Review-of-maglev-train-technologies

IEEETRANSACTIONSONMAGNETICS,VOL.42,NO.7,JULY20061917ReviewofMaglevTrainTechnologiesHyung-WooLee1,Ki-ChanKim2,andJuLee2KoreaRailroadResearchInstitute,Uiwang437-757,KoreaDepartmentofElectricalEngineering,HanyangUniversity,Seoul133-791,KoreaThispaperreviewsandsummarizesMaglevtraintechnologiesfromanelectricalengineeringpointofviewandassimilatestheresultsofworksoverthepastthreedecadescarriedoutallovertheworld.ManyresearchesanddevelopmentsconcerningtheMaglevtrainhavebeenaccomplished;however,theyarenotalwayseasytounderstand.ThepurposeofthispaperistomaketheMaglevtraintechnologiesclearataglance.Includedaregeneralunderstandings,technologies,andworldwidepracticalprojects.Furtherresearchneedsarealsoaddressed.IndexTerms—EDS,EMS,Maglevtrain,magneticguidance,magneticlevitation,magneticpropulsion.I.INTRODUCTIONALONGwiththeincreaseofpopulationandexpansioninlivingzones,automobilesandairservicescannotaffordmasstransitanymore.Accordingly,demandsforin-novativemeansofpublictransportationhaveincreased.Inordertoappropriatelyservethepublic,suchanew-generationtransportationsystemmustmeetcertainrequirementssuchasrapidity,reliability,andsafety.Inaddition,itshouldbeconvenient,environment-friendly,lowmaintenance,compact,light-weight,unattained,andsuitedtomass-transportation.Themagneticlevitation(Maglev)trainisoneofthebestcandidatestosatisfythoserequirements.Whileaconventionaltraindrivesforwardbyusingfrictionbetweenwheelsandrails,theMaglevtrainreplaceswheelsbyelectromagnetsandlevitatesontheguideway,producingpropulsionforceelectromechanicallywithoutanycontact.TheMaglevtraincanbereasonablydatedfrom1934whenHermannKemperofGermanypatentedit.Overthepastfewdecadessincethen,developmentoftheMaglevtrainwentthroughthequickeningperiodofthe1960s,thematurityofthe1970s–1980s,andthetestperiodofthe1990s,finallyaccomplishingpracticalpublicservicein2003inShanghai,China[1]–[4].SincetheMaglevtrainlookstobeaverypromisingsolu-tionforthenearfuture,manyresearchershavedevelopedtech-nologiessuchasthemodelingandanalysisoflinearelectricmachinery,superconductivity,permanentmagnets,andsoon[5]–[25].TheMaglevtrainoffersnumerousadvantagesoverthecon-ventionalwheel-on-railsystem:1)eliminationofwheelandtrackwearprovidingaconsequentreductioninmaintenancecosts[26];2)distributedweight-loadreducestheconstructioncostsoftheguideway;3)owingtoitsguideway,aMaglevtrainwillneverbederailed[96];4)theabsenceofwheelsremovesmuchnoiseandvibration;5)noncontactsystempreventsitfromslippingandslidinginoperation;6)achieveshighergradesandcurvesinasmallerradius;7)accomplishesaccelerationandde-celerationquickly;8)makesitpossibletoeliminategear,cou-pling,axles,bearings,andsoon;9)itislesssusceptibletoDigitalObjectIdentifier10.1109/TMAG.2006.875842TABLEICOMPARISONOFMAGLEVANDWHEEL-ON-RAILSYSTEMSweatherconditions.However,becausethereisnocontactbe-tweenrailsandwheelsintheMaglevtrain,thetractionmo-torsmustprovidenotonlypropulsionbutalsobrakingforcesbydirectelectromagneticinteractionwiththerails.Secondly,themoreweight,themoreelectricpowerisrequiredtosupportthelevitationforce,anditisnotsuitableforfreight.Thirdly,owingtothestructureoftheguideway,switchingorbranchingoffiscurrentlydifficult.Fourthly,itcannotbeoverlookedthatthemagneticfieldgeneratedfromthestrongelectromagnetsforlevitationandpropulsionhaseffectsonthepassengercompart-ment.Withoutpropermagneticshielding,themagneticfieldinthepassengercompartmentwillreach0.09Tatfloorleveland0.04Tatseatlevel.Suchfieldsareprobablynotharmfultohumanbeings,buttheymaycauseacertainamountofinconve-nience.Shieldingforpassengerprotectioncanbeaccomplishedinseveralwayssuchasbyputtingironbetweenthem,usingtheHalbachmagnetarraythathasaself-shieldingcharacteristic,andsoon.[27],[79].TableIshowsthecomparisonofMaglevandwheel-on-railsystems.Inallaspects,Maglevissuperiortoaconventionaltrain.TableIIrepresentsthecomparisonofcharacteristicsofthemasstransportationsystemsprovidedbytheMinistryofTrans-portationinJapan.Itisappreciablefromthetablesthattheten-dencyofglobaltransportationistowardtheMaglevtrain.Ac-cordingly,itisnecessarytobeconcernedandunderstandall0018-9464/$20.00©2006IEEE1918IEEETRANSACTIONSONMAGNETICS,VOL.42,NO.7,JULY2006TABLEIICOMPARISONOFCHARACTERISTICSOFTHEMASSTRANSPORTATIONSYSTEMSFig.1.Comparisonofsupport,guidance,andpropulsion.(a)Wheel-on-railsystem.(b)Maglevsystem.technologiesincludingmagneticlevitation,guidance,propul-sion,powersupply,andsoon.II.TECHNOLOGYASPECTSState-of-the-artMaglevtraintechnologiesareinvestigated.Fig.1illustratesthedifferencebetweentheconventionaltrainandtheMaglevtrain.Whiletheconventionaltrainusesarotarymotorforpropulsionanddependsontherailforguidanceandsupport,theMaglevtraingetspropulsionforcefromalinearmotorandutilizeselectromagnetsforguidanceandsupport.A.LevitationTypically,therearethreetypesoflevitationtechnologies:1)electromagneticsuspension;2)electrodynamicsuspension;and3)hybridelectromagneticsuspension.1)ElectromagneticSuspension(EMS):Thelevitationisac-complishedbasedonthemagneticattractionforcebetweenaguidewayandelectromagnetsasshowninFig.2.Thismethod