Search Results (21)

To further satisfy the extreme operating conditions of electric tractors, a pole-changing double-sided excitation permanent magnet vernier motor (PC-DPMVM) is proposed evolving from the existing PC-SPMVM in this paper. Half of the rotor PMs are transferred to the stator small slots, while a consequent-pole rotor structure and stator PM structure can be obtained. Firstly, the simulation and experiments of the existing PC-SPMVM are introduced, which shows the deficiency of the maximum torque output. Then, the evolution process of the proposed PC-DPMVM is illustrated. The rotor modulation and stator modulation behaviors of the PC-DPMVM are introduced based on airgap field modulation theory. The main working PM flux density harmonics are deduced further. Next, electromagnetic performance comparisons are made between two PC-PMVMs by using finite element method, and the results reveal that the proposed PC-DPMVM has superior torque output compared with the PC-SPMVM, while the speed regulation abilities of the two motors are similar. It can be concluded that two extra operation regions can be obtained for the PC-DPMVM according to the comparison of torque-speed curve of the two motors. 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

Permanent magnet vernier motors (PMVMs) have significant advantages in low-speed direct-drive fields on account of their high torque density, and their performance improvement is still a research hotspot. To enhance the overall electromagnetic performance and provide an alternative solution for low-speed direct-drive applications, this paper proposes a permanent magnet vernier motor with rotor auxiliary teeth (denoted as “RAT-PMVM”). Firstly, the structure and working principle of RAT-PMVM are introduced. Then, the two-dimensional (2D) finite element method (FEM) is used to comparatively study the influence of the number, position, and tooth profile of the rotor auxiliary teeth on the electromagnetic performance of the proposed motor. The results show that the RAT-PMVM with trapezoidal teeth (denoted as “TT-PMVM”) achieved improvement in output torque, efficiency, and power factor: the output torque increased from 11.32 Nm to 14.19 Nm, the efficiency increased from 88.5% to 92.2%, and the power factor increased from 0.60 to 0.71. Finally, in order to further reduce the torque ripple and improve the torque, power factor, and efficiency, multi-objective optimization of the TT-PMVM is carried out. The optimization yields a 27.3% increase in torque, a 31.8% reduction in torque ripple ratio, an efficiency improvement from 92.2% to 93%, and a power factor enhancement from 0.73 to 0.81, demonstrating significant potential for low-speed direct-drive applications like industrial robots and wind power generation. 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

Nowadays, motor type plays a significant role in the vehicle performances. This article compares various types of permanent magnet vernier motors (PMVMs) with different shapes of field modulation teeth and different numbers of field modulation poles (FMPs). Based on this, the electromagnetic performance of permanent magnet synchronous motors (PMSMs) and PMVMs is compared. First, the back EMF, air gap flux density, flux density distribution, and torque of PMVMs with different shapes of FMPs are compared. Based on the selected PMVMs, the rated torque and overload capacity of PMVMs with different slot–pole combinations are compared. Subsequently, the comprehensive electromagnetic performance of PMVMs and PMSMs is compared, where the strength and weakness of PMSMs and PMVMs are concluded. Finally, a prototype is manufactured and tested, verifying the correctness and accuracy of the simulation model. 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

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

Aging is commonly associated with a decline in motor control and neural plasticity. Tuning cortico–cortical interactions between premotor and motor areas is essential for controlling fine manual movements. However, whether plasticity in premotor–motor circuits predicts hand motor abilities in young and elderly humans remains unclear. Here, we administered transcranial magnetic stimulation (TMS) over the ventral premotor cortex (PMv) and primary motor cortex (M1) using the cortico–cortical paired-associative stimulation (ccPAS) protocol to manipulate the strength of PMv-to-M1 connectivity in 14 young and 14 elderly healthy adults. We assessed changes in motor-evoked potentials (MEPs) during ccPAS as an index of PMv-M1 network plasticity. We tested whether the magnitude of MEP changes might predict interindividual differences in performance in two motor tasks that rely on premotor-motor circuits, i.e., the nine-hole pegboard test and a choice reaction task. Results show lower motor performance and decreased PMv-M1 network plasticity in elderly adults. Critically, the slope of MEP changes during ccPAS accurately predicted performance at the two tasks across age groups, with larger slopes (i.e., MEP increase) predicting better motor performance at baseline in both young and elderly participants. These findings suggest that physiological indices of PMv-M1 plasticity could provide a neurophysiological marker of fine motor control across age-groups. Full article

This paper investigates the performance enhancements of permanent magnet Vernier machines (PMVMs) that can be achieved using a new structure of Halbach array permanent magnets (HAPMs) for a direct-drive motorcycle application. To start with, size and design specifications of the electric machine are determined based on the assumed acceleration and drive cycle performance of a motorcycle. Then, five-segment Halbach array permanent magnet Vernier machines (HAPMVMs) with two different slot/pole combinations (24 s/44 p and 12 s/20 p) are suggested and optimized to achieve a high torque density with an acceptable power factor while maintaining a low torque ripple. Two selected designs from optimizations are investigated in the full speed range considering power factor and efficiency maps. Consequently, in order to demonstrate the effectiveness of the proposed five-HAPM structure, the same optimization methods are repeated with three-segment HAPMs as well as with single-piece PMs. The comparisons show a great enhancement in torque and power factor achieved with the use of five HAPMs. For instance, for 22 s/44 p topology, generated torque doubles with the use of five-segment PMs compared to single-segment PMs. Finally, the harmonics of magnetic flux density in the airgap of PMVMs and HAPMVMs are compared and investigated to reveal the reasons behind the superiority of VMs with HAPMs. Full article

Removing the gearbox from the single-motor configuration of an electric vehicle (EV) would improve motor-to-wheel efficiency by preventing mechanical losses, thus extending the autonomy of the EV. To this end, a permanent-magnet Vernier machine (PMVM) is designed to ensure such operation. This machine avoids the high volume and large pole-pair number of the armature winding since its operating principle resembles that of a synchronous machine with an integrated magnetic gear. Therefore, such a structure achieves low-speed and high-torque operation at standard supply frequencies. From the specification of an urban vehicle, the required specification for direct-drive operation is first determined. On this basis, an initial prototype of a Vernier Machine with permanent magnets in the rotor that can replace the traction part (motor + gearbox) is designed and sized. This first prototype uses radial contiguous surface-mounted magnets and its performance is then analyzed using finite element analysis (FEA), showing a relatively high torque ripple ratio. The rotor magnets are then arranged in a quasi-Halbach configuration and simulations are performed with different stator slot openings and different ratios of the tangential part of the magnet in order to quantify the effect of each of these two quantities in terms of average torque, torque ripples and harmonics of the back-electromotive force at no load. Since the design and optimization of this motor is finite element-assisted, a coupling process between FEA Flux software and Altair HyperStudy is implemented for optimization. This method has the advantages of high accuracy of the magnetic flux densities and electromagnetic torque estimates, and especially the torque ripples. The optimization process leads to a prototype with an average torque value that meets the specification, along with a torque ripple ratio below 5% and a high power factor, while keeping the same amount of magnet and copper. Full article

This paper investigates the prospect of permanent magnet vernier machine (PMVM) technology for wind power applications. Two types of PMVMs are defined based on the winding arrangements and resultant gear ratio ranges. A comprehensive design study of the selected PMVM topologies is conducted at 1 and 3 MW power levels. The optimized candidate designs of the PMVMs are then evaluated and also compared against the equivalent permanent magnet synchronous machine (PMSM) in terms of performance, costs, size and mass. While the existing research publications mainly focused on the PMVM designs of ($G_r=5$), this study reveals that the pole/slot combinations of PMVMs with ($G_r\le 5$) are more appealing as there is a good trade-off between a reasonable power factor and high power density in these designs. It shows, in this paper, that the PMVM is a promising alternative to common PMSM technology for utility-scale wind-turbine drive-train applications. Full article

This paper presents theoretical studies of Fano resonance based electric-field (E-field) sensors. E-field sensor based on two electro-optical (EO) materials i.e., barium titanate (BaTiO${}_3$, BTO) nanoparticles and relaxor ferroelectric material Pb(Mg${}_{1/3}$Nb${}_{2/3}$)O${}_3$-PbTiO${}_3$ (PMN-PT) combined with nanostructure are studied. As for the BTO based E-field sensor, a configuration of filling the BTO nanoparticles into a nano-patterned thin film silicon is proposed. The achieved resonance quality factor (Q) is 11,855 and a resonance induced electric field enhancement factor is of around 105. As for the design of PMN-PT based E-field sensor, a configuration by combining two square lattice air holes in PMN-PT thin film but with one offsetting hole left is chosen. The achieved resonance Q is of 9,273 and an electric field enhancement factor is of around 96. The resonance wavelength shift sensitivity of PMN-PT nanostructured can reach up to 4.768 pm/(V/m), while the BTO based nanostructure has a sensitivity of 0.1213 pm/(V/m). If a spectrum analyzer with 0.1 pm resolution is considered, then the minimum detection of the electric field $E_{min}$ is 20 mV/m and 0.82 V/m for PMN-PT and BTO based nanostructures, respectively. The nano-patterned E-field sensor studied here are all dielectric, it has therefore the advantage of large measurement bandwidth, high measurement fidelity, high spatial resolution and high sensitivity. Full article

The purpose of this paper is the design, analysis, and optimization of a new structure of a permanent magnet vernier machine (PMVM) with a high torque density and low rotor losses. First, the modulation principle and topology of this PMVM is introduced. Then, its average torque and rotor loss are enhanced and reduced by optimizing the flux modulation poles distribution. For the sake of further reducing the rotor losses on the premise of maintaining the torque density, the contribution of the air gap flux density harmonics to the rotor loss is analyzed. Then, a new topological structure of a rotor with a flux barrier is introduced to reduce the rotor losses due to the decrease of each harmful harmonic. Through the analysis of the structure of the PMVM with the flux barrier, the influence of the parameters on the performance is built. After that, a multi-objective optimization algorithm is used to optimize the PMVM so as to obtain the optimal performance. Moreover, the electromagnetic performance comparison between the newly proposed machine and the original one is presented to indicate that lower rotor losses can be obtained by the proposed machine when the torque is ensured. Finally, a prototype of proposed PMVM is built and further tested to verify the validities of the theoretical and finite-element analyses. Full article

This paper presents a novel topology of dual airgap radial flux permanent magnet vernier machine (PMVM) in order to obtain a higher torque per magnet volume and similar average torque compared to a conventional PMVM machine. The proposed machine contains two stators and a sandwiched yokeless rotor. The yokeless rotor helps to reduce the magnet volume by providing an effective flux linkage in the stator windings. This effective flux linkage improved the average torque of the proposed machine. The competitiveness of the proposed vernier machine was validated using 2D finite element analysis under the same machine volume as that of conventional vernier machine. Moreover, cogging torque, torque ripples, torque density, losses, and efficiency performances also favored the proposed topology. Full article