frequency simulation in orcad pspice 9.2 Lite

Discussion in 'Homework Help' started by nesrine, Oct 4, 2013.

1. nesrine Thread Starter New Member

Oct 4, 2013
8
0
Hi, I am trying to redo the simulation already made ​​in the thesis of Mr. Maxime Moreau simulation software orcad pspice 9.2 lite: the simulation scheme in page 19 is a series chopper powered by a DC voltage source to tavers a LISN.
I can extract the curves in the time domain but my problem lies with the curves in the frequency domain (Ie and Ip) on page 21 and (Ve and VT) on page 22 I can not understand the transition between simulation in the time domain and the frequency domain what it does to enter the frequency.
I so need help because it is very close to my thesis topic and it will help me very much.
thank you for all.

File size:
3.1 MB
Views:
81
2. shteii01 AAC Fanatic!

Feb 19, 2010
4,461
706
I think you are looking at it wrong.

On page 21, Figure 8a is time domain, and it contains ie and ip, note low case letters. Figure 8b is frequency domain, it contains Ie and Ip, note upper case letters. When you are looking at the two plots, you can not compare them directly because they represent very different things, this difference is denoted by the use of lower case and upper case letters.

The way to go from Plot a to Plot b is to take the equation that represents the line in Plot a and do some math on it. Let me show a simple example:
Let say you have a signal in time domain: y(t)=2cos(2pi100t)+3cos(2pi200t)+5.4cos(2pi320t)
What does this thing will look like in frequency domain?
Well, I don't know, but! Look at the parts after the pi: 100, 200, 320.
What are these three parts? They are frequencies.
So, when you do frequency domain plot of y(t) (Y(f)), you will have a component (spike) at 100 Hz, 200 Hz and 320 Hz.
These spikes would not show on time domain plot because we are not looking at frequencies in time domain plots.

Going back to the Figure 8 on page 21. Plot a tells you the behavior of the current, like that spike in red that goes just past 20 ampere, it happens 100.06 microseconds after the device turned on, there is a smaller second spike a little later, but after that the current slowly settles down, until (I hope) it becomes just a flat line. Plot b tells you at what frequency that spike occurs. If this was an audio system, you would hear a very short burst of noise when you turn the audio system on, that is Plot a. But if you wander at what frequency that noise happened, you would have to look at Plot b.

3. t_n_k AAC Fanatic!

Mar 6, 2009
5,448
790
Yes - I agree shteii01 is pointing to the correct interpretation. One would normally apply [say] a Fast Fourier Transform (FFT) algorithm to the time domain data to obtain the corresponding frequency domain data. Some anti-aliasing filtering may be applied to the raw time based data prior to application of the FFT algorithm. It's a routine signal processing task. My French is poor, so I'm not sure if the author elaborates what analysis was carried out in preparing the graphs.

4. nesrine Thread Starter New Member

Oct 4, 2013
8
0
i'm so thankful

5. nesrine Thread Starter New Member

Oct 4, 2013
8
0
good morning, please can someone show me how to make advanced markers displayed

6. LvW Well-Known Member

Jun 13, 2013
769
104
In the "schematics" environment there is a menu point "markers".
Here you can select "mark advanced".

7. nesrine Thread Starter New Member

Oct 4, 2013
8
0
excuse i didn't find it in schematics but in capture=pspice=markers=advanced= i find them but all not displayed what to do to make them shown