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BELTCONVEYINGSYSTEMSDEVELOPMENTOFDRIVINGSYSTEMAMONGTHEMETHODSOFMATERIALCONVEYINGEMPLOYED，BELTCONVEYORSPLAYAVERYIMPORTANTPARTINTHERELIABLECARRYINGOFMATERIALOVERLONGDISTANCESATCOMPETITIVECOSTCONVEYORSYSTEMSHAVEBECOMELARGERANDMORECOMPLEXANDDRIVESYSTEMSHAVEALSOBEENGOINGTHROUGHAPROCESSOFEVOLUTIONANDWILLCONTINUETODOSONOWADAYS，BIGGERBELTSREQUIREMOREPOWERANDHAVEBROUGHTTHENEEDFORLARGERINDIVIDUALDRIVESASWELLASMULTIPLEDRIVESSUCHAS3DRIVESOF750KWFORONEBELTTHISISTHECASEFORTHECONVEYORDRIVESINCHENGZHUANGMINETHEABILITYTOCONTROLDRIVEACCELERATIONTORQUEISCRITICALTOBELTCONVEYORSPERFORMANCEANEFFICIENTDRIVESYSTEMSHOULDBEABLETOPROVIDESMOOTH，SOFTSTARTSWHILEMAINTAININGBELTTENSIONSWITHINTHESPECIFIEDSAFELIMITSFORLOADSHARINGONMULTIPLEDRIVESTORQUEANDSPEEDCONTROLAREALSOIMPORTANTCONSIDERATIONSINTHEDRIVESYSTEMSDESIGNDUETOTHEADVANCESINCONVEYORDRIVECONTROLTECHNOLOGY，ATPRESENTMANYMORERELIABLECOSTEFFECTIVEANDPERFORMANCEDRIVENCONVEYORDRIVESYSTEMSCOVERINGAWIDERANGEOFPOWERAREAVAILABLEFORCUSTOMERSCHOICES11ANALYSISONCONVEYORDRIVETECHNOLOGIES11DIRECTDRIVESFULLVOLTAGESTARTERSWITHAFULLVOLTAGESTARTERDESIGN，THECONVEYORHEADSHAFTISDIRECTCOUPLEDTOTHEMOTORTHROUGHTHEGEARDRIVEDIRECTFULLVOLTAGESTARTERSAREADEQUATEFORRELATIVELYLOWPOWER,SIMPLEPROFILECONVEYORSWITHDIRECTFU11VOLTAGESTARTERSNOCONTROLISPROVIDEDFORVARIOUSCONVEYORLOADSANDDEPENDINGONTHERATIOBETWEENFU11ANDNO1OADPOWERREQUIREMENTS，EMPTYSTARTINGTIMESCANBETHREEORFOURTIMESFASTERTHANFULLLOADTHEMAINTENANCEFREESTARTINGSYSTEMISSIMPLE，LOWCOSTANDVERYRELIABLEHOWEVER,THEYCANNOTCONTROLSTARTINGTORQUEANDMAXIMUMSTALLTORQUE；THEREFORETHEYARELIMITEDTOTHELOWPOWER,SIMPLEPROFILECONVEYORBELTDRIVESREDUCEDVOLTAGESTARTERSASCONVEYORPOWERREQUIREMENTSINCREASE，CONTROLLINGTHEAPPLIEDMOTORTORQUEDURINGTHEACCELERATIONPERIODBECOMESINCREASINGLYIMPORTANTBECAUSEMOTORTORQUE1SAFUNCTIONOFVOLTAGE，MOTORVOLTAGEMUSTBECONTROLLEDTHISCANBEACHIEVEDTHROUGHREDUCEDVOLTAGESTARTERSBYEMPLOYINGASILICONCONTROLLEDRECTIFIERSCRACOMMONSTARTINGMETHODWITHSCRREDUCEDVOLTAGESTARTERSISTOAPPLYLOWVOLTAGEINITIALLYTOTAKEUPCONVEYORBELTSLACKANDTHENTOAPPLYATIMEDLINEARRAMPUPTOFULLVOLTAGEANDBELTSPEEDHOWEVER,THISSTARTINGMETHODWILLNOTPRODUCECONSTANTCONVEYORBELTACCELERATIONWHENACCELERATIONISCOMPLETETHESCRS,WHICHCONTROLTHEAPPLIEDVOLTAGETOTHEELECTRICMOTORARELOCKEDINFULLCONDUCTION,PROVIDINGFU11LINEVOLTAGETOTHEMOTORMOTORSWITHHIGHERTORQUEANDPULLUPTORQUE，CANPROVIDEBETTERSTARTINGTORQUEWHENCOMBINEDWITHTHESCRSTARTERS,WHICHAREAVAILABLEINSIZESUPTO750KWWOUNDROTORINDUCTIONMOTORSWOUNDROTORINDUCTIONMOTORSARECONNECTEDDIRECTLYTOTHEDRIVESYSTEMREDUCERANDAREAMODIFIEDCONFIGURATIONOFASTANDARDACINDUCTIONMOTORBYINSERTINGRESISTANCEINSERIESWITHTHEMOTORSROTORWINDINGSTHEMODIFIEDMOTORCONTROLSYSTEMCONTROLSMOTORTORQUEFORCONVEYORSTARTING，RESISTANCEISPLACEDINSERIESWITHTHEROTORFORLOWINITIALTORQUEASTHECONVEYORACCELERATES，THERESISTANCEISREDUCEDSLOWLYTOMAINTAINACONSTANTACCELERATIONTORQUEONMULTIPLEDRIVESYSTEMSANEXTERNALSLIPRESISTORMAYBELEFTINSERIESWITHTHEROTORWINDINGSTOAIDINLOADSHARINGTHEMOTORSYSTEMSHAVEARELATIVELYSIMPLEDESIGNHOWEVER,THECONTROLSYSTEMSFORTHESECANBEHIGHLYCOMPLEX，BECAUSETHEYAREBASEDONCOMPUTERCONTROLOFTHERESISTANCESWITCHINGTODAY，THEMAJORITYOFCONTROLSYSTEMSARECUSTOMDESIGNEDTOMEETACONVEYORSYSTEMSPARTICULARSPECIFICATIONSWOUNDROTORMOTORSAREAPPROPRIATEFORSYSTEMSREQUIRINGMORETHAN400KWDCMOTORDCMOTORSAVAILABLEFROMAFRACTIONOFTHOUSANDSOFKW，AREDESIGNEDTODELIVERCONSTANTTORQUEBELOWBASESPEEDANDCONSTANTKWABOVEBASESPEEDTOTHEMAXIMUMALLOWABLEREVOLUTIONSPERMINUTER/MINWITHTHEMAJORITYOFCONVEYORDRIVES,ADCSHUNTWOUNDMOTORISUSEDWHEREINTHEMOTORSROTATINGARMATUREISCONNECTEDEXTERNALLYTHEMOSTCOMMONTECHNOLOGYFORCONTROLLINGDCDRIVESISASCRDEVICEWHICHALLOWSFORCONTINUALVARIABLESPEEDOPERATIONTHEDCDRIVESYSTEMISMECHANICALLYSIMPLE,BUTCANINCLUDECOMPLEXCUSTOMDESIGNEDELECTRONICSTOMONITORANDCONTROLTHECOMPLETESYSTEMTHISSYSTEMOPTIONISEXPENSIVEINCOMPARISONTOOTHERSOFTSTARTSYSTEMSBUTITISARELIABLE,COSTEFFECTIVEDRIVEINAPPLICATIONSINWHICHTORQUE,1OADSHARINGANDVARIABLESPEEDAREPRIMARYCONSIDERATIONSDCMOTORSGENERALLYAREUSEDWITHHIGHERPOWERCONVEYORS，INCLUDINGCOMPLEXPROFILECONVEYORSWITHMULTIPLEDRIVESYSTEMS，BOOSTERTRIPPERSYSTEMSNEEDINGBELTTENSIONCONTROLANDCONVEYORSREQUIRINGAWIDEVARIABLESPEEDRANGE12HYDROKINETICCOUPLINGHYDROKINETICCOUPLINGS，COMMONLYREFERREDTOASFLUIDCOUPLINGSARECOMPOSEDOFTHREEBASICELEMENTSTHEDRIVENIMPELLER,WHICHACTSASACENTRIFUGALPUMP；THEDRIVINGHYDRAULICTURBINEKNOWNASTHERUNNERANDACASINGTHATENCLOSESTHETWOPOWERCOMPONENTSHYDRAULICFLUIDISPUMPEDFROMTHEDRIVENIMPELLERTOTHEDRIVINGRUNNER,PRODUCINGTORQUEATTHEDRIVENSHAFTBECAUSECIRCULATINGHYDRAULICFLUIDPRODUCESTHETORQUEANDSPEED，NOMECHANICALCONNECTIONISREQUIREDBETWEENTHEDRIVINGANDDRIVENSHAFTSTHEPOWERPRODUCEDBYTHISCOUPLINGISBASEDONTHECIRCULATEDFLUIDSAMOUNTANDDENSITYANDTHETORQUEINPROPORTIONTOINPUTSPEEDBECAUSETHEPUMPINGACTIONWITHINTHEFLUIDCOUPLINGDEPENDSONCENTRIFUGALFORCESTHEOUTPUTSPEEDISLESSTHANTHEINPUTSPEEDREFERREDTOASSLIPTHISNORMALLYISBETWEENLAND3BASICHYDROKINETICCOUPLINGSAREAVAILABLEINCONFIGURATIONSFROMFRACTIONALTOSEVERALTHOUSANDKWFIXEDFILLFLUIDCOUPLINGSFIXEDFILLFLUIDCOUPLINGSARETHEMOSTCOMMONLYUSEDSOFTSTARTDEVICESFORCONVEYORSWITHSIMPLERBELTPROFILESANDLIMITEDCONVEX/CONCAVESECTIONSTHEYARERELATIVELYSIMPLE,1OWCOST,RELIABLE,MAINTENANCEFREEDEVICESTHATPROVIDEEXCELLENTSOFTSTARTINGRESULTSTOTHEMAJORITYOFBELTCONVEYORSINUSETODAYVARIABLEFILLDRAINCOUPLINGSDRAINABLEFLUIDCOUPLINGSWORKONTHESAMEPRINCIPLEASFIXEDFILLCOUPLINGSTHECOUPLINGSIMPELLERSAREMOUNTEDONTHEACMOTORANDTHERUNNERSONTHEDRIVENREDUCERHIGHSPEEDSHAFTHOUSINGMOUNTEDTOTHEDRIVEBASEENCLOSESTHEWORKINGCIRCUITTHECOUPLINGSROTATINGCASINGCONTAINSBLEEDOFFORIFICESTHATCONTINUALLYALLOWFLUIDTOEXITTHEWORKINGCIRCUITINTOASEPARATEHYDRAULICRESERVOIROILFROMTHERESERVOIRISPUMPEDTHROUGHAHEATEXCHANGERTOASOLENOIDOPERATEDHYDRAULICVALVETHATCONTROLSTHEFILLINGOFTHEFLUIDCOUPLINGTOCONTROLTHESTARTINGTORQUEOFASINGLEDRIVECONVEYORSYSTEM，THEACMOTORCURRENTMUSTBEMONITOREDTOPROVIDEFEEDBACKTOTHESOLENOIDCONTROLVALVEVARIABLEFILLDRAINCOUPLINGSAREUSEDINMEDIUMTOHIGHKWCONVEYORSYSTEMSANDAREAVAILABLEINSIZESUPTOTHOUSANDSOFKWTHEDRIVESCANBEMECHANICALLYCOMPLEXANDDEPENDINGONTHECONTROLPARAMETERSTHESYSTEMCANBEELECTRONICALLYINTRICATETHEDRIVESYSTEMCOSTISMEDIUMTOHIGH,DEPENDINGUPONSIZESPECIFIEDHYDROKINETICSCOOPCONTROLDRIVETHESCOOPCONTROLFLUIDCOUPLINGCONSISTSOFTHETHREESTANDARDFLUIDCOUPLINGCOMPONENTSADRIVENIMPELLER,ADRIVINGRUNNERANDACASINGTHATENCLOSESTHEWORKINGCIRCUITTHECASINGISFITTEDWITHFIXEDORIFICESTHATBLEEDAPREDETERMINEDAMOUNTOFFLUIDINTOARESERVOIRWHENTHESCOOPTUBEISFULLYEXTENDEDINTOTHERESERVOIR,THECOUPLINGISL00PERCENTFILLEDTHESCOOPTUBE,EXTENDINGOUTSIDETHEFLUIDCOUPLING，ISPOSITIONEDUSINGANELECTRICACTUATORTOENGAGETHETUBEFROMTHEFULLYRETRACTEDTOTHEFULLYENGAGEDPOSITIONTHISCONTROLPROVIDESREASONABLYSMOOTHACCELERATIONRATESTOBUTTHECOMPUTERBASEDCONTROLSYSTEMISVERYCOMPLEXSCOOPCONTROLCOUPLINGSAREAPPLIEDONCONVEYORSREQUIRINGSINGLEORMULTIPLEDRIVESFROML50KWTO750KW13VARIABLEFREQUENCYCONTROLVFCVARIABLEFREQUENCYCONTROLISALSOONEOFTHEDIRECTDRIVEMETHODSTHEEMPHASIZINGDISCUSSIONABOUTITHEREISBECAUSETHATITHASSOUNIQUECHARACTERISTICANDSOGOODPERFORMANCECOMPAREDWITHOTHERDRIVINGMETHODSFORBELTCONVEYORVFCDEVICESPROVIDEVARIABLEFREQUENCYANDVOLTAGETOTHEINDUCTIONMOTOR,RESULTINGINANEXCELLENTSTARTINGTORQUEANDACCELERATIONRATEFORBELTCONVEYORDRIVESVFCDRIVESAVAILABLEFROMFRACTIONALTOSEVERALTHOUSANDKW,AREELECTRONICCONTROLLERSTHATRECTIFYACLINEPOWERTODCAND，THROUGHANINVERTER,CONVERTDCBACKTOACWITHFREQUENCYANDVOLTAGECONTRO1VFCDRIVESADOPTVECTORCONTROLORDIRECTTORQUECONTROLDTCTECHNOLOGY，ANDCANADOPTDIFFERENTOPERATINGSPEEDSACCORDINGTODIFFERENTLOADSVFCDRIVESCANMAKESTARTINGORSTALLINGACCORDINGTOANYGIVENSCURVESREALIZINGTHEAUTOMATICTRACKFORSTARTINGORSTALLINGCURVESVFCDRIVESPROVIDEEXCELLENTSPEEDANDTORQUECONTROLFORSTARTINGCONVEYORBELTSANDCANALSOBEDESIGNEDTOPROVIDELOADSHARINGFORMULTIPLEDRIVESEASILYVFCCONTROLLERSAREFREQUENTLYINSTALLEDONLOWERPOWEREDCONVEYORDRIVES，BUTWHENUSEDATTHERANGEOFMEDIUMHIGHVOLTAGEINTHEPASTTHESTRUCTUREOFVFCCONTROLLERSBECOMESVERYCOMPLICATEDDUETOTHELIMITATIONOFVOLTAGERATINGOFPOWERSEMICONDUCTORDEVICES，THECOMBINATIONOFMEDIUMHIGHVOLTAGEDRIVESANDVARIABLESPEEDISOFTENSOLVEDWITHLOWVOLTAGEINVERTERSUSINGSTEPUPTRANSFORMERATTHEOUTPUT，ORWITHMULTIPLELOWVOLTAGEINVERTERSCONNECTEDINSERIESTHREELEVELVOLTAGEFEDPWMCONVERTERSYSTEMSARERECENTLYSHOWINGINCREASINGPOPULARITYFORMULTIMEGAWATTINDUSTRIALDRIVEAPPLICATIONSBECAUSEOFEASYVOLTAGESHARINGBETWEENTHESERIESDEVICESANDIMPROVEDHARMONICQUALITYATTHEOUTPUTCOMPAREDTOTWOLEVELCONVERTERSYSTEMSWITHSIMPLESERIESCONNECTIONOFDEVICESTHISKINDOFVFCSYSTEMWITHTHREE750KW/23KVINVERTERSHASBEENSUCCESSFULLYINSTALLEDINCHENGZHUANGMINEFORONE27KMLONGBELTCONVEYORDRIVINGSYSTEMINFOLLOWINGTHEPRINCIPLEOFTHREELEVELINVERTERWILLBEDISCUSSEDINDETAIL2NEUTRALPOINTCLAMPEDNPCTHREELEVELINVERTERUSINGIGBTSTHREELEVELVOLTAGEFEDINVERTERSHAVERECENTLYBECOMEMOREANDMOREPOPULARFORHIGHERPOWERDRIVEAPPLICATIONSBECAUSEOFTHEIREASYVOLTAGESHARINGFEATURES1OWERDV/DTPERSWITCHINGFOREACHOFTHEDEVICES，ANDSUPERIORHARMONICQUALITYATTHEOUTPUTTHEAVAILABILITYOFHVIGBTSHASLEDTOTHEDESIGNOFANEWRANGEOFMEDIUMHIGHVOLTAGEINVERTERUSINGTHREELEVELNPCTOPOLOGYTHISKINDOFINVERTERCANREALIZEAWHOLERANGEWITHAVOLTAGERATINGFROM23KVTO416KVSERIESCONNECTIONOFHVIGBTMODULESISUSEDINTHE33KVAND416KVDEVICESTHE23KVINVERTERSNEEDONLYONEHVIGBTPERSWITCH2,321POWERSECTIONTOMEETTHEDEMANDSFORMEDIUMVOLTAGEAPPLICATIONSATHREELEVELNEUTRALPOINTCLAMPEDINVERTERREALIZESTHEPOWERSECTIONINCOMPARISONTOATWOLEVELINVERTERTHENPCINVERTEROFFERSTHEBENEFITTHATTHREEVOLTAGELEVELSCANBESUPPLIEDTOTHEOUTPUTTERMINALS，SOFORTHESAMEOUTPUTCURRENTQUALITY，ONLY1/4OFTHESWITCHINGFREQUENCYISNECESSARYMOREOVERTHEVOLTAGERATINGSOFTHESWITCHESINNPCINVERTERTOPOLOGYWILLBEREDUCEDTO1/2ANDTHEADDITIONALTRANSIENTVOLTAGESTRESSONTHEMOTORCANALSOBEREDUCEDTO1/2COMPAREDTOTHATOFATWOLEVELINVERTERTHESWITCHINGSTATESOFATHREELEVELINVERTERARESUMMARIZEDINTABLE1UVANDWDENOTEEACHOFTHETHREEPHASESRESPECTIVELY；PNANDOARETHEDCBUSPOINTSTHEPHASEU，FOREXAMPLE，ISINSTATEPPOSITIVEBUSVOLTAGEWHENTHESWITCHESS1UANDS2UARECLOSED，WHEREASITISINSTATENNEGATIVEBUSVOLTAGEWHENTHESWITCHESS3UANDS4UARECLOSEDATNEUTRALPOINTCLAMPING，THEPHASEISINOSTATEWHENEITHERS2UORS3UCONDUCTSDEPENDINGONPOSITIVEORNEGATIVEPHASECURRENTPOLARITY，RESPECTIVELYFORNEUTRALPOINTVOLTAGEBALANCING，THEAVERAGECURRENTINJECTEDATOSHOULDBEZERO22LINESIDECONVERTERFORSTANDARDAPPLICATIONSAL2PULSEDIODERECTIFIERFEEDSTHEDIVIDEDDCLINKCAPACITORTHISTOPOLOGYINTRODUCESLOWHARMONICSONTHELINESIDEFOREVENHIGHERREQUIREMENTSA24PULSEDIODERECTIFIERCANBEUSEDASANINPUTCONVERTERFORMOREADVANCEDAPPLICATIONSWHEREREGENERATIONCAPABILITYISNECESSARY,ANACTIVEFRONTENDCONVERTERCANREPLACETHEDIODERECTIFIER,USINGTHESAMESTRUCTUREASTHEINVERTER23INVERTERCONTROLMOTORCONTRO1MOTORCONTROLOFINDUCTIONMACHINESISREALIZEDBYUSINGAROTORFLUXORIENTEDVECTORCONTROLLERFIG2SHOWSTHEBLOCKDIAGRAMOFINDIRECTVECTORCONTROLLEDDRIVETHATINCORPORATESBOTHCONSTANTTORQUEANDHIGHSPEEDFIELDWEAKENINGREGIONSWHERETHEPWMMODULATORWASUSEDINTHISFIGURE，THECOMMANDFLUXISGENERATEDASFUNCTIONOFSPEEDTHEFEEDBACKSPEEDISADDEDWITHTHEFEEDFORWARDSLIPCOMMANDSIGNALTHERESULTINGFREQUENCYSIGNALISINTEGRATEDANDTHENTHEUNITVECTORSIGNALSCOSANDSINAREGENERATEDTHEVECTORROTATORGENERATESTHEVOLTAGEANDANGLECOMMANDSFORTHEPWMASSHOWNPWMMODULATORTHEDEMANDEDVOLTAGEVECTORISGENERATEDUSINGANELABORATEPWMMODULATORTHEMODULATOREXTENDSTHECONCEPTSOFSPACEVECTORMODULATIONTOTHETHREELEVELINVERTERTHEOPERATIONCANBEEXPLAINEDBYSTARTINGFROMAREGULARLYSAMPLEDSINETRIANGLECOMPARISONFROMTWOLEVELINVERTERINSTEADOFUSINGONESETOFREFERENCEWAVEFORMSANDONETRIANGLEDEFININGTHESWITCHINGFREQUENCY，THETHREELEVELMODULATORUSESTWOSETSOFREFERENCEWAVEFORMSUR1ANDUR2ANDJUSTONETRIANGLETHUS,EACHSWITCHINGTRANSITIONISUSEDINANOPTIMALWAYSOTHATSEVERALOBJECTIVESAREREACHEDATTHESAMETIMEVERYLOWHARMONICSAREGENERATEDTHESWITCHINGFREQUENCYISLOWANDTHUSSWITCHINGLOSSESAREMINIMIZEDASINATWOLEVELINVERTER,AZEROSEQUENCECOMPONENTCANBEADDEDTOEACHSETOFREFERENCEWAVEFORMSINORDERTOMAXIMIZETHEFUNDAMENTALVOLTAGECOMPONENTASANADDITIONALDEGREEOFFREEDOM，THEPOSITIONOFTHEREFERENCEWAVEFORMSWITHINTHETRIANGLECANBECHANGEDTHISCANBEUSEDFORCURRENTBALANCEINTHETWOHALVESOFTHEDC1INK3TESTINGRESULTSAFTERSUCCESSFULINSTALLATIONOFTHREE750KW/23KVTHREELEVELINVERTERSFORONE27KMLONGBELTCONVEYORDRIVINGSYSTEMINCHENGZHUANGMINETHEPERFORMANCEOFTHEWHOL
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