逆变器并联系统直流环流检测与抑制方法英文

1、D C LOO P-CURRENT D ETECT ING A ND RESTRA IN INGM ETHOD S FO R PA RALL EL INVERTER SY STEMCH EN L ia n g 2l ia n g , X IA O L a n , YA N Y a n g 2g u a n g(A e ro 2Pow e r Sc i2T ech C en te r, N U A A210016, P. R. C h ina)29 Yudao S t ree t, N an jing,A bstrac t: D C com po nen t is co n ta ined in

2、 inve r te r o u tp u tvo ltage due to m any rea so n s such a s th e ze ro 2po in t dev ia t io n o f op e ra t io na l am p lif ie r s and th e d iffe rence s be tw een pow e r sw itch ing t ran sisto r sch a rac te r ist ic s. Fo r th e p a ra lle l inve r te r sy stem w itho u t o u tp u t iso l

3、a t io nt ran sfo rm e r s, th e d iffe rence o f D C com po nen t s o f th e o u tp u t vo ltage can cau se la rge D C loop 2cu r ren t am o ng m o du la r inve r te r s. A im ing a t th is p ro b lem , th is p ap e r stud ie s seve ra l D C loop 2cu r ren t de tec t ing and re st ra in ing m e tho

4、 d s. B y d ig ita l ad ju stm en t w ith h igh p rec isio n o n th e D C com po nen t s o f refe rence sine w ave, th e D C com po nen t s o f inve r te rs o u tp u t vo ltage can be ad ju sted to re st ra in D C loop 2cu r ren t. E xp e r im en ta l re su lt s p ro ve th a t th e D C loop 2cu r re

5、n t de tec t ing and re st ra in ing m e tho d sh ave a goo d p e rfo rm ance.+1redu n dan t sy stem b y Nredu n dan cy an d toco n st itu team o du la rpow e rd ist r ib u t io nsy stem 1 5 .H ow eve r,D Ccom po n en tisco n ta in ed in in ve r te r o u tp u t vo ltage du e to th eze ro 2po in t de

6、v ia t io n o f op e ra t io n a l am p lif ie r s,th eu n b a lan ce o fco n t ro lsign a l,an dth et ran sisto r sd iffe ren ce sinpow e rch a rac te r ist ic s6, 7 , e tc. sy stem w itho u t o u tp u tsw itch in gFo r th e p a ra lle l in ve r te rt ran sfo rm e r s, d iffe ren ceo f D C com po n

7、 en t b e tw een o u tp u t vo ltage o f eachm o du le can cau se la rge D C loop 2cu r ren t am o n g in ve r te r s b ecau se th e equ iva len t im p edan ce o f th e in ve r te r is ve ry sm a ll. A s a re su lt, each m o du le o f th e p a ra lle l in ve r te r sy stem can no t sh a re lo ad cu

8、r ren t even if th e p h a se an d th e am p litu de o f each m o du les o u tp u t vo ltage a re th e sam e a s o th e r s, w h ich redu ce s th e re liab ility o f p a ra lle l sy stem 7, 8 .T h e m o st effec t ive m e tho d fo r re st ra in in g D C loop 2cu r ren t is u sed to ad ju st th e o u

9、 tp u t D C com po n en t o f each m o du le to b e th e sam e a s o th e r s. A cco rd in g to th is idea, seve ra l D C loop 2 cu r ren t de tec t in g an d re st ra in in g m e tho d s ino u tp u t t ran sfo rm e r le ss p a ra lle l in ve r te r sy stem a re p ropo sed in th is p ap e r. B y d i

10、g ita l ad ju stm en t o n th e D C com po n en t o f in ve r te r refe ren ce sin e w ave, th e D C com po n en t o f in ve r te r o u tp u tvo ltage is d ig ita lly regu la ted w ith h igh p rec isio nKey words: D C loop 2cu r ren t; de tec t; d ig ita l ad ju stm en t;p a ra lle l inve r te rCL C

11、 n um ber: TM 464D ocum en t code: AA r t ic le ID : 100521120 (2004) 0120001206INTROD UCT IO NW ithth e fa st deve lopm en teco nom ic s, requ e st o n th e cap ac ity,o fn a t io n a lp e rfo rm an cean d re liab ility o f sw itch in g m o de pow e r supp lysu ch a s u n in te r rup ted pow e r su

12、pp ly (U P S ) h a s b een deep ly in c rea sed. Its comm o n ly reco gn izedth a t p a ra lle l op e ra t io n o f th e pow e r supp ly is th edeve lopm en ttech no lo gy.d irec t io no fpow e rsupp lyloop 2cu r ren t.P a ra lle lin ve r te rsy stemisan dtore st ra inD CE xp e r im en ta lin c rea

13、sin g ly u sed to o b ta in fau lt2to le ran t6re su lt s in akV A p a ra lle l sy stem ve r ify th efea sib ility o f D Cloop 2cu r ren tre st ra in in g m e tho d s p ropo sed.R T 3 IL m axde tec t in g an dR Tw h e re U L ac =sin t, U L dc =I H dc.NNE q.( 3)in d ica te s th a t th e D C com po n

14、en t o fcu r ren t L EM s o u tp u t vo ltage is lin ea r w ith th eD C loop 2cu r ren t o f p a ra lle l sy stem , an d th e D C loop 2cu r ren t can b e ca lcu la ted b y de tec t in g th e D C com po n en t o f uL EM. T h e de tec t io n c ircu it o fD C com po n en t is show n in F ig. 2.1D C LO

15、O P-CURRENTT ING M ETHOD SD ETEC-tw o 2m o du le p a ra lle lin ve r te rsy stemAw itho u t o u tp u t iso la t io n t ran sfo rm e r is tak en a san ex am p le.In F ig. 1, R 1 an d R 2 a re th eequ iva len t o u tp u t re sisto r s o f tw o in ve r te r s, L fan d C f th e in ve r te rs o u tp u t

16、f ilte r in du c to r an df ilte r cap ac ito r,an d U dc1 an dcom po n en t s o f o u tp u t vo ltage o f re sp ec t ive ly.U dc2 th e D Ctw o in ve r te r s,F ig. 2 D e tec t io n c ircu it o f D C com po nen tT h is de tec t io n c ircu it is com po sed o f th reep a r t s: R 1 an d C 1 co n st i

17、tu te f ilte r in g c ircu it w h ich f ilte r s L EM s o u tp u t vo ltage to a r ipp le D C vo ltage. In teg ra l c ircu it is com po sed o f R 2 , R 3 , R 4 , C 2 an d op e ra t io n a l am p lif ie r O P 1. T h e o u tp u t vo ltage o f O P 1 is p ropo r t io n a l to th e D C com po n en t o f

18、cu r ren t L EM s o u tp u t vo ltage.B ecau se th e o u tp u t vo ltage o f O P 1 is som e t im e s n ega t ive w h ich can no t b e de tec ted b y A D co n ve r te r. T h e add it io n c ircu it com po sed o f R 5 , R 6 , + 5 V DC vo ltage so u rce an d O P 2 g ive s a D C b ia s. A ssum in g th a

19、 t U op dc an d U op ac a re D C com po n en t an d A C in g red ien t o f op e ra t io n a l am p lif ie r o u tp u t vo ltage o f O P 1 , re sp ec t ive ly,th e steady2sta te D C am p lif ica t io n ra t io o f f ilte rin teg ra l c ircu it can b e g iven b yF ig. 1 A tw o 2m o du le p a ra lle l

20、inve r te r sy stemA ssum in g th a t R 1 = R 2 = R , th e exp re ssio no f D C loop 2cu r ren t can b e def in ed a srrI o 1 -I o 2U dc1 - U dc2rI H dc =(1)=22R( 1)E q.in d ica te s th a t a sm a ll u n b a lan ce o fD C com po n en t s b e tw een each m o du les o u tp u tvo ltage can cau se la rg

21、e D C loop 2cu r ren t b ecau se in ve r te r equ iva len t re sisto r R is ve ry sm a ll.It is ev iden t th a t D C loop 2cu r ren t f low sth ro u gh in ve r te r o u tp u t f ilte r in du c to r a s show nU op dcR 4(4)K dc =in F ig.1,th e refo re D C loop 2cu r ren t can b eL dc R 1 + R 2Ude tec

22、ted b y de tec t in g th e D C com po n en t o f f ilte rin du c to r cu r ren t iL. A ssum in g th a tT h e A C am p lif ica t io n ra t io o f D C com po n en tf ilte rin teg ra l c ircu it can b e exp re ssed a siL = IL m ax sin t + I H dc(2)U op acK ac =w h e re I H dc is th e D C com po n en t

23、o f f ilte r in du c to rcu r ren t.T h e in du c to r cu r ren t can b e de tec ted th ro u gh a cu r ren t L EM w ith a ra t io o f 1N an d de tec t in g re sistan ce R T. T h en th e o u tp u t vo ltageo f cu r ren t L EM can b e d raw n a s fo llow sU L ac R 4 (5)(S C 2R 4 + 1) (S C 1R 1R 2 + R

24、1 + R 2 )W h en th e o u tp u t f requ en cy o f in ve r te r is 50H z, a ssum in g th a t C 1 =2F , C 2 =1F , R 1 =R 2 = 250 k 8 , R 5 = R 6 = 10 k 8 , R 4 = 1 M 8 , th eD C an d A C am p lif ica t io n ra t io s o f D C com po n en t f ilte rin teg ra l c ircu it can b e go t a s K dc = 210 an dR

25、T 3IL m ax sin t + R T 3 I H dciLuL EM = N 3 R T =Nam p lif ica t io n ra t io is m u ch sm a lle r th an th e D Cam p lif ica t io n ra t io , so th e A C in g red ien t o f L EM o u tp u t vo ltage can b e igno red. T h en th e exp re ssio n o f o u tp u t vo ltage U dc in th e D C com po n en t d

26、e tec t io n c ircu it can b e go t R 6 3 R 4 5R 5 ) 3 U L dc =U dc = R-(R 5 + R 6 ) (R 1 + R 25 + R 6F ig. 3 Co nf igu ra t io n o f th ree sta te h y ste re sis2band co n t ro led inve r te rR T215 -U L dc =215 -(6)I H dcNE q. (6) in d ica te s th a t th e o u tp u t vo ltage U dco f D C com po n

27、en t de tec t io n c ircu it is lin ea r w ith th e D C loop 2cu r ren t o f p a ra lle l sy stem an d it is ve ry ea sy to ge t D C loop 2cu r ren t o f p a ra lle l in ve r te r th ro u gh sim p le ca lcu la t io n.b an d co n t ro lled in ve r te r can b e show n a sU o (S )T S + R o K g(S ) =(7)

28、U r (S )T 1S 2 + T 2S+K g K vfR ow h e re T , T 1 , T 2 an d K g a re p a ram e te r s o f th reesta te h y ste re sis2b an d co n t ro lled in ve r te r.T h en th e D C t ran sfe r r in ggo t b y se t t in g S to ze rofu n c t io n can b e2 D C LOO P -CURRENT RE-STRA IN ING PR INC IPL E A ND M ETHO

29、D SU o dc (S ) 1 dc (S ) =(8)rdc ()USK vfw h e re U rdc an d U o dc a re D Ccom po n en t s o frefe ren ce sin e w ave an d in ve r te r o u tp u t vo ltage,K vf is th e feedb ack co eff ic ien t o f in ve r te r o u tp u t vo ltage.E q. ( 8 ) in d ica te s th a t th e D C com po n en tch an ge o f

30、in ve r te r o u tp u t vo ltage is lin ea r w ith th a t o f refe ren ce sin e w ave w ith a ra t io o f 1K vf.A s a re su lt, th e D C com po n en t o f in ve r te r o u tp u t vo ltage can b e d ig ita lly regu la ted w ith h igh p rec isio n th ro u gh d ig ita l ad ju stm en t o n th e D C com

31、po n en t o f refe ren ce sin e w ave so a s tore st ra in D C loop 2cu r ren t o f p a ra lle l sy stem.T h e re st ra in t m e tho d o f D C loop 2cu r ren t canb e rea lized b y h a rdw a re o r so f tw a re.T h eh a rdw a re m e tho d is to u t ilize o u tp u t iso la t in gt ran sfo rm e r.T h

32、em e tho dh a stw od isadvan tage s. F ir st ly, th e steady2sta te vo ltageaccu racy o f th e p a ra lle l sy stem is g rea t ly redu ced b ecau seo fth evo ltaged ropo fiso la t in gt ran sfo rm e r.Seco n d ly,th e pow e r den sity isredu ced b ecau se o f th e w e igh t an d th e vo lum e o ft r

33、an sfo rm e r.lowf requ en cyiso la t in gT h eso f tw a re m e tho d is rea lized b y d ig ita l ad ju stm en to n th e D C com po n en t co n ta in ed in in ve r te r o u tp u t vo ltage to re st ra in D C loop 2cu r ren t.212D C com pon en t d ig ita l a d justm en t m e thod sf or in ver ter ref

34、 eren ce s in e wa veT h e co n t ro l u n it u sed in th e p a ra lle l in ve r te r211D C com pon en t a d just in g pr in c ip lesy stemis 80C 196KB ,a16 b itsin g lech ipA s an a lyzed abo ve,th e m o st effec t ivem ic rop ro ce sso rp ro du cedb yIN T ELm e tho d fo r re st ra in in g D C loop

35、 2cu r ren t is u sed toad ju st th e o u tp u t D C com po n en t o f each m o du le to b e th e sam e a s o th e r s. T h e p a ra lle l in ve r te r sy stem stu d ied in th is p ap e r is com po sed o f tw o 2 th ree sta te h y ste re sis2b an d co n t ro l in ve r te r s b a sed o n o u tp u t v

36、o ltage an d f ilte r in du c to r cu r ren t do u b le c lo se2loop in stan tan eo u s feed b ackco n t ro l tech no lo gy, a s show n in F ig. 3.Co rpo ra t io n. A p e r io d o f refe ren ce sin e w ave isd iv ided in to 1 000 d ig ita l po in t s w h ich a re p laced in E PROM 27C 256, th en a 5

37、0 H z refe ren ce sin e w ave can b e go t b y sen d in g o n e d ig ita l po in t to12 b it DA C M A X 507 each 20 s. T h e exp re ssio no f refe ren ce sin e w ave U r is g iven b yD X i -2 048D X i -2 048)U r = U ref= 520482 048in d ica te th a t th e c lo se2loopR ef s. 9, 10(9)DA C M A X 507, D

38、 X i ( i =1, 2, , 1 000)is 1 000D X 1 =loop 2cu r ren t o f p a ra lle l in ve r te r sy stem.If a ll th e 500 po in t s o f po sit ive ( n ega t ive ) h a lf p e r io d o f refe ren ce sin e w ave a re m u lt ip lied b y a f lo a t in g po in t n um b e r K ( a ssum in g th a t K = 1- , 0 1 ) , th

39、en a n ega t ive (po sit ive ) D C com po n en t w ill b e p ro du ced b ecau se o f th eu n b a lan ce b e tw een th e po sit ive an d n ega t ive vo ltage2seco n d p ro du c t o f refe ren ce sin e w ave.T h e p r in c ip le o f th e m e tho d is show n in F ig. 4.d ig ita l po in t s o f refe ren

40、 ce sin e w ave,D X 501 = 2 048, D X 250 = 4 095, D X 750 = 0.T h e D C com po n en tw ave can b e d raw n a sU rdc o frefe ren cesin e2 120U r (t) d t =U rdc =1 0001 32 5 D X i -2 048=2 1 000 i= 12048 1 D X 1 + + D X 1 000(10)- 1 0002002 048U su a lly th e fo llow in g equ a t io n is ten ab le1D X

41、 1 + + D X 1 000U rdc =- 1 000= 02002 048(11)com 2A cco rd in g to E q s. ( 10, 11 ) , th e D Cpo n en t o f refe ren ce sin e w ave can b e ad ju sted b y1 000p ro ce ssin g th e sed ig ita l po in t s p rop e r lyb efo re th ey a re sen t to DA C M A X 507.O b v io u sly, a po sit ive ( n ega t iv

42、e ) D C com po n en t w ill b e p ro du ced b y add in g ( su b t rac t in g ) a d ig ita l qu an tum D X to a ll th e d ig ita l po in t sD X 1 , D X 2 , , D X 1 000 b efo re th ey a re sen t toM A X 507, th u s th e D C com po n en t o f refe ren ceF ig. 4 D C com po nen t ad ju st ing p r inc ip

43、leT h e D C com po n en t o f refe ren ce sin e w avecan b e g iven b y E q.( 15 )( a ssum in g th a t apo sit ive D C com po n en t is requ e sted , th en a ll th e500 po in t s o f th e n ega t ive h a lf p e r io d a re m u lt ip lied b y K )(10, 11)sin e w ave can b e go t f romE q s.12U rdc =3

44、1U rdc = 2 U p 0 -(1 - )U p 0 s in tdt = 52001 000(15)B ecau se 80C 196KB can o n ly dea l w ith m u lt i2D X i + 1 0003 D X- 1 00032 048=i= 12 048 1 3 1 0003 D X p lica t io n an d d iv isio n o f 16 b it500 po in t s o f n ega t ive h a lf p ro ce ssed a sin tege r, a ll th ep e r io d can b e(12)

45、th e D C com po n en t ad22002 048B ecau se D X m in =1,16D X i 3(2 - D )ju st in g p rec isio n o f refe ren ce sin e w ave isD X 3= D X i (1 -=i21611 000 =U rdc =32144(13)16D 2 ) = D X i (1 - )501 i 1 0002002 048(16)A cco rd in g ly th e D C com po n en t ad ju st in gp rec isio n in a 220 V 50 H

46、z in ve r te r can b e go t b yO b v io u sly D m in = 1, th e refo re th e D C com 2po n en t ad ju st in g p rec isio n o f th e refe ren ce sin e w ave is(8)E q.220U o dc = U rdc= 01152(14)5 25m in5D m in= 2412U rdc =(17)216 3E q. ( 14 ) in d ica te s th a t th e D C com po n en tad ju st in g p

47、rec isio n o f th e m e tho d is no t ve ry h igh , an d th e ad ju st in g p rec isio n m ay b e low e r w h en th e p rec isio n o f D A co n ve r te r is low e r.T h e refo re, a m o re eff ic ien t m e tho d fo r ad ju st in gA cco rd in g ly th e D C com po n en t ad ju st in gp rec isio n o f

48、in ve r te r o u tp u t vo ltage isU o dc = U rdc 220 =1151(18)5 2th e m e tho d is ve ry h igh an d th e ad ju st in g m e tho dh a s a ve ry lit t le im p ac t o n T HD o f in ve r te r o u tp u t vo ltage.3EXPER IM ENTAL RESUL TSIn o rde r to ve r ify th e fea sib ility o f th eloop 2cu r ren tp

49、ropo sedD Cde tec t in gan dre st ra in in g m e tho d s, a 6sy stem w ithtw o 2th reekV Asta tep a ra lle l in ve r te rh y ste re sis2b an dF ig. 6 E xp e r im en ta l w avefo rm s o f o u tp u t vo ltage sand cu r ren t s w itho u t D C loop 2cu r ren t re st ra in ing m ea su reco n t ro l in ve

50、 r te r s u n de r re sist ive lo ad is b u ilt an dte sted. T h e p a ram e te r s o f th e sin g le in ve r te r a reU in = 340 V dc ,U o = 220 V 50 H zP o = 3 kV A , L f = 1184 m H , C f = 40 FA ssum in g th a t U o dc1 , U o dc2 an d I H dc a re D Ccom po n en t s o f tw o in ve r te r so u tp u

51、 t vo ltage s an dT h e D C com po n en t s o f tw o in ve r te r so u tp u tvo ltage s an d D C loop 2cu r ren t o f p a ra lle l in ve r te r2.1sy stem isCo n d it io nshow n in T ab leCo n d it io nan dD C loop 2cu r ren t, re sp ec t ive ly.T ab le1show s2rep re sen t th e op e ra t io n a l sta

52、 te sw ith D C loop 2cu r ren t re st ra in in gth e exp e r im en ta l re su lt s o n th e re la t io n s b e tw eenD C com po n en t s an d D C loop 2cu r ren t in th e p a ra lle l in ve r te r sy stem.It can b e seen th a t a sm a ll d iffe ren ce o f D C com po n en t s w ill cau sela rge D C l

53、oop 2cu r ren t.w itho u t an dm ea su re s.Table 2 Exper im en ta l re sults Co n d it io n U dc1 m V U dc2 m V I H dc A Table 11- 225. 2180. 33- 2. 94Exper im en ta l re sults of D C loop- curren t2- 8. 3611. 2- 0. 076U o dc1 mVU odc2 mVU odc mVI H dc A247. 60111. 80- 15. 9712. 3610. 5511. 24235.

54、20101. 30- 27. 211. 420. 67- 0. 13T h e ch an ge o f D C loop 2cu r ren t can b e d raw nf rom T ab le 2 af te r re st ra in in g m e tho d is ca r r ied o u t - 259. 70 11. 68 - 271. 40 - 1. 77 2194 - 01076 =21864(19) I H dc =I H dc1 -I H dc0 =E xp e r im en ta l w avefo rm s o f o u tp u t vo ltag

55、euo an d o u tp u t cu r ren t io 1 ,( 19)th a t D C loop 2io 2 w ith an d w itho u t D CIt can b e seen f rom E q.loop 2cu r ren t re st ra in in g m ea su re s a re show n inF ig s. 5, 6 re sp ec t ive ly.cu r ren t redu ce s g rea t ly af te r D C loop 2cu r ren tde tec t in g an d re st ra in in

56、 g m ea su re s b e in g app lied, w h ich ve r if ie s th e fea sib ility o f th e se m e tho d sp ropo sed in th is p ap e r.4CO NCL US IO NT h e p ro du c t io n rea so n s o f D C loop 2cu r ren tin o u tp u t t ran sfo rm e r le ss p a ra lle l in ve r te r sy stem a re an a lyzed. D C loop 2cu

57、 r ren t de tec t in g an d re st ra in in g m e tho d s in p a ra lle l sy stem a re a lso w e ll re sea rch ed in th is p ap e r. T h e D C com po n en to f in ve r te r o u tp u t vo ltage is regu la ted w ith h ighF ig. 5 E xp e r im en ta l w avefo rm s o f o u tp u t vo ltage sand cu r ren t s

58、 w ith D C loop 2cu r ren t re25M a t su se K , K itah a ta T. A co n t ro l st ra tegy fo r af ive leve l vo ltage2so u rce inve r te r w ith tw o D CD C com po n en t o f refe ren ce sin e w ave to ach ievegoo d D C loop 2cu r ren t re st ra in in g p e rfo rm an ce.chopp e r s A . P ro c IP EM C

59、97 C .668.1997. 664 T h e m e tho d m ak e s it po ssib le fo rco n n ec t io n o f p a ra lle l in ve r te r sy stem.th ed irec tT sa i W en 2Inne, Sun Yo rk 2Y ih. D e sign and im p le2 m en ta t io n o f th ree p h a se H IPWM inve r te r s w ith in stan taneo u s and ave rage feedback A . P ro c IE E E IECON 93 C . 1993. 800 805.T o ko k aw ababa, H iga sh ino S. P a ra lle