Development of a Superconducting Machine With Stacks of Second Generation HTS Tapes

In this paper, we investigate a topology of superconducting electric machine, which uses stacks of second-generation (2G) superconducting tapes. These stacks have been used as an alternative to replace bulks in trapped field superconducting machines. In this context, we built prototypes of superconducting machines with 2G tapes spirally disposed on the rotor. These prototypes were tested in liquid nitrogen bath at 77 K for operation in two regimes: synchronous and asynchronous. The operation mode is according to the load torque. To perform the torque tests under these operating conditions, a measurement system was also built. Quasi-static torque, locked rotor torque with stator frequencies up to 60 Hz, and dynamic torque up to 1200 rpm were measured. The prototype with 2G high temperature superconductor (HTS) stacks presented a torque, very close to nominal value of this machine with permanent magnets in the rotor. Promising results have been found showing that 2G HTS may be an alternative to superconducting bulks.