khuech dai cong suat

7/30/2019 khuech dai cong suat

1/20

Chng 2 Mch khuch i cng sut

Bin son: Th.S Vit H Bm: K thut in t


2/20

NI DUNG

2.1. nh ngha v phn loi 2.2. Mch khuch i ch A 2.3. Mch khuch i ch B (AB)

2.4. Mch khuch i ch C


3/20

2.1. NH NGHA V PHN LOI a. Khinim

Lmch khuch i tng cuicng

Tora cngsutcungcpcho ti(vi Wattnvi trmWatt), inp vcng dngin tng i ln Mch khuch itnhiu ln: khngs dng s tng ng ng caTransistor ms dng phngphp th gii quytbi ton

b. Phnloi Ch A: Transistor c phn cc cng tuyn tnh. Tn hiu c khuch i gn nh tuyn

tnh. Dng tn hiu ra c gi nguyn ch bin i v bin so vi tn hiu vo. Ch ny chiu sut thp (vi ti in tr di 25%) nhng mo phi tuyn nh nht. im lm vic tnhtrong ch A phi nm gia ng ti tnh. Ch B: Transistor c phn cc vng ngt. Tn hiu ra ch c trong mt na chu k (mhoc dng). Ch ny c hiu sut ln (78%), tuy mo xuyn tm ln nhng c th khc phc bng cch kt hp vi ch AB hoc dng hi tip m. Ch AB: C tnh cht chuyn tip gia ch A v ch B. Transistor c phn cc gn

vng ngt tham gia vo vic gim mo khi tn hiu vo c bin nh. Tn hiu ra c hnmt na chu k. Ch C: Transistor c phn cc di vng ngt. Tn hiu ra ch c trong nh hn mt nachu k, hiu sut ln (>78%) nhng mo rt ln. Mch ch C c dng trong cc mchkhuch i cao tn c ti l cc khung cng hng chn lc tn s mong mun v t hiu sutcao.Ch D: Transistor lm vic nh mt kho in t ng m. Di tc dng ca tn hiu voiu khin transistor thng bo ho l kho ng, dng IC t cc i, cn kho m khi transistor ngt, dng IC = 0.


4/20

2.1. NH NGHA V PHN LOI Phn loi mch khuch i cng sut theo v tr im lm vic

Dng tn hiu ra ca cc mchkhuch i cng sut

I C

U CE

A

ABB

C V ng ngt

V ng b oha

Gi i h ncng sut


5/20

2.1. NH NGHA V PHN LOI


6/20

2.1. NH NGHA V PHN LOI Cc tham s ca mch khuch i cng sut

H s khuch i cng sut:

Hiu sut ca mch:

Cng sut tiu tn cc i ca Transistor L cng sut ln nht m Transistor c th chu cL mt tham s rt quan trng i vi mch khuch i cngsut Nu Transistor lm vic vt qua gii hn ca ng ngcng sut cc i th Transistor s b hng do qu nhit

i

oP

P

PK

%100dc

o

PP

m ax DP


7/20

2.2. MCH KHUCH I CH A Mch khuch i ch A ti in tr:

Mch khuch i ch A ghp bin p


8/20

MCH KHUCH I CH ATI IN TR(1)Ti l in tr, thng c gi trnhim cng tc tnh nm chnhgia ng ti tnh

vs

R 2

R

V

R

R

Q

0

C1

1n

1

CC

L

E

)16,8,4(

p L E

CC CQ I R R

V I 2

1 pCC CEQ U V U 2

1

L pc it I i sin

t I I i I i pCQcCQC sin

t U u pce sin

t U U uU u pCEQceCEQCE sin


9/20

MCH KHUCH I CH ATI IN TR(2) Cng sut xoay chiu trn ti:

Cng sut ngun mt chiu cung cp cho mch

Hiu sut ca mch

2

2

2

2

8

1

.2

1

2

1

2

1

L E

LCC

L L E

CC L po

R R

RV

R R R

V R I P

)(22

1.

2

L E

CC

L E

CC CC CQCC dc R R

V R R

V V I V P

L E

L

dc

o

R R R

PP

4

1

%25

0

ma x

ma x

E R


10/20

MCH KHUCH I CH ATI IN TR(3) Cng sut tiu tn tc thi trn Transistor

Cng sut tiu tn trung bnh trn Transistor:

Phng trnh ng ti tnh:

Phng trnh ng ti ng:

C CE Q iu p

t I Vcct t I U t I I t U U p

CQCQCEQ

pCQ pCEQQ

2sin12

sin1sin1.

sinsin

CQCC T

QQ I V dt t pT P 01

CE C U f I

E LC CC CE R R I V U E LCC

CE E L

C R RV

U R R

I 1

)( CE C u f i

Lcce Riu

E CQCC LC E CQCC LCQc

E LCQCC LcCEQceCE

R I V Ri R I V R I i

R R I V RiU uu .


11/20

MCH KHUCH I CH ATI IN TR(4) Phng trnh ng ti ng:

H s gc ca ng ti tnh:

H s gc ca ng ti ng:

ng ti ng v ng ti tnh giao nhau ti im cng tc tnh Q, ngti ng c h s gc nh hn so vi ng ti tnh nn c dc ln hn.

L

E CQCC

CE L

C R

R I V

u Ri1

E L R Rtg

11

12

1 tg

Rtg

L

iC

uCE

ng ti tnh

ng ti ng

Q


12/20

MCH KHUCH I CH A TI L CUN CM

thu c tn hiu u ra khng mo v t c hiu sut l ln nht th:

Cng sut xoay chiu thu c trn ti:

Cng sut mt chiu cung cp cho mch:

Hiu sut ca mch:

CEQU

CC CEQ V U L

CC CQ

R

V I

R2

0

RL

RE

R1

CE

Q1

vs

C1

L1

1

2

VCC

C2

CC p V U L

CC CQ p R

V I I

L

CC L p L R

V R I P2

2

21

21

C i

L

CC

R

V 2

CC V CC V 2

ng ti tnh, h s gc=

ng ti ng,h s gc =-1/RL

CE u

QCQ I

E R

1

L

CC CQCC dc R

V I V P

2

%50dc

o

P

P


13/20

MCH KHUCH I CH AGHP BIN P

Cng sut xoay chiu thu c trn ti:

Cng sut mt chiu cp cho mch

Hiu sut ca mch:

T11 4

2 3

vs

Q1C1

RLR1

CER2

VCC

RE

C i

'

2

L

CC

R

V

CC V CC V 2

ng ti tnh, h s gc=

ng ti ng,h s gc =-1/RL

CE u

QCQ I

E R

1

CC CEQ V U '

L R

CC p V U ' L

CC CQ p R

V I I

L L R R2'

L

CC L p L R

V R I P 2

2'2

2

1

2

1

L

CC CQCC dc R

V I V P 2

2

%50

im cng tc tnh:

Trong , l ti s cp:

t c hiu sut ln nht ti u ra:

'

L

CC CQ R

V I


14/20

2.3. MCH KHUCH I CH B (AB) Mch khuch i y ko i xng b (ngc) Mch khuch i y ko dng bin p Mch khuch i kt cui n vi 1 ngun cung cp


15/20

M CH KHUCH I Y KO I XNG B (1)

Mi transistor c phn cc ch B v ch dn trong na chu k. Tuynhin c mt s suy bin nh c bitkhi tn hiu nh (mo im 0).

Hai transistor Q 1 v Q 2 s thay nhau dntrong mi na chu k. Khng c khuch i p nhng h skhuch i dng in ln khuch icng sut.

c tuyn truyn t v dng sng mch khuch i ch B

Mch khuch i y kob ch B c bn.

Q 2

Q 1

+Vcc

-Vcc

R L

u r u v

i L

0.6V- 0.6V u v

u r u r

t

u v

Transistor b o ho

Transistor b o ho


16/20

M CH KHUCH I Y KO I XNG B (2)H IU SUT

in p ra cho mch ch B ny l:

Trong in p ra ln nhtU p = V CC.in p uCE1 c vit theo cng thc:

Cng sut trung bnh trn ti l:

cng sut trung bnh ca mi ngun cp

Cng sut trung bnh do c 2 ngun cp

Hiu sut ca mch l:

Hiu sut ln nht khi tn hiu ra lnnht viU p =V CC . Ta c:

Thc t, hiu sut ca mch ch Bthp hn gi tr trn do cc suy haokhc ca mch v in p ra nh (U p )phi nh hn V CC trnh a transistor vo minbo ho. Khi bin inp ra tng th mo tn hiu ra cng tng. mo mc chp nhn c, in p ra nh U p thng nh hn V CC vi Volt.

sino pu U t

1 sinCE CC pu V U t

21

2 p

L L

U P

R

( ) pS S CC L

U P P V

R

2

12

42. ( )

p

p L L

p CC S CC

L

U U P R

U V P V R

2. ( ) pS CC L

U P V

R

max 78.5%4


17/20

M CH KHUCH I Y KO I XNG B (2)MO IM 0

Trong di in p gn 0V, c 2transistor u ngt v in p ra bng0 v to ramo im 0 vi tn hiu vodng sin. Mo im 0 ny c th c khc phc bng cch phn cc tnh vi gitr nh cho c Q1 v Q2 v mchkhuch i kiu ny hot ng trongch AB.in tr R l in tr phn cc dn dngn2 diode D1 v D2 to inpkhng i gia Q1 v Q2. Haitransistor Q1 v Q2 c cng VBE nn I1 = I2. Khi inp ri trn diode bng VBE, ta c ti imA v imC cinp bngVBE, imB cinp l2VBE.

Q 2

Q 1

+Vcc

-Vcc

R L

u r

i L

R

D 1

D 2

i 1

i 2

2V BE

V BE

B

A

u r

V BE

V BE u v

a. S mch b. c tuyn truyn t

C


18/20

M CH KHUCH I Y KO DNG BIN P Bin p o pha u vo c nhim vto 2 in p vo ngc pha nhau ati 2 transistor Q1 v Q 2.Khi khng c tn hiu vo, c Q1 v Q 2 u ngt, khng c dng in trongmch, in p ra trn ti bng 0. Khi c tn hiu vo, trong na chu kdng ca tn hiu, Q1 dn. Dngi 1 chy qua bin p u ra to cm ngcp cho ti nn trn ti c na sngdng. Trong na chu k ny, tn hiua vo Q2 m nn Q 2 ngt.

n na chu k tip theo, tn hiu avo Q 2 dng nn Q2 dn. Dngi 2 chy qua bin p u ra to cm ngcung cp cho ti nn trn ti c nasng dng. Trong khi , tn hiu avo Q 1 m nn Q 1 ngt. Do i 1 v i 2 chy ngc chiu nhau trongbin p ra nn in th cm ng bncun th cp cng ngc pha nhau,chng kt hp vi nhau to c chu kca tn hiu trn ti.

Hiu sut ca tng c tnh nh sau: = b.a . B

Trong b.a l hiu sut ca my binp (khong t 80% 90%), B l hiu

sut khuch i ca tng khuch ich B khi khng ghp bin p. Theokt qu tnh ton phn trn ta c B (max)= 78.54% .

max = b.a . B(max)= 60% 70%

Q 2

Q 1

+VccR Lu v

i 1

i 2

N 1

N 1

N 2

i LQ 1 dn

Q 2 dn

Bin p

o phau vo

Bin p

u ra


19/20

M CH KHUCH I KT CUI N VI 1 NGUN CUNG CP ti s phi c ni vi mt t in cgi tr cao (khong vi trm mF).

in p trn t s l hng s trong sutchu k hot ng, ging nh mt nguncung cp th 2.Nu 2 Transistor ging nhau, ti im

chung A c in p Vcc/2 v t s duytr in p ny.Khi Q 1 dn, in p cung cp cho mchs l hiu ca Vcc v in p trn t,tc l bng Vcc/2. Cn khi Q2 dn, ch c ngun cung cp bi t l hot ng,cng bng Vcc/2.

T C ng vai tr nh ngun 1 chiu vigi tr in p l:U Co = Vcc/2

Q 2

Q 1

+Vcc

u v

Bin po phau vo

C

R L

U Co

+A

1 1 L

d d L

R hay C C R


20/20

M CH KHUCH I CH CMch khuch i ch C transistor c phn cc trong min ngt, im lm viccn thp hn im ngt.Ti mt s im khi tn hiu ln vtqu ngng ngt (trong na chu k dngca tn hiu) th mi xut hin tn hiu ra.Do trong ch ny transistor ch dntrong khong nh hn na chu k Tn hiu ra ca mch khuch i ch C lnhng xung hp. Mo trong trng hp nyl rt ln nn khng s dng tng khuchi n hoc tng y ko.

Mch khuch i ch C c kh nng cungcp cng sut ln vi hiu sut ln hn78.5%, tuy nhin ch C to mo ln trongtn hiu ra. Cc mch khuch i ch Cch yu c ng dng trong khuch i tns cao dng ti cng hng RLC thngdng trong cc my pht ca Tivi hoc i

ICQ

U BE

IC

t

t

Q

Vcc/RcIcmax

T

A

B

IC

t

U BEQ

t

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