Time variable fields involving nonlinear materials.

Dear Coleagues,

I have been searching for time dependent solutions using a multi-turn coil and a nonlinear core. The geometry of the problem is a simple “E” structure and it can be shown in the attached file. I tried to put "100*sin(2*pi*t)" in the current excitacion, for example, on the multi-turn coil, but i didn't get success on the solution (the solution didn't converge in this case). Is it correct in this kind of problem? Or i need to create an electrical circuits physics for the excitacion of the coil?
I saw an example in comsol.com, and they just put "100*sin(2*pi*t)" and got success without the electrical circuits physics. I'm using the Magnectic Fields Physics.

Thanks,
Kevin