外文资料翻译及原文

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1、外文资料翻译及原文From：SwitchingPowerSupplyDesign.ThirdEdition.McGraw-Hill.UsingPowerSemiconductorsinSwitchedModeTopologiesTheelectricenergyisnotnormallyusedintheforminwhichitwasproducedordistributed.Practicallyallelectronicsystemsrequiresomeformofenergyconversion.Adevicethattransferselectricenergyfromagive

2、nsourcetoagivenloadusingelectroniccircuitsisreferredtoasPowerSupply.Atypicalapplicationofapowersupplyunit(PSU)isconvertutilityACvoltageintoregulatedDCvoltagerequiredforelectronicequipment.NowadaysinPSUtheenergyflowiscontrolledwithsemiconductorsthatarecontinuouslyswitchingonanoffwithhighfrequency.Su

3、chdevicesarereferredtoasswitchmodepowersuppliesorSMPS.Theyoffergreaterefficiencycomparedwithlinearsuppliesbecauseaswitchcancontrolenergyflowwithlowlosses:whenaswitchisoff,itblockstheflowofvoltageandcurrent,canberelativelylowinbothstates.SMPSarealsosmallerinsizeandlighterinweightduetothereducedsizeo

4、fpassivecomponentsandlowerheatgeneration.Theindustrytendedtowardminiaturization,advancementsinsemiconductortechnology,aswellasvariousenergyefficiencyregulationshavemade"switch"thedominanttypeofPSRacrosspracticallythefullspectrumofapplications.MostoftheswitchersmanufacturedtodayforACinputapplication

5、sincludeaPFCfrontend.Powersuppliesinthemid–70’s.WeidentifiedtheseasSWITCHMODEproducts.AswitchingpowersupplydesignedusingONSemiconductorcomponentscanrightfullybecalledaSWITCHMODEpowersupplyorSMPS.Ingeneral,SMPScanbeclassifiedintofourtypesaccordingtotheinputandoutputwaveforms:ACin,DCout:rectifier,off

6、-lineconverterinputstageDCin,DCout:voltageconverter,orcurrentconverter,orDCtoDCconverterACin,ACout:frequencychanger,cycloconverter,transformerDCin,ACout:inverterFormanyyearstheworldofpowersupplydesignhasseenagradualmovementawayfromtheuseoflinearpowersuppliestothemorepracticalswitchedmodepowersupply

7、(S.M.P.S.).Thelinearpowersupplycontainsamainstransformerandadissipativeseriesregulator.Thismeansthesupplyhasextremelylargeandheavy50/60Hztransformers,andalsoverypoorpowerconversionefficiencies,bothseriousdr