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1、U-140APPLICATIONNOTEAverageCurrentModeControlofSwitchingPowerSuppliesLloydDixonAbstractisnearlyequivalenttoaverageinductorcurrentCurrentmodecontrolasusuallyimplementedcontrol.inswitchingpowersuppliesactuallysensesandInaconventionalswitchingpowersupplycontrolspeakinductorcurrent
2、.Thisgivesrisetoemployingabuckderivedtopology,theinduc-manyseriousproblems,includingpoornoisetorisintheoutput.Currentmodecontrolthenimmunity,aneedforslopecompensation,andisactuallyoutputcurrentcontrol,resultinginpeak-to-averagecurrenterrorswhichtheinherent-manyperformanceadvant
3、ages.Ontheotherlylowcurrentloopgaincannotcorrect.Averagehand,inahighpowerfactorpreregulatorusingcurrentmodecontroleliminatestheseproblemstheboosttopology,theinductorisintheinput.andmaybeusedeffectivelytocontrolcurrentsCurrentmodecontrolthencontrolsinputotherthaninductorcurrent,
4、allowingamuchcurrent,allowingittobeeasilyconformedtobroaderrangeoftopologicalapplication.thedesiredsinusoidalwaveshape.GeneralPerspectivePeakCurrentModeControlProblemsCurrentmodecontrolisatwo-loopsystemPoornoiseimmunity.ThepeakmethodofasshowninthesimpleexampleofFig.1.Theinducto
5、rcurrentcontrolfunctionsbycomparingswitchingpowersupplyinductoris“hidden”theupslopeofinductorcurrent(orswitchwithintheinnercurrentcontrolloop.Thiscurrent)toacurrentprogramlevelsetbythesimplifiesthedesignoftheoutervoltagecon-outerloop-seeFig.1.Thecomparatorturnstrolloopandimprov
6、espowersupplyperfor-thepowerswitchoffwhentheinstantaneousmanceinmanyways,includingbetterdynamics.currentreachesthedesiredlevel.ThecurrentTheobjectiveofthisinnerloopistocontrolrampisusuallyquitesmallcomparedtothethestate-spaceaveragedinductorcurrent,butprogramminglevel,especiall
7、ywhenV,,,,islow.inpracticetheinstantaneouspeakinductorAsaresult,thismethodisextremelysuscepti-currentisthebasisforcontrol.(Switchcurrentbletonoise.Anoisespikeisgeneratedeach--equaltoinductorcurrentduringthe“on”timetheswitchturnson.Afractionofavolttime--isoftensensed.)Iftheinduc
8、torripplecoupledintothecontrolcircuitcancauseittocurre
