Feasibility Study on a Water-cooled-type Cooling System Applied in a Large-scale Wind Turbine Generator

Recently, studies on the application of an AFPM (axial flux permanent magnet) generator to a large-scale, offshore, direct-drive wind turbine were performed. This is due to the AFPM simple mechanism and high efficiency, such as a torque effect per unit volume and power density. The high torque effect and current density, however, induce an overheating of the stator which can cause a critical problem during the production of electricity. Therefore, a proper cooling system is necessary. In this study, a newly developed water-cooled-type system for a 2.5 MW AFPM generator was proposed, and its cooling performance was compared with the conventional air-cooled-type system. This was done via an electro-magnetic and thermal fluid interaction analysis. Results obtained from the numerical analysis showed a similar cooling performance with both cooling systems. From a light-weight design point of view, the weight of the equipment required for the proposed water-cooled-type system can be reduced by two-folds compared to the conventional system.