外文翻译--基于DDS参数可调谐波信号发生器的研究

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1、外文原文：http:/  1 中文 2330 字     毕  业  设  计（论  文）附  件  外  文  文  献  翻  译      学     号：  姓     名：  所在院系：    数理系    专业班级：  指导教师：  原文标题： Research of Parameter Adju

2、stable Harmonic Signal  Generator Based on DDS   2014 年   6   月   10   日  2 2008ISECSInternationalColloquiumonComputing,Communication,Control,andManagement       ResearchofParameter AdjustableHarmonicSignalGeneratorBasedonDDS   LI Wei ZHANGJinbo

3、 CollegeofComputerandInformation CollegeofComputerandInformationEngineering  Engineering HohaiUniversity HohaiUniversity Changzhou,213022,China Changzhou,213022,Chinaliwei_     Abstract  Harmonicsignalgeneratorwhosefrequency,phaseandharmonicproportionareadjustableisdesignedforthe

4、detectingequipmentofpowersystem.TheprincipleofDDSandthedesign requirement are introduced.ThenthealgorithmofROMcompression based onthe symmetry ofsinewaveisexpounded.Finally,usingAlteraFPGA,thedetaildesignofthewholesystemispresentedandtestwaveformsaregiven.Testresultsindicatethatthesystemfulfilsthede

5、signrequirements.   1. Introduction  Anideal power systemsupplies powerwithsinewave,butthepracticalwaveformofpowersupplyoftenhasmanyharmoniccomponents.Thebasicreasonofharmonicisthatthepowersystemsuppliespowertotheelectricalequipmentwithnonlinearcharacteristic.Thesenonlinearloadsfeedhigherh

6、armonicbacktothepowersupply,andmakethewaveformofcurrentandvoltageinpowersystemproduceseriousdistortion. Inthedetectionfieldofpowersystem,standardsignalgeneratorswhichcansimulatethepowerharmonicarehighlyneededtocalibratethepowerdetectingequipment,suchasphasedetector,PDdetector,andsoon.Sotheresearchof

7、parameteradjustableharmonicsignalgeneratorprovides theexactbasis forthestableoperationofpowerdetectingequipment,andhasgreateconomicbenefitandsocialvalue.  2. Principleofdirectdigitalsynthesis  Directdigitalsynthesis(DDS)isanewfrequencysynthesistechnologywhichdirectlysynthesizeswaveformonth

8、ebasisofphase.Usingtherelationshipbetweenphaseandamplitude,thephaseofwaveformis   3 segmented and assignedrelevant addresses. Ineachclockperiod,theseaddresses are  extractedandtherelevantamplitudesaresampled.Theenvelopeofthesesampledamplitudesistheexpectedwaveform.Iftheclockfrequencyiscons

9、tant,thefrequencyofoutputsignalisadjustablewithdifferentextractedstepsofaddresses1.TheprinciplediagramofDDSisshowninFig.1.  Figure1.PrinciplediagramofDDS Intheaboveprinciplediagram,DDSiscomposedofphaseaccumulator,ROMtable,DACandLPF.Ineachclockperiod,theoutputofphaseaccumulatorisaccumulatedwithf

10、requency controlword,andhighL-bitoftheoutput are used as address to querythe ROM table.IntheROM,theseaddressesareconvertedtothesampledamplitudes of  theexpectedwaveform.Then DACconvertsthesampledamplitudestoladderwave.IntheLPF,theladderwaveissmoothed,andtheoutputisthecontinuousanalogwaveform2.

11、Supposethattheclockfrequencyisfc,frequencycontrolwordisK,phaseaccumulatorisN-bit,thenoutputfrequencyisfout=(K/2N)fc,frequencyresolutionisfmin=fc/2N.AccordingtotheNyquistSampleCriterion,outputfrequencyupperlimitisfmax<0.5fc.Becauseofthenon-idealcharacteristicofLPF,outputfrequencyupperlimitofDDSisfmax=0.4fc.  3. Schemedesign  3.1. Designrequirements