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1、M~ESSORSANDMICROS~TEMSELSEVIERMicroprocessorsandMicrosystems20(1996)297-301TechnicalapplicationMicrocontrollerbasedLCRmeterM.A.Atmanand,V.JagadeeshKumarDepartmentofElectricalEngineering,IndianInstituteofTechnology,Madras600036,IndiaReceived19March1995;r
2、evised10May1996AbstractAmicrocontrollerbasedschemeforLCRmeasurementisdescribed.Theunknownelement(aninductororacapacitororaresistor)ismeasuredemployinganonconventionalacbridge.Theelementtobemeasuredformsonearm(side)ofthebridgeandthesecond(series)armismad
3、eupofasimpleresistor.AMultipliertypeDigitaltoAnalogConverter(MDAC),controlledbyamicrocontroller,servesastheothertwoarms.Themicrocontroller,afterobtainingquadratureconditionbetweenthebridgeoutputandoneofthedesignatedbridgevoltages,acquiresthecurrentthrou
4、ghandvoltageacrosstheseriesconnectedresistor.WiththesevaluesandthevalueofdigitalinputtotheMDAC,theparametersofLorCorRvaluesareevaluatedbythemicrocontrolleranddisplayedinappropriatedisplayfields.TheschemewasimplementedusinganInte18751microcontroller.Anov
5、erallaccuracyoftheorderof+1.0%wasachievedfortheprototypewitha12-bitMDAChavinganaccuracyof4-0.2%.Keywords:LCRmeasurement;Microcontroller-application;Quasi-balancedbridge;PSD-application1.Introductionbeendevelopedforaspecificapplicationofthesebridges[7,8]
6、.Measurementofcomponents(inductanceL,Capaci-Toovercometheproblemofbalancinginconven-tanceCorresistanceR)isessentialinmanyfieldsoftionalacbridges,quasibalancingmethodshavebeenelectricalandelectronicsengineering.Severalschemesproposed.Thesequasibalancedbr
7、idge-formsrequireforLCRmeasurementhavebeendevelopedforgeneraladjustmentofonlyonevariableelementandhencecon-aswellasspecificapplications.Thesemethodscanbevergencetothebalancecondition,ingeneral,isobtainednormallygroupedintowithfewsteps.However,inconventi
8、onalquasibalancedbridgeforms,twoindependentquasibalancesare(a)bridgemethodsandobtainedandtheparametersoftheunknownZcom-(b)directmethods.putedtherefrom.Inmostofthesetypesofbridges,bal-Inaclassofdirectmethodsofmeasurements,aknownan