Simulation of Sensorless Speed Control of Induction Motor Using APFO Technique

Transcription

1 International Journal of Computer and Electrical Engineering, Vol. 4, No. 4, Augut 2012 Simulation of Senorle Speed Control of Induction Motor Uing APFO Technique T. Raghu, J. Sriniva Rao, and S. Chandra Sekhar Abtract Thi paper decribe a Adaptive Peudoreducedorder Flux Oberver (APFO) for peed control of the Induction Motor drive (IM) without a peed enor. In thi cheme an Adaptive Peudo reduced-order Flux Oberver (APFO) i ued intead of the Adaptive Full-order Flux Oberver (AFFO). In comparion with the AFFO, thi method conume le computational time, and provide a better peed etimation at very low peed. APFO i ued for etimate the IM rotor peed and tator reitance, and thee are ued a feedback ignal for the Field Oriented Control (FOC), which i a widely ued control method for Induction Motor drive (IM). Simulation reult how that the etimated peed can replace to meaured peed in enorle induction motor drive, and alo oberved line current, torque and peed under noload and load condition. Experimental reult are alo hown for rotor etimated and real peed, peed in forward and revere direction. Thi cheme i more efficient at very low peed. Index Term Adaptive full-order flux oberver (AFFO), adaptive peudoreduced-order flux oberver (APFO), induction motor drive (IM), model reference adaptive ytem (MRAS), peed etimation. I. INTRODUCTION Induction motor (IM) can be conidered a the workhore of the indutry becaue of it pecial feature uch a low cot, high reliability, low inertia, implicity and ruggedne. The enorle induction motor drive have reached a great maturity in recent i year. However, the peed etimation baed on machine modeling problematic at low peed operation. The main reaon i the intability problem of the mot exiting peed etimator in the literature at low peed and the obervability problem at zero tator frequency operation. Thi ha directed the reearcher to utilize the aliency effect to etimate the peed [1]. Senorle vector control induction motor drive eentially mean vector control without any peed enor. Senorle induction motor (IM) drive are widely ued in indutry for their reliability and flexibility, particularly in hotile environment [2]. Indirect field-oriented control (IFOC) method i widely ued for IM drive. Within thi cheme, a rotational tranducer uch a a tachogenerator, an encoder, wa often mounted on the IM haft. Variou enorle field oriented control (FOC) Manucript received May 10, 2012; revied June 12, Raghu i with the department of electrical and electronic engineering, Anurag engineering college (Affiliated to JNT Univerity), kodad, nalgonda (Dt.), Andhra pradeh, India ( raghu.thumu@gmail.com). Sriniva Rao and Chandra Sekhar are with the department of electrical and electronic engineering, Anurag engineering college, kodad, nalgonda (Dt.), Andhra pradeh, India ( janigarinivarao@gmail.com, hod.eee@anurag.ac.in). method for induction motor drive have been propoed [3]- [5]. Adaptive full-order flux oberver (AFFO) for etimating the peed of IM were developed uing Popov and Lyapunov tability criteria [6]. While thee cheme are not computationally intenive, an AFFO with a non-zero gain matrix may become untable. An adaptive peudoreducedorder flux oberver (APFO) for enorle FOC wa propoed in uing the Lyapunov method [7]. The performance of the etimator uing APFO wa hown to be uperior compared to that uing AFFO cheme only at medium peed. In the APFO-baed technique for enorle induction motor drive the rotor peed i etimated and i ued a the feedback ignal for the FOC. The rotor flux i etimated through a cloed loop oberver, thu eliminating the need for auxiliary variable related to the flux and need for the pure integration for flux calculation [8]. A a reult, the drive ha a wider adjutable peed range and can be operated at zero and very low peed. II. PARALLEL MODEL REFERENCE ADAPTIVE SYSTEM Thi cheme i relatively eay to implement ytem with high peed of adaptation for a wide range of application. Thi i one of the baic cheme of the model reference adaptive technique called a parallel configuration (output error method). In thi cheme relative placement of the reference model and of the adjutable ytem i not the ame [9]. The cheme preented above are characterized by the fact that the reference model wa dipoed in parallel with the adjutable ytem. Fig. 1. Baic configuration of a parallel model reference adaptive ytem The ue of parallel MRAS i determined by it excellent noie-rejection propertie that allow obtaining unbiaed parameter etimate, and in thi cheme an error vector i derived uing the difference between the output of two dynamic model, i.e. the reference and adjutable model, where only one of the model include the etimated parameter a a ytem parameter, i.e. peed/reitance, and the input of two model are the ame. The error vector, e, i 440

2 International Journal of Computer and Electrical Engineering, Vol. 4, No. 4, Augut 2012 driven to zero through an adaptive law [9]. One of the mot noted advantage of thi type of adaptive ytem i it high peed of adaptation. The main drawback of thi algorithm i it enitivity to inaccuracie in the reference model, and difficultie of deigning the adaptation mechanim block. III. SENSORLESS CONTROL Speed enorle etimation a it name implie, i the determination of peed ignal from an IM drive ytem without uing rotational enor. It make ue the dynamic equation of the IM to etimate the rotor peed component for control purpoe. Etimation i carried out uing the terminal voltage and current which are readily available uing enor. Senor le vector control induction motor drive eentially mean vector control without any peed enor. An incremental haft mounted peed encoder, uually an optical type i required for cloed loop peed or poition control in both vector control and calar controlled drive. A peed ignal i alo required in indirect vector control in the whole peed range and in direct vector control for the low peed range, including the zero peed tart up operation. Controlled induction motor drive without mechanical peed enor at the motor haft have the attraction of low cot and high reliability. Drive operating in hotile environment or in high peed drive peed enor can t be mounted. To replace the enor the information on the rotor peed i extracted from meaured tator voltage and current at the motor terminal. The chematic diagram of control trategy of induction motor with enorle control i hown in Fig 2. Senor le control induction motor drive eentially mean vector control without any peed enor. The inherent coupling of motor i eliminated by controlling the motor by vector control, like in the cae of a a eparately excited motor. The inverter provide witching pule for the control of the motor. The flux and peed etimator are ued to etimate the flux and peed repectively. Thee ignal then compared with reference value and controlled by uing the PI controller. IV. ADAPTIVE FLUX OBSERVER In open loop etimator, epecially at low peed, parameter variation ha ignificant influence on the performance of the drive both at teady tate and tranient tate. However, it i poible to improve the robutne againt parameter mimatch and alo ignal noie by uing cloed loop oberver. The propoed oberver i explained below A. Luenberger Oberver The cheme i baed on the fact that one oberver etimate the rotor flux and the peed are derived by the tator current error and the etimated rotor flux. In term of claification, the cheme that adopt an oberver could be alo treated a MRAS, where the motor i conidered a the reference model and the oberver i conidered a the adjutable model. The IM model in term of tate variable in tationary reference frame i given a follow: Fig. 2. Baic block diagram of enorle control of induction motor. Fig. 3. Luenberger baed peed etimation tructure. d dt i A = r A A A i + B1 vˆ r 0 where A i the motor parameter matrix, B i the input matrix; C i the output matrix, i the tate variable vector, and (tator voltage) i the command The tator current and the rotor flux are etimated by the full order Luenberger tate Oberver decribed by the following equation: (3) The motor peed can be etimated by: i i = [ C] r i = A + Bv r (1) (2) (4) where and are the current error calculated a the difference between the meaured and the etimated current. The block diagram for 441

3 International Journal of Computer and Electrical Engineering, Vol. 4, No. 4, Augut 2012 Luenberger oberver i repreented in Fig 3. The baic Luenberger oberver i applicable to a linear, time-invariant determinitic ytem. V. ADAPTIVE SCHEME FOR SPEED ESTIMATION The peed can be calculated by the Model Referencing Adaptive Sytem. The baic block diagram of MRAS peed etimation ytem i hown in Fig 4. The model reference approach (MRAS) make ue of redundancy of twomachine model of different tructure that etimate the ame tate variable. Both model are referred to in the tationary reference frame. A the name implie it conit of two model namely reference model and adaptive model, where the output of a reference model i compared with the output of an adjutable or adaptive model until the error between the two model vanih to zero. With the correct value of rotor peed, the fluxe determined from the two model hould match. An adaptation algorithm with P-I control can be ued to tune the peed value until the two flux value match. where Ψ ω r = ς k dr (5) In teady tate, ζ=0, balancing the fluxe; in other word, ς = A B = ψˆ ψ ^ = Ψ Ψ dr dr and qr qr. The MRAS in Fig. 3 can be interpreted a a vector Phae Locked Loop (PLL) in which the output flux vector from the reference model i the reference vector and the adjutable model i a vector phae hifter controlled by ω r. VI. RESULTS A. Simulation Reult The imulation of enorle peed control of Induction Motor i done by uing MATLAB /SIMULINK. The reult for different cae are given below. Cae-1: Under No-Load Reference peed = 100 rad/ ^ = Ψ p + qr k i ψˆ qr ψ dr Fig. 4. Baic block diagram of MRAS peed etimation Fig φ Current, peed, and torque for no-load reference peed of 100 rad/ Cae-2: Set Point Change Fig. 5. Actual peed and etimated peed uing MRAS in rad/ In deigning the adaptation algorithm for the MRAS, it i important to take account of the overall tability of the ytem and to enure that the etimated peed will converge to the deired value with atifactory dynamic characteritic. Uing Popov criteria etimated peed i derived a follow: Fig. 7. Rotor peed (actual and etimated) 442

4 International Journal of Computer and Electrical Engineering, Vol. 4, No. 4, Augut 2012 Fig φ Current, rotor peed, and torque Fig. 11. Experimental reult of forward-revere operation Cae 3: Reveral of Speed Speed reveral command i applied at t = 0.5 from -100 rad/ to +100 rad/ VII. CONCLUSION Senorle control of induction motor uing AFPO technique ha been propoed. Senorle control give the benefit of Vector control without uing any haft encoder. The principle of Senorle control of induction motor i given elaborately. The mathematical model of the drive ytem ha been developed and reult have been imulated. Simulation reult of Senorle Control of induction motor uing AFPO technique were carried out by uing Matlab/Simulink. The imulation reult of the propoed cheme have been preented. Fig φ Current, rotor peed, and torque B. Experimental Reult Fig 9 and Fig 10 how the experimental reult with ampling period of 0.5 m. The APFO i implemented on PC interfaced to LAB Window/CVI. An Intel 80C 196KD microcontroller i ued for protection purpoe. Experimental data are acquired through a data acquiition board. The agreement between the etimated and meaured value of rotor peed how that the MRAS etimator work preciely at forward and revere direction. Fig. 10 how experimental reult of the forward-revere operation under no load condition. Fig. 10. Actual peed and etimated peed ACKNOWLEDGMENT We are thankful to Dr.P.Rajewar Reddy, chairman, Anurag Group of Intitution, for hi kindly co-operation in providing u the required infratructure and facilitie. We are thankful to Dr.Akah.N.Patwari, Principal, Anurag Engineering College, Kodad, for hi encouragement and guidance. We are thankful to the faculty member of electrical and electronic Department, Anurag Engineering College, for their continuou upport and guidance. REFERENCES [1] E. Levi and M. Wang, Impact of parameter variation on peed etimation in enorle rotor flux oriented induction machine, IEEE Proc. Of Power Electronic and Variable Speed Drive, no. 456, pp , September [2] H. M. Kojabadi and L. Chang, Model reference adaptive ytem peudoreduced order flux oberver for very low peed and zero peed etimation in enorle induction motor drive, IEEE annual power electronic pecialit conference, Autralia, vol. 1, [3] M. Cirrincione and M. Pucci, An MRAS-baed enorle highperformance induction motor drive with a predictive adaptive model, IEEE Tran. on Indutrial Electronic, vol. 52, no. 5, pp [4] C. Schauder, Adaptive peed identification for vector control of induction motor without rotational tranducer, IEEE Tran. on Indutrial Application, vol. 28, no. 5, pp , October [5] G. F. Profumo, C. Illa, R. Magueranu, and P. Vranka, A unitary approach to peed enorle induction motor field oriented drive baed on variou model reference cheme, IEEE/IAS Annual Meeting, pp , [6] J. Mae and J. A. Melkebeek, peed-enorle direct torque control of induction motor uing an adaptive flux oberver, IEEE Tran.on Ind Appl, vol. 36, no.3, pp , 2000 [7] S. Tamai, Speed enorle vector control of induction motor with model reference adaptive ytem, Int. Indutry Application Society, pp , [8] E. Levi, M. Wang, Impact of parameter variation on peed etimation in enorle rotor flux oriented induction machine, 443

5 International Journal of Computer and Electrical Engineering, Vol. 4, No. 4, Augut 2012 IEEE Proc. Of Power Electronic and Variable Speed Drive, no. 456, pp , [9] Y. D. Landau, Adaptive control The model Reference Approach, Marcel Dekker, New York, T. Raghu wa born in He received hi M.Tech (Power Electronic) degree in Electrical and Electronic Engineering from Jawaharlal Nehru Technological Univerity, Hyderabad. Preently he i working a aitant profeor in Anurag engineering college, Kodad. He i guiding both undergraduate and pot graduate tudent project. Hi area of interet include Power Electronic and Drive. J. Sriniva Rao wa born in He received hi M.Tech (Power Electronic) degree in Electrical and Electronic Engineering from Jawaharlal Nehru Technological Univerity, Hyderabad. Preently he i working a aitant profeor in Anurag engineering college, Kodad. He i guiding both undergraduate and pot graduate tudent project. Hi area of interet include Power Electronic and Drive. S. Chandra Sekhar wa born in He received hi M.Tech (High Voltage Engineering) degree in Electrical and Electronic Engineering from Jawaharlal Nehru Technological Univerity, Kakinada. Preently he i working a aociate profeor in Anurag engineering college, Kodad. He i guiding both undergraduate and pot graduate tudent project. Hi area of interet include High voltage tranmiion, Power Electronic and Drive. 444