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## How to use external current density in racetrack coil

Hi all,

I need to analyze Electromagnetic force of racetrack coil with time dependent. To make this model, I use external current density. It has been confirmed that the external current density can be properly analyzed by time dependent analysis of circular coil. By using like those formula. Ix = I0-y/sqrt(x^2 + y^2), Iy = I0x/sqrt(x^2 + y^2), Iz=0

Now I try to analyze racetrack coil using external current density but I can't. I attached the file. Please give me your help and advice.

Thank you

4 Replies Last Post 12.7.2019 klo 3.38 UTC-4

Posted: 7 months ago
Updated: 7 months ago

Hi,

Why don't you try using the Solid Conductor using the Coil feature to model the solid piece and compute the Lorentz Force?

BR/Nirmal

Posted: 7 months ago
Updated: 7 months ago

Dear Nirmal,

Thank you for your reply. I want to use the Coil future but it cannot be used in time dependent.

Posted: 7 months ago
Updated: 7 months ago

Are you sure it is a single bulk conductor? If it is a bobbin (or if it is a bulk but you can assume constant resistivity as the pulse is slow... as could seem from your case given a fast look to parameters if it is not a multiturn) you can use multiturn. Transient 3D, current fed works out of the box for multiturn. This will include inductive effect averaged on the coil, but not local skin depth.

Have you already sent the model to support? If not, do it as we could help you as there is a couple of extra tricks for single turn, that you can use for current feeding time domain single turn conductor.

Cite a few. 1) add a voltage feed and se the voltage so to constrint current (in easy cases this is easy and works) 2) mix electric currents and magnetic fields as it is demoed in second part of https://www.comsol.com/model/rotating-machinery-3d-tutorial-10437 3) solution as https://www.comsol.com/model/geometry-optimization-of-a-3d-complex-shaped-coil-for-induction-heating-58051 where the feeding is put via a discontinuity on a "Magnetic Fields No Current" physics

Good luck

Cesare