Toroidal Nanocrystalline Powder Core with Trapezoidal Cross Section

This digest proposes a toroidal nanocrystalline powder core with a trapezoidal cross section. The non-uniform magnetic flux density distribution of toroidal cores with different shapes of cross section is discussed, and inductance calculation equations are derived. The local electromagnetic interference (EMI) radiation at the inductor edge is investigated by simulation, and evident EMI reduction is observed in the toroidal core with a trapezoidal cross section. A 10-turn coil is wound on the cores, the measured inductance values show a good match with the simulation and calculation values. By adopting the trapezoidal cross section, a 30 % reduction of the material can be achieved in compromising 17 % inductance.