電腦基礎(chǔ)知識(shí)

電腦基礎(chǔ)知識(shí)第1頁/共55頁

LCD和等離子體TV市場(chǎng)逐年增長。這些市場(chǎng)和其他市場(chǎng)都需要一種具有如下功能特色的SMPS產(chǎn)品：

TheLCDandPLASMATVmarketisgrowingeachyear.TheseandalsoothermarketscallforanSMPSunitthatcanprovidethesefeatures:輸出功率范圍：150W～600W

Outputpowerfrom150Wupto600W寬范圍交流輸入U(xiǎn)niversalmains有源和無源PFC（由所需的功率所決定）

ActiveorpassivePFC(givenbyneededpower)寬度和空間有限，無風(fēng)扇：通風(fēng)條件有限Limitedwidthandspace,nofan:limitedairflow低待機(jī)能耗Lowstandbypowerconsumption消費(fèi)類電子市場(chǎng)：殘酷的競(jìng)爭(zhēng)ConsumerElectronicsmarket:fiercecompetition

上述要求能夠通過一個(gè)SMPS來實(shí)現(xiàn)，該電路可以提供：

TheaboverequirementscanbefulfilledwithanSMPSthatprovides:高功率密度Highpowerdensity平滑的EMI特征SmoothEMIsignature元件數(shù)量少、成本經(jīng)濟(jì)性好的解決方案Costeffectivesolutionwithminimumcomponentcount為何采用LLC串連諧振變換器？

WhyanLLCSeriesResonantConverter?第2頁/共55頁LLC串連諧振變換器的優(yōu)點(diǎn)

BenefitsofanLLCSeriesResonantConverter

串連諧振式變換器的類型。與其他諧振結(jié)構(gòu)相比，該諧振器可以在相對(duì)較寬的電壓和輸出負(fù)載范圍內(nèi)工作

Typeofserialresonantconverterthatallowsoperationinrelativelywideinputvoltageandoutputloadrangewhencomparedtotheotherresonanttopologies元件數(shù)量有限：諧振回路元件可以集成到單個(gè)變壓器（唯一需要的磁元件）中Limitednumberofcomponents:resonanttankelementscanbeintegratedtoasingletransformer–onlyonemagneticcomponentneeded在所有通常負(fù)載條件下，原邊開關(guān)都工作在零電壓開關(guān)（ZVS）條件下ZeroVoltageSwitching(ZVS)conditionfortheprimaryswitchesunderallnormalloadconditions副邊二極管工作在零電流開關(guān)條件下，無反向恢復(fù)損耗

ZeroCurrentSwitching(ZCS)forsecondarydiodes,noreverserecoverylosses用于中、高輸出電壓變換器的高成本效益、高效率和EMI友好的解決方案Costeffective,highlyefficientandEMIfriendlysolutionforhighandmediumoutputvoltageconverters第3頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransformerconstruction第4頁/共55頁一種HBLLC的構(gòu)形——單個(gè)諧振電容

ConfigurationsofanHBLLC–SingleRes.Cap

-更高的輸入電流紋波和RMS值HigherinputcurrentrippleandRMSvalue流過諧振電容的RMS電流更大HigherRMScurrentthroughtheresonantcapacitor需要耐高壓（600-1500V）的諧振電容Highvoltage(600–1500V)resonantcapacitorneeded低成本Lowcost小尺寸/布局簡(jiǎn)單Smallsize/easylayout第5頁/共55頁與單電容解決方案相比，這種分體連接具備如下特點(diǎn)Comparedtothesinglecapacitorsolutionthisconnectionoffers:更低的輸入電流紋波和RMS值(1/√2)

LowerinputcurrentrippleandRMSvalue(1/√2)諧振電容承受一半的RMS電流ResonantcapacitorshandlehalfRMScurrent所用電容的量值為單個(gè)諧振電容的一半

Capacitorswithhalfcapacitanceareused當(dāng)可以利用鉗位二極管實(shí)現(xiàn)低成本、方便的保護(hù)時(shí)，電路可采用低額定電壓（450V）的諧振電容Lowvoltageratings(450V)fortheresonantcapacitorswhenclampingdiodesD3,D4performaneasyandcheapoverloadprotection一種HBLLC的構(gòu)形——諧振電容采用分體結(jié)構(gòu)ConfigurationsofanHBLLC–SplitRes.Cap第6頁/共55頁諧振回路構(gòu)形——分立元件解決方案

ResonantTankConfigurations–DiscreteSolution諧振電感放置在變壓器之外

Resonantinductanceislocatedoutsideofthetransformer優(yōu)點(diǎn)Advantages:-更高的設(shè)計(jì)靈活形（設(shè)計(jì)者可以選擇任意滿足需要的Ls

和Lm組合Greaterdesignflexibility(designercansetupanyLsandLmvalue)）-更低的EMI輻射LowerradiatedEMIemission這種解決方案的缺點(diǎn)在于Disadvantagesofthissolutionare:原邊和副邊繞組之間的絕緣變得復(fù)雜

Complicatedinsulationbetweenprimaryandsecondarywindings繞組的冷卻條件較差Worsecoolingconditionsforthewindings需要對(duì)更多的元件進(jìn)行安裝

Morecomponentstobeassembled第7頁/共55頁變壓器的漏電感被用作一個(gè)諧振電感

Leakageinductanceofthetransformerisusedasaresonantinductance優(yōu)點(diǎn)Advantages:-低成本，只需一個(gè)磁性元件Lowcost,onlyonemagneticcomponentisneeded

SMPS的尺寸往往更小UsuallysmallersizeoftheSMPS變壓器繞組的冷卻條件更好Bettercoolingconditionsfortransformerwindings原邊和副邊之間可以方便地實(shí)現(xiàn)絕緣

Insulationbetweenprimaryandsecondarysideiseasilyachieved缺點(diǎn)Disadvantages:靈活性較差（可用的LS電感范圍有限）

Lessflexibility(achievableLsinductancerangeislimited)

EMI輻射更強(qiáng)HigherradiatedEMIemission采用集成化諧振回路的LLC的工作方式與采用分立的Ls解決方案之間存在輕微的差別

LLCwithintegratedresonanttankoperatesinaslightlydifferentwaythanthesolutionwithdiscreteLs原邊和副邊之間存在更強(qiáng)的鄰近效應(yīng)

Strongproximityeffectintheprimaryandsecondarywindings諧振回路構(gòu)形——集成化的解決方案

ResonantTankConfigurations–IntegratedSolution

第8頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransformerconstruction第9頁/共55頁LCC變換器的工作狀態(tài)：

LLCconvertercanoperate:a)Fmin

～

Fs之間

betweenFminandFs， c)高于FsaboveFsb)直接諧振在Fs上directinFs d)Fmin和Fs之間——過載

betweenFminandFs–overload

e)Fmin以下belowFmin

。LLC變換器的工作狀態(tài)

OperatingStatesoftheLLCConverter可以確定兩個(gè)諧振頻率Tworesonantfrequenciescanbedefined:分立諧振回路解決方案Discreteresonanttanksolution第10頁/共55頁c)Fop>Fs時(shí)，基于分立諧振回路的解決方案的工作波形OperatingwaveformsforFop>FsDiscreteresonanttanksolutionCBADEFLLC變換器的工作狀態(tài)OperatingStatesoftheLLCConverter第11頁/共55頁集成化的諧振回路的行為特性不同于分立式的諧振回路

Integratedresonanttankbehavesdifferentlythanthediscreteresonanttank漏電感來自于變壓器繞組的耦合leakageinductanceisgivenbythetransformercoupling只有在原邊和副邊之間存在能量的傳遞時(shí)，Llk才起作用Llkparticipatesonlyifthereisaenergytransferbetweenprimaryandsecondary

一旦副邊的二極管在ZCS條件下閉合時(shí)Llk沒有能量OncethesecondarydiodesareclosedunderZCS,Llkhasnoenergy在HBLLC中，副邊的二極管在ZCS條件下始終處于關(guān)斷狀態(tài)。諧振電感和磁化電感永遠(yuǎn)不會(huì)象在基于分立諧振元件的解決方案中那樣共同參與諧振。SecondarydiodesarealwaysturnedOFFunderZCSconditioninHBLLC.TheresonantinductanceLsandmagnetizinginductanceLmneverparticipateintheresonancetogetheraswithdiscreteresonanttanksolution!LLC變換器的工作狀態(tài)OperatingStatesoftheLLCConverter集成化的諧振回路解決方案Integrated

resonanttanksolution第12頁/共55頁LLC變換器再次可以工作在：

LLCconvertercanagainoperate:a)

Fmin～Fs之間

betweenFminandFs

c)高于Fs

aboveFsb)直接諧振在Fs上directinFs

d)

Fmin和Fs之間——過載

betweenFminandFs–overload

e)低于Fmin

belowFmin

可以定義兩種諧振頻率Tworesonantfrequenciescanbedefined:集成化的諧振回路解決方案Integrated

resonanttanksolutionLLC變換器的工作狀態(tài)OperatingStatesoftheLLCConverter第13頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransformerconstruction第14頁/共55頁LLC變換器建模——等效電路LLCConverterModeling–EquivalentCircuit

等效電路的傳遞函數(shù)Transferfunctionofequivalentcircuit:Z1,Z2

與頻率有關(guān)=>LLC變換器的行為特性類似于一個(gè)與頻率有關(guān)的分壓器。負(fù)載越高，Lm所受到的、由Rac所產(chǎn)生的嵌位作用就越大。于是，LLC諧振回路的諧振頻率在Fs

和Fmin之間變化。Z1,Z2arefrequencydependent=>LLCconverterbehaveslikefrequencydependentdivider.

Thehigherload,theLmgetstobemoreclampedbyRac.ResonantfrequencyofLLCresonanttankthuschangesbetweenFsandFmin.LLC變換器可以通過一階基波近似來描述。僅僅是近似——精度極為有限！在Fs處達(dá)到最高精度

LLCconvertercanbedescribedusingfirsfundamentalapproximation.Onlyapproximation–accuracyislimited!!BestaccuracyisreachedaroundFs.第15頁/共55頁在使用基頻近似時(shí)，實(shí)際的負(fù)載電阻必須被修改，因?yàn)閷?shí)際的諧振回路是由電壓方波驅(qū)動(dòng)的

Realloadresistancehastobemodifiedwhenusingfundamentalapproximationbecausetherealresonanttankisdrivenbysquarewavevoltage.考慮方波的基頻分量，在RMS電壓是：

Consideringthefundamentalcomponentofthesquarewave,theRMSvoltageis:在全波橋電路中，RMS電流為：

Inafull-wavebridgecircuittheRMScurrentis:AC電阻Rac

可以表示為：TheACresistanceRaccan

beexpressedas:LLC變換器建?！刃щ娐稬LCConverterModeling–EquivalentCircuit

第16頁/共55頁諧振回路方程ResonantTankEquations品質(zhì)因數(shù)Qualityfactor:特性阻抗Characteristic

impedance:Lm/Ls

比：

Lm/Lsratio:最小諧振頻率：Minimumresonantfrequency:串連諧振頻率：Seriesresonantfrequency:與負(fù)載有關(guān)Loaddependent!！變換器的增益：Gainoftheconverter:第17頁/共55頁歸一化的增益特性NormalizedGainCharacteristic區(qū)域1：ZCS區(qū)Region3:ZCSregion區(qū)域1和區(qū)域2:ZVS工作區(qū)Region1and2:ZVSoperatingregionsQ=0.05–HeavyloadZCSZVSQ=200–Lightload第18頁/共55頁增益特性討論GainCharacteristicDiscussion-所需要的工作區(qū)是在增益特性曲線的右側(cè)（負(fù)斜率意味著原邊MOSFET工作在ZVS模式下）

Thedesiredoperatingregionisontherightsideofthegaincharacteristic(negativeslopemeans–ZVSmodeforprimaryMOSFETs).LLC變換器工作在fs＝1的狀態(tài)下，其增益為1（對(duì)于分立諧振回路元件解決方案）——由變壓器的匝數(shù)比來決定。從效率和EMI的角度來看，該工作點(diǎn)

是最有吸引力的——正弦原邊電流、MOSFET和副邊二極管得到了最優(yōu)化的利用。該工作點(diǎn)只能在特定的工作電壓和負(fù)載條件下達(dá)到（往往是指滿負(fù)載和名義值Vbulk）。

GainoftheLLCconverter,whichoperatesinthefsis1(fordiscreteresonanttanksolution)-i.e.isgivenbythetransformerturnsratio.ThisoperatingpointisthemostattractivefromtheefficiencyandEMIpointofview–sinusoidalprimarycurrent,MOSFETsandsecondarydiodesoptimallyused.Thisoperatingpointcanbereachedonlyforspecificinputvoltageandload(usuallyfullloadandnominalVbulk).

增益特性曲線的形狀以及所需要的工作頻率范圍將由如下參數(shù)給出：Gaincharacteristicsshapeandalsoneededoperatingfrequencyrangeisgivenbytheseparameters:-Lm/Ls比Lm/Lsratio諧振回路的特征阻抗Characteristicimpedanceoftheresonanttank負(fù)載值Loadvalue-變壓器匝數(shù)比Transformerturnsratio第19頁/共55頁如何獲取增益特性？HowtoObtainGainCharacteristics?

使用任何一種仿真軟件（如PSpice，Icap4等）中的基頻近似和AC仿真

UsefundamentalapproximationandACsimulationinanysimulationsoftwarelikePSpice,Icap4etc..

Rac就是所用的參數(shù)Racistheparameter!

1V幅值的AC電源1VamplitudeACsupply在給定的Rac參數(shù)下，可以直接繪制增益曲線DirectgainplotforgivenRac第20頁/共55頁分立元件解決方案的仿真原理圖Simulationschematicfordiscretesolution集成解決方案的仿真原理圖Simulationschematicforintegratedsolution對(duì)于分立和集成諧振回路DiscreteandIntegratedTankGainDifferences第21頁/共55頁滿載時(shí)的Q和k因數(shù)優(yōu)化FullLoadQandkFactorsOptimization這兩個(gè)因數(shù)的恰當(dāng)選擇是LLC諧振變換器設(shè)計(jì)的關(guān)鍵！它們的選擇將影響到變換器的如下特性：ProperselectionofthesetwofactorsisthekeypointfortheLLCresonantconverterdesign!Theirselectionwillimpacttheseconvertercharacteristics:輸出電壓調(diào)節(jié)所需的工作頻率范圍Neededoperatingfrequencyrangeforoutputvoltageregulation

線性和負(fù)載調(diào)節(jié)率范圍

Lineandloadregulationranges-諧振回路中循環(huán)能量的大小

Valueofcirculatingenergyintheresonanttank變換器的效率

Efficiencyoftheconverter在優(yōu)化時(shí)，效率、線性和負(fù)載調(diào)節(jié)率范圍往往是最重要的判據(jù)Theefficiency,lineandloadregulationrangesareusuallythemostimportantcriteriaforoptimization.

品質(zhì)因數(shù)Q直接受負(fù)載的影響。它由滿負(fù)載條件下的Ls

和Cs

元件值決定：QualityfactorQdirectlydependsontheload.ItisgivenbytheLsandCscomponentsvaluesforfullloadconditions:第22頁/共55頁-更高的Q值可以實(shí)現(xiàn)更大的Fop范圍要在給定的負(fù)載下獲得更高的Q值，必須降低特性阻抗，=>更高的Cs

HigherQfactorresultsinlargerFoprangeCharacteristicimpedancehastobelowerforhigherQandgivenload=>higherCs

-低Q因數(shù)會(huì)造成調(diào)壓能力的下降！

LowQfactorcancausethelossofregulationcapability!

-在Q值很低的情況下，LLC增益特性退化到SRC。

LLCgaincharacteristicsaredegradedtotheSRCforverylowQvalues.0.0000.0500.1000.1500.2000.2501.00E+041.00E+051.00E+06頻率[Hz]Gain[-]Q=2Q=3Q=4n=8,Ls/Lm=6,Q=parameter,Rload=2.4WGminGmaxDf@Q=4Df@Q=3Neededgainsband實(shí)現(xiàn)滿負(fù)載穩(wěn)壓時(shí)所需的增益分布帶forfullloadregulation滿載時(shí)的Q和k因數(shù)優(yōu)化FullLoadQandkFactorsOptimization第23頁/共55頁k=Lm/Ls比決定了Lm

中存儲(chǔ)多少能量。Thek=Lm/LsratiodictateshowmuchenergyisstoredintheLm.更高的k值將造成磁化電流和變換器增益的降低Higherkwillresultinthelowermagnetizingcurrentandgainoftheconverter.-K因數(shù)更高，則所需的調(diào)節(jié)頻率范圍也越大

Neededregulationfrequencyrangeishigherforlargerkfactor.0.0000.0500.1000.1500.2000.2501.00E+041.00E+051.00E+06頻率[Hz]Gain[-]k=2k=4k=6k=8k=10GmaxGminNeededgainsbandforfullloadregulationDf@k=6Df@k=2n=8,Cs=33nF,Ls=100uH,Lm=parameter,Rload=2.4W滿載時(shí)的Q和k因數(shù)優(yōu)化FullLoadQandkFactorsOptimization第24頁/共55頁在實(shí)踐中，Ls

（集成化的變壓器解決方案中的漏電感）只能在有限的范圍內(nèi)取值，而且由變壓器的構(gòu)造（以滿足所需的功率水平）和匝數(shù)比所決定。

Practically,theLs(i.e.leakageinductanceoftheintegratedtransformerversion)hasonlylimitedrangeofvaluesandisgivenbythetransformerconstruction(forneededpowerlevel)andturnsratio.Q因數(shù)的計(jì)算由所需要的標(biāo)稱工作頻率fs所給出。

TheQfactorcalculationisthengivenbythewantednominaloperatingfrequencyfs.K因數(shù)也必須計(jì)算出來，以確保輸出電壓調(diào)節(jié)率（線電壓和負(fù)載發(fā)生變化）所需的增益。

Thekfactorhastobethencalculatedtoassuregainsneededfortheoutputvoltageregulation(withlineandloadchanges).

在設(shè)定K因數(shù)時(shí)，可以讓變換器在輕負(fù)載時(shí)無法繼續(xù)維持穩(wěn)壓作用——可以輕松地實(shí)現(xiàn)忽略模式，以降低無負(fù)載條件下的功耗。Thekfactorcanbesetinsuchawaythatconverterwontbeabletomaintainregulationatlightloads–skipmodecanbeeasilyimplementedtolowernoloadconsumption.滿載時(shí)的Q和k因數(shù)優(yōu)化FullLoadQandkFactorsOptimization第25頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransformerconstruction第26頁/共55頁Fsw=Fs原邊電流——單諧振電容

PrimaryCurrents–SingleResonantCap

IIN,IDM1ICsVCsIDM2第27頁/共55頁IINICs2VCs2ICs1IDM1IDM2原邊電流——分體諧振電容PrimaryCurrents–SplitResonantCapFsw=Fs第28頁/共55頁單體和分體諧振電容解決方案——24V/10A應(yīng)用Singleandsplitresonantcapacitorsolutions-24V/10Aapplication原邊電流的比較ComparisonofPrimaryCurrents

參數(shù)Parameter單電容SingleCap分體電容SplitCapsICs_Pk2.16A1.08AICs_RMS1.52A0.76AIIN_Pk2.16A1.08AIIN_RMS1.07A0.76A分體式的解決方案可以讓諧振電容的電流降低50％，并讓輸入rms電流降低30％

Splitsolutionoffers50%reductioninresonantcapacitorcurrentand30%reductionininputrmscurrent根據(jù)電流和電壓額定值來選擇諧振電容Selectresonantcapacitor(s)forcurrentandvoltageratings第29頁/共55頁-體二極管僅在死區(qū)時(shí)間（A）中導(dǎo)通

Bodydiodeisconductingduringthedeadtimeonly(A)-MOSFET在余下時(shí)間中導(dǎo)通（B）

MOSFETisconductingfortherestoftheperiod(B)-導(dǎo)通損耗由Qg所決定（在驅(qū)動(dòng)電路而非MOSFET中消耗）

TurnONlossesaregivenbyQg(burnedinthedrivernotinMOSFET)-MOSFET在非零電流狀態(tài)下關(guān)斷＝>關(guān)斷損耗

MOSFETturnsOFFundernon-zerocurrent=>turnOFFlosses原邊開關(guān)元件參數(shù)的確定PrimarySwitchesDimensioningAB第30頁/共55頁MOSFETRMS電流值的計(jì)算MOSFETRMScurrentcalculation-體二極管導(dǎo)通時(shí)間可以忽略Thebodydiodeconductiontimeisnegligible-假定MOSFET電流為半正弦波形

AssumethattheMOSFETcurrenthashalfsinusoidwaveform關(guān)斷電流的計(jì)算TurnOFFcurrentcalculation-假定磁化電流是線性增長的Assumethatthemagnetizingcurrentincreaseslinearly-關(guān)斷損耗（EOFF@IOFF)可以在MOSFET的數(shù)據(jù)表中找到

TurnOFFlosses(EOFF@IOFF)canbefindintheMOSFETdatasheet原邊開關(guān)元件參數(shù)的確定PrimarySwitchesDimensioning第31頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransformerconstruction第32頁/共55頁副邊整流器的設(shè)計(jì)SecondaryRectifierDesign副邊整流器工作在ZCS狀態(tài)下SecondaryrectifiersworkinZCS可能采用的架構(gòu)Possibleconfigurations:a) 推挽結(jié)構(gòu)——提供低電壓/大電流輸出Push-Pullconfiguration–forlowvoltage/highcurrentoutputb) 橋式結(jié)構(gòu)——提供高壓/小電流輸出Bridgeconfiguration–forhighvoltage/lowcurrentoutputc) 橋式結(jié)構(gòu)與2個(gè)副邊繞組的組合——提供互補(bǔ)的輸出電壓Bridgeconfiguration

withtwosecondarywindings–forcomplementaryoutputvoltages優(yōu)點(diǎn)Advantages:與橋式結(jié)構(gòu)相比，二極管壓降減少了一半。

Halfthediodedropscomparedtobridge單體封裝，可以使用成對(duì)加工的雙二極管Singlepackage,dualdiodecanbeused

空間利用率高Spaceefficient缺點(diǎn)：Disadvantages:

需要附加的線圈Needadditionalwinding

更高的整流器擊穿電壓

Higherrectifierbreakdownvoltage

線圈之間需要更好的匹配

Needgoodmatchingbetweenwindings推挽結(jié)構(gòu)Push-PullConfiguration第33頁/共55頁計(jì)算式Equations24V/10A輸出outputRMS二極管電流RMSdiodecurrent

平均二極管電流AVGdiodecurrent

峰值二極管電流Peakdiodecurrent12V/20A輸出output副邊電流計(jì)算——推挽工作

SecondaryCurrentCalculations–Push-Pull

為了簡(jiǎn)化計(jì)算，假設(shè)電流為正弦變化，而且Fop=FsTosimplifycalculations,assumesinusoidalcurrentandFop=Fs第34頁/共55頁計(jì)算式Equations24V/10AVf=0.8V,Rd=0.01Ohm由于正向壓降而帶來的損耗:

Lossesduetoforwarddrop由于動(dòng)態(tài)電阻而帶來的損耗Lossesduetodynamicresistance:12V/20AVf=0.5V,Rd=0.01Ohm計(jì)算式Equation24V/10A12V/20A整流電路損耗——推挽結(jié)構(gòu)

RectifierLosses–Push-Pull

第35頁/共55頁優(yōu)點(diǎn)Advantages:器件額定電流低

Lowervoltagerating-只需一個(gè)繞組Needsonlyonewinding無需實(shí)現(xiàn)繞組間的匹配Nomatchingneededforwindings缺點(diǎn)Disadvantages:-更高的二極管壓降Higherdiodedrops需要4只整流管Needfourrectifiers副邊整流電路——橋式結(jié)構(gòu)

SecondaryRectifiers-BridgeConfiguration

第36頁/共55頁選擇恰當(dāng)?shù)耐負(fù)洌ㄍ仆爝€是橋式）Selectappropriatetopology(push-pullorbridge)計(jì)算出整流元件中的峰值、平均值和RMS值電流Calculaterectifierpeak,AVGandRMScurrent根據(jù)所需要的電流和電壓額定值選用出恰當(dāng)?shù)恼髟electrectifierbasedontheneededcurrentandvoltageratings測(cè)量應(yīng)用中的二極管上的電壓波形，設(shè)計(jì)出吸收網(wǎng)絡(luò)，以限制二極管電壓的過沖，改善其EMI特征（LLC需要“微弱的”吸收網(wǎng)絡(luò)，因?yàn)槎O管工作在ZCS模式下）MeasurethediodevoltagewaveformintheapplicationanddesignsnubbertolimitdiodevoltageovershootandimproveEMIsignature(forLLC“weak”snubberisneededsincediodesoperateinZCSmode)注：Notes:fop<fs

時(shí)，電流紋波增加，電流波形仍然為半“正弦波”，但是在每個(gè)半周期內(nèi)都存在死區(qū)時(shí)間

Thecurrentrippleincreasesforfop<fs,thecurrentwaveformisstillhalf“sinusoidal”butwithdeadtimesbetweeneachhalfperiod對(duì)于低壓和大電流LLC應(yīng)用來說，峰值電流很高——以12V/20A輸出為例：Ipeak=31.4AandIRMS=9.7A！每個(gè)“m”都很關(guān)鍵——PCB布局布線。副邊整流通道應(yīng)該盡可能地對(duì)稱，以確保每個(gè)開關(guān)周期的參數(shù)相一致

ThepeakcurrentisveryhighforlowvoltageandhighcurrentLLCapplications–example12V/20Aoutput:Ipeak=31.4AandIRMS=9.7A!!Each“m”becomescritical-PCBlayout.Thesecondaryrectificationpathsshouldbeassymmetricalaspossibletoassuresameparametersforeachswitchingcycle.副邊整流電路設(shè)計(jì)流程

SecondaryRectifierDesignProcedure第37頁/共55頁輸出電容是唯一的儲(chǔ)能元件

Outputcapacitoristheonlyenergystoragedevice峰值/rms紋波及能量更高Higherpeak/rmsripplecurrentandenergy紋波電流將導(dǎo)致：Ripplecurrentleadsto:輸出電容的ESR所產(chǎn)生的電壓紋波（主要）

VoltageripplecreatedbytheESRofoutputcapacitor(dominant)電容所產(chǎn)生的電壓紋波（次要）

Voltageripplecreatedbythecapacitance(lesscritical)輸出電容參數(shù)的確定OutputCapacitorDimensioning第38頁/共55頁計(jì)算式：Equations:24V/10A例子example

:Cf=5000uF,ESR=6m峰值整流電流Peakrectifiercurrent輸出電壓紋波的峰－峰值OutputvoltageripplepeaktopeakESR造成的輸出紋波分量

ESRComponentofOutputRipple與電流紋波同相，且與頻率無關(guān)Inphasewiththecurrentrippleandfrequencyindependent為保證紋波限制在可接受的范圍之內(nèi)，需要采用低ESR電容LowESRcapacitorsneededtokeeprippleacceptable，成本/性能方面的折中（效率的影響）

Cost/performancetrade-off(efficiencyimpact)電容的RMS電流：CapacitorRMScurrent:ESR造成的功率損耗ESRpowerlosses第39頁/共55頁電容造成的輸出紋波分量

CapacitiveComponentofOutputRipple與電流和頻率不同相，而且與頻率有關(guān)

Outofphasewithcurrentandfrequencydependent由于所選用的電容的量值很大，因此在實(shí)踐中紋波可被忽略

Actualripplenegligibleduetohighvalueofcapacitancechosen計(jì)算式Equation:24V/10A輸出例：outputexample

:Cf=5000uF,Fop=100kHz24V/10A輸出例：outputexample

:Cf=100uF,Fop=100kHz第40頁/共55頁濾波電容的設(shè)計(jì)流程

FilterCapacitorDesignProcedure根據(jù)Io和Vout計(jì)算出整流元件及電容的峰值/rms電流。

CalculatepeakandrmsrectifierandcapacitorcurrentsbasedonIoandVout2.計(jì)算出所需要的ESR值，該值應(yīng)確保輸出紋波低于最大的性能指標(biāo)。

CalculateneededESRvaluethatwillassurethattheoutputripplewillbelowerthanmaximumspecification3.選擇恰當(dāng)?shù)碾娙萜鳎▊儯?yīng)該能承受計(jì)算出的rms電流，而ESR應(yīng)當(dāng)與計(jì)算值一致或更低。

Selectappropriatecapacitor(s)tohandlethecalculatedrmscurrentandhavingcalculatedESRorlower考慮價(jià)格、物理尺寸和瞬態(tài)響應(yīng)等因素。

Factorinprice,physicaldimensionsandtransientresponse5.

檢查電容所造成的紋波分量（對(duì)于足夠高的Cf來說，往往可以忽略）。

Checkthecapacitivecomponentvalueoftheripple(usuallynegligibleforhighenoughCf)注：Notes:副邊整流通路應(yīng)該盡可能對(duì)稱，以保證每個(gè)開關(guān)周期具有一致的參數(shù)。

Thesecondaryrectificationpathsshouldbeassymmetricalaspossibletoassuresameparametersforeachswitchingcycle第41頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransformerconstruction第42頁/共55頁諧振電感的平衡ResonantInductanceBalance例Example:Llk(p-s1)=105uH Llk(p-s2)=115uH

?Llk=10uH

Llk(total)=100uH Lm=600uH Cs=33nF-總的Ls總是受到變壓器的漏電感的影響。

TotalLsisalwaysaffectedbythetransformerleakageinductance-具有集成漏電感的變壓器屬于特殊情況——Ls=LlkSpecialcasefortransformerwithintegratedleakageinductance-Ls=Llk-推挽和多輸出應(yīng)用對(duì)漏電感的平衡性十分敏感。

Pushpullandmult.outputapp.aresensitivetotheleakageinductancebalance參數(shù)Parameter測(cè)量引腳MeasuredbetweenPins副邊引腳定義SecondarypinsconfigurationLlk(p-s1)A-BC-D短路shortD-E開路openLlk(p-s2)A-BC-D開路openD-E短路shortLlk(total)A-BC-D短路shortD-E短路shortLmA-BC-D開路openD-E開路openfs1=85.5kHzfs2=81.7kHz5%差值difference變壓器的漏電感Transformerleakageinductance第43頁/共55頁諧振電感的平衡性ResonantInductanceBalance每個(gè)開關(guān)波形的半周期，串連諧振頻率都不同，這造成了原邊和主副邊的電流不平衡性Seriesresonantfrequencydiffersforeachswitchinghalf-cyclethatresultsinprimaryandmainlysecondarycurrentimbalance副邊電流的峰值出現(xiàn)3A的差異——各對(duì)整流管的功率耗散就不同，而且對(duì)于副邊繞組來說，功率耗散也不同3Adifferenceinthepeaksecondarycurrent–thepowerdissipationisdifferentforeachrectifierfrompairaswellasforthesecondarywindings.第44頁/共55頁諧振電感的平衡性ResonantInductanceBalance在開關(guān)周期的前半周，變換器工作在串連諧振頻率Fs之下，而在開關(guān)周期的第二半周，變換器工作在諧振頻率上。

ConverterworksbelowseriesresonantfrequencyFsfortheonehalfoftheswitchingcycleandintheFsforthesecondhalfoftheswitchingcycle.Iprimary第45頁/共55頁對(duì)于大功率應(yīng)用而言，將原邊繞組串連起來，并將副邊繞組并聯(lián)起來，是一種有吸引力分方法。這樣的結(jié)構(gòu)有望可以通過對(duì)副邊繞組的恰當(dāng)連接，對(duì)變壓器漏電特性的不平衡性形成補(bǔ)償。Forhighpowerapp.itisattractivetoconnectprimarywindingsinseriesandsecondarywindingsinparallel.Thereispossibilitytocompensatetransformerleakageimbalancebyappropriateconnectionofthesecondarywindings:?Llk_total=2*?Llk?Llk_total=0諧振電感的平衡性ResonantInductanceBalance第46頁/共55頁副邊漏感被反射到原邊，從而提高了總的諧振電感值。具有很高的匝數(shù)比的LLC應(yīng)用處于危險(xiǎn)狀態(tài)

Thesecondaryleakageinductanceistransformedtotheprimaryandincreasesthetotalresonantinductancevalue.SituationbecomescriticalfortheLLCapplicationswithhighturnsratios.12V/20A應(yīng)用例applicationexample

:Np=35turns Llk_s1=100nHNs=2x2turns Llk_s2=150nHn=Np/Ns=17.5Ls=110uHLm=630uH?Llk_s=50nH副邊出現(xiàn)50nH的差異，就可能造成Ls出現(xiàn)14%的差異!!!

50nHdifferenceonthesecondarycauses14%differenceofLs!!!諧振電感的平衡性ResonantInductanceBalance第47頁/共55頁變壓器的構(gòu)造和副邊在布局方面的考慮：Transformerconstructionandsecondarylayoutconsiderations:- 采用推挽結(jié)構(gòu)時(shí)，諧振回路參數(shù)可以在每個(gè)開關(guān)周期中發(fā)生變化。這會(huì)導(dǎo)致原邊和副邊的電流出現(xiàn)不平衡。

Resonanttankparameterscanchangeeachswitchinghalfcyclewhenpushpullconfigurationisused.Thiscancausetheprimaryandsecondarycurrentsimbalance.對(duì)于集成了諧振電感的變壓器而言，必須檢查變壓器的制造商給如何保證漏電感指標(biāo)。所有短路的副邊繞組是不相關(guān)的。特定的漏電感值可以不同。

Forthetransformerwithintegratedresonantinductance,ithastobecheckedhowthetransformermanufacturerspecifiestheleakageinductance.Specificationforallsecondarywindingsshortedisirrelevant.Theparticularleakageinductancevaluescandiffer.- 將更多的變壓器組合使用，將其原邊繞組串連起來并將其副邊繞組并聯(lián)，則通過恰當(dāng)?shù)母边吚@組連接可以補(bǔ)償漏電感的不對(duì)稱性。

Whenusingmoretransformerswithprimarywindingsinseriesandsecondarywindingsinparalleltheleakageinductanceasymmetrycanbecompensatedbyappropriatesecondarywindingsconnection.- 副邊漏電感可以造成采用高變壓器匝數(shù)比的應(yīng)用中諧振電感出現(xiàn)顯著的不平衡性。在這種情況下，LLC諧振變換器的副邊的布線就有著關(guān)鍵性影響。

Secondaryleakageinductancecancausesignificantresonantinductanceimbalanceinapplicationswithhightransformerturnsratio.LayoutonthesecondarysideoftheLLCresonantconverteriscriticalinthatcase.諧振電感的平衡性ResonantInductanceBalance第48頁/共55頁議程Agenda為何采用HBLLC變換器WhyanHBLLCconverterHBLLC變換器和諧振回路的構(gòu)形ConfigurationsoftheHBLLCconverterandaresonanttankHBLLC的工作狀態(tài)

OperatingstatesoftheHBLLCHBLLC變換器建模和增益特性HBLLCconvertermodelingandgaincharacteristics原邊電流和諧振電容的參數(shù)確定Primarycurrentsandresonantcapdimensioning副邊整流設(shè)計(jì)和輸出電容參數(shù)的確定Secondaryrectificationdesignandoutputcapdimensioning諧振電感的平衡性Resonantinductancebalance變壓器繞組參數(shù)的確定和變壓器的制作Transformerwindingdimensioningandtransf