VOLT-HERTZ CONTROL OF THE SYNCHRONOUS MOTOR WITH RAMP EXCITING VOLTAGE

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1 nnal of th Unvrty of Craova, Elctrcal Engnrng r, No. 30, 006 VOT-HERTZ CONTRO OF THE SYNCHRONOUS MOTOR WITH RMP EXCITING VOTGE Caba SZBÓ, Mara IMECS, Ioan Iov INCZE Tchncal Unvrty of Clj-Napoca, Dacovc tr. 5, Clj-Napoca 40000, Romana btr Th contant Volt/Hrtz mtho an mprcal f-forwar calar control procr n opn-loop n orr to mantan th rat flx lvl of th C machn nrng th optmal of th rv capablt. Th man rawback of th contant Volt/Hrtz procr cont on th ffct of th voltag rop at low frnc. Th can b lmnat by aoptng ffrnt tchn, for th voltag rop compnaton. Th papr al wth th Voltag-Hrtz control of a alnt-pol ynchrono motor wth varabl, ramp xctng voltag, wth crrnt-fbackba voltag-rop compnaton. Kywor: ynchrono motor, Volt-Hrtz control, varabl xctng fl, voltag-rop compnaton.. INTRODUCTION In varo ntral applcaton, whr no n for hgh ynamcal prformanc (lk pmp, vntlator, tc., for varabl p C rv calar control procr ar. Mot of th lctrcal rv, prnt on th markt, ncl b th vctor control, alo calar control ba tratg. Gnrally, th calar control n rc p-rang applcaton (ω mn /ω max :0. Htorcally th frt lo-l control mtho for th C machn wa th o-call contant Volt/Hrtz control. In ntral applcaton, th Volt/Hrtz control frntly, to t mplcty. Th tator contrcton of th ncton an th ynchrono machn ar th am, conntly th control mtho can b appl wthot any chang for both motor typ. Bca th ynchrono motor oprat at ynchrono p, thr ar no lp-rlat problm to b olv n comparon wth othr motor typ. Th mchancal charrtc (p-tor ar contant, only th loa angl wll b varabl wth rpct to th loa tor mofcaton, whch ha no mportanc n th calar control procr. In ca of th Voltag-Hrtz control, th contant tator-flx opraton obtan mprcally, (no flx ntfcaton rr by an opn-loop fforwar calar control procr, wthot mchancal nor. Th only rfrnc varabl th pply frncy, whl th tator-voltag compt ba on th mplf tay-tat valnt crct of th tator. For a crtan val of th Ω fnamntal frncy of th tator-voltag an m loa tor (whch trmn th magnt of th I tator crrnt, f th xctng fl contant, th rltng tator flx trmn only by U tator voltag. In orr to obtan rat flx val, th tay-tat tatorvoltag aton ha to b flfll: U ( R jω I jω m R I jω σ. ( For th U prcrb val, th mofcaton of th I la to th varaton of th EMF, an conntly to th varaton of th rltant tator flx. In orr to rtor th flx, th tator voltag ha to b ajt. Th varaton of th Ω alo la to th varaton of th EMF, an of th flx, too. Th flx can b rtor only by ajtng th tator voltag n ch a mannr, that t val wll pn trctly on th frncy. From aton ( th EMF can b xpr n vctoral form, a follow: or n calar form: E jω, ( E Ω πf. (3 If th tator flx nrctly controll, thn E π f E π f N N ct. (4.. th mathmatcal form of th contant Volt/Hrtz prncpl. If ( rpct, t nhrntly contan th compnaton wth th voltag rop: Δ R I. By nglctng th tator rtanc, rlt: U. (5 π f From th abov xpron, on can obrv th orgn of th procr nam,.. contant Volt/Hrtz control. Th rol of th control mtho to nr th pnnc of th tator voltag on th frncy. Fg. prnt th block agram of th alnt-pol ynchrono motor rv ytm, ng th contant Volt/Hrtz calar control procr. Conrng th rfrnc frncy f Rf Rf, th amplt U an 89

2 nnal of th Unvrty of Craova, Elctrcal Engnrng r, No. 30, 006 ynchrono anglar p Ω of th tator-voltag vctor compt by man of th V-Hz Control Block block. It prov th npt gnal, whch ar rvng a paramtr for th block 3~ Sn Wav Gnrator. Th block gnrat th molaton gnal of th thr-pha n-wav tator-voltag. Th Voltag-Sorc Invrtr amplf thm an rv th ynchrono motor. Rf f V-Hz Control Block Ω U 3~ Sn-Wav Gnrator Rf a, b, c PWM VSI comptng of th tator-voltag rfrnc prform accorng to th charrtc from Fg. [4], a follow: rm rm Rf rm U N RI Rf U R I f. (7 fn U U N 0V N U 0 Exctng Voltag Control Rf Varabl DC-Voltag Sorc a, b, c f Fgr. Block agram of a alnt-pol ynchrono motor rv ytm, ba on th Volt/Hrtz calar procr ng varabl xctng fl. Th bac arrangmnt ally wthot f-back, bca th orgnal control mtho wa a fforwar on, conntly t ha not rr any fback for th comptaton of th control varabl. Th xctaton wnng f by a varabl DC-pply. Th DC-voltag compt n th Exctng Voltag Control block. In th papr t wll b conr npnnt an pnnt on th compt tator voltag val, rpctvly. In ch a ca th tatorvoltag rfrnc may b compt approxmatly accorng th followng xpron: f Rf U U, (6 N f N whr: U th rat tator voltag, N f th al tator frncy an f t rat val. N Nvrthl, th man rawback of th contant Volt/Hrtz procr cont n th ffct of th tator-voltag rop, whch ca ffclt, pcally at low p opraton. Th voltag rop at low frnc ha th am orr of magnt a th compt voltag an t mak th mtho naat for low p rgon. Th problm can b lmnat by aoptng ffrnt mprovng tchn, lk: programm voltag vr frncy charrtc [3], formla ba voltag-rop compnaton [] or voltag-rop compnaton ng crrnt fback [4], [5]. Nthr of th two mtho tak nto accont th loa ffct. In th thr ca th motor loa takn nto accont by man of th al tator crrnt. That man th f N 50Hz Fgr. Voltag frncy agram for th crrntcompnat Volt/Hrtz mtho. Th varabl lop of th crv to th crrnt pnnt U val an t gvn by th xpron: 0 rm rm U N R I. f N From th control agram t can b obrv that th control law fn o, that all crv cro th motor rat workng pont (0 V / 50 Hz.. CONSTNT VOTGE-HERTZ CONTRO WITH VRIBE EXCITING FIED In ca of th ynchrono motor thr ar om wll known problm rlat to th tartng procr. On of th clacal tartng procr rr an atonal machn, whch to tart th nxct motor. Whn th p rach th rat p, th DC pply connct to th xctng wnng, an th motor wll fall n tp. It rr prfct tmng, for th raon th tartng procr ffclt pcally for hgh powr motor. Mor problm ar ca f th motor loa. Th motor wth mpr wnng (.. al a rrl-cag may b tart n aynchrono mo. In th ca th crrnt n th mpr wnng (hort-crct ampr bar vlop th rr tartng tor for th motor. Th nc voltag at th ynchrono p or nar t wll b zro. t th pont th xctaton ppl wth DC voltag n orr to achv th ynchrono opraton mo. If th motor f by a Statc Frncy Convrtr (SFC, a varabl frncy tartng pobl, o th Voltag-Hrtz procr can b aat. In orr to nr a mooth tartng, varabl xctng fl may b appl, whch magnt alo proportonal to th rfrnc frncy. Th varaton lnar, an t achv th rat val at rat p. Th mtho vlop n orr to mprov th ynamc bhavor of th contant Volt/Hrtz procr. nothr avantag f 90

3 nnal of th Unvrty of Craova, Elctrcal Engnrng r, No. 30, 006 cont n th f that changng th control law, whch compt th xctaton voltag, ffrnt opraton paramtr can b obtan, namly an nrct f-forwar control of th powr for. 3. THE MTHEMTIC MODE OF THE SIENT-POE SYNCHRONOUS MOTOR In orr to prfor m th mlaton of th abov control mtho, th mathmatcal mol of th ynchrono motor an t control ytm ha to b vlop. Th mol xpr n tat-aton c form gnral aton []. Thy ar wrttn n rotor-ornt rfrnc-fram ( θ θ, ng th pac-phaor thory []. In th voltag aton th tat varabl wll b th flx, a follow: θ θ R t θ θ R t R ; t R t R t θ θ ω ω θ θ ; ; 0; 0. (8 Th npt varabl ar th voltag; ω th rotor lctrcal anglar p rltng from th moton aton by th ntgraton. Th otpt varabl - th crrnt can b xpr by man of algbrc xpron pnng on th flx-lnkag: θ θ θ θ θ θ θ m m θ θ θ (9 Whr th nc rfr to th tator, th to th xctaton an to th mpr crct antt. θ an θ ncat th rotor-ornt rct (longtnal an aratr (tranvral varabl, rpctvly. In xpron (9, an ar th tator-, xctng- an mpr-crct nctanc, m th fl nctanc. Th b-trannt rct-ax nctanc: Δ Δ m m m m 3 ( σ Δ σ σ Δ m (0 Th b-trannt rct-ax mtal nctanc ar: θ Δ m σ Δ θ m σ Δ m σ Th b-trannt aratr-ax nctanc ar: m m ( ( Th lat tat-aton obtan from th moton aton: ω z p 3 z p ( θ θ θ θ m t J, (3 whr m th lctromagntc tor, m th loa tor, z th nmbr of th pol par an J th momnt of nrta. p U N f Rf f N N D - R PF U Rf I rm Fgr 3. Smlaton trctr of th V-Hz control. Th trctr of th V-Hz Control Block, ba on xpron (7, hown n th fgr 3. In orr to lmnat lctromagntc prtrbaton, th compnaton trm fltr ng oftwar mplmnt ow Pa Fltr (PF. 4. SIMUTION RESUTS For valaton of th propo voltag-rop compnaton tchn, comptr mlaton wa prform, ng th MTB/Smlnk ynamc mlaton nvronmnt. 9

4 nnal of th Unvrty of Craova, Elctrcal Engnrng r, No. 30, 006 Th nam-plat ata of th alnt-pol ynchrono motor ar: th rat powr P N 800 W, tator frncy f N 50 Hz, tator voltag U N 0 V, rat p n N 500 rpm, tator crrnt N.5, powr for coφ N 0.8 (capv an th nmbr of pol par z p. p-pnnt lnar loa-tor profl appl,.. t val ncra from th motor noloa tor (at zro p to th rat lctromagntc tor (at th rat p corrponng to th tay-tat opraton: ω m ( m N m m gn ( ω, (4 0 ω 0 N whr m N th rat lctromagntc tor, m 0 th no-loa tor. Th motor controll ng th Volt/Hrtz calar control procr, whr th rfrnc frncy ha a ramp varaton profl rng th tartng procr. Th ntal conton wr th followng: th alnt-pol ynchrono motor wth ampr wnng tart wth th xctaton wnng ppl form a DC-voltag orc. Thr wr mlat two ca. In both ca th xctng voltag ha alo a ramp varaton profl. In th frt ca, th xctng voltag rach th mpo val bfor th tator voltag achv h rat val. In th con ca, th xctng voltag ramp trmn o, that wll rach th mpo rfrnc at th am momnt than th tator voltag rach t rat val. It man, that U / U ct. 4.. Crrnt fback-ba compnaton wth ramp-voltag xctaton an U / U ct. Th ntal conton for th mlaton wr: th tartng procr from 0 to 50 Hz.5, whl th xctaton voltag achv th mpo val n. Two ffrnt ca wr mlat, at 0.8 capv fgr 4 to 6 an nty powr for fgr 7 to 9 n tay-tat opraton Rlt for co ϕ Fgr 5. Powr for (coϕ an tator flx r.m.. val ( rm vr tm. Fgr 6. Stator crrnt r.m.. val ( rm an xctaton crrnt ( vr tm From th obtan rlt can b obrv that alo n th ca, whn varabl xctaton appl, th contant Volt/Hrtz control prform wll. Th nrct flx control mantan, howvr, an ovrhot occr rng th tartng procr, whch ca by th voltag-rop compnaton procr. Bca of th, at crtan momnt ovrcompnaton may appar, an for th pro th contant Volt/Hrtz rato lot Rlt for co ϕ 0. 8 Fgr 4. Stator frncy (f Rf rfrnc val, f al val an tor (m lctromagntc, m loa vr tm. Fgr 7. Stator frncy (f Rf rfrnc val, f al val an tor (m lctromagntc an m loa vr tm. 9

5 nnal of th Unvrty of Craova, Elctrcal Engnrng r, No. 30, Rlt for co ϕ Fgr 8. Powr for (coϕ an tator flx r.m.. val ( rm vr tm. Fgr 0. Stator frncy (f Rf rfrnc val, f al val an tor (m lctromagntc an m loa vr tm. Fgr 9. Stator crrnt r.m.. val ( rm an xctaton crrnt ( vr tm Th ntablty rng th tartng procr amplf n ca of capv powr for opraton, whn th xctaton voltag hghr. Bca th xctng voltag varaton ramp fatr than th frncy varaton ramp, th motor ovr-xct. Howvr, n tay tat opraton mo th tablty mantan. In pt of th problm, n om applcaton convnnt f th xctaton voltag varaton ramp fatr, bca t hlp th motor loang capablty. Th tranton from nctv to capv powr for opraton mo alo fatr, whch an avantag f th ynchrono motor a a rv nrgy orc. 4.. Crrnt fback-ba compnaton wth ramp-voltag xctaton an U / U ct. Th rato btwn th tator an xctng voltag kpt contant, n th am mannr a th contant Volt/Hrtz rato. Th varaton ramp compt o, that th xctng voltag rach th mpo val whn th tator voltag at th rat val, n or ca. Th am ca wr mlat a n cton 4.. Fgr. Powr for (coϕ an tator flx r.m.. val ( rm vr tm. Fgr. Stator crrnt r.m.. val ( rm an xctaton crrnt ( vr tm In comparon wth th prvo mlaton from cton 4. t can b obrv, that th bhavor of th ynchrono machn n trannt opraton mo mprov. 93

6 nnal of th Unvrty of Craova, Elctrcal Engnrng r, No. 30, Rlt for co ϕ 0. 8 control mtho mprov. In ca of th ynchrono machn, hghr rv prformanc can b obtan f varabl xctng crrnt appl nta of a contant on [7], [8]. In th papr, a ramp-typ voltag form wa appl for th motor tartng procr. ccorng to th pcfc applcaton, th lop of th xctng voltagramp can b ffrnt from that of th varaton ramp of th compt tator-voltag. Howvr, th bt rlt wr obtan f th rato btwn th two voltag kpt contant rng th tartng procr. Rfrnc Fgr 8. Stator frncy (f Rf rfrnc val, f al val an tor (m lctromagntc an m loa vr tm. Fgr 9. Powr for (coϕ an tator flx r.m.. val ( rm vr tm. Fgr 0. Stator crrnt r.m.. val ( rm an xctaton crrnt ( vr tm. For th partclar ca, f th contant rato btwn th tator- an xctaton-voltag mantan, th mlaton rlt how that t nr optmal workng conton for th ynchrono motor. Th tor rppl ar conrably rc, th flx control bttr, an th lvl of th aborb tatorcrrnt rc. 5. CONCUSIONS Wth crrnt-fback ba voltag-rop compnaton th clacal contant Volt/Hrtz calar []. Klmn, Mara Imc: Vctor Control of C Drv. Volm : Vctor Control of Synchrono Machn Drv. Bapt, Ecrtr, 993, ISBN []. Klmn: Elctrcal Drv (ctonar Elctrc, n Romanan, Etra Dca Pagogca, Bchart. [3]. bbonant: Mtho of flx control n ncton motor rvn by varabl frncy, varabl voltag ppl, Rprnt from IEEE IS nnal Mtng. pp [4] M. Imc, C. Szabo: Control Strctr of ncton motor rv Stat-of-th-art, Proc. of 4 th Workhop on Eropan Scntfc an Intral Collaboraton WESIC vanc Tchnolog n Manfrng, Mkolc- llafür, ISBN: , pp [5] I. I. Incz, Mara Imc, C. Szabo: Smpl Voltag-Hrtz control wth crrnt fback of th ncton machn, Proc. of 004 IEEE-TTTC QTR 004 THET 4, Clj-Napoca, ISBN , Tom I, pp [6]. Mnoz-Garca, T..po, D. W. Novotny: nw ncton motor V/f control mtho capabl of hgh-prformanc rglaton at low p, IEEE Tranon on Intry pplcaton, Vol.34, No.4, Jly/gt, pp [7] C. Szabó, Mara Imc, I. I. Incz: Smpl Voltag-Hrtz control wth crrnt-fback of th ynchrono machn wth contant xctaton, Procng of th 7 th Intrnatonal Carpathan Control Confrnc ICCC 006, Otrava, Czch Rpblc, on CD an n pr. [8] C. Szabó, I. I. Incz, Mara Imc: Voltag-Hrtz control of th ynchrono machn wth varabl xctaton, IEEE-TTTC Intrnatonal Confrnc on tomaton, Qalty an Ttng, Robotc. QTR 006 (THET 5, Clj-Napoca, Romana, May 5-8, Tom I, pp [9] D. W. Novotny, T.. po: Vctor Control an Dynamc of C Drv. Clarnon Pr, Oxfor, 997, ISBN [0] P. Va: Vctor Control of C Machn. Oxfor, Clarnon Pr,