Induction generators for direct-drive wind turbines

This paper considers the use of a squirrel cage induction generator for a direct-drive wind turbine. Advantages of this topology include a simple/rugged construction, and no need for permanent magnets. A major focus of this paper is the choice of an appropriate pole number. An iterative, analytical design process is employed to create generators of different pole numbers for comparison, with static 2-D finite element analysis used for verification. It is shown that increasing the pole number has the effects of reducing the required core material, reducing the power factor, increasing the leakage reactance, and increasing the efficiency.