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Magnetic pulse welding realizes solid-state connection through a high-speed collision of materials, which can effectively overcome the welding difficulties of light metal materials. In the magnetic pulse welding system, in order to improve the welding efficiency, a field shaper is usually applied between the multi-turn coil and the workpiece to concentrate the magnetic field in the welding area, thereby improving the electromagnetic force. However, a large number of researchers are currently on the tube-welded field shaper, and very few researchers have studied the structure of the plate-welded field shaper. Therefore, this paper proposed a new field shaper for plate welding. The effect of the structure parameter of the field shaper on the magnetic field and electromagnetic force on the aluminum plate was analyzed in the COMSOL multiphysics software. The optimal structure parameters of the field shaper were selected. The plastic deformation and the generation of jets under different voltages and the welding of the same/dissimilar metal materials at different standoff distances were studied experimentally, which verifies the feasibility of the new field shaper. [ABSTRACT FROM AUTHOR]

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]

In the present study, author analyses the vibration of protein microtubules and its interaction with the surrounding elastic medium and electromagnetic and gravitational forces. Protein microtubules are dynamic Nano fibers found inside the cell's cytoplasm, strengthening the cytoskeleton and gives shape to the cell. When the cell undergoes deformation microtubules vibrate. Understanding the vibration of these Nano fibers within the elastic medium and along with the body forces as electromagnetic and gravitational forces is crucial. The main purpose of this study is to explore the effects of surrounding elastic medium and electromagnetic and gravitational forces on the vibration of protein microtubules. The findings reveal that the effects of surrounding medium and the external influences on the vibration of these Nano fibers are significant. The study presents the numerical values in the form of table associated with microtubules in various conditions: free, embedded, and in the presence of electromagnetic and gravitational forces. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A performance evaluation system (PES) can experimentally test the structural stability and magnetic field effects of HTS coils against high magnetic fields and electromagnetic forces before mounting the HTS coils on a large-capacity rotating machine. This paper deals with the characteristic analysis of electromagnetic force in an HTS field coil for a 10 MW Class HTS Wind Power Generator using PES. Based on the designed 10 MW class HTS wind power generator, the HTS coils are manufactured and installed in the PES by a support structure, which is designed considering the electromagnetic force (torque) and heat loads in the HTS coil. To check the stress and deformation in the support structure caused by the electromagnetic force generated from the coil, strain gauge sensors were attached to the support structure and measured under full-load conditions. As a result, the maximum magnetic field and electromagnetic force are 2.8 T and 71 kN, respectively. Compared to the analysis results, the magnetic field and generated electromagnetic force in the HTS coil were the same under no-load and full-load conditions. These results will be effectively used to study and fabricate high magnetic field coils for HTS applications, as well as the PES being fabricated. [ABSTRACT FROM AUTHOR]

During the driving process of the in-wheel drive electric vehicle, the air gap eccentricity of the motor caused by external disturbance cannot be avoided, resulting in a negative effect on vehicle dynamics. In this paper, the negative effect of vehicle lateral dynamics caused by motor-inclined eccentricity and the corresponding control method are studied. According to the Maxwell stress tensor and the air gap permeance correction coefficient, the unbalanced radial force under the inclined eccentricity of the in-wheel motor is characterized, and the corresponding vehicle dynamics model is established. Based on the vehicle dynamics model, different steering conditions are set to explore the influence of inclined eccentricity on the negative effect of vehicle lateral dynamics. It is found that the inclined eccentricity affects the handling stability of the vehicle under normal conditions and affects the rollover stability under extreme conditions. In order to solve these problems, the integrated control strategy is formulated by using the steering and driving system of an electric vehicle, and the particle swarm optimization algorithm is introduced to optimize it. The simulation results show that the proposed integrated optimal control of active rear-wheel steering and direct yaw control can effectively alleviate the negative effect of vehicle lateral dynamics caused by the inclined eccentricity of the in-wheel motor under different working conditions. [ABSTRACT FROM AUTHOR]

Copyright of Automotive Engineer (1674-6546) is the property of Auto Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wireless charging for UAVs (unmanned aerial vehicles) is a significant development in the field of robotics and aerial technology. It has the potential to revolutionize the way UAVs are used and deployed, by eliminating the need for tethers and cables to provide power. However, electromagnetic force will be generated due to the interaction between coupled magnetic field and moving charge. Especially in the space isolation environment, the coil structure will produce non-contact free movement under the action of electromagnetic force, which has a side effect on the safe operation of the system. This paper analyses the characteristics of electromagnetic force on the coil structure, proposes an optimization method to reduce the electromagnetic force, and verified the optimized structure by simulation. According to the results, the electromagnetic force on the optimized coil structure is significantly lower than that of the traditional coil structure. [ABSTRACT FROM AUTHOR]

This article presents a detailed analysis of the electromagnetic force and vibration behavior of a new axial flux permanent magnet (AFPM) machine with a yokeless stator and interior PM rotor. Firstly, the configuration of an AFPM machine with a dual rotor and a sandwiched stator is introduced, including the structural design, fixation of the yokeless stator and segmented skew rotor structure. Then, the influence of anisotropic material and a fixed structure on stator modes is analyzed, including elastic modulus, shear model, the skew angle of slot and the thickness of stator yoke. Furthermore, a new non-equally segmented skew rotor structure is proposed and calculated for the reduction in vibration based on the multiphysics model. Three different segmented skew rotor schemes are compared to illustrate the influence of reducing vibration and noise. The predicted results show that the effect of the non-equally segmented skew rotor on reducing vibration is better than the other two schemes. Finally, a 120 kW AFPM motor is experimented with and the result matches well with the predicted data. The vibration performance of the AFPM motor with a dual rotor and sandwiched yokeless stator is revealed comprehensively. [ABSTRACT FROM AUTHOR]

In response to the problems of insufficient electromagnetic driving force and slow response speed of electromagnetic valves under the constraints of driving power and electromagnetic valve volume, the dynamic and static features of electromagnetic valves are analyzed. Through simulation analysis and prototype experiments, it is verified that improving the intrinsically safe electromagnetic force can significantly improve the response features of electromagnetic valves. A plan to improve the response features of electromagnetic valves by optimizing the electromagnetic force is determined. The evaluation indicators for the features of intrinsically safe electromagnets, including effective stroke index, average electromagnetic force index, and static comprehensive performance index, have been proposed to solve the problem of difficult performance evaluation of electromagnets caused by different stroke. The Maxwell electromagnetic simulation software is used to analyze the effects of changes in guide tube depth, armature radius, non working air gap, non working air gap, and pot mouth height on the static features of the electromagnet. The sensitivity of different parameters to the static features is obtained, providing a reference for selecting the size control range in parameter optimization. A second-order response surface model is constructed based on the results of orthogonal experiments to evaluate the comprehensive features of electromagnets using iron core structural parameters. Genetic algorithm is used to optimize the iron core parameters. The prototype test results show that the optimized electromagnetic force in the horizontal section of the electromagnet has increased by 56%, the effective stroke has increased by 26%, and the opening response time of the intrinsically safe electromagnetic valve has been shortened by 52.5%.

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]

In order to achieve automatic fast reset of the falling-body (FB) viscometer, and reduce the volume of the device and the amount of sample used, this paper proposes to use a single coil to reset the FB and use another single coil to measure the FB position. In this paper, the characterization ability of the sensing coil impedance to the FB position and its influencing factors, and the reset ability of the driving coil to the FB and its enhancement factors, are studied via electromagnetic finite element simulations and experiments. There is a linear zone between the FB position and the sensing coil impedance, with the slope being largest. The lower limit of the FB motion should be designed in this linear zone to accurately determine the moment when the FB reaches the lower limit point. Increase in the FB height, and in the number of turns of the sensing coil, and decrease in the wire diameter are beneficial to the FB positioning. There is a maximum force point when the FB approaches the driving coil, and the FB's motion range needs to cover this point for reliable reset. Using iron plugs allows the FB to obtain greater electromagnetic attraction and ensure its successful reset. Experimental results show that the device requires only 1 mL of sample to measure liquid viscosity. For 9.5-1265 mPa·s dimethyl silicone oil, the average absolute value of the relative measurement error is 0.22% and the maximum value is 4.3%. [ABSTRACT FROM AUTHOR]

Short‐circuit forces, which result in violent vibration of power transformer windings, are induced by the interaction between the short‐circuit currents and the leakage magnetic induction. During vibration, the rearrangements of disks affect the magnetic flux distribution, which leads to time‐varying equivalent reactance and further changes of currents and forces. When a short‐circuit accident occurs, these processes happen simultaneously and constantly. In this article, the influence of circuit parameters on short‐circuit currents is analyzed. The strongly coupled phenomenon between equivalent circuit, magnetic field and structural field is explicated, and the method to obtain vibration process with strongly coupled phenomenon considered is proposed. Then the strongly coupled effect on vibration process is investigated. The vibration process is characterized by the time‐varying currents, electromagnetic forces and displacements. The space coefficient is defined to represent the magnetic flux distribution. The changes of maximum value and its occurrence time of the characteristic parameters are obtained. The peak values of the short‐circuit forces and displacements increase and the waveforms change, which is caused by the distortions of leakage magnetic flux and the changes of spatial ampere‐turn balance during vibration. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this research, a micromirror driven by electromagnetic force is designed and fabricated. The micromirror features a microfabricated L-shaped spring for large deflection and a bulk permanent magnet with a size of 1 × 1 × 1.5 mm3 mounted on the micromirror for generating electromagnetic actuation force. The device has a footprint of approximately 10 × 10 mm2. The design of the micromirror is based on Castigliano's theorem, theoretic spring constant evaluation, and finite element analysis, which are applied to estimate the deflection. The fabricated micromirror can be actuated at the resonance frequency in the atmosphere. The piston vibration at a fundamental frequency of 26.6 Hz is desirable for Michelson interferometers. An 830 µm stroke is achieved by applying 1 Vpp at the resonance frequency, and a 4.44° tilting angle is observed. Overall, the large stroke of the fabricated micromirror implies that the electromagnetic micromirror is promising for high-resolution interferometer applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microwave heating has the characteristics of simple control and high efficiency, in which electromagnetic force plays an important role. Using the UDF function and energy equation in FLUENT software, the electromagnetic force model in the tube is established. The mixing process of cerium chloride solution under different heating modes, the mixing effect of Lorentz force and the preparation process of cerium oxide under different inlet material velocities were numerically simulated. CFD-Post and MATLAB software are used to post-process the data of the whole fluid area. Through the above analysis, the best process conditions of numerical simulation and experiment are finally determined. The results show that microwave heating has better mixing effect and lower material loss compared with conventional heating, in which electromagnetic force plays a promoting role; Under the condition of microwave heating, the product conversion rate is high, and the concentration of cerium oxide is high and distributed evenly. The more appropriate mixing method of cerium chloride and preparation method of cerium oxide are microwave heating, and the more appropriate inlet velocity of materials is 0.15 m/s.

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]

To reduce the interference from the electromagnetic force caused by coupling coils due to distance changes in a wireless power transfer (WPT) system, this paper conducts a theoretical analysis of the factors influencing the electromagnetic force experienced by the receiving coil. Maxwell electromagnetic simulation is used for modeling and analysis, revealing the trends in the electromagnetic force exerted on the receiving coil. Based on this analysis, a method is proposed that actively adjusts the working frequency of WPT to alter the current phases of the transmitting and receiving coils, thereby regulating the magnitude of the force on the receiving coil. Finally, mechanical tests, including torque experiments, were conducted to validate the proposed method. The electromagnetic force on the coil in the microgravity isolation platform of a space station was reduced from 961   μ N to 113   μ N , a level which plays an important role in improving the microgravity index of the system. [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]

The paper presents a detailed theoretical analysis of the electromagnetic forces in the arc plasma and the weld pool metal in Tungsten Inert Gas (TIG) welding at direct current (DC) and high-frequency pulse current (HFPC) modulation with a frequency of 10 kHz. The electromagnetic (Lorentz) force, acting on arc plasma and metal is presented via potential (magnetic pressure) and rotational (equivalent electromagnetic force) force components. This approach allows us to substantially simplify the analysis of the Lorentz force effect on the arc plasma and weld pool metal under different arc burning modes. It was shown that in HFPC TIG welding with a given frequency, the effect of modulated current on the arc plasma is inherently non-stationary, whereas the effect on the weld pool metal is determined by the time-averaged magnitude of electromagnetic force throughout the period of current modulation. The proposed approach serves as a basis for numerical analysis of the electromagnetic forces in arc plasma and weld pool metal during DC and HFPC modes of the welding process. We established that the application of HFPC modulation promotes a greater intensity of both the gas-dynamic processes in the welding arc, thereby significantly increasing the pressure on the weld pool surface, and convective heat transfer from the most heated central region near the weld pool surface towards the weld pool bottom. Both these factors lead to an increase of the arc penetrability in the case of the HFPC mode compared with the DC mode, all other conditions being equal. • Only rotational part of the Lorentz force initiates vortical flow. • Square-wave pulse is used as a welding current wave form. • Non-stationary magnetic field diffusion equation is solved numerically. • In-house Wolfram Language code is used for FEM-analysis. • HFPC modulation increases the effective driving force in the weld pool. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A compound varifocal lens based on electromagnetic drive technology is designed and fabricated, where the polydimethylsiloxane (PDMS) film acts as a driving component, while the PDMS biconvex lens and the plane-concave lens form a coaxial compound lens system. The plane-concave lens equipped with driving coils is installed directly above the PDMS lens surrounded by the annular magnet. When different currents are applied, the annular magnet moves up and down, driving the PDMS film to undergo elastic deformation, and then resulting in longitudinal movement of the PDMS lens. The position change of the PDMS lens changes the focal length of the compound lens system. To verify the feasibility and practicability of this design, a prototype of our compound lens system is fabricated in experiment. Our proposed compound lens shows that its zoom ability reaches 9.28 mm when the current ranges from −0.20 A to 0.21 A. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 short-circuit faults in the untapped portion of the regulating windings, offering crucial technical support for fault diagnosis and prevention of power transformers.

During the normal life of the transformers, they are subjected to different electromagnetic stresses. One of these stresses is the electromagnetic forces resulting from the passage of short-circuit current in the transformer coils due to internal or external faults and may lead to the failure of the transformer when this electromagnetic force exceeds the threshold level. This work deals with the computation and analysis of leakage magnetic flux and electromagnetic forces when the worst-case fault (symmetrical short-circuit current) occurs in distribution transformer (DT) coils using the finite element method (FEM). The three types of DTs that were adopted in this work are similar in capacity and voltage transformation ratio (250 kVA and 11,000/416 V), but they are different in the shape of coils (oval, cylindrical, and rectangular coils).

As the wide application of power electronics devices, supply containing low-order harmonic becomes more and more common in industry. It may cause the significant vibration of induction motors (IMs). This study firstly analyzed the time-space distribution characteristics of the additional electromagnetic force caused by the low-order harmonics in supply. Then, an improved concentric and unequal-turn windings is designed and its impact on unconventional vibration of IMs is also analyzed. The increase ratio of force amplitude between the force in different cases is defined, by which the force characteristics of IMs with supply containing low-order harmonics and concentric and unequal-turn windings can be revealed under different load conditions. With a 32-kW IM, harmonic response analysis and experimental validation are also carried out, the results show that, with concentric unequal-turn winding, the vibration in different frequency bands can be reduced effectively, the average vibration can be suppressed from 89.7dB to 86.9dB.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A performance evaluation system (PES) can experimentally test the structural stability and magnetic field effects of HTS coils against high magnetic fields and electromagnetic forces before mounting the HTS coils on a large-capacity rotating machine. This paper deals with the characteristic analysis of electromagnetic force in an HTS field coil for a 10 MW Class HTS Wind Power Generator using PES. Based on the designed 10 MW class HTS wind power generator, the HTS coils are manufactured and installed in the PES by a support structure, which is designed considering the electromagnetic force (torque) and heat loads in the HTS coil. To check the stress and deformation in the support structure caused by the electromagnetic force generated from the coil, strain gauge sensors were attached to the support structure and measured under full-load conditions. As a result, the maximum magnetic field and electromagnetic force are 2.8 T and 71 kN, respectively. Compared to the analysis results, the magnetic field and generated electromagnetic force in the HTS coil were the same under no-load and full-load conditions. These results will be effectively used to study and fabricate high magnetic field coils for HTS applications, as well as the PES being fabricated.

The processes of creating an electromagnetic force acting on the molten metal in the active zone of a magnetodynamic pump are studied depending on the spectral composition of the higher harmonic components of the current in the channel and the induction of the magnetic flux induced by an electromagnet. The peculiarities of the regulation of the magnitude and direction of the resultant vector of this force, the favorable conditions of the vibrational action on the molten metal in the active zone are defined. Ref. 8, fig. 4, tables 3.

Stator asymmetric-paths winding of variable speed pump storage (VSPS) generator-motor can solve the problem of mismatch of unit speed, capacity and outlet voltage. However, different winding connection schemes will lead to the change of magnetomotive force (MMF) asymmetry of each branch, and then affect the electromagnetic force of generator-motor. In order to explore the effect of this winding type on the electromagnetic force, stator asymmetric-paths winding's MMF and electromagnetic force of 336 MW VSPS generator-motor is derived. Waveforms and harmonic contents of the stator asymmetric-paths winding MMF of the equal-pitch and unequal-pitch schemes are analyzed. Under the consideration constraints of factors such as minimizing MMF asymmetry and electromagnetic vibration, a reasonable asymmetric-paths winding scheme with unequal pitch is determined It is concluded that asymmetric-paths winding scheme with pitch of 14-15-16 can effectively weaken the low-order MMF harmonics and reduce the electromagnetic force under the limitation of asymmetric-paths winding form. The finite element model of VSPS generator-motor is further developed, and the electromagnetic force amplitude and spatial and temporal distribution characteristics under 6 winding schemes are calculated to verify the accuracy of the calculation model. The results of the study can provide technical support for the development of localized VSPS generator-motor.

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.

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study is to examine and analyze the axial and radial forces, electromagnetic forces (EMFs) acting on the low and high-voltage windings of an amorphous core transformer via the two different approaches: an analytic approach and a 3-D finite element method (FEM). Firstly, the analytic method is proposed to analyze the distribution of leakage magnetic field in the magnetic circuit and the forces acting on the transformer windings. The FEM embedded in the Ansys Maxwell tool is then proposed to compute and simulate the axial and radial forces under three different operating conditions: no-load, rated full-load, and short-circuit. The obtained results from two different methods such as the rated voltage, rated current, short-circuit current, axial and radial forces and EMFs in the low and highvoltage windings are finally compared to illustrate an agreement of methods. The validation of the methods is applied on a three-phase amorphous core transformer of 1600kVA-22/0.4kV. [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]