Dr. Ali M Eltamaly. Increasing. Fig.1 Speed-torque characteristic for separately excited or shunt DC motors at different external armature resistance

Transcription

1 King Su Univeity t Seete 47-48H Cllege f Engineeing Finl Ex Electicl Engineeing Deptent ie: 3.0 h. EE435-Electic Dive.. Anwe All Quetin: Quetin () Explin with the i f equtin, cuve n tte the wbck f the tue eitnce cntl f c t. Slutin: Atue eitnce cntl f DC t i ne f the pee cntl f the DC t it i cle f the fllwing equtin n figue R R ω ext Keφ ( Keφ ) (f eptely excite hunt DC t) ω ω R R e nceing R e que Fig. Spee-tque chcteitic f eptely excite hunt DC t t iffeent extenl tue eitnce R O ω (f eie DC t) K K K K e f e f ω nceing R e - - que Fig. Spee-tque chcteitic f eie DC t t iffeent extenl tue eitnce

2 (b) Dw the cicuit f buck cnvete n explin it petin in c t cntl. Fig.3 hw Buck cnvete, in thi cicuit we ue tht the witch i iel n the utput cpcit i ue t be vey lge. When the witch S i tune n t t0, the ie will be evee bie n the upply i cnnecte t the l, v n it will upply the l n inuct with enegy. When the witch S i tune ff, the ie will be fw bi n the inuct cuent will flw thugh the ie, tnfeing e f it te enegy t the l. he utput vltge f buck cnvete i hwn in Fig.4. L i L R v L Fig.3 cicuit ig f buck cnvete. A - B - t t n t ff Fig.4 he utput vltge f buck cnvete. F the cicuit in Fig.3, the utput vltge equl the input vltge when the witch i ON n it i ze when the witch i OFF. By vying the utin f which the witch i ON n OFF, it cn be een tht the vege utput vltge cn be vie, but the utput vltge i nt pue DC. he utput vltge cntin n vege vltge with - -

3 que-vltge upeipe n it, hwn in Fig.4. Uully the eie utce i DC vltge withut ny nticeble ipple cntent. When the witch i n f tie utin t n, the witch cnuct the inuct cuent n the ie bece evee bie. hi eult in pitive vltge v L - c the inuct in Fig.3. hi vltge cue line incee in the inuct cuent i L. When the witch i tune OFF, becue f inuctive enegy tge, i L cntinue t flw. hi cuent nw flw thugh the ie, n v L - in Fig.3. n tey tte petin, the integl f the inuct vltge v L ve ne tie pei ut be ze. hen, S t n S v L t vl t vl t 0 () t n n Fig.4 the fging equtin iplie tht the e A n B ut be equl. heefe; ( O n O S n ) t ( t ) () tn D (3) O S Neglecting pwe le cite with ll the cicuit eleent, the input pwe P equl the utput pwe P O : P P O (4) O O (5) (6) D O O hi cnvete cn be ue in pee cntl f DC t by cntlling the tue n fiel vltge by vying the uty ti f the buck cnvete

4 (c) he pee f eie c t i cntlle by ingle-phe full bige ie ectfie n bt cnvete. he ie ectfie i pete f 380, 60 Hz ingle-phe upply. he bt cnvete h f. 5kHz, L 0. H n C 00uF. he tue n fiel eitnce e 0.08 n 0.5 Ω n K φ. /p. he cnvete n c upply e cniee t be iel. () f the t cuent i 00A t 0.7 uty ti f bt cnvete, fin t pee, evelpe tque. () F the e l cuent (00) n 00 p pee, eteine the equie uty ti f bt cnvete. Slutin: *380 () 34. π π S S 34. OB D( D) D( D) * 0.7 * ( 0.7) 39. 5A L L 500 * * Q < OB, then, he bt wk in icntinuu cnuctin e S 34. Q DΔ 00 *.7 * Δ L 500* *.000 hen Δ Δ D Δ hen 98. hen E ( R R ) * ( ) 5. f E Kφ Ν 5.. * N hen N p E 5. * 00 ev 9N. ω * π *043.5 / 60 () n eie c t evα, ue t the tque i till the e in pt () then the cuent l till the e. hen 00A E Kφ N hen E. *00 30 E R R f * hen, ( ) ( ) S 7 L * OB, x D 4 7 B,x / 4 7 A /

5 Quetin () Dw n explin the pee tque cuve f eie n eptely excite c t in pee lwe n highe thn te pee. he DC eie t cn be cntlle by uing tue vltge cntl n thee i n epte cntl n the flux. But eptely excite DC t cn be cntlle by uing tue vltge cntl t te fiel cuent t pee lwe thn te pee n flux cntl t te vltge f pee gete thn the te pee. he fllwing figue hw the pee cntl f eie n hunt DC t lwe n highe thn the te pee. ω Deceing flux t cntnt ω Deceing φ t cntnt Deceing t Full flux que Deceing t cntnt φ Seie Shunt n eptely excite Fig.5 Spee cntl f eie n hunt DC t lwe n highe thn the te pee. (b) he pee f 0 hp, 300, 900 p eptely excite c t i cntlle by thee phe full wve cntlle cnvete. he fiel cicuit i cntlle by theephe hlf wve cntlle cnvete. he c input t the tue n fiel cnvete i thee-phe, Y-cnnecte, 08, 60 Hz. he tue eitnce i R 0. 5Ω, the fiel cicuit eitnce R 70Ω. he n- l pee t te fiel f cuent t ze ely ngle f tue n fiel cnvete i 000 p. he tue n fiel cuent e cntinuu n ipple fee.. f the fiel cnvete i pete t the xiu fiel cuent n the tue cuent i 47 A t 750 p, eteine the ely ngle f tue n fiel cnvete.. f the fiel cicuit cnvete i et t the xiu fiel cuent, the tue cuent i 48 A, n the ely ngle f the tue cnvete i ze, eteine the t pee.. F the e tue cuent f pt (), eteine the fiing ngle f the fiel cicuit cnvete if the pee h t be incee t 800 p

6 LL 08 p 0, p * () 3 3 *69.83 f π π f f A R 70 f 3 3 he tue c vltge t n l i π E N E 750 E0 N hen E hen E R * hen cα 80.9 * cα π 3 3 (b) π hen Eb br Eb 48 * hen, E b E b Nb 73.7 N b E N * 750 hen, N b p (c) f the N c 800p E c fc * Nc E *800 c fc E * N 73.7 * b hen,. 5 fb b Ec 5. 8 fc α () fc c 08.5 fc c hen () c fc Ec cr (3) Subtitute f () n () int (3) we get the fllwing: * 0.5 hen, fc fc. 086 fc fc * R fc.086 * A *69.83 f cα cα π π hen, α

7 Quetin 3 () Dw the thee-phe PWM cnvete cicuit n explin the petin f thi cnvete in cntlling thee-phe inuctin t. Al, explin n w the cicuit f the unipl n bipl PWM. hee-phe invete i t hpe n cntl the thee-phe utput vltge in gnitue n fequency with n eentilly cntnt input vltge c. btin blnce thee-phe utput vltge in thee-phe PWM invete, the e tingul vltge wvef i cpe with thee inuil cntl vltge tht e 0 ut f phe which cn cntl thee-phe inuctin t. he fequency f utput vltge cn be vie by vying the fequency f cntl ignl. PWM with Bipl ltge Switching he ignlly ppite witche ( A, B- ) n ( A-, B ) f the tw leg invete e witche witch pi n, epectively. With thi type f PWM witching, the utput vltge wvef f leg A i ienticl t the utput f the bic ne-leg invete, which i eteine in the e nne by cpin f v cntl n v ti. he utput f invete leg B i negtive f the leg A utput; f exple, when A i n n v A i equl t i l n n v B. heefe: vb() t va() t v t v t v t v t n () () () () A B A he v wvef i hwn in the fllwing figue. hen; ˆ.0 4 π ( ) n ˆ < ( >.0) < - 7 -

8 PWM with bipl vltge witching. PWM with Unipl ltge Switching n PWM with unipl vltge witching, the witche in the tw leg f the full-bige invete e nt witche iultneuly, in the peviu PWM chee. Hee, the leg A n B f the full-bige invete e cntlle eptely by cping v ti with v cntl n vcntl, epectively. A hwn in the fllwing figue, the cpin f v cntl with the tingul wvef eult in the fllwing lgic ignl t cntl the witche in leg A: v cntl > vti A n n AN v cntl < vti A n n AN 0 he utput vltge f invete leg A with epect t the negtive c bu N. F cntlling the leg B witche, vcntl i cpe with the e tingul wvef, which yiel the fllwing: v cntl > vti B n n BN v cntl < vti B n n BN 0 he wvef f the fllwing figue hw tht thee e fu cbintin f witch n-tte n the cepning vltge level: - 8 -

9 Fig.4.5 PWM with unipl vltge witching (ingle phe). We ntice tht when bth the uppe witche e n, the utput vltge i ze. he utput cuent ciculte in lp thugh A n D B D A n B epening n the iectin f i. Duing thi intevl, the input cuent i i ze. A iil cnitin ccu when bth btt witche A n B e n. ˆ.0 hen; ( ) 4 π n ˆ < ( >.0) < - 9 -

10 (b) A 480, 60 Hz 4 ple 70 p, Y-cnnecte inuctin t h the fllwing pete pe phe: R 0. 3Ω, R 0. 5Ω, X X. Ω X 40 Ω he t i cntlle by vible fequency cntl t cntnt flux f te vlue. () Clculte the pee n tt cuent t hlf the te tque n 0 Hz upply. () Slve pt () uing the pee-tque cuve t be pllel tight line f <. () Clculte the fequency, the tt cuent, n vltge t te beking tque n 400 p. 0 f 0 * 60 (b) N 800 p P 4 πn π *800 ω 88.5 / ec N N 0.05 N 800 R Rt ipence 0.5 Z jx j. 3 j Ω 0.05 Stt ipence Z R jx 0.3 j Ω Z * Z Mchine ipence Z in Z Z Z ( ) * ( 40 90) Zin ( ) ( 40 90) ph 480 / A Z in ( 40 90) ( ) ( 40 90) Z * * A Z Z E * Z 0.97* R * * 4.4 N. ω (i) At 0 Hz 60 3 Rte tque ( ) 3 ω Ete * R R / ( ) ( X ) * 0.5* 3/ * 9 hen Ω 4.4 N

11 hen, t i nt cceptble vlue, enble vlue. ω ω ( ) *88.5* ( ) / ec 3 N * N ( ) *800 * ( ) p 3 0 At 0 Hz E * R 0.5 j. Z jx Ω E Z E jx j40 / A A A (ii) x n Hz 3y x 600 y 0Hz FL FL x x 3* 0.05 S FL 0.05 hen, y y - -

12 S n hen, n 600 * ( ) 555 p x hen, y F cntnt flux, the E f cn tn t 0 At 0 Hz E * R 0.5 j. Z jx E A Z E A jx j40 / A Ω N l t te tque 90 p (iii) 90 N 490 p f N 490 hen, f Hz hen P R 0.5 Z jx j0.878 * E te 0.878* A Z ei the e A A E Z 0.878* Ω ( j0.878*.) *

13 Quetin 4 () n cntnt flux cntl f 3-phe inuctin t, pve tht the xiu tque i cntnt f ny peting fequency in < nge. he equivlent cicuit t ny fequency t cntnt flux cntl i hwn in the fllwing figue: X X R / R X E E R te te ( X ) ( X ) E R 3 R ( ) 3 E te * R / ω ω R X get the xiu tque ue 0 R ± ubtitute thi equtin in the tque equtin we get the fllwing equtin: X 3 E te x ω X t i cle f thi equtin tht the xiu tque i nt functin f pe unit fequency. S tht the xiu tque i cntnt f ny peting fequency in < nge. (b) hee phe 4-ple Hz, Y-cnnecte inuctin t i cnnecte t ( Hz upply) vi thee-phe full wve uncntlle ectifie, bt cnvete n 3-phe PWM invete t cntl it pee by /f cntl. he witching fequency f the bt cnvete i 0kHz n it inuctnce i H. he c link vltge i intine cntnt t 650, the l tque i intine cntnt t 70N.. he inuctin t h the fllwing pete pe phe: R 0. 8Ω, R 0. 7Ω, X X. Ω X 4 Ω, Auing the pee tque cuve i pllel tight line f <. - f it i equie t ive the t t 900 p, eteine; (i) he lip f inuctin t. (ii) he ultin inex f the PWM invete. (iii) he uty ti f the bt cnvete. - f it i equie t ive the t t 60Hz cntl ignl fequency f the PWM, eteine: (i) he pee f ttin

14 (ii) he ultin inex f the PWM invete. (iii) he uty ti f the bt cnvete. (b) - (i) At te cnitin, 0 f 0 *50 πn N 500 p, hen π *500 ω / ec P F (6.5) ( ) ( ) te * R /, ω R R / X X 3 0 *0.7 / ( ) ( ) / he feible vlue i N N * Rt ipence R 0.7 Z jx j j Ω Stt ipence Z R jx 0.8 j Ω Z Mchine ipence * Z Z in Z Z Z, ( ) ( ) p ( 4 90) ( 4 90) * Zin ph 380 / A, Z 0.54 E te in 380 / E 05.8 hen, 4. 6 f 50 * ( R jx ) ( ) 5.6 * Ω - 4 -

15 n Hz f Hz 800 At 800p ` pee; PN N p, f 4 * Hz (ii) E E te * FL Ete R 0.7 jx j( *.) [ R j( X X )] / jx 0.7 j0.5496(. 4) j * 4 E * R jx 3. 0 ( ) hen, LL 3.76 * * 650, hen (iii) he input pwe t inuctin t i : 3 * 4.36 * 0.77* c( ) W hen the c link cuent i A 650 * ( 0.8 j.5496*.) A - 5 -

16 3 3 he utput vltge f the ectfie i LL LL π π 650, then D 0. D 53.8 S 650 Q B D( D) * 0.* ( 0.) 4. 6A L *0 * * 0.*0 Q <, hen the bt cnvete wk in icntinuu cnuctin e. hen, B S 7 L 7 OB, x * *0 650 * 0.*0 / hen, D,x B hen the bt cnvete wk in icntinuu cnuctin e n the uty ti will be btine befe D (i).4 >, hen, te F (6.56) ( ) ( ) te * R / ω R R / X X / 3* 0.7 /(.4) ( ) ( ) / he feible vlue i N 0 * 70 / 4 00p, N ( ) N ( 0.030) p (ii) 0. 6 LL , hen (iii) Rt ipence R 0.7 Z jx j.4 * Ω Stt ipence Z R jx 0.8 j.4 * Z Mchine ipence * Z Z in Z Z Z (.4 * 4 90) (.4 * 4 90) * Zin Ω ph 380 / A Z in he input pwe t inuctin t i : 3 * 380 * 38.4 * c(.8) 3.479kW 3479 hen the c link cuent i 36. 3A < hen the bt cnvete wk in icntinuu cnuctin e. hen; A Ω / - 6 -

17 / /,x B D