pwm整流器外文翻译.docx

pwm整流器外文翻译.docx

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pwm整流器外文翻译

ACVoltageandCurrentSensorlessControlof

Three-PhasePWMRectifiers

Dong-ChoonLee,Member,IEEE,andDae-SikLim

1THREE-PHASEPWMRECTIFIERS

ASystemModeling

Fig.1showsthepowercircuitofthethree-phasePWMrectifier.Thevoltageequationsaregivenby

（1）

Fig.1.Three-phasePWMrectifierwithoutac-sidesensors.

where,andarethesourcevoltage,thelinecurrent,andtherectifierinputvoltage,respectivelyandaretheinputresistanceandtheinputinductance,respectively.Whenthepeaklinevoltage,angularfrequency,andinitialphaseanglearegiven,assumingabalancedthree-phasesystem,thesourcephasevoltageisexpressedas

（2）

Where

（3）

Atransformationmatrixbasedontheestimatedphaseangle,whichtransformsthree-phasevariablesintoasynchronousd–qreferenceframe,is

（4）

Transforming

（1）intothe–referenceframeusing（4）

（5）

wherepisadifferentialoperatorand.

Expressing（5）inavectornotation

（6）

where,

（7）

Takingatransformationof

（2）byusing（4）

（8）

Where

（9）

Expressing（6）and（8）inadiscretedomain,byapproximatingthederivativetermin（6）byaforwarddifference[9],respectively,

（10）

（11）

WhereTisthesamplingperiod.

Fig.2.Overallcontrolblockdiagram.

BSystemControl

ThePIcontrollersareusedtoregulatethedcoutputvoltageandtheacinputcurrent.Fordecouplingcurrentcontrol,thecross-couplingtermsarecompensatedinafeedforward-typeandthesourcevoltageisalsocompensatedasadisturbance.Fortransientresponseswithoutovershoot,theanti-winduptechniqueisemployed[10].TheoverallcontrolblockdiagrameliminatingthesourcevoltageandlinecurrentsensorsisshowninFig.2.Theestimationalgorithmofsourcevoltagesandlinecurrentsisdescribedinthefollowingsections.

2PREDICTIVECURRENTESTIMATION

Thecurrentsof

and

cannotbecalculatedinstantlysincethecalculationtimeoftheDSPisrequired.Toeliminatethedelayeffect,astateobservercanbeused.Inaddition,thestateobserverprovidesthefilteringeffectsfortheestimatedvariable.

Expressing（5）inastate-spaceform,

（12）

（13）

where,

Andyistheoutput.

Transforming（12）and（13）intoadiscretedomain,respectively,

（14）

（15）

where,

Then,theobserverequationaddinganerrorcorrectiontermtoisgivenby

（16）

WhereKistheobservergainmatrixand“＾”meanstheestimatedquantity,and

isthestatevariableestimatedaheadonesamplingperiod.Subtracting（15）from（16）,theerrordynamicequationoftheobserverisexpressedas

（17）

where

.Here,itisassumedthatthemodelparametersmatchwellwiththerealones.Fig.3showstheblockdiagramoftheclosed-loopstateobserver.

Thestatevariableerrordependsonlyontheinitialerrorandisindependentoftheinput.For（17）toconvergetothezerostate,therootsofthecharacteristicequationof（17）shouldbelocatedwithintheunitcircle.

Fig.3.Closed-loopstateobserver.

Fig.4.Shortpulseregion.

3EXPERIMENTSANDDISCUSSIONS

A.SystemHardwareConfiguration

Fig.5showsthesystemhardwareconfiguration.Thesourcevoltageisathree-phase,110[V].Theinputresistanceandinductanceare0.06Ωand3.3mH,respectively.Thedclinkcapacitanceis2350μFandtheswitchingfrequencyofthePWMrectifieris3.5kHz.

Fig.5.Systemhardwareconfiguration.

Fig.6.Dclinkcurrentsandcorrespondingphasecurrents（insectorV）.

TheTMS320C31DSPchipoperatingat33.3MHzisusedasamainprocessorandtwo12-bA/Dconvertersareused.Oneofthemisdedicatedfordetectingthedclinkcurrentandtheotherisusedformeasuringthedcoutputvoltageandthesourcevoltagesandcurrents,whereacsidequantitiesarejustmeasuredforperformancecomparison.

OneoftwointernaltimersintheDSPisemployedtodecidethePWMcontrolperiodandtheotherisusedtodeterminethedclinkcurrentinterrupt.Consideringtherectifierblankingtimeof3.5s,A/Dconversiontimeof2.6s,andtheothersignaldelaytime,theminimumpulsewidthissetto10s.

A.ExperimentalResults

Fig.6showsmeasureddclinkcurrentsandphasecurrents.IncaseofsectorVofthespacevectordiagram,thedclinkcurrentcorrespondstofortheswitchingstateofandforthatof.Fig.7（a）showstherawdclinkcurrentbeforefiltering.Ithasalotofringingcomponentsduetotheresonanceoftheleakageinductanceandthesnubbercapacitor.Whenthedccurrentissampledattheendpointoftheactivevoltagevectorsasshowninthefigure,themeasuringerrorcanbereduced.

Fig.7.Samplingofdclinkcurrents.

Fig.8.Estimatedsourcevoltageandcurrentatstarting.

Toreducethiserrorfurther,thelowpassfiltershouldbeemployed,ofwhichresultiss