Magnetic Arrangement Research Articles

Optimizing geometric parameters for the rotor of a traction synchronous reluctance motor assisted by partitioned permanent magnets

This paper considers partitioning parameters and the mutual arrangement of magnets in the rotor of the traction synchronous-jet engine with permanent partitioned magnets. The synthesis of geometrical parameters for the rotor of a synchronous reluctance motor with partitioned permanent magnets was proposed on the basis of solving the problem of conditional optimization. To solve the synthesis problem, a mathematical model has been built to determine the electromagnetic momentum of a synchronous reluctance motor with partitioned permanent magnets. It is based on the calculation of the electromagnetic momentum of the engine employing the results of a finite-element analysis of the magnetic field in the flat-parallel statement of the problem. The model is implemented in the finite-element analysis FEMM environment and makes it possible to determine the electromagnetic momentum of the engine with a variety of partitioning of permanent magnets. As an analysis problem, it is proposed to use a mathematical model of the magnetic field of the engine. The problem of conditional optimization of the rotor of a synchronous reluctance motor was stated according to the geometric criteria of the rotor. Restrictions are set on geometric, strength indicators, as well as on the level of electromagnetic momentum. The chosen optimization method is the Nelder-Mead method. Based on the results of solving the problem of synthesizing parameters for the partitioned rotor of the traction motor of trolleybus wheels, it was established that the volume of permanent magnets was reduced by 2.27 times compared to the base structure; their optimal geometric dimensions were determined (5 mm, 5.2 mm, and 5 mm), as well as the distance between them, 17.8 mm and 15.3 mm, and the engine load angle, which is 121.12 electrical degrees. Based on the results of solving the problem of synthesizing parameters for the partitioned rotor of a trolleybus traction synchronous reluctance motor, its optimal geometric parameters have been determined

The effect of point defects formation on the magnetic properties of Fe2MnGa: A first-principles study

Density functional theory-based calculations have been performed to investigate the effect of point defects formation on the ground-state magnetic properties of the Fe2MnGa compound. The calculated formation energies for vacancies, antisite and exchange defects point out which defects have the most probability to be formed. The density of states calculations denotes that the formation of a point defect in Fe2MnGa induces changes in the electronic structure. As a result of these changes almost all defect structures studied show an increase in the total magnetic moment relative to that of the ideal compound. Great modifications are also observed in the values of the magnetic moments of Fe and Mn atoms. Several defect structures have a complicated magnetic arrangement (antiferromagnetic or ferromagnetic) of the atomic magnetic moments depending on the site's position due to the atomic disorder.

Structural Analysis of Loosely Coupled Transformers with FEA-Aided Visualization for Wireless Power Transfer Systems against Misalignment Tolerance

The main problems of automotive wireless power transmission (WPT) systems include a weak misalignment tolerance are urgently required to be solved through the design of the loosely coupled transformer. In this paper, an analysis methodology based on finite element analysis (FEA) visualization is proposed, it is easy-implemented and straightforwardly explains this complex electromagnetic phenomenon. Firstly, the transformer structures with different winding and magnetic core arrangement were modeled by FEA in both 3-D and 2-D visualizations. The distribution of space coupling magnetic fields and leakage fields was analyzed by ANSYS Electronics. The key parameters that have a great influence on the coupling performance were delicately chosen. Then, the quantitative analysis of these key parameters and coupling performance against misalignment tolerance is presented. The numerical statistical result shows that the maximum coupling coefficient of the three structures that have been optimized consistently appears when the two key parameters, the inner and outer diameter, account for about 20% and 60% of the whole dimension of the transformers. A new transformer with a solenoid-shaped structure and strong misalignment tolerance was proposed based on the analysis methodology and the FEA results of the three structures. The delivered power and transfer efficiency under different misalignments of the new structure were analyzed via an FEA-aided joint method as well. The relationships among misalignment tolerance, key structural dimensions and coupling coefficients for all these structures were comprehensively investigated, which provide guidance for the subsequent multi-objective optimization strategies.

Magnetic Resonance Studies of Hybrid Nanocomposites Containing Nanocrystalline TiO2 and Graphene-Related Materials

Nanocomposites based on nanocrystalline titania modified with graphene-related materials (reduced and oxidized form of graphene) showed the existence of magnetic agglomerates. All parameters of magnetic resonance spectra strongly depended on the materials’ modification processes. The reduction of graphene oxide significantly increased the number of magnetic moments, which caused crucial changes in the reorientation and relaxation processes. At room temperature, a wide resonance line dominated for all nanocomposites studied and in some cases, a narrow resonance line derived from the conduction electrons. Some nanocomposites (samples of titania modified with graphene oxide, prepared with the addition of water or butan-1-ol) showed a single domain magnetic (ferromagnetic) arrangement, and others (samples of titania modified with reduced graphene oxide) exhibited magnetic anisotropy. In addition, the spectra of EPR from free radicals were observed for all samples at the temperature of 4 K. The magnetic resonance imaging methods enable the capturing of even a small number of localized magnetic moments, which significantly affects the physicochemical properties of the materials.

Design aspects for in-vehicle IPM motors for sustainable mobility

In battery electric vehicles, permanent magnet synchronous IPM motors are gaining more and more ground due to their high power density and high-efficiency operation. Many research examine their specific characteristics. In order to reach a desired total torque, low torque ripple, high efficiency, many pre-plannings have to be executed. The modern age engineering industry can rely much on complex simulation software, such as MotorAnalysis – PM. In this paper, an initial IPM motor design with delta magnet arrangement was created for vehicle application. This study had a strong focus on finding correlation between rotor layout arrangement and crucial motor operationial attributes, such as: torque components, torque ripple, cogging torque and efficiency. Time stepping magnetostatics FE and time stepping transient FE simulations were used. Each arrangement changement held its own simulation file, thus the effect of each change could have been separately examined. Arrangements, where the distance between magnets is smaller, resulted in greater torque and efficiency. Usage of enlarged magnets had the same results. Size should be increased and distance should be decreased with care to avoid a growth in torque ripple.

Study of the spectroscopic, magnetic, and electrical behavior of PVDF/PEO blend incorporated with nickel ferrite (NiFe2O4) nanoparticles

Pure nickel ferrite nanoparticles (NiFe2O4 NPs) were prepared by the solvothermal method. Different concentrations of NiFe2O4 were added to PVDF/PEO blend to prepare the PVDF/PEO-NiFe2O4 nanocomposite films. The films were characterized using different techniques in detail. Pure NiFe2O4 NPs images have a semispherical shape and roundness of the edges, with average particle size ~ 4.3–8.8 nm, and polycrystalline structure. Pure NiFe2O4 NPs show that micrometrical agglomeration suggests the presence of pore-free crystallites on the surface. The spectroscopic techniques such as XRD, FTIR, and UV–visible have confirmed the interaction between PVDF/PEO and NiFe2O4 NPs. Still, the nanocomposites exhibit a smooth surface with typical spherulitic clusters revealing the semi-crystalline structure of the PVDF/PEO-NiFe2O4 nanocomposites. The values of ε′ and ε″ were increased as an increase of NiFe2O4 due to the high value of dielectric permittivity of NiFe2O4. The appearance of semi-circles in the plot of M″ with Log confirms the single phase of the samples. The dielectric measurements show that M′ is inversely proportional to ε′. At higher temperatures, M′ levels off at frequencies higher than those at lower temperatures because the relaxation processes were spread over a range of frequencies. The values of saturation magnetization of PVDF/PEO-NiFe2O4 films were linearly increased as an increase of NiFe2O4 indicates improvement in the magnetic vector arrangement. Due to the enhancement of the magnetic properties, they can further exploit the films for magnetic applications.

Snap-through triboelectric nanogenerator with magnetic coupling buckled bistable mechanism for harvesting rotational energy

We propose a snap-through triboelectric nanogenerator with magnetic coupling and buckled bistable mechanism to harvest rotational energy (ST-RTENG). The buckled bistable beam generates convex and concave snap-through under magnetic excitation, which can significantly increase the contact force of the functional materials of triboelectric nanogenerator (TENG), thereby significantly improving the electrical output. By adopting a magnetic coupling non-contact energy transfer mechanism, the drive part and the electromechanical conversion part are easily physically separated, which improves the robustness of the system in the harsh environment. The electromechanical coupling dynamic model of the system is established and verified by experiments. The different modes and key parameters of the magnet arrangement are investigated. The ST-RTENG with two pairs of magnets with staggered poles has a maximum voltage of 1235 V at a rotating speed of 150 r/min and a maximum average power of 778 μW at a rotating speed of 800 r/min. The prototype can light up more than 1000 LEDs under low speed excitation, and realize self-powered temperature monitoring and wireless transmission. The rotational energy harvester with magnetic coupling buckled bistable mechanism proposed in this paper can be used for wind energy harvesting in the field environment, self-powered state monitoring of the pressure pipelines, and other applications that require isolation of external excitation and electromechanical conversion components.

On the Design and Topology Selection of Permanent Magnet Synchronous Generators for Natural Impedance Matching in Small-Scale Uncontrolled Passive Wind Generator Systems

Small-scale uncontrolled passive wind generator systems are an attractive solution for rural energy generation because of the system’s reliability and low cost. However, designing these uncontrolled wind generators for good power matching with the wind turbine is challenging and often requires external impedance matching. In this paper, permanent magnet generators with different stator and rotor structures were investigated and designed to increase the generator’s synchronous inductance for a natural impedance matching. For the design methodology, multi-objective optimisation was used to design the generators for near-maximum turbine power matching, whereby internal impedance matching was reached as much as possible. It was shown that altering the placement and orientation of the permanent magnets in the rotor is a viable method to achieve the desired impedance matching; however, these generators do not have the best performance. It was found that the surface-mounted permanent magnet generator with semi-closed slots was the optimum topology. An optimised generator prototype was tested for the experimental validation. All designs were verified by comparing the results of 2D and 3D finite-element analysis.

Heat transfer enhancement of Fe 3 O 4 ‐water nanofluid by the thermo‐magnetic convection and thermophorestic effect

The promotion of the heat transfer by ferro-nanofluid under a magnetic field has caught more extensive attention in the field of nuclear industry and energy engineering. Firstly, a modified model based on the Buongiorno model was proposed to investigate the heat transfer considering the Kelvin force in the presence of an inhomogeneous magnetic field to elevate the heat transfer performance of nanofluid using thermomagnetic convection. Secondly, the influence of Kelvin force, thermophoresis, and Brownian motion of nanoparticles on the heat transfer at a moderate Reynolds number was investigated. The numerical results indicate that the chaotic convection induced by the Kelvin force and the thermophoretic effect are much important factors. Thirdly, the numerical results demonstrate that the NSN and NSN/SNS arrangements of magnets should be the preferential selection. Besides, the more powerful magnetic field and greater volume fraction of nanoparticle can produce better heat transfer performance. Finally, the discussions on the underneath mechanisms for heat transfer augment are conducted, and it can be concluded the thermomagnetic convection induced the combination of the magnetic effect and thermophoretic effect may be the key mechanism.

On the anhysteretic magnetization of soft magnetic materials

Electrical steels are still the materials of choice for large-scale transformers and most electric motors. Yet, they may present a nonhomogeneous magnetic nature which prevents describing accurately their anhysteretic magnetization with the Langevin-Weiss model. Although interpolation and extrapolation methods may be used to model any anhysteretic curve, a simple and physically-based model would be of great value for fundamental and applied research. Inspired in the law of partial volumes for gas mixtures, we proposed a law of partial magnetizations for magnetic mixtures. In a two-component system, the model leads to the double Langevin-Weiss function. We also introduced a graphical method and a fitting approach to analyze and model anhysteretic magnetization curves. A semi-log magnetization derivative plot is central to this end. We validated our strategy through well-motivated examples using published data on soft magnets. The single Langevin-Weiss function provided an accurate description of the magnetization of isotropic and anisotropic magnetically homogeneous materials: a soft ferrite and a nanocrystalline alloy, respectively. For modelling a magnetization transverse to the material’s preferred direction, the key is to allow a negative molecular field constant. The double Langevin-Weiss function was suitable for less homogeneous materials, such as a grain-oriented electrical steel magnetized along the rolling direction and a non-oriented electrical steel. Moreover, a highly-grain-oriented electrical steel magnetized transverse to the rolling direction, which exhibits a constricted hysteresis loop, could be modeled in excellent agreement with data. The key for the latter, has been to allow an antiparallel arrangement of the mean magnetization of both components.

Magnetic docking stations for remotely powered light emitting diodes

Light emitting diodes (LEDs) are efficient light sources which due to low power consumption often are considered for demonstrations of wireless energy transmission. It is often not only necessary to power these light sources wirelessly, but also to ensure that they conveniently dock at the correct position as effortlessly as possible without the need for chemical adhesives or mechanical attachment. In the current work a passive magnetic docking system which aids attachment of wirelessly powered LEDs is proposed. The system utilizes electromagnetic induction of nearby coils to power the LED. The spatial range of the magnetostatic interactions is controlled by the specific magnet arrangement used, such that the light is turned on either before or after docking is initiated. The constant and time-varying magnetic fields occupy the same volume, thus allowing the presenter to demonstrate the difference between magnetostatic interactions locking the LED in place and electromagnetic induction turning the LED on. It is demonstrated that the proposed system works well for light signaling in salt water, and may find use in wireless underwater communication.

Feasibility analysis of novel Maglev EDM by comparing with conventional micro EDM

EDM is the most popular unconventional machining process. The present technology of EDM consists of a pulsed or capacitive type power supply in which the pulsed type power supply is more popular and effective. The following essential component of an EDM is its servo mechanism, which controls the gap between the electrodes and maintains the gap voltage. A low machining speed, complex power supply, and servo mechanism increase the cost of machining and the maintenance cost of an EDM machine. To resolve the above issues from the EDM, a novel servo mechanism has been developed, which is simple in design and low in cost and has the capacity to use direct current as a power source. The current work elaborates a brief description of the novel servo mechanism and its feasibility analysis. Pure DC power is employed with the conjunction of Maglev lucidity to refine the shortcomings of conventional micro EDM. The novel technology addresses the prime concerns of conventional micro EDMs and deficiencies such as the delayed response of mechanical actuators and a servo mechanism. The novel technology uses the logical arrangement of permanent magnets and electromagnets to address inadequacies such as short circuiting and arcing. The work outlook is to establish the viability of the novel Maglev EDM by a comparison with a similar range of parameters. The results on the novel technology showed an improved material removal rate (MRR), which was in the range of 76.6 μgm/min, whereas the specific energy and surface roughness were 33.4 Joule/microgram and 4.3 μm, respectively, while machining commercially pure titanium.

A novel core structure of inner-ringed multi-pitch rods for lightweight induction coil sensor design

A novel inner-ringed multi-pitch rods core structure for lightweight induction coil sensor design, in which the higher-permeability magnetic rods are located in the inner ring of the induction coil, is proposed. The abbreviation for the novel core structure is “IRMPR core structure”. It is theoretically shown that the induction coil sensor sensitivity of the IRMPR core structure is equal to that of the single-rod solid structure. Compared with the traditional single-rod solid magnetic core structure, the mass of magnetic core of the IRMPR core structure is reduced more than 28%, however, the sensor sensitivity is not sacrificed. Besides, the performance of the IRMPR core structures with permalloy and Zn-Mn alloy magnetic cores were tested under 500Hz and 1–22kHz band conditions, and the performance was improved compared with the single-rod structure of the same materials. The results demonstrate the potential for IRMPR core structure application to various induction coils with different inner-ringed magnetic core materials under broadband conditions. The study also provides a method to vary the sensitivity and resonant frequency of the induction coil sensor by changing the magnetic core arrangement. Furthermore, thinner magnetic rod is more cost-effective and IRMPR core structure will be more compact for the integration of the sensors and their electronics within a single housing.

Effect of magnetic field on improvement of photocatalytic performance of V2O5/TiO2 nanoheterostructure films prepared by sparking method

Our porous V2O5/TiO2 nanoheterostructure films (with a Ti/V atomic ratio of 1:1) were fabricated via a single-step sparking method using a strong magnetic field (0.5 T) without annealing requirement for the first time. We found that the magnetic flux arrangement has effect on film crystallization, unique morphology, large specific surface area, and surprisingly controllable phase structure of the films. An amorphous TV film was transformed to the TiO2 (anatase/rutile) phase (for TVN) and V2O5–VO2 mixed-phase (for TVH) without destroying the mesopores from an annealing process. Moreover, the TVH sample able to improve the degradation rate up to 270% compared with pre-annealed TV films and up to 30% with post-annealed (400 °C) TVA films. In this paper, the influence of magnetic flux arrangement on structural, morphological, optical, and photocatalytic properties of prepared sample have been investigated and reported.

Symmetrical Resonance Mechanism of Elimination of Parasitic Torques of the Permanent Magnets Generator when Starting and Idling

. “Sticking” and vibrations of the stator of permanent magnet generators cause their increased wear, noise; also, their operation efficiency decreases. The article theoretically considers the possibility of eliminating the starting torque and oscillation of the rotation torque of the generator with permanent magnets without load due to mutual compensation of the interaction of coils with the field of permanent magnets at a certain symmetry of this field. The mentioned pheno-menon is called pi-resonance. For the specified class of model interaction potentials of the field of permanent magnets and coils, it has been shown that full compensation occurs with a certain number of coils (Ns) and magnets (Nr), while for other combinations of {Ns, Nr} the interaction is in the nature of oscillations. The corresponding tables for various classes of potentials are given which can serve as a basis for making design decisions when developing generators. Pi-resonance more probably takes place in the case of even number of stator coils and odd number of magnets, as well as with an increase in the number of stator coils. The cases of both one-sided and two-sided arrangement of the stator relative to the rotor are considered. Numerical modelling has shown that the pi-resonance is easily destroyed if the placement of magnets or coils is inaccurate, as well as by the magnet field potential symmetry breaking. An error in the angular arrangement of the coils of 1° can result in the appearance of a significant “cogging” of the rotor with energy of the order of the interaction energy of an isolated magnet – coil pair. A distortion of the symmetry of the potential yields a result similar in scale which is equivalent to the adding of a rump function with the amplitude of 10 % of the amplitude of the symmetric periodic potential. The patterns that have been discovered can be used in the design of efficient generators with reduced level of noise and vibration.

Optimization of a New Asymmetric-Hybrid-PM Machine With High Torque Density and Low Torque Ripple Considering the Difference of Magnetic Materials

In this article, a new asymmetric PM-placed rotor topology is applied to the conventional less-rare-Earth hybrid magnet machine, where such new placement of hybrid magnets can be designed to improve the torque performance effectively. Considering the difference between the two magnetic materials, the optimal placement scheme of NdFeB-PMs and ferrite-PMs in the rotor are determined by theoretical derivation of equivalent magnetic circuit and finite element analysis. Based on the torque component separation analysis using frozen permeability method, the sizes of the two magnets are preliminarily designed to improve the utilization of reluctance torque and to reduce the superposition coupling loss of PM torque. Then, based on the parameter sensitivity analysis, the proposed asymmetric-hybrid-PM machine (AHPM) is further optimized aiming at the multi-objective of torque performance and anti-demagnetization performance. Finally, a prototype motor is fabricated and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the AHPM and the proposed design method.

A Design of IPMSM for High-Power Electric Vehicles With Wide-Field-Weakening Control Region

The motor in high-power electric vehicle (EV) easily reached the voltage limit because of its large magnetic flux. Therefore, the motor should be designed so that the voltage is controlled at the limit. To achieve well voltage control condition, the interior permanent-magnet synchronous motor (IPMSM) is controlled by the field-weakening control method after the constant torque region. This is conducted by canceling the magnetic flux from the permanent magnet with the magnetic flux of the stator winding. However, this method generates many harmonics. In this article, a design that effectively controls the voltage by reducing the harmonics generated in the field-weakening control is proposed. To reduce the harmonics in the field-weakening region, the change stator and rotor design parameters and the reason for using V-type permanent magnet arrangement for high-speed operation will be elucidated.

Structural and magnetic phase transitions in Ca-substituted bismuth ferromanganites

Single-phase samples of the Bi0.85Ca0.15Fe1−xMnxO3 (0.1 ≤ x ≤ 0.5) perovskites have been prepared by a solid state reaction method and investigated using X-ray and neutron diffraction, scanning electron microscopy, piezoresponse force microscopy, magnetization, and ac susceptibility measurements. It has been found that the increase in Mn concentration induces a modification of crystal and magnetic structures giving rise to the canted antiferromagnetic polar phase → collinear antiferromagnetic polar phase → paramagnetic nonpolar phase transitions at room temperature. The appearance of spontaneous magnetization suggesting a transformation of the room-temperature antiferromagnetic structure characteristic of the ferroelectric Bi0.85Ca0.15Fe1−xMnxO3 compounds near the polar / nonpolar (R3c / Pnma) phase boundary is observed with decreasing temperature. The transformation of the magnetic arrangement can also be driven by a magnetic field application. Such metamagnetic transition can be accompanied by a large (up to ~4 emu/g for the sample with x = 0.4, when measured at T = 2 K) magnetization jump far exceeding that specific to a field-driven cycloidal order → canted order transformation in the pure BiFeO3. Nonpolar samples (x ≥ 0.45) acquire a large (a few emu/g) spontaneous magnetization at low temperature, a value that cannot be explained by a spin canting. It is shown that the low-temperature magnetic behavior of the polar and nonpolar Mn-enriched Bi0.85Ca0.15Fe1−xMnxO3 compounds can be successfully described in terms of an antiferromagnetic phase + glassy magnetic phase coexistence.

Study on the trajectory of magnetic particles in the process of magnetorheological elastomer pre-structure

Magnetorheological elastomers (MREs) is made by embedding micro/nano-sized magnetic particles in a polymer matrix. Among them, the distribution and arrangement of internal magnetic particles have an important influence on the performance of magnetorheological elastomers. Therefore, the current research mainly focuses on the influence of the distribution and arrangement of magnetic particles inside MREs on its performance. However, there are few studies on the trajectory of magnetic particles in the prefabrication process of magnetorheological elastomers. In order to solve the above problems, this paper firstly calculated the magnetic interaction force and fluid force of the magnetic particles through numerical simulation. Then, the equation of motion of the magnetic particles is obtained through the coupling of the magnetic interaction force and the fluid force. Finally, the numerical simulation is verified through experiments. In addition, it is found through numerical simulation that the trajectory of magnetic particles is determined by the direction of the magnetic interaction force, instead of its magnitude. After that, the relationship between the direction of the magnetic interaction force and the motion trajectory is analyzed and summarized. The findings of this study have a directive function in explaining the mechanism of magnetic particle arrangement.

Increasing the waste heat absorption performance in the refrigeration system using electromagnetic effect

This paper enables a simulation model for analyzing and predicting magnetic field patterns and their magnetic flux density on the pipe. Different types of arrangements of magnets like series, parallel, and Halbach arrays are utilized and their magnetic flux density and magnetic field intensity are compared on the respective pipes. Electromagnetic field simulation software calculates different magnetic fields and circuit parameters. Using this software, accurate results can be obtained such as the perfect arrangement of magnets and so on. For this experimentation, Neodymium-35 type magnets are used which have appropriate and stable magnetic strength as compared to other magnets. Diffusion absorption refrigeration systems can also be used alternatively in domestic refrigeration, thus replacing conventional vapor compression refrigeration systems. Thus, results obtained by using different magnetic arrangements will be highly beneficial to choose the proper magnetic arrangement in diffusion absorption refrigeration system for various cooling applications.