From what I can gather, this[1] is the research paper behind the described transformer, however it's not open access. However there is an available technical re

From what I can gather, this[1] is the research paper behind the described transformer, however it's not open access. However there is an available technical report here[2] with details. The design is based on an autotransformer[3], where the primary and secondary windings are connected in series, so effectively one coil. Section 2 in the technical report has details on how the flexible impedance windings. It's not as trivial as just adding some more windings, though perhaps in practice that's what it looks like. [1]: https://ieeexplore.ieee.org/document/9959916 https://ieeexplore.ieee.org/document/9959916 [2]: https://www.osti.gov/biblio/1527031 https://www.osti.gov/biblio/1527031 [3]: https://en.wikipedia.org/wiki/Autotransformer https://en.wikipedia.org/wiki/Autotransformer