An overview of power loss calculation methods for high-frequency litz wires

Accurate calculation of power losses has always been important for the design and optimization of magnetic components consisting of windings and magnetic cores, such as inductors and transformers. Focusing on windings, litz wire outperforms its counterparts in terms of eddy current losses, making it particularly suitable for high-frequency (HF) applications. The power loss calculation of litz wire is however challenging due to its complex structure of thin strands twisted in multiple levels. This article therefore aims to review various kinds of litz wire power loss calculation methods from analytical methods, numerical methods to coupling ones. In addition to, the principles and applications of each method, their inherent correlation and differences are also highlighted in this article. On this basis, a comprehensive review and comparison of different calculation methods of litz-wire power loss are provided. Finally, future challenges and directions are then summarized, whose ultimate goal is to calculate the power loss of litz wire accurately and efficiently.