ElevatorSystemBasedonPLCComposedbytheorderofrelaycontrolsystemisarealizationofthefirstelevatorcontrolmethod.However,toenterthenineties,withthedevelopmentofscienceandtechnologyandthewidespreadapplicationofcomputertechnology,thesafetyofelevators,reliabilityoftheincreasinglyhighdemandontherelaycontrolweaknessesarebecomingevident.Elevatorcontrolsystemrelaysthefailureratehigh,greatlyreducesthereliabilityandsafetyofelevators,andescalatorsstoppedoftentotakewiththestaffabouttheinconvenienceandfear.Andtheeventratherthantakingtheliftorsquatattheendoftheliftwillnotonlycausedamagetomechanicalcomponents,butalsopersonalaccidentmayoccur.ProgrammableLogicController(PLC)isthefirstorderlogiccontrolinaccordancewiththeneedsofdevelopedspecificallyforindustrialenvironmentapplicationstooperatetheelectronicdigitalcomputingdevice.Givenitsadvantages,atpresent,therelaycontrolthelifthasbeengraduallyreplacedbyPLCcontrol.Atthesametime,ACvariablefrequencymotorspeedcontroltechnology,thewaytheliftdragspeedhasbeenagradualtransitionformDCtoACfrequencyconverter.Thus,PLCcontroltechnologyincreasesVVVFElevatormoderntechnologyhasbecomeahotindustry.1.PLCelevatorcontroladvantages:(1)UsedinelevatorcontrolPLC,withsowareforautomaticcontrolofliftoperation,reliabilitygreatlyincreased.(2)Layerwasremovedandmajorityoftherelay,thecontrolsystemstructureissimple,simplifytheexternalcircuit.(3)PLCcanbeavarietyofcomplexcontrolsystem,easytoaddorchangecontrolfunctions.(4)PLCcanbeautomatedfaultdetectionandalarmdisplaytoimprovetheoperationofsecurityandeaseofmaintenance.(5)Forthegroupcontroltheallocationandmanagement,andimprovetheefficiencyofelevatoroperation.(6)Donotneedtochangethecontrolschemechangeswhenthehardwareconnection.2.VVVFelevatorcontrolcharacteristics.Withthepowerelectronics,microelectronicsandcomputertechnologytocontroltherapiddevelopmentoftechnology,communicationtechnologyVVVFalsoaveryrapidrate.ACvariablefrequencymotorspeedcontroltechnologyisthepowertoimprovetheprocessinordertoimproveproductqualityandimprovingtheenvironmentandpromotingtechnologicalprogressasaprimarymeans.Frequencyofitsexcellentperformanceandthespeedbrakefromasmoothperformance,highefficiency,highpowerfactorandpower-savingofabroadscopeofapplicationandmanyotheradvantagesofbeingathomeandabroadrecognizedasthemostpromisingapproachspeed.ExchangecharacteristicsofVVVFElevator:(1)lowenergyconsumption.(2)lowloadcircuit,thereemergencypowersupplydeviceofsmall.Intheaccelerationstage,therequiredstart-upcurrentoflessthan2.5timestheratedcurrent.Peakstartingcurrentandtimeisshort.Sincethestartingcurrentisdrasticallyreduced,sopowerconsumptionandpowersupplycablediametercanbereducedalot.Requiredforemergencypowersupplydevicesarealsorelativelysmallsize.(3)highreliabilityandlongservicelife.(4)goodcomfort.Elevatoroperationisbesttofollowthespeedcurveofagivenoperation.Theircharacteristicscanbeadaptedtohumanfeelings,andtoensurethatnoiseoperation,smoothbrakePinglayerandhighprecision.(5)stablenoise-free.(6)Inthecar,theengineroomandadjacentareastoensurethatnoise.Becausetheirsystemsuseahighclockfrequency.Alwaysproduceatruesinewavepowersupplycurrentyet.Motortorquerippledoesnotappear.Therefore,toeliminatevibrationandnoise.3.Elevatorcontroltechnology.Theso-calledelevatorcontroltechnologyreferstotheelevatordrivesystemandelectricalcontrolsystemofautomaticcontrol.70asthe20thcenturyinChina’selevatorweremarkedbytheexchangeoftwo-speedelevator.Itsspeedisusedtochangetheelevatortractionmotoroftheveryfew,twoormute-levelapproachtothenumberofwindings,veryfewofthemashigh-speedwindingofthewinding,averyfewnumberofwindingsasthelow-speedwinding.Windingsforhigh-speedelevator-speedstart-upandrunning,low-speedwindingsforbrakingandthemaintenanceofelevators.Theearly80s,VVVFinvertercontrolledvariableliftsystemavailable.ItusesACmotordrivers,areabletoreachthelevelofDCmotor,controlthespeedofthecurrenthasreached6m/sec.Itssmallsize,lightweight,highefficiency,energysaving,inc1udingthepastalmostalltheadvantagesofthelift.IsthelatestelevatordrivesystemOperationinverticallift,thereisalsothestartingpointoftheterminusstation.Formorethanthree-storyelevatorbuildings,thestartingpointoftheterminalstationsandstopsbetweenthehadnot,thestartingpointforthesestationsatthefirstflooroftheterminallocatedatthehighestfloor.Startingpointinthefirstfloorofthestationknownasbasestations,knownasthestartingpointatbothendsoftheterminalstationsandstationsatbothendsofintermediatestopsbetweenstations.Outsidethestationhasacallbox,boxsetareusedbystaffforelevatorcallbuttonortouchthecallbutton,thegeneralendsoftheliftstationsinthecallboxontheSettingsbuttonortouchofabutton.1iddlelayerofthestationsetupthecallboxbuttonortouchbutton2.Nodriversforthecontrolofelevators,atvariousstationsaresetupcallsmeonabuttonortouchbutton.Elevatorcarandtheinternalsettings(exceptfordebriselevator)tomanipulateme.Controlboxswitchonthehandleorsetupstationsandthecorrespondinglayerofbuttonsortouch-buttoncontrolboxonthetouch-controlbuttonorcommandbuttonortouchthecitybutton.Outsidethecommandbuttonortouch-buttonissueasthesignaloutsidethecommandsignal,withinthecommandbuttonortouch-buttonissuewithinthesignalasacommandsignal.80Inthemid-20thcentury,thetouchbuttonhasbeenreplacedbymicro-button.Astheelevatorcallboxoutsidethebasestation,inadditiontosetupacallbuttonortouchbutton,buta1sosetakeyswitchinordertoworktheelevatorclearance.Driversormanagementstafftoopentheelevatortothebasestationcanwrigglethroughadedicatedkeytothekeyswitch.Closetheelevatorinplacetoautocraticallycutofftheelevatorcontrolpowersupplyorpowersupply.4.PLCControlElevatorDesign.Withthecontinuousdevelopmentofurbanconstruction,theincreasinghigh-risebuildings,elevatorsandlifeinthenationaleconomyhasabroadapplication.Elevatorhigh-risebuildingsasameansoftransportintheverticalrunofdailylifehavebeeninextricablylinkedwithpeople.Infacttheliftisbasedonexternalcallcontrolsignals,aswellasthelawsoftheirown,suchasrunning,andthecal1israndom,theliftisactuallyaman-machineinteractivecontrolsystem,simpletousecontrolorlogiccontrolordercannotmeetthecontrolrequirement,andtherefore,elevatorcontrolsystemusesarandomcontrollogic.Elevatorcontroliscurrent1ygenerallyusedintwoways,first,theuseofcomputerasasignalcontrolunit,thecompletionoftheliftsignalacquisition,operationandfunctionofthese,toachievetheliftandsettheautocraticschedulingfunctiontoruntheelection,dragthecontrolfrominvertertocomplete;thesecondcontrolmodewithprogrammablelogiccontroller(PLC)toreplacethecomputercontrolsignalsetstheelection.Fromthecontrolandperformance,thesetwotypesofmethodsandthereisnosignificantdifference.Mostofthedomesticmanufacturerstochoosethesecondapproach,becausethesmallerscaleofproductiontheredesignandmanufactureofhighcostofcomputercontroldevices;andPLChighreliabi1ity,convenientandflexibleprogramdesign,anti-interferenceability,stableandreliableoperationofthecharacteristicsofTherefore,theelevatorcontrolsystemisnowwidelyusedtorealizeprogrammablecontrol.5.Liftcontrolsystem.Liftcontrolsystemisusedtomanipulateeachcontrolprocessbymanagingsuchcommandsasrunningdirection,carcall,landingcall,loadsignal,landingindication,safetyprotection.Liftsindifferentapplicationshavedifferentload,speedanddrive/controlmodes.Liftsinsameapplicationmayalsohavedifferentcontrolmode.Whatevercontrolmodeisadopted,theobjectiveisthesame,tobespecific,accordingtocarcallandlandingcall,liftcontrolsystemwillexecuteautomaticlogicjudgmenttodeterminewhichliftwillreceivesignal,whichdirectionliftwillruntowardsandcompleteprogrammedcontrolobjectivethroughelectricalautomaticsystembasedoncommand.Typesofliftcontrolsystem.Controlsystemdevelopmentchronicleindicatesthattherehasappearedmanycontrolmodes,suchassuchasrelaycontrol,PLC,singlecomputercontrol,multiple-computercontrol.Prevailingindifferentera,thesecontrolmodesarestillemployedinliftsnowduetomassiveintegratedcircuitandcomputertechnologydevelopment.PLCcontrolsystem.Asabbreviationofprogrammablelogiccontroller,PLCisanelectronicsystemfeaturingdigitalcomputation.ItadoptsprogrammableEPROMtoexecutelogiccomputation,ordercontrol,timing,numbercounting,arithmeticcomputation,besides,itcaninputandoutputthroughdigitaloranalogymodes.ThemechanismofPLCcontrolisasfollows:inputofPLCincludessuchcommandsignals,aspowerkeytohomelanding,carcall,landingcall,varioussafetyswitches,positionsignal,whileoutputofPLCincludescontactor,relay,indicatorsofcar/landingsandcommunicationunitary,indicatorsinsidecarandswitch,positionsignal,areinputtoPC,whileotherexecutingcom.Programmingprincipleisdeterminedbyliftcontrolmode.Programmingcaneitherbemadeaccordingtorelaylogiccontrolcircuitorindividuallyindifferentphasesaccordingtoliftcontrolfunctionsaftercompletelyseparatingfromrelaycontrolcircuit.Basedonthereadymadecontrolcircuit,theformerissimpleandeasytomaster,whilethelatterinvolveslessprogramsbyintegratingprogramsofsmallfunction.Usedinliftcontrolsystem,PLChassuchadvantages,ashighreliability,stability,easyprogramming,user-friendliness,convenientmaintenance&inspection.Nowadays,thereisawiderangeandseriesofprogrammablelogiccontrollers.Input/outputpointsrangefrom30to8000orabove,soastomeetliftcontrolrequirementswithdifferentlandingnumber.PLC限制下的電梯系統由繼電器組成的依次限制系統是最早的一種實現電梯限制的方法。但是，進入九十年頭，隨著科學技術的發展和計算機技術的廣泛應用，人們對電梯的平安性、牢靠性的要求越來越高，繼電器限制的弱點就越來越明顯。電梯繼電器限制系統故障率高，大大降低了電梯的牢靠性和平安性，常常造成停梯，給乘用人員帶來不便和驚憂。且電梯一旦發生沖頂或蹲底，不但會造成電梯機械部件損壞，還可能出現人身事故。可編程序限制器（PLC）最早是依據依次邏輯限制的須要而發展起來的，是特地為工業環境應用而設計的數字運算操作的電子裝置。鑒于其種種優點，目前電梯的繼電器限制方式己漸漸被PLC限制所代替。同時，由于電機溝通變頻調速技術的發展，電梯的拖動方式己由原來直流調速漸漸過渡到了溝通變頻調速。因此，PLC限制技術加變頻調速技術己成為現代電梯行業的一個熱點。1.PLC限制電梯的優點：（1）在電梯限制中采納了PLC用軟件實現對電梯運行的自動限制,牢靠性大大大提高。（2）去掉了選層器及大部分繼電器，限制系統結構簡潔，外部線路簡化。（3）PLC可實現各種困難的限制系統，便利地增加或變更限制功能。（4）可進行故障自動檢測與報警顯示，提高運行平安性，并便于檢修。（5）用于群控調配和管理，并提高電梯運行效率。（6）更改限制方案時不需改動硬件接線。2.電梯變頻調速限制的特點：隨著電力電子技術、微電子技術和計算機限制技術的飛速發展，溝通變頻調速技術的發展也非常快速。電動機溝通變頻調速技術是當今節電、改善工藝流程以提高產品質量和改善環境、推動技術進步的一種主要手段。變頻調速以其優異的調速性能和起制動平穩性能、高效率、高功率因數和節電效果，廣泛的適用范圍及其它很多優點而被國內外公認為最有發展前途的調速方式。溝通變頻調速電梯的特點：（1）能源消耗低。（2）電路負載低，所需緊急供電裝置小。在加速階段，所需起動電流小于2.5倍的額定電流。且起動電流峰值時間短。由于起動電流大幅度減小，故功耗和供電纜線直徑可減小很多。所需的緊急供電裝置的尺寸也比較小。（3）牢靠性高，運用壽命長。（4）舒適感好。電梯運行是跟隨最佳給定的速度曲線運行的。其特性可適應人體感受，并保證運行噪聲小，制動平穩。（5）平層精度高。（6）運行平穩無噪聲在轎廂內，機房內及鄰近區域確保噪聲小。因為其系統中采納了高時鐘頻率。始終產生一個不失真的正弦波供電電流。電動機不會出現轉距脈動。因此，消退了振動和噪聲。3.電梯限制技術。所謂電梯限制技術是指電梯的傳動系統及操縱系統的電氣自動限制。作為我國20世紀70年頭電梯的主要標記是溝通雙速電梯。其調速方法是采納變更電梯牽引電動機的極對數，兩種或兩種不同級對數的繞組，其中極數少的繞組稱為高速繞組，極數多的繞組稱為低速繞組。高速繞組用于電梯的起動及穩速運行，低速繞組用于制動及電梯的修理。80年頭初，VVVF變頻變壓系統限制的電梯問世。它采納溝通電動機驅動，卻可以達到直流電動機的水平，目前限制速度已達6米/秒。它的體積小，重量輕，效率高，節約能源等幾乎包括了以往電梯的全部優點。是目前最新的電梯拖動系統。電梯在垂直運行過程中，有起點站也有終點站。對于三層樓以上的建筑物的電梯，起點站和終點站之間還沒有停靠站，起點站設在一樓，終點站設在最高樓。設在一樓的起點站稱為基站，起點站和終點站稱為兩端站，兩端站之間稱為中間站。各站廳外設有呼喚箱，箱上設置有供乘用人員呼喚電梯用的呼喚按鈕或觸鈕，一般電梯在兩端站的呼喚箱上各設置一只按鈕或觸鈕。中間層站的呼喚箱各設置兩只按鈕或觸鈕。對于無司機限制的電梯，在各層站的呼喚箱上均設置一只按鈕或觸鈕。而電梯的轎廂內部設置有（雜物電梯除外）操縱箱。操縱箱上設置有手柄開關或與層站對應的按鈕或觸鈕，操縱箱上的按鈕或觸鈕城內指令按鈕或觸鈕。外指令按鈕或觸鈕發出的電信號稱為外指令信號，內指令按鈕或觸鈕發出的電信號成為內指令信號。20世紀80年頭中期后，觸鈕已