Hetero-Magnetic Coupled Inductor (HMCI) for High Frequency Interleaved Multiphase DC/DC Converters

A coupled inductor made of different magnetic materials was designed and fabricated for high frequency interleaved multiphase DC/DC converters. The coupled inductor, herein termed hetero-magnetic coupled inductor or HMCI, has a sandwich structure with two ferrite plates and metal windings in between. The gap region between the ferrite plates is filled with a low temperature curable magnetic paste to increase inductance density and reduce fringing effect. The winding structure combined with a custom-formulated magnetic paste provides flexible negative coupling between the different phases. Compared to the a commercial two-phase coupled inductor, FEA simulation of our HMCI shows reductions in footprint by 50% and AC resistance by 36% while having a similar transient inductance. Experimental results on the fabricated inductor were in agreement with the simulated results.