Numerical Study of Multi-Pole Generator With HTS Windings for Direct Drive Wind Turbines

Abstract

High-temperature superconducting (HTS) materials show potential advantages for direct drive wind turbine generators by enabling higher power density and lower volume. However, incorporating HTS windings necessitates a cryogenic system, which can increase costs, add weight and reduce overall generator efficiency. Consequently, investigating AC losses in HTS windings is crucial given the losses largely influence the cryogenic requirements. C-GEN is a permanent magnet synchronous generator conceived by the University of Edinburgh, which is characterised by modular structures for easy installation and maintenance. In this work, we have numerically investigated the AC losses in a MW-class direct drive air-cored HTS wind turbine generator, which has evolved from the C-GEN topology. Finite-element method (FEM) modelling was applied using COMSOL Multiphysics to build generator models equipped with HTS windings. Four designs were analysed in this study. Design-1 follows a conventional C-GEN structure and serves as a reference, utilising permanent magnets (PMs) for the rotor and air-cored copper windings for the stator. Designs-2 and 3 incorporate partial HTS structures. Design-2 replaces the stator copper coils with HTS windings, whereas Design-3 substitutes the rotor permanent magnets with closed magnetic loop (CML) HTS coil arrays. Design-4 features a fully HTS design, with both HTS rotor and stator windings. Dynamic analysis of the AC losses in HTS windings was conducted. The simulation results show that both partially and fully HTS designs provide higher power density compared with conventional design.