A High Performance Rotor-Flux Oriented Indirect Vector Controlled Induction Motor Drive using Fuzzy Logic Control

Transcription

1 A High Pefomance Roto-Flux Oiented Indiect Vecto Contolled Induction Moto Dive using Fuzzy ogic Contol Anjali.S 1, Radhika.R 2 M.Tech Student, Rajiv Gandhi Institute of Technology, Kottayam, India 1 Asst. Pofesso, Rajiv Gandhi Institute of Technology, Kottayam, India 2 Abstact: In most of the industies, scala contolled induction motos ae widely used fo the vaiable speed applications. Nowadays, fo high pefomance applications, field oiented contol (FOC) technique is pefeed. But, detuning caused by distubances in paametes and exteio load distubances still limits the pefomance of these ives. In ode to accomplish vaiable speed opeation, conventional PID contolle is commonly used which povides limited good pefomance ove a wide ange of opeation. In this pape a vecto contolled induction moto employing a Fuzzy ogic Contolle (FC) in the oute speed contol loop is analysed. The scheme is simulated in MATAB/SIMUINK and the pefomance of FC based scheme is compaed with those of PI contolle based scheme. Keywods: Indiect vecto contol, PI contolle, fuzzy logic contolle, field weakening opeation. I. INTRODUCTION In industies fo the vaiable speed application, nowadays, 3-phase induction motos ae pefeed due to its low cost, ugged and simple constuction. Absence of commutato in Induction moto esults to less maintenance and long life. Also it has good opeating chaacteistics like sufficiently high efficiency, easonably good powe facto and good speed egulation. When loaded fom no-load to full load, thee is only a few pecent op in speed as in the case of a constant speed moto with a shunt chaacteistics. The physical size of induction moto is elatively small as compaed with othe types of motos, fo a given output ating. Also IM ae available in the ange of factional hosepowe to multi mega-watt capacity. [1].In the past, the induction moto have been mainly used in constant speed applications as thei speed contol methods have eithe been costlie o pooly efficient. But nowadays availability of thyistos, IGBT and GTO has allowed the use of ac motos in vaiable speed ive application [2]. But in geneal as compaed to the contol and estimation of dc ives, those of ac ives ae consideably moe complex. This complexity inceases substantially if high pefomances ae needed due to the need of vaiable fequency, complex dynamics of ac machines and machine paamete vaiations. Diffeent contol techniques of induction moto ives ae scala contol, vecto o field-oiented contol, diect toque and flux contol and adaptive contol [3]. In scala contol only the magnitude of the contol vaiables ae vaied. Some of the scala contol techniques ae stato voltage contol, supply fequency contol and oto esistance contol. Scala contol is compaatively simple to implement but the inheent coupling effect of induction moto esults a sluggish esponse with poo dynamic pefomance and long settling time. This poblem can be solved if an induction moto can be contolled like a sepaately excited dc moto which happens in vecto contol. In industy the scala contol has been widely used, but ecently thei impotance has diminished due to the supeio pefomance of vecto contolled ives, which is demanded in many applications [3]. Fo high pefomance application, whee a specified efeence tajectoy should be followed by the moto speed egadless of load distubance, model uncetainties and paamete vaiations, vecto contolled induction motos ae suitable. Vecto contol scheme can be classified into the diect o feedback method, invented by Blaschke and the indiect o feed fowad method, invented by Hasse based on unit vecto geneation. In vecto contol,one of the cuent Copyight to IJAREEIE 413

2 contol input i ds is oiented with oto flux. i ds can also be oiented with ai gap flux m o stato flux s.but the oto flux oientation gives natual decoupling contol. Vecto contol leads to independent contol of toque and flux. But they ae sensitive to paamete vaiations, which in tun deteioates the pefomance of conventional contolles like PID o PI.Well established theoetical backgound on stability is available fo conventional contolle and it also allows diffeent design objective such as steady state and tansient chaacteistics of closed loop system, but knowledge of coect mathematical model is equied which is not necessay in case of contolle using atificial intelligence like fuzzy contol. This pape intoduces both contol methods (conventional and atificial intelligence) and applies to a oto flux oiented indiect vecto contolled induction moto ive and the design is tested by MATAB/SIMUINK.Indiect Vecto contol is discussed in the second section whee as thid section deals with contol pinciple. Fouth section explains design of fuzzy logic contolle. Fifth section is dedicated fo the simulation and esult analysis. The last section in this pape is conclusion. II. INDIRECT VECTOR CONTRO It is possible to extend the DC machine like pefomance to an induction moto if the machine contol is consideed in a synchonously otating efeence fame, whee sinusoidal vaiables appeas as steady state dc quantities. Field oiented contolled machine equies two constant as input efeence: the toque component (aligned with q-axis coodinate) and the flux component (aligned with d-axis coodinate).with vecto contol, i ds is analogous to I f, field cuent and i qs analogous to I a, amatue cuent of dc machine. The oto cicuit equation can be witten as d Ri ( e ) 0 (2) d R i ( ) 0 The oto flux linkage expession can be given as i i e m ds i i m qs Fom (4) and (5), the equation fo i and i can be obtained and is substituted on (2) and (3) which gives d R m R i ds sl 0 (3) (4) (5) (6) d R Ψ m R i qs Ψ sl 0 (7) whee ω sl = ω e - ω. Fo decoupling contol =0 (8) d 0 (9) Substituting above conditions in (6) and (7) d ˆ R Copyight to IJAREEIE Ψ ˆ i m ds

3 (10) mr sl ˆ i qs (11) If oto flux is constant, ˆ m ds The electomagnetic toque is given by T e i 3 P ( ) 2 2 m ( ˆ i qs ) Fig. 2 shows the block diagam of an indiect vecto contolled induction moto ive.in this unit vectos ae geneated fom the slip speed, ω sl and oto speed,ω. (12) (13) Fig. 1 Geneal block diagam of an Indiect vecto Contolled Induction Moto Dive. III. CONTRO PRINCIPE In this pape, fo speed contol of an indiect vecto contolled induction moto both conventional (PI) and atificial intelligent (FC) contol methods ae used. A. PI contolle Fist appoach uses a conventional PI contolle. The conventional PI contolle has been fequently used fo contol action. By means of poles placement, it is quite easy to tune the contolle. The stuctue of PI contolle is shown in Fig. 2. Copyight to IJAREEIE 415

4 Fig. 2 Conventional PI contolle stuctue. B. Fuzzy ogic Contolle (FC) Second appoach uses a fuzzy logic contolle. Fig. 3 shows the fuzzy logic stuctue in which K1, K2 and K3 ae known as scaling factos which is vey impotant in fuzzy logic contolle. Selection of scaling factos is made based on the knowledge about the pocess to be contolled. Sometimes it is set though tial and eo to achieve the best possible contol pefomance. Fig. 3 Fuzzy contolle stuctue. IV. DESIGN OF FUZZY OGIC CONTROER Fuzzy logic contolle utilizes the ules obtained fom human expetise o input-output mapping of contolled plant. The inputs to the FC ae the linguistic vaiables of speed eo (e) and change in speed eo (ce) and the output is toque component of stato cuent. Fig. 4 shows the intenal stuctue of a FC. It consists of fou blocks: fuzzication, knowledge base, infeence engine and defuzzification. Fig. 4 Fuzzy contolle intenal stuctue. The cisp vaiables of contol inputs ae conveted into fuzzy vaiables by the fuzzification module. A fuzzy vaiable has values, which ae defined by gadually vaying membeship function. Membeship function can have diffeent shape and tiangula, tapezoidal and gaussian shaped membeship function is most commonly used. The poposed contolle uses following linguistic labels N, MN, SN, Z, SP, MP, and P. Each of the inputs and outputs contain membeship function with all these 7 linguistic. A fuzzy contol essentially embeds the expeience and intuition of a human opeato. The data base and the ule fom the knowledge base with which the infeence elation is obtained. Knowledge base involves defining the ules epesented as IF-THEN ules statement which govens the elationship between input and output vaiables in tems of membeship function. The IF -side of the ule is called the antecedent (conditionψ and the THEN -side is called the consequent (conclusion).in this stage, the infeence engine pocesses the input vaiables and executes 49 ules epesented in ule table below. The fist ule can be stated as if e is N and ce is N then the contol output is N. Hee Mamdani s algoithm is used. Copyight to IJAREEIE 416

5 The mathematical pocedue of conveting fuzzy values back to cisp values is known as defuzzification. Some of the defuzzification methods ae centoid method o cente of gavity method, cente of sums and mean of maxima. Hee centoid method is used. (a) (b) Fig. 5 Membeship function fo (a) eo,e, (b) change in eo,ce, (c) output. (c) e ce TABE I FUZZY OGIC CONTRO RUE N MN SN Z SP MP P N N N N N MN SN Z MN N MN MN MN SN Z SP SN N MN SN SN Z SP MP Z N MN SN Z SP MP P SP MN SN Z SP SP MP P MP SN Z SP MP P MP P P Z SP MP P P P P Copyight to IJAREEIE 417

6 Fig. 6 Gaphical epesentation of ules using suface viewe. V. SIMUATION AND RESUT ANAYSIS The conventional PI and fuzzy logic contolle based IFOC technique wee developed fo a 1.1kW IMD. The paamete of the machine is given in TABE II. Fig. 7 and Fig. 8 shows the speed esponse of a PI and fuzzy logic contolle espectively at no load with a speed efeence of 1430 pm.pi contolle esults a esponse with maximum oveshoot of 1.04% whee as the fuzzy contolle esults zeo oveshoot. The settling time fo fuzzy contolle is less as compaed to that of PI contolle. The settling time of a PI contolle based scheme is 0.4 s and that of FC is 0.08 s.now a load is applied at 3 s. and esponse ae obseved. When loaded at 3 sec FC ecoves the speed faste than PI contolle. Fom Fig.11 (a) and (b),it is clea that in case of fuzzy contolle the eo settles faste than that of PI contolle. The opeation is also extended to field weakening egion and Fig.12 (a) and (b) shows the speed esponse and flux of the system explaining the field weakening opeation. Up to base speed, the flux is constant and when the speed cosses the base speed,flux deceases. TABE III FUZZY OGIC CONTRO RUE Paametes Values Stato esistance,rs 8 Roto esistance, R 4 Stato self inductance, s 0.47 H Roto self inductance, 0.47 H Mutual inductance, m 0.44 H No of poles, P 4 Moment of Inetia, J kgm 2 Copyight to IJAREEIE 418

7 Fig. 7 Speed esponse of a PI contolle at no load with a speed efeence of 1430 pm. Fig. 8 Speed esponse of a FC at no load with a speed efeence of 1430 pm. Fig. 9 Speed esponse of a PI contolle when a load is applied at 3s. Fig. 10 Speed esponse of a FC when a load is applied at 3s. Copyight to IJAREEIE 419

8 (a) (b) Fig. 11 (a) and (b) Eo esponse of a PI and Fuzzy contolle. (a) (b) Fig.12 (a) and (b). Speed esponse and flux explaining field weakening opeation). TABE IV COMPARISON OF PI AND FC CONTROER % OVERSHOOT SETTING TIME PI 1.04 % 0.4 sec FUZZY (FC) sec VI. CONCUSION The concept of Fuzzy logic has been descibed in this pape and the oto-flux oiented Indiect Vecto Contolled Induction Moto Dive using PI and Fuzzy ogic Contolle as speed contolle is simulated and thei pefomances wee compaed. The simulation esults obtained have confimed that the intelligent contolle-fc ealizes a good dynamic behaviou of the moto with a faste settling time and zeo oveshoot than conventional PI contolle. Also the opeation was extended to above base speed and esults wee satisfactoy. REFERENCES [1] J.B.Gupta.Theoy and Pefomance of Electical Machines, 14th edition, S.K.Kataia and sons. [2] Gopal K.Dubey. Fundamentals of Electical Dives, 2nd edition, Naosa Publishing House. [3] Bimal.K.Bose 2002.Moden Powe Electonics and AC Dives, Pentice-Hall. [4] Khalaf Salloum Gaeid, Hew Wooi Ping, Haide A.F.Mohamed Indiect Vecto Contol of a Vaiable Fequency Induction Moto Dive (VCIMDΨ, Poc.ICICI-BME [5] M. N. Uddin, T. S. Radwan and M. A. Rahman Pefomances of Fuzzy-ogic-Based Indiect Vecto Contol fo Induction Moto Dive, IEEE Tans. on Industy Applications, Vol. 38, No. 5, pp , Septembe/Octobe, [6] Vinod Kuma, R. R. Joshi, Hybid Contolle based Intelligent Speed Contol of Induction Moto, Jounal of Theoetical and Applied. [7] Rohit Gupta, Ruchika, Intelligent Induction Moto Dive, Intenational Jounal of Compute Applications, Volume 50 No.22, July [8] Pete Vas, Atificial Intelligence-Based Electical Machines and Dives. Gi-Won Chang, Geado Espinosa-Péez, Eduado Mendes, and Romeo Otega, Tuning ule fo the PI gains of field-oiented contol of Induction motos, IEEE Tans..Industial Electonics. vol. 47, No.3,June Copyight to IJAREEIE 420