3.3變壓器漏感對整流電路的影響 The influence of transformer leakage inductance on rectifier circuit中英版

Powerelectronicstechnology電力電子技術(shù)3.3Influenceoftransformerleakageinductanceonrectifiercircuit3.3變壓器漏感對整流電路的影響Item3Rectifiercircuit項目三整流電路TeachingResourcesDatabaseof

NationalVocationalEducationPowerSupplyTechnologyBilingualcourses3.3Influenceoftransformerleakageinductanceonrectifiercircuit

變壓器漏感對整流電路的影響前面分析整流電路時，均來考慮包括變壓器漏感在內(nèi)的交流側(cè)電感的影響，認為換相是瞬時完成的。Inthepreviousanalysisoftherectifiercircuit,theinfluenceofACsideinductanceincludingtransformerleakageinductancewasconsidered,andthecommutationwasconsideredtobeinstantaneous.但實際上變壓器繞組總有漏感，該漏感可用一個集中的電感表示，并將其折算到變壓器二次側(cè)。Infact,thereisalwaysleakageinductanceinthetransformerwindings,whichcanbeexpressedbyaconcentratedinductanceandconvertedtothesecondarysideofthetransformer.由于電感對電流的變化起阻礙作用，電感電流不能突變，因此換相過程不能瞬間完成，而是會持續(xù)一段時間。Becausetheinductancehindersthechangeofthecurrent,theinductancecurrentcannotbeabrupt,sothecommutationprocesscannotbecompletedinstantly,butwillcontinueforaperiodoftime.

實際工作中，整流變壓器存在漏抗，晶閘管之間的換流不能瞬時完成，會出現(xiàn)參與換流的兩個晶閘管同時導(dǎo)通的現(xiàn)象，同時導(dǎo)通的時間對應(yīng)的電角度稱為換相重疊角γ。Inpracticalwork,therectifiertransformerhasleakagereactance,andtheconverterbetweenthethyristorscannotbecompletedinstant.Therewillbethephenomenonthatthetwothyristorsparticipatingintheconverterconductatthesametime,andtheelectricalanglecorrespondingtotheconductiontimeiscalledcommutationoverlapangleγ.1、換相重疊角γCommutationoverlapangleYLl為變壓器的每相繞組折合到二次側(cè)的漏抗Llistheleakagereactanceofeachphasewindingofthetransformerconvertedtothesecondaryside

圖1考慮變壓器的漏抗后相控整流電路的等效電路及輸出電壓電流的波形Figure1Theequivalentcircuitandthewaveformofoutputvoltageandcurrentofthephase-controlledrectifiercircuitafterleakagereactanceofthetransformerareconsidered

3.3Influenceoftransformerleakageinductanceonrectifiercircuit

變壓器漏感對整流電路的影響

當ωt１時刻觸發(fā)Ｔ２時，Ｂ相電流不能瞬時上升到Ｉd值，Ａ相電流不能瞬時下降到零，電流換相需要時間tγ，換流重疊角所對應(yīng)的時間為tγ=γ/ω。在重疊角期間，Ｔ１、Ｔ２同時導(dǎo)通，產(chǎn)生一個虛擬電流Ik

，Whenωt１triggersＴ２,theBphasecurrentcannotrisetotheIdvalue,Aphasecurrentcannotfalltozero,thecurrentcommutationrequirestimetγ，thecorrespondingtimefortheoverlapAngleofthecommutationistγ=γ/ω.Duringtheoverlapangle,T1andT2simultaneouslyturnon,producingavirtualcurrentIk,2、工作過程WorkingprocessLl為變壓器的每相繞組折合到二次側(cè)的漏抗Llistheleakagereactanceofeachphasewindingofthetransformerconvertedtothesecondaryside

3.3Influenceoftransformerleakageinductanceonrectifiercircuit

變壓器漏感對整流電路的影響圖1考慮變壓器的漏抗后相控整流電路的等效電路及輸出電壓電流的波形Figure1Theequivalentcircuitandthewaveformofoutputvoltageandcurrentofthephase-controlledrectifiercircuitafterleakagereactanceofthetransformerareconsidered

而整流輸出電壓為Andtherectifieroutputvoltageis由圖可知Thefigureshows2、工作過程Workingprocess3.3Influenceoftransformerleakageinductanceonrectifiercircuit

變壓器漏感對整流電路的影響圖1考慮變壓器的漏抗后相控整流電路的等效電路及輸出電壓電流的波形Figure1Theequivalentcircuitandthewaveformofoutputvoltageandcurrentofthephase-controlledrectifiercircuitafterleakagereactanceofthetransformerareconsidered

在γ期間，直流輸出電壓比uA或uB都小，使輸出電壓波形減少了一塊陰影面積,降低的電壓值為

。Duringγ,theDCoutputvoltageissmallerthaneitherUAorUB,sothattheoutputvoltagewaveformisreducedbyashadowarea,andthereducedvoltagevalueis.式Formula

ud表明：Shows圖中的陰影面積大小為：Thesizeoftheshadowareainthefigureis:2、工作過程Workingprocess3.3Influenceoftransformerleakageinductanceonrectifiercircuit

變壓器漏感對整流電路的影響圖1考慮變壓器的漏抗后相控整流電路的等效電路及輸出電壓電流的波形Figure1Theequivalentcircuitandthewaveformofoutputvoltageandcurrentofthephase-controlledrectifiercircuitafterleakagereactanceofthetransformerareconsidered

圖1考慮變壓器的漏抗后相控整流電路的等效電路Figure1Theequivalentcircuitofphase-controlledrectifyingcircuitaftertheleakagereactanceofthetransformerisconsidered1）換相壓降Uγ

CommutationpressuredropUγ3、參數(shù)計算Parametercalculation上式中是變壓器每相漏感折合到二次則的漏電抗。Intheaboveformula,theleakagereactanceofthetransformerisconvertedtothesecondaryleakageinductanceperphase.在圖2.5.1(a)所示的三相半波可控整流電路中，整流輸出電壓為3相波形組合（即一周期內(nèi)換相3次），每個周期內(nèi)有3個陰影面積，這些陰影面積之和3S除以周期2π，即為換相重疊角期間輸出平均電壓的減少量，稱為換相壓降Uγ。

Inthethree-phasehalf-wavecontrollablerectifiercircuitshowninFigure2.5.1(a),therectifieroutputvoltageisathree-phasewaveformcombination(i.e.,threecommutationtimeswithinonecycle),andtherearethreeshadowareasineachcycle.Thesumoftheseshadowareasis3Sdividedbytheperiod2π,whichisthereductionoftheoutputaveragevoltageduringthecommutationoverlapAngle,calledcommutationvoltagedropUγ.

換相壓降Uγ正比于負載電流Ｉd，它相當于整流電源增加了一項等效電阻，但這個等效內(nèi)阻并不消耗有功功率。CommutationvoltagedropUγisproportionaltotheloadcurrentID,whichisequivalenttoaddinganequivalentresistancetotherectifiersupply,butthisequivalentinternalresistancedoesnotconsumeactivepower.

3.3Influenceoftransformerleakageinductanceonrectifiercircuit變壓器漏感對整流電路的影響上式表明，當Ll或Id增大時，γ將增大；當α增大時，γ減小。必須指出，如果在負載兩端并聯(lián)續(xù)流二極管，將不會出現(xiàn)換流重疊的現(xiàn)象，因為換流過程被續(xù)流二極管的存在所改變。

TheaboveequationshowsthatwhenLLorIDincreases,γwillincrease;Asαincreases,γdecreases.Itmustbenotedthatifthecontinuationdiodesareconnectedinparallelatbothendsoftheload,therewillbenooverlapinthecommutationbecausethecommutationprocessisalteredbythepresenceofthecontinuationdiodes.2、換相重疊角γcommutationoverlapangleY圖1考慮變壓器的漏抗后相控整流電路的等效電路及輸出電壓電流的波形Theequivalentcircuitandthewaveformofoutputvoltageandcurrentofthephase-controlledrectifiercircuitafterleakagereactanceofthetransformerisconsidered3.3Influenceoftransformerleakageinductanceonrectifiercircuit變壓器漏感對整流電路的影響2、換相重疊角γ計算過程Calculationprocessofcommutationoverlapangleγ在圖2.5.1(b)中為便于計算，將坐標原移到Ａ、Ｂ相的自然換流點，設(shè)Infigure2.5.1(b),fortheconvenienceofcalculation,theoriginalcoordinateismovedtothenaturalcommutationpointofphaseAandphaseB,andlet由式(5.5.1)可得

ItcanbeobtainedfromEquation(5.5.1)將上式兩邊同乘以ω得Multiplyω

bothsidesofthisequation從電路工作原理可知，當電感Ll中電流從０變到Id時，正好對應(yīng)ωt從α變到α+γ，將此條件代入式(5.5.5)得Fromtheworkingprincipleofthecircuit,itcanbeseenthatwhenthecurrentintheinductanceLl

changesfrom0toId,itexactlycorrespondstothechangeofωtfromαtoα+γ.ThisconditionissubstitutedintoEquation(5.5.5)toobtain即Namely則換相重疊角為

Thenthecommutationoverlapangleis3.3Influenceoftransformerleakageinductanceonrectifiercircuit變壓器漏感對整流電路的影響2、換相重疊角γ的計算過程Calculationprocessofcommutationoverlapangleγ表1各種整流電路換相壓降和換相重疊角的計算Table1Calculationofcommutationvoltagedropandcommutationoverlapangleofvariousrectifiercircuits3.3Influenceoftransformerleakageinductanceonrectifiercircuit變壓器漏感對整流電路的影響CircuitformSingle-phasefullwaveSinglephasefullyc