Simulink仿真演示外文翻译.docx
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Simulink仿真演示外文翻译.docx
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Simulink仿真演示外文翻译
英文原文
SimulinkDemos
Simulinkisatoolformodeling,analyzing,andsimulatingphysicalandmathematicalsystems,includingthosewithnonlinearelementsandthosethatmakeuseofcontinuousanddiscretetime.
AsanextensionofMATLAB,SimulinkaddsmanyfeaturesspecifictodynamicsystemswhileretainingallofgeneralpurposefunctionalityofMATLAB.
RundemosforotherSimulinkproductsyouhaveinstalled.Trythesedemostosee
whichSimulinkproductsmightbeappropriatefortheworkyoudo.NotethatthisisacomprehensivelistofSimulinkproducts.YourparticularinstallationofMathWorks
IntheContentspane,foreachSimulinkproduct,seedocumentationExamplestoview
moresamplecodeyoucanrunorcopy.
Three-phaseThree-levelPWMConverter(discrete)
Thisdemonstrationillustratessimulationofa3-phase,3-levelinverterandDiscrete
3-phasePWMGenerator.ItalsodemonstratesharmonicanalysisofPWMwaveforms
usingthePowergui/FFTtool.
CircuitDescriptionThesystemconsistsoftwothree-phasethree-levelPWMvoltagesourceconverters
connectedintwinconfiguration。
TheinverterfeedsanACload(1kW,500var60Hz208Vrms)throughathree-phasetransformer.
Harmonicfilteringisperformedbythetransformerleakageinductance(8%)andload
capacitance(500var).EachofthetwoinvertersusestheThree-LevelBridgeblock
wherethespecifiedpowerelectronicdevicesareIGBT/Diodearmconsists
of4
IGBTs,4antiparalleldiodes,and2neutralclampinginverteris
controlledinopenloop.PulsesaregeneratedbytheDiscrete3-PhaseDiscretePWM
Generatorblock.ThisblockisavailableintheExtras/DiscreteControlBlockslibrary.
ThisPWMgeneratorormodulatorcanbeusedtogeneratepulsesfor3-phase,2-level,
or3-levelconvertersusingonebridgeortwobridges(twinconfiguration).Inthis
demo,thePWMmodulatorgeneratestwosetsof12pulses(1setperinverter)atP1
andP2outputs.Openthe'Discrete3-phasePWMGenerator'menu.Noticethatthe
generatorcanoperateeitherinsynchronizedorun-synchronizedmode.
Whenoperatinginsynchronizedmode,thecarriertriangularsignalissynchronizedon
aPLLreferenceangleconnectedtoinput'wt'.Insynchronizedmode,thecarrierchoppingfrequencyisspecifiedbytheswitchingratioasamultipleoftheoutputsinusoidal0.85pumodulatingsignalsareprovidedbythe'Discrete3-phaseProgrammableSource'toobtainamodulationindexof0.85.Thecarriersignalsaresynchronizedonthemodulatingsignals.inthePWMGeneratorblock,youcaninsteadselect'Un-synchronized'and'Internalgenerationofmodulatingsignals'.Insuchacasethemagnitude(modulationindex),frequencyandphaseangleoftheoutputsignalsarespecified.directlyinsidethePWMGeneratorblockthisexampletheDCbusvoltageis400V(+/-200V),choppingfrequencyis1080Hz(18*60Hz),magnitudeofthethreemodulatingsignalsis0.85(correspondingtoamodulationindexm=0.85)andthefrequencyofthethreegeneratedsignalsis60ordertoallowfurthersignalprocessing,signalsdisplayedontheScopeblock(sampledatsimulationsamplingrateof3240samples/cycle)arestoredinavariablenamed'psb3phPWM3level_str'(structureswithtime).
Demonstration
RunthesimulationandobservethefollowingthreewaveformsontheScopeblock:
Phase-neutralvoltageVan_inv1generatedbyinverter1(trace1),phaseAvoltageVaa_invertergeneratedbythetwininverter(trace2)andphase-phaseloadvoltageVab_load(trace3).TheVan_inv1waveformclearydemonstratesthethreelevels:
+200V,0V,and-200thesimulationiscompleted,openthePowerguiandselect'FFTAnalysis'todisplaythe0-5000Hzfrequencyspectrumofsignalssavedinthe'psb3phPWM3level_str'structure.TheFFTwillbeperformedona2-cyclewindowstartingatt=0.1-2/60(last2cyclesofrecording).Selelecttheinputlabeled'Vaa_inverter'.ClickonDisplayandobservethefrequencyspectrumoflast2fundamentalcomponentofVaa_inverterandTHDforthe0-5000HzfrequencyrangearedisplayedabovethespectrumoftheforwardvoltagedropsintheIGBTs(Vf=1V)anddiodes(Vfd=1V),themagnitudeofthefundamentalvoltageoftheinverter(335V)isslightlylowerthanthetheoreticalvalue(340Vform=0.85).Asexpectedforatwininverter,firstharmonicsoccuraroundmultiplesofdoubleofcarrierfrequency(n*2*1080Hz+-k*60Hz).Thesamecircuitusingtwo-levelinvertersintwinconfigurationisavailableinthepsb3phPWM.mdldemonstrationthisdemoandcomparetheharmoniccontentsinthe2-leveland3-levelinvertervoltageforthesamemodulationindex(m=0.85).Harmonicsoccuratthesamefrequenciesbuttheirmagnitudeisapproximatelytwotimeslowerfora3-levelinverter.
DC/DCandDC/ACPWMConverters(discrete)
ThisdemonstrationillustratesuseoftheUniversalBridgeandDiscretePWMPulseGeneratorblocks.ItalsodemonstratesharmonicanalysisofPWMwaveformsusingthePowergui/FFTtool.
CircuitDescription
ThesystemconsistsofthreeindependantcircuitsillustratingvariousPWMDC/DCandDC/ACconvertersarecontrolledinopenloopwiththeDiscretePWMGeneratorblockavailableintheExtras/DiscreteControlBlockslibrary.
ThethreecircuitsusethesameDCvoltage(Vdc=400V),carrierfrequency(1080Hz)
andmodulationindex(m=0.8).Fromtoptobottom,thethreecircuitsare:
1.DC/DC,two-quadrantconverter(one-arm;two-switches)
2.DC/AC,bipolarconverter(one-arm;two-switches)
3.DC/AC,monopolarconverter(two-arms;four-switches)
Inordertoallowfurthersignalprocessing,signalsdisplayedonthethreeScope
blocks(sampledatsimulationsamplingrateof3240samples/cycle)arestoredinthree
variablesnamed'psb1phPWM1_str','psb1phPWM2_str'and'psb1phPWM3_str'
(structureswithtime).
Demonstration
RunthesimulationandobservethefollowingtwowaveformsontheScopeblocks:
currentintotheload(trace1),voltagegeneratedbythePWMinverter(trace2).
Oncethesimulationiscompleted,openthePowerguiandselect'FFTAnalysis'to
displaythe0-5000Hzfrequencyspectrumofsignalssavedinthethree
'psb1phPWMx_str'structures.TheFFTwillbeperformedona2-cyclewindow
startingatt=0.1-2/60(last2cyclesofrecording).ForeachcircuitselelectInput
labeled'Vinverter'.ClickonDisplayandobservethefrequencyspectrumoflast2
fundamentalcomponentofVinverter(DCcomponentincaseofcircuit
1)isdisplayedabovethespectrumthemagnitudeofthe
fundamentalorDCcomponentoftheinvertervoltagewiththetheoreticalvalues
giveninthecircuit.
Comparealsotheharmoniccontentsintheinvertervoltageforthetwo-switchand
four-switchDC/ACinverters.
Forthetwo-switchinverter,thefirstharmonicsoccuraroundthecarrierfrequency
(1080Hz+-k*60Hz,withamaximumof103%at1080Hz),
whereasforthefour-switchinverterharmonicsarelowerandappearatdoubleof
carrierfrequency(maximumof40%at2*1080+-60Hz).Asaresult,thecurrentis
"cleaner"forthefour-switchinverter.
IfyounowperformaFFTonthesignalIloadyouwillnoticethattheTHDofload
currentis7.3%forthetwo-switchinverterascomparedtoonly2%forthe
four-switchinverter。
CircuitDescription
Athree-phasemotorrated3HP,220V,1725rpmisfedbyasinusoidalPWM
inverter.Thebasefrequencyofthesinusoidalreferencewaveis60Hzwhilethe
triangularcarrierwave'sfrequencyissetto1980Hz.
ThePWMinverterisbuiltentirelywithstandardSimulinkblocks.Itsoutputgoes
throughControlledVoltageSourceblocksbeforebeingappliedtotheAsynchronous
Machineblock'sstatorwindings.Themachine'srotorisshort-circuited.Itsstator
leakageinductanceLlsissettotwiceitsactualvaluetosimulatetheeffectofa
smoothingreactorplacedbetweentheinverterandthemachine.Theloadtorque
appliedtothemachine'sshaftisconstantandsettoitsnominalvalueof11.9N.m.Themotorisstartedfromstall.Thespeedsetpointissetto1.0pu,or1725rpm.This
speedisreachedafter0.9s.
Demonstration
Takealookatthesimulationparameters.TheMaximumtimestephasbeenlimitedto
10microseconds.
Thisisrequiredduetotherelativelyhighswitchingfrequency(1980Hz)ofthe
inverter.
Observethattherotorandstatorcurrentsarequite"noisy,"despitetheuseofa
smoothingreactor.ThenoiseintroducedbythePWMinverterisalsoobservedinthe
electromagnetictorquewaveformTe.However,themotor'sinertiapreventsthisnoise
fromappearinginthemotor'sspeedwaveform.TheRMSvalueofthefundamentalcomponentofthelinevoltageatthemachine's
statorterminalsisextractedwithaFourierblock,whichcanbefoundinthe
MeasurementsgroupoftheExtraslibrary.
Finally,observethePWMinverter'soutput.Usethezoomonthevaboscilloscopeto
zoominonthewaveform.
Simple6-pulseHVDCTransmissionSystem(discrete)
Thisdemonstrationillustratessteady-stateandtransientperformance
ofasimple500MW(250kV-2kA)HVDCtransmissionsystem
CIRCUITDESCRIPTION
A500MW(250kV,2kA)DClinterconnexionisusedtotransmitpowerfroma315
kV,5000MVAACnetwork.ThenetworkissimulatedbyaLLRdampedequivalent
(impedanceangleof80degreesat60Hzand3rdharmonic).Theconverter
transformerandtherectifieraremodelledrespectivelywiththeUniversal
TransformerandUniversalBridgeblocksTheconverterisa6-pulserectifier.Itis
connectedtoa300kmdistributedparameterlinethrougha0.5Hsmoothingreactor
inverterissimulatedbyasimpleDCvoltagesourceinserieswithadiode(to
forceunidirectionalconduction)andsmoothingreactorreactivepower
requiredbytheconverterisprovidedbyasetoffilters(Cbankplus5th,7thandhigh
passf
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