Trng HSPKT - Hng Yn - n - Khoa in in T in T C Bn

n 3: in T Cng Sut-T

TRNG HSPKT HNG YN

KHOA IN - IN T

------------CNG HA X HI CH NGHA VIT NAM

c lp-T do- Hnh phc

------------

tuthienbao.com N MN HC

Kha hc: 2010-2014 Ngnh hc: o lng-iu khin t ng Lp: - T K8.4 TI: THIT K B IU P XOAY CHIU MT PHA IU KHIN TC NG C IN.

Ging vin hng dn: Nguyn Th Thanh Tm

Nhm sinh vin thc hin:Hong Lng Thi SnTrn Vn Thoi

Hng Yn ngy 11 thng 11 nm 2012 TI: NGHIN CU, THIT K B IU P XOAY CHIU MT PHA IU KHIN TC NG C TI R-L.

I-S liu cho trc:

-Dng xoay chiu vi cc thng s:

-ng c vi cc thng s: Um=220V; Pm=0.2kw ,nm=1420vg/ph,I dm=1.9A, (m=60%, Cosm=0.8; fm=50Hz. tuthienbao.comII-Ni dung cn hon thnh:

Bo co v tin thc hin cc cng vic theo tng tun.

Thuyt minh ti: ( Phn tch yu cu, trnh by cc phng php thc hin, c s l thuyt, qu trnh thc hin n,)

Cc bn v thit k cho tng khi, cho ton b mch y chnh xc.

Phi m bo tnh kh thi, tnh n nh khi lm vic ca sn phm.

Sn phm cn phi m bo tnh m quan m vn m bo tnh k thut p ng c yu cu ca gio vin hng dn.

Trnh by c hng pht trn ca ti.MC LC:

7PHN I: C S L THUYT

7CHNG I: NG C IN XOAY CHIU MT PHA

71.1.Khi nim

71.2.Nguyn l iu khin ng c xoay chiu mt pha

81.3.Mt s mch iu khin ng c mt pha

10CHNG II: B IU P XOAY CHIU MT PHA

102.1.t vn

102.2.Gii thiu mt s s mch ng lc

132.3.Gii thiu v phn t bn dn triac.

132.3.1 Cu to v k hiu

142.3.2 c tnh V-A.

142.4.iu p xoay chiu mt pha ng vi ti R-L

18PHN II: THIT K MCH

18CHNG I: THIT K

181.1.S khi

181.2.Phn tch tng khi

181.2.1. Khi ngun

191.2.2 .Mch lc

211.2.3.Mch iu khin

211.2.3.1.Phn tch

221.2.3.2. Nguyn l hot ng.

231.2.3.3.Gii thiu TCA 785

271.2.3.4.S

28CHNG II: CH TO

282.1.Tnh ton thit k ch to m hnh

282.1.1.Tnh chn van ng lc

292.1.2. Chn thit b bo v.

292.1.2.1. Bo v qu nhit.

302.1.2.2. Bo v qu dng in cho van.

302.1.2.3. Bo v qu in p cho van.

342.3.S board

362.4.S b tr thit b

362.5.phng hng pht trin ca ti

LI NI Uin t cng sut v truyn ng in l mt mn hc hay v l th, cun ht c nhiu sinh vin theo ui. L nhng sinh vin chuyn ngnh o lng iu khin, chng em mun c tip cn v hiu su hn na b mn in t cng sut v truyn ng in.V vy, n mn hc ch to sn phm l iu kin tt gip chng em kim chng c l thuyt c hc.

Trong n in t cng sut ln ny, chng em c nhn ti Nghin cu,thit k b iu p xoay chiu mt pha iu khin tc ng c. Sau thi gian nghin cu, chng em ch to thnh cng b iu khin in p xoay chiu 1 pha p ng c c bn yu cu ca ti.

Trong sut thi gian thc hin ti, chng em gp mt s vng mc v l thuyt v kh khn trong vic thi cng sn phm. Tuy nhin, chng em nhn c s gii p v hng dn kp thi ca c Nguyn Th Thanh Tm, s gp kin ca cc bn sinh vin trong lp. c nh vy chng em xin chn thnh cm n v mong mun nhn c nhiu hn na s gip , ch bo ca c gio v bn trong cc n sau ny.

Chng em xin chn thnh cm n!Nhm thc hin:

Hong Lng Thi Sn Trn Vn Thoi

PHN I: C S L THUYTCHNG I: NG C IN XOAY CHIU MT PHA

1.1. Khi nim

ng c in xoay chiu mt pha (gi tt l ng c mt pha) l ng c in xoay chiu khng c gp c chy bng in mt pha. Loi ng c in ny c s dng kh rng ri trong cng nghip v trong i sng nh ng c bm nc ng c qut ng c trong cc h thng t ng...Khi s dng loi ng c ny ngi ta thng cn iu chnh tc v d nh qut bn ,qut trn.

iu khin tc ng c mt pha ngi ta c th s dng cc phng php sau:

- Thay i s vng dy ca Stator.

- Mc ni tip vi ng c mt in tr hay cun dy in cm.

- iu khin in p a vo ng c.

1.2. Nguyn l iu khin ng c xoay chiu mt pha

Trc y iu khin tc ng c bng iu khin in p xoay chiu a vo ng c, ngi ta thng s dng hai cch ph bin l mc ni tip vi ti mt in tr hay mt in khng m ta coi l Zf hoc l iu khin in p bng bin p nh l survolter hay cc n p.

Hai cch trn y u c nhc im l kch thc ln v kh iu khin lin tc khi dng in ln.

Ngy nay vi vic ng dng Tiristor v Triac vo iu khin, ngi ta c th iu khin ng c mt pha bng bn dn

1.3. Mt s mch iu khin ng c mt pha

Mt trong nhng ng dng rt rng ri ca iu p xoay chiu l iu khin ng c in mt pha m in hnh l iu khin tc quay ca qut in.

Chc nng ca cc linh kin trong s hnh 15 - 4:

T - Triac iu khin in p trn qut.

VR - bin tr iu chnh khong thi gian dn ca Triac.

R - in tr m.

D - diac - nh ngng in p Triac dn.

C - T in to in p ngng m thng diac.

in p v tc ca qut c th c iu khin bng cch iu chnh bin tr VR trn hnh a. Tuy nhin s iu khin ny khng trit , v vng in p nh khi Triac dn t rt kh iu khin.

S hnh b c cht lng iu khin tt hn. Tc quay ca qut c th c iu khin cng bng bin tr VR. Khi iu chnh tr s VR ta iu chnh vic np t C lc iu chnh c thi im m thng diac v thi im Triac dn. Nh vy Triac c m thng khi in p trn t t im dn thng diac. Kt qu l mun tng tc ca qut ta cn gim in tr ca VR t np nhanh hn, Triac dn sm hn in p ra ln hn. Ngc li in tr ca VR cng ln t np cng chm Triac m cng chm li in p v tc ca qut nh xung.

* Mch iu khin trn y c u im:- C th iu khin lin tc tc qut - c th s dng cho cc loi ti khc nh iu khin sng ca n si t, iu khin bp in rt c hiu qu.

-Kch thc mch iu khin nh, gn.

*Nhc im:

Nu cht lng Triac, diac khng tt th vng tc thp qut s xut hin ting do thnh phn mt chiu ca dng in.

CHNG II: B IU P XOAY CHIU MT PHA

2.1. t vn Cc b bin i in p xoay chiu dng bin i in p hiu dng t ln ti. Nguyn l ca b bin i ny l dng cc phn t van bn dn ni ti vi ngun trong mt khong thi gian t1 ri li ct i trong mt khong thi gian t0 theo mt chu k lp li T. Bng cch thay i rng ca t1 hay t0 trong khong T ta thay i c gi tr in p trung bnh ra trn ti. Nguyn l ny c u im l iu chnh in p ra trong mt phm vi rng v v cp, hiu sut cao v tn tht trn cc phn t in t cng sut rt nh. iu p xoay chiu thng c s dng trong iu khin chiu sng, t nng, trong khi ng mm v iu chnh tc qut gi hoc my bm.

-Phn loi: Da vo s pha ngun cp m ta c cc b iu chnh in p khc nhau l iu p xoay chiu mt pha, iu p xoay chiu ba pha.

2.2. Gii thiu mt s s mch ng lc

Hnh 1 gii thiu mt s mch iu p xoay chiu mt pha. Hnh 1a l iu p xoay chiu iu khin bng cch mc ni tip vi ti mt in khng hay in tr ph (tng tr ph ) bin thin. S mch iu chnh ny n gin d thc hin. Tuy nhin, mch iu chnh kinh in ny hin nay t c dng, do hiu sut thp (nu Zf l in tr ) hay cos( thp(nu Zf l in cm ).

Hnh 1 Cc phng n iu p mt pha

Ngi ta c th dng bin p t ngu iu chnh in p xoay chiu U2 nh trn hnh 1b. iu chnh bng bin p t ngu c u im l c th iu chnh in p U2 t 0 n tr s bt k, ln hay nh hn in p vo. Nu cn in p ra c iu chnh, m vng iu chnh c th ln hn in p vo, th phng n phi dng bin p l tt yu. Tuy nhin, khi dng ti ln, s dng bin p t ngu iu chnh, kh t c yu cu nh mong mun, c bit l khng iu chnh lin tc c, do chi than kh ch to c th ch tip xc trn mt vng dy ca bin p.

Hai gii php iu p xoay chiu trn hnh 1a,b c chung u im l in p hnh sin, n gin. C chung nhc im l qun tnh iu chnh chm v khng iu chnh lin tc khi dng ti ln. S dng s bn dn iu chnh xoay chiu, c th khc phc c nhng nhc im va nu.

Cc s iu p xoay chiu bng bn dn trn hnh 1c c s dng ph bin. La chn s no trong cc s trn tu thuc dng in, in p ti v kh nng cung cp cc linh kin bn dn. C mt s gi khi la chn cc s hnh 1c nh sau:

Hnh 2: S iu p xoay chiu mt pha bng bn dn

a. bng hai tiristor song song ngc

b. bng triac

c. bng mt tiristor mt diod

d. bng bn diod mt tiristorS kinh in hnh 2.A thng c s dng nhiu hn, do c th iu khin c vi mi cng sut ti. Hin nay Tiristor c ch to c dng in n 7000A, th vic iu khin xoay chiu n hng chc nghn ampe theo s ny l hon ton p ng c

Tuy nhin, vic iu khin hai tiristor song song ngc i khi c cht lng iu khin khng tt lm, c bit l khi cn iu khin i xng in p, nht l khi cung cp cho ti i hi thnh phn in p i xng (chng hn nh bin p hay ng c xoay chiu). Kh nng mt i xng in p ti khi iu khin l do linh kin mch iu khin tiristor gy nn sai s. in p ti thu c gy mt i xng nh so snh trn hnh 3b.

in p v dng in khng i xng nh hnh 3.b cung cp cho ti, s lm cho ti c thnh phn dng in mt chiu, cc cun dy b bo ho, pht nng v b chy. V vy vic nh k kim tra, hiu chnh li mch l vic nn thng xuyn lm i vi s mch ny. Tuy vy, i vi dng in ti ln th y l s ti u hn c cho vic la chn.

Hnh 3: Hnh dng ng cong in p iu khin a- Mong mun b- Khng mong mun

khc phc nhc im va nu v vic ghp hai tiristor song song ngc, triac ra i v c th mc theo s hnh 2.B. S ny c u im l cc ng cong in p ra gn nh mong mun nh hnh 3.a, n cn c u im hn khi lp rp. S mch ny hin nay c s dng kh ph bin trong cng nghip. Tuy nhin triac hin nay c ch to vi dng in khng ln (I < 400A), nn vi nhng dng in ti ln cn phi ghp song song cc triac, lc s phc tp hn v lp rp v kh iu khin song song. Nhng ti c dng in trn 400A th s hnh 2.B t dng.

S hnh 2.C c hai tiristor v hai it c th c dng ch ni cc cc iu khin n gin, s ny c th c dng khi in p ngun cp ln (cn phn b in p trn cc van, n thun nh vic mc ni tip cc van).

S hnh 2D trc y thng c dng, khi cn iu khin i xng in p trn ti, v y ch c mt tiristor mt mch iu khin nn vic iu khin i xng in p d dng hn. S lng tiristor t hn, c th s c u im hn khi van iu khin cn him. Tuy nhin, vic iu khin theo s ny dn n tn hao trn cc van bn dn ln, lm hiu sut ca h thng iu khin thp. Ngoi ra, tn hao nng lng nhit ln lm cho h thng lm mt kh khn hn

2.3. Gii thiu v phn t bn dn triac.

2.3.1 Cu to v k hiu

EMBED Visio.Drawing.11Hnh 4: Cu to v k hiu ca triac.

Triac l linh kin bn dn tng t nh hai Thyristor mc song song ngc, nhng ch c mt cc iu khin. Triac l thit b bn dn ba cc, bn lp. C th iu khin cho m dn dng bng c xung dng (dng i vo cc iu khin) ln xung dng m (dng i ra khi cc iu khin). Tuy nhin xung dng iu khin m c nhy km hn, ngha l m Triac s cn mt dng iu khin m ln hn so vi dng iu khin dng. V vy trong thc t m bo tnh i xng ca dng in qua Triac th s dng dng iu khin m l tt hn c.

*Nguyn l hot ng.

C 4 t hp in th c th m Triac cho dng chy qua:

B2G

++

+-

--

-+

Trng hp MT2 (+), G(+). Thyristor T m cho dng chy qua nh mt Thyristor thng thng.

Trng hp MT2 (-), G(-). Cc in t t N2 phng vo P2. Phn ln b trng ni ti EE1 ht vo, in p ngoi c t ln J2 khin choBarie ny cao n mc ht vo nhng in tch thiu s(cc in t ca P1) v lm ng nng ca chng ln b gy cc lin kt ca cc nguyn t Sillic trong vng. Kt qu l mt phn ng dy chuyn th T m cho dng chy qua.

2.3.2 c tnh V-A.

Hnh 5: c tuyn V-A ca triac

Triac c ng c tnh V-A i xng nhn gc m trong c hai chiu

2.4. iu p xoay chiu mt pha ng vi ti R-L

Hnh7: Hnh dng dng in v in p i vi ti R-LKhi tiristor T1 m c phng trnh:

L + Ri = sint

i =

EMBED Equation.3sin() + Ae-

EMBED Equation.3Hng dng s tch phn A c xc nh : Khi th i = 0. Biu thc dng ti i c dng:

i =

EMBED Equation.3 [ sin() - sin()e]

Biu thc ny ng trong khong n

Gc c thay i bng cch thay v t i= 0

Sin()- sin().e- = 0

Trong biu thc trn: tg =

Tiristor T1 phi c kho li trc khi cho xung m T2, nu khng th khng th m c T2, tc

tho mn iu kin ny ta phi c:

Hnh 8: Hnh dng dng in v in p i vi ti thun tr v thun cmiu ni ln rng, ngay c trng hp ti thun tr, li in xoay chiu vn phi cung cp mt lng cng sut phn khng.

Gi tr hiu dng ca in p trn ti:

Uc = = V.

Gi tr hiu dng ca dng ti:

Ic = .()

Cng sut tc dng cung cp cho mch ti:

P = UcIc = ().(

EMBED Equation.3)

Nh vy bng cch lm bin i gc t 0 n , ngi ta c th iu chnh c cng sut tc dng t gi tr cc i P =() n 0

Di y l bng gc m ng vi tng loi ti :

PHN II: THIT K MCH

CHNG I: THIT K

1.1. S khi

1.2. Phn tch tng khi1.2.1. Khi ngun

a.S

b.Chc nng

Bin i dng xoay chiu in p 15V thnh dng mt chiu cp cho chn vo ca TCA785.

c.Nguyn l hot ng

Dng in 15V xoay chiu qua cu chnh lu 3A lm bin i t dng xoay chiu thnh dng mt chiu.Khi qua IC n p 7815 s cho dng in c in p 15V n nh.Sau khi chnh lu cu in p 15v c cho qua t 2200F san phng in p to in p n nh cho IC n p 7815 v mc song vi mt t gm loi b thnh phn sng hi ca in p xoay chiu sau IC 7815 ta mc song song vi mt led bo mch iu khin c ngun 1.2.2 .Mch lc

Vi yu cu ca ti l thit k b iu p xoay chiu cho ng c (ti R+L) nn chng em chn s dng TRIAC iu khin v s dng Triac c nhng u im sau:

- Cng sut ti l khng ln nn Triac p ng y v cng sut p ng

- Mch iu khin Triac n gin.

- Gi thnh r, vn hnh n gin.

a. S mch

b.Nguyn l lm vic

Tn hiu c a vo chn iu khin G ca Triac. Triac c nhim v iu khin m dn dng t ta nhn c gi tr in p trn ti tng ng vi gc m ca triac khi ta iu chnh bin tr V11 iu chnh rng xung vung tng ng ti trn s c th t trc hoc sau van u c :Di y l s dng sng u ra ca van khi iu chnh gc m:

Nhn t hnh trn ta thy do ti c tnh cm khm nn khi tt vn c mt phn in p tr li ca ng c .Nn c th xut hin mt vng khng hot ng nu din cm ln th mch c th khng hot ng hon ton

Nguyn nhn ca hin tng ny nh sau :

Em xin trnh by vi 2 tiristor mc song song ngc (tng t 1 triac)

Khi in p ngun U1 i du m cun dy in cm cha x ht nng lng, lm cho T1 vn dn t cho n 1 nu T1 ang dn chng t T1 ang phn cc thun v in p Ua1a2>0.Khi T1 phn cc thun chng t T2 phn cc ngc. Do trong vng t 1 cho n nu c pht xung iu khin T2 th T2 khng dn c .Phn ny em cng trnh by trn .Th 2 l do khi c in cm, dng in khng bin thin t ngt ti thi im m tiristor,in cm cng ln khi dng in bin thin cng chm. Nu rng xung iu khin hp, dng in khi c xung iu khin khng ln hn dng in duy tr,do van bn dn khng t gi dng in. Kt qu khng c dng in, van s khng m. Hin tng ny s thy cui v u chu k in p, lc in p tc thi t vo van bn dn nh. Khi kt thc xung iu khin, dng in cn nh hn dng duy tr nn van bn dn kho lun. Ch khi no in p m van ln hn dng dng in duy tr, dng in mi tn ti trong mch khc phc hin tng ny l to xung gin on bng chm xung lin tip nh hnh v di y. T thi im m van cho ti cui bn k:Di y l s :

Tu theo ti c in cm ln c no m ta thit k chn rng xung cho hp l

1.2.3.Mch iu khin

1.2.3.1.Phn tch

iu khin Triac trong s chnh lu hin nay c rt nhiu phng php khc nhau thng gp l iu khin theo nguyn tc thng ng tuyn tnh. Theo nguyn tc ny iu khin gc m ca Triac ta to ra mt in p ta dng tam gic (in p ta rng ca Urc). Dng mt in p mt chiu Uk so snh vi in p ta. Ti thi im hai in p ny bng nhau(Uk= Urc) .

Trong vng in p dng anot th pht xung iu khin cho ti cui bn k (hoc ti khi dng in bng 0) .

thc hin trn mch iu khin bao gm 3 khu c bn:

Hnh 9: S khi cc khu trong mch iu khin

* Nhim v ca cc khu trong s khi nh sau:

1. Khu ng b: C nhim v to ra in p ta Urc tuyn tnh trng pha vi in p Anot (cc G) ca Thyristor (triac)

2. Khu so snh: Nhn tn hiu in p ta v in p iu khin. C nhim v so snh gia in p ta vi in p iu khin Uk. Tm thi im hai in p bng nhau(Uk= Urc). Ti thi im hai in p ny bng nhau th pht xung iu khin u ra gi sang tng to xung v khuch i xung.

3. Khu to xung v khuch i xung:

C nhim v to xung ph hp m Triac. Xung m Triac cn c cc yu cu: Sn trc dc thng ng m bo m Triac tc thi khi c xung iu khin (Thng gp l xung kim hoc xung ch nht) rng (vi rng xung ln hn thi gian m cacTriac). Cch ly gia mch iu khin v mch ng lc (nu in p ng lc qu ln) cng sut.

1.2.3.2. Nguyn l hot ng.

Tn hiu in p cung cp cho mch iu khin c a n khi ng pha. u ra ca khi ny c in p thng l hnh sin cng tn s v c th lch pha mt gc xc nh so vi in p ngun. in p ny gi l in p ng b Vb . u ra ca mch pht in rng ca ta c cc in p rng ca ng b v tn s v gc pha vi in p ng b. Cc in p ny gi l in p rng ca Vrc. in p rng ca Vrc c a vo u vo ca khi so snh. Ti c mt tn hiu khc na l in p mt chiu iu chnh ly t ngoi. Hai tn hiu ny c mc vi cc tnh sao cho tc ng ca chng ln mch so snh l ngc chiu nhau. Khi so snh lm nhim v so snh hai tn hiu ny. Ti thi im hai tn hiu ny bng nhau th tn hiu u ra khi so snh l cc xung xut hin vi chu k ca Vrc . Xung rng ca c hai sn trong c mt sn m ti th u ra khi so snh xut hin mt xung in p th sn l sn s dng . Vy ta c th thay i thi im ca xung xut hin ti u ra khi so snh bng cch thay i Vk khi gi nguyn dng ca VrcTrong mt s trng hp xung ra khi so snh c a ngay n u cc ca thit b cn iu khin nhng trong a s cc trng hp th tn hiu ra khi so snh cha yu cu cn thit. Ngi ta phi thc hin vic khuch i thay i li hnh dng xung. Cc nhim v ny c thc hin bi mt mch gi l mch xung. u ra ca khi to xung v khuch i xung s c mt chui xung iu khin c cc thng s yu cu v cng sut, di, dc mt u ca xung. Ti thi im bt u xut hin cc xung hon ton trng vi thi im xut hin xung trn u ra khi so snh.

Ngy nay cc mch c in nh trn thng c thay th bng cc IC tch hp y cc khu, vi kt cu nh gn, gi thnh r v t c chnh xc rt cao. IC TCA 785 l mt vi mch nh vy1.2.3.3.Gii thiu TCA 785

Vi mch TCA 785 l vi mch phc hp thc hin c 4 chc nng ca mt mch iu khin: to in p ng b, to in p rng ca ng b, so snh v to xung ra.

a.K hiu v chc nng ca TCA 785.

ChnK hiuChc nngChnK hiuChc nng

1OSChn ni t9R9in tr to mch rng ca

2Qu ra 2 o10C10T to mch rng ca

3QUu ra U11V11in p iu khin

4Q

u ra 1 o12C12T to rng xung

5VSYNCin p ng b13LTn hiuiu khin xung ngn, xung rng

6ITn hiu cm14Q1u ra 1

7QZu ra z15Q2u ra 2

8VREFin p chun16Vsin p ngun nui

Hnh 13: dng sng v chc nng ca cc chn TCA785 SHAPE \* MERGEFORMAT b.Cc thng s ca TCA 785.Thng sGi tr nh nhtGi tr tiu biu

F =50Hz

Vs = 5vGi tr ln nhtn v

Dng tiu thI.S4,56,510mA

in p vo iukhin,chn11

Tr khng voV11

R110,215V10maxV

K

Mch to rng ca

Dng np t

Bin ca rng ca

in tr mch np

Thi gian sn ngn ca xung rng caI10

V10

R9

TP10

3801000

VS-2

300A

V

K

S

Tn hiu cm vo, chn 6

Cm

Cho phpV6I

V6H43,3

3,32,5V

V

rng xung ra, chn13

Xung hp

Xung rngV13H

V13L3,52,5

3,52,5V

V

Xung ra, chn 14, 15

in p ra mc cao

in p ra mc thp

rng xung hp

rng xung rngV14/15L

V14/15L

tp

tpVS-3

0,3

20

530VS-2,5

0,8

30

620,mVS-1,0

2

40

760V

V

S

S/nF

in p iu khin

in p chun

Gc iu khin ng vi in p chunVref

ref2,83,1

2 x10-43,4

5x10-4V

1/K

Tnh ton cc phn t bn ngoi:

T rng ca: C10 Min = 500pF; Max = 1F

Thi im pht xung: tTr =

Dng np t: I10 =

in p trn t: V10 =

TCA 785 do hng Siemen ch to, c s dng iu khin cc thit b chnh lu, thit b chnh dng in p xoay chiu.

C th iu chnh gc t 00 n 1800 in. Thng s ch yu ca TCA 785:

+ in p nui: US = 18V

+ Dng in tiu th: IS = 10mA

+ Dng in ra: I = 50mA

+ in p rng ca: Ur max = (US - 2)V

+ in tr trong mch to in p rng ca: R9 = 20K 500K

+ in p iu khin: U11 = -0,5 (US-2)V

+ Dng in ng b: IS = 200A

+ T in: C10 = 0,5F

+ Tn s xung ra: f = 10 500 Hz

b. S chc nng chn ca vi mch TCA785

Hnh 14: s khi chc nng chn ca tca785

1.2.3.4.S

CHNG II: CH TO MCH.2.1. Tnh ton thit k ch to m hnh

2.1.1. Tnh chn van ng lc

Da vo cc yu t c bn dng ti, s cn chn, iu kin tn nhit, in p lm vic.

P: Cng sut nh mc ca ti Pm=0.2 Kw

U: in p nh mc U=220V

cos : H s cng sut ti ly cos =0,8

Khi :

-in p lm vic cc i ca triacU = K .U = .220 = 311,13V

in p ca van cn chnU = K . U = 1.8.311,13 = 560,034 V

K l h s d tr in p .Vi phn tnh ton ny chng em ly in p d tr ca van l Kdt=1.8-Dng in lm vic ca van c tnh theo dng hiu dng

Iti=1.136 A

Vi I== 200/(2200.8)=1.136 A

Chn iu kin lm vic ca van: c cnh tn nhit khng c qut i lu Dng in nh mc ca van cn chn

Ilv =30%Idmvan = 3.786 A

Vi cc thng s trn theo datasheet cng nh ph bin ngoi th trng chng em quyt nh la chn loi van sau :

BTA-136 600E c cc thng s sau:

in p nh mc: Um = 600 V.

Dng in nh mc: Im = 4 A.

Dng in iu khin: Ik = 50 m A.

in p iu khin: Uk = 1.5V.

Dng in r: Ir = 500.

Dng in duy tr: Ih = 15 mA.

St trn van khi m: U = 1.7 V.

Thi gian gi xung iu khin: tx = 2

Tc tng in p: = 500 V/ s.

Nhit lm vic cc i: T0C = 1250C.

Trn y l thng s em chn ng vi ti l ng c in mt pha cng sut nh.cc gi tr ca ngun kh c th vt qua gi tr ny nn chng em quyt nh s dung TCA 600E lm van mch lc.

Cc gi tr trn em ly trn datasheet ca triac

Vi cc gi tr ca van u p ng v st cc thng s yu cu ca ng c nn chng em quyt nh s dng van ny trong mch

2.1.2. Chn thit b bo v.

2.1.2.1. Bo v qu nhit.

Triac lm vic vi dng in ti a Imax = 1.136 A chu mt tn hao trn van l (P1) v khi chuyn mch (P2). Tng tn hao s l:

P = P1 +P2

EMBED Equation.3 P1 = U.Ilv = 1,6.1.136 = 1,82W.

Tn hao cng sut ny sinh ra nhit. Mt khc van ch lm vic ti nhit ti a cho php l T = 1250C. Do phi bo v van bng cch gn van bn dn ln cnh to nhit.

Khi van bn dn c mc vo cnh to nhit bng ng hoc nhm, nhit ca van c to ra mi trng xung quanh nh b mt ca cnh to nhit. S to nhit ny l nh vo s chnh lch nhit gia cnh to nhit v mi trng xung quanh. Khi cnh to nhit nng ln, nhit xung quanh cnh to nhit nng ln. Nhit xung quanh cnh to nhit tng ln. Lm cho tc dn nhit ra mi trng khng kh b chm li. Din tch b mt to nhit c tnh:

Stn =

Tn hao cng sut: P = 1,82W.

chnh lch nhit so vi mi trng: = Tlv TmtC Tlv = 1250C, chn nhit mi trng: Tmt = 400C.

EMBED Equation.3 = 125 - 40 = 85 0C

Ktn: H s c xt ti iu kin ta nhit.

Chn Ktn = 8.10-4 W/cm2 0C.

Stn = = 26,76 cm2

Hnh 15: hnh dng cnh tn nhit cho triac

2.1.2.2. Bo v qu dng in cho van.*Chn cu ch tc ng nhanh bo v ngn mch ngun:

Icc = 1,1Ilv = 1,1.1,136 = 1,25 A.

Chn mt cu ch loi 1 A.

2.1.2.3. Bo v qu in p cho van.

Bo v qu in p do qu trnh ng ct Triac c thc hin bng cch mc R-C song song vi triac(hoc thyristor). Khi c s chuyn mch cc in tch tch t trong cc lp bn dn, phng ra ngoi to ra dng in ngc trong khonh thi gian ngn. S bin thin nhanh chng ca dng in ngc s gy ra sc in ng cm ng rt ln trong cc in cm lm cho qu in p gia Anot v Katot ca triac (hoc thyristor). Khi c mch R - C mc song song vi triac (hoc Thyristor) to ra mch vng phng in trong qu trnh chuyn mch nn triac (hoc thyristor) khng b qu in p.

Hnh 16: s mch ng lc c la chn

Thng thng chn R = 10 100, C = 0,11000F.

Trn y chng em xin trnh by cch tnh chn van v mch dng lc cho mch iu khin !

3 tnh chn phn t cch ly

C rt nhiu phng n cho khu cch ly c th dung phn t cch ly quang bin p xung hay vi mch cng sut nh ch cn dng diot chng ngc dng

Trong phm vi ti l ng dng vi ti cng sut trung bnh v nh p ng c tnh gn nh v gi thnh ca mch phng n s dng cch ly quang c chng em quyt nh s dng v kh hiu qu gi thnh r gn nh v cch ly an ton gia mch lc v mch iu khin t cc thong s trn chng em quyt nh s dng MOC 3021 thc hin khu cch ly ny.Sau y l mt s s kt ni trong datasheet :

y l mt s s kt ni ca MOC 3020 ng vi cc loi ti khc nhau sau y l s kt ni trong khu cch ly ca chng em

Hnh 18: S khi v s nguyn l ca moc 3020

2.2. S nguyn l ton mch

* Nguyn l hot ng

Khi cp ngun cho mch iu khin qua khi chnh lu in p 15V AC vo cc chn 13,6,16 cho TCA 785 chn 5 ca mch ni vi in p xoay chiu 15V sau my bin p to in p ng vi mch lc (mch lc v mch iu khin chung ngun) . to c xung rng ca sau khi tham kho s chn ca datasheet chng em ni chn 12 vi mt t khng phn cc 22nF to rng xung v mt t 68nF vo chn 10 to bin cho mch iu khin iu khin c triac dng 2 bin tr 50k vo chn 11 diu khin rng xung qua iu chnh gc m cho triac v t nhn c mt gi tr in p tng ng trn ti . (cc chn cn li khng dng chng em chn gii php trng khng ni mt).Xung ra t chn iu khin 14 iu chnh gc m phn in p dng ,chn 15 pht xung iu khin m phn in p m m cho triac ta c th nhn c gi tr in p tng ng t cho ti t iu chnh c tc ng c theo mun . an ton cho mch iu khin khng b in p ngc t mch lc s dng 2 diot chng ngc dng v qua mch cch ly quang s dng MOC 3020 nh chng em gii thiu.Mch lc c bo v bi cu ch 1A

iu khin tc ng c ngi iu khin ch cn vn bin tr R11 nhn c gi tr in p tng ng gc m cng nh th in p t trn ti cng ln v ngc li.Bin tr R9 iu chnh mn cho gc m nh iu chnh bin ca xung rng ca

2.3. S board

2.4. S b tr thit b

2.5. Phng hng pht trin ca tiVi mch iu o s dng IC tch hp ny chng ta c th iu khin hu ht cc loi ng c mt pha cng sut nh v va trong cc x nghip va nh .Cch khc phc hin tng khng m khi c ti l in cm ln chng em trnh by trn. Vi u im l gn nh iu khin trn c tc v di iu chnh rng .Mch cn ng dng iu khin nhit ca l in tr v ng dng trong k thut chiu sang.Mch c th chuyn thnh mch iu o xoay chiu 3 pha khi ta nhn 3 mch iu khin.dng cho cc ng c ba pha cng sut ln trong cng nghip (lc ny van bn dn l tiristor).Thc t th nhu cu iu khin tc ng c trong thc t l kh ln .Vi mch iu khin ny chng ta c th iu khin hu ht cc loi ng c.u im ca mch l gi thnh hp l nh gn v rt d vn hnh cng nh sa cha.LI KT

Nh vy, sau hai thng nhn v thc hin mn hc vi ti : Nghin cu, thit k, ch to b iu chnh in p xoay chiu iu khin ng c mt pha bng cc phn t bn dn cng sut cho n nay chng em hon thnh. Cng vi s n lc c gng ca bn thn, s gip ca bn b trong lp, v c bit vi s gip nhit tnh, tn tm ca c gio: Nguyn Th Thanh Tm chng em thc hin c mt cch tng i tt nhng yu cu c bn m ti t ra.

Nhng bn cnh , trong thi gian thc hin ti, do vi trnh kin thc cn c hn nn khng trnh khi nhng sai st . Do chng em rt mong s nhn c nhng kin ng gp ca cc thy, c gio v cc bn ti ca chng em ngy mt c hon thin hn.

Chng em cng xin c cm n tt c cc thy, cc c gio thuc b mn in t cng sut v truyn ng in gip chng em ,tn tnh ch bo chng em c th hon thin c ti n ny.

Mt ln na, chng em xin chn thnh cm n!

Hng yn, thng 11 nm 2012Nhm sinh vin thc hin n : Hong Lng Thi SnTrn Vn Thoi

TI LIU THAM KHO Ti liu tham kho:

in t cng sut-Nguyn Vn Doanh

in t cng sut Nguyn Bnh

Gio trnh truyn ng in- Cng Thng-Nguyn Phng Tho

www.alldatasheet.com/www.dientuvietnam.net/www.tailieu.vn/www.hoiquandientu.com/

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EMBED Visio.Drawing.11

GV hng dn: Nguyn Th Thanh TmTrang 2

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