Design of a Novel Torque Tube for a Direct-Drive Superconducting Wind Generator

Direct-drive superconducting (DDSC) generators are promising in wind power due to their light weight, compact size, and high efficiency. Torque tube is one of the most important part in a DDSC generator. It should be capable of maintaining the airgap length of the generator and transferring the extremely large electromagnetic (EM) torque from low rotating speed. Furthermore, the torque tube should have a low conduction heat leakage to decrease the heat load on the cryogenic system. The cooling cost, which accounts for a large proportion of the maintenance cost, would then be reduced. This paper proposes a new torque tube structure for a 12 MW low temperature superconducting direct-drive wind generator. Thermal analysis is done to estimate the heat leakage of the torque tube. Thermal-structural coupling analysis is then carried out to evaluate the mechanical performance of the torque tube. The three-dimensional (3-D) finite-element method is used in the analysis. Reliability of the bolts in the torque tube is also verified.