The SupraGenSys project investigated the design, optimisation and holistic assessment of fully superconducting generators for multi‑megawatt wind turbines. The core objective was to replace conventional copper windings in both stator and rotor with high‑temperature superconductor (HTS) conductors, thereby reducing copper losses, lowering generator weight and enabling larger rotor diameters without increasing tower mass. The study focused on direct‑drive ring generators, which operate at low rotational speeds and frequencies, making them especially suitable for HTS implementation.

A systematic design methodology was developed. Several base configurations were defined, varying stator and rotor winding types (tooth winding, distributed winding, air‑gap winding), cooling concepts (conduction, thermosiphon, lead cooling) and superconductor materials (HTS bandwire at 20–40 K, MgB₂ at 20 K, warm‑iron bandwire at 30–68 K). Numerical models were built in FEMAG‑DC to evaluate electromagnetic performance, AC losses and mechanical stresses. The results showed that HTS bandwire configurations can reduce AC losses by more than 50 % compared with conventional copper windings, while maintaining the required torque density. A 10 MW fully HTS generator concept was derived, featuring a 6.25 m stator diameter and a pole‑pair count that balances magnetic flux density and mechanical load. A 100 kW demonstrator was also designed to validate the concepts at a smaller scale.

Thermal analysis was performed using analytical calculations and CFD simulations. The simulations confirmed that the chosen cooling schemes keep the HTS conductors below their critical temperature under normal operation and during fault conditions. Mechanical studies, including finite‑element stress analysis, demonstrated that the rotor and stator structures can withstand the high centrifugal forces and magnetic forces without excessive deformation.

The project also examined the integration of power electronics operating at cryogenic temperatures. Literature reviews and experimental tests indicated that silicon‑based power devices exhibit improved efficiency and reduced size when cooled to 20–40 K. The study identified potential gains in overall system efficiency, power density and reliability, and established criteria for when cryogenic power electronics are advantageous.

Experimental work validated key components. An AC‑HTS coil was fabricated and characterised, confirming the predicted loss behaviour and mechanical robustness. A power‑electronics test rig was upgraded to operate at low temperatures, allowing measurement of switching losses and thermal performance of silicon devices under cryogenic conditions.

Collaboration was central to the project’s success. Fraunhofer Institute for Energy Efficiency (Fraunhofer IEE) led the design, simulation and experimental work. Siemens AG contributed industrial expertise in turbine design and manufacturing. Karlsruhe Institute of Technology (KIT) provided mechanical engineering support, while Krämer Energietechnik supplied power‑electronics knowledge and test facilities. The Federal Ministry for Economic Affairs and Climate Action funded the project, with the project sponsor Jülich offering project management and budgetary oversight. The partners coordinated across the full development cycle, from concept to prototype, ensuring that the technical results were grounded in industrial feasibility and that the project met its funding objectives.