外文翻译--变频调速交流牵引电机绝缘电老化机理的研究.DOC -- 5 元

InvestigationonInsulationElectricalAgingMechanismofInverterFedACTractionMotorsInverterfedtractionmotorsusedinmotortrainunitareregardedastheresearchobjectforinsulationelectricagingmechanism,basedonresearchproductionsofinsulationtechniqueofinverterfedmotors.Highfrequencyequivalentcircuitmodelsofcableandstatorwindingareestablishedtosimulateovervoltageofmotorterminalsandunevenvoltagedistributionofwindings.Anovelhighfrequencyhighvoltagetestsystemhasbeendevelopedtocarryoutlifetimetestsoftractionmotorwindings.Changetendencyofdielectricloss,partialdischargeandthermallystimulatedcurrentTSCareusedtodeduceinsulationelectricbreakagemechanism.Highfrequencyequivalentcircuitmodelsofcableandstatorwindingareestablishedtosimulateovervoltageofmotorterminalsandunevenvoltagedistributionofwindings.Thesimulationresultsshowthattheovervoltageisthefunctionofrisetime,cablelengthandreflectionratioonmotorterminals.Criticallengthandcriticalrisetimeiscorrespondingonetoone.TheovervoltageisuptothemaximumvalueaslongasthecablelengthisreaterthanthecriticallengthAnovelhighfrequencyhighvoltagetestsystemhasbeendevelopedinplaceofinverterstocarryoutinsulationagingtest.PulsesquarewavesaregeneratedbyIGBTandareenlargedbyhighfrequencyandhighvoltagetransformersinthedevice.Themaximumvalueofhighfrequencyandhighvoltagesquarewavesisupto10kV.Theresultsoflifetestsofmotorwindingsindicatethatherelationshipofinsulationlifetimeandtheamplitudeofpulsesistheinversepowerlawmodel,therelationshipofinsulationlifetimeandthefrequencyofpulsesisexponentialmodelundercontinuouspulsescondition.Whenthetestambienttemperatureisbelow200℃，thetemperaturehaslittleinfluenceoninsulationlifetimeofmagnetwirewithcoronaresistantfilminsulation.Anovelpartialdischargedetectiondevicewasdevelopedbyimpulsecurrentsensor,handcomputer.Accordingtothecharacteristicsofthetestedsignals,anewalgorithmbasedonwaveletenvelopedetectiontechniqueisproposedtofilterEMIfromthetestsystemandspaceelectromagneticwaves.BecauseoftheinfluenceofverylargedV/dtandhighfrequencyplusminusvoltagedischargesundercontinuoussquarewavesconditionaredifferentfromthoseundersinevoltagecondition.Ontheonehand,largerdV/dtleadstohigherbreakdownvoltage.Ontheotherhand,highfrequencyplusminusvoltageconversioncausesalotofspacechargecumulatedontheinsulationsurface.Largebreakdownspacechargeresultindischargepulseswithshortrisetimeandlargemagnitude.Thenumber,magnitudeandpowerofpartialdischargesincreasewiththetemperature,frequencyandvoltagechangeofsquarewaves.Thenumberofpartialdischargebecomelargewiththefrequencyofsquarewaveincreaseintheunittime,butitbecomessmallinoneperiodofsquarewave.ContrasttestsarecarriedoutunderACand10kHzsquarewavepulseconditions.ThedifferencesbetweenACagingandsquarewavepulseagingarestudiedbasedonchangecurvesofdielectricloss,partialdischargepatternandTSC.ThesecurvesprovethatsquarewavepulsesbringmoredefectsthanACvoltagetotheinsulationmaterials.Underquarewavepulsecondition,thetwokeyfactorswhichtoinsulationagingaredischargeadspacecharge.Damageactionsofpartialdischargesandspacechargesareintensifiedwithvoltage,frequencyandtemperatureincreasing.Duetothedestructionofdischargesunderthesquarewavecondition,theweaknessesofinsulationstructurewillbreakdownrapidlyifpartialdischargesoccur.Dischargechannelcomesintobeingasaresultofthecooperationofpartialdischargesandspacecharges.Insulationsurfacesaredestroyedbypartialdischarges.Injectionanddrawoffofelectricchargesgeneratingbychargesresultinmolecularchainfractureinsideinsulationstructure.Subsequently,dischargechannelsareexpandedalongthebreakingpointintheinsulation.Finally,theprocessleadstoinsulationistheuseofpowersemiconductordeviceswillbetheroleofonofffrequencytoanotherfrequencypowerconversionpowercontroldevices.WearenowmainlyusedincrossfrequencyconverterdirectwaytopayVVVFinverterorvariablefrequencyvectorcontrol,beforetheadoptionofpowerfrequencyACpowerintoDCpowerrectifierandthenconvertedtoDCpowersupplyfrequencyandvoltagecanbecontrolledACpowertosupplythemotor.Invertercircuitingeneralbytherectifier,intermediateDClink,inverterandcontroloffourparts.Partofthreephasebridgerectifierisnotcontrolledrectifier,inverterpartofthreephasebridgeinverterIGBTandPWMoutputwaveform,themiddleofDClinkforthefiltering,storageandbufferDCreactivepower.InverterSelection,SelectionconvertertodeterminethefollowingThepurposeoftheuseofvariablefrequencyconstantvoltagecontrolorconstantcurrentcontrol.Invertertypeofloadsuchasthevanepumporpumps,suchasvolume,withparticularattentiontotheperformanceoftheloadcurve,theperformancecurvedeterminesthewaysandmeansofapplication.InverterandloadmatchingproblemvoltagematchingInverterratedvoltageandloadinlinewiththeratedvoltage.Currentmatchingordinarycentrifugalpump,ratedcurrentoftheinverterandthemotorratedcurrentline.Foraspecialdeepwaterpumps,etc.Iftheloadisnecessarytorefertotheelectricalperformanceparameterstodeterminethemaximumcurrentinvertercurrentand.Torquematchingthissituationintheconstanttorqueloadordecelerationdevicethatmayoccurfromtimetotime.Intheuseofhighspeedmotordriveinverter,duetoantihighspeedelectricmotorsmall,highorderharmonicgenerationtoincreasevalueresultinginincreasedoutputcurrent.Thereforetheinverterforhighspeedmotorselection,anditscapacitytobeslightlylargerthantheselectionofgeneralmotors.Ifyouwantalongcableconverterrunningatthistimetotakemeasurestocurbalongcableontheimpactofcouplingcapacitancetoavoidshortageofinverteroutput,soinsuchcircumstances,thefrequencyconvertertoenlargethecapacityofafileorintheinverteroutputinstalledreactoroutput.Forsomespecialapplications,suchashightemperature,highaltitude,atthistimewillcauselowercapacityinverter,invertercapacitytoenlargeablock.Internalhighpowerinverteristheelectroniccomponents,extremelyvulnerabletotheeffectsoftemperature,productsaregenerallycalledfor055℃,buttheworkinordertoensuresafe,reliable,shouldbetakenintoaccounttheuseofroom,itisbestcontrolledat40℃under.Inthecontrolbox,theconvertershouldnormallybeinstalledintheupperbox,andstrictlycomplywiththeproductspecificationoftheinstallationrequirements,absolutelydoesnotalloweasyheatheatingelementsorcomponentsclosetothebottomoftheinstallationofinverter.II.Theambienttemperature.Hightemperatureandlargetemperaturechanges,theinverterinternalcondensationpronetothephenomenonofperformanceoftheinsulationwillgreatlyreduceandmayevenleadtoshortcircuitaccident.Whennecessary,theneedtoincreasethedesiccantintheboxandheater.Inwatertreatment,thegenerallyheavierthanwater,ifthetemperaturevariation,thentheproblemwouldbemoreprominent.III.Corrosivegases.Theuseoftheenvironmentiftheconcentrationofcorrosivegas,andnotonlythecorrosionofleadcomponents,suchasprintedcircuitboards,butalsoacceleratetheagingofplasticdevicestoreducetheinsulationperformance.IV.Vibrationandshock.Equippedwithinvertercontrolcabinetbythemechanicalvibrationandshockwillcausebadelectrical.Thermoelectric.Atthistime,apartfromimprovingthemechanicalstrengthofthecontrolcabinet,awayfromthevibrationsourceandtheimpactofthesourcebutalsotheuseofantiseismicrubberpadfixedoutsideandinsidethecontrolcabinetofthetypeofelectromagneticswitchcomponentsgeneratedvibration.Equipmentforsometime,shouldcarryoutinspectionandmaintenance.V.electromagneticinterference.Inverterintheworkofrectificationandfrequencyasaresult,hascreatedalotofthesurroundingelectromagneticinterference,thesehighfrequencyelectromagneticwavesinthevicinityoftheinstrument,apparatus,acertaindegreeofinterference.Accordingly,instrumentationandelectronicsystemsinsideshouldbeoptionalmetalcase,shieldingoftheinstrumenttransducerinterference.Allthecomponentsshouldbegroundedandreliable,inaddition,allelectricalcomponents,apparatusandinstrumentsshouldbeusedtoconnectbetweenthecontrolcableshieldingandshieldshouldbegrounded.Electromagneticinterference,ifnothandledproperly,oftentheentiresystemwillnotwork,resultinginfailureofordamagetothecontrolunit.