A Permanent Magnet Brushless Doubly Fed Generator With Segmented Structure

The brushless doubly fed machine (BDFM) has been one of the key topics in the research of wind power generation. To improve the performances of the BDFM, a new permanent magnet (PM) brushless doubly fed generator (BDFG) with complementary structure is proposed in this paper. Compared with the traditional BDFM, there is an additional PM rotor providing excitation magnetic field for power and control windings. Benefiting from the absence of the exciting current and the excitation loss, the efficiency, and the power density may be increased. In order to solve a series of problems due to the introduction of PM rotor and the field modulation ring, the segmented structure is adopted. The improvement schemes are introduced in detail. Finally, the performances of the proposed BDFG are analyzed by the finite-element analysis and the results verify the effectiveness of the proposed methods.