基于PLC的船舶起货机控制系统设计外文.docx

基于PLC的船舶起货机控制系统设计外文.docx

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基于PLC的船舶起货机控制系统设计外文

DesignandImplementationofPLC-BasedMonitoringControlSystemforInductionMotor

ZHUShao-ying，XUYu，HeZheng-wen

XianJiaotongUniversity，Xian710049，P.R.China

Abstract：

Theimplementationofamonitoringandcontrolsystemfortheinductionmotorbasedonprogrammablelogiccontroller（PLC）technologyisdescribed.Also,theimplementationofthehardwareandsoftwareforspeedcontrolandprotectionwiththeresultsobtainedfromtestsoninductionmotorperformanceisprovided.ThePLCcorrelatestheoperationalparameterstothespeedrequestedbytheuserandmonitorsthesystemduringnormaloperationandundertripconditions.TestsoftheinductionmotorsystemdrivenbyinverterandcontrolledbyPLCproveahigheraccuracyinspeedregulationascomparedtoaconventionalcontrolsystem.TheefficiencyofPLCcontrolisincreasedathighspeedsupto95%ofthesynchronousspeed.Thus,PLCprovesthemselvesasaveryversatileandeffectivetoolinindustrialcontrolofelectricdrives.

Keywords：

Computer-controlledsystems,computerizedmonitoring,electricdrives,inductionmotors,motioncontrol,programmablelogiccontrollers（PLCs）,variable-frequencydrives,voltagecontrol.

I.INTRODUCTION

Sincetechnologyformotioncontrolofelectricdrivesbecameavailable,theuseofprogrammablelogiccontrollers（PLCs）withpowerelectronicsinelectricmachinesapplicationshasbeenintroducedinthemanufacturingautomation[1],[2].Thisuseoffersadvantagessuchaslowervoltagedropwhenturnedonandtheabilitytocontrolmotorsandotherequipmentwithavirtuallyunitypowerfactor[3].ManyfactoriesusePLCsinautomationprocessestodiminishproductioncostandtoincreasequalityandreliability[4]–[9].Otherapplicationsincludemachinetoolswithimprovedprecisioncomputerizednumericalcontrol（CNC）duetotheuseofPLCs[10].Toobtainaccurateindustrialelectricdrivesystems,itisnecessarytousePLCsinterfacedwithpowerconverters,personalcomputers,andotherelectricequipment[11]–[13].Nevertheless,thismakestheequipmentmoresophisticated,complex,andexpensive[14],[15].

FewpaperswerepublishedconcerningdcmachinescontrolledbyPLCs.Theyreportboththeimplementationofthefuzzymethodforspeedcontrolofadcmotor/generatorsetusingaPLCtochangethearmaturevoltage[16],andtheincorporationofanadaptivecontrollerbasedontheself-tuningregulatortechnologyintoanexistingindustrialPLC[17].Also,othertypesofmachineswereinterfacedwithPLCs.Thereby,anindustrialPLCwasusedforcontrollingsteppermotorsinafive-axisrotorposition,directionandspeed,reducingthenumberofcircuitcomponents,loweringthecost,andenhancingreliability[18].Forswitchedreluctancemotorsasapossiblealternativetoadjustablespeedacanddcdrives,asinglechiplogiccontrollerforcontrollingtorqueandspeedusesaPLCtoimplementthedigitallogiccoupledwithapowercontroller[19].OtherreportedapplicationconcernsalinearinductionmotorforpassengerelevatorswithaPLCachievingthecontrolofthedrivesystemandthedataacquisition[20].Tomonitorpowerqualityandidentifythedisturbancesthatdisruptproductionofanelectricplant,twoPLCswereusedtodeterminethesensitivityoftheequipment[21].

II.PLCASSYSTEMCONTROLLER

APLCisamicroprocessor-basedcontrolsystem,designedforautomationprocessesinindustrialenvironments.Itusesaprogrammablememoryfortheinternalstorageofuser-orientatedinstructionsforimplementingspecificfunctionssuchasarithmetic,counting,logic,sequencing,andtiming[23],[24].APLCcanbeprogrammedtosense,activate,andcontrolindustrialequipmentand,therefore,incorporatesanumberofI/Opoints,whichallowelectricalsignalstobeinterfaced.InputdevicesandoutputdevicesoftheprocessareconnectedtothePLCandthecontrolprogramisenteredintothePLCmemory（Fig.1）.

Fig.1.ControlactionofaPLC.

III.CONTROLSYSTEMOFINDUCTIONMOTOR

InFig.2,theblockdiagramoftheexperimentalsystemisillustrated.Thefollowingconfigurationscanbeobtainedfromthissetup.

a）Aclosed-loopcontrolsystemforconstantspeedoperation,configuredwithspeedfeedbackandloadcurrentfeedback.Theinductionmotordrivesavariableload,isfedbyaninverter,andthePLCcontrolstheinverterV/foutput.

b）Anopen-loopcontrolsystemforvariablespeedoperation.TheinductionmotordrivesavariableloadandisfedbyaninverterinconstantV/fcontrolmode.

c）Thestandardvariablespeedoperation.Theinductionmotordrivesavariableloadandisfedbyaconstantvoltage-constantfrequencystandardthree-phasesupply

Theopen-loopconfigurationb）canbeobtainedfromtheclosed-loopconfigurationa）byremovingthespeedandloadfeedback.Ontheotherhand,operationc）resultsiftheentirecontrolsystemisbypassed.

IV.HARDWAREDESCRIPTION

Thecontrolsystemisimplementedandtestedforawoundrotorinductionmotor,havingthetechnicalspecificationsgiveninTableI.Theinductionmotordrivesadcgenerator,whichsuppliesavariableRload.Thethree-phasepowersupplyisconnectedtoathree-phasemainswitchandthentoathree-phasethermaloverloadrelay,whichprovidesprotectionagainstcur-rentoverloads.Therelayoutputisconnectedtotherectifier,whichrectifiesthethree-phasevoltageandgivesadcinputtotheinsulatedgatebipolartransistor（IGBT）inverter.Itstechnicalspecifications[25]aresummarizedinTableII.TheIGBTinverterconvertsthedcvoltageinputtothree-phasevoltageoutput,whichissuppliedtothestatoroftheinductionmotor.Ontheotherhand,theinverterisinterfacedtothePLC-basedcontroller.

Fig.2Electricaldiagramofexperimentalsystem.

TABLEIINDUCTIONMOTORTECHNICALSPECIFICATIONS

TABLEIIINVERTERTECHNICALSPECIFICATIONS

ThiscontrollerisimplementedonaPLCmodularsystem[5],[26]–[28].ThePLCarchitecturereferstoitsinternalhardwareandsoftware.Asamicroprocessor-basedsystem,thePLCsystemhardwareisdesignedandbuiltupwiththefollowingmodules[29]–[37]:

·centralprocessorunit（CPU）

·discreteoutputmodule（DOM）

·discreteinputmodule（DIM）

·analogoutputsmodule（AOM）

·analoginputsmodule（AIM）

·powersupply.

OtherdetailsofthePLCconfigurationareshowninTablesIIIandIV.

Aspeedsensorisusedforthespeedfeedback,acurrentsensorisusedfortheloadcurrentfeedback,andasecondcurrentsensorisconnectedtothestatorcircuits[32].Thus,thetwofeedbackloopsoftheclosed-loopsystemaresetupbyusingtheloadcurrentsensor,thespeedsensor,andtheAIM.

V.RESULTS

Thesystemwastestedduringoperationwithvaryingloadsincludingtestsoninductionmotorspeedcontrolperformanceandtestsfortripsituations.ThePLCmonitorsthemotoroperationandcorrelatestheparametersaccordingtothesoftware.

Atthebeginning,forreferencepurposes,theperformanceofinductionmotorsuppliedfromastandard380V,50-Hznetworkwasmeasured.Then,theexperimentalcontrolsystemwasoperatedbetweennoloadandfullload（1.0N

m）inthetwodifferentmodesdescribedinSectionIII:

a）inductionmotorfedbytheinverterandwithPLCcontrol;

b）inductionmotorfedbytheinverter.

TherangeofloadtorqueandofspeedcorrespondstothedesignofthePLChardwareandsoftwareasdescribedintheprevioussections.

Thespeedversustorquecharacteristicswerestudiedintherange500–1500r/minandisillustratedinFig.7.Theresultsshowthatconfigurationb）operateswithvaryingspeed-varyingloadtorquecharacteristicsfordifferentspeedsetpoints

.Configurationa）operateswithconstant-speed-varyingloadtorquecharacteristicsinthespeedrange0–1400r/minand0–100%loads.However,intherangeofspeedshigherthan1400r/minandloadshigherthan70%,thesystemoperateswithvarying-speed-varying-loadandtheconstantspeedwasnotpossibletobekept.Thus,for

1400r/minbothcon-figurationsa）andb）haveasimilartorque-speedresponse.ThisfactshowsthatPIcontrolforconstantspeedasimplementedbythesoftwarewithPLCiseffectiveatspeedslowerthan93%ofthesynchronous.

Fig.6.Flowchartofcutoff/restartmotorsoftware.

Theefficiencyfordifferentvaluesof

wasalsostudied.InFig.8,theefficiencyisshownnormalized,usingasbasevalueor1p.u.theefficiencyoftheinductionmotorsuppliedfromthestandardnetwork.AsdepictedinFig.8,theresultsshowthatconfigurationa）inallcaseshasahigherefficiencythanconfigurationb）.Also,atoperationwithloadshigherthan70%,thenormalizedefficiencyis

>1,meaningthattheobtainedefficiencywithPLCcontrolishigherthantheefficiencyofinductionmotoroperatedfromthestandard380-V,50-HznetworkwithoutthecontrolofPLCandwithouttheinverter.Accordingtothisfigure,theefficiencyofPLC-controlledsystemisincreasedupto10–12%comparedtothestandardmotoroperation.

Fromatheoreticalpointofview,ifweneglectmagnetizingcurrent,anapproximatevaluefortheefficiencyis

wheresistheslipand

arethestatorandrotorwindingresistances,respectively.AscanbeseenfromFig.7,thePLC-controlledsystema）workswithverylowslipvalues,almostzero.Inallspeedandloadtorqueconditions,theconfigurationa）hasasmallerslipthanconfigurationb）,thusthehighervaluesofefficiencycanbejustifiedandespeciallyathighspeedsandfrequencies.Atlowerfrequencies,themagneticfluxincreasesand,thus,thereisanincreaseinmagnetizingcurrentresultinginincreasedlosses.

Thissystempresentsasimilardynamicresponseastheclosed-loopsystemwithV/fspeedcontrol.Itstransie