Item6Alternatingcurrentconversioncircuit項目六交流變換電路6.1Alternatingcurrentvoltageregulatingcircuit6.1交流調(diào)壓電路TeachingResourcesDatabaseof

NationalVocationalEducationPowerSupplyTechnologyBilingualcourses.Powerelectronicstechnology電力電子技術(shù)交流變換電路：把交流電能的參數(shù)（幅值、頻率、相位）加以轉(zhuǎn)換的電路。ACconversioncircuit:Acircuitthatconvertstheparameters(amplitude,frequency,phase)ofACenergy.交流電力控制電路ACpowercontrolcircuit

交一交變頻電路（直接變頻電路）AC-ACfrequencyconversioncircuit(directfrequencyconversioncircuit)維持頻率不變改變輸出電壓的幅值。Changetheamplitudeoftheoutputvoltagewhilekeepingthefrequencyconstant.

將電網(wǎng)頻率的交流電直接變換成較低頻率的交流電直接變頻的同時也可實現(xiàn)電壓變換。TheACofthepowernetworkfrequencyisdirectlyconvertedtotheACoflowerfrequency,andthevoltageconversioncanberealizedatthesametime.分類Classification6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路3.交流調(diào)壓電路應(yīng)用：ACvoltageregulatingcircuitapplication

電爐的溫度控制

Temperaturecontrolofelectricfurnace燈光調(diào)節(jié)（如舞臺燈光控制）

Lightingcontrolsuchasstagelightingcontrol)異步電機軟起動

Softstartofinductionmotor異步電機調(diào)速Inductionmotorspeedregulation調(diào)節(jié)整流變壓器一次側(cè)電壓Adjustprimarysidevoltageofrectifiertransformer2.交流調(diào)壓的實現(xiàn)方法：通過控制晶閘管在每一個電源周期內(nèi)的導(dǎo)通角的大?。ㄏ辔豢刂疲﹣碚{(diào)節(jié)輸出電壓的大小。ThemethodofACvoltageregulation:bycontrollingthesizeofthethyristorconductionAngleineachpowercycle(phasecontrol)toadjustthesizeoftheoutputvoltage.1.交流調(diào)壓電路:是用來變換交流電壓幅值（或有效值）的電路。ACvoltageregulatingcircuit:itisusedtotransformtheACvoltageamplitude(oreffectivevalue)circuit.6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路單相交流調(diào)壓器主電路特點：

SinglephaseACvoltageregulatormaincircuitcharacteristics:T1

、T2

構(gòu)成無觸點交流開關(guān)。T1andT2constituteacontactlessACswitch.1）電源正半周：T1觸發(fā)導(dǎo)通，電源的正半周施加到負(fù)載上；Positivehalfcycleofpowersupply:T1triggertoturnon,thepositivehalfcycleofpowersupplyisappliedtotheload;2）電源負(fù)半周：T2觸發(fā)導(dǎo)通，電源負(fù)半周便加到負(fù)載上；Powersupplynegativehalfcycle:T2triggeron,powersupplynegativehalfcyclewillbeaddedtotheload;3）電源電壓過零：T1

、T2交替觸發(fā)導(dǎo)通，電源電壓全部加到負(fù)載；Powersupplyvoltagezerocrossing:T1,T2alternatelytriggeron,powersupplyvoltageisalladdedtotheload;4）關(guān)斷T1

、T2

：電源電壓不能加到負(fù)載上。TurnoffT1andT2:thepowersupplyvoltagecannotbeaddedtotheload.圖1單向交流調(diào)壓器電路Figure1one-wayACvoltageregulatorcircuit單向交流電壓電路的工作情況與它的負(fù)載性質(zhì)有關(guān)Theoperationofone-wayACvoltagecircuitisrelatedtothenatureofitsload

6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路1）電源電壓正半周：晶閘管T1承受正向電壓，當(dāng)ωt=α?xí)r，觸發(fā)T1使其導(dǎo)通，負(fù)載上得到缺α角的正弦半波電壓；Positivehalfcycleofpowersupplyvoltage:ThyristorT1issubjectedtopositivevoltage.Whenωt=α,itwilltriggerT1toturnon,andsinehalfwavevoltagewithoutαanglewillbeobtainedontheload;2）電源電壓過零：T1管電流下降為零而關(guān)斷；Thepowersupplyvoltagecrosseszero:T1tubecurrentdropstozeroandshutsoff;3）電源電壓負(fù)半周：晶閘管T2承受正向電壓，當(dāng)ωt=π+α?xí)r，觸發(fā)T2使其導(dǎo)通，則負(fù)載上又得到了缺α角的正弦負(fù)半波電壓。持續(xù)這樣控制，在負(fù)載電阻上便得到每半波缺α角的正弦電壓；Negativehalfcycleofpowersupplyvoltage:ThyristorT2issubjectedtopositivevoltage.Whenωt=π+α,T2istriggeredtoturnon,andsinenegativehalfwavevoltagewithoutαAngleisobtainedontheload.Continuedinthisway,asinusoidalvoltageisobtainedacrosstheloadresistoratanAngleminusalphaforeachhalfwave;圖2電阻性負(fù)載時單向交流電壓電路及輸出電壓波形Figure2one-wayACvoltagecircuitandoutputvoltagewaveformunderresistiveload改變α角的大小，便改變了輸出電壓有效值的大小。TheeffectivevalueoftheoutputvoltageischangedbychangingthesizeofthealphaAngle.1.電阻性負(fù)載Resistantload6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路電阻性負(fù)載數(shù)量關(guān)系：Quantityrelationofresistiveload

負(fù)載電壓的有效值Theeffectivevalueoftheloadvoltage

負(fù)載電流的有效值

Theeffectivevalueoftheloadcurrent

調(diào)壓器的效率

Voltageregulatorefficiency總結(jié)：隨著α角的增大，U0逐漸減小。當(dāng)α=π時，U0=0。因此，單相交流調(diào)壓器對于電阻性負(fù)載，其電壓可調(diào)范圍為0～U，控制角α的移相范圍為0～π。Conclusion:U0

decreaseswiththeincreaseofα

angle.Whenα=π,U0=0.Therefore,forresistiveload,thevoltageadjustablerangeofsingle-phaseACregulatoris0~U,andthephaseshiftrangeofcontrolangleαis0~π.圖2電阻性負(fù)載時單向交流電壓電路及輸出電壓波形Figure2one-wayACvoltagecircuitandoutputvoltagewaveformunderresistiveload6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路2.感性負(fù)載（R-L負(fù)載）Inductiveload(R-Lload)圖3帶阻感負(fù)載單向交流調(diào)壓電路及輸出波形Figure3One-wayACvoltageregulatorcircuitwithresistiveloadanditsoutputwaveform

單相交流調(diào)壓器帶阻感負(fù)載時，工作情況同可控整流電路帶電感負(fù)載相似；Single-phaseACvoltageregulatorwithresistiveload,theworkingsituationissimilartothecontrollablerectifiercircuitwithinductiveload;

當(dāng)電源電壓反向過零時，負(fù)載電感產(chǎn)生感應(yīng)電動勢阻止電流的變化，故電流不能立即為零；Whenthepowersupplyvoltagereversezero,theloadinductorproducesaninducedelectromotiveforcetopreventthechangeofcurrent,sothecurrentcannotbeimmediatelyzero;晶閘管的導(dǎo)通角θ的大小與控制角a

、負(fù)載阻抗角φ都有關(guān)。Theconductionangleθofthethyristorisrelatedtothecontrolanglea

andtheloadimpedanceangleφ.6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路

阻感負(fù)載的工作情況分析：Workingconditionanalysisofresistiveload

晶閘管T1導(dǎo)通時，負(fù)載電流IO為：WhenthyristorT1ison,theloadcurrentIois式中intheformula

（θ為晶閘管的導(dǎo)通角θistheconductionAngleofthethyristor）T2導(dǎo)通時，上述關(guān)系完全相同，只是iO相差1800WhenT2ison,therelationshipisexactlythesame,exceptthatthedifferenceiniO

is1800圖4單相交流調(diào)壓器以φ為參變量時θ與a的關(guān)系曲線Figure4Therelationcurvebetweenθandawhenφistakenastheparameterofsingle-phaseACregulator利用邊界條件Usingboundaryconditions：,i0=0可求得θ：

θcanbeobtained6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路1.α>ф，導(dǎo)通角θ?1800，正負(fù)半波電流斷續(xù)。α愈大，θ愈小，波形斷續(xù)愈嚴(yán)重。Theα>ф,conductionangleθ?1800,positiveandnegativehalfwavecurrentisdiscontinuous.Thelargertheαis,thesmallertheθis,themoreseriousthewaveformdiscontinuityis.

負(fù)載電壓的有效值UO、晶閘管電流平均值IdT、晶閘管電流有效值IT以及負(fù)載電流有效值IO分別為：TheeffectivevalueofloadvoltageUo,themeanvalueofthyristorcurrentIdT,theeffectivevalueofthyristorcurrentIT

andtheeffectivevalueofloadcurrentIO

arerespectively調(diào)壓電路的工作情況Operatingconditionofvoltageregulatingcircuit（α>ф

、α=ф、α<ф

）6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路2.α=ф可得：Wecangetθ=1800

此時，晶閘管輪流導(dǎo)通，相當(dāng)于晶閘管被短接。負(fù)載電流處于連續(xù)狀態(tài)，為完全的正弦波。Atthispoint,thethyristorisswitchedoninturn,itisequivalentthatthethyristorbeingshorted.Theloadcurrentisinacontinuousstateandisacompletesinewave

由Since6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路圖5窄脈沖觸發(fā)時的工作波形Figure5Workingwaveformofnarrowpulsetriggered

如果采用窄脈沖觸發(fā)，會出現(xiàn)先觸發(fā)的一只晶閘管導(dǎo)通，而另一只管子在電流下降為零時，因其門極脈沖已經(jīng)消失不能導(dǎo)通的失控現(xiàn)象?；芈分袑⒊霈F(xiàn)很大的直流電流分量，無法維持電路的正常工作。Ifanarrowpulseisused,arunawayphenomenonoccurswhenoneofthethyristorsisactivatedfirst,andtheothertubeisunabletoconductwhenthecurrentdropstozerobecauseitsgatepulsehasdisappeared.TherewillbealargeDCcurrentcomponentintheloop,whichwillnotbeabletomaintainthenormaloperationofthecircuit.解決辦法：采用寬脈沖或脈沖列觸發(fā)，使第二個晶閘管的導(dǎo)通角θ<π。即可使兩個晶閘管的導(dǎo)通角θ=1800達到平衡。解決失控現(xiàn)象。Solution:Useawidepulseorpulsetraintotriggerthesecondthyristor'sconductionangleθ<π.Theconductionangleθ=1800ofthetwothyristorscanbebalanced.Solveout-of-controlphenomena.3.α<фθ＞18006.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路單相交流調(diào)壓電路總結(jié)：Summaryofsingle-phaseACvoltageregulatorcircuit當(dāng)時，并采用寬脈沖觸發(fā)，負(fù)載電壓、電流總是完整的正弦波，改變控制角a,負(fù)載電壓、電流的有效值不變，即電路失去交流調(diào)壓的作用。When,andusingawidepulsetrigger,theloadvoltageandcurrentarealwayscompletesinewave,changethecontrolanglea,theloadvoltageandcurrentoftheeffectivevalueofthesame,thatis,thecircuitlosestheroleofACvoltageregulation.在電感負(fù)載時，要實現(xiàn)交流調(diào)壓的目的，則最小控制角（負(fù)載的功率因數(shù)角）。所以

的移相范圍為φ～1800

Theminimumcontrolangle(thepowerfactorangleoftheload)isrequiredforthepurposeofACvoltageregulationwhentheinductorisloaded.Sothephaseshiftrangeofisφ～1800

6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路圖5窄脈沖觸發(fā)時的工作波形Figure5Workingwaveformofnarrowpulsetriggered

1.三相四線制調(diào)壓電路特點：Characteristicsofthree-phasefour-wirevoltageregulatingcircuit

圖6三相四線制調(diào)壓電路Figure6Three-phasefour-wirevoltageregulationcircuit

1）相當(dāng)于三個獨立的單相交流調(diào)壓電路組合而成的；Equivalenttothecombinationofthreeindependentsingle-phaseACvoltageregulatingcircuits

2）存在中性線，但是3次諧波在中線中的電流大，故中線的導(dǎo)線截面要求與相線一致；Thereisaneutralline,butthecurrentofthethirdharmonicinthecenterlineislarge,sothewirecrosssectionofthecenterlineisrequiredtobeconsistentwiththephaseline;

3）晶閘管的門極觸發(fā)脈沖信號，同相間兩管的觸發(fā)脈沖要互差180°。

Thegatepoleofthethyristortriggersthepulsesignal.Thetriggerpulseofthetwotubeswiththesamephaseshouldbe180°differentfromeachother.

4）各晶閘管導(dǎo)通順序為T1～T6，依次滯后間隔60°；TheconductionsequenceofeachthyristorisT1～T6,andthedelayintervalis60°successively;

5）因存在中線，可采用窄脈沖觸發(fā)；Becausethereisamidline,narrowpulsecanbeusedtotrigger;

6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路

6）該電路工作時，零線上諧波電流較大，含有三次諧波，控制角a=90°時，零線電流甚至和各相電流的有效值接近。若變壓器采用三柱式結(jié)構(gòu)，則三次諧波磁通不能在鐵心中形成通路，產(chǎn)生較大的漏磁通，引起發(fā)熱和噪音。Whenthecircuitworks,theharmoniccurrentonthezerolineislarge,includingthethirdharmonic.WhenthecontrolAngleA=90°,thezerolinecurrentisevenclosetotheeffectivevalueofeachphasecurrent.Ifthetransformeradoptsathree-columnstructure,thethirdharmonicfluxcannotformapathinthecore,resultinginlargefluxleakage,causingheatandnoise.

7）該電路中晶閘管上承受的峰值電壓為

(

為線電壓)。Thepeakvoltageonthethyristorinthecircuitis(isthelinevoltage)6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路圖6三相四線制調(diào)壓電路Figure6Three-phasefour-wirevoltageregulationcircuit1.三相四線制調(diào)壓電路特點：Characteristicsofthree-phasefour-wirevoltageregulatingcircuit

2.三相三線制交流調(diào)壓電路的特點Thecharacteristicsofthree-phasethree-wireACvoltageregulatingcircuit

圖7三相三線制交流調(diào)壓電路Figure7

Three-phasethree-wireACvoltageregulatingcircuit

1）每相電路必須通過另一相形成回路；

Eachphasecircuitmustpassthroughanotherphasetoformaloop;

2）負(fù)載接線靈活，且不用中性線；Theloadwiringisflexible,andnoneutralline

3）晶閘管的觸發(fā)電路必須是雙脈沖，或者是寬度大于600的單脈沖Thetriggercircuitofthethyristormustbeadoublepulse,orasinglepulsewidthgreaterthan600；

4）觸發(fā)脈沖順序和三相全控橋一樣，為T1～T6，依次間隔600；

Thesequenceoftriggeringpulsesisthesameasthatofthree-phasefullycontrolledbridge,T1～T6,withanintervalof600;

5）電壓過零處定為控制角的起點，a角移相范圍是0°～150°；Thevoltagezerocrossingissetasthestartingpointofthecontrolangle,andthephaseshiftrangeofanglea

is0°~150°;

6)輸出諧波含量低,無3次諧波；

Lowoutputharmoniccontent,nothirdharmonicwave;

4626.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路

圖8a=0°時負(fù)載相電壓波形Figure8Loadphasevoltagewaveformwhena=0°

(1)0°≤a<60°時，三個晶閘管導(dǎo)通與兩個晶閘管導(dǎo)通交替，每管導(dǎo)通180°－a

。但a=0°時一直是三管導(dǎo)通，圖8所示a=0°時的負(fù)載電壓波形。When0°≤a<60°,threethyristorsconductalternatelywithtwothyristors,eachconducting180°-a.However,whena=0°,thethreepipesarealwayson.Figure8showstheloadvoltagewaveformwhena=0°.3.三相三線制交流調(diào)壓電路改變α，電路中晶閘管的導(dǎo)電模式Thethree-phasethree-wireACvoltageregulatingcircuitchangesα,theconductionmodeofthethyristorinthecircuit6.1Alternatingcurrentvoltageregulatingcircuit

交流調(diào)壓電路Rangeofthyristorconduction

圖9