3D Printed Air Core Inductors for High Frequency Power Converters

3D Printed Air Core Inductors for High Frequency Power Converters This paper presents the design, modeling and characterization of 3D printed air core inductors for high frequency power electronics circuits. The use of 3D modeling techniques to make passive components extends the design flexibility and addresses some of the fabrication limitations of traditional processes. Recent work [1]–[9] has demonstrated the feasibility of incorporating air core inductors in high frequency (>10 MHz) switching power converters. These implementations have used discrete wire wound solenoids and toroids, and planar components that use Printed Circuit Board (PCB) traces or microfabrication techniques to make air core inductors. However, realizations of such components have limitations in performance and applicability including open paths conducive to the flow of leakage fields, and difficulties in achieving optimal cross-section to minimize loss. Along with the current effort of involving 3D printing technology to make inductors [10], [11], we propose the use of 3D printing and casting/plating techniques as a simple and accessible alternative that adds flexibility and functionality to air core inductor design for high frequency power conversion at moderate to high power (e.g. tens to thousands of watts) and high voltage (greater than 100 V) levels. In this paper, we present several examples of air core inductors realized using 3D printing and casting/plating techniques to give an idea of the geometries that are possible to design. Moreover, we show that some of these designs can lead to improved electrical performance. The paper also describes the tools used by the authors to design, fabricate and characterize the electromagnetic performance of the air core inductors. The software used to generate the 3D scaffolds for the inductors are freely available and easily accessible. Readers are encouraged to explore more possibilities of geometries that can lead to better performance with the ease of manufacturing. As progress in additive manufac- uring continues, we envision 3D printing of a complete scaffold structure that after plating (or casting) will contain all resonant passive components of an RF switching converter. Toward this goal, we present a 70 W prototype 27.12 MHz resonant inverter that incorporates some of the 3D printed components developed for this work.