High-Performance High-Power Inductor Design for High-Frequency Applications

Abstract

The performance and size of power electronic circuits are greatly impacted by magnetic components. This is especially true at Radio Frequencies (RF) of many MHz and above. In the High Frequency (HF, 3-30 MHz) range, coreless (or "air-core") inductors with a typical quality factor (Q) of 200-300 are conventionally used and are often the major contributor to the overall system’s loss and size. Even when they can achieve high Q, air-core inductors can induce electromagnetic interference (EMI) and eddy current loss in surrounding components, thus limiting system miniaturization. With the recent advancements in high-performance, high-frequency magnetic materials, there is interest in leveraging these magnetic materials at RF and replacing lossy air-core inductors with cored inductors to achieve an improved combination of size and loss. This thesis investigates high-power, high-frequency, high-Q cored inductors. This approach leverages high-frequency high-performance magnetic materials, core geometry, and quasi-distributed gaps to achieve a self-shielded inductor that emits less flux outside its physical volume and can be placed close to other circuit components without inducing EMI or eddy current loss. The performance and self-shielding characteristics of the proposed design procedure are experimentally verified for a 500 nH inductor (Q = 1150) designed to operate at 13.56MHz with a peak ac current of up to 80 Amps.