3D modelling of the generator for OpenHydro's tidal energy systems

OpenHydro is developing open-centred submerged turbines for the extraction of energy from ocean tides. Power take-off is via a surface-mounted, radial-flux, permanent-magnet generator mounted to the rim of the turbine blades. A number of full-scale devices have been deployed globally, up to 2 MW and 16 m diameter. The aspect ratio of the machines mean that end effects are likely to be significant, and hence 3D modelling is required to fully capture them. In this presentation, alternative methods for modelling the existing machine design are discussed and compared. It is demonstrated that, although a full-scale detailed FEA approach yields the best results, simplified FEA and even analytical approximations are best for the purpose of designing the machines.