Bai giang Dien tu cong suat Phan 04

8/14/2019 Bai giang Dien tu cong suat Phan 04

1/55

Chng 5: Thit b ngh ch lu


2/55

5.1 Khi nim chung Phn lo i

Bin i nng lng in m t chiu thnh n ng lng in xoay chi u

Phn lo i

Theo s lng pha:- Mt pha- Ba pha

- Nhiu pha Theo s - Hnh c u- Hnh tia

Theo c im ngu n- Ngu n p- Ngu n dng


3/55

5.2 S nguyn l

S nguyn l ngh ch lu cu m t pha

S nguyn l ngh ch lu tia v bn c u m t pha

S1 S3

S4 S2

R

u ZU

S2S1 S2S1S4S3

0

uZ

= t

S1 S2

R

Ud

uZ

O

S1S2S1

U d

= t

uZU d

U d

S1

S2

R

uZ


4/55

Ngh ch lu c u ba pha

ti thun tr

U d

S1 S3 S5

S4 S6 S2

1 2 3

uZ1 uZ2 uZ3

S1S2S3S4S5S6

3

Ud2

= t

uZ1

uZ2

uZ3


5/55

5.3 Nghch lu p

5.3.1 Dng cng su t hu cng v ph n khng

P = U dId

P > 0 Id > 0: c. ngh ch luP < 0 Id < 0: c. ch nh lu

===

m

n nd d piU p

1

Mang tnh ch t ngu n p: t o ra in p xoay chi u. Dng in ura ph thuc vo t i. u vo c a ngh ch lu p l ngu n in p m t chiu

Udid

-id S

VR

P = U d .Id

p = U d .id

1

2

3

p1Z1p2Z2

p3Z3


6/55

5.3.2 Nghch lu p cu mt pha

: Gc d kin ng cc b kha

S : Gc thng dng c a cc b kha

R: Gc thng dng c a ccdiode ng c

VR2

VR1

S2

S1 S3

S4

VR4

VR3

iZ

uZU d

L R

Z

id

iVR1

iS1


7/55

S1,S2VR1,VR2

S3,S4VR3,VR4

u Z

R

= t U d

S

-U dO

U d /R

-Ud /R

2

iZ

iS1 = i S2

O

I d

iVR3 = i VR4

iS3 = i S4 iVR1 = i VR2

O

O

U d

S1

S2

Z

iZ

S1,S2

Z

iZ

VR3

VR4

VR3,VR4

S4

S3

ZiZ

S3,S4


8/55

5.3.3 Nghch lu p tia mt pha

Nh p S1:

uZ = u a = U d

iS1 = id = iZ tng theo ng cong hm m

=


9/55

Nh p VR2:

uZ = u b = -U diVR2 = -id = iZ gim theo ng cong hm m

Ngt xung iu khi n a vo S1. Do nh h ng c a L trong t i, dngin trong cu n th cp v qua dng trong cu n s cp vn gichiu c . Dng trong cu n s cp ch y qua VR2 v qua n a ph i cacun s cp.

Nh p VR2 k t thc khi dng i VR2 gim v gi tr 0


10/55

Nh p S2:

uZ = u b = -U d

iS2 = id = -iZ tng theo ng cong hm m vi chiu ng c li

Xung iu khi n a vo S2 ngay sau khi ng t S1. Khi VR2 ng,dng s chy qua S2. in p trn t i vn khng i, tuy nhin dng i Zs o chi u

Nh p S2 k t thc khi ng t xung iu khi n a vo S2 v b t u a xungiu khin vo S1


11/55

Nh p VR1:

uZ = u a = U diVR1 = -id = -iZ tng theo ng cong hm m

Ngt xung iu khi n a vo S2. Do nh h ng c a L trong t i, dngin trong cu n th cp v qua dng trong cu n s cp vn gichiu c . Dng trong cu n s cp ch y qua VR1 v qua n a tri c acun s cp.

Nh p VR1 k t thc khi dng i VR1 tng ln gi tr 0


12/55

5.3.4 Nghch lu p cu ba pha


13/55


14/55

S1, S5, S6

1 3

2

ZuZ1

uZ3

uZ2

Ud

uZ1 = u Z3 = U d/3uZ2 = -2U d/3


15/55

S1, S2, S61

32

uZ1

uZ3uZ2

Ud

uZ1 = 2U d/3

uZ2 = u Z3 = -U d/3


16/55

S1, S2, S3

1 2

3

ZuZ1

uZ2

uZ3

Ud

uZ1 = u Z2 = U d/3

uZ3 = -2U d/3


17/55

S2, S3, S42

31

uZ2

uZ3uZ1

Ud

uZ2 = 2U d/3

uZ1 = u Z3 = -U d/3


18/55

S3, S4, S5

2 3

1

ZuZ2

uZ3

uZ1

Ud

uZ2 = u Z3 = U d/3

uZ1 = -2U d/3


19/55


20/55

= S + R = = < S + R >

TI


21/55


22/55

5.3.5 iu khin ngh ch lu p cu 3 pha

Nguyn tc thay i tn s xung

Nguyn tc iu bin r ng xung - PWM

IN P RNG CAiN PIU KHIN

ln: U d Tn s : tn s pht xung vo cc b kha

Pht xungu c Phn ph i

xungKhuych i

xung

S1, S3, S5 S2, S4, S6

uZ1 = u Z2 = u Z3 = 0


23/55


24/55

5.4 Nghch lu dng5.4.1 Hai chc nng ca b chuyn mch

trong ngh ch lu dng

t in p ng cln thyristor, ng thyristor.

Tham gia vo qu trnhchuy n m ch


25/55

5.4.2 Nghch lu dng mt pha

Gi s V1, V2 m , dng in qua t iiZ = Id

in p trn cc t uC1

< 0, uC2

< 0.

Mun ng V1, V2: m V11, V12.

Dng i Z = Id chy qua V11, C1, C2, V12 in p trn cc t o chi u.

Trong th i gian in p trn cc t cn


26/55

i vi ti L: u V3 = u C1 , u V4 = u C2V3, V4 m khi u C1 = u C2 = 0

Dng in ch y qua V11, C1, Z, C2, V12gim d n. Dng in ch y qua V3, Z, V4tng d n.B chuy n m ch th c hin ch c n ngth hai

Qu trnh chuy n m ch k t thc khiiV3 = iV4 = -iZ = Id


27/55

5.4.3 Nghch lu dng 3 pha

Thyristor chnh: V1, V2, , V6 T chuy n m ch: C13, C35, , C 26, C24 Diode phn cch: V11, V12, , V16.

0120 = V1V2V3V4V5V6

iZ1

iZ2

Id-Id

iZ3


28/55

Nh p V1, V2, V11, V12

iZ1 = Id; iZ2 = 0; i Z3 = -IduC13 > 0

uV3 = u C13 > 0: V3 ang tr ng thi kha

Nh p V3, V11, V2, V12

a xung iu khi n m V3.uC13 ng V1.Dng I d chy qua V3, C13, song song v iC13 l C35 v C15, V11, vo pha 1.uV13 = u Z12 u C13 < 0 ... V13 v n ng.Id s o chi u in p trn C13.

B chuy n m ch th c hin ch c n ng th 1


29/55

Nh p V3, V11, V13, V2, V12

Khi u V13 = u Z12 u C13 = 0 ... V13 m ...Dng ch y qua V3 v V13 vo pha 2.

Qu trnh chuy n m ch: dng ch yvo pha 1 gi m d n, dng ch y vopha 2 t ng d n.

B chuy n m ch th c hin ch c n ng th 2: tham gia vo qu trnh chuy n m ch

Qu trnh chuy n m ch k t thc khi dngchy vo pha 1 gi m v 0 v dng ch yvo pha th 2 b ng I d.

Chuy n sang nh p V3, V13, V2, V12


30/55

5.4.4 iu khin ngh ch lu dng


31/55

Chng 6: Thit b bin tn


32/55

6.1 Khi nim chung Phn lo i

Dng bin i nng lng in xoay chi u b ng cch thay i tn s

Phn lo i theo s lng pha- Mt pha- Ba pha- m-pha

Phn lo i theo s - Tr c tip- Gin ti p

+ Ngu n p+ Ngu n dng


33/55

6.2 Bin tn tr c tipBin i tr c tip in p xoay chi uthnh in p xoay chi uc tn s khc


34/55

12 1 2( 1)

T T T n

p= + n: s na chu k in p u vo

to nn n a chu k in p u ra

2 1

1 2 2( 1) f T p f T p n

= =+ [ ]

1 12 2( 1)

T T T p n q

p p= + =


35/55

Tn s in p u ra f 2 < 25Hz v khng th iu khi n v c p

Bin tn tr c tip t c s dng

[ ] 1 12 2( 1)T T

T p n q p p

= + = i vi bin tn 3 pha:


36/55

6.3 Bin tn gin tip

6.3.1 Bin tn ngun p

CHNH LU NGHCH LU P

UdII > 0

C f , Lf : mch lcMch lc cng v i ch nh lu to thnhngu n p m t chiu u vo c angh ch lu p

C f : nh n dng ph n khng.Nguyn tc iu khin:

Nguyn t c iu khin tn s xung:

f 2: tn s xung pht vo ngh ch lu

U2: s dng ch nh lu c iu khi n, ho c s dng ch nh lu khng iu khi nv b bin i xung p

Nguyn t c PWM ch nh lu ch cn l khng iu khi n.

UdI > 0 IdI > 0

P I > 0 Cng su t khng th o chi u


37/55

6.3.2 Bin tn ngun dng

CHNH LU NGHCH LU DNG

Lf : Mch lc

Ch nh lu v m ch lc ph i ctnh ch t ngu n dng m t chiu

Nguyn tc iu khin:

f 2: tn s xung pht vo ngh ch luI2: s dng ch nh lu c iu khi n.

Id > 0 UdI > 0 ho c < 0

Cng su t c th o chi u


38/55

Chng 7B kha xoay chi u

v thit b bin i in p xoay chi u


39/55

7.1 Khi nim chung Phn lo iB kha xoay chi u: ng, c t dng xoay chi uThit b bin i in p xoay chi u: thay i gi tr in p xoay chi u

Phn lo i theo s lng pha

- Mt pha- Ba pha- m-pha

Phn lo i theo s

- C bn- Tit kim

Phn lo i theo ph ng php iu khin- iu khin hon ton

- Bn iu khi n


40/55

7.2 B kha xoay chi u7.2.1 B kha xoay chi u mt pha

NG

NGT

sinm

Z

Z U u

d

di L Ri ==+

Z: gc b t uiz(z) = 0

( )

sin( ) sin( )

Z R

m m L Z z

U U

i e Z Z

=

2 2 2 ; arctan L Z R L R = + =

f 1() f 2()


41/55


42/55


43/55

7.3 Thit b bin i in p xoay chi u

Ti thun tr R

7.3.1 Thit b bin i in p xoay chi u mt pha


44/55

Ti R, L:

Khi < <

( )

sin( )

sin( )

m Z

R

m L

U i Z

U e Z

=

Z =

Khi 0 < <

Khng iu khin c in p.Thit b lm vi c nh b kha xoay chi u


45/55

Ti L

Khi /2 < <

(cos cos )m Z U

i L

=

Khi 0 < < /2

Khng iu khin c in p.Thit b lm vi c nh b kha xoay chi u

= /2


46/55

7.3.2 Thit b bin i in p xoay chi u ba pha

Gm c ba b bin i in p xoay m t pha m c vi nhau


47/55

CHNG 8: BO VVIU KHINCC THIT BBIN I


48/55

8.1 Bo vcc ph n t in t cng su t8.1.1 Cng sut tn tht v lm mt

1 2 1P p p p = + P Cng su t tn th t

1 p Cng su t tn th t chnh2 p Cng su t tn th t ph

20 ( )T AV F P U I R I = +


49/55

j a th

th jv vr ra

T T R P

R R R R

= + = + +

Nhit mt ghp

T j Nhit mt ghpTa Nhit khng kh mi tr ngR jv in tr nhit gia m t ghp v v linh kin bn d n

R vr in tr nhit gia v v cnh t n nhi tR ra in tr nhit gia cnh t n nhi t v khng kh mi tr ng

Lm mt:

Cnh t n nhi t Cnh t n nhi t + qu t gi Cnh t n nhi t + n c Ngm trong d u bin th


50/55

8.1.2 Bo vdng inCu ch:

CC ph i ch u c dng lm vi c nh m c ca thi t b Nhit dung ch u ng c a CC ph i nh hn nhi t dung c a thi t b cn

bo v nhit lng (I 2t)CC < (I2t)TB in p h quang c a CC ph i tng i ln Gim nhanh dng in

v tiu tn n ng lng trong m ch. Khi CC t, in p ph c h i phi ln Khng lm cho h quang chy

li gia hai c c ca c u chLp t: c nhi u cch

Tng pha c a cu n dy s cp ho c th cp MBA Ni tip vi tng van Ni tip vi tng nhm van m c song song u ra c a thi t b bin i


51/55

8.1.3 Bo vqu p

Qu p trong

S tch t in tch trong cc l p bn d n(qu trnh ng c a diode v thyristor)

Bo v bng m ch R C u song song v i diode ho c thyristor

Qu p ngoi

Ct khng t i MBA trn ng dy, CC b o v nhy, s m st, Bo v bng m ch R C m c gia cc pha th cp ca MBA ng lc

R .. 10 1000 C 0.01 1 F


52/55

8. 2 iu khin cc thit b bin i8.2.1 Khuych i thut ton

2

1r v

Ru u

R=

Khuych i o

Mch so snh

...

...cc

r cc

U u uu U u u

+

+

>=+ >


53/55

Mch tch phn

1r vu u dt

RC =

-

+

R

Cu r v

r du

u RC dt

=

Mch vi phn


54/55

8.2.2 Mch to xung chu n s dng IC 555


55/55

1 1 2 2 2

1 2 1 2

0.693 ( ); 0.693

0.693 ( 2 )

t C R R t CR

T t t t C R R

= + == = + = +

Mch lt n s dng IC 555

1.1T RC =

1

3 ccV

Documents

Bai giang Dien tu cong suat Phan 04