Glossaryintroduction
High-powerswitchingpowersupplyistouseacircuittocontroltheswitchingtubetoconducthigh-speedturn-onandturn-off.Thedirectcurrentisconvertedintohigh-frequencyalternatingcurrentandsuppliedtothetransformerfortransformation,therebygeneratingtherequiredoneormoresetsofvoltages!Thereasonfortheconversiontohigh-frequencyalternatingcurrentisthattheefficiencyofhigh-frequencyalternatingcurrentinthetransformertransformercircuitismuchhigherthan50Hz.Sotheswitchingtransformercanbemadeverysmall,anditisnotveryhotduringwork!Thecostisverylow.Itdoesn’tmakesenseifyoudon’tchange50Hztohigh-frequencyswitchingpowersupply.
Switchingpowersuppliescanberoughlydividedintotwotypes:isolatedandnon-isolated.Theisolatedtypemusthaveaswitchingtransformer,whilethenon-isolatedtypemaynotnecessarilyhave.
Howitworks
1.TheACpowerinputisrectifiedandfilteredintoDC;
2.Theswitchingtubeiscontrolledbyahigh-frequencyPWM(pulsewidthmodulation)signal,andtheDCisaddedtotheprimaryoftheswitchingtransformer;
3.Thehigh-frequencyvoltageisinducedinthesecondaryoftheswitchingtransformer,whichisrectifiedandfilteredandsuppliedtotheload;
4.TheoutputpartisfedbacktothecontrolcircuitthroughacertaincircuittocontrolthePWMdutycycletoachievethepurposeofstableoutput.
5.WhentheACpowerisinput,itgenerallyneedstopassthroughsomethinglikeacurrentcircletofilterouttheinterferenceonthepowergrid,andatthesametimefiltertheinterferenceofthepowersourcetothepowergrid;
6.Whenthepoweristhesame,thehighertheswitchingfrequency,thesmallerthevolumeoftheswitchingtransformer,butthehighertherequirementsfortheswitchingtube;
7.Thesecondaryoftheswitchingtransformercanhavemultiplewindingsorawindingwithmultipletapstogettherequiredoutput;
8.Generally,someprotectioncircuitsshouldbeadded,suchasno-load,short-circuitandotherprotection,otherwiseitmayburntheswitchingpowersupply
Basiccomposition
Thehigh-powerpowersupplyisaslargeasthemainpowercircuit,PWMcontrolcircuit,Thesingle-chipcontrolcircuitandauxiliarypowersupplyarecomposedoffourparts.
Mainpowercircuit
Inrushcurrentlimiter:Limittheinrushcurrentontheinputsidewhenthepoweristurnedon.Inputfilter:Itsfunctionistofiltertheclutterthatexistsinthepowergridandpreventthecluttergeneratedbythemachinefrombeingfedbacktothepowergrid.
Rectificationandfiltering:DirectlyrectifytheACpowerofthegridintoasmootherDCpower.
Inverter:Converttherectifieddirectcurrentintohigh-frequencyalternatingcurrent,whichisthecorepartofthehigh-frequencyswitchingpowersupply.
Outputrectificationandfiltering:Accordingtotheneedsoftheload,provideastableandreliableDCpowersupply.
PWMcontrolcircuit
Ontheonehand,samplesaretakenfromtheoutputterminal,comparedwiththesetvalue,andthentocontroltheinverter,changeitspulsewidthorpulsefrequencytomaketheoutputstable,Ontheotherhand,accordingtothedataprovidedbythetestcircuit,throughtheidentificationoftheprotectioncircuit,acontrolcircuitisprovidedtocarryoutvariousprotectionmeasuresforthepowersupply.
Single-chipcontrolcircuit
Single-chipmicrocomputerusesADCtosampletheoutputvoltageandcurrent,andthroughtheDACoutputtocontrolthechangeofoutputvoltageandcurrent,andmonitortheoperationstatusoftheentirepowersupply,andisresponsibleforcommunicatingwiththecomputercontinuous.
Auxiliarypowersupply
Realizethesoftware(remote)startofthepowersupply,andsupplypowerfortheprotectioncircuitandcontrolcircuit(chipssuchasPWM)andthesingle-chipmicrocomputer.
Mainuses
Switchingpowersupplyproductsarewidelyusedinindustrialautomationcontrol,militaryequipment,scientificresearchequipment,LEDlighting,industrialcontrolequipment,communicationequipment,powerequipment,instrumentation,medicalequipment,Semiconductorrefrigerationandheating,airpurifiers,electronicrefrigerators,liquidcrystaldisplays,LEDlamps,communicationequipment,audio-visualproducts,securitymonitoring,LEDlightbags,computercases,digitalproductsandinstruments,etc.