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Ac current and dc current at the same time

Posted Feb 15, 2010, 11:46 a.m. EST Version 4.0 6 Replies

Lidia Campa
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Hello everybody!

I'm using the AC/DC Module, and I need to apply a DC current and an AC current at the same time in the model (3D). I've thought about it and I've found some options:

1. Time dependent model (transient analysis)
2. Multiphysics model (static / time harmonic analysis)

Which way should be the best one? Any other ideas are welcome.

Thanks in advance,
Lidia.
6 Replies Last Post Sep 28, 2011, 10:18 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 16, 2010, 1:56 a.m. EST
Hi

Interesting question you have there !

a) transient certainly will do, but if you want to do a frequency sweep you will solve forever, or close to
b) in modal or harmonic you will not see any DC by default, so you must add some formulas in the eqautions to get the DC component (from my understanding).

For me, this question is sufficiently generic and of generla importance that it could be sent to "support" and is worth an example in the model exchange (or even better in next version DOC ;)

Good luck
Ivar
Hi Interesting question you have there ! a) transient certainly will do, but if you want to do a frequency sweep you will solve forever, or close to b) in modal or harmonic you will not see any DC by default, so you must add some formulas in the eqautions to get the DC component (from my understanding). For me, this question is sufficiently generic and of generla importance that it could be sent to "support" and is worth an example in the model exchange (or even better in next version DOC ;) Good luck Ivar
Johan Gustafsson
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Posted: 1 decade ago Mar 22, 2010, 8:40 p.m. EDT
Hi Lidia,

I am having the same problem, and am just very interesting in knowing whether you have been making any progress on this issue?

Thanks,
Johan
Hi Lidia, I am having the same problem, and am just very interesting in knowing whether you have been making any progress on this issue? Thanks, Johan
Lidia Campa
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Posted: 1 decade ago Mar 23, 2010, 5:25 a.m. EDT
Hi Johan,

I'm afraid I'm still at the same point. I've had some advice from technical support, and though they were right on some points (thanks, Linus), it does not work :-(
I'm still trying.

Regards,
Lidia.
Hi Johan, I'm afraid I'm still at the same point. I've had some advice from technical support, and though they were right on some points (thanks, Linus), it does not work :-( I'm still trying. Regards, Lidia.
Jean-Francois Leon
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Posted: 1 decade ago Mar 23, 2010, 5:38 a.m. EDT
my 2cts on the question

IF the model is linear the best approach will be, in my opinion, to compute the steady state solution and the harmonyc solution separately and add them afterward [ superposition principle is your friend here] [ scripting or post processing depending upon your need]. This is relatively simple

If the model is non linear, I am afraid that the only way to go is to do a transient calculation.

Indeed there are some non linear physical coupling [ often related to material saturation] that CANNOT be grasped accurately otherwis.

Outside and independantly of of Comsol, this problem, along with the solution I am proposing is well known of people that are doing em simulation.

jf
my 2cts on the question IF the model is linear the best approach will be, in my opinion, to compute the steady state solution and the harmonyc solution separately and add them afterward [ superposition principle is your friend here] [ scripting or post processing depending upon your need]. This is relatively simple If the model is non linear, I am afraid that the only way to go is to do a transient calculation. Indeed there are some non linear physical coupling [ often related to material saturation] that CANNOT be grasped accurately otherwis. Outside and independantly of of Comsol, this problem, along with the solution I am proposing is well known of people that are doing em simulation. jf
Yang
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Posted: 1 decade ago Jul 14, 2011, 2:30 p.m. EDT
Dear Jean-Francois Leon

I have a problem to add AC current source in COMSOL,I am trying to study the heating problem resulted by electric current for some conductors. I choose heat transfer and electric current as my physics, and for electric current, I create a terminal,the problem is when I set the terminal as 'current' and type a sin function as value, it stoped during my simulation, when I change the terminal to 'voltage' and type the sin function it works right and get the result. And for DC current, it also work right. So how can I apply an AC current to my condutor. Thank you very much!

--
Yang
Dear Jean-Francois Leon I have a problem to add AC current source in COMSOL,I am trying to study the heating problem resulted by electric current for some conductors. I choose heat transfer and electric current as my physics, and for electric current, I create a terminal,the problem is when I set the terminal as 'current' and type a sin function as value, it stoped during my simulation, when I change the terminal to 'voltage' and type the sin function it works right and get the result. And for DC current, it also work right. So how can I apply an AC current to my condutor. Thank you very much! -- Yang
Bakkaoui Otmane
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Posted: 1 decade ago Sep 28, 2011, 10:18 p.m. EDT

I want to get 20,000 [A] Ac through a copper wire and apply a voltage 1500 [V] how I can do that

--
Yang


[QUOTE] I want to get 20,000 [A] Ac through a copper wire and apply a voltage 1500 [V] how I can do that -- Yang [/QUOTE]

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