US Patent 11303194 Wound field synchronous machine

A cryogen-free partially-superconducting electric machine of the wound field synchronous type includes a room temperature semi-slotless stator, a superconducting motor rotor, a gap between the rotor and stator, a torque tube which isolates the cryogenic superconducting motor rotor from a central shaft, bearings, an acoustic cryocooler integrated within the motor rotor and torque tube, a heat exchange, a rotary transformer, a vacuum pump, a vacuum enclosure integrated with the stator, and an eddy current/thermal shield. The electric machine can act as a motor or a generator and produces a high specific power and efficiency.