王串聯(lián)型開關(guān)線性復(fù)合結(jié)構(gòu)包絡(luò)線跟蹤電源中多電平變換器優(yōu)化設(shè)計(jì)

(航空航天大學(xué)，江蘇OptimizedDesignoftheMultilevelConverterinSeries-formSwitch-LinearHybridEnvelope-TrackingPowerSupply(NanjingUniversityofAeronautics&Astronautics,Nanjing :Inmodernradiocommunications,theenvelopeofradiofrequency(RF)signalfeatureswithlargepeaktoaveragepowerratio(PAPR).Thisnecessitatestheadoptionoflinearpoweramplifiers(PAs).InordertoachieveahighefficiencyforlinearPAs,envelopetracking(ET)techniqueisemployed,whichprovidesPAswithasupplyvoltagethattrackstheenvelopeofthetransmittedRFsignalinsteadofaconstantvoltage.Thispaperfocusesontheseries-formswitch-linearhybridETpowersupply,wheretheswitching-modeconverterusesamultilevelconverter.Themethodtoselectthesettingvoltagesunderthepremiseofvaluesandnumberofthevoltagelevelsofthemultilevelconverterareoptimizedusingapreciselossmodelbasedontheprobabilitydensityfunction(PDF)oftheenvelopesignal.Besides,thepulse-blankmethodisproposedtoimprovethesystemefficiencyfurther.Finally,aprototypeisbuiltaimingfortrackingtheenvelopesignalofwidebandcodedivisionmultipleaccess(WCDMA),with5MHzbandwidth,12V~27Voutputvoltage,4Waverageand10Wpeakoutputpower.TheexperimentalresultsshowthattheoutputvoltageoftheETpowersupplytracksthereferenceaccurayandthesystemefficiencycanreach76%.:Envelopetracking,lossmodel,multilevelconverter,optimizeddesign,poweramplifier：放大。包絡(luò)線(EnvelopeTracking,ET)技術(shù)給線性功放提結(jié)構(gòu)包絡(luò)線電源，介紹了其工作原理并給出了各電平之間切換點(diǎn)電平的。為優(yōu)化多電平變換器中電平值及

法進(jìn)一步提高系統(tǒng)的效率。最后，本文以一臺(tái)5MHz帶10W的原理樣機(jī)進(jìn)行實(shí)驗(yàn)驗(yàn)證。實(shí)驗(yàn)結(jié)果驗(yàn)證了所提方案的有效性，電源整體效率為76%。：包絡(luò)線損耗模型多電平變換器優(yōu)化設(shè)計(jì)功相移鍵控(QuadraturePhaseShiftKeying,QPSK)及(QuadratureAmplitudeModulation,QAM)等復(fù)雜的調(diào)制方式[1]，此類調(diào)制方式會(huì)造成射頻(RadioFrequency,RF)輸入信號(hào)的包絡(luò)線幅值不(PeakToAveragePowerRatio,PAPR)RF信AAB類等線性功放(LinearPowerAmplifier,LPA)。然而，LPA在恒壓供LPA效率，一種較為有效的方法是RFLPA供電，如圖1所示。包絡(luò) 供包絡(luò) 供t圖1包絡(luò) 2ET此技術(shù)即為包絡(luò)線(Envelopetracking,ET)技術(shù)[2?3]2ET技術(shù)的原理框圖，其中檢的輸出給LPA供電。ET電源可以大致分為以下三類：?jiǎn)伍_關(guān)變換器結(jié)構(gòu)[4]，多開關(guān)變換器結(jié)構(gòu)[5?7，開關(guān)線性復(fù)合點(diǎn)，已成為主流結(jié)構(gòu)。SLHET電源可分為串聯(lián)和并SLHETRLdET電V1V2Vn；電平vsw去初步擬合輸出電A類放大狀態(tài)，采樣網(wǎng)絡(luò)的輸出與信為了保證Qlin工作性放大狀態(tài)(對(duì)應(yīng)三級(jí)管的線MOS管的飽和區(qū))，vswvo；又因?yàn)榫€從損耗的角度，vswvo。本文在保

相同。但是此方法忽略了RF輸入信號(hào)包絡(luò)線的分布平數(shù)越多，vsw擬合輸出電壓的程度越好，即線性放如前所述，vswRF輸入信號(hào)包絡(luò)線的點(diǎn)電平值相接近，vsw將會(huì)產(chǎn)生短電壓脈沖。本文提本文針對(duì)串聯(lián)型HTF來指導(dǎo)多電平變換器中電平值和電平數(shù)的選取。另5z1~2V40WT串聯(lián)型SLHET+_ vo

<

<…<

=

3SLHET =2,3,…,n)為選通管，Dk為阻斷二極管。為了避 D1BuckBuckn-BuckD1BuckBuckn-Buck__

4

+_+__+_

MOSvDS_b，以虛線形式表示。在分界線上有VGD等于MOS管開啟電壓VGS(th)，因此vDS_b可表示為：vDS_bvGSvGDvGS 兩個(gè)不同的電壓源并聯(lián)，D2至Dn-1分別和SW2

i GS DOvoiDVset2~Vsetn(Vset2<Vset3<…<Vsetn)進(jìn)行比較，其iD

vDS_b D3D3D2 2 Comp33n

………………

vsminvsmax。為了保證在5 whenv when vwhen vvsw

(2kn whenv

A3，v

6N溝道MOSFETR (v ovv QRloss_lin

Vsetkk2,3,n)，根據(jù)上述分析，VsetkVsetkVk-1v

iiD

VsetkvoVset(k+1)(2kn)Vk向負(fù)Vsetk(k2,3n)

)floor(Vsetkvo_min)

vo

7vsw和vo之間不同壓差時(shí)vsw多電平變換器中電平值和電平數(shù)

vo(j)vo_min(j1)

結(jié)合式(7)~(9)Vkk2,3,n)向負(fù)載提

vo(i)V(v whenk

Rij RPjVv

(v when2k

R

ij(V j(v)v V(v whenk 絡(luò)信號(hào)的概率密度分布函數(shù)(ProbabilityDensity

ij(Vsetk Function,PDF)，其用于表征隨機(jī)信號(hào)落在某段區(qū) V2 區(qū)間長(zhǎng)度定義為vPDF可通過下

變換器工作于電流連續(xù)模式(continuousConduction(vM(vx N DV iVinVkD 8WCDMAPDF，其中

LkL感電流有效值irms_Lk分別為：

irms_Qk

1T1Tk0.5i kts kLk2k

vo rms_Qk

1

j(v

ontoff

ij(vo_min

Ploss_lin(vo(i))(vo

因此，系統(tǒng)總損耗Ploss_total

VVk(1D Vkk1,2n)和包絡(luò)信號(hào)PDF F V2 V

irms_LkkRack

RRR

eqk

初始化V1vo_minV2V1+Vn1V1+(n2),Vn=Vin。R

d

4)更新Vn1Vn1，若Vn1Vin d24

4d

步驟3，否則更新Vn2Vn2,Vn1Vn22頻率處的深度。

至V1Vinn1)5)在迭代結(jié)果中查找系統(tǒng)損耗Ploss_total最小時(shí)k

V1=vo_min,V2=V1+λ,YNVn?2=Vn?2+λ,NYYLOOPNPcon_lsPdri_lsPsw_ls，以及二極管的導(dǎo)通損耗PD_ls，分別計(jì)算如下：j(v)v(i) (v con

ij(Vset2)

RLd

dri_lsg_lsk 1n )Vsetk(VV) k-1 k j(V)Vvo(i)(v F ij(v 為選通管的導(dǎo)通電阻；Qg_ls為總的門級(jí)電荷；Vdri_ls為驅(qū)動(dòng)電壓；ton_lstoff_ls分別為開通和關(guān)斷時(shí)間。

結(jié)合式(2)和式(7)，線性放大器的平均損耗 圖9選取最優(yōu)電平值的迭代流程表1 221,20,20.5,318,24,17.5,21,18.5,22.5,416.5,25.5,17,19.5,18.5,26.5,515.6,22.8,26.4,16,18,20,18.5,21,27,615,18,24,27,15.5,17,20.5,23.5,18.5,21,27,28,趨勢(shì)。但是系統(tǒng)的復(fù)雜度隨著電平數(shù)的增加而增加。值有很大概率較低。相應(yīng)的串聯(lián)型SLHET電源的技

10vsw輸入電壓：Vin30輸出電壓范圍：12V~27包絡(luò)信號(hào)帶寬：5表1給出了在不平選擇方法下，線性放大器

V Vinvo_min (k1,2,..., 以線性放大器效率最優(yōu)方法[9]選取電平值可通過最

11(b)所示，且輸出電壓降低的對(duì)于實(shí)際信號(hào)，通常采用標(biāo)幺化的方差(normalizedmeansquareerror,NMSE)[7]VV電平數(shù)n=4較為合適。

(b)上切脈沖消除后圖11上切脈沖消除前后主要波形的對(duì)比圖在容許的范圍之內(nèi)。NMSE的計(jì)算如下：(e

NMSE

(v

oi1

NMSE來衡

21%~2%e(i)e(i)

0f0.032 v 極大值點(diǎn)處。vchop可通過下式計(jì)算：vchopvo_m m

ff0m2NMSE m2

13m為在輸出電壓畸變區(qū)域中總的輸出電壓采樣

表2V2chopV2

通過消除階梯波中存在的下切短電壓脈沖可以2b

2342345

t

t

SMU200A矢量信號(hào)發(fā)生器產(chǎn)生。3切換點(diǎn)電平選取之前(Vsetk=Vk-1vsmax,k=2, (b)下切脈沖消除 圖12下切脈沖消除前后主要波形的對(duì)比Ploss_multi代表C2:vsw[10C1:vref[1C3:vo[10Time:[214SLHET電源原理樣機(jī)

C1:vref[1C2:C1:vref[1C2:vsw[10C3:vo[10Time:[2C2:v[10C1:C2:v[10C1:vref[1C3:vo[10 Time:[2

17(a)

7別為優(yōu)化選取切換點(diǎn)電平前后的效率對(duì)比。由圖可6。Ploss_linearPloss_multiPloss_totalPloss_linearPloss_multiPloss_total23454平416.5,21,25.5,417,19.5,23,419,22.5,26,點(diǎn)電平根據(jù)負(fù)載大小動(dòng)態(tài)的調(diào)整可取得更高的系統(tǒng)效率；基于RF為zARaabFH,AsbeckP,CrippsS,KeningtonPB,PopovicZB,PothecaryN,SevicJF,SokalNO.PoweramplifiersandtransmittersforRFandmicrowave[J].IEEETransactionsonMicrowaveTheoryTechniques,2002,50(3):814826.BondadeR,ZhangY,MaD.Alinear-assisteddc-dchybridpowerconverterforenvelopetrackingRFpoweramplifiers[C].Proc.IEEEECCE,2014:5769-5773.ChinH,AndingZ,YanJJ,DraxlerP,KimballDF,LanfrancoS,AsbeckPM.Digitallyassisteddual-switchhigh-efficiencyenvelopeamplifierforenvelope-trackingbase-stationpoweramplifiers[J].IEEETransactionsonMicrowaveTheoryTechniques,2011,59(11):29432952.HaningtonG,ChenP,AsbeckPM.High-efficiencypoweramplifierusingdynamicpower-supplyvoltageforCDMAapplications[J].IEEETransactionsonMicrowaveTheoryTechniques,1999,48(8):14711476.WuPY,MokPKT.Atwo-phaseswitchinghybridsupplymodulatorforRFpoweramplifierswith9%efficiencyimprovement[J].IEEEJournalofSolid-StateCircuits,2010,45(12):25432556.RodriguezM,Fernandez-MiajaP,RodriguezA,SebastianJ.Amultiple-inputdigitallycontrolledbuckconverterforenvelopetrackingapplicationsinradiofrequencypoweramplifiers[J].IEEETransactionsonPowerElectronics,2010,25(2):369-381.MiajaPF,RodriguezA,SebastianJ.Buckderivedconvertersbasedongalliumnitridedevicesforenvelopetrackingapplications[J].IEEETransactionsonPowerElectronics,2015,30(4):2084–2095.KimballDF,JinhoJ,ChinH,DraxlerP,LanfrancoS,NagyW,LinthicumK,LarsonLE,AsbeckPM.High-efficiency

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