ECA - Ch1.7 1

1.7 Cac phep bien oi tng ng mach

1.7.1 Gii thieu :

n gian hoa s o bang cach dung cac luat bien oi, bao toan u,i phan mach con lai.

Co y ngha thc tien ln . Cho li giai nhanh chong .

ECA - Ch1.7 2

1.7.2 Bien oi nguon ly tng :

n

td kk 1

e e=

=

Nguon ap noi tiep :

e1

e2

en

etd

Xet dau :

ECA - Ch1.7 3

1.7.2 Bien oi nguon ly tng :

n

td kk 1

J J=

= Jtd

Nguon dong song song :

J1 J2 Jn

Xet dau :

ECA - Ch1.7 4

1.7.2 Bien oi nguon ly tng :

Lu y :

e = e1 = e2e1 e2 Khong ton tai neu e1 e2 .

Khong ton tai neu J1 J2 .

J1J2

J = J1 = J2

ECA - Ch1.7 5

1.7.2 Bien oi nguon ly tng :

Nguon ap song song nhanh :

e

e

J

J

Nguon dong noi tiep nhanh :

ECA - Ch1.7 6

1.7.3 Bien oi tng ng mach ien tr

a) ien tr noi noi tiep :

b) ien dan noi song song :

n

eq kk 1

R R=

=

n

eq kk 1

G G=

=

ECA - Ch1.7 7

V du: Tng ng mach ien tr

Hai ien tr noi song song :

1 2eq

1 2

R RRR R

= +

ECA - Ch1.7 8

c) Bien oi ien tr noi Y- :

1 2( )

12 23 31

( )Y node

R R to nodeRR R R = + +

1 2 1 3 3 2

( )Y

R R R R R RRR facing node

+ +=

ECA - Ch1.7 9

1.7.4 Mach chia ap

a) Mach gom 2 ien tr :

b) Mach gom N ien tr :

11

1 2

Ru uR R

= +2

21 2

Ru uR R

= +

kk N

ii 1

Ru uR

=

=

ECA - Ch1.7 10

1.7.5 Mach chia dong

b) Mach gom N ien tr :

Fk 0

k

Ri iR

=

21 0

1 2

Ri iR R

= + 12 01 2

Ri iR R

= +

a) Mach gom 2 ien tr :

i0

ECA - Ch1.7 11

1.7.6 Mach nguon tng ng

Su E R .i= S

1i J uR

=

SE R .J= Hai mang mot ca la tng ng neu thoa :

Cho 2 mang mot ca (la 2 mach nguon thc) :

ECA - Ch1.7 12

Source Transformation :

(a) Independent source transform

(b) Dependent source transform

The arrow of the current source is directed toward the positive terminal of the voltage source.

The source transformation is not possible when R = 0 for voltage source and R = for current source.

++

++

--

--

ECA - Ch1.7 13

1.7.7 Lu y khi dung bien oi tng ng

Phan mach b bien oi khong c cha tn hieu b phu thuoc.

Ch bien oi neu ta di tn hieu b phu thuoc o i ni khac.