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

InvestigationonInsulationElectricalAgingMechanismofInverter-FedACTractionMotorsInverter-fedtractionmotorsusedinmotortrainunitareregardedastheresearchobjectforinsulationelectricagingmechanism,basedonre-searchproductionsofinsulationtechniqueofinverter-fedmotors.Highfrequencyequivalentcircuitmodelsofcableandstatorwindingareestablishedtosimulateover-voltageofmotorterminalsandunevenvoltagedistributionofwindings.Anovelhighfrequencyhighvoltagetestsystemhasbeendevelopedtocarryoutlifetimetestsoftractionmotorwindings.Changetendencyofdielectricloss,partialdischargeandthermallystimulatedcurrent(TSC)areusedtodeduceinsulationelectricbreakagemechanism.Highfrequencyequivalentcircuitmodelsofcableandstatorwindingareestablishedtosimulateovervoltageofmotorterminalsandunevenvoltagedistributionofwindings.Thesimulationresultsshowthattheover-voltageisthefunctionofrisetime,cablelengthandreflectionratioonmotorterminals.Criticallengthandcriticalrisetimeiscorrespondingonetoone.Theover-voltageisuptothemaximumvalueaslongasthecablelengthisreaterthanthecriticallengthAnovelhighfrequencyhighvoltagetestsystemhasbeendevelopedinplaceofinverterstocarryoutinsulationagingtest.PulsesquarewavesaregeneratedbyIGBTandareenlargedbyhighfrequencyandhighvoltagetransformersinthedevice.Themaximumvalueofhighfrequencyandhighvoltagesquarewavesisupto10kV.Theresultsoflifetestsofmotorwindingsindicatethatherelationshipofinsulationlifetimeandtheamplitudeofpulsesistheinversepowerlawmodel,therelationshipofinsulationlifetimeandthefrequencyofpulsesisexponentialmodelundercontinuouspulsescondition.Whenthetestambienttemperatureisbelow200，thetemperaturehaslittleinfluenceoninsulationlifetimeofmagnetwirewithcoronaresistantfilminsulation.Anovelpartialdischargedetectiondevicewasdevelopedbyimpulsecurrentsensor,handcomputer.Accordingtothecharacteristicsofthetestedsignals,anewalgorithmbasedonwavelet-envelopedetectiontechniqueisproposedtofilterEMIfromthetestsystemandspaceelectromagneticwaves.BecauseoftheinfluenceofverylargedV/dtandhighfrequencyplus-minusvoltagedischargesundercontinuoussquarewavesconditionaredifferentfromthoseundersinevoltagecondition.Ontheonehand,largerdV/dtleadstohigherbreakdownvoltage.Ontheotherhand,highfrequencyplus-minusvoltageconversioncausesalotofspacechargecumulatedontheinsulationsurface.Largebreakdownspacechargeresultindischargepulseswithshortrisetimeandlargemagnitude.Thenumber,magnitudeandpowerofpartialdischargesincreasewiththetemperature,frequencyandvoltagechangeofsquarewaves.Thenumberofpartialdischargebecomelargewiththefrequencyofsquarewaveincreaseintheunittime,butitbecomessmallinoneperiodofsquarewave.ContrasttestsarecarriedoutunderACand10kHzsquarewavepulseconditions.ThedifferencesbetweenACagingandsquarewavepulseagingarestudiedbasedonchangecurvesofdielectricloss,partialdischargepatternandTSC.ThesecurvesprovethatsquarewavepulsesbringmoredefectsthanACvoltagetotheinsulationmaterials.Underquarewavepulsecondition,thetwokeyfactorswhichtoinsulationagingaredischargeadspacecharge.Damageactionsofpartialdischargesandspacechargesareintensifiedwithvoltage,frequencyandtemperatureincreasing.Duetothedestructionofdischargesunderthesquarewavecondition,theweaknessesofinsulationstructurewillbreakdownrapidlyifpartialdischargesoccur.Dischargechannelcomesintobeingasaresultofthecooperationofpartialdischargesandspacecharges.Insulationsurfacesaredestroyedbypartialdischarges.Injectionanddraw-offofelectricchargesgeneratingbychargesresultinmolecularchainfractureinsideinsulationstructure.Subsequently,dischargechannelsareexpandedalongthebreakingpointintheinsulation.Finally,theprocessleadstoinsulationistheuseofpowersemiconductordeviceswillbetheroleofon-offfrequencytoanotherfrequencypowerconversionpowercontroldevices.Wearenowmainlyusedincross-frequencyconverter-direct-waytopay(VVVFinverterorvariablefrequencyvectorcontrol),beforetheadoptionofpower-frequencyACpowerintoDCpowerrectifierandthenconvertedtoDCpowersupplyfrequencyandvoltagecanbecontrolledACpowertosupplythemotor.Invertercircuitingeneralbytherectifier,intermediateDClink,inverterandcontroloffourparts.Partofthree-phasebridgerectifierisnotcontrolledrectifier,inverterpartofthree-phasebridgeinverterIGBTandPWMoutputwaveform,themiddleofDClinkforthefiltering,storageandbufferDCreactivepower.InverterSelection,Selectionconvertertodeterminethefollowing:Thepurposeoftheuseofvariablefrequency；constantvoltagecontrolorconstantcurrentcontrol.Invertertypeofload；suchasthevanepumporpumps,suchasvolume,withparticularattentiontotheperformanceoftheloadcurve,theperformancecurvedeterminesthewaysandmeansofapplication.Inverterandloadmatchingproblem；voltagematching；Inverterratedvoltageandloadinlinewiththeratedvoltage.Currentmatching；ordinarycentrifugalpump,ratedcurrentoftheinverterandthemotorratedcurrentline.Foraspecialdeep-waterpumps,etc.Iftheloadisnecessarytorefertotheelectricalperformanceparameterstodeterminethemaximumcurrentinvertercurrentand.Torquematching；thissituationintheconstanttorqueloadordecelerationdevicethatmayoccurfromtimetotime.Intheuseofhigh-speedmotordriveinverter,duetoanti-high-speedelectricmotorsmall,high-orderharmonicgenerationtoincreasevalueresultinginincreasedoutputcurrent.Thereforetheinverterforhigh-speedmotorselection,anditscapacitytobeslightlylargerthantheselectionofgeneralmotors.Ifyouwantalongcableconverterrunningatthistimetotakemeasurestocurbalongcableontheimpactofcouplingcapacitancetoavoidshortageofinverteroutput,soinsuchcircumstances,thefrequencyconvertertoenlargethecapacityofafileorintheinverteroutputinstalledreactoroutput.Forsomespecialapplications,suchashightemperature,highaltitude,atthistimewillcauselowercapacityinverter,invertercapacitytoenlargeablock.Internalhigh-powerinverteristheelectroniccomponents,extremelyvulnerabletotheeffectsoftemperature,productsaregenerallycalledfor055,buttheworkinordertoensuresafe,reliable,shouldbetakenintoaccounttheuseofroom,itisbestcontrolledat40under.Inthecontrolbox,theconvertershouldnormallybeinstalledintheupperbox,andstrictlycomplywiththeproductspecificationoftheinstallationrequirements,absolutelydoesnotalloweasyheatheatingelementsorcomponentsclosetothebottomoftheinstallationofinverter.II.Theambienttemperature.Hightemperatureandlargetemperaturechanges,theinverterinternalcondensationpronetothephenomenonofperformanceoftheinsulationwillgreatlyreduceandmayevenleadtoshort-circuitaccident.Whennecessary,theneedtoincreasethedesiccantintheboxandheater.Inwatertreatment,thegenerallyheavierthanwater,ifthetemperaturevariation,thentheproblemwouldbemoreprominent.III.Corrosivegases.Theuseoftheenvironmentiftheconcentrationofcorrosivegas,andnotonlythecorrosionofleadcomponents,suchasprintedcircuitboards,butalsoacceleratetheagingofplasticdevicestoreducetheinsulationperformance.IV.Vibrationandshock.Equippedwithinvertercontrolcabinetbythemechanicalvibrationandshockwillcausebadelectrical.Thermoelectric.Atthistime,apartfromimprovingthemechanicalstrengthofthecontrolcabinet,awayfromthevibrationsourceandtheimpactofthesourcebutalsotheuseofanti-seismicrubberpadfixedoutsideandinsidethecontrolcabinetofthetypeofelectromag