Common Mode Noise Reduction with Balance Technique Considering Soft Saturation Characteristics

Balance techniques have been widely utilized to reduce common-mode (CM) noise. Powder cores, however, introduced soft saturation characteristics which disrupt balance conditions. This is because the leakage flux increases at heavy loads, resulting in decrease of coupling coefficient. In this study, the effect of the soft saturation characteristics of powder cores on the balance condition is investigated. Additionally, a winding structure minimizing the leakage flux by using foil winding is proposed. The proposed structure achieves a high coupling coefficient regardless of load conditions, confirmed by static magnetic field simulations. The CM noises of the conventional and proposed winding structures are compared in various load conditions from 0.5 kW to 4 kW and verified the effectiveness of the proposed structure.