APPLICATIONS OF HIGH ENERGY DENSITY PERMANENT MAGNETS W. Kappel R&D Institute for Electrical Engineering ICPE-Advanced Research Splaiul Unirii 313, sector 3, Bucharest, Romania European School on Magnetism,September 8-18 th , Cluj Napoca
Magnetic Materials hard/soft European School on Magnetism,September 8-18 th , Cluj Napoca
How works a PM? 1 1 = = − = − W B H V B H V W m m m m m m mext min t 2 2 final ∫ ∫ ∫ = = = W BHdv W BHdv Fdl mext mext ∞− ∞− m m initial European School on Magnetism,September 8-18 th , Cluj Napoca
The highest loading energy of a PM 1 = max( W ) ( B H ) V max m min t 2 Example: for NdFeB-PM with = ( W ) / mass 50 / J kg max min t = 4 w 10 J kg / car battery 12 Comparison : V / 60 Ah el European School on Magnetism,September 8-18 th , Cluj Napoca
Permanent magnets European School on Magnetism,September 8-18 th , Cluj Napoca
High energy permanent magnets European School on Magnetism,September 8-18 th , Cluj Napoca
Working at high temperature European School on Magnetism,September 8-18 th , Cluj Napoca
Working temperature Properties of some Re-TM permanent magnets Permanent magnet (BH) max B r jHc Manufac-turing Highest working Producer (kJ/m 3 ) (T) (kA/m) method Temp. ( ° C) NdFeB 390 1.40 875 sintering 80 Shin Etsu NdFeB 263 1.17 2387 sintering 180 Shin Etsu NdFeB 190 1.00 3260 sintering 210 Vacuumschmelze NdFeB/MQI 64 0.61 1200 bonded 125 General Motors NdFeB-MQII 112 0,80 1600 densified 200 GM NdFeB-MQIII 360 1.37 1120 hot worked 150 GM NdFeB 240 1.11 2800 sintering 220 MFS[ SmGdCo 5 80 0.64 2400 sintering 250 Ugimag SmCos 170 0.93 2000 sintering 250 MFS Sm 2 Co 17 215 1.06 2000 sintering 350 MFS European School on Magnetism,September 8-18 th , Cluj Napoca
Working at high temperatures = + α − ( BH ) ( BH ) [1 ( T T )] Linear approximation: max max o BH o α = α + α = ( BH ) ( BH ) Where: Two PM at T e : BH I H max1 max 2 − 1 k ∆ = T 12 at , k 12 = (BH) max1o /(BH) max2o e k α − α 12 BH 1 BH 2 α = − = 3 0.04% / K Exemple Alnico IUNDK8AA, ( BH ) 100 kJ m / , BH 1 max1 α = − = 3 0.70% / K ( BH ) 300 kJ m / NdFeB , max2 BH 2 ∆ = 100 o T C => e European School on Magnetism,September 8-18th, Cluj Napoca
Working at high temperatures µ >> H I Reversible losses if: cI o r − 1 k = µ µ = ∆ = k I / H T max : H I T , We define from which: ro o cIo cI o r max k α − α I H − = → ⇒ ∆ → − α k 0 T 1/ 1 (1/ 0.005 K 200 K max H → ⇒ ∆ → k 1 T 0 max ⇒ ∆ = T 200 K ) max > ⇒ ∆ ∆ < k k T / T 1 If That means 1 2 max1 max 2 For two PM having the same coercivity, the highest working temperature has the PM with the lower remanence (sintered /bonded) European School on Magnetism,September 8-18th, Cluj Napoca
ρ ( BH ) / Energy mass = / PM worldwide max = ρ Energy / cos t ( BH ) / :cos / t kg max + - PRCo; * - NdFeB; # - Ferrite; o - Alnico European School on Magnetism,September 8-18 th , Cluj Napoca
PM worldwide European School on Magnetism,September 8-18 th , Cluj Napoca
Load line + − − B H M (1 N ) 1 N → = ⎯⎯⎯ H 0 →− = − m 0 S 0 µ − H H NM N 0 m 0 dl ∫ ∫ + = + Φ = H l Hdl H l 0, m m m m µ A − circuit m dl 1 Λ ≡ ∫ permeance = Λ c µ A − c circuit m k A k A = 1 g = Λ Λ = λ S / 2 m / c m l l g m European School on Magnetism,September 8-18 th , Cluj Napoca
Recoil line/minor histerezis loop N – demagnetization factor of the PM European School on Magnetism,September 8-18 th , Cluj Napoca
Ideal Permanent magnet µ = = µ + → 1 B ( H M ) m 0 m r rec (main demagnetisation curve) B r An ideal permanent magnet : no irreversibil losses until Hd= intrinsec coercivity! = µ 2 ( BH ) ( B ) /( 4 ) max r 0 European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
λ = λ + λ G N S European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
European School on Magnetism,September 8-18 th , Cluj Napoca
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. → T T If , A1 is not restored because the induction (magnetisation) − 40 20 even become smaller at higher temperature European School on Magnetism,September 8-18 th , Cluj Napoca
PM Applications European School on Magnetism,September 8-18 th , Cluj Napoca
Applications Different types of magnetic materials Type of SOFT MAGNETIC MATERIALS HARD MM Magn. Transport magn.mate memory Magnetostriction properties rial material Field of E-tron. Sensors EMC E-techn. E-techn. E-tron. IT Actua- Sensors Sensors appl. tors TM- FeSi, Nano Compo FeSi, AlNi- FeCoZr Permalloy alloys Nano FeNi sites FeNi, Co &am M+pol FeCo, FeNi ymers Fe RE-TM NdFeB NdFeB TbFeCo RE-Fe 2 SmCo SmCo Ferrit. Soft Soft Soft Magn. Hexa- Hexa- Fe 2 O 3, LaREMnO 3 CrO 2 Mangani ferrites ferrites ferrites liquids ferrites ferrites tes CoCrTM- RE/CoCr systems RE-TM Alloys, Metall &oxid oxids Thin films Ni Multi- M-mu. Mu.- Metall &oxid PtCo RE-TM,TM-TM’ TM/nonmag/ layers layers lay.+in systems TM,TM/insu sulater l./ TM Nano Am.(Co) Fe 2 O 3 Comp.with exch. Magn. interaction wires TM=3d-transition metal,RE=rare earth,M=metal European School on Magnetism,September 8-18 th , Cluj Napoca
Magnetizing & shapes European School on Magnetism,September 8-18 th , Cluj Napoca
Applications of high energy PM Generating mag. fields European School on Magnetism,September 8-18 th , Cluj Napoca
Cladding magnets/effects European School on Magnetism,September 8-18 th , Cluj Napoca
PM Applications π sin( 2 / N ) = B B ln( R 2 R / ) Generating mag. fields r π 1 2 / N Hallbach (magic) cylinder H. A. Leupold,Static Applications, Re-Fe PM, J.M. Coey, Clarondon Press, 1996 [ ] ∈ − 2 ,2 B B B int M Coey, D. White, the Ind. Phys. Sept.1998 European School on Magnetism,September 8-18 th , Cluj Napoca
Hallbach Cylinder Inside notch ← x ⎯→ 2 x x’ x x’ ⎡ − ⎤ x = 6 B ( x ) B ( 0 ) 1 P ( geometry )( ) ⎢ ⎥ inside inside R ⎣ ⎦ Outside notch 1 European School on Magnetism,September 8-18 th , Cluj Napoca
PM Applications Magnetic Field (for a sphere, but for a cylinder, ' = ' H M / 2 ! ) int Applications : PM powder pressing tools for anisotropic PM, built from ferromagnetic steels European School on Magnetism,September 8-18 th , Cluj Napoca
dB/dT=0 with thermocompensating alloys π − = 2 2 ( R r ) S = + TK B S BS B S m m TK TK dB dB dB = ⋅ + m TK S S S m TK dT dT dT dB/dT = 0 ( ) ( ( ) ) = + α − B T B 1 T T m mo m o dB ( ) = α TK S S B T TK m m o m dT α S B = m mo m S Thermoflux TK dB dT TK European School on Magnetism,September 8-18 th , Cluj Napoca
dB/dT=0 Kw-meter 1 dH = F B 2 V x m 1 1 2 dx 2 / ρ M B break Al ρ = ρ + α − ( 0 T ( T )(1 ( T T )) Al Al 0 Al T , 0 α = − 0 0,4%/ C Al T , European School on Magnetism,September 8-18 th , Cluj Napoca
Field Generator ← → L European School on Magnetism,September 8-18 th , Cluj Napoca
Holding magnets European School on Magnetism,September 8-18 th , Cluj Napoca
Holding magnets R = Λ 1/ 2 B = A µ F L 2 0 European School on Magnetism,September 8-18 th , Cluj Napoca
Φ − Θ -Demagnetisation curve optimal optimal R R Φ = = + = Φ + Φ B S B S B S g s ≡ = R R m m m g g s s g s int ext + Φ R R Θ = = = Θ = Θ = H l H l R g s m m m m m g g g s Θ l l 1 α = = = = = m m m tg R m Φ λ Λ S S B / H m m m m m m m European School on Magnetism,September 8-18 th , Cluj Napoca
1 dH = 2 F B V Bearings x m 1 1 2 dx European School on Magnetism,September 8-18 th , Cluj Napoca
Axial coupling = M f ( BH ) pV max geom mag mag European School on Magnetism,September 8-18 th , Cluj Napoca
Multiple Radial Coupling − 2 3 n 10 Nm T ~ 10 European School on Magnetism,September 8-18 th , Cluj Napoca
Radial coupling 2 2 M B R L max L European School on Magnetism,September 8-18 th , Cluj Napoca
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