外文文献及翻译-sinusoidal pulse width modulation

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1、更多相关参考论文设计文档资源请访问http://www.docin.com/lzj781219本科毕业设计(论文)外文翻译专业：电气工程及其自动化所在学院：电子信息工程学院二零一二年六月24.437PowerElectronicsSinusoidalPulsewidthmodulationTheswitchesinthevoltagesourceinverter(SeeFig.1)canbeturnedonandoffasrequired.Inthesimplestapproach,thetopswitchisturnedonIfturnedonandoffonlyonceineachc

2、ycle,asquarewavewaveformresults.However,ifturnedonseveraltimesinacycleanimprovedhar-monicprofilemaybeachieved.Fig1:SimpleVoltageSourcedInthemoststraightforwardimplementation,generationofthedesiredoutputvoltageisachievedbycomparingthedesiredreferencewaveform(modulatingsignal)withahigh-frequencytri

3、angu-lar‘carrier’waveasdepictedschematicallyinFig.2.Dependingonwhetherthesignalvoltageislargerorsmallerthanthecarrierwaveform,eitherthepositiveornegativedcbusvoltageisappliedattheoutput.Notethatovertheperiodofonetrianglewave,theaveragevoltageappliedtotheloadisproportionaltotheamplitudeofthesignal

4、(assumedconstant)duringthisperiod.Theresultingchoppedsquarewaveformcontainsareplicaofthedesiredwaveforminitslowfre-quencycomponents,withthehigherfrequencycomponentsbeingatfrequenciesofanclosetothecarrierfrequency.Noticethattherootmeansquarevalueoftheacvoltagewaveformisstillequaltothedcbusvoltage,

5、andhence本参考设计材料，包含项目源代码，设计说明书、任务书、报告书以及文献参考翻译等，完整的设计文件及源代码，资料请联系68661508。索要或访问https://shop335357914.taobao.com更多相关参考论文设计文档资源请访问http://www.docin.com/lzj781219thetotalharmonicdistortionisnotaffectedbythePWMprocess.Theharmoniccomponentsaremerelyshiftedintothehigherfrequencyrangeandareautomati-callyf

6、ilteredduetoinductancesintheacsystem.WhenthemodulatingsignalisasinusoidofamplitudeAm,andtheamplitudeofthetriangularcarrierisAc,theratiom=Am/Acisknownasthemodulationindex.Notethatcontrollingthemodulationindexthereforcontrolstheamplitudeoftheappliedoutputvoltage.Withasufficientlyhighcarrierfrequenc

7、y(seeFig.3drawnforfc/fm=21andt=L/R=T/3;T=periodoffunda-mental),thehighfrequencycomponentsdonotpropagatesignificantlyintheacnetwork(orload)duethepresenceoftheinductiveelements.However,ahighercarrierfrequencydoesresultin