transformer simulation with AC/DC, HEAT TRANSFER

Hi everyone,

I would like to simulate a three phase transformer in 3D with more module in the same time.
The aim of my model is seeing the effect of the magnetic field (eddy current, leakage flux) for the temperature.
First I simulated only the magnetic field, then only the heat transfer in solids, and these were working.
But when I tried to simulate the magnetic field and the heat transfer in solids physics in the same time it don't want to converge (In this case i used only air). So this is my first problem. Which solver configuration can you offer?

In general my model is an oil filled transformer, so it will be perfect with a fluid flow module. In this case does my model need the heat transfer module too or only the CFD module?

Thanks,
Anna