文献翻译——单级单刀功率因数校正器 ACDC变换器

第1页外文文献资料Single-stagesingle-switchpowerfactorcorrectionAC/DCconverterAsingle-stagesingle-switchpowerfactorcorrectionAC/DCconverterisproposedinwhichthepowerfactorcorrection(PFC)inductionisconnecttoatapontheprimarywindingoftheDC/DCflybackconverterstage;thereisdirectenergytransferofapartoftheinputenergytotheoutputandtheDC-busvoltagefeedback.TheadditionaldischargepathinthePFCinductionandDC-busvoltagefeedbackeffectivelysuppressestheDC-busvoltageandincreasestheoverallefficiency.Experimentalresultsfora60Wconverterataconstantswitchingfrequencyof70kHzareobtainedtoshowtheperformanceoftheproposedconverter.ItisshownthatthevoltageacrosstheDC-buscapacitorcanbeheldbelow405Veventhoughtheconverteroperatesinawiderangeofinputvoltages(90V-265VAC)andthemeasuredinputcurrentharmonicssatisfytheIEC。1IntroductionManyPFCAC/DCconvertershavebeenpresentedinrecentyears.PFCtechniquescanbedividedintotwocategories:asingle-stageapproachandatwo-stageapproach.Thetwo-stageapproachisthemostcommonlyusedapproach.Conventionaltwo-stagePFCconvertersinvolvetheuseofcascadingtwopower-processingstages,responsibleforpowerfactorcorrectionandoutputvoltage.APFCconverterisadoptedatthefront-endtoforcethelinecurrenttrackingthelinevoltageandanotherconventionalDC/DCconverteriscascadedafterthePFCstagetoobtainthedesiredtightlyregulatedoutputvoltage.Thisapproachcanobtainverygoodperformance,suchashighpowerfactor,andlowvoltagestress.However,duetotheuseoftwopower-processingstages,conversionefficiencyisreducedandanadditionalPFCstageaddscomponentsandcomplexity.Consequentlytheoverallcostin第2页creases.Thetwo-stageapproachhasdisadvantagesoflowpowerdensity,controlcomplexity,andhighcost.Toreducetheoverallsizeandcost,anumberofsiglestagePFCconvertershavebeendevelopedintheliteraturewitchessothatthePFCswitchanditscontrollercanbeeliminated.Thesingle-stageapproachisspeciallyattractiveinlow-costandlow-powerapplicationsduetoitssimplepowerstageandcontrolcircuit.However,itstillhasseveraldrawbackssuchashighcurrentstressinpowerswitchandhighDC-busvoltagestress.ItsmajordrawbackisahighvoltagestressontheDC-buscapacitor.Manysingle-stagePFCAC/DCconverterssufferfromhighDC-busvoltagestressatlightloadandhighline,whichmakestheseconvertersimpractical.AhighDC-busvoltagemeanshighcomponentrating,highcostandlowvoltagestress.Experimentalresultsfora60Wconverterataconstantswitchingfrequencyof70kHzareobtainedtoshowtheperformanceoftheproposedconverter.ItishownthatthevoltageacrosstheDC-buscapacitorcanbeheldbelow404Veventhoughtheconverteroperatesinawiderangeofinputvoltages(90V-265VAC)andthemeasuredinputcurrentharmonicssatisfytheIEC61000-3-2ClassDrequirements.2AnalysisofproposedconverterFigure1showstheequivalentcircuitsoftheproposedconverter.ThesecondarywindingNbisaddedinthePFCboostinduction.ThefirsttransformerT1inDC/DCpartcanbeoperatedeitherinCCMorDCMdependingontheloadconditionsasintheconventionalflybackconverter.Forsimplification,DC/DCpartisassumedtooperateinCCMforentirelineperiod.ThesecondtransformerT2isoperatedinDCM.AccordingtotheoperationofT2,WhentheDC-busvoltagefeedbackvalueV1(=np2Vab,np2=N2/Np)ishigherthantherectifiedlineinputvoltagevi,theconverteroperationentersregionA.InregionAonlyT1isoperatingandDbisreverse-biasedduringtheon-timeperiodS.WhenViishigherthanV1andlowerthanV2theoperationconverterentersregionB.InthisregionT1andT2worklikeflybacktransformers;V2isdeterminedbyVd+(n1-na)Vowheren1=N1/Nsandna=Na/Nb.WhenviishigherthanV2theconverteroperationentersregionC.In第3页thisregionT1workslikeaflybacktransformerandT2workslikeaboostinduction.SincethevoltageviisVmsinotinthefirstquarteroflineperiod,theboundarytimestxandtyforthreemodesaregivenbyFig.1Equivalentcircuit2.1RegionAoperationInregionAtheinputvoltageviislowerthantheDC-busvoltagefeedbackvalueVl=(N2/Np)Vd.OnlytheDC/DCpartoperates.ItdeliverspowerfromtheDC-buscapacitorCdtotheloadRLthroughT1.AttotheswitchSisturnedon.SincetheDC-busvoltageVdisappliedacrossthemagnetisinginductanceLm1,themagnetisingcurrentiLm1increaseslinearlyfromitslowpeakvalueImA,Lasfollows:Att1theswitchSisturnedoffandtheoutputdiodeD1ison.Since-npVoisappliedacrossthemagnetisinginductanceLm1,thecurrentdecreaseslinearlyfromitshighpeakvalueImA,Hasfollows:ThediodecurrentiD1isgivenbyFrom(3)and(4)thevoltagegainisdeterminedasfollows:SincetheDC/DCpartoperatesinCCM,thedutycycleDdoesnotchangewiththeloadvariation.From(6)theturnrationnpcanbedeterminedby第4页ThedutycycleDcanbeobtainedasThedutycycleDisalsoeffectiveinregionsBandC.ThepowerP1deliveredbythetransformerT1isdeterminedasSincethepowerP1deliveredbythetransformerT1shouldbeequaltotheoutputpowerPo(=Vo2/RL),thefollowingrelationisobtained:ConsequentlytheDC-buscapacitorprovidesthewholepowertotheload.From(3),(6)and(10),thehighandlowpeakvaluesofiLm1aredeterminedby2.2RegionBoperationWhenthevoltageviishigherthanV1andlowerthanV2,theconverteroperatesinregionB.PFCcelloperatesasDCMflybackconverter.Att0theswitchSisturnedon.SincetheDC-busvoltageVdisappliedacrossthemagnetisinginductanceLm1,themagnetisingcurrentiLm1increaseslinearlyfromitslowpeakvalueImB,Lasfollows:ThemagnetisingcurrentiLm2increaseslinearlyfromzeroasfollows:SincetheDC-buscapacitorcurrentiCd,thecurrenti2,andtheswitchcurrentisaregivenby第5页From(15)itcanbeseenthatthemagnetisingcurrentiLm1issuppliedbythemagnetisingcurrentiLm2andthedischargingcurrentiCdoftheDC-buscapacitorCd.From(17)theswitchcurrentisisalsocomposedofthetwocomponents.Theconductionlosscanbereducedbyselectingsmallernp1.Att1theswitchSisturnedoffandtheoutputdiodesD1andD2areon.SincenpVoisappliedacrossthemagnetisinginductanceLm1,thecurrentiLm1decreaseslinearlyfromitshighpeakvalueImB,Hasfollows:SincethediodeD2ison,_naVoisappliedacrossthemagnetisinginductanceLm2andthecurrentiLm2decreaseslinearlyfromitspeakvalueIm,pasfollows:ThepeakvalueIm,pisgivenbyFrom(20)Att2thecurrentiLm2arrivesatzeroandthediodeD2isturnedoff.ThepowerP1deliveredbythetransformerT1isgivenbyThepowerP2deliveredbythetransformerT2isdeterminedbySincethesumofthepowerP1deliveredbythetransformerT1andthepowerP2deliveredbythetransformerT2shouldbeequaltotheoutputpowerPo,thefollowingrelationisobtained:From(6),(13)and(24),thehighandlowpeakvaluesofiLm1aredeterminedby第6页2.3RegionCoperationWhenthevoltageviishigherthanV2theconverteroperatesinregionC.ThePFCcelloperatesasaDCMboostconverterandthediodeD2isoffinthisregion.Att0theswitchSisturnedon,iLm1increaseslinearlyasfollows:iLm2increaseslinearlyasinregionB.Equations(9)(11)arealsoeffectiveinthisregion.ThemagnetisingcurrentiLm1issuppliedbythemagnetisingcurrentiLm2andthedischargingcurrentiCdoftheDC-buscapacitorCd.WhenthecurrentiLm2ishighenoughthatnp2iLm2exceedsiLm1,theDC-buscapacitorcanbeinchargingmodeduringtheontimeintervalofS.Thischargingmodemayoccurnearthelinepeakvoltageasfollows:Att1theswitchSisturnedoffandtheoutputdiodesD1.Since_npVoisappliedacrossthemagnetisinginductanceLm1,thecurrentiLm1decreaseslinearlyfromitshighpeakvalueImC,Hasfollows:SincethediodeDbison,thevoltageacrossthemagnetisinginductanceLm2is_Vd_n1Vo+viandthecurrentiLm2decreaseslinearlyfromitspeakvalueIm,pasfollows:ThepeakvalueIm,pisgivenby第7页From(31)Sincethecurrenti1,theDC-buscapacitorcurrentiCd,andthediodecurrentiD1aredetermineasfollows:ThecurrentiD1iscomposedoftwocomponentswhicharefromLm1andLm2.Therefore,thereisdirectpowertransferfromthelineinputtotheloadduringtheswitchoff-time.Asaresulttheoverallefficiencycanbeimproved.Att2,thecurrentiLm2arrivesatzeroandthediodeDbisturnedoff.ThecurrentiD1isnpiLm1.SincetheoutputpowershouldbeequaltothesumofthepowerfromLm1andthepowerfromLm2,thefollowingrelationisobtained:From(6),(13)and(24),thehighandlowpeakvaluesofiLm1aredeterminedby第8页Title:AC/DCconvertercircuitAbstract:ThereisdisclosedanAC/DCconvertercircuit.Thecircuitcomprises:aninputterminalforreceivinganACsupplyvoltage;adrivercircuitadaptedtosupplyaDCdrivecurrentorvoltagetoanoutputofthecircuitbasedonasignalprovidedtoacontrolterminalofthedrivercircuit;andanACcouplingnetworkconnectedbetweentheinputterminalandthecontrolterminalofthedrivercircuit.TheACcouplingnetworkisadaptedtoderiveasignalfromanACsupplyvoltagereceivedbytheinputterminalandtosupplythederivedsignaltothecontrolterminalofthedrivercircuit.1.AnAC/DCconvertercircuitcomprising:aninputterminalforreceivinganACsupplyvoltage;adrivercircuitadaptedtosupplyaDCdrivecurrentorvoltagetoanoutputofthecircuitbasedonasignalprovidedtoacontrolterminalofthedrivercircuit;andanACcouplingnetworkconnectedbetweentheinputterminalandthecontrolterminalofthedrivercircuit,whereintheACcouplingnetworkisadaptedtoderiveasignalfromanACsupplyvoltagereceivedbytheinputterminalandtosupplythederivedsignaltothecontrolterminalofthedrivercircuit.2.Thecircuitofclaim1,whereintheACcouplingnetworkisadaptedtoderiveasignalbasedonthephaseoftheACsupplyvoltagereceivedbytheinputterminal.3.Thecircuitofclaim1or2,whereinthedrivercircuitisanintegratedcircuit.4.Thecircuitofclaim3,whereintheintegratedcircuitisanAC/DCconverterdriver.5.Thecircuitofanyprecedingclaim,furthercomprisingarectifieradaptedtorectifyanACsupplyvoltagereceivedbytheinputterminal.6.Thecircuitofanyprecedingclaim,whereintheACcouplingnetworkcomprisesacapacitorandresistorconnectedinseries.第9页7.Thecircuitofanyprecedingclaim,whereinthecontrolterminalofthedrivercircuitisadaptedtocontrolatleastoneparameterofthedrivercircuit.8.Thecircuitofclaim1,whereintheatleastoneparametercomprisesatleastoneof:apeakinductioncurrent;aswitchingfrequencyofthedrivercircuit;andapulseinterval.9.Thecircuitofanyprecedingclaim,furthercomprisingaDCcouplingarrangement,andwhereinthedrivercircuitisfurtheradaptedtosupplytheDCdrivecurrentorvoltagetotheoutputofthecircuitbasedonasignalfromtheDCcouplingarrangement.10.AsolidstatelightingdevicecomprisinganAC/DCconvertercircuitaccordingtoanyprecedingclaim.11.AnelectricalpowersupplycomprisinganAC/DCconvertercircuitaccordingtoanyprecedingclaim.Description:Thisinventionrelatestothefieldofconvertercircuits,andmoreparticularlytoanAC/DCconvertercircuitfordrivingsolidstatelightingdevicesandthelike.ItisknowntoemployAC/DCconvertercircuitsinordertodriveandcontrolSolidStateLighting(SSL)devices,suchasLED.WithhighvolumeproductionofSSLdevices,thereisadesiretoreducethecostofsuchcircuits.ConventionalAC/DCconvertercircuitsemploysimpleIntegratedCircuit(ICS)incombinationwithexternalcomponents.Tolimittheassociatedcostofthecomponents,itispreferabletominimizeheadroominthethermaldesignofthecircuitandtheSSLdevice,andthismayrequireaccurateregulationofthedrivecurrentsuppliedtotheSSLdevice.Also,forthepurposeofenergyconservation,goodperformanceofthecircuitintermsofefficiencyandPowerFactor(PF)mayberequired.ICscontaininganadvancedalgorithmtoachieveagoodPFandaccuratedrivecurrentareavailable,butthesearealsoexpensive.Someexistinglow-costdriversolutionsareknownwhichaddressthedrivecurrentaccuracyrequirement,butthesedonotachieveanadequatePF.第10页AgoodPFisbecomingmoreandmoreimportant,andplacesastrictrequirementondriversolutions.Forexample,intheUnitedStatesofAmericas,thePFmustbeatleast0.7forresidentialuseandeven0.9forcommercialuse.TypicalAC/DCconvertercircuitsfordrivingaSSLdevicecompriseaBuck,tapped-Buck,Buck-BoostorFlybackconverterthat,ineveryswitchingcycle,rampsupthecurrentinaninductiontoanaccuratepredefinedvalueandthenreleasesthemagneticenergyintotheSSLload.DependingontheconverterworkinginBoundaryConductionMode(BCM)orDiscontinuousConductionMode(DCM),thenextcycleisstartedrightaftertheenergyintheinductionhasvanishedtozero(inBCM)oronlyafterreceivingacontroltriggerfromaseparatetimer,runningonadefinedswitchingfrequency(inDCM).Themostsimpleandlow-costconverterwithagoodperformanceintermsofdrivecurrentaccuracyorregulation(assessableintermsoftheinsensitivityofthedrivecurrenttothemagnitudeof:theACinputvoltage(e.g.amainsinputvoltage);theloadvoltage;inductionvalue;andswitchingfrequencyFSW)istheBuckconverteroperatinginBCM.However,othercircuitsmaybeconfiguredasBuck-BoostorFlybackdriverworkinginBCMInordertogetahighPF,theswitchingfrequencyFSWand/ortheconvertinputcurrentIPKmaybemodulatedwiththephaseoftheinputvoltage(mainsfrequencybeingtypically50or60Hzforexample).However,knownmethodstomodulatetheconverterinputcurrentand/ortheswitchingfrequencyinthiswayaredependentonthemagnitudeoftheinputvoltage,andresultinapoorregulationofthedrivecurrent.Thisproblemofpoorregulationofthedrivecurrent(alsoreferredtoaslineregulation)hasresultedinmorecomplicated,andhencemoreexpensive,circuitsbeingimplemented.AccordingtoanaspectoftheinventionthereisprovidedanAC/DCconvertercircuitfordrivingasolidstatelightingdeviceaccordingtoindependentclaim1.ProposedisanAC/DCconvertercircuitcomprisinganACcouplingnetworkthatderivesasignalfromanACinputvoltageandsuppliesthederivedsignaltothecontrolterminalofadrivercircuit.Controlofthedriver第11页circuitmaythereforebemodulatedinphasewiththeACinputvoltage.EmbodimentmaythusmodulatetheinputcurrentwaveformofaswitchingAC/DCconverterusinganACsupplyvoltagewhilstpreservinggoodaccuracy(i.e.goodregulation)oftheoutputDCdrivecurrent.Thus,thePFofanAC/DCconvertercircuitaccordingtoanembodimentmaybeimprovedwhilstmaintainingregulationoftheoutputcurrent.Also,embodimentmaymodulateaninputcurrent,switchingfrequencyorothercontrolparameter,withoutneedingawaveformgeneratorthatisphase-lockedtothemainsphase,orwithoutrequiringcomplicatedalgorithms(likeasystemexplicitlysensingtheinputvoltagemagnitudeoracalculationandfeedbackloop).ExistingSSLdriverICSmaythereforebeemployedinconjunctionwithjustafewexternalcomponentsinordertocreateembodimentoftheinvention.TheACcouplingnetworkmaysimplyconsistofacapacitorarrangedinserieswithsignaltobecoupled(e.g.aninputACsupplyvoltage).Inotherembodiment,theACcouplingnetworkmayfurthercompriseoneormoreresistorsthatservetoscalethecoupledsignal.Although,theembodimentdescribedabovehavebeendetailedinconjunctionwithspecificdriverICS,otherembodimentoftheinventioncanbeimplementswithotherdriverICSforsupplyingacurrenttoaload(suchasanLEDforexample).Also,althoughembodimenthavebeendescribedasbeingsuitablefordrivingaSSLdevice,otherembodimentareapplicableasanymains-suppliedAC/DCconverter.EmbodimentneednotbeconnectedtoamainASsupplyvoltage,butmayinsteadbeconnectedtoanyothersuitablepowersupply.TheACcouplingnetworkmaybemodifiedtooptimizethecircuitinapreferreddirectionbyshiftingtheDCset-pointandchangingthegain.TheACcouplingnetworkcanalsobemodifiedtocontainacombinationofACandDCcoupling.AlthoughembodimentenablemodulationofthedriverICinputinordertoimprovetheconverterPF,otherobjectivesmayalsobeserved(likeoptimizingacompromisebetweenthesizeofarequiredoutputcapacitorandthePF).第12页第13页中文翻译稿单级单刀功率因数校正器AC/DC变换器摘要单级单刀开关AC/DC功率因数校正器（PFC）是电感连接到初级绕组的直流/直流转换器；输入能量的一部分直接转移成输出能量和反馈给DC总线。另外在PFC电感放电和DC总线电压反馈过程中，有效地抑制了直流母线电压，提高了整体效率，在一个功率60W、恒定开关频率70千赫转换器的实验中的性能结果表明，电压在直流总线下电容可以兼容，即使低于405V，转器工作在带宽输入电压（90-265VAC）的条件下，测量输入电谐频各项指标满足国际电工委员会要求。1简介近年来，许多功率因数校正AC/DC转换器相继问世。PFC的技术可以分为两个类别：单级方法和双级方法。这两个不同层次的方法是最常使用的方法。传统的双级PFC变换器涉及两个级联在电路中使用，负责功率因数校正和输出额定电压。PFC转换器是采用在前端迫使线电流跟踪线电压，一种传统的直流/直流转换器串联后的PFC可以获得现阶段所需的稳定的额定输出电压。这种方法可以取得很好的成效，如提高功率因数，降低电压冲击。然而，由于两种电源的工作转换使用效率降低，增加了PFC阶段额外的组件和复杂性,因此整体成本增加。这两个阶段的方法具有低功率强度，控制复杂，成本高的缺点。为了减少整体规模和成本，在一些相关著作中对很多单级PFC的转换器作了详细阐述。其主要思想是，PFC和DC/DC有共同的PFC开关，它的开关及其控制器可以被闲置。由于单级方法简单特别是在低成本和低功耗地方得到了应用。然而，它仍然有几个缺点比如在电源开关和高直流母线电压冲击下有较高的电流脉动。其主要缺点是对直流总线电容有高电压损伤。许多PFC和C/DC转换器受到低负载和高直流限制，高直流总线高电压组合方法具有高成本和低效率的特点。横跨直流总线电容的电压随着输入电压和负载的变化而变化，特别是当在不连续工作的传导模式（DCM）和直流/直流中的部分PFC是连续传导模式（CCM）。DCMPFC和CCM的直流/直流组合可生成一个高达1000v的直流母线电压它可以像对在高线和低荷载线路上普遍应用。然而，在DCM或者CCM两部分第14页的结合操作模式中没有直流母线电压应力的问题。由于DCM的升压转换器有其内在的PFC特性，PFC部分更适合在DCM中操作。如果PFC部分和DC/DC部分都在DCM中操作，则直流总线电容的电压是独立的负载。然而，与CCM操作模式相比较，高开关电流需要高电流额定开关并且会降低效率。因此，在低功耗应用中DCMPFC和CCMDC/DC的结合被认为是理想的组合。为了抑制高直流母线电压应力，一个变频调速被很好的使用起来，但是它也存在一些问题，类似于高频率和电感元件及输入滤波器的设计上有问题。PFC的附加绕组电感能有效地抑制直流母线电压并且提供直接能源转换。然而，当开关打开，无论是升压电感电流和磁化电流都会流过开关。也就是说，开关电流冲击是PFC的一部分，它是组成直流/直流的部分，它增加传导损耗。提出了单级单开关功率因数校正AC/DC转换器，因为第二绕组中加入PFC升压电感，输入功率是直接转化为输出功率。此外，在DC/DC级绕组的初级阶段通过连接上的PFC电感扼流圈一直到首端，有一部分的输入能量直接转化成输出能量。并且，当开关为ON时，在直流/直流变压器转化时有一些升压电感的磁化会使电感充电，它可以减少传导损失。一般来说，这些直接的能量转移会提高整体效率和抑制直流总线电压。一个60W的转换器的实验中，恒定开关频率为70千赫换器的性能结果表明，电压在直流总线电容可以兼容，即使低于405V，转换器工作在宽输入电压范围（90B265VAC）的条件下，测量输入电谐频各项指标满足国际电工委员会要求。2转换器的分析建议图1显示了转换器的等效电路图。二次绕组中添加Nb，是PFC的升压电感。一次侧变压器T1在DC/DC部分无论是CCM或DCM，可以根据负载在常规条件下反馈给转换器。为了简化，直流/直流部分用于CCM总线路的操作中。变压器T2的在DCM中。根据T2的运作，有三个操作，如图3所示，当直流总线V1的电压反馈值(=Np2Vd,Np2=N2/Np)超过输入电压的整流线的电压，该转换器就会在区域A运行。在A区只有T1是正在运行，Db是在一段时间s上反向偏置。Vi高于V1和低于V2的时候，此时转换操作进入B区。在这个区域，T1和T2工作起来就像一个回扫转换器;V2是由Vd+(n1-na)Vo决定。其中n1=N1/Ns和na=Na/Nb。当ViV2时该转换器操作进入C区。在这个区域，T1就像一个回扫变压器在工作并且T2就像一个升压电感。由于Vi电压是正弦曲线最大值的四分之一，是介于tx和tY的，如下所示：第15页图1转换器的等效电路图2.1A区操作在区域A，输入电压Vi低于直流总线V1的电压反馈值，Vl=(N2/Np)Vd.，只有直流/直流部分运作。它提供的直流电源通过T1使总线电容从Cd的负荷传给RL。在t0时刻开关S是打开的。由于直流母线电压Vd适用于整个磁化电感Lm1中，磁化电流iLm1从最低的IMA，L的峰值线性增加如下：磁化电感L，从最在T1时刻开关S是关闭的，输出二极管D1处于工作状态。由于npVo是适用于整个高的IMA，H的峰值线性减少如下：二极管电流ID1是：在（3）及（4）中电压V0如下：由于直流/直流部分在CCM中运作，环流D不会改变负载的变化。从（6）看出np可确定为：环流D的表达式为：环流D在B区和C区也是有效的通过T1得到的P1的表达式如下所示：功率P1等于输出功率P0即：因此直流总线电容向负载提供了全部功率。从（3），（6）及（10），最大值ImA,H第16页和最ImA,L小值取决于2.2B区的运作当电压vi高于V1或低于V2的时候，该转换器就在B区运作,此时PFC单元作为DCM回扫式转换器。在T0时刻开关S是打开的。由于直流母线电压VD的应用整个磁化电感Lm1被磁化,iLm1从最小值ImB,L线性增加，关系式如下：该磁化电流iLm2从零线性增加，即：由于N1i1+N2i2=0的i2i1=iLm2，直流总线电容电流ICD，电流I2和开关电流is关系如下从（15）可以看出，磁化电流iLm1和磁化电流iLm2是由直流总线电容ICD的放电提供的。（17）开关电流is也是其中的两个组件。通过选择np1可以使该传导的损失减少。在T1时刻开关S是关闭的，输出二极管D1和D2处于工作状态。相关表达式如下：由于二极管D2处于工作状态，-nav0是从磁化电感Lm2和当前电流iLm2的峰值imp线性下降，即：峰值imp为：从（20）在T2时刻电流iLm2到达零，二极管D2断开。由T1得到的P1为第17页由T2得到的P2由T1得到P1和T2得到P2共同控制输出电压，关系式为：从（6），（13）和（24），最高和最低峰值iLm1取决于2.3C区运作当电压viV2时，转换器在C区运作，在这个区，PFC单元就像DCM升压转换器同时二极管D2是断开的。在T0时刻，开关S是打开的，iLm1是线性增加的即：iLm2在区域B线性增加。此时可以运用上述的方程组（9）-（11）。磁化电流iLm1是由磁化电流和放电iLm2直流总线电容Cd所提供的。当电流iLm2是足够高并且np2iLm2超过iLm1时，直流总线电容在充电过程中会出现一个瞬时电流。这种充电模式会产生线性峰值电压，如下：在t1时刻，开关S和输出二极管D1是断开的。由于-npVo是适用于整个磁化电感Lm1，电流iLm1线从峰值线性减少由于二极管DB是连通的，两端电压的磁化电感Lm2是-Vd-n1Vo+vi，电流iLm2从峰值im，p线性减少峰值im，p由下式确定：由(31)：第18页由于电流i1，直流总线电容电流iCd和二极管电流iD1的决定式如下电流ID1来自于电感Lm1和Lm2两个部分。因此，功率直接从输入线路到负载上转换，因此总体效率被提高。在t2时刻，电流iLm2为零并且二极管Db是断开的。电流ID1=npiLm1。由于输出功率等于来自于电感Lm1和电感Lm2的总和，下面的关系式为：从（6），（13）和（24），电流iLm1的最大值和最小值由下式决定名称：AC/DC转换电路摘要：本文所讲的是一种AC/DC转换电路。该电路包括：用于接收交流电源电压的输入端;适于驱动电路供给直流驱动电流或电压，以根据提供给所述驱动电路的控制端子的信号的电路的输出;以及连接在输入端子和所述驱动电路的所述控制端之间的交流耦合网络。AC耦合网络被适配成导出从由输入端子接收的AC电源电压的信号，并且供给来自信