ALUPOWER Research Project

How oxide-insulated aluminum litz wires can achieve a fourfold increase in power density in inverters – with precise consideration of thermal anisotropy.

Research Focus

The project investigated innovative approaches to developing power inductors with significantly higher power densities for modern inverters. A specific focus was placed on oxide-insulated aluminum litz wires and their respective heat dissipation mechanisms. The ultimate goal was to develop components that exhibit four times the power density of previous standard solutions.

The Challenge

The primary challenge lay in understanding the external proximity effect and the anisotropic behavior of aluminum litz wires within a magnetic field. It was essential to clarify how permeability and thermal conductivity depend on the orientation of the individual strands, as these properties vary greatly between longitudinal and transverse directions.

Our Solution Strategy

Precise mathematical and simulation models were developed to calculate permeability and heat conduction in different directions. A complex permeability tensor now enables highly accurate power loss calculations. Additionally, approximate formulas for heat conduction were established, demonstrating that thermal conductivity along the strands is significantly higher than in the transverse direction.

Result

The developed models allow engineers to specifically design the orientation of the strands for optimal heat dissipation. Through this deeper understanding of physical processes, significant improvements in power density were achieved. These results serve as a sound decision-making basis for selecting the optimal litz wire for energy-efficient electronic systems.