This paper proposes a novel hybrid-excitation flux-switching (HEFS) machine with axial partitioned stator (APS) arrangement, which can achieve the independent accommodation of armature winding and field-excitation winding, thus enhancing the field-excitation capability and improving the winding heat dissipation. More importantly, a particular parallel-magnetic-circuit (PMC) hybrid-excitation pattern consisting of the axial and radial magnetic paths is innovatively developed in the HEFS machine, which is an effective solution for improving the flux-regulation ability. Consequently, the PMC-based flux-regulation principle is comprehensively illustrated. Moreover, by investigating the flux-regulation characteristics of three structural feasible APS-HEFS topologies, the bilateral complementary structure is finally determined as the preferred option. By using the multi-objective optimization method and the three-dimensional finite element analysis (3D-FEA), the dimensional parameter optimization design of the proposed machine is conducted, and the performance comparison with a conventional HEFS counterparts is also carried out to prove the flux-regulation superiority of the proposed design. Finally, a prototype is fabricated for experimental testing, and the measured results are in good agreement with the FEA, which verifies the validity of the proposed APS-HEFS topology and its theoretical flux-regulation principle analysis.

This article presents a novel flux-switching (FS) machine adopting star-array permanent-magnets (PMs), termed as star-FSPM machine. In comparison with the conventional spoke-FSPM machine, the proposed one can achieve not only enhanced flux-concentration effect, but also enlarged stator-slot area, thus improving PM utilization ratio and torque density. The harmonic characteristics of both PM field and armature reaction field in the star-FSPM machine are investigated based on the field modulation theory. More importantly, the torque generation mechanism of the star-FSPM machine is also investigated and compared with that of the spoke-FSPM machine. The results show that the proposed machine can utilize the working harmonics more effectively for torque generation. Afterwards, the electromagnetic performance comparison of four PM machines is carried out by finite-element analysis. It is found that the proposed star-FSPM machine exhibits improved PM utilization ratio and enhanced torque density as compared to the spoke-FSPM machine. Finally, the theoretical analysis and FEA results are verified by experimental measurement.

This paper reveals the fundamental reason for the asymmetrical issue in magnetic-geared machines (MGMs) based on flux modulation theory. The analysis indicates that the magnetic circuits of three-phase windings in MGMs are inherently asymmetrical. This asymmetrical issue is even more severe in conventional consequent-pole MGMs (CP-MGMs) because of the more distorted magnetic field. Hence, to address the asymmetrical issue, a novel structure featuring enhanced harmonic elimination capability is proposed in this paper. Consequently, torque density can also be improved. In particular, the proposed CP-MGM employs modular structure and axially embedded permanent magnets (PMs) to achieve symmetrical back electromotive force (EMF) waveforms and improved torque capability, respectively. To further improve the electromagnetic performance of the proposed CP-MGM, the PM arc ratio and flux modulator width ratio are analytically designed, which provides a general design guideline for CP-MGMs. To illustrate the merits of the proposed CP-MGM, a few other MGMs are included for a fair comparison based on finite element analysis (FEA). Results show the proposed CP-MGM can achieve more symmetrical back EMF waveforms and lower torque ripple, as well as lower PM consumption and higher torque density, as compared with its MGM counterparts.

This paper proposes a magnetic equivalent circuit (MEC) model for a two degree-of-freedom rotary-linear machine with transverse flux structure. The permeance grid is formed according to the flux pattern generated in finite-element method (FEM). By tuning the leakage flux permeance, the electromagnetic performance of the rotary-linear machine calculated by the MEC model shows good alignment to that by FEM. To fully demonstrate the benefits of the MEC model, the calculation accuracy and time consumption comparisons among the MEC model, magnetomotive force (MMF) model, and FEM are conducted. In addition, the MEC model is applied to the parametric study, which proves that the MEC model is capable of obtaining the accurate results under various geometry designs. Based on that, a hierarchical optimization flow is put forward which is a practical method for global optimization on 3D structure. Finally, an experimental prototype is manufactured to verify the proposed concepts.

This paper investigates a flux-switching (FS) machine with U-V-array permanent magnet (PM) arrangement, termed UV-FSPM. The key design is to construct parallel magnetic circuit by adopting U-V-array PMs. Based on the parallel magnetic circuit, the operating principle of the UV-FSPM is illustrated. To provide a deeper insight into the torque enhancement mechanism, the analytical model of the UV-FSPM is built by using the general air-gap field modulation theory. It is found that the U-V-array PMs can significantly enhance the dominant working harmonic which effectively contributes to torque enhancement of the investigated UV-FSPM. To reveal the impact of key parameters on torque performances, the parametric optimization of the UV-FSPM is conducted. The electromagnetic performances of three FSPMs are comparatively studied by finite element analysis (FEA). It is proved that the investigated UV-FSPM exhibits the highest torque density and highest PM utilization ratio within the pool. Finally, a prototype of the UV-FSPM is fabricated and tested for verification of the investigated concepts.

This article aims to investigate a novel hybrid-magnet variable flux memory machine (VFMM) with improved field regulation capability for electric vehicle applications. Two sets of permanent magnets (PMs), i.e., high-energy-density neodymium–iron–boron PM and low coercive force (LCF) PM, are arranged in a delta array to improve field regulation capability and torque density. The machine topology, key features, and operating principle of the presented machine are demonstrated. Based on the simplified magnetic circuit model, the underlying design tradeoffs of the presented machine are revealed qualitatively. The nonlinear magnetic circuit model of the presented machine taking saturation and hybrid-magnet leakage flux into consideration is built for machine analysis. Electromagnetic performance comparisons are carried out by finite element analysis between the presented VFMM and the existing VFMM. The results show that the presented machine can achieve significantly improved flux regulation capability while maintaining the high output torque due to the improved arrangement of hybrid magnetic branches and enhanced flux concentration effect. Finally, the investigated VFMM is prototyped. The operating principle and predicted results are verified by experimental results.