Assessment of core losses in a flux-modulating synchronous machine

In this paper, the core losses that occur in a 4-kVA flux-modulating synchronous machine (FMSM) were investigated using 2D finite element analysis (FEA), and the results were supported by experiments. A method for reducing the rotor core loss was also presented. The FMSM is a new type of multipole synchronous machine in which the stator field MMF is modulated by the air-gap permeance to generate the rotating field. A 2p_a-pole three-phase armature winding and a 2p_f -pole field winding are centrally wound around individual stator teeth, and a reluctance rotor with 2p_r(= p_a + p_f) saliencies is used to provide a magnetic coupling between these windings. As a result of the investigation, although the total core loss was not very significant in the 4-kVA FMSM, the core loss in the rotor was found to be about the same amount as that in the stator. Additionally, it was shown that the rotor core loss could be effectively reduced by decreasing the height of the rotor poles.