Optimal design of the direct-driven high power permanent magnet generator turbine by wind

In this paper, an optimal design method of a high power permanent magnet synchronous generator (PMSG) turbine by wind is proposed. The expression of the cogging torque was studied based on the Fourier analysis. A method of permanent magnet shifting to reduce cogging torque was presented. In this paper a prototype for 5MW generator was built and a comparative study of the performance both of no load and rated load was made based on finite element analysis (FEA) for the machine with the normal magnets and the machine with the shifted magnets. It was proved that the cogging torque and the harmonics of the back electro motive force (EMF) can be greatly reduced by the proposed method. With this PM shifting method, it is helpful to obtain the better performance of the direct-drive PMSG.