Buck-Boost教育训练

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1、BoostConverter&BuckConverterReporter:JackDate:2009.71.BoostConverter-Principle-Application-Layout2.BuckConverter-Principle-Application-Layout3.CompensationNetworkofPWMConverter4.FunctionofPWMConverterAgendaSwitched-ModePowerSupplyAswitched-modepowersupply,sw

2、itching-modepowersupplyorSMPS,isanelectronicpowersupplyunit(PSU)thatincorporatesaswitchingregulator.theSMPSrapidlyswitchesapowertransistorbetweensaturation(fullon)andcutoff(completelyoff)withavariabledutycyclewhoseaverageisthedesiredoutputvoltage.Theresulting

3、rectangularwaveformislow-passfilteredwithaninductorandcapacitor.ThemainadvantageofthismethodisgreaterefficiencyBoostconverterBuckconverterVoltageControlmodeofBoostConverterBasicblocksoftheboostconverterBoostPowerStageModelingVOUTSWTheswitchSisclosed,resulting

4、inanincreaseintheinductorcurrentTheswitchisopenandtheonlypathofferedtoinductorcurrentisthroughtheD,thecapacitorCandtheloadR.ThisresultsintransferringtheenergyaccumulatedduringtheOn-stateintothecapacitor.On-stateOff-stateBoostConverter-PrincipleWhenaboostconve

5、rteroperatesincontinuousmode,thecurrentthroughtheinductor(IL)neverfallstozero.Rightpictureshowsthetypicalwaveformsofcurrentsandvoltagesinaconverteroperatinginthismode.ContinuousConductionModeWaveformsofcurrentandvoltageinaboostconverteroperatinginanidealconti

6、nuousmodeD=1-VIN/VOUTThedutycycle,DisdefinedasTON/TBoostConverter-PrincipleBoostConverter-ApplicationParameter–ContinuousConductionMode(CCM)VLXVOUTInsomecases,theamountofenergyrequiredbytheloadissmallenoughtobetransferredinatimesmallerthanthewholecommutationp

7、eriod.Inthiscase,thecurrentthroughtheinductorfallstozeroduringpartoftheperiod.Theonlydifferenceintheprincipledescribedrightisthattheinductoriscompletelydischargedattheendofthecommutationcycle(seewaveformsinrightpicture).Waveformsofcurrentandvoltageinaboostcon

8、verteroperatinginanidealdiscontinuousmode.DiscontinuousConductionModeBoostConverter-PrincipleBoostConverter-ApplicationParameter–DiscontinuousConductionMode(DCM)VLXVOUTBoostConverter-Appl