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外文資料翻譯中英文對照外文翻譯文獻(文檔含英文原文和中文翻譯)LowPowerMagneticBearingDesignForHighSpeedRotatingMachineryP.E.Allaire,E.H.Maslen,andR.R.Humphris,DepartmentofMechanicalandAerospaceEngineeringUniversityofVirginiaCharlottesville,VA22901C.K.SortoreAuraSystems,Inc.EISegundo,CA90245P.A.StuderMagneticConceptsSilverSprings,MD20901317SUMMARYAgneticsuspensiontechnologyhasadvancedtothepointofbeingabletoofferanumberofadvantagestoavarietyofapplicationsintherotatingmachineryandaerospacefields.Onestrongadvantageofmagneticbearingsoverconventionalbearingsisthedecreaseinpowerconsumption.Theuseofpermanentmagnets,alongwithelectromagnets,isoneappealingoptionwhichcanfurtherreducethepowerconsumptionofthebearing.Thedesignandconstructionofasetofpermanentmagnetbiased,activelycontrolledmagneticbearingsforaflexiblerotorispresented.Bothpermanentmagnetsandelectromagnetsareusedinaconfigurationwhicheffectivelyprovidesthenecessaryfluxesintheappropriateairgaps,whilesimultaneouslykeepingtheundesirabledestabilizingforcestoaminimum.Thedesignincludestworadialbearingsandathrustbearing.Thetheoreticaldevelopmentbehindthedesignisbrieflydiscussed.Experimentalperformanceresultsforasetofoperatingprototypebearingsispresented.Theresultsincludemeasurementsofloadcapacity,bearingstiffnessanddampingandthedynamicresponseoftherotor.Withfewexceptions,theexperimentalmeasurementsmatchedverywellwiththepredictedperformance.Thepowerconsumptionofthesebearingswasfoundtobesignificantlyreducedfromthatforacomparablesetofallelectromagneticbearing.INTRODUCTIONMagneticbearingshaveanumberofstrongadvantages.Onemostobviousadvantageistheirnon~ontacting,virtuallyfriction-freecharacteristics.Entirelubricationsystemsandtheneedformechanicaloilseals,whichaddtofrictionlossesandinstabilitiesassociatedwithcrosscoupledbearingcoefficients,canbeeliminatedbyusingthesetypesofbearings.Thelifeexpectancyofamagneticbearing,inmanycases,canbemuchhigherthanthatofconventionalbearing.Duetothenon~ontactingnatureofthebearings,mechanicalpartsdonotwearout.Thiscanobviouslyincreasesystemreliabilityanddecreasecostlyrepairsandnecessarymaintenancewhichinterruptprofitablemachineoperation.Ifdesignedproperly,amagneticbearingcanperformundermuchharsherconditionsandenvironmentsforextendedperiodsoftimewhichwouldnotbepossiblewithothertypesofbearings.Onefurtheradvantageofthefrictionlesscharacteristicofthesebearingsisthatofpowerloss.Thepowerconsumptionofaconventionalfluid-filmbearingisinmanycasesmuchmorethanforamagneticbearing.Powerlossreductionsofoneorderofmagnitudeormorecanbeexpectedwhenamachineisconvertedfromusingconventionalbearingstomagneticbearings.Avarietyofworkhasbeenaccomplishedonanumberofdifferentapplicationsandaspectsofmagneticbearings.Anextensiveamountofresearchhasbeenperformedbyanumberofuniversityandindustryresearchersonthedevelopmentofmagneticbearingsinan·industrialcannedmotorpump[1].AnumberofothersuccessfulindustrialapplicationsofmagneticbearingshasbeenreportedbyWeise[21.Burrowset.al.[3]presentsthedevelopmentandapplicationofamagneticbearingspecificallydesignedforthevibrationcontrolofaflexiblerotor.Keith,et.al.[4]successfullydevelopedaPC-baseddigitalcontrollerformagneticbearings.Continuingresearchisbeingperformedintheareasofdigitalandadaptivecontrolsformagneticbearings.Inresearchingtheuseofpermanentmagnetsincombinationwithelectromagnets,ofparticularinterestaretwopatentscreditedtoPhilipStuder[5,6].Thesepatentscontainanumberoffeatures,primarilydealingwithpermanentmagnets,whichhaveusefulapplicationtothebearingsdiscussedinthispaper.WilsonandStu~er[7]havealsoappliedthepermanentmagnetbiasconcepttoalinearmotionbearing.Ohkamiet.al.[8]haveperformedsomeinterestingcomparisonstudiesofmagneticbearingsofvariousconfigurationswhichusepermanentmagnets.AnotherpaperbyTsuchiyaet.al.[9]studiesandcommentsonthestabilityofahighspeedrotorwhichissuspendedinmagneticbearingsbiasedwithpermanentmagnets.Meeks[10]hasalsoperformedacomparisonofthevariousmagneticbearingdesignapproachesandconcludesthatthecombiningofactivelycontrolledelectromagnetswithpermanentmagnetsresultsinasuperiormagneticbearingintermsofsize,weightandpowerconsumption.Therareearthpermanentmagnetsoftoday,inparticularSm-CoandNd-Fe-Bomagnets,offerveryhighperformancecharacteristicsintermsofmagneticstrength,energyproductandthermalqualities.Themagnetdesignerisabletoconcentrateaverylargeamountofmagneticenergyinasmallpackage,makingmoreefficientuseofavailablespace.ThedesignconceptforthepermanentmagnetbiasedmagneticbearingdesigndiscussedinthispaperisavariationonresearchanddevelopmentreportedbyStuder[5,6].Thefollowingtwosectionsgiveabriefdescriptionofhowthebearingsconceptuallyoperate.RadialMagnetiCBearingDescriptionAdiagramofapermanentmagnetbiasedradialmagneticbearingisshowninFigure1.Thisbearingisdesignedtooperateatoneendoftherotorandcontrolradialforcesonly.Fouraxiallymagnetizedarcsegmentmagnetsarepositionedcircumferentiallyadjacenttothestator.Thebiasfluxgeneratedbythepermanentmagnetspassesdownthelaminatedstatorpoleleg,throughtheworkingairgap,axiallyalongtheshaft,thenreturnstothepermanentmagnetvia.aradialbiaspolepiece.Theactivecontrolfluxgeneratedbythecoilsalsopassesdownthestatorpolelegandthroughtheworkingairgap.Thereturnpathfortheactivefluxisthencircumferentiallyaroundthestator,asshowninFigure1.Thisdesignrequiresonlyfourpolesandfourcoils,unlikeanallelectromagneticdesignwhichgenerallyrequireseight.Inaddition,sincethecoilsforeachbearingaxisareconnectedinseries,thebearingcontrolsystemrequiresonlyfivecurrentamplifierchannels,whichishalfasmanyasrequiredoftheallelectromagneticbearing.CombinationRadial/ThrustMagneticBearingDescriptionAschematicofthisbearingdesign,revealingthevariousmagneticpaths,isshowninFigure2.Thisbearingcombinescontrolofbothradialandthrustforces.Theradialportionofthebearingisidenticaltothatwhichwasdescribedintheprevioussection.Thethrustcontrolhowever,isimplementedbyauniquemagneticfluxconfiguration.Thepermanentmagnetbiasfluxpassingalongtheshaftsplitsequallybetweenthetwothrustpolesbeforereturningtothepermanentmagnet.Asingleactivecoilproducesamagneticflux,intheshapeofatoroid,whichsymmetricallyaddsorsubtractstothebiasfluxintheworkingairgapsbetweenthethrustdiskandthrustpoles.DesignConceptThebearingsdesignedforthisprojectaredifferentfromallelectromagneticbearingdesignsinthattheyemploybothpermanentmagnetsandelectromagnets.Permanentmagnetsgeneratethebiasfluxintheworkingairgapsandelectromagnetsareusedtomodulatethisflux.Thepurposeofestablishingabiasfluxintheworkingairgapsistolinearizethegoverningforceequationofthemagneticactuator.Thebiasfluxisanominalfluxdensityaboutwhichthecontrolfluxisvaried.Ifabiasfluxofzeroisused,(onlyoneopposingactuatorisoperatedatatime,)thentheforcegeneratedbytheactuatorontherotorfollowsaquadraticforcelaw,i.e.,theforcewillbeproportionaltothesquareofthefluxdensityintheairgaps.Consequently,theforceslewratewillbezerowhentherotorisinthenominalbalancedpositionandthetransientresponsewillbeadverselyeffected.If,however,thebearingfluxesaremodulatedaboutanon-zerobiasflux,(withopposingactuatorssymmetricallyperturbed,)itiseasilyshownthattheforcebecomeslinearlyrelatedtothecontrolflux.Thefollowingsectiondemonstratesthisimportantrelation.ForceRelationshipsTheforcegeneratedinanairgapofareaAgandlengthgbyamagneticactuatorcanbeexpressedbythedirectrelationwhereBgisthefluxdensityintheairgapandJ.Loisthepermeabilityoffreespace.Ifonlyasingleaxisofthebearingisconsidered,thenthenetforceactingontheshaftwillbethedifferenceofthetwooppositeactingactuatorforces.Assumingtheareasofthetwoopposingairgapsarethesame,theforceactingontheshaftbythemagneticbearingcanbeexpressedasThefluxdensityintheairgapsisbeingsuppliedbytwosources,i.e.,thepermanentmagnetandthecoil.Inordertoproperlyprovidedifferentialcontrol,thefluxesinthetwogapsaresymmetricallyperturbedsothatthefluxinonegapisincreasedwhilethefluxintheoppositegapisdecreasedbythesameamount.ThisimpliesthatwhereBpmisthefluxdensitygeneratedby'thepermanentmagnetandBeisthefluxdensitygeneratedbythecoil.SubstitutingEqs.l3,4)intoEq.(2),expandingandsimplifying,theforceactingontheshaftcannowbeexpressedasByexpressingtheequationfortheforceontheshaftinthisform,itisinterestingtonotethattheforceisnotonlyproportionaltothebiaslevel,Bpm,butitisalsolinearizedwithrespecttothecontrolflux,Be..OpenLoopStiffnessandActuatorGainTheforcegeneratedbythebearinginthehorizontaldirection,Fx,canbeaccuratelyapproximatedbythetruncatedTaylorseriesexpansioninthefollowingway:Iftnemagneticcircuitisbalanced,thenthefirstterminEq.(6)isequaltozeroandwherexrepresentstherotordisplacementandierepresentsthecontrolcurrentintheelectromagneticcoil.TheparametersKxandKiaredefinedashequantityKxisreferredtoastheopenloopstiffnessandrepresentsthechangeinthehorizontalforceduetohorizontaldisplacement.Theopenloopstiffnessisalwaysnegativewhichimpliesthatthebearingisunstableintheopenloopcontrolconfiguration.Unlikeaactualspringwithapositivestiffness,apositivedispacementoftherotortowardthemagnetwillincreasetheattractiveforce.ThequantityKirepresentstheactuatorgainofthebearing.Itrepresentschangesinthehorizontalforceduetocontrolcurrent,ie.Equivalentexpressionsexistforthecomponentsoftheverticalforceexpression.Expressionsfortheopenloopstiffnessandtheactuatorgainaredeterminedbyperformingtheappropriatedifferentiationoftheforceexpression.TheseexpressionstakeontheformwhereLandHrepresentthelengthanddemagnetizationforce,respectively,ofthepermanentmagnetandNisthenumberofturnsintheelectromagneticcoil.ControlSystemDescriptionThecontrolelementsofthissystemarethosecomponentswhichdetectthemotionoftheshaft,determinetherequiredcontrolforceandgenerateacoilcurrentrequiredbythemagneticbearingtogeneratethisforce.Themagneticbearingsystemconsistsoffourdistinctcomponents:themagneticactuator,thedisplacementsensorsandassociatedconditioningcircuits,theanalogPIDcontrollerandthepoweramplifier.Theactualmagneticbearingmainlyconsistsoftheelectromagneticcoils,ironpolepieces,rotorandpermanentmagnets.Thesignalconditioningcomponentconsistsoftheeddycurrentinductiondisplacementsensors,signalamplificationandcoordinatetransformationcircuits.Theanalogcontrollerprimarilyconsistsofthreeseparatecomponents.Thecomponentstaketheformofproportional(P),integral(I)andderivative(D)compensationnetworks.Thesethreeparallelstagesareaddedtogetherthroughasummingamplifiertoproducetheoutputoftheanalogcontroller.Thelastcomponentinthecontrolloopisthepoweramplifier.Theamplifier,uponrequestofthecontroller,suppliestherequiredcurrenttomagneticcoilstoproducethenecessaryfluxesinthebearing.Thedynamicsofthebearing-rotorsystemcanbecombinedwiththeoperatingcharacteristicsofthecontrolelectronicstoformaclosed-loopcontrolsystem.ThiscontrolsystemisshowninasimplifiedblockdiagramforminFigure3.Thedisplacementsensorcharacteristics,analogcontrollerandamplifiermakeuptherelativelycomplextransferfunctionofthefeedbackcontroller,Gc(s).Thefeedbackcontrollerrelatestherotorpositiontotheactuatorcurrent.Theclosed-looptransferfunctionforthismagneticbearingsystem,asdeterminedfromthisblockdiagram,isgivenbywheremisthemassoftherotorsupportedbythebearing.PrototypeBearingConstructionThefour-poleradialbearingstators,asshowninthediagramsofFigures1and2,weredesignedtobeidenticalforbothbearings.Thestatorsandrotorswereconstructedof3%silicon-ironlaminationmaterialwhichhadathicknessof0.007inches.Eachlaminatedcomponentconsistsofapproximately100laminations.Thelaminationsweregluedtogetherusingatwopartactivator/resinadhesiveandtheshapewasmachinedbywireEDM(electricdischargemachining.)Thebearingstatorshaveanoutsidediameterofapproximately3.0inchesandanaxiallengthofapproximately0.7inches.Theoutsidediameterofthelaminatedrotorisapproximately1.5inches.Thethrustbearingcomponentsweremachinedfromsoftmagnetiron.Thehighenergypermanentmagnets,madeoutofageodymium-Iron-Boronalloy,haveamaximumenergyproductof30MG-Oe.Thebearingssupportashaftweighingapproximately3.7Ibm.LoadCapacityMeasurementsofthemaximumloadappliedtotheshaft,beforefallingoutofsupport,areplottedasafunctionofproportionalcontrollergain,Kp,inFigure4.Theforceinthistestwasappliedbyhangingweightsontheshaft.Apulleysystemwasconstructedinsuchawaythattheforcecouldbeappliedinthedesireddirection.Theforceintheplotsrepresentsforcesappliedalongthebearingaxes.Thevariationofthemaximumloadatlowerproportionalgainsisactuallyameasureofthestabilitythresholdofthesystem.ItisnotedinEq.t8)thattheopenloopstiffness,Kxisdefinedatanominaloperatingpoint,i.e.,rotorpositionandcontrolcurrentequaltozero.However,asthebearingisloadedwithastaticforce,thesteadystatecurrentbeginstoincrease.ItcanbeshownanalyticallythatKxisafunctionoftheoperatingpointofthecontrolcurrent.Thatis,asthecontrolcurrentcurrentincreases,Kxalsoincreases.IncreasingproportionalgainhastheeffectofcompensatingforthisincreaseinKxandconsequentlyincreasingthestabilityofthesystem.Themeasurementsmadeathigherproportionalgainsrepresentamoreaccuratemeasureoftheactualloadcapacityofthebearing.Enoughstabilityisprovidedsothatmagneticsaturationisreachedinthebearingpolestructures.ThemaximumpredictedloadsintheplotsofFigure4arecalculatedatthepointofmagneticsaturation.EquivalentBearingStiffnessandDampingMeasurementsoftheequivalentstiffnessofthebearingsareshowninFigure5.Thissimplemeasurementwasperformedbyapplyingaconstantforce,~F,andnotingthedisplacement,~x,oftheshaft(controllerintegratorsturnedoff.)ThestiffnessthenisgivensimplybyKeq=~F/~x.Alinearregressionwasperformedonthemeasureddata,whichresultedinverygoodcorrelation,ascanbeobservedintheplots.Itisnotedthattheproportionalgainhasadirecteffectonthestiffnessofthebearings,ashasbeenpreviouslydemonstratedbyHumphris,et.al.[11].Relativedampinginthebearingswasinvestigatedfromawhitenoisefrequencyresponseanalysisofthebearingandrotor.Theanalysiswasperformedbyinjectingnoise,composedofallfrequenciesofinterest,intooneaxisoftheturbine-endradialbearing,andperformingaFFT(FastFourierTransform)analysisonthevibrationresponseofthataxis.Thislinearfrequencyresponse,composedof100averages,isshowninFigure6.Thederivativecontrollergain,Krwasvariedthrougharangeofvaluesasnotedintheplot.Asexpected,thederivativegainhadadirecteffectonthedampinginthebearings[11].Thefirstlargespikerepresentsthefirsttwomodesofshaftvibration.Theyareveryclosetogetherinfrequencyandessentiallyindistinguishable.Thefrequencyofthesecondspikeisthethirdmodeofvibrationandthethirdsmallspikeatapproximately60,000cpmisthefourthmode.Itisnotedthatthevariationofthederivativegainstronglyeffectsthefirsttwomodes,hasasmalleffectonthethirdmodeandvirtuallynoinfluenceonthevibrationamplitudeofthefourthmode.CriticalSpeedsandRotorResponseThedampedsynchronouscriticalspeedsoftheflexibleshaftsupportedbythesebearingscanbeapproximatelydeterminedfromthewhitenoisefrequencyresponseplotsofFigure6.Thesevalues,however,representthezerospeednaturalfrequencies,andthegyroscopicstiffeningeffectsofanyattacheddiskswouldnotbeincluded.Sincethenaturalfrequencyisgivenby,wherekistheshaftstiffnessandminthemodalmassoftherotor,itisofcourseexpectedthattheobservedcriticalspeeds,whentheshaftwasspinning,wouldbehigher.PlotsshowingthevibrationmagnitudeandphasefortheshaftspeedsthatwereobtainedisincludedinFigure7.Amplitudeinformationwastakendirectlyfromthemagneticbearingsensorsandakey-phasesensorwasusedtoprovidethephaseinformation.AccordingtothemaximumvibrationamplitudesobservedinFigure7,thefirstvibrationmodeisobservedtooccuratapproximately10,000rpmandthesecondatapproximately13,000rpm.PowerConsumptionFinally,anumberofpowerconsumptionmeasurementsweremade.Measurementsofthepowerweretakenwithawattmeterforanumberofcases.Thismeterisusedwiththeassumptionthatthemeasuredvoltageandcurrentbeingsuppliedtothecontrolelectronicsissinusoidalinnature.Inaddition,itisrealizedthatitrepresentsasomewhatgrossmeasurementasitincludesalltheinefficienciesofthevariouselectroniccomponents.Table1summarizestheresults.Thenon~ssentialelectronicdiagnosticcomponentsofthebearingsystemwereobservedtoconsumeonlyabout7watts.Thesemeasurementsrepresentasignificantimprovementoverthe500wattsofapproximatetotalpowerconsumedbyacomparablecurrentbiasedallelectromagneticbearingdesign.CONCLUSIONSThebrieftheorywhichwaspresentedinthispaperestablishedthebasicelectromagneticandmechanicalrelationshipsnecessarytodevelopasetofpermanentmagnetbiasedmagneticbearings.Thedesigninvolvedbothradialandthrustbearings.Theavailabilityofnewerrare-earthhighenergypermanentmagnetsmadeitpossibletoeffectivelyprovidethenecessarybiasfluxesinthebearing.Thebearingsandrotorweresuccessfullyconstructedandoperated.Anumberoftestsandexperimentswereperformedonthebearing-rotorsystem.Thetestsconsistedofloadcapacity,stiffnessanddampingmeasurements.Theresultsprovedtobeverypositiveinthatthetheoreticalpredictionsandtheobservedperformancematchedreasonablywell,givingcredibilitytothemodelswhichwereusedtoperformtheanalysis.Ofparticularinterestforthisstudywasthemeasuredpowerconsumptionofthebearings.Itclearlydemonstratesthattheuseofpermanentmagnetscanimprovetheoperatingefficiencyofanactivemagneticbearing.Itwassuccessfullyobservedanddemonstratedthatthesebearingshavestrongpotentialforfutureuseasefficient,reliablebearings.However,furtherresearchanddevelopmentisrequiredintheareasofcontrols,magneticmaterialsandactuatordesignbeforeitispossibletoinstallthemintoausefulindustrialapplication.REFERENCES1.AllaireP.;Imlach,J.;McDonald,J.;Humphris,R.;Lewis,D.;Banerjee,B.;Blair,B.;Clayton,J.;Flack,R.:"Design,ConstructionandTestofMagneticBearingsinanIndustrialCannedMotorPump,"PumpUsersSymposium,TexasA&M,Houston,TX,May1989.2.Weise,D.A.:"PresentIndustrialApplicationsofActiveMagneticBearings,"Presentedatthe22ndIntersocietyEnergyConversionEngineeringConference,Philadelphia,Pennsylvania,August1987.3.Burrows,C.R.,Sahinkaya,N.;Traxler,A.;andSchweitzer,G.:"DesignandApplicationofaMagneticBearingforVibrationControlandStabilizationofaFlexibleRotor,"ProceedingsoftheFirstInternationalMagneticBearingsSymposium,ETHZurich,Switzerland,June1988.4.KeithF.J.,Williams,R.D.;Allaire,P.E.;andSchafer,R.M.:"DigitalControlofMagneticBearingsSupportingaMultimassFlexibleRotor,"PresentedattheMagneticSuspensionTechnologyWorkshop,Hampton,Virginia,February1988.5.Studer.P.A.:NASA,MagneticBearing,Patent3865442,PatentApplication100637,February1975.6.Studer,P.A.:NASA,LinearMagneticBearing,Patent4387935,PatentApplication214361,December1980.7.Wilson,M.;andStuder,P.A.:"LinearMagneticBearings,"PresentedattheInternationalWorkshoponRareEarth-CobaltMagnetsandTheirApplications,Roanoake,Virginia,June1981.8.Ohkami,Y.,Okamato,0.;Kida,T.;Murakami,C.;Nakajima,A.;Hagihara,S.;andYabuuchi,K.:"AComparisonStudyofVariousTypesofMagneticBearingsUtilizingPermanentMagnets,"PresentedattheInternationalWorkshoponRareEarth-CobaltPermanentMagnetsandTheirApplications,Roanoake,Virginia,June1981.9.Tsuchiya,K;Inoue,M.;Nakajima,A.;Ohkami,Y.;andMurakami,C.:"OnStabilityofMagneticallySuspendedRotoratHighRotationalSpeed,."PresentedattheAerospaceSciencesMeeting,Reno,Nevada,January1989.10.Meeks,C.:"TrendsinMagneticBearingDesign,"PaperpresentedatNavalSeaSystemsCommandMagneticBearingForum,Washington,D.C.,July1989.高速旋轉機械的低功率磁力軸承設計總結:磁懸液研究具有先進的研發技術,有一定的優勢,廣泛應用于旋轉機械和航空航天等領域。最突出的優勢,磁力軸承比傳統的軸承功耗少。電磁鐵是一個十分具有吸引力的選擇,它可以進一步降低軸承的功耗。一組永久磁鐵偏置,主動控制的磁軸承的柔性轉子。永久磁鐵和電磁鐵的配置有效地提供通量在合適的氣隙,同時將不穩定力量降到最低。該設計包括2個徑向軸承和一個推力軸承。對設計理論和發展進行了簡要討論。一組操作的原型軸承的實驗性能結果如下,結果包括負載能力的測量,軸承剛度和阻尼和轉子的動態響應。有幾個情況是例外,實驗測量相匹配的預測性能非常好,這些軸承的功率消耗顯減少。簡介:磁力軸承有許多優點。一個最明顯的優勢是無摩擦的特點。整個潤滑系統和機械油封,這增加了摩擦損失和不穩定性與交叉耦合軸承系數,可以消除這些類型的軸承的摩擦。一個磁力軸承的壽命,在正常情況下,可以遠高于傳統的軸承。由于好性質的軸承,機械零件不磨損。這可以明顯提高系統的可靠性,降低成本的維修,中斷盈利機器操作。如果設計得當,磁軸承工作的時間是不可能與其他類型的軸承長時間在嚴酷的條件和環境下進行。對于這些軸承的摩擦特性,另一個優點是功率損失。傳統的流體膜軸承的功率消耗無時無刻,遠遠超過了磁性軸承。當一臺機器使用傳統的軸承到換用磁力軸承的時候,可以從一個數量級或更高的減少功率損耗。各種各樣的程序完成了一些不同的工作和磁性軸承的運行。許多研究人員和工業研究人員已經進行了大量的實驗研究,工業屏蔽電機泵的磁軸承的發展[1],和多磁軸承在工業廣泛應用已被魏澤[2]報道。為撓性轉子振動控制系統的開發與應[4],成功研制出一種基于微機的磁力軸承數字控制器。正在進行的數字和自適應控制的磁軸承的持續研究,在研究永磁體結合電磁鐵的使用,兩個專利歸功于菲利普[5,6]。這些專利包含了一些內容,主要是處理永久磁鐵,這有助于本文討論的軸承。Wilson和斯圖~二[7]也應用了永磁偏置的概念,在一個直線運動軸承。ohkami等人[8]對使用永久磁鐵的各種結構的磁力軸承進行了一些有意義的比較研究。土屋等人的另一篇論文,[9]懸浮于永磁體的磁懸浮轉子高速轉子穩定性的研究與評價。米克斯[10]還說出各種磁軸承的設計方法并進行比較和總結,控制電磁鐵與磁軸承的永久磁鐵的作用相結合,重量和功耗減少,今天的稀土永磁體,特別是釹鐵磁體,擁有非常高的性能特點,在磁場強度,能源產品和熱質量方面。磁鐵設計人員能夠將大量的磁能量集中在一個小的包中,使得更有效地利用可用空間。對永磁偏置磁軸承的設計本文設計的概念是由Studer[5報告的研究和發展變化,6]。下面兩節簡要說明如何在概念上操作的軸承。1.組合徑向/推力磁軸承描述此軸承設計,揭示了各種磁性路徑,這種軸承的徑向和推力相結合的控制。軸承的徑向部分是相同的,這是在上一節中描述的。然而,推力控制,實現由一個獨特的磁通配置。永久磁鐵的偏置磁通通過沿軸分裂之前,兩個推力桿,返回到永久磁鐵。一個積極的線圈產生磁場,在一個環形的形狀,對稱添加或減去在推力盤與推力桿之間的工作氣隙磁偏置。2.設計理念本課題設計的軸承是不同于所有電磁軸承的設計中,他們采用永久磁鐵和電磁鐵。永久磁鐵產生的偏置磁場在工作間隙和電磁鐵是用來調節這個流量。在工作間隙建立偏置磁場的目的是對磁驅動器的控制力方程線性化。偏置磁通是一個額定磁通密度的控制磁通變化的。如果零的偏置磁通,(只有一個相對的致動器操作的時間,),然后由致動器所產生的致動器的轉子上的二次力法,即,該力將在空氣間隙中的磁通密度的平方成正比。因此,強制轉換率將是零,當轉子處于額定平衡位置和瞬態響應將受到不利影響。如果,軸承磁通調制約一個非零的偏置磁通,(與相對的致動器對稱擾動),很容易地表明,力與控制磁通呈線性關系。下面的部分演示了這個重要關系。力量關系磁性致動器產生的空氣間隙中的空氣間隙的力可以表示由直接關系BG在空氣間隙和J.Lo的磁通密度是具有自由空間的通透性。如果僅僅是一個軸的軸承被認為具有這種特性,由于軸上的凈力作用,兩個相反的作用致動器力的差異。假設兩者的相對空氣間隙的區域是相同的,通過磁力軸承作用于軸上的力可以表示為F。空氣間隙中的磁通密度由2個源提供,即永磁體和線圈。為了正確地提供差分控制,在2個間隙的磁通對稱擾動,一個間隙中的磁通增加,而相反的間隙中的磁通減少相同的量。這意味著BPM產生的永久磁鐵的磁通密度和由線圈產生的磁通密度。替代式。L3、4)代入式(2),擴展和簡化,作用在軸可以表示為Y表示對這種形式的軸力的方程,需要注意的是,力不僅是偏置電平,BPM比例很有趣,但它也是線性化控制流量。開環剛度和執行器增益在水平方向上的受力所產生的力,可以準確地近似截斷泰勒級數展開的以下方式:如果在磁路平衡,然后在公式的第一項(6)等于零在《X代表和單位代表轉子位移控制的電磁線圈的電流。“鴨王是KX參數定義為KX的量稱為開環剛度是由于水平位移在水平力的變化。開環剛度是負的,這意味著軸承是不穩定的開環控制配置。不像一個正剛度彈簧位移,磁轉子會增加吸引力。它的數量表示軸承的執行器增益。這是由于控制電流水平力的變化,垂直表達的成分存在等價表達式。用于開環剛度和執行器增益的表達式通過執行當差異化的力表達式來確定。這些表達式采取的形式那里的土地H代表長度和退磁力,分別代表在永磁體和N是在電磁線圈的匝數。控制系統說明該系統的控制元件是檢測軸的運動的組件,確定所需的控制力,并由一個線圈電流所需的磁力軸承產生這種力量。該磁軸承系統有四個不同的組成部分:磁性致動器,位移傳感器和相關的調理電路,模擬量控制器和功率放大器。實際的磁軸承主要由電磁線圈、鐵磁極片、轉子和永久磁鐵組成。信號調理元件由電渦流感應位移傳感器、信號放大和坐標轉換電路組成。模擬控制器主要由三個獨立的組件組成。組成比例(對)、積分(我)和派生(和)補償網絡的組成部分。這三個并聯階段通過相加放大器相加,以產生模擬控制器的輸出。控制回路中的最后一個組成部分是功率放大器。該放大器,根據控制器的要求,提供所需的電流,以產生必要的磁通在軸承的磁場線圈。軸承轉子系統的動態可以結合控制電子的工作特性,形成一個閉環控制系統。該控制系統中的簡化框圖形式中顯示。位移傳感器特性、模擬控制器和放大器組成了反饋控制器相對復雜的傳遞函數。反饋控制器將轉子位置與致動器電流有關。此磁軸承系統的閉環傳遞函數,確定從這個框圖,給出4.控制系統描述四磁極徑向軸承定子,在設計上是相同的兩個軸承。定子和轉子的構造3%硅鐵層壓材料,厚度為0.007英寸。每個層壓組件由約100片。疊片膠合在一起使用一部分活化劑/樹脂膠粘劑和形狀是電火花線切割加工(電火花加工。)軸承定子的外約3英寸,軸向長度約0.7英寸。層片的外直徑約為1.5英寸。從軟磁鐵鐵的推軸承組件進行加工。高能永磁體,由geodymium鐵硼合金有30毫克的OE最大磁能積。軸承支撐體重約3.7IBM軸。5.承載能力應用于軸的最大負荷的測量,在失去支持,被繪制為一個函數的比例控制器增益KP,在這個測試中,在軸上懸掛重物。用這樣一種方式,該力可以施加在所需的方向上構造一個滑輪系統。圖中的力表示沿軸承軸施加的力。在較低的比例增益的最大負載的變化實際上是一個衡量系統的穩定性閾值。它是在式8注),開環剛度,KX是定義在一個標稱工作點,即轉子位置和控制電流等于零。然而,隨著軸承的靜載作用,穩態電流開始增加。它可以顯示分析,KX具有控制電流的工作點的功能。即為控制電流的增大,KX也增加。增加比例增益補償增加的KX從而提高系統穩定性的影響。在較高比例的收益的測量代表了更準確的測量軸承的實際負載能力。提供足夠的穩定性,使磁飽和的軸承磁極結構達到。最大預測載荷是在磁飽和點上計算的。6.等效軸承剛度和阻尼測量的軸承的等效剛度,這個簡單的測量是通過施加一個恒定的力,進
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