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In this paper, a novel method for suppressing the detent force of permanent magnet linear synchronous motors is proposed. First, the end force is adjusted to offset the cogging force while the cogging force remains unchanged. On the other hand, the proposed method can arbitrarily change the shape of the end magnetic regulating module (EMRM), thus allowing the end force to obtain a wider adjustment range, which is different from the conventional limited shape optimization. More interestingly, compared to the traditional approach for suppressing the end force, which is to suppress the end force to the lowest level, the proposed method does not necessarily suppress the end force to the lowest level, but rather adjusts it to a reasonable level, so that it can offset the cogging force. This leads to the fact that the optimized end magnetic regulating module is effective in adjusting the end force and may even increase the end force, which is different from the conventional idea of suppressing the detent force. Next, the optimal EMRM's topologies are solved using the optimization algorithm, which replaces the traditional low-dimensional single-direction optimization and performs multi-direction global search. Finally, the prototype with optimal EMRM's topology and the testing platform are established and the experimental results validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Neodymium (Nd) magnets (Nd 2 Fe 14 B) are key materials for achieving high energy conversion efficiency. The coercive forces (fields) of the magnets are often reinforced by adding dysprosium (Dy), especially at high temperatures. To understand the magnetic properties of Dy-substituted systems (Nd 1 − x Dy x) 2 Fe 14 B, it is important to study those of Dy 2 Fe 14 B and Nd 2 Fe 14 B and analyze the difference in detail from a microscopic viewpoint. Applying a recently developed atomistic model approach, we investigated thermodynamic properties of these magnets. We studied the temperature and field dependences of the magnetizations, and anisotropy fields and energies. We found that the simulation results captured the characteristic features of the experimentally observed data. We discuss the detail with the magnetization profiles of the component atoms. Furthermore, we investigated the effect of Dy random substitution on the coercivity in two systems: one in contact with vacuum and the other in contact with a grain boundary phase. We found that the threshold fields increased almost linearly with the concentration of Dy atoms in both systems, which was compared to the results of the layer-by-layer substitution effect analyzed in our previous work. We discuss the influence of the arrangement of Dy atoms on coercivity enhancement. [ABSTRACT FROM AUTHOR]

This study presents an approach to achieve a triaxial magnetic alignment through a linear drive type of modulated rotating magnetic field by using a permanent magnet array. This magnet array generates a modulated rotating magnetic field (MRF) without moving the sample and can produce an MRF of ∼ 0.8 T. By utilizing this magnet array, DyBa2Cu3Oy (Dy123, y ∼ 7) grains were biaxially aligned. After cutting the as-aligned sample that was magnetically aligned, we observed a location dependence of the orientation degree. We achieved the higher in-plane orientation degree of ∼ 8.5° and the c-axis orientation degree of ∼ 6.0°, respectively. The 3D simulation analysis played a key role in identifying the region where the uniformity of the MRF is within the magnet array. Compared to the epitaxial growth techniques, the use of the magnet array offers a cost-effective and versatile solution for achieving triaxial magnetic alignment. [ABSTRACT FROM AUTHOR]

L10-MnAl exhibits excellent magnetic properties and could be used as a candidate to fill the gap between hard ferrite and rare-earth based permanent magnet (PM) applications. However, one of the major problems with L10-MnAl is that the structure is metastable and decomposes to other structural phases at higher temperature. Therefore, enhancing the structure stability of L10-MnAl is essential for PM applications. We studied the prospect of improving the structural stability and increasing the uniaxial magnetic anisotropy energy (K u) of the L10-MnAl structure in this work. It is found that C-doping at the 1d interstitial site enhanced the structure stability of the compound. Moreover, Fe substitution on Mn sites shows a significant increase in the uniaxial magnetic anisotropy energy (K u). Therefore, the electronic structure and magnetic properties of L10-ordered Mn1−xFexAlC (x = 0, 0.125, 0.250, 0.375, 0.50, 0.625, 0.75, and 0.87) alloys are investigated by using the first-principles calculations. The results show that x = 0.375 Fe content in the L10-MnAl alloy and 6% doping of C maintained the structural stability and provided a maximum value of K u = 2.13 (MJ/m3), which is 25% higher than for the pristine L10-MnAl, making it suitable for permanent magnet applications. [ABSTRACT FROM AUTHOR]

The paper focuses on the potential of magneto-fluorescent nanostructures intended to join simultaneously several functions of dissimilar core and shell material into a single entity. Two different types of magneto-fluorescent nanostructures with a broad array of physicochemical properties are premeditated and collated here. Strontium hexaferrite (Hard ferrite) core with CdS shell and Nickel Zinc ferrite (Soft ferrite) core with CdS shell are the two sets of magneto fluorescent nanostructures that were designed. Magnetic and optical analysis of both sets provides divergent outcomes. The shape of the derivative hysteresis curve gives a direct indication of the dissimilar nature (superparamagnetic & Permanent magnetic) of magnetic cores respectively. Optical results depict that both sets of magneto-fluorescent nanostructures are highly stable showing emission only in the position of the CdS shell only. [ABSTRACT FROM AUTHOR]

This work focuses on the study of the microstructure and magnetic properties of nanocrystalline powders of Sm4ZrFe33, prepared by high‐energy ball milling. The Sm4ZrFe33 compound adopts a monoclinic structure (space group Cm). Upon annealing, these Sm4ZrFe33 samples exhibit notable variations in their extrinsic magnetic properties, closely linked to temperature fluctuations. The investigation delves into the correlation between morphology, grain size and magnetic characteristics. A significant enhancement in coercivity (Hc), remanent magnetization (Mr), and maximum energy product ((BH)max) is observed, primarily attributed to the finer grain structure present in the samples. Particularly noteworthy, among all annealed specimens, the nanocrystalline Sm4ZrFe33 compound annealed at a temperature of Ta = 973 K demonstrates the most promising magnetic properties. This specimen exhibits a coercivity Hc of 18 500 Oe, remanent magnetization (Mr) of 58 emu g−1, maximum energy product ((BH)max) of 5.18 MGOe, Curie temperature (TC) of ≈804 K, and magnetic anisotropy field (Ha) of 115 980 Oe. These research findings pave the way for future investigations and applications in the realm of permanent magnets, spintronic devices, and magnetic recording, utilizing nanocrystalline alloys based on the Sm4ZrFe33 compound. [ABSTRACT FROM AUTHOR]

A novel direct instantaneous torque control (DITC) strategy based on optimized conduction angle is proposed with the aim of reducing the torque ripple of permanent magnet-assisted switched reluctance motor (PMa-SRM) during the two-phase exchange (TpE) region in this paper. Firstly, according to the inductance characteristics, the TpE region is subdivided into TpE I and TpE II region where the turn-off angle is acted as the region separation point, and the corresponding torque hysteresis strategies are formulated in different regions. Secondly, K-fold extreme learning machine (ELM) method is used to optimize the turn-on angle in order that the current of incoming phase can quickly increase to maintain torque balance. In order to make full use of the ability of torque generation of two adjacent phases, the position where the torque of adjacent phases is equal is used as the turn-off angle of incoming phase. Finally, a 6/20 PMa-SRM prototype is simulated and verified. Compared with the conventional DITC strategy, the novel strategy not only diminish torque ripple and negative torque under different operating conditions, but also expands the operating range of the motor and improves the motor efficiency. [ABSTRACT FROM AUTHOR]

Analyzing the magnetization reversal process is crucial for enhancing the magnetic properties of nanocomposite magnets, thereby subsequently increasing the magnetic energy product and advancing the development of next-generation rare earth permanent magnet materials. Here, the open recoil loop is systematically investigated based on micromagnetic simulations and comparing magnetization configurations, which is strongly associated with the asymmetric behavior of weak pinning at the soft/hard magnetic interface. By removing and reapplying field, the irreversible weak pinning sites exhibit asymmetric behavior, leading to the formation of open phenomena in nanocomposites. The open degree of recoil loops obtained from experimental testing was also correlated with the irreversible magnetization, which supports the simulation results. Our findings provide a novel approach for understanding the magnetization reversal mechanism in nanocomposite magnets. [ABSTRACT FROM AUTHOR]

To maximize the performance of rotating machines, it is essential to establish a design method with minimal arbitrariness. This paper proposes a self‐assembling method to design stator slots for alternating current (AC) rotating machines. First, we develop a line‐current approximation model of the stator winding using pulse‐width modulation technique and realize an ideal spatial magnetic flux density distribution. Subsequently, we design the realistic stator with an acceptable current density of the winding by forming unique slot shapes in a self‐assembling manner under two synthetic conditions using the developed line‐current approximation model as the starting model. The designed stator realizes a rotating magnetic field similar to the conventional design results. Additionally, we perform an analysis of motor rotation characteristics by combining the self‐assembled stator with a surface‐mounted permanent magnet rotor to determine the possibility of a higher output compared to that when using a conventional stator. The self‐assembled motor without relying on empirical rules shows a possibility of further improving the torque characteristics, thereby contributing to designing the AC rotating machines. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A vibration absorption meta-structure with strong nonlinear stiffness is proposed by combining concepts of the vibration absorber and meta-structure. An experimental setup comprising the meta-structure and a primary oscillator is designed. The results of ultraslow linear sweep and fixed-frequency harmonic excitation tests show that the meta-structure can suppress the vibrations of the primary oscillator with different stiffnesses. Moreover, the meta-structure changes the resonance frequency band of the test system to an acceptable range when softer springs are used in the primary oscillator. The primary oscillator and meta-structure have almost the same phase when the resonance occurs, resulting in an acceptable change. Another meta-structure mode is activated as its frequency increases, inducing an additional resonance band when a harder spring is attached. Furthermore, permanent magnets are installed in the meta-structure to form a bistable characteristic, and the influences of the number of magnets on the vibration reduction are analyzed. When the meta-structure has twelve magnets, the high-frequency resonance peak is eliminated because the magnets can suppress the second mode of the meta-structure. The wavelet analysis is conducted to detect the frequency components. The meta-structure results in energy spread from the excitation frequency to the other frequencies. [ABSTRACT FROM AUTHOR]

We have successfully fabricated a series of the SmCaBCuO bulk superconducting ceramics with different ratios of nanoscale Boron doping into mixture powder by the solid-state reaction method. Permanent magnets (PMs) with three different values in the same form were used for magnetic levitation force (MLF) measurements. During measurement of levitation forces between small PMs and bulk high Tc superconducting ceramic materials, significant hysteretic behavior was observed as a function of the distance between the magnet and the superconductor. We focused on the effect of doping and different permanent magnets on magnetic levitation force (MLF) measurements and magnetic stiffness calculations of materials, considering zero field-cooling (ZFC) and field-cooling (FC) conditions. It was seen that MLF decreased with the increase in boron dopant in the sample under ZFC conditions. We explained this result with weak bonds between grain boundaries, cracks and grain size reduction in the samples. Under FC conditions, with the increase of permanent magnet value and nano boron doping, the levitation force, which should be effective, left its place to the attractive force. Flux trapping centers formed by doping dominate the attractive force. The increase in doping caused a decrease in magnetic stiffness values. The increase in the permanent magnet caused an increase in the stiffness values of the material. This result agrees with the literature. The MLF and magnetic stiffness data got will be useful in the technological applications of maglev and carrier systems. [ABSTRACT FROM AUTHOR]

In order to study the influence of electromagnetic (EM) effect and load change on the modal characteristics and dynamic response of gear transmission system driven by permanent magnet synchronous motor (PMSM), a electromechanical coupling dynamic model is established. The composite air gap permeability coefficient is introduced, and the formula of permanent magnet flux linkage under the influence of space harmonic and cogging effect is derived. The variation laws of gear meshing stiffness and bearing support stiffness under the influence of load change are simulated and analyzed. The natural frequency and vibration modal under different load, flux linkage and PI controller gain are revealed. On this basis, the influence of EM effect and load change on the resonance domain is analyzed through frequency sweep analysis and time domain simulation. Results indicate that the 1st order natural frequency and resonance amplitude will increase with the load, and the influence of PMSM EM excitation will gradually dominate. The increase of the flux linkage and speed loop controller gain Kpω will reduce the 1st order natural frequency. When Kpω=123, a new mode appears, and there is a modal transition between the new mode and mode 1 when Kpω=161. The research results can provide theoretical guidance for improving the transmission performance and structure optimization design of the permanent magnet gear transmission system. [ABSTRACT FROM AUTHOR]

With the rise of eco-friendly policies, advanced motor technologies are being developed to replace fossil fuel-based engines in the mobility industry. Axial flux motors, known for their ability to reduce size and increase output torque compared to radial flux motors, require different materials and manufacturing techniques. Specifically, the production of complex stator cores and segmented magnets presents significant challenges, often leading to higher costs. To address this issue, soft magnetic composite (SMC) materials, which offer greater design flexibility, are being explored for use in stator cores. However, soft magnetic composite materials exhibit lower permeability and saturation flux density compared to laminated silicon steel, resulting in reduced output torque and efficiency. This paper investigates the effects of stator geometry on axial flux motor performance and explores cladding core technology, which combines soft magnetic composite materials with silicon steel. By conducting finite element method (FEM) analysis to evaluate the output torque and efficiency based on the shape of the silicon steel within the cladding core, this study proposes an optimized cladding core design to enhance the efficiency and output torque of axial flux motors. [ABSTRACT FROM AUTHOR]

L10-ordered FeNi (tetrataenite) exhibits a large saturation magnetization and a robust uniaxial magnetic anisotropy, making it a valuable rare-earth free candidate for permanent magnet applications. It has been predominantly identified in iron meteorite rocks, and its laboratory synthesis has been hindered due to sluggish diffusion occurring below the order-disorder temperature of about 600 K. Doping of Cu is anticipated to facilitate interdiffusion and therefore enabling the laboratory synthesis of the L10-ordered FeNi phase. This study investigates interdiffusion and magnetization in undoped and Cu-doped Fe/Ni thin film multilayers through a complementary usage of polarized neutron reflectivity (PNR) and SQUID-VSM (S-VSM). The PNR measurements were performed on the as-deposited (at 423 K) and isochronally annealed samples at 473, 503, 533, and 573 K. It was found that the magnetic moment of Fe/Ni multilayers was not significantly affected by Cu doping but a substantial increase in interdiffusion is clearly evident. The enhancement of coercivity and anisotropy field was further examined using S-VSM. These findings are expected to lead to a new pathway toward the laboratory synthesis of the L10 phase. [ABSTRACT FROM AUTHOR]

Eddy‐current technique has been used in several industrial applications, such as non‐destructive testing and characterization, transmission systems, and separation processes. The main advantage of other separation techniques for eddy current separation is the absence of direct contact and do not use other liquid and water. This paper presents a novel configuration for a single‐disk vertical eddy current separator, covered by alternating permanent magnets. Unlike several other works, which employ a horizontal orientation for magnetic disks. The advantage is that it contains one driving motor, few strong permanent magnets, and a small size and simpler construction than the usual eddy‐current separators. In this work, the analysis of an eddy current separator with magnetic single disk using a numerical model based on finite element method, the obtained partial differential equation is done into the numeric solver. The experimental device was realized to separate two kinds of non‐ferrous waste: aluminium and copper. The experiment results show the effect of speed variation, metals size, and kind of metal on ejection distance. [ABSTRACT FROM AUTHOR]

An experimental investigation has been conducted with respect to the effect of permanent magnet stirring (PMS) under different rotation speeds (0, 60, 180 rpm) on the solidification of AH32 shipbuilding steel by analyzing the inclusion evolution, solidification structure, and mechanical properties. As the rotation speed increased from 0 to 180 rpm, the mean size of inclusions (Al2O3, MnS, and Al2O3–MnS) reduced significantly from 6.23 to 2.92 μm, their number increased from 49 to 82 n mm−2 and the ratio of complex inclusions increased from 30.6% to 75.6% in the AH32 steel ingot. Besides, the increasing number of small complex inclusion promotes the formation of acicular ferrite in steel, resulting in an elevation of the area ratio from 10.5% to 27.8%. Furthermore, under a rotation speed of 180 rpm, the mean grain size decreased to 99.4 μm and the frequency of high‐angle grain boundaries (HAGBs) increased to 86.1%. In addition, the as‐cast AH32 steel exhibited an optimized ultimate tensile strength of 532.0 MPa and an improved elongation of 24.2% after an enhanced PMS, which was attributed to more acicular ferrite, higher HAGBs ratio, and refined grain size. [ABSTRACT FROM AUTHOR]

This article explores the concept of impulsive magnetic damping (IMD) and its application to a physical pendulum. It discusses how circular magnets passing over a bar induce eddy currents, resulting in the dissipation of mechanical energy and damping of the oscillation. The article provides mathematical equations to calculate the power of dissipation and loss of energy for each swing. It also describes the experimental setup used to study IMD and concludes that it leads to linear damping instead of exponential damping. The authors suggest that this experiment could be used for physics instruction at the undergraduate level. [Extracted from the article]

Ferrofluid droplets falling toward a permanent magnet elongate as they approach the magnet. This phenomenon has been proposed as a way to visualize how tidal (nonuniform) forces can cause stretching/elongation of objects, such as the bulging of Earth's oceans under the nonuniform force of the Moon's gravity. In this manuscript, we analyze a ferrofluid in the nonuniform magnetic field of a permanent magnet and compare a simple model for the tidal stretching mechanism with the magnetic energy mechanism, which is known to stretch a ferrofluid droplet even in a uniform magnetic field. Far from the magnet, both mechanisms display power-law behavior as a function of the distance to the magnet z; for the tidal mechanism, the droplet's elongation is proportional to 1 / z 8 , while that due to the magnetic energy mechanism is proportional to 1 / z 6 . Thus, the elongation of a droplet falling toward a permanent magnet is initially dominated by the magnetic energy effect. The tidal effect overtakes the magnetic energy effect as the droplet approaches the magnet, and at a critical distance, a tidal disruption event occurs. This system can be studied in the laboratory and could be used as an exploratory laboratory for student-designed experimentation. Editor's Note: Have you ever heard of a ferrofluid? They are colloidal suspensions of ferromagnetic particles in a liquid, allowing them to act almost as a deformable superparamagnet. Among their many interesting properties is a distinctive elongation when droplets of ferrofluid fall toward a magnet. This paper was motivated by the question of whether the elongation is due to tidal forces (a force gradient due to the non-uniform magnetic field) or due simply to the lower magnetic self-energy for this shape. Spoiler alert: both contribute. Learn more by reading this paper, which could be used in an upper-level electromagnetism course or could motivate student projects. [ABSTRACT FROM AUTHOR]

Safety, comfort, range, and energy consumption continue to be highly important for today's motor vehicles. This study considers suspension systems and investigates a semi-active suspension system based on a tubular flux-switching linear machine. The study optimizes motor performance by defining objective functions that use genetic algorithms to reduce cogging forces. Different configurations of model including block, circular, and cylindrical magnetized have been compared in terms of flux density, mesh size, and manufacturing cost by using magnetostatic analyses. Changes in induced voltage, cogging force, and thrust force according to the current based on 2D transient time analysis data were investigated. Multi-physics analysis of the machine was performed on a quarter-vehicle model using linear analysis, as using a linear machine was more effective for vibration mitigation. A prototype of the proposed block magnet-configurated machine was manufactured, comprising a linear motion system driven by an induction motor with a crankshaft to simulate linear motion of the suspension system. Analysis shows that the designed machine is effective as a semi-active suspension system for vibration and damping. [ABSTRACT FROM AUTHOR]

Rotor turn short circuit fault of permanent magnet synchronous machines (PMSMs) in the distribution system has a significant issue caused by unbalance loading. This fault has a significant electromagnetic impact on the rotor winding in relation to the machine's external equipment. As a result, while designing the power system distribution network, the PMSMs rotor winding short circuit current limitation receives majority of attention. For simulation a 3-phase short-circuit model of synchronous generator is developed here by using MATLAB/SIMULINK software. Therefore, a method is used to determine a PMSM's internal winding quantity in the event of a short circuit, as well as its location within the distribution network. The PMSM is energized with a small sinusoidal voltage at standstill situation in this suggested approach to compute the synchronous inductance and winding resistance through the output current. It has been demonstrated that the number of shorted windings may be calculated using the variation of output current caused by an internal winding short circuit event under zero fault resistance condition. Except for intricate machine modelling or investigation of machine internal winding short circuit models comprising several tappings, this useful technique can be used to determine fault intensity for a specific synchronous machine. This paper primarily addressed on fault extremity protection strategies using before-fault and after-fault activities by employing harmonic filters. A three-phase synchronous machine model with a protective system is implemented in the distribution network using MATLAB/SIMULINK is taken into consideration in order to verify the findings. The results presented in this work are vital to a complete solution that includes fault reduction techniques. Harmonics elimination and instant fault mitigation techniques with load unbalancing are analyzed based on effective outcomes to judge the system stability and feasibility of the short circuit current intensity assessment. [ABSTRACT FROM AUTHOR]

The fault level is increasing day-by-day due to huge expansion of electrical network. To cope with the increasing fault level, Fault Current Limiter (FCL) is a good solution. Presently, use of DC loads as well as DC transmission is increasing a lot. Each DC load contains a rectifier circuit with it which helps it to convert the AC power source to DC source. Faults may occur at different positions of the network. This paper gives a detailed discussion on the working analysis of a PMFCL for faults occurring at different position in the rectifier circuit. [ABSTRACT FROM AUTHOR]

High pressure torsion (HPT) is presented as a new fabrication route to produce bulk Sm–Co magnets with a strongly refined microstructure down to the nanometer regime. The initial powders, based on the compositions SmCo5, Sm2Co7 and Sm2Co17, are compacted and subsequently deformed by HPT. The microstructural evolution in dependence on the applied deformation parameters is characterized by electron microscopy and the effect of HPT on the phase stability is monitored by synchrotron X‐ray diffraction. An increasing amount of applied strain leads to a stronger reduction in grain size while strain localization counteracts a homogeneous microstructural refinement. The positive effect of elevated deformation temperatures is demonstrated for Sm2Co17, which promotes homogeneous grain refinement, but causes strain‐induced phase transformations at the same time, strongly affecting the magnetic behavior. Superconducting quantum interference device magnetometry is used to characterize the magnetic properties after HPT deformation, which indicates the formation of a magnetic texture depending on the respective phase. [ABSTRACT FROM AUTHOR]

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A356 aluminum alloy has attracted enormous attention because of its excellent mechanical properties and good corrosion resistance. Refining the eutectic Si phase is required to improve the mechanical properties for practical applications. In this work, a new strategy is proposed by synergizing the permanent magnet stirring (PMS) with rare earth (RE) La and Ce elements simultaneously during the solidification of A356 aluminum alloy. Experimental studies reveal that the eutectic Si phase transforms from coarse needle-like and flake-like shapes to small granular morphology, and its average size reduces from 12.94 to 8.86 μm. It is noted that the additions of La and Ce can induce twins and stacking fault structures in the Si phase preventing its further growth. Meanwhile, the PMS can significantly refine the grain size of α-Al phase and generate more small size La–Ce precipitates at the front of Si phase. When PMS and rare earth are applied together, the electromagnetic force generated by PMS and the twins and stacking fault structures induced by rare earth elements La and Ce, collectively act on the A356 alloy to refine both the Si phase and α-Al phases. The refined alloy exhibits an outstanding combination of mechanical properties and wear resistance. [ABSTRACT FROM AUTHOR]

In this paper, a permanent magnet synchronous machine (PMSM) with an auxiliary winding (AW) on the rotor is analyzed by two-dimensional approach. This PMSM with AW (AWPMSM) can be used in many applications such as propulsion system, aircraft and traction because it includes rotor flux control capability. First, the magnetic field in different parts of AWPMSM is calculated based on Maxwell equations. Then, as a consequence of the magnetic field, the torque components, including cogging, reluctance, electromagnetic and instantaneous torque are computed. Next, torque-speed characteristic has been investigated. This AWPMSM can be located in the flux weakening mode in two ways, first one is to attenuate the rotor field by changing the direction of the AW field and the other one is to adjust the armature current angle, both of them have been investigated. After that, the overload capability and temperature effects have been analyzed. Finally, using the meta-heuristic algorithms such as genetic algorithm, particle swarm optimization, differential evolution and teaching learn base optimization the dimensions of AWPMSM and the initial angle of the rotor are determined in such a way that the torque-to-volume ratio is maximized. The influences of the type of armature winding and the magnetization patterns have also been investigated. The results obtained by the two-dimensional method have been confirmed numerically. [ABSTRACT FROM AUTHOR]

A discharge in the annular cavity of a Hall effect thruster is sustained by extracting electrons from a radiofrequency (rf) inductively coupled plasma source located downstream of the thruster structure, where a radial magnetic field of 0.1-0.15 T is applied to the thruster discharge cavity by permanent magnets. Argon gas is introduced into the cavity via an anode structure and the ejected gas passes through the rf plasma source powered by a 13.56 MHz and 200 W generator. After turning on the rf plasma, a dc voltage is applied between a cathode installed inside the rf source and the anode of the Hall effect thruster, creating the bright annular discharge in the cavity. Measured ion energy distribution functions contain the energetic ions having the maximum potential close to the anode potential, demonstrating the ion acceleration from the annular cavity and the neutralization by the electrons in the rf plasma source. [ABSTRACT FROM AUTHOR]

Metal-bonded magnetic composites (MBMCs) present a promising alternative to dense sintered magnets, particularly for intricate components. Compared to polymer-based bonded magnets, MBMCs have wider applicability in harsh environments. In this paper, we demonstrate a solid-state shear-based manufacturing technique to introduce localized magnetization into a paramagnetic aluminum matrix by embedding SmCo5 permanent magnet particles. Our magnetic composites display hard magnetic behavior with a coercivity of 13 kOe and a remanent magnetization of 4.32 emu/g. In addition to magnetization, we also report a 9% improvement in Young's modulus. Despite the local temperature rise during processing, the magnetic phases didn't decompose into unwanted phases, preserving the composite's hard magnetic properties. Creation of an interfacial metallurgical bond with the matrix ensured the suitability of the composites for structural applications. Our study investigates the mechanical, and functional properties of composites, paving the way for lightweight structural magnetic composites with a transformative potential in the aerospace, nuclear, and automotive applications. This work underscores the potential for further optimization and development to drive innovations in magnet and equipment design. [ABSTRACT FROM AUTHOR]

Addressing the challenges of significant speed overshoot, stability issues, and system oscillations associated with the sliding mode control (SMC) strategy in maximum power point tracking (MPPT) for permanent magnet synchronous wind power systems, this paper introduces a fuzzy sliding mode control (FSMC) method employing an innovative exponential convergence law. By incorporating a velocity adjustment function into the traditional exponential convergence law, a novel convergence law was designed to mitigate oscillations during the sliding phase and expedite the convergence rate. Additionally, a fuzzy controller was developed to implement a fuzzy adaptive SMC strategy, optimizing the MPPT for permanent magnet synchronous wind power generation systems. Simulation results indicated that this approach offered a faster response and superior interference rejection capabilities, compared to conventional and modified SMC strategies. The improved FSMC strategy demonstrated a swift, dynamic response and excellent steady-state performance, improving the efficiency of MPPT, thus confirming the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Bulk high-temperature superconductors (HTSs) such as REBa2Cu3O7−x (REBCO, RE = Y, Gd) are commonly used in rotationally symmetric superconducting magnetic bearings. However, such bulks have several disadvantages such as brittleness, limited availability and high costs due to the time-consuming and energy-intensive fabrication process. Alternatively, tape stacks of HTS-coated conductors might be used for these devices promising an improved bearing efficiency due to a simplification of manufacturing processes for the required shapes, higher mechanical strength, improved thermal performance, higher availability and therefore potentially reduced costs. Hence, tape stacks with a base area of (12 × 12) mm2 and a height of up to 12 mm were prepared and compared to commercial bulks of the same size. The trapped field measurements at 77 K showed slightly higher values for the tape stacks if compared to bulks with the same size. Afterwards, the maximum levitation forces in zero field (ZFC) and field cooling (FC) modes were measured while approaching a permanent magnet, which allows the stiffness in the vertical and lateral directions to be determined. Similar levitation forces were measured in the vertical direction for bulk samples and tape stacks in ZFC and FC modes, whereas the lateral forces were almost zero for stacks with the REBCO films parallel to the magnet. A 90° rotation of the tape stacks with respect to the magnet results in the opposite behavior, i.e., a high lateral but negligible vertical stiffness. This anisotropy originates from the arrangement of decoupled superconducting layers in the tape stacks. Therefore, a combination of stacks with vertical and lateral alignment is required for stable levitation in a bearing. [ABSTRACT FROM AUTHOR]

To address the problem of energy wastage in traditional long-distance belt conveyors with low carrying capacity due to the excessive power installation of a single drive motor, a model of a distributed permanent magnet direct drive belt conveyor driven by multiple small power motors is proposed. A power regulator based on material carrying capacity is designed for energy saving. The minimum number of motors is set as the adjustment target. The number of running motors is adjusted, and the remaining motor power is distributed. The speed constraints of multiple motors are analyzed. The speed difference between adjacent motors is used as feedback to construct a ring coupling speed controller. This realizes the coordinated operation of the distributed permanent magnet direct drive belt conveyor. Co-simulations with AMESIM (version 2020.1) and MATLAB (version 2019b) are conducted to verify the system's stability. The power regulator optimizes motor distribution under varying conditions, reducing operational losses. The experimental results confirm the effectiveness of the proposed power control strategy. [ABSTRACT FROM AUTHOR]

In the realm of electric machines, there has been an increasing interest in multiphase (greater than three-phase) and hybrid excited machines. The benefits of multiphase machines include improved power density, efficiency, reliability, and fault tolerance, while for hybrid electric machines, the literature offers a variety of topologies, each with its own advantages and disadvantages. In essence, the term hybrid for electric machines is used when there is more than one source of excitation, e.g., permanent magnet (PM) excitation combined with or assisted by wound field (WF) excitation. This paper presents an extensive review of the latest topologies in hybrid machines. It explores fundamental principles, multiphase winding, and the advantage of multiphase over three-phase, as well as a comparison of ripple in the DC link for different numbers of phase winding. Additionally, this review discusses applications across industries, including automotive, aerospace, marine, and renewable energy systems. This paper later studies the motoric and generator modes of hybrid machines while considering the machine characteristics in both of these modes. [ABSTRACT FROM AUTHOR]

Flywheel energy storage systems (FESSs) are widely used for power regulation in wind farms as they can balance the wind farms' output power and improve the wind power grid connection rate. Due to the complex environment of wind farms, it is costly and time-consuming to repeatedly debug the system on-site. To save research costs and shorten research cycles, a hardware-in-the-loop (HIL) testing system was built to provide a convenient testing environment for the research of FESSs on wind farms. The focus of this study is the construction of mathematical models in the HIL testing system. Firstly, a mathematical model of the FESS main circuit is established using a hierarchical method. Secondly, the principle of the permanent magnet synchronous motor (PMSM) is analyzed, and a nonlinear dq mathematical model of the PMSM is established by referring to the relationship among d-axis inductance, q-axis inductance, and permanent magnet flux change with respect to the motor's current. Then, the power grid and wind farm test models are established. Finally, the established mathematical models are applied to the HIL testing system. The experimental results indicated that the HIL testing system can provide a convenient testing environment for the optimization of FESS control algorithms. [ABSTRACT FROM AUTHOR]

Permanent magnetic levitation (PML) is an innovative levitated transportation system. Examining the dynamic response of PML vehicles based on their permanent magnetic track relationship is crucial for assessing system stability and safety. In this regard, this study first established the multibody dynamic equations of PML vehicles according to their magnetic trajectory relationship. A coupled dynamic model was then developed within the Simulink environment; finally, the dynamic characteristics of the PML vehicle engineering machine were analyzed. The simulation results were in good agreement with the experimental results, further verifying the accuracy and reliability of the dynamic model. The results show that the bogie keeps a certain attitude for a long time at a low speed. The vibration acceleration of the bogie and body was much smaller than the corresponding dynamic evaluation criteria. Notably, the spectral analysis of the vertical vibration acceleration of the body shows that the axis distance of the PML, lateral and axial distances of the second suspension system, and lateral distance of the guide wheels have a significant effect on the body vibration. This study provides a relevant reference for the engineering application of PML vehicles. [ABSTRACT FROM AUTHOR]

Intraluminal epithelial abnormalities, potential precursors to significant conditions like cancer, necessitate early detection for improved prognosis. We present a motor-free telerobotic optical coherence tomography (OCT) endoscope that offers high-resolution intraluminal imaging and overcomes the limitations of traditional systems in navigating curved lumens. This system incorporates a compact magnetic rotor with a rotatable diametrically magnetized cylinder permanent magnet (RDPM) and a reflector, effectively mitigating thermal and electrical risks by utilizing an external magnetic field to maintain temperature increases below 0.5 °C and generated voltage under 0.02 mV. Additionally, a learning-based method corrects imaging distortions resulting from nonuniform rotational speeds. Demonstrating superior maneuverability, the device achieves steerable angles up to 110° and operates effectively in vivo, providing distortion-free 3D programmable imaging in mouse colons. This advancement represents a significant step towards guidewire-independent endomicroscopy, enhancing both safety and potential patient outcomes. Abnormalities in intraluminal epithelium can point to serious diseases. Here, the authors present a mono-magnet actuated OCT endoscope that enables high-resolution, programmable imaging in complex lumens without local heat effects, with safety and quality in thermoelectrically sensitive scenarios. [ABSTRACT FROM AUTHOR]

This paper investigates the thermal operating capability of an interior permanent magnet synchronous machine. An iterative workflow is presented, combining electromagnetic modeling, control, power‐loss modeling, and thermal modeling to identify maximum thermal stable operating points. Special attention is given to the critical temperatures of winding and permanent magnets. A nonlinear reduced order model based on finite element method model was used to simulate the system, including an inverter model with space vector pulse width modulation in combination with field‐oriented control. Furthermore, an advanced iron core loss model and thermal lumped parameter model were employed. The presented approach allows for evaluating losses and their impact on steady‐state temperatures. The obtained results highlight the significant influence of space vector pulse width modulation on iron core losses and the importance of considering both advanced power‐loss models and adequate thermal models when analyzing the machine's thermal state. This research emphasizes the concept of a thermally stable envelope, providing a comprehensive understanding of the thermal boundaries under various operating conditions. [ABSTRACT FROM AUTHOR]

Permanent magnet coupling (PMC) generates a large amount of thermal energy due to the eddy current induced in the metal isolation cylinder, resulting in performance degradation. The magnetic-thermal-mechanical coupling analysis has an important impact on the design and operation of PMC devices. In this paper, the Maxwell equations are solved based on the separated variable method; the 3D eddy current loss and magnetic torque equations are proposed; and the electrical conductivity, the convective heat transfer coefficient, and the magnetic-thermal-mechanical properties of PMC are presented. The 3D analytical coupling model calculates the temperature field and presents an uneven distribution of temperature along the coolant flow direction, and it then obtains a more precise magnetic field and torque under various temperatures. Furthermore, the working conditions such as rotor speed, coolant flow rate, and applied load are taken into consideration in the 3D analytical model. The results show that the eddy current loss is proportional to the square of the speed. With an increase in the load, the eddy current decreases. However, with an increase in the coolant flow, more eddy current loss would be produced, but the generated heat would be taken away by the increased coolant flow, resulting in a decrease in the temperature. The 3D analytical coupling model results are in good agreement with the experimental data, which is helpful to the design and optimization of the PMC system. [ABSTRACT FROM AUTHOR]

Relativistic backward wave oscillators (RBWOs) have the characteristics of high power and high repetition rate. Reducing the magnetic field strength and the weight of the external permanent magnet (PM) is a significant development direction of RBWOs. In previous research, an X-band RBWO enclosed with a PM has achieved a power efficiency of 50%. However, the PM used in these papers requires a magnetic field magnitude of over 0.68 T, which leads to a weight exceeding 400 kg. The RBWO designed in this paper operates in coaxial TM01 mode, and the radial distance between its cathode and the surface of the slow wave structures reaches 7 mm. Under the condition of a low magnetic field, this design can provide a wide electron beam channel to avoid the rubbing of the electron beam envelope on the inner and outer conductors. Particle-in-cell simulation results have demonstrated that this RBWO achieves an output microwave power of 3 GW with a power efficiency of 50% enclosed in a PM with a magnetic field strength of 0.43 T and a weight of 74 kg. [ABSTRACT FROM AUTHOR]

In the article is implemented interresonance mechanical oscillating system vibrational technological equipment, which provides using two continuous of connected area successively to working body vibrational machines. Disturbance of the structure is carried out by applying a variable-sign power supply voltage to the reactive continuous section, where in interaction with the magnetic field from the permanent magnets, a variable-sign disturbance force occurs. Inertial forces from the reactive continuous section are transferred to the intermediate continuous section, which resonates with the working body. In fact, an interresonance discrete-continuous oscillating system is obtained in which there are no springs. The function of springs is performed by bodies with distributed parameters that have elastic properties. Based on the Krylov-Duncan functions, a system of equations was formed that establishes the amplitude of oscillations of the working body. The amplitude-frequency characteristic of the discrete-continuous system was studied, which confirms the possibility of creating interresonance oscillating systems of vibrating technological equipment without springs. [ABSTRACT FROM AUTHOR]

To achieve compactness and miniaturization for high-power microwave devices, this paper proposes an X-band permanent magnet-packaged coaxial relativistic klystron oscillator (RKO) with a novel diode structure featuring a stair-step cathode. First, by adopting a large-radius anode structure, the emission of beam currents from the side of the cathode surface is diminished, thereby reducing the proportion of the backward current in the beam current from 10% to 7%. Second, a stair-step cathode is used to inhibit the return flow of electron beams from striking the anode and generating plasma. Concurrently, a radially non-uniform coaxial resonant cavity structure is employed to enhance the fundamental wave modulation depth of the electron beam and improve the beam–wave interaction's efficiency. The experimental results show that the novel device outputs a microwave with a frequency of 9.46 GHz and a pulse width of 55 ns. It generates a power output of 1.5 GW with an efficiency of approximately 30.5%, in the case in which the diode voltage is 505 kV, the beam current is 9.7 kA, and the guiding magnetic flux density is 0.4 T. This novel structure surpasses traditional diode configurations by enhancing the beam-to-wave conversion efficiency by roughly 10%, thereby offering substantial support for the compactness and miniaturization of RKO. [ABSTRACT FROM AUTHOR]

The fluctuations in the plasma potential ( V s ̃ ) and electron density ( N e ̃ ) are measured in the steady-state dipole plasma confined in a spherical vacuum chamber using a single permanent dipole magnet. Measurements are made from a radial distance r = 0.5–17 cm, from the surface of the magnet in the equatorial (θ = 90 °) and polar (θ = 180 °) directions, using a 4-pin probe setup, and have been characterized by power spectra, cross-phase, cross-coherence, induced transport, and energy spectra. The fluctuations are stronger near the surface of the dipole magnet for θ = 90 ° , thereafter their magnitude decreases gradually with the radial distance. However, a peaked profile of potential fluctuations with the peak around r = 9 cm is observed for θ = 180 °. The locations of strong fluctuations are around the locations of smaller values of the electron neutral collision frequency. Frequency-resolved power spectra show that the fluctuations in the dipole plasma, predominantly, belong to the very low-frequency range. The values of cross-phase (≤ 45 °) and | V s ̃ / T e | / | N e ̃ / N e | ≤ 1 indicate the presence of drift wave instability in both planes, where T e and N e are equilibrium values of the electron temperature and density. The radial variation of fluctuation-induced electron flux ( Γ r ) verifies the "inward diffusion" of electrons in the equatorial plane. [ABSTRACT FROM AUTHOR]

To address the harmonic issues associated with the pulse width modulation (PWM) method, this article introduces variable delayed time (VDT) space vector pulse width modulation (SVPWM) with double central symmetry for dual three-phase permanent magnet synchronous machines (DTP-PMSMs). Firstly, the switching sequence of four traditional vectors undergoes double central symmetry, resulting in the doubling of the frequency of the phase voltage. This alteration eliminates harmonics occurring at odd multiples of carrier frequency. Additionally, the adopting of a single null vector minimizes the additional switching times introduced by the double central symmetry. Subsequently, VDT-SVPWM is employed to further suppress the harmonics at the even multiples of carrier frequency. The implementation of the proposed double central symmetry method involves directly utilizing the calculated duty cycle of the traditional four vectors. Moreover, integrating VDT-SVPWM with the double central symmetry method is straightforward. Simulation and experimental results validate the efficacy of the proposed method in suppressing harmonics and mitigating vibrations in the DTP-PMSM. [ABSTRACT FROM AUTHOR]

The PWM voltage pulses output by the inverter reaches the stator winding of the wind turbine generator through the cable. Due to the impedance mismatch between the motor and the cable, the voltage at the motor end rises under the action of the circuit wave process; on the other hand, electromagnetic oscillation occurs within the motor winding. Higher overvoltage is generated under the combined effect of both, which greatly accelerates the aging and breakdown of the insulation layer of the permanent magnet synchronous wind turbine. In this paper, a three-dimensional electromagnetic model of the permanent magnet synchronous wind turbine generator is established. The distribution circuit parameters of the stator winding of the permanent magnet machine are calculated using the finite element method, and its circuit model is based. The voltage distribution of the stator winding under different PWM excitations is investigated by simulation software, and the effects of the time of the rising edge and the pulse width of the PWM pulse on the stator winding voltage to ground and the turn-to-turn voltage distribution are studied. The results show that the effect of the rising edge time is larger when the rising edge time is shorter, the maximum voltage to ground occurs in the first coil, and the amplitude can be up to 1.5 times of the output voltage. When the rising edge time is longer, the maximum voltage to ground occurs in the end coil, and the amplitude is slightly higher than the output voltage. The trend of turn-to-turn voltage variation is similar for different rising edges; only the maximum turn-to-turn voltage amplitude is different. Pulse width has a small effect on overvoltage and only occurs when the pulse width is less than 10 μs. The research results of this paper are of great significance in revealing the aging and breakdown mechanism of the generator stator insulation, as well as the insulation coordination and design. [ABSTRACT FROM AUTHOR]

Multifunctional stretchable rubber composites are gaining attention due to their unique electrical, mechanical, and magnetic properties. However, their high production costs pose economic challenges. This study explores the use of cost-effective metal powders—iron, aluminum, and their 1:1 (vol/vol) hybrid filler—in styrene–butadiene rubber composites, varying from 10 to 20 vol%. The effects of these metal particles on the mechanical, electrical, morphological, and swelling properties were investigated. Metal particles generally act as non-reinforcing fillers but can significantly enhance the mechanical modulus, electrical, and magnetic properties based on the filler structure and the filler–rubber interactions. Iron-based composites exhibit significant electrical conductivity and excellent magnetic properties. Aluminum enhances the modulus, while the combination yields average mechanical properties with added magnetic characteristics. Iron demonstrates higher reactivity with sulfur-based crosslinking ingredients, adversely affecting the rubber matrix's crosslinks, as shown by swelling tests. This reactivity is attributed to iron's transition metal characteristics. At 20 vol%, iron-filled composites display the highest magnetic anisotropic effect on toughness (~25%) under a magnetic field by permanent magnets and excellent electrical conductivity (1.5 × 10−2 S/m). While iron significantly boosts the electrical and magnetic properties, higher filler amounts degrade the mechanical properties. These composites are currently suitable for electrical and smart mechanical applications, but incorporating reinforcing fillers could enhance their robustness for broader applications. [ABSTRACT FROM AUTHOR]

The accumulation of space debris is an ever-increasing problem. Systems that can reliably de-orbit (i.e., decrease the time to re-entry for) an inactive resident space object (RSO) are highly sought after. In this paper, we investigate the feasibility of utilizing the forces owing to the interaction of Earth's magnetic field with a permanent magnet that has been attached to an RSO in low Earth orbit. We consider an actively controlled permanent magnet that is optimally oriented to remove energy from the system, and the most favorable magnet-to-RSO mass ratio. We show that, even under these best-case assumptions, the interaction between a permanent magnet and Earth's magnetic field is not a viable means of de-orbiting an RSO. [Display omitted] • The interaction between a permanent magnet and Earth's magnetic field can be used to remove energy from an object in orbit. • The orientation of the permanent magnet can be controlled to optimize the energy loss. • This optimal orbital energy loss is not sufficient to de-orbit the object in a reasonable amount of time. • Interaction between a permanent magnet and Earth's magnetic field is therefore not a viable means for de-orbiting space debris. [ABSTRACT FROM AUTHOR]

In this paper, an innovative hamburger-shaped eddy current damper (HSECD) is presented to mitigate the responses of civil structures subjected to wind excitations. The damper's capacity to dissipate energy is significantly enhanced through a two-phase configuration of permanent magnets (PMs) and two transmission devices: a ball-screw assembly and a bevel gear group. The improved eddy current damper (ECD) solves the problem that the low damping density of traditional ECDs hinders their application to the field of vibration control for civil structures. First, the construction details of this novel HSECD are elaborated, and its principle is discussed through theoretical analysis and numerical simulation. Subsequently, a prototype of the HSECD was fabricated, and cyclic tensile–compressive tests were conducted to investigate its mechanical performance. Furthermore, the temperature effect on the damper's maximum output force was analyzed, and more than 10% performance degradation was detected in tests with a continuous loading of 1,250 s, while the damper performance quickly reached a steady state after a certain decline. A theoretical model of the HSECD was then established to simulate its hysteretic characteristics, and the accuracy was verified by comparing it with the test data, where their energy error was only 1.9%. Finally, the application of the HSECD to both a single-degree-of-freedom (SDOF) simplified system and a jacking engineering system demonstrates its excellent control performance because the reduction ratios of their peak displacement were as high as 31.1% and 40.9%, respectively. These results highlight the significant practical value of the HSECD in mitigating the wind-induced vibrations for engineering structures. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous linear motor (PMSLM) parameters are susceptible to temperature changes and motor aging, which can result in inaccurate models and reduced control accuracy. Therefore, PMSLM parameters must be monitored accurately. In this study, a back-propagation (BP) neural network is used to identify the resistance, inductance, and flux linkage parameters of a PMSLM, and a genetic algorithm (GA) is employed to optimize the identification system. A full-rank model is established, and the BP neural network parameter identifier is used to realize the multiparameter discrimination, and the GA is employed to optimize the network parameters of the identifier model to improve its training speed and accuracy. A GABP-based multiparameter identification system for a PMSLM is built, and the experiment results show that the GABP parameter identifier can accurately identify the four parameter values of the PMSLM simultaneously. [ABSTRACT FROM AUTHOR]

The motor parameters of permanent magnet synchronous motor (PMSM) can be mismatched in operation due to temperature variations and magnetic saturation. The parameter mismatch leads to a significant decrease in the robustness of traditional deadbeat predictive current control (DPCC), which leads to issues such as current static error and motor vibration noise. In this paper, a model-free predictive current control (MFPCC) method based on an improved sliding mode disturbance observer (SMDO) was proposed. The method estimated the total disturbance of the system using the improved SMDO, which could effectively suppress sliding mode chattering and accelerate the convergence speed of current errors. Subsequently, the predicted control voltage was calculated using a hyper-local model and compensated for the time delay. The experimental results demonstrated that the improved MFPCC-SMDO method generated lower motor noise compared to the traditional DPCC method when the controller's inductance parameters are mismatched. [ABSTRACT FROM AUTHOR]

The synthesis of a strontium hexaferrite magnet is studied using in situ synchrotron powder X‐ray diffraction (PXRD) with a 16‐ms time resolution. The precursor material is cold compacted shape‐controlled goethite and strontium carbonate. The time evolution of the phases is modeled with sequential Rietveld refinements revealing that strontium hexaferrite forms within seconds at ≈1173 K. Texture analysis is performed on selected PXRD frames throughout the experiment, and the preferred orientation introduced by cold‐pressing goethite prevails through the iron oxide phase transitions (goethite → hematite → strontium hexaferrite). Electron backscatter diffraction (EBSD) data on the final pellet confirms the preferred orientation observed with PXRD. The resulting magnet has respectable magnetic properties, considering the simplicity of the preparation method, with an energy product (BHmax) of 18.6(8) kJ m−3. [ABSTRACT FROM AUTHOR]