fuel cell and super capacitors

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20 ECTI TRANSACTIONS ON ELECTRICAL ENG., ELECTRONICS, AND COMMUNICATIONS VOL.3, NO.1 FEBRUARY 2005

Fuel Cell and Supercapacitors for AutomotiveHybrid Electrical System

Phatiphat Thounthong 1 , S tphane Rael 2, and Bernard Davat 2, Non-members

ABSTRACT

The design and testing of a purely supercapaci-tor energy storage system for the power condition-ing of automotive system having a PEM fuel cellas main source is presented. The innovative controlstrategy is that fuel cell is simply operating in al-most steady state conditions in order to lessen themechanical stresses of fuel cell and to insure a goodsynchronization between fuel ow and fuel cell cur-rent. Supercapacitors are functioning during absenceof energy from fuel cell, transient energy delivery ortransient energy recovery. The system utilizes a su-percapacitive storage device, composed of six compo-nents (3,500 F) associated in series. This device isconnected to a 42 V dc bus by a 2-quadrant dc/dcconverter, and fuel cell is connected to the dc busby a boost converter. The system structure is re-alized by analogical current loops and digital con-trol (dSPACE) for voltage loops and estimation al-gorithms. Experimental results with a 500 W PEMfuel cell point out the slow dynamics of fuel cell be-

cause of thermodynamic and mechanical operation,and also substantiate that the supercapacitors canimprove dynamics and power conditioning for auto-motive electrical system.

Keywords : Automotive, Hybrid Electrical System,Polymer Electrolyte Membrane Fuel Cell, Superca-pacitor

1. INTRODUCTION

At this time, the energy and pollution crisis be-comes the great problem around the world, and as a

consequence novel renewable and clean energy powersources must be considered. One of the prevalent al-ternative sources of electric power is fuel cell (FC)[1].

Scientists are developing many different types of fuel cell employing different fuels and electrolytes.

05PSJ05: Manuscript received on January 22, 2005 ; revisedon April 5, 2005.

1 The author is with Department of Teacher Training in Elec-trical Engineering, King Mongkut’s Institute of TechnologyNorth Bangkok, E-mail: [email protected].

2 The authors are with Ecole NationaleSuperieure d’ Electricite et de Mecanique, Insti-tut National Polytechnique de Lorraine, Nancy,France, E-mail: [email protected],[email protected].

One of the most promising is the lightweight, rela-tively easy to build and small Polymer ElectrolyteMembrane Fuel Cell (PEMFC), rst used by NASAin the 1960’s as part of the Gemini space program[2,3].

Fuel cell power generation systems are expected toincrease in utilization in different applications suchas stationary loads, automotive applications, and in-terfaces with electric utilities due to the numerous

advantages over conventional generation systems.Hybrid electrical cars, such as the Honda Insightand Toyota Prius, were especially tested by U.S. De-partment of Energy (DOE) and showed their abilityfor fuel saving [4]. Furthermore, the fuel cell TransitBus, which has been designed and developed by DOE,has been acknowledged as a zero emission vehicle. Itsonly emission is, in fact, water vapor [5].

Different previous works have already pointed outthe possibility to use fuel cell in distributed powergeneration systems [6-8]. Nonetheless, one of themain weak points of fuel cell is its slow dynamics.In reality, the dynamics of fuel cell is limited by thehydrogen and oxygen delivery system, which containspumps and valves, and in some cases a hydrogen re-forming process [9-11]. Especially, a step in the loadpower demand will imply huge variation of the dc busvoltage, because the main source has a slow dynamicresponse. Moreover, in distributed system, the dcbus voltage control has problem when electrical loadsdemand or recover high energy in short time (for ex-ample, while motors start or brake).

To solve these problems, the system must have afast auxiliary source, to supply or to absorb high tran-sient energy. The new high current supercapacitortechnology has been developed for this purpose [12-16]. Then the very fast power response of superca-pacitors can be used to complement the slower poweroutput of the fuel cell to produce the compatibilityand performance characteristics needed by automo-tive system as shown in Fig. 1.

In addition, fuel cell has slow dynamics by natural.If it is operated in nearly steady state condition inorder to avoid speedy transition of fuel cell current,mechanical stresses are avoid, and lifetime of the fuelcell stack will increase [17-19].

This paper presents principles of fuel cell and su-percapacitor, and proposes a small-scale test bench

composes of a PEM fuel cell as main source and su-percapacitors as auxiliary source for a 42 V dc bus.It especially details the new control strategy based



Fuel Cell and Supercapacitors for Automotive Hybrid Electrical System 21

Fig.1: Fuel Cel l and Supercapacitors for AutomotiveSystem.

on power conditioning between the two sources tak-ing into account the low dynamics of the fuel cell.The experimental results are composed of two parts;the rst one shows PEM fuel cell characteristics whenconnecting with converter to the dc bus; the secondone shows hybrid characteristics for different situa-tions while connecting to dc bus in order to authen-ticate system operation.

2. FUEL CELL

2.1 Principle of Operation [2,20]

The developments leading to an operational fuelcell can be traced back to the early 1800’s with Sir

William Grove recognized as the discoverer in 1839.A fuel cell is an energy conversion device that con-

verts the chemical energy of a fuel directly into elec-tricity. Energy is released whenever a fuel (hydrogen)reacts chemically with the oxygen of air. The reactionoccurs electrochemically, and the energy is released asa combination of low-voltage dc electrical energy andheat.

Types of fuel cells differ principally by the type of electrolyte they utilize as present in Fig. 2. The typesof electrolyte, which is a substance that conducts ions,determine the operating temperature, which varieswidely between types (table 1).

Proton Exchange Membrane (or “solid polymer”)Fuel Cell (PEMFC) is presently the most promisingtype of fuel cells for automotive applications and hasbeen used in the majority of prototypes built to date.Accordingly, this research focuses exclusively on thistype of fuel cell.

The structure of a cell is represented in Fig. 3.Flowing along the x direction the gases come fromchannels designed in the bipolar plates (thickness 1-10 mm). Vapor water is added to gases to humidifythe membrane. The diffusion layers (100-500 µm) en-sure a good distribution of the gases to the reaction

layers (5-50 µm). These layers constitute the elec-trodes of the cell made of platinum particles, whichplay the role of catalyst, deposited within a carbon

Fig.2: Principle of Acid (top) and Alkaline (bottom)Electrolytes Fuel Cells.

support on the membrane.

Fig.3: Different Layers of an Elementary Cell.

Hydrogen oxidation and oxygen reduction:

H 2 → 2H + + 2 e − anode (1)

2H + + 2 e − +12

O2 → H 2 O cathode

are separated by the membrane (20-200 µm) whichcarries protons from the anode to the cathode and isimpermeable to electrons. This ow of protons dragswater molecules as gradient of humidity leads to adiffusion of water according to the local humidity of the membrane. Water molecules can then go in bothdirections inside the membrane according to the sidewhere the gases are humidied and to the current den-

sity which is directly link to the proton ow throughthe membrane and to the water produced on the cath-ode side.




Table 1: Different Types of Fuel Cells, Ion Crossing the Electrolyte, Operating Temperature and Typical Applications [1].

Electrons, which appear on the anode side, cannotcross the membrane and are used in the external cir-cuit before returning to the cathode. Proton ow isdirectly linked to the current density:

J H =iF

(2)

where F is the Faraday’s constant.The value of the output voltage of the cell is given

by Gibb’s free energy ∆G and is:

V rev = −∆ G2F

= 1 .23V (3)

This theoretical value is never reached even at noload. For the rated current (around 0.5 A.cm-2), thevoltage of an elementary cell is about 0.6-0.7 V. Thena fuel cell is always an assembly of elementary cellswhich constitute a stack as shown in Fig. 4.

Fig.4: Example of PEMFC stack (23 cells).

Fig. 4 shows some of the tubes which deliveredgases, a stack having usually 2 × 4 connections: 2

wires for the current, 2 × 2 tubes for the gases and1× 2 tubes for the cooling system. As the gases aresupplied in excess to ensure a good operating of thecell, the non-consumed gases have to leave the fuel cellcarrying with them the produced water. Generally,

a water circuit is used to impose the operating tem-perature of the fuel cell (approximately 60-70 C). Atstart up, the fuel cell is warmed and later cooled as atthe rated current nearly the same amount of energy isproduced under heat form than under electrical form.

3. SUPERCAPACITOR

Basically, the three factors to realize massive ca-pacitance are the physical surface area of the two elec-trodes, the distance between them, and the type of dielectric material. Instead of metal plates, porouscarbon electrodes (nanostructured carbons) are em-ployed. The extremely small pores measured innanometers in such carbons give the material a verylarge active internal surface, in the order of 1000m 2 .g − 1 . The activated carbon electrodes are sepa-rated by a porous membrane (paper, polymer mem-branes or glass bers) in an organic electrolyte as de-picted in Fig. 5. A supercapacitor according to thisprinciple is frequently called an electric double layer(EDL) capacitor [21,22].

Fig.5: Principle of a Supercapacitor.

Compared with batteries, supercapacitors have atleast two orders of magnitude higher specic powers,and much longer lifetime. Because they are capable of millions cycles, they are virtually free of maintenance.Their great rated currents enable fast discharges andfast charges as well. Their quite low specic energy,compared to batteries, is in most cases the factor thatdetermines the feasibility of their use in a particularhigh power application [23-26].

4. HYBRID SYSTEM STRUCTURE

4.1 Fuel Cell Converter

Fuel cell operates giving direct current, and at alow voltage; thereby, the boost converter, presented




The “Hybrid control algorithm” as explained here-after does the choice among these three references.

Firstly, during normal operation, when iSuperC 3

is zero, supercapacitors are charged by the fuel cellup to the voltage level V SuperCNormal , which is

within the previously dened interval [ V SuperCMin ,V SuperCMax ]. To meet this target, “Fuel cell currentcontroller2” is supplied with rated fuel cell current asreference, I FCRated , corresponding to rated fuel cellpower. “Supercapacitor voltage controller” is sup-plied with V SuperCNormal as reference.

The following example will illustrate the calcula-tion of current references iSuperC 1 and iSuperC 2 . Forthe considered test bench, the maximum power levelat the dc bus P Max is equal to 441 W, which cor-responds to a rated fuel cell current of 40 A. For asteady state operation of the dc bus with for examplea load power P Load of 200 W, let consider the casewhere the supercapacitor voltage vSuperC is equalto 5 V. The supercapacitors have to be charged toV SuperCNormal , here 14 V. If assuming now that pro-portional gain of “Supercapacitors voltage controller”is 50, one obtains for current reference iSuperC 2 avalue of 450 A which corresponds to a power of 2,250W. This is higher than P Max , so that this referencecannot be used.

In contrast, “Fuel cell current controller2” gener-ates iSuperC1 by I corrector, which will automaticallygenerate the accurate value to obtain zero steadystate error. As it is necessary to charge the super-

capacitors, the fuel cell current reference iFCREF2 isequal to the rated current of 40 A. From “Fuel cellcurrent controller2”, one obtains a current iSuperC1of 48 A, by (441W-200W)/5V (assuming here thatconverters have no losses).

The “Hybrid Control Algorithm” will chose theminimum value between iSuperC 1 and iSuperC 2 . If iSuperCREF is equal to iSuperC 1 , the system workswith a value which corresponds to the available fuelcell power. Then, supercapacitors end of charge willbe controlled by voltage loop. When this one oc-curs iSuperCREF becomes iSuperC 2 . On the consid-ered test bench, when vSuperC reaches 13.56 V, refer-ence iSuperC 2 becomes lower than reference iSuperC 1 ,to prepare the end of charge.

Note that during this operation, charging currenthas to be limited in rate of change, in order to avoidinstability due to a too fast increasing current, whichwould be seen as a peak load by the system. Notealso that each transition in the normal mode beginswith the initialization of the integrator of “Fuel cellcurrent controller2”.

Secondly, when one of the two limitations (rate of change, and level) on fuel cell power reference is work-ing, a non-zero iSuperC 3 signal is generated, which can

be positive or negative, depending on power conditionat the dc bus.Therefore, in the case of discharge mode, charac-

terized by a fast transient increasing load, or by apower load greater than P FCMax , the current refer-ence iSuperC 3 becomes negative in order to transferthe lacking energy to the dc bus. “Supercapacitorvoltage controller” is supplied with V SuperCMin as

reference, and the “Hybrid control algorithm” leadsto select the maximum value between iSuperC 3 andiSuperC 2 if supercapacitor voltage is greater thanV SuperCMin , zero otherwise.

On the other hand, in the case of recovery mode(transient fast decreasing load, or power load lessthan P FCMin ), the current reference iSuperC 3 be-comes positive. “Supercapacitor voltage controller” issupplied with V SuperCMax as reference, and the “Hy-brid control algorithm” leads to select the minimumvalue between iSuperC 3 and iSuperC 2 if supercapacitorvoltage is less than V SuperCMax , zero otherwise.

In the two cases ( iSuperC 3 is positive or negative),

the reference and integrator of “Fuel cell current con-troller2” are set to zero for prevision of the next nor-mal operation as shown in Fig. 8 by the “ControlSignal”.

Finally, note that iSuperC 3 , which is sensitive to dcbus disturbance (noise immunity), to switching andto ESR of supercapacitors, has to be ltered beforesending to hysteresis switch in order to dene hybridsystem modes of operation. This lter and hystere-sis comparator will be done numerically within the“Hybrid Control System”.

5. HYBRID SYSTEM IMPLEMENTATION

Fig. 9 depicts hybrid system implementation forsystem algorithm in Matlab/Simulink block diagramfor dSPACE (CP1104) interfacing card. The hybridsystem communicates with operator by ControlDeskfrom computer screen, and contacts with converter(vBus , vSuperC ), and so forth) by DAC (Digital toAnalogue Conversion) and ADC (Analogue to DigitalConversion) of dSPACE interfacing card. dSPACEsystem generates current references which are sentto fuel cell and supercapacitor current controllers.These last ones are realized by analogical circuits inorder to operate with a high bandwidth.

Notice that motor controller is considered as a loadat the dc bus. It does not relate with the hybrid con-trol algorithm, which is independent from load cur-rent.

6. EXPERIMENTAL RESULTS AND DIS-CUSSIONS

Fig. 10 shows the simplied diagram of the PEMfuel cell system used for this research. Constructedby Zentrum f ur Sonnenenergie und Wasserstoff-Forschung (ZSW), Ulm, Germany, the fuel cell stackis composed of 23 cells of 100cm 2 . It is supplied with

pure hydrogen (stored under pressure in bottles) andair from a compressor. Additionally, the hardwaretest bench structure is presented in Fig. 11.




Fig.8: Hybrid System Control Structure.

Fig.9: Hybrid System Context Diagram.

6.1 Fuel Cell Converter Testing with an IdealPower Supply

First testing is performed using an ideal 12.5Vpower supply, which has the same rated voltage asthe fuel cell, in order to conrm that the boost con-

verter can operate correctly and to compare fuel celland ideal power supply characteristics.Fig. 12 shows the input current response with a

Fig.10: Simplied Diagram of the 500 W PEM Fuel

Cell System.

stepped current command. It shows that current re-sponse has high dynamics with optimum response bycurrent controller (PID).

6.2 Fuel Cell Converter Testing with a PEMFuel Cell

In a practical system, when fuel cell is operated,its fuel ow is controlled by fuel cell processor, whichreceives current demand from current reference as

shown in Fig. 8. The fuel cell processor links thereactant delivery rate to the usage rate [8, 9].Nevertheless, to present the fuel cell characteris-




Fig.11: Hybrid System Test Bench.

Fig.12: Current Response to a 10 - 40 A Step.

tics, this test bench is operated in two different waysfor fuel ow,• Firstly, fuel cell works at constant fuel ow corre-sponding to the maximum available current of 50 A.In this case, the fuel cell has always enough hydrogenand oxygen.• Secondly, the fuel ow varies depending on fuel cellcurrent reference.As shown in Fig. 13, dynamic response of fuel cellcurrent is different from Fig. 12. There are twoways to explain this phenomenon. Firstly, by elec-trical way, the electrical fuel cell model is different

from an ideal power supply. Secondly, by physicalway, the phenomenon is due to the slowness of itsthermodynamic operation.

Fig.13: Fuel Cell Current Response to a 10-40 AStep at Constant Fuel Flow for 50 A.

And, Fig. 14 shows the effect of mechanical prob-lems. It can be seen from fuel cell voltage that itdrops lower than on Fig. 13. This means that its fuelsupply and delivered electrical current do not coin-cide. Fuel ow is not enough for converter current.This condition of operating is hazardous for the fuelcell stack. For this reason, a fast auxiliary powersource must be used to cooperate with fuel cell inorder to limit speedy transition of fuel cell current.

At least, the characteristics of the PEMFC, insteady-state when connecting with converter, are pre-sented in Fig. 15. It can be distinguished thatthe PEMFC contains complex impedance component,which it is not purely resistive at a switching fre-quency of 25 kHz [20].

6.3 Hybrid System Test Bench

As storage device, hybrid system utilizes six SAFTsupercapacitors (capacitance: 3,500 F, rated voltage:

2.5 V, rated current: 400 A, series resistance: 0.8mΩ ) connected in series. Technical specications of the control process are as follows: P F CRated = 500




Fig.14: Fuel Cell Current Response to a 10-40 AStep at Variable Fuel Flow.

Fig.15: PEM Fuel Cell Characteristics at Rated Power (top: FC Voltage Ripple [250 mV/Div], bot-

tom: FC Current [10 A/div]).

Fig.16: Hybrid Response to a Stepped Load.

W, P FCMin = 50 W, P FCMax = 530 W, I F CRated

= 40 A, V SuperCNormal = 13 V, V SuperCMin = 8 V,V SuperCMax = 15 V, and power slope of fuel cell is50 W. s − 1 (around 8.5 A. s − 1 ) while current slope of fuel cell for charging supercapacitors is limited to 4A.s − 1 .

While operating with the supercapacitors, the fuelow is not anymore xed to a 50 A current butadapted to the value of the delivered current to im-prove the efficiency of the system.

Fig. 16 shows transient responses to a steppedload, which corresponds nearly to a 10-40 A step of the fuel cell current. One can observe that the dcbus voltage is well regulated, and that fuel cell cur-rent smoothly increases with a slope of 8.5 A. s − 1 .Furthermore, during transient state, supercapacitorstransfer energy back to the dc bus in order to com-pensate the energy, which is not supplied by the mainsource.

Fig. 17 presents hybrid characteristics during nor-mal operation, through supercapacitors charge from12 V to 13 V. The dc bus has a constant load of about10 A delivered by the main source. At the beginningof charge at t = 3 s, iSuperCREF is iSuperC 1 . It can beobserved that fuel cell current slope is approximately

4 A.s− 1

, which is lower than the previous 8.5 A. s− 1

,necessary condition for stability. Furthermore, duringthe charging process the fuel cell delivered its rated




Fig.17: Charging Supercapacitors from 12 V to13 V.

current. Besides, the transition of iSuperCREF fromiSuperC 1 to iSuperC 2 occurs (end of charge) at t =25 s, for a supercapacitor voltage of nearly 13 V, be-cause of the use of a high proportional gain (200) forsupercapacitor voltage controller.

Fig. 18 presents transient responses of the hybridsystem to an excessive load. Before this test, superca-pacitor voltage is equal to V SuperCNormal = 13 V. Thesupercapacitors compensate the main source duringboth transient state and steady state, because of fuel

cell current slope and fuel cell power limitations. Dur-ing the rst interval, beginning at t = 4 s, the currentdelivered by the main source slowly increases (with acontrolled slope) up to its maximum value, the lack-ing energy being delivered by supercapacitors from t= 7.8 s to 18 s. Then, the sudden decrease of thepower load at t = 18 s leads to a recovery mode forsupercapacitors, in order to allow a slow controlleddecrease of the fuel cell current.

Fig. 19 corresponds to a sudden recovery of energyon the dc bus. This energy is recovered by the super-capacitors while a slow decreasing of the main source

current is performed. In this example, fuel cell neverdelivered less than 50 W in order to maintain fuel cellconverter operating in continuous current mode.

Fig.18: Hybrid System Response when Overloading.

Fig.19: Hybrid System Response when Recovering.




7. CONCLUSION

The main objective of this work is to propose a newmethod of controlling an automotive dc bus suppliedby a hybrid source using supercapacitors as auxiliarysource, in association with a PEM fuel cell as mainsource, knowing that this kind of electrical source isnot able to supply energy during fast transitions of load because of current slope limitation, during peakloads because of power limitation, and during recov-ery because of only positive current delivering.

The experimental results with a 500 W PEM fuelcell conrm the slow dynamic response of the system,due to both thermodynamic and mechanical phenom-ena. Results carried out by means of a hybrid systemtest bench, which uses a storage device composed of six SAFT 3,500 F supercapacitors connected in series,have shown the possibility to improve the transient

performance of the system and validate the proposedcontrol principle.This control principle can be also applied with

other kinds of auxiliary power source, such as Li-Ionbatteries, and with other kinds of main sources.

ACKNOWLEDGEMENT

This research is partially supported by French Na-tional Center for Scientic Research (CNRS) andNancy Research Group in Electrical Engineering(GREEN, UMR CNRS 7037).

References

[1] S. Thomas and M. Zalbowitz, Fuel Cells - Green Power , prepared for the U.S. Department of En-ergy, under contract W-7405- ENG-36, Available:http://education.lanl.gov/resources/fuelcells/fuelcells.pdf.

[2] J. Larminie and A. Dicks, Fuel cell systems ex-plained , John Wiley and Sons, Inc., New York,2000, pp. 1-43.

[3] D. McKay and A. Stefanopoulou, “Parameteriza-tion and Validation of a Lumped Parameter Diffu-sion Model for Fuel Cell Stack Membrane Humid-ity Estimation,” in Proc. 2004 IEEE-American Control Conf. , June 30 - July 2, 2004, Boston,MA.

[4] K. J. Kelly and A. Rajagopalan, Bench-marking of OEM hybrid electric vehicles at NREL , prepared for the DOE, Contract No.DE-AC36-99-GO10337, August 2001, Available:http://www.eere.energy. gov.

[5] U.S. Department of Energy, Thunder Power bus evaluation at Sun Line Transit Agency ,DOE/GO-102003-1786, November 2003, Avail-able: http:// www.eere.energy.gov.

[6] C. Jeraputra and P.N. Enjeti, “Development of a robust anti-islanding algorithm for utility inter-connection of distributed fuel cell powered gener-

ation,” IEEE Trans. on Power Electronics , Vol.19, No. 5, Sep. 2004, pp. 1163- 1170.

[7] S.K. Mazumder et al, “Solid-oxide-fuel-cell per-formance and durability: resolution of the ef-fects of power-conditioning systems and applica-

tion loads,” IEEE Trans. on Power Electronics ,Vol. 19, No. 5, Sep. 2004, pp. 1263- 1278.[8] J. Wang et al, “Low cost fuel cell converter system

for residential power generation,” IEEE Trans. onPower Electronics, Vol. 19, No. 5, Sep. 2004, pp.1315-1322.

[9] P.T. Krein, R.S. Balog and Xin Geng, “High-frequency link inverter for fuel cells based onmultiple-carrier PWM,” IEEE Trans. on Power Electronics , Vol. 19, No. 5, Sep. 2004, pp. 1279-1288.

[10] A. Vahidi, A.G. Stefanopoulou and H. Peng,“Model Predictive Control for Starvation Preven-tion in a Hybrid Fuel Cell System,” in Proc. 2004IEEE-American Control Conf. , 2004, June 30 -July 2, 2004, Boston, MA.

[11] P. Thounthong, S. Rael and B. Davat,“Test of a PEM fuel cell with low volt-age static converter,” Journal of Power Sources , Available: http://authors. else-vier.com/sd/article/S0378775305001564

[12] E. J. Cegnar, H. L. Hess and B. K. Johnson,“A Purely Ultracapacitor Energy Storage Systemfor Hybrid Electric Vehicles Utilizing a Microcon-troller Based dc-dc Boost Converter,” in Proc.

IEEE-APEC’2004 , Feb. 22-26, 2004, Anaheim,California-USA.[13] J. M. Miller, “Ultracapacitors Challenge the

Battery,” The world and I Magazine , June 2004,pp.130-137.

[14] B. Maher, “A Backup Power System UsingUltracapacitors,” Power Electronics Technology Magazine , Sep 01, 2004, pp. 44-49.

[15] Y. Kim, “Ultracapacitor Technology PowersElectronic Circuits” Power Electronics Technol-ogy Magazine, Oct 01, 2003, pp. 34-39.

[16] B. Maher, “Ultracapacitors and the Hybrid Elec-tric Vehicle,” Passive Component Industry Maga-zine, March/April 2001, pp. 30-36.

[17] J.T. Pukrushpan, A.G. Stefanopoulou and H.Peng, “Controlling Fuel Cell Breathing,” IEEE Control Systems Magazine , Vol. 24/2, April, 2004,pp. 30-46.

[18] P. Thounthong, S. Rael and B. Davat, “TestBench of a PEM Fuel Cell with Low Voltage StaticConverter,” in Proc. The 2004 Fuel Cell Seminar ,(CDROM), Texas-USA, November 1-5, 2004.

[19] P. Thounthong, S. Rael and B. Davat, “Utiliz-ing Fuel Cell and Supercapacitors for AutomotiveHybrid Electrical System,” in Proc. IEEE-APEC

2005 Conf., Texas-USA, March 6-10, 2005.[20] W. Friede, S. Rael and B. Davat, “Mathemati-cal Model and Characterization of the Transient




Behavior of a PEM Fuel Cell,” IEEE Trans. on Power Electronics , Vol. 19, No. 5, Sept. 2004, pp.1234-1241.

[21] R. Kotz and M. Carlen, “Principles and applica-tions of electrochemical capacitors,” Electrochim-

ica Acta , Vol: 45, Issues 15-16, May 3, 2000, pp.2483-2498.[22] A. Burke, “Ultracapacitors: why, how, and

where is the technology,” Journal of Power Sources , Vol. 91, Issue 1, Nov.

[23] A. Rufer and P. Barrade, “A Supercapacitor-Based Energy-Storage System for Elevators WithSoft Commutated Interface,” IEEE Trans. on In-dustry Applications , Vol. 38, Issue: 5, Sept./Oct.2002, pp. 1151-1159.

[24] A. Rufer, D. Hotellier and P. Barrade, “ASupercapacitor-Based Energy-Storage Substationfor Voltage-Compensation in Weak Transporta-

tion Networks,” IEEE Trans. on Power Delivery ,Vol. 19, No. 2, April 2004, pp. 629-636.

[25] J. W. Dixon and M.E. Ortuzar, “Ultracapacitors+ DC-DC Converters in Regenerative BrakingSystem,” IEEE Aerospace and Electronics Sys-tems Magazine , vol. 17, Issue: 8, Aug. 2002, pp.16 -21.

[26] M. Ortuzar, J. Dixon and J. Moreno, “Design,Construction and Performance of a Buck-BoostConverter for an Ultracapacitor-Based AuxiliaryEnergy System for Electric Vehicles”, in Proc.IEEE-IECON2003 , Nov. 2-6, 2003, Roanoke, Vir-ginia, USA, (CDROM).

[27] M. Y. Ayad, S. Rael and B. Davat, “HybridPower Source Using Supercapacitors and Bat-teries,” in Proc. EPE’03 Conf. , Toulouse-France,Sept. 2003.

[28] W. Choi, P. Enjeti and J. W. Howze, “Fuel CellPowered UPS Systems: Design Considerations,”in Proc. IEEE-PESC’03 Conf. , Acapulco, June2003.

[29] P. Thounthong, S. Rael and B. Davat, “Super-capacitors as an Energy Storage for Fuel CellAutomotive Hybrid Electrical System,” in Proc.ESSCAP’2004 1st European Symposium on Su-

percapacitors & Applications, (CDROM) , Belfort-France, Nov. 4-5, 2004.

Phatiphat Thounthong received theB.S. in Technical Education in Elec-trical Engineering and M.E. degreein Electrical Engineering both fromKing Mongkut’s Institute of TechnologyNorth Bangkok (KMITNB), Bangkok,Thailand, in 1996 and 2000, respec-tively. In 1997, he worked as elec-trical engineer in E.R. Metal WorksLtd. (EKARAT GROUP). In 1998 to2000, he was an assistant lecturer at

KMITNB. Nowadays, he is preparing a Ph.D dissertationabout utilizing fuel cells and supercapacitors in electrical ve-hicle at ENSEM, Institut National Polytechnique de Lorraine(INPL), France.

S tphane Rael received the Engineerdegree at ENSIEG, Grenoble, France in1992, and the Ph.D degree from Insti-tut National Polytechnique de Grenoble(INPG) in 1996. Since 1998, he has beenworking as associate Professor at EN-SEM, INPL in the eld of power elec-

tronic components, supercapacitor, bat-tery and fuel cell.

Bernard Davat received the Engineerdegree at ENSEEIHT, Toulouse, Francein 1975, the Ph.D degree in 1978 and the“Docteur d’Etat” degree in 1978, bothfrom Institut National Polytechnique deToulouse (INPT). During 1980-1988, heworked as researcher at CNRS (FrenchNational Center for Scientic Research)at LEEI. Since 1988, he has been work-ing as Professor at ENSEM, INPL. Hismain research interests deal with power

electronics and new electrical devices (fuel cell and superca-pacitor).

fuel cell and super capacitors

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