8--Comparison of Losses and Efficiency in Alternate.pdf

ΦAbstract -- The performance of the optimized conventional, novel E- and C-core flux-switching permanent magnet (FSPM) machines having different combination of stator and rotor pole numbers is compared by finite element analyses, with particular reference to the conductor and magnet eddy current loss and iron loss. Both iron loss and conductor eddy current loss increase with the rotor pole number, while the 11- and 13- rotor pole machine always exhibit lower magnet eddy current loss than those of the 10- and 14-rotor pole machine, respectively. The E- and C-core machines use half number and volume of magnets but exhibit higher efficiency than those of the conventional FSPM machine. Index Terms-- Brushless, direct drive, flux-switching, permanent magnet, torque density. I. INTRODUCTION S a kind of permanent magnet (PM) brushless AC machine with non-overlapping windings, a flux- switching PM (FSPM) machine [1-3] exhibits high torque density and efficiency which are similar to those of a fractional-slot PM machine [4]. Hence, it has been extensively investigated recently [5-9]. The design parameters of the FSPM machine were optimized and its electromagnetic performance was analyzed in [4], [10]. The other design considerations, such as the influence of end- effect [11], iron loss [12], [13], eddy current loss in magnets [14], proximity copper loss [15], [16], were investigated. On the other hand, new topologies of FSPM machine were proposed. In [2], the 3-phase FSPM machine was developed from the 1-phase FSPM machine which was firstly introduced in 1950s [1]. Then the alternate pole wound and multi-phase FSPM machines were investigated in [17], [18]. However, the foregoing machines have large magnet usage which also reduces the slot area since the magnet is on the stator, Figs. 1(a) and (b). In order to reduce the magnet usage, the stator pole without armature winding in the conventional FSPM machine with alternate poles wound, Fig