co-Autors:
Rolf Müller (Bombardier Primove GmbH),
Christian Gnandt (TESIS DYNAware GmbH)