In this paper, a novel E-core dual-permanent magnet flux-switching (DPM-FS) machine is proposed for traction applications in electrified transportation. The key is that an extra set of permanent magnet (PM) source is artfully inserted into stator slot openings, which has a parallel main flux path with spoke-type PMs, significantly improving the utilization ratio of the stator core as well as alleviating the magnetic saturation in the iron core. As a result, the proposed machine exhibits a bidirectional flux improvement ability of multiple working harmonics. The working harmonics of air-gap flux density with positive contributions to torque production are greatly enhanced, and those with negative influences are effectively suppressed. Compared with a conventional E-core FSPM machine with the same PM volume, the proposed machine exhibits a 42.8% higher open-circuit back electromotive force (EMF) and a 38.5% higher average output torque. A magnetomotive force (MMF)-permeance model is established to investigate the working principle of the proposed machine. Furthermore, the effectiveness of the proposed design is verified by using finite element analysis (FEA) and experimental results.

A novel dual permanent magnet (PM) machine with Halbach segmentation flux modulation is proposed in this paper, which is evolved from a flux switching PM machine (FSPM). In order to improve the performance of the FSPM, several PM arrangement methods have been adopted and three new different structures have been investigated. To achieve a fair comparison, all the structures are under the same size and rotate at the same speed. The performances of output torque and back EMF are compared. The analysis results show that the dual PM with Halbach segmentation has the highest torque density and power efficiency. The torque is improved by 100.3% from the FSPM while the PM volume does not increase too much. The unique of this best structure is that it not only combines the vernier machine and FSPM machine together, but also reduces the torque ripple. The performance of the motor is verified by the simulation using finite-element analysis (FEA).

In this paper, a novel dual-set permanent magnet (PM) flux-switching (DSPM-FS) machine is proposed for the improvement of torque density and fault-tolerance capability. Originating from a flux-switching permanent magnet (FSPM) machine with a U-shaped PM array, fault-tolerance stator teeth are first introduced in the stator slots to prevent the risk of short-circuit faults between coils of different phases. Subsequently, aiming to enhance the torque generation, a set of surface-mounted PM is added to the fault-tolerance teeth. Due to a parallel flux circuit, the phase flux linkage is greatly increased, further improving the no-load back electromotive force (EMF). Meanwhile, a magnetomotive force (MMF)-permeance model is established, which reveals that the amplitudes of the main working harmonics of the DSPM-FS machine are significantly elevated. Moreover, the proposed and conventional machines are comprehensively compared regarding various electromagnetic performances. Consequently, the no-load back EMF and output torque of the proposed machine are increased by 43.89% and 31.47%, respectively. Additionally, the proposed machine showcases a comparable overload performance compared to the conventional machine. Furthermore, the fault-tolerance ability and power efficiency of the proposed DSPM-FS machine also exhibit notable improvement. Finally, a prototype is fabricated and tested to verify the performance of the proposed machine.

In this work, a novel general pattern of assisted flux barriers in an asymmetric V-shape interior permanent magnet (AVIPM) machine is presented. The AVIPM machine has a symmetric permanent magnet (PM) structure and an asymmetric rotor core structure to realize the magnetic-field-shifting (MFS) effect. The general pattern can represent four possible types of assisted flux barriers at different positions on the rotor core and the final structure can be automatically determined by using optimization method. The advantage of the proposed optimization pattern is that the optimal design of assisted flux barriers in V-shape interior permanent magnet (VIPM) machines with high torque and low torque ripple can be generated within a short computing time. The proposed optimization method is applied to improve the structure of a conventional 8-pole 48-slot VIPM machine, which is commonly used for driving electric vehicles (EVs). A non-dominated sorting genetic algorithm II (NSGA-II) is used for the global optimization of both a VIPM machine and an AVIPM machine. The electromagnetic performance is computed using a finite element analysis (FEA). Moreover, a frozen permeability (FP) method is applied to perform an accurate separation of PM torque and reluctance torque. The results exhibit that the peak output torque of the AVIPM machine is increased by 8.7% compared to a conventional VIPM machine with the same PM volume due to the notable MFS effect. In the meantime, the AVIPM machine has a better overload capability due to the larger contribution of reluctance torque. Moreover, the proposed machine has high efficiency of over 97%.

Recently, the interest in consequent-pole flux-switching permanent magnet (CP-FSPM) machines has been increasing because of the flux-focusing PM arrangements and the removal of the flux-barrier effect. A simple and rigid outer-rotor salient pole rotor structure can be adopted in CP-FSPM machines, making them applicable for in-wheel direct-drive applications. In this study, three CP-FSPM machines with II-shaped (II-PM), V-shaped (V-PM), and straight U-shaped PM (SU-PM) arrays are analyzed and compared. Moreover, a CP-FSPM machine with inclined U-shaped PM (IU-PM) arrays is proposed to improve the flux-focusing effect and stator slot utilization. The working principles of CP-FSPM machines are analyzed by adopting a semi-analytical model. Combining the finite element analysis (FEA) results of air gap flux density and the analytical model of phase back electromotive force (EMF), the contributions of multiple working harmonics to the back EMF are quantitatively analyzed. Additionally, 6/16 and 6/17 CP-FSPM machines with different PM arrangements are globally optimized. Both the no-load and on-load performance of the optimized machines are included in the performance comparison. The results illustrate that the 6/16 and 6/17 machines exhibit their respective merits, and the IU-PM machine shows the best torque production ability in these CP-FSPM machines with the same design criteria.

This paper presents a comprehensive analysis of a novel complementary dual-stator Vernier machine (DSVM) with improved performance. In contrast to conventional DSVMs, the proposed machine employs a unique configuration featured by a complementary stator design alongside phase-shifted dual stator winding. Therefore, the symmetry of flux distribution is improved, and the non-working even order harmonics produced by the armature winding are effectively reduced. Consequently, the power factor is notably improved to 0.91, and the unbalanced force is reduced by 60.14% compared to the conventional DSVM. The electromagnetic performance, mechanical structure and thermal analysis are well investigated by using finite element analysis (FEA). In addition, the temperature rise under the rated load condition with natural cooling is safe, and the mechanical strength is proved to be sufficient, which validates the feasibility of the proposed novel design. Finally, a prototype is fabricated, and the performance is tested to verify the feasibility of the proposed design.