太阳能光伏并网逆变器设计原文及翻译

Grid-ConnectedSolarMicroinverterReferenceDesignAbstract-Intraditionalgrid-connectedPVsystem,it’shardtoremovefailureofindividualPVpanels.ThispaperpresentsaSolarPVGrid-ConnectedMicro-inverterwhichcanbeembeddedinasinglestand-alonephotovoltaicpaneltosolvetheproblemofsinglepointoffailure.Forasinglephotovoltaicpanel,ratedpoweroftheMicro-inverteris220W,usingthetopologyofinterleavedflybackconverter.Keywords-Micro-inverter;interleavedflybackconverter;grid-connected;PVpanelI.INTRODUCTIONWiththedrainingoffossilfuelandincreasinglyseriouspollutioncausedbytraditionalpowergenerationmethodsacrosstheworld,renewableandpollution-freeenergyhasgainedmuchattentionineconomicandpoliticalfields.Renewableenergyincludesphotovoltaic(PV)andwindpowergenerationsystems.Wideapplicationofrenewableenergyisnowimpededbycostandextensiveresearchesshallbeconductedinordertoimprovecosteffectiveness.PVsystem,alsoknownassolarconverter,hasgainedpopularityinrecentyearsasaconvenientrenewableenergywithgoodprospects.HighproductioncostandlowconversionefficiencyofsiliconsolarpanelaremajordefectsofPVenergy.CosteffectivenessofPVprojectswillbecomemorereasonablewiththeapplicationofnewPVpanelproductiontechnologyandtheimprovementofconverterefficiency.ІІ.EVOLUTIONOFPVSYSTEMA.TraditionalGrid-connectedSystemTraditionalgrid-connectedPVsystemiscomprisedof:UrbanHomeSystem–multiplesolarpanelsareconnectedinserialtosupply200-400VDCandoutputmediumpower(2-10KW)ACelectricity.IfcertainPVpanelintheseriesloopisdamaged(i.e.singlepointoffailure),theentiresystemwillbecrashed,i.e.thesystemisunstableSingleInverterWithMultipleDC/DCConverters–multiplePVpanelsareconnectedinparallelafterDC/DCconversiontoinputtotalDCbusbarvoltagetoinverterandincreaseoutputpower.SuchcircuitstructurealsohasproblemofsinglepointoffailuremeanwhilefusionofDCpowersupplyisverycomplex.UrbanHomeSystemWithStringInverters–PVpanelproviding200-400VinputDCvoltageisconnectedtomultipleparallelinverterstogeneratemediumpower(2-10KW)120/240VACpowersupply.Multipleparallelinverterscanboostoutputpowerandimprovesystemreliability.B.PVGrid-connectedMicro-inverterBasedontheaboveadvantagesanddisadvantagesofPVsystem,thepresentpaperproposesthedesignofPVgrid-connectedmicro-invertertoenableallPVpanelsinPVsystemtobeembeddedingrid-connectedmicro-inverter,seefigure1forsystemstructure.Micro-inverterwithsuchstructurehasfollowingadvantages:•replacecentralinverterwithdistributedinvertertooptimizeenergyutilization;•IntegratedPVpanelreducesinstallationcost;•Powerofmicro-inverterislow(hundredsW),resultingnlowinternaltemperatureandlongersystemservicelife,meanwhilefanisnotrequired.III.DESIGNOFPVGRID-CONNECTEDINVERTERThepresentpaperdesignsasinglestagePVgrid-connectedmicro-inverter.Asimpleinterleavedflybackconverterisappliedtooutputsinehalf-wavecommutatingvoltageandcurrent,passthroughbridgeinvertertooutputfullwavesinevoltageandcurrentandmakethecurrenthavethesamefrequencyandphaseofthepowergridvoltage.ThisPVgrid-connectedmicro-invertermatcheswithanyPVcomponentswith220Wpowerrating,25-45Voutputvoltageandupto55Vopen-circuitvoltage.A.SystemChartPVgrid-connectedmicro-inverterappliesparallelinterleavedflybackconverter,seefigure2.Ipri1iscurrentofflyback1converterMOSFETandIsec1iscurrentofflyback1outputdiode.Currentofsecondarydiode(Isec1)generatessinusoidaloutputvoltageafterbeingfilteredbyoutputfiltercapacitor.Theinvertermakesoutputcurrentsynchronouswithgridvoltagewithdigitalphase-lockedloop(PLL)technology.Themaximumpowertracksandcontrolstheoutputcurrent.VoltageoutputbyPVpanelisconvertedintosinehalf-wavecommutatingvoltage/currentbyinterleavedflybackconverter,inputsfull-bridgeinvertercircuitwhereitisinvertedintocurrentwiththesamephaseofgridvoltage,andisconnectedtopowergridafterEMC/EMIfiltration.Dutyratioflybackconverterswitchshallbecontrolledtomaketheoutputcurrenthavethesamephaseandfrequencywithgridvoltage.Interleavedflybackconverterimprovesservicelifeofcapacitorbyreducingtheeffectivevalueofinputlargeelectrolyticcapacitorripplecurrent.Interlacedoutputreducesoutputcurrentripplesoastodecreasetotalharmonicdistortionofcurrent.B.CircuitAnalysisPVpanelDCvoltageinputsinterleavedflybackconverteranddrivesflybackMOSFETtogeneratesineoutputvoltage/currentwithHFsinePWNmodulatingsignal.Phasedifferencebetweentwointerleavedflybackconverterdrivingsignalsis180degree.Interleavedflybacktopologystructureworksundertwoswitchmodes.•Mode1:whenflybackMOSFETisopened,HFflybacktransformerprimarymagneticinductoraccumulatesenergy,diodeisphasereversalblockedandthesecondarytransformerwindingvoltageisreversebiased.Duringthatperiod,primaryinductorofHFflybacktransformerislikeapowerinductor,primarycurrent(Ipri1/Ipri2)ascendslinearlyandloadcurrentisfromoutputcapacitor.Mode2:whenflybackMOSFETisclosed,voltageofprimarywindingisinphasereversalandoutputdiodeisforwardbiased.Energystoredatprimarywindingistransferredtosecondarywindingandprovidecurrenttooutputcapacitorandload.Duringthatperiod,outputvoltageisfromthesecondarytransformerwindingdirectlyandthenlinearityofdiodecurrentdecreases.SinePWMmodulatingsi