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1、附录1外文翻译外文资料Switched-modepowersupplyAswitched-modepowersupply(alsoswitching-modepowersupply,SMPS,orsimplyswitcher)isanelectronicpowersupplyunit(PSU)thatincorporatesaswitchingregulator.Whilealinearregulatormaintainsthedesiredoutputvoltagebydissipatingexcesspowerinap
2、asspowertransistor,theswitched-modepowersupplyswitchesapowertransistorbetweensaturation(fullon)andcutoff(completelyoff)withavariabledutycyclewhoseaverageisthedesiredoutputvoltage.Itswitchesatamuch-higherfrequency(tenstohundredsofkHz)thanthatoftheACline(mains),whic
3、hmeansthatthetransformerthatitfeedscanbemuchsmallerthanoneconnecteddirectlytotheline/mains.Switchingcreatesarectangularwaveformthattypicallygoestotheprimaryofthetransformer;typicallyseveralsecondariesfeedrectifiers,seriesinductors,andfiltercapacitorstoprovidevario
4、usDCoutputswithlowripple.Themainadvantageofthismethodisgreaterefficiencybecausetheswitchingtransistordissipateslittlepowerinthesaturatedstateandtheoffstatecomparedtothesemiconductingstate(activeregion).Otheradvantagesincludesmallersizeandlighterweight(fromtheelimi
5、nationoflowfrequencytransformerswhichhaveahighweight)andlowerheatgenerationduetohigherefficiency.Disadvantagesincludegreatercomplexity,thegenerationofhighamplitude,highfrequencyenergythatthelow-passfiltermustblocktoavoidelectromagneticinterference(EMI),andaripplev
6、oltageattheswitchingfrequencyandtheharmonicfrequenciesthereof.AnoteaboutterminologyAlthoughtheterm"powersupply"hasbeeninusesinceradioswerefirstpoweredfromtheline/mains,thatdoesnotmeanthatitisasourceofpower,inthesensethatabatteryprovidespower.Itissimplyadevicethat(
7、usually)acceptscommercialACpowerandprovidesoneormoreDCoutputs.Itwouldbemorecorrectlyreferredtoasapowerconverter,butlongusagehasestablishedtheterm.ClassificationSMPScanbeclassifiedintofourtypesaccordingtotheinputandoutputwaveforms:ACin,DCout:rectifier,off-lineconve
8、rterinputstageDCin,DCout:voltageconverter,orcurrentconverter,orDCtoDCconverter.ACin,ACout:frequencychanger,cycloconverter,transformerDCin,ACout:inverter
