Design and Analysis of a Novel Hybrid Excitation Flux Reversal Machine

A novel hybrid excitation flux reversal machine (HEFRM) is developed. The machine has a simple reluctance rotor and a stator, which has both an ac armature winding and a dc field winding. The core on the surface of the pole arc at the centerline of the stator pole and the core on the outer surface of the stator yoke each have a slot along the rotating axis, where the field windings are placed. A permanent magnet (PM) with opposite polarity is placed respectively on each side of a slot in the same stator pole. In this paper, the working principle of the new HEFRM is introduced, the influence of magnetic pole parameters and armature parameters on motor performance are also analyzed, and genetic algorithm (GA) is used for multi-objective optimization of the torque characteristics. Finally, the HEFRM prototype is built, and its theoretical correctness is verified by the finite element analysis (FEA).

Design and Performance Assessment of a Small-Scale Ferrite-PM Flux Reversal Wind Generator

Currently, there is increasing research interest in harnessing wind energy for power generation by means of non-conventional electrical machines e.g., flux-reversal machines. The flux reversal machine is usually designed using scarce rare–earth permanent magnet material which may be unattractive in terms of machine cost. In this study, an attempt is made to re-design the flux reversal machine with non-rare-earth ferrite permanent magnet for wind energy applications. Because these machines possess high cogging torque, which results in vibration and noise, that are detrimental to the machine performance, especially at low speeds, a novel combined skewed and circumferential rotor pole pairing method is developed. The proposed cogging torque reduction method is implemented in 2-dimensional finite element analysis modeling and comparatively analyzed with other existing stand-alone methods viz., skewing, and rotor pole pairing. The results show that the proposed method led to 94.8% and 71% reduction in the cogging torque and torque ripple compared to the reference generator, respectively. However, the calculated torque density is reduced by 13%. Overall, the electromagnetic performance of the proposed ferrite PM machine exhibits desirable qualities as an alternative design for the direct drive wind generator.