Heteromagnetic Swinging Inductor and Its Application for Power Factor Correction Converters

A variable inductor concept based on a magnetic structure consisting of composite of magnetic materials is introduced to meet the designed inductance function of current. A design of the inductor, termed heteromagnetic swinging inductor (HMSI), was fabricated using a toroid core with a gap that was filled by a custom-developed low-permeability magnetic powder + polymer material. Having the gap filled with the magnetic material allowed for greater flexibility in L–I design with added benefit of low fringe field. The analytical model of HMSI was derived and verified by simulation. And the step-by-step design of arbitrary L–I curve HMSI was posted. We applied this swinging inductor to a critical conduction mode boost power factor correction converter to reduce its switching frequency variation range. First, the required L–I curve of the HMSI needed for narrow range of switching frequency was calculated. Then, the HMSI core structure consisting of two magnetic materials was designed. Finally, a prototype of the HMSI was fabricated and tested. Experimental result showed that for a 110-Vrms input, the converter with the HMSI had a switching frequency variation factor, defined as Δ f / f _min , six times less than that of the converter using a linear inductor.