5.1 逆變電路的換流方式 The commutation method of the inverter circuit中英版

Item5InverterCircuit項(xiàng)目五逆變電路Themodeofinvertercircuittransfer5.1逆變電路的換流方式TeachingResourcesDatabaseof

NationalVocationalEducationPowerSupplyTechnologyBilingualcourses.Powerelectronicstechnology電力電子技術(shù)Themodeofinvertercircuittransfer5.1逆變電路的換流方式什么是逆變？為什么要逆變？

Whatisinversion?Whyinversion?逆變——把直流電轉(zhuǎn)變成交流電，是整流的逆過(guò)程。Inversion-Turnthedirectcurrentintoalternatingcurrent,isthereverseprocessofrectification.有源逆變電路——交流側(cè)和電網(wǎng)連結(jié)

Activeinvertercircuit-ACsideisconnectedtothegrid應(yīng)用：直流可逆調(diào)速系統(tǒng)、交流繞線轉(zhuǎn)子異步電動(dòng)機(jī)串級(jí)調(diào)速以及高壓直流輸電等Applications:DCreversiblespeedregulationsystem,ACwindingrotorasynchronousmotorcascadespeedregulationandHVDCtransmissionetc..對(duì)于可控整流電路，滿足一定條件就可工作于有源逆變，其電路形式未變，只是電路工作條件轉(zhuǎn)變。既工作在整流狀態(tài)又工作在逆變狀態(tài)，稱(chēng)為變流電路Forthecontrollablerectationcircuit,tomeetcertainconditionscanworkintheactiveinverter,itscircuitformhasnotchanged,butthecircuitworkingconditionschange.Itworksbothintherectitionstateandintheinvertedstate,calledconvertorcircuit實(shí)例：電力機(jī)車(chē)下坡行駛，機(jī)車(chē)的位能轉(zhuǎn)變?yōu)殡娔?，反送到交流電網(wǎng)中去Example:Whenanelectriclocomotiverunsdownhill,thepotentialenergyofthelocomotiveisconvertedintoelectricenergyandsentbacktotheACgrid逆變電路——把直流電逆變成交流電的電路Invertercircuit-acircuitthatconvertsdirectcurrentintoalternatingcurrent無(wú)源逆變——變流電路的交流側(cè)不與電網(wǎng)聯(lián)接，而直接接到負(fù)載。Passiveinverter-theACsideoftheconvertercircuitisnotconnectedtothegrid,butdirectlyconnectedtotheload.換流——電流從一個(gè)支路向另一個(gè)支路轉(zhuǎn)移的過(guò)程，也稱(chēng)為換相。Conversion--Theprocessbywhichanelectriccurrentistransferredfromonebranchtoanother.Alsocalledcommutation.開(kāi)通

Openup：適當(dāng)?shù)拈T(mén)極驅(qū)動(dòng)信號(hào)就可使器件開(kāi)通。Thedevicecanbeopenupbytheappropriategatedrivesignal.關(guān)斷Shutoff：全控型器件可通過(guò)門(mén)極關(guān)斷。Thefullycontrolleddevicecanbeturnedoffbythegate.半控型器件晶閘管，必須利用外部條件才能關(guān)斷。Thethyristorofthesemi-controlleddevicemustbeturnedoffbyexternalconditions.一般在晶閘管電流過(guò)零后施加一定時(shí)間反壓，才能關(guān)斷。Generallyinthethyristorcurrentafterzerotoapplyacertaintimebackpressure,canbeturnedoff.研究換流方式主要是研究如何使器件關(guān)斷。Thestudyofconvertermodeismainlytostudyhowtoturnoffthedevice.Themodeofinvertercircuittransfer5.1逆變電路的換流方式1)器件換流

Devicecommutation利用全控型器件的自關(guān)斷能力進(jìn)行換流。Usetheself-shutdownabilityofthefullycontrolleddeviceforcurrentcommutation.在采用IGBT、電力MOSFET、GTO、GTR等全控型器件的電路中的換流方式是器件換流。InthecircuitusingIGBT,powerMOSFET,GTO,GTRandotherall-controlleddevicesinthecircuitisthedevicetransfer.2)電網(wǎng)換流

Powernetworkcommutation電網(wǎng)提供換流電壓的換流方式。Amethodofcommutationinwhichthegridprovidescommutationvoltage.將負(fù)的電網(wǎng)電壓施加在欲關(guān)斷的晶閘管上即可使其關(guān)斷。不需要器件具有門(mén)極可關(guān)斷能力，但不適用于沒(méi)有交流電網(wǎng)的無(wú)源逆變電路。Applyinganegativegridvoltagetothethyslicalgatetubethatyouwanttoshutdown,thenyoucanshutsitdown.Thedeviceisnotrequiredtohavegate-offcapability,butisnotsuitableforpassiveinvertercircuitswithoutanACgrid.3)

負(fù)載換流

Loadcommutation4)強(qiáng)迫換流

ForcedcommutationThemodeofinvertercircuittransfer5.1逆變電路的換流方式圖1負(fù)載換流電路及其工作波形Fig.1load-commutatedcircuitanditsworkingwaveform?t?t?t?tOOOOiit1b)a)uouoioiouVTiVT1iVT4iVT2iVT3uVT1uVT4負(fù)載換流

LoadcommutationThemodeofinvertercircuittransfer5.1逆變電路的換流方式由負(fù)載提供換流電壓的換流方式。Commutingmodeinwhichthecommutationvoltageisprovidedbytheload.負(fù)載電流的相位超前于負(fù)載電壓的場(chǎng)合，都可實(shí)現(xiàn)負(fù)載換流。Whenthephaseoftheloadcurrentisaheadoftheloadvoltage,theloadcommutationcanberealized.如圖是基本的負(fù)載換流電路，4個(gè)橋臂均由晶閘管組成。Asshowninthefigure,isthebasicload-commutatedcircuit,thefourbridgearmsarecomposedofthyslgates.整個(gè)負(fù)載工作在接近并聯(lián)諧振狀態(tài)而略呈容性。Thewholeloadworksinastateofnearparallelresonanceandslightlycapacitive.直流側(cè)串電感，工作過(guò)程可認(rèn)為id

基本沒(méi)有脈動(dòng)。DCsideseriesinductance,theworkingprocesscanbeconsideredthatidbasicallynopulsation.負(fù)載對(duì)基波的阻抗大而對(duì)諧波的阻抗小。所以u(píng)o接近正弦波。Theimpedanceoftheloadtothefundamentalwaveislargeandtheimpedancetotheharmonicwaveissmall.Souo

isclosetoasinewave.注意觸發(fā)VT2、VT3的時(shí)刻t1必須在uo過(guò)零前并留有足夠的裕量，才能使換流順利完成。PayattentiontothetriggeringtimeofVT2andVT3.t1mustbebeforeUOcrosseszeroandleaveenoughsparecapacitytomakethecommutationcompletesmoothly.由換流電路內(nèi)電容直接提供換流電壓直接耦合式強(qiáng)迫換流通過(guò)換流電路內(nèi)的電容和電感的耦合來(lái)提供換流電壓或換流電流電感耦合式強(qiáng)迫換流設(shè)置附加的換流電路，給欲關(guān)斷的晶閘管強(qiáng)迫施加反壓或反電流的換流方式稱(chēng)為強(qiáng)迫換流。Setupanadditionaltransflowcircuit,forcingthethylocktubetobeshutdowntoapplyareversepressureoranti-currenttransfermodecalledforcedcommutation.通常利用附加電容上所儲(chǔ)存的能量來(lái)實(shí)現(xiàn)，因此也稱(chēng)為電容換流。Thisisusuallyachievedbyusingtheenergystoredonanadditionalcapacitor,soitisalsocalledcapacitivecommutation.分類(lèi)

ClassificationThemodeofinvertercircuittransfer5.1逆變電路的換流方式強(qiáng)迫換流ForcedcommutationThecommutatorvoltageisdirectlysuppliedbythecapacitorintheconvectorcircuitDirectlycoupledforcedcommutationToprovideacommutatorvoltageorcurrentthroughthecouplingofacapacitorandinductorinaconvectorcircuitInductivelycoupledforcedconverter圖2直接耦合式強(qiáng)迫換流原理圖Fig.2Schematicdiagramofdirectlycoupledforcedcommutation圖3電感耦合式強(qiáng)迫換流原理圖Fig.3Schematicdiagramofinductivelycoupledforcedconverter電感耦合式強(qiáng)迫換流

Inductivelycoupledforcedconverter先使晶閘管電流減為零，然后通過(guò)反并聯(lián)二極管使其加上反向電壓。Thethyristorcurrentisreducedtozero,andthenthereversevoltageisappliedtothethyristorthroughthereverseshuntdiode.也叫電流換流。Alsocalledcurrentconversion.Themodeofinvertercircuittransfer5.1逆變電路的換流方式直接耦合式強(qiáng)迫換流

Directlycoupledforcedcommutation當(dāng)晶閘管VT處于通態(tài)時(shí)，預(yù)先給電容充電。當(dāng)S合上，就可使VT被施加反壓而關(guān)斷。WhenthethyristorVTisintheopenstate,thecapacitorischargedinadvance.WhenSisclosed,VTcanbeturnedoffbyapplyingbackpressure.也叫電壓換流。Alsocalledvoltagecommutation.LoadLoadLoadThemodeofinvertercircuittransfer5.1逆變電路的換流方式換流方式總結(jié)

Summaryofconvertermode：器件換流——適用于全控型器件。Devicecommutation-suitableforfullycontrolleddevices.其余三種方式——針對(duì)晶閘管。Theotherthreeways-forthyristors.器件換流和