Theoretical analysis of the electrical and magnetic field distributions in a toroidal core with circular cross section

With the rapid development of high-frequency magnetic components, it is important to know the distributions of the electrical and magnetic fields in the ferrimagnetic cores. In this paper, an improved model for analyzing the distributions of electrical and magnetic fields in a toroidal core is given. It supplies the basis for the theoretical analysis of the iron loss in the magnetic cores, which is helpful in evaluating experimental results. On the basis of calculated results, we find that the magnetic field produced by the eddy current and displacement current due to the electrical field will shield the magnetic flux from the inner portion of the core cross section. This results in a flux skin effect analogous to the skin effect in the conductors of a winding. This phenomenon becomes more obvious when frequency increases.