dien tu cong suat doan quang vinh 97 4067
TRANSCRIPT
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in t cng sut
Thnh ph H Ch Minh, thng nm ..
-
IN T CNG SUT
Ti liu tham kho in t cng sut L Vn Doanh Gio trnh in t cng sut Nguyn Vn Nh in t cng sut Nguyn Bnh
[email protected] 586 586
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CHNG 1M U CC LINH KIN IN T CNG SUT
1.1 Khi nim chung
in t Cng sut ln
Cc linh kin in t cng sut c s dng trong cc mch ng lc cng sut ln
-
S khc nhau gia cc linh kin in t ng dng (in t iu khin) v in t cng sut
Cng sut: nh ln Chc nng: iu khin ng ct dng in cng sut ln
IB
IC
Thi im Cng sut
ng lciu khinCc linh kin in tcng sut ch lm chc nng ng ct dng in cc van
-
Transistor iu khin: Khuych i
Transistor cng sut: ng ct dng in
B
IC
UR
ab
A
A
UCE = U - RIC
UCE = UCE1
UCE1 U
IB2 > IB1
IB1 > 0
IB = 0
UBE < 0 UCEIB2IB
R
U
uCE
CiB
B
uBEE iE
iC
-
c tnh Volt Ampe ca van cng sut l tng
i
u
iu khinu
i
ac
b
d
-
i tng nghin cu ca in t cng sut
Cc b bin i cng sut Cc b kha in t cng sut ln
Chnh lu
Nghch lu
BB in p mt chiu (BXA)
BB in p xoay chiu (BAX) Bin tn
-
1. 2. Cc linh kin in t cng sut1.2.1 Cht bn dn - Lp tip gip P - NCht bn dn: nhit bnh thng c dn in nm gia cht dn in v cht cch inLoi P: phn t mang in l l trng mang in tch dngLoi N: phn t mang in l cc electron mang in tch m
+
++
+
+
+++
-- -+
-- -
-- -
Min bo ha- Cch in
P N
+
++
+
+
+++
+
+
+
--- -+
--- -
--- -
P N
J
-
Phn cc ngc
+
++
+
+
+++
-- -+
-- -
-- -
Min bo ha- Cch in
P N
+-
+
+
+
-
-
-
Min bo ha - Cch in
P N
+-
-
Phn cc thun
+
++
+
+
+++
-- -+
-- -
-- -
Min bo ha- Cch in
P N
-+
-+
i
-
1.2.2 Diode
Cu to, hot ng
R: reverse ngcF: forward thun
NP KatodeKA
AnodeiR
uR
iFuF
KA
Hng ngc
Hng thun
-
c tnh V ADiode l tng
u
iNhnh thun m
Nhnh ngc ngDiode thc t
UTO: in p ri trn diode
in tr thun trong diodeF
FF dI
dUr =in tr ngc trong diode
RR
R
dUrdI
=
UBR: in p nh thng
Hai trng thi: m ng
U[BR]
IR [mA]
UF [V]UR [V]
1 1,5800 400 0
50
100
30
20
URRMT
j = 30 C
o
oT
j = 160 C
IF [A]
URSM
Nhnh thun m
Nhnh ngc ng
-
c tnh ng ca diode
UK: in p chuyn mch trr: Thi gian phc hi kh nng ng irr: Dng in chuyn mch phc hi
= rrt
rrr dtiQ0
: in tch chuyn mch
Qu p trong
L
+UK
-S
I
iF
irr
iR
iF
n
g
S
trr0,1 irrM
i
r
r
M
iR
i
F
=
I
tO
irr Qr
t
uR
uF
Uk
uRM
uR = UkO
-
Bo v chng qu p trong
R C
LuR V
Uk
irriL
iRC
- +
V
Ot
irr iRCO
Uk
t
M ng
LR k
diu U Ldt
= RCrrL iii +=
-
Cc thng s chnh ca diode
in p:
Gi tr in p nh thng UBR Gi tr cc i in p ngc lp li: URRM Gi tr cc i in p ngc khng lp li: URSM
Dng in - nhit lm vic
Gi tr trung bnh cc i dng in thun: IF(AV)M Gi tr cc i dng in thun khng lp li: IFSM
U[BR]
IR [mA]
UF [V]UR [V]
1 1,5800 400 0
50
100
30
20
URRMT
j = 30 C
o
oT
j = 160 C
IF [A]
URSM
Nhnh thun m
Nhnh ngc ng
-
Diode thc t: IDB30E60 Infineon Technologies
-
1.2.3 Transistor lng cc (BT)
Cu to, hot ng
R
U
uCE
CiB
B
uBEE iE
iC
R
U
uEC
CiB
B
uEBE iE
iC
N
N
PB
C
E
P
P
NB
C
E
(Bipolar Transistor)
-
c tnh Volt Ampe
Min m bo ha
Min ng bo ha
M
ng
c tnh ngoi IC = f(UCE) c tnh iu khin IC = f(IB)
B
IC
UR
ab
A
A
UCE = U - RIC
UCE = UCE1
UCE1 U
IB2 > IB1
IB1 > 0
IB = 0
UBE < 0 UCEIB2IB
-
ICE
ICE0ICERICESICEU
UCE0 UCE
UBR(CEU)
UBR(CES)
UBR(CER)
UBR(CE0)IB = 0
UCERUCES
UCEU
RB
-IB UBE
+
-
RB
-IB UBE
+
-+
-ICEU
b) c)
a)
O
0 H mch B E (IB = 0) R Mch B E theo hnh b) S Ngn mch B E (RB 0) U Mch B E theo hnh c)
-
Qu trnh qu ca transistor
iBIB
0.9IB
O t
0.1IB
0.1ICuCE
td tr
iCts
tofftonO
tf
0.9IC IC 0.1IC
-
Mch tr gip ng m
(in t cng sut Nguyn Bnh)
Cc thng s chnh
in p:
Gi tr cc i in p colector emitor UCE0M khi IB = 0 Gi tr cc i in p emitor baz UEB0M khi IC= 0
Dng in: Gi tr cc i ca cc dng in IC, IB, IE
-
Transistor thc t - MJW3281A (NPN) ON Semiconductor
-
1.2.4 Transistor trng MOSFET(Metal Oxid Semiconductor Field Effect Transistor)
N iD
D
OXIDGS uGS
PN
G
D iD
uDS
SuGS
N
D
OXIDGS
P
N
G
D
S
-
c tnh ng
RGon
UGoff
CGS uGS
G
CGD D
iD
CDS
R
uDS U
+
-+
-S
GS
UGS(th)0.1UG
UG
0.9UG
t
0.9U
U
tr
td(on)
ton
td(off)
uDSiD
tf
toff
0.9U
0.1U
-
MOSFET thc t - 19MT050XF International Rectifier
-
1.2.5 Transistor lng cc cng cch ly - IGBTInsulated Gate Bipolar Transistor
C
G
E
G
C
E
-
c tnh ng
Gon
UG
RG
iC
C
EuCE
uGE
off
R
U
uGE
0.1UCM
UGE(th)
UG 0.9UG
tuCE
0.1ICM
U
td(on)
tr
ton
td(off)
tf
toff
ICT
iC
ICM0.1ICM
0.9ICM
-
IGBT thc t1MB-30-060 Fuji Electric
-
1.2.6 Thyristor
Cu to Hot ng
A
iG
i2
i1i
G
KuAK
uR
A
K
GPP
P
N
NN
J3J2J1
A
K
G
NPNP
-
iu kin m Thyristor
UAK > 0 Xung iu khin a vo cc iu khin.
iu kin ng Thyristort in p ngc ln A K
uD
iD
iG
iR
uR
uT
iT
uGA K
Hng ngc
Hng thun
Trng thi: M ng Kha
T: Thun D: Kha R: Ngc
K hiu
-
c tnh Volt - Ampe
Thyristor l tng
u
iNhnh thun m
Nhnh ngc ngThyristor thc t
Ba trng thi: ng m kha
Nhnh kha kha
UBR: in p ngc nh thngUBO: in p t m ca thyristorUTO: in p ri trn Thyristor
IH: Dng duy tr (holding)IL: Latching
Cc thng s chnh
Tng t nh diode.URRM = UDRM
Nhnh thun m
Nhnh kha kha
Nhnh ngc ng
IG = 25 mA
IG = 0
IG = 0
IG = 25 mA
INIL
U[TD]
U[BR]
U[BR]
[V]UR
[V]UDUT
IR-110
-210
-310
[A]
[A]
ID
IT10
102
10-3
10-2
10-1
1
1101010 23
32 1010101
-
c tnh iu khin ca thyristor:
iG
U
R
uG
UG[V]40
30
20
UGTO
IGT1 IG[A]
2
(PGM)=/6UG=U-RIG
(PGM)=/12
-400C
iG
2IG
t
iG
t0
-
c tnh ng
M thyristor
Tn thtcng sut khi mthyristor
-
Kha thyristor
G
A
J1
J2
J3
P
N
P
N
iC
+
K-
iC
C uD
uD
tO
tO
iC
-
ng thyristor
Bo v qu p trong Thi gian ng thyristor Gc an ton
toff
-
Thyristor thc t - 22RIA SERIES International Rectifier
-
1.2.7 GTOGate Turn Off Thyristor
J1
J2J3
G
iRG K
A
P
NP
N
uRG
uFGiRG
iFG
ir(iD)
ur(uD)
A
K
G
-
c tnh ng
M GTO
uD
tgd tgr
UD 0.9UD
ir
0.1UDt
O
O
tgt
iFGIFG10
0.2IFG
-
ng GTO
I
iD
iTL
uD
iRG
uRG
iTtgs
tgf uD
ITQ0.9IT
UDP
IT=I
O t
tgqttq
O
uRG iRG
iRG
QGQuRG
IRG
Mch tr gip
-
GTO thc t - FG3000FX-90DA Misubishi Electric
-
1.2.8 Triac
Hng ngc
Hng thun
in p thunin p khaDng in thunDng in kha
Dng in thunDng in kha
in p thun in p kha
Dng in v in p cc iu khin
-
Nhnh m
Nhnh kha
Nhnh kha
Nhnh m
UD > 0
UG > 0; IG > 0
UG < 0; IG < 0
UDR > 0UG > 0; IG > 0
UG < 0; IG < 0
c tnh Volt - Ampe
-
Triac thc t - 2N6344 - ON Semiconductor
-
CHNG 2: MT S KHI NIM C BN TRONG IN T CNG SUT
-
2.1 Nng lng tch ly vo cun khngv gii phng t cun khng
[ ]
1
0
1 1
0 0
0 1
( ) ( )
0 1 1 0 1 0( ) ( )
( , );
( , ) ( ) ( ) ( ) ( )L L
L L
tL L
L L Lt
t i t
L L L L L L Lt i t
d diu dt Q t t u Ldt dt
Q t t d L di t t L i t i t
= = =
= = = =
t0
t0
-
2.2 Nhp v s chuyn mch
Nhp l khong thi gian gia hai ln lin tip thay i trng thi ca linh kin in t cng sut trong mch. Tn ca nhp l tn ca linh kin ang dn in.
Chuyn mch l trng thi in t xy ra trong mch b bin i, c c trng bng vic dng in trong mt nhnh chuyn sang mt nhnh khc trong khi dng in tng chy ra t nt gia hai nhnh vn khng i.
Nhnh chnh Nhnh phLinh kin TCS chnh Linh kin TCS ph
-
Nhnh chnhNhnh chnh
Nhnh chnh
Nhnh ph in p chuyn mch Chuyn mch ngoi Chuyn mch t nhin Chuyn mch trong Chuyn mch trc tip Chuyn mch gin tip Chuyn mch nhiu tng Thi gian chuyn mch Gc chuyn mch Chuyn mch tc thi
-
2.3 Cc ng c tnh
c tnh ngoi (c tnh ti): Mi quan h gia in p u ra v dng in u ra ca b bin i
c tnh iu khin: Mi quan h gia in p u ra v i lng iu khin ca b bin i
2.4 H s cng sut ca b bin i
SP=
P: Cng sut hu cngS: Cng sut biu kin
H s cng sut PF (Power Factor)
-
P = mUI(1)cos(1)m: s phaU: Gi tr hiu dng in p iu ha ca phaI(1): Gi tr hiu dng ca thnh phn bc 1 dng in pha(1): Gc chm pha ca thnh phn bc 1 dng in pha so vi in p
S = mUI
I: Gi tr hiu dng dng in pha =
=1
2)(
2
nnII
2 2 2 2 2 2 2 2 2 2( ) (1) ( )
1 2n n
n nS m U I m U I m U I
= == = +
2 2 2 2 2 2 2 2 2 2 2 2 2 2(1) (1) (1) (1) (1) (1) (1)cos sinS m U I m U I m U I P Q = = + = +mUI(1): Cng sut biu kin ca thnh phn bc 1Q(1): Cng sut phn khng ca thnh phn bc 1
-
2 2 2 2(1)
2( )
2n
n
S P Q D
D mU I
=
= + +
= D: Cng sut phn khng bin dng
(1)2 2 2(1)
(1)
cosPP Q D
II
= =+ +=
mo dng tng THD (Total Harmonic Distortion)
H s mo dng DF (Distortion Factor)
H s cng sut PF (Power Factor)
2( )
2
(1)
nn
I
ITHD
I
==
-
CHNG 3: THIT B CHNH LU
-
Chc nng:
Bin i dng in xoay chiu thnh dng in mt chiu
ng dng
Cp ngun cho cc ti mt chiu: ng c in mt chiu, b np accu, m in phn, my hn mt chiu, nam chm in, truyn ti in mt chiu cao p,
3.1 KHI NIM CHUNG
-
3.2 c im ca in p v dng in chnh lu3.2.1 in p chnh luud: Gi tr tc thi ca in p chnh lu Bao gm c thnh phn xoay chiu u v thnh phn mt chiu Gi tr trung bnh ca in p chnh lu Ud
dd Uuu += S xung p mch ca sng in p chnh lu:
(1)fpf
= f(1): Tn s ca sng iu ha bc 1 thnh phn xoay chiu ca ud f: Tn s in p li
-
3.1.2 Dng in chnh lu
id: Gi tr tc thi ca dng in chnh lu Sng dng in chnh luId: Gi tr trung bnh Thnh phn mt chiu ca sng dng in chnh lui: Thnh phn xoay chiu ca dng in chnh lu
d di i I= +Xt h thng chnh lu ti R,L,E:
( )dL d ddiu L u Ri Edt
= = +
0; 0dd d Ldiu Ri E udt
> + > >0; 0dd d Ldiu Ri E udt
= + = =
0; 0dd d Ldiu Ri E udt
< + <
-
Dng in lin tc Dng in gin on Dng in bin gii gin on
d di i I= +
ddU EIR= 0d dI U E
( )( ) 22
( )
nn
n
UI
R L
=
+
i vi gi tr trung bnh thnh phn mt chiu:
i vi thnh phn xoay chiu: I(n): Gi tr hiu dng ca sng iu ha bc n thnh phn xoay chiu ca dng in chn lu U(n): Gi tr hiu dng ca sng iu ha bc n thnh phn xoay chiu in p chnh lu. (n): Tn s gc ca sng iu ha bc n thnh phn xoay chiu.
( ) 0n d dL I i I = Dng in c san phng tuyt i
-
3.3 Chnh lu hnh tia m-pha dng lin tc
Z
LK
RK
u1
-
3.3.1 Chnh lu hnh tia khng iu khin
S
1
2
3
sin2sin( )34sin( )3
m
m
m
u U
u U
u U
==
= t =
2sin ( 1)n mu U n m =
-
Trong khong 1 < < 2: Gi s V2 m
2
1 2 1 1 1 2
1
00
0
V
V V
V
uu u u u u uu
= = =
>Tng t khi gi thit V3 m. V1 m Nhp V1
Khng hp l
-
Nhp V1 1 < < 2:1 2 2 1 3 3 1
1 1 2 3
0; ;; ; 0
V V V
d d V d V V
u u u u u u uu u i i I i i
= = = = = = = =
Nhp V2 2 < < 3:2 1 1 2 3 3 2
2 2 1 3
0; ;; ; 0
V V V
d d V d V V
u u u u u u uu u i i I i i
= = = = = = = =
Nhp V3 3 < < 4:3 1 1 3 2 2 3
3 3 1 2
0; ;; ; 0
V V V
d d V d V V
u u u u u u uu u i i I i i
= = = = = = = =
-
Nhp Vn:
1 1
1
0; ;; ; 0
Vn V n Vm m n
d n d Vn d V Vm
u u u u u u uu u i i I i i
= = = = = = = =
Qu trnh chuyn mch ti cc thi im 2: in p chuyn mch l uk = u2 u1Tng t ti cc thi im 3, 4:in p chuyn mch ln lt lu3 u2 v u1 u3
Chuyn mch t nhin
p = mS xung:
-
3.3.2 Chnh lu hnh tia c iu khin
Tn hiu
iu khinuc
Khu pht xung
-
Thi im chuyn mch t nhin
Gc iu khin : tnh t thi im chuyn mch t nhin n thi im pht xung m thyristor.
Phm vi ca gc iu khin :
-
coscossin 0dim
di UmmUU ==
0 sinmdimUU
m
=
Udi0: Gi tr trung bnh in p chnh lu khng iu khin.
20 2
3 3 3 3 6sin 1.173 2 2
m mdi
U U UU U = = = =m = 3
Gi tr trung bnh in p chnh lu
2
2
sin2
m
di m
m
mU U d
+ +
+=
-
Cc ng c tnh
c tnh iu khin: c tnh ngoi (c tnh ti): u ra: Ud u vo:
0 cosdi diU U =Ch
chnh luCh
nghch lu
-
6 2 < < c dng lin tc: trong ti phi c L
3.3.3 Ch lm vic chnh lu v nghch lu ph thuc
Ch lm vic chnh lu
Ch lm vic nghch lu
d dP U I=
ch nghch lu ph thuc2 >
-
Trong ti phi c E E o chiu2
> dE U >iu kin c nghch lu ph thuc
-
Gc an ton
0 <
Ch chnh lu
Ch nghch
lu
offt =
-
3.3.4 Chnh lu hnh tia 3 pha c diode V0
dV uu =0V0 s m khi trong trng hp khng c V0 th ud < 0
V0 ch hot ng khi
2 m
-
Chen vo gia cc nhp V1, V2, V3 l cc nhp V0:
0 1 1 2 2 3 3
0
0; ; ;d V V V Vd V d
u u u u u u u ui i I
= = = = == =
-
coscossin 0dim
di UmmUU ==
0 sinmdimUU
m
=
2 m
2 2m m +
0
2
1 sin( )sin
2 2sinm
di di
m
mU mU d U
m
+
= =
0 sinmdimUU
m
=
-
nh hng ca diode V0
Khng c ch nghch lu Diode V0 lm tng hiu sut ca b chnh lu
d dU ImUI
=U, I: gi tr hiu dng ca in p v dng in pha
1
2V
dI I
= 1 02
V Vm =
Diode V0 lm gim gi tr hiu dng thnh phn xoay chiu ca in p chnh lu
-
3.4 Chnh lu hnh cu trong ch dng lin tc
Thit b chnh lu s u ni hnh cu v thc cht l hai b chnh lu hnh tia mc ni tip
Nhm
KA
TOD
E
Nhm
AN
OD
ENhm ANODE
Nhm KATODE
-
3.4.1 Chnh lu hnh cu 3 pha iu khin hon tonS
-
Dng in trong cc pha:
i1 = iV1 iV4; i2 = iV3 iV6; i3 = iV5 iV2
Gi tr trung bnh in p chnh lu:
p = 2m
di diA diKU U U=
2 sin cos
diA diKU U
m Um
= =
Trong trng hp m = 3
0
0
cos
2 2 sin
di di
di
U U
mUUm
==
03 6 2.34di
UU U= =
-
Gin ng ct Xung iu khin:
-
3.4.2 Chnh lu hnh cu bn iu khin
0 0
3 6 cos23 6 1 cos 3 6;2 2
diA
diK di di di
UU
U UU U U U
=+= = =
-
3.4.3 Chnh lu hnh cu iu khin hon ton c diode V0
Diode V0 s hot ng khi
623;)
6sin(1
20 +
= didi UU
Tc dng: - Gim nhp nh ca in p v dng in ti - Tng hiu sut
- Khng cho php ch nghch lu ph thuc
03 6
diUU =
-
3.4.4 Chnh lu cu mt pha iu khin hon ton
1 2
1
2
sin
sin2
sin( )2
m
m
m
u U u uUu
Uu
= = =
=
1 4 2 3
d dA dK
V V V V
u u ui i i i i
= = =
-
00
cos
2 2 0.9
di di
di
U U
UU U
== =
Gi tr trung bnh in p chnh lu
-
00
1 cos2
2 2
di di
di
U U
UU
+=
=
3.4.5 Chnh lu cu mt pha bn iu khin
-
So snh gia hai phng n: iu khin hon ton v bn iu khin
nh m ca sng in p chnh lu b ct nhp nh Khng th lm vic ch nghch lu Hiu sut b bin i cao hn.
-
3.5 Dng in lin tc v gin on ca chnh lu p xung3.5.1 Thit b chnh lu ch dng in gin on
S xut hin ca dng in gin on
Ti R: 0 0d di u
Ti R,L: 0d dU RI= > vi cc m ch dng lin tc Ud < 0 s xut hin dng in gin on
Trong nhp 0:
Trong nhp 0:
Ti L, E: dU E= vi cc m ch dng lin tc Ud < Es xut hin dng in gin on Trong nhp 0:
0;d Vi iu u u= =
0;d Vi iu u u= =
;d Vi iu E u u E= = ;MIN MAX
-
3.5.2 Phn tch dng in chnh lu ca chnh lu p xung,khng c V0
p = 1 Dng in lun gin on
Vi p > 1:
Chnh lu hnh tia c iu khin m pha. p = m. Um l bin in p pha
Chnh lu hnh cu iu khin hon ton m pha. p = 2m. Um l bin in p dy (tr trng hp m = 1)
Z =Gc bt u:
p = 1:
2Z p = + p > 1:
-
sin (1)dd mdiRi L E Ud
+ + =
Ti tng qut R, L, E:
sin( )
1
( ) sin( )
Z
Z
md
md Z Z
UiZ
E eR
Ui eZ
= +
+
(2)
2 2 2
arctg
Z R LLR
LR
= +=
= 0di iu kin:
-
Dng in gin on:
MIN Z MAX <
p dng vo (2)
2 2
2( ) ( ) sin( )
1 ( ) sin( )
md Z d K Z
p pmd Z Z
Ui iZ p
UE e i eR Z
= = +
+ (5)
Suy ra 2
2
2sin( ) sin( )( ) ( )
1
pZ Z
d Z d K m
p
eEpi i UZ
Z e
+ = =
(6)
-
3.5.3 Dng in chnh lu ca chnh lu p xung,c diode V0
-
3.6 Hin tng trng dn
-
1 2V V d di i i I+ = =2 1
2 1V V
Kdi diL u udt dt
= 2 1 sin
2 sin
k km
km m
u u u U
U Um
= == bin in p dy gia hai pha k nhau
2
20
sin2
Vikm
VK
Udi dL
=
-
( )( )
2 cos cos2cos cos
2
kmV
K
km
kmkm
K
UiL
IUIL
= = =
( )cos cosd kmI I = + arccos cos d
km
II
= gc trng dn
-
22
1 22
Vd k
diu u Ldt
u u
= +=
-
( )cos coskm di I I = km
kmK
UIL=
( )1 23 4 1
cos cos2km
V V
V V d V
Ii i
i i I i
= = = =
( )2 cos cosd kmI I = + 2arccos cos dkm
II
=
0du =
-
St p do trng dn Ud
d dU R I =
2kpXR =
Chnh lu hnh tia ba pha Chnh lu cu 3 pha
kpXR = Chnh lu cu mt pha
-
Ud: St p do Lk.Udr = Rk.Id: St p trn RkUdF: St p trn van
c tnh ngoi khi xt n st p v dng in gin on
-
nh hng n gc an ton ca thyristor:
M + + =
( )cos cosdMkm
II
= + Chnh lu hnh cu 3 pha, tia ba pha
Chnh lu hnh cu mt pha
( )2cos cosdMkm
II
= +
-
Xc nh gi tr in p chnh lu cc i
( )0 1di c dM d M drM dFMU c U U U Ub = + + +cc: hng s d tr cho iu khin cc = 1.04 1.06
b: hng s d tr ca li in 5% b = 0.95
-
3.7 Chnh lu c o chiu dng in - bn gc phn t
Nguyn l iu khin:
iu khin ring:
Tng b chnh lu lm vic c lp, trong khi b chnh lu cn li khng lm vic.
-
iu khin chung
Xung iu khin cng mt lc c a vo c hai b, trong c mt b c iu khin vi gc < /2, lm vic ch chnh lu. Cn b th hai c iu khin vi gc > /2, ch ch.
khng c dng ngn mch gia hai bchnh lu:
UdI + UdII 0
( )0 0
0
.cos .cos 0cos cos 0
di I di II
di I II
I II
U UU
+ +
+
-
Tuy nhin:udI + udII 0 dng in tun hon
Hn ch dng tun hon:lp thm cun khng cn bng
-
3.8 My bin p ng lc
3.8.1 Dng in
iS = IS(AV) + iS
NP: s vng dy cun s cpNS: s vng dy cun th cp
iP.NP = iS.NS
3)(d
AVSII =
Gi s NP = NS = N
-
1 1 1
2 2 2
3 3 3
3
3
3
dS S P
dS S P
dS S P
Ii i i
Ii i i
Ii i i
= =
= =
= =
1 3 1
2 1 2
3 2 3
L P P
L P P
L P P
i i ii i ii i i
= = =
-
3.8.2 Cng sut biu kin ca my bin p
2P S
tN t tNS SS K P+= =
StN: Cng sut biu kin nh mc my bin pSP: Cng sut biu kin cun dy s cpSS: Cng sut biu kin cun dy th cpPtN: Cng sut hu cng nh mc ca my bin p
i vi my bin p /Y2 /3
2
0
12 3
dS d
II I d
= =( ) ( )2 /3 22 2
0 2 /3
21 2 /3 / 32 3
dP d d
II I d I d
= + =
-
3 3
3 2S S SN S dN
P P PN P dN
S U I U I
S U I U I
= == =
Vi chnh lu tia ba pha: 03 62di
U U=
0
0
2 23 32 23 3 3 3
S di dN dN
P di dN dN
S U I P
S U I P
= =
= =
2 23 3 3 1.35
2tN dN dNS P P
+= =
-
3.9 Cc nguyn tc iu khin chnh lu
Xung iu khin a vo thyristor lc in p t ln thyristor dng Phi bit c khi no in p t ln thyristor dng Phi c in p ng b: ng b vi in p kha t ln thyristor
S khi ca khu pht xung b iu khin:
ng bub
So snh
uc
Khuych iv p.p
iG1, iG2, iG3
-
3.9.1 Nguyn tc thng ng tuyn tnh
in p ng b l in p rng ca
. cK u =( )0 0cos cos .di di di cU U U K u= =
ub1
ub2
ub3
uC
uC
uC
-
3.9.2 Nguyn tc arccos:
in p ng b l mt ng cosin
max cosbu U =max
max
cos
arccos
b c
c
u u U
uU
= =
= 0 0
maxcos cdi di di
uU U UU
= =
-
Umax
uc
ubuAK
-
Chng 4: B bin iv b khamt chiu
-
4.1 Khi nim chung Phn loi
-
4.2 B kha mt chiung ct dng in mt chiu
S nguyn l s dng GTO
a) V
UV0 L
R
iZ
Z
iG
iV0
iV
LR
0
0
iG
iViV0
tRL
ng
Ct
-
Khi s dng thyristor:
M - ng
ng Ct
NGNG
CTS
BCM
S
S
PS
ZV0
OS
OSSPS
t
-
4.3 Phn loi thit b bin i mt chiu
4.3.1 Phn loi theo phng php bin i Trc tip b bin i xung Gin tip
4.3.2 Phn loi theo chc nng bin i Gim p mc ni tip Tng p mc song song iu khin xung gi tr in tr
4.3.3 Phn loi theo phng php iu khin Tn s xung rng xung Hai gi tr
Nghch luChnh luc iu khin
U UZ
-
4.4 Nguyn l lm vic ca cc b bin i xung
4.4.1 B bin i gim p mc ni tip
Nguyn l lm vic
Nhp S:uZ = U
iZ = iS: tng theo ng conghm m v gi tr (U - E)/R
Nng lng t ngun U, mt phn tch ly vo cun L, phn ln np cho E, phn cn li tiu tn trn R
Nhp S ko di trong khon thi gian T1. Kt thc khi tn hiu ct a vo kha S.
uc
S
iS
U
iV0
V0R
L
uZ
iZZ
uZ
0
0
S V0 S V0 S
UUZi
tT1 T2T
iS iV0 IZ
iZ
iZMiZMIN
t
-
Nhp V0:
uZ = 0
iZ = iV0: gim theo ng conghm m v gi tr -E/R
Nng lng trc y tch ly trong cun L c gii phng, phn ln np cho E, phn cn li tiu tn trn R
Nhp V ko di trong khon thi gian T2. Kt thc khi tn hiu ng a vo kha S.
uc
S
iS
U
iV0
V0R
L
uZ
iZZ
uZ
0
0
S V0 S V0 S
UUZi
tT1 T2T
iS iV0 IZ
iZ
iZMiZMIN
t
-
Gi tr trung bnh in p trn ti
zUUTTUZi == 1
z: t s chu k
0 z 10 Uzi U
Ziz
U EIR=
uc
S
iS
U
iV0
V0R
L
uZ
iZZ
uZ
0
0
S V0 S V0 S
UUZi
tT1 T2T
iS iV0 IZ
iZ
iZMiZMIN
t
-
4.4.2 B bin i tng p mc song song
Nguyn l lm vic
Nhp S:
uZ = 0
iZ = iS; tng theo ng cong hm m, v gi tr E/R
Nng lng t ngun E c tch ly phn ln vo cun L, phn cn li tiu tn trn in tr R
Nhp S ko di trong khong thi gian T1. Nhp kt thc khi tn hiu ct a vo S
uc
iV0
V0
iS
S
iZ
Z
UR
L
uZ
S V0 V0S S
T1 T2T
0UUZi
t
uZ
iS iV0 iZMIN iZM
t
-
Nhp V0:
uZ = U
iZ = iV0; gim theo ng cong hm m, v gi tr(E U)/R < 0
Nng lng t ngun Ecng vi nng lng tch ly trong cun L nhp trc, tiu tn mt phn trn in tr R, phn ln cn li c tr v ngun U.
Nhp V0 ko di trong khong thi gian T2. Nhp kt thc khi tn hiu ng a vo S.
uc
iV0
V0
iS
S
iZ
Z
UR
L
uZ
S V0 V0S S
T1 T2T
0UUZi
t
uZ
iS iV0 iZMIN iZM
t
-
Gi tr trung bnh in p trn ti
( )
2
1
1
ZiTU UTT T UTz U
= == =
=
Ziz
E UIR=
uc
iV0
V0
iS
S
iZ
Z
UR
L
uZ
S V0 V0S S
T1 T2T
0UUZi
t
uZ
iS iV0 iZMIN iZM
t
-
4.4.3 B bin i xung gi tr in tr
Nguyn l lm vicNhp S:iZ = iS: tng vi h s gc bng U/L
Nhp S ko di trong khong thi gian T1. Kt thc khi tn hiu ct a vo S.
URP
S
uc
L
iZ
L
iS
SiRRp
U
uc
T1 T2
T
iS iR iZMINiZM
t0
iZ =iS+iR
-
Nhp 0
iZ = iR; gim theo ng cong hm m v gi tr U/Rp.
Nhp 0 ko di trong khong thi gian T2. Kt thc khi tn hiung c avo S
iZ
L
iS
SiRRp
U
uc
T1 T2
T
iS iR iZMINiZM
t0
iZ =iS+iR
-
Xc nh gi tr in tr tng ng Rei
eip
ZZpZ RU
TTR
UITIRTUI ===2
22
( )2 1ei p pTR R z RT= = 0 ei pR R
iZ
L
iS
SiRRp
U
uc
T1 T2
T
iS iR iZMINiZM
t0
iZ =iS+iR
-
4.5 B chuyn mch4.5.1 Mch LC
UdtdiLidt
Cu
t
C =++ 0
1)0((0) sin (0)cosC v v
U ui t i tLC
= +
v: tn s gc ca mch LC 1
v LC =
C uC
i
L
t = 0uC(0)
0
uCi
t
U
t = 0L
i
uC C Ot
uC(0)=0
uCi U
2U
V iV
S C
-
[ ]0
1(0)
(0) cos (0)sin
t
C C
C v v
u u idtC
LU u U t i tC
= + =
= + +
-
4.5.2 Phn tch b chuyn mch ca b bin i xung p
uc
S
iS
U
iV0
V0R
L
uZ
iZZ
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZ
-
Nhp V0 (0, t1)
iZ = iV0, uV0 = 0, uZ = 0
Gi thit uC = U
uV2 = 0; uV1 = U
iC = iV1 = iV2 =0
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZt
0
0
0
0
U
U
U
-K1U
K1U
uC iC
IZ
iV1
uV1
t0V1
uV2 iV2
t0V2
tIZ
iZ iV2
iV0
V0
T
T1 T2
V1V3
V1 V2 V0
K1U
UuZ
t20 t1 t3 t4 t5 t6 t7
QK
-
Nhp V1, V3 (t1, t3)
Ti t1 a xung iu khin m V1
uZ = U; uV0 = -uZ = -U V0 ng liiZ = iV1
1cos ( )C vu U t t=
1sin ( )C vUi t tLC
=
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZt
0
0
0
0
U
U
U
-K1U
K1U
uC iC
IZ
iV1
uV1
t0V1
uV2 iV2
t0V2
tIZ
iZ iV2
iV0
V0
T
T1 T2
V1V3
V1 V2 V0
K1U
UuZ
t20 t1 t3 t4 t5 t6 t7
QK
-
uV1 = 0iV1 = IZ - iCuV2 = -uCiV2 = 0
Ti t = t3, dng iC = 0; V3 ng li
uC(t3) = -K1U; K1 = 0.7 0.9
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZt
0
0
0
0
U
U
U
-K1U
K1U
uC iC
IZ
iV1
uV1
t0V1
uV2 iV2
t0V2
tIZ
iZ iV2
iV0
V0
T
T1 T2
V1V3
V1 V2 V0
K1U
UuZ
t20 t1 t3 t4 t5 t6 t7
QK
-
Nhp V1 (t3, t4)
Tt c cc i lng gi nguyn gi trti thi im t = t3
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZt
0
0
0
0
U
U
U
-K1U
K1U
uC iC
IZ
iV1
uV1
t0V1
uV2 iV2
t0V2
tIZ
iZ iV2
iV0
V0
T
T1 T2
V1V3
V1 V2 V0
K1U
UuZ
t20 t1 t3 t4 t5 t6 t7
QK
-
Nhp V2 (t4, t6)
Ti t = t4 a xung iu khin vo V2 m V2
uV2 = 0
in p ngc trn C t ln V1 ng V1
4
4
4 1
1( )
( )
t
C Z C C Zt
Z
i I u u t I dtC
I t t K UC
= = +
=
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZt
0
0
0
0
U
U
U
-K1U
K1U
uC iC
IZ
iV1
uV1
t0V1
uV2 iV2
t0V2
tIZ
iZ iV2
iV0
V0
T
T1 T2
V1V3
V1 V2 V0
K1U
UuZ
t20 t1 t3 t4 t5 t6 t7
QK
-
Nhp V2 (t4, t6)
iV2 = IZuV1 = uCiV1 = 0uZ = U uC = -uV0
Ti t = t6, uZ = 0 V0 m, V2 ng li Bt u nhp V0uZ(t6) = 0 uC = U
iiV1
V1
CuC
iC uV1V2
V3L1
UV0
Z
iZ
uZt
0
0
0
0
U
U
U
-K1U
K1U
uC iC
IZ
iV1
uV1
t0V1
uV2 iV2
t0V2
tIZ
iZ iV2
iV0
V0
T
T1 T2
V1V3
V1 V2 V0
K1U
UuZ
t20 t1 t3 t4 t5 t6 t7
QK
-
Np in cho t C khi bt u lm vic
M V2 trc ng t C trc tip vo ngun U qua mt in tr hn ch dng
Xc nh cc thng s C v L
V1 s dng khong (t4, t5) phc hi kh nng kha (t5 t4)MIN = toffV1
115 4
1( ) ZM offV
Z
I tK UCt t CI K U
= = V2 s dng khong (t1, t2) phc hi kh nng kha (t2 t1)MIN = toffV2
22
2 1 2
4( )
4 2offVv tTt t LC LC
= = =
-
4.6 Nguyn tc iu khin b bin i xung p
rng xung thay i T1 Tn s xung thay i T Hai gi tr
4.6.1 Nguyn tc iu khin rng xung
Gi nguyn f = 1/T, thay i T1
BK
M
uc BCM
C
T T1 T2
0
ucM uP uc
t
-
4.6.2 Nguyn tc iu khin tn s xung
Gi nguyn T1, thay i T
f = 1/T M
BK
M
uc BCM
Khupht xung
Tr T1
-
4.6.3 Nguyn tc iu khin hai gi tr
B pht xung ng vai tr ca mt b iu khin dng in
iZt
0
iZMINiZM
I'Z=IZ
ui1
ui2
iZ
ui1ui2
ui1 ui2
uc
uc > 0
uc < 0
M
uc
BCM
V0Z
iZ
ui1
ui2
uc
M
-
4.7 Cc b bin i xung nhiu gc phn t
-
4.7.1 B bin i hai gc phn t o chiu dng in
V
S1
US2
V0Z
uZ
iZ
-
4.7.2 B bin i hai gc phn t o chiu in p
)12(21 == zUTTTUUZi
z > 0.5 Uzi > 0z < 0.5 Uzi < 0
U
S1
V2
uZ
iZV1
S2
Z
S1S2 V1V2
S1S2V2V1
0
iZ
uZ
t
T1 T2 T
-
4.7.3 B bin i bn gc phn t
V2
V1
S2
S1 S3
S4V4
V3
Z
iZ
uZU
S2S1 S4S3
S3S4
S2S1 V4V3 V1V2
S4S3V2V1
iZ
uZ
t
0
0
S2S1 S1V3 S2S1 S3
V1 S3S4 S3V1
tiZ uZ
-
Chng 5: Thit b nghch lu
-
5.1 Khi nim chung Phn loi
Bin i nng lng in mt chiu thnh nng lng in xoay chiu
Phn loi
Theo s lng pha:- Mt pha- Ba pha- Nhiu pha
Theo s - Hnh cu- Hnh tia
Theo c im ngun- Ngun p- Ngun dng
-
5.2 S nguyn l
S nguyn l nghch lu cu mt pha
S nguyn l nghch lu tia v bn cu mt pha
S1 S3
S4 S2
R
uZU
S2S1 S2S1S4S3
0
uZ
= t
S1 S2
R
Ud
uZ
O
S1S2S1
Ud
= t
uZUd
Ud
S1
S2
R
uZ
-
Nghch lu cu ba phati thun tr
Ud
S1 S3 S5
S4 S6 S2
1 2 3uZ1 uZ2 uZ3
S1S2S3S4S5S6
3
Ud2
= t
uZ1
uZ2
uZ3
-
5.3 Nghch lu p
5.3.1 Dng cng sut hu cng v phn khng
P = UdId
P > 0 Id > 0: c. nghch luP < 0 Id < 0: c. chnh lu
=
==m
nndd piUp
1
Mang tnh cht ngun p: to ra in p xoay chiu. Dng in u ra ph thuc vo ti. u vo ca nghch lu p l ngun in p mt chiu
Udid
-id S
VR
P = Ud.Idp = Ud.id
1
2
3
p1Z1p2Z2p3Z3
-
5.3.2 Nghch lu p cu mt pha
: Gc d kin ng cc b khaS: Gc thng dng ca cc b kha
R: Gc thng dng ca cc diode ngc
VR2
VR1
S2
S1 S3
S4
VR4
VR3
iZ
uZUd
L R
Z
id
iVR1
iS1
-
S1,S2VR1,VR2
S3,S4VR3,VR4
uZ
R
= t Ud
S
-UdO
Ud/R
-Ud/R
2
iZ
iS1 = iS2
O
Id
iVR3 = iVR4
iS3 = iS4 iVR1 = iVR2
O
O
Ud
S1
S2
Z
iZ
S1,S2
ZiZ
VR3
VR4
VR3,VR4
S4
S3
ZiZ
S3,S4
-
5.3.3 Nghch lu p tia mt pha
Nhp S1:
uZ = ua = Ud
iS1 = id = iZ tng theo ng cong hm m
=
-
Nhp VR2:
uZ = ub = -UdiVR2 = -id = iZ gim theo ng cong hm m
Ngt xung iu khin a vo S1. Do nh hng ca L trong ti, dng in trong cun th cp v qua dng trong cun s cp vn gichiu c. Dng trong cun s cp chy qua VR2 v qua na phi ca cun s cp.
Nhp VR2 kt thc khi dng iVR2 gim v gi tr 0
-
Nhp S2:
uZ = ub = -UdiS2 = id = -iZ tng theo ng cong hm m vi chiu ngc li
Xung iu khin a vo S2 ngay sau khi ngt S1. Khi VR2 ng, dng s chy qua S2. in p trn ti vn khng i, tuy nhin dng iZs o chiu
Nhp S2 kt thc khi ngt xung iu khin a vo S2 v bt u a xung iu khin vo S1
-
Nhp VR1:
uZ = ua = UdiVR1 = -id = -iZ tng theo ng cong hm m
Ngt xung iu khin a vo S2. Do nh hng ca L trong ti, dng in trong cun th cp v qua dng trong cun s cp vn gichiu c. Dng trong cun s cp chy qua VR1 v qua na tri ca cun s cp.
Nhp VR1 kt thc khi dng iVR1 tng ln gi tr 0
-
5.3.4 Nghch lu p cu ba pha
-
TI
-
5.3.5 iu khin nghch lu p cu 3 pha
Nguyn tc thay i tn s xung
Nguyn tc iu bin rng xung - PWM
IN P RNG CAiN P IU KHIN
ln: Ud Tn s: tn s pht xung vo cc b kha
Pht xunguc Phn phi
xungKhuych i
xung
S1, S3, S5 S2, S4, S6
uZ1 = uZ2 = uZ3 = 0
-
5.4 Nghch lu dng5.4.1 Hai chc nng ca b chuyn mch
trong nghch lu dng
t in p ngc ln thyristor, ng thyristor. Tham gia vo qu trnh
chuyn mch
-
5.4.2 Nghch lu dng mt pha
Gi s V1, V2 m, dng in qua tiiZ = Id
in p trn cc t uC1 < 0, uC2 < 0.
Mun ng V1, V2: m V11, V12.
Dng iZ = Id chy qua V11, C1, C2, V12 in p trn cc t o chiu.
Trong thi gian in p trn cc t cn
-
i vi ti L: uV3 = uC1, uV4 = uC2 V3, V4 m khi uC1 = uC2 = 0
Dng in chy qua V11, C1, Z, C2, V12gim dn. Dng in chy qua V3, Z, V4tng dn.
B chuyn mch thc hin chc nngth hai
Qu trnh chuyn mch kt thc khiiV3 = iV4 = -iZ = Id
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5.4.3 Nghch lu dng 3 pha
Thyristor chnh: V1, V2, , V6 T chuyn mch: C13, C35, , C 26, C24 Diode phn cch: V11, V12, , V16.
0120 = V1V2V3V4V5V6
iZ1
iZ2
Id-Id
iZ3
-
Nhp V1, V2, V11, V12
iZ1 = Id; iZ2 = 0; iZ3 = -IduC13 > 0uV3 = uC13 > 0: V3 ang trng thi kha
Nhp V3, V11, V2, V12
a xung iu khin m V3.uC13 ng V1.Dng Id chy qua V3, C13, song song vi C13 l C35 v C15, V11, vo pha 1.uV13 = uZ12 uC13 < 0 ... V13 vn ng.Id s o chiu in p trn C13.
B chuyn mch thc hin chc nng th 1
-
Nhp V3, V11, V13, V2, V12
Khi uV13 = uZ12 uC13 = 0 ... V13 m ... Dng chy qua V3 v V13 vo pha 2.
Qu trnh chuyn mch: dng chy vo pha 1 gim dn, dng chy vo pha 2 tng dn.
B chuyn mch thc hin chc nng th2: tham gia vo qu trnh chuyn mch
Qu trnh chuyn mch kt thc khi dng chy vo pha 1 gim v 0 v dng chy vo pha th 2 bng Id.
Chuyn sang nhp V3, V13, V2, V12
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5.4.4 iu khin nghch lu dng
-
Chng 6: Thit b bin tn
-
6.1 Khi nim chung Phn loi
Dng bin i nng lng in xoay chiu bng cch thay i tn s
Phn loi theo s lng pha- Mt pha- Ba pha- m-pha
Phn loi theo s - Trc tip- Gin tip
+ Ngun p+ Ngun dng
-
6.2 Bin tn trc tipBin i trc tip in p xoay chiuthnh in p xoay chiuc tn s khc
-
12 1 2( 1)
TT T np
= + n: s na chu k in p u vo to nn na chu k in p u ra2 1
1 2 2( 1)f T pf T p n
= = + [ ] 1 12 2( 1)T TT p n qp p
= + =
-
Tn s in p u ra f2 < 25Hz v khng th iu khin v cp
Bin tn trc tip t c s dng
[ ] 1 12 2( 1) T TT p n qp p= + =i vi bin tn 3 pha:
-
6.3 Bin tn gin tip
6.3.1 Bin tn ngun p
CHNH LU NGHCH LU P
UdII > 0
Cf, Lf: mch lcMch lc cng vi chnh lu to thnhngun p mt chiu u vo canghch lu p
Cf: nhn dng phn khng.
Nguyn tc iu khin:
Nguyn tc iu khin tn s xung:
f2: tn s xung pht vo nghch luU2: s dng chnh lu c iu khin, hoc s dng chnh lu khng iu khin
v b bin i xung p Nguyn tc PWM chnh lu ch cn l khng iu khin.
UdI > 0 IdI > 0 PI > 0 Cng sut khng th o chiu
-
6.3.2 Bin tn ngun dng
CHNH LU NGHCH LU DNG
Lf: Mch lc
Chnh lu v mch lc phi ctnh cht ngun dng mt chiu
Nguyn tc iu khin:
f2: tn s xung pht vo nghch luI2: s dng chnh lu c iu khin.
Id > 0 UdI > 0 hoc < 0 Cng sut c th o chiu
-
Chng 7B kha xoay chiu
v thit b bin i in p xoay chiu
-
7.1 Khi nim chung Phn loiB kha xoay chiu: ng, ct dng xoay chiuThit b bin i in p xoay chiu: thay i gi tr in p xoay chiu
Phn loi theo s lng pha- Mt pha- Ba pha- m-pha
Phn loi theo s - C bn- Tit kim
Phn loi theo phng php iu khin- iu khin hon ton- Bn iu khin
-
7.2 B kha xoay chiu
7.2.1 B kha xoay chiu mt phaNG
NGT sinmZ
Z UuddiLRi ==+
Z: gc bt uiz(z) = 0
( )sin( ) sin( )Z
Rm m L
Z zU Ui eZ Z
=
2 2 2 ; arctan LZ R LR
= + =
f1() f2()
-
NG
NGT
-
7.2.2 B kha xoay chiu ba pha
Gm 3 b kha 1 pha
-
7.3 Thit b bin i in p xoay chiu
Ti thun tr R
7.3.1 Thit b bin i in p xoay chiu mt pha
-
Ti R, L:
Khi < <
( )
sin( )
sin( )
mZ
Rm L
UiZ
U eZ
=
Z =
Khi 0 < < Khng iu khin c in p.Thit b lm vic nh b kha xoay chiu
-
Ti L
Khi /2 < <
(cos cos )mZUiL
=
Khi 0 < < /2Khng iu khin c in p.Thit b lm vic nh b kha xoay chiu
= /2
-
7.3.2 Thit b bin i in p xoay chiu ba pha
Gm c ba b bin i in p xoay mt pha mc vi nhau
-
CHNG 8: BO V V IU KHINCC THIT B BIN I
-
8.1 Bo v cc phn t in t cng sut8.1.1 Cng sut tn tht v lm mt
1 2 1P p p p = + P Cng sut tn tht
1p Cng sut tn tht chnh2p Cng sut tn tht ph
20 ( )T AV FP U I R I = +
-
j a th
th jv vr ra
T T R P
R R R R
= + = + +
Nhit mt ghp
Tj Nhit mt ghpTa Nhit khng kh mi trngRjv in tr nhit gia mt ghp v v linh kin bn dnRvr in tr nhit gia v v cnh tn nhitRra in tr nhit gia cnh tn nhit v khng kh mi trng
Lm mt:
Cnh tn nhit Cnh tn nhit + qut gi Cnh tn nhit + nc Ngm trong du bin th
-
8.1.2 Bo v dng in
Cu ch:
CC phi chu c dng lm vic nh mc ca thit b Nhit dung chu ng ca CC phi nh hn nhit dung ca thit b cnbo v nhit lng (I2t)CC < (I2t)TB
in p h quang ca CC phi tng i ln Gim nhanh dng inv tiu tn nng lng trong mch.
Khi CC t, in p phc hi phi ln Khng lm cho h quang chyli gia hai cc ca cu ch
Lp t: c nhiu cch
Tng pha ca cun dy s cp hoc th cp MBA Ni tip vi tng van Ni tip vi tng nhm van mc song song u ra ca thit b bin i
-
8.1.3 Bo v qu p
Qu p trong
S tch t in tch trong cc lp bn dn(qu trnh ng ca diode v thyristor) Bo v bng mch R C u song song vi diode hoc thyristor
Qu p ngoi
Ct khng ti MBA trn ng dy, CC bo v nhy, sm st, Bo v bng mch R C mc gia cc pha th cp ca MBA ng lc
R .. 10 1000 C 0.01 1 F
-
8. 2 iu khin cc thit b bin i8.2.1 Khuych i thut ton
2
1r v
Ru uR
=
Khuych i o
Mch so snh
...
...cc
rcc
U u uu
U u u ++
>= + >
-
Mch tch phn
1r vu u dtRC
=
-
+
R
Cur v
rduu RCdt
=
Mch vi phn
-
8.2.2 Mch to xung chun s dng IC 555
-
1 1 2 2 2
1 2 1 2
0.693 ( ); 0.6930.693 ( 2 )
t C R R t CRT t t t C R R
= + == = + = +
Mch lt n s dng IC 555
1.1T RC=13 ccV