Software package to plot SMPS Bode plots

[treez]

Hello

I am working on stability of SMPS’s.

I am currently getting the Bode plots of the SMPS transfer function in a very time consuming way by manipulating the complex numbers “by hand” in Excel.

This is prone to typing errors.

I would like to find a cheap mathematical software package, which will allow me to input the expression for the transfer function (a quotient containing complex numbers) and get the bode plots shown on the screen.

That is, input something such as…………

A = [(1+j2f) (5.3-j)] / [ (6.2+j 2f) (4.2-j) j ]

And get a graph of………

20 * log (magnitude of A) versus LOG(“f”)

And a graph of…………

(Phase of A) versus LOG (“f”)
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Does any reader know of a (cheap) package that will do this?

 

[MacGyverS2000]

What's wrong with MatLab? Under $1k and eats complex number and phase graphs for lunch.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Noway2]

If that is too much for your buget, take a look at either Octave or SciLab. Octave is more Matlab compatible, but Scilab is more refined. One advantage to scilab is that there is also a tool called Scicos, and now Scicoslab, which allow you to model block diagrams.

Either of these tools will easilly provide you with a bode plot of your system. You can simply define the transfer function and tell it to plot. You can input the terms as a combined equation, as a numerator/denominator, as a polynomial, or as poles and zeros as you shown in your post.

If you want to simulate an electrical circuit, then take a look at LtSpice.

 

[GonzaloEE]

MathCAD 13

 

[ScottyUK]

I have some notes somewhere on Bode and Nyquist using Excel. And Excel can handle complex numbers, even if the syntax is clunky.

Googling Bode Nyquist Excel yielded

http://www.chem.mtu.edu/~tbco/cm416/freqexcel.html.

Any use?


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If we learn from our mistakes I'm getting a great education!

 

[GonzaloEE]

Once your s/w let you split complex numbers into Real/Imaginary part, the rest is just some algebra and you're done.

Regards,