Exploring Fully Superconducting Air-Core Machine Topology for Off-Shore Wind Turbine Applications

This paper presents an electromagnetic (EM) analysis and feasibility design study of a 10 MW air-core fully superconducting (SC) generator for off-shore wind turbine applications. This machine topology uses MgB₂ SC wires in both armature and field windings to reduce the generator cost. To reduce the weight of the machine, stator iron core in the traditional SC machine design is replaced with shield coils to contain the flux inside the machine. This air-core design allows the air-gap flux density to be increased without saturation to achieve an increased power density in machine design. Further, eliminating the iron core also eliminates the core losses. This is an attractive feature for off-shore wind turbine applications where machine weight can be reduced with increased efficiency. Preliminary EM studies are performed on a 10 MW, 10 r/min fully SC air-core machine design and its associated ac losses are evaluated. Design specification of the machine is provided with the armature, field, and shield winding parameter details. Finite element (FE) analysis is used to evaluate the flux density and torque profile of the machine. To reduce the ac losses in the armature coils, magnetic flux density at the armature winding is set to be 2 T. The preliminary results show this fully SC air-core generators show better performance in ac losses compared to the similar fully SC MW wind turbine designs.