Torque analysis and slot regions assignment of a DC-excited flux-modulated machine with two stator windings

This paper presents a DC-excited flux-modulated (DCEFM) machine. It has one rotor with p_r poles and two sets of windings on one stator. One of the windings has p_f pole-pairs and is excited with DC current. The second winding has p_a pole-pairs and is excited with AC sinusoidal current. The relationship between pr, p_f and p_a is p_r = p_f + pa. The purpose of this paper is to analyze the torque of the machine in order to optimize the slot regions assigned to the two stator windings for generating the highest torque at the admissible copper losses. Firstly, the torque equation of the machine is derived. The methods described in this paper are also feasible for other machine types such as variable flux reluctance machine, field excited flux-switching machine. By using the finite element analysis (FEA) the analytical results are verified. The results show that the magneto motive forces (MMFs) of the two windings need to be approximately equal to obtain optimal torque.