Learning Forum

[Travis Huang]

Hello all,

Recently I am using Q3D to simulate planar transformer. I have an EE core made of ferrite. Since I only want to simulate the winding loss, I set the bulk conductivity of ferrite material to be 0 Siemens/m.

However, when I use AC R/L Fields/Mag_SurfaceJac to check the current distribution, I can still observe considerable amount of current in the ferrite core. This is strange because its conductivity is 0. Can anyone explain this phenomenon?

[Travis Huang]

We guess that the current in ferrite core is not conduction current, but displacement current. Displacement current reflects the time-varying electric field in the core, which has nothing to do with the conductivity. We try to see the difference in the current in the core by changing the permittivity of core material. Unfortunately, we still can not observe the difference even though we have increased the relative permittivity to 1000.

[Travis Huang]

Unfortunately, even if we change the permittivity of core material or the frequency, the current observed in the core surface would not change. Still, we could not prove that the current in the core surface is displacement current. It is very likely that it is not displacement current.