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 (SM) (FMSM) are investigated using 2-D finite-element analysis, and the results are supported by experiments. A method for reducing the core losses is also presented. The FMSM is a new type of multipole SM in which the stator field magnetomotive force 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, it was found that, although the core losses occur in the rotor as well as in the stator, the rotor core loss can be effectively reduced by decreasing the height of the rotor poles.