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Vibration is a challenging issue during the design process of electric machines. In this article, an analytical model of an ironless axial flux permanent magnet machine (AFPM) is proposed for electromagnetic force calculation. And the vibration of the machine is analyzed combined with the electromagnetic force and modal shape. Firstly, the causes of the machine vibration are analyzed based on a 12-slot/10-pole AFPM machine configured with a middle ironless stator and double-sided rotor. Then, an analytical model with the end effect considered for air gap magnetic flux density is presented and compared to the finite element analysis (FEA). The electromagnetic force is calculated based on the air gap flux density. The final analytical calculation results of air gap flux density and electromagnetic force both match the FEA ones well. After that, a three-dimensional simulation model is built and modal shape analysis of the entire machine system is studied. Finally, the validity of the vibration spectrum simulation results is verified through experiments, proving the effectiveness of the presented AFPM machine vibration mechanism and the electromagnetic force analytical model. [ABSTRACT FROM AUTHOR]

The interturn short circuit fault is one of the common faults in power transformers. At present, research on interturn short circuit faults focuses on high, medium, and low voltage windings, while there is relatively little research on interturn short circuit in regulating windings. Specifically, there is a lack of reported studies on the transient electromagnetic processes, magnetic field distribution, and electromagnetic force characteristics of interturn short circuits in regulating windings unconnected to the circuit. This study presents an actual fault scenario involving interturn short circuits occurring in the untapped portion of the regulating windings of a specific power transformer. A field-circuit coupled model was established to analyze the transient electromagnetic processes during the fault, and the model's effectiveness was validated by comparing its results with actual fault recording data. Additionally, the magnetic field distribution and electromagnetic force characteristics during the fault were analyzed, and discussions were carried out regarding various ratios of short-circuit turns in the regulating windings. The results indicate that even when an interturn short circuit occurs in the portion of the regulating winding that is not connected to the circuit, the current in the short-circuited turns can reach several tens of times the rated value. Additionally, the leakage magnetic field and the electromagnetic force experienced by the short-circuited ring also increase significantly. The short-circuit ratio has a significant impact on the current of the short-circuited ring, leakage magnetic field intensity, and electromagnetic force. This study contributes to a better understanding of the impact of interturn shortcircuit faults in the untapped portion of the regulating windings, offering crucial technical support for fault diagnosis and prevention of power transformers. [ABSTRACT FROM AUTHOR]

To solve the problems of poor transmission performance and small torque regulation range of traditional MR device, a variable working gap MRF transmission device driven by electromagnetic force is proposed. The device uses electromagnetic force driving the squeeze disk to move axially to squeeze the MRF, thereby changing the number of working gaps and effective working thickness of the MRF to improve the transmission performance of the MR device. Based on the coil magnetization effect, the relationship between current, magnetic field intensity, and electromagnetic force is established. According to the driving characteristics of electromagnetic force and the rheological characteristics of MRF, a nonlinear function relationship between electromagnetic force and MRF working gap thickness and working volume is derived. Using the finite element method, a theoretical analysis of the magnetic circuit design, magnetic field distribution and temperature change profile in different parts of MRF device with different currents was conducted, the MRF torque transfer equations were deduced and calculated, and experimentally verified the correctness of the theoretical equations. Finally, the transmission performance of the variable working gap MRF transmission device is tested through the established testing system. Results show that, the required squeeze force is 6.65 kN when the MRF thickness reaches 1 mm in both working gaps. As the current increases from 0.5 to 3.0 A, the electromagnetic force increases from 0.65 to 6.77 kN, with an increase of 972.3%, the average temperature of the MRF in working gap I increases from 25.2°C to 71.2°C and the MRF in working gap II increases from 23.5°C to 48.3°C. When the current is 1.5 A, the MRF in the working gap I reaches magnetic saturation, continue to increase the current to 3.0 A, the MRF thickness in both working gaps is 1 mm, and the MR device transmits torque reach 376.6 N·m, which is 72.3% higher than that of the traditional MR device. [ABSTRACT FROM AUTHOR]

This paper introduces an evaluation of the flux air gaps of Shunt Reactors (SRs) to effectively mitigate fringing and leakage fluxes along the height of the iron core. The assessment of these discretely distributed flux air gaps in SRs is a rigorous and challenging process. To define their exact number, the case of one flux air gap is analyzed and investigated to observe/simulate the influence of the flux density distribution and the leakage flux along the air gaps on the reactive power and the operation conditions of the SR. Based on that, to reduce leakage flux, a large flux air gap is divided into smaller ones. Initially, an analytic model is presented to define the main parameters of the SRs. Then, a finite element method is developed to simulate electromagnetic quantities, such as the magnetic flux density, leakage flux, and electromagnetic force. The obtained results can help manufacturers define the exact number of flux air gaps along the iron core of the SR. From that, a suitable technology can be given in manufacturing high voltage SRs applied to high or super high voltage transmission lines. [ABSTRACT FROM AUTHOR]

In order to clarify the magnetic-thermal-force changing rule of high-frequency transformers under different winding arrangements, this paper tests the magnetization and loss characteristics of nanocrystalline materials at different temperatures, and based on the magnetization and loss data, establishes a magnetic-thermal-force coupling calculation model of 15 kVA, 5 kHz nanocrystalline high-frequency transformers, and calculates and analyzes the magnetic flux density, loss and temperature rise distributions of high-frequency transformers with three different winding arrangements under no-load and short-circuit conditions, respectively. Through comparative analysis, it was found that under no-load conditions, the cross-transposition of winding has less influence on the magnetic flux of the high-frequency transformer core, but it can reduce the iron-core loss and transformer temperature rise. The cross-transposition of winding under short-circuit conditions can significantly reduce the leakage magnetic field strength of high-frequency transformers; complete cross-transposition weakens the high-frequency transformer losses and temperature rise better than partial cross-transposition. According to the winding current density and core leakage field distribution under short-circuit conditions, we calculated and analyzed the distribution of its the axial and radial electromagnetic forces. The results show that the axial electromagnetic force causes the winding to be squeezed from both ends to the middle, the radial electromagnetic force causes the primary winding to shrink inward and the secondary winding to expand outward, so cross-transposition can greatly reduce electromagnetic force and weakening the deformation of the winding. Therefore, high-frequency transformers of winding cross-transposed should be used in actual projects to reduce transformer temperature rise and improve efficiency and security. This research has theoretical significance for the multi-physical field coupling of high-frequency transformers and its structural design. [ABSTRACT FROM AUTHOR]

The magnetic suspension damper, which is based on magnetic suspension technology, is receiving more and more attention from academics as active–passive hybrid damping technology develops. A new symmetric magnetic suspension structure is constructed in this study, and the accuracy of the simulation findings is confirmed by contrasting the output from finite element simulation with the theoretical formulations. On the basis of this, how the structure, size, and material of the electromagnet and armature affect the magnetic flux density, electromagnetic force, and suspension force is investigated. The structure optimization of the electromagnet and armature was performed in accordance with the simulation results, and a new symmetric magnetic suspension structure was produced. The results of the simulation demonstrate that DT4(electrical pure iron) is the ideal material for armatures and electromagnets. The reinforcing ring construction can be built up by the armature to increase suspension force. The suspension force output by the armature will be greatly increased when the size and placement of the reinforcing ring structure are right. The system stiffness adjustment range will expand at this point, enhancing the magnetic suspension damper's functionality. This study offers novel perspectives for designing structures that reduce vibration and noise in various projects and serves as a guide to constructing magnetic suspension dampers. [ABSTRACT FROM AUTHOR]

Saving energy from domestic appliances is a focus in the effort to combat energy challenges. Linear compressors are a more efficient alternative to the traditional compressors used in refrigerators, which account for 20–40% of all residential electricity use. This article investigates the new topology of the moving magnet (MM), dual-stator single-mover linear oscillating actuator (DSSM-LOA) for linear compressor application. Both the stators were C-shaped, with coils looped across their end sides. Two permanent magnets (PMs) that were axially magnetized were housed on the mover. The PM structural shape significantly affected its fabrication cost and magnitude of magnetic flux density ( B ). The DSSM-LOA makes use of axially magnetized rectangular-shaped PMs because they are inexpensive and generate high electromagnetic (EM) force density. End ferromagnetic core materials were used to improve the magnetic flux, linking from the stator to the mover. All the design parameters were optimized through parametric analysis using the finite parametric sweep method. Parameters present within the three primary parameters (length, height, and depth) that were assumed constants were optimized, and the optimal dimensions were selected based on the EM force. The investigated DSSM-LOA was contrasted with traditional LOA designs, and they showed significant improvement in EM force per ampere, generally named motor constant (MC), MC per PM mass, MC density, cogging force, and stroke. Additionally, the proposed DSSM-LOA had a simple structure and low cost, and it operated in a feasible range of strokes for linear compressor application. [ABSTRACT FROM AUTHOR]

• The steady-state EMF is the body force and has self-regulating characteristic. • The maximum welding thickness of the plate is up to 30 mm in the steady-state EMF assisted laser welding in a single pass. • The intensity of the magnetic field and the density of the DC have the equivalent effect to control the magnitude of the steady-state EMF. Root collapse is the major problem in laser welding of the thick plate, limiting the maximum welding thickness in a single pass. The steady-state electromagnetic force (EMF), produced by direct current (DC) and rectangular magnets, greatly improve the welding stability at the root. Aiming to understand the influence of the EMF on the root collapse suppression, the transient simulation model of the EMF assisted laser welding is developed and deeply discusses the inner flow behaviors. The simulation results show the weld morphology has a great influence on the magnitude and orientation of magnetic field. The EMF is the body force and has self-regulating characteristic. The direction of the EMF is confirmed based on the Fleming's rule and mainly directed vertical. The experimental tests are implemented in full penetration laser welding of thick stainless steel. The EMF is the real working force on improving the welding stability, not the DC or magnetic field alone. The maximum thickness of the plate is up to 30 mm in a single pass. The intensity of the magnetic field and the density of the DC have the equivalent effect to control the magnitude of the EMF. The vector control of the EMF is more flexible. [ABSTRACT FROM AUTHOR]

The structural discontinuities in the form of air gaps in transformer cores cause the concentration of electromagnetic force, which is an important source of transformer vibration and noise. In this paper, an engineering model of magnetic flux density and electromagnetic force density on transformer core discontinuities is analytically developed. Based on a reasonable structural simplification and assumptions, magnetic flux density and electromagnetic force density are deduced as explicit functions of the geometric, material, and electrical excitation characteristics of the gap region and the transformer core. The accuracy of the established model is validated by the finite element method (FEM) combined with a magnetic measurement experiment. According to this engineering model, the electromagnetic force density can be reduced by decreasing the gap ratio and increasing the gap thickness to a reasonable level. The outcome of this paper can help to understand the physical mechanism of the electromagnetic force generated by core air gap discontinuities, which is meaningful for noise control and the condition monitoring of transformers. [ABSTRACT FROM AUTHOR]

Shunt reactors are usually used in electrical systems to imbibe reactive powers created by capacitive powers on the lines when the system is operating on low or no loads. Moreover, they are also used to balance reactive powers and maintain the stability of a specified voltage. In general, the air gaps of a magnetic circuit shunt reactor are arranged along the iron core to reduce the influence of fringing and leakage fluxes. Therefore, non-magnetic materials made of ceramics or marbles are often used in air gaps to separate the iron core packets. The direction of the fringing flux is perpendicular to the laminations, so the core packets of the shunt reactor are generally made from radially laminated silicon steels. Due to the alternating electromagnetic field through the core, a periodically altered electromagnetic force is produced between the core packets, tending to compress the ceramic spacers. This electromagnetic force causes vibration and noise in the core. In this research, a finite element approach based on the Maxwell stress tensor was developed to compute the magnetic flux density and the electromagnetic forces appearing in a shunt reactor. [ABSTRACT FROM AUTHOR]

The structural discontinuities in the form of air gaps in transformer cores cause the concentration of electromagnetic force, which is an important source of transformer vibration and noise. In this paper, an engineering model of magnetic flux density and electromagnetic force density on transformer core discontinuities is analytically developed. Based on a reasonable structural simplification and assumptions, magnetic flux density and electromagnetic force density are deduced as explicit functions of the geometric, material, and electrical excitation characteristics of the gap region and the transformer core. The accuracy of the established model is validated by the finite element method (FEM) combined with a magnetic measurement experiment. According to this engineering model, the electromagnetic force density can be reduced by decreasing the gap ratio and increasing the gap thickness to a reasonable level. The outcome of this paper can help to understand the physical mechanism of the electromagnetic force generated by core air gap discontinuities, which is meaningful for noise control and the condition monitoring of transformers.

This article deals with electromagnetic forces of permanent magnet synchronous motors (PMSMs) with inclined and parallel rotor eccentricity. The electromagnetic forces have the spatial orders of the main components (multiples of pole numbers) and the sideband components when the rotor is eccentric. Although other studies have reported that each amplitude of an upper and a lower sideband is different, the causes of the asymmetry have not been fully investigated. The rotor eccentricity leads to changes in the gap permeance, the working point of the rotor magnets, and the distribution of gap magnetic flux density. By considering these effects in detail, we develop a new analytical expression of electromagnetic force, which expresses the asymmetry of a pairs of sidebands. The expression is compared with 3-D magnetic field analyses of PMSMs with inclined and parallel rotor eccentricity. As a result, it is found that upper sideband amplitudes are larger than lower sideband amplitudes, and the ratio of an upper sideband to the lower sideband of parallel eccentricity is larger than that of inclined eccentricity. [ABSTRACT FROM AUTHOR]

• For short-circuit analysis, constant-permeability core modeling can be used. • 2D-axisymmetric geometry is not accurate for calculating axial forces. • Simulations using 2D-axisymmetric geometries underestimate radial forces. • Detailed representation results in more accurate EF density and total axial forces. • Only highly detailed geometries allow to determine fault-prone regions. Computer simulations are currently one of the most used methods on transformer's short circuit analysis. For them to be effective, an accurate characterization of the transformer core and geometric representation of windings is essential. Hence, this work investigated the influence of core characterization and different geometric representations on magnetic flux density (MFD) and electromagnetic forces (EF) calculated during short circuits. A comparative study using simulations based on the finite-element method (FEM) were carried out for a 180 MVA transformer model. First, the influence of the nonlinear characteristic of the core B-H curve on EF was analyzed. Then, three two-dimensional (2D) axisymmetric and one three-dimensional (3D) representations were compared. Results indicate there is no significant difference in EF with a core represented by a constant value of permeability. Also, 2D-axisymmetric geometric representations underestimate radial forces and diverge significantly on axial forces in comparison with the 3D representation. Differences up to 99% between the calculated total axial forces were obtained for the analyzed cases. In addition, representations with greater level of detail result in magnetic force density up to 5.5 times greater than that obtained with the simplified representation. [ABSTRACT FROM AUTHOR]

In conventional electromagnetic tube expansion (EMTE), the wall thickness of the tube decreases significantly because the electromagnetic force is mainly in the radial direction. To solve this problem, this paper proposes a new method named electromagnetic tube expansion with axial compression (EMTEAC). Besides the driving coil, we introduce a coil at each end of the tube to generate axial electromagnetic force on the tube. We use the finite element method to analyze the distribution of the magnetic flux density and the electromagnetic force generated by the three coils in series. The simulation results show that the axial electromagnetic force generated by EMTEAC is about 7 times that generated by conventional electromagnetic tube expansion, which enhances material flow when the tube is expanding. The effectiveness of the method is verified by a series of experiments. The experimental results show that EMTEAC reduces the decrease in wall thickness from 27 to 19%. [ABSTRACT FROM AUTHOR]

The effect of harmonic magnetic field (HMF), pulse magnetic field (PMF), differential phase harmonic magnetic field (DHMF), and differential phase pulse magnetic field (DPMF) on liquid and mushy zones of crystallizing metal was investigated by numerical simulation referring to electromagnetic DC (direct chill) casting process. Firstly, the experimental pulse current for electromagnetic casting was obtained by a digital oscilloscope. The physical and finite element models of Φ300-mm cylindrical crystallization for the electromagnetic field simulation were established. Then, the distribution of magnetic flux density (B) and electromagnetic forces (FMAG) generated by the four types of magnetic fields were obtained in a period (T). Actions of HMF, PMF, DHMF, and DPMF on molten melt were discussed based on radial and axial electromagnetic forces. Finally, the effects of electromagnetic parameters (current intensity, frequency, and duty cycle) on electromagnetic forces under PMF and DPMF were studied. The effect of electromagnetic forces on metal flow has been discussed. The results indicate that compared with harmonic current, the pulse current can generate a stronger magnetic field with the same conditions. Single-coil magnetic field can easily cause the molten metal radial vibration. The differential phase magnetic field can not only cause radial vibration but also produce axial convection, while the vibration effect is weaker. The electromagnetic forces increase with the increase of current intensity and duty cycle under PMF and DPMF. Moreover, the electromagnetic force has low sensitivity to frequency under DPMF. [ABSTRACT FROM AUTHOR]

The Active Magnetic Bearing (AMB) is used in the main helium blower in the High Temperature Reactor-Pebble-bed Modules (HTR-PM) which is being constructed in Shandong province, China. The axial AMB is very large and works under extreme conditions. The calculation deviation of the electromagnetic force of the axial AMB was studied experimentally. Through measuring B-H curve of the material in large range of magnetic field intensity, considering flux leakage in calculation, and considering residual magnetism and the change of the gas gap in measurement, the calculation deviation reduces to 10%, with most values less than 5%. The material selection method of the axial AMB working under extreme conditions was studied experimentally. Through measuring the electromagnetic force when the stator and the thrust disc are made of different materials, it's found that the force mostly depends on the stator. Combined with the analysis of the stress distribution of the stator and the thrust disc under working condition, the dual material selection method is proposed. That is, the stator material should have good magnetic properties and its mechanical properties are not very important, however, the thrust disc material should have good mechanical properties, and its magnetic properties are not very important. [ABSTRACT FROM AUTHOR]

This study analysed the characteristics of electromagnetic force and noise of claw pole alternators with different pole and slot combinations and different phase number. The magnetic flux density in the airgap was first derived based on the magnetomotive force and permeance. Then the electromagnetic force was obtained using Maxwell stress tensor method. According to the analytical model, the spatial order and frequency of electromagnetic force can be expressed as the function of pole‐pairs number p, slot number s and phase number m. Afterwards, the electromagnetic noise of three different alternators was tested in a semi‐anechoic chamber. Combined with the 2D fast Fourier transform of electromagnetic force, the main force harmonics that caused the electromagnetic noise were distinguished. Finally, the relationship between the frequencies of electromagnetic force and noise and the number of pole‐pairs and phase were established. Analysis result shows that for m‐phase 2p‐pole/s‐slot integer slot claw pole alternators, the spatial order of electromagnetic force is kp (k = 0, 1, 2, 3,...) and the corresponding frequency of these force harmonic is [±2mpk′ + (±kp)]fr (k′ = 0, 1, 2, 3 ...). The main order (frequency domain) of electromagnetic noise is 2mp which is independent of the slot number. [ABSTRACT FROM AUTHOR]

In the process of micro beam plasma welding of thin-walled parts, gravity and surface tension make a molten metal flow downward, sometimes causing a bad formation. To solve this problem, a new external magnetic field-controlled method based on the eddy current principle was proposed. The distribution of the magnetic flux density, the induced current density, and the Lorentz force on a 4 mm stainless steel AISI 304 thin plate was examined using different oscillation frequencies (1, 5, 10 kHz) of the magnetic field with the finite element package COMSOL Multiphysics 5.0. The higher frequency was found to be more helpful to create greater electromagnetic force. This study examined the single-pass and three-layer welding of the 4-mm-thick stainless steel AISI 304 with different magnetic fields (3~12 mT) at 10 kHz. The results show that 7- and 8-mT magnetic fields were effective in suppressing the sagging of the cladding layer. [ABSTRACT FROM AUTHOR]

The SWASTIK type radial magnetic field (RMF) contact design is widely used in vacuum interrupters. The mutually perpendicular petal limbs are a unique feature of this contact design. The focus of this work is to relate the Lorentz force acting on the arc with petal dimensions through closed‐form expressions. Considering the petal limbs as equivalent to finite current carrying conductors, analytical equations are derived to compute the magnetic flux density at any point in space. The results are verified by using finite‐element method (FEM) simulations of rail electrodes. The expressions are then used to compute the Lorentz force on the arc in SWASTIK contacts. The analytical predictions are compared with three‐dimensional FEM simulations of a CAD model of the contacts. Applicability of the analytical results is investigated in the context of parametric variation of the radius, length and position of the arc and temporal variation of the contact current. The present work can be used in the first iteration of contact petal design. It is also applicable for the design of rail gun geometries. [ABSTRACT FROM AUTHOR]

Electromagnetic forming (EMF) is a processing technology using pulsed electromagnetic force to achieve a high forming speed. It draws wide attention because it significantly improves metal material formability. At present, the electromagnetic force is ordinarily generated in the whole workpiece area during the EMF process, which results in a conical contour of formed workpiece with poor forming performance. Therefore, this paper proposes a method named Electromagnetic Forming with Local Loading (EMFLL), in which the electromagnetic force is mainly generated in the specific area of the workpiece. By using ANSYS Software, it gives the simulations for the analysis of the magnetic flux density distribution and the electromagnetic force distribution in the EMFLL process with the new type of coil. The obtained results show that the electromagnetic force generated by the new type of coil is more concentrated. Finally, a series of experiments on the traditional EMF and EMFLL of AA5052 with a diameter of 160 mm and a thickness of 2 mm has been carried out, the experimental results show that a well-proportioned deformation at the bottom of the workpiece is achieved by EMFLL, which verifies that EMFLL has some certain potential in lightweight alloy processing. [ABSTRACT FROM AUTHOR]

To adjust the flow rate of liquid in the pipeline in real-time in the process of crop drip irrigation, to achieve sustainable agricultural irrigation. This paper designs and develops a kind of liquid speed-regulating device for drip irrigation based on traveling wave magnetic field. This paper aims to use the electromagnetic driving force generated by the traveling wave magnetic field to realize the soft control of liquid flow rate in drip irrigation pipelines. First of all, the structure of the combined traveling wave magnetic field generator was designed. COMSOL physical field simulation software was used to build the traveling wave magnetic field simulation model, and the magnetic field distribution diagram and the variation curve of the magnetic field intensity were generated in the time domain. Then, through the analysis of the simulation model, the harmonic interference of a single row and combined traveling-wave magnetic field generator is compared, and the optimal spacing between the traveling-wave magnetic field generator units is determined. Finally, the water-fertilizer fusion liquid used in the process of agricultural irrigation was selected and the liquid speed regulation experiment was carried out. The experimental results show that the combined liquid speed regulating device can effectively reduce the number of traveling wave field harmonics, compared with the single wave field generator at the same power, the magnetic field intensity is increased by 33.9 %. When the excitation current is 2 A and the initial flow rate is 0.5 m/s, the device can increase the flow rate of water-fertilizer fusion liquid for agricultural drip irrigation by 2.27 % and decrease by 2.13 %, which can meet the real-time and effective speed regulation requirements of water-fertilizer fusion liquid in the process of agricultural drip irrigation. • A kind of liquid speed regulating device for drip irrigation network based on traveling wave magnetic field was designed and developed. • Using the electromagnetic driving force generated by the traveling wave magnetic field acting on the flowing liquid, the soft control of liquid flow rate in drip irrigation pipeline was realized. • In the process of integrated water and fertilizer drip irrigation, the traveling wave magnetic field is used to real-time control the flow rate of liquid in the branch pipe of drip irrigation network, so as to meet the changes in the water and nutrient demands of crops and realize sustainable agricultural irrigation. [ABSTRACT FROM AUTHOR]

In this investigation, an optimal design procedure for tubular linear brushless permanent magnet (PM) machines has been proposed. A two-dimensional analytical magnetic field model in cylindrical coordinates has been employed to quickly and accurately calculate the magnetic flux density distribution and electromagnetic force. The objectives of the optimization problem are to simultaneously minimize the power losses and machine volume and the constraints are to ensure to develop the required level of electromagnetic force and to avoid saturation in the back-iron. The optimization problem has been solved using two types of metaheuristic optimization techniques, i.e., particle swarm optimization (PSO), and fuzzy adaptive PSO (FAPSO). The design procedure has been implemented on a case study to illustrate the capability of the proposed approach. [ABSTRACT FROM AUTHOR]

The paper offers a methodology for the identification the time harmonic interactions with a strong negative impact on the rotor of a high power induction machine. These potentially dangerous pulsating torques may be effectively reduced by carefully setting the machine’s drive control. A novel approach based on a complex finite element model and further post-processing is used. Results obtained from electromagnetic calculations in the form of pulsating torques are used as mechanical loading of a structural dynamic model. This complex model intended for rotor vibration analysis is described in brief in the mechanical part of the paper. The proposed methodology is applied to the machine used as a propulsion unit for multisystem locomotives of 1600 kW power. [ABSTRACT FROM AUTHOR]

• A nano-torque generating machine has been developed using electromagnetic force. • Geomagnetism was investigated using a measurement system based on quantum mechanics. • Uncertainty of torque realized by a nano-torque generating machine has been estimated. • Generation of an SI-traceable torque of about 0.2 nN·m to 1 mN·m was successful. In the present study, we developed a torque generating machine using an electromagnetic force based on the principle of the Kibble balance method in order to realize a nano-torque traceable to the International System of Units (SI). In order to realize a nano-torque, the size and number of turns of the rectangular coil as well as the magnetic flux density must be reduced. However, when the magnetic flux density is reduced, there is concern about the influence of geomagnetism and other factors. Therefore, we first evaluated the influence of such factors on the machine using a method based on quantum mechanics. As a result, it was found that the influence of geomagnetism on the device is approximately 1 % of the magnetic field formed by the Helmholtz coil at maximum. In addition, the variation of the geomagnetic field during the time of the nano-torque experiment was found to be very small. The torque realized by an electromagnetic force was in the range of approximately 0.2 nN·m to 1 mN·m. Furthermore, the uncertainty in the realized torque was evaluated. Finally, an SI-traceable nano-torque was successfully realized using an electromagnetic force. [ABSTRACT FROM AUTHOR]

Transient electromagnetic forces in radial and axial directions induce critical mechanical stress on windings and transformers. In this paper, short-circuit electromagnetic forces that are exerted on transformer windings are investigated. A 3-D transformer model is considered to calculate the transient electromagnetic forces. The magnetic vector potential, magnetic flux density, and electromagnetic forces due to the short-circuit transient currents applied to the power transformer are analyzed by a coupled electromechanical finite-element method. The results obtained are compared with the analytical results and show good agreement. The numerical modeling technique dealt with in this paper is expected to be useful in the design of power transformers. [ABSTRACT FROM AUTHOR]

Magnetically impelled arc butt (MIAB) welding is a unique forge welding process in which an arc is drawn in the gap between the two tubes to be welded in order to raise them to a high temperature to allow forging to form a solid-state weld. In this case, the arc is rotated with a high speed around the weld line by an electromagnetic force resulting from the interaction of the magnetic field and the arc current. This paper presents the details of the results and the conclusions of the experimental trials conducted on the MIAB module designed and developed based on the principle. Further, nonlinear electromagnetic analysis has been performed to determine the magnetic field and electromagnetic force distribution in MIAB process using finite element package ANSYS. Typical results of this analysis pertaining to magnetic field are compared with the experimental data for steel tubes (outer diameter 47 mm and thickness of 2 mm). It is observed that the results from finite element analysis and the experimental trials are in excellent agreement. The proposed three-dimensional finite element method model for electromagnetic force distribution facilitates comprehensive understanding of the arc rotation process in MIAB welding. [ABSTRACT FROM AUTHOR]

This paper proposes a 3-Dimensional Finite Element Model (FEM) for the simulation of magnetic flux distribution in a Magnetically Impelled Arc Butt (MIAB) welding process. The electromagnetic force responsible for the arc rotation in MIAB welding process is governed by the magnetic flux density in the gap, the arc current and the arc length (gap size). To be precise the radial magnetic flux density is a critical factor in arc rotation and weld quality. The aim of this study is to explore the interdependence of the magnetic flux density and the existing current in the coils using finite element code ANSYS. The results of this analysis are verified with the available experimental data for steel pipes (outer dia 50mm and 2mm thickness). The results of the numerical simulation emphasize that the magnetic flux density in the gap between the pipes is proportional to the exciting current. [ABSTRACT FROM AUTHOR]

This paper focuses on the mechanical, dynamic numerical modelling of an electrical-current-carrying cable using a non-linear absolute nodal coordinate formulation. The derived equations are an expansion of the mechanical equation of motion. They allow interdisciplinary mechanical and electrical research of the cable dynamics where large electrical currents are present in the cables. A vector of the generalised electromagnetic forces in the absolute nodal coordinate formulation for a current-carrying finite element of arbitrary length is derived. For the cable elements a filament approach is used to determine the magnetic flux density. To round off the method's applicability, the contact forces that can occur between free-moving cables are also considered. The generalised electromagnetic forces are derived and expressed with the pre-computed matrices. As the numerical testing shows, the presented method is computationally very effective. The equations are general and can be applied to any similar dynamic systems. • The ANCF equations of motion are expanded with the generalised electromagnetic forces. • These allow interdisciplinary mechanical and electrical research of the cable dynamics. • The ANCF electromagnetic force is presented in integral and line segment forms. • The proposed line segment approach is very computationally cost effective. [ABSTRACT FROM AUTHOR]