The brushless doubly-fed reluctance machine is attracting attention because it has no brushes and a reduced converter drive requirement [1][2]. It has a reluctance type of rotor of p pole pairs. The stator will have two sets of 3-phase windings with p±1 pole pairs. Test machines that have been investigated have had 4 rotor poles with 2- and 6-pole stator windings although there is no reason why higher pole numbers cannot be used. While the application for these machines could be in the area of power drives, they could also be used in wind turbines as an alternative to the wound field induction generator [3]; their operation can be considered as being similar with two windings and the rotor speed being independent of the rotating field velocity. In the induction machine, the windings are couple directly by a common pole number whereas in the reluctance type of machine the MMFs are modulated by air-gap permeance to produce flux waves of p±1 producing cross coupling. It is necessary to use a rotor with a high d-q reluctance ratio as is vector control for correct operation [4]. One winding is fixed in frequency and volts (grid connection or power winding) and the rotor speed varies according to the load; there is a synchronizing requirement for the non-grid connected winding (control). The equation governing this is ω_c=pω_r-ω_p, where the ω is a rotational velocity (rad/sec) and c, r and p represent the control frequency, rotor velocity and grid frequency.
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