Search Results (47)

The five-phase fault-tolerant consequent-pole permanent-magnet Vernier machine (FTCP-PMVM) has attracted extensive research attention owing to its excellent permanent-magnet utilization while maintaining competitive electromagnetic performance. However, the double-salient structure poses considerable challenges for analysis. The torque generation and power factor characteristics of the FTCP-PMVM are analyzed from a magnetic field modulation perspective in this work. Initially, based on the air gap field modulation effect, the modulation processes of both the permanent-magnet field and the armature field are analyzed. Subsequently, the torque generation mechanism is explained through harmonic matching resulting from the field modulation process, the results demonstrate that the 23rd air gap harmonic dominates the generation of average electromagnetic torque and accounts for the majority of output torque. Furthermore, the power factor is examined in depth by analyzing the reactive power contributed by the machine inductive components (e.g., self-inductance, mutual inductance and leakage inductance) and the active power generated by the permanent-magnet portion, all from the standpoint of field modulation. Finally, a prototype is fabricated to test the machine’s torque, power factor and efficiency. Experimental data confirms the reliability of the theoretical analysis. Full article

Axial–radial flux permanent magnet synchronous machines (ARFPMSMs) are an emerging family of electrical machines that combine radial flux and axial flux topologies within a single electromagnetic structure. By using multiple radial and axial air gaps, they increase the effective torque-producing surface without enlarging the machine envelope, which enables higher torque density and better utilization of active materials than in conventional single-flux topologies. This makes them attractive for traction, aerospace, wind, elevator and other compact high-torque applications. This paper reviews the state of the art of ARFPMSMs and provides four main contributions. First, it proposes a unified topology-oriented classification of classical PM-only, hybrid-excitation and vernier/flux-modulated ARFPMSMs, while clarifying their conceptual boundary with transverse-flux machines. Second, it consolidates published designs and compares key parameters across the three families. Third, it summarizes experimentally validated prototypes, including rated power, torque density, materials and cooling methods. Finally, it identifies open research challenges and outlines future directions, including surrogate models, Bayesian optimization and active cooling strategies. Full article

Nowadays, direct-drive systems are widely used in the actuators of computer numerical control machine tools. Linear motors are widely used in high-end computer numerical control machine tools due to their high positioning accuracy, good dynamic response, and simple transmission structure. First, a high-thrust-density concentrated magnetic linear permanent magnet vernier motor is proposed in this paper, which is designed by machine learning and optimized through an artificial intelligence optimization algorithm, to improve the air-gap magnetic density of the motor and improve the thrust density of the motor in principle; compared with traditional linear permanent magnet synchronous motors, the thrust density is increased by 40%. Second, using finite element calculations, a regression machine learning algorithm is proposed, which involves introducing a regression machine learning algorithm (called extreme learning machine (ELM)) to solve the computational modeling problem; compared with traditional ELM networks, it has faster training speed and higher stability. By mapping the nonlinear complex relationship between input structural factors and output motor performance, the superiority of the intelligent optimization algorithm is confirmed by comparative verification. Full article

This work presents the design, fabrication, and characterization of a three-dimensional FeCo-based flux-modulator microwinding intended for integration into high-torque axial-flux Vernier micromotors. The proposed micromotor architecture modulates the stator magnetic flux using 12 magnetically isolated FeCo teeth interacting with an 11-pole permanent-magnet rotor. The design requires the manufacturing of complex three-dimensional micrometric parts, including three teeth and a cylindrical core. Such a complex design cannot be manufactured using conventional micromanufacturing lithography or 2D planar methods. The flux-modulator envelope dimensions are 250 μm outer diameter and 355 μm height. It is manufactured using a femtosecond laser-machining process that preserves factory-finished surfaces and minimizes heat-affected zones. In addition, this micrometric part has been wound using 20 μm diameter enamelled copper wire. A dedicated magnetic clamping fixture is developed to enable multilayer microwinding of the integrated core, producing a 17-turn inductor with a 60.6% fill factor—the highest reported for a manually wound ferromagnetic-core microcoil of this scale. Geometric and magnetic characterization validates the simulation model and demonstrates the field distribution inside the isolated core. The results establish a viable micromanufacturing workflow for complex 3D FeCo microwindings, supporting the development of next-generation high-performance MEMS micromotors. Full article

Advancements in ship propulsion technologies are essential for improving the efficiency and reliability of maritime transportation. This study introduces a comprehensive approach that integrates motor design with sensorless control strategies, specifically focusing on Dual Three-Phase Permanent Magnet Vernier Motors (DTP-PMVM) for ship propulsion. The initial section of the paper explores the design of a 5-MW DTP-PMVM using finite element method (FEM) analysis in dual three-phase configurations. The subsequent section presents a novel sensorless control technique employing a Prescribed-time Sliding Mode Observer (PTSMO) for accurate speed and position estimation of the DTP-PMSM, eliminating the need for physical sensors. The proposed observer convergence time is entirely independent of the initial estimation guess and observer gains, allowing for pre-adjustment of the estimation error settling time. Initially, the observer is designed for a DTP-PMVM with fully known model parameters. It is then adapted to accommodate variations and unknown parameters over time, achieving prescribed-time observation. This is accomplished by using an adaptive observer to estimate the unknown parameters of the DTP-PMVM model and a Neural Network (NN) to compensate for the nonlinear effects caused by the model’s unknown terms. The adaptation laws are innovatively modified to ensure the prescribed time convergence of the entire adaptive observer. MATLAB (R2023b) Simulink simulations demonstrate the superior speed-tracking accuracy and robustness of the speed and position observer against model parameter variations, strongly supporting the application of these strategies in real-world maritime propulsion systems. By integrating these advancements, this research not only proposes a more efficient, reliable, and robust propulsion motor design but also demonstrates an effective control strategy that significantly enhances overall system performance, particularly for maritime propulsion applications. Full article

The scaling effect of machines from kW to MW greatly affects electromagnetic performance and needs to be investigated for different machines. Therefore, this paper presents a comprehensive comparative study on the intriguing electromagnetic performance of contra-rotating permanent-magnet vernier machines and dual-port, wound-field-excited, flux-switching machines at the MW power level for contra-rotating wind turbine applications. The analysis evaluates both machines across various slot/pole combinations while maintaining constant key design parameters. The electromagnetic performance analysis reveals that the permanent-magnet vernier machine (PMVM) exhibits superior torque and power, with minimal cogging torque compared to the wound-field flux-switching machine (WFFSM). Conversely, the WFFSM outperforms the PMVM in terms of power factor and efficiency. This study provides valuable perspectives on the strengths and weaknesses of each machine, highlighting their potential for contra-rotating turbine and wind power generation. Finally, to justify the findings of the finite element analysis and the proof of concept, an experimental prototype is tested to validate the study. Full article

This paper proposes a new Asymmetric Permanent Magnet Vernier Motor (A-PMVM) for low-speed high-torque applications. Unlike conventional symmetric V-shaped PMVMs (SV-PMVMs), the A-PMVM features irregular U-shaped magnet arrays composed of asymmetric V-shaped magnets. Finite element analysis confirms its superior performance: 10.6% higher torque (19.67 N·m vs. 17.78 N·m), 22% reduced PM volume (37,500 mm³ vs. 48,000 mm³), and 53% lower cogging torque (0.32 N·m vs. 0.68 N·m peak-peak). While exhibiting higher initial torque ripple ratio (8.65%), multi-objective optimization suppresses torque ripple ratio by 5.32% (from 8.65% to 8.19%), reduces cogging torque 12.5% (from 0.32 N·m to 0.28 N·m), and enhances torque by 0.76% (from 19.67 N·m to 19.82 N·m). The optimized A-PMVM achieves a significant reduction in cogging torque and torque ripple ratio, demonstrating significant potential for applications like wind turbines and electric vehicles. Additionally, this paper confirms that the proposed motor maintains consistent performance during both clockwise and counterclockwise operation. Full article

The permanent magnet vernier motor (PMVM) is characterized by high torque density and torque transmission capability. It is widely used in applications such as electric transportation and renewable energy generation, where low-speed, high-torque operation is preferred. This paper reviews the basic working principles and development of topologies, as well as the applications of PMVM. The methods to improve the torque density, power factor, and torque ripple of PMVM are discussed. Furthermore, the paper explores the future development trends of PMVM, providing theoretical foundations and technical support for their further research and engineering applications. In addition to these areas, PMVMs have gained significant attention in precise motion control systems, such as in robotics and CNC machines, where high torque and low vibration are critical. Vernier motors are also being explored in applications like actuators for aerospace systems and advanced medical equipment, where reliability and efficiency are paramount. The ability to precisely control the torque ripple and improve the power factor of PMVMs makes them ideal for use in these demanding environments. Full article

In this paper, a Dual Winding Flux Modulation Machine (DWFMM) is proposed for variable speed application. The DWFMM is configured by adding windings to the Single Winding Flux Modulation Machine (SWFMM), consisting of a master winding that drives the motor and a slave winding that enables pole changing and performance enhancement. Through pole changing, the DWFMM can operate as two different machines: a Vernier Machine (VM) for varying speeds and torque operations and a Permanent Magnet Synchronous Machine (PMSM). In the VM mode, flux enhancement is applied to improve torque, and in the PMSM mode, Flux Weakening is applied to increase speed. The characteristics of the two different operating modes were analyzed using the Finite Element Method (FEM) to validate the machine’s performance. Finally, the DWFMM and SWFMM were designed and compared as variable speed application machines to confirm their suitability and superiority. Full article

This paper presents the results of a comprehensive investigation into the comparative analysis and design optimization of ferrite-based surface permanent magnet vernier machines (SPMVMs). While SPMVMs boast a simple mechanical structure and enhanced torque density attributed to the flux modulation effect, they suffer from a persistent challenge of low power factor. Several factors hinder the adoption of low-cost ferrite magnets in SPMVMs. First, ferrite magnets are prone to irreversible demagnetization, constraining the allowable range of magnet thickness. Second, the reduced residual magnetic flux density of ferrite magnets exacerbates the decrease in power factor and machine efficiency. Thus, achieving optimal performance in ferrite-based SPMVMs necessitates the careful selection of various design parameters. To address these issues, this study employs a surrogate-based metaheuristic optimization algorithm with adaptive sampling to identify the optimal solution. Additionally, the integration of a Halbach array is explored to further enhance the performance of the three-slot/two-pole SPMVM topology. Subsequently, two ferrite-based SPMVM baseline models—one with a conventional SPM structure and another with a Halbach magnet array—are thoroughly designed, optimized, and subjected to detailed performance analysis using the 2D finite element method. Full article

The evolution of electric propulsion systems in the maritime sector has been influenced significantly by technological advancements in power electronics and machine design. Traditionally, these systems have employed surface-mounted permanent magnet synchronous motors (PMSMs) in podded configurations. However, the advent of permanent magnet Vernier motors (PMVMs), which leverage magnetic gearing effects, presents a novel approach with promising potential. This study conducts a comparative analysis between PMVMs and conventional PMSMs at a power level of 5 MW for podded ship propulsion, with a particular focus on the impact of gear ratios ($Gr$). An objective function was developed that integrates motor dimension constraints and the power factor (PF), a critical yet frequently neglected parameter in existing research. The findings indicate that PMVMs with lower $Gr$ have lower mass and cost compared to those with higher $Gr$ and traditional PMSMs, at a PF level of 0.7, which is high for Vernier machines. Moreover, PMVMs with lower $Gr$ achieve efficiencies exceeding 99%, outperforming both their higher $Gr$ counterparts and conventional PMSMs. The superior performance of PMVMs is attributed to lower current density and reduced copper loss, which contribute to their enhanced thermal performance. These details are elaborated on further in the paper. Consequently, these findings suggest that PMVMs with lower $Gr$ are particularly well suited for high-power maritime propulsion applications, offering advantages in terms of compactness, efficiency (EF), cost-effectiveness, and thermal performance. Full article

This paper proposes an analytical model of the double-stator spoke-type permanent magnet vernier machine (DSSTVM) using the subdomain method (SDM), which can be used to calculate the magnetic field distribution and corresponding electromagnetic parameters of the DSSTVM. The whole field domain is divided into several subdomains according to the magnetic characteristics of each region, within which Laplace’s and Poisson’s equations are solved accordingly in terms of magnetic vector potential (MVP). Then, the corresponding magnetic flux density distribution, back electromotive force (EMF), and electromagnetic torque of the DSSTVM can be obtained. Ultimately, finite element analysis (FEA) is adopted to validate the proposed analytical model’s effectiveness for quickly predicting the no-load and on-load performances of the DSSTVM. Full article

The permanent magnet vernier synchronous machine (PMVSM) has the characteristics of high torque density and high power density and has advantages in the field of low-speed and high-torque applications. The PMVSM utilizes rich harmonics for torque enhancement, but it can also cause an increase in radial electromagnetic force and vibration noise. In this paper, we take a 12-slot 10-pole PMVSM as an example to analyze the source of radial electromagnetic force, vibration and noise. The electromagnetic finite-element model and structural finite-element model of the PMVSM are established for calculation. Through the analysis and calculation of two-dimensional electromagnetic fields, the radial electromagnetic force distribution of the PMVSM is obtained. We derive the radial electromagnetic force formula of the PMVSM and verify the correctness of the formula through harmonic analysis of the radial electromagnetic force. The sources of radial electromagnetic forces at various orders and frequencies within the PMVSM are analyzed and summarized by coupling the radial electromagnetic force obtained from the electromagnetic finite-element model to the structural finite-element model and conducting electromagnetic vibration harmonic response analysis on the PMVSM. The measured acceleration spectrum of the prototype is compared with the finite-element method (FEM) results, verifying the correctness of the finite-element simulation results for electromagnetic vibration. Full article

This paper presents the efficiency improvement of a pole-changing vernier machine (PCVM) by considering the residual magnetic flux density ($B_r$) of low coercivity force (LCF) permanent magnets (PMs). The PCVM operates in two modes: vernier machine (VM) mode and permanent magnet synchronous machine (PMSM) mode, achieved through pole-changing. Pole-changing involves reversing the magnetic flux direction of LCF PM to alter the number of rotor pole pairs. By changing the number of rotor pole pairs, the PCVM operates as a VM mode at low speeds, providing high torque, and as a PMSM mode at high speeds, offering high efficiency. To achieve this, a combination of high coercivity force (HCF) PM and LCF PM is utilized in a single structure. The magnetic flux direction in the LCF PM is determined by $B_r$, and the highest efficiency is achieved when $B_r$ reaches its maximum value |$B_{rm}$|. This paper focuses on improving efficiency by obtaining $B_{rm}$ in VM mode and −$B_{rm}$ in PMSM mode through the design process. Additionally, finite element analysis (FEA) is employed to compare the performance of the improved model, which considers $B_r$, with that of the conventional model, designed without considering $B_r$. The improved model achieves higher $B_r$ values in each mode compared to the conventional model, resulting in increased torque density. Consequently, this leads to improved efficiency. Full article

The Double Permanent Magnet Vernier (DPMV) machine is well known for its high torque density and magnet utilization ratio. This paper aims to investigate the torque generation mechanism and its improved design in DPMV machines for hub propulsion based on the field modulation principle. Firstly, the topology of the proposed DPMV machine is introduced, and a commercial PM machine is used as a benchmark. Secondly, the rotor PM, stator PM, and armature magnetic fields are derived and analyzed considering the modulation effect, respectively. Meanwhile, the contribution of each harmonic to average torque is pointed out. It can be concluded that the 7th-, 12th-, 19th- and 24th-order flux density harmonics are the main source of average torque. Thanks to the multi-working harmonic characteristics, the average torque of DPMV machines has significantly increased by 31.8% compared to the counterpart commercial PM machine, while also reducing the PM weight by 75%. Thirdly, the auxiliary barrier structure and dual three-phase winding configuration are proposed from the perspective of optimizing the phase and amplitude of working harmonics, respectively. The improvements in average torque are 9.9% and 5.4%, correspondingly. Full article