Size reduction of permanent magnet generators for wind turbines using halbach cylinders

It has been demonstrated that by employing a Halbach cylinder as the rotor in an outer rotor 3.5kW PMG, size reduction is possible. By varying the number of magnet segments in the Halbach cylinder, the outer diameter of the rotor can be reduced by up to 25%, translating to a 29% reduction in rotor volume. The potential for reduction of material use is significant for large wind turbine application. However, the Halbach cylinders investigated do not produce sufficient magnetic flux density over the rotor surface to allow for the use of rare earth free PMs. Halbach cylinders with a smaller angle of rotation of magnetization direction between magnet segments will be investigated in future work.