Coreinformation
Core(magneticring)
[pronunciation]cixin[Interpretation]Aspecialterminelectricalengineering,refersto:Inordertoincreasethemagneticinductionintensityoftheelectromagnet,amagneticmaterial(magneticcore)issetinthemagneticcircuitoftheinductorcoil.
[Source]Electricalengineering,electronics.
[Example]Thesiliconsteelsheet(magneticcore)inthepowertransformercoilisusedtoincreasethemagneticfluxdensityofthemagneticcircuitoftheelectromagneticcoil(Magneticflux)reducecopperlosstoincreaseelectromagneticinductionintensityandimprovevoltageconversionefficiency.
Introductiontomagneticcores
TheAmericanphysicistWangAnputforwardtheideaofusingmagneticmaterialstomakememoriesin1950.Forrestturnedthisideaintoreality.Inordertoachievemagneticcorestorage,Forrestneedsasubstance,whichshouldhaveaveryclearmagnetizationthreshold.HefoundanoldGermanceramicexpertinacompanythatproducesferriteconvertersfortelevisionsinNewJersey,andobtainedspecificmagneticpropertiesbymeltingironoreandoxides.
Aclearthresholdformagnetizationisthekeytodesign.Thegridandcoreofthiskindofwirearewovenonthewirenet,anditiscalledcorestorage.Itsrelatedpatentsareverycrucialtothedevelopmentofcomputers.Thissolutionisreliableandstable.Magnetizationisrelativelypermanent,sothestoreddatawillstillberetainedafterthesystem'spoweristurnedoff.Sincethemagneticfieldcanbereadatthespeedofelectrons,thismakesinteractivecomputingpossible.Furthermore,becauseitisawiregrid,anypartofthestoragearraycanbeaccessed,thatistosay,differentdatacanbestoredindifferentlocationsonthewirenetwork,andreadingabunchofbitsatthelocationcanbeaccessedimmediately.ThisiscalledRandomAccessMemory(RAM),whichisaninnovativeconceptofinteractivecomputing.ForrestertransferredthesepatentstotheMassachusettsInstituteofTechnology,andthecollegereceivesbetween15millionand20millionU.S.dollarseachyearonthesepatents.
ThefirsttoobtainthesepatentlicenseswasIBM,andIBMfinallywonacommercialcontractfortheinstallationoftheTornadoonthedefensemilitarybaseinNorthAmerica.Moreimportantly,sincethe1950s,alllargeandmedium-sizedcomputershavealsoadoptedthissystem.Magneticcorestoragehasbeenthestandardmethodofcomputermainmemoryfromthe1950sand1960suntiltheearly1970s.
Theuseofmagneticcore
Themagneticringthatweusuallyseeatoneorbothendsofthepowerlineorsignallineofelectronicequipmentisacommonmodechoke.Thecommonmodechokecoilcanformalargeimpedancetothecommonmodeinterferencecurrent,buthasnoeffectonthedifferentialmodesignal(theworkingsignalisadifferentialmodesignal),soitissimpletousewithoutconsideringthesignaldistortion.Andthecommonmodechokedoesnotneedtobegroundedandcanbedirectlyaddedtothecable.SelectionofthenumberofturnsofthemagneticringPasstheentirebundleofcablesthroughaferritemagneticringtoformacommonmodechokecoil.Ifnecessary,thecablecanalsobewoundseveralturnsonthemagneticring.Themorethenumberofturns,thebetterthesuppressioneffectonlowerfrequencyinterference,andtheweakerthesuppressioneffectonhigherfrequencynoise.Inactualengineering,thenumberofturnsofthemagneticringshouldbeadjustedaccordingtothefrequencycharacteristicsoftheinterferencecurrent.Usuallywhenthefrequencybandoftheinterferencesignalisrelativelywide,twomagneticringscanbeputonthecable,andeachmagneticringhasadifferentnumberofturns,sothathigh-frequencyinterferenceandlow-frequencyinterferencecanbesuppressedatthesametime.Fromthepointofviewofthemechanismofthecommonmodechokecoil,thelargertheimpedance,themoreobvioustheinterferencesuppressioneffect.TheimpedanceofthecommonmodechokecoilcomesfromthecommonmodeinductanceLcm=jwLcm.Itisnotdifficulttoseefromtheformulathatforacertainfrequencyofnoise,thelargertheinductanceofthemagneticring,thebetter.Buttheactualsituationisnotthecase,becausethereisaparasiticcapacitanceontheactualmagneticring,anditswayofexistenceisinparallelwiththeinductance.Whenencounteringhigh-frequencyinterferencesignals,thecapacitivereactanceofthecapacitorissmall,whichshort-circuitstheinductanceofthemagneticring,therebymakingthecommonmodechokecoiluseless.Accordingtothefrequencycharacteristicsoftheinterferencesignal,nickel-zincferriteormanganese-zincferritecanbeselected.Thehighfrequencycharacteristicsoftheformerarebetterthanthelatter.Thepermeabilityofmanganese-zincferriteisinthethousands---tensofthousands,whilethepermeabilityofnickel-zincferriteisinthehundreds---thousands.Thehigherthepermeabilityofferrite,thegreatertheimpedanceatlowfrequenciesandthesmallertheimpedanceathighfrequencies.Therefore,whensuppressinghigh-frequencyinterference,nickel-zincferriteshouldbeused;otherwise,manganese-zincferriteshouldbeused.Orputmanganese-zincandnickel-zincferriteonthesamecableatthesametime,sothattheinterferencefrequencybandthatcanbesuppressediswider.Thegreaterthedifferencebetweentheinnerandouterdiametersofthemagneticringandthegreaterthelongitudinalheight,thegreatertheimpedance,buttheinnerdiameterofthemagneticringmustbetightlywrappedaroundthecabletoavoidmagneticleakage.Theinstallationpositionofthemagneticringshouldbeascloseaspossibletothesourceofinterference,thatis,closetotheentranceandexitofthecable.
Principlesofuse
1Thelongerthemagneticring,thebetter.2Thetightertheholediameterandthecablepassingthrougharecombined,thebetter.
3Whenthelow-frequencyendisdisturbed,itisrecommendedtowindthecablewith2to3turns.Whenthehigh-frequencyendisdisturbed,itshouldnotbeturnedaround(becauseofthedistributedcapacitance).Usealongermagneticring.
Structure
①Laminatedsheet,usuallypunchedfromsiliconsteelornickelsteelsheetintoE,I,F,Oandothershapes,andstackedintoanironcore.
②Thering-shapedironcoreismadeofO-shapedsheets,oritcanbewoundfromlongandnarrowsiliconsteelandalloysteelstrips.
③C-shapedironcore,thiskindofironcorecanavoidtheshortcomingsofring-shapedironcorewindingdifficulty,andisformedbybuttingtwoC-shapedironcores.
④Thepot-shapedironcoreisastructurethathasthemagneticcoreoutsideandthecoppercoilinside,whicheliminatestheinconvenienceoftoroidalcoilsandcanreduceEMI.Thedisadvantageisthattheinternalcoilhaspoorheatdissipationandhightemperaturerise.
TDK
TDKmagneticcoreproductdescription
PC40EF20-Zmagneticcore240501
PC40EER42/42/15-ZmagneticCore16230
PC40EE16-Zmagneticcore299930
PC40EER42/42/20-Zmagneticcore13335
PC40EE19/27/5-ZmagneticCore93300
PC44PQ26/20Z-12core26880
PC40EF25-Zcore81497
PC40EI33/29/13-Zcore20848
PC44PQ32/30Z-12core10533
PC40EE55/55/21-Zcore3708
Q1CDR1.6X1.7D29core908000
PC40EER28L-Zcore23071
PC44PQ50/50Z-12core510.5
PC40EE19/16-Zcore100430
PC44PQ40/40Z-12core1182
PC40EI28-Zcore18656
IntroductiontoRMcore
Inadditiontothepotcore,Therearemanyothershapesofferritecores.ApopulartypeistheRM(RectangularModule,square)core.
Becausetheyaresquareorrectangular,theyhaveahigherPCBareautilizationefficiencythanroundmagneticcores.MultipleRMcorescanbephysicallyplacedclosertogether.AlthoughtheclosedmagneticcircuitprovidedbytheRMcoreislessthanthatofthepot-shapedcore,andthereismoremagneticleakagebetweenthecores,themagneticperformanceoftheRMcoreissimilartothatofthepot-shapedcore.
Deflection
Thedeflectioncoreisusedtocontrolthedeflectionoftheelectronbeam.Theseelectromagnetsareusuallyinstalledontheoutside,neartheneckwhereitisconnectedtothebucket,andconsistofaseriesofwindingsthataremoldedtomatchtheshapeoftheglasskinescope.Thecomponentattachedtothebucketasadeflectoriscalledadeflectioncore.
TheWar
ThecorewarwasborninBellLabsaround1959.Itistheproductofthreeyoungpeopleintheirsparetime.TheyareMaiYaolai,VysowskiandMorris.Amongthem,MorrisisthefatherofRotMorriswholatercreatedthe"MorrisWorm".Atthattime,allthreewereintheirtwenties.
Thegameplayofthecorewaristhatbothsidesofthegamewriteasetofprogramsandinputthemintothesamecomputer.Thetwosetsofprogramschaseeachotheroutinthecomputer'sstoragesystem.Becausetheyallruninthestoragecoreofthecomputer,theygotthenameofthecorewar.Thefeatureofthisgameisthataftertheprogramsofbothpartiesenterthecomputer,theplayercanonlywatchthebattlestatusdisplayedonthescreen,andcannotmakeanychangesuntiltheprogramofonepartyiscompletely"eaten"bytheprogramoftheotherparty.Therefore,thecorewarcanonlyberegardedasatoyforprogrammers.Becausetheprogramsusedingamesareverydestructive,foralongtime,peoplewhoknowhowtoplay"corewars"havestrictlyadheredtoanunwrittenrule:nottodisclosethecontentoftheseprogramstothepublic.However,in1983,thisrulewasbroken.CohenThompsongaveaspeechattheawardceremonyofanoutstandingcomputerawardwinnerthatyear.Henotonlypubliclyconfirmedtheexistenceofcomputerviruses,butalsotoldalltheaudiencehowtowritetheirownvirusprograms.Allhiscolleagueswereterrified,butthesecrethadalreadyspread.In1984,thesituationbecamemorecomplicated.Thisyear,thecolumnistoftheMonthly"ScientificAmerican"wrotethefirstarticlediscussingcorewarsintheMayissue,andaslongastwodollarsaresent,anyreadercanreceiveanoutlineonhowtowriteaprogram.Openupthebattlefieldinthehomecomputer.Inthisway,Pandora'sBoxwasopened,andmanyprogrammersunderstoodtheprincipleofthevirus,andthenbegantotrytocompilethisspecialprogramthatisconcealed,offensiveandcontagious.Nowadays,computerviruseshavebecomethebiggestplagueinthecomputerworld.Theauthorsofthecorewarneverthought:theirtoyswouldcausesuchabigtroubletotheworld.
Powertransformercoreperformancerequirementsandmaterialclassification
Inordertomeettherequirementsofswitchingpowersuppliestoimproveefficiencyandreducesizeandweight,ahighmagneticfluxdensity,highfrequencyandlowlossarerequiredTransformercore.Althoughthereiscompetitionwithhigh-performanceamorphoussoftmagneticalloys,softferritematerialsarestillthebestchoicefromtheperspectiveofperformance-priceratio;especiallyinthehigh-frequencyrangefrom100kHzto1MHz,newlow-losshigh-frequencypowerFerritematerialshavetheiruniqueadvantages.Inordertomaximizetheuseofmagneticcores,forsoftferritematerialsunderhigh-poweroperatingconditions,theyshouldhavethefollowingmostimportantmagneticpropertiesinthehigh-temperatureoperatingrange(suchas80-100°C):
1.Highsaturationmagneticfluxdensityorhighamplitudepermeability.Inthisway,thetransformercoreallowsalargemagneticfluxdeviationatthespecifiedfrequency,whichcanreducethenumberofturns;thisisalsoconducivetothehigh-frequencyapplicationofferrite,becausethecut-offfrequencyisproportionaltothesaturationmagneticfluxdensity.
2.Thereislowtotalcorelossintheoperatingfrequencyrange.Undergiventemperatureriseconditions,lowcorelosswillallowhighpassingpower.
TheadditionalrequirementsincludehighCuriepoint,highresistivity,andgoodmechanicalstrength.
Thenewlyreleasedindustrystandardof"ClassificationofSoftFerriteMaterials"(equivalenttoIEC61332:1995)dividespowerferritematerialsforhighmagneticfluxdensityapplicationsintofivecategories,asshowninTable1.Inadditiontorequirementsforamplitudepermeabilityandpowerloss,eachtypeofferritematerialalsoproposesa"performancefactor"parameter(thisparameterwillbefurtherdescribedbelow).FromPW1toPW5category,theapplicableoperatingfrequencyisgraduallyincreased.Forexample,PW1material,theapplicablefrequencyis15-100kHz,mainlyusedinflybacktransformercore;PW2material,theapplicablefrequencyis25-200kHz,mainlyusedinswitchingpowersupplyTransformercore;PW3material,applicablefrequencyis100～300kHz;PW4materialissuitableforfrequency300kHz～1MHz;PW5materialissuitableforfrequencyof1～3MHz,domesticproductionisequivalenttoPW1～PW3material,PW4materialcanonlybeproducedinsmallquantities,PW5materialhasyettobedeveloped.
Classification
Siliconsteelsheetcore
Siliconsteelsheetisanalloyformedbyaddingasmallamountofsilicon(generallylessthan4.5%)topureironTheiron-siliconalloyiscalledsiliconsteel.Thistypeofironcorehasthehighestsaturationmagneticinductionvalueof20000Gs;becauseoftheirgoodmagnetoelectricproperties,easymassproduction,lowprice,andsmallmechanicalstress,theyarewidelyusedinthepowerelectronicsindustry.Suchaspowertransformers,distributiontransformers,currenttransformersandotherironcores.Itisthematerialwiththelargestoutputandusageamongsoftmagneticmaterials.Itisalsothematerialwiththelargestamountofmagneticmaterialsusedinpowertransformers.Especiallysuitableforlowfrequencyandhighpower.Commonlyusedarecold-rolledsiliconsteelsheetDG3,cold-rollednon-orientedelectricalsteelstripDW,cold-rolledorientedelectricalsteelstripDQ,suitableformediumandsmallpowerlow-frequencytransformers,chokes,andreactorsinvariouselectronicsystemsandhouseholdappliances,Inductorcore,thiskindofalloyhasgoodtoughnessandcanbeprocessedbypunching,cutting,etc.Thecorehaslaminatedandwindingtypes.However,thelossincreasessharplyathighfrequencies,andthegeneralusefrequencydoesnotexceed400Hz.Fromanapplicationpointofview,thechoiceofsiliconsteelshouldconsidertwofactors:magnetismandcost.Forsmallmotors,reactorsandrelays,pureironorlow-siliconsteelsheetscanbeselected;forlargemotors,high-siliconhot-rolledsiliconsteelsheets,single-orientedornon-orientedcold-rolledsiliconsteelsheetscanbeselected;fortransformers,single-orientedcold-rolledsiliconsteelsheetsareoftenselectedpiece.Whenusedunderpowerfrequency,thethicknessofthecommonlyusedstripis0.2~0.35mm;whenusedunder400Hz,thethicknessof0.1mmisusuallyselected.Thethinnerthethickness,thehighertheprice.
Permalloy
Permalloyoftenreferstoiron-nickelalloyswithanickelcontentintherangeof30~90%.Itisaverywidelyusedsoftmagneticalloy.Throughappropriatetechnology,magneticpropertiescanbeeffectivelycontrolled,suchasinitialpermeabilityexceeding105,maximumpermeabilityexceeding106,coercivityaslowas2‰Oersted,rectangularcoefficientcloseto1orcloseto0,Permalloywithaface-centeredcubiccrystalstructurehasgoodplasticityandcanbeprocessedinto1μmultra-thinribbonsandvariousformsofuse.Commonlyusedalloysare1J50,1J79,1J85andsoon.Thesaturationmagneticinductionof1J50isslightlylowerthanthatofsiliconsteel,butitsmagneticpermeabilityisdozensoftimeshigherthanthatofsiliconsteel,anditsironlossisalso2to3timeslowerthanthatofsiliconsteel.Itismadeintoatransformerwithahigherfrequency(400~8000Hz),andtheno-loadcurrentissmall.Itissuitableformakingsmallhigh-frequencytransformersbelow100W.1J79hasgoodcomprehensiveperformanceandissuitableforhighfrequencyandlowvoltagetransformers,leakageprotectionswitchcores,commonmodeinductancecoresandcurrenttransformercores.Theinitialpermeabilityof1J85canreachmorethan100,000105,whichissuitableforlow-frequencyorhigh-frequencyinputandoutputtransformers,commonmodeinductorsandhigh-precisioncurrenttransformerswithweaksignals.
AmorphousandNanocrystallinealloys
(AmorphousandNanocrystallinealloys)
Siliconsteelandpermalloysoftmagneticmaterialsareallcrystallinematerials.Arrangeregularlyinthree-dimensionalspacetoformaperiodiclatticestructure,withdefectssuchascrystalgrains,grainboundaries,dislocations,interstitialatoms,andmagnetocrystallineanisotropy,whicharedetrimentaltosoftmagneticproperties.Fromtheperspectiveofmagneticphysics,theirregulararrangementofatoms,theabsenceofperiodicityandtheamorphousstructureofgrainboundariesareidealforobtainingexcellentsoftmagneticproperties.Amorphousmetalsandalloysareanewmaterialfieldthatcameoutinthe1970s.Itspreparationtechnologyiscompletelydifferentfromthetraditionalmethod,butadoptsthesuperrapidsolidificationtechnologywithacoolingrateofabout1milliondegreespersecond.Fromthemoltensteeltothefinishedstrip,itisformedatonetime,whichisbetterthanthegeneralcold-rolledmetalstripmanufacturingprocess.Manyintermediateprocessesarereduced,andthisnewprocessiscalledarevolutiontotraditionalmetallurgicalprocesses.Duetothesuper-rapidsolidification,theatomscannotbeorderedandcrystallizedwhenthealloyissolidified.Theobtainedsolidalloyhasalong-rangedisorderedstructurewithoutthecrystalgrainsandgrainboundariesofthecrystallinealloy.Itiscalledanamorphousalloyandiscalledametallurgicalmaterial.Arevolutioninlearning.Thisamorphousalloyhasmanyuniqueproperties,suchasexcellentmagneticproperties,corrosionresistance,wearresistance,highstrength,hardnessandtoughness,highelectricalresistivityandelectromechanicalcouplingproperties.Becauseofitsexcellentperformanceandsimpleprocess,ithasbecomethefocusofresearchanddevelopmentinmaterialsscienceathomeandabroadsincethe1980s.TheUnitedStates,Japan,andGermanyalreadyhavecompleteproductionscales,andalargenumberofamorphousalloyproductshavegraduallyreplacedsiliconsteel,permalloyandferriteintothemarket.
mycountryhasstartedtheresearchanddevelopmentofamorphousalloyssincethe1970s.Afterthecompletionofmajorscientificandtechnologicalresearchprojectsduringthe"SixthFive-YearPlan","SeventhFive-YearPlan"and"EighthFive-YearPlan"period,atotalofscientificresearchhasbeenobtained.Thereare134achievements,2nationalinventionawards,16patents,andnearly100alloyvarieties.TheCentralIronandSteelResearchInstitutecurrentlyhasfouramorphousalloystripproductionlinesandoneamorphousalloycomponentironcoreproductionline.Productionofvariousshapediron-based,iron-nickel-based,cobalt-basedandnanocrystallinestripsandironcores,suitableforironcorecomponentsofinverterpowersupplies,switchingpowersupplies,powertransformers,leakageprotectors,andinductors,withanannualoutputvalueofnearly2000Tenthousandyuan.Duringthe"NinthFive-YearPlan",athousand-toniron-basedamorphousproductionlineisbeingestablished,whichhasenteredtheranksoftheinternationaladvancedlevel.
Thebestindividualperformancelevelachievedbytheamorphoussoftmagneticalloyis:
Initialpermeabilityμo=14×104
Themaximumcobalt-basedamorphousPermeabilityμm=220×104
Co-basedamorphouscoercivityHc=0.001Oe
Co-basedamorphoussquarenessratioBr/Bs=0.995
Cobalt-basedamorphoussaturationmagnetization4πMs=18300Gs
Iron-basedamorphousresistivityρ=270μΩ/cm
Thetypesofcommonlyusedamorphousalloysare:iron-based,iron-nickelBase,cobalt-basedamorphousalloysandiron-basednanocrystallinealloys.Thenationalgradesandperformancecharacteristicsareshowninthetableandfigure.Fortheconvenienceofcomparison,thecorrespondingperformancesofcrystallinealloysiliconsteelsheet,permalloy1J79andferritearealsolisted.Thesetypesofmaterialshavedifferentcharacteristicsandareusedindifferentaspects.
Basiccompositionandcharacteristicsofgrades
1K101Fe-Si-Bseriesfast-quenchedsoftmagnetbasealloy
1K102Fe-Si-BCseriesfast-quenchedsoftmagnet-Basedalloy
1K103Fe-Si-B-Ni-basedfast-quenchedsoftmagnet-basedalloy
1K104Fe-Si-B-NiMo-basedfast-quenchedsoftmagnet-basedalloy
1K105Fe-Si-B-Cr(andotherelements)seriesfastquenchedsoftmagneticbasealloy
1K106highfrequencyandlowlossFe-Si-Bseriesfastquenchedsoftmagnetbasealloy
p>1K107High-frequencylow-lossFe-Nb-Cu-Si-Bseriesfast-quenchedsoftmagnet-basednanocrystallinealloy
1K201High-pulsepermeability,fast-quenchedsoftmagneticcobalt-basedalloy
p>1K202highremanenceratio,fastquenchingsoftmagneticcobalt-basedalloy
1K203highmagneticinduction,lowloss,fastquenchingsoftmagneticcobalt-basedalloy
1K204highfrequency,lowloss,fastQuenchedsoftmagneticcobalt-basedalloy
1K205highinitialpermeabilityandfast-quenchedsoftmagneticcobalt-basedalloy
1K206quenchedhigh-permeabilitysoftmagneticcobalt-basedalloy
1K501Fe-Ni-PBseriesfast-quenchedsoftmagnetnickel-basedalloy
1K502Fe-Ni-V-Si-Bseriesfast-quenchedsoftmagnetnickel-basedalloy
400Hz:Siliconsteelcoreamorphousironcore
Power(W)4545
Coreloss(W)2.41.3
Excitingpower(VA)6.11.3
Totalweight(g)295276
(1)Fe-basedamorphousalloys(Fe-basedamorphousalloys)
Itiscomposedof80%Feand20%Si,Btypemetalelements.Ithashighsaturationmagneticinductionintensity(1.54T).Comparedwiththelossofiron-basedamorphousalloyandsiliconsteel,themagneticpermeability,excitationcurrentandironlossaresuperiorinallaspectsDuetothecharacteristicsofsiliconsteelsheet,especiallylowironloss(1/3-1/5oforientedsiliconsteelsheet),itcansaveenergyby60-70%insteadofsiliconsteelasadistributiontransformer.Thethicknessoftheiron-basedamorphousalloystripisabout0.03mm,whichiswidelyusedindistributiontransformers,high-powerswitchingpowersupplies,pulsetransformers,magneticamplifiers,intermediatefrequencytransformersandinvertercores,suitableforuseatfrequenciesbelow10kHz
2,Fe-Nibased-amorphousalloy(Fe-Nibased-amorphousalloy)
Fe-Nibased-amorphousalloyiscomposedof40%Ni,40%Feand20%Composedofmetalelements,ithasmediumsaturationmagneticinductionintensity[0.8T],highinitialpermeabilityandhighmaximumpermeability,aswellashighmechanicalstrengthandexcellenttoughness.Ithaslowironlossatmediumandlowfrequencies.Theheattreatmentinairwillnotoxidize,andagoodrectangularloopcanbeobtainedaftermagneticfieldannealing.Thepriceis30-50%cheaperthan1J79.Theapplicationrangeofiron-nickel-basedamorphousalloycorrespondstothatofmedium-nickelpermalloy,butitsironlossandhighmechanicalstrengtharefarsuperiortocrystallinealloys;insteadof1J79,itiswidelyusedinleakageswitches,precisioncurrenttransformercores,andmagneticShieldandsoon.Theiron-nickel-basedamorphousalloyistheearliestdevelopedinChinaandthemostwidelyusedamongthedomesticamorphousalloys.Theannualoutputisabout200tons.Theiron-nickel-basedamorphousalloy(1K503)isinventedbythecountrywhenheattreatmentintheairdoesnotoccur.PatentsandU.S.patentrights.
3.Iron-basednanocrystallinealloy(Nanocrystallinealloy)
Iron-basednanocrystallinealloyismainlycomposedofironelement,andasmallamountofNb,Cu,Si,andBelementsareadded.Akindofamorphousmaterialformedbytherapidsolidificationprocessofthealloy.Afterheattreatment,theamorphousmaterialcanobtainmicrocrystalswithadiameterof10-20nm,whicharedispersedontheamorphousmatrixandarecalledMicrocrystalline,nanocrystallinematerialornanocrystallinematerial.Nanocrystallinematerialshaveexcellentcomprehensivemagneticproperties:highsaturationmagneticinduction(1.2T),highinitialpermeability(8×104),lowHc(0.32A/M),lowhigh-frequencylossunderhighmagneticinduction(P0.5T/20kHz=30W/kg),theresistivityis80μΩ/cm,whichishigherthanthatofPermalloy(50-60μΩ/cm).Afterlongitudinalortransversemagneticfieldtreatment,highBr(0.9)orlowBrvalue(1000Gs)canbeobtained.).Itisthematerialwiththebestcomprehensiveperformanceinthecurrentmarket;applicablefrequencyrange:50Hz-100kHz,bestfrequencyrange:20kHz-50kHz.Widelyusedinhigh-powerswitchingpowersupplies,inverterpowersupplies,magneticamplifiers,high-frequencytransformers,high-frequencyconverters,high-frequencychokecores,currenttransformercores,leakageprotectionswitches,andcommon-modeinductorcores.
Comparisonofthecharacteristicsofcommonlyusedsoftmagneticcores
1.Comparisonofthecharacteristicsofmagneticpowdercoresandferrites:MPPcores:useampereturns<200,50Hz~1kHz,μe:125~500;1~10kHz;μe:125~200;>100kHz:μe:10~125
HFcore:useampereturns<500,canbeusedinlargerOnthepowersupply,itisnoteasytobesaturatedunderalargemagneticfield,whichcanensuretheminimumDCdriftoftheinductance,μe:20~125
Ironpowdercore:useampere-turns>800,canbeusedinhighmagnetizationThefieldisnotsaturated,whichcanensurethestabilityofACandDCsuperpositionwiththebestinductancevalue.Thefrequencycharacteristicisstablewithin200kHz;butthehighfrequencylossislarge,suitableforusebelow10kHz.
FeSiAlFmagneticcore:insteadofironpowdercore,theusefrequencycanbegreaterthan8kHz.TheDCbiascapabilityisbetweenMPPandHF.
Ferrite:lowsaturationmagneticdensity(5000Gs),minimumDCbiascapability3.Comparisonofthecharacteristicsofsiliconsteel,permalloy,andamorphousalloy:
SiliconsteelandFeSiAlmaterialsIthashighsaturationmagneticinductionvalueBs,butitseffectivepermeabilityvalueislow,especiallyinthehighfrequencyrange;
Permalloyhashighinitialpermeability,lowcoercivityandloss,magneticItcanbestable,buttheBsisnothighenough.Whenthefrequencyisgreaterthan20kHz,thelossandeffectivepermeabilityarenotideal,thepriceismoreexpensive,andtheprocessingandheattreatmentarecomplicated.Cobalt-basedamorphousalloyshavehighpermeability,LowHc,lowlossinawidefrequencyrange,closetozerosaturationmagnetostrictioncoefficient,insensitivetostress,butlowBsvalueandexpensive;
Iron-basedamorphousalloyshavehighTheBsvalueandpricearenothigh,buttheeffectivepermeabilityvalueislow.
ThemagneticpermeabilityandHcvalueofthenanocrystallinealloyareclosetocrystallinehighpermalloyandcobalt-basedamorphous,andthesaturationmagneticinductionBsisequivalenttothatofmediumnickelpermalloy.TheheattreatmentprocessissimpleanditisakindofIdeallow-costhigh-performancesoftmagneticmaterial;althoughtheBsvalueofnanocrystallinealloysislowerthanthatofiron-basedamorphousandsiliconsteel,itshigh-frequencylossunderhighmagneticinductionismuchlowerthanthem,andithasbettercorrosionresistanceandMagneticstability.Comparedwithferrite,nanocrystallinealloyhas2to3timeshigherworkingmagneticinductiononthebasisoflowerlosswhenitislowerthan50kHz,andthemagneticcorevolumecanbemorethandoubled.
Method
Reducethelossofinductorcore
Everyoneknowsthatinductorcoreisusedinmanyelectronicproducts.Oneoftheproducts,suchasmobilephones,MP3,MP4,computers,converters,transformersandLEDTVdisplays,etc.Andeveryoneshouldalsoknowthatelectronicproductsproduceacertainamountoflossduringuse,andinductorcoresarenoexception.However,ifthelossoftheinductorcoreistoolarge,itwillleadtoareductionintheservicelifeoftheinductorcore,andinseverecases,itwillalsoaffectthenormaloperationoftheproductusingtheinductorcore.Sohowshouldwereducethelossoftheinductorcore?
Thereasonforthelossoftheinductorcore:
ThelossofthechipinductorcoremainlycomesfromthecorelossandcoillossTwoaspects,andthesizeofthelossinthesetwoaspectsneedstobejudgedaccordingtoitsdifferentcircuitmodes.Amongthem,thecorelossismainlycausedbythealternatingmagneticfieldinthecorematerial.Thelossitgeneratesisafunctionoftheoperatingfrequencyandthetotalmagneticfluxswing(ΔB),whichwillgreatlyreducetheeffectiveconductionloss.Coillossistheenergylosscausedbythechangeofmagneticenergy.Itwillreducethestrengthofthemagneticfieldwhenthepowerinductorcurrentdrops.
Methodsforreducingthelossoftheinductorcore:
1.Thecorelossgeneratedintheinductorcorewilldecreasewiththeincreaseoftheinductorcoreloss.TheallowablecopperwirelossisalsoWillbringthesameinductancemagneticcorematerialfluxsurge.Therefore,whentheswitchingfrequencyrisesabove500kHz,theinductorcorelossandwindingAClosscangreatlyreducetheallowableDCcurrentintheinductor.
2.Thelossoftheinductorcoreinthecoilismainlymanifestedinthelossofthecopperwire.Therefore,ifyouwanttoreducethelossofthecopperwire,youmustreducethelossoftheinductorcorewhenthelossoftheinductorcoreincreases.equal.Thebestcaseisthatthelossesremainstableandequalathighfrequenciesandallowthemaximumoutputcurrenttobeobtainedfromthemagneticstructure.