Structure of Air-Core Power Inductor With High Energy Density and Low Copper Loss

In recent years, the development of power inductors with high inductance density and low loss has been required to realize high-power-density power supplies. The proposed inductor can be used in the high-power range where solenoid inductors are used and have higher inductance density than conventional inductors. The relationship between structural parameters and inductance is clarified based on the basic theoretical equation of inductance. Moreover, this article discussed the relationship between loss and structure due to skin and proximity effects using the electromagnetic field analysis. The results provide insights into the principles for the design of an air-core inductor with high energy density and low copper loss. A prototype test is conducted to prove the usefulness of the proposed inductor. As a result, the prototype inductor achieved an inductance density of $360 ~\mu \text{H}$ /kg at 500 kHz, approximately 23 times higher than conventional solenoid inductors.