电力电子技术.docx
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电力电子技术.docx
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电力电子技术
Chapter1
PowerElectronicDevices
(PartI)
Outline
1.1Anintroductoryoverviewofpowerelectronicdevices
1.2Uncontrolleddevice一powerdiode
1.3Half-controlleddevice一thyristor
1.4Typicalfully-controlleddevices
1.5Othernewpowerelectronicdevices
1.6Drivecircuitforpowerelectronicdevices
1.7Protectionofpowerelectronicdevices
1.8Seriesandparallelconnectionsofpowerelectronicdevices
1.1Anintroductoryoverviewofpowerelectronicdevices
*Theconceptandfeatures
*Configurationofsystemsusingpowerelectronicdevices
*Classifications
*Majortopics
Theconceptofpowerelectronicdevices
∙Powerelectronicdevices:
aretheelectronicdevicesthatcanbedirectlyusedinthepowerprocessingcircuitstoconvertorcontrolelectricpower.
InbroadsenseVacuumdevices:
Mercuryarc
rectifierthyratron,etc..seldom
powerelectronicdevicesinusetoday
Semiconductordevices:
majorpowerelectronicdevices
∙Veryoften:
Powerelectronicdevices=Powersemiconductordevices
Majormaterialusedinpowersemiconductordevices--Silicon
Featuresofpowerelectronicdevices
∙Theelectronicpowerthatpowerelectronicdevicedealswithisusuallymuchlargerthanthattheinformationelectronicdevicedoes.
∙Usuallyworkinginswitchingstatestoreducepowerlosses
On-state----Voltageacrossthedeviceis0----p=vi=0
v=0
Off-state----Currentthroughthedeviceis0---p=vi=0
i=0
Featuresofpowerelectronicdevices
∙Needtobecontrolledbyinformationelectroniccircuits.Veryoften,drivecircuitsarenecessarytointerfacebetweeninformationcircuitsandpowercircuits.
Dissipatedpowerlossusuallylargerthaninformationelectronicdevices一specialpackagingandheatsinkarenecessary.
Powerlossesonpowersemiconductordevices
Totalpowerlosson
powersemiconductor=conductionloss十turn-offloss十off-stateloss十turn-onloss(on-stateloss)
Switchingloss
Configurationofsystemsusingpowerelectronicdevices
Powercircuit(powerstage,maincircuit)Configurationofsystemsusingpowerelectronicdevices
Terminalsofapowerelectronicdevice
∙Controlsignalfromdrivecircuitmustbeconnectedbetweenthecontrolterminalandafixedpowercircuitterminal(thereforecalledcommonterminal).
Aclassificationofpowerelectronicdevices
Uncontrolleddevice:
diode(Uncontrollabledevice)
hasonlytwoterminalsandcannotbecontrolledbycontrolsignal.Theonandoffstatesofthedevicearedeterminedbythepowercircuit.
Half-controlleddevice:
thyristor
(Half-controllabledevice)
isturned-onbyacontrolsignalandturned-offbythepowercircuit
Fully-controlleddevice:
PowerMOSFET,IGBT,GTO,IGCT
(Fully-controllabledevice)
Theonandoffstatesofthedevicearecontrolledbycontrolsignals.
Otherclassifications
powerelectronicCurrent-driven(current-controlled)devices
devicesVoltage-driven(voltage-controlled)devices
(Field-controlleddevices)
powerelectronicPulse-triggereddevices
devicesLevel-sensitive(level-triggered)devices
powerelectronicUnipolardevices(Majoritycarrierdevices)
devicesBipolardevices(Minoritycarrierdevices)
Compositedevices
Majortopicsforeachdevice
∙Appearance,structure,andsymbol
∙Physicsofoperation
∙CharacteristicsStaticcharacteristics
Switchingcharacteristics
∙Specification
∙Specialissues
∙Devicesofthesamefamily
Passivecomponentsinpowerelectroniccircuit
∙Transformer,inductor,capacitorandresistor:
thesearepassivecomponentsinapowerelectroniccircuitsincetheycannotbecontrolledbycontrolsignalandtheircharacteristicsareusuallyconstantandlinear.
∙Therequirementsforthesepassivecomponentsbypowerelectroniccircuitscouldbeverydifferentfromthosebyordinarycircuits.
UncontrolleddevicePowerdiode
Appearance
PNjunction
Directionofinnerelectricfield
∙Semiconductor(ColumnIVelement,Si)
∙Electronsandholes.
∙Puresemiconductor(intrinsicsemiconductor)
∙Doping,p-typesemiconductor.N-typesemiconductor
∙PNjunction
∙Equilibriumofdiffusionanddrift
PNjunctionwithvoltageappliedintheforwarddirection
Constructionofapracticalpowerdiode
Featuresdifferentfromlow-power(informationelectronic)diodes
一Largersize
--Verticallyorientedstructure
一n-driftregion(p-i-ndiode)
一Conductivitymodulation
Forward-biasedpowerdiode
Reverse-biasedpowerdiode
∙Breakdown
一Avalanchebreakdown
一Thermalbreakdown
Junctioncapacitor
∙Thepositiveandnegativechargeinthedepletionregionisvariablewiththechangingofexternalvoltage.
——JunctioncapacitorCj.
PotentialbarriercapacitorCb
JunctioncapacitorCj——
DiffusioncapacitorCd
∙Junctioncapacitorinfluencestheswitchingcharacteristicsofpowerdiode.
Staticcharacteristicsofpowerdiode
Switching(dynamic)characteristicsofpowerdiode
∙Reverse-recoveryprocess:
∙Reverse-recoverytime,reverse-recoverycharge,reverse-recoverypeakcurrent.
Switching(dynamic)characteristicsofpowerdiode
Turn-ontransient
Forwardrecoveryprocess:
forward-recoverytime
Specificationsofpowerdiode
∙AveragerectifiedforwardcurrentIt(av)
∙ForwardvoltageUf
∙PeakrepetitivereversevoltageUrrm
∙MaximumjunctiontemperatureTjm
∙Reverse-recoverytimetrr
Typesofpowerdiodes
∙Generalpurposediode(rectifierdiode):
standardrecovery
∙Fastrecoverydiode
Reverserecoverytimeandchargespecified.trrisusually
lessthan1us,formanylessthan100nsultra-fast
recoverydiode.
*Schottkydiode(Schottkybarrierdiode-SBD)
--Amajoritycarrierdevice
一Essentiallynorecoveredcharge,andlowerforwardvoltage.一Restrictedtolowvoltage(lessthan200V)
Examplesofcommercialpowerdiodes
Historyandapplicationsofpowerdiode
∙Appliedinindustriesstarting1950s
∙Stillin-usetoday.Usuallyworkingwithcontrolleddevicesasnecessarycomponents
∙Inmanycircumstancesfastrecoverydiodesorschottkydiodeshavetobeusedinsteadofgeneralpurposediodes.
1.3Half-controlleddevice—Thyristor
History
∙Anothername:
SCR—siliconcontrolledrectifier
∙ThyristorOpenedthepowerelectronicsera
一1956,invention,BellLaboratories
一1957,developmentofthe1stproduct,GE
一1958,1stcommercializedproduct,GE
一Thyristorreplacedvacuumdevicesinalmosteverypowerprocessingarea.
∙Stillinuseinhighpowersituation.Thyristortillhasthehighestpower-handlingcapability.
Appearanceandsymbolofthyristor
AppearanceSymbol
Structureandequivalentcircuitofthyristor
StrutureEquivalentcircuit
Physicsofthyristoroperation
∙
Equivalentcircuit:
Apnp
∙transistorandannpntransistornterconnectedtogether
∙Positivefeedback
∙Trigger
∙Cannotbeturnedoffbycontrolsignal
∙Half-controllable
Quantitativedescriptionofthyristoroperation
Othermethodstotriggerthyristoron
∙Highvoltageacrossanodeandcathode—avalanchebreakdown
∙Highrisingrateofanodevoltagte—du/dttoohigh
∙Highjunctiontemperature
∙
Lightactivation
Staticcharacteristicsofthyris
Switchingcharacteristicsofthyristor
Specificationsofthyristor
PeakrepetitiveforwardblockingvoltageUDRM
PeakrepetitivereverseblockingvoltageURRm
Peakon-statevoltageUTm
Averageon-statecurrentIT(AV)
HoldingcurrentIh
LatchingupcurrentIL
PeakforwardsurgecurrentItsm
du/dtdi/dt
Thefamilyofthyristors
1.4Typicalfully-controlleddevices
1.4.1Gate-turn-offthyristor—GTO
1.4.2Gianttransistor—GTR
1.4.3Powermetal-oxide-semiconductorfieldeffecttransistor—PowerMOSFET
1.4.4Insulated-gatebipolartransistor—IGBT
Features
一ICfabricationtechnology,fully-controllable,highfrequency
Applications
一Begintobeusedinlargeamountin1980s
一GTRisobsoleteandGTOisalsoseldomusedtoday.
一IGBTandpowerMOSFETarethetwomajorpowersemiconductordevicesnowadays.
1.4.1Gate-turn-offthyristor—GTO
Majordifferencefromconventionalthyristor:
Thegateandcathodestructuresarehighlyinterdigitated,withvarioustypesofgeometricformsbeingusedtolayoutthegatesandcathodes.
PhysicsofGTOoperation
CharacteristicsofGTO
Staticcharacteristic
一Identicaltoconventionalthyristorintheforwarddirection一Ratherlowbreakdownvoltage(20-30V)
Switchingcharacteristic
SpecificationsofGTO
MostGTOspecificationshavethesamemeaningsasthoseofconventionalthyristor.
Specificationsdifferentfromthyristor’s
一MaximumcontrollableanodecurrentIATO
一Currentturn-offgainboff
一Turn-ontimeton
一Turn-offtimetoff
1.4.2GiantTransistor—GTR
StructuresofGTRdifferentfromitsinformation-processingcounterpart
PhysicsofGTRoperation
StaticcharacteristicsofGTR
SwitchingcharacteristicsofGTR
Safeoperatingarea(SOA)ofGTR
PhysicsofMOSFEToperation
SpecificationsofpowerMOSFET
Drain-sourcebreakdownvoltageUds
ContinuousdraincurrentId
PeakpulseddraincurrentIdm
On(On-state)resistanceRDs(on)
Inter-terminalcapacitances
一ShortcircuitinputcapacitanceCiss=CGS十CGD
一ReversetransfercapacitanceCrss=CGD
一Shortcircuitoutput
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