Multi-stage controlled frequency generator for direct-drive wind power

A multi-sage controlled frequency generator is described that has a low size, weight and cost. The new generator requires an electronic controller that requires only 25% of the total generated power (100%) when the generator shaft speed varies by +/-25% around its synchronous speed. The shaft driving the generator in the direct-drive controlled frequency generator may be moved at a variable speed. The output frequency of the generator may be controlled by electrically controlling the frequency of the first stator stage and by selecting the control frequency, the number of poles, and the number of stages, such that the output of the last stage will be maintained constant at the desired grid frequency.