Design and optimization of a transverse flux machine using an analytical 3-D magnetic charge model

Offshore wind farms are gaining more attention in the development of new renewable energy sources at the expense of onshore wind farms. The higher energy yield of an offshore wind farm is the main advantage. The reliability and efficiency of the wind turbine is of great significance as the capital costs for installation and maintenance as well as the repair time are increased over onshore wind turbines. The reliability of the commonly used gearbox is low and when reliability is considered besides efficiency, the direct drive permanent magnet generator is favorable. Energy produced from renewable sources by direct drive generators requires operation at low speeds in the range of 10 to 90 rpm. A machine topology with a high number of poles and high force density is needed in order to keep losses, mass and size limited. The Transverse Flux Machine (TFM) makes it possible to have a high pole number and high power density as the space for the winding is independent of the space for the poles and magnet flux. A segment of a TFM is shown in Fig. 1.