Development of magnetic materials during the last decade has led to significant improvements in the ability of specialist steels to retain magnetic energy. As a result, the use of permanent magnet generators for megawatt scale wind turbines is no longer looking as costly and difficult as it once did. The magnetic energy per unit volume that the latest steels can retain is 50% higher than it was 20 years ago. ABB is now marketing permanent magnet generators for wind turbine applications with ratings up to 3.6 MW. Efficiency is claimed to be over 98% at full load, and over 97% at half load.The simplicity that results from the lack of windings in the rotor -- along with the higher efficiency that results -- is what makes permanent magnet generators attractive as a design option for wind turbines.
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Senior Renewable Energy Analyst (WindGEMINI Product Lead) DNV GL Bristol (City Centre), City of Bristol