COMPARISON OF TWO TARQUE CONTROL METHODS FOR INDUCTION MOTORS

Transcription

1 COMPARION OF TWO TARQUE CONTRO METHOD FOR INDUCTION MOTOR Mohaad Bagh Banna haifian, Ebahi Babai and Ali Eslai Faculty of Elctical and Coput Engining, Tabiz Univsity, Tabiz, , IRAN & Ky wods: Induction Machins, Fild Ointd Contol, Dict Toqu Contol ABTRACT In this pap, th static as wll as th dynaic opations of th fild-ointd contol (FOC) and dict toqu contol (DTC) thods fo induction achins a copad. Fo this pupos, an induction oto with atings of 50 HP, 460 V and 60 HZ is considd. Th siulink odls of both thods a obtaind and th siulation sults show th advantags and disadvantags of ach thod. I. INTRODUCTION Th ost widspad lctochanical systs a basd on th induction otos. Fo th point viw of contol, thy psnt a coplx ultivaiabl nonlina contol pobl. On th oth hand, iplntation of th induction oto contol syst to achiv a high dynaical pfoanc, fficincy, obustnss is an ipotant pactical task [1]. With th appaition of th FOC, induction oto divs hav bco a ajo candidat in high pfoanc otion contol applications. With th coplx achin dynaics, th oupling tchniqu pits indpndnt contol of th toqu and fild. Th concpts of oupling using both flux and toqu coponnts in th FOC thod nabls an asi contol of induction otos. To div th oto with th sulting cunt contol signals th cunts a tansfod to th stato cunt coponnts, which a thn gnatd using puls width odulation [2]. Vaious tchniqus a usd fo contolling toqu induction otos. Aong thos a, th DTC tchniqu, which is a convnint and lativly asy to iplnt. In fact, th DTC is a cobination of th FOC and dict slf-contol tchniqus. It opats basd on th asud voltag and cunt. Th DTC tchniqu ay b iplntd with o without spd snsos, dpnding on th thod usd to stiat th stato flux. Gnally, in th dsign of th div, an attpt has bn ad to duc th quid input data, to as th coputational ti and updat th syst dynaic quations []. Ev sinc th fist dvlopnts of th DTC thod, it has bn usd in any AC div applications. This is du to th fast toqu spons and obustnss against achin paats vaiations. Its sipl stuctu is du to using hystsis copaatos and switching vcto tabls fo flux and toqu contol [4]. II. THE BAIC THEAORY OF THE FOC AND DTC TECHINQUE A. Fild Ointd Contol Blasck (1972) fist dvlopd th fild ointation thod. This is a toqu-flux oupling tchniqu applid to induction achin contol [1]. Th FOC tchniqu is a wll-stablishd and widly usd applid contol tchniqu in daling with high pfoanc induction oto divs. In Fig.1, th block diaga of th FOC contol tchniqu fo induction otos is shown. Fig 1: Block diaga of th FOC tchniqu To achiv a fild ointation th cunt coponnts supplid to th achin should b ointd as such that to

2 isolat th coponnt of th stato cunt, thus poducing a flux. Th q-axis coponnt of th stato fnc cunt, i, ay b coputd using th fnc input toqu (T ) as: wh i = st 2 2 p T st th stiatd flux of th oto, is givn by: ids = (2) st 1 + τ s with and τ a th agntization inductanc, oto ti constanc, spctivly. Th d-axis coponnt of th stato fnc cunt, i ds, also ay b obtaind by using th fnc input flux ( ) as: (1) i ds = () By using th oto spd, ω, and th slip fquncy givn by quation (4): R ωs1 = i (4) st Th angl of th oto flux ay b valuatd using th quation (5): With th vcto quantitis stato voltag ( V ) and cunt I s a bing obtaind using quations (7) and (8) spctivly. 2π 4π j j V = a + b + c (7) 2π 4π 2 j j I = ia + ib + ic (8) wh V, i and i k (i, k = a,b,c) a DC voltag, th signals of th gats of th invt and th stato asud cunts, spctivly. Finally, th lctoagntic toqu T ay b calculatd using: T P = ( I s j ) (9) 2 2 Th oto odl calculats th toqu, stato flux and shaft spd basd on th asunts of two-phas cunt and th cicuit voltag. Toqu and flux fncs a copad with ths valus, and contol signals a poducd using a two lvl hystsis. Th optial switching logic dfins th bst vcto voltag basd on th toqu and flux fncs [6]. θ 1 = (ω + ωs )dt (5) wh R and a th oto sistanc and inductanc spctivly. Th fnc cunts of th stato i ds and i aft tansfing to phas cunts (i a, i b and i c) a ntd to cunt gulatos sction. Th cunt gulatos sction poducs th pattns of th switchs of th invt ( a, b and c ). B. Dict Toqu Contol In addition to vcto contol systs, instantanous toqu contol yilding fast toqu spons ay also b obtaind by ploying DTC thod. Th DTC was dvlopd o than a ad ago by Japans and Gan sachs (Takahashi and Noguchi 1984, 1985; Dpnbock 1985) [5]. Th basic ida in th DTC contol, whit block diaga shown in Fig. 2, is to choos th optial vcto voltag, fo which th gnatd otatd flux poducs th dsid toqu [4]. Th DTC tchniqu is basd on th thoy of th FCO induction oto and dict slf contol thod. Th co of th DTC consists of hystsis contolls of th toqu and flux; optial switching logic; pcis oto odl. Th spac vcto of th stato flux ( ) is calculatd by using: = ( V s R si )dt (6) Fig 2: Block diaga of th DTC tchniqu III. THE IMUATION REUT iulations of th FOC and DTC tchniqus hav bn pfod fo a 50 PH induction oto, with data bing listd in th appndix. In ach cas, a th-phas invt fds th induction oto. Th fquncy switching fo both cass a diffnt, and dpnd to hystsis contolls. Howv, th paats a chosn as such that th fquncy ang is th sa.

3 Fig. : Th siulink odl fo FCO tchniqu Using FOC tchniqu, th band of th hystsis cunt contoll is 10 A, and using DTC, th bands of th hystsis flux and toqu contolls a 0.2 Wb and 40 N., spctivly. To invstigat th dynaic opation of th toqu, a squa wav with aplitud 200 N. is applid to th toqu whil th fnc of th flux bing fixd at ating valu. Th oto opats with low spd, and th switching ti is appoxiatly 0.5 s. To invstigat th opation of th flux, w as th input contol flux to b 0.75 pcnt of th ating valu, whil kping of th toqu fixd. Nxt, w fist dscib th siulation fo both of thods and thn povid th siulation sults. A. Th FOC thod Fig. shows th siulink odl of th FOC tchniqu, wh th q-axis coponnt of th stato cunt is bing considd. Thfo, th opation of th contol syst dpnds on th stato cunts gulatos. Du to th fast spons, th hystsis contolls a usd. Thfo, th switching fquncy of th invt will b vaiabl and will dpnd on th opation conditions. Th vaiation of th toqu is popotional to th vaiation of th q-axis coponnt of th stato cunt: Fig. 4: Th stp spons of th toqu contol in FOC tchniqu T t P i = (10) 2 2 t Figs. 4 and 5 show th siulation sults fo th FOC tchniqu. At FOC tchniqu, as th Fig. 5 shows th stato and oto flux's chang with th ti constanc qual to th oto ti constanc (in this cas τ =0.156 ). Fig. 5: Th stp spons of th flux contol in FOC tchniqu

4 Fig. 6: Th siulink odl fo DTC tchniqu B. Th DTC Mthod Dpnding on th application, lctic vhicl tchnology nds to dvlop induction oto-powd convt systs with quick-spons and high fficincy. Dict toqu contol is usd in any of th nw divs wh th tchniqu is usually basd on th dict contol of th stato flux and toqu [6]. This is accoplishd by sapling th supply voltag and stato cunt and using a hystsis contoll with siulink givn in Fig. 6. By noting that th ti of th toqu spons, dpnds on th angula spd slip and ay b valuatd using th quation (11): ω (ax) ± s = (11) s wh Ψ is th stato flux vcto. Also, th axiu vaiation of th oto toqu is popotional to th axiu angula spd slip: Fig. 7: Th stp spons of th toqu contol in DTC tchniqu T (ax) t P = 2 s ωsl (12) 2 2 s wh ω sl is givn by: ω sl = ωs(ax) ω = ± ω (1) s Thus, th flux stato ay b changd fast and this is shown in Figs. 7 and 8. In this cas, th ti spons of th stato flux is appoxiatly 0.5 s, and this ability shows th fast dynaic spons of th DTC tchniqu spct to FOC tchniqu. At DTC thod, th oto flux follows th stato flux with ti constanc στ (in this cas στ =7 s ). Fig. 8: Th stp spons of th flux contol in DTC tchniqu

5 Howv, a dict toqu contolld oto suffs fo gat toqu ippl du to th fast spons of th toqu. Th ost ipotant chaactistic of DTC is its fast toqu spons. Whn a pop vcto is applid to oto, th stato flux vcto otats vy fast and th angl btwn th stato flux and oto flux is incasd [4]. Dict toqu contol (DTC) is usd to contol th oto. In this contol statgy, fficincy is optiizd by adjusting th agntic flux of th oto [6]. Th ipotant chaactistics of th DTC thod a: Dict contol of stato flux and lctoagntic toqu and indict contol of stato cunts and voltags; Alost sinusoidal stato fluxs and cunts; Rducd toqu oscillations; Excllnt toqu dynaics; Invt switching fquncy dpnding on flux and toqu hystsis bands. Th ain advantags of th DTC thod a: Absnc of coodinatd tansfoations (which a quid in ost of th vcto-contolld div iplntations), spaat voltag odulation block (quid in vcto divs) and voltag oupling cicuits (quid in voltag-souc invt-fd vcto divs); Rducd nub of contolls Dtination of th actual flux-linkag vcto position is not ncssay only th scto wh th flux linkag is locatd. Th ain disadvantags of a convntional DTC thod a: tating, low-spd opation and toqu changs could b of so concn. Th flux-linkag and lctoagntic toqu stiato a ndd. Vaiabl switching fquncy [5]. tato inductanc Magntization inductanc Roto sistanc Roto inductanc REFERENCE s =0.8H =4.7H R =0.228Ω =0.8H [1]. Psada, A. Tonilli, and R. Moici, High- Pfoanc Indict Fild-Ointd Output- Fdback Contol of Induction Motos, Elsvi cinc,. Psada t al./ Autoatica, vol. 5, pp , [2] Haid A. F. Mohad, Hw Wooi Ping, and Nasudin Abd Rahi, Pfoanc Ipovnts to th Vcto Contol-Basd pd of Induction Motos Using liding Mod Contol, ICE 2002, August 5-7, 2002, Osaka, pp [] Jawad Faiz, M.B.B. haifian, Copaison of diffnt switching pattns in dict toqu contol tchniqu of induction otos, Elsvi cinc, Elctic Pow ysts Rsach, vol. 60,, pp.6 75, [4]. Kaboli, M. R. Zolghadi,. Haghbin and A. Eadi, Toqu Rippl Miniization in DTC of Induction Moto Basd on Optiizd Flux Valu Dtination, IEEE 200, pp [5] Pt Vas, nsolss Vcto and Dict Toqu Contol, Oxfod Univsity Pss, [6] J. Faiz,.H. Hossini, M. Ghani, A. Kyhani, and A. Poca, Dict toqu contol of induction otos fo lctic populsion systs, Elsvi cinc, Elctic Pow ysts Rsach, vol.51, pp , IV. CONCUION In this pap, two thods naly FOC and DTC fo contolling th induction otos a considd. Iplntation of th FOC thod quis having a sinusoidal fnc signal, whil on th contay, du to th us of stationay fnc, th DTC thod dos not ncssitats having a sinusoidal fnc signal. Finally, it can b shown that th DTC algoith povids uch fast spons than FOC. Appndix: Induction oto data Ratd pow 50PHP Ratd voltag 460V Ratd fquncy 60Hz Nub of pols 4 tato sistanc R s =0.087Ω