DESIGN AND ANALYSIS OF FUZZY LOGIC BASED SLIDING MODE CONTROLLER INDUCTION MOTOR

InternationalJournalofElectricaland ElecronicsEngineering(IJEEE)

ISSN(P):2278–9944;ISSN(E):2278–9952

Vol.11,Issue1,Jan–Jun2022;1–14 ©IASET

DESIGNANDANALYSISOFFUZZYLOGICBASEDSLIDINGMODECONTROLLER INDUCTIONMOTOR

MNaliniDevi1&Dr.R.SrinuNaik2

1ResearchScholar,DepartmentofElectricalEngineering,AUCollegeofEngineering,Vishakhapatnam, AndhraPradesh,India

1AssistanceProfessor,MGIT,Hyderabad,India

2AssistantProfessor,DepartmentofElectricalEngineering,AUCollegeofEngineering,Vishakhapatnam, AndhraPradesh,India

ABSTRACT

IncomparisontoPIDcontroller,thePIcontrollerissimplerbutexhibitsslowerresponseandalsoprovidessomesteady stateerrorinspeed.PerhapsPIcontrollercanbeeasilyimplementedwithsimpleoperationalamplifiercircuits.Nonlinear controlsystemsareaffectedbyinaccuraciesintheplantmodel.SMCisconsideredasanimportantcontroltechniquefor suchsortofcontrolproblems.Atransferfunction,afeedbackcontrollawandsomemodelsrepresentingtheuncertainty arethetypicalcomponentsofarobustcontroller.TheSMCisrobustbutslowandsuffersfromtheproblemofchattering apartfrombeingmoredifficulttorealize.AdaptiveSlidingModeController(ASMC),ontheotherhand,isfast,more robust,andfreefromproblemofchattering.However,itrequiresalargermemoryforrealtimeimplementationandis difficulttorealize.HenceFuzzySlidingModeController(FSMC)isproposedanditisfoundtoperformwellascompared toASMC,intermsofrobustnessandlearningcapability

KEYWORDS:InductionMotor,FLCBasedSlidingModeController,PIController,IndirectVectorControl

ArticleHistory

Received:16Jun2022|Revised:20Jun2022|Accepted:25Jun2022

INTRODUCTION

About50%oftotalelectricalenergyproducedisconsumedbyindustriesallovertheglobe.Aneconomicalandmore practicalmeanstolimitenergyusageistheenergyconservation.Becauseofitsbenefitslikereliability,robustness, maintenancefreeoperationandlowcost,theInductionMotor(IM)isoneofthebulkconsumersofelectricalenergy.The IMoccupiesamajorpartofthetotalelectricalload[1].A

Smallincrementinefficiencyofthesemotorsbyprovidingenhancedcontroloroptimaldesigncanresultina significantdropinenergycost.Nonlinear,complexandtimevaryingdynamicsaretheimportant

CharacteristicsofIMs.ManyoftheIMproblemsrelatedtocontrolhavebeensolvedbymeansofvectorcontrol techniques.Blaschkewasthepioneer

Toworkontheprincipleofvectorcontrolandthiswasfollowedbyseveralresearchersintheirresearchpaperson theaspectsofvectorcontrol.Inscalarcontrol,theIMmayexhibitanexcellentresponseduringsteady-statecondition.

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However,itsdynamicbehaviourisnotsatisfactory.Theprimereasonforthislimitationisduetothefactthatthecontrolof torqueandfluxarenotdelinkedfromeachotheraswiththecaseofDCmotor.TheIMsaresensitivetodriveparameter variationsduetotemperatureandfluxmeasurementsorspeedestimationdeviations.

variationsduetotemperatureandfluxmeasurementsorspeedestimationdeviations.

Foreasycomputation,theorderreductionisdonetosimplifythenonlinearplants.Imprecisionoccursdueto modelsimplificationanduncertaintiesexistingintheplant.IndustrialPlantswithlessparametervariationsand disturbancesmakeuseoftherobustcontrollerstosolvetheuncertainties.Amongtherobustcontroltechniquessuitablefor IM,SlidingModeController(SMC)wasstudiedbymanyinvestigators.ARussianScientistin1950sdevelopedSMC whichisavariablestructuredcontroller.TheSMCmethodisusedinthecagemotorapplicationsrequiringfasterdynamic responsefrombothduringstartandspeedreversal.IntheSMC,manycontinuousfunctionsaredefinedtomapthestateof thesystemtoaspecificcontrolsurface.Therearemanytrajectorieswhichslidealongtheboundariesofthecontrol structure.TheproblemfoundintheSMCischattering,whichoccursbecauseofitsfastswitchingofcontrolsignals.

Normallyswitchedcontrollershavemanyimperfectionsthatlimitswitchingfrequencyinreal-timesystems. Aroundtheslidingsurface,unwantedoscillationsofthetrajectoriesoccur.Thesearereferredtoaschatteringeffect. Chatteringproblemsalsoexistwhenaprocessorsamplesthesignals.Chatteringproblemindigitalcircuitsoccursbetween anytwosamplinginstancesbecausetheplantoperatesinopenloopsystem.Toavoidthechatteringeffects,intelligent controllersarepreferred.Perhaps,methodslikeFuzzyInferenceSystems(FISs)aretherightchoiceforthedesignofmotor controllersinindustriestoreplacethePIDcontrollers.FuzzySMC(FSMC)providesanalternativesolutiontoPID controller,especiallyfornonlinearcontrolproblemslikethecontrolofIM.FSMCwithclosedloopoperationinvector controlmodeisalsopresentedinthisresearchwork.

responsefrombothduringstartandspeedreversal.IntheSMC,manycontinuousfunctionsaredefinedtomapthestateof thesystemtoaspecificcontrolsurface.Therearemanytrajectorieswhichslidealongtheboundariesofthecontrol Chatteringproblemsalsoexistwhenaprocessorsamplesthesignals.Chatteringproblemindigitalcircuitsoccursbetween anytwosamplinginstancesbecausetheplantoperatesinopenloopsystem.Toavoidthechatteringeffects,intelligent controlmodeisalsopresentedinthisresearchwork.

SpeedcontrolofindirectvectorcontrolledinductionmotorusingPIcontrollerfailedtoachieveaccuratespeed responsewhenexternalparameterssuchasloadtorque,momentofinertiaandviscousfrictionvariedwithknownbounds. InthischaptertheslidingmodecontrolisintroducedinplaceofPIcontrollertoachievegoodandaccurateresponseif limitsontheexternalcontrollervariationsareknown.Slidingmodecontroltechniqueisanonlinearcontroltechnique applicabletosystemofordern,butpresentedhereonlyforafirst-ordersystem.

Aswitchingsurfaceisdefinedandthecontrollawisdesignedtodrivethesystemstateontotheswitchingsurface insuchawaythatifthestateisonforonce,thesystemisconstrainedtoremainontheswitchingsurface.Thecontrollaw

Control. NAASRating2.96

IndirectVectorController

Figure1:SpeedControlofIMUsingIndirectVector Control.

isdesignedbyknowingtheboundsofparametervariationsonthebasisofLyapunov’sstability.Theresponsesofstep commandandimpactduetointernalcontrollervariations,suchasrotorresistanceandinductancearestudied.Theblock diagramforcompleteimplementationofspeedcontroller,basedonslidingmodeisshowninFig-3Slidingmodecontroller designisexplainedindetailtogeneratetheq-axissynchronousframecurrentbyprocessingtheerrorproducedby comparingthecommandspeedandactualspeed,whichissensedbythesensor.Theslipspeedcommandsignalis generatedfromthefluxcommandsignal,andthenaddedtotheactualspeedtogeneratetheunitvectorwhichisusedto convertstatorq-daxiscurrentscommandinsynchronousreferencetostatorreferenceframe.Thestatorreferenceframe currentcommandsareagainconvertedintoab-ccurrentcommandsignals.Thea-b-ccurrentcommandsignalsiscompared withcorrespondingactualcurrentthroughahysteresisbandcontrollertogeneratethepulsesfortriggeringthesixswitches of3phaseinverter[3,4,5].

VectorcontrolofInductionmotordriveshowsquickreaction,smoothexecution,andhighpowerfulreactionwith speedvariationandtransientcircumstances.ConcerningphasorchartofIndirectVectorControlstrategyforenlistment engine,thisisdisplayedinFigure2

Figure2:SchematicofFuzzySlidingMode Controller.

Figure3:PhasorRepresentationofIndirect VectorControlIM

anddr/dt=0canbeswitchedtoequation4,sothattherotorfluxissetasFigure2showsadiagramoftheFuzzy slidercontrolvalveforindirectvectorcontrolInductionmotoryouwant *.FuzzyLogiccontrollerinrecenttimes, fuzzylogiccontroltechniquesarepreferredinmanyindustrialapplications.FuzzyLogicControllers(FLCs)arerule-based systemswhichcaneasilyrepresentthehumanknowledge.The‘fuzzysets’wereintroducedbyLotfiZadehintheyear1965, asanextensionoftheconventionalsettheory.Inconventionalsettheory,anobjectiseitheramemberornon-memberofa set.Thefuzzyconceptistointroducethatpartialmembershipfunctionispossible.ThemostimportantpartoftheFLC systemistheFuzzyControlRulesassociatedthroughafuzzyinferencesystem.Technologicaladvancesinsolid-state powerelectronicsdevicesandhighcomputingcapabilitydigitalcontrollershavemadeACmotordriveapplicationssimpler. Inthispartofthethesis,theapplicationofSMCforefficientthreephaseIMisinvestigated.Thecentralfocusofthe proposedresearchistoimprovetheSMCtechniquewithaprimeintentofchatteringmitigation.Thefeasibilityofthe proposeddesignforindustrialapplicationsishighlightedwithexperimentalstudiesonprototypemodelsandhardware-inloopsimulations.ThehardwareimplementationofFSMCisdonebyusinglowcosthardware-in-loopstructureusing FPGAsforbetterdynamicresponse.Thereal-worldapplicationsoftheFSMCarementionedbelow:

 Energypreservationmodeisnecessaryinrecentdriveunits.Theincreasingcurrentiskeptlowduringriseinspeed andsoSMCachievesasmoothtransitionofspeed.Intextileindustries,vectorcontrolofIMdriveisused.

 ItrequirestheACmotortofunctionatvaryingspeedsandtorquelevelstosuitvariousloads.AsinFigure1.4the basicfuzzylogicsystemconsistsoffuzzification,inferencemechanismand

Output/Input

Thedesignofthefuzzysystemprovidingflexibleinputandoutput.Themainlyimportantvariablesthatcomein handyarethedefaultspeedcontrollerselectedasthespeederror

FUZZIFICATION

Theinputandoutputparametersarenormalizedtoliebetween0and1.Fuzzificationistheprocessofmodifyingthecrisp variablestofuzzyvariables.Theinputvariablesarerepresentedbytriangularrepresentationofmembershipfunctions.

LinguisticvariablesPS(PositiveSmall),PM(PositiveMedium)andPB(PositiveBig),Z(zero),NB(NegativeBig),NM (NegativeMedium),NS(NegativeSmall),areshowninFigures5(a),5(b)and5(c).Inordertoobtainbettercontrol,the membershipfunctionsnearthezeroregionsshouldbemadenarrower.Hence,themembershipfunctionscanbeadjustedto someextentonatrialanderrorbasistoimprovedynamicperformance.TheinputvariablesofFSMCareErrorand Change-in-Error,andoutcomevariableisTorqueHereErroristhedivergencebetweensituationslidinglineandactual representativepointofthesystemonthephaseplane

Figure4:ShowsaBlockDiagramofaFuzzyInterference SystemwithLogicalControllerConsistsofFourBasic MajorComponents:DefuzzificationFuzzy,FuzzyInference EngineandKnowledgeBase.

Figure4FuzzyInterferencesystem

FuzzyInferenceandRuleBase

TheFISisasetofarulebasedatasystem.Asampleruleisasgivenbelow.

IfErrorisNBandChangeinErrorisNB,ThenTisNB

Where,TdenotesTorque.Forty-ninerulesarecreatedusingFuzzyLogic.InthecaseofFSMC,thecontrolruleis designedinsuchawaythattheactualtrajectoryalwaysturnstowardsthereferenceslidinglineonthephaseplane.The actualtrajectoryalsodoesnotcrossthereferenceslidinglineonthephaseplane.Therebytheexistenceconditionis satisfied.Theformationoftherulebasecanbedonebasedonthefollowing,

 Experienceandcontrolknowledgederivedfromtheusersandoperatingmanual,

 Usercontrolactionsformulatedintermsofinput-outputoperatingdata,

Figure5:(A)DegreeofMembershipVs.Error.

Figure5:(B)DegreeofMembershipVs.ChangeinError.

Figure5:(C)DegreeofMembershipVs.Torque.

 Fuzzymodellingofthecontrolprocessand

 ApplyingIntelligenttechniqueslikeneuralnetwork, SlideModeController

AslidingmodecontrolofIMwithdynamicvariationswhereinthesystemchangesbasedonthecurrentstateofthe structure.FSMCisanonlinearcontrolappliedtobothnonlinearandlinearplantswhichispartoftheadoptivetechniques. FSMCcancontrollargerspeedswithgreatcontrolofparametersvariationsandloadstorquesdisturbance.FSMCisa variablestructureofindependentcontrolscanbeviewedascombinedswitchinglogic.Aslidingsurfaceistobedesigned andwithappropriateswitchinglogicthedriveresponseisforcedtotrackorslidealongtheslidingsurfaceorplaneina phaseplanewithoutloaddisturbance.Aslipperysurfaceisdefinedonaglobalscalebythescalarequation.[8]s(e,ė,t)= 0When,asmoothvariable,Sis

Equation(8),indicatesthecontrolparametersdeterminedasofs(t)=0disregardingthedistributedvulnerability (L(t)=0)isachievedtheidealpresentationunderostensiblemodelanditisimplementedtoascomparableparametersas follows

Notwithstand,thevectorcontrolisexceptionallyboundarydelicate.Erraticboundaryvarieties,outsideload unsettlinginfluence,unmodelledandnonlinearelementsunfavourablyinfluencethecontrolexecutionoftheInduction motordrive.Inthismannerthecontrolexertioncan'tguaranteethetraditionalcontrolexecution.SubsequentlyFSMCtobe intendedtoorganizeoftheimpactoftheunappreciableaggravations

Whereghisarepresentscontrolgainconcernedwithupperlimitsofuncontrolledvariables,anddenoted withsgn(.) signfunction.

Now,theslidingmodecontrolrulebasedcontrollerprovidesextraordinaryperformanceduetothehighcontrol overplantanditsoperationfunctions,whichleadstodynamiccontroldialogandsystemconditions.Reducingthe discussionofthelimitsisusuallyintroducedintotheSMCcontroller,andthentheregulatoryStabilitywithintheLimits cannotbeguaranteedandinsufficientselectionofthethresholdvaluesmayresultinanunstabletrackingresponse.Itis thereforeasystemofcontrollingtheslidingmodes,inwhichanabstractthinkingapproachisusedtofollowthelawof slidingcontrol.

FuzzyLogicBasedSlideModeController

TheFuzzylogicbasedSMCusesasetoffuzzyrulesrepresentingthedecisionmakingprocesstocorrecttheimpactof definitesystemmotives.thepurposeofusingFSMCistoreplacethecontrollerwithacompetentmethodwithan

incomprehensiblelegalsystem.IncomprehensibleinputvectorssystemvehiclespeeddeviationΔωandaccelerationΔώ. AnincomprehensiblesetofinputandoutgoingmembershipfunctionsisdisplayedinFig.(3).Unexplainedoutputisa changeofreferencetorque(ΔTref{k})addedtothepreviousreferencetorquevalue(Tref{k-1}).Unintelligibleoutput setshavethesamelanguagevariablesthatareusedforinputsexceptthatanadditionalTtoindicatePositivetorque.The observationtable,inwhichthecorrelationbetweeninputvariables,ΔωandΔώ,alsodescribedtheoutputvariablesofthe abstractmindcontrolweredevelopedandappliedtosimulations.AlookouttableisprovidedinTable1.TheAdvanced SmallModeMethodhasbeenusedtoobtainvagueexitrulesstage,asfollows:

Table-1representsthelookuptableoffuzzylogicbasedSlidingmodecontrollerwhichdefinethebondbetween outputvariableinafuzzyvariables.FSMCisusedandmodifiedtofindouttheexpectedtorque(Tref)systemindicator showninFig.(2).FSMCoutputissumofpreviousreferencetorqueTref{k-1}andcalculatedcurrentTref{k}using equation(15).

Figure6:InputandOutputFuzzyMemberships.

Figure7:InputAndOutputFuzzyMemberships.

RESULTSANDDISCUSSIONS

VariousdistractionsweremodelledtotestvehicleperformanceusingDTCunderPIandFLCbasedslidingmodecontrols. Figure9representsacomparativeoftheflexibleresponseofavehicleinstalledoutsidethecurrentlimitandwithoutωref loadequalto300,750and1500rpm.TheproposedFSMCspeedcontrolprovidedamoreflexibleresponse,intermsof shootingandrotationpercentage,comparedtothestandardtraditionalcontrolswithKp=20andKi=0.1.Thefigure numbers10-12representtheperformanceoftheDTCusingthePIthecontrollerandfigurenumbers14-16representthe SMC-FLCbasedDTCbycomparingthevariablevehicleresponsewheninitiatedatthecurrentlimitagainstloadingand fullload,respectively,atωrefequals750,1500and500rpm.ThebestperformanceinspeedcontrolofIMasachievedby FSMCespeciallyinthecaseoffullload.Fig.13representsthesimulinkmodeloffuzzylogicbasedslidingmodecontrol onthreephaseinductionmotorwhichachievedbetterperformanceascomparedtothetraditionalcontrollerSimulink ImplementationofPIbasedSlidingmodecontrollerforIM

Figure8:OutputSurfaceofFLC.

Figure9:SimulinkImplementationofDtcPiCircuit.

Figure10:Speedinm/s.

Figure11:TorqueinM/S.

Figure12:StatorCurrents

SimulinkImplementationofFLCbasedSlidingmodecontrollerforIM

RESULTS

Figure13:SimulinkImplementationofDtcFuzzyCircuit.

Figure14:SpeedinM/S.

Figure15:TorqueinM/S.

CONCLUSION

Thispaperhassuccessfullydemonstratedtheuseofanindirectslidingmodecontrolsystemforinductiondrivefocusedon indirectlocationtrackingcommandsfromtimetotime.Thedesignanddescriptionoftheclassicslidingmode(SMC) controllerispresentedindetail.Then,ablurringmindcontrolisusedtotunethecontrollertoremoveoscillationsand improvesystemperformance.However,advancedlogicalcontrolanalysis,designandspeedregulationofthevector controlledIMusingvariouscontrollersdemonstratedthroughthecomputersimulationusingMATLAB/Simulink.Many resultsarepresentedtoshowthecapabilityofFLCbasedSMCascomparedtoothercontroltechniques.simulationresults arepresentedtoillustratetheeffectivenessofdesignedcontrollerforthevectorcontrolledIM

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BIOGRAPHIES