Features
Designedfortherequirementsofthecommunicationsindustry
Adoptinginternationaladvancedhigh-frequencyphase-shiftedgeresonancetechnology,ultra-wide-rangepowergridACinput,
Themoduleadoptspowerfactorcorrectiontechnology,whichisefficientandreliable.
FullyautomaticcurrentsharingN+1redundantmodulardesign
Themonitoringsystemrealizestherectifiermodule,feederinput,andbatteryintelligenceReal-timetubemonitoringsystemrealizesrectifiermodule,
feederinput,batteryintelligentreal-timetube
Withmulti-levellightningprotectionmeasures,thesystemhasstrongimpactresistanceandfastdynamicresponse
Completesystemscheme,whichcanbewidelyusedinvariouscommunicationequipmentsupporting
Technology
Optimizationdesignofintelligentdigitalpowersystem
Introducedthemaincharacteristicsanddevelopmentstatusofthedigitalpowersystem,brieflyanalyzedtheperformancecharacteristicsandworkingprinciplesofthevariouschipsthatmakeupthesystem,andfocusedonthecircuitdesignofthedigitalpowersystem.Itprovidesaspecificschemefortherealizationoftheoptimaldesignofthedigitalpowersystem.
Introduction
Switchingpowersuppliesaredevelopinginthedirectionofintelligenceanddigitization.Theintelligentdigitalpowersystemthathasjustcomeoutisattractingpeople'sattentionwithitsexcellentcharacteristicsandcompletemonitoringfunctions.Digitalpowersuppliesprovideintelligentadaptabilityandflexibility,withtheabilitytodirectlymonitor,processandadapttosystemconditions,andcanmeetanycomplexpowerrequirements.Inaddition,thedigitalpowersupplycanalsoensurethelong-termreliabilityofthesystemthroughremotediagnosis,includingfaultmanagement,over-currentprotection,andavoidanceofdowntime.
Features
Mainfeaturesofdigitalpowersystem
Digitalpowersystemhasthefollowingfeatures.
1)Itisanintelligentswitchingpowersupplysystemcomposedofdigitalsignalprocessor(DSP)ormicrocontroller(MCU)asthecoreanddigitalpowerdriverandPWMcontrollerasthecontrolobject.Thetraditionalswitchingpowersupplycontrolledbyamicrocontroller(μPorμC)generallyonlycontrolsthestartupandshutdownofthepowersupply,andisnotatruedigitalpowersupply.
2)Adoptingthe"IntegratedDigitalPower"(FusionDigitalPower)technology,theoptimalcombinationofanaloganddigitalcomponentsintheswitchingpowersupplyisrealized.Forexample,theanalogcomponentusedinthepowerstage,theMOSFETdriver,canbeeasilyconnectedtothedigitalpowercontrollerandrealizevariousprotectionandbiaspowermanagement,andthePWMcontrollerisalsoanumericallycontrolledanalogchip.
3)Highintegration,whichrealizesthepowersystemonchipintegration(Powersystemonchip),integratingalargenumberofdiscretecomponentsintoachiporagroupofchips.
4)Itcangivefullplaytotheadvantagesofdigitalsignalprocessorsandmicrocontrollers,sothatthedesigneddigitalpowersupplycanreachhightechnicalindicators.Forexample,itspulsewidthmodulation(PWM)resolutioncanreach150ps(10-12s),whichisbeyondthereachoftraditionalswitchingpowersupplies.Thedigitalpowersupplycanalsorealizethefunctionsofmulti-phasecontrol,non-linearcontrol,loadcurrentsharingandfaultprediction,whichprovidesconvenientconditionsforthedevelopmentofgreenenergy-savingswitchingpowersupplies.
5)Itisconvenienttoformadistributeddigitalpowersystem.
Developmentstatus
Developmentstatusofdigitalpowersystem
Withthedevelopmentofmodernscienceandtechnologyandthedemandofswitchingpowersupplymarket,Atthebeginningofthe21stcentury,thedevelopmentofdigitalpowersystemsbeganinternationally.InMarch2005,TexasInstruments(TI)announcedthelaunchofinnovativedigitalpowerproducts,whichcannotonlysignificantlyimprovetheperformanceofthepowersystem,butalsogreatlyextenditsservicelife.ThecompanyalsodemonstratedtheFusjonDigitalPowesolutiontoprovethatthedigitalpowersystemcanachievehighperformanceindicatorsanddesignflexibilityataverycompetitivelowcost.
Thesolutionincludesthefollowing3typesofchips:
1)UCD7Kseriesdigitalpowerdriver(includingUCD7100andUCD7201);
2)UCD8KseriesPWMcontrol(IncludingUCD8620andUCD8220);
3)UCD9Kseriesdigitalsignalprocessor(UCD9110/9501).
Theabove-mentionedchipshaveformedaseriesofproductsandwillbeofficiallysoldinthefallof2005.ThisproductsupportspowersystemsfromAClinestoloads,andcanbewidelyusedintelecommunicationsfacilities,computerservers,datacenterpowersystems,anduninterruptiblepowersupplies(UPS).
Basicstructure
2.lDigitalpowerdriver
UCD7100/7201arealldigitalcontrolpowerdriverchips.ThedifferenceisthatUCD7100isasingle-endedoutput,UCD7201isadouble-endedoutput,theratedoutputcurrentis±4A,candriveMosFETswitchpowertube,canbeadaptedtoUCD9110/9501digitalcontroller.Themaincontrollercanmonitoritsoutputcurrent,quicklydetectover-currentfaultsandquicklyturnoffthepowersupply,withadetectioncycleofonly25ns.
TakingUCD7100asanexample,itsinternalblockdiagramisshowninFigure1.
Mainlyincludes3.3Vvoltageregulatorandreferencevoltagesource,trigger,Schmittcomparator,undervoltageshutdowncircuit,controlgate,TrueDrivedriver."TrueDrive"isaproprietarytechnologyofTI.Itisahybridoutputstagecomposedofapull-up/pull-downcircuitcomposedofbipolartransistorsandMOSFETsinparallel.Itsadvantageisstrongdrivingability,normaloutputevenatlowvoltage,andcancontroltheovervoltageandundervoltageprotectionofexternalpowerMOSFETunderextremelylowoutputimpedance.ThepowerMOSFETdoesnotneedtobeconnectedtoaprotectiveSchottkyclampdiode.UCD7100canprovideahighpeakcurrenttothegateoftheMOSTFETwithinafewhundrednstoquicklyturnonthedriver.TheUCD7100'shigh-impedancedigitalinput(IN)canreceivesignalswitha3.3vlogiclevelandamaximumswitchingfrequencyof2MHz.TheSchmidtcomparatorcanisolatetheinternalcircuitfromexternalnoise.IfthePWMoutputofthecontrollerstopsatahighlevelandanover-currentfaultoccurs,thecurrentdetectioncircuitturnsofftheoutputofthedriver,andthesystemcanentertheretrymode.ThroughthewatchdogcircuitinsideDSPorMCU,thechipcanberestarted.The3.3v/lOmAvoltageregulatorinsideUCD7100canbeusedasthepowersupplyofthedigitalcontroller.
2.2PWMcontroller
UCD8220/8620isadouble-endedpush-pullPWMcontrollercontrolledbyDSPorMCU.ThedifferencebetweenthetwoisthatUCD8220canbestartedwithalowvoltageof48V,anda110VhighvoltagestartcircuitisaddedinsideUCD8620.TheinternalblockdiagramofUCD8220isshownasinFig.2.
Mainlyincludes3.3vvoltageregulatorandreferencevoltagesource,pulsewidthmodulator(PWM),drivelogic,push-pulldriver,undervoltageshutdowncircuit,currentlimitingcircuit,currentdetectioncircuit.UCD8220/8620canruninpeakcurrentmodeorvoltagemode,notonlycanprogramthelimitcurrent,butalsooutputalimitcurrentdigitalsignthatcanbemonitoredbythemaincontroller.ThetimingoperatingwaveformofUCD8220/8620isshownasinFig.3.
2.3DigitalSignalProcessor(DSP)
UCD9501isadigitalsignalprocessorspeciallydesignedfordigitalpowersystemsbyTI.ItssimilarproductsincludeTMS320F2808andTMS320F2806.Theymainlycontain100MHz32-bitCPU,clockoscillator,332-bittimers,watchdogcircuit,internal/externalinterruptcontroller,SCIbus,SPIbus,CANbusandICbusinterface,and12PWMsignals.Output,systemcontroller,16channelsand12bits.ADC,16K×16Flash,6K×16SARAM,1K×16ROM.Itusesastandard3.3vinput/outputinterface,whichisfullycompatiblewiththeUCD8Kseries.UsePowerPADTMHTSSOP,andQFNsoftwarepackagecanbeprogrammed.
Circuitdesign
Theintelligentdigitalpowersystemcanbecomposedof6parts:PWM,powerdriver,DSP,interfacecircuit,displayandkeyboard.ThesystemblockdiagramisshownasinFig.4.
ThedigitalsignalprocessorUCD9501inthefigureisconnectedtothekeyboardandthedisplaythroughtheinterfacechip.Theusercannotonlyobservethecurrentpowerparametersfromthedisplay,butalsomodifythepowerparametersatanytimethroughthekeyboard.
Inordertosimplifytheconfiguration,adigitalsignalprocessor(UCD9501)andadigitalcontrolpowerdriver(UCD7100)canalsoformanintelligentdigitalpowersystem.ThecircuitisshowninFigure5.
The+36～72VDCinputvoltageU1obtainedbyACvoltageafterrectificationandfilteringisconnectedtotheprimarywindingofthehigh-frequencytransformer;afterR1andR2aredivided,theyarerespectivelyconnectedtotheanaloginputterminalAN1ofUCD9501AndAN2.TheotherendoftheprimarywindingisconnectedtoapowerMOSFET.R3isthecurrentlimitingresistor.R4isthecurrentsenseresistor.TheoutputvoltageofthebiaswindingisrectifiedandfilteredthroughVD1andC1toobtaina+12vDCbiasvoltage,whichisconnectedtothepowersupplyterminal(UDD)ofUCD7100.The3.3vvoltageoutputbyUCD7100providespowerforUCD9501.ThesecondaryrectifierfiltercircuitiscomposedofVD2,LandC2.VD3isafreewheelingdiode,andUDistheDCoutputvoltage.Thepulsewidthmodulationsignal(PWMA)outputfromUCD9501issenttotheINterminalofUCD7100.Thelimitcurrentflagterminal(CLF)ofUCD7100isconnectedtotheinterruptterminal(INT)ofUCD9501,andthelimitcurrentsettingterminal(ILIM)isconnectedtotheGMTRterminalofUCD9501.Theoutputstagecanbeisolatedfromtheinputstagebyusinganoptocouplerisolationamplifier.
WhenUDD=12V,UCD7100loadcapacitanceCLOAD=10nF,switchingfrequencyf=300kHz,thebiaspowerconsumptionisP=CLOADUDD2=10nF*(12v)2*300kHz=0.432W.BiascurrentI=P/UDD=0.432W/12V=0.036A.
IfUCD7201isused,twoexternalpowerMOSFETscanbedriven.Inaddition,UCD9501andUCD8620canbeusedtoformadigitalpowersystem.
Conclusion
Digitalpowersystemhassignificantadvantagessuchashighintegration,highcostperformance,completepowermanagementfunctions,simpleperipheralcircuits,anduser-orienteddesign.Itcreatesfavorableconditionsforrealizingtheoptimaldesignofintelligentpowersystem.