Analysis of Steady State Performance of Brushless Doubly Fed machine

Brushless doubly fed machine (BDFM) is indeed an induction machine which has two windings in the stator and a cage rotor with a special design. Due to absence of brushes and slip rings, this machine is considered for the applications needs high reliability, such as wind turbines. In this paper, stead state performance of BDFM in synchronous mode of operation, the most interesting mode of operation, is studied in more detail and, in addition to theoretical analysis, the required experimental results are presented. A new relationship is developed for calculation of the electromagnetic torque, which based on that, the share of synchronous and induction torques are determined in the synchronous mode. It is shown that in this mode, the synchronous mode has the dominant effect and hence, the induction torques could be neglected in steady state calculations, reducing calculations and facilitating analysis of results.