§ 1-1 Introduction
The voltage source
The current source
The resistor
The inductor
The capacitor
1 Circuit models（模型）
Two active（有源） models
Three passive(无源） models
current
controlled voltage
source
Voltage
controlled current
source
current
controlled current
source
(CCVS)
(VCCS)
(CCCS)
Voltage
controlled voltage
source
(VCVS)
2,Network variables (网络变量 )
The systems of units (M.K.S.system) (单位制 )
Length [meter] (m)
Mass [kilogram] (kg)
Time [second] (s)
(1) Current--i(t),I ---- (A,mA,μA...)
The net time-rate of transference (传递 ) of charge is
referred to as the flow of current.
? ???? t ditqdtdqti ?? )()()(
(2) Energy (or work)--w(t) (J)
(4) Power--p(t) (W,k W,m W)
)()()( titdtdqdqdwdtdwtp ????
? ???? t d)()t(dt )t(d)t( ??????
(5) Flux linkages(磁通链 )--- (weber-turn)?
The time rate of performing work is defined as power.
L
dq
dwt ?)(?
(3) Voltage --- (kV,V,mV)
The ratio of work to charge is given the name voltage.
)t(?
7
3,Reference directions(参考方向 )
)(ti 0)( ?ti
? ?
0)( ?ti
? ?
(1) Reference directions for current
)(t?
?
?
0?)t(?
?
??
?
0)( ?t?
?
?
?
?
(2) Reference directions for voltage
7
(3) Reference conventions (惯例 ) for two-terminal
elements (R,L,C or,.,)
)(ti
R
?
?
)t(?
The relative (关联 ) reference directions
The reference arrow for the current variable enters
the terminal,which is identified by the plus sign of the
voltage reference polarity markings.
)(ti
?
?
)t(?
(4) The reference for power
p(t)<0 the negative power absorbed by the
element or it is actually generating power and
delivering it to some external element.
)()()( tittp ??
p(t)>0 the power absorbed by the element.
?
?
)t(?
)(ti