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NASA Investments in Electric Propulsion Technologies for Large Commercial Aircraft

Cheryl Bowman

NASA Glenn Research Center November 28, 2016

National Aeronautics and Space Administration

www.nasa.gov

Perspective on Electrified Aircraft Propulsion

Strategic Thrusts Guide NASA

Investment Decisions


www.nasa.gov

Perspective on Electrified Aircraft Propulsion

Address Key Challenges• Electrical system weight

• Energy storage capabilities

• Thermal management

• Flight controls

• Safety

• Certification

Small

Single

Aisle

Large Single

Aisle

Small

Twin

Aisle

Large

Twin

Aisle

Very

Large

Aircraft

2012 Fuel Consumption, FAA US Operations

Data. Analysis by H Pfaender, GA Tech

Regional

Jet

Turbo

prop

Explore alternative propulsion systems that can reduce carbon,

noise, and emissions from commercial aviation

• Potential for vehicle system efficiency gains (use less energy)

• Leverage advances in other transportation and energy sectors

• Address aviation-unique challenges (e.g. weight, altitude)


www.nasa.gov

Technology Investment Strategy

…

Concept B

Concept A

Baseline Future Vehicle

Predicted Available Technologies

Concept that closes w/ Net

Benefit

Derive Key Powertrain

Performance Parameters

Dissect Contributors

to Weight and Loss in

SOA

Derive Key Subcomponent Performance Parameters

Calculated

power and

efficiency

curves, etc.

Vehicle Systems

Studies including

missions profile,

propulsion

system, CFD

Materials and

electromagnetic

properties, EMI,

fault tolerance,

etc.

Investments informed by concepts plus systems-level testbedsWith successively higher fidelity

Build, test, fly, learn at successively higher power and voltage levels

Validate the vehicle architecture as well as component performance


www.nasa.gov

Baseline Aircraft with

Podded Turbo-FanVEHICLE CONFIGURATION EXAMPLES

X-57 Maxwell 4 PAX Plane SUGAR VOLT 150 PAX Study

STARC-ABL 150 PAX Study

N3-X 300 PAX Turbo-ElectricCurrent NRA 150 PAX StudiesAATT 50 PAX Studies

ECO-150 150 PAX Studies

Electrified Propulsion Vehicle Configurations

Potential for earlier

entry into service

Higher potential

and longer term


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Introduction of Alternative Propulsion Systems

Build, Test, Mature Enabling Technologies and Knowledge Bases


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Notional Vehicle Power System Requirements

7

Component Quantity Specific Power Efficiency Size

Weight

(kg)

Losses

(kW)

Battery 1 208 W-hr/kg 93.0% 381 kW 1833 36

Generator 1 6.0 kW/kg 96.0% 230 kW 38.3 10

Rectifier 1 13.0 kW/kg 98.0% 225 kW 17.3 5

Cable (2 pairs 33 ft),

400 V/477 A) 2 170.0 A/(kg/m) 99.6% 191 kW 112.1 2

Circuit Protection

(inverters, battery, rectifier) 200.0 kW/kg 99.5% 754 kW 3.8 0

High Lift Inverter 6 13.0 kW/kg 98.0% 34 kW 15.9 4

High Lift Motor 6 6.0 kW/kg 96.0% 33 kW 33.0 8

Cruise Inverter 2 13.0 kW/kg 98.0% 156 kW 24.0 6

Cruise Electric Motor 2 6.0 kW/kg 96.0% 150 kW 50.0 13

Thermal Management System 0.68 kW/kg 0.0% 83kW 122.6

Total System 82.1% 2250 83

Ref: Jansen et al., AIAA, 2016


www.nasa.gov


8

Component Quantity Specific Power Efficiency

(%)

Power

(kW)

Weight

(kg)

Losses

(kW)

Generator (2) 2 13.0 kW/kg 96.0% 1400 215 117

Rectifier (2) 2 19.0 kW/kg 99.0% 1386 146 28

Cable 2 170 A/(kg/m) 99.6% 1380 192 11

Circuit Protection 4 200 kW/kg 99.5% 1373 13.6 28

Inverter 1 19.0 kW/kg 99.0% 2719 143 27

Electric Motor 1 13.0 kW/kg 96.0% 2610 201 109

Thermal System 0.68 kW/kg 291 470

Total System 89.1% 1394 320

Ref: Jansen et al., AIAA, 2016


www.nasa.gov


Ref: H-D Kim 2014; Armstrong CR-2013-217865

Left Side Superconducting

Propulsor Motor

Right Side Superconducting

Propulsor Motor

Normally Closed SSCB

Normally Open SSCB

SFCLSuperconducting

Generator

Rectifier

Inverter

Superconducting

Magnetic Energy Storage

Superconducting

Fault Current Limiter


Propulsor Motor


Propulsor Motor


Normally Open SSCB

SFCLSuperconducting

Generator

Rectifier

Inverter

Superconducting


Superconducting



Propulsor Motor


Propulsor Motor


Normally Open SSCB

SFCLSuperconducting

Generator

Rectifier

Inverter

Superconducting


Superconducting


Component QuantitySpecific Power

(kW/kg)Efficiency

Power

(MW)

Weight

(kg)

Losses

(kW)

Generator 4 40 99.8 12.5 1250 100

Rectifier 4 35 99.4 12.4 1417 298

Cables, Transmission 4 250 A/kg/m 99.9 12.4 150 50

Cables, Feeder 16 250 A/kg/m 99.9 3 150 48

Circuit Protection (simplified) >48 200 99.5 1.8 -12.5 2k - 4k >400

Inverter 16 35 99.4 1.79 818 172

Motor 16 40 99.8 1.8 720 58

Total System 6500 - 8500 >1100


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Typical TRL 9 motors have performance outside target zone

Electric Machine State of the Art

10

UAV (Launchpoint) 100 kW

10.7 kW/kg (6.5hp/lb), 93%

efficiency -- Can this

performance be extended to

higher power?

Industrial Motors, 0.5-1MW, ~0.17

kW/kg (0.1 hp/lb), 96% efficiency

2008 Lexus, 110kW, 2.5kW/kg

(1.5 hp/lb), 91% efficiency

Lines represent performance boundary targets

2018 NASA Sponsored

1 MW Demo


www.nasa.gov

Why Superconducting Electric MachinesSuperconducting (infinitely small direct conduction loss) leads to much higher

specific power and greatly enhances feasibility for larger aircraft dist. propulsion

TRL 2-3: Projections for fully

superconducting electric

machines greatly exceed those

for other motor types.

11

TRL 3-4: Wind turbine industry

is considering superconducting

power generation for volume

reduction and improved

component lives

TRL 7: Limited data on specific power, reported values as high as 7 kW/kg

with flat-tape stator wire (HTS fully superconducting, GE, 2007)

TRL 9: Extensive use of dc superconducting magnet coils in medical imaging

Note: Lines represent minimum breakeven

performance for different benefit assumptions.

Components must exceed minimum drive system

performance

/api.viglink.com/api/click


www.nasa.gov

Enabling Materials

•Use composite materials systems and advanced manufacturing techniques

•Concurrently tailor component materials for hybrid/turbo electric applications and

design power components that utilize advance materials

Dielectrics and Insulation

Improve electrical insulation systems

• Study interface functionalization to enable new composite formulations

• Increase both the thermal conductivity and high voltage stability

High Conductivity Copper

High risk, high pay-off investment in carbon nano-tube (CNT)/copper

composites

• Chemical engineered CNT interfaces

• Sorted CNTs to isolate the metallic conducting from semi-conducting

• SBIR investment in new manufacturing techniquesCu-coated CNT’s

Magnetic Materials

Enable high frequency operation with low electrical losses

• Collaborate with industry and academia to produce nano-crystalline

magnetic material

• Perform alloy development and microstructural stability of soft magnetic

alloys

• Support power electronic component development using new alloys

Hi Voltage

Dielectric

Testing

0.75 miles of continuous

soft magnetic ribbon


www.nasa.gov

Batteries for Aviation

What can be done now

• Current State of the Art Batteries have

specific energy in the range of 150-

250W-hr/kg

• 1-2 person airplanes using this battery

technology have been demonstrated to

TRL level 6

• Studies have shown that larger planes

(9-50 PAX) can use electric technology

for short range or in combination with

range extenders (hybrid electric) when

battery system have specific energies

of 200-300 W-hr/kg

The benefit of advanced batteries

• Improvements in battery technology

allows electric and hybrid electric

systems to be extended into larger

plane classes (50PAX and greater)

and longer range missions (>200

miles)

• With these battery improvements the

carbon impacts can be much more

substantial than a system which relies

primarily on jet fuel as it energy source

• Additionally, studies on smaller aircraft

indicate that operational cost

improvements can result from the

greater use of battery systems for the

short range.

13


www.nasa.gov

Highly Efficient

Turbine Engines

Power Systems

Architectures

Advanced Electrical

Components

Boundary-Layer

Ingestion Systems

Efficient, Low

Noise Propulsors

Integrated Vehicles and

Concepts Evaluation

Electrified Propulsion in Technology Suite

Electrified Propulsion

Vehicle Configurations


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Nearer Term Vehicle Configuration Examples

• Parallel Hybrid options studied in detail because podded configurations may

allow fleet retro-fit or earlier entry into service

• Single Propulsor Distribution studied to explore minimal airframe modification

Boeing

SUGAR VOLT

Cruise Hybrid

UTRC

TO / Climb

Hybrid

R-R NA

Fleet Opt

Hybrid

NASA

Turboelectric

Aft BLI

Study Fidelity / TRL Detailed

analysis down

to subsystem

Detailed

analysis down

to subsystem

Detailed

analysis down

to subsystem

High level;

airframe and

prop. system

In-Flight Fuel Saving

for 900nm14% 6% 24% 7%

In-Flight Energy

Saving for 900nm0% 2.5% 7% 7%

In-Flight Emission

Reduction~ 14% ~ 6% >24% ~ 7%

Noise Reduction

Potential

Low, fan stays

the same

Low, fan stays

the same

Moderate, fan &

core smaller

Moderate, fan &

core smaller

These studies were performed with independent assumptions.

Improvements are referenced to separate baselines.


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Configurations Inform Technology Investment

The technology development needs determined from configuration studies

• Elucidate challenges associated with electrified propulsion development

• Inform research investments

Energy Storage Electrical Dist. Turbine Integration Aircraft Integration

Battery Energy

Density

High Voltage

Distribution

Fan Operability with

different shaft

control

Stowing fuel &

batteries; swapping

batteries

Battery System

Cooling

Thermal Mang’t of

low quality heat

Small Core Dev’t

and control

Propulsor design &

integration

Power/Fault Mang’t Mech. Integration Integrated Controls

Machine Efficiency

& PowerHi Power Extraction

Robust Power Elec.

Parallel Hybrid Specific Common to Both Turboelectric Specific

Color Legend:


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Non-Superconducting Electric Machines

Improved motor/generator topology options enabled by advanced power

electronics

Better specific power or power density due to advanced design & manufacturing

processes.

Emerging wide-band gap

devices enable high

frequency operation with

lower switching-frequency

losses

New materials and

fabrication developments

will push specific power

farther

Rapid advancements in machines and power electronics


www.nasa.gov

TRL 2-3 Motor design analysis for 1 MW size predicts performance feasibility

Electric Machine Development Potential

19

NRA Contract: TRL 4 Demo by

2018 for 1 MW machine with 13

kWkg (8hp/lb), 96% efficiency

(triangle)

Synchronous reluctance motor

optimized for SOA materials (open

circle), with advanced materials

(solid circle)

Interior Permanent Magnet motor

optimized for SOA materials (open

square), with advanced materials

(solid square)

Note: Lines represent minimum breakeven

performance for different benefit assumptions.

Components must exceed minimum drive

system performance

Ref: Duffy et al., AIAA, 2015


www.nasa.gov

NASA Electrified Propulsion Takeaways

• NASA Aeronautics Strategic Thrust 4 -Transition to Low-Carbon

Propulsion is supporting investment in alternative aircraft

propulsion including electrified aircraft propulsion

• The NASA vision includes transforming aviation via new propulsion

technologies integrated with airframes to

– increase aircraft functionality

– reduce carbon emissions

– improve operational efficiency and reduce noise

• There are many possible Electrified Aircraft configurations

• NASA investment includes vehicle concepts and technology to

support commercial transport aircraft through

– Top Down—Vehicle System Analysis, Design, Flight Testing

– Bottoms Up—Power Components Design and Testing

– Closing the Loop—Power System Design and Testing

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