Copper Pipes as Medium Frequency Transformer Windings

Owing to increasing power demand, new technologies, such as solid-state transformers, are progressively researched and improved. Thereby, galvanic isolation and voltage adaptation are achieved by medium frequency transformers. To reach high power density designs, transformer windings can be realized by means of copper pipes, allowing for efficient liquid cooling. This paper provides insight to many relevant aspects for the use of hollow copper conductors as windings. This includes electrical and thermal modeling, as well as considerations regarding mechanical implementations. Additionally, the winding concept is investigated based on a 1 MW medium frequency transformer prototype.