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How do I load arbitrary current to the coil in comsol?

Posted Jul 14, 2013, 10:18 p.m. EDT Low-Frequency Electromagnetics Version 4.3b 7 Replies

Xin Wei
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In comsol, I want to give the coil arbitrary current defined by interpolation, but it always wrong. My specific approach is: (a) the global definition, using interpolation method defined excitation current, the function name is current3, as shown below:


(b) Defining the multi-turn coil, in the coil excitation, I chose the "current", then in the coil current, I would like to fill out the "current3", but the characters are displayed in yellow, is undefined variable, how is this going ? How can I put my defined arbitray current to the coil.

Look forward to your reply, thank you.

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7 Replies Last Post Jul 22, 2013, 1:58 a.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Jul 15, 2013, 2:52 a.m. EDT
A yellow expression mostly means a unit issue. Using current3[A] should do the trick.

Cheers
Edgar

--
Edgar J. Kaiser
www.emphys.com
A yellow expression mostly means a unit issue. Using current3[A] should do the trick. Cheers Edgar -- Edgar J. Kaiser http://www.emphys.com
Ralf Tschiesche
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Posted: 1 decade ago Jul 16, 2013, 2:21 a.m. EDT
Hi!
Since you are doing a transient simulation, you should use current3(t).
If you get unit error, you can write current3(t[1/s])[A].
Ralf
Hi! Since you are doing a transient simulation, you should use current3(t). If you get unit error, you can write current3(t[1/s])[A]. Ralf
Xin Wei
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Posted: 1 decade ago Jul 16, 2013, 5:33 a.m. EDT
Thank you very much. You are right. In comsol, the functions need units. I want to ask another question. when 0=<t<=1, the function is f(t). When 1=<t<=2, the function is g(t). If f(t) and g(t) are current functions, and they need to be loaded the excited coil. Should I write "f(t)&&g(t)" in coil current (Icoil)?
Thank you very much. You are right. In comsol, the functions need units. I want to ask another question. when 0=
Ralf Tschiesche
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Posted: 1 decade ago Jul 16, 2013, 6:51 a.m. EDT
Hi!
Try to define a third function like: h(t) = if(t<1, f(t), g(t))
Ralf
Hi! Try to define a third function like: h(t) = if(t
Xin Wei
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Posted: 1 decade ago Jul 17, 2013, 11:27 p.m. EDT
thank you. Your answer is right. I am doing eddy current detection. Do your research direction is the same one ? if it is, I hope that we can have more exchanges.
thank you. Your answer is right. I am doing eddy current detection. Do your research direction is the same one ? if it is, I hope that we can have more exchanges.
Xin Wei
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Posted: 1 decade ago Jul 19, 2013, 10:42 a.m. EDT
Excuse me. I want to ask another question. when 0=<t<=1, the function is f(t). When 1<t<=2, the function is g(t). When 2<t<=3, the function is h(t). How can the three functions be written one? If they are only f(t) and g(t), it can be written" if(t<1,f(t),g(t))". However, they are three, What shoud I do?

Best your wishes,

Xin Wei
Excuse me. I want to ask another question. when 0=
Sasa
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Posted: 1 decade ago Jul 22, 2013, 1:58 a.m. EDT
you can use Definitions -> functions -> piecewise
in argument type "t", for "start" and "end" use the start and end times and in "functions" use the expression you want for this part
you can use Definitions -> functions -> piecewise in argument type "t", for "start" and "end" use the start and end times and in "functions" use the expression you want for this part

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