Abstract：This research focused on the separation and calculation of electromagnetic losses in semi-direct

drived permanent magnet wind generators（SDDPMWG）. Firstly，analytical method for calculating core loss of

motor considering harmonic current was derived based on the Bertotti method. The eddy current loss of permanent

magnet was obtained by analyzing axial and tangential components of the eddy current density of permanent

magnet. The analytical methods for calculating DC copper loss，AC copper loss，and circulating current loss of the

stator winding were also analyzed. Secondly，the changes of flux density over time in 6.5 MW SDDPMWG were

analyzed according to finite element method. The spatial and temporal harmonics of flux density in the core were

abundant. The impact of electromagnetic frequency on core loss of generator was calculated and analyzed. Then the

relationship between eddy current loss of permanent magnet and electromagnetic frequency in 6.5 MW

SDDPMWG was studied. Eddy current loss of permanent magnet increases with the increase of electrical frequency.

Finally，finite element method and theoretical method were combined to calculate winding DC loss，AC loss and

circulating current loss of 6.5 MW SDDPMWG quantitatively. The winding AC loss and circulating current loss are

big.The research results can be effectively used for electromagnetic loss separation calculation of SDDPMWG. It

can also provide support for the development of high-performance and low-cost SDDPMWG.

      Key words：semi-direct drived；permanent magnet wind generator；electromagnetic losses