Evaluation of 3D Printed Cobalt Iron Cores for Filter Inductors

This article presents a timely report on 3D printed cobalt iron (CoFe) soft magnetic cores enabled by the latest advances of additive manufacturing technologies. The feasibility of 3D printing CoFe magnetic cores is demonstrated in a current-ripple-filtering line inductor for power electronics applications. A like-for-like comparison is conducted between the 3D printed solid core and a commercial laminated core with the identical outer geometries to benchmark the former. Performance of the cores is evaluated based on assembled inductors regarding two key high-frequency characteristics, the inductance and the core losses. The results show that the effective permeability of the 3D printed core reduces rapidly with the increase of frequency, due to the low effective resistivity and consequently prominent eddy currents. When the functional equivalent is achieved, i.e., the same inductance for filtering switching-frequency current ripples, the inductor with 3D printed CoFe cores shows five times larger core losses compared with the commercial laminated core.