We presented our research results at the 63rd National Heat Transfer Symposium, held at the Sapporo Convention Center in May 26–28, 2026.

Title: Evaluation of effective thermal conductivity in the radial direction of copper wire in motor windings using Litz wire

Presenter: Kazuya Asada (Alumnus of Science Tokyo) [Photo]

Co-authors: Masaki Yamanaka, Akira Minami (Komatsu), Akira Sumitani, and Takushi Saito (Science Tokyo)

As construction machinery becomes increasingly electrified and higher-powered, preventing overheating in the winding sections of electric motors has become an important challenge. Stranded wire structures, such as Litz wire, have the potential to improve thermal conductivity in the radial direction of copper conductors.

To investigate this possibility, we evaluated the effect of the three-dimensional structure of stranded wires on their effective thermal conductivity through numerical simulations and steady-state measurements, and developed a corresponding model.

We will continue to leverage these findings to support the electrification of construction machinery and contribute to the realization of a carbon-neutral society.