Electromagnetic-mechanical Coupling Research Articles

An Advanced Computational Approach for Evaluating Screening-Current-Induced Strain in REBCO HTS Coils Considering Electromagnetic-Mechanical Coupling

An Advanced Computational Approach for Evaluating Screening-Current-Induced Strain in REBCO HTS Coils Considering Electromagnetic-Mechanical Coupling

The influence of ITSF on vibration of high voltage Line-Start permanent magnet synchronous motor

PurposeThe purpose of this paper is to present the influence of inter-turn short circuit faults (ITSF) on electromagnetic vibration in high-voltage line-starting permanent magnet synchronous motor (HVLSPMSMS).Design/methodology/approachIn this paper, the ampere–conductor wave model of HVLSPMSM after ITSF is established. Second, a mathematical model of the magnetic field after ITSF is established, and the influence law of the ITSF on the air-gap magnetic field is analyzed. Further, the mathematical expression of the electromagnetic force density is established based on the Maxwell tensor method. The impact of HVLSPMSM torque ripple frequency, radial electromagnetic force spatial–temporal distribution and rotor unbalanced magnetic tension force by ITSF is revealed. Finally, the electromagnetic–mechanical coupling model of HVLSPMSM is established, and the vibration spectra of the motor with different degrees of ITSF are solved by numerical calculation.FindingsIn this study, it is found that the 2np order flux density harmonics and (2 N + 1) p order electromagnetic forces are not generated when ITSF occurs in HVLSPMSM.Originality/valueBy analyzing the multi-harmonics of HVLSPMSM after ITSF, this paper provides a reliable method for troubleshooting from the perspective of vibration and torque fluctuation and rotor unbalanced electromagnetic force.

A numerical simulation method for solving electromagnetic-mechanical coupling field

A new numerical simulation method based on the finite volume method has been proposed to address the challenges associated with the pseudo-oscillation phenomenon that occurs with an increased Péclet number, as well as determining an appropriate time step for electromagnetic-mechanical coupled physical field calculations. This method utilizes the concept of upwind from Computational Fluid Dynamics (CFD) to solve Maxwell's equations, a finite-volume method for discretizing the electromagnetic diffusion equations. Through computing typical electromagnetic field problems such as TEAM problem 9–1 and comparing the results to the literature, it has been confirmed that this method has sufficient computational accuracy to solve electromagnetic field numerical simulation problems containing moving conductors. Additionally, a three-dimensional simulation model of the electromagnetic coil gun has been established to verify the viability of the proposed method for solving magnetic field problems under the electromagnetic launch (EML) system. The study also examined the change in magnetic field strength and current density of the EML device during the launching process. The results lay the foundation for the technical application of this method.

New approach for determining the fracture parameters by electromagnetic-mechanical coupling

This paper introduces a novel method for assessing fracture mechanics parameters such as Stress Intensity Factor (SIF), Energy Release Rate (J) and Crack Tip Opening Displacement (CTOD). An electromagnetic–mechanical coupling (EMC) approach is employed to evaluate and to measure these fracture parameters by monitoring the variation of impedance using eddy currents. This approach relies on the eddy current signal obtained from a sensor, which calculates and verifies SIF parameters along with the J-integral and CTOD through changing the sensor impedance. To ensure theoretical consistency, the magnetic field is theoretically used, formulated and verified. Additionally, a numerical simulation method employing the finite element method is used to analyze and identify cracks in structures and assess their propagation. The quantification of SIF and J-integral parameters is demonstrated using two sensors based on a differential probe. This research paper demonstrates that the proposed method is the most efficient approach for exploring and detecting cracks in materials, as well as understanding their propagation behavior.

Screening-current-induced magnetic fields and strains in a compact REBCO coil in self field and background field

REBa2Cu3O7−x (REBCO) coated conductors, owing to its high tensile strength and current-carrying ability in a background field, are widely regarded a promising candidate in high-field applications. Despite the great potentials, recent studies have highlighted the challenges posed by screening currents, which are featured by a highly nonuniform current distribution in the superconducting layer. In this paper, we report a comprehensive study on the behaviors of screening currents in a compact REBCO coil, specifically the screening-current-induced magnetic fields and strains. Experiments were carried out in the self-generated magnetic field and a background field, respectively. In the self-field condition, the full hysteresis of the magnetic field was obtained by applying current sweeps with repeatedly reversed polarity, as the nominal center field reached 9.17 T with a maximum peak current of 350 A. In a background field of 23.15 T, the insert coil generated a center field of 4.17 T with an applied current of 170 A. Ultimately, a total center field of 32.58 T was achieved before quench. Both the sequential model and the coupled model considering the perpendicular field modification due to conductor deformation are applied. The comparative study shows that, for this coil, the electromagnetic–mechanical coupling plays a trivial role in self-field conditions up to 9 T. In contrast, with a high axial field dominated by the background field, the coupling effect has a stronger influence on the predicted current and strain distributions. Further discussions regarding the role of background field on the strains in the insert suggest potential design strategies to maximize the total center field.

High-efficiency computation for electromagnetic forming process: An explicit-implicit GPU approach

Low computational efficiency is one of the crucial challenges in electromagnetic forming process simulation. However, the huge gap in switching from the electromagnetic field to mechanics hinders the development of high-efficiency parallel coupling. A graphics processing unit (GPU)-based explicit-implicit coupling method is proposed to address the high-computational cost in simulations of the electromagnetic forming process, in which the large deformation (explicit) and electromagnetic field (implicit) are intimately coupled. The electromagnetic-mechanical coupling is achieved by constructing five parallel algorithms, which include the parallel operations of vector-vector, matrix-matrix, matrix-vector, vector assembly, and matrix-free assembly parallel preconditioned conjugate gradient algorithm. The high-efficiency GPU parallel computing is realized through the special data storage structure and parallel strategies. The explicit-implicit GPU method is validated against the experimental results, and several examples are presented for simulations of the electromagnetic forming process to illustrate both the accuracy and high-efficiency parallel acceleration performance of the present program.

Design, optimization, and characterization of an XY nanopositioning stage with multi-level spatial flexure hinges for high-precision large-stroke motion guidance.

Establishing a novel design and accurate analytical models for XY nanopositioning stages based on voice coil motor (VCM) actuators is critical to achieving an optimal working performance. To overcome the existing design challenges of 2-degree-of-freedom guiding mechanisms, a four-layer structure composed of L-shaped spatial double parallelogram flexure mechanisms was proposed for the magnetic stage, which exhibits light weight and inhibits parasitic and decoupled motions. The guiding mechanisms were modeled by the compliance matrix method. Thereafter, by combining an electromagnetic model for the VCMs with the equivalent magnetic network method, an electromagnetic-mechanical coupling optimization method with multiple constraints was proposed for the stage to achieve a millimeter-range motion with a maximized natural frequency. The mechanical and electromagnetic performances were then verified by finite element analysis software. The optimized prototype was tested with a stroke of ±3.41 and ±3.08mm for X axis and Y axis, respectively, a closed-loop resolution of 100nm for X axis and 150nm for Y axis, and a resonant frequency of 11.75Hz for both axes. The tracking of a 0.1Hz spiral of Archimedes achieved a maximum tracking error of 2.9%.

Experimental Study on the Active Control and Dynamic Characteristics of Electromagnetic Active–Passive Hybrid Vibration Isolation System

Targeting the problems of conventional active–passive hybrid vibration isolation systems, such as low output force, poor bearing capacity, large power loss and inability to withstand strong impacts, this paper proposes an active–passive hybrid vibration isolation system combining an electromagnetic actuator, rubber passive vibration isolator and magnetorheological damper. The overall design of the hybrid vibration isolation system is first introduced. Then, a two-dimensional electromagnetic frequency-domain simulation is carried out on the electromagnetic actuator to obtain the output characteristics. A three-dimensional modeling is conducted to simulate the electromagnetic–mechanical coupling in the time–frequency domain to obtain nephograms of the magnetic flux diffusion distribution and power loss. Then, a dynamic stiffness test is carried out on the rubber vibration isolator to obtain the dynamic stiffness characteristics and the damping angle curve. At the same time, an adaptive suppression filtered-x least mean square (ASFXLMS) algorithm is proposed to adjust the update of the control weight coefficients to ensure that the current signal does not exceed the effective operating range of the actuator when the electromagnetic actuator is subjected to strong external disturbances. Finally, a hybrid vibration isolation system-based active vibration isolation experimental platform is built, and multifrequency line spectra active–passive vibration isolation experiments are carried out. The results demonstrate that the hybrid vibration isolation system has good control effects in the time–frequency domain and shows good robustness when subjected to impact.

Electromagnetic-mechanical coupling analysis of high-temperature superconducting racetrack coil

The second-generation high-temperature superconducting (HTS) coated conductor has been recognized as one of the most promising materialsfor high field magnets due to its superior electromagnetic and mechanical performances. HTS racetrack coils wound with the coated conductors are an extensively used configuration in engineering applications, such as HTS machines and high-speed maglevs. In this paper, in order to analyze the electromagnetic and mechanical behaviors of HTS racetrack coils, a 3D coupled electromagnetic-mechanical model is used to consider the effect of coil deformation and the strain dependence of critical current. The effectiveness of the coupled model is validated by comparing the numerical results with experimental data in the literature. A numerical simulation of a 3D HTS racetrack coil subjected to an external electromagnetic field is carried out using coupled and uncoupled models. The results indicate that the structure deformation can reduce the penetration depth of the screening current, and the hoop stress and strain are mainly concentrated on the circular part of the racetrack coil. Afterwards, the influences of various parameters on the electromagnetic and mechanical responses of the HTS racetrack coil are also investigated.

Electromagnetic-mechanical coupling analysis and optimization method of electromagnetic vibroseis

Electromagnetic vibroseis is an important seismic wave excitation device. At present, the research of electromagnetic vibroseis mainly focuses on application and prototype design, lacking research on electromagnetic-mechanical coupling. Analyzing the electromagnetic-mechanical coupling and optimizing the air gap magnetic field is of great significance to improve the excitation quality of low-frequency seismic waves. In this paper, the electromagnetic-mechanical coupling is analyzed by studying the parameter force factor, and two novel optimal designs of the air gap magnetic field are proposed. Firstly, the finite element model of the air gap magnetic field is established, and the influence of the force factor distribution curve on the vibration signal is analyzed by using the Gaussian function and parameter spline difference method. Further, an asymmetrical axial dual-magnet design is proposed to enhance the radial magnetic induction intensity in the air gap. The design of adding a radial magnet to the outer yoke is proposed to compensate for the nonlinearity of the in the air gap. The simulation results show that the asymmetric axial dual-magnet structure increases the by 22.2% compared with the axial single-magnet structure. Adding a radial magnet to the outer yoke reduces the amplitude ratio of the third harmonic to the fundamental wave from 23.24% to 4.66%. It is necessary to consider the influence of the height of the driving coils on the maximum displacement, force factor distribution curve, and harmonic distortion.

Analysis Method Development of Hybrid Linear Motor Considering Cogging Force Effect

This study examines the distributions of the cogging and current forces in a hybrid linear motor and their impact on its performance. Subsequently, using the Maxwell stress tensor to analyze the force acting on the motor, a method has been proposed for calculating the cogging force effect on the mechanical system stiffness. Based on the force profile, it was found that the cogging force was a noncurrent force that could reduce the spring stiffness of a hybrid linear motor when it is in operation. An electromagnetic–mechanical coupling analysis was conducted to calculate the displacement and acceleration of the hybrid linear motor on a dummy jig. The experimental and analytical results were in good agreement, indicating that the proposed method is accurate and reliable.

A study on the shaft stability and prediction of electromagnetic and NVH characteristics of permanent magnet synchronous machine according to the different pole/slot combination

In this study, electromagnetic noise sources of permanent magnet synchronous motors with 8-pole 9-slot and 12-slot fractional slot concentrated windings were analyzed through finite element analysis, and the radiated noise/vibration levels were compared through structural-acoustic analysis. In addition, the stability of the rotational shaft generated vibration was analyzed. Electromagnetic noise sources are classified into cogging torque, torque ripple, and unbalanced magnetic force. The effect of electromagnetic noise sources on vibration/noise was analyzed in the frequency domain through the electromagnetic-mechanical coupling analysis. The noise level was compared to the electromagnetic noise source characteristics for each frequency using the waterfall diagram, and additional vibration due to mechanical resonance was analyzed using critical speed analysis while taking the rotor's bearing stiffness into account.

극/슬롯 조합에 따른 영구자석 동기전동기의 전자기 및 NVH 특성 비교 분석

In this paper, electromagnetic noise sources of permanent magnet synchronous motors with 8-pole 9-slot and 12-slot fractional slot concentrated windings were analyzed through finite element analysis, and the radiated noise/vibration levels were compared through structural-acoustic analysis. Electromagnetic noise sources are classified into cogging torque, torque ripple, magnetic pull force, and unbalanced magnetic force, and the main values of electromagnetic excitation forces are different according to the pole/slot combination. In particular, the effect of electromagnetic noise sources on vibration/noise was analyzed in the frequency domain through the electromagnetic-mechanical coupling analysis. The noise level according to the speed was compared with the noise characteristics for each frequency using the waterfall diagram.

Novel Magnetic Circuit Design and Acceleration Calculation of Horizontal Linear Vibration Motor

This study proposes a novel magnetic circuit design to reduce the size of horizontal linear vibration motors (HLVMs) used in vehicle touchscreens. The HLVM prototype uses two thick permanent magnets to create a magnetic circuit below the voice coil; however, the novel design places four thin permanent magnets above and below the voice coil. Moreover, the coil position has been changed to a yoke center to create an effective magnetic circuit with short magnets. Compared with the vertical linear vibration motor, the force calculation method of the HLVM is significantly different. In this study, a new force calculation method is used to analyze the electromagnetic–mechanical coupling of the HLVM. As a prototype, the novel design is small in size (−28.85%) but possesses similar acceleration. The experimental results verify the analysis results of the HLVM in the displacement and acceleration on a dummy jig.

Characteristic Analysis and Experimental Verification of Electromagnetic and Vibration/Noise Aspects of Fractional-Slot Concentrated Winding IPMSMs of e-Bike

In this study, we performed the electromagnetic and mechanical characteristic analyses of an 8-pole 12-slot interior permanent magnet synchronous motor (IPMSM). Permanent magnet synchronous motors are classified into surface permanent magnet synchronous motor and interior permanent magnet synchronous motors according to the type of rotor. The IPM type is advantageous for high-speed operation because of the structure where the permanent magnet is embedded inside the rotor, and it has the advantage of having a high output density by generating not only the magnetic torque of the permanent magnet, but also the reluctance torque. However, such a motor has more vibration/noise sources than other types, owing to changes in reluctance. The sources of motor noise/vibration can be broadly classified into electromagnetic, mechanical, and aerodynamic sources. Electromagnetic noise sources are classified into electromagnetic excitation sources, torque pulsations, and unbalanced magnetic forces (UMFs). Vibration and noise cause machine malfunctions and affect the entire system. Therefore, it is important to analyze the electromagnetic vibration source. In this study, the electromagnetic characteristics of an IPMSM were analyzed through the finite element method to derive the UMF. Vibration and noise analyses were performed by electromagnetic–mechanical coupling analysis, and vibration and noise characteristics based on electromagnetic noise sources were analyzed.

Numerical Simulation of Laminate-Containment Launcher Based on the Electromagnetic–Mechanical Coupled Model

The laminate-containment structure is a kind of high-efficiency containment structure, which reduces the eddy current and increases the velocity of the armature. However, the research on the whole launching process of the laminate-containment launcher is rarely mentioned. In order to realize the numerical simulation of the whole launching process of the laminate-containment launcher, a simplified model of the laminate-containment launcher is established, and the electromagnetic–mechanical coupling calculation of the model is carried out by using the finite-element analysis (FEA). In the process of calculation, the pulse power source (PPS) program and electromagnetic field co-simulation are used to realize the field-circuit coupling calculation of the launching process. The movement of the armature during the launching process is realized by an embedded interior ballistic program. This calculation method provides a way to deeply understand the launching process of the laminate-containment launcher.

Winding vibration analysis of unbalanced transformer based on electromagnetic-mechanical coupling

Aiming at the problem of winding vibration of the transformer under unbalanced operation, the changes in winding current, internal magnetic leakage, and winding vibration characteristics in the three-phase Δ / Y transformer under different operating modes are studied through the electromagnetic-mechanical coupling. To simulate the internal electromagnetic environment of transformer during unbalanced operation state, a three-dimensional finite element simulation model is constructed. Then a dynamic model experiment platform was built to measure winding current and vibration acceleration of transformer under different conditions. The results of simulation and experiment show that the unbalanced phase differs from the normal phase in electromagnetic force and vibration acceleration by about two times, in a 20% unbalanced degree, which seriously endangers the stability of internal structure in transformer. The correctness of this model is verified by the comparison of simulation and experiment. It summarizes the variation law of electric field, magnetic field, and mechanical field of the transformer, and provides a feasible method for the extraction and identification of abnormal characteristics of unbalanced winding operation.

Design and Analysis of Novel Low-Cost Linear Vibration Motor for an Electronic Cigarette

The spring structure design and magnetic circuit optimization were considered to design a novel linear vibration motor with advantages of lower cost and similar motor performance compared to a coin-type vibration motor. A vibration motor is inserted in an electronic cigarette to provide haptic feedback to remind the user that the electronic cigarette is ready to operate. For the new generation of electronic cigarettes, new vibration motors require smaller size, lower cost, and acceptable motor performance. A three-dimensional finite element method has been used to find the coil’s magnetic flux density and von Mises stress distribution in the spring. Moreover, the electromagnetic-mechanical coupling method has been employed to find the motor acceleration on a dummy jig. The acceleration of the vibration motor was obtained to verify the analysis results by experiment. The experiment results verified the analysis results of the linear vibration motor. Compared to a coin-type vibration motor, the novel linear vibration motor has 9.09% and 80.77% reductions in total thickness and manufacturing cost, and a 40.0% improvement in acceleration.

Experimental and Comparative Study of Rotor Vibrations of Permanent Magnet Machines with Two Different Fractional Pole/Slot Combinations

This study deals with the noise, vibration, and harshness (NVH) characteristic analysis of permanent magnet synchronous motors (PMSMs) for electrical machines, such as electrically driven tools that are used in industries. An improved NVH design is needed for application to industrial tools. In general, the electromagnetic NVH characteristics of PMSMs are classified into electromagnetic excitation sources, such as total harmonic distortion of EMF, torque pulsation, magnetic pull force, and unbalanced magnetic force (UMF). This study compares the vibration and noise generated by fractional pole/slot combinations. In PMSMs with fractional pole/slot combinations, UMF is an important NVH source. PMSMs generate UMF because of armature reaction fields based on the pole/slot combinations and harmonics of magnetic flux density. UMF was derived using the finite element method, and the rotor vibration analysis was performed using electromagnetic mechanical coupling analysis. The analysis results and the effect of electromagnetic excitation characteristics on the rotor vibration of the PMSMs were compared and analyzed.

Analysis of Magnetostrictive Effect on Low-Frequency Force Wave in Rotating Magnetic Field

The electromagnetic vibration and noise in motors is mainly induced by electromagnetic forces and magnetostrictive force. The low-frequency force waves have a great influence on the deformation of the motor stator core due to resonance. In this article, a 2-D electromagnetic-mechanical coupling transient model was built based on the quadratic magnetic domain rotation model, considering the magnetostrictive characteristics of silicon steel sheet and the magnetoelastic coupling of materials. Through numerical simulation calculation and analysis, it was found that low-frequency force waves appeared in the motor stator, and the large amplitudes happened on the single and twice power frequency. The actual experimental measurements were designed in the rotating motor and the transformer to verify this phenomenon. It is concluded that the rotating field or the magnetic path distortion leads to the large amplitude at single-power frequency or rotating field frequency on the electrical equipment.