§ 2-5 Maximum power transfer in the DC case
LS
S
L RRi ??
?
L
LS
S
LLRL RRRRip
22 )(
???
?
4
2
2 2
)(
)()()(
LS
LSLLS
SRL
L RR
RRRRRp
dR
d
?
????? ?
Equation is satisfied when R L= R S.
The maximum power is
L
S
R
P
4
2
m a x
??
03
2
???? )( )(
LS
SLS
RR
RR ?
Example,What is the maximum power that can be
delivered to an external load RL by the network.
111 5.14020 ??
?? ????
oc V24)2.040(30 1
11 ??? ??
Voc 36??
120403020 302040 11,,?????? ??sci 4.2303020 202.01 ??????
?????? 20018.0/3618.012.040 4.2 thsc Ri
WP 62.12 0 04 36 2m a x ???
Solution:
sci
oc?
{ R 两端并何元件，使 i=0}
i
active
source
controlled
node
path
loop
reference
branch
clockwise
counterclockwise
A mesh current may often be identified as abranch
current,as i1 and i2 are identified above.This is not
always true,however,for consideration of a square
nine-mesh network soon shows that the central mesh
current cannot be identified as the current in any
branch.
There is also no reason that an independent
source must assume only its given value or a
zero value in the several experiments; it is only
necessary for the sum of the several values to be
equal to the original value,An inactive source
almost always leads to the simplest circuit,
however.