Manufacturing and testing of robotic-wound segmented non-planar REBCO coil for distributed windings in superconducting rotating machines

Distributed windings offer significant electromagnetic advantages for fully superconducting rotating machines, especially higher power density. Non-planar REBCO coils are required for the realization of it but remain challenging to design and fabricate due to the limited strain tolerance of the REBCO layer. In this work, we extend a previously proposed single-turn segmented non-planar coil design to a 20-turn configuration, deriving the geometric parameters of each turn analytically to account for the finite tape thickness. Based on the parameterized coil geometry, we develop a robotic winding procedure using a discrete representation of the tool trajectory and orientation to enable controlled and repeatable tape placement. We validate the approach by manufacturing a no-insulation REBCO test coil and characterizing its electromagnetic performance at 77 K. A critical current of 70 A is measured, in good agreement with the modified load-line estimate of 74.5 A, and the measured central magnetic flux density deviates by less than 1 % from the Biot–Savart calculation.