The Finite Element Analysis of Magnetic Field of the Hybrid Excitation Linear Synchronous Motor with Permanent Magnet and Electric Excitation

Transcription

1 The Fte Eleet Aalyss of Magetc Feld of the Hybrd Exctato Lear Sychroous Motor wth Peraet Maget ad Electrc Exctato (*)Huag Mgxg, (**)Ye Yuyue, Che Xua (*)(**)College of Electrcal Egeerg Zhejag Uversty, Hagzhou, Zhejag Provce 30027, P.R.Cha Tel. (057) E-al Author Iforato: Huag Mgxg (976- ), aster graduate studet, the research doa s lear otor ad ts cotrol. Keywords Electroagetc feld Fte eleet aalyss Hybrd exctato Lear sychroous otor Abstract Ths paper troduces the structure ad characterstc of two ovel kds of hybrd exctato lear sychroous otor wth peraet aget ad electrc exctato-alterat hybrd exctato ad eve hybrd exctato lear sychroous otor. The ar-gap agetc feld of the s aalyzed wth ANSYS8. software package. The results of the dstrbuto of agetc feld ad the electroagetc propulsve force uder the dfferet exctg curret are gve. The the advatage ad dsadvatage of the two kds of exctato are copared. I the ed, we copare the theoretcal results wth the experetal results of the actual odels. Itroducto Whe the brad, sze ad dosage of the peraet aget of lear sychroous otor wth peraet aget exctato are chose, ts exctato syste s as well as ascertaed. So we ca't adjust the testy of exctato agetc feld accordg to actual eed, whch akes the applcato of the otor coveet. Ths s a proble. The hybrd exctato lear sychroous otor s brought forward to solve the proble. The so-called hybrd exctato lear sychroous otor eas that the secodary pole of lear sychroous otor, besdes peraet aget exctato, electrc exctato wdg geerates agetc flux also, both of the sytheszg ar-gap. Whle the aout of exctg curret s adjusted, the testy of ar-gap agetc feld ca be cotrolled. The advatage of the hybrd exctato lear sychroous otor s that t s brushless, the testy of agetc feld ca be adjusted, ad t s easy to cotrol agetc feld. There are two kds of structural desg schee. The frst oe s that exctato wdg ad peraet aget are placed alterately (as show Fg.-a). The secod oe s that there are both peraet aget exctato ad electrc exctato every secodary pole, both of whch geerate agetc flux the ar-gap (as show Fg.-b). 877

2 a) Alterat hybrd exctato b) Eve hybrd exctato. prary core 2. prary wdg 3.secodary wdg 4. peraet aget 5. secodary core 2 Fte eleet aalyss Fg.. Structure sketch ap of two kds of hybrd exctato The suspeso ad propulso are realzed by ar-gap agetc feld the hybrd exctato lear sychroous otor wth peraet aget ad electrc exctato. So t s very portat for aalyzg the perforace of otor to aster the dstrbuto of the ar-gap agetc feld. To splfy the calculato, the agetc crcut ethod (MCM) was ostly adopted to solve egeerg probles the past. MCM eas that the exstg ueve agetc feld s coverted to equvalet ultple agetc crcuts, where agetc flux s deeed as evely dstrbutg alog every secto ad drecto each agetc crcut. By that ethod, we ca covert the calculato of agetc feld to the calculato of agetc crcuts. The, by the troducto of soe aedatory coeffcets, the agetc dfferece of potetal of each equvalet agetc crcut becoes the sae as that of correspodg locatos agetc feld [2]. Although MCM s effectve to deal wth soe geeral egeerg desg probles, t s t so satsfactory whe hgh precso s requred, whch calls for ore precse ethod. Wth the assace of coputer the ddle perod of last cetury, the so-called fte eleet ethod (FEM) was brought forward for the hghest precso ad effcecy the doas of coputatoal atheatcs, coputatoal echacs, ad coputatoal egeerg. FEM s a ethod that coverts the boudary value proble of partal dfferetal equato to the dscretzato varatoal proble(.e. fuctoal extree value proble) to obta the uerc soluto [4]. Wth FEM appled wdely ay egeerg doas, ay kds of FEM software package coe out. Aog those, ANSYS s a qute successful oe, whch cludes oe EMAG odule havg powerful 878

3 fucto to aalyze low frequecy electroagetc feld. Thereafter, we wll apply ANSYS8. to aalyze the dstrbuto of ar-gap agetc feld ad the agetc propulsve force of the hybrd exctato lear sychroous otor. 2. Aalyss of the ar-gap agetc feld Because the otor has these characterstcs as the trasversal legth of otor s far bgger tha the legth of ar-gap, the prary wdg s three phase ass wdg, the ed of wdg s shorter, ad all ro cores are laato, t ca be ade for soe splfed hypothess as follows. a. The dstrbuto of agetc feld ca be regarded as syetrcal the axs drecto. The curret desty vector J r ad the agetc vector potetal A r have oly the part of the axs drecto,.e. J = J z, A = Az. b. The agetc feld outsde the shell of otor ca be gored. Thus, the outward surfaces of the prary ad secodary ca approxately be regarded as a equvalet agetc potetal surface wth zero vector value. c. The dstrbuto of curret desty coductor s supposed to be syetrcal. d. It ca be assued that the agetc pereablty of ro core s sotropc. At the sae te the hysteress effect ad the eddy curret effect are otted. Based o the foregog hypothess, we adopt a two-deso odel to aalyze the dstrbuto of agetc feld. The paraeters of odel are show Table.. They are also the paraeters of prototype ache [5]. Overall legth of prary 5520 Noal voltage 380V Prary pole spa 45 Noal curret 3.8A Legth of ar-gap 5 Noal frequecy 50Hz Ptch of prary wdg 45 Nuber of secodary pole 6 Type of prary wdg Tur uber of prary wdg Wre daeter of prary wdg Equvalet heght of prary slot Three phase, Moolayer, Cha, Y coecto Legth of secodary pole Heght of secodary pole Heght of secodary yoke Tur uber of secodary wdg Breadth of prary slot Wre daeter of secodary wdg Breadth of prary tooth 4 Noal exctg curret of secodary wdg Thckess of prary stack 50 Brad of peraet aget N35SH 2.8A Heght of prary yoke 35 Sze of peraet aget Table.. Paraeters of the hybrd exctato lear sychroous otor 879

4 The peraet aget wll be calculated as a curret source. After the drecto of chargg agets, the relatve pereablty µ r, ad the coercve force H c of peraet aget are gve the otor odel, ANSYS software wll work out the equvalet surface curret desty. Hereo, we aalyze the odel of otor whe the secodary q axs superposes the phase a o the rated state. The the trphase curret value of the prary wdg are respectvely a = 2I N = = A, 2 b = c = - 2 I = A. Whe the secodary exctg N curret I f s respectvely -3.2/-.5/0/.5/3.2A, we aalyze the two deso dstrbuto of agetc feld of the eve hybrd exctato ad alterat hybrd exctato lear sychroous otor wth the ethod of statc feld aalyss. The charts of agetc les of flux are show Fg.2 ad Fg.3. a) I f =-3.2A a) I f =-3.2A b) I f =-.5A b) I f =-.5A c) I f =0A c) I f =0A d) I f =.5A d) I f =.5A Fg.2. Charts of agetc les of flux of the eve Fg.3. Charts of agetc les of flux of the hybrd exctato lear sychroous otor uder alterat hybrd exctato lear sychroous the dfferet exctg curret I f otor uder the dfferet exctg curret I f 880

5 (Cotued) e) I f =3.2A e) I f =3.2A Fg.2. Charts of agetc les of flux of the eve hybrd exctato lear sychroous otor uder the dfferet exctg curret I f Fg.3. Charts of agetc les of flux of the alterat hybrd exctato lear sychroous otor uder the dfferet exctg curret I f As show the above charts of agetc les of flux, the agetc flux desty of every couple poles of the eve hybrd exctato lear sychroous otor boosts up gradually, wth chagg the exctg curret fro egatve value to postve value. However the agetc flux of electrc exctato pole of the alterat hybrd exctato lear sychroous otor chages drecto fro beg reverse to the agetc flux drecto of peraet aget pole to beg sae to that, so the agetc flux desty of peraet aget pole wll vary fro beg weakeed to beg tesfed. As show Fg.3, the agetc flux desty of electrc exctato pole s approxatvely equvalet a) ad e), lkewse b) ad d), but the agetc flux drecto of the s cotrary. I Fg.3-c), the agetc flux desty of electrc exctato pole s alost zero. Coparg Fg.2 wth Fg.3, t ca be cocluded that the eve hybrd exctato lear sychroous otor has ore syetrcal dstrbuto of agetc feld tha the alterat hybrd exctato lear sychroous otor. Ad the ar-gap agetc flux desty of the forer s hgher tha that of the latter uder the sae exctg curret. 2.2 Aalyss of electroagetc propulsve force The electroagetc propulsve force s a portat perforace dex of the hybrd exctato lear sychroous otor. I electroagetc theory, there are two kds of ethod to calculate electroagetc force,.e. the ethod of Maxwell s stress tesor ad the ethod of vrtual dsplaceet [3] Method of Maxwell s stress tesor Accordg to Maxwell's opo, the volue force whch acts o ay area of a edu ca be deduced to the tesle force actg o surface of the area. If the agetc pereablty of two kds of edu are µ a ad µ b, the force actg o object surface the agetc feld s b - a 2 2 F = ( B + a bht ) () 2 a b The drecto of force s fro the edu wth bgger agetc pereablty to the edu wth saller agetc pereablty. If two kds of edu are respectvely ferroagetc ateral ad ar, the expresso of the force s F = B + B H (2) ( 2 0 ) 2 r - r t t r 0 Ad the drecto of force s always fro ferroagetc ateral to ar. 88

6 2.2.2 Method of vrtual dsplaceet It s a ethod to solve the electroagetc force. Its theoretcal bass s that the vrtual dsplaceet of the secodary begets the chage of every ut of agetc feld. If the electroechacal couplg syste s cosdered as a o-loss coservatve syste, agetc power storage W s a state fucto of the coservatve syste, flux lkage Ψ ad dsplaceet x are depedet varable of the syste, the W = dψ = W Ψ 0 ( Ψ, Ψ, LΨ ; x, x, Lx Supposed that a terval dt, No. k of coupled crcuts takes place a vrtual dsplaceet dx k, ad the others are oble, accordg to the coservato of eergy prcple, there s dw Ω = dw + dw e (4) I the above equato, dw W ad dw e s respectvely dw Ω = F k dx k (5) dψ dwe = edt = dt = dψ (6) = = dt = Accordg to equato (4), (5), ad (6), t ca be deduced that dw = F dx k k 2 = 2 ) (3) dψ (7) Ad fro equato (3), ca deduce that W W dw = dxk + dψ (8) xk = Ψ Couplg equato (7) ad (8), the force actg o the object the agetc fled s W (Ψ, x) Fk = (9) xk ANSYS software package ca autoatcally work out the electroagetc propulsve force wth above two kds of ethod. Table.2 ad Table.3 lst the results of the electroagetc propulsve force of two kds of hybrd exctato lear sychroous otor uder the dfferet exctg curret. Fg.4 s the graph of propulsve force ad exctg curret s relatoshp. Exctg curret I f /A Electroagetc propulsve force F Electroagetc propulsve force F (Method of vrtual dsplaceet)/n (Method of Maxwell s stress tesor)/n Table.2. Values of propulsve force of eve hybrd exctato lear sychroous otor 882

7 Exctg curret I f /A Electroagetc propulsve force F Electroagetc propulsve force F (Method of vrtual dsplaceet)/n (Method of Maxwell s stress tesor)/n Table.3. Values of propulsve force of alterat hybrd exctato lear sychroous otor Fg.4. Coparso of calculated propulsve force of two kds of hybrd exctato lear sychroous otor As show the above graph, there s a fxed dfferece of propulsve force that s respectvely worked out wth two kds of ethod. The electroagetc propulsve force worked out wth the ethod of vrtual dsplaceet s bgger tha that wth the ethod of Maxwell s stress tesor. It s related to the precso of parttog odel s esh. After provg the partto precso, the dfferece of propulsve force wll reduce. 3 Experetal results of the prototype ache A experetal prototype ache about 6-eters log has bee ade the lear electrc ache sttute of Zhejag Uversty. I addto two secodary cars wth eve hybrd exctato ad alterat hybrd exctato structure respectvely have bee ade also. The prototype ache s cossted of 30 otors ad dvded to 3 segets for respectvely curret supplyg. Its paraeters are show Table.. Whe the prototype ache s tested, we adopt the eas of statc force sulatg dyac force. Trphase syetrcal AC s coducted the prary wdg. The travelg wave feld of arature s ovg wth sychroous speed, whle the exctg feld s oble. Therefore, a pull teso gauge fxed o the secodary car ca easure the propulsve force [6]. I order to easurg the regulato fucto of exctg curret to the ar-gap agetc feld, we 883

8 chage the secodary exctg curret I f fro egatve value to postve value, ad acqure a seres of experetal data of propulsve force F o codto that prary power supply frequecy f s respectvely 5Hz, 25Hz, &50Hz (as show Table.4). I Table.4, the egatve curret value eas that the agetc flux geerated by electrc exctato couteract the oe by peraet aget, cotrarwse the postve value eas tesfyg. F deotes the propulsve force of the car wth eve hybrd exctato structure, ad F2 deotes the propulsve force of the car wth alterat hybrd exctato structure. The graph of propulsve force ad exctg curret s relatoshp s Fg.5. f I f /A Hz F /N F 2 /N Hz F /N F 2 /N Hz F /N F 2 /N Table.4. Electroagetc propulsve force F uder the dfferet exctg curret I f a) f=5hz b) f=25hz c) f=50hz Fg.5. Coparso of experetal propulsve force of two kds of hybrd exctato lear sychroous otor 884

9 4 Cocluso O oe had the ar-gap of prototype ache s asyetrc, o the other had the precso of easurg apparatus s lower, so there s a error betwee the experetal outcoe ad the theoretcal aalyss outcoe. But coparg the data Table.2, Table.3, ad Table.4, t ca be deduced that the theoretcal aalyss outcoe s approxately equvalet to the experetal outcoe as prary power supply frequecy beg 50Hz. It s because the foregog fte eleet aalyss s o codto that the secodary q axs superposes the phase a o the rated state. Ths valdates that the odel ad calculated outcoe are accurate the foregog fte eleet aalyss. The advatage of alterat hybrd exctato s that the structure eeds oly to chage the half structure of geeral peraet aget lear sychroous otor, but the dstrbuto of ts agetc feld s asyetrc. Whe the eve hybrd exctato lear sychroous otor s o stable operato, there s o curret the electrc exctato wdg, ad oly the agetc feld geerated by peraet aget provdes the ecessary electroagetc propulsve force for otor rug. The electrc exctato wdg offers adjustet to the ar-gap agetc flux. Oly uder soe specal crcustaces such as startg, stoppg, ad sudde accelerato ad decelerato, the curret s coducted electrc exctato wdg. Accordg to the foregog coputer sulato aalyss ad experet, t ca be cocluded that the eve hybrd exctato lear sychroous otor has ay advatages over the alterat hybrd exctato lear sychroous otor, such as ore coveet adjustet to the ar-gap agetc feld, ore syetrcal dstrbuto of the agetc feld, stroger propulsve force, ad better perforace. Refereces. Ye Yuyue. The Theory ad Applcato of Lear Motor, Cha Mache Press, Bejg 00037, PRC, Tag Reyua, etc. The Theory ad Desg of Moder Peraet Maget Motor, Cha Mache Press, Bejg 00037, PRC, Zhag Mgtao, Xao Ruhog. Electroagetc Feld of Motor, Cha Mache Press, Bejg 00037, PRC, N Guagzheg, Qa Xuyg, etc. Nuerc Calculato of Electroagetc Feld, Hgher Educato Press, Bejg 00009, PRC, Che Yu. Optal desg of log stator lear sychroous otor [M.S. Dssertato], Zhejag Uversty, Hagzhou, Zhejag Provce 30027, PRC, Che Xua. Study o hybrd exctato lear sychroous otor ad ts drve syste [M.S. Dssertato], Zhejag Uversty, Hagzhou, Zhejag Provce 30027, PRC,