電氣工程其自動化專業(yè)英語翻譯

1、電氣工程及其自動化專業(yè)英語翻譯電氣工程及其自動化專業(yè)英語翻譯電氣工程及其自動化專業(yè)英語翻譯精選文檔Semiconductorswitchesareveryimportantandcrucialcomponentsinpowerelectronicsystems.theseswitchesaremeanttobethesubstitutionsofthemechanicalswitches,buttheyareseverelylimitedbythepropertiesofthesemiconductormaterialsandprocessofmanufacturing.在電力電子系統(tǒng)，中半導(dǎo)

2、體開關(guān)是特別重要和重點零件。半導(dǎo)體開關(guān)將要取代機(jī)械開關(guān),但半導(dǎo)體資料的性質(zhì)和生產(chǎn)過程嚴(yán)重限制了他們。Switchinglosses開關(guān)耗資PowerlossesinthepowereletronicconvertersarecomprisedoftheSwitchinglossesandparasiticlosses.電力電子變換器的功率耗資分為開關(guān)耗資和寄生耗資theparasiticlossesaccountforthelossesduetothewindingresistancesoftheinductorsandtransformers,thedielectriclossesofcap

3、acitors,theeddyandthehysteresislosses.寄生損失的繞組電感器、變壓器的阻力、介電耗資的電容器,渦流和磁滯耗資theswitchinglossesaresignificantandcanbemanaged.這個開關(guān)耗資是特別重要的,能夠被辦理。theycanbefurtherdividedintothreecomponents:(a)theon-statelosses,(b)theoff-statelossesandthelossesinthetransitionstates.他們能夠分為三個部分:通態(tài)耗資，斷態(tài)耗資和轉(zhuǎn)換過程中產(chǎn)生的耗資。On-StateLo

4、sses通態(tài)耗資：Theelectricalswitchesconductheavycurrentandhavenonzerovoltageacrosstheswitchintheon-state.Theon-statepowerlossesaregivenbyPon=Usonif.這個電子開關(guān)能導(dǎo)通大電流，而且在通態(tài)時有非零的壓降。這個通態(tài)功率耗資的公式為Pon=Usonif.TheUsonandIfarerespectivelytheswitchvoltageintheon-stateandtheforwardcurrentthroughtheswitch.Forexample,thety

5、picalpowerdiodesandthepowertransistorshavenearly0.5tolvoltacrossthemintheon-state.Theforwardcurrentscanbehundredstothousandsofamperes.Theon-statepowerlossesareverysignificant.此中Uson是通態(tài)時開關(guān)上的壓降，if是流過開關(guān)的電流。比方，典型的功率二極管和功率晶體管有近似0.51伏的通態(tài)壓降。而電流會有數(shù)百到數(shù)千安培。這個通態(tài)耗資特別重要。Off-StateLosses斷態(tài)耗資Theelectricalswitcheswi

6、thstandhighvoltagesandhavenonzeroleakagecurrentthroughtheswitchintheoff-state.Theoff-statepowerlessesaregivenbyPoh=Uoffir在關(guān)斷狀態(tài)時，電子開關(guān)到經(jīng)受得起高電壓，并會有非零的漏電流。斷態(tài)耗資的公式為Poh=Uoffir.TheUsoffandIrarerespectivelythereversebiasvoltageintheoff-stateandthereversecurrentthroughtheswitch.Forexample,thetypicalpowerdiod

7、esandthepowertransistorshavehighreversevoltagesinhundredstothousandsofvoltsandmicroampstomilliampsthroughthemintheoffstate.此中Uoff在斷態(tài)時的反向偏置電壓，ir是流過開關(guān)的反向漏電流。比方，典型的功率二極管和功率晶體管有很高的反向壓降幾百到幾千伏和幾微安到幾毫安的漏電流。.精選文檔Transition-StateLosses耗：Thepracticalswitchingdeviceshavelimitedcapabilitiesofrateofvoltagetransi

8、tionandtherateofcurrentsteering.Thesenonabrupttransitionratesgiverisetopowerlossesintheswitchingdevices.Wewillexaminetheseswitchinglossesintwocasesseparately:theinductiveandcapacitiveloads.在的開關(guān)裝置限制了率和流化率。非突惹起了開關(guān)裝置的功率耗。我開關(guān)耗分兩種狀況：感性和容性。SwitchingwithInductiveLoad接感性的開關(guān)：Theindutorisassumedtobelargesotha

9、tthecurrentthroughitinsteadystateisnearlyconstantIo.Assumethatinitiallytheswitchisoff.Theinductorcurrentis+IoandfreewheelsthroughdiodeV1.Whentheswitchisturnedon,thecurrentthroughtheswitchbeginstobuilduplinearly(anassumption)to+IowhilethediodeV1isstillon.Theondiodehaszerovoltageacrossit(anidealdiode)

10、,hence,thevoltageontheswitchisheldconstantat+Us.Whenthecurrentbuildupisover,thediodeV1ceasestoconductandthevoltageontheswitchrampslinearly(againanassumption)downtozero.假感無大，即在定流感的流是恒定的Io，假定開始開對于關(guān)斷狀。感流+Io性流二極管V1。當(dāng)開關(guān)合后，流流開關(guān)開始成立性上漲+Io此二極管扔通。二極管降0，此開關(guān)兩頭持在+Us當(dāng)流成立達(dá)成后，二極管V1截止，開關(guān)兩頭性降落0。Whentheswitchisturned

11、off,thevoltagebeginstobuilduplinearlyto+uswhilethediodeV1isoff.whilethediodeisoffthecurrentthroughtheswitchequalstheinductorcurrent,whichisconstantI0Aftertheswitchvoltagereachesaero,thecurrentthroughtheswitchbeginstodecreasebelowI0,astheremainingcurrentisnowsteeredthroughthediodeV1whichhasnowturnedo

12、nThecurrentthroughtheswithchrampsdowntozeroultimately.SwitchingwaveformswithinductiveloadareshowninFig.3-1開關(guān)翻開后，開關(guān)兩頭性上漲至Us。此二極管仍截止，二極管截止，流開關(guān)的流相當(dāng)于流感的流，持在恒定的Io。開關(guān)到0，通開關(guān)的流開始上漲到Io以下。此余留的流正向二極管V1，V1通。最通開關(guān)的流降落到0，開關(guān)程的波形的感波形3-1Theswitchinglossesaregivenby:Psw=1/2UsIo.fs開關(guān)耗的公式是Psw=1/2UsIo.fsTheswitchingpower

13、lossesincreaselinearlywiththeswitchingrequencylikeintheresistivecasebutaboutsixtimesmore.Theupperboundontheswitchingfrequencyisalsoabouthalf.開關(guān)功率耗性增添跟著開關(guān)率此的耗要比阻性耗的6倍多。當(dāng)f取最大Psw=1/2UsIo。SwitchingwithcapacitiveLoad開關(guān)接有容性Thecapacitorisassumedtobelargesothatthevoltagethroughisinstedystateisnearlyconstant

14、U0.Assumethatinitiallytheswitchis.精選文檔on,hence,thecuttentthroughtheswitchisIS.ThecapacitorvoltageisUthevoltageacrosstheswitchiszeroandthediodeV1isreversebiased.Whentheswitchisturnedoff,theswitchvoltagebeginstorampupto+U0whilethediodeV1isstilloff.Duringthisbuildup,thecurrentthroughtheswitchisheldcons

15、tantatIs.Whengthevoltagebuildupisover,thediodeV1beginstoconductandthevoltageontheswitchisclampedatU0,andthecurrentthroughtheswitchrampslinearly(againanassumption)downtozero.假定電容器很大，以致在堅固狀態(tài)下其兩頭電壓接近為常數(shù)Uo。假如開關(guān)初始狀態(tài)為閉合，則經(jīng)過開關(guān)的電流為Is。電容器的電壓為Uo開關(guān)兩頭的電壓為零，二極管V1反向偏置。當(dāng)開關(guān)翻開后，開關(guān)兩頭電壓開始上漲到Uo，此時二極管向來關(guān)斷。當(dāng)電壓等于Uo時，二極管V1

16、開始導(dǎo)通而且開關(guān)兩頭電壓被鉗位在Uo。流過開關(guān)的電流線性降落到零。Whentheswitchisclosed,thecurrentbeginstobuilduplinearlytoIswhilethediodeV1isstillon.ThevoltageontheswitchremainsclampedatU0.AftertheswitchcurrentreachesIs,thediodeturnsoffandthevoltageontheswitchbeginstorampdowntozero.當(dāng)開封閉合，電流開始上漲至Is，此時V1仍舊導(dǎo)通，開關(guān)兩頭電位被鉗位在Uo。當(dāng)開關(guān)電流等于Is時，

17、二極管關(guān)斷而且開關(guān)兩頭電壓線性降落至0。Theswitchingpowerlossesinthecaseofcapacitiveloadalsohavesimilardependenceasinthecaseofinductiveloads.當(dāng)開封閉合，電流開始上漲至Is，此時V1仍舊導(dǎo)通，開關(guān)兩頭電位被鉗位在Uo。當(dāng)開關(guān)電流等于Is時，二極管關(guān)斷而且開關(guān)兩頭電壓線性降落至0。Theswitchingpowerlossesinthecaseofcapacitiveloadalsohavesimilardependenceasinthecaseofinductiveloads.接容性負(fù)載狀況下的開關(guān)功率耗資的決定要素與感性負(fù)載狀況下有相像之處。Theswitchinglossescanbeusuallymini