Fuel Cell Friedrich new - electromobility · A320 D-ATRA Development ... New System for Flight Testing Fuel Cell System Air Fuel Cell System for ... Direct Hybrid > Prof.-Dr. K. A

Folie 1Direct Hybrid > Prof.-Dr. K. A. Friedrich > 2011-09-26

Fuel cell systems for mobile applications: a comparison of automotive and aeronautic system design

J. Kallo, J. Ungethüm, K. A. Friedrich

Folie 2

Content

• General introduction electromobility

• Synergies between terrestrial transport and aircraft application

• Multifunctional fuel cell system

• Emission-free taxiing of aircraft

• Efficient electric drives and “direct hybridization”

• System Modeling

Folie 3

Efficiencies

Typical car efficiency (Tank to Wheel):Internal combustion engine: 20 – 25 %

Fuel cell electrical drive: 40 – 50 %

Battery electrical drive: 70 – 80 %

fuel heat movement electricity

fuel electricity

OH

H

chemical energy electricityelectricity

Secondary battery

Folie 4

Efficiency Comparison of Automotive Power Trains

Based on Well-to-Wheel studies of European and Japanese Sources: Concawe, EUCAR, JRC und JHFC

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mis

sion

s / g

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2eq k

m-1

250200150100500Energy Comsumption Well-to-Wheel / MJ (100 km)-1

GasolineDiesel

Hybrid (gasoline)Hybrid (Diesel)

Fuel Cell Powertrainwith 100% H2 from natural gas

Battery drivewith power from 100% EU grid

Fuel Cell Powertrainfrom 100% renewable H2

Battery Powertrainfrom 100% renewable power

Technology Change

Gasoline Japan (JHFC)

Diesel Japan (JHFC)

Hybride Gasoline Japan

Fuel Cell Japan (nowadaysand future)

Battery Japan (Power Mix)

Folie 5

Motivation for Fuel Cell System Application

Ecological and Economical A/C Operation AspectsEcological Aspects:

Emission reductionHigher fuel economyNoise reduction

Economical Aspects:Weight ReductionLow MaintenanceMission ImprovementsElimination of RAT and APUBattery ReductionAPU ~ 20 %

idle ~ 10 %APU ~ 40 %

idle ~ 50 %

Folie 6

Emergency Power

Fuel Tank inerting system

Auxiliary Power

Batteries

Ground SupportEquipment Water Refilling Truck

No pollutants :(HC, NOx, CO, SO2)Less noise

Fuel and CO2:Reduced fuel burn= lower CO2 emissions

Hydrogen supplied fuel cell

Low Emissions System : Fuel Cells

Folie 7

FCEPS – Fuel Cell Emergency Power SystemTest Flight

Provides immediately Power after failure of power generationIntegration into the aircraft body -> independent of flight velocityBenefits compared to Ram Air Turbine:

• Possible weight reduction without influence on flow resistance• Switch-off and reactivation of system is possible • Maximum power independent of flight phase• (flight velocity and flight height)• Less maintainance (no moving parts)

Constant Power during acceleration in flight (30.000ft)!

Folie 8

Inclination Vibrations Temperature Low pressure

Integration and Test in A320 D-ATRA

Development Multifunctional Fuel Cell SystemTechnology Platform

Flight certified architecture and componentsABD 100 und DO160E

Load calculation for mechanical set up

Qualification tests and documentation

Folie 9

Fuel Cell Technology Transfer to Aircraft Application

Mechanical Strenght Simulation

Aircraft ApplicationFunctionality, Architecture, BOP

FC System from Transport Application

Airworthy technology development platform

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New System for Flight Testing Fuel Cell System

Air Fuel Cell System for multifunctional use: Power > 12.5 kW

Water generation and inerting function demonstrated

Folie 11SEITE 11

Multifunctional Fuel Cell System

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LambdaInert @ 10°CLambdaInert @ 1°CLambdaref @ 10°CLambdaref @ 1°C

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Lambdaref LambdaInert1 LambdaInert2 Inerting Requirement

System of 12 kW electrical power with aircraft relevant design shows inert gas generation (oxygen content < 12 Vol.%) and water generation

Major importance is air stoichometry

Modelling for flight operation according to Federal Aviation Administration (FAA) publications

Folie 12

Overview emission free taxiing with fuel cell and electric nose wheel drive

Multifunctional fuel cell system in cargo bay- Output Voltage 300VDC

Fully integrated e-NWD

DC/DC+

DC/AC

ControlBox and Data

Aquisition

High Torque 11.000Nm


Hybridisation Basics

Power and energy source with highenergy densitye.g.. Fuel Cell (or ICE + Generator)

Power and energy source with highpower densitye.g.. Battery

Load

Hybridized Power FC + Batt

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Combined Power FC + Batt [W]Power FC [W]

Hybrid system with 50 kW power12 kWh Li-Ion capacity, 33 kWh H2 electrical energy (50 %)

Battery shut down

Antares System 2nd Generation


Concept of the direct hybrid

Fuel Cell Stack

ElectricLoad

MDC

DC

DC

AC

Battery Pack

Conventional hybrid systemsneed one or two DC/DC converterfor potential separation DC/DC converter are expensiveDC/DC converter reduce system efficiency

Fuel Cell Stack

ElectricLoad

MDC

DC

DC

AC

Battery PackDC

DC Direct hybrid systems donot use any DC/DC converterPotential separation is managed by two diodesNo active current control isnecessaryLoad balancing is achieved bythe polarization characteristicsof fuel cell stack and batteryRecharge is achieved by asingle MOSFET / IGBT

Advantages of the direct hybrid systemNo inductanceHigh efficiencyLower costLight weightReliableMostly passive elements

Disadvantages: no fixed potential


Fuel cell stackSchunk FC-42

Electric loadEL9080-200HP

Li-ion battery packA123 ALM12V60

MOSFET

DiodeCurrent

transducer

Voltmeter

Fuse

Relay

Relay

Switch

The direct hybrid test system at the DLR (small scale)

Stack: Schunk FC-42nominal power: 360Wnominal current: 15Anominal voltage: 24Voperating temperature: 70°Coperating pressure: atmospherecooling medium: air

Battery: A123 ALM12V60 (2s)two blocks in serialnumber of cell per block: 4nominal capacity per block (1C):

4.32Ahnominal voltage per block: 12Vmaximal discharge current: 80A


Fuel Cell – Battery - Direct hybrid principle – Load phase

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BatteryFuel cell

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ybrid

Fuel Cell and Battery characteristics

Operating at voltages UFC > UOCV,Batt- Load delivered by fuel cell only

Operating at voltages UFC < UOCV,Batt- Load delivered by fuel cell and battery

UOCVBatt


Fuel Cell – Battery - Direct hybrid principle - Recharge

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ybrid

Fuel Cell and Battery characteristics

Operating at voltages UFC > UOCV,Batt- Load delivered by fuel cell only

UOCV,Batt

Max. battery voltage UBatt,Max

Rec

harg

e ar

ea

Rechargearea

Operating at voltages UBattMax>UFC>UOCVBatt- Load and recharge current delivered by fuel cell if recharge switch „on“


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Load_UBattery_UFuel cell_ULoad_IBattery_IFuel cell_I

Voltage

Current

Quasi static behavior of the hybrid system

At low electric load power isdelivered by fuel cell only

at higher load fuel cell voltage equals battery voltage, both systems deliver energy

fuel cell power is limitedas its voltage cannot drop below battery voltage

FC + Batthybrid operation

FConly


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current

voltage

Dynamic behaviour of the direct hybrid system

fc only fuel cell and batteryDynamic behaviour wastested using anintermittent load distributionElectric load is changed with± 165A per second(<100ms step)Afterwards it is kept constantfor 30 seconds

load balancing is done automaticallyonly fuel cell delivers current at low loadboth fuel cell and battery delivers current higher loadbattery limits current slope dI/dtbattery delivers current

after fast load step-up


Dynamic behaviour of the direct hybrid system

For medium load battery delivers current only for a short periodFor higher load battery keeps delivering currentFor a few 10th of a second current is delivered fromdouble layer capacity and gas volume effectIn any case fuel cell voltage is kept in acceptable rangeUcell> 580mV

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Direct hybrid – high dynamic and cycling behaviour

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LoadBatteryFuel cellLoadBatteryFuel cell

Demonstration of cyclic operation at the frequency of 2.5Hz and 0% - 100% - 0% fuel cell load in <25ms

- Fuel cell “buffer” effect done by double layer capacitance and gas volume effect- Battery low voltage “safety net” - stable continuous operation


20110711_4

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Power lossPower loss at diodePower loss/Gross power(%)

Diodes

ContactsRelaysWires…

Power losses of the direct hybrid system

Power losses originates byDiodesContact resistanceRelaysWires…

Diode losses raise onlylinear with gross powerDiode losses areapproximately 1.5% of gross power

At nominal power auxiliary losses are additional 2.5%of gross power


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max. Fc current16A (per design)

Fc 44 cells

Fc 42 cells

Fc 40 cells

Umin Fc 42 cells

Umin Fc 44 cells

Umin Fc 40 cells

Bat 9 cells

Bat 8 cells

Bat 7 cells

20110708_11

Design of the direct hybrid system

Characteristic of load balancing is fixed by designVoltage range of battery packdefines the range of hybridoperation 8-cell battery / 42 cell Fc hybrid: hybrid operation between UFc,min = 24 … 26.4V = UBat,OCVthe 42-cell FC-Stack delivers ~12.5 … 16A in that range9-cell battery / 44 cell Fc hybrid:hybrid operation between UFc,min = ~25 … 29.7V = UBat,OCVthe 44-cell FC-Stack delivers ~9.5 … 16A in that range

Flexible design of hybrid characteristicdepending on application


20110708_11

System characteristics at variable battery SOC

The battery voltage depends on current and SOCat 60A battery current:

24.5V at 80% SOC 23.5V at 20% SOC

As fuel cell polarization curve ismuch steeper at high load thanbattery curve, fuel cell currentchanges only slightly with SOC

~15A at 80% SOC, at full load~14A at 20% SOC, at full load

Fuel cell behaviour, range and dynamic is mostly independentfrom battery SOC

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min. Bat voltageat 80% SOC~24.5V

max. Fc currentat 80% SOC

max. Fc currentat 20% SOC

Fc 40 cells

Bat 80% SOC

Bat 50% SOC

Bat 20% SOC

min. Bat voltageat 20% SOC~23.5V

max. Bat current60A (per design)


Direct hybrid – Load and Recharge Phase

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LoadBatteryFuel cellLoadBatteryFuel cell

Voltage

Current

Load Phase

Load + Battery Recharge Phase

- Max battery rechargecurrent defined by number of fuel cells and batteries

- Battery overvoltage protection circuit

Efficient (up to 95%) and reliable recharging process


Hybridized Power FC + Batt

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Combined Power FC + Batt [W]Power FC [W]

DLR – direct hybrid – big scale up to 50 kWel.

Direct Hybrid FC + Battery (Li Ion)Advantages:

- Power boost for critical situations- Fuel cell in max. efficient mode- Very low cost components!

Direct coupling FC + BattBattery shut down

Input for battery research in these areas:- Safety (overvoltage)- Cyclability (durability)- Thermal management - Efficiency (Battery Management System) Hybrid system with 12kWh Li-Ion

Target 3-5kWh LiFePO4


Hybrid Fuel Cell / Battery SystemsUpgrade Antares DLR H2 to Antares DLR H3

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U-I-Kennlinie - 660mbarU-I-Kennlinie - 700mbarU-I-Kennlinie - 806mbarU-I-Kennlinie - 1000mbar

Current [A]

underpressure behaviour

Hybridization

Build up of an improved plane with endurance from 15 to 50 h- third generation fuel cells 35 kWel.- Hybridization improvement > 55 kWel.- improved fuel tank capacity- 30% efficiency gain (motor

and aerodynamics improvement)- Payload up to 250kg (operational)

volta

ge [V

]


Thank you for your attention!

Acknowledgement: DLR Team, Airbus Team and BMWi for funding

Documents

Fuel Cell Friedrich new - electromobility · A320 D-ATRA Development ... New System for Flight Testing Fuel Cell System Air Fuel Cell System for ... Direct Hybrid > Prof.-Dr. K. A