電力電子技術(shù)基礎(chǔ)(英文)-Cha1Devices課件

Chapter1

PowerDevicesapowerdevice~aswitch

SwitchingStates:

*onstate(static) Von-state=0ideallyCurrentratings–continuous,average,RMS,peak*offstate(static)

Ileakage=0ideallyoff-statevoltageratings-forwardandreverse

*commutationstate(dynamic) dv/dt,di/dt=

ideally

dv/dtrating(anequivalentcapacitorinoff-state,adisplacementcurrenti=Cdv/dt)

di/dtrating(ahotpointintheregionwherethefirstconductionoccurs)

Chapter1PowerDevicesapow1pswitch

SwitchEnergyLosses:

Wstatic =Won+Woff

=

on-timeion(t)von-state(t)dt

+

off-timeileakage(t)voff(t)dtWon---majorlossatlower-frequencyoperation

Wswitch---significantathigh-frequencyoperation

Wswitch=

turn-oni(t)v(t)dt

+

turn-offi(t)v(t)dt

Paverage=(Wstatic+Wswitch)/TPowerDevicespswitchSwitchEnergyLosses2APOWERSWITCHINGDEVICE

*permitscurrentflowinonedirectiononly *canwithstandaforwardvoltage(exceptdiodes)*canbeturnedonoroff

byarelativelysmallcontrollingcurrentorvoltageStudyfocuses:

(Diode,SCR,GTO,BJT,MOSFET,IGBT,IPM)

characteristics,ratherthanthephysics firingrequirements ratings comparisonsofthedevicesPowerDevicesAPOWERSWITCHINGDEVICEPower3PowerDevicesStructureandsymbolCharacteristics1-1.DiodePowerDevicesStructureandsym4PowerDevicesreverserecoverytimetrrTypicalturn-offconditionofadiode.FastRecoveryDiodetrrPowerDevicesreverserecovery51-2.Thyristor

(SCR)PowerDevicesStructureandsymbolCharacteristicswithnogatecurrent

AnodeCathodeCharacteristicswithgatecurrent

+AnodeIaIcIgIb1Ib2Gate-CathodePNNPIg

Ib1

Ia,IcIb2

Positivefeedback

1-2.Thyristor(SCR)PowerDe6Firingrequirements

a.Gate-cathode—poorP-Njunction

withinagivenproductionbatch Igmin<Ig<Igmax Vgmin<Vg<Vgmax IgVg<Pgmax

b.pulsefiringcurrent

withafastriseandasufficientlength

PowerDevicesFiringrequirementsPowerDevic71-3.GTO(GateTurn-offThyristor)(a)Conventionalthyristorsymbol.(b)ConventionalthyristorP-N-P-Nstructure.(c)Gateturn-offthyristorsymbol.(d)Gateturn-offthyristorstructure.PowerDevicesAreversevoltagewiththecathodepositivewillbreakdowntheanodejunctionatalowlevel.1-3.GTO(GateTurn-offThyr8Turn-onconditions:

similartothethyristorbutthelatchingcurrenthigher&thegatecurrentcontinuous

a.turn-onhighlevelgatecurrentforalongertime b.afterturn-onalowlevelofgatecurrent tominimizetheanode-cathodevoltageTurn-offconditions:

byapplyinganegativevoltageacrossthegate-cathode

a.turn-offvoltagehighenoughbutlessthanthebreakdown b.areversegatecurrentwithapeakvalueof1/5~1/3oftheanodecurrentestablishedinlessthan1μsPowerDevicesTurn-onconditions:PowerDevic91-4.PowerTransistor(GTR/BJT)PowerDevicesN-P-Ntransistor.(a)Structure.(b)Symbol.P-N-Ptransistor.(a)Structure.(b)Symbol.1-4.PowerTransistor(GTR/10PowerDevicesCommonemittercharacteristicforN-P-Ntransistor.PowerDevicesCommonemitterch11Profileofthebasetothecollectorcurrent

—basecurrentjustsufficienttomaintainsaturation

a.atturn-on,thebasecurrent highenoughtogiveafastturn-on b.anychangeinthecollectorcurrent matchedbyachangeinthebasecurrent c.atturn-off,thebasecurrent reducedataratethecollectorcurrentcanfollowPowerDevices*Secondarybreakdown*HighswitchinglossProfileofthebasetothecol122-5.PowerMOSFETPowerDevices(a)Symbol.(b)Simplifiedcross-sectionalstructure.2-5.PowerMOSFETPowerDevic13PowerDevicesElectricalcircuit.(b)Outputcharacteristic.PowerMOSFET(a)(b)PowerDevicesElectricalcircui14PowerMOSFET*Veryfastswitching

voltagecontrolledwithoutanystoredcharge*Lowpowerrating

narrowinducedconductingchannel*Highconductionloss

highconstantresistance*Positivetemperaturecoefficientforresistance

simpleparallelingofdevicesPowerDevicesPowerMOSFETPowerDevices151-6.IGBT(InsulatedGateBipolarTransistor)PowerDevices(a)Simplifiedcross-section.(b)Equivalentelectriccircuit.(c)Symbol.

Thecollector-emittercharacteristicsaresimilartothoseofthepowertransistorbutthecontrolfeaturesarethoseoftheMOSFET.Currenttailing1-6.IGBT(InsulatedGateB16

Ideallyasacontrolledswitchthedevicewouldhave:

1.Controlledturn-onand–off

MOSFET、IGBT、BJT、GTO、SCR

2.Unlimitedvoltageandcurrentratings

SCR、GTO、IGBT、BJT、MOSFET

3.Instantturn-onand–offtimes

MOSFET、IGBT、BJT、GTO、SCR

4.Zeroconductionloss

SCR、GTO、BJT、IGBT、MOSFET

5.Zerogatefiringpowerrequirement

MOSFET、IGBT、BJT、SCR、GTO

6.Lowcost

SCR、GTO、BJT、IGBT、MOSFETPowerDevices2-7.DeviceComparisons

Ideallyasacontrolledswit17PowerDevices

Researchanddevelopmentworkisconstantlybeingundertakentoimprovethepresentdevicesandtodevelopnewdevicesclosertotheidealelectronicswitches.

MCT(MOS-controlledthyristor)isoneofthenewdevicesunderdevelopmentwhichhastheanode-cathodecharacteristicssimilartothoseofthyristorsbutthecontrolfeaturessimilartothoseoftheMOSFET.

IPM(IntelligentPowerModule)isanotherkindofnewdeviceswhichiscurrentlycommerciallyavailable.Itusuallyintegratesapowerdevice,say,anIGBT,plusitsgatedrivingcircuitandsomeprotectionlogicssuchasshortcircuit,overcurrent,overtemperatureandundervoltage.PowerDevices Researcha18RealLoadsandSources

Appendix1-1LOADSnotasimpleresistancewithfewexceptions;withwireshavinginductanceandcapacitance;oftencontainingelectricalsources,interfacefilters,etc.;manynon-linear.Twobroadcategories:

quasi-steadyloads

&transientloadsAcommonfeature:

seriesinductanceexhibitingcurrentsourcebehavioronshorttimescaleCriticalinductance

–thelowestvalueofloadinductanceforwhichiload>0atalltimes.RealLoadsandSources 19Appendix1-1Specialtypesofwirestoreduceinternalself-inductance.Appendix1-1Specialtypesofw20Appendix1-1Circuitmodelforabatteryoncharge.Inductionmotorcircuitmodel.Appendix1-1Circuitmodelfor21SORCESAnidealvoltagesourceprovidesadefinedv(t)valueatanycurrent.Itdisplayszeroimpedancetocurrentflow.Anidealcurrentsourcemaintainsadefinedi(t)valueatanyvoltage.Itdisplaysinfiniteimpedancetoexternalvoltage.Idealandrealvoltagesourcescompared