I. INTRODUCTIONThe most well-known application of a doubly fed machine is probably the use of a doubly fed induction generator (DFIG) with a wind turbine. A clear drawback to the use of DFIGs is the need for slip rings to supply power to the rotor circuit, which may result in increased operation and maintenance cost [1]. Nowadays, the brushless doubly fed reluctance machines (BDFRMs) have been developed as a class of machines that is controlled using a power converter that has a rating lower than the total power rating of the machine which makes it an attractive solution for applications where speed control over a limited operating range is required like in the case of wind turbines. It has two windings with different no. of poles. One of the windings called primary winding which is connected directly to the power grid, while the other winding called secondary winding is connected through a variable speed drive to grid and is used to control the output frequency [1]. The machine model proposed is an axial flux machine with dual stator topology. In this paper, axial flux brushless doubly fed reluctance machine (AF-BDFRM) is designed and analyzed and the initial FEA results are presented. II. MACHINE MODEL AND DESIGN EQUATIONSThe machine model presented in this paper has two stators and one salient pole reluctance rotor. The salient pole rotor is made of only iron and winding free. The absence of permanent magnets, ability to control power factor and stable mechanical structure of the machine make it overall cheaper and more rugged. Absence of copper losses in the rotor also increases the overall efficiency of the proposed machine. Lower stator pole number, P 1 is 8 and its winding is named primary winding which is directly connected to the grid and the upper stator pole number, P 2 is 16 and its winding is named secondary winding and it is connected to the grid through a converter. Proposed machine can operate in sub-synchronous, synchronous or super-synchronous mode depending on whether a negative sequence frequency, DC or positive sequence frequency is applied to the secondary winding, respectively [1]. Different parts of the new proposed machine are illustrated in Fig. 1. The relationship among the no. of saliencies of rotor and both stators pole pairs is as under [1],[2]: P r = (P 1 + P 2 ) / 2 (1) -: if direction of excitation field and rotor are in opposite. +: if direction of excitation field and rotor are same. Where, subscript 1 and 2 denotes the primary and secondary winding, respectively and rotor electrical speed will be: ω r = (ω 1 + ω 2 ) / 2 (2) After that, the torque expression of the new machine is similar to a double air gap machine which can be written as T = 3/2 Pr ( λ qs i d2` -λ ds i q2` )= 3/2 P r L m ( i d2` i q1 -i q2` i d1 ) (3) The above expression is reduced in steady state to T = 3/2 L m ( i d2` i q1 ) = 3/2 P r λ ds i q1 = 3/2 P r ds N 1 i q1 (4) Where is its assumed that I d1 = 0 (unity power factor of the primary winding) so that λ ds = L m I d2. By Choosing radial length of machine...

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