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AHEAD

This project aimed at optimizing the powertrain of a serial hybrid electric bus for public transportation. First the optimal sizing of the powertrain components (sizes of combustion engine, supercapcitor, traction motor, etc) were found using optimal control theory. Then an optimal energy management was implemented on the vehicle. Using the standardized on-road test procedure it was shown that the serial hybrid electric bus consumes up to 27.5% less fuel than a comparable diesel bus. Running on a real busline for 3 weeks, the serial hybrid bus consumed 20-25% less than a comparable diesel bus.

The main final results of this project have been published in the external pageMTZ - Motorentechnische Zeitschrift Deutschland in external pageGerman as well as in external pageEnglish language.

This project was awarded the external pageWatt'dOr-Prize in the category "energy efficient mobility" in 2015.

The AHEAD project was a cooperation of external pageHESS AG (Bellach, Solothurn) and ETH Zürich, sponsored by external pageKTI and external pageBFE.

Currently, HESS AG and IDSC are collaborating with external pageVBZ in the field of Trolley-Bus-Systems in the SwissTrolley+ Project.

Hardware of a serial hybrid powertrain
The bus is propelled by an electric traction motor (see figure below). Electric energy is delivered by an engine-generator set in the back of the vehicle. During downhill driving and braking maneuvers, the traction motors regenerate kinetic and potential energy, which is then stored in the electric double-layer capacitors (EDLCs) on the roof of the bus. This "recuperated" energy can be used for propulsion later on.

Hardware of a serial hybrid powertrain

Components have to fit vehicle and mission
The components of the powertrain have to be adjusted to the primary use of the bus. If for example the route is a flat and straight road without many stops the components will be very different from the case where the bus is driven in a hilly city. This project develops methods and tools to find the optimal design for a vehicle's primary use.

Optimal energy management needed
During operation, the vehicle requires an energy management controller that decides upon the power split, i.e., how the traction power to be delivered is split up between the diesel generator set and the superacapacitors. A good energy management controller is crucial for good fuel economy. In this project, a fuel-optimal energy management controller was developed and implemented on the vehicle. Using the standardized on-road test procedure, it was shown that the serial hybrid electric bus together with the fuel-optimal energy management reduces consumption by 17.5-27.5% compared to a conventional diesel bus.

Ahead Consumption

Information about future elevation profile allows saving energy
Nowadays, almost every city bus is equipped with a GPS receiver that allows to detect the position of the bus on the busline. Together with a map of the busline stored on-board, the system can provide specific data to the energy management system. This way, the supercaps can be discharged prior to long descend and recuperation energy that otherwise would have been lost can be used to recharge the supercapacitors. This way, the system is more robust to altitude variations on buslines.

HeightProfilePred

Project goals
In public transportation, where buses run only on very few routes, the design of the vehicle can be specialized and optimized. This project seeks

  • to find the fuel-optimal component sizes for a given vehicle on a given route;

to implement a fuel-optimal, predictive energy management strategy that takes into account the future elevation profile.

Practical outcomes
HESS benefits from

  • reduced time and cost for development and design;
  • the possibility to demonstrate and compare the performance of powertrain designs.

The costumer of a HESS bus benefits from

  • 20-25% reduced CO2 emissions;
  • 20-25% reduced fuel cost.

Scientific research topics
Hybrid electric vehicle design and optimization and predictive control of hybrid electric vehicles.

 

Final Results

Elbert P., Widmer M., Gisler H.-J., Onder C., "Systematic Optimization of a Serial Hybrid Electric Bus", 2016, MTZ - Motorentechnische Zeitschrift Deutschland, Vol. 77, No. 5, pp. 62-67, Read Article in external pageEnglish or external pageGerman.

Peer Reviewed Journals

Elbert P., Widmer M., Gisler H.-J., Onder C., "Stochastic dynamic programming for the energy management of a serial hybrid electric bus," 2015, International Journal of Vehicle Design, Vol. 69 No. 1/2/3/4 pp. 88-112. external pageRead Article

Elbert P., Nüesch T., Ritter A., Murgovski N., Guzzella L., "Engine On/Off Control for the Energy Management of a Hybrid Electric Bus via Convex Optimization," 2013 IEEE Transactions on Vehicular Technology, Vol 63, No. 8, pp. 3549-3559. external pageRead Article

Elbert P., Ebbesen S., Guzzella L., "Implementation of Dynamic Programming for n-Dimensional Optimal Control Problems with Final State Constraints," 2012, IEEE Transactions on Control Systems Technology, Vol 21, No. 3, pp. 924-931. external pageRead Article

Ebbesen S., Elbert P., Guzzella L., "Battery State-of-Health Perceptive Energy Management for Hybrid Electric Vehicles," 2012, IEEE Transactions on Vehicular Technology, Vol. 61, No. 7, pp. 2893-2900. external pageRead Article

Ebbesen S., Elbert P., Guzzella L., "Engine Downsizing and Electric Hybridization Under Consideration of Cost and Drivability," 2012, Oil & Gas Science and Technology – Rev. IFP Energies nouvelles, Vol. 68, No. 1, pp. 109-116. external pageRead Article

Nüesch T., Flankl M., Elbert P., Onder, C., Guzzella L., "Convex Optimization for the Energy Management of HEVs Considering Engine Start and Gearshift Costs," 2013, Energies, Vol. 7, No. 2, pp. 834-856. external pageRead Article

Peer Reviewed Conferences

Elbert P., Onder C., Gisler H.-J., "Capacitors vs. Batteries in a Serial Hybrid Electric Bus," 2010, IFAC Symposium Advances in Automotive Control, AAC 2010, Munich, Germany.

Elbert P., Ebbesen S., Guzzella L., "Economic Viability of Battery Load-Leveling in Hybrid Electric Vehicles using Supercapacitors," 2011, Int. Scientific Conference on Hybrid Electric Vehicles, RHEVE 2011, Rueil-Malmaison, France

Ebbesen S., Elbert P., Guzzella L., "Engine Downsizing and Electric Hybridization Under Consideration of Cost and Drivability," 2011, Int. Scientific Conference on Hybrid Electric Vehicles, RHEVE 2011, Rueil-Malmaison, France

Gisler H.-J., Elbert P., "Capacitors vs. Batteries in a Serial Hybrid Electric Bus," 2012, 9th Symposium on Hybrid- and Electric Vehicles, IAV 2012, Braunschweig, Germany

09.01.2015
external pageEnergeia plus blog summarizes the Watt d'Or award ceremony.

08.01.2015
ETH Life, external pageSolothurner Zeitung and external pageSoaktuell report about HESS and IDSC winning the Watt d'Or award.

08.01.2015
external pageEnergeia explain in their special issue for external pageWatt d'Or how IDSC helps HESS to save energy. DownloadRead article. (PDF, 827 KB)

01.03.2014
external pageEnergeia explain in their external pagelatest issue how IDSC helps HESS to save energy. DownloadRead article. (PDF, 644 KB)

01.01.2014
The external pageOmnibusspiegel explains the concept of the HESS-Voith Hybrid bus. DownloadRead article. (PDF, 1.6 MB)

27.11.2013
The external pageHeidenheimer Zeitung explain the concept of the HESS-Voith Hybrid bus. DownloadRead article. (PDF, 453 KB)

21.10.2011
Congratulations! AHEAD was awarded the Downloadsecond prize (PDF, 417 KB) and external pageRegional Winner of Switzerland in the European Satellite Navigation Competition external pageESNC.

21.06.2011
ETH GLOBE explain in their Downloadlatest issue (PDF, 8 MB) how IDSC helps HESS to save energy. DownloadRead article. (PDF, 483 KB)

21.01.2011
ETH Life reports on Philipp Elbert winning the Hans-Eggenberger Prize for his Masterthesis.

01.01.2011
Congratulations! Philipp Elbert's Masterthesis "Optimal Component Design for Serial Hybrid Electric Buses" was awarded the external pageHans Eggenberger Prize.

01.10.2007
external pageStadtbus.de Onlinemagazin

This project is a cooperation with external pageHESS AG.
It is sponsored by external pageKTI.

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