Investigation of a six pole stator system using no-insulation 2nd generation high temperature superconductor for a 10 kW generator demonstrator

The enhanced thermal stability of no-insulation superconducting coils, due to the absent turn-to-turn insulation is demonstrated in several publications. With the self-protecting properties of these coils, the application of second generation high temperature superconductors in real energy applications can be simplified, regarding quench detection and protection. Furthermore, it enables a system design with superconducting coils operating closer to their critical current limitation compared to their insulated counterparts. The usage of superconducting materials, improving the power density in wind turbine generators is an ongoing research topic. As a result, the design and construction of a 10 kW laboratory demonstrator is intended. Therefore, six double pancake racetrack coils are manufactured with two different superconducting tape architectures and compared with respect to the critical current, turn-to-turn resistance and transient performance in liquid nitrogen at 77 K. The superconducting coils are joined together to a six-pole stator system for the installation in the 10 kW generator demonstrator. All 12 pancakes reach the expected critical current and show a similar transient response of the magnetic field in the individual measurements. However, the series-connected stator system has a much longer field delay than the individual pancakes, which cannot be sufficiently explained by the typical equivalent circuit diagram for no-insulation coils.