电气工程及其自动化专业英语》课程论文

重庆邮电大学移通学院《电气工程及其自动化专业英语》课程论文年级专业姓名学号Insulated-gateBipolarTransistorBasics【Abstract】ModernPowerElectronicsmakesgeneroususeofMOSFETsandIGBTsinmostapplications,and,ifthepresenttrendisanyindication,thefuturewillseemoreandmoreapplicationsmakinguseofMOSFETsandIGBTs.Forhigh-voltageorhigh-powerapplications,itmaybenecessarytorealizealogicalswitchbyconnectingsmallerunitsinparallelandseriestoachievehighavailability,high-frequencyoperation,andlowcostduetobuild-inredundancy,reduceddynamiclosses,andmodularuseofstandardizedunits,respectively.IGBTsareveryconvenienttorealizesuchunits,becauseofquasi-linearcontrollabilityviaagateterminal.ThisthesisinvestigatescontrolmethodologiesforpowerMOSsemiconductorswitcheswithfocusoncombinedparallelandseriesconnectionofIGBT/diodemodules.ItisproposedtoprovideeachIGBTwithprimarylocalcontroltomonitorandadjusttheIGBT'sstaticanddynamicbehavior.Secondary(global)controlsynchronizestheoperationofmultipleIGBTs.Agloballysynchronousclockcanalsobederivedlocally.Thismakesitpossibletouselow-costlow-bandwidthdatalinksbetweenseries-connectedunits.Thereby,aflexiblemaster-slaveapproachcanavoidtheneedofdedicatedglobalcontrol.Thatis,theentiresystemismanageablebythelocalgatedrivecircuitry.Keywords:IGBTapplicationsMOSFETcharacteristicIntroduction:TheIGBTisasemiconductordevicewithfouralternatinglayers(P-N-P-N)thatarecontrolledbyametal-oxide-semiconductor(MOS)gatestructurewithoutregenerativeaction.ThismodeofoperationwasfirstproposedbyYamagamiinhisJapanesepatentS47-21739,whichwasfiledin1968.Thismodeofoperationwasfirstexperimentallyreportedinthelateralfourlayerdevice(SCR)byB.W.ScharfandJ.D.Plummerin1978.[1]Thismodeofoperationwasalsoexperimentallydiscoveredinverticaldevicein1979byB.J.Baliga.[2]Thedevicestructurewasreferredtoasa‘V-grooveMOSFETdevicewiththedrainregionreplacedbyap-typeAnodeRegion’inthispaperandsubsequentlyas'theinsulated-gaterectifier'(IGR),theinsulated-gatetransistor(IGT),theconductivity-modulatedfield-effecttransistor(COMFET)andbipolar-modeMOSFET.[3]IGBTFundamentals:TheInsulatedGateBipolarTransistor(IGBT)isaminority-carrierdevicewithhighinputimpedanceandlargebipolarcurrent-carryingcapability.ManydesignersviewIGBTasadevicewithMOSinputcharacteristicsandbipolaroutputcharacteristicthatisavoltage-controlledbipolardevice.TomakeuseoftheadvantagesofbothPowerMOSFETandBJT,theIGBThasbeenintroduced.It’safunctionalintegrationofPowerMOSFETandBJTdevicesinmonolithicform.Itcombinesthebestattributesofbothtoachieveoptimaldevicecharacteristics.1.ThemainadvantagesofIGBToveraPowerMOSFETandaBJTare:1.Ithasaverylowon-statevoltagedropduetoconductivitymodulationandhassuperioron-statecurrentdensity.Sosmallerchipsizeispossibleandthecostcanbereduced.2.LowdrivingpowerandasimpledrivecircuitduetotheinputMOSgatestructure.Itcanbeeasilycontrolledascomparedtocurrentcontrolleddevices(thyristor,BJT)inhighvoltageandhighcurrentapplications.3.WideSOA.Ithassuperiorcurrentconductioncapabilitycomparedwiththebipolartransistor.Italsohasexcellentforwardandreverseblockingcapabilities.2.Themaindrawbacksare:1.SwitchingspeedisinferiortothatofaPowerMOSFETandsuperiortothatofaBJT.Thecollectorcurrenttailingduetotheminoritycarriercausestheturn-offspeedtobeslow.2.ThereisapossibilityoflatchupduetotheinternalPNPNthyristorstructure.TheIGBTissuitableforscalinguptheblockingvoltagecapability.IncaseofPowerMOSFET,theon-resistanceincreasessharplywiththebreakdownvoltageduetoanincreaseintheresistivelyandthicknessofthedriftregionrequiredtosupportthehighoperatingvoltage.BasicStructure:AnIGBTcellisconstructedsimilarlytoan-channelverticalconstructionpowerMOSFETexcepttheN+drainisreplacedwithaP+collectorlayer,thusformingaverticalPNPbipolarjunctiontransistor.ThisadditionalP+regioncreatesacascadeconnectionofaPNPbipolarjunctiontransistorwiththesurfacen-channelMOSFET.SomeIGBTs,manufacturedwithouttheN+bufferlayer,arecallednon-punchthroughIGBTswhereasthosewiththislayerarecalledpunch-throughIGBTs.Thepresenceofthisbufferlayercansignificantlyimprovetheperformanceofthedeviceifthedopinglevelandthicknessofthislayerarechosenappropriately.Despitephysicalsimilarities,theoperationofanIGBTisclosertothatofapowerBJTthanapowerMOSFET.ItisduetotheP+drainlayer(injectinglayer)whichisresponsiblefortheminoritycarrierinjectionintotheN-driftregionandtheresultingconductivitymodulation.IGBTCharacteristics：BecausetheIGBTisavoltage-controlleddevice,itonlyrequiresasmallvoltageontheGatetomaintainconductionthroughthedeviceunlikeBJT’swhichrequirethattheBasecurrentiscontinuouslysuppliedinasufficientenoughquantitytomaintainsaturation.AlsotheIGBTisaunidirectionaldevice,meaningitcanonlyswitchcurrentinthe“forwarddirection”,thatisfromCollectortoEmitterunlikeMOSFET’swhichhavebi-directionalcurrentswitchingcapabilities(controlledintheforwarddirectionanduncontrolledinthereversedirection).TheprincipalofoperationandGatedrivecircuitsfortheinsulatedgatebipolartransistorareverysimilartothatoftheN-channelpowerMOSFET.Thebasicdifferenceisthattheresistanceofferedbythemainconductingchannelwhencurrentflowsthroughthedeviceinits