Calculation of Power Losses in Litz Wire Systems by Coupling FEM and PEEC Method

The frequency-dependent resistance of inductive components with high-frequency litz wires is essential for the design of power electronic systems. A novel simulation approach is demonstrated, which combines the specific benefits of two numerical methods: The magnetic field distribution is calculated by standard finite-element method tools for complex 3-D geometries based on a solid conductor. The resulting magnetic field on cut sections of the conductor is used as boundary condition for the partial element equivalent circuit method. Based on the coupling of these methods, power losses on litz wire level have been calculated taking different bundle structures and pitch lengths into account. The work flow has been automatized and enables simulations of litz wire systems with hundreds of strands. For different simulation setups, the simulations have been verified by comparison to measurements up to 500 kHz. The average deviation is less than 5% in the relevant frequency range.