Magnetic Materials Enabling Electrified Aircraft Propulsion

1Advanced Air Transport Technology Project

Advanced Air Vehicles Program

National Aeronautics and Space Administration

www.nasa.gov

Dr. Cheryl Bowman, Hybrid Gas Electric Propulsion Technical Lead

NASA John H. Glenn Research Center

Energy Tech 2017

October 31, 2017

Cleveland, OH

Magnetic Materials Enabling Electrified Aircraft Propulsion

Research Team:

Drs. Alex Leary, Ron Noebe and Randy Bowman

Vladimir Keylin and Grant Feichter



Outline

• How materials research enables electrified aircraft propulsion

• Definition of magnetic materials

• How magnetic materials are used in electric machines and electronics

• Hard/Permanent Magnetic Materials

• Soft Magnetic Material

• Application potential for new soft alloy class

• Manufacturing status and component demonstration status

Electrified Propulsion Requires Increase in Performance



Power Electronic

Higher Operating Frequencies

Lower loss Filtering

Higher Efficiency

Motor/Generator

Magnets for Power Density

Thermal Management

Adv. Manufacturing

Insulation

Batteries/Energy Storage

Cell Chem for Power Density

Pack Eng. for Safety

Materials Research Enables Electrified Propulsion

Vehicle Concepts Informing Materials R&D: • STARC-ABL aircraft concept closes with net fuel burn benefit IF advanced power

components can be developed and implemented

• Other electrified aircraft concepts will require similar improvements

BLI Fans

Distortion Tolerant

Power Architecture

Insulation for HiVolt

Better EMI Protection

Adv. Conductors

Flight Controls and

Mission Profiles

HEIST studies

Concept NRAs

Advancement in Component Materials is Required


Advanced Air Vehicles Program4

Coercivity (A/m)

10-1 100 101 102 103 104 105 106 107

Sa

tura

tio

n M

agn

etiza

tio

n (

T)

0.0

0.5

1.0

1.5

2.0

2.5

FeCo

REPM

Steels

FeNi

Alnico

Definition of Magnetic Materials

All materials have magnetism; Ferromagnetic materials are useful

• Soft magnets—easy domain wall movement with minimal energy—tight loop

• Hard/Permanent magnets—more energy required to magnetize and demagnetize but

maintain their magnetic alignment

Magnetic Materials are High Performance Alloys

Br

Hcmi

BS Mag Saturation, strength

External Field Strength, H

To

tal F

ield

,

B

Hc Coercivity,

resistance to de-mag

mi Permeability,

ease of magnetization

• Chemistry, Grain Size, Domain Size,

Crystallographic Orientation are key

features

• Properties can vary with product form

• Handling can affect properties



Magnetic Materials in Electrical Machines

Hard Magnets Provide Constant Magnetic Field

• Rare Earth Permanent Magnets (REPM) are the highest coercivity magnets, so have

the highest resistance to demagnetizing fields

• NdFe class has highest magnetic strength

• SmCo class has highest temperature resistance

• FeCo (Hiperco) soft magnetic alloys have the highest saturation strength and are

used in applications where mass is critical

• Other soft magnetic alloys can yield lower losses, especially at high frequency

• Hard magnets provide constant

magnetic field which can greatly

improve motor specific power

• Soft magnets provide magnetic field

shaping



Soft Magnetic Materials in Electrical Components

• Soft magnetic materials are the building block of chokes, filter inductors,

transformers and EMI shields

Soft Magnets Enable Power Conversion/Conditioning

• Thin laminations reduce eddy current losses

• Reduced coercivity decreases hysteresis losses

• Desirable permeability is component dependent;

e.g. low permeability for inductors, high

permeability for transformers

Core Flux

Leakage

Flux

• Wide band-gap semi-conductors enable

higher power and higher frequency

applications

• Soft magnetic materials must be chosen to

compliment the particular power component

application

Transformer

Most devices/components benefit from higher

operating frequencies, which results in higher power

densities (higher output and lower volume)



Nanocomposite Alloys Fill Void in Electronics Design

Nanocomposite alloys have higher saturation & temperature capability than

amorphous alloys and tailorable permeability

New Alloy Class with Good Design Characteristics

Classes of

Materials

Relevant

Frequency

Range

Max

Saturation

(T)

DC

Permeability

Resistivity

(Ω-cm)

Useful

Temperature

Range (°C)

Bulk Alloys DC – 1 kHz 2.5 102 - 105 0.5 x 10-6 <500

Powder Core 10 – 500 kHz 1.6 20 – 500 1 <200

Ferrites 10 kHz – 100

MHz

0.5 100 – 5000 102 - 108 <300

Amorphous Alloys DC – 100 kHz 1.5 105 130 x 10-6 <200

Nanocomposites DC – 100 kHz 1.9 100 - 105 110 x 10-6 <400

Saturation—2nd

only to bulk

alloys

Frequency—up

to 100 kHz

Resistivity

higher than

bulk alloy

Temperature—

2nd only to bulk

alloys

Tunable Permeability—controlled

by strain or field annealing



Amorphous and Nanocomposite Alloy Production

Substantial Soft Magnetic Alloy Development Potential

• Melt Spinning Fe-base, Co-base or Fe-Ni alloy with “glass former” creates amorphous

alloys that are naturally thin with lower losses at high frequency

• Selective nanocrystallization of magnetic

phases makes a nanocomposite that is still

naturally thin with low losses at high

frequency as well as

• Better temperature stability

• Crystallization in magnetic or strain field

allows selective permeability



Nanocomposite Alloy Development

Substantial Soft Magnetic Alloy Development Potential

Finemet is a first generation Fe-based nanocomposite which is commercially available

Next generation Fe-based nanocomposite will offer

• Improved electrical stability such as a more square B-H curve, which allows constant

inductance over a wider field

• Stable permeability also improves performance over a wider range

of DC bias conditions

• Higher temperature stability

Co-based nanocomposite alloys have better

mechanical properties

• Alloying and processing studies are striving

to maximize magnetic properties

Fe-Ni alloys are being explored to potentially produce

lower cost alloys

Hc

BS

H

B



Nanocomposite Alloys Transitioning to Components

Transitioning Alloys from Lab-scale to Components

• NASA Glenn operating a medium scale spin-

caster producing 3 kg of ribbon up to 50 cm wide

• Producing Fe- and Co-based alloys in quantities

and sizes sufficient for relevant-sized

components

• Completed 50-kg delivery of Co-based alloy

ribbon for DOE inductor program

Casting Co alloy



Ready to Design, Build, and Test for Specific Applications

Substantial Component Development Potential

Example Nanocomposite has lower losses

than a powder core in comparable application

Working practical fabrication

issues associated with

manufacturer-ability

Designed a prototype to replace

a ferrite core inductor in a 20

kHz NASA controller—bench

testing shows 40 times lower

losses per inductor

COTS

powder core:

50 Hz

100 Hz

200 Hz



Ongoing Partnerships

Transitioning Alloys from Lab-scale to Components

• Advanced Inductor for DOE Motor Program- Partners included NETL (DOE), Eaton, and Carnegie

Mellon

- Started in Sept 2017

- Developing a 3 MW-motor for gas industry applications

- Delivered 50 kg of a custom alloy.

- Producing test data to support inductor design.

• Ohio Federal Research Network- Ohio partners include Case Western and Youngstown

State

- Developing high-temperature magnetic materials

• Colorado School of Mines (CSM)- NSF-funded 1st principle modeling of

magnetic materials

- Hosted a CSM summer student at GRC

• Interagency Advanced Power Group

(IAPG)- Coordinates research activities across

multiple federal agencies

- Established an “Electrical Materials”

panel in 2016 under the Electrical

Systems Working Group

• Fort Wayne Metals- Establishing industrial production capabilities for

commercialization of these new materials

• SunShot National Laboratory Multiyear

Partnership (SuNLaMP)- Partners included NETL (DOE), NC State, and Carnegie

Mellon

- Started in March 2016

- The SunShot program is targeting solar PV cost reduction and

new technology development, both of which are required to

achieve dramatically increased penetration of solar energy

by the year 2020.

• NASA EPSCoR- University of Alabama

- Atomistic and micro-magnetic models to

guide alloy development efforts



Take Away Points

• Materials Development is important for continued component

improvements

• There is significant development potential remaining in soft

magnetic materials which correspond to the significant

development potential remaining in power electronics in general

• Component designers should not limit themselves to “off the

shelf” passive component designs when planning for future power

electronic components or systems

Electrified Propulsion Requires Increase in Performance



Magnetic Materials Enabling Electrified Aircraft Propulsion

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