The minimization of magnetic stray fields from toroids with air gaps

The external magnetic stray field is investigated in gapped toroids with a rectangular cross section. An analytical method is used in which the field distribution is calculated by means of orthogonal expansion. Further, the influence of various parameters, such as winding position and air gap size, on the radiated magnetic field is discussed and, based on the results, basic rules are given that need to be followed when designing reduced stray field configurations.