外文翻译--开环PWM控制技术.doc

附录OpenloopPWMcontroltechniquesSinusoidalPWM(SPWM)SPWMtechniqueisoneofthemostpopularmodulationtechniquesamongtheothersappliedinpowerswitchinginverters.InSPWM,asinusoidalreferencevoltagewaveformiscomparedwithatriangularcarrierwaveformtogenerategatesignalsfortheswitchesofinverter.Powerdissipationisoneofthemostimportantissuesinhighpowerapplications.ThefundamentalfrequencySPWMcontrolmethodwasproposedtominimizetheswitchinglosses.Themulti-carrierSPWMcontrolmethodsalsohavebeenimplementedtoincreasetheperformanceofmultilevelinvertersandhavebeenclassifiedaccordingtoverticalorhorizontalarrangementsofcarriersignal.TheverticalcarrierdistributiontechniquesaredefinedasPhaseDissipation(PD),PhaseOppositionDissipation(POD),andAlternativePhaseOppositionDissipation(APOD),whilehorizontalarrangementisknownasphaseshifted(PS)controltechnique.InfactPS-PWMisonlyusefulforcascadedH-bridgesandflyingcapacitors,whilePD-PWMismoreusefulforNPC。Eachofthementionedmulti-carrierSPWMcontroltechniqueshavebeenillustratedinFig.:1,respectively.ThesinusoidalSPWMisthemostwidelyusedPWMcontrolmethodduetomanyadvantagesincludingeasyimplementation,lowerharmonicoutputsaccordingtoothertechniques,andlowswitchinglosses.InSPWMcontrol,ahighfrequencytriangularcarriersignaliscomparedwithalowfrequencysinusoidalmodulatingsignalinananalogorlogiccomparatordevices.Thefrequencyofmodulatingsinusoidalsignaldefinesthedesiredlinevoltagefrequencyattheinverteroutput.Fig.1.Multi-carrierSPWMcontrolstrategies:(a)PD,(b)POD,(c)APOD,(d)PS.Fig.2.AnSPWMcontrolledinverter:(a)completesystem,(b)modulatorblockofinvertermaSwitchingfreq.(Hz)Linevoltages(V)Linecurrents(A)SwitchingangleTHDratios(%THD)LinecurrentLinevoltage10.61000202.816.19309.34107.2520.6200021216.19304.4692.7230.65000202.816.2730.41.7125.2140.610,000206.316.2829.890.885.3650.81000277.121.58308.3081.7260.82000295.722.9429.865.4164.9170.85000293.823.0129.962.9733.6380.810,000303.924.0429.555.0117.28911000351.627.3130.148.2861.211012000355.727.6829.784.1651.78111500037729.2329.673.7832.6612110,0004024.8214.23131.21000385.129.9830.057.9552.68141.22000387.730.2229.924.6048.42maSwitchingfreq.(Hz)Linevoltages(V)Linecurrents(A)SwitchingangleTHDratios(%THD)LinecurrentLinevoltage151.25000389.832.4722.3410.5932.10161.210,000425.933.1526.47.5722.01171.41000399.831.1230.37.4349.37181.42000403.931.5829.934.1446.43191.45000424.432.4728.234.8327.75201.410,000441.333.3623.537.1315.31Table1.CurrentandvoltageTHDanalysisoffullbridgeinverter.Athree-phasefullbridgeinverterandtheSPWMmodulatorthathasbeendesignedtogenerateswitchingsignalsforthree-phasefullbridgeinverterisdepictedinFig.2aandFig.2b.Inthedesignedthree-levelinverter,modulatedSPWMsignalshavebeenusedtocontrolMOSFETswitchesoftheinverter,andTHD（TotalHarmonicDistortion）analysisofoutputvoltageandcurrenthavebeenperformedasseeninTable1.Thedesignparameterswereasfollows；DCvoltage(VDC)=300VModulationindex(mi)=0.6mi1.4Switchingfrequency(fsw)=1kHzfsw10kHzLoadresistance(RL)=5Loadimpedance(L)=5mHRatedpower=10kVAIntheharmonicanalysesofSPWMcontrolledinverterdesignedusingSimulink；thelowestTHDforcurrenthasbeenmeasuredas0.88%whilemodulationindexis0.6andswitchingfrequencyat10kHz.TheTHDforlinevoltagehasbeenmeasuredas5.36%forthesameoperatingconditionsThelinevoltagehasincreasedalmostproportionaltoEq.（1）inover-modulationrange,whileproportionaltoEq.(2)inlinearmodulationrange.InSPWMcontroltechnique,theoutputvoltageisobtainedinlinearmodulationrange,（1）（2）AnotherapplicationhasbeenimplementedusingSPWMtechniquetocontrolafive-levelCHB-MLIasseeninFig3.ThedesignedVSIisbasedonthetopologyofFig.4whichincludesdualH-bridgecellsasshowninFig.5perphasetogenerateafive-leveloutputvoltage.Themaintopologicalcalculationswhichareperformedinitiallyindicatetherequirementsofmodulatorandinverterblocks,andallowobtainingawellpreparedmodulationalgorithmtoincreasetheperforman