一种基于单片机的新型三相多费率电能表的设计外文文献及翻译.docx

一种基于单片机的新型三相多费率电能表的设计外文文献及翻译.docx

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一种基于单片机的新型三相多费率电能表的设计外文文献及翻译

alwaysadoptsmechanicaltinplatetomeasure.Therearesomeshortcomingsthatthemeasurementprecisionfallswithmachineabrasion,singletimeperiodsettingandstrongmanpower[2].Inthispaper,weproposeanovelmulti-ratethree-phasewatt-hourmeterbasedonAT89LV52.Thismulti-ratethree-phasewatt-hourmeteradoptsAD7752formeasurement.Ithasthecharacteristicswhicharetime-sharingmeasurement,accuratemeasurement,LCDdisplay,automaticmeterreading,flexibletimeperiodsetting,timelyemendation,lowcostandnoveldesign.

II.STRUCTUREANDWORKINGPRINCIPLE

Thenovelmulti-ratethree-phasewatt-hourmeterproposedinthispaperisbaseduponAT89LV52singlechip[3].AT89LV52hastheflashmemorizerwith8kbytes,cryptographicalprogrammemorizerwiththirdclass,RAMwith256bytes,32programmableI/Olines,threetime/counterwith16bitsandatwoclasshaltwithsixvectors.TheinterfacecircuitadoptsI2Cbusunitwhichisa8bitssinglechipwithgoodperformanceandsuitableprice.Thesystemstructurediagramisshowninfigure1.

Figure1.Systemstructurediagram

Theprincipleofthismulti-ratewatt-hourmeterisreadinginthe

multi-ratetimesegmentsusingRS485busandnotinginX25045thentakeovercorrectionalclockwithRS485busandwriteinclockCMOSchipS3530A.Thethree-phaseACvoltageandelectriccurrentpassthroughpotentiometerandmutualinductanceinstrumentrespectivelysoastoproducesmallsignalwhichissenttoAD7752tocompletemeasurement.TheclockCMOSchipS3530AgivesclockinformationpersecondinthecourseofautomaticmoveandanalyzethisclockbelongstowhichperiodoftimeaccordingtoadvanceperiodsoftimesetinX25045thensavetheelectricalenergyinRAMmemorizer

accordingtocorrespondingperiodoftime.WewriteittocorrespondingaddressofX25045whentheelectricalenergyachievesonedegreeinordertomakethemulti-ratemeasurementcometrue.Thiswatt-hourmeterhasfunctionsofclearLCDdisplay,missingphasedetection,burthencontrol,haltelectricitycheckandstorage,automaticmeterreadingandsoon.

III.THEDESIGHOFHARDWARECIRCUIT

A．Electricalenergymeasurement

Thethree-phaseelectricalenergymeasurementisrealizedbythelowconsumeCMOSchipAD7752ofADIcompany.TheinsideofAD7752adoptsdigitalcircuitbesidesADC,filterandmultiplicationcircuitwhichcaneliminatenoiseseffectively.Thesamplingcourseofvoltageandelectriccurrentinthree-phaseACpowersupplyloopisshowninfigure2inwhichIAstandsforvoltagesamplingofAphase.ThesamplingcircuitsofBphaseandCphasearesimilartoAphase.Thepowerafterintegralistransformedtoelectricalpulseforoutput.Thepulseoffan-outCFentersinto

interregnumINT0ofAT89LV52throughphotoelectricityinsulation4N25.CPUmeasurestheelectricalenergy[4].WeadjustthepulsenumberofCFbycombiningthestateofS1andS2.TheconnectionofelectricalenergyandpulseisW=MC.Inwhich,Wistheelectricalenergywiththeunitofkilowatt-hour,Misthetotalpulsenumber,Cisthepulsenumberofammeter.WechooseCequalsto3000thatistosayeverykilowatt-houris3000

pulses.

Figure2.Circuitschematicdiagramofwatt-hourmeter

B．LCDdisplay

TheLCDdisplay[6]adoptsHT1621CMOSchipofHOLTEKCompanyto

achievetwelvebitsdigitaldisplay.HT1621istheLCDdriverswith128segments（32×4）innermemorizer.TheinteriorofHT1621consistsofcontrolandtimecircuits,RAM,LCDdriveandwatchtimer.Ithas

themeritsofsmallvolumeandlowcostsothatitissuittowatt-hourmeter.WeuseserialinterfacewhichonlyhasfourlinesbetweenHT1621andAT89LV52.Thedetailedconnectionisshowninfigure3.P20,P21,P22andP23ofAT89LV52connecttoCS,RD,WRandDATArespectivelywiththeusetorefurbishthedisplayofRAM.HT1621driveCMOSchiphas48nodesinwhichCOM0,COM1,COM2,COM3connecttothecommunalendanddriveoutputofLCDandSG0,SG1,SG2,SG3connecttodriveoutputofeverysegmentrespectively.Inaddition,anadjustableresistanceof20kΩisputbetweenVDDandVLCDtoadjustthedisplaycontrastofLCD.ExperimentshowsthatthecontrastisbetterwithVDD=5VandVLCD=4V.

C．Serialmemorizer

SerialmemorizeradoptslowpowerconsumptionchipX25045ofXICOR

company.IthasthreefunctionswhicharewatchdogtimerWTD,voltagesupervisionandserialmemorizerE2PROMwith512bytes.WTDcanbeset200ms,600msand1400mstimeintervals.ThesoftwareprogramisreadintoX25045.Duringthenormalrunningofprogram,WTDreceivesthetriggersignalintimeintervalsinordertoensurethenormalrunningofprogram.X25045willoutputahighpotentialthroughRESETlineifWTDdoesnotreceivetriggersignalintimeintervals.Thetriggerwatt-hourmeterresetinordertopreventprogramflyingaway.Astheserialmemorize