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Trng H BK TPHCM Khoa ien - ien t
e thi hoc ky mon ien t cong suat 1
E THI HOC KY 2 - MON : IEN T CONG SUAT 1- 1Ngay thi :
27/06/2006- Thi gian lam bai 90 phut- SV c s dung tai lieu. Sinh
vin vtrc tip vo
bi lm v np thi cng vi bi lm.
Cau 1 (4) : Cho bo chnh lu cau ba pha ieu khien hoan toan . Ap
nguon xoay chieu ba pha co trhieu dung Upha=220V, tan so 50Hz. in p
pha cc pha ngun ln lt l u1,u2,u3, in p dy l u12,u23 vu31. Mach xac
lap..
Figure 1
Cho biet goc kch bang 600, tren cung mot toa o thigian (hoac
goc). Gias dong tai lien tuc vaphang va co
o ln bang 10A, haya. Ve dang ien ap tai trnhnh 4a [0.5]
b. Ve dang dong ien qua pha nguon u1 trnhnh 4b[0.5]
c. Tnh tr trung bnh ien ap chnh lu [0.5]d. Tnh he so cong suat
nguon cung cap [0.5]
Neu s dung tai thuan trR=100[Ohm], va goc kchbang 60 o, haye.
Vdang ien ap tai trn hnh 5a [0.5]f. Vdang dong ien qua nguon u1
trnhnh 5b [0.5]g. Tnh tr trung bnh ien ap tai [0.5]h. Cong suat
trung bnh cua tai [0.5]
Cau 2 (3.5): Cho bo bien oi ien ap mot chieu tong quat trnhnh 2.
Tai RLE vi R=1, L=0.1H,E=50V. Nguon ap mot chieu ngo vao bo bien oi
co gia tr U=150[V]. Bobien oi c ieu khien theophng phap tan soong
cat khoa khong oi co gia tr la fsw= 500Hz, cc khaS1, S2 c kch ng
thi,tng tcho S3 v S4. Gia thiet mach trang thai xac lap va dong tai
lien tuc.
Figure 2
1. Tnh thi gian kch cho S1,S2 v S3,S4 dng tit gi trtrung bnh
+30A [0.5].
2. Gi s trong cu 1, dng ti khng i (+30A).Trong 1 chu k ng ngt,
hy vit phng trnhdng qua linh kin IGBT S1 [0.5], vthdngqua n [0.5] v
tnh trtrung bnh dng in trn[0.5].
3. Gismch ti trcng sut vngun dc vi scin ng E= --100V. Dng qua ti
phng +30A.Xc nh thi gian kch S1,S2 v S3,S4 [0.5].
Trong chu kng ng
t, hy vi
t ph
ng trnh mt dng in qua ngun dc [0.5] v xc nh tr
trung bnh dng np cho ngun [0.5]
Cau 3 (2.5) : Cho bo nghch lu ap mach cau ba pha trnhnh 3. Chu
ky pti la 10ms. Ap nguon motchieu cogia tr Ud=500V. Tai ba pha RL
au sao vi Ra= Rb= Rc= 2, La = Lb= Lc = 2mH. Xet mach trang thai xac
lap.
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Trng H BK TPHCM Khoa ien - ien t
e thi hoc ky mon ien t cong suat 2
Figure 3
GisBNL pc ieu khien theo phng phap ieu
bien (six-step)1. Tnh trhiu dng in p ti [0.5]2. Tnh trhiu dng
thnh phn cbn ca in p pha ti
[0.5] v dng ti [0.5]Gi s s dng k thut iu ch rng xung, so snh
sng iu khin udka, udkb,udkc ca 3 pha vi sng mangtam gic up to
xung kch.3. V xung kch cho S1,S3 v S5 trn hnh 6b (0.5)4. Vdng in p
ti - pha A trn hnh 6c (0.5)
Figure 4
