A Low-Loss Inductor Structure and Design Guidelines for High-Frequency Applications

Operation in the HF regime (3-30 MHz) has shown potential for miniaturizing power electronics, but substantial challenges in the design of efficient miniaturized inductors at HF remain. Al these frequencies, losses due to skin and proximity effects arc difficult to reduce, and gaps needed to keep B fields low in the core add fringing field loss. We propose a low-loss inductor structure suitable for small, highly efficient inductors al HF and introduce step-by-step design guidelines for the geometry. An example similar to 15 mu H inductor designed using these guidelines achieved an experimental quality factor of 620 at 3 MHz and 2 A (peak) of ac current. We further demonstrate the low loss of the inductor in a high-current-swing power converter operated at 1-3 MHz; at 250 W, the inductor improved converter efficiency by 1.2 %, compared to a conventional inductor design. Thus, we show that the proposed inductor geometry and design guidelines can reduce losses and thereby help realize high frequency miniaturization of power electronics.