Magnetic material selection for EMI filters

EMI filters are widely used in power electronics converters to meet EMI standards. Since the common-mode inductor is often the largest single magnetic component, it must be optimized for size and cost. This paper investigates and presents datasheet and experimental comparisons of the magnetic materials aimed for a common-mode choke design. Several magnetic materials are considered: amorphous iron, nanocrystalline, ferrite and iron-nickel alloys. The material analysis compares and contrasts various effects, such as dimensional resonance, eddy current and core geometry. Finite element analysis is validated with experimental investigation of selected magnetic materials: ferrite and nanocrystalline.