intersil开关电源培训补偿环路设计培训tb417.pdf

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1、DesigningStableCompensationNetworksfor®SinglePhaseVoltageModeBuckRegulatorsTechnicalBriefDecember2003TB417.1Author:DougMattinglyAssumptionsOutputFilterThisTechnicalBriefmakesthefollowingassumptions:Theoutputfilterconsistsoftheoutputinductorandalloftheoutputcapacitance.Itisimportanttoinc

2、ludetheDC1.Thepowersupplydesignerhasalreadydesignedtheresistance(DCR)oftheoutputinductorandthetotalpowerstageofthesinglephasebuckconverter.ThelastEquivalentSeriesResistance(ESR)oftheoutputcapacitorsteptothedesignisthecompensationnetwork.bank.TheinputtotheoutputfilteristhePHASEnodeand2.T

3、hedesignerhasatleastabasicunderstandingoftheoutputistheregulatoroutput.Figure3showsthecontrolsystemstheory.equivalentcircuitoftheoutputfilteranditstransferfunction.3.ThedesignerhasabasicunderstandingofBodeplots.LOIntroductionDCRVOUTSynchronousandnon-synchronousbuckregulatorshavePHASEthr

4、eebasicblocksthatcontributetotheclosedloopsystem.COTheseblocksconsistofthemodulator,theoutputfilter,andthecompensationnetworkwhichclosestheloopandESRstabilizesthesystem.ERRORAMPLIFIER+OUTPUTOUTPUT1sESRC+⋅⋅OUTMODULATORGAINFILTER=-----------------------------------------------------------

5、-----------------------------------------------------------------------------FILTER2_1++s⋅⋅()ESR+DCRCOUTs⋅⋅LOUTCOUTREFERENCEFIGURE3.THEOUTPUTFILTERCOMPENSATIONNETWORKThetransferfunctionfortheoutputfiltershowsthewellknowndoublepoleofanLCfilter.ItisimportanttonotethatFIGURE1.BASICBLOCKSOF

6、THEBUCKREGULATORtheESRofthecapacitorbankandtheDCRoftheinductorbothinfluencethedampingofthisresonantcircuit.ItisalsoModulatorimportanttonoticethesinglezerothatisafunctionoftheoutputcapacitanceanditsESR.ThemodulatorisshowninFigure2.Theinputtothemodulatoristheoutputoftheerroramplifier,whic

7、hisusedOpenLoopSystemtocomparetheoutputtothereference.Figure4illustratestheopenloopsystemandpresentstheVINtransferfunction.DRIVEROSCPWMCOMPARATOR∆VOSCPHASELODCRVOUT-+OUTPUTOF-+ERRORAMPLIFIERE/ACODRIVEROUTPUTESRFIGURE2.THEMODULATORTheoutputofthemodulatoristhePHASEnode.ThegainofV