Transcript Slide 1
Capacitor and Inductor Using PSpice
First Edition: 18/8/09
Modeling Capacitor in PSpice
1
I1
C1
R1
0
We have to put a big resistor (e.g. 1G) across a
capacitor to provide a DC current path to ground.
This is because a capacitor acts as open circuit to
DC (No DC path is provided by capacitor). PSpice
always requires a DC path to ground for its calculation.
Modeling Inductor in PSpice
1
R1
1x
L1
V1
0
We have to put a small resistor (e.g. 1u) in series
with an inductor to avoid the DC current in the
inductance infinitely large.
This is because an inductor acts as a short circuit
to DC.
Modeling PWL Sources (I or V)
1x
1
1
R1
I1
C1
R1
or
V1
L1
0
0
I1
or
V1
(2ms,100)
100
I1 0 1 PWL(0,0)(2ms,100)
50
(0,0)
0
0s
or
0.5ms
1.0ms
V1 1 0 PWL(0,0)(2ms,100)
1.5ms
2.0ms
Time
2.5ms
3.0ms
3.5ms
4.0ms
To Set Analysis Request
Type of Analysis: Transient
General format:
.TRAN TSTEP TSTOP <TSTART <TMAX>>
Example:
.TRAN 5u 5m 0 5u or .TRAN 5m 5 0 5m
TSTEP and TMAX determine the time increment. To make the
thing simpler, set the same values for both TSTEP and TMAX. If
the time increment is not small enough, the plot will not be
smooth.
PSpice will generate data from 0 (TSTART) to 5ms (TSTOP)
with the time increment of 5u (TSTEP or TMAX). So, at least 1000
data will be generated.
To Get Add Trace Expression
Capacitor Voltage
ic(t)
V(1)
Capacitor Current
ic(t)
I(C1)
Capacitor Power
vc(t)ic(t)
V(1)*I(C1)
Capacitor energy
v
C
(t )iC (t )dt
S(V(1)*I(C1))
* What you will really type in the trace expression:
box depends on your own netlist description.
*
EXAMPLE 6-1
1
I1
C1
R1
Capacitor circuit
I1 0 1 PWL(0,0)(2m,100)
C1 1 0 1mF IC=0
R1 1 0 1G
.Tran 4u 4ms 0 4u
.Probe
.end
0
300
200
Capacitor Current
100
0
0s
V(1)
0.5ms
I(C1)
1.0ms
1.5ms
2.0ms
Time
2.5ms
3.0ms
3.5ms
4.0ms
EXAMPLE 6-2
1
V1
C1
R1
Capacitor circuit
.param pi=3.141592654 w=6000
V1 1 0 SIN(0 10 {w/(2*pi)} 0 0 90) ; cosine
C1 1 0 5uF IC=10
R1 1 0 1G ; to satisfy PSpice requirement
.Tran 3u 3m 0 3u
.Probe
.End
0
8.0
Capacitor voltage
4.0
0
-4.0
-10.0
V(1)
400m
Capacitor current
0
-400m
0s
0.5ms
1.0ms
1.5ms
I(C1)
Time
2.0ms
2.5ms
3.0ms
EXAMPLE 6-3
1
V1
C1
R1
Capacitor circuit
V1 1 0 PWL(0,0)(2,100)(3,50)
C1 1 0 5mF IC=0
R1 1 0 1G
.Tran 5ms 5s 0 5ms
.Probe
.end
0
40
Power
0
-40
V(1) * I(C1)
40
Energy
20
0
0s
0.5s
S(I(C1) * V(1))
1.0s
1.5s
2.0s
2.5s
Time
3.0s
3.5s
4.0s
4.5s
5.0s
EXAMPLE 6-4
Inductor circuit
V1 1 0 PWL(0,30)(0.9999m,30)(1.0001m,-10)
+(2.9999m,-10)(3.00001m,0)
R1 1 1x 1u
L1 1x 0 50mH IC=0
.Tran 4us 4m 0 4us
.Probe
.End
1x
1
R1
L1
V1
0
30
V(1)
0
-10
V(1)
1.0A
I(L1)
0A
0s
0.5ms
I(L1)
1.0ms
1.5ms
2.0ms
Time
2.5ms
3.0ms
3.5ms
4.0ms
Using Toggle Cursor
Probe toolbar
Toggle Cursor
1. By clicking Toggle Cursor toolbar, we will get access to Cursor toolbar.
Cursor toolbar
Cursor Peak: to get the peak
point on the plot.
Mark label: to mark the data
point on the plot.
Cursor Peak
Cursor Search
Mark Label
Cursor Search: to search data point on the plot. For example, by typing
SFXval(3s) in Search Command box, the Probe Cursor will point at x=3s.
Using Toggle Cursor
Toggle Cursor Toolbar is used to get access to data points on a plot
through the Probe Cursor. We can toggle the display of the Probe cursor
on and off by clicking the Toggle Cursor toolbar.
2. Also, by clicking the cursor toolbar, we will
be given access to two cursors. One of the cursors
is controlled by the left mouse button [A1 = (x,y)]
and one is controlled by the right mouse button [A2
= (x,y)]. A small window labeled Probe Cursor gives
the values at each of the cursors as well as the
difference between them. We can also finely move
the cursors by using left-arrow and right-arrow on
the keyboard.
3. Marking a specific voltage/current level. By clicking Mark Label toolbar
will label the specific point on the plot, which is pointed to by the cursor that
was last moved.