Theoretical analysis of doubly excited brushless reluctance machine used in wind power generation system

The doubly excited brushless reluctance machine (DEBRM) is a new type of reluctance machine and is attractive for converter-fed variable speed drive applications and variable-speed constant-frequency generating systems. The DEBRM system features not only simplicity, robustness and reliability of the reluctance or cage-rotor inductance machines, but a much smaller power electronic converter, compared to a conventional AC induction machine. This paper bases on winding function theory, establish the linear model of the DEBRM to calculate the air-gap flux distribution and winding flux linkages of the two sets of stator windings. The self and mutual inductance of the two stator windings is computed for equivalent circuit derivation, and the DEBRM torque capabilities are investigated with 3-pole rotor machine. All the results are used to highlight the common principles of electromechanical energy conversion for the DEBRMs with unconventional magnetic structures and provide insights into the optimal design and control of a practical DEBRM.