FEMAG-C Serial hybrid generator for electric city cars 14th Annual International Symposium Hybrid Small Fuel Cells 2012 Domenico Serpella LABOR S.r.l. (ITALY) Boston, July 18th 2012
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Finding a way or making one Company s information Laboratories recognised by the Italian Ministry of Research (2006) Quality certification ISO 9001:2008 (2008) Amongst the founders of the European Joint Technology Platform on Hydrogen and Fuel Cells (2007) More than 40 EC founded R&D projects carried out (2011) Coordinator of 13 FP6 projects, 5 FP7 projects Labor is the 3rd classified in Europe among SMEs for number of successful projects
What is FEMAG-C? FEMAG-C is the acronym for Flexible Ecological Multipurpose Advanced Generator - Car It is a technology framework enabling the use of fuel cells as an on board electric generator for electric vehicles, allowing to match improved autonomy and reduced weight with the zero emission environmental advantage. It consists in a plug-in serial hybrid electric power train, featuring scalable and redundant architecture, able to convert and control electric power, according to preset strategies, conceived to reduce control requirements of PEMFC, and to improve their efficiency and lifetime. A low pressure metal hydride system performs safely hydrogen storage, with independent hydrogen sensors wired to automatically shutdown the system upon leak detection. FEMAG-C is also a platform available for the development of Internal Combustion Engine (ICE) plug-in serial hybrid off-highway vehicle
FEMAG-C cooperation FEMAG-C is the result of a public funded project, performed as a cooperative effort between: AGT Engineering System engineering Università degli Studi di Roma Tor Vergata Energetic design and simulation Testing and validation LABOR Mechanical design of the generator (and integration with vehicle) Design of DC/DC converter and control system Prototyping and testing Algorithms for the optimization of the power distribution
FEMAG-C simplified Architecture Lithium Polymer Battery Pack #1 PEMFC #1 Intelligent DC-DC Converter Electric motor Power supply #2 PEMFC #2 Intelligent DC-DC Converter
Technical Characteristics / Hydrogen Section Hydrogen Storage 6 Ovonics@work 940sl tank Metal hydride low pressure storage Excess heat from fuel cells is used for hydrogen release Hydrogen conversion 2 Ballard MK1020ACS PEM Fuel cell stacks 46 cells per stack 1,6 kw nominal power 45-60% LHV Efficiency 50Amps @ 32V with no significant degradation
Technical Characteristics / Energy conversion DC-DC Converter 24-50V input voltage 30-60V output voltage 50A maximum current output 88-94% electrical conversion efficiency DC-DC Converter efficiency 1 0,95 0,9 0,85 0,8 0,75 0,7 0,65 0,6 0,55 0,5 5 10 15 20 25 30 35 40 45 50 Fuel cell input current (A) 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 DC-DC Converter efficiency 0 5 10 15 20 25 30 35 40 45 50 Fuel cell Input current (A)
Technical Characteristics / Control system 60 Smart controller 50 Intelligent loading of fuel cells with preset ramps for longer lifecycle Independent control of fuel cells Current (A) 40 30 20 10 Battery charge and discharge management 0 13:40:53 13:40:54 13:40:56 13:40:57 13:40:59 13:41:1 13:41:3 13:41:4 13:41:6 13:41:7 13:41:9 13:41:11 13:41:13 Scalable architecture System evolution DC1 Output DC2 Output Load
Technical Characteristics / Energy storage Battery Pack 3 EIG M4820 Lithium Polymer batteries 48V 60Ah Total nominal capacity 3C recommended discharge rate 10C maximum discharge rate Recommended charge 2h Maximum charge 1h
Overall System Performance / Prototype 10 12 kwh capacity (depending on fuel cell load strategy) 85 kg weight 40-55% LHV efficiency to electric motor 3 kw nominal power 10 kw peak power Instantaneous start-up Improved fuel cell lifetime
Power train performance comparison Features FEMAG-C Lythium- Ion Battery Pb-Gel Battery Volume (l) 140 140 140 Weight (kg) 85 140 175 Usable energy (kwh) 12 14 5 Volumetric energy density (Wh/l) Gravimetric energy density (Wh/kg) 86 100 36 141 100 29
Hydrogen storage performance comparison Storage Section Usable energy (assuming 50% cell efficiency) Gravimetric energy density (Wh/kg) FEMAG-C System Metal Hydrides 350bar H2 tanks Chemical Hydrides 8400 8400 8400 Weight (kg) 39 17,1 8,4 215 490 1000 Total usable energy (Wh) 11400 11400 11400 Gravimetric energy density (Wh/kg) Total weight 85 63,1 54,4 135 180 210
FEMAG-C conventional control strategy According to a conventional and non adaptive control strategy, fuel cells are protected against load fluctuations by preset ramps implemented by the DC/DC converters and the target of the ramp is set according to the load demand Fuel cells are protected by overloading with two settings: maximum current and minimum voltage Battery pack provides load current exceeding the maximum rated current of fuel cells, and the temporary load peaks while fuel cells are adjusting This strategy is not optimizing the contributions from fuel cells and battery. Since the efficiency of the fuel cells is lower at higher current an improved algorithm has been developed to distribute load current demand and implement an overall control strategy aimed at efficiency maximisation
FEMAG-C optimization / assumptions Efficiency of the FC and DC-DC converter aggregate Efficiency of battery charge /discharge
FEMAG-C optimization / how to balance? A greedy optimization algorithm without any correction would simply discharge batteries, since they are the most efficient source To balance the contribution between fuel cells and batteries a further function has been introduced This function awards FC current when batteries are at a lower voltage, and on the contrary, batteries current at higher voltage
Battery power FEMAG-C optimization / battery map
Fuel cell power FEMAG-C optimization / fuel cell map
FEMAG-C optimization / conclusions The algorithm results still need to be validated on the vehicle. Preliminary simulation with available data and extrapolation of controller behaviour shows a considerable efficiency increase (5-8%) Control route simulation has to be implemented and tested to calculate differences over ECE cycles
FEMAG-C open issues Hydrogen storage is still a critical point for automotive acceptability 350/700 bar compressed storage offer higher energy density and will be considered for future projects. Fuel cells are still undergoing heavy technological development and their mass market will not start soon FEMAG-C Electronics is currently being upgraded to a more powerful and expandable platform Labor is opened to partner with industrial players interested to the exploitation of FEMAG-C concepts, and actively looking for new applications and early markets for hydrogen technology Results of the FEMAG-C project are currently being used to develop a plug-in serial hybrid off-highway vehicle based on an LPG powered Internal Combustion Engine (ICE)
Thank you! Contacts: Domenico Serpella: d.serpella@labor-roma.it Alfredo Picano: a.picano@labor-roma.it Labor s.r.l., Via Giacomo Peroni 386, 00131 Roma, Italy - www.labor-eu.net