Winding Changeover Permanent-Magnet Generators for Renewable Energy Applications

This paper reports on the development of a permanent-magnet (PM) generator for a wind turbine which has variable winding connections for load matching. This means that the generator characteristics can be regulated via winding changeover so that the wind turbine can be controlled and maximum power point tacking (MPPT) followed; constant power output is possible without pitch control, complex algorithms or expensive power converters. The operating range (up to the cut-out point) can be extended into the high wind speed zone without drawing high power from the wind. This is achieved by maintaining the generator at the rated power when the wind speed increases beyond the rated point. Therefore, the specifications and costs of the generator and power electronics can be reduced. Experiments are conducted to demonstrate the effectiveness of the presented method.