H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
H01F27/00—Details of transformers or inductances, in general
H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
H01F27/38—Auxiliary core members; Auxiliary coils or windings
H01F27/385—Auxiliary core members; Auxiliary coils or windings for reducing harmonics