Matlab Simulink Implementation of Switched Reluctance Motor with Direct Torque Control Technique

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1 Matlab Simulink Implementation of Switched Reluctance Moto with Diect Toque Contol Technique Vikamaajan Jambulingam Electical and Electonics Engineeing, VIT Univesity, India. Abstact - The switched eluctance moto is one of the types of electical machines. This type moto eceives consideable esponse fom industies in last decades due to high toque, high eliability and inexpensive manufactuing cost. But the main dawback of switched eluctance moto is lage toque ipple. This poduces vibation and noise in the moto. Theefoe in ode to ovecome that poblem the diect toque contol technique is implemented. Due to this DTC technique the output toque of the switched eluctance moto can be egulated within the hysteesis band. This pape descibes the mathematical model of SRM moto and diect toque contol technique. In addition to this the simulink model of switched eluctance moto with diect toque contol technique is designed and tested though MATLAB/Simulink softwae. The paametes like speed and toque ae epesented gaphically. Keywods - SRM Moto, Diect Toque Contol, Switched Reluctance Moto, DTC Technique. I. INTRODUCTION The switched eluctance moto ugged in constuction theefoe it can be suitable fo vibating and high tempeatue zone. The toque poduced by the switched eluctance moto is not dependent of phase cuents polaity. Theefoe the less numbe of semiconducto switches ae used in the powe convetes. In addition to this the loss occued in the SRM moto is fom the stato only. Hence it can be cooled easily. The switched eluctance moto ae mainly used in electic vehicles, vacuums cleane, washing machine, sevo type and vaiable speed applications. The switched eluctance moto simulink model consists of thee main blocks. They ae position senso block, convete block and switched eluctance block. The position senso block consists of a position senso which is linked to the oto of switched eluctance moto. Hence the tun-on and tun-off angles of the switched eluctance moto phases can be measued accuately. To contol the developed toque switching angles ae used. At the same time the measued cuent and efeence cuent ae compaed to geneate dive signal fo insulated gate bipola tansisto. Hence the hysteesis contolle contols the cuents independently. The convete block consists of thee legs and each leg consists of two insulated gate bipola tansisto and two FW diodes. R Kishnan has pesented the detailed switched eluctance moto dive modeling, simulation, analysis, design and applications [1]. II. CONSTRUCTION AND WORKING PRINCIPLE OF SWITCHED RELUCTANCE MOTOR Actually in electical machines the switched eluctance moto is the simplest one when compae to othe electical machines. Constuction wise thee is no pemanent magnet o conductos in the oto of switched eluctance moto. The oto of switched eluctance moto consists of steel lamination stacked on to a shaft. In addition to this the cost of moto is low due to simple mechanical constuction. T. J. E. Mille has explained the Switched Reluctance Motos and thei Contol techniques [2]. The Figue [1] shows the coss sectional view of a switched eluctance moto. Fom figue [1] we can see the 6/4 pole aangement. That is the stato and oto poles of switched eluctance moto. Thee phase supply is given to the 6/4 switched eluctance. Figue.1 6/4 Thee phase SRM moto IJEDR Intenational Jounal of Engineeing Development and Reseach ( 48

2 On the basis of toque poduction the electical machine ae classified in to two types. Theefoe the one way of toque poduction is due to electomagnet and the othe way of toque poduction is due to vaiable eluctance. In switched eluctance moto the toque is poduced due to vaiable eluctance. Hence it is known as switched eluctance moto. The main pinciple of SRM moto is to give ise to minimum magnetic eluctance in ode to fom a stable equilibium position in electomagnetic system. The neaest oto poles ae attached towads each othe. At the time two diametically opposite poles ae excited to poduce toque. But de-enegize takes place when two oto poles gets aligned with the stato pole. Now the adjacent stato pole gets enegized to attact anothe pai of oto poles. The aligned position is nothing but when the oto poles and the stato poles get aligned in a cetain position. At this time the la eaches maximum value. So as eluctance eaches minimum value. Once the L a value deceases gadually then the oto poles move away fom its aligned position and eluctance value eaches minimum value. Since the L a value deceases gadually the oto poles moves away fom its aligned position. At a cetain point the oto poles moves to a complete unaligned position fom stato poles. At that moment phase inductance value eaches minimum value L u and eluctance eaches maximum value. Figue.2. Block diagam of DTC technique The toque flux calculato block is used to estimate flux components {alpha and beta} and electomagnetic toque. Based on moto equations the estimations ae done. The vecto block is used to find the alpha and beta. The hysteesis contol block is used to contol flux and toque. Then fom the look table which is pesent inside the switching table block will select the specific voltage vecto. The invete commutation fequency is limited in the switching contol block. III. MATHEMATICAL MODEL OF SWITCHED RELUCTANCE MOTOR The numeical and analytical modeling of switched eluctance machine has been explained clealy by Zhang zhihui and Somesan Liviu [3-4]. A New Toque and Flux Contol Method fo Switched Reluctance Moto Dives have been developed by A. D. Cheok [5]. S Mi designed the Toque Ripple Minimization in Switched Reluctance Motos Using Adaptive Fuzzy Contol model [6]. Mathematical equations fo switched eluctance moto: d {, I} V RsI Equation{1} R s=resistance / phase = flux linkage / phase L{, I} I Equation{2} L=Mutual inductance {depends on oto position and phase cuent} Phase Voltage equations, d{ L(, I) I} V RsI Equation{3} di d dl{ L(, I)} V RsI L{, I} I Equation{4} d di dl (, I) V RsI L{, I} mi Equation{5} d dl (, I) e mi KbmI Equation{6} d dl(, I) Kb Equation{7} d IJEDR Intenational Jounal of Engineeing Development and Reseach ( 49

3 Instantaneous input powe is the sum of winding esistance loss, ate of change of field enegy and ai gap powe. Theefoe the instantaneous input powe can be witten as, 2 2 dl{, I} di PI VI RsI I L{, I} I Equation{8} Time, t Equation{9} m Ai gap powe equations, 1 2 dl{, I} Pa I Equation{10} dl{, I} d Pa I Equation{11} 2 d 1 2 dl{, I} Pa I m Equation{12} 2 d P T Equation{13} a m e By equating the equations 12 and 13 we get toque {T e}, 1 2 dl{, I} Te I Equation{14} 2 d Mathematical equations fo diect toque contol technique: 3 P Lm Te s * Equation{15} 2 2 Ls' L 3 P Lm Te s sin Equation{16} 2 2 L ' L s The stato flux assessment is done on the basis of stato voltage model and cuent model. The equation 17, 18 and 19 epesents stato voltage equations. In case of cuent model equation 20 and 21 ae used. s V s i s R Equation {17} V i R Equation {18} ds ds ds s s s s qs qs qs s s 2 s 2 s ds qs Equation {19} d Li m s Equation{20} T L m s Lsis Equation{21} L IV. SIMULATION MODEL OF SWITCHED RELUCTANCE MOTOR WITH DIRECT TORQUE CONTROL TECHNIQUE In the MATLAB simulation of switched eluctance moto the following specification ae used: Numbe of phases = 3, Numbe of stato and oto poles = 6/4, Fequency [F] = 50 Hz, DC supply voltage [Vdc] = 240 volts, Tun on and off angle = 45 deg and 75 deg espectively, Refeence cuent = 200 amps, Hysteesis band = +10, -10. Fiction = 0.01 N-M s, Stato esistance [R] = 0.01 ohms/phase, Moment of inetia [J] = Kg-m/sec, Unaligned inductance = 0.7 m H, Aligned Inductance = 20 m H. The simulation of a 6/4 switched eluctance moto based on MATLAB/Simulink envionment has clealy pesented by F Soaes and C Banco [7]. IJEDR Intenational Jounal of Engineeing Development and Reseach ( 50

4 Figue.3 MATLAB simulink model of switched eluctance moto with DTC technique V. SIMULATION RESULTS [A] Cuent Figue.4 MATLAB simulink subsystem model of diect toque contol block IJEDR Intenational Jounal of Engineeing Development and Reseach ( 51

5 [B] Flux Figue.5. Cuent in Ampee [C]Inductance Figue.6 Flux in Webe IJEDR Intenational Jounal of Engineeing Development and Reseach ( 52

6 [D] Toque Figue.7 Inductance in Heny [E] Speed Figue.8 Toque in Newton-Mete IJEDR Intenational Jounal of Engineeing Development and Reseach ( 53

7 Figue.9 Speed in Revolution pe Minutes Fom Figue [8] it is obseved that the toque is diectly popotional to the squae of cuent, theefoe the toque of the switched eluctance moto is independent of cuent diection but it depends on dl d value. If this value is positive then the toque of switched eluctance moto is also positive. In case if it is negative then toque of the switched eluctance moto is negative. But this toque contains lot of noise and hamonics. VI. CONCLUSION The switched eluctance moto ae mainly used in electic vehicles, vacuums cleane, washing machine, sevo type and vaiable speed applications. The switched eluctance moto gives high pefomance in hash conditions like dusty envionment and high tempeatue. In this eseach pape switched eluctance moto model with diect toque contol is designed though MATLAB softwae and also tested successfully by pesenting the toque and speed values gaphically. The potential of switched eluctance moto is highly geate paticulaly in motion contol. VII. REFERENCES [1] R. Kishnan, Switched Reluctance Moto Dives Modelling, London, CRC Pess, [2] T. J. E. Mille Switched Reluctance Motos and thei Contol, Magna Physics & Oxfod [3] Zhang Zhihui and Li Yuen, Numeical and Analytical Modeling of Switched Reluctance Machines, Jounal of Computes, Vol.7, no.12, Dec [4] Somesan Liviu, Paduaiu Emil, Simple Analytical Models of Switched Reluctance Moto fo Design and Contol Pupose, Jounal of Compute science and Contol Systems, Vol.4, no.1, May [5] A. D. Cheok, Y. Fukuda, "A New Toque and Flux Contol Method fo Switched Reluctance Moto Dives," IEEE Tansl. on Powe Electonics, vol. 17, pp , July [6] S. Mi, I. Husain, M. Elbuluk, Toque Ripple Minimization in Switched Reluctance Motos Using Adaptive Fuzzy Contol, IEEE Tans. on Ind. Appl.,vol. 35, pp , Mach/Apil [7] F. Soaes and C. Banco, Simulation of 6/4 Switched Reluctance Moto Based on MATLAB/Simulink Envionment, IEEE Tansaction on Aeospace and Electonics System, Volume 37, Issue 3, July VIII. BIOGRAPHY M.J.Vikamaajan eceived his Maste degee in Powe Electonics and Dives and Bachelo degee in Electical and Electonics Engineeing fom VIT Univesity, India. He has published seveal intenational eseach books and jounals. His eseach inteests ae electical machines, powe electonic applications, powe quality, powe electonic convetes and powe electonic contolles fo enewable enegy systems. IJEDR Intenational Jounal of Engineeing Development and Reseach ( 54