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.

Torque density is a crucial performance metric for flux-switching permanent magnet (FSPM) machines. However, the emergence of flux barriers tends to impede the magnetic field modulation effect, especially in machines with high pole ratios, ultimately impacting overall performance. To solve this issue, this paper proposed a consequent-pole FSPM machine with a flux-concentrated magnet design. The proposed machine adopts a 12-slot/13-pole configuration with a pole ratio of 13. To optimize the magnetic field concentration, the design integrates shortened clockwise tangentially magnetized PMs under an “h” core, positions radially magnetized PMs at the core's shoulders, and inserts counterclockwise tangential PMs into the slot openings. This arrangement effectively addresses the magnetic barrier issue, enhancing the magnetic field compactness within the machine. The operating principle of the proposed FSPM machine is analyzed using analytical computations and finite element analysis (FEA). The structural parameters are optimized for maximum average torque and efficiency. The proposed machine offers a 14.96% higher average torque and 2.1% higher efficiency than the existing FSPM machine with flux bridges at the same stator copper loss. A 640 W-rated prototype of the proposed machine was fabricated and tested, validating the simulation results and design accuracy through experiments.

A novel asymmetric spoke-type interior permanent magnet (AS-IPM) machine is proposed in this paper. It utilizes the magnetic-field-shifting (MFS) effect to improve the torque performance, which achieves a high utilization ratio of both permanent magnet (PM) torque and reluctance torque. In addition, a general pattern of rotor topologies is proposed to represent all possible machine structures. Various rotor structures can be obtained by changing the design parameters of the general pattern. A non-dominated sorting genetic algorithm II (NSGA-II) is adopted to automatically search for optimal rotor configurations. With the aid of the optimization program, an asymmetric spoke-type rotor structure with improved performance is obtained. To showcase the advantages of the proposed machine, the electromagnetic performance is compared between a conventional spoke-type interior permanent magnet (S-IPM) machine and a proposed AS-IPM machine. The finite-element simulation results show that the optimal design of the AS-IPM performs a 7.7% higher output torque ripple due to the MFS effect while the total PM volume remains the same. Meanwhile, the torque ripple of the proposed structure is significantly reduced by 82.1%.

Thrust ripple and density greatly impact the performance of the linear machine and other linear actuators, causing positioning control precision, dynamic performance, and efficiency issues. Generalized pole-pair combinations are difficult to satisfy both the thrust and ripple for double salient reluctance linear machines. In this paper, a DC-Biased vernier reluctance linear machine (DCB-VRLM) is proposed to solve the abovementioned issues. The key to the proposed design is to reduce the ripple and enhance the thrust density with non-uniform teeth by utilizing and optimizing the modulated flux in the air gap. To effectively verify the proposed design, the DCB-VRLMs with different winding pole pairs and secondary poles are compared. The 12-slot/10-pole combination is chosen to adopt a non-uniform air gap structure. Moreover, the energy distribution of AC/DC winding is studied and optimized to further enhance the performance of the proposed DCB-VRLM. The results indicate that the DCB-VRLM with the non-uniform air gap has a lower thrust ripple, better overload capability, and higher thrust density, which confirms its superiority in long-stroke linear rail transit and vertical elevator applications.

At present, the majority of electric machine design software employs its own unique machine data structure. However, when users need to transfer their designs between software, they are often faced with significant obstacles or cannot obtain a parametric model suitable for optimization. In order to solve this issue, a universal parametric modeling framework is proposed for electric machine design. The geometric structure is strictly constrained to ensure that the model will not interfere with each part because of the randomness of input parameters. A data structure consisting of points, lines, and surfaces is constructed, and a conversion interface for parametric modeling with different software is established. Consequently, this universal framework can automatically generate parametric models appropriate for different finite element analysis (FEA) software according to the input parameters. The framework is especially convenient for users who need to design or optimize an electric machine, particularly when FEA software is required for verification. Numerical verification is performed using different software based on interior permanent magnet (IPM) synchronous machines to demonstrate the effectiveness of the framework.

High torque output capability is crucial for electric vehicle in‐wheel machines. In order to comprehensively evaluate the performance of different out rotor flux reversal permanent magnet (FRPM) machines, a comparative study of two FRPM machines with different topologies is conducted. Different from the conventional consequent pole FRPM machines (CPFRPM), the FRPM machine with auxiliary teeth (ATFRPM) features a stator tooth with a complete piece of permanent magnet (PM) of the same polarity, whereas the adjacent stator tooth is devoid of any PM. The paper introduces the topology structure of the machine using a 24‐slot/22‐pole combination and analyses its operation principle. Geometrical parameters are globally optimised to improve torque performance of FRPM machines. Furthermore, the electromagnetic characteristics of the CPFRPM and ATFRPM machines are compared under the same current density. The ATFRPM machine exhibits superior performance in efficiency, power factor and torque density. Finally, an ATFRPM machine prototype is manufactured to verify the theoretical analysis, and the experimental results confirm the effectiveness of the simulation analysis and optimised design.