Large-diameter Ironless Permanent Magnet Generator for Offshore Wind Power Application

This paper presents the research on direct-driven ironless permanent magnet generator with a diameter over 24 m that can be used in offshore wind power plants. Machines with ironless stator do not suffer from attraction forces between the rotor and the stator so a very low total weight can be achieved even with the large-diameter carrying structure. By using modularized active parts, manufacturing, transportation, assembly and repair of the large-diameter generator becomes possible. Several variants of turbine design and the corresponding ways to integrate the generator into the turbine are discussed. Several axial-flux and radial-flux machine variants are modeled with the help of the finite element method. Comparison of the different generators is carried out based on such criteria as active mass, material cost and efficiency.