Analytical Model for 3D Geometry, Radius and DC Resistance of Arbitrary Litz Wire

Litz wire is frequently used for reducing high frequency losses in modern power electronic systems. However, due to its complex twisting procedure, the 3D geometry and the important parameters of LW such as radius and DC resistance are difficult to obtain. Therefore, the radius and DC resistance of LWs are usually measured, which is not helpful in the magnetic and converter design. To eliminate the barrier caused by the complex twisting structure of LW, this paper provides an analytical model that not only mathematically describes the 3D geometry but also calculates the radius and the DC resistance of an arbitrary LW with less than 4% error proved by experiments. With the proposed model, a more flexible and accurate design and optimization for magnetics and converters can be achieved.