Kappel APPLICATIONS OF HIGH ENERGY DENSITY …magnetism.eu/esm/2007-cluj/slides/kappel-slides.pdfAPPLICATIONS OF HIGH ENERGY DENSITY PERMANENT MAGNETS European School on Magnetism,September

APPLICATIONS OF HIGH ENERGY DENSITY PERMANENT MAGNETS

European School on Magnetism,September 8-18th, Cluj Napoca

W. KappelR&D Institute for Electrical Engineering ICPE-Advanced Research

Splaiul Unirii 313, sector 3, Bucharest, Romania

Magnetic Materials


hard/soft

How works a PM?


min1 12 2

mextm

m m m m m m mextt

W BHdv

W B H V B H V W

∞−

=

= = − = −

∫final

mextm initial

W BHdv Fdl∞−

= =∫ ∫

The highest loading energy of a PM


maxmin1max( ) ( )2 mtW B H V=

min( ) / 50 /tW mass J kg=

Example: for NdFeB-PM with

max

:Comparison car battery 12 / 60V Ah410 /elw J kg=

Permanent magnets


High energy permanent magnets


Working at high temperature


Working temperature


MFS 350 sintering 2000 1.06 215 Sm2Co17

MFS250sintering20000.93170SmCos

Ugimag250sintering24000.6480SmGdCo5

MFS[ 220 sintering 2800 1.11 240 NdFeB

GM150hot worked11201.37360NdFeB-MQIII

GM200densified16000,80112NdFeB-MQII

General Motors125bonded12000.6164NdFeB/MQI

Vacuumschmelze210 sintering 3260 1.00 190 NdFeB

Shin Etsu180sintering23871.17263NdFeB

Shin Etsu80 sintering 875 1.40 390 NdFeB

ProducerHighest working Temp. (°C)

Manufac-turing method

jHc(kA/m)

Br(T)

(BH)max(kJ/m3)

Permanent magnet

Properties of some Re-TM permanent magnets

Working at high temperatures

Linear approximation: max max( ) ( ) [1 ( )]o BH oBH BH T Tα= + −

Where: BH I Hα α α= + Two PM at Te: max1 max 2( ) ( )BH BH=

at 12

12 1 2

1e

BH BH

kTk α α

−∆ =

−, k12 = (BH)max1o /(BH)max2o

Exemple Alnico IUNDK8AA, 3max1( ) 100 /BH kJ m= , 1 0.04% /BH Kα = −

NdFeB 3max 2( ) 300 /BH kJ m= , 2 0.70% /BH Kα = −

=> 100oeT C∆ =


Working at high temperatures

cI o rH Iµ >>Reversible losses if:

We define max : cI o rT H Iµ = max1

I H

kTkα α

−∆ =

−from which: /ro o cIok I Hµ=,

max

max

0 1/1 0

Hk Tk T

α→ ⇒ ∆ → −→ ⇒ ∆ →

If 1 2 max1 max 2/ 1k k T T> ⇒ ∆ ∆ < That means

For two PM having the same coercivity, the highest working temperature has the PM with the lower remanence (sintered /bonded)


max 200 )T K⇒∆ =

1(1/ 0.005 200K K− =

PM worldwide


+ - PRCo; * - NdFeB; # - Ferrite; o - Alnico

max( ) /BH ρ/Energy mass =

max/ cos ( ) / : cos /Energy t BH t kgρ=

PM worldwide


Load line


0,m m m mcircuit m

dlH l Hdl H lAµ−

+ = +Φ =∫ ∫1

ccircuit m

dlAµ−

=Λ∫ c permeanceΛ ≡

1 2/ /g mc m

g m

k A k ASl l

λ= = Λ Λ =

0 00

0 0

(1 ) 1Hm

m

B H M N N SH H NM Nµ

→+ − −= ⎯⎯⎯→− = −

−

Recoil line/minor histerezis loop


N – demagnetization factor of the PM

Ideal Permanent magnet


(main demagnetisation curve)1=recµ → )(0 rmm MHB += µ

An ideal permanent magnet :

no irreversibil losses until Hd= intrinseccoercivity!

rB

)4/()()( 02

max µrBBH =





SNG λλλ +=






Ferrites at low temperatures


If T→ - 40C, A→A2 on the load line

If Hd is applied, A→B at 20C resp. B1 at -40C

If Hd = 0, than B→A1resp B1→A3 along the corresponding recoil lines.

If , A1 is not restored because the induction (magnetisation) even become smaller at higher temperature

40 20T T−

→

PM Applications


Applications


Different types of magnetic materialsType of magn.material

SOFT MAGNETIC MATERIALS HARD MM Magn. memory

Magnetostriction material

Transport properties

Field of appl.

E-tron. Sensors EMC E-techn. E-techn. E-tron. IT Actua- tors

Sensors Sensors

TM-alloys

FeSi, Nano &am FeNi

Nano FeNi

Composites M+polymers

FeSi, FeNi, FeCo, Fe

AlNi- Co

FeCoZr Permalloy

RE-TM NdFeB SmCo

NdFeB SmCo

TbFeCo RE-Fe2

Ferrit. Manganites

Soft ferrites

Soft ferrites

Soft ferrites

Magn. liquids

Hexa- ferrites

Hexa- ferrites

Fe2O3,

CrO2

LaREMnO3

Thin

fil

ms

Allo

ys,

oxid

s

Met

all

&ox

id

syst

ems

CoC

rTM

-R

E/Co

Cr

RE-

TM

Ni

Multi- layers

M-mu. layers

Mu.-lay.+insulater

Metall &oxid systems

PtCo RE-TM,TM-TM’ TM/nonmag/ TM,TM/insul./ TM

Nano Am.(Co) Fe2O3 Comp.with exch. interaction

Magn. wires

TM=3d-transition metal,RE=rare earth,M=metal

Magnetizing & shapes


Applications of high energy PMGenerating mag. fields


Cladding magnets/effects


PM ApplicationsGenerating mag. fields


Hallbach (magic) cylinder

)/ln(/2

)/2sin(12 RR

NNBB r π

π=

M Coey, D. White, the Ind. Phys. Sept.1998

H. A. Leupold,Static Applications, Re-Fe PM, J.M. Coey, Clarondon Press, 1996

[ ]int 2 , 2B B B∈ −

Hallbach Cylinder


Inside notch

Outside notch⎥⎦

⎤⎢⎣

⎡−= 6

1

))((1)0()(RxgeometryPBxB insideinside

⎯→← x2

x

x

x’

x’

PM ApplicationsMagnetic Field


Applications: PM powder pressing tools for anisotropic PM, built

from ferromagnetic steels

(for a sphere, but for a cylinder,

!2/''int MH = )

dB/dT=0 with thermocompensating alloys


TKTKmm SBBSSB +=

dTdB

SSdTdB

dTdB

S TKTK

mm +⋅=

( ) ( )( )ommom TTBTB −+= α1dB/dT = 0

( ) mommTK

TK TBSdT

dBS α=

ThermofluxdTdB

BSS

TK

mmomTK

α=

TKS2 2( )R rπ − =

dB/dT=0


Kw-meter

2 /break AlM B ρ

0 , 0( 0 ( )(1 ( ))Al Al Al TT T T Tρ ρ α= + −

0, 0, 4% /Al T Cα = −

21 1

12x m

dHF B Vdx

=

Field Generator


L← →

Holding magnets


Holding magnets


2

02LBF Aµ

=

1 /R = Λ

-Demagnetisation curve


Φ −Θ

m m m g g s s g sB S B S B SΦ = = + = Φ +Φ

m m m g g g sH l H lΘ = = = Θ = Θ1

/m m m

mm m m m m m m

l ltg RS S B H

αλ

Θ= = = = =Φ Λ

intg s

extg s

R RR R

R R≡ =

+

optimal optimal

m mR= Φ

Bearings


21 1

12x m

dHF B Vdx

=

Axial coupling


max ( )geom mag magM f BH pV=

Multiple Radial Coupling


2 3~ 10 10T n Nm−

Radial coupling


2 2max LM B R L

Eddy current coupling


Tahometer

2 2max /LM R B ρ

Hysterezis couplings


~ hystM pV HdB∫

Loudspeaker


1 1( )2g m m mW B H V

γσ=

Voice coil motors


Voice coil motors


Motors with Nonferrousrotors


π

SEA/France

ICPE-1980

Watches


Magnetic separators


Actuators with PM


High speed motors


G. W. Jewell, 2002, UK

PM motors


Double Stator Motor

Stepper Motor

Flux Directions

Radial Axial

250 kW Generator


G. W. Jewell, 2002, UK

Very high temperature motors


Micromagnets


PM for e.m. watch

ICPE-1982

Magnetic orientation


Magnetotacticbacteria

Magnetic navy compass

Measuring Equipement


Magnetic recording


Medical Applications


Many thanks to


Mihai Mihaescu

Mirela Codescu

Mircea Ignat

Eros Patroi

Iulian Iordache




Documents

Kappel APPLICATIONS OF HIGH ENERGY DENSITY …magnetism.eu/esm/2007-cluj/slides/kappel-slides.pdfAPPLICATIONS OF HIGH ENERGY DENSITY PERMANENT MAGNETS European School on Magnetism,September