Magnetizing Considerations for Motor Design

Magne&zingConsidera&ons
forMotorDesign
DavidMiller
Magne&cs2016
January21-22,2016
Jacksonville,FL
Overview
•  TheMagne&zingProcess
•  SpecifyingAssembliesforMagne&za&on
•  Magne&zingateachMotorDevelopmentStage
•  TechnicalConsidera&ons
•  SupplyChainWorldview
2
TheMagne&zingProcess
•  Permanent magnetic
material is exposed to
a high intensity
magnetic field to align
magnetic domains and
create a ‘permanent
magnet.’
•  Magnetization
closer to the end of
the assembly
process is usually
more desirable.
3
TheMagne&zingProcess
Produc&onmagne&zingisusuallyundertakenusinga
capaci&vedischargepowersupply(“magne&zer”)andasetof
configuredsolenoidsarrangedinmul&plepoles(“fixture”).
4
SpecifyingAssembliesforMagne&za&on
Fixtures can be designed for many types of pole configurations
The desired magnetization can be imparted to nearly any motor design.
Axial
Diametrical
Multi-pole axial
Outer-diameter Halbach
Surface magnetization
Uni-polar radial
Inner-diameter Halbach
5
SpecifyingAssembliesforMagne&za&on
Magnetizing fixtures are specified by defining the magnet or magnetic
assembly along with its desired magnetization
•  Magnet material
–  2nd Quadrant BH & Saturation Characteristics
•  Can be determined from samples
• 
• 
• 
• 
• 
Magnet material orientation
Magnetized orientation
Number of poles
Magnet geometry
Assembly geometry when magnetizing an assembly
–  Including Soft Magnetic Components
•  Occasionally Soft Magnetic BH Characteristics are Required
•  Cycle rate (water or air cooling for faster rates)
•  Magnet calibration (tuning to a specific strength if desired)
6
Magne&zingatEachMotorDevelopmentStage
Design
InFiniteElementAnalysis(FEA)toolsorina
computa&onaltoolsuchasSPEED,
magne&za&onisassignedtohardmagne&c
regionsinthemodel.
•  OYencatalog,orpublished,BH
characteris&csareused.
•  Orienta&onofthemagnetisauserinput,
andthisisoYenassumed.
PayA\en&onto:
•  MaterialProper&escanvaryfromthepublisheddata
•  AssumedOrienta&onmaynotbeachievable
7
Magne&zingatEachMotorDevelopmentStage
EarlyPrototype
InearlyprototypesmagnetsareoYen
magne&zedindividuallyinsolenoidsand
manuallyplacedintoasubassembly.
PayA\en&onto:
•  Satura&ngfieldsareeasilyachievedinasolenoid;
duplica&onwithin-situmagne&za&onmaynotbe
perfect
•  In-situMagne&zingfixturesmaynothaveperfect
orienta&on;off-axismagne&zingfieldswillrequire
evenhigherfieldmagnitude
8
Magne&zingatEachMotorDevelopmentStage
Pre-Produc5onPrototype
Atthisstageaprototypemagne&zingfixture
shouldcloselyemulateaproduc&on-intent
fixture.
•  Ensuresthattheproduc&onmagne&zing
situa&oniswellunderstood.
Costsavingstrategies
•  Reduced-pole-countprototypes
o 
Forexample,use2-polesand5
magne&zingpulsesfora10-polerotor
•  UpgradeablePrototype(NextSlide)
9
Magne&zingatEachMotorDevelopmentStage
Pre-Produc5onPrototype(UpgradeablePrototype)
Theinvestmentinaproduc&on-intentmagne&zingfixturecanbekepttoa
minimumandleveragedatthe&meofcommitmenttoproduc&on.
10
Magne&zingatEachMotorDevelopmentStage
PPAP&Produc5on
Produc&onfixtureswilltypically
magne&zetothesameleveland
orienta&onasprototypes.Major
addi&onsfromtheprototypestage
include:
•  Cooling(forquickestcycle&mes)
•  Safetyenclosuresandshielding
•  Parthandlinghardware
•  Temperaturemonitoring
•  Partmeasurement(verifica&on)
11
Magne&zingatEachMotorDevelopmentStage
PartMeasurementinProduc5on
Gaussand/orfluxmeasurementsmaybe
madeandrecordedforeachpartthatis
processed.Faultacknowledgmenton
systemshelpsensurethatfaultypartsare
notpassedintodownstreamproduc&on.
Partmeasurementdatacanbehighly
correlatedwithmotorperformance.
Totalfluxmeasurementsinpar&cularhave
beenshowntobedirectlypropor&onaland
highlycorrelatedwithamotor’sback-emf.
12
TechnicalConsidera&ons-Orienta&on
ResultantMagne&za&onVectors
AnisotropicOrienta5on(mostcommon)
AnisotropicMaterialhasapreferred
magne&za&onorienta&onthatis
determinedduringthematerial
fabrica&onprocess.
Orienta&onisfixedatthemagnet
materialvendorandisnotinfluencedby
themagne&zingfixture.
RadiallyAnisotropic
Magne&zingField(fromasolenoid)
13
TechnicalConsidera&ons-Orienta&on
ResultantMagne&za&onVectors
IsotropicOrienta5on(usuallyBondedNeo)
Isotropicmaterialhasnopreferred
magne&za&onorienta&on.
Orienta&onisimpartedbythemagne&zing
fixture.
Isotropic
Magne&zingField(fromasolenoid)
14
TechnicalConsidera&ons-Orienta&on
IPMRotors
Magne&zingFluxLines
Anisotropic
Orienta&on
Somemagne&zingfieldregionsarenot
alignedwiththematerialorienta&on.
Be\ersuitedforfavorablyaligned
magne&zingfields.
15
TechnicalConsidera&ons-Satura&on
HorizontalAxis:Energy,Current,Voltage,AppliedField,etc.
Ver&calAxis:Flux,ResidualField,Back-emf,etc.
16
TechnicalConsidera&ons-Satura&on
MQ3mayrequiremoremagne&zingfieldthansinteredneoat
similarenergyproducts.
Sm2Co17canrequireupto50kOetomagne&ze
17
TechnicalConsidera&ons-Satura&on
Assembliesthatarechallengingtosaturate
SomeIPMRotors
LargeValuesfor(Diameter/Pole-Pitch)
10PolesonØ2.9mm
18
TechnicalConsidera&ons-Satura&on
RecentTrendin“SpokeRotors”
MeanstoAchievehighpowerdensityusing
rela&velycheaperferritemagnetmaterial
Magne&zingCoilsmustbe
locatedoutsidethisperiphery
Challengingto
producesufficient
magne&zingfield
inthisregionof
themagnet
Tipsfor“SpokeRotors”
•  KeepmagnetsasclosetotheODasisfeasible
•  Lowerpolecountmakesmagne&za&onlesschallenging
19
TechnicalConsidera&ons-Satura&on
“Saturation” v Magnetized
20
TechnicalConsidera&ons-Satura&on
ChallengingCase
LargeValuesfor(Diameter/Pole-Pitch)
10PolesonØ2.9mm
21
TechnicalConsidera&ons-Satura&on
10PolesonØ2.9mm
PossibleMagne&zingSolu&on
22
TechnicalConsidera&ons-Satura&on
Mostcommercialfixturesoperatebelow8kA/mm2
Magne&za&onat10kA/mm2 Magne&za&onat20kA/mm2
Peakradialfield
onmagnetsurface
Isapproximately
27kilo-Oersteds
Peakradialfield
onmagnetsurface
Isapproximately
47kilo-Oersteds
FieldMagnitudeinkilo-Oersteds
Magne&za&onat30kA/mm2
Peakradialfield
onmagnetsurface
Isapproximately
65kilo-Oersteds
23
TechnicalConsidera&ons–EndTurns
•  InsufficientSpaceforend-turns
Acuprotorwithinsufficientroomforendturnswouldbea
challengewithaconven&onalwire-woundmagne&zingfixture.
24
TechnicalConsidera&ons–DefiningSkewAngles
SkewAnglesaretypicallyspecifiedasthe
‘clockface’anglesweptasviewedwiththeaxis
perpendiculartotheviewingplane.
Typicallyahalforfullslotpitchofthe
armatureorstatorwindingsforthegreatest
reduc&onincogging.(Mayrequire
op&miza&onfromthisidealmeasure)
Ø  Requiresadifferentmagne&zingfixturefor
mul&plelengthshavingthesameskew
angle
25
TechnicalConsidera&ons–ThermalStability
•  Magne&cknockdownmaybeusedtoreplaceathermal
stabiliza&onprocessduringmanufacturing
Thermalstabiliza&on
Fieldstabiliza&on
Timeconsuming;
addi&onalprocess
Quick;PartofMagne&zing
Process
26
TechnicalConsidera&ons–In-SituChallenges
In-Situvpre-assemblymagne&za&on
•  IPMRotors
•  MagnetMaterialisfarfromtherotorsurface
–  LargeValuesfor(Diameter/Pole-Pitch)
•  MagnetPlatesSpacedClosely
–  Maybechallengingtoproperlymagne&zeedgesofplate
27
Difficulttoa\ainFluxWaveshape:Fixtureslotshaping
Iron
Magnet
Air
Copper
Conductor
Flatslotmagne&zingfixtureSystem
Motorphaseback-emfformagnetorienta&onachieved
usingtheflatandcurvedslotmagne&zingfixtures
Iron
Magnet
Air
Copper
Conductor
Curvedslotmagne&zing
fixtureSystem
Coggingtorqueofthemotorformagnetmagne&zedusingtheflat
andcurvedslotmagne&zingfixtures
28
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor-Benchmarking
•  After Market Automotive HVAC Blower Motor
29
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
BenchmarkedandRedesignedMotorComparison
Parameter
Benchmark
PMDC Motor
4-Pole PMBL DC Motor with
Bonded Neo Magnets
Type of Magnet
Ferrite
Compression Molded MQPB2+
Total motor weight (gm)
697.51
467.5
Length of the motor (mm)
37.20
25.00
Overall diameter(mm)
81.80
64.00
Total copper weight (gm)
81.94
77.90
Total magnet weight (gm)
257.20
32.60
Length of Air gap (mm)
1.25
1.25
Current at 400 mN-m (A)
16.00
15.90
Current at 700 mN-m (A)
27.00
28.00
Efficiency at 400 mN-m (%)
66.84
73.00
Efficiency at 700 mN-m (%)
51.39
54.00
30
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor–DimensionComparisonof
BenchmarkedandRedesignMotors
Benchmarked Motor
Redesigned
Motor
Skewed Magnet of
the Redesigned
Motor
31
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
Magne&cFixtureDesign1(Outer)
Conductor
Iron
Circuit parameters
R: 6E-03 Ω
L: 2.19E-6 H
C: 4E-03 F
V: 1213 V
Peak Current: 43 kA
Time to peak: 136 us
Wire Conductor size: AWG13
Magnet
Field is measured
at mid of magnet
32
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
Magne&cFixtureDesign2(Inner&Outer)
Circuit parameters
R: 12E-03 Ω
L: 4.5E-6 H
C: 2E-03 F
V: 1315 V
Peak Current: 23 kA
Time to peak: 138 us
Wire Conductor size: AWG13
Field is
measured
at mid of
magnet
Magnetizing Fixture with Conductors on
Outside and Inside of magnet surface
33
CourtesyofMagnequench
DesignStudy-HVACBlowerMotor–AppliedField
attheMidoftheMagnet
34
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
MeasurementofMidAirgapFluxDensity
Application model’s B-field is
measured at center of airgap (r = 21.625mm)
35
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
MidAirgapFluxDensity
Type of Magnetization
Outer
Inner & Outer
Ideal Radial
Integral of B-field Modulus (T)
108.47
114.91
118.45
Change between Outer vs. Outer/Inner
Magnetization (%)
--
5.94
Change between Outer/Inner vs. Ideal Radial
Magnetization (%)
-2.99
-36
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
EffectofMagne&za&ononCoggingTorque
Cogging Torque for Ideal Radial Magnetization with Skew of 30º
Magne5za5on
Outer
(Skew=0)
Inner&Outer IdealRadial
(Skew=0)
(Skew=0)
IdealRadial
(Skew=30)
Tpk-pk(mN-m)
29.45
51.86
0.67
51.46
37
CourtesyofMagnequench
DesignStudy–HVACBlowerMotor
PerformanceComparison
Torque-Efficiency and Torque-Power
Characteristics for the Benchmarked
and Redesigned Motors
Torque-Speed and Torque-Current
Characteristics for the Benchmarked
and Redesigned Motors
38
CourtesyofMagnequench
SupplyChainWorldview
Classic‘Silo-Style’Development
Supplier
Deliverto
Specifica&on
Component
Mfg
OEM
Consumer
Preference
Collabora5veDevelopment
Supplier
Component
Mfg
Deliverto
Specifica&on
OEM
•  Fostercloserela&onshipsbetween
supplychainpartnersacross
mul&plefunc&ons
•  ShareKnow-Howascri&cal
decisionsaremade
Ø  Resultsingreatervaluefromthe
supplychain
39
ThankYou!
Ques&ons?