Comparison of Megawatt-Class Permanent Magnet Wind Turbine Generator Concepts

This paper begins by investigating which permanent magnet synchronous generators are being used in wind turbines today. These are broken into three classes based on the ratio of speed between the blades and the generator. Four example gearbox/generator combinations are demonstrated to explore the differences in cost, efficiency, and mass of each drivetrain solution, and these are in turn related to the cost of energy.

Based on the initial criteria of the study, the results favor geared concepts over direct-drive. The effects of varying several parameters are then explored in order to see what changes in availability, cost of structural mass, and OPEX would make the direct-drive concept favorable. It is concluded that if the cost of structural mass can be controlled, and availability/ OPEX advantages of around 2% and 40% respectively can be achieved, the cost of energy comparison may begin to favor directdrive wind turbines.