Encyclopediabusinesscard
Phase-controlledpowersupplyreferstoapowersupplysystemthatusesthyristorsasrectifiers.ItsprincipleisthattheACinputvoltageissteppeddownbyapowerfrequencytransformer,andthenthyristorsareusedforrectification.Inordertomaintainthestabilityoftheoutputvoltage,amorecomplicatedthyristortriggercircuitisrequired.
Thehigh-frequencyswitchingpowersupplyisdirectlyrectifiedbyACinput,andthenhigh-voltageDC(single-phaserectificationisabout300V,Three-phaserectifier(about540V)istransformedintoahigh-frequencysquarewave(above20kHz),andthehigh-frequencysquarewaveissteppeddownbyahigh-frequencytransformerandthenrectifiedandfilteredtoobtainastableDCoutput.
Productadvantages
Thehigh-frequencyswitchingpowersupplyisdirectlyrectifiedbyACinput,andthenpassesthroughaninvertercircuitcomposedofpowerswitchingdevices(powertransistors,MOStubes,IGBTs,etc.)Converthigh-voltagedirectcurrent(about300Vforsingle-phaserectification,about540Vforthree-phaserectification)intohigh-frequencysquarewaves(above20kHz).Thehigh-frequencysquarewavesaresteppeddownbyhigh-frequencytransformerstoobtainlow-voltagehigh-frequencysquarewaves,whicharethenrectifiedandfiltered.StableDCoutput.Comparedwiththephase-controlledregulatedpowersupply,thehigh-frequencyswitchingregulatedpowersupplyhasthefollowingadvantages:
1.Technicalindexadvantages
1)Smallsizeandlightweight.High-frequencytransformershavereplacedlargeandheavyindustrialfrequencytransformers,makingpowersuppliesmoreandmoreminiaturizedandlighterinweight.
2)Thehighoperatingfrequencyenablestheoutputfiltercircuittobeminiaturized.
3)Highpowerfactor.Theformeradoptsanactivepowerfactorcorrectioncircuit,andthepowerfactorcanbeabove0.98,whilethelatterhaswaveformdistortionandseriousinterferencetothepowergrid.
4)Highefficiencyandenergysaving.Theefficiencyoftheformerisgenerally88%~95%.Theefficiencyofthelatterisgenerallybelow70%.
5)Thedynamicresponseisgood,andthecommunicationqualityisimproved.Theformerhasahighoperatingfrequency,anditsdynamicresponsetotheloadandpowergridisfarsuperiortothelatter.
6)Smallripple.Theoutputrippleandnoiseoftheformeraregenerallysmallerthanthelatter,whichhelpstoimprovethequalityofcommunication.
7)Lownoise.Theworkingfrequencyoftheformerisoutsidetherangeofhumanhearing,andtheaudiblenoiseismuchlowerthanthatofthelatter.
8)Convenientexpansion.High-frequencyswitchingpowersuppliesgenerallyadoptamodularstructure,whichismoreconvenientformaintenanceandexpansion.
Ofcourse,high-frequencyswitchingpowersuppliesalsohavesomeshortcomings,suchasradiofrequencyinterference,electromagneticinterferenceisslightlylargerthanphase-controlledpowersupply,etc.,butwiththedevelopmentofcommunicationpowersupplytechnology,theseshortcomingsaregraduallybeingovercome.
2.Intelligentadvantage
Becausethephase-controlledpowersupplywasbornearlierthanthehigh-frequencyswitchingpowersupply,itsdegreeofintelligenceislow.However,thedevelopmentofhigh-frequencyswitchingpowersupplyisnowadayswiththegreatdevelopmentofcomputertechnology,anditsdegreeofintelligenceismuchhigherthanthatofphase-controlledpowersupply.Changesinthemaintenancesystemrequireremotecentralizedmonitoring,unattendedorfewpeopleonduty.Theintelligentcommunicationhigh-frequencyswitchingpowersupplycreatestheconditionsforunattendedorfewpeopleondutyofthecommunicationpowersupply.Theoldphase-controlledpowersupplycannotmeetthisrequirement.