DIRECT TORQUE CONTROL OF MULTILEVEL INVERTER- FED INDUCTION MACHINES A SURVEY

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1 31 t July Vol. 41 No JAI & LLS. All ight vd. DIREC ORQUE CONROL OF MULILEVEL INVERER- FED INDUCION MACHINES A SURVEY 1 NAZIHA AHMAD AZLI, 2 NORJULIA MOHD NORDIN, 3 NIK RUMZI NIK IDRIS Univiti knologi Malayia, Faculty of Elctical Engining, Dpatmnt of Engy Convion, UM Skudai, Joho, Malayia 1 naziha@i.og, 2 nojulianodin@i.og, 3 nikumzi@i.og ABSRAC Dict oqu Contol with Multilvl Invt (DC-MLI) ha mgd cntly in high dynamic AC div fild fo induction machin o pmannt magnt machin application. In thi pap, a viw on a vaity of tchniqu and concpt of dict toqu contol of multilvl invt-fd induction machin i pntd. h tchniqu and concpt involvd a claifid a follow: Look-up tabl hyti bad DC-MLI, DC-MLI with pac vcto modulation, pdictiv contol tatgy of DC-MLI, hybid modulation and hybid invt tatgy of DC-MLI and DC-MLI with fuzzy logic contoll. Fom thi viw, th popti of th dicud contoll tchniqu togth with advantag and diadvantag a pntd. Kywod: Dict oqu Contol (DC), multilvl invt, look-up tabl, Spac Vcto Modulation (SVM), pdictiv, Fuzzy Logic Contoll (FLC) 1. INRODUCION Induction Machin (IM) hav bn widly ud in th induty du to th fact that it i maintnanc f, impl in tm of contuction, liabl and uggd. In contat to th commutation DC moto, induction machin can b ud in an xploiv, cooiv o any hah nvionmnt. hi i bcau th latt ha no poblm with pak and cooion which i du to th commutato and th buh a in th fom. Dpit th advantag, IM howv, uff fom contol poblm whn ud in high pfomanc Adjutabl Spd Div (ASD) application. Bad on th commonly adoptd pac phao dynamic modl [1-3], quation latd to th dynamic modling of an IM a :- d v = R i + + jω (1) dt d dt 0 = R i + + j( ω ω ) (2) = L i + L i (3) m = L i + L i (4) m 3 P i (5) = 2 dω m J dω L = J = (6) dt P dt wh v,,, i and i a th tato voltag, tato flux, oto flux, tato cunt and oto cunt vcto pctivly; ω and ω m a th oto pd in ad/ and mchanical pd in pm; L, L and L m a th tato, oto and magntizing inductanc;, L,J and P a th lctomagntic toqu, load toqu, ytm intia and th numb of pol pai, pctivly. h pac phao quantiti a xpd in th gnal fnc fam which otat at a gnal pd, ω. h up-cipt dnot that th quantiti a in th gnal fnc fam. Contolling IM i conidably mo complx than that of DC machin. h a val way of contolling IM. It can b claifid into two gnal contol mthod; Scala and Vcto Contol. In cala contol, only th magnitud and fquncy, which i bad on th tady tat modl of IM of a pac vcto vaiabl uch a cunt, voltag and flux linkag, a contolld. Contaily, in vcto contol, th toqu dvlopd in th moto togth with th magnitud and fquncy of pac vcto of th-pha moto vaiabl a manipulatd in th contol algoithm. h pac 181

2 31 t July Vol. 41 No JAI & LLS. All ight vd. vcto pnt th intantanou valu of th coponding th-pha vaiabl which a bad on an IM dynamic modl. Vaiou mthod hav bn dicovd to implmnt vcto contol fo IM. On of th wllknown vcto contol mthod i Fild Ointd Contol (FOC) that ha bn popod by F. Blachk [4] and K. Ha [5] hi typ of contol i oto-flux ointd bad which man th oto flux vcto i th ointing vcto of th contoll. hi mthod nabl IM to mulat th paatly xcitd DC machin and giv it high dynamic pfomanc. In FOC, th poition no i mployd fo coodinat tanfomation of th IM quation. FOC can b dividd into two typ; Dict and Indict. In th ca of Dict FOC (flux-fdback contol), th oto flux linkag vcto i dtmind by dict maumnt of th ai-gap flux. It i th only paamt that can b maud dictly fom th moto (uing a wo Hall no o ach coil o tappd tato winding of th machin [2]) togth with th tato cunt and calculatd dictly by a o-calld flux modl. Fo Indict FOC (flux-fdfowad contol), th oto flux linkag vcto i dtmind indictly by utilizing th monitod tato cunt and oto pd. h oto flux linkag angl that i ud in th coodinat tanfomation i obtaind a a um of th oto angula poition that i maud by a haft poition no and th lip angula poition. Oth than oto-flux ointd bad, FOC can b contolld bad on tato-flux ointation which i known a Stato Flux Ointd Contol (SFOC) [6]. In contat to th oto-flux FOC, SFOC do not qui th knowldg of oto pd. Intad, only th tato itanc, voltag and cunt valu a quid. hfo it i mo obut to paamt vaiation and ai to implmnt [7]. In aly 1980, an innovation on FOC ha bn mad by Iao akahahi and Noguchi [8] and Dpnbock [9] in which ca th coodinat tanfomation block i omittd. h block i placd with th bang-bang o hyti contoll [1] fo th dvlopd toqu and tato flux. In addition, th appoach in contolling th invt i claly diffnt fom that of FOC. hi contol tatgy i fd to a Dict oqu Contol (DC). DC ha bn xpincing continuou impovmnt and futh dvlopmnt by many oth ach thoughout th ya. h 1990 th mgnc of tchnologi that qui high lvl of pow and voltag. Multilvl invt hav thn bn highlightd a th olution at uch lvl of opation. Multilvl invt a known to off val advantag uch a vy low hamonic ditotion, low dv/dt, no output filt quimnt tc. [10]. Du to th continuouly volving indutial application that nd high pow and voltag opating lvl a wll a high pfomanc of machin application, ach hav popod to xtnd o adapt th taditional DC chm to multilvl invt topologi. hi man that th multilvl invt a placing th convntional th-pha invt that hav bn pviouly ud in th taditional DC configuation to upply th tato voltag fo th IM. hi pap pnt a viw on th dvlopmnt and impovmnt of DC with multilvl invt contol tchniqu fo IM. h baic concpt of convntional DC and DC-MLI a givn in Sction 2. Vaiou tchniqu and concpt of DC-MLI uch a look-up tabl tatgy pac vcto modulation tatgy, pdictiv tatgy, hybid tatgy and fuzzy logic tatgy a dicud fom ction 3 to 7 pctivly, bfo fowading th concluion of th viw. 2. DC BASIC CONCEP Fig. 1 how th gnal DC block diagam. h intantanou valu of flux and toqu a calculatd fom th maud vaiabl of th IM and dictly contolld by lcting an optimum witching tat of th invt o that th quid Fig. 1. nal DC block diagam optimum voltag vcto i gnatd. In tationay fnc fam, th tato voltag vcto a in (1), can b wittn a, d v = R i + (7) dt 182

3 31 t July Vol. 41 No JAI & LLS. All ight vd. If it i aumd fo ov a mall piod of tim and th voltag dop aco th tato itanc can b nglctd, (7) can b wittn a, v = t (8) which claly how that th vaiation of tato voltag vcto i dictly affctd by th tato flux linkag vcto. hu th tato flux locu can b contolld by lcting th appopiat voltag vcto. In DC chm, th adiu of th locu which i alo known a th tato flux magnitud i focd to follow a cicula path by limiting it magnitud within th hyti band. Whn th tato flux touch th upp o th low hyti band, an appopiat voltag vcto i lctd ith to dca o inca th tato flux magnitud, pctivly. Contaily, vaiation of th tato voltag ov th oto flux linkag i filtd by th oto and tato lakag inductanc. hfo ov a mall piod of tim, th oto flux i aumd to hav a low otation compad to th tato flux. Fo that aon whn th voltag vcto i applid, th tato flux will hav a quick movmnt. Hnc th angl btwn both flux vcto, θ will inca and that will cau an inca in th lctomagntic toqu,. h lation btwn th tato-oto flux angl and th lctomagntic toqu can b xpd a th-pha IM, a th-pha multilvl invt i quid. h th-pha multilvl invt i compod of th multilvl invt lg. h a th pominnt multilvl invt topologi: Diod-clampd multilvl invt (DCMI) o nutal-point clampd (NPC) invt, Flying Capacito multilvl invt (FCMI), and Cacadd H-Bidg multilvl invt (CHMI). Fig. 2 (a), (b), and (c) how on of th th multilvl invt lg that a quid in fding a th-pha IM. 3 3 = P i = P inθ (9) 2 2 wh and a th magnitud of tato flux linkag and th magnitud of oto flux linkag pctivly and thi xpion i in th tationay fnc fam. In oth wod, th vaiation of th tato voltag will affct both tato flux and tatooto angl movmnt. hi pincipl i ud in DC to achiv th did toqu pon and to coct th flux tajctoy of th induction machin. A. DC with Multilvl Invt (DC-MLI) Whn a multilvl invt i ud in th DC configuation to fd th IM, th numb of availabl voltag pac vcto i incad popotionally to th voltag lvl of th invt. By having thi xta flxibility in lcting th optimum voltag vcto, a mo pci contol of both toqu and flux can b obtaind. o fd a Fig. 2. Multilvl invt lg fo ingl pha. (a) Nutal-point Clampd (NPC) topology (b) Flying Capacito (FCMI) topology (c) Cacadd H-Bidg In Fig. 3 th gnal block diagam of a thpha IM fd by a th-pha multilvl invt i hown. h contol tatgy block gnat th appopiat voltag vcto in od to kp th fnc (toqu, pd o poition) at th ight valu. Fig. 4 (a), (b), and (c) how a t of voltag pac vcto that can b gnatd by an NPC invt, FCMI, and CHMI pctivly. By injcting th quid valu of th voltag vcto to th invt contol block, th witching tat i gnatd accodingly fo ach multilvl invt lg. 183

4 31 t July Vol. 41 No JAI & LLS. All ight vd. Sval contol tatgi hav bn popod fo DC-MLI uch a look-up tabl tatgy (LU), pac vcto modulation tatgy (SVM), pdictiv contol tatgy, fuzzy logic contol tatgy (FLC) and hybid contol tatgy. h dtail of th contoll a dcibd in th following ction. (a) Fig. 3. nal block diagam of th-pha IM fd by th-pha multilvl invt 3. LOOK-UP ABLE SRAEY OF DC- MLI (LU-DC) A gnal block diagam fo DC with Look-up abl (LU-DC) i hown in Fig. 5. (b) Fig. 5. nal block diagam fo DC with look-up tabl tatgy (DC-LU) h tato flux, and toqu, fnc i compad to tato flux, and toqu, by uing th flux and toqu hyti contoll, pctivly. In th claical DC which u a convntional th-pha invt, th d-q flux plan i dividd into 6 cto. h flux and toqu (c) Fig. 4. St of voltag vcto that can b gnatd by multilvl invt topology. (a) 3-lvl Nutalpoint Clampd (NPC) topology (b) 5-lvl Flying Capacito (FCMI) topology (c) 5-lvl Cacadd H- 184

5 31 t July Vol. 41 No JAI & LLS. All ight vd. hyti contoll conit of two- and th-lvl compaato pctivly that gnat th digitizd output ignal which can b dfind a, o = 0 fo > H, upp o = 1 fo < H, Low fo flux and = 1 fo o > H, upp o = 0 fo = 0 o = 1 fo < H, Low fo toqu, wh o and o i th tato flux and lctomagntic toqu o; H,upp, H,Low, H,upp, H,Low, a th flux and toqu hyti upp and low band, pctivly. Howv whn DC i adaptd o xtndd to th multilvl invt, th hyti contoll nd to b modifid to uit th multilvl invt topology. Adaptation of DC on a FCMI o NPC invt i pntd in [11] and [12]. In both ca, th d-q flux plan i dividd into 12 cto. But whn it com to lcting th appopiat voltag vcto to coct th actual flux and toqu, diffnt appoach hav bn popod. In [11], balancing of th nutal-point voltag nd to b takn into account whn lcting th voltag vcto. hfo th vitual vcto concpt which mploy an optimum look-up tabl fo a witching tatgy ha bn adoptd in lcting th uitabl voltag whil at th am tim th nutal-point voltag i maind balancd. In th vitual vcto concpt, a imila hyti contol a th claical DC i mployd.. On th contay, in [12], th flux contol i compod of a two-lvl hyti compaato that i dfind in th gion; Ngativ Flux o, Zo Flux o, and Poitiv Flux o. A fo th toqu contol, it mploy a fiv-lvl hyti compaato that i dfind in fiv gion; Ngativ Lag oqu o, Ngativ Small oqu o, Zo oqu o, Poitiv Small oqu o, and Poitiv Lag oqu o. Fo th witching tatgi, two diffnt appoach hav bn popod. hu, bad on12 cto in th d-q flux plan, two typ of witching tabl wh by ach of it hold on appoach a dvlopd. Simila to th NPC invt, th witching tatgy in an FCMI a pntd in [13] mut b capabl of balancing th capacito voltag and th quid voltag lvl. In th FCMI witching tatgy, th d-q flux plan i dividd into 12 cto with th mchanical oto pd takn into conidation in th voltag vcto lction. hfo, fou witching tabl a ud. Each tabl copond to th pcific ang of oto pd. Whn th pd i low, low amplitud voltag vcto i lctd whil at high pd, high amplitud of voltag vcto i lctd. In thi witching tabl, flux and toqu a idntifid uing 3 diffnt tat; 0 man th flux and toqu i within th limit of th hyti contoll, 1 man th valu a gat than th upp limit; and -1 man th valu a mall than th low limit. 4. SPACE VECOR MODULAION SRAEY OF DC-MLI (DC-SVM) h u of a hyti compaato in claical DC i known to cau vaiation in witching fquncy that i undiabl inc it can lad to dynamic onanc xcitmnt in th load and hnc contitut a iou dawback to DC. hi i bcau; th witching fquncy i a function of moto pd, tato and oto flux, and tato voltag which alway vay with tim. In addition th invt witching capability i not fully utilizd and alo ult in cunt and toqu ditotion du to cto chang [14, 15]. A combination of DC and Spac Vcto Modulation (SVM) avoid th u of look-up tabl in lcting th voltag vcto. SVM i ud to ynthiz a quid voltag vcto that ha bn calculatd by th contoll in th DC chm. By uing a pac vcto modulato, th toqu ippl i ducd and th witching fquncy of th componnt i contant. Whn xtnding th claic DC-SVM chm to th multilvl invt, om modification hav bn mad inc th invt i capabl of gnating mo availabl voltag vcto popotional to it voltag lvl. A. Pha-Shifting SVM Statgy of DC-MLI In th Pha-Shifting SVM (PSSVM) tatgy a popod in [16], a CHMI ha bn mployd. An N-cll cacadd H-bidg multilvl invt (CHMI) gnally ha 2N am vcto p pha with N lft am vcto and N ight am vcto. h output voltag vcto, U, of th invt i dfind a, U i = U Li - U Ri (10) 185

6 31 t July Vol. 41 No JAI & LLS. All ight vd. wh U Li and U Ri a th total lft and ight am voltag vcto of pha i (i = a, b, c) pctivly. A fo th N-cll CHMI, U Li and U Ri a dfind a, U Li = U L1i + U L2i + U L3i +..+ U LNi (11) U Ri = U R1i + U R2i + U R3i +..+ U RNi (12) h vcto U Li and U Ri fo ach cll a gnatd bad on th SVM tatgy of taditional two-lvl invt. hi SVM tatgy dcompo th did gnatd vcto into two vcto with th am amplitud but diffnt pha. By auming th ampling piod of th SVM i, if fou-pat of modulating tatgy i adoptd, th pha hifting tim of ach cll i /N, and if vn-pat of modulating tatgy i adoptd, th pha hifting of ach cll i /2N. h ffcting tim of th lft am o th ight am vcto of ach cll i th am a th ampling tim. hfo th pha hifting tim a mntiond ali i th pha diffnc btwn th H-bidg vcto. o calculat th vcto amplitud, th pha diffnc can b nglctd inc th ampling tim piod i commonly hot. Hnc th amplitud of vy Fig. 6. DC block diagam with PSSVM tatgy vcto can b xpd a, U Li 1 = U Ri U (13) i 2 N Fig. 6 how th block diagam of th PSSVM- DC. B. Nat Voltag Vcto Statgy of DC- MLI h Nat Voltag Vcto tatgy i anoth futh modification of th SVM tchniqu. hi appoach i clo to DC-SVM with clod-loop flux and toqu contol. In thi tatgy, th did voltag that ha bn gnatd by th flux and toqu contoll i ynthizd by chooing th nat voltag vcto that can b dlivd by th multilvl invt. h a two typ of nat voltag vcto tatgy. h fit on i th nat voltag vcto that i dtmind by man of calculating th minimum ditanc of th voltag vcto that can b gnatd by th multilvl invt, which in thi ca th NPC invt i ud. hi tatgy ha bn popod by X. dl oo acia t al [17].h cond tatgy i dtmining th clot o nat voltag lvl intad of th nat voltag vcto. hi tatgy ha bn popod by Kouo t al [18] and an aymmty CHMI ha bn ud. In thi tatgy, th fnc voltag vcto i tanfomd into a th-pha voltag fnc in tim domain uing a th-pha coodinat tanfomation. hn by uing th ound{x} function, wh x i th voltag fnc, th voltag fnc i oundd to th nat intg. In thi ca th nat intg i th nat voltag lvl that can b dlivd by th multilvl invt. 5. PREDICIVE CONROL SRAEY OF DC-MLI A pdictiv contoll i on of th contol algoithm that u th foknowldg of a ytm to pdict th nxt tat of a ytm which i th ocalld on-tp ahad pdiction [19]. In lctical div point of viw, pdictiv contol i bad on th fact that th witching bhavio of an invt can b pdictd. In addition, mathmatical quation can b ud to xp th pon of th div to dtmin a ctain witching tat. Hnc th cacadd tuctu of th contoll in th pviou DC contol chm can b liminatd a all of th maud ytm vaiabl can b conidd in on contoll. hfo th pdictiv contoll off a btt dynamic pfomanc and a btt pntation of a nonlina ytm. h a a numb of pap that pot th application of pdictiv contol in DC with multilvl invt chm. Diffnt pdictiv algoithm hav bn intoducd in mting pcification of ducd toqu ippl and contant witching fquncy. A. DC-MLI with Impod Switching Fquncy Statgy In th litatu, th typ of multilvl invt hav bn ud in DC with Impod 186

7 31 t July Vol. 41 No JAI & LLS. All ight vd. Switching Fquncy tatgy; FCMI [20], CHMI [21], and aymmty/hybid CHMI [22]. In gnal, th witching fquncy impoition tatgy i pfomd by taking into account th intantanou valu of toqu and flux and thi divativ fo th lction of pac vcto. A pdictiv modl i dtmind by diving th timatd valu of toqu and flux, which a calculatd fom th maud valu of IM vaiabl, vu tim. Coniding at th ampling intant, t k, th actual pac vcto poition i Q k. By uing th knowldg θ ' = 2 ( tk + 1). σ. L1L2 ) acin 3 p. Lh 1 ( tk + 1). 2 ( t 12( tk + 1 ' k ) (14) wh 1 and a th tato flux and toqu fnc pctivly; L 1, L 2 and L h a tato, oto, and mutual inductanc pctivly; σ, p, and 2 a lakag facto, numb of pol pai and oto flux fd to th tationay fnc fam pctivly. hu, th output of th dad-bat contoll i obtaind a follow. ( ) = θ ( t ) ( t ) θ (15) + 12 tk 12 k 1 θ12 k By uing th knowldg of a vaiation angl of oto flux, θ 2 a a fd-fowad [23], which can b calculatd by uing a maud valu of th machin, and th lip angl vaiation, th tato flux vaiation angl i dtmind by th following quation. ( ) = θ ( t ) + ( t ) θ (16) 1 tk 12 k θ2 k Fig. 7. nal DC block diagam with impod witching fquncy tatgy on th actual poition, Q k, and alo fom th toqu and flux and thi divativ, th nxt point of th pac vcto poition, Q k+1 can b obtaind. In th am ampling intant, t k th commutation tim t k com that will nu th zo toqu and flux o on th nxt ampling tim i calculatd. h Q k+1 i applid at t k com. Fig. 7 how th gnal block diagam of DC with impod witching fquncy. B. DC-MLI with PI and Dad-bat Contoll h combination of a PI contoll and a dadbat contoll ha bn hown to impov both tady tat and dynamic bhavio of DC-MLI [23]. h diffnc btwn th fnc toqu and th timatd toqu i th input fo th PI contoll to obtain th lip angl vaiation (tato and oto flux angl diffnc), θ 12. A th PI contoll can only off a modat dynamic pfomanc, a dad-bat contoll i mployd to giv a fat dynamic pon. hi i poibl by pdicting th lip angl vaiation uing th valu of th fnc toqu a givn by (14) and ploading th PI contoll pat in th nxt ampling tim. Finally th appopiat tato voltag pac phao can b obtaind by uing th knowldg on th tato flux vaiation angl and th timatd tato flux linkag. hi voltag pac phao thn nd to b ynthizd to witching tat uing a modulato in od to nu th multilvl invt poduc th appopiat voltag output. A in [23], thi pdictiv contol tatgy fo DC ha bn adaptd to th CHMI topology. Hnc th pac phao modulato (SPM) ha bn conidd to ynthiz th voltag pac phao. C. Output Rgulation Subpac (ORS) bad of Switching Contol fo DC-MLI Schm h u of th Output Rgulation Subpac (ORS) concpt which intoduc a hypplan that patition th input pac and a quadatic cition i on of th futh impovmnt of th pdictiv contol concpt. h incopoation of th concpt ha bn hown to ait in th duction of th computational load [24]. Adapting a claical DC chm with th contoll concpt a mntiond ali, avoid th u of look-up tabl, guaant th gulation tak and duc th toqu ippl. In th middl of 2003, thi mthod ha bn adaptd to DC with an NPC invt in lcting th voltag vcto [25]. In thi application, ORS dfin two taight lin that divid th vcto pac (input pac) plan into fou quadant coponding to diffnt combination of ign fo toqu and flux tim divativ. Both 187

8 31 t July Vol. 41 No JAI & LLS. All ight vd. ORS (toqu and flux) a ppndicula and intct ach oth at th oigin. hfo it i found to duc th pac wh th vcto a lctd. In oth wod, th ach of uitabl voltag vcto i tictd to a ctain quadant. Hnc it duc th mathmatical computation whil valuating thm in ngy function. 6. HYBRID MODULAION AND HYBRID INVERER CONFIURAION SRAEY OF DC-MLI h dvlopmnt in th impovmnt of DC pfomanc not only focu on king fo nw olution in th multilvl invt witching contol tatgy but alo in th configuation of th multilvl invt itlf. In [26], a hybid modulation tatgy ha bn popod fo DC with aymmtic CHMI. h DC chm i accomplihd by uing a toqu o (th diffnc btwn th fnc toqu and th timatd toqu) to gnat a fnc load angl, δ, which i ncay to coct th toqu bhavio. hn th did load angl i ud to poduc an appopiat tato flux fnc which i dtmind by, l witching lo in poducing it. Fig. 8 how a hybid modulation opating pincipl fo a 3 cll aymmtic CHMI A popod in [27], a modifid th-pha cacadd of two invt ha bn ud in DC implmntation. Fig. 9 how th configuation of a modifid th-pha invt in cacadd topology. h nw invt topology a in Fig. 9 can poduc a maximum of 9 lvl o 11 lvl of output voltag dpnding on th colation btwn th voltag of iolatd ouc, U d, U d1, U d2, and U d3. Fig. 8. Hybid modulation opating pincipl fo 3 cll aymmtic cacadd multilvl invt co ( δ + θ ) + in ( δ ) (17) = + j θ wh i th tato flux fnc amplitud and θ i th oto flux vcto angl. By ubtacting th tato flux fnc with th timatd tato flux, a vaiation of tato flux ( ) i obtaind. hn th appopiat voltag vcto i dtmind a follow, v (18) h appopiat voltag vcto i thn ynthizd by th hybid modulation tatgy to poduc a witching tat fo th multilvl invt. hi typ of modulation tatgy hlp to duc witching lo and impov th convt fficincy inc th hight pow cll nd only 4 commutation p fnc cycl, which man that th witch tun ON and OFF only onc duing a half cycl. h un-modulatd pat lft by th qua hap of th hight pow cll output i thn modulatd by th nxt pow cll and o on until th final un-modulatd pat of th fnc i modulatd by th mallt pow cll at high witching fquncy uing PWM. hi modulation tatgy thn poduc a multilvl tppd wavfom with a high fquncy componnt but Fig. 9. Modifid th-pha invt Fig. 10. DC ytm fd by modifid multilvl invt block diagam In thi ca, a DC chm i pfomd by uing a 188

9 31 t July Vol. 41 No JAI & LLS. All ight vd. pdictiv modl of IM togth with th flux and toqu timato to obtain an optimal tato voltag vcto a a function of toqu and tato flux, V α opt and V β opt, in α and β plan pctivly. Fom thi optimal voltag vcto, th clot voltag vcto that may b dlivd by th modifid multilvl invt i chon though th witching function algoithm in an invt contol block. Fig. 10 how a DC ytm fd by th modifid multilvl invt a popod in [27]. 7. DC-MLI WIH FUZZY LOIC CONROLLER h mploymnt of Fuzzy Logic Contoll (FLC) in DC ha povidd om impovmnt in toqu and tato flux contol and witching Fig. 12. Hyti Contoll with additional fuzzy contoll Fig. 13. Block diagam fo th DC chm with fuzzy logic contoll Fig. 11. Block diagam fo th DC chm with FLC at th out pd loop fquncy [28]. In th litatu, FLC can b ith addd to on pat of th DC-SVM chm [29] o placing th hyti contoll and th look-up tabl ud in DC-LU [30] fo witching ynthization and nutal-point-voltag balanc inc a 3-lvl NPC invt i ud. A in [31], th FLC i locatd at th out pd loop and om modification ha bn mad in vcto lction uch a intoducing 2 typ of DC with FLC algoithm in on ytm in od to uit it with th SVM mthod. Fig. 11 how th block diagam of th DC chm with FLC at th out pd loop. A in [29], th FLC i addd to both th hyti contoll and th toqu and tato flux. By uing thi modification, th hyti cycl bcom wid. It povid a mo pci lction of th voltag vcto, hnc nhancing th pfomanc of toqu and tato flux contol in a DC and nutal-point-balanc in th NPC invt. Fig. 12 illutat th modification of th DC convntional hyti contoll. Fig. 12 illutat th modification of DC hyti contoll. In [30], th hyti contoll and th look-up tabl ha bn placd by FLC. h witching tat lction w don by FLC. Som modification ha bn mad to th look-up tabl in od to uit it with th FLC ul. By uing thi chm, th DC pfomanc a nhancd in tm of ducing flux and toqu ippl, and hamonic ditotion. Fig. 13 how th block diagam of DC ytm with FLC. 8. CONCLUSION In thi pap, a thotical viw on DC tatgi with multilvl invt fo induction machin ha bn pntd. DC i a viabl altnativ olution to FOC in AC div. It i known to off a impl configuation of DC du to th abnc of coodinat tanfomation block. It i alo capabl of pfoming with both fat toqu pon and hamonic duction. Howv thi claic DC chm ha om diadvantag uch a high toqu ippl, vaiabl witching 189

10 31 t July Vol. 41 No JAI & LLS. All ight vd. fquncy and hamonic lo which a till conidd a high. Adapting DC to multilvl invt i on of th impovmnt that can b mad fo fat toqu pon duing tanint, toqu ippl duction, contant witching fquncy opation and low hamonic lo. hi i bcau a multilvl invt off a naly inuoidal voltag output, low dv/dt, and xta dg of fdom in voltag vcto lction in od to nu th minimization of toqu and flux ippl. DC tatgi with multilvl invt hav bn dividd into fiv goup: witching tabl (look-up tabl) tatgy of DC-MLI, pac vcto modulation tatgy of DC-MLI, pdictiv contol tatgy of DC-MLI, Hybid modulation and hybid invt configuation tatgy of DC- MLI and FLC tatgy of DC-MLI. h baic pincipl, advantag and limitation of ach tatgy ha bn ytmatically pntd. Alo thi latt pog and th application fild hav bn indicatd. A a concluion, it i blivd that th ach on DC tatgy with multilvl invt will continu to dvlop in lin with th continuou ach fo a high pfomanc motionnol AC div fo induction machin. REFRENCES: [1] A. M. zynadlowki, Contol of Induction Moto: Acadmic P, [2] P. Va, Vcto Contol of AC Machin: Oxfod Univity P, Nw Yok, [3] B. K. Bo, Pow Elctonic and AC Div: Pntic-Hall, [4] F. Blachk, "h pincipl of fild ointation a applid to th nw tanvkto clod-loop contol ytm fo otating-fild machin," Adjutabl Spd AC Div Sytm, [5] K. Ha, "Zum dynamichn Vhaltn d Aynchonmachin bi Btib mit vaiabl Standfqunz und Standpannung, ( On th dynamic bhavio of induction machin divn by vaiabl fquncy and vaiabl voltag ouc )," EZ-A, Bd, vol. 89, pp , [6] X. Xu and D. W. Novotny, "Implmntation of dict tato flux ointation contol on a vatil DSP bad ytm," IEEE anaction on Induty Application, vol. 27, pp , [7].. Habtl, F. Pofumo,. iva, M. Patolli, and A. Bttini, "Stato itanc tuning in a tato-flux fild-ointd div uing an intantanou hybid flux timato," IEEE RANS POWER ELECRON, vol. 13, pp , [8] I. akahahi and. Noguchi, "A nw quickpon and high-fficincy contol tatgy of an induction moto," IEEE anaction on Induty Application, pp , [9] M. Dpnbock, "Dict lf-contol(dsc) of invt-fd induction machin," IEEE anaction on Pow Elctonic, vol. 3, pp , [10] J. Rodiguz, J. S. Lai, and F. Z. Png, "Multilvl invt: a uvy of topologi, contol, and application," IEEE anaction on Indutial Elctonic, vol. 49, pp , [11] Z. an, Y. Li, and M. Li, "A dict toqu contol of induction moto bad on th-lvl NPCinvt," [12] R. Zaimddin, L. Rfoufi, and E. M. Bkouk, "An Impovd Dict oqu Contol Statgy fo Induction Moto Div," Intnational Jounal of Elctical and Pow Engining, Mdwll Jounal, vol. 1, pp , [13] M. F. Ecalant, J. C. Vanni, and A. Azand, "Flying capacito multilvl invt and DC moto div application," IEEE anaction on Indutial Elctonic, vol. 49, pp , [14] J. Rod guz, J. Pontt, C. Silva, S. Kouo, and H. Mianda, "A novl dict toqu contol chm fo induction machin with pac vcto modulation," [15].. Habtl, F. Pofumo, M. Patolli, and L. M. olbt, "Dict toqu contol of induction machin uing pac vcto modulation," IEEE anaction on Induty Application, vol. 28, pp , [16] Y. Wang, H. Li, and X. Shi, "Dict oqu Contol with Spac Vcto Modulation fo Induction Moto Fd by Cacadd Multilvl Invt," 2006, pp [17] X. dl oo acia, A. Aia, M.. Jayn, P. A. Witting, V. M. Sala, and J. L. Romal, "Nw DC Contol Schm fo Induction Moto fd with a h-lvl Invt," AUOMAIKA-ZAREB-, vol. 46, p. 73, [18] S. Kouo, R. Bnal, H. Mianda, C. A. Silva, and J. Rodiguz, "High-pfomanc toqu and flux contol fo multilvl invt fd induction moto," IEEE anaction on Pow Elctonic, vol. 22, pp , [19] R. Knnl and A. Lind, "Pdictiv contol of invt upplid lctical div," [20] C. A. Matin, X. Roboam, A. M. hiy, and A. S. Cavalho, "Switching fquncy impoition and ippl duction in DC div by uing a multilvl convt," IEEE anaction on Pow Elctonic, vol. 12, pp , [21] J. Rodíguz, J. Pontt, S. Kouo, and P. Coa, "Dict toqu contol with impod witching fquncy in an 11-lvl cacadd invt," 190

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