RLC resonnance solving

[athurin]

Hi,

Sorry if it seems to be a beginner's question, but I am trying to get Mathcad to calculate an RLC resonnance response.

The circuit I am considering is based on a L in series with R//C, but I am adding the series resistance of the inductance and of the cap, so it looks like :

Rl - L - (R // (Rc - C))

I tried to inspire myself from a simple RLC series resonnance solving file I found on this forum, but it doesn't work and I don't understand the error.

I tried to do it initially with numerical values for all the components, but ideally, I would like to get it in pure symbolics, if it is possible.

If someone knows how I can get this to work, that would be extremely useful.

Thank you very much

Adrien

[Werner_E · Accepted solution]

You have to solve for all four functions in play (I,Ic,V,Vc) or alternateviley setup your system with only the two functions you want to see. Simply add the two missing functions to the vector in odesolev and it works.

[athurin]

It works ! Thank you very much !

Is it possible to solve it symbolically, or is it only possible with numerical value ? I have solved it by hand with only Rl as only resistance, but it gets to much for me with all of them.

[Werner_E]

Unfortunately Mathcad can't solve ODEs symbolically. It may help you with the intermediate steps like doing symblic integrations if you do it "´by hand" or you may try to set it up using Laplace transform, which is available in Mathcads symbolic. But there is no "out of the box / push button" solution available in Mathcad.

[athurin]

I will try with Laplace transform.

Thank you very much.

[Werner_E]

You might be interested in this sheet: http://communities.ptc.com/docs/DOC-3682