INDUGIE Research Project

How the INDUGIE research project pushes the boundaries of inductive energy transfer at 2 MHz through precise strand design and PCB embedding.

Research Focus

As part of the collaborative project INDUGIE (High-frequency inductive energy transfer for autonomous electric drives), an advanced inductive wireless power transfer system was developed. The research focused on optimizing energy transfer at a high operating frequency of 2 MHz to achieve maximum efficiency within a minimal footprint.

The Challenge

At 2 MHz, both the skin and proximity effects cause massive increases in resistance within conventional conductors. The primary challenge was to identify a litz wire construction where the single-strand diameter is perfectly matched to the minimal skin depth of approximately 47 µm, thereby minimizing current displacement.

Our Solution Strategy

Using analytical modeling and real-world AC resistance measurements, various configurations were evaluated. The final selection was an ultra-fine HF litz wire comprising 360 single strands, each with a diameter of 0.04 mm. This dimensioning optimally addresses the skin effect. A key innovation was the subsequent integration of the transmitter coil directly into a cavity of the printed circuit board (PCB).

Result

Compared to a solid wire of the identical cross-section, copper losses were reduced by an impressive 32%. The successful PCB embedding demonstrates that modern HF litz wires, combined with innovative packaging and interconnection technology, are essential for developing highly efficient, compact energy transfer systems.