外文翻譯英文原文BeltConveyingSystemsDevelopmentofdrivingsystemAmongthemethodsofmaterialconveyingemployedbeltconveyorsplayaveryimportantpartinthereliablecarryingofmaterialoverlongdistancesatcompetitivecostConveyorsystemshavebecomelargerandmorecomplexanddrivesystemshavealsobeengoingthroughaprocessofevolutionandwillcontinuetodoso.Nowadays,biggerbeltsrequiremorepowerandhavebroughttheneedforlargerindividualdrivesaswellasmultipledrivessuchas3drivesof750kWforonebelt(thisisthecasefortheconveyordrivesinChengzhuangMine).Theabilitytocontroldriveaccelerationtorqueiscriticaltobeltconveyors'performance.Anefficientdrivesystemshouldbeabletoprovidesmooth,softstartswhilemaintainingbelttensionswithinthespecifiedsafelimits.Forloadsharingonmultipledrives,torqueandspeedcontrolarealsoimportantconsiderationsinthedrivesystem'sdesign.Duetotheadvancesinconveyordrivecontroltechnology,atpresentmanymorereliable.Cost-effectiveandperformance-drivenconveyordrivesystemscoveringawiderangeofpowerareavailableforcustomers'choices[1]Analysisonconveyordrivetechnologies1.1DirectdrivesFull-voltagestarters.Withafull-voltagestarterdesign,theconveyorheadshaftisdirect-coupledtothemotorthroughthegeardrive.Directfull-voltagestartersareadequateforrelativelylow-power,simple-profileconveyors.Withdirectfull-voltagestarters.nocontrolisprovidedforvariousconveyorloadsand.dependingontheratiobetweenfull-andno-loadpowerrequirementsemptystartingtimescanbethreeorfourtimesfasterthanfullload.Themaintenance-freestartingsystemissimple,low-costandveryreliable.However,theycannotcontrolstartingtorqueandmaximumstalltorque；therefore.theyarelimitedtothelow-power,simple-profileconveyorbeltdrives.Reduced-voltagestarters.Asconveyorpowerrequirementsincrease,controllingtheappliedmotortorqueduringtheaccelerationperiodbecomesincreasinglyimportant.Becausemotortorque1safunctionofvoltagemotorvoltagemustbecontrolled.Thiscanbeachievedthroughreduced-voltagestartersbyemployingasiliconcontrolledrectifier(SCR).AcommonstartingmethodwithSCRreduced-voltagestartersistoapplylowvoltageinitiallytotakeupconveyorbeltslack.andthentoapplyatimedlinearrampuptofullvoltageandbeltspeed.However,thisstartingmethodwillnotproduceconstantconveyorbeltacceleration.Whenaccelerationiscomplete.theSCRs,whichcontroltheappliedvoltagetotheelectricmotor.arelockedinfullconduction,providingfull-linevoltagetothemotorMotorswithhighertorqueandpul—uptorque,canprovidebetterstartingtorquewhencombinedwiththeSCRstarters,whichareavailableinsizesupto750KW.Woundrotorinductionmotors.WoundrotorinductionmotorsareconnecteddirectlytothedrivesystemreducerandareamodifiedconfigurationofastandardACinductionmotor.Byinsertingresistanceinserieswiththemotor’srotorwindings.themodifiedmotorcontrolsystemcontrolsmotortorqueForconveyorstarting,resistanceisplacedinserieswiththerotorforlowinitialtorque.Astheconveyoraccelerates,theresistanceisreducedslowlytomaintainaconstantaccelerationtorque.Onmultiple-drivesystems.anexternalslipresistormaybeleftinserieswiththerotorwindingstoaidinloadsharingThemotorsystemshavearelativelysimpledesign.However,thecontrolsystemsforthesecanbehighlycomplex,becausetheyarebasedoncomputercontroloftheresistanceswitching.Today,themajorityofcontrolsystemsarecustomdesignedtomeetaconveyorsystem’sparticularspecifications.Woundrotormotorsareappropriateforsystemsrequiringmorethan400kW.DCmotor.DCmotors.availablefromafractionofthousandsofkW,aredesignedtodeliverconstanttorquebelowbasespeedandconstantkWabovebasespeedtothemaximumallowablerevolutionsperminute(r/min).withthemajorityofconveyordrives,aDCshuntwoundmotorisused.Whereinthemotor’srotatingarmature專業(yè)WORD.isconnectedexternally.ThemostcommontechnologyforcontrollingDCdrivesisaSCRdevice,whichallowsforcontinualvariable-speedoperationTheDCdrivesystemismechanicallysimple,butcanincludecomplexcustom-designedelectronicstomonitorandcontrolthecompletesystem.Thissystemoptionisexpensiveincomparisontoothersoft-startsystems.butitisareliable,cost-effectivedriveinapplicationsinwhichtorque,1oadsharingandvariablespeedareprimaryconsiderations.DCmotorsgenerallyareusedwithhigher-powerconveyors,includingcomplexprofileconveyorswithmultiple-drivesystems,boostertrippersystemsneedingbelttensioncontrolandconveyorsrequiringawidevariable-speedrange.1.2HydrokineticcouplingHydrokineticcouplings,commonlyreferredtoasfluidcouplings.arecomposedofthreebasicelements；thedrivenimpeller,whichactsasacentrifugalpumpthedrivinghydraulicturbineknownastherunnerandacasingthatenclosesthetwopowercomponents.Hydraulicfluidispumpedfromthedrivenimpellertothedrivingrunner,producingtorqueatthedrivenshaft.Becausecirculatinghydraulicfluidproducesthetorqueandspeed,nomechanicalconnectionisrequiredbetweenthedrivinganddrivenshafts.Thepowerproducedbythiscouplingisbasedonthecirculatedfluid’samountanddensityandthetorqueirproportiontoinputspeed.Becausethepumpingactionwithinthefluidcouplingdependsoncentrifugalforces.theoutputspeedislessthantheinputspee；dReferredtoasslipthisnormallyisbetweenl%and3%,BasichydrokineticcouplingsareavailableinconfigurationsfromfractionaltoseveralthousandkW.Fixed-fillfluidcouplings.Fixed-fillfluidcouplingsarethemostcommonlyusedsoft-startdevicesforconveyorswithsimplerbeltprofilesandlimitedconvex/concavesections.Theyarerelativelysimple,1ow-cost,reliable,maintenancefreedevicesthatprovideexcellentsoftstartingresultstothemajorityofbeltconveyorsinusetoday.Variable-filldraincouplings.Drainable-fluidcouplingsworkonthesameprincipleasfixed-fillcouplings.Thecoupling'simpellersaremountedontheACmotorandtherunnersonthedrivenreducerhigh-speedshaftHousingmountedtothedrivebaseenclosestheworkingcircuitThecoupling'srotatingcasing專業(yè)WORD.containsbleed-offorificesthatcontinuallyallowfluidtoexittheworkingcircuitintoaseparatehydraulicreservoir.Oilfromthereservoirispumpedthroughaheatexchangertoasolenoid-operatedhydraulicvalvethatcontrolsthefillingofthefluidcoupling.Tocontrolthestartingtorqueofasingle-driveconveyorsystem,theACmotorcurrentmustbemonitoredtoprovidefeedbacktothesolenoidcontrolvalve.Variablefilldraincouplingsareusedinmediumtohigh-kWconveyorsystemsandareavailableinsizesuptothousandsofkW.Thedrivescanbemechanicallycomplexanddependingonthecontrolparameter.sthesystemcanbeelectronicallyintricateThedrivesystemcostismediumtohigh,dependinguponsizespecified.Hydrokineticscoopcontroldrive.Thescoopcontrolfluidcouplingconsistsofthethreestandardfluidcouplingcomponents：adrivenimpeller,adrivingrunnerandacasingthatenclosestheworkingcircuitThecasingisfittedwithfixedorificesthatbleedapredeterminedamountoffluidintoareservoir.Whenthescooptubeisfullyextendedintothereservoir,thecouplingisl00percentfilled.Thescooptube,extendingoutsidethefluidcoupling,ispositionedusinganelectricactuatortoengagethetubefromthefullyretractedtothefullyengagedposition.Thiscontrolprovidesreasonablysmoothaccelerationrates.tobutthecomputer-basedcontrolsystemisverycomplex.Scoopcontrolcouplingsareappliedonconveyorsrequiringsingleormultipledrivesfroml50kWto750kW.1.3Variable-frequencycontrol(VFC)Variablefrequencycontrolisalsooneofthedirectdrivemethods.Theemphasizingdiscussionaboutithereisbecausethatithassouniquecharacteristicandsogoodperformancecomparedwithotherdrivingmethodsforbeltconveyor.VFCdevicesProvidevariablefrequencyandvoltagetotheinductionmotor,resultinginanexcellentstartingtorqueandaccelerationrateforbeltconveyordrives.VFCdrives.availablefromfractionaltoseveralthousand(kW),areelectroniccontrollersthatrectifyAClinepowertoDCand,throughaninverter,convertDCbacktoACwithfrequencyandvoltagecontrol.VFCdrivesadoptvectorcontrolordirecttorquecontrol(DTC)technology,andcanadoptdifferentoperating專業(yè)WORD.speedsaccordingtodifferentloads.VFCdrivescanmakestartingorstallingaccordingtoanygivenS-curves.realizingtheautomatictrackforstartingorstallingcurves.VFCdrivesprovideexcellentspeedandtorquecontrolforstartingconveyorbelts.andcanalsobedesignedtoprovideloadsharingformultipledrives.easilyVFCcontrollersarefrequentlyinstalledonlower-poweredconveyordrives,butwhenusedattherangeofmedium-highvoltageinthepast.thestructureofVFCcontrollersbecomesverycomplicatedduetothelimitationofvoltageratingofpowersemiconductordevices,thecombinationofmedium-highvoltagedrivesandvariablespeedisoftensolvedwithlow-voltageinvertersusingstep-uptransformerattheoutput,orwithmultiplelow-voltageinvertersconnectedinseries.Three-levelvoltage-fedPWMconvertersystemsarerecentlyshowingincreasingpopularityformulti-megawattindustrialdriveapplicationsbecauseofeasyvoltagesharingbetweentheseriesdevicesandimprovedharmonicqualityattheoutputcomparedtotwo-levelconvertersystemsWithsimpleseriesconnectionofdevices.ThiskindofVFCsystemwiththree750kW/23kVinvertershasbeensuccessfullyinstalledinChengZhuangMineforone2.7-kmlongbeltconveyordrivingsysteminfollowingtheprincipleofthree-levelinverterwillbediscussedindetail.Neutralpointclamped(NPC)three-levelinverterusingIGBTsThree-levelvoltage-fedinvertershaverecentlybecomemoreandmorepopularforhigherpowerdriveapplicationsbecauseoftheireasyvoltagesharingfeatures.lowerdv/dtperswitchingforeachofthedevices,andsuperiorharmonicqualityattheoutput.TheavailabilityofHV-IGBTshasledtothedesignofanewrangeofmedium-highvoltageinverterusingthree-levelNPCtopology.Thiskindofinvertercanrealizeawholerangewithavoltageratingfrom.23kVto4.16kVSeriesconnectionofHV-IGBTmodulesisusedinthe3.3kVand4.16kVdevices.The2.3kVinvertersneedonlyoneHV-IGBTperswitch[2,3]2.1PowersectionTomeetthedemandsformediumvoltageapplications.athree-levelneutralpointclampedinverterrealizesthepowersection.Incomparisontoatwo-levelinverter.theNPCinverteroffersthebenefitthatthreevoltagelevelscanbe專業(yè)WORD.suppliedtotheoutputterminals,soforthesameoutputcurrentquality,only1/4oftheswitchingfrequencyisnecessaryMoreoverthevoltageratingsoftheswitchesinNPCinvertertopologywillbereducedto1/2.andtheadditionaltransientvoltagestressonthemotorcanalsobereducedto1/2comparedtothatofatwo-levelinverter.Theswitchingstatesofathree-levelinverteraresummarizedinTable1.U.VandWdenoteeachofthethreephasesrespectively；PNandOarethedcbuspoints.ThephaseU,forexample,isinstateP(positivebusvoltage)whentheswitchesS〔andS2areclosed,whereasitisinstateN(negativebusvoltage)whentheswitches§andS4areclosed.AtneutralpointclampingthephaseisinOstatewheneither§orS3conductsdependingonpositiveornegativephasecurrentpolarity,respectively.Forneutralpointvoltagebalancing,theaveragecurrentinjectedatOshouldbezero.2.2LinesideconverterForstandardapplications.al2-pulsedioderectifierfeedsthedividedDC-linkcapacitor.Thistopologyintroduceslowharmonicsonthelineside.Forevenhigherrequirementsa24-pulsedioderectifiercanbeusedasaninputconverter.Formoreadvancedapplicationswhereregenerationcapabilityisnecessary,anactivefront.endconvertercanreplacethedioderectifier,usingthesamestructureastheinverter.2.3InvertercontrolMotorContro1.Motorcontrolofinductionmachinesisrealizedbyusingarotorflux.orientedvectorcontroller.Fig.2showstheblockdiagramofindirectvectorcontrolleddrivethatincorporatesbothconstanttorqueandhighspeedfield-weakeningregionswherethePWMmodulatorwasused.Inthisfigure,thecommandfluxisgeneratedasfunctionofspeed.Thefeedbackspeedisaddedwiththefeedforwardslipcommandsignal.theresultingfrequencysignalisintegratedandthentheunitvectorsignals(cosandsin)aregenerated.ThevectorrotatorgeneratesthevoltageandanglecommandsforthePWMasshown.PWMModulator.ThedemandedvoltagevectorisgeneratedusinganelaboratePWMmodulator.Themodulatorextendstheconceptsofspace-vectormodulationtothethree-levelinverter.Theoperationcanbeexplainedbystartingfromaregularlysampledsine-trianglecomparisonfromtwo-levelinverter.Insteadofusingonesetofreferencewaveformsandonetriangledefiningtheswitchingfrequency,thethree-levelmodulatorusestwosetsofreferencewaveformsU1andUandjustonetriangle.Thus,eachswitchingtransitionisusedinanoptimalwaysothatseveralobjectivesarereachedatthesametime.Verylowharmonicsaregenerated.Theswitchingfrequencyislowandthusswitchinglossesareminimized.Asinatwo-levelinverter,azero-sequencecomponentcanbeaddedtoeachsetofreferencewaveformsinordertomaximizethefundamentalvoltagecomponent.Asanadditionaldegreeoffreedom,thepositionofthereferencewaveformswithinthetrianglecanbechangedThiscanbeusedforcurrentbalanceinthetwohalvesoftheDCTink.TestingresultsAfterSuccessfulinstallationofthree750kW/23kVthree-levelinvertersforone2.7kmlongbeltconveyordrivingsysteminChengzhuangMine.TheperformanceofthewholeVFCsystemwastested.Fig.3istakenfromthetest,whichshowstheexcellentcharacteristicofthebeltconveyordrivingsystemwithVFCcontroller.Fig.3includesfourcurves.Thecurve1showsthebelttension.Fromthecurveitcanbefindthatthefluctuationrangeofthebelttensionisverysmall.Curve2andcurve3indicatecurrentandtorqueseparatelyCurve4showsthevelocityofthecontrolledbelt.Thebeltvelocityhavethe"s"shapecharacteristic.Alltheresultsofthetestshowaverysatisfiedcharacteristicforbeltdrivingsystem.ConclusionsAdvancesinconveyordrivecontroltechnologyinrecentyearshaveresultedinmanymorereliable.Cost-effectiveandperformance-drivenconveyordrivesystemchoicesforusers.Amongthesechoices,theVariablefrequencycontrol(VFC)methodshowspromisinguseinthefutureforlongdistancebeltconveyordrivesduetoitsexcellentperformances.TheNPCthree-levelinverterusinghighvoltageIGBTs專業(yè)WORD.maketheVariablefrequencycontrolinmediumvoltageapplicationsbecomemuchmoresimplebecausetheinverteritselfcanprovidethemediumvoltageneededatthemotorterminals，thuseliminatingthestep-uptransformerinmostapplicationsinthepast.ThetestingresultstakenfromtheVFCcontrolsystemwithNPCthree.levelinvertersusedina2.7kmlongbeltconveyordrivesinChengzhuangMineindicatesthattheperformanceofNPCthree-levelinverterusingHV-IGBTstogetherwiththecontrolstrategyofrotorfield-orientedvectorcontrolforinductionmotordriveisexcellentforbeltconveyordrivingsystem.中文譯文:帶式輸送機及其牽引系統(tǒng)在運送大量的物料時，帶式輸送機在長距離的運輸中起到了非常重要的競爭作用。輸送系統(tǒng)將會變得更大、更復(fù)雜，而驅(qū)動系統(tǒng)也已經(jīng)歷了一個演變過程，并將繼續(xù)這樣下去。如今，較大的輸送帶和多驅(qū)動系統(tǒng)需要更大的功率，比如3驅(qū)動系統(tǒng)需要給輸送帶750KW(成莊煤礦輸送機驅(qū)動系統(tǒng)的要求)?？刂乞?qū)動力和加速度扭矩是輸送機的關(guān)鍵。一個高效的驅(qū)動系統(tǒng)應(yīng)該能順利的運行，同時保持輸送帶緊力在指定的安全極限負(fù)荷。為了負(fù)載分配在多個驅(qū)動上，扭矩和速度控制在驅(qū)動系統(tǒng)的設(shè)計中也是很重要的因素。由于輸送機驅(qū)動系統(tǒng)控制技術(shù)的進(jìn)步，目前更多可靠的低成本和高效驅(qū)動的驅(qū)動系統(tǒng)可供顧客選擇[1]1帶式輸送機驅(qū)動1.1帶式輸送機驅(qū)動方式全電壓啟動在全電壓啟動設(shè)計中，帶式輸送機驅(qū)動軸通過齒輪傳動直接連接到電機。直接全壓驅(qū)動沒有為變化的傳送負(fù)載提供任何控制，根據(jù)滿載和空載功率需求的比率，空載啟動時比滿載可能快3?4倍。此種方式的優(yōu)點是:免維護(hù)，啟動系統(tǒng)簡單，低成本，可靠性高。但是，不能控制啟動扭矩和最大停止扭矩。因此，這種方式只用于低功率，結(jié)構(gòu)簡單的傳送驅(qū)動中。降壓啟動隨著傳送驅(qū)動功率的增加，在加速期間控制使用的電機扭矩變得越來越重要。由于電機扭矩是電壓的函數(shù)，電機電壓必須得到控制，一般用可控硅整流器(SCR)構(gòu)成的降壓啟動裝置，先施加低電壓拉緊輸送帶，然后線性的增加供電電壓直到全電壓和最大帶速。但是，這種啟動方式不會產(chǎn)生穩(wěn)定的加速度，當(dāng)加速完成時，控制電機電壓的SCR鎖定在全導(dǎo)通，為電機提供全壓。此種控制方式功率可達(dá)到750kW。繞線轉(zhuǎn)子感應(yīng)電機繞線轉(zhuǎn)子感應(yīng)電機直接連接到驅(qū)動系統(tǒng)減速機上，通過在電機轉(zhuǎn)子繞組中串聯(lián)電阻控制電機轉(zhuǎn)矩。在傳送裝置啟動時，把電阻串聯(lián)進(jìn)轉(zhuǎn)子產(chǎn)生較低的轉(zhuǎn)矩，當(dāng)傳送帶加速時，電阻逐漸減少保持穩(wěn)定增加轉(zhuǎn)矩。在多驅(qū)動系統(tǒng)中，一個外加的滑差電阻可能將總是串聯(lián)在轉(zhuǎn)子繞組回路中以幫助均分負(fù)載。該方式的電機系統(tǒng)設(shè)計相對簡單，但控制系統(tǒng)可能很復(fù)雜，因為它們是基于計算機控制的電阻切換。當(dāng)今，控制系統(tǒng)的大多數(shù)是定制設(shè)計來滿足傳送系統(tǒng)的特殊規(guī)格。繞線轉(zhuǎn)子電機適合于需要400kW以上的系統(tǒng)。直流(DC)電機大多數(shù)傳送驅(qū)動使用DC并勵電機，電機的電樞在外部連接?？刂茖I(yè)WORD.DC驅(qū)動技術(shù)一般應(yīng)用SCR裝置，它允許連續(xù)的變速操作。DC驅(qū)動系統(tǒng)在機械上是簡單的,但設(shè)計的電子電路，監(jiān)測和控制整個系統(tǒng)，相比于其他軟啟動系統(tǒng)的選擇是昂貴的，但在轉(zhuǎn)矩、負(fù)載均分和變速為主要考慮的場合，它又是一個可靠的，節(jié)約成本的方式。DC電機一般使用在功率較大的輸送裝置上，包括需要輸送帶力控制的多驅(qū)動系統(tǒng)和需要寬變速圍的輸送裝置上。1.2液力偶合器流體動力偶合器通常被稱為液力偶合器，由三個基本單元組成：充當(dāng)離心泵的葉輪，推進(jìn)水壓的渦輪和裝進(jìn)兩個動力部件的外殼。流體從葉輪到渦輪，在從動軸產(chǎn)生扭矩。由于循環(huán)流體產(chǎn)生扭矩和速度，在驅(qū)動軸和從動軸之間不需要任何機械連接。這種連接產(chǎn)生的動力決定于液力偶合器的充液量，扭矩正比于輸入速度。因在流體偶合中輸出速度小于輸入速度，其間的差值稱為滑差，一般為1%?3%。傳遞功率可達(dá)幾千千瓦。固定充液液力偶合器固定充液液力偶合器是在結(jié)構(gòu)較簡單和僅具有有限的彎曲部分的輸送裝置中最常用的軟啟動裝置，其結(jié)構(gòu)相對比較簡單，成本又低，對現(xiàn)在使用的大多數(shù)輸送機能提供優(yōu)良的軟啟動效果?？勺兂湟阂毫ε己掀饕卜Q為限矩型液力偶合器。偶合器的葉輪裝在AC電機上，渦輪裝在從動減速器高速軸上，包含操作部件的軸箱安裝在驅(qū)動基座。偶合器的旋轉(zhuǎn)外殼有溢出口，允許液體不斷地從工作腔中流出進(jìn)入一個分離的輔助腔，油從輔助腔通過一個熱交換器泵到控制偶合器充液量的電磁閥。為了控制單機傳動系統(tǒng)的啟動轉(zhuǎn)矩，必須監(jiān)測AC電機電流，給電磁閥的控制提供反饋。可變充液液力偶合器可使用在功率輸送系統(tǒng)中，功率可達(dá)到數(shù)千千瓦。這種驅(qū)動無論在機械，或在電氣上都是很復(fù)雜的，其驅(qū)動系統(tǒng)成本中等。勺管控制液力偶合器也稱為調(diào)速型液力偶合器。此種液力偶合器同樣由三個標(biāo)準(zhǔn)的液力偶合單元構(gòu)成，即葉輪、渦輪和一個包含工作環(huán)路的外殼。此種液力偶合器需要在工作腔以外設(shè)置導(dǎo)管（也稱勺管）和導(dǎo)管腔，依靠調(diào)節(jié)裝置改變勺管開度（勺管頂端與旋轉(zhuǎn)外殼間距）人為的改變工作腔的充液量,從而實現(xiàn)對輸出轉(zhuǎn)速的調(diào)節(jié)。這種控制提供了合理的平滑加速度，但其計算機控制系統(tǒng)很復(fù)雜。勺管控制液力偶合器可以應(yīng)用在單機或多機驅(qū)動系統(tǒng)，功率圍為150kW?750kW。1.3變頻控制（VFC）變頻控制也是一種直接驅(qū)動方式，它具有非常獨特的高性能。VFC裝置為感應(yīng)電機提供變化的頻率和電壓，產(chǎn)生優(yōu)良的啟動轉(zhuǎn)矩和加速度。VFC設(shè)備是一個電力電子控制器，首先把AC整流成DC，然后利用逆變器，再將DC轉(zhuǎn)換成頻率、電壓可控的AC。VFC驅(qū)動采專業(yè)WORD.用矢量控制或直接轉(zhuǎn)矩控制(DTC)技術(shù)，能根據(jù)不同的負(fù)載采用不同的運行速度°VFC驅(qū)動能根據(jù)給定的，曲線啟動或停車，實現(xiàn)自動跟蹤啟動或停車曲線。VFC驅(qū)動為傳送帶啟動提供了優(yōu)良的速度和轉(zhuǎn)矩控制，也能為多機驅(qū)動系統(tǒng)提供負(fù)載均分。VFC控制器可以容易地裝在小功率輸送機驅(qū)動上。過去在中高電壓使用時，VFC設(shè)備的結(jié)構(gòu)由于受電力半導(dǎo)體器件的電壓額定值限制而變得很