电气工程其自动化专业英语翻译

1、电气工程及其自动化专业英语翻译电气工程及其自动化专业英语翻译电气工程及其自动化专业英语翻译精选文档Semiconductorswitchesareveryimportantandcrucialcomponentsinpowerelectronicsystems.theseswitchesaremeanttobethesubstitutionsofthemechanicalswitches,buttheyareseverelylimitedbythepropertiesofthesemiconductormaterialsandprocessofmanufacturing.在电力电子系统，中半导

2、体开关是特别重要和重点零件。半导体开关将要取代机械开关,但半导体资料的性质和生产过程严重限制了他们。Switchinglosses开关耗资PowerlossesinthepowereletronicconvertersarecomprisedoftheSwitchinglossesandparasiticlosses.电力电子变换器的功率耗资分为开关耗资和寄生耗资theparasiticlossesaccountforthelossesduetothewindingresistancesoftheinductorsandtransformers,thedielectriclossesofcap

3、acitors,theeddyandthehysteresislosses.寄生损失的绕组电感器、变压器的阻力、介电耗资的电容器,涡流和磁滞耗资theswitchinglossesaresignificantandcanbemanaged.这个开关耗资是特别重要的,能够被办理。theycanbefurtherdividedintothreecomponents:(a)theon-statelosses,(b)theoff-statelossesandthelossesinthetransitionstates.他们能够分为三个部分:通态耗资，断态耗资和转换过程中产生的耗资。On-StateLo

4、sses通态耗资：Theelectricalswitchesconductheavycurrentandhavenonzerovoltageacrosstheswitchintheon-state.Theon-statepowerlossesaregivenbyPon=Usonif.这个电子开关能导通大电流，而且在通态时有非零的压降。这个通态功率耗资的公式为Pon=Usonif.TheUsonandIfarerespectivelytheswitchvoltageintheon-stateandtheforwardcurrentthroughtheswitch.Forexample,thety

5、picalpowerdiodesandthepowertransistorshavenearly0.5tolvoltacrossthemintheon-state.Theforwardcurrentscanbehundredstothousandsofamperes.Theon-statepowerlossesareverysignificant.此中Uson是通态时开关上的压降，if是流过开关的电流。比方，典型的功率二极管和功率晶体管有近似0.51伏的通态压降。而电流会有数百到数千安培。这个通态耗资特别重要。Off-StateLosses断态耗资Theelectricalswitcheswi

6、thstandhighvoltagesandhavenonzeroleakagecurrentthroughtheswitchintheoff-state.Theoff-statepowerlessesaregivenbyPoh=Uoffir在关断状态时，电子开关到经受得起高电压，并会有非零的漏电流。断态耗资的公式为Poh=Uoffir.TheUsoffandIrarerespectivelythereversebiasvoltageintheoff-stateandthereversecurrentthroughtheswitch.Forexample,thetypicalpowerdiod

7、esandthepowertransistorshavehighreversevoltagesinhundredstothousandsofvoltsandmicroampstomilliampsthroughthemintheoffstate.此中Uoff在断态时的反向偏置电压，ir是流过开关的反向漏电流。比方，典型的功率二极管和功率晶体管有很高的反向压降几百到几千伏和几微安到几毫安的漏电流。.精选文档Transition-StateLosses耗：Thepracticalswitchingdeviceshavelimitedcapabilitiesofrateofvoltagetransi

8、tionandtherateofcurrentsteering.Thesenonabrupttransitionratesgiverisetopowerlossesintheswitchingdevices.Wewillexaminetheseswitchinglossesintwocasesseparately:theinductiveandcapacitiveloads.在的开关装置限制了率和流化率。非突惹起了开关装置的功率耗。我开关耗分两种状况：感性和容性。SwitchingwithInductiveLoad接感性的开关：Theindutorisassumedtobelargesotha

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

10、,hence,thevoltageontheswitchisheldconstantat+Us.Whenthecurrentbuildupisover,thediodeV1ceasestoconductandthevoltageontheswitchrampslinearly(againanassumption)downtozero.假感无大，即在定流感的流是恒定的Io，假定开始开对于关断状。感流+Io性流二极管V1。当开关合后，流流开关开始成立性上涨+Io此二极管扔通。二极管降0，此开关两头持在+Us当流成立达成后，二极管V1截止，开关两头性降落0。Whentheswitchisturned

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

12、nThecurrentthroughtheswithchrampsdowntozeroultimately.SwitchingwaveformswithinductiveloadareshowninFig.3-1开关翻开后，开关两头性上涨至Us。此二极管仍截止，二极管截止，流开关的流相当于流感的流，持在恒定的Io。开关到0，通开关的流开始上涨到Io以下。此余留的流正向二极管V1，V1通。最通开关的流降落到0，开关程的波形的感波形3-1Theswitchinglossesaregivenby:Psw=1/2UsIo.fs开关耗的公式是Psw=1/2UsIo.fsTheswitchingpower

13、lossesincreaselinearlywiththeswitchingrequencylikeintheresistivecasebutaboutsixtimesmore.Theupperboundontheswitchingfrequencyisalsoabouthalf.开关功率耗性增添跟着开关率此的耗要比阻性耗的6倍多。当f取最大Psw=1/2UsIo。SwitchingwithcapacitiveLoad开关接有容性Thecapacitorisassumedtobelargesothatthevoltagethroughisinstedystateisnearlyconstant

14、U0.Assumethatinitiallytheswitchis.精选文档on,hence,thecuttentthroughtheswitchisIS.ThecapacitorvoltageisUthevoltageacrosstheswitchiszeroandthediodeV1isreversebiased.Whentheswitchisturnedoff,theswitchvoltagebeginstorampupto+U0whilethediodeV1isstilloff.Duringthisbuildup,thecurrentthroughtheswitchisheldcons

15、tantatIs.Whengthevoltagebuildupisover,thediodeV1beginstoconductandthevoltageontheswitchisclampedatU0,andthecurrentthroughtheswitchrampslinearly(againanassumption)downtozero.假定电容器很大，以致在坚固状态下其两头电压接近为常数Uo。假如开关初始状态为闭合，则经过开关的电流为Is。电容器的电压为Uo开关两头的电压为零，二极管V1反向偏置。当开关翻开后，开关两头电压开始上涨到Uo，此时二极管向来关断。当电压等于Uo时，二极管V1

16、开始导通而且开关两头电压被钳位在Uo。流过开关的电流线性降落到零。Whentheswitchisclosed,thecurrentbeginstobuilduplinearlytoIswhilethediodeV1isstillon.ThevoltageontheswitchremainsclampedatU0.AftertheswitchcurrentreachesIs,thediodeturnsoffandthevoltageontheswitchbeginstorampdowntozero.当开封闭合，电流开始上涨至Is，此时V1仍旧导通，开关两头电位被钳位在Uo。当开关电流等于Is时，

17、二极管关断而且开关两头电压线性降落至0。Theswitchingpowerlossesinthecaseofcapacitiveloadalsohavesimilardependenceasinthecaseofinductiveloads.当开封闭合，电流开始上涨至Is，此时V1仍旧导通，开关两头电位被钳位在Uo。当开关电流等于Is时，二极管关断而且开关两头电压线性降落至0。Theswitchingpowerlossesinthecaseofcapacitiveloadalsohavesimilardependenceasinthecaseofinductiveloads.接容性负载状况下的开关功率耗资的决定要素与感性负载状况下有相像之处。Theswitchinglossescanbeusuallymini