Upload
hieuhuech1
View
212
Download
0
Embed Size (px)
DESCRIPTION
C9_BDNLDC_BaiGiang8
Citation preview
Bin i Nng Lng in C NQN-TCB, HCMUT, 2013
1
1 My in cng sut nh
H Bch Khoa TP.HCM Khoa in-in T B Mn Thit B in
Bi ging: Bin i nng lng in c
Chng 9: My in cng sut nh
Bin son: Nguyn Quang Nam Cp nht: Trn Cng Binh
NH20122013, HK2
2 My in cng sut nh
Mt s loi my in cng sut nh trong cc ng dng
dn dng v cng nghip s c gii thiu.
Cc loi my in sau s c gii thiu: ng c 2 pha,
ng c 1 pha, ng c servo (DC v AC), ng c t tr,
ng c bc, v c cu chp hnh (actuator).
Bi ging ch gii thiu chi tit hn v ng c 1 pha v
ng c bc, l nhng ng c c ng dng ph bin.
Sinh vin s c cung cp ti liu c thm v cc loi
my in cng sut nh khc.
My in cng sut nh Gii thiu
3 My in cng sut nh
ng c khng ng b u tin c ch to th l mt
ng c 2 pha, trong 2 cun dy c t lch nhau 90
in trong khng gian, v c cung cp h dng in lch
pha 90 in theo thi gian.
Vi cu hnh nh trn, cc cun dy s to ra mt t
trng quay trn u, v s khin rto lng sc t trong t
trng quay theo.
H thng AC 2 pha tuy nhin km hiu qu so vi h thng
AC 3 pha, do cc ng c KB tr thnh cc thit b 3
pha, ngay khi chng minh c nguyn l.
ng c khng ng b 2 pha Gii thiu
4 My in cng sut nh
Dy qun stato bao gm 2 dy qun t lch pha 90
trong khng gian, v s to ra t trng quay trn nu c
cung cp bi mt h dng in 2 pha lch nhau 90 in.
Nu c th to ra h dng in 2 pha t ngun AC 1 pha,
th ng c s c th vn hnh t ngun 1 pha => ng c
khng ng b 1 pha.
C th chng minh rng ng c KB 1 pha c th vn
hnh vi ch 1 dy qun c cp ngun, vi chiu quay
khng nh trc v khng c mmen m my.
ng c KB mt pha Gii thiu
5 My in cng sut nh
Trong thc t, ngi ta thm vo dy qun th hai (dy
qun ph), v dng mt s phng php to ra m men
m my hay duy tr mt h dng in 2 pha c hiu qu. T
dn n cc loi my KB 1 pha: phn pha, c t khi
ng, c t thng trc, c t khi ng v thng trc,
phn pha khi ng/t thng trc, c khu t cc.
Khng c l do g mt kiu rto khc, do rto trong
cc ng c KB 1 pha thc cht l cc rto lng sc nh
trong cc my 3 pha.
ng c KB mt pha Gii thiu (tt)
6 My in cng sut nh
nh chp ng c AC 1 pha thc
Bin i Nng Lng in C NQN-TCB, HCMUT, 2013
2
7 My in cng sut nh
Cc phng php kch thch dy qun ph
Phn pha
T khi ng T thng trc
T khi ng/ T thng trc
Phn pha khi ng/ T thng trc
8 My in cng sut nh
Cc phng php trn u khng to ra h dng in 2
pha l tng (lch pha 90 in). Do , t trng sinh ra c
dng elip v s to ra mmen b dao ng.
V cc li in gia dng thng l 1 pha, cc ng c
ny c s dng trong hu ht cc thit b in gia dng 1
pha nh: bm, qut, my git, t lnh, .
c im v ng dng
9 My in cng sut nh
ng c servo (cn gi l ng c tha hnh) l mt b
phn ca h thng iu khin chuyn ng hoc iu khin
v tr. V phc v cho mc ch iu khin, cc ng c ny
c mc cng sut va phi, thng khng qu 1 HP, v
nm trong nhm ng c cng sut nh.
ng c servo cn phi p ng cc yu cu: tc p
ng nhanh, di tc lm vic rng, lm vic n nh v lu
di tc thp (n 0).
ng c servo
10 My in cng sut nh
ng c servo c th thuc mt trong cc dng: ng c
AC (ng c KB), ng c DC, v ng c BLDC.
ng c tha hnh DC c s dng trc tin, nh u
im v mt iu khin. Ngy nay, vi s tin b ca k
thut iu khin v cng ngh in t cng sut, cc ng
c tha hnh AC v BLDC ang ngy cng pht trin, nh
khc phc c nhc im chi than + c gp ca ng
c tha hnh DC.
ng c servo (tt)
11 My in cng sut nh
ng c t tr l ng c trong m men c to bi
xu hng chuyn n trng thi lm cho t cm ca dy
qun ang c kch thch tr nn cc i.
Stato ca ng c ny gm cc cc t li vi cc dy
qun kch t (ging nh ca ng c DC, v r to dng cc
li m khng c bt k dy qun hay nam chm trn n.
Vi cu trc cc k n gin v chc chn nh trn, ng
c ny c ch nh gi thnh rt thp v tnh bn vng.
ng c t tr chuyn mch
12 My in cng sut nh
ng c t tr chuyn mch (tt)
Bin i Nng Lng in C NQN-TCB, HCMUT, 2013
3
13 My in cng sut nh
Cm t chuyn mch c gn lin vi tn gi v phi
c thao tc chuyn mch rto lin tc di chuyn t cc t
ny sang cc t kia.
Mc d c nguyn tc hot ng ging nh ng c
bc, ng c t tr chuyn mch c ch to nh mt
ngun c nng, khc vi ng c bc phc v cho mc
ch iu khin.
Cn c cm bin v tr rto iu khin chuyn ng.
ng c t tr chuyn mch (tt)
14 My in cng sut nh
ng c bc c cu to tng t nh ng c t tr
chuyn mch. Tuy nhin, ng c bc c ch to c
kh nng t gi v tr trong iu kin ti c thit k, v s
quay 1 gc nh trc i vi mi xung dng kch thch vo
cun dy stato thch hp.
Nh thit k trn, ng c bc c dng trong cc ng
dng o lng v iu khin cht lng cao, nh my CNC,
my in phun, bm nh lng, ...
ng c bc Gii thiu
15 My in cng sut nh
Cc u im ca ng c bc: gc quay t l vi s
xung ng vo, nh v chnh xc v c sai s khng tch ly
gia cc bc, p ng nhanh, cc k tin cy nh kt cu
chc chn, khng cn tn hiu hi tip v tr.
Phn loi ng c bc theo tnh cht rto: t tr thay
i, nam chm vnh cu, v kt hp hai loi trn. Cc cun
dy stato c th dng n cc (cp dng theo 1 chiu)
hoc lng cc (dng in c th chy theo c hai chiu).
ng c bc Gii thiu (tt)
16 My in cng sut nh
Hnh di y minh ha hot ng ca ng c bc vi
cun dy n cc, gc bc danh nh l 15.
ng c bc S nguyn l
17 My in cng sut nh
Chiu quay ca ng c c quyt nh bi th t kch
hot cc pha dy qun stato.
Tn ti cc k thut iu khin chia nh hn na cc
bc ca ng c, nng cao cht lng iu khin m
khng tn thm chi ph phn cng. Cc k thut ny c
gi l k thut na bc (half-step) v vi bc (microstep).
Cc cun dy thng c in cm nh, do thng i
hi mt c ch gii hn dng in (thng dng PWM).
ng c bc iu khin