Pseudo-Direct-Drive Electrical Machine for a Floating Marine Turbine

This article presents an investigation into the application of a magnetically geared pseudo-direct-drive (PDD) electrical machine in a floating tethered 6 kW, 100 r/min marine current turbine. The turbine is designed to harness the energy from ocean currents, in regions with relatively high-speed water flows at depths that are a long distance from the seabed and cannot be economically exploited by conventional fixed turbines. The marine current turbine is a robust, easy to service, and cost-effective solution for regions with variable or fixed sea depth of more than 60 m. This article presents the electromagnetic design and analysis of the PDD generator, and predicted performance such as efficiency, which is compared with dynamometer measurements on a prototype PDD generator. Furthermore, test results on a demonstrator marine turbine in a towing tank are also presented.