A systemic design methodology of PM generators for fixed-pitch marine current turbines

This paper deals with the systemic design of permanent magnet (PM) generator associated with fixed-pitch turbine for tidal energy generation. The main problem with marine current turbines systems are the maintenance requirements of the drive-train. It is known that the blade pitch system increases the complexity, cost, and the maintenance requirements of the drive-train. In offshore energy generation, the maintenance should be minimized as much as possible. For that purpose direct-drive permanent-magnet machines associated with fixed-pitch marine turbines can be an attractive solution. The main challenge with fixed-pitch blades is to ensure the power limitation of the turbine at high speed without using variable pitch system. As solution, we propose a systemic design approach of the generator that takes into account the power limitation requirement. In addition, this methodology takes into account the tidal site energy potential, the turbine characteristic, the control strategy, the generator specifications and the power converter constraints. The obtained results show the feasibility of our approach to satisfy the control strategy requirements.