Influence of teeth materials and slot-pole combinations on electromagnetic forces and vibrations of a 12 MW superconducting direct-drive wind generator

Large-scale superconducting direct-drive (SCDD) generators have received lots of attention in recent years, featuring high torque density, efficiency and reliability. Due to the application of SC field windings, airgap flux density is large and often more than 2 Tesla (no more than 1 T in traditional machines), which could result in huge electromagnetic radial forces and vibrations in SCDD generators. Given SC coils are very sensitive to vibration, it is important to investigate effect factors of radial forces and vibrations in the large SCDD generators. Since vibration characteristics are determined by the airgap flux density, it is necessary to analyze the parameters that affect harmonics and magnitude of the airgap flux, such as slot-pole combinations and teeth materials. In this paper, a 12 MW high temperature superconductor (HTS) superconducting direct-drive wind generator with FSCWs is designed. The analytical model of the electromagnetic forces and the vibrations is provided. The influences of teeth materials and slot-pole combinations on electromagnetic forces and vibrations are discussed. The mechanical stress and deformations of the main structures of the SCDD generators are also investigated based on finite element analysis (FEA). In addition, an optimal winding configuration for large-scale superconducting wind generators considering electromagnetic force and vibration is presented.