ABSTRACT
This chapter shows the benefits of the new concept compared with conventional machines by describing its evolution using the conventional surface-mounted permanent magnet machines as a reference. A successful directly driven generator will be able to produce a moderate to high shear stress while elegantly negating the effect of the magnetic attraction. A lightweight generator produces cost savings in terms of manufacturing, transportation, installation and decommissioning, as well as cost benefits in terms of designing other parts such as the tower and foundations. The stator must allow sufficient electrical loading to provide the necessarily large torque – needed for this low-speed direct-drive application – and support the coils in air. The discrete nature of these coils means they could be designed to be replaced relatively easily. This will be of significant advantage in larger machines, as electrical faults are one of the more common causes of failure for direct-drive generators in wind turbines.
