do an tuong tu

n mch tng t

GVHD: L Vn Chng

Nhn xt ca gio vin hng dn ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... Ngy. Thng.nm 2010 K tn

SVTH: Nguyn Trung Kin Lp: 49K-TVT

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n mch tng t

GVHD: L Vn Chng

Nhn xt ca gio vin ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... Ngy.thngnm 2010 K tn


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GVHD: L Vn Chng

MC LCLi m u ..........................................................................................Trang 03 C s l thuyt .................................................................................... Trang 05I. nh ngha tng qut ................................................................... Trang 05 1. nh ngha v bi p................................................................ Trang II. Cc b bin i DC-DC ............................................................ Trang 05 1. B bin i gim p ................................................................ Trang 2. B bin i tng p ................................................................. Trang 3. B bin i o p .................................................................. Trang

Thit k v tnh ton mch bin i ngun 5VDC ln 12VDC ....... Trang 13I. Thit k khi to xung ................................................................. Trang II. Thit k v tnh ton cho ton mch ........................................... Trang 1. Thit k mch nguyn l ......................................................... Trang 2. Tnh ton cc linh kin ............................................................ Trang

Kt lun chung .................................................................................... Trang


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n mch tng t

GVHD: L Vn Chng

LI M UTrong lnh vc k thut hin i ngy nay, vic ch to ra cc b chuyn i ngun c cht lng in p cao, kch thc nh gn cho cc thit b s dng in l ht sc cn thit. Qu trnh x l bin i in p 1 chiu thnh in p mt chiu khc gi l qu trnh bin i DC-DC. Mt b nng in p l mt b bin i DC-DC c in p u ra ln hn in p u vo. B bin i DC-DC tng p hay c s dng mch mt chiu trung gian ca thit b bin i in nng cng sut va c bit l cc h thng pht in s dng nng lng ti to (sc gi, mt tri). Cu trc mch ca b bin i vn khng phc tp nhng vn iu khin nhm t c hiu sut bin i cao v m bo n nh lun l mc tiu ca cc cng trnh nghin cu. Thm vo , b bin i l i tng iu khin tng i phc tp do m hnh c tnh phi tuyn. Di y l mt trong nhng ng dng ca in t tng t trong cuc sng hng ngy l Thit k mch bin di ngun 5VDC ln 12VDC trong bi n ny. Em hi vng rng sau khi hon thnh n ny n s gip em cng c li kin thc m em tch ly c trong sut thi gian hc tp v vi c mong n s l mt im ta c bn cho em sau khi ra trng. Trong qu trnh lm n em c s hng dn tn tnh ca thy L Vn Chng. Mc d c gng ht sc nhng l mt lnh vc mi i vi em, nn khng trnh khi nhng thiu st v ni dung v phng php trnh by. Em rt mong c s ch bo hng dn ca thy c v kin ng gp ca cc bn ti ca em c hon thin hn. Em xin chn thnh cm n! Sinh vin thc hin


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GVHD: L Vn Chng

NGUYN TRUNG KIN

Phn 1C s l thuytI. NH NGHA TNG QUT:I.2. nh ngha v bi p: y l qu trnh bin i in p mt chiu U v t gi tr ny sang cc gi tr khc thp hn hoc cao hn, hoc c du ngc li. N thng dng to ra cao p mt chiu cng sut nh trong cc thit b in t lu ng.V d: vt bt mui, di cui in... II. CC B BIN I DC-DC (DC-DC converter) C hai cch thc hin cc b bin i DC-DC kiu chuyn mch: dng cc t in chuyn mch, v dng cc in cm chuyn mch. Gii php dng in cm chuyn mch c u th hn cc mch cng sut ln. Cc b bin i DC-DC c in dng in cm chuyn mch bao gm: buck (gim p), boost (tng p), v buck-boost/inverting (o du in p). Hnh 1.1 th hin s nguyn l ca cc b bin i ny. Vi nhng cch b tr in cm, kha chuyn mch, v diode khc nhau, cc b bin i ny thc hin nhng mc tiu khc nhau, nhng nguyn tc hot ng th u da trn hin tng duy tr dng in i qua in cm.

Hnh 1.1. Cc b bin i DC-DC chuyn mch bng in cm

II.1. B bin i gim p (buck converter)SVTH: Nguyn Trung Kin Lp: 49K-TVT Trang 5

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GVHD: L Vn Chng

1. S nguyn l c bn ca mch buck:

Hnh 1.2. S nguyn l mch gim p (buck). 2. Nguyn l hot ng: y l kiu bin i ngun cho in p u ra nh hn so vi in p u vo tc l Vin (T1/T)Vin = Vout Gi tr D = T1/T thng c gi l chu k nhim v (duty cycle). Nh vy, Vout = VinD. D thay i t 0 n 1 (khng bao gm cc gi tr 0 v 1), do 0 DVin = (1 D)Vout Khi D = 0.5, Vin = Vout. Vi nhng trng hp khc, 0 < Vout < Vin khi 0 < D < 0.5, v 0 < Vin < Vout khi 0.5 < D < 1 (ch l y ch xt v ln, v SVTH: Nguyn Trung Kin Lp: 49K-TVT Trang 13

n mch tng t

GVHD: L Vn Chng

chng ta bit Vin v Vout l ngc du). Nh vy, b bin i ny c th tng p hay gim p, v l l do m n c gi l b bin i buck-boost. Xt cng mt loi bi ton thng gp nh nhng trng hp trn, tc l: cho bit phm vi thay i ca in p ng vo Vin, gi tr in p ng ra Vout, dao ng in p ng ra cho php, dng in ti ti thiu Iout,min, xc nh gi tr ca in cm, t in, tn s chuyn mch v phm vi thay i ca chu k nhim v, m bo n nh c in p ng ra. Phm vi thay i ca in p ng vo v gi tr in p ng ra xc nh phm vi thay i ca chu k nhim v D: Dmin = Vout/(Vin,max + Vout), v Dmax = Vout/(Vin,min + Vout). L lun tng t nh vi b bin i buck, thay i dng in cho php s bng 2 ln dng in ti ti thiu. Trng hp xu nht ng vi ln ca in p trung bnh t vo in cm khi kha (van) ngt t gi tr ln nht, tc l khi D = Dmin. Nh vy ng thc dng chn chu k (tn s) chuyn mch v in cm L ging nh ca b bin i buck: (1 Dmin)TVout = Lmin2Iout,min Cch chn t in ng ra cho b bin i ny cng khng khc g so vi nhng trng hp trn.


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GVHD: L Vn Chng

PHN II

THIT K V TNH TON MCH BIN I NGUN 5V DC LN 12V DCp dng nguyn l cc b chuyn i DC trn, trong phm vi n ny ta s thit k v tnh ton mch bin i t in p mt chiu 5V ln in p mt chiu 12V. Yu cu v cc thng s ca mch bin i nh sau: - in p vo 5VDC - in p ra 12VDC - Sai s in p ra Vrip=100mV - Dng ti cc tiu Iout,min=100mA Vi yu cu nh vy, em s dng mch boost tng in p. Mch boost hot ng theo chu k ca xung a vo ng ngt tranzito. S khi ca mch nh sau: MCH TO XUNG

IN P VO

MCH BOOST

IN P RA

Hnh 2.1. S khi mch I. THIT K KHI TO XUNG: Mch to xung c nhim v to ra cc xung ng ngt transistor mt cch nhp nhng. C nhiu phng n to xung vung nh dng mch a hi, dng IC 555, dng mch dao ng nght Trong n, em la chn mch dao ng dng IC 555 v mch ny tng i n gin, ch cn mt IC 555 cng vi


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GVHD: L Vn Chng

cc linh kin khc l c th to u ra cc xung ch nht p ng yu cu bi ton. 1. Gii thiu v IC 555: IC thi gian 555 c du nhp vo nhng nm 1971 bng cng ty Signetics Corporation bng 2 dng sn phm SE555/NE555 v c gi l my thi gian v cng l loi c u tin. N cung cp cho cc nh thit k mch in t vi chi ph tng i r, n nh v nhng mch t hp cho nhng ng dng cho n n v khng n nh. T thit b ny c lm ra vi tnh thng mi ha. 10 nm qua mt s nh sn sut ngng sn sut loi IC ny bi v s cnh tranh v nhng l do khc. Tuy th nhng cng ty khc li sn sut ra nhng dng ny. IC 555 hin nay c s dng kh ph bin cc mch to xung, ng ct hay l nhng mch dao ng khc

2. Cu to v nguyn l hot ng IC555:2.1. S chn:

NE 555

Hnh 2.2: S chn ca IC nh thi 555 2.2. S khi:


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GVHD: L Vn Chng

Hnh 2.3: S khi ca IC nh thi 555 2.3. S nguyn l NE555:

Hnh 2.4. S nguyn l ca NE555 2.4. Chc nng tng chn ca 555 Chn s 1 (GND): cho ni GND ly dng cp cho IC hay chn cn gi l

chn chung. Chn s 2 (TRIGGER): y l chn u vo thp hn in p so snh v

c dng nh 1 chn cht hay ng vo ca 1 tn so p. Mch so snh y dng cc transitor PNP vi mc in p chun l 2/3Vcc.


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GVHD: L Vn Chng

Chn s 3 (OUTPUT): Chn ny l chn dng ly tn hiu ra logic.

Trng thi ca tn hiu ra c xc nh theo mc 0 v 1. 1 y l mc cao n tng ng vi gn bng Vcc nu (PWM=100%) v mc 0 tng ng vi 0V nhng m trong thc t mc 0 ny ko c 0V m n trong khong t (0.35 ->0.75V) . Chn s 4 (RESET): Dng lp nh mc trng thi ra. Khi chn s 4 ni

masse th ng ra mc thp. Cn khi chn 4 ni vo mc p cao th trng thi ng ra ty theo mc p trn chn 2 v 6. Nhng m trong mch to c dao ng thng hay ni chn ny ln VCC. Chn s 5 (CONTROL VOLTAGE): Dng lm thay i mc p chun

trong IC 555 theo cc mc bin p ngoi hay dng cc in tr ngoi cho ni GND. Chn ny c th khng ni cng c nhng m gim tr nhiu ngi ta thng ni chn s 5 xung GND thng qua t in t 0.01uF n 0.1uF cc t ny lc nhiu v gi cho in p chun c n nh. Chn s 6(THRESHOLD) : l mt trong nhng chn u vo so snh in

p khc v cng c dng nh 1 chn cht. Chn s 7(DISCHAGER) : c th xem chn ny nh 1 kha in t v chu

iu khin bi tng logic ca chn 3. Khi chn 3 mc p thp th kha ny ng li, ngc li th n m ra. Chn 7 t np x in cho 1 mch R-C lc IC 555 dng nh 1 tng dao ng .

Chn s 8 (Vcc): Khng cn ni cng bt l chn cung cp p v dng

cho IC hot ng. Khng c chn ny coi nh IC cht. N c cp in p t 2V 18V .

3.Thit k mch to xung:3.1. S nguyn l mch to xung dung IC555


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GVHD: L Vn Chng

Hnh 2.3: S nguyn l mch 555 Dng xung u ra ca mch to xung: TT1 T2

to

xung dng IC

Hnh 2.4: Dng xung u ra ca mch to xung Cng thc tnh cc thng s ca xung: + Chu k xung (T): T=T1+T2 Trong : T Chu k xung (s) T1 Thi gian tch cc ca xung (s) T2 Thi gian xung bng 0 (s) + Cng thc tnh T1 v T2: T1 = 0.7(R1+R2)C1 T2 = 0.7R2C1 Suy ra: + Tn s xung (f):f = 1 1,4 = (Hz) T ( R1 + 2 R 2).C1T = 0.7( R1 + 2 R 2)C1


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GVHD: L Vn Chng

II. THIT K V TNH TON CHO TON MCH:1. Thit k mch nguyn l:Yu cu ca bi ton l tng in p DC t 5V ln 12V, vy nn em s dng mch boost lm mch bin p. Mch boost iu khin bi xung do mch to xung to ra. S nguyn l ton mch nh hnh 2.5. Ch cc gi tr Rd v Rgs l gi tr tr trong ca cun dy v in tr mt tip gip G-S khi tranzito thng. Gi tr ca chng thng kh nh (khong 1).Vin

L0.1mH

Rd1

DDIODE-SC

Vout

3 8

U1Q DC 3 7

R12k 2 1

R

VCC

4

Q C3100uF

Rt1k

5

CV

R2GND TH 555 6

5k

C210nF

2

Rgs1

TR

C110nF GND

1

Hnh 2.5. S nguyn l ton mch

2. Tnh ton cc linh kin cho mch: Tnh ton cho mch to xung Tnh ton rng xung: Nh phn tch trn, ta c mi lin h gia in p ra v in p vo l: Vout = Vin/(1 D) (*) D - chu k nhim v ca xung ng ngt tranzito => D = 1-Vin/Vout Yu cu ca ti l in p vo l Vin=5V, Vout=12V. Suy ra mch to xung to ra xung vung c chu k nhim v D=1-5/12=7/12. SVTH: Nguyn Trung Kin Lp: 49K-TVT Trang 20

n mch tng tD=

GVHD: L Vn ChngT1 0.7( R 2 + R1) R 2 + R1 = = T 0.7( R 2 + 2 R1) R 2 + 2 R1

R1 + R 2 7 = R1 + 2 R 2 12

5R1 = 2 R 2

Chn R1=2K, R2=5K Tnh ton tn s xung: i vi mch boost, xung lin h theo cng thc: (1 Dth)T(Vin,th Vout) = Lmin2Iout,min (**) Dth - gi tr ti hn ca chu k nhim v ( rng xung). Ta c: Dth = D = 7/12; Vin,th = 5V; Iout,min = 100mA. Suy ra gi tr chu k T v t cm cc tiu ca cun dy Lmin phi tho mn ng thc (**) trn. Do ta c: Thay s ta c:f = (1 7 / 12 ) (12 7) 10,5 = 3 L min L min 2 100 10f = 1 (1 D ) (Vout Vin ) = T L min 2 Iout , min

Mt khc, trong qu trnh ng/ngt, transistor phi tri qua mt giai on chuyn gia hai trng thi, v do sinh ra tn tht cng sut trn n. iu ny c ngha l khi tn s lm vic cng ln (cng c nhiu ln ng/ngt linh kin trong mt n v thi gian) th tn tht chuyn mch cng ln, v l mt trong nhng l do khin tn s lm vic ca mch b gii hn. Nhng vic nng cao tn s lm vic s gip gim kch thc v khi lng ca cc linh kin, v tng mt cng sut. Chn tn s xung nhp gi tr trung bnh f=10Khz tho mn cc yu cu trn. T ta c gi tr t C1: Tnh gi tr t C1: =>C1 =f = 1,4 ( R1 + 2 R 2) C1

1,4 1,4 = 10 nF ( R1 + 2 R 2) f ( 2 + 2 5) 10 3 10 4

Chn gi tr t C1=10nF SVTH: Nguyn Trung Kin Lp: 49K-TVT Trang 21

n mch tng t Tnh ton cho mch bin p: Tnh ton cun cm L:

GVHD: L Vn Chng

Theo gi thit, cun dy l tng tc l in tr trong rt nh, c th b qua c. Hn na, dy qun cn chu c dng cm ng qua cun dy. Do tit din dy qun phi ln (R = l/S). Chn ng knh dy qun l 1mm t cm ca cun dy tho mn ln hn gi tr Lmin . Gi tr Lmin tnh ton nh sau: Lmin= 10,5/f = 10,5/10000 = 0,1(mH) Gi tr cun dy ny l gi tr nh nht m bo rng dng qua ti l lin tc (gi tr tc thi lun > 0). Do , chn cun cm c t cm L = 0.1mH Cch qun cun cm: Vi li khng kh c t thm =1. Ta c:L = 4 10 7 N 2S l

Hay Trong :

L = 4 10 7

N .S d

S - tit din ngang ca cun dy ( m2) N - s vng qun (vng) d - ng knh si dy qun (m) l - chiu di cun dy (m). Ta c l=N.d Thay gi tr L=0.1mH:0.110 3 = 4 3.14 10 7 N .S = 80 d N.S d

Do ng knh si dy qun chn trn d=1mm. Chn N=80 (vng), S=0.001(m2)=.R2 ng knh li qun dy:


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n mch tng tR= S 3.14

GVHD: L Vn Chng =0.001 3.14

=1,7(cm)

Vy cun dy qun li khng kh, ng knh dy qun d=1mm; ng knh vng qun l D=2R=3,4cm; qun 80 vng. Ta s dng dy ng v chng rt ph bin. Tnh ton t C: Thnh phn xoay chiu ca dng in qua in cm s i qua t in ng ra. Vi dng in qua in cm c dng tam gic, in p trn t in ng ra s l cc on a thc bc hai ni vi nhau (xt trong mt chu k chuyn mch). Lng in tch c np vo t in khi dng in qua in cm ln hn dng in trung bnh s l IT/2. Nu biu din theo in dung v in p trn t in th lng in tch ny bng CV. Trong , I l bin ca thnh phn xoay chiu ca dng in qua in cm, cn V l thay i in p trn t khi np (cng nh khi x, xt trng thi xc lp). Nh vy, chng ta c th xc nh gi tr ca t in da vo ng thc sau: IT/2 = CV I c xc nh trn, bng hai ln dng in ti Iout,min. Vi nhp nh in p ra V=100mV ta c:C= 1 I 1 2 0 .1 T = 10 4 = 100 F 2 V 2 0 .1

Chn gi tr t lc u ra loi 100F, 35V. it ta s dng it Schottky, chn loi 1N5820. Sau khi tnh ton, ta tin hnh ghp mch theo s nguyn l nh hnh 2.5


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n mch tng t

GVHD: L Vn Chng

III. LP RP MCH THC T: Sau khi tnh ton linh kin ta tin hnh v mch in theo mch nguyn l. Sau y l s mch in, trong gi tr cc linh kin tnh ton trn: Bottom View

Top view


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n mch tng t

GVHD: L Vn Chng

KT LUN CHUNG1.Nhn xtMch bin i ngun l thit b c ng dng rng ri trong thc t, n c thit da trn nguyn tc hot ng chung ca ngun xung.Trong bi tp n ny em ch trnh by mt trong cc dng ca ngun xung v trnh by mt s chc nng thng dng ca kha mch bin i in p t 5V DC 12VDC. Do kinh nghim thc t v thi gian cn hn ch, kh nng hiu bit ca em cn hn hp do trong khi thc hin lm n khng trnh khi nhng thiu st nn chng em rt mong nhn c s nh gi ch bo, ng gp kin ca cc thy c v ton th cc bn ti c hon thin hn.

2.Hng pht trinNgy nay khoa hc k thut ngy cng pht trin, c bit l in t, khng nhng th trnh hiu bit ca con ngi ngy cng c nng cao. Do mch tng p ngy cng c thit k n gin, hiu qu, tuyt i m bo an ton cht lng. Trong ti ny em chn gii php mch tng p 5VDC ln 12VDC v n n gin, an ton v c nhiu ng dng trong thc t.

3. xutSch gio khoa ti liu cc ngun thng tin trong qu trnh hc tp, lm bi tp, lm n i vi sinh vin l rt quan trng. N nh hng trc tip n cht lng hc tp ca sinh vin cng nh nh hng n cht lng n. Nhng trong qu trnh hc tp v lm n th chng em thy s lng sch v ti liu chuyn ngnh trong th vin nh trng cn rt hn ch c bit v sch chuyn ngnh khng mang tnh cp nht p ng nhu cu hc tp, nghin cu ca sinh vin. SVTH: Nguyn Trung Kin Lp: 49K-TVT Trang 25

n mch tng t

GVHD: L Vn Chng

Do vy, em mong rng th vin ca nh trng c nhiu sch, ti liu hn c th tm hiu v nghin cu su hn. Mt khc em thy rng hc i i vi hnh. Song song vi vic hc l thuyt trn lp th vic nghin cu ti liu cng rt cn thit. Nh vy cn phi c y trang thit b h tr em trong qu trnh thc hnh. Em thy trang thit b trong nh trng cn nhiu hn ch, sinh vin t c thc hnh c bit l thit b in t. Em mong c nhiu trang thit b c thc hnh nhiu hn.

4. Kt lunTrong thi gian thc hin n, di s hng dn tn tnh ca gio vin L Vn Chng, cng vi s c gng ca c nhn, em hon thnh xong n ny. Tuy c nhiu c gng trong vic tm ti v thc hin, song vn khng trnh khi nhng thiu st v sai lm. Chng em mong nhn c kin nh gi t thy gio L Vn Chng cng cc thy c gio khc trong khoa cng nh tt c cc kin nh gi qu bu khc ca cc bn sinh vin. Em xin chn thnh cm n ! Vinh, ngy 23 thng 06 nm 2011 Sinh vin thc hin

NGUY N TRUNG KIN


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GVHD: L Vn Chng

Ti liu tham kho1. Cc trang web, forum v in t - Vin thng nh dientuvietnam.net, hoiquandtvt.net . 2. K thut mch in t.. 3.


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do an tuong tu

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