Additive Manufacturing of Spiral Windings for a Pot-Core Constant-Flux Inductor

Constant-flux inductors (CFIs) are designed to have a more uniform flux density in the core for efficient use of the magnetic material and higher inductance density. However, these inductors generally require unique winding structures that are difficult to manufacture by conventional means. In this article, we applied a paste-extrusion 3-D printer to fabricate spiral windings with varying turn-by-turn widths to make a pot-core CFI. The printing speed and extrusion rate of the printer were optimized for a commercial silver paste to form the windings. The printed windings were sintered at 850 degrees C to get electrical conductivity approaching that of bulk silver. To form the magnetic core, a custom-made curable magnetic composite paste was used to encase the windings. After curing at 200 degrees C, the permeability of the magnetic material can reach over 35 with low core-loss density. A 1- $\mu \text{H}$ pot-core CFI of 5 mm $\times \,\,5$ mm $\times \,\,2$ mm was designed, fabricated, and characterized for its inductance and quality factor versus frequency and inductance versus dc current.