Bien Doi Dien AP DC-DC _1

8/3/2019 Bien Doi Dien AP DC-DC _1

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N IN TCNG SUT 2BBMGIM 1 CHIU

GVHD: Th.S NGUYN TH THANH LI Page 1


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I. GII THIU V BBM XUNG 1 CHIU


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2.Mch bm gim 1 chiu:

- Mch bm gim lm gim tc ng c t gi tri nh mc n gi tr nhtnh

2.1 mch iu khin bm gim 1 chiu:

-Gm c cc khu:

+ Khu to xung

+ Khu to p rng ca

+ Khu so snh


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CHNG 3: PHN TCH CC KHU TRONG MCHIU KHIN

I. KHU TO DAO NG:

-

- Mch ny gip to xa rung vung c tn hiu dng logic 0-1 iu khinC828 bn khu to in p rng ca


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IC thi gian 555 c du nhp vo nhng nm 1971 bng cng tySignetics Corporation bng 2 dng sn phm SE555/NE555 v c gi l my thi gianv cng l loi c u tin. N cung cp cho cc nh thit k mch in t vi chi phtng i r, n nh v nhng mch t hp cho nhng ng dng cho n n v khngn nh. T thit b ny c lm ra vi tnh thng mi ha. 10 nm qua mt s nhsn sut ngng sn sut loi IC ny bi v s cnh tranh v nhng l do khc. Tuy thnhng cng ty khc li sn sut ra nhng dng ny. IC 555 hin nay c s dng khph bin cc mch to xung, ng ct hay l nhng mch dao ng khc.

1. Thng s

+ in p u vo : 2 - 18V ( Ty tng loi ca 555 : LM555, NE555, NE7555..)

+ Dng tiu th : 6mA - 15mA

+ in p logic mc cao : 0.5 - 15V


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+ in p logic mc thp : 0.03 - 0.06V

+ Cng sut tiu th (max) 600mW

2. Chc nng ca 555

+ To xung+ iu ch c rng xung (PWM)

+ iu ch v tr xung (PPM) (Hay dng trong thu pht hng ngoi)

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 dngnh 1 chn cht hay ng vo ca 1 tn so p.Mch so snh y dng cc transitor PNPvi mc in p chun l 2/3Vcc.+ Chn s 3(OUTPUT): Chn ny l chn dng ly tn hiu ra logic. Trng thi ca tnhiu 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 nyko 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 ngra mc thp. Cn khi chn 4 ni vo mc p cao th trng thi ng ra ty theo mc ptrn chn 2 v 6.Nhng m trong mch to c dao ng thng hay ni chn nyln VCC.+ Chn s 5(CONTROL VOLTAGE): Dng lm thay i mc p chun trong IC 555theo cc mc bin p ngoi hay dng cc in tr ngoi cho ni GND. Chn ny c thkhng ni cng c nhng m gim tr nhiu ngi ta thng ni chn s 5 xungGND 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 vcng 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 thn 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 hotng. Khng c chn ny coi nh IC cht. N c cp in p t 2V -->18V (Ty tng


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loi 555 nh thp nht l con NE7555)

Nhn vo s mch trn ta c cng thc tnh tn s , rng xung.

+ Tn s ca tn hiu u ra l

f = 1/(ln2.C.(R1 + 2R2))


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- rng xung ca mch ty thuc vo R1,R2 v C nn ta c:

+ Chu k ca tn hiu u ra : t = 1/f

+ Thi gian xung mc H (1) trong mt chu k

t1 = ln2 .(R1 + R2).C+ Thi gian xung mc L (0) trong 1 chu k

t2 = ln2.R2.C

Khu to xung c m phng trong protues:

Mch thc hin khu to xung


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II. KHU TO IN P RNG CA:

Ta chn mch nh hnh vdi y:

- Khi tn hiu t U3 kch vo chn B ca C828 ta c nh sau:- Nu tn hiu t U3 vo chn B l 1 tc l c828 dn th dng t ngun Vcc s

khng i qua t lc ny t s xin- Nu tn hiu t U3 vo chn B l 0 tc l c828 ng th dng t ngun Vcc s i

qua t lc ny t s np in

Dng song ra ca mch ny l rng ca tuyn tnh nn c dng nh sau:


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-

Mch thc hin khu to in p rngca:

III. KHU SO SNH


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U2: Uta hay cn gi l Urc

Udkl U c ly t bin trc ththay i in p

U3: l Uss


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-Dng Lm339 lm khu so snh, LM339 tch hp 4 b so snh ,trong mchny ta dng chn 6 a vo Urc chn 7 a vo Udk ,chn 12 c cp ngun12V chn 3 cp 0V,dng 1 b so snh

MCH KHU SO SNH

Uss c m phng trong protues


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-Uk c a vo chn 7 v Urc c a vo chn 6,2 xung ny c a quabso snh to xung vung c thiu chnh c rng xung nhm ngct van bn dn

-OPTO dng cch ly mch iu khin v mch iu khin nhm bo v mchiu khin

Mch Khu so snh v Udk


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IV. KHI TO UdkCho dng in p ra 1 chiu c bin 5-10V

Dy xung vung c T iu chnh c

-Nhim v ca Udk l to ra in p DC so snh vi in p rng ca to nnxung vung c bin iu chnh c


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CHNG 4: MCH NG LC1.Mch nguyn l:

- Kha bn dn cng sut c nhim vbm in p DC 24V t ngun 24v bngvic ng ngt van bn dn lm cho in p ra c ththay i c nh vic tnggim rng xung v dn n iu khin c ng c theo mun.

- Khi kha IGBT dn tc l lc ny Vo =Vi ,ng c c in th cao nht,lc nycun cm trong ng c s np in

- Khi kha IGBT ng tc l lc ny Vo=Vl,in thng c bng in th trongcuc cm phng ra dng in cho ng c

- Vic thay i rng xung hay thay i thi gian ng ngt slm thay i gi trtrung bnh ca Vo ng ra lm gim in th ng ra dn n iu chnh c ngc

- ng c ban u c cp ngun 24V- iu chnh c ng c ta cn iu chnh bin trUdk nhm to ra tn s

ng ngt hay rng xung thay i c


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- cung cp ngun 24 V cho ng c ta c th dng Ngun pin 1 chiu 24V hayc th chnh lu t 220V Ac xung 24DC qua bin p

- cung cp ngun 12V cho mch iu khin ta cng dng mch chnh lu t220V xung 12V DC cp cho mch iu khin,lu vi mch iu khin thdo yu cu ngun cp vo phi n nh nn lu thm nn dng cc n p c song ra tt hn

Mch ngun 24v cung cp cho ng c v mch ng lc tch hp


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Mch ngun 12V Dc cung cp cho mch iu khin

Bien Doi Dien AP DC-DC _1

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