Representing Signals with Fourier Series in Multisim

Click For Summary
SUMMARY

Representing signals using Fourier series in Multisim is feasible by calculating the series sum externally and importing the data. The Fourier series for a sawtooth voltage with period T=2π can be approximated using a significant number of terms, ideally hundreds, to achieve accuracy. Users can generate the required data using MATLAB code and then save it to a text file for use in Multisim's PWL Voltage source. This method allows for the simulation of arbitrary periodic signals without manually connecting multiple AC voltage sources.

PREREQUISITES
  • Understanding of Fourier series and their mathematical representation
  • Familiarity with Multisim software and its PWL Voltage source feature
  • Basic knowledge of MATLAB programming for signal generation
  • Experience with data file handling in simulation tools
NEXT STEPS
  • Learn how to implement Fourier series in MATLAB for different waveforms
  • Explore the PWL Voltage source functionality in Multisim
  • Investigate the capabilities of Simulink for signal generation and simulation
  • Study advanced techniques for phase synchronization in signal processing
USEFUL FOR

Electrical engineers, signal processing professionals, and students interested in simulating complex waveforms using Multisim and MATLAB.

etf
Messages
179
Reaction score
2
Is it possible to represent some signal in terms of Fourier series in Multisim? For example, Fourier series of sawtooth voltage with period T=2pi is $$\sum_{n=1}^{\infty }\frac{2}{n}(-1)^{n+1}sin{(nt)}=2sin{(t)}-sin{(2t)}+\frac{2}{3}sin{(3t)}-\frac{1}{2}sin{(4t)}+...$$. These terms on right side of equation will be AC voltage sources connected in series. For good approximation of sawtooth waveform I should use few hundreds terms of series. It would be impossible to connect all these sources manually :) Is there any better way to do this?
 
Last edited:
Engineering news on Phys.org
It would be easier to simulate a circuit that generates a linear sawtooth than to correctly phase and sum all those Fourier terms.
 
  • Like
Likes 1 person
I know there is sawtooth generator in Multisim but I used sawtooth waveform only as example. I was wondering is it possible to simulate random periodic signal which can be represented through Fourier series.
 
How many different frequencies can Multisim generate at one time? One, or more?
How would you synchronise the phases to get the correct time domain signal?
 
I'm not sure I can give you right answer. If it's impossible in Multisim, can it be done in Simulink maybe? Here is my program in Matlab to plot Fourier series of sawtooth waveform:

clear
clc
t=linspace(0,2*pi,1000);
suma=0;
for n=1:10000
suma=suma+((2./n).*(-1).^(n+1)).*sin(n.*t);
end
plot(t,suma)
grid

Can I link it somehow with Simulink to generate this waveform?
 
Finally I solved it!
In order to simulate arbitrary periodic signal written in terms of Fourier series, it is necessary to calculate sum using my code for example, post #5 (Bigger n - better approximation.) . For every value of t we have appropriate value of "suma". Then we have to save our data in text file, time goes in first column and values for "suma" goes in second column. Then we load our text file in PWL Voltage in Multisim (Enter data points int table - Initialize from file...) and that's it
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
20
Views
2K
  • · Replies 7 ·
Replies
7
Views
734
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 33 ·
2
Replies
33
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K