Structural analysis and optimisation of transverse flux permanent magnet machines for 5 and 10 MW direct drive wind turbines

The transverse flux permanent magnet generator offers high power density in terms of active mass. Two configurations of this machine topology (referred to as TFPM-1 and TFPM-2) are described, and optimised electromagnetic designs are presented. Direct drive generators require a significant support structure, which is designed to minimise the deflection into the air gap due to inherent electromagnetic attraction forces. The design of these structures is also dependant upon the generator topology. Structural design tools, which can be used in a design office environment, have been developed for the transverse flux machine and verified using commercial numerical modelling packages. Generic disc and arm structures are used. Only static analysis has been performed, but this does provide the designer with an estimate for more detailed design. A comparison of mass is made between the two transverse flux machines and a more conventional iron-cored permanent magnet generator. The comparison shows that TFPM-2 has the lowest total mass at 5 and 10 MW, but the conventional iron-cored machine is lighter than TFPM-1. Copyright (C) 2012 John Wiley & Sons, Ltd.