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PhotovoltaicPowerPupplyPinePaveInverterBasedOn68HC908MR16MCUIntroductionWiththegrowingenergycrisisandincreasetheenvironmentalawarenessofmankind,thedevelopmentandutilizationofnewenergyisreceivingincreasingattention.Andsolarenergyasaninexhaustiblesupplyofhighlyefficientnonpollutingenergyhasmorepeopleofallages.Inthispaper,thephotovoltaicpowersystemissinusoidalinvertersuitableforahousehold,especiallyforelectricitywithoutelectricityinremoteareasofthewesternregionofapowersystemusers,asChinaswesterndevelopmentwillbeitsmarketprospectswillbecomemoreandmorebroad.2Structureandprincipleoftheinvertersystem2.1ThebasicstructureofthesystemFirstofall,bythesolararraytothebatterychargingcircuitinordertogetabasicstabilityoftheDCvoltage,andthenbytheinvertercircuitwillbehighfrequencyalternatingcurrentintodirectcurrentreverse,andfinallybythefrequencystepuptransformerandfiltercircuitfilteringinto50Hz,220VsinusoidalACvoltage.ControlofthewholesystemiscompletedbyasinglechipMR16.ThecorepartoftheformationofSPWMwaveandtheoutputACvoltageaccordingtothefeedbackform,composedofsamplingdigitalPIregulatorpart.2.2SinglechipontheMR1668HC908MR16singlechipisalowcost,highperformancesinglechip8.Ithas32kbytesofrewritableflashmemorychipFLASH,with768bytesofRAM,thissystemcompletelyenoughwithadedicatedmotorcontrolfor6channelPWMoutputPWMMCmodules,suitableforinsinglephase,threephaseinverter,atthesametimethemodulewasalsodevotedtotheprotectionFaultFAULTpin4,whenthefaultdoesnotoccurinthecaseofinterruptioncausedbytherapidblockadeofthePWMoutputtoachievethepurposeofprotectionwiththeoptionexternalcrystalclockorinternalclockphaselockedloopclockgeneratormodule,thesystemchosenbytheinternalPLLclockcanproduceaccurate8MHzinternalbusfrequency,soastoensuretheaccuracyofthefrequencyofthesystemwithprogrammableADclock,ADfastestconversiontimeonly2μs,tominimizedisruptionofprogramexecutiontimewithSCIserialcommunicationinterface,canworkinfullduplexorhalfduplexmode,inthissystemcanreliablybecompletedwiththeoutsideworldkeyboardmonitorserialcommunicationsystem.2.3InverterMainCircuitSwitchingdeviceisappropriateforlowpowerdevices,withswitchingspeed,highfrequencycharacteristicsofthepowerMOSFET.SwitchgatedrivesignalfromthesinglechipMR16wavegeneratedbytheSPWMsignaldrivercircuit.FullbridgeinverterSPWMoutputforhighfrequencywave,thestepuptransformerandfilterimmediatelybe220V,50HzstandardACvoltagesinusoidal.2.4SPWMwaveformation68HC908MR16withaspecialsinglechipmotorcontrolcanbeusedtoworkinthreepairsofcomplementarymodeorstandalonemode,including6channelPWMoutputmodulePWMMC.InitializationofthesysteminitsworkinthreepairsofcomplementarypatternsinthesamebridgethatthetwoPWMsignalarmiscomplementary,intheinitializationofdollarstowriteavaluetothePMODHLinordertodeterminethecarrierfrequencythatisswitchingfrequency.RealtimewavePWMpulsewidthcalculationiscompletedbytheinterruptionoftheprocedure,eachPWMMCmodulePCTNHLcountercountstoPMODHLofthevalueofinterruptioncaused.Pre0360°tothesinevaluesstoredinFLASHintoforminagivenregion,eachfailuretotakeasinevalue,aftersomecalculations,Ihaveavalue,besenttoPVALXHLregister,singlechipwillPVALXHLofthevalueofPMODHLafterthevalueintheautomaticgenerationofSPWMsignalsentbythePWMpin.InordertopreventthesamebridgearmofthetwotubesatthesametimethephenomenonofconductionoccurredintheabsenceofsignalgeneratorDEADTIMEinDEADTMwritesaregistervaluetodeterminethedeadtime.Thedesignofthesystemdeadtimefor2.5μs,thecarrierfrequencyto10kHz,including200madetoenlargethevalueofthesinesinetable.Thereare4modulesPWMMCfaultprotectionportFAULT1FAULT4,whentheportwhenhigh,PWMMCinitializationcanbesettoblockinaccordancewiththecorrespondingPWMoutput,thesystemistheuseoftheovercurrentprotectionfunction,Whenovercurrent,itFAULT1homeportinordertoplaceallsixroadblockadePWMport.PWMMCworkthesystemsothatthecenteralignmentmode,inthePWMclockfrequencyof8MHzcarrierunderitsformulaforthecycleCarriercycle1/10kPMODHL1/8M2Therefore,thesystemmustbeinitializedPMODHL0190NotefortheMR16inhexadecimalnotation2.5SystemcontrolstructureThesystemthroughthedigitalPIregulatortocontroltherealizationofregulators.Thecontrolsystemblockdiagramshowninfigure3.ACvoltagefeedbacksignalfromtheADsample,inordertoensureaccuracy,thesystemusessamplingvoltagetransformer.Juststarttosetoutputvoltagefromthesoftstart,softstartisgeneratedatstartupinordertoavoidlargepeakcurrent,softstarttheuseofsuccessiveincrementalincreasestoavoltagerequiredforthemethod,afterthesoftstartvoltageissettocorrespondto220Vvoltagevalues.Inordertoenhancethespeed,thesystemusesafeedforwardcontrolandfeedbackcontrolofthecontrolmethodofcombining.Inordertoenhancetheoutputcharacteristicsofthedynamicsystem,thesystemchangesinaccordancewiththeratioofdeviationofthesizeofcoefficientandintegralcoefficientofthefuzzycontrolmethod,whenthedeviationislarger,theproportioncoefficientandintegralcoefficientisalsolarger,whenthedeviationoftheproportionofsmallcoefficientsandintegralcoefficientsmaller,thusreducingtheovershoot,itiseasytomakethesystemstable,thetotaleliminationoftheintegralsaturationphenomenon,butalsotoenhancetheadaptabilityofthesystem.3SerialCommunicationInordertoenhancethesystemsabilitytoadapttodifferentenvironments,itisnecessarytomonitorandcontrolsystemtomonitorandmodifytheparametersofregulation,thissystemusesaserialcommunicationtechnologykeyboardmonitoringsystemwiththeoutsideworldtocommunicate.Proceduresontheuseofinquirymethodstotheoutsideworldperiodicallysendtestdata,testdataincludingthesolarcellvoltage,chargecurrent,batteryvoltage,DCcurrent,outputvoltage,outputcurrent,heatsinktemperature,whentheeventofthefailureprioritysendfaultsignal,whentheneedtomodifyparametersandmodifydataonthereceptionofthecorrespondingparameters,andusethemethodsofcalibrationandcalibrationtestoftheaccuracyofdatacommunications.MAXIMshardwareasaMAX485interfacechiptoworkinhalfduplexmode,whilethesystemoptocouplerisolationsystemsapproachtoenhanceantiinterferenceabilityandreliability.4SystemsoftwaredesignThemodulardesignofsystemsoftware,includingtheinitializationmodule,theprotectionmodule,regulatormodules,communicationmodules,suchasinterruptionofprogrammodules,inadditiontodisruptionofmodulesoutsidethemainprogramontheremainingmodules,whichwillCompletionofsysteminitializationmainmoduleinitialization,thevariableunit,giventheinitialvalueoftheregisterunit.ProtectionmoduleinaccordancewithvoltageandcurrentsamplevaluestodeterminefaultandthefaultoccursinthePWMoutputoftheblockade.Protection,includingundervoltagebattery,batteryovervoltage,systemoverload,overheatingprotection,includingbatteryvoltage,overvoltageprotectioncanbeachievedsincetherestoration,thatis,thebatteryvoltageisdetectedandreturnedtonormal,thesystemresoftstartandresumenormalwork.Overcurrentprotectionasaresultoftherapidresponsetheyneedtoprotecttheuseofhardware,whentheovercurrentatthetimeoftheblockadeassoonasallthePWMoutput,butalsosealedoffallthedrivingcircuit,onlytoreturntoworkcanbereset,softwarecandeterminewhethertherehasbeenovercurrentprotection.RegulatormoduletocompletethesystemofthePIregulatoroutputvoltageregulation,sothattheoutputvoltagestabilizedat220V,whilesoftstartonthemalso.TheentrancetotheoutputparametersforthesoftstartexportstothedisruptionmoduleMparametersinvolvedinthecalculationofPWMpulsewidth.Throughrealtimeadjustmentofthevalueoftheparametervaluecanbechangedsothattheoutputpulsewidthgiventofollow.InterruptionofprogrammodulestocompletetheissueofSPWMwaveform,ACvoltage,ACcurrentparametersofthesample.InterruptionoftheentranceparametersofPIregulatorfortheoutputparameterM,theparametersinvolvedinthecalculationofpulsewidththatisPVALXHLvaluescalculated,thuschangingthedutycyclewhichregulatestheoutputvoltage.2inaccordancewiththerulesofSPWMsamplingmethods,combinedwiththeinitializationofPWMMCsetformulaforcalculatingrealtimepulsewidthforIsahalfcyclePVALXHLPMODHL/2MSINPTRNegativehalfcyclePVALXHLPMODHL/2MSINPTROnePTRpointertosinetable,SINPTRforthecorrespondingsinevalueofthepointerPTR.Prototypemadeinaccordancewiththeabovethinking,thelasttoberelativelystandard220V,50Hzsinusoidalvoltage,softstartisalsoverystable,itsfrequencyerror≤0.1,theoutputvoltageerrorof≤0.5.Asaresultofthecarrierfrequencyof10kHz,inthetransformerprimarysidetobe20kHzhighfrequencysignalswithoutnoise.Undertheabovementionedcontrolcanensurethesystemloadorasuddenreductioninloadtomaintainoutputvoltagestabilityquickly.Keyboardandmonitorsystemwiththeoutsideworldoftheserialcommunicationgood,strongpracticalityandreliability.
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