Interntionl Journl of Science nd Reserch (IJSR) Spce Vector Pulse Width Modultion Bsed Induction Motor with V/F Control Vikrmrjn Jmbulingm Electricl nd Electronics Engineering, VIT University, Indi Abstrct: In djustble speed drive system speed control techniques re generlly essentil. Therefore in order chieve this it requires vrible voltge supply nd frequency which is invribly obtined from three-phse Voltge source inverter. Even though there re numbers of pulse width modultions scheme is used to obtin vrible frequency nd voltge supply from n inverter. It is less used thn the spce vector pulse width modultion. Becuse the SVPWM hs severl merits such s better dc bus utiliztion, esier digitl reliztion over the other Pulse width modultion methods. In the spce vector pulse modultion method with voltge / frequency control of induction motor drive is widely used in medium performnce drive system. It is due to its chrcteristics like good power fctor, extremely rugged nd high efficiency. This scheme leds to be ble to djust the speed of the motor by control the frequency nd mplitude of the sttor voltge, the rtio of sttor voltge to frequency should be kept constnt. In this pper the voltge source inverter type spce vector pulse width modultion model design nd implementtion hs been done through MATLAB / SIMULINK softwre for the speed control of induction motor. In ddition to these prmeters like sttor current, rotor current, torque nd speed re obtined grphiclly. Keywords: SVPWM, V/F Control, Induction motor, Pulse Width Modultion 1. Introduction The induction motor or synchronous is the most widely used electricl drive. [1] Hs explined the complete nlysis of electricl mchinery drive system. Actully becuse independent control of torque nd flux seprtely excited dc drives re simpler in control. Due to ruggedness, efficiency nd simplicity the induction motors hve been used in severl pplictions for over century. [2-] hs presented the nlysis nd simultion model development of induction motor in MATLAB / SIMULINK softwre. In ddition to tht the induction motors involve corresponding control of sttor current mgnitude nd the phse, mking it complex control. The sttor flux linkges cn resolve long ny frme of reference. For this ction it requires position of flux linkge t every instnt. In ddition to this the control of the c mchine is very similr to tht of seprtely excited direct current motor nd lso this type of control involves field coordintion. So it is lso clled s field oriented control [vector control]. The vector control is divided in to two types on the bsis of method of mesurement. They re indirect nd direct vector control. Therefore in the cse of direct vector control, the flux mesurement is done by using the flux sensing coils or the Hll devices. But in cse of indirect vector control the flux ngle is not clculted directly, but it is predicted from the equivlent circuit model nd from mesurements of the sttor current, voltge nd rotor speed. The Min resons for two level inverter topologies is to provide three phse voltge source, where the phse, frequency of the voltge nd mplitude, phse should lwys be controllble. SVPWM technique is widely used in rectifier nd inverter controls. In SV pulse width modultion inverter the voltge utiliztion fctor cn be incresed to 0.906, normlized to tht of the six step opertion. The SP Pulse Width Modultion cn be obtined by suitbly dding zero-sequence voltge to the originl modultion wveform. The motor-control issues re conventionlly hndled by fixed gin PI nd PID controllers. 2. Spce Vector Pulse Width Modultion Principle The spce vector pulse width modultion technique is frequently used in direct torque control drive nd vector control drive. In ddition to this when current control is exercised in rotting reference frme. The reference voltge genertion is used in prticulrly for vector control drives. The vector forms the hexgon s shown in figure.1. At the sme time it consists of six sector spnning 60 degree ech. Actully it consist of eight switching sttes which includes two zero sttes nd six ctive sttes generted by the voltge source inverter. The three phse voltge is represented by reference vector nd it is generted by using spce vector pulse width modultion by switching between two nerest ctive vectors nd zero vectors. Figure 1: Spce vector digrm for three level inverter Pper ID: NOV161260 964
Interntionl Journl of Science nd Reserch (IJSR). Mthemticl Model of Spce Vector Pulse Width Modultion Step 1: For finding the vlues of U, U, U, U the equtions 1, 2,, 4 nd 5 re used. ndu b c lph Figure 2: Spce vector time clcultion The bove figure.2 hs to be tken in to ccount to clculte time of ppliction of different vectors. At the first sector depict the position of different vilble spce vectors nd reference vectors. In ech leg the chnges tkes plce only once in one switching period to obtin optimum hrmonic performnce nd fixed switching frequency from spce vector pulse width modultion. This cn be chieved by pplying zero stte vectors followed by two djcent ctive vectors in hlf switching period nd in the next hlf of the switching period it contins the mirror imge of the first hlf. In this cse the totl switching period is divided in to seven prts fter tht the 0 vector is pplied for one fourth of the totl 0 vector time first nd then followed by the ppliction of ctive vectors for hlf of their ppliction time nd then gin 0 vector is pplied for one fourth of 0 vector time. Now once gin this is repeted in the next hlf of the switching period. This is repeted in the next hlf of the switching period. This is how the spce vector pulse width modultion is obtined. The leg voltge nd spce vector disposition for one switching period in sector 1 is shown in figure.. [4-8] hs explined in detil bout spce vector pulse width modultion technique of induction motor nd simultion model is developed in ddition to this it is tested successfully in MATLAB / SIMULINK softwre. U u(1)*sin{ u(2)*2* pi * u()} Eqution.1 pi Ub u(1)*sin{ u(2)*2* pi* u() 2* } Eqution.2 pi Ub u(1)*sin{ u(2)*2* pi* u() 2* } Eqution. 2 Ulph *( U 0.5* Ub 0.5* Uc ) Eqution.4 2 U *( Ub Uc) Eqution.5 2 2 Step 2: To Find the suitble sector judgment U 0, A 1 Eqution.6 U U 0, B 1 Eqution.7 lph U U 0, C 1 Eqution.8 lph Once A, B, C vlues re determined then find the N vlue, by substituting the vlues of A, B, C in eqution 9. N A 2B 4 C Eqution.9 Sector I II III IV V VI N 1 5 4 6 2 Step : Clculte the operting time of the fundmentl vectors The vlues of X, Y, Z re clculted by the following equtions, X 2 T( U ) / (2* U ) Eqution.10 Y T( U U ) / (2* U ) Eqution.11 dc lph dc Z T( U U ) / (2* U ) Eqution.12 lph dc T1 T2 T Eqution.1 If T1 T2 T Eqution.14 then, T T { T / ( T T )} Eqution.15 1 1 1 2 T T { T / ( T T )} Eqution.16 2 2 1 2 Figure : Leg voltge nd spce vector disposition for one switching period in sector 1 N 1 2 4 5 6 T1 Z Y -Z -X X -Y T2 Y -X X Z -Y -Z Step 4: Clculte the switching operting time Pper ID: NOV161260 965
T { T T T }/ 4 Eqution.17 1 2 T T { T / 2} Eqution.18 b 1 T T { T / 2} Eqution.19 c b 2 Interntionl Journl of Science nd Reserch (IJSR) N 1 2 4 5 6 Tcm1 Tb T T Tc Tc Tb Tcm2 T Tc Tb Tb T Tc Tcm Tc Tb Tc T Tb T 4. V/F Control Method The closed loop v/f control of induction motor is nothing but pplying vrible voltge nd vrible frequency to the motor. In ddition to this the shft position encoder or speed sensor is used to monitor the ctul speed of the induction motor. Once the ctul speed is found then the ctul speed is compred with the reference speed. Now the difference between the ctul speed nd the reference is known s error. This error is processed through controller nd then the frequency of the inverter is fixed. By dding ctul speed nd slip speed the synchronous speed of the induction motor is obtined nd this determines the frequency of inverter. The block digrm of voltge / frequency is shown in figure.4. [9] Hs developed MATLAB / SIMULINK model for voltge / frequency control of three phse induction motor drive with different pulse width modultion techniques nd lso tested. Figure 5: MATLAB simulink model of SVPWM bsed induction motor The figure.5 shows the complete MATLAB / SIMULINK model of the spce vector pulse width modultion bsed induction motor with v/f control. The step by step subsystem model of the SVPWM method is shown figure.6, figure.7, figure.8, figure.9, figure.10 nd figure.11. These subsystem models re designed on the bsis of the mthemticl eqution of SVPWM methods s it is discussed in chpter. Figure 6: MATLAB simulink subsystem model for the genertion of gte pulse Figure 4: Block digrm of V/F control method 5. Simultion Model of SVPWM nd V/F Control The simultion results re given for the induction motor for the following specifiction: Number of poles [P] = 4, Frequency [F] = 50 Hz, Number of phses =, Sttor resistnce [Rs] = 6 ohms, Rotor resistnce [Rr] = 10 ohms, Sttor inductnce [Ls] = 450 mh, Mutul inductnce [Lm] = 90 mh, Moment of inerti [J] = 0.0088 Kg-m/sec. Figure 7: MATLAB simulink subsystem model for sector judgment Pper ID: NOV161260 966
Interntionl Journl of Science nd Reserch (IJSR) Figure 11: MATLAB simulink subsystem model for generting SVPWM Figure 8: MATLAB simulink subsystem model for clculting X, Y, Z 6. Simultion Results 6.1. Sttor Current Figure 9: MATLAB simulink subsystem model for clculting operting time of the fundmentl vectors Figure 12: Sttor current 6.2. Rotor Current Figure 10: MATLAB simulink subsystem model for clculting switching operting time Figure 1: Rotor current Pper ID: NOV161260 967
6.. Speed 6.4. Torque 7. Conclusion Interntionl Journl of Science nd Reserch (IJSR) Figure 14: Speed Figure 15: Torque In this reserch pper spce vector pulse width modultion bsed induction motor with v/f control model is designed through MATLAB softwre nd lso tested successfully by evluting the prmeters like sttor current, sttor current, torque nd speed.. It is due to its chrcteristics like good power fctor, extremely rugged nd high efficiency. This scheme leds to be ble to djust the speed of the motor by control the frequency nd mplitude of the sttor voltge, the rtio of sttor voltge to frequency should be kept constnt. In ddition to tht the design nd implementtion of n induction in simulink is uncomplicted nd trouble free. These types of induction motors cn be used in lthes, drilling mchines, lifts, crnes, conveyors, industril drives, griculturl nd industril pumps. References [1] P. C. Kruse, O. Wsynczuk, S. D. Sudhoff Anlysis of Electric Mchinery nd Drive Systems, IEEE Press, A John Wiley & Sons, Inc. Publiction Second Edition, 2002. [2] H. C. Stnley, An Anlysis of the Induction Motor, AIEE Trnsctions, Vol. 57 (Supplement), pp. 751-755, 198. [] Burk Ozpineci, L.M.Tolbertr, Simulink Implementtion of Induction Mchine Model-A modulr pproch, IEEE rns.200. [4] S. A. Shirsvr, M. D. McCulloch nd C. G. Guy, Speed Sensor less Vector Control of Induction Motor with Prmeter Estimtion, "IEEE Conf. On Industril Applictions, vol.1, pp. 262-269, 1996. [5] R. Ling Swmy nd P. Stish Kumr, Speed Control of Spce Vector Modulted Inverter Driven Induction Motor Proceedings of the Interntionl Multi Conference of Engineers nd Computer Scientists 2008 Vol. III MECS 2008 Mrch, pp 19-21. [6] M Kubeitri, Spce Vector PWM Simultion for Three Phse DC/AC inverter, World Acdemy of Science, Engineering nd Technology 70 2012, pp 16-144. [7] K. Vinoth Kumr, Prwin Angel Michel, Joseph P. John nd Dr. S. Suresh Kumr, Simultion nd comprison of spwm nd svpwm control for three phse inverter ISSN 1819-6608, ARPN Journl of Engineering nd Applied Sciences, Vol. 5, No. 7, July 2010. [8] Shilp V. Kilswr nd Prof. R.A.Keswni, Speed Control of Three Phse Induction Motor by V/f Method for Btching Motion System Interntionl Journl of Engineering Reserch nd Applictions (IJERA) ISSN: 2248-9622 www.ijer.com Vol., Issue 2, Mrch -April 201, pp.172-176. [9] El-Nobi A. Ibrhim1 Mohmed Elbesely, V/F control of Three Phse Induction Motor Drive with Different PWM Techniques, Innovtive Systems Design nd Engineering,ISSN:2222-1727 (Pper) ISSN 2222-2871 (Online), Mrch 201Vol.4, No.14.pp11-144. Author Profile Mr. J. Vikrmrjn received his Mster degree in Power Electronics nd Drives nd Bchelor degree in Electricl nd Electronics Engineering from VIT University, Indi. He hs published severl interntionl reserch books nd journls. His reserch interests re electricl mchines, power electronic pplictions, power qulity, power electronic converters nd power electronic controllers for renewble energy systems. Pper ID: NOV161260 968