Sensorless Control of Surface Permanent Magnet Synchronous Motor with A Self-Adaptive Flux Obserber

Transcription

1 7th WSEAS Int. Conf. on MATHEMATICAL METHODS an COMPUTATIONAL TECHNIQUES IN ELECTRICAL ENGINEERING, Sofia, 27-29/10/05 (pp63-68) Senole Contol of Suface Pemanent Magnet Synchonou Moto with A Self-Aaptive Flux Obebe SONG ZHENGQIANG HOU ZHIJIAN JIANG CHUANWEN Shanghai Jiaotong Univeity Infomation an Electical Engineeing Shanghai CHINA Abtact: - In thi pape, a new appoach to enole pee contol an initial oto poition etimation fo a uface pemanent magnet ynchonou moto (SPMSM) ive i peente. At a otating conition, pee an oto poition etimation of SPMSM ive i obtaine on-line though a elf-aaptive flux obeve (SAO) by only meauing phae voltage an cuent. When SPMSM i on tantill, the initial oto poition i pefome off-line by uing the nonlinea magnetization chaacteitic of the tato coe which i caue by the oto magnet. Expeimental eult how that in both teay an tanient tate, the ytem can all achieve expecte pefomance. Key-Wo-pemanent magnet ynchonou moto; enole contol; DSP; aaptive contol 1 Intouction Since1980, AC evo moto, epecially pemanent magnet ynchonou moto (PMSM) ha been eceiving inceae attention in inuty application becaue of thei high toue to inetia atio, upeio powe enity an high efficiency. A pee contolle of evo moto i vey impotant fo the pefomance impovement of mechanic evo ytem applying to the inuty application uch a machine tool, X-Y table, obotic an o on. A poition eno uch a an encoe o a eolve i euie in a PMSM in oe to ynchonize the phae excitation pule to the oto poition. Howeve, in many inutial intallation, thee ae peence of the ive cot, eliability, machine ize an noie immunity an cannot be mounte in a hotile envionment. Then, thee ha been an inceae inteet in eliminating the nee fo the oto-mounte mechanical eno. Many metho have been peente in the liteatue fo etecting the oto poition of iffeent clae of PMSM [1-14]. Mot of them have been evelope fo the IPMSM (Inteio Pemanent Magnet Synchonou Moto), becaue the inuctance vaiation in the an axe coul be monitoe eaily to etect the oto poition [3,4] incluing INFORM metho peente by M.Schoel. Thee poition enole contol cheme have a fine pee an poition contol pefomance without poition eno fo IPMSM. On the contay, fo SPMSM (Suface Pemanent Synchonou Magnet), it i ifficult to contol a moto pee accuately, epecially, on conition that an angula oto pee become a zeo an/o a low pee. The ifficulty with the uface-mounte oto i the eual inuctance along both an axe, o many metho applying in IPMSM ae ineffective fo SPMSM without getting the vaiation between an axe. In aition, SPMSM ha moe avantage than IPMSM uch a lowe cot, imple mechanic tuctue in inuty application [7]. A a eult, the eeach of enole contol fo SPMSM i geatly ignificant. Fo SPMSM, liteatue concentate on thee main iffeent aea: 1- back electomotive foce (BEMF) bae techniue. 2- techniue bae on the machine' phyical popetie. 3- tate obeve an Extene Kalman Filte (EKF). In ega to the fit techniue, [8] an [9] have emontate enole moto tating an velocity loop contol uing the BEMF metho. The velocity ignal coul be integate to geneate a poition etimate. Howeve, thi ignal i enitive to paamete vaiation an ten to ift an have offet poblem. Anothe poblem with BEMF to etimate poition i that at zeo pee the BEMF goe to zeo. Even at low pee the ignal-to-noie atio can t be ignoe. [10] ae an obeve of tato eitance vaiation to eceae the negative effect of tato eitance vaiation, howeve, tato eitance of SPMSM i effecte many facto of envionment, then it i ifficult to etimate the eitance vaiation on-line accuately an can not etimate the oto initial poition when moto i in tantill conition. Some eeache have evelope obeve uing the

2 7th WSEAS Int. Conf. on MATHEMATICAL METHODS an COMPUTATIONAL TECHNIQUES IN ELECTRICAL ENGINEERING, Sofia, 27-29/10/05 (pp63-68) moto moel [11]. A uitable eign of the obeve pouce a high level of inenitivity to paamete vaiation; but, the obeve ae enitive to the meauement noie an thei tability analyi i ifficult. Alo Kalman filte bae obeve ue the moto mathematical moel. They ae ieally uite to etimate oto pee an poition, an eject meauement noie. Unfotunately, tuning of covaiance matice of the moel an meauement eo i ough an euie kille opeato. Moeove the Kalman filte bae algoithm ae computationally intenive an time conuming. In the lat ecae many eeach effot have been caie out to apply liing-moe techniue to contol of inuction moto an pemanent magnet moto. Thee techniue have been invetigate becaue of thei known obutne popetie with epect to paamete uncetaintie. The negative apect of liing moe i the icontinuou natue of the contol action. Uually, it i 10% of ate pee to full one that mot of enole contol metho fo SPMSM i vali[12]. In aitional, the above ecibe metho o not give poition infomation at tantill. A a coneuence, the SPMSM ha to be fit tate in opene-loop with an abitay witching an bought up to a pee high enough to pemit one to etect voltage component. Thi appoach i not eliable in many application becaue it oe not neceaily lea to mooth tating in the ight iection. Altenatively the PMSM can be tate afte an aligning poceue to place the oto in the iection of a phae wining. It i alo poible to etimate oto poition by etecting the voltage efeence ocillation phenomena caue by magnetic atuation [13]. Recently a new zeo-pee enole contol techniue, bae on the injection of a high-feuency tato voltage component an emoulation of the tato cuent, ha been popoe to etimate the oto poition by exploiting the magnetic aniotopy of altenate-cuent moto [14]. The SPMSM ha a vey low level of aniotopy o that the oto poition ientification, uing thi techniue, i ha. In concluion, thee till have ome poblem a low pee unning an oto poition etimation at tantill in the fiel of enole contol of SPMSM. In thi pape, a new cheme fo oto initial poition etimation of SPMSM, voltage pule vecto metho (VPVM) i intouce auming ieal cylinical behavio ( X = X ). The etimation i pefome by the nonlinea magnetization chaacteitic of the tato coe caue by the magnet of the oto. Thi metho i bae on the pinciple that the X-axi cuent value ue to the voltage vecto applie to the moto une magnet atuation conition inceae a the voltage vecto geneate fom the invete appoache the N pole of the oto. Futhemoe, cloe-loop contolle toue tat-up i popoe uing a elf-aaptive flux obeve (SAO), which allow the tat-up moothly in evee tating conition becaue oto initial poition i known in avance an low unning i teaily at 5 /min of ating pee. 2 Methematical Moel of SPMSM A pace vecto iagam of SPMSM i hown in Fig.1. The voltage euation in - efeence fame ae axi axi θ axi axi Fig.1. Definition of axe efeence ytem u u = 0 0 i i p ω The flux linkage ae efine a, L = 0 i L i 0 m 0 ω p. (1). (2) 3 Stuctual Aaptive Obeve The tato voltage euation i given in the tato efeence fame, v = i (3) t The tato flux linkage euation in the tato fame i given by, = Li Lmi e. (4) Whee i flux linkage of tato, L i inuctance of tato, L m i the inuctance of pemanent magnet, i i the euivalent oto cuent θ i the oto angle. Subtitute the flux linkage 4 into 3, v ( i = Li Lmie ) (5) t an obeve that L i = φ, m φ i the oto flux. We get,

3 7th WSEAS Int. Conf. on MATHEMATICAL METHODS an COMPUTATIONAL TECHNIQUES IN ELECTRICAL ENGINEERING, Sofia, 27-29/10/05 (pp63-68) v i = ( Li φ e ). (6) t Integating the left ie of (6) yiel, = ( v i ) t = Li φ e. (7) Expeing the lat tem in the paenthei fom (6) on component (the eal an imaginay pat), φ e = φ co θ jφ in θ = φ jφ. (8) an plit the (7) in eal an imaginay component, olving the euation fo, φ = ( V i ) t Li = L i (9) φ = ( V i ) t Li = L i. (10) Then, the oto angle in tem of the obeve flux i, φ θ = actan. (11) φ Simulation an pactical expeiment ae mae to analyze the behavio of thi poition obeve. Thi obeve i an ieal integato without any offet compenation. Due to mall DC offet which invaiably exit in any pactical implementation, an ieal integato will alway ift. In flux linkage obevation, the ieal integato ( 1 )i geneally eplace by applying fit oe inetia filte τ /( 1 τ). Fom the expeion of the fit oe filte, it can be een that the filte can be euivalent to an ieal integato when ω f f 1/ τ an that it make the initial ignal behave amply with time when ω appoximate to 1 / τ. A hown in Fig.2, τ = 0.01, the output ignal ha a DC ift. Howeve, a hown in Fig.3 the fit oe filte amp DC component in the output ignal uickly. Applying fit oe filte inepenently ha no acce to accuate obevation of oto pee an poition in the entie pee egulating ange becaue of the vaiable velocity. Theefoe, thi pape peent a kin of elf-aaptive obeve which can automatically ajut the compenation uantity accoing to the vaiou feuency of input ignal. Fig 4 illutate it tuctue. The inputte BEMF i tanfome fom ABC-thee phae tationay efeence fame to -two phae tationay efeence fame. The flux linkage component in the efeence fame ae eive fom the integation of BEMF. The inepenent contol of the magnitue an phae of flux linkage can be implemente by tanfoming it fom the ectangula cooinate to pola cooinate fame. Hee, the eo ignal which i pouce afte flux linkage magnitue an BEMF pa the uaatue-compaato, i ae to the flux linkage a the fee back uantity. Alo, the magnitue of eo ignal i ecie by (12). cmp k emf emf i = ( k p ) (12) cmp i the magnitue of eo ignal, emf i BEMF of tato, w = 1/ τ. c Fig.2. Flux linkage cuve uing ieal integato Fig.3. Flux linkage cuve uing fit oe filte 1 ω c 1 ω c ωc ω c ωc ω c fom XY to θρ amp. emf. emf PI e to XY fom Fig.4. The tuctue of elf-aaptive obeve 4 Etimation Metho of Roto Initial Poition The etimation i pefome by the nonlinea magnetization chaacteitic of the tato ion coe caue by the magnet of the oto. Thi metho i fitly peente by Pete.B [20]. The etimation theoy i bae on the pinciple that the X-axi cuent value fo the voltage vecto applie to the moto une magnet atuation conition inceae a the voltage vecto geneate fom the invete appoache the N pole of the oto. Howeve, pete. B only bought about a baic theoy without expeiment in pactical application. What moe, imulation eult in [20] wee complete within the aumption that oto angle θ i vey little, then co (2θ ) = 1, in (2θ ) = 0. In fact, it i unealitic. θρ

4 7th WSEAS Int. Conf. on MATHEMATICAL METHODS an COMPUTATIONAL TECHNIQUES IN ELECTRICAL ENGINEERING, Sofia, 27-29/10/05 (pp63-68) [21] put thi metho into pactice fitly. It i eget that it i not effective fo any SPMSM, becaue not all magnetization cuve of SPMSM ae ame an iffeent voltage pule ae neee fo iffeent SPMSM. In thi pape, a geneal oto initial poition etimation metho, namely VPVM which can automatically efine the magnitue of voltage pule that can bing about magnet atuation of tato ion coe. Duing etimation poce, the oto i pactically at tantill. Thi pat i complete with off-line etimation poceue. Fig.5 how the voltage vecto of SPMSM. X i the voltage vecto applie to the tato, an θ v i the angle between the voltage vecto an a-axi. Fig. 6 how the tato cuent a a function of oto poition. The peak cuent value ae appoximately the ate. Cuent value of the moto i 45 amp. Thee plot emontate the atuation effect of the tato ion a explaine with Fig.6. The etimate electical angle that i calculate uing thi voltage pule techniue i plotte a a function of the actual mechanical oto angle an i hown in Fig.8. The actual oto angle i meaue uing a feeback eolve attache to the moto haft an i hown fo compaion. The eo between the calculate angle an actual angle i foun to be vey mall angle iffeence in each egion. Fig.9 how the pee cuve of ytem with SAO an a tantill initial poition. Fig.10 i oto poition cuve when the moto i unning. N pole X θ v Fig.5. Voltage vecto Fig.7. Mechanical oto poition Fig.6. Change ate of tato cuent a a function of oto poition when the coil a flux to the flux pouce by the oto magnet. When a noth pole i aligne with the coil, the cuent in the coil inceae a the tato atuation inceae. When a outh pole i aligne with the coil, the cuent in the coil eceae a tato atuation eceae. Since the cuent of the coil i iffeent fo noth an outh pole, one can itinguih the polaity of the oto pole that i aligne with the coil, then the poition of oto can be known. The 6 eie of voltage pule ae applie to a 6 pole SPMSM an the coeponing peak cuent value meaue an plotte a hown in Fig.7. Thee meauement ae taken at zeo pee at each of the poition a the moto i mechanically otate fom one poition to the next. Fig.8. Initial poition of oto Fig.9. Spee cuve of ytem

5 7th WSEAS Int. Conf. on MATHEMATICAL METHODS an COMPUTATIONAL TECHNIQUES IN ELECTRICAL ENGINEERING, Sofia, 27-29/10/05 (pp63-68) Fig.10. Roto poition 5 Expeimental Reult Expeimental eult ae obtaine uing a 6-pole uface PMSM evo ive (ee Table 1): Table 1 Technical ata of SPMSM Fig.12. A phae cuent cuve at 1000pm/min Rate powe Rate pee Rate voltage 1.2kW 6000pm 400V Fig.13. Spee cuve at 5pm/min Rate cuent 2.8A A fixe-point igital ignal poceo (DSP), TMS320F240, i ue to un the vecto contol algoithm. The contol an etimation peio i µ. The PWM witching feuency fo inulate gate bipola tanito i 15kHz. The DSP alo un the poition etimation algoithm. At fit, an initial oto poition etimate will be applie into the elf-aaptive integato, then the moto begin to un. Fig.11 how the pee cuve when the moto i unning at 1000pm. At the ame time, the A phae cuent cuve i peente a Fig.12. In oe to tet the function of thi enole contol metho in the conition of lowe pee, the moto i contolle by unning at 5pm/min. The expeimental eult ae hown in Fig.13 (Spee cuve) an Fig.14 (A phae cuent cuve). Fig.11. Spee cuve at 1000pm/min Fig.14. A phae cuent cuve at 5pm/min 6 Concluion The SAO i the type of poition obeve popoe. With the euie conition atifie (initial poition can be meaue exactly), it i emontate that thi obeve povie eliable poition infomation fo a contolle toue, cloe-loop tat-up. The peente wok emontate that the meaue teminal cuent an voltage, togethe with the machine paamete, can be ue to obtain a contolle tat-up of the SPMSM une evee conition. The metho can be employe in ive ytem with SPMSM, o any type of SM, which euie a contolle toue tat-up une high loa uing the ate cuent, which eliminate the poblem of eigning an oveate invete to povie high cuent uing tat-up.

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