Direction Of Magnetic Flux Research Articles

A comparative study on the lamella effect and properties of atomized iron powder and reduced iron powder in Fe-based soft magnetic composites

We prepared Fe soft magnetic composites (SMCs) with lamellar structure by using the flaky Iron powder, and studied the effects of types of iron powder on the microstructure and properties of Fe SMCs. The results show that the atomized iron powder and the reduced iron powder are deformed into flaky structure after ball milling, and these flaky iron powder have greater magnetic susceptibility and eddy current diameter perpendicular to the magnetic flux direction. In addition, compared with flaky gas atomized iron powder, the flaky reduced iron powder has large aspect ratio and lower coercivity. Therefore, the Fe SMCs with flaky reduced iron powder exhibit relatively high permeability (82) and low eddy current loss (0.033 W/kg at 50 kHz, 0.05 T), which shows the potential possibility of application at high frequency.

Analysis of the air gap magnetic field in cylindrical magnetic couplings based on mathematical and finite element approach

The air gap magnetic field of a magnetic coupling plays a crucial role in the examination of its static torque and eddy current losses. Precise characterization of the air gap magnetic field is essential for ensuring the accuracy of performance assessments of the magnetic coupling. This study focuses on the cylindrical magnetic coupling as the subject of investigation, employing mathematical analysis and finite element methods to evaluate and quantify the magnetic field properties. The study establishes a mathematical model of the magnetic field of a magnetic coupling based on electromagnetic field principles and the superposition theorem. An analytical formula for the magnetic flux density distribution of the air-gap magnetic field is derived. Subsequently, a three-dimensional magnetic field finite element model is created using the finite element method to numerically calculate the air gap magnetic field and validate the analytical formula. The research also explores the periodic distribution characteristics of the magnetic field in the air gap, analyzing axial differences in magnetic flux density value and direction distribution influenced by end effects.

Phase-selective fabrication of Cu-based films by magnetic field-assisted sparking process for improved photocatalytic dye degradation and CO2 reduction

Copper-based films (Cu2(OH)3NO3, Cu2O, and CuO) were successfully synthesized using a sparking process under an external magnetic field, without requiring an annealing process. We thoroughly investigate the impact of magnetic field orientation on the structural, morphological, and optical properties of the films, along with their performance in photocatalytic degradation of methylene blue (MB) and carbon dioxide (CO2) reduction. Field-emission scanning electron microscopy (FE-SEM) images reveal that the CuEB(S) sample displays secondary particles forming spherical, dense clusters, whereas the CuEB(N) sample exhibits larger, loosely packed clusters. In contrast, the cluster-like structures disperse in the CuEB(P) sample, resulting in a smoother film surface aligned with the parallel magnetic flux direction. Upon close observation, rice-shaped particles of varying sizes (26.3–60.3 nm) were found stacked together. This study presents a facile method to selectively fabricate films comprising single-phase Cu2(OH)3NO3, a CuO/Cu2O composite, or a combination of all phases by manipulating the external magnetic field orientation during the sparking process. All synthesized materials exhibit photocatalytic activity, with the heterojunction composed of CuO, Cu2O, and Cu2(OH)3NO3 demonstrating superior performance. This heterostructure achieved up to a 180 % enhancement in MB degradation and approximately doubled the CO2-to-CO conversion rate to 16.09 μmol g–¹ h–¹ compared to the sample prepared without a magnetic field.

Improving Efficiency of a Pole-Changing Vernier Machine Considering Residual Magnetic Flux Density

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

50W급 산업용 무선 충전 LED 조명등 개발

In this study, a 50W class industrial wireless charging LED lamp capable of wireless charging was developed. The LED battery pack was charged by a push-pull DC-DC converter, and the transmission-receiving coils for wireless charging adopted a magnetic flux concentrating type. Magnetic flux distribution and magnetic flux direction were analyzed by MAXWELL, and a transmission-receiving coils were manufactured according to the designed the turns ratio. The validity of this study was verified by six quantitative performance indicators by a 50W class wireless charging LED lighting test set. As a result of the verification, the light efficacy of the LED lamp was 126lm/W, the power conversion efficiency was over 90%, and the WPT efficiency was over 85% under the 6mm air gap condition. Since the working environment of industrial LED lamp is poor, it must be resistant to waterproofing, and the developed system satisfies the waterproof standard of IP X5. The output voltage ripple was 4.55%, and it was possible to supply stable DC voltage to LED lamp. The 50W wireless charging LED light developed as a result of this study can be used not only for industrial LED work lights but also for indoor and outdoor lighting, and when LEDs of various colors are applied, it is expected to be applied as landscape lighting.

방향성 강판을 적용한 전기자동차용 매입형 영구자석 동기전동기 설계

In this paper, the interior permanent magnet synchronous motor (IPMSM) for electric vehicles (EVs) using grain-oriented electrical steel (GO) is proposed. It was confirmed through the B-H characteristic curve and the B-W characteristic curve that the GO has superior magnetic characteristic compared to the non-grain-oriented electrical steel (NO). In order to maximize the effect of GO, the GO was partially applied to the stator teeth that has a uniform magnetic flux direction through magnetic path analysis of the EV traction motor. It has been confirmed that the output and various characteristics of the motor have improved with the application of GO. In particular, the iron loss was decreased by 44.83% in no-load condition. Moreover, the average torque and the efficiency were increased by 5.26%, 0.29%, respectively and the iron loss was decreased by 42.45% in load condition. The result of this study shows that the partial application of the GO in IPMSM improves the performance of the motor, effectively.

Energy Consumption Characteristics for Design Parameters of Permanent Magnet-Based Al Billet Heater

This study analyzed design factors to maximize energy efficiency, via numerical analysis, through an examination of the characteristics of a heating system that uses permanent magnets and is employed for preheating in the aluminum cladding extrusion process. The design parameters of the billet heater using permanent magnets are the magnetic flux direction, the number of magnets, clearance, and eccentricity. The magnetic flux density, current density, power loss, temperature, and energy consumption characteristics were examined using the results of the parameter variations. Numerical analysis for the base model was conducted, and it was experimentally verified that the aluminum billet reached 450 °C in about 260 s, and the temperature error at that time was about 2%. The analysis results show that the optimal factor conditions vary significantly depending on the magnetic force direction of the permanent magnet, that is, the circumferential (tangential) and centrifugal (normal) directions. Furthermore, eccentricity has an effect on efficiency in general, and the narrower the clearance was between the magnet and billet, the higher the efficiency achieved. That is, it was confirmed that the power loss increased by about 1.79% in the four permanent magnets to the tangential model, and increased by about 10.51% in the 12 permanent magnets to the tangential model when an eccentricity of 2 mm was applied at a clearance of 2.5 mm. In addition, the optimal design parameters of a system that heats aluminum billets with a diameter of 60 mm and a length of 70 mm were proposed, and the importance of the design parameters was revealed. In this study, it was found that 12 magnets were the most effective when the magnetic flux pole direction was tangential.

New Way of Generating Electromagnetic Waves

This article presents a new method for generating low-frequency electromagnetic waves for navigation and communication in challenging environments, such as underwater and underground. The key concept is to disturb the magnetic energy stored around a permanent magnet in a time-variant fashion. The magnetic reluctance of the medium around the permanent magnet is modulated to alter the magnetic flux intensity and direction (disturb the stored energy) in order to achieve this goal. The nonlinear properties of the surrounding magnetic material are a critical phenomenon for efficient and effective modulation. Since the proposed way of generating the electromagnetic field is not based on a second-order system (resonant structure), the bandwidth of any modulation schema is not limited to the overall system quality factor. A transmitter is prototyped as a proof of concept, and the generated field is measured. Compared with the rotating magnet, the prototyped transmitter can modulate up to 50% of the permanent magnet’s stored energy with much lower power consumption.

Motion Control of Magnetic Microrobot Using Uniform Magnetic Field

A microrobot with untethered control in 3D space is a good choice to be applied in the fields of biomedicine with in small and confined workspace. In this paper, an electromagnetic actuation system (EMA) which combined with Helmholtz coil and Maxwell coil for the microrobot 5 DOF locomotion in 3D space is built. The magnetic field analysis of the proposed 3D EMA system was analyzed by finite-element-method (FEM) with multi-physics COMSOL software. The proposed EMA system can produce magnetic field with different characteristics such as a controllable uniform gradient magnetic field, a rotating magnetic field and a oscillating magnetic field in a three-dimensional space by independently changing the current in each coil. In this paper the 3D motion dynamic equation model of microrobot was established. A novel control method for the gravity compensation for the wireless locomotive microrobot was proposed. The proposed method has the property that the direction of magnetic flux and the locomotion path of the microrobot are independent. Meanwhile, it can achieve the horizontal motions or nearly horizontal motions and overcome the gravity well at the same time. It has been verified by experiments in 3D liquid environment. With the proposed method, the microrobot shows good performance in horizontal motions as well as various motions in the 3D space.

Plane-Type Receiving Coil With Minimum Number of Coils for Omnidirectional Wireless Power Transfer

In this article, a novel structure of a receiving (Rx) coil with only two coils, which enables omnidirectional wireless power transfer (WPT) for any type of transmitting (Tx) system, is proposed for the first time. The coil adopts each coils into plane cross-shaped ferrite core, with each leg of the ferrite core intersecting both coils. The intersecting direction of the ferrite core for one coil is identical to that of the other one when it is rotated 90 degrees. It is verified that voltage will be induced on at least one coil with any direction of magnetic flux. With an analysis of circuit diagram, it is shown that a high quality factor of each coil can guarantee an omnidirectional power transfer even when the coupling coefficient between two coils has a nonzero value. A simulation model and an experimental prototype is built to verify the omnidirectional WPT of the proposed Rx coil structure, with loop-type Tx coil as an example among various Tx types. Omnidirectional power transfer capability of the proposed coil was verified with a light emitting diode (LED) load. The superiority of the proposed coil was verified by comparison with other Rx coil structures also.

Influences of magnetic flux on growth and direction of Chiang Rai Phulae Pineapple roots

Currently, chemicals are widely used in plant cultivation in many countries, allowing plants to have more roots, grow faster, and increase productivity. This research aimed to study application of permanent magnets (Neodymium Magnets (NM)) to accelerate the growth of plant roots instead of using chemicals for cultivation. Pineapples were planted in liquid media under permanent magnetic flux density (B) of 1-90 mT intensity. Magnetic flux directions were arranged in two forms, either toward or ejected from the plant roots. The result showed that the number of roots of pineapples planted under the magnetic flux was 2 times greater than the control and the length of roots was also 4.5 times greater in length than those without magnetic flux. The roots exposed toward the magnetic flux had about 2 times greater number and length of roots compared to when the magnetic flux direction was ejected from the plant roots. The direction of the magnetic flux influenced the direction of plant root growth significantly.

Dislocation Magnetism of the GaSb〈Mn〉 Semiconductor

The GaSb〈Mn〉 magnetic semiconductor has been studied using the visualization and analysis of electron-microscopic images of the material, an approach widely used in practice in making ultrastrong permanent magnets based on metallic alloys. The role of columnar magnetic crystals is assigned to manganese-decorated dislocations, and the role of a nonmagnetic matrix is played by the GaSb compound semiconductor. The material synthesized in this study has been characterized by X-ray diffraction, scanning electron microscopy, and magnetic measurements. The magnetization of a polished transverse section of GaSb〈Mn〉 has been analyzed as a function of the angle it makes with the magnetic flux direction and as a function of temperature in the range 4–300 K.

Significant power enhancement method of magneto-piezoelectric energy harvester through directional optimization of magnetization for autonomous IIoT platform

Unlike previous piezoelectric energy harvesters that generate electrical energy from a magnetic field according to the magnetic strength or magnetostrictive material, the proposed method achieves significant power enhancement using directional optimization of magnetization. This method can serve as a ubiquitous autonomous energy source that converts a magnetic field into usable electrical energy in a wireless sensor network for an (Industrial) Internet of Things (IIoT). The key approach in the proposed model is to increase of the Lorentz force by vertically adjusting the magnetic flux direction of a power cable and the magnetic direction of a tip magnet. In the simulation, a 3592 times higher y-axis Lorentz force was obtained in the vertical pole array, which resulted in about a 1.6 times higher output voltage. Then, we experimentally compared the electrical output performance of six different types of pole array according to the size and direction of the tip magnet. In a one-tip magnet (10 × 10 × 10 mm3), the output power values were 2.34 mW (Vertical) and 1.23 mW (Horizontal) at 8 kΩ matching impedance. For two-tip magnets (20 × 10 × 10 mm3), the output power values of the harvester were 39.2 mW (Planar-Vertical), 18.4 mW (Orthogonal-Vertical), 8.64 mW (Planar-Horizontal), and 0.05 mW (Orthogonal-Horizontal) at 5 kΩ matching impedance. It was found that the power generation differed by 2.13 to 784 times. With this method of power enhancement using multi-disciplinary research, we successfully constructed autonomous IoT and IIoT sensor systems for smart homes, smart buildings and smart factories.

Coreless Transmitting Coils With Conductive Magnetic Shield for Wide-Range Ubiquitous IPT

New coreless transmitting (Tx) coils with a conductive material plate for wide-range ubiquitous inductive power transfer (IPT) zones, i.e., U-IPT zones, where electric devices can be wirelessly charged during operation, are proposed in this paper. Because commercialized IPT systems are only available for short distances of several centimeters and one-to-one charging, the demand is increasing for U-IPT zones in which long-distance wireless charging with three-dimensional (3-D) free-positioning and simultaneous charging of multiple receiving (Rx) coils can be achieved. To satisfy this demand, U-IPT zones should be constructed to have a uniform magnetic field distribution in a wide space, which also poses no risk to the human body. In addition, to generate a uniform magnetic field in a wide 3-D space, such as a single room, the system requires the installation of many Tx coils above the ceilings and behind the walls of the room, and these coils should be capable of high electrical performance to support the efficiency of the entire IPT system and should be of excellent mechanical quality. Therefore, a U-IPT zone should meet the following four criteria: human safety, free-positioning of Rx coils, magnetic field uniformity, and economization. By virtue of a conductive material plate that cancels out the undesired direction of magnetic flux generated from the return wires, the proposed coreless Tx coil does not need any heavy ferromagnetic cores, which can cause nonuniformity of the magnetic field distribution and difficult construction. A prototype coreless Tx coil with the dimensions of 1 m × 1 m × 10 cm was fabricated and experimentally verified for a 1 m × 1 m U-IPT zone. The experimental results showed that 74%, 83%, and 76% high magnetic field uniformity could be achieved for z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 25 cm, 50 cm, and 75 cm, respectively, and a 3-D omnidirectional wireless power delivery was achieved, while the guideline of the International Commission on Non-Ionizing Radiation Protection for human safety was satisfied throughout the entire U-IPT zone. Moreover, the weight of the entire system was only 9 kg, enabling easy installation. In the multiple wireless charging experiments, 47 W of power was consumed in total by load resistors, each of them connected to nine Rx coils, respectively, with 32% power efficiency at z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 20 cm.

Shape Mapping Detection of Electric Vehicle Alloy Defects Based on Pulsed Eddy Current Rectangular Sensors

In this paper, we investigate pulsed eddy current (PEC) testing based on a rectangular sensor for the purpose of defect shape mapping in electric vehicle lightweight alloy material. Different dimensional defects were machined on the 3003 aluminum alloy and detected using the A-scan technique and C-scan imaging in two scanning directions. The experiment results indicated that defect plane shape could be preliminarily obtained and length and width could be estimated based upon C-scan contour images. Consequently, the comparison of results between the two directions showed that the C-scan identification in the direction of magnetic flux was better than in the direction of the exciting current. Finally, subsurface defects and irregular defects were detected to verify the performance of shape mapping as a recommended approach. The conclusion drawn indicates that the proposed method, based on PEC rectangular sensors, is an effective approach in reconstructing a defect’s shape.

AN ADJUSTING APPROACH TO THE DETERMINATION OF THE PERMEABILITY FUNCTIONAL DEPENDENCIES OF ANISOTROPIC COLD-ROLLED ELECTROTECHNICAL STEELS

Purpose. To develop an effective approach for the determination of mathematical functional relationships for the high-precision description of the nonlinear dependences of the permeability on the magnetic flux density, taking into account the anisotropy of modern cold-rolled electrotechnical steel, which are used in the production of new series of power transformers.Methodology. The researches were carried out using interpolation methods, approximation, regression analysis, mathematical physics, electromagnetic field theory.Findings. The methods of functional conception of nonlinear characteristics of magnetization of ferromagnetic materials, including cold-rolled anisotropic electrotechnical steels, are researched. An adjustment approach is proposed to increase the dimension of the initial data, based on the spline interpolation method on the Hermite polynomial basis for the digital data of the magnetization characteristics. This excludes an increase of the errors in determining the permeabilities in the sections between the nodal values of the magnetic flux density. For a mathematical description of the dependences of the permeability on the magnetic flux density, a special functional basis with Gaussian functions and additional error functions has been developed, that ensures the continuity of derivatives of various orders at fixed angular values between the rolling direction of anisotropic electrical steel and magnetic flux. The method of nonlinear regression in the structure of function package of the Mathcad software for the high-precision determination of regression coefficient vectors in functional descriptions of permeabilities is applied. With the help of verification and validation of the results, which adjusting nonlinear regression with computational data using the generic method and with experimental data, a significant decrease in the relative errors that do not exceed 1.62% for fixed angles between the direction of rolling of anisotropic electrical steel and magnetic flux is obtained. The application of the new regression equations substantially improves the conditions for the field simulation of electromagnetic fields in the open-circuited mode of the power transformer in the Comsol Multiphysics software, and ensures the stability of iterative computing processes.Originality. A new approach to increasing the dimension of input arrays, based on spline interpolation of digital data arrays of magnetization characteristics for fixed angles between the directions of rolling of the electrical steel and magnetic flux is implemented. For nonlinear regression equations, a new functional basis with Gaussian functions and additional error functions for mathematical descriptions with continuous derivatives for the dependences of the permeabilities of anisotropic cold-rolled electrotechnical steels on the magnetic flux density with high accuracy in the range of angles variation between the rolling directions and magnetic flux from 0o to 90o.Practical value. The approaches and techniques for the basis of Gaussian functions and additional error functions proposed in this paper make it possible to significantly improve the accuracy of determining the nonlinear characteristics of anisotropic electrotechnical steels. Also to reduce the relative errors to 1.62% when the angles between directions of rolling of the electrotechnical steels and magnetic flux vary from 0° to 90°.

A hybrid magnetorheological elastomer developed by encapsulation of magnetorheological fluid

A new hybrid MR elastomer was fabricated by encapsulating a magnetorheological fluid (MR fluid) within a UV-curable silicone elastomer. A strong magneto-deformation effect was observed where the hybrid MR elastomer changed its shape in the presence of a magnetic field. Furthermore, when a moderately strong magnetic field was applied, the elastic and damping properties of the hybrid MR elastomer changed obviously. The magnetic field strength, strain amplitude, strain rate, preload, and orientation of magnetic flux direction affected the behavior of the new hybrid MR elastomer. The hybrid MR elastomer also exhibited a higher MR effect when compared with conventional MR elastomer. The investigation also found that the combination of magnetic field strength and preload highly influenced the hybrid MR elastomer behavior. This MR fluid-encapsulated elastomer is expected to be a potential candidate for the tunable spring-damper element as well soft actuators.

Optimal Design of an Axial-Flux Switched Reluctance Motor With Grain-Oriented Electrical Steel

This paper employs grain-oriented electrical steel (GOES) in an axial-flux switched reluctance motor (AFSRM) to improve its torque characteristic, taking advantages of the material's excellent magnetic properties in the rolling direction. Based on the study on the parameter and switching characteristics of an AFSRM, GOES can be divided into pieces and arranged in the rotor and stator teeth so that the magnetic flux mainly travels along the rolling direction of the material. AFSRMs with different lamination shapes and deviation angles between the magnetic flux and rolling direction of the GOES have been studied to further improve the output performance; the maximum electromagnetic torque of the proposed design shows a 20.5% increase in comparison with that of the conventional nonoriented electrical steel motors under identical conditions. The rotor retaining ring is composed of epoxy resin lamination to constrain the rotor teeth modules. Thermal and stress analyses under fault conditions are analyzed to verify the reliability of the retaining ring. Furthermore, an AFSRM prototype is built and experiments are conducted to validate the calculated data.

Angle-dependent magnetotransport in GaAs/InAs core/shell nanowires.

We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires. At small tilt angles, when the magnetic field is aligned nearly parallel to the nanowire axis, we observe Aharonov–Bohm type h/e flux periodic magnetoconductance oscillations. These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell. With increasing tilt of the nanowire in the magnetic field, the flux periodic magnetoconductance oscillations disappear. Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles. We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

Design of Electromagnetic Linear Actuator Using the Equivalent Magnetic Circuit Method

This paper analyzes the design variations of an electromagnetic linear actuator with a divided coil excitation system, such as the colenoid system, using the equivalent magnetic circuit (EMC) method. First, the magnitude and direction of magnetic flux for each pole can be obtained using the EMC method, while the magnetic flux density for each pole is calculated using the superposition principle. To make the magnetic flux density uniform at each pole, the pole width is adjusted by the iteration method. The generated clamping force of the optimized model with EMC has almost the same force characteristics as the optimization results based on the finite-element analysis. By the proposed EMC method, the characteristics of the electromagnetic linear actuator with variations in the slot width and current are investigated. An electromagnetic linear actuator is also developed to produce a clamping force of 35 kN, and the experimental results show that it can be used to hold a workpiece firmly instead of using a hydraulic cylinder in a chucking system.