Reduction of Power Losses in the Tape-Wound FeNiCuNbSiB Nanocrystalline Cores Using Interlaminar Insulation

An effect of interlaminar insulation on the dynamic magnetic properties of the tape-wound FeNiCuNbSiB-type nanocrystalline cores was investigated. This insulation was prepared by three methods. After thermomagnetic treatment of toroidal cores selected types of suitably chosen varnishes were applied onto the core edges so as to enable their in-depth penetration thus forming the desired insulation. In the final stage of thermomagnetic treatment, conducted initially under protective atmosphere of argon, oxygen was introduced to the process to enable formation of interlaminar oxide layer. Finally, the ribbon was coated with SiO layer prior to its winding into the core. Then, dynamic magnetic properties of the cores were measured within a frequency range from 50 Hz to 100 kHz. It was found that the use of a modified acrylic-type resin resulted in the decrease of the Fe_73.8Ni₅Cu_0.6Nb_2.6Si₉B₉ core losses at higher frequencies. In the cores with an oxide insulation, reduction of power losses was observed at lower frequencies. The use of interlaminar SiO insulation resulted in considerable reduction of core losses above the frequency of 5 kHz. The results of this paper can be practically applied in the production of nanocrystalline cores for power electronic equipment.