Improvement in Dynamic Response of Electrical Machines with PID and Fuzzy Logic Based Controllers

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1 WCECS 2007, October 24-26, 2007, Sn Frncisco, USA Iproveent in Dynic Response of Electricl Mchines with nd Bsed s Gdd Mllesh,Meber, IEEE, K.B. Venkt Rn Abstrct logic or set theory is given uch ephsis in recent yers especilly in power electronics bsed control pplictions. logic hs et with growing interest in ny otor control pplictions due to its non-linerity, hndling fetures nd independence of plnt odeling. This pper describes ppliction of fuzzy logic in speed control syste for Electricl Mchines: DC otors nd AC Induction otors. The design of fuzzy logic controlled for Electricl Mchines re very siilr. The controller designed is bsed on proportionl, Integrl nd derivtive fuzzy resoning. It directly trnsfors the s: speed error nd its rte of chnge to the output quntity nd fuzzy logic speed controller is eployed in the outer loop. The coplete schee of the Electricl chine incorporting the FLC is ipleented using MATLAB (Mth works). The perfornces of the electricl chines re investigted with () controller for different operting conditions. The response including fuzzy logic controller is lso obtined. The coprison of results shows tht the controller with FLC is ore robust nd hence found to be suitble ddition to the conventionl controller for high perfornce industril drive pplictions. Index Ters Electricl Mchines, (FLC), Integrl Absolute Error (IAE), Non liner systes, controllers, Siultion Anlysis. I. INTRODUCTION Clssic Control hs proven for long tie to be good enough to hndle control tsks on Electricl Mchines, however this ipleenttion relies on n exct theticl odel of the plnt to be controlled nd not siple theticl opertions. In the lst decdes, ny control techniques hve been developed providing good perfornce. However, the desired drive specifictions re still not stisfied perfectly nd their lgoriths re too coplex. On the other hnd, (FLC) [1] is bsed on single hun resoning odels, therefore their design re This work ws supported in prt by the Deprtent of Electricl Engineering, University College of Engineering (A), Osni University. Gdd Mllesh is with the Deprtent of Electricl Engineering, University College of Engineering (A), Osni University, Hyderbd, A.P., INDIA, (e-il: lleshiitd@yhoo.co). K. B. Venkt Rn with the University Building Division, Osni University, Hyderbd, nd A.P., INDIA, (e-il: kbvr@yhoo.co). guided by intuition, expert knowledge nd engineering. s cn be clssified ccording to their nd output vribles, when typicl vribles such s "error", "chnge in error" nd "error su" re used lone or cobined, FLC's becoe " Proportionl", " Integrl", nd so on[2]. This pper presents the experientl results of the bsic ides of the s pplied to Electricl Mchines, showing the high level of suitbleness of on speed control of DC otors nd AC otors. The fuzzy logic pproch hs been the object of n incresing interest nd hs found pplictions in ny doins. The in dvntge of fuzzy logic control when copred to conventionl control is the fct tht no theticl odeling is required for the controller design. logic hs been successfully used to control ill-known or coplex systes where precise odeling is difficult or ipossible. In otion control systes, fuzzy logic cn be considered s n lterntive pproch to conventionl feedbck control. It hs been deonstrted tht dynic perfornce of electric drives s well s robustness with regrd to preter vritions cn be iproved by dopting the non-liner speed control techniques. control is non-liner control nd it llows the design of optiized nonliner controllers to iprove the dynic perfornce of conventionl regultors. In the literture, one cn find the ppliction of fuzzy logic in the control of vrious systes: DC otor nd Induction otors, AC Servo, etc. The otor control issues re trditionlly hndled by fixed gin proportionl, integrl nd derivtive () controller. However, the fixed gin controllers re very sensitive to preter vritions, disturbnces, etc. so, the controller preters hve to be dpted. The proble cn be solved by severl control techniques nd design of ll of the bove controllers depends on the exct syste theticl odel. However, it is often difficult to develop n ccurte syste theticl odel due to unknown vrition, unknown nd unvoidble preter vritions due to sturtion, teperture vritions nd syste disturbnces. In order to overcoe the bove probles, recently the fuzzy logic controller (FLC) is being used for otor control purpose, the theticl tool for this is the fuzzy set theory introduced by Prof. Zdeh [3]. As copred to the conventionl controllers

2 WCECS 2007, October 24-26, 2007, Sn Frncisco, USA nd their dptive versions the FLC hs soe dvntges such s: (1) it does not need ny exct syste theticl odel; (2) it cn hndle non-linerity of rbitrry coplexity nd (3) it is bsed on the linguistic rules with IF-THEN generl structure which is the bsis of hun logic. In this pper, the ppliction of fuzzy logic to control electricl chines is investigted. logic control principle is considered for the design of the speed controller. The control perfornce of this fuzzy logic controller is evluted by siultion for different operting conditions nd by copring with the results of the conventionl controller using the Integrl of Tie by Absolute Error criterion. L di dt V I. R K.. (2) The dynic odel of the syste is fored using these differentil equtions nd the Mtlb Siulink block with controller s shown in figure (1). b II. PRINCIPLE AND CONTROL OF PROPOSED DC MOTOR A. Introduction The speed of DC otors cn be djusted within wide boundries so tht this provides esy controllbility nd high perfornce[4]. DC otors used in ny pplictions such s still rolling ills, electric trins, electric vehicles, electric crnes nd robotic nipultors require speed controllers to perfor their tsks. Speed controller of DC otors is crried out by 'ens of voltge control, in 1981 fustly by Wrd Leonrd [5]. The regulted voltge sources used for DC otor speed control hve gined ore iportnce fter the introduction of thyristor s switching devices in power electronics. Then seiconductor coponents such s MOSFET, IGBT nd GTO hve been used s electric switching devices [6, 7]. In this study, the speed response of DC otor exposed to fixed rture voltge ws investigted for both under ed nd uned operting conditions. The DC otor ws operted for required reference speed under ed nd uned operting conditions using nd logic control ethods. B. Motor Model The resistnce of the field winding nd its inductnce of the otor used in this study re represented by R f nd L f, respectively. The resistnce of the rture nd its inductnce re shown by R nd L respectively in dynic odel. Arture rection effects re ignored in the description of the otor. This negligence is justifible to iniize the effects of rture rection since the otor used hs either interpoles or copensting winding. The fixed voltge V, is pplied to the field nd the field current settles down to constnt vlue. A liner odel of siple DC otor consists of echnicl eqution nd electricl eqution s deterined in the following equtions: J dw dt K.. I b. M (1) Fig. 1 MATLAB/Siulink odel of DC otor with controller The preters of DC otor used in this study re shown in Tble 1. TABLE I Preters of the DC Motor odel used Preters Description Vlue R Arture Resistnce (Ohs) 0.5 L Arture Inductnce (H) J Motor Inerti (Kg. 2 /s 2 ) K = K e = (Kb. Φ) Motor Constnt = K t = (K. (N/Ap) 0.8 Φ) Dping Rtio of B Mechnicl syste (Ns) The speed control of the DC otor using conventionl controller nd logic is ipleented nd the siultion results discussed in the next sections. III. PRINCIPLE AND CONTROL OF PROPOSED INDUCTION MOTOR The Synchronous chines re double fed chines, tht is one hs to provide the excittion s well s the rture. The induction chines receive their excittion by induction; hence we need only one source of power. They re clled singly-fed chines. There re no couttors, slip rings or brushes. Hence this is ost rugged nd intennce free

3 WCECS 2007, October 24-26, 2007, Sn Frncisco, USA chine. Becuse there is no loss in brush contcts or echnicl friction, it is of high efficiency A. Principle of Opertion The sttor is siilr to the sttor of synchronous chine. It is fed with 3-phse lternting current nd provides rotting flux. This flux rottes t synchronous speed 120 f N s (in rp) where (f) if the source frequency nd p (p) the nuber of poles on the chine. Or: 4 f s rd / s (3) p The rotor hs either 3 phse short-circuited winding, or ny conducting eleents. In study we will consider 3-phse winding on the rotor (wound rotor chine). The revolving field induces flux in the rotor windings. Since the windings re short circuited, current is flowing nd tht current produces flux of its own. According to Lenz s lw, this flux will oppose the flux which creted it, nd hence torque is developed on the shft. If this torque is higher thn the torque, the rotor will strt to rotte. Under no, the rotor current will hve very low frequency [8]. This lso clled n Asynchronous Mchine. At operting speed, the rotor currents will hve the frequency of the reltive otion between rotor nd sttor rotting speed. Hence the rotor frequency is N The reltive speed is clled the slip s N r N S N shft (4) N r S shft S shft (5) NS N S When the rotor is sttionry (strt), the slip is 1 nd we hve the equivlent of short-circuited trnsforer (Priry is the sttor, secondry is the rotor). The dynic odel of the Induction otor using controller is developed nd is shown in figure (2). Fig.2 MATLAB/Siulink odel of Induction otor The preters of the Induction otor used in this study re shown in Tble II TABLE II Preters of the Induction otor used in this study Rotor type : Squirre-cge Reference fre : Sttionry Noinl power : 2200VA Voltge(line-line): 208Vrs Frequency : 50Hz Sttor resistnce : 0.59oh Sttor Inductnce : H Rotor resistnce : 0.37oh Rotor Inductnce : H Mutul inductnce : H Inerti : Friction fctor nd pirs of poles : The siultion results of Induction otor using controller is discussed in the next sections IV. FUZZY LOGIC CONTROLLER (FLC) DESCRIPTION AND DESIGN The concept of fuzzy logic (FL) ws conceived by Prof. Lofti Zdeh, professor t the University of Cliforni t Berkley [9] nd presented not s control ethodology, but s wy of processing dt by llowing prtil set ebership rther thn crisp set ebership or non-ebership. This pproch to set theory ws not pplied to control systes until the lte 70 s due to insufficient sll-coputer cpbility prior to tht tie. Professor Zdeh resoned tht people do not require precise, nuericl infortion, nd yet they re cpble of highly dptive control. If feedbck controllers could be progred to ccept noisy, iprecise, they would be uch ore effective nd perhps esier to ipleent. FL is proble-solving control syste ethodology tht lends itself to ipleenttion in the syste rnging fro siple, sll, ebedded icro-controllers to lrge, networked, ulti-chnnel PC or worksttion-bsed dt cquisition nd control systes. It cn be ipleented in hrdwre, softwre, or cobintion of both. FL provides siple wy to rrive t definite conclusion bsed upon vgue, biguous, iprecise, noisy, or issing infortion. FL s pproch to control probles iics how person would ke decisions, only uch fster. [10, 11] A. FLC Designs Design of DC otor nd AC otor fuzzy logic controllers re very siilr nd re bsed on proportionl, Integrl nd derivtive fuzzy resoning [12, 13]. In both otors, proportionl, Integrl nd derivtive controller uses s (feed bck) vribles re speed error nd chnge on speed error nd s output vrible the increent to the lst control ction or pproprite control ction is generted. This

4 WCECS 2007, October 24-26, 2007, Sn Frncisco, USA is increent to the control ction is regulted not only by the error s gnitude but lso by the speed nd the direction tht the error signl flows. The ebership functions [14] of these fuzzy vribles used by the DC otor nd Induction otor fuzzy controllers re shown in figures Fig.3 nd the MATLAB Siulink digrs for DC otor nd Induction otor using re shown in Fig. 4 nd Fig. 5 respectively. Siilrly logic controller for induction otor hs the se structure (se fuzzy -output vribles) nd control strtegy, but it uses different ebership functions nd stightly different set of rules[15, 16].The in difference between DC otors nd induction otor syste is found t different kind of ctutions. Fig.5 MATLAB/Siulink odel of the Induction Motor using logic The speed control of DC otors using nd FLC which is designed in MATLAB/Siulink nd hs been studied with different cses nd corresponding results re plotted. The reference speed is defined s 200rd/sec. The siultion results re shown in figure (6), figure (7) for different cses with nd without of 60N- t 1.5sec nd corresponding perfornce specifictions re shown in Tble III. Fig.3 The ebership functions of fuzzy vribles used for the DC otor V. COMPARISON BETWEEN AND FUZZY LOGIC SPEED CONTROLLERS In the previous sections, the speed control of Electricl chines is considered using conventionl controller nd controller. The different cses re considered with nd without on the chines. Fig. 6 The dynic response of the DC Motor with nd strting under Lod with step s reference speed. Fig. 4 MATLAB/Siulink odel of the DC Motor using logic.

5 WCECS 2007, October 24-26, 2007, Sn Frncisco, USA THE DYANAMICRESPONSE OF THE DCMOTORSTARTING UNDERNO-LOADFORUNIT STEP INTHE REFERENCE SPEED different reference with of 20N- t 1sec nd without nd re show in following figure (8), figure (9) nd perfornce specifictions re given in tble (IV). w (rd/sec) DCMOTORREFERENCE SPEED DCMOTORSPEEDWITH DCMOTORSPEEDWITHFUZZY TIME (Sec) Fig. 7 The dynic response of the DC Motor with nd strting under Lod with stircse s reference speed TABLE III The Coprison tble of DC Motor Specifictions using nd logic s Different types of Dely Without Dely Input with Without with Stir cse Without Stir cse with % Mxiu pek Over shoot (%Mp) Setting Tie ts Stedy Stte error( ess) IAE % (1st pek) 45% (2nd pek) 12 (1st pek) 18 (2nd pek) 46% (1st pek) 45% (2nd pek) 14% (undershoot due to ) 12 (1st pek) 18 (2nd pek) 3 (undershoot due to ) The dynic odel of the Induction otor using fuzzy logic is developed in the MATLAB Siulink using the Induction otor equtions. The siultions crried out for Fig. 8 The dynic response of the Induction Motor with nd strting under Lod with step s reference speed Fig. 9 The dynic response of the Induction Motor with nd strting under Lod with Trpezoidl s reference speed TABLE IV The coprison tble of Induction otor specifiction using nd fuzzy logic Different types of without With Trpezoidl without Trpezoidl with % Mx iu pek over shoot (%Mp) Setting Tie (sec) ts Stedy Stte error ( ess) IAE

6 WCECS 2007, October 24-26, 2007, Sn Frncisco, USA The siultion results show tht the error driven by fuzzy logic controller hs shown the best overll perfornce, s copred to conventionl controller. This y be due to fct tht fuzzy controller serch for optioned control s copred to conventionl controllers The results clerly ention the difference between two ethods. The speed control bsed on logic hs better perfornce thn tht of conventionl controller. logic speed control is soeties seen s the ultite solution for high perfornce drives of the next genertion. Finlly for given Kp, Ti, Td, the tie doin specifictions i.e. Mxiu Pek over shoot(m P ), settling tie(t s ), stedy stte error (e ss )nd perfornce esures IAE re better s copred to the controller. VI. CONCLUSION In this pper, controller with fuzzy logic controller bsed speed control of Electricl chines hs been presented. logic controller nd controllers hve been designed for speed control loop. The siultions hve been crried out using MATLAB/Siulink toolbox. In order to iniize the rel-tie coputtionl burden siple ebership functions nd rules hve been used. Since exct syste preters re not required in the ipleenttion of the proposed controller, the perfornces of the drives syste re robust, stble nd sensitive to preters nd operting condition vritions. In order to prove the superiority of the FLC, conventionl controller bsed Electricl chines DC Motor nd Induction Motors hs lso been siulted nd the perfornce hs been investigted t different dynic operting conditions. It is concluded tht the proposed fuzzy logic controller hs shown superior perfornces like M P, ts, ess nd IAE over the conventionl controllers nd shows robustness vrition of the torque. Finlly, soe conclusions nd Future scope of this work re controllers cnnot copenste theselves for very lrge vritions of echnicl preters. logic controllers re suitble option to ke speed regultion DC otor nd AC otors. The single hun bsed resoning used on FLC cn be very useful to overcoe non-linerities of ny kind of plnts in logicl wy. It would be necessry to use ore coplex intelligent control systes i.e. dptive fuzzy syste, Neuro- systes nd genetic lgoriths, in order to obtin better perfornce on speed control. REFERENCES [1] C. Els, s, Seckin Publishing, April [2] Applictions of Sets Methodologies in Industril Engirneering. Evns, Gerld W; Wlder, K.; Wilhel, M.R..Asterd; New York: Elsevier; 1989 [3] L. A. Zdeh, Sets Inforl Control, vol.8,pp , 1965 [4] Design of control syste for DC drivers. Buxbu, A.Shieru; Strughen, A. Berlin; New York: Springer-Verlg [5] Chn, C. C., Low Cost Electronic Controlled Vrible Speed Reluctnce Motors, IEEE Trnsctions on Industril Electronics, Vol. IE-34, No Februry [6] Khoei, A.. Hdidi, Kh., Microprocessor Bsed Closed-Loop Speed Control Syste For DC Motor Using Power Mosfet. Electronics Circuits nd Systes IEEE Interntionl Conference ICECS 96, Vol. 2, , [7] F. Rhn, Lectures 18 Control of DC-DC Conveners, Power Electronics. ELEC4240/9240 [8] B.K. Bose, P Electronics nd AC Drives, Prentice-Hll, Englewood Cliffs, New Jersey, 1986 [9] L. A. Zdeh,. Outline of new pproch to the nlysis coplex systes nd decision processes IEEE Trns. Syst.Mn Cybe, vol. SMC-3, pp , 1973 [10] O. Kynk. G.Argn, Otosyon Mgzine. A new pproch for process control:, July-August [11] "Developent Syste for Fuzy Control Systes" (In Spnish), Crlos A. Hernbndez; J. Mnuel Rirez. MEXICON '9 1, Puebl, Mexic. [12] A fuzzy set Bsed Control of Phse Controlled Converter DC Mchine Drive. Gilberto C. D., Bil K. Bose. IEEE Trnsctions on Industry Applictions, Vol.30 No. 1 Jnury/Februry [13]. s for DC otor. B. S Thesis. Fonsec, Joquin; Herndez, Sergio. Universidd de ls Aerics-Puebl. Mexico [14] logic Technology nd Applictions. Robert MrksII. Technology Updte Series. IEEE [15] J.Klir. George, Yun, Bo. : Furry Sets nd -Theory nd Applictions [16] Minh T-Co, J.1.Silv Neto, nd hong Le-Huy, Bsed for Induction Motor Drives, CCECE 96, pp , BIBLIOGRAPHIES Gdd Mllesh ws born in Bolleplly (Vil), Bhongir (Mon), Nlgond (Dist.) on 20th August, He received the B.E degree in Electricl nd Electronics Engineering fro University College of Engineering (A), Osni University, Hyderbd, Indi in He received his Msters degree in Control Engineering nd Instruenttion fro Indin Institute of Technology, Delhi, Indi in 2002.Since 2002; he hs been n Assistnt Professor in the Deprtent of Electricl Engineering, University College of Engineering (A), Osni University, Hyderbd, Indi. His in interest includes Artificil Intelligence Techniques pplied to Electricl Engineering. He ws Secretry of IEEE joint chpter of PES/IAS Societies, Hyderbd Section. He hs visited Greece nd Cnd to present technicl ppers. K. B. Venkt Rn ws born in Jngon, in Indi, in1967. He received the B.E degree in Electricl nd Electronics Engineering fro the Osni University, Hyderbd, Indi. He received his Msters degree in Industril Drives nd Controls speciliztion fro Osni University, Hyderbd, Indi. His eployent experience included working s Assistnt Engineer t Buildings Division, Osni University, Hyderbd. His interests include Motor Drives Control.