電力電子技術（PowerElectronicTechnology）Introducebasicideasaboutpowerelectroniccomponentssuchasthyristor（晶閘管）,4kindsofrectifyingcircuit（整流電路）,4kindsofpowerconverterincludingrectifier(AC-DC整流器),inverter[in?v?:t?](DC-AC逆變器),ACvoltageregulator(AC-AC交流調壓器),chopper(DC-DC直流斬波器).['t??p?(r)]Thyristor:ThethyristorisasemiconductordevicewithfourlayersofP-Ntypematerial.ItconductswhentheGatereceivesacurrentpulse.最早出現與主要的一種是硅控整流器（SiliconControlledRectifier，SCR）(positivefeedback)Switchingcharacteristics開Inaconventionalthyristor,onceithasbeenswitchedonbythegateterminal,thedeviceremainslatchedintheon-state(i.e.doesnotneedacontinuoussupplyofgatecurrenttoconduct),providingtheanodecurrenthasexceededthelatchingcurrent(IL).Aslongastheanoderemainspositivelybiased,itcannotbeswitchedoffuntiltheanodecurrentfallsbelowtheholdingcurrent(IH).關AthyristorcanbeswitchedoffiftheexternalcircuitcausestheanodetobecomenegativelybiasedAC-DC（整流）:Arectifierisadevicethatconvertsalternatingcurrent(AC)todirectcurrent(DC).Thereare4kinsofveryimportantrectifier:singlephasehalf-wave（單相半波）,singlephasebridge（單相橋）,threephasehalf-wave（三相半波）,threephasebridge（三相橋）.Inhalfwaverectificationofasingle-phasesupply,eitherthepositiveornegativehalfoftheACwaveispassed,whiletheotherhalfisblocked.Becauseonlyonehalfoftheinputwaveformreachestheoutput,meanvoltageislower.Half-waverectificationrequiresasinglediodeinasingle-phasesupply,orthreeinathree-phasesupply.Rectifiersyieldaunidirectionalbutpulsatingdirectcurrent;half-waverectifiersproducefarmoreripplethanfull-waverectifiers,andmuchmorefilteringisneededtoeliminateharmonicsoftheACfrequencyfromtheoutput.半波整流halfwave橋式全波整流Ifyouarenotusingcenter-tappedtransformer,andonlyonesetofoutputcoil,youneedtousefourdiodesinordertodoafull-waverectifier.令峰值電壓Peakvoltage為Vm，未做濾波filter時的AveragevoltageVdc=0.636Vm，FrequencyofACfrequencyof2timestheoriginal，每個二極管所承受的逆向峰值電壓(PIV,PeakInverseVoltage)值是Vm。此種方式(如圖)稱為橋式整流，這四個二極管合稱為橋式整流器：中心抽頭式Forthesingle-phaseACpower，Ifthetransformeriscenter-tappedtype，Twobacktobackdiodes(cathodeconnectionreferstothecathodeoranodeconnectedtotheanode)mayformafull-waverectifier。未做濾波時的平均Vdc=0.636Vm，頻率為原來頻率2倍。每個二極管PIV值2Vm。Full-waverectificationtodoublethetransformersecondarywinding,lesssotoday.三相橋式整流器。Forathree-phasefull-wavedioderectifier,theideal,no-loadaverageoutputvoltageisIfthyristorsareusedinplaceofdiodes,theoutputvoltageisreducedbyafactorcos(α):Or,expressedintermsofthelinetolineinputvoltage:Where:VLLpeak,thepeakvalueofthelinetolineinputvoltages,Vpeak,thepeakvalueofthephase(linetoneutral)inputvoltages,α,firingangleofthethyristor(0ifdiodesareusedtoperformrectification)TheaboveequationsareonlyvalidwhennocurrentisdrawnfromtheACsupplyorinthetheoreticalcasewhentheACsupplyconnectionshavenoinductance.Inpractice,thesupplyinductancecausesareductionofDCoutputvoltagewithincreasingload,typicallyintherange10–20%atfullload.Theeffectofsupplyinductanceistoslowdownthetransferprocess(calledcommutation)fromonephasetothenext.Asresultofthisisthatateachtransitionbetweenapairofdevices,thereisaperiodofoverlapduringwhichthree(ratherthantwo)devicesinthebridgeareconductingsimultaneously.Theoverlapangleisusuallyreferredtobythesymbolμ(oru),andmaybe2030°atfullload.Withsupplyinductancetakenintoaccount,theoutputvoltageoftherectifierisreducedto:TheoverlapangleμisdirectlyrelatedtotheDCcurrent,andtheaboveequationmaybere-expressedas:Where:Lc,thecommutatinginductanceperphaseId,thedirectcurrent生成交流(這樣的設備被稱為交流發電機)的大多數設備生成三相交流為例，一個汽車交流發電機有六個里面作為為電池充電應用程式的全波整流二極管。可以作為計算的一個理想的全波整流的平均均方根輸出電壓：符號說明:Vdc,Vav-直流輸出電壓，平均電壓Vp-峰值電壓（半波中的）Vrms-輸出的RMS(均方根值)電壓，注;RMS值也稱有效值e=~2.71828Half-waverectificationandfull-waverectifierDCoutputafter,arenotconstantDCvoltage.InordertogeneratestableACpowerrectifierdirectcurrent,theneedforfiltercircuitsmoothingtheoutputvoltage.Thesimplestfiltercircuitistheoutputoftherectifierwithacapacitortostoreelectricalenergy,通常稱為濾波電容，即平滑電容（smoothingcapacitor）。butthesefiltercapacitorcannoteliminate[i?limineit]allripple['r?pl]Three-phasehalf-waverectifiercircuitusing\o"Thyristor"thyristorsastheswitchingelements,ignoringsupplyinductanceThree-phasefull-wavethyristorrectifiercircuitusingacentre-tappedtransformer.中心抽頭變壓器Thisisequivalenttoasix-phasehalf-waverectifier.觸發延遲角α：TriggerDelayAngle）3-phaseACinput,halfandfull-waverectifiedDCoutputwaveformsThree-phaseGraetzbridgerectifieratalpha=0°withoutoverlapThree-phaseGraetzbridgerectifieratalpha=0°withoverlapangleof20°Three-phasecontrolledGraetzbridgerectifieratalpha=20°withoverlapangleof20°Three-phasecontrolledGraetzbridgerectifieratalpha=40°withoverlapangleof20°DC-AC(逆變):Ainverterisadevicethatconvertsdirectcurrent(DC)toalternatingcurrent(AC).itcanbeusedforacmotordrivesandUPS（uninterruptiblepowersupplies）An\o"Uninterruptiblepowersupply"uninterruptiblepowersupply(UPS)usesbatteriesandaninvertertosupplyACpowerwhenmainpowerisnotavailable.Whenmainpowerisrestored,a\o"Rectifier"rectifiersuppliesDCpowertorechargethebatteries.半橋逆變器halfbridgeinverterV1V2turnsonalternately.ACoutputfrequencycanbechangedbychangingtheswitchingfrequencyofv1v2.開關旁一般需要并聯續流\o"二極管"二極管Freewheelingdiode，以便在感性\o"負載"負載時起到續流作用。ifv1,v2turnonatthesametime,dcsourcewillbeshort.全橋逆變器fullbridgeinverter(圖)全橋逆變器由各含兩個開關的兩個橋臂連接成正方形組成，輸出端的兩端分別位于兩組開關的中點，相當于取兩個半橋的電壓差，因此可以得到正負雙向的交流輸出。Diagonal[da???g?n?l]devicealternatelyturn三相橋式逆變器threephasebridgeinverter(圖)t1-6turnsoninturn,delay60degreeintime.Three-phasebridgeinvertercangetasetofequalamplitudeandfrequencyareequal,thephasedifferenceof120°electricalphase.Thereare2typesofinverter:1,Activeinverter（有源逆變）,convertDCtoAC,andsendtheACdirectlytothepowersystem.2,Reactiveinverter（無源逆變）,convertDCtoAC,andsendtheACtoelectricalequipments.AC-AC:ACvoltageregulator（交流調壓）,changetheamplitudeofACvoltage,andthefrequencyarestillthesame.twothyristorsreversedparalledconnectedinseries任一相導通須和另一相構成回路，因此電流通路中至少有兩個晶閘管，應采用雙脈沖或寬脈沖觸發。觸發脈沖順序和三相橋式全控整流電路一樣，為VT1~VT6,依次相差60°。把相電壓過零點定為開通角的起點，三相三線電路中，兩相間導通時是靠線電壓導通的，而線電壓超前相電壓30°，因此角的移相范圍是0°~150°。?根據任一時刻導通晶閘管個數以及半個周波內電流是否連續可將0°~150°的移相范圍分為如下三段√0°≤<60°范圍內，電路處于三個晶閘管導通與兩個晶閘管導通的交替狀態，每個晶閘管導通