C. Dien ap hieu dung hai dau dien tro nho hon di?n ap hieu dung hai dau doan mach.
PHl/CTNG PHAP
+ Cuong do dong d i ^ n trong mach: i = IQ cos(cot + (p,)
+ Hieu di?n thehai dau dien tro:
' U K =U„KCOs(cot + ( P u j J - U„ K C o s( c o t + (p,)
+ Hieu d i^ n thehai dau cuon cam thuan:
U L= U o L C O s( ( o t + (p, ) = U„i_cos wt + ( P i + - =-UoLsin(cot + (Pi)
+ Hieu d i^ n thehai d a u ty dien:
uc = U()c cos((ot + (puc ) = cosj^cot + <Pi - 2 J " Uocsin ((ot + cpi)
Bicu dien ca bon ham i ; u K ; U L ; U ( ; tren cimg mot d u o n g tron lugng giac n h u sau + Cuong dp dong di?n trong mach:
i ^-1,) cos((ot + (pj) la ham cosin
cung chieu true cosin c6 chieu (+) t u trai sang phai voi bien do la
^ ' m a x - IQ
+ Hi^u di?n the hai dau di?n tro:
" R = ^QR cos(cot + (P|) la ham cosin
=> cung chieu true cosin c6 chieu (+) t u trai sang phai voi bien do la
=>'jRtnax ='UoR thuan
+ Hi?u di^n the hai dau cupn cam: U L =-UoLsin((ot + (Pi)
La ham trir sin =:> nguoc chieu true sin nen c6 chieu (+) huong tu tren
xuong voi bien d p U L ^ J X = ^ O L va (p^^^ = 9i + ^
+ H i ^ u di^n the hai dau ty di^n: u ^ = Uocsin((ot + cpj) la ham sin => cung
chieu true sin nen co chieu (+) hudng t u d u o i len voi bien do
TTTTJ^ VIC I
m V I DU MAU
Vi du 1: Cho mach dien xoay chieu gom di?n tro thuan R, cuon day thuan 10 -3
cam L va tu dien C = F mac noi tiep. Bieu thuc di?n ap gii>a hai ban tu dien la u = 5 0 N / 2 C O S l O O T T t - 37t
khi t = 0,01 (s) la
A. +5(A). B. -5(A).
(V). Cuong do dong dien trong mach
C . - 5 V 2 ( A ) . D.+5V2 (A).
^hdn tick vd hir&ng ddn gidi
hAiion fun ciimi\; do don;^ dien fai mot thai diem cu thenao do thi viec lam bSt buoc la phai vict dime phiron;^ tr'inh cm amng do dong dim sau do chi can thai/ t vao phu'o'ng trinh la c6 ngay dap an.
Dung khang cua tu dien: ZQ = 1 (adsbygoogle = window.adsbygoogle || []).push({});
100 J °
7t
-3 = 10Q
Bieu thiic cuong do dong dien trong mach (nhanh pha hon dien ap hai dau
tu mot goc nil):
1 = — ^ c o s 5CW2
10 -cos l O O n t - Z c I '"^ 2.
Hay 1 = 5s/2cosf 1 0 0 7 t t - - l ( A )
Khi t = 0,01 (s) thi cuong do dong dien trong mach:
STT 71
— + — ( A )
i = 572 cos I 10071.0,01 - - 1 ( A ) = 5^2 cosf T: - - 1 = 5>y2 C h p n d a p an B
V 2 I
= - 5 A
Vi du 2: Mach R noi tiep voi C. Dat vao hai dau mach mot di?n ap xoay chieu CO tan so f = 50Hz. Khi dien ap tuc thai hai dau R la 20>/7 V thi cuong do dong di?n tuc thoi la Vz A va d i ^ n ap tuc thoi hai dau tu la 45V. Den khi dien ap hai dau R la 40 ^3 V thi dien ap tuc thai hai dau tu C la 30V. T i m C A. 3.10 -3 871 B. 2.10 -3 371 C. 10 - 4 D. 10 -3 871
^hdn tich vd hu&ng ddn gidi
Cdc bai todn lien quan tai su vuong goc thi viec dau tien cac ban nen nghi t&i Id he thi'tc doc lap theo thai gian. Dien nay chitng ta dd gap rat nhieu trong chuang dao dong ca vi the bai todn nay dugc gidi quyel nhanh nhu sau: ,. , ,
BI quyei on luycit tlu nat nt?c uui uiem lui ua vui n, lap^i - L.e vun vinn
Do mach chi c6 R noi tiep vai C nen UR va U c luon vuong pha nhau. Neu gpi phuang trinh ciia i c6 dang: i = IQ COS cot (1)
phuong trinh aia U R C6 dang: M,^ =Uf^^cosCDt (2) phuang trinh ciia c6 dang: U c = UQC COS cot —