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Journal of Engineering Sciences, Assiut University, Vol. 40, No. 4, pp.1121 -1135, July 2012 1121 SPEED CONTROL DESIGN OF A PMSM BASED ON FUNCTIONAL MODEL PREDICTIVE APPROACH A. A. Hassan 1 and Ahmed M. Kassem 2 1 Electrical Dep., Faculty of Engineering, El-Minia University, Egypt 2 Control Tech. Dep., Industrial Education College, Beni-Suef University, Egypt, Email:[email protected] (Received January 19, 2012 Accepted May 5, 2012) This paper investigates the application of the model predictive control (MPC) approach to control the speed of a permanent magnet synchronous motor (PMSM) drive system. The MPC is used to calculate the optimal control actions including system constraints. To alleviate computational effort and to reduce numerical problems, particularly in large prediction horizon, an exponentially weighted functional model predictive control (FMPC) is employed. In order to validate the effectiveness of the proposed FMPC scheme, the performance of the proposed controller is compared with a classical PI controller through simulation studies. Obtained results show that accurate tracking performance of the PMSM has been achieved. KEYWORDS: Predictive control, Functional model predictive control, permanent magnet synchronous motor. 1. INTRODUCTION Permanent magnet synchronous motors fed by PWM inverters are widely used for industrial applications, especially servo drive applications, in which constant torque operation is desired. In traction and spindle drives, on the other hand, constant power operation is desired [1]. The inherent advantages of these machines are light weight, small size, simple mechanical construction, easy maintenance, good reliability, and high efficiency. Generally speaking, the applications of the PMSM drive system include two major areas: the adjustable-speed drive system and the position control system. The adjustable-speed drive system has two control-loops: the current-loop and the speed loop. To improve the performance of the PMSM drive system, a lot of research has been done. In general, the research has focused on improvement of the performance related to current-loop, speed loop, and/or position loop. The PMSM drive system has been controlled using a PI controller due to its simplicity. The PI controller, however, can not provide good performance in both transient and load disturbance conditions. Several researchers have investigated the speed controller design of adjustable speed PMSM systems to improve their transient responses, load disturbance rejection capability, tracking ability, and robustness [2-11]. The MPC controller generally requires a significant computational effort. As the performance of the available computing hardware has rapidly increased and new faster algorithms have been developed, it is now possible to implement MPC to command fast systems with shorter time steps, as electrical drives. Electric drives are of particular interest for the application of MPC for at least two reasons: 1) They fit in the class of systems for which a quite good linear model can be

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Journal of Engineering Sciences, Assiut University, Vol. 40,No. 4, pp.1121 -1135,July 2012 1121 SPEED CONTROL DESIGN OF A PMSM BASED ON FUNCTIONAL MODEL PREDICTIVE APPROACH A. A. Hassan 1 and Ahmed M. Kassem 2 1Electrical Dep., Faculty of Engineering, El-Minia University, Egypt 2 Control Tech. Dep., Industrial Education College, Beni-Suef University, Egypt, Email:[email protected] (Received January 19, 2012 Accepted May 5, 2012) Thispaperinvestigatestheapplicationofthemodelpredictivecontrol (MPC)approachtocontrolthespeedofapermanentmagnetsynchronous motor(PMSM)drivesystem.TheMPCisusedtocalculatetheoptimal controlactionsincludingsystemconstraints.Toalleviatecomputational effortandtoreducenumericalproblems,particularlyinlargeprediction horizon,anexponentiallyweightedfunctionalmodelpredictivecontrol (FMPC)isemployed.Inordertovalidatetheeffectivenessoftheproposed FMPC scheme, the performance of the proposed controller is compared with aclassicalPIcontrollerthroughsimulationstudies.Obtainedresultsshow that accurate tracking performance of the PMSM has been achieved. KEYWORDS:Predictivecontrol,Functionalmodelpredictivecontrol, permanent magnet synchronous motor. 1. INTRODUCTION PermanentmagnetsynchronousmotorsfedbyPWMinvertersarewidelyusedfor industrialapplications,especiallyservodriveapplications,inwhichconstanttorque operationisdesired.Intractionand spindledrives,ontheotherhand,constant power operationisdesired[1].Theinherentadvantagesofthesemachinesarelightweight, smallsize,simplemechanicalconstruction,easymaintenance,goodreliability,and highefficiency.Generallyspeaking,theapplicationsofthePMSMdrivesystem includetwomajorareas:theadjustable-speeddrivesystemandthepositioncontrol system. The adjustable-speed drive system has two control-loops: the current-loop and thespeedloop.ToimprovetheperformanceofthePMSMdrivesystem,alotof researchhasbeendone.Ingeneral,theresearchhasfocusedonimprovementofthe performance related to current-loop, speed loop, and/or position loop. ThePMSMdrivesystemhasbeencontrolledusingaPIcontrollerduetoits simplicity.ThePIcontroller,however,cannotprovidegoodperformanceinboth transientandloaddisturbanceconditions.Severalresearchershaveinvestigatedthe speedcontrollerdesignofadjustablespeedPMSMsystemstoimprovetheirtransient responses, load disturbance rejection capability, tracking ability, and robustness [2-11]. TheMPCcontrollergenerallyrequiresasignificantcomputationaleffort.As theperformanceoftheavailablecomputinghardwarehasrapidlyincreasedandnew fasteralgorithmshavebeendeveloped,itisnowpossibletoimplementMPCto commandfastsystemswithshorter timesteps,aselectricaldrives.Electricdrivesare of particular interest for the application of MPC for at least two reasons: 1)Theyfitintheclassofsystemsforwhichaquitegoodlinearmodelcanbe A. A. Hassan and Ahmed M. Kassem 1122 obtained both by analytical means and by identification techniques; 2)Boundsondrivevariablesplayakeyroleinthedynamicsofthesystem; indeed,twomainapproachesareavailabletodealwithsystemconstraints: antiwinduptechniqueswidelyusedintheclassicalPIcontrollers,andMPC. Thepresenceoftheconstraintisoneofthemainreasonswhy,forexample, state space controllers have limited application in electrical drives. Inspiteoftheseadvantages,MPCapplicationstoelectricaldrivesarestill largelyunexploredandonlyfewresearchlaboratoriesareinvolvedonthem.For exampleGeneralizedPredictiveControl(GPC)aspecialcaseofMPChasbeen appliedtoinductionmotorsforonlycurrentregulation[12]andlaterforspeedand current control [13]. In [14], the more general MPC solution has been adopted for the design of the current controller in the same drive. In this paper a centralized MPC with large prediction horizon for PMSM speed controlispresented.Theproposedcentralizedschemeimprovesthecontrol performance in a coordinated manner.AnotherchallengeofcentralizedMPCforPMSMisitslargecomputationaleffort needed.Toovercomethisdrawback,afunctionalMPCwithorthonormalbasis Laguerrefunction[15]ispresented.ThepresentedfunctionalMPCreduces computationaleffortsignificantlywhichmakesitmoreappropriateforpractical implementation. In addition, an exponential data weighting is used to reduce numerical issue in MPC with large prediction horizon [16,17]. To verify the effectiveness of the proposed scheme,time-basedsimulationsarecarried out. The resultsobtainedproved thatthefunctionalMPCisabletocontrolsuccessfullythePMSMsysteminthe transient and steady state cases. 2. DYNAMIC MODEL OF PMSM ThedynamicmodelofthePMSMcanbedescribedinthed-qrotorframeasfollows [18]: ||

\|+ =q r d d dLiPri vLidtd21(1) ( )||

\|+ =m d r q q qLiPri vLidtd 21(2) ( )r L e rB T TJ dtd =1(3) Where q t q m ei k iPT = = 2 23 r rdtd =(4) whereristhestatorresistance, di isthed-axisstatorcurrent, qi istheq-axisstator current,Listhestatorinductance,d/dtisthedifferentialoperator,Pisthepole numbers, r isthemechanicalrotorspeed,m isthefluxlinkagegeneratedfromthe permanentmagnetmaterial, eT istheelectromagnetictorqueand r istherotor position. SPEED CONTROL DESIGN OF A PMSM BASED ON 11233. LINEARISED MODEL ThebasicprincipleincontrollingthePMSMisbasedonfieldorientation.Thisis obtained by letting the permanent magnet flux linkage be aligned with the d-axis, and the stator current vector is kept along the q-axis direction. This means that the value of di is kept zero in order to achieve the field orientation condition. Since the permanent magnet flux is constant, therefore the electromagnetic torque is linearly proportional to theq-axiscurrentwhichisdeterminedbyclosedloopcontrol.Asaresult,maximum torque per ampere can be obtained from the machine in addition to the achievement of highdynamicperformance.Applyingthefieldorientationconceptinequations(1-4), the linearised model of the PMSM can be described in a state space form as : Du Cx yBu Ax x+ =+ =&(5) Where[ ]Tr r q di i x =[ ]Td qv v u = ,[ ]LT d =((((((((

+=0 1 0 00 00 ) (2 202 2JBJkLipLr pip pLrAtmdo roqo ro, TLLB((((

=0 0100 0 01,TJE((

= 010 0 4. FUNCTIONAL MODEL PREDICTIVE CONTROL A.Model predictive Control Model predictive controluses an explicitmodel of systemto predict futuretrajectory of system states and outputs. This prediction capability allows solving optimal control problemonline,wherepredictionerror(i.e.containingdifferencebetweenthe predictedoutputandreferenceoutput)andcontrolinputactionareminimizedovera futurehorizon,possiblysubjecttoconstraintsonthemanipulatedinputs,statesand outputs. The optimization yields an optimal control sequence as input and only the first inputfromthesequenceisusedastheinputtothesystem.Atthenextsampling interval, the horizonis shiftedand the wholeoptimization procedureis repeated.The main reason for using this procedure, which is called receding horizon control (RHC), is that it allows compensating for future disturbance and modeling error. ThebasicstructureofmodelpredictivecontrolisdepictedinFig.1.An explicit model of the system is used to predict future output response chain y. Based on thepredictedsystemoutputandcurrentsystemoutput,theerroriscalculated.The A. A. Hassan and Ahmed M. Kassem 1124 errors,then,arefedtotheoptimizer.Intheoptimizer,thefutureoptimalcontrol sequence, u, is calculated based on the objective function and system constraints. Inthispaper,thestatespacemodelofthesystemisusedinthemodel predictivecontrol.Thegeneraldiscreteformofthestatespacemodelusedinmodel predictive control is of the form: ) ( ) () ( ) ( ) ( ) ( ) 1 (k x C k yk w F k d E k u B k x A k xzz z z z=+ + + = +(6) where k is the sampling instant, x is state vector, u is input vector, d represents system disturbance and w represents system noise model. Az, Bz, Cz, Ez and Fz are coefficients of system state space model and reflect the PMSM model in (5). The final aim of model predictive control is to provide zero output error with minimal control effort. Therefore, the cost function J that reflects the control objectives, is defined as: ( ) ( ) + + + + == =cNkkpNkref kk n u v k n y k n y n J1212) ( ) ( ) ( (7) Where k kv and respectively, the weighting factors for the prediction error and control energy ) ( k n y + kth step output prediction; ) ( k n yref+ kth step reference trajectory; ) ( k n u + kth step control action. wherethefirsttermreflectsthefutureoutputerrorandsecondtermreflectsthe consideration given to the control effort. The predicted output vector has dimension of 1Np where Np is the prediction horizon. u is control action vector with dimension of 1Nc that Nc is control horizon. In the model predictive control, the control horizon, Nc ,isalwayssmallerthanorequaltopredictionhorizon(Np). k kv and reflectingthe weights on the predicted error of predicted outputs and change in the control action. Theconstraintsofmodelpredictivecontrolincludeconstraintsofmagnitudeand change of input, state and output variables that can be defined in the following form. max min) ( u k n u u + , max min) ( u k n u u + max min) ( x k n x x + , max min) ( x k n x x + (8)max min) ( y k n y y + , max min) ( y k n y y + Solvingtheobjectivefunction(7)withsystemconstraint(8)givestheoptimalinput control sequence. B. Laguerre Based Model Predictive Control Intheclassicalmodelpredictivecontrol,thefuturecontrolsignalismodeledasa vector of forward shift operator with length of Nc . SPEED CONTROL DESIGN OF A PMSM BASED ON 1125[ ] ) 1 ( ),..., ( ),..., ( + + = cN n u k n u n u U (9) whereNcunknowncontrolvariablesintheoptimizationprocedure.However,large predictionhorizonisneededtoachievehighclosedloopperformance.Thatwould require large computational burden. Therefore, MPC may not be fast enough to be used as a real time optimal control for such case. AsolutiontothisdrawbackistheuseoffunctionalMPC.Inthefunctional MPC,futureinputisassumedtobealinearcombinationofafewsimplebase functions. In principle, these could be any appropriate functions. However in practice, a polynomial basis is usually used [19]. This approximation of input trajectory can be moreaccuratebyproperselectionofbasefunction.UsingfunctionalMPC,theterm usedintheoptimizationprocedurecanbereducedtoafractionofthatrequiredby classical MPC. Therefore, the computational load will be reduced largely. Inthispaper,orthonormalbasisLaguerrefunctionisusedformodelinginput trajectory. Laguerre polynomial is one of the most popular orthonormal base functions which has extensive applications in system identification [15]. The z-transform of mth Laguerre function is given by: 121 1((

= mma zaza za(10) where0a1isthepoleofLaguerrepolynomialandiscalledscalingfactorinthe literature.ThecontrolinputsequencecanbedescribedbythefollowingLaguerre functions: + =Nmm mk l c k n u1) ( ) ( (11) where lm is the inverse z-transform of m in the discrete domain. The coefficients cm are unknowns and should be obtained in the optimization procedure. The parameters a and Naretuningparametersandshouldbeadjustedbyuser.UsuallythevalueofNis selectedsmallerthan10thatisenoughformostpracticalapplications.Generally, choosing larger value for N increases the accuracy of input sequence estimation. C. Exponentially Weighted Model Predictive Control Closed loop performance of MPC depends on the magnitude of prediction horizon Np. Generally,byincreasingthemagnitudeofpredictionhorizon,theclosedloop performancewillbeimproved.However,practically,selectionoflargeprediction horizonislimitedbynumericalissue,particularlyintheprocesswithhighsampling rate. One approach to overcome this drawback is to use exponential data weighting in model predictive control [16]. D. Design of the proposed Functional Model Predictive Control Inthissection,theLaguerrebasedmodelpredictivecontrolandexponentially weightedmodelpredictivecontrolarecombinedinordertoalleviatecomputational effort and reduce numerical problems. At first, a discrete model predictive control with exponentialdataweightingisdesigned.Theinput,stateandoutputvectorsare changed in the following way: A. A. Hassan and Ahmed M. Kassem 1126 ((

+ + =((

+ + =((

+ = ) ( ),..., 1 () ( ),..., 1 () 1 ( ),..., (11) 1 ( 0ppNTppNTccN TN n x n y YN n x n x XN n u n u U (12) whereistuningparameterinexponentialdataweightingandislargerthan1.The state space representation of system with transformed variable is: ) ( ) ( ) () () 1 (n x C n yn u B n x A n x= + = + (13) Where /, /, /C C B B A A = = =The optimalcontrol trajectorywithtransformed variablescan beachievedby solving the new objective function and constraints. ( ) ( ) + + + + == =cNkkpNkref kk n u v k n y k n y n J121 ) ( ) ( ) ( (14) max minmax minmax minmax minmax minmax min) ( , ) ( ) (, ) ( ) ( , ) (y k n y yy k n y yx k n x xx k n x xu k n u uu k n u uk kk kk kk kk kk k + + + + + + (15) Bychoosinga>1,theconditionnumberofhessianmatrixwillbereduced significantly, especially for large values of prediction horizon (Np).This leads to a more reliable numerical approach. Aftersolvingnewobjectivefunctionwithnewvariables,thecalculatedinput trajectory should be transformed into standard variable with the following equation. ((

+ = ) 1 ( , ... ), ( )1(ccN o TN k u a k u a U(16) TheLaguerrebasedmodelpredictivecontrolandexponentiallyweighted model predictive control can be combined using the following systematic procedure: -Choosing of the proper tuning parameter . -Transforming the system parameters (A, B, C) and the system variables (U, X, Y) are transformed using equations (13) and (14). -Theobjectivefunctionwithitsconstraintsiscreatedbasedonequations(15)and (16). -OptimizingobjectivefunctionbasedonLaguerrepolynomialandthencalculating unknown Laguerre coefficients. SPEED CONTROL DESIGN OF A PMSM BASED ON 1127-Calculating input chain from equation (11). -Thecalculatedweightedinputchainistransformedintounweightedinputchain using equation (16) and applied on the plant. Fig. (1): Basic structure of model predictive control 5. SYSTEM CONFIGURATION The block diagram of the field oriented PMSM with the proposed FMPC is shown in figure(2).Allthecommandedvaluesaresuperscriptedwithasteriskinthediagram. The proposed system control consists of three loops. The first loop for the speed based on FMPC and theothers for thed-q currents based onPI controllers. Simulationsare carriedouttocomparetheperformanceofdesignedspeedcontrollerbyFMPCwith conventionalPIcontroller.TheinputandtheoutputoftheFMCareconsideredas speederrorandreferenceq-axiscurrentrespectively.Thecontrolparametersare assumed as in the following input weight matrix: =0.15INcNc output weight matrix: v=1INpNp The constraints are chosen such that, the q-axis stator current is normalized to be between 0 and 1, where 0 corresponds to zero and 1 corresponds to maximum stator current. Thus, max min1 0 u u u = = . The constraints imposed on the control signal are hard, whereas the constraints onthestatesaresoft,i.e.,smallviolationscanbeaccepted.Theconstraintsonthe states are chosen to guarantee signals stay at physically reasonable values as follows: max min4302200xixrq=|||

\||||

\||||

\|= The speed error is fed to the speed controller (FMPC) in order to generate the torque current command*qi . The flux current command *diis set to zero to satisfy the field orientation condition. The reference currents *qiand *diare compared withtheir respectiveactualcurrents.Theresultederrorsareusedtogeneratethevoltage A. A. Hassan and Ahmed M. Kassem 1128 commands *dvand *qvwhich are converted to three phase reference values*av , *bvand *cv inthestatorframe.Thesevoltagesignalsarecomparedwithtriangularcarrier signal and the output logic is used to control the PWM inverter. The entire system has been simulated on the digital computer using the Matlab /Simulink/Powerlibsoftwarepackage.Themotorusedinthesimulationprocedure has the following specifications [20]: PMSM : 1.5 kw, 2-pole, 4250 rpm Stator resistance : 1.6 ohm Stator inductances: L= 6.37 m.H. Permanent magnet flux : 0.19 Wb. Moment of inertia : 0.0001854kg.m2 Friction coefficient : 5.396e-005 N.m.s/rad Fig. (2): block diagram of the proposed PMSM speed control system 6. SIMULATION RESULTS Computer simulations have been carried out in order to validate the effectiveness of the proposed scheme. The simulation tests are carried out using Matlab/Simulink software package. Wherever, the state space model of the permanent magnet synchronous motor isprogrammedwiththefunctionalmodelpredictivealgorithmsinMATLABwork space.TheMPCcontrolalgorithmdependsonthesolutionofaconstrained optimization problem. Most designers choose Np (prediction horizon) and Nc (control horizon) inawaysuchthatthecontrollerperformanceisinsensitivetosmall adjustmentsinthesehorizons.Herearetypicalrulesofthumbforobtainingastable process: 1.Choosethecontrolintervalsuchthattheplant'sopen-loopsettlingtimeis approximately 2030 sampling periods (i.e., the sampling period is approximately one fifth of the dominant time constant). 2.Choose prediction horizon to be the number of sampling periods used in step 1. 3.Use a relatively small control horizon, e.g., 35. SPEED CONTROL DESIGN OF A PMSM BASED ON 1129SelectionofsuitablevaluesofaandNwillincreasethesystemoutput predictedvaluesaccuracyandhelptoimprovethesystemperformancewithsmall controleffort.Thetuningparameterischoseninordertodecreasethenumerical problemsanddecreasethesimulationtimeandhencemakethesystemmoresuitable for implementation. Therefore, the system state space with transformed valuesA,B, C andD are obtained using the system state space model A, B, C and D and tuning parameter , where, /A A = , /B B = , /C C =and /D D = . Then, the control objectives are achieved by solving the new cost functionJand new constraints. In the proposed system under study, the parameters of the FMPC are adjusted tobea=0.38,N=6,=1.04,Np=200andNc=5.Thesystemperformancewiththe proposedFMPCcontrolleriscomparedwiththecorrespondingoneusingthe conventional PI controller. The gains of the PI controller are adjusted as: proportional gainKp=6and integralgainKi=2.5. Thefollowingsimulation testsarecarriedoutto show the validity of the proposed FMPC controller: a- High speed case: Itisassumedthatthemachinefollowsacertainspeedtrajectorystartingfrom400 rad/sec., stepped to 300 rad/sec. at time t=0.03 sec., then returned back to 400 rad/sec att=0.05sec.Theloadtorqueiskeptconstantatthevalue3N.m.duringthe simulation period. Figures (3) to (7) show the dynamic responses of the speed, torque, rotorpositionandstatorcurrentsofthePMSMsystembasedonbothFMPCandPI controllers. Ithasbeenshownthattheproposedsystemhasbettertransientresponse. This is clear in figures (3) and (4) where the system with PI controller oscillates many timesbeforethesteadystatevaluesareattained.Incontrast,thesystemwiththe proposedcontrollerhasattainedthesteadystatevalueveryquickly.Thatiscanbe shown infig.(3)tofig.(9),where overshootandsettlingtimeofsystemarereduced when FMPC controller is used. The settling time of PI controller is 18 ms, where in the case of FMPC the settling time equal 5 ms as shown in fig 3. Also, Fig. (5) illustrates thatthePIcontrollerproduceslargephasedifferenceintherotorpositionresponse which adversely affecting the axes transformation and the flux orientation, and thereby reducing thesystemperformance.Ontheotherhand,theFMPCtrackswelltherotor position reference and the field orientation condition is satisfied.. Figures(6)and(7)showthestatorcurrentresponsebasedonFMPCandPI controllers.ItisobviousthatwiththeFMPCcontroller,thestatorcurrenthasless ripple content and over shoot than using PI controller. b- Low speed case: TheperformanceofthePMSMschemewiththeproposedFMPCcontrolleris investigated at low speed (10 rad/sec). The load torque is assumed to be stepped from 2 N.m. to 5 N.m. at time t=0.035 second. Figures (8) and (9) show the system responses usingtheFMPCandPIcontrollers.Itisclearthatthesystemhaspoortransient responseusingPIcontrollerespeciallyatstartingandattheinstantofloadchange. Also,moreripplesarenoticedinthetorqueresponse.Thesedrawbacksarenearly eliminated using the FMPC controller. Also in the FMPC, the unknown variables are 16 times less than the classical MPC. Ineachtimeinterval,thecalculationtimeneededforclassicalMPCis4.6ms, A. A. Hassan and Ahmed M. Kassem 1130 whereasthistimeisreducedto0.48msintheFMPC.Thisisagreatcomputational advantage of using functional MPC. 00.01 0.02 0.03 0.04 0.05 0.06 0.070100200300400500time (sec)rotor speed (rad/sec)(a) using FMPC controller 00.01 0.02 0.03 0.04 0.05 0.06 0.070100200300400500time (sec)rotor speed (rad/sec)(b) using PI controller refFMPCrefPI Fig. (3): speed response of the PMSM system based on FMPC and PI controllers. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07-40-2002040time (sec)load torque (Nm) PIFMPC Fig. (4): Torque response of the PMSM system based on FMPC and PI controllers. SPEED CONTROL DESIGN OF A PMSM BASED ON 11310 0.01 0.02 0.03 0.04 0.05 0.06 0.07-4-3-2-101234time(sec)rotor position (rad) ref. PIFMPC

Fig. (5): Rotor position response of the PMSM system based on FMPC and PI controllers. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07-40-30-20-10010203040time (sec)the phase currents (A) Fig. (6): stator current response of the PMSM system based on the FMPC controller. A. A. Hassan and Ahmed M. Kassem 1132 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07-30-20-10010203040time (sec)three phase currents (A) Fig. (7): stator current response of the PMSM system based on PI controller. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07-202468101214161820time (sec)rotor speed (rad/sec) ref. speedPIFMPC Fig. (8): Low speed response at variable load based on proposed FMPC and PI controllers. SPEED CONTROL DESIGN OF A PMSM BASED ON 11330 0.01 0.02 0.03 0.04 0.05 0.06 0.07-30-20-10010203040time (sec)load torque (Nm) PIFMPC Fig. (9): Torque response based on FMPC and PI controllers at low speed. 7. CONCLUSIONS In this paper, a centralized functional model predictive controller is proposed to control thespeedandtorqueofthepermanentmagnetsynchronousmotordrivesystem.The proposed predictive controller uses orthonormal Laguerre functions to describe control inputtrajectorywhichreducesrealtimecomputationlargely.Also,exponentialdata weighingisusedtodecreasenumericalissue,particularlywithlargeprediction horizon. Constraints are imposed on both the q-axis current and the motor speed.Computersimulationshavebeencarriedoutinordertoevaluatethe effectivenessoftheproposedcontroller.Theresultsprovedthattheproposedsystem hasaccuratetrackingperformanceatlowspeedsaswellashighspeeds.Also,small ripple contents arenoticed inthe torque andstator currentwaveforms. Moreover,the proposedcontrollerhassignificantlybetterperformancerelativetoPIcontroller especially at starting and load change conditions. The main reasons of this superiority are: centralized structure of the proposed controller which reduces negative interaction betweenlocalcontrolactions,properconstraintsthatimproveoptimalcalculationof control trajectory using large prediction horizon gives a performance close to global. REFERENCES [1]MorimotoS,SandaM,TakedaY."Widespeedoperationofinteriorpermanent magnetsynchronousmotorswithhighperformancecurrentregulator"..IEEE Transactions on industry applications, Vol. 30, pp. 920-926, Aug 1994. [2]Y.A.R.I.Mohamed,Adaptiveself-tuningspeedcontrolforpermanent-magnet synchronousmotordrivewithdeadtime,IEEETransactionsonEnergy Conversion, Vol. 21, No. 4, pp. 855-862, Dec. 2006. [3]C. H. Fang, C. M. Huang, and S. K. Lin, Adaptive sliding-mode torque control of aPMsynchronousmotor,IEEProceedings-ElectricPowerApplications,Vol. 149, No. 3, pp. 228-236, May 2002. A. A. Hassan and Ahmed M. Kassem 1134 [4]AbdulMotinHowladery,NaomitsuUrasaki,TomonobuSenjyu,AtsushiYona, and Ahmed Yousuf Saber, " optimal pam control for a buck boost dc-dc converter with a wide-speed-range of operation for a pmsm", Journal of Power Electronics, Vol. 10, No. 5, pp.477-484, 2010. [5]Y. S. Kung, and M. H. Tsai, FPGA-based speed control IC for PMSM drive with adaptive fuzzy control, IEEE Transactions on Industrial Electronics, Vol. 22, No. 6, pp. 2476-2486, Nov. 2007. [6]Nung-SeoPark,Min-HoJang,Jee-SangLee,Keum-ShikHong,andJang-Mok Kim," Performance Improvement of a PMSM Sensorless Control Algorithm Using aStatorResistanceErrorCompensatorintheLowSpeedRegion",Journalof Power Electronics, Vol. 10, No. 5, pp.485-490, 2010.[7]Ying-ShiehKungandMing-HungTsai,"FPGA-basedspeedcontrolicforpmsm drivewithadaptivefuzzycontrol".IEEEtransactionsonpowerelectronics,Vol. 22, No. 6, November 2007. [8]YANDahu,JIZhicheng,"BacksteppingSpeedControlofPMSMBasedon Equivalent Input Disturbance Estimator". Proceedings of the 29th Chinese Control Conference, China, pp. 3377-3382, July 2010. [9]Rong-MawJan,Chung-ShiTsengandRen-JunLiu,"RobustPIDcontroldesign forpermanentmagnetsynchronousmotor:Ageneticapproach".ElectricPower Systems Research, Vol. 78, No.7, pp. 1161-1168, 2008. [10] Fayez F. M. El-Sousy," A Vector-Controlled PMSM Drive with a Continually On-LineLearningHybridNeural-NetworkModel-FollowingSpeedController", Journal of Power Electronics, Vol. 5, No. 2, pp.129-141, 2005. [11]MuratKarabacak,H.IbrahimEskikurt,"Speedandcurrentregulationofa permanentmagnetsynchronousmotorvianonlinearandadaptivebackstepping control".MathematicalandComputerModelling,Vol.53,No.9-10,pp.2015-2030,2011. [12]L.Zhang,R.Norman,andW.Shepherd,LongRangePredictiveControlof current regulated PWM for induction motor drives using the synchronous reference frame,IEEETransactionsonControlSystem.Technology.,Vol.5,No.1,pp. 119126, 1997. [13]R.Kennel,A.Linder,andM.Linke,Generalizedpredictivecontrol(GPC) readyforuseindriveapplications?inProc.oftheIEEEPowerElectronics Specialists Conference PESC 01, pp. 18391844, 2001. [14] A. Linder and R. Kennel, Model predictive control for electrical drives, in Proc. of the IEEE Power Electronics Specialists Conference PESC 05, pp. 17931799, 2005. [15]WangL,DiscretemodelpredictivecontroldesignusingLaguerrefunctions. Journal of Process Control, pp. 131-142, 2004.[16]WangL,Useofexponentialdataweightinginmodelpredictivecontroldesign. Proc 40th IEEE Conf. on Decision and Control, 2001. [17]AhmedM.Kassem,"RobustVoltagecontrolofaStandAloneWindEnergy ConversionSystemBasedonFunctionalModelPredictiveApproach". InternationalJournalofElectricalPowerandEnergySystems, Vol.41,pp.124-132, 2012. [18]S.zra,N.Bekirolu,andE.Ayiek,"SpeedControlofPermanentMagnet Synchronous Motor Based on Direct Torque Control Method". IEEE International SPEED CONTROL DESIGN OF A PMSM BASED ON 1135SymposiumonPowerElectronics,ElectricalDrives,AutomationandMotion,pp 268-272, June, 2008. [19] Maciejowski J.M, Predictive Control with Constraints, Pearson Education, POD, 2002. [20] "MATLAB Math Library User's Guide", by the Math Works. Inc., 2010.

!" # (model predictive control) ! " # $ % & ' ( ) !* (+, - .!&$ / *0(1!,+1 % (23( 4!3 ! 1 $ ' / (largepredictionhorizon) 5 !# * -#6 7 -6.8*5 % !1 9/ (Functional modelpredictivecontrol) !1!-*( /4!35 %(03 5 5 * / : ; ?/ ?( (+,(".55:53 $ #3 %