1384970

LI NI U

Chng 2: La chn phng n thit k

TI

Thit k b ngun cho my hn t dng dng thyristor m bo c cc yu cu cng nghSV:inh Trng Thun

LI NI UTrong nhng nm gn y vi s pht trin ngy cng mnh m ca nn kinh t x hi, cc lnh vc khoa hc, k thut ng dng vo cc ngnh cng nghip ni chung v ngnh cng nghip in t ni ring, cc thit b in t cng sut c ng dng v c ch to ngy cng nhiu, c bit l ng dng vo cc ngnh kinh t quc dn v i sng, lm cho yu cu v s hiu bit v thit k cc loi thit b ny ht sc cn thit i vi k s ngnh in

Cng vi s pht trin ca ngnh in t cng sut th vic ng dng rng ri cc loi my hn vo cng nghip l ht sc quan trng ni mt cch c th hn l i vi cc ngnh c kh ch to.

hiu r c vai tr ca in t cng sut v cc loi my hn trong c hn t ng. Trong bn n mn hc ny c s hng dn ca thy Mnh Cng vi ti :

Thit k b ngun cho my hn t dng dng thyristor m bo c cc yu cu cng nghEm c a ra mt s phng n trnh by trong bn n thit k. Tuy nhin vi s hiu bit v nhng kin thc hc cn hn ch nn bn n ca em khng trnh khi nhng thiu st nht nh.Em rt mong nhn c s gp v ch bo ca cc thy c gio bn n ca em c hon thin hn. Em xin chn thnh cm n !

Sinh vin

inh Trng Thun

Chng 1TM HIU CNG NGH

1.1.Nguyn l ca hn mt chiu

a. nh ngha Hn l qu trnh ni hai vt liu bng kim loi vi nhau bng cch nung nng ch ni n nng chy hoc gn nng chy

b. Nguyn l ca hn mt chiu

L mt dng phng in trong cht kh vi mt dng in ln (102 n 103A/mm2 ) to hin tng h quang in lm nng chy kim loi... iu kin bnh thng cht kh hu nh khng dn in. Nu t ln hai in cc trong mi trng khng kh mt in trng c cng ln th c th ph v cch in ca cht kh v c kh nng dn dng in ln, ph thuc vo tnh cht cht kh, p sut ca n, nhit mi trng, vt liu lm in cc, ln ca cng in trng

c tnh V-A, c tnh tnh ca h quang:

gim c U mi m vn gy c h quang ngi ta cho hai in cc tip xc nhau gy ra I on mch. Nu I on mch ln s nung kim loi ch tip xc nng chy. Thng s dng on c tnh CD hn. Hnh 1.1 c tnh VA Trong tt c cc phng php ghp ni cc chi tit vi nhau th phng php hn in c nhiu u vit hn tt c.Chnh v vy m ngy nay n c s dng rng ri trong hu ht cc ngnh cng nghip, xy dng, ch to my ... v hn in tr thnh mt phn tt yu khng th thiu. Phng php hn in c nhng u im ni bt sau:+ Kh nng ghp ni cc chi tit cao vi cht lng mi hn tt .

+ Chi ph sn xut h , cho nng sut lao ng cao .

+ t tiu hao nguyn vt liu .

+ Bo v mi trng v sinh cng nghip .

+ Cng ngh n gin, kh nng c gii ha v t ng ha cao1.2. Cu trc my hn

Ty theo nhu cu s dng v tiu chun ca nh sn xut nn cu to cc loi my hn cng khc bit nhau.Tuy nhin cu to my hn c th chia thnh cc phn chnh sau:

- Ngun in c th l xoay chiu AC hoc mt chiu DC c to ra t b bin i

- M hn v kp mass cng cp dn in

- Bnh kh v van iu p c th l kh Argon tinh khit, Heli tinh khit, CO2 tinh khit, Hn hp Argon + heli, Hn hp Argon + CO2

Ngoi ra cn cc b phn khc nh v, ng h, lm mt, cc nt iu khin...vv

1.3. Phn loia. Theo ch hn ngi ta chia lm 2 loi

-Kiu thng: dng in c khng ch theo dng hnh thang: c im tng dng, duy tr v gim dn v khng

-Kiu c xung: cng nh trn nhng dng khng ch c iu ch mt tn s no . rng v chu k cng c th thay i cho ph hp vi vt

b. Phn loi theo kiu my : c 3 loi

-My dng chnh lu diode

-My dng chnh lu bng thyristor

-My inveter

c. Phn loi theo dng hn: c 2 loi

-My hn DC

Inveter AC--->DC--->AC--->DC

Thyristor AC--->DC

+- My hn AC--->DC--->AC1.4. Cc yu cu khi lm vic Ngun hn phi m bo dng h quang c ch mi v ch h quang n nh

m bo an ton khi lm vic ch lm vic cng nh ch ngn mch lm vic

Ngun hn phi c cng sut ln

Ngun hn phi c kh nng iu chnh c dng hn

ng c tnh ngoi ca ngun hn phi p ng c tng phng php hn c th y

l hn t ng th ng c tnh ngoi phi cng

CHNG 2:

LA CHN PHNG N THIT K

cp ngun cho ti mt chiu, chng ta cn thit k cc b chnh lu vi mc ch bin i nng lng in xoay chiu thnh nng lng in mt chiu. Cc loi b bin i ny c th s dng cc s chnh lu sau y: Chnh lu tia ba pha c iu khin

Chnh lu cu ba pha iu khin khng i xng.

Chnh lu cu ba phan c iu khin.

2.1. Nhn xt cc s a. u v nhc im ca chnh lu tia 3 pha

-u im : so vi chnh lu mt pha th chnh lu tia 3 pha c cht lng in p mt chiu tt hn, bin in p p mch thp hn, thnh phn sng hi bc cao b hn, vic iu khin cc van tng i n gin-nhc im : s chnh lu tia 3 pha c cht lng in p ra ti cha tht tt lm, khi cn cht lng in p ra tt hn th dng s nhiu pha hn.

b.u nhc im ca s cu ba pha khng i xng

- u im:s c t knh iu khin hn so vi s cu 3 pha i xng nn iu khin d dng hn,u t t hn

- nhc im: in p ra khng c tt nh s cu 3 pha i xng,di iu chnh in p khng ln lmc. u v nhc im ca chnh lu cu 3 pha i xng- u im : cht lng in p tt nht, h s p mch thp, thnh phn sng hi nh, hiu sut s dng bin p tt nht

- nhc im : cn phi m ng thi hai van theo ng th t pha nn rt phc tp, n gy kh khn khi ch to vn hnh v sa chaVi bi cho : thit k b chnh lu dng cho my hn 1 chiu c cc thng s :

Uvo(v) Ud0(v) Im( A )

3x380 75 200

S b ta c cng sut mt chiu Pd = Ud . Id =75 . 200=15000wTheo cc ti liu cho thy :

- Cng sut > 5 KW ta dng s chnh lu ba pha

- n p mt chiu ra ti cao > 30V nn dng s hnh cu

- in p chnh lu nh hn nhiu so vi li nn phi s dng BA ngun

==> V vy ta chn s cu ba pha c iu khin l thch hp nht2.2. S CU 3 PHA C IU KHIN:

a. S v th

Hnh 2.1 S

b.Cng thc tnh ton:( p dng gio trnh in t cng sut ca thy

Trn Trng Minh V Minh Chnh - Phm Quc Hi )

Nu

( khi gc m = 0 )

Hnh 2.2 th in p

2.3. Tnh ton cc tham s ca s

2.3.1 Pha ngun:MBA ( chn MBA ba pha ba tr )

- in p s cp MBA: U1 =3 X 380 (V)

- Cng sut mt chiu:

W - Cng sut MBA:

VA- Ta c phng trnh cn bng in p:

Vi

,

=64,5 (V)

Vi s 3 pha c iu khin ta c cng thc sau: m

=

- in p pha th cp MBA l :33 (V )

Dng hiu dng th cp l:

- Dng s cp MBA:

Hnh 2.3 : S mch lc

I1 = I2.Kba = = = 14,1(A)

- S vng / vn: ( vng/ vn )

- S vng dy s cp: ( vng / vn )

- S vng dy th cp: ( vng / vn )

2.3.2.Pha mch lc: tnh ton chn van

- in p chnh lu khng ti :

-in p ngc t ln van l: Ungmax = U2 = .33 =80.5 ( v)

- in p ngc ln nht m van phi chu:

EMBED Equation.3=1,6 . 80.5 = 129 (V) vi kdtU : h s d tr in p chn kdtU = 1,6

- Dng in lm vic ca van: : ITBVAN 66,6 (A)

Chn ch lm mt cho van l qut thng gi v cnh tn nhit, chn h s d tr dng in: KDTI = 2 vy van phi chu c dng in l: : IV = KDTI . ITBVAN = 2.66,6 = 133,2 (A)

chn thyristor T10-80 do nga ch to ( ph lc 2trang 432 sch hng dn thit k in t cng sut ca thy Phm Quc Hi ) vi cc thng s sau:

- Umax = 1200V Imax = 1200A

(U =2.7V Igm = 150 mA Ugm =4 V dU/dt = 50 1000 V/(s di/dt = 40 - 200 A/(s Toff =150 - 70(sa. Tnh ton bo v:

* Bo v dng in di/dt = 40 - 200 A/(s cho van:

+Aptomat dng ng ct mch ng lc, t ng bo v khi qu ti v ngt mch Thyristor, ngn mch u ra b bin i, ngn mch th cp my bin p,

+ Chn Aptomat c:

Im = 1,1.I1 = 1,1.14,1 = 15,51 (A)

+ Chnh nh dng ngn mch: Inm = 2,5.I1 = 2,5.14,1 = 35,25(A)

+ Dng qu ti:

Iqt = 1,5.I1 = 1,5.14,1 = 21,15 (A)

* Bo v qu in p cho van: Ngi ta chia lm 2 loi nguyn nhn gy ra qu in p

+Nguyn nhn bn trong: s tch t in tch trong cc lp bn dn. Khi kho thyristor bng in p ngc, cc in tch ni trn i ngc li to ra dng in trong khong thi gian rt ngn. S bin thin nhanh chng ca dng in ngc gy ra sc in ng cm ng rt ln trong cc in cm. Do vy gia anot v catot ca thyristor xut hin qu in p.

+Nguyn nhn bn ngoi: Nhng nguyn nhn ny thng xy ra ngu nhin nh khi ct khng ti mt my bin p trn ng dy, khi c sm st.....

bo v qu in p , ngi ta thng dng mch RC u song song vi Thyristor nhm bo v qu in p do tch t in tch khi chuyn mch gy nn. Mch RC u gia cc pha th cp MBA l bo v qu in p do ct khng ti MBA gy nn. Trong mch bo v qu in p ta chn R=80( , C=0,25(F

2.4.Tnh ton cun khng lc:

Vi yu cu ca in p hn c Kmv = , h s san bng ca mch lc : Ksb = , vi s cu 3 pha iu khin i xng ta c: Kmr= 0,057 Ksb =

ti c in tr tng ng: ta c gi tr in cm:

vy : in cm yu cu ca cun khng lc :

dng nh mc chy qua cun khng: Idm=200 (A)

bin dng xoay chiu bc 1: I1m=10%Idm=20 (A)

do dng in cun khng ln v in tr b do ta c th coi tng tr cun khng xp x in khng:

Zl Xl = wl = 2..f.5,12.10-4 = 0,16

in p ri trn cun khng lc: = 0,16.= 2,2 (v )Chng 3:

Tnh ton mch iu khin

3.1-Nguyn tc iu khin: Hnh di l s cu trc v th minh ho. y khu Ut to ra in p ta c dng c nh (thng c dng rng ca, i khi hnh sin) theo chu k do nhp ng b ca ub. khu so snh ss xc nh thi im cn bng ca 2 in p Ut v Uk pht ng khu to xung tx. nh vy trong nguyn tc ny thi im pht xung m van hay gc iu khin thay i do s thay i tr s ca uk, trn th l s di chuyn theo chiu dc ca trc bin . a s mch iu khin thc t s dng nguyn tc ny

Hnh 3.1 S khi

Hnh 3.2 S in p

3.2. Thit k mch iu khin:

3.2.1. Tnh ton cc khu trong mch iu khin:

a.Tnh ton khu ng b:

Tnh ton:

Chn gc duy tr v thot nng lng ( =5th in p U1 t vo ca (+) ca b so snh l: U=Umaxsin 5 =.12.sin 5 = 1,48(v)

ta c:

Hnh 3.3 S mch(

(

chn R2 = 5 (k() , VR1 = 50 (k()

in tr u vo ca OA1 l ln ta chn in tr R c gi tr l 100(k() Hnh 3.4 S in p

b.Khu to in p rng ca: Tnh ton: Chu k ca in p li l: tng ng vi 360

Hnh: 3.5 Smch

Hnh: 3.6 S in p ( Chu k ca in p rng ca l : tng ng vi 180

mt khc Trc = Tp + Tn trong : tp - thi gian phng ca t c1 Tn - thi gian np ca t c1 nh trn ta chn ( = 5 tc l Tn = 10 ( Tp = 180 - 10 = 170tng ng vi thi gian l: Tp = Tn =

chn gi tr ca t c1 = 0,2f

gi dng n trong qu trnh np l In. sau khong thi gian t = tn = 0,6 (ms) th in p trn t t gi tr Uco vy ta c:

chn R3 c gi tr l 3,5 k(

gi dng n trong qu trnh phng l ip. sau khong thi gian t = tp = 9,4 (ms) th in p trn t v gi tr 0 vy ta c: Ucp = =0

ta c:

EMBED Equation.3

chn R4 = 20 k(, vr2 = 50 k( c th iu chnh cc. Khu so snh: m bo cho dng in i vo cc ca ca khuych i thut ton nh hn 1mA ta chn R5=R6=15 k( Hnh 3.7 S mch

Hnh 3.8 S in p d. Khu pht xung chm:

Hnh 3.9 S mch Hnh 3.10 S in p

Hnh 3.11 S to xung chmTnh ton:

chu k dao ng:

chn tn s pht xung l f = 10 Khz

(

theo kinh nghim thng chn R9 + R10 c 20 k(, gim chnh lch gia 2 ca vo ca OA chn R10 nh hn R9.vy chn R10 = 5 K(, r9 = 15 K( , chn tr s t in c2 l 10 nf( (()

chn tr s ca r8 l: 2,5 k(, c sn xung dc ng ta nn s dng loi OA c tham s v tc tng p ln (nh lF351) hoc dng comparator (nh LM301, LM339), cc loi OA thng dng nh LM324, (a741 cho xung khng tht dc vi khu vc tn s trn 10 (khz)

e. Khu trn xung:

Khu trn xung s dng IC cc cng AND c 3 u vo vi cc thng s: ngun nui IC : Vcc = 3(15 (v), ta chn: Vcc = 12 (v).

+ nhit lm vic : - 40o c ( 80o c

+ in p ng vi mc logic 1: 2.5(4,5 (v).

+ dng in nh hn: 1 ma

Bng chn l ca cng AND:

x1x2y

111

100

010

000

f. Khu phn hi: Hnh 3.12 S mch* Nguyn l hot ng ca khu phn hi :

Ly in p phn hi t ngun hn thng qua in tr shunt, v in p ny nh nn ta cho qua b khuch i c in p thch hp. tip theo in p phn hi c a vo b cng (o) vi in p m ta t cho ngun hn lm vic.Sau in p phn hi c a qua khu PI loi b cc sng nhiu c tn s cao lm cho mch tng tnh n nh

chn in p trn in tr shunt urs = 2,5 v

ta c: Rs = = 0,0014 Prs = 1747 2.0,0014 = 4272 w

chn: Rs = 0,0015 v Prs = 10 kw

g.Khi ngun:

Hnh 3.13 S mch

* Tnh ton bin p

Cng sut cp cho cc khi l rt nh, thng thng ta chn thng s ca cc bin p ca cc khi nh sau:

Khu n p:

U=17 v; I=0,6 A cng sut ca khu n p l:

P=U.I=17.0,6=10,2 (w)

Khu ngun cng sut :

U=10 v; I=1 A cng sut ca ngun n p l:

P=U.I=10.1=10 (w)

Khu ng pha:

U=12 v; I=0,1 A

cng sut ca ngun ng pha l:

p=U.I=24.0,1=2,4 (w)

==>Tng cng sut ca c ba khu l:

P= P +P+ P=10,2 + 10 + 2,4 = 22,6 (w)

dng in s cp trong my bin p l:

* Tnh ton khu chnh lu v n p:

To ngun nui e=12 V, ta dng mch chnh lu cu 1 pha dng diode, in p th cp my bin p ngun nui: U2 =17 v

n nh in p ra ca ngun nui ta dng 2 IC n p 7812 v 7912, cc thng s chung ca vi mch ny:

+ in p u vo : Uv = 7(35 (v).

+ in p u ra : Ura = 12(v) vi IC 7812.

Ura = -12(v) vi IC 7912

+ dng in u ra: Ira = 0(1 (A).

t in C4, C5 dng lc thnh phn sng hi bc cao.

chn: = c: 50v/1000

= c: 25v/1000

==

chn C4 c: 25v/1000

cc diode D1 ( D8 chn loi diode thng thng c cc thng s:Itb = 1A , Um = 200 vh.Khuych i xung & bin p xung:

*.Bin p xung:

Theo phn tnh ton mch lc ta chn van thyristor T10-80tham kho cc ti liu cho thy t s bin p xung thng p dng m =1(3 l tt nht.

y ta chn m = 2 .Vy gi tr dng s cp ca BAX

I1 = I2 / m = 150 / 2 = 75 (mA)

gi tr in p s cp ca BAX:

U1 = U2 .m = 4. 2 = 8 ( v )

cng sut ca BAX:

S = U1 . I1 = 0,075 . 8 = 0,6 (VA )

chn vt liu li bin p xung l ferit lm vic trn mt phn ca c tnh t ha: Bs = 0,45 t, t thm (A = 6000 a/m, din tch li 1cm2.

s vng dy cun s cp BAX:

Hnh 3.14: S mch

trong : Tx l chiu di xung truyn qua my bin p thng c gi tr t 10 n 600(s. y ta chn tx l 350 (s

S : l tit din li ferit, thay s vo ta c:

+ s vng dy cun th cp BAX:

(vng)

EMBED Equation.3 + gi tr trung bnh s cp v th cp BAX

EMBED Equation.3 *.Khuych i xung: chn Ecs = 10 v

ta c:

chn TR2 loi H1061 vi cc thng s:

Uec = 35 (v)

Iec = 2 (A)

( = 120 ( y s dng ( = 10.)

ta c: ibt2 = iect1 = 15 (mA)

chn TR1 loi C828 vi cc thng s:

Uec = 35 (v)

Iec = 150 (mA)

( = 100 ( y s dng ( = 10.)

chn R12 = 10 k

3.2.2 S nguyn l v thuyt minh:

a. S

Hnh 3.15 S nguyn l mch iu khin

Hnh 3.16 S in p

b: Thuyt minh:

Khi cp ngun vo s cp ca bin p ng pha, pha th cp ca bin p c h p. sau khi qua mch chnh lu c im trung tnh in p U1 l in p mt chiu na hnh sin. in p mt chiu na hnh sin ti U1 c a vo cc (+) ca OA1 so snh vi in p phng U c t vocc (-) ca OA1 do E1, VR1 v R2 to ra. kt qu ta c tn hiu u ra U2 ca OA1 c dng xung vung ng b vi li.

in p dng xung vung sau khi c to ra khu ng b trc c a vo khu to in p rng ca. Khi U2 c gi tr m, diode D3 m, t C1 c np theo chiu t U3 qua t C1 qua R3 qua diode D3 v U2. Khi U2 c gi tr dng,transistor T m diode D3 kho lc ny t C1 phng t + C1 qua transistor T v C1 .kt qu ta c U3 c dng in p rng ca. in p iu khin c ly t in p phn hi trn in tr shunt c khuych i ln c ln thch hp, sau khi qua khu khuych i o v khu PI lc sai s ng ta c Uk c dng ng thng.

in p rng ca U3 c a vo ca (-) ca OA3 v so snh vi in p iu khin Uk c a vo ca (+). khi U3 > Uk th in p u ra ca OA3 l U4 c gi tr m. Ngc li, khi U3 < Uk th in p u ra U4 c gi tr dng. Kt qu ta c U4 c dng xung vung.

Khu pht xung chm c tc dng to ra chm xung di s phng np ca t C2. d9 c tc dng loi b xung m. Do tn hiu in p U6 c dng xung chm dng. in p U4 c trn vi xung chm U6 bi IC4081 ri c a qua tng khuych i do tn hiu xung vn cha ln kch m thyristor.

Tng khuych i gm cc transisto mc theo kiu dalington, xung dng c t vo baz ca TR1 lm TR1 m ng thi TR2 m theo khi c xung i vo bin p xung. trn cun th cp ca bin p xung c xung kch m thyristo. Khi in p trn bin p xung gim t ngt, cun dy ca bin p xung xut hin sc in ng cm ng ngc du lc diode D4 v D7 c tc dng tr ngc in p dp tt sc in ng bo v cc transistor khi b qu p. Kt lun

Sau mt qu trnh hc tp v nghin cu, cng vi s hng dn tn tnh ca cc thy c gio trong b mn c bit l thy Mnh Cng v s gip ca cc bn cng nhm, em hon thnh cc nhim v c giao ca bn n : Thit k b ngun cho my hn t ng.Trong qu trnh thc hin do trnh v hiu bit cn hn ch nn chc chn khng th trnh khi nhng thiu st, em rt mong nhn c nhng kin ng gp ca cc thy c gio v cc bn bn n ny c hon thin hn.

Em xin chn thnh cm n!

H Ni, ngy 3 thng 9 nm 2012

Sinh vin:

inh Trng ThunTi liu tham kho :

1. in t cng sut V Minh Chnh, Phm Quc Hi, Trn Trng Minh.

Nh xut bn khoa hc k thut.

2. in t cng sut Nguyn Bnh.


3. Gio trnh in t cng sut Trn Trng Minh

Nh xut bn gio dc.

4. Bi ging hng dn thit k mch in t cng sut - Phm Quc Hi.

5. Thit k my bin p Phm Vn Bnh, L Vn Doanh.


MC LC

Li ni u..................................................................................................................................1Chng 1 Tm hiu cng ngh................................................................................................21.1. Nguyn l ca hn mt chiu..........................................................................................................2

1.2.Cu trc my hn..............................................................................................................................2

1.3. Phn loi my hn...........................................................................................................................3

1.4.Cc yu cu khi lm vic..................................................................................................................3

Chng 2- La chn phng n thit k................................................................................4

2.1. Nhn xt cc s ...........................................................................................................................4

2.2. S cu 3 pha c iu khin.........................................................................................................5

2.3. Tnh ton cc tham s ca s ......................................................................................................6

2.4. Tnh ton cun khng lc................................................................................................................8

Chng 3- Tnh ton mch iu khin....................................................................................9

3.1. Nguyn tc iu khin.....................................................................................................................9

3.2. Thit k mch iu khin................................................................................................................9

3.2.1 Tnh ton cc khu trong mch iu khin....................................................................................9

3.2.2 S nguyn l v thuyt minh....................................................................................................17

Kt lun...............................................................................................................................................20Ih

A

B

C

D

EMBED Equation.3

EMBED AUTOCAD.DRAWING.17

EMBED AutoCAD.Drawing.17

EMBED AutoCAD.Drawing.17

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1384970