II. DYNAMIC MACHINE MODEL OF AN INDUCTION MOTOR

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1 Direct Torque Control Senorle nduction Motor Drive Uing Space Vector Modulation Manoj Bhaurao Deokate, D. N. Katole 2, R.V.Humane Reearch Scholar, Aitant Profeor, Department of Electrical Engineering, Priyadarhini J.L.College of Engineering, Nagpur/ Rahtraant Tukadoji Maharaj Nagpur Univerity (ndia) ABSTRACT : The baic cheme preent a contribution for detailed comparative analyi between Field- Oriented Control and Direct Torque Control technique for high performance induction motor drive. The toque and flux are controlled imultaneouly by applying uitable voltage vector, and by limiting thee quantitie within their hyterei band, de-coupled control of torque and flux can be achieved. Thi paper preent the evaluation technique of pace vector modulation applied to the induction machine. The imulation were carried out uing MATLAB/SMULNK imulation package. Evaluation i made baed on the drive performance, which include dynamic torque and flux repone, feaibility and the complexity of the ytem. However, the bai of DTC SVM trategy i the calculation of the required voltage pace vector to compenate the flux and torque error exactly by uing a predictive technique and then it generation uing the Space Vector Modulation. We can note a light advance of DTC cheme compared to FOC cheme regarding the dynamic flux control performance and the implementation complexity. The choice of one or the other cheme will depend mainly on pecific requirement of the application. General Term : Sector implementation, ripple in torque, ripple in current, inverter tate. Keyword: nduction motor, Field oriented control (FOC), Direct torque control (DTC), Senorle, Space Vector Pule Width modulation (SVPWM).. NTRODUCTON n recent year, everal tudie have been developed which propoe alternative olution to the FOC control motor drive with two objective: firt, achievement of an accurate and fat repone of the flux and the torque, and econd, reduction in the complexity of the control ytem. Since the introduction of field-oriented control in the beginning of 970, the foregoing problem can be olved by vector or field-oriented control and in the mid- 980 an advanced control technique, known a direct torque and flux control (DTFC or DTC) wa introduced for voltage-fed PWM inverter drive. Depite it implicity, DTC i able to produce very fat torque and flux control in teady-tate and tranient operating condition [], if the torque and the flux are correctly etimated. Among the variou propoal, Direct Torque Control ha found wide Acceptance. [] [0].. DYNAMC MACHNE MODEL OF AN NDUCTON MOTOR Among all type of ac machine, the induction machine, particularly the cage type, i mot commonly ued in indutry. The induction motor tator equation are hown a: () Vq Vd r r i i q d d q d dt d d q dt (2) The torque equation hown below i the cro product of rotor flux and tator current and other equation a the cro product of tator flux and tator current. nternational Conference on Advance in Engineering & Technology 204 (CAET-204) 66 Page

2 ----- () (4) The tranformation relation of current are d b c q 2 a b c (5) (6). PRNCPLE OF FELD ORENTED CONTROL The principle of vector control of electrical drive i baed on the control of both the magnitude and the phae of each phae current and voltage. Thi control i baed on projection which tranform a three phae time and peed dependent ytem into a two co-ordinate time invariant ytem. Field orientated controlled machine need two contant a input reference: the torque component and the flux component. Thi make the control accurate in teady tate and tranient working operation and independent of the limited bandwidth mathematical model. The FOC thu olve the claic cheme problem. We can then control the torque by controlling the torque component of tator current vector. [2] [0] The eae of applying direct torque control becaue in the (d, q) reference frame the expreion of the torque i: (7) Figure : Baic cheme of field oriented control nternational Conference on Advance in Engineering & Technology 204 (CAET-204) 67 Page

3 V. PRNCPLE OF DRECT TORQUE CONTROL The name direct torque control i derived by the fact that, on the bai of the error between the reference and etimated value of torque and flux, it i poible to directly control the inverter tate in order to reduce the torque and flux error within the prefixed band (Hyterei band) limit.[8][][2] The tator flux linkage of an M can be expreed in the tationary reference frame with the help of the following two equation (8) (9) The torque produced i dependent on the equation the tator flux a well a rotor flux according to (0) Figure 2: Baic cheme of direct torque control V. DEVELOPMENT OF DTC AND TS SWTCHNG OPERATON The operation of direct torque control of induction motor depend on the voltage vector election. Here we are uing a two level inverter for direct torque control operation. The vector pace i divided into ix ector equally paced (a hown in the figure) uch that the ix voltage vector that the inverter can produce reide at the centre of each ector. Figure : nverter voltage vector and tator flux witching ector Table. Switching table of inverter voltage vector Table 2. Parameter of induction motor nternational Conference on Advance in Engineering & Technology 204 (CAET-204) 68 Page

4 dλ dte SECTOR V2 V V4 V5 V6 V 0 V0 V7 V0 V7 V0 V7 Nominal Power[Pn] Voltage (line-line) Frequency[fn(Hz)] 228 Watt 220 Volt(Vrm) - V6 V V2 V V4 V5 Rotor Reitance[Rr (Ohm)] 0.86Ω V V4 V5 V6 V V6 Above table Rotor nductance[llr (H)] 2.0e- H how the - 0 V7 V0 V7 V0 V7 V0 Mutual nductance[lm(h)] 69.e- two level - V5 V6 V V2 V V4 nertia[j(kg.m^2)] 0.089Kg.m^2 flux comparator and three-level hyterei comparator are ued Pole Pair 2 for the torque error evaluation. V. SMULATON RESULTS 60 Hz Stator Reitance[R(Ohm)] 0.45Ω Stator nductance[ll(h)] 2*2.0e-H Figure 4: Plot of V,, peed & torque w. r.t. time of FOC Figure 5: Plot of V,, peed & torque w. r.t. time of DTC Figure 6: Plot of tator flux of d-q axi w. r. t. time of DTC & FOC. Figure 7: Plot of V and Speed w. r.t. time of DTC nternational Conference on Advance in Engineering & Technology 204 (CAET-204) 69 Page

5 Figure 8: Plot of FOC & DTC of voltage comparion Figure 9: Plot of FOC & DTC at of current comparion w. r. t. time (GREEN DTC, BLUE FOC) w. r. t. time (GREEN DTC, BLUE FOC) Figure 0: Plot of FOC & DTC of torque comparion Figure : Plot of FOC & DTC of peed comparion w. r. t. time (GREEN DTC, BLUE FOC) w. r. t. time (GREEN DTC, BLUE FOC) Above figure, how the performance of current, peed & torque comparion of two technique. 6. Current Comparion The DTC preent a more ocillating current at tarting, contrary to the FOC. Current pattern i alo better for DTC. 6.2 Speed Comparion Dynamic Speed Repone i fat in Cae of DTC a compared to FOC. The DTC preent a high dynamic at tarting intant and rapid load torque diturbance rejection without overhoot compared to the FOC. DTC i a better choice a compared to FOC a far a peed repone i conidered. 6. Torque Comparion DTC preent a high dynamic at tarting intant and rapid load torque diturbance rejection without overhoot compared to the FOC. t hould be noted that the amplitude of the torque ripple in DTC i lightly higher than that of FOC. The ocillation in FOC cheme are more regular and uniform than the DTC. Torque initially increae in DTC and later on it tabilize at lower value a compared to FOC. FOC i better if tarting torque limit i poed by an application. nternational Conference on Advance in Engineering & Technology 204 (CAET-204) 70 Page

6 V. CONCLUSON The ynthei of thi imulation reveal a advantage of DTC cheme compared to FOC cheme regarding the dynamic flux control performance. Dynamic peed repone i fat in cae of DTC a compared to FOC.Torque initially increae in DTC and later on it tabilize at lower value a compared to FOC. Current pattern and Stator fluxe are alo better for DTC. The uer to identify the more uitable olution for any application that require torque control. Several numerical imulation have been carried; the concluion i that the whole performance of the cheme i comparable. DTC with SVM might be preferred for high dynamic application, but, on the other hand, how higher current and torque ripple. The DTC cheme i impler to implement, requiring a very mall computational time. REFERENCES [] Naceri Farid*, Belkacem Sebti, Kercha Mebarka and Benmokrane Tayeb* Univerity of Batna/Department of Electrical Engineering, Batna, Algeria Performance Analyi of Field-Oriented Control and Direct Torque Control for Senorle nduction Motor Drive July27-29, 2007, Athen-Greece T2-002 [2] F. Parailiti, Appunti delle lezioni di Azionamenti Elettrici: Controllo Vettoriale and Orientamento di Campo, Univerità degli Studi di L Aquila [] R. Di Gabriele, F. Parailiti, M. Turini, Digital Field Oriented Control for induction motor: implementation and experimental reult, Univeritie Power Engineering Conference (UPEC 97) [4] Riccardo Di Gabriele, Controllo vettoriale di velocità di un motore aincrono mediante il Filtro di Kalman Eteo, Tei di Laurea, Univerità degli Studi di L Aquila, Anno Accademico [5] L.Zhang, C. Wathanaarn, F. Hardan, An efficient Microproceor-Baed Pule Width Modulator uing Space Vector Modulation Strategy, EEE 994 [6] Satohi Ogaawara, Hirofumi Akagi, Akira Nabae, A novel PWM cheme of Voltage Source nverter baed on Space Vector Theory, EPE Aachen 989 [8] Joachim Holtz, Pulewidth Modulation-A Survey, EEE 992 [7] Werner Leonard, Control of Electrical Drive, 2nd Completely Revied and Enlarged Edition, Springer [8] F. BLASCHKE, «The principle of field oriented a applied to the new Tran- vector cloed-loop control ytem for rotating machine», Siemen Rev, vol. 9 n 4, pp , 972. [9] C. Lacu,. Boldea, and F. Blaabjerg, «A modified direct torque control for induction motor enorle drive», EEE Tran. ndutry Appl, vol. 6, pp.22-0, Jan/Feb [0] Takahahi, T. Noguchi, «A new quick-repone and high efficiency control trategy of an induction machine» EEE Tran. ndutry Appl, vol. 22, pp , Sep/Oct 986. [] Farouk M. Abdel-kader, A. EL-Saadawi, A. E. KALAS, Oama M.EL-bakawi Study in Direct Torque Control of nduction Motor By Uing Space Vector Modulation /08/$ EEE. [2] B.K.Boe, Modern Power Electronic & AC Drive. Pearon Education. nternational Conference on Advance in Engineering & Technology 204 (CAET-204) 7 Page