Toroidal Nanocrystalline Powder Core With Trapezoidal Cross Section

This article introduces a toroidal nanocrystalline powder core with a trapezoidal cross section. The nonuniform magnetic flux distribution of toroidal cores with different cross-sectional geometries is discussed, the inductance equations are derived, and the geometrical optimization factor is given in order to retain the highest possible inductance value while minimizing material usage. A ten-turn coil is wound on the core, with the measured inductance values showing a good match with both finite element method (FEM) and mathematical calculation. The near-field electromagnetic interference (EMI) radiation in close proximity to the inductor is investigated by both FEM and experimental validation, and the toroidal core with a trapezoidal cross section has shown reduced EMI. By adopting a trapezoidal cross section for the toroidal core, a 30% reduction in material usage and lower EMI are achieved, albeit with a compromise of 14% in inductance.