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Coil Current not matching Integrated Current

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So I'm doing a 2d axial model. I'm using a multi-turn coil and I am plotting the current in the coil. I've defined my voltage as a step function and that is the excitation.

Just noticed that when I plot a point graph (1d) and select mf.ICoil_1 I get one plot with a max at about .16 amps.
When I graph by doing a surface integration of mf.Jphi (selecting the domain of the coil ) I get a max at about 16 amps. Now these graphs have the same exact shape, just have amplitude scaling.

There is a difference in a factor of 100. Now there are 100 turns in my coil... but aren't these two graphs representing the same thing? Or does mf.ICoil_1 just calculate the current through each individual wire where as integration calculated the total current?

Thanks in advance for any input!

1 Reply Last Post 21.09.2013, 06:20 GMT-4

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Posted: 1 decade ago 21.09.2013, 06:20 GMT-4
Hi Andy,

the multi-turn coil domain is a simple model and only takes the resistance of the wire into account (no proximity and no skin-effects). To get a correct result (considering the resistance), you have to specify the cross section area a_coil of one single wire.
Because the model spreads the coil-threads evenly over the selected surface, the current flowing through the surface is the Number of turns multiplied by the current of one thread (= ampere turns). Thats exactly what you noticed.
If you like to look at the single threads of the coil, you have to use the single turn coil model (there is a check box to activate for multi-turn) or the RLC-coil model.

Regards Ueli
Hi Andy, the multi-turn coil domain is a simple model and only takes the resistance of the wire into account (no proximity and no skin-effects). To get a correct result (considering the resistance), you have to specify the cross section area a_coil of one single wire. Because the model spreads the coil-threads evenly over the selected surface, the current flowing through the surface is the Number of turns multiplied by the current of one thread (= ampere turns). Thats exactly what you noticed. If you like to look at the single threads of the coil, you have to use the single turn coil model (there is a check box to activate for multi-turn) or the RLC-coil model. Regards Ueli

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