Additive Manufacturing of Hetero-Magnetic Coupled Inductors

Coupled inductors are used in power electronics to improve transient response and reduce component size. To further increase inductance density and reduce fringing fields, a combination of different magnetic materials was introduced to create a hetero-magnetic coupled inductor (HMCI) core. To simplify and speedup the prototyping of HMCI designs, in this study a paste-extrusion additive manufacturing platform was used to co-process a custom-developed magnetic and conductive feedstock. First, ferrite plates of each having a winding were co-printed and co-sintered. Then, the HMCI was assembled by bonding together the ferrite + winding plates using a low-temperature curable magnetic paste. The finished HMCI was characterized by measuring its dc winding resistances, leakage inductance, and coupling coefficient. The coupling coefficient of the HMCI was easily adjustable to meet various requirements for high-frequency interleaved multiphase buck converters. This work demonstrates the feasibility of applying an additive manufacturing process for rapid prototyping of an unconventional power magnetic component having an inhomogeneous magnetic core.