Analytical model for the thermal resistance of windings consisting of solid or litz wire

In this paper a method to calculate the thermal resistance of windings is presented and validated by measurements. Two formulas have been developed for widely used wire types in power electronics being round and litz wire. With the presented approach it is possible to describe the thermal resistance of arbitrary wire arrangements. This analytical approach can either be used in fast forward designs of magnetic devices, respectively can also be integrated in automatized optimization procedures to improve the designs of magnetic components. The calculated results are showing good coincidence with the measured values.