# Discussion Forum

## Coil inductance and resistance vs frequency

 Topics: AC/DC Module, 4.1, Transformers, 4.3a
RSS feed   |   Turn on email notifications   |   12 Replies   Last post: January 21, 2013 11:29pm UTC

Pierre Jaquier

November 12, 2009 4:36pm UTC

Coil inductance and resistance vs frequency

Hi,

With the ACDC module of Comsol, I would like to calculate the standard parameters of air coil by taking into account frequency effect (inductance, resistance and capacitance of the coil)
I would like to run this Comsol model under Matlab in order to make a parametrical optimization. This mean that the solve procedure of the model should not be too long !

I already read the model library of ACDC module, but still didn't find the best solution for my model.

Lumped parameters can be used to do that. But as I understand, I need to use a 3D model and apply potiential (GND, port) to the coil terminal (the "power inductor" model of the model library or the "planar transformer" used such Lumped parameters to calculate the Impedance of the coil.
I tried to modelize a 1 layer 30 turns coils in 3D by using the helix3 command line in Matlab (remember that the geometrical parameters of the coil must be tunable under matlab for a future optimization procedure), then apply potential (GND and port) to the coil terminal as in power inductor example. Unfortunately the solver doesn't converge. I'm a newbie in Comsol so I don't know which parameters to modify in the solver (I keep the same as in the power inductor example).
BUT this way to do seems to take a lot of time to solve.

For sure, it is also possible to make an approximation by using a one "area-equivalent" conductor in a 2D axis-symetrical environnement by definiing a current density in the conductor and then using a Psi/I expression to calculate the inductance of the coil (I also have to calculate mutual inductance between 2 coils). I also to that in the static-magnetic mode... but this doesn't take into account frequency effect.

which is the best way to compute inductance or mutual inductance simulation in 2D ?

I also wanted to take into account the resistance increase functions of the frequency, this can be done eventually by modeling 1 conductor per layer and then multiplying the resistance by the number of turns per layer in the coil...

Simulation of the whole 3D coil seems to be a crazy way, isnt'it ?

Thanks for the help!

Ivar Kjelberg

November 14, 2009 9:31am UTC in response to Pierre Jaquier

Re: Coil inductance and resistance vs frequency

Hi

As a first hint, from my experience, one always want to start directly in 3D as that is in our view the "right solution. But, as you, when I try, I get mostly stuck. So I can only highly recommend: start simpler in 2D, even axisymmetric in ACDC becase its works mostly very well (in structural often the boundary conditions violate the axisymmetry case even if the gometry is nicely axisymmetric = somewhat more complex cases).

Then build up your model in steps, one phenomena at the time, check them out carefully, are they correct ? then finally go to the 3D model (because you often find a few unexpected effects there too ;)

Anyhow 2D cases soves correctly in a fraction of the time of a 3D case, so its easy and quick to restart and check out all parameters

I do ineed mostly use N*I for the Amp*turn case, but for HF effects and skin effects, when you might well want to go to the details of each turn. There are a few examples in the documentation, slightly tedious for 30 turns though, I highly recommend to start by going through these examples in detail, it's not lost time, even if YOUR problem does not seem to be resolved this way, but you gain afterwards, knowing directly what and how to start.

Bonne chances pour la suite et tenez nous au "courant"
Ivar

Sara Feb.

October 31, 2010 11:51am UTC in response to Ivar Kjelberg

Re: Coil inductance and resistance vs frequency

Hello!

I would like to calculate the inductance, resistance and capacitance of a coil in 3D AC/DC module/Electromagnetic. I applyed an AC current to coil, solved it using parametric solver for freq, and plotted V(volt)/I(Ampere), but the frequency response seems wrong! There is not any resonance frequnecy even at 1e15 Hz!

what's wrong with my simulation?

Thank you for any help

Ivar Kjelberg

October 31, 2010 3:09pm UTC in response to Sara Feb.

Re: Coil inductance and resistance vs frequency

Hi

could it be that you are missing the "complex" value of the response, see the doc, you need to use correctlly the real(), imag() and abs() operators to get the impedance out. Often a lumped port approach is easier to use, again try out the examples in the doc first ;)

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Good luck
Ivar

November 5, 2010 11:14am UTC in response to Pierre Jaquier

Re: Coil inductance and resistance vs frequency

I hve also tried to solve same type of pb. Kindly, tell me the correct name of that document, so I will easily find.

Ivar Kjelberg

November 5, 2010 1:03pm UTC in response to Fovad Ali Khan

Re: Coil inductance and resistance vs frequency

Hi

for me the "doc" are many the ACDC manual of COMSOL and the umerous examples (the theory of the 3.5a models still remain valid for v4, OK the way to click around on thegui have changed)

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Good luck
Ivar

Haochen Cui

November 11, 2010 8:56pm UTC in response to Pierre Jaquier

Re: Coil inductance and resistance vs frequency

Does anyone know how to do the coil inductance and resistance vs Frequency Simulation in 3D model?

Thank you

Ivar Kjelberg

November 12, 2010 7:52am UTC in response to Haochen Cui

Re: Coil inductance and resistance vs frequency

Hi

I believe you must use MEF then, and MEF is giving me headaches these days (4.1) to get it to converge, in 3D with velocity, eddy currents etc

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Good luck
Ivar

Mustafa Kavasoglu

December 16, 2010 5:57pm UTC in response to Pierre Jaquier

Re: Coil inductance and resistance vs frequency

I have exactly the same problem

I am trying the model thing and there is no way to get any kind of convergance for me

Did you find any kind of solution ?

Ivar Kjelberg

December 16, 2010 6:43pm UTC in response to Mustafa Kavasoglu

Re: Coil inductance and resistance vs frequency

Hi

perhaps there are some clues to catch from the ACDC COMSOL webinar, set up in 5 min (at 20h-GMT+1, 2PM-ET). See the main COMSOL web site site "events free webinars"

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Good luck
Ivar

Sofia

April 15, 2012 8:42am UTC in response to Pierre Jaquier

Re: Coil inductance and resistance vs frequency

Hi,

I have some problems with my Comsol model.
Could anyone tell me where can I find the tutorial model "planar transformer"?

Wagner Gurgel do Amaral Filho

January 17, 2013 10:21am UTC in response to Sofia

Re: Coil inductance and resistance vs frequency

Hello Sofia,

Did you resolve your problens with the Transformers model?

Wagner.

Induja S

January 21, 2013 11:29pm UTC in response to Wagner Gurgel do Amaral Filho

Re: Coil inductance and resistance vs frequency

Hi Pierre,
did you find a solution? I'm also working on a similar problem.