Electromagnetic Coupling Effects Research Articles

Frequency domain solution method for electromagnetic influence analysis on torsional vibrations

In electric motor-driven machines, mechanical torsional dynamics are nonlinearly coupled with the electrical system through the electromagnetic torque and the counter-electromotive force. In this paper, an approach based on small-signal linearization is proposed for modeling the steady-state torsional dynamics of the coupled system. Using the linearized model, resonance interference diagrams, torsional response, and stability can be evaluated rapidly across numerous operating points, while accurately accounting for the electromagnetic effects. The model is validated with conventional time-stepping simulations of two induction machines. An example analysis of a 3 MW motor-driven compressor train displays the modification of torsional properties due to the electromagnetic coupling effect and explains the mechanism of torsional destabilization. Finally, previously published measurements of a 37 kW motor test bench are considered to validate the instability of the elastic torsional mode predicted by the model.

Facile synthesis of Fe3O4/Ti3C2Tx MXene/RGO aerogels with broadband microwave absorption and thermal insulation performance

Abstract The development of microwave absorbing materials with attributes such as low weight, broad absorption bandwidth, and superior thermal insulation performance is still challenging. In this study, Fe3O4 nanoparticles were anchored on Ti3C2Tx MXene/RGO nanosheets by one-step hydrothermal gelation method to prepare Fe3O4/Ti3C2Tx MXene/RGO (FeMR) hybrid aerogels. Perfect impedance matching and electromagnetic coupling effect were achieved by adjusting the composition ratio of FeMR aerogels, so exceptionally outstanding microwave absorption performance was obtained. FeMR aerogel at 2.90 mm thickness, effective absorption bandwidth (EAB) up to 8.10 GHz. Simultaneously, FeMR aerogels have has good thermal insulation performance. After heating at 300°C for 60 min, the aerogel can still isolate the thermal radiation of about 155 °C. This work demonstrates a simple method for preparing lightweight, broadband electromagnetic wave absorption and heat insulation three-dimensional MXene-based aerogels, which provides inspiration for the structural design and potential applications of EWA materials.

Enhanced microwave absorption in graphene-based composites: A study on the synergistic effect of ferrite integration and electromagnetic coupling

Graphene integration with magnetic particles demonstrates a synergistic enhancement in dielectric and magnetic loss properties, facilitating the realization of absorbing materials that are strong, broadband, lightweight, and thin. This study achieved uniform dispersion of ferrite on the surface of in-situ synthesized high-conductivity graphene, utilizing an economical liquid glucose precursor and cobalt ferrite sintering process. An interface consisting of iron carbide and cobalt-iron alloy forms between the graphene and cobalt ferrite, significantly enhancing the samples’ microwave absorption performance. Furthermore, the magnetic loss is notably enhanced through the coupling of soft and hard magnetic materials. Consequently, a composite material consisting of Graphene/Fe3C/CoFe2/CoFe2O4, with a minimal thickness of 1.85 mm, demonstrated an impressive minimum reflection loss of −48.8 dB and a notable absorption bandwidth extending over 4.04 GHz. This research will offer an effective approach for developing high-performance microwave absorption materials using graphene-based composite magnetic materials.

A High-Precision Model for Dual Three-Phase PMSM Considering the Effect of Harmonics, Magnetic Saturation, and Electromagnetic Coupling

A High-Precision Model for Dual Three-Phase PMSM Considering the Effect of Harmonics, Magnetic Saturation, and Electromagnetic Coupling

Dynamic Characteristics of Magnetorheological Mounted Metal Rubber Structures Under Multi-physics Coupling Conditions

To accurately predict the dynamic characteristics of MR mounting, the nonlinear electromagnetic coupling law between MR liquid and soft magnetic material and the solid-liquid interaction, the electromagnetic coupling and fluid-structure coupling mathematical models and numerical simulation models of MR mounting are established. Through the magnetorheological mounting test, the simulation results are compared with the experimental results, and the validity of the numerical simulation model is verified. On this basis, the distribution effect of electromagnetic coupling in a magnetic circuit is analyzed. According to the Bingham model, the variation rule of magnetorheological fluid damping force was deduced. The magnetic field simulation results are introduced into the fluid model and the fluid-solid model, and the fluid-solid coupling effect of the numerical model of magnetorheological mounting is calculated. The dynamic and static characteristics of magnetorheological mounting under different current excitation conditions are simulated. It provides the basis for designing and simulating multi-physical field simulation of MR mounting.

Tackling capacitive coupling in broad-band spectral electrical impedance tomography (sEIT) measurements by selecting electrode configurations

SUMMARY Electromagnetic (EM) coupling effects including both inductive and capacitive coupling have long been an essential problem in broad-band spectral electrical impedance tomography (sEIT) measurements at the field scale. Efforts have been made to remove EM coupling numerically or to suppress the effects by modified data acquisition strategies. For near-surface applications with relatively small survey layouts, inductive coupling can be well removed in the mHz to kHz frequency range. With the use of shielded coaxial cables and so-called active electrodes where the amplifiers are mounted at the electrodes, capacitive coupling in sEIT measurements can also be reduced. However, it remains challenging to cope with capacitive coupling between the cable shield and the ground, especially in resistive field conditions. The aim of this study is to deal with this type of capacitive coupling effect by identifying and filtering out sEIT measurements that are strongly affected by capacitive coupling. Based on a correction method for capacitive coupling proposed in a previous study, an approach to estimate measurement errors due to capacitive coupling is presented first. In the second step, a workflow was proposed to calculate the capacitive coupling strength (CCS) for each electrode configuration, which is defined as the ratio of the imaginary part of the impedance induced by capacitive coupling and the imaginary part of the impedance due to the subsurface electrical conductivity. In the final step, measurements with low CCS were selected for inversion and the results were compared with inversion results obtained using the previously developed correction approach. It was found that the filtering method based on CCS is more capable in tackling capacitive coupling compared to using model-based corrections. Spectrally consistent sEIT results up to kHz were obtained using the newly developed filtering method, which were not achieved in previous work using model-based correction.

Progress on 3D tubular passive electronics: Residual stress-based fabrication, application, and modeling

The platform concept and methodology to create three-dimensional (3D) tubular structures by releasing the stress of two-dimensional multilayer membranes has been demonstrated for the design and fabrication of advanced integrated passive electronics, which revolutionizes their design and fabrication, enabling extraordinarily strong electromagnetic coupling effects and high energy storage densities, for the miniaturization of a variety of systems. In this perspective, we highlight the important recent progress, which constitutes the scope of understanding of 3D tubular passive electronics, including fabrication techniques, applications, and multi-physics modeling. Basic 3D tubular inductive and capacitive components are discussed, in addition to complex and composite devices and systems such as transformers, filters, and antennas. Finally, state-of-the-art strategies to engineer reconfigurable 3D tubular structures are discussed, with the intention to inspire a more disruptive design of passive electronics.

Impact Analysis of High-Altitude Electromagnetic Pulse Coupling Effects on Power Grid Protection Relays

Protection relays are important equipment used for protection, control, and metering functions in the power grid. These relays are used to protect critical and difficult-to-replace equipment, like generators, transformers, and capacitor banks. Once the protection devices are disturbed or damaged, a high risk of power generation interruption occurs. Therefore, it is important and necessary to study the relay’s immunity to electromagnetic pulse (EMP) events. As a preliminary step toward empirical experimentation on actual equipment, this manuscript outlines an economical and efficient methodology for evaluating the impact of an EMP. An impedance measurement strategy was employed to model the equipment, setting the stage for subsequent immunity analyses. These analyses included the pulse current injection (PCI) method, which utilized an injecting probe to introduce the transient, and frequency domain electromagnetic (FEKO) simulation, which integrated electromagnetic coupling effects into the transient simulation. The impedance measurement and simulation results in this paper provide a reliable basis for gauging equipment performance in the face of HEMP threats. The results obtained using the PCI and FEKO simulations demonstrated the performance of different port responses under a high-altitude EMP, indicating the requirement for some protection to ensure the reliable operation of relays.

A piezoelectric-electromagnetic hybrid energy harvester with frequency-up conversion mechanism towards low-frequency-low-intensity applications

This paper proposes a piezoelectric-electromagnetic hybrid energy harvester (PEHEH) with frequency-up conversion (FUC) mechanisms toward harvesting low-frequency-low-intensity, and wideband vibrational energy. The PEHEH consists of a stator with embedded coils, an eccentric rotor embedded with permanent magnets, and a fan-folded piezoelectric beam fixed to the stator. The eccentric rotor converts low-frequency straight vibration into rotational motion, and generates currents across the coils. The rotor could collide with the fan-folded beam, resulting in voltage generation due to the deformation of the fan-folded beam. The FUC mechanism broadens the bandwidth and harvests additional energy through the piezoelectric effect. The fan-folded beam can be considered as a nonlinear oscillator of hardening type. The electro-magnetic-mechanical system is modeled as a driven pendulum that impacts a mass-spring-damper system. The electromagnetic coupling effect is theoretically determined and equivalent to a nonlinear damping term. The nonlinear dynamical system is analyzed theoretically, numerically and experimentally. The results show that the bandwidth of the PEHEH is broadened than that of the energy harvester without the FUC mechanism. The maximum power reaches 26.4 mW at 4 Hz. The PEHEH can power an acceleration sensor at 4 Hz in laboratory environments and a temperature-humidity sensor in actual working conditions of an agricultural tractor's spray rod.

Solution of electromagnetic scattering field of adjacent transmission towers based on reciprocity theorem

Due to the large number of transmission towers being built, the dense distribution of transmission towers is inevitable in some areas. Densely distributed transmission towers will generate severe electromagnetic coupling, which will affect the setting of the passive interference protection distance between transmission towers and adjacent radio stations. Therefore, based on the traditional algorithm for solving the electromagnetic scattering field of a single electrically large target in wide area space, the electromagnetic coupling effect between multiple adjacent transmission towers within a range of 10 times the signal wavelength was considered. Based on the reciprocity relationship between the scattering electric field and the source and the introduced auxiliary field source as the intermediate variable, the electric field integral equation of the secondary scattering field generated by the electromagnetic coupling effect of adjacent transmission towers was derived, and the secondary scattering field is superimposed with the primary scattering field of the transmission generated by the electromagnetic wave excitation of the radio station, obtaining the electromagnetic scattering field at any point. In order to verify the accuracy of the algorithm proposed in this article, the scaled model experiments for the electromagnetic coupling effect between two transmission towers in an anechoic chamber were conducted. The average error of the algorithm proposed in this article is 6.73%, while the error of traditional algorithms is 20.18%. Compared with the traditional algorithm, the accuracy of the proposed algorithm is improved by 13.45%.

Quench analysis of a no-insulation REBCO magnet based on the ADI method considering the coupling effect of the cryostat

A no-insulation (NI) REBCO superconducting magnet is under development at Wuhan National High Magnetic Field Center, China. The magnet with the liquid helium cryostat system has a compact structure to reduce the space required for operation. During a quench, the fast-changing spatial magnetic field around the NI magnet may induce a strong eddy current in the conductive parts of the cryostat. The eddy current and its associated Lorentz force will generate mechanical stress on the cryostat, especially on the thermal shield (TS). The mechanical strength of the cryostat needs verification in the preliminary design. Furthermore, the degree to which the electromagnetic coupling between the cryostat and NI magnet might impact the quench behaviors of the NI magnet remains uncertain. In this paper, a multi-physics quench model is newly developed for the NI REBCO magnet, and the alternating direction implicit method is employed for the solver of the thermal model to improve computational efficiency. This simulation model can consider the electromagnetic coupling effect between the NI magnet and cryostat by constructing a partial element equivalent circuit. A quench analysis has been performed and we found that: (1) The cryostat can function as a secondary shorted circuit to the NI magnet and slow down the quench speed to a certain extent. (2) During the rather fast inductive quench phase, the cryostat will experience an attraction force towards the quench propagation frontier. (3) A quench propagation from one end of the magnet can cause a significant z-axis unbalanced force on the TS. (4) Cryostat materials with drastically changed electrical conductivity can significantly affect their mechanical responses during a quench. However, the eddy current density and maximum Von Mises stress on the TS are barely affected by the thickness of the TS and the contact resistance of the NI REBCO magnet.

A 3.83–5.55 GHz high frequency resolution DCO with optimized switched‐capacitor ladder and low‐coupled eight‐shaped transformer

SummaryA high frequency resolution digitally controlled oscillator (DCO) is proposed for wireless transceivers, in which the scheme adopts an optimized cascaded differential switched‐capacitor (SC) ladder and a low‐coupled eight‐shaped transformer. The frequency resolution is further improved by the low electromagnetic coupling effect between the primary and secondary coils of the on‐chip transformer, thus reducing quantization noise and phase noise. An eight‐shaped transformer designed using two coils cross‐connected each other is adopted to reduce the magnetic coupling and frequency pulling. The proposed DCO is implemented in a TSMC 180‐nm CMOS process, and a tuning range of 36.7% from 3.83 to 5.55 GHz with a frequency resolution of 17 kHz is achieved. The phase noise is −120.29 dBc/Hz at 1 MHz offset from the 3.83 GHz carrier frequency. The DCO consumes 9.26 mA from a 1.8 V supply, while the figure of merit with tuning range is −191 dBc/Hz. The chip size is 0.294 mm2.

Phase field model for brittle fracture in multiferroic materials

Multiferroic materials, which simultaneously possess piezomagnetic, piezoelectric, and electromagnetic coupling effects, have a wide range of applications in various fields. Multiferroic materials are generally brittle with low fracture toughness, and accurate prediction of the fracture behaviors of multiferroics is challenging. In this work, a phase field model for brittle fracture in multiferroic materials is developed with the help of the Hamilton principle. In light of the second law of thermodynamics, the constitutive equations are derived in the context of the phase field method. The present theoretical framework unifies two classical phase field models and four combinations of the electric and magnetic boundary conditions. The residual controlled staggered algorithm, which enjoys a higher accuracy and lower computational cost, is extended to the fracture problems in the context of magneto-electro-elasticity. Systematic numerical simulations are performed in both 2D and 3D cases. The influences of the external magnetic field, electric field, and electric and magnetic boundary conditions on fracture behaviors of multiferroic materials are studied in detail. The applied magnetic field may not only accelerate or delay the fracture, but also influence the crack path. The present work is beneficial to assess the safety of multiferroic-based devices in engineering applications.

Mechanism Analysis and Experiment of the Effects of the Guard Ring on the Inductors Performance

The grounded guard ring (GGR) is widely used to suppress the electromagnetic coupling (EMC) among adjacent inductors and reduce crosstalk with other components. However, the GGR will affect the performance of the inductor itself. To intuitively and deeply analyze the mechanism of the effects of GGR on the performance of inductors, an equivalent circuit model of inductors was adopted. Then, the substrate doping (SD) and EMC effects are introduced to characterize the mechanism of the GGR effects. To verify the correctness and rationality of the mechanism analysis, the inductors with and without GGR are taped-out using a standard 180-nm CMOS process. Then, the experimental results of the effects of GGR on the performance of inductors are presented. Furthermore, the equivalent model parameters are extracted based on measured S-parameters of two kinds of inductors. Finally, the experimental results are consistent with the mechanism analysis of the GGR effects, which has important guiding significance for the design of the subsequent GGR to improve the inductor and circuit performance.

Exploration of magnetic media modulation engineering on heterogeneous carbon spheres for optimized electromagnetic wave absorption

Magnetic carbon spheres are promising electromagnetic wave (EMW) absorbing materials due to their strong electromagnetic coupling effect. In the present work, magnetic carbon spheres composed of N-doped carbon spheres (NCSs) with magnetic Fe and Fe3C (Fe-Fe3C) nanoparticles were synthesized and the contents of Fe nanoparticles were adjusted through dilute hydrochloric acid treatment processes. The prepared NCSs/Fe-Fe3C composites dominate excellent EMW absorption performances with an optimal reflection loss value reaching − 63.77 dB at 9.92 GHz under a matching thickness of 2.9 mm, and the effective absorption bandwidth (EAB) reaches 4.88 GHz. The excellent absorption performance can be attributed to the synergistic effect of conductance loss, polarization loss, and magnetic loss arising from the different components of the composites. Moreover, the variation of Fe contents can regulate the dielectric and magnetic permeability characteristics of NCSs/Fe-Fe3C composites, and finally balance the impedance matching and attenuation coefficient. Our results pave the way for the development of high-efficiency EMW absorbing materials and clarify the regulation mechanism of magnetic media on the absorption performances of magnetic carbon spheres.

Ac corrosion phenomenon and mitigation in buried pipeline due to very-high-voltage (VHV) overhead transmission line effect

The presence of a very-high-voltage (VHV) electricity transmission line nearby a metallic pipeline can be a source of dangerous effects for this pipeline due to the electromagnetic field generated by this power line, it can induce a considerable voltage which may threaten the safety of operating personnel and the integrity of the pipeline. The main purpose of this paper is to evaluate the electromagnetic coupling effect in a buried metallic pipeline located in close proximity to a very-high-voltage (VHV) overhead transmission line using the Faraday's law and nodal network analysis under steady state conditions, as well as to estimate the possibility of AC induced corrosion of the metallic pipeline. The obtained results show that the induced voltage on the metallic pipeline exceeds the maximum threshold value recommended by the international regulations CENELEC and NACE, the AC corrosion current density surpasses the allowable value indicated by the specialized majority of corrosion studies. Therefore, a mitigation technique based on a pipeline grounding system is proposed to reduce the voltage induced on the pipeline to safe limits, in order to remedy the hazardous potential effects. The adopted mitigation technique has achieved better efficiency by reducing the induced voltage well below the safety limit.

Analysis and Prevention of Commutation Failure Caused by Line Coupling Effect in LCC-HVDC

In actual line-commutated converter based high- voltage direct-current (LCC-HVDC) projects, multiple HVDC transmission lines are usually installed on the same tower to save transmission corridors and reduce construction costs. However, electromagnetic coupling effect between adjacent lines can cause commutation failure (CF) in the non-fault poles when a line or pole fails. Hence, this paper deeply investigates the mechanism and the prevention strategy of CFs caused by line coupling effect in single- and double-circuit HVDC systems. The influencing factors of line coupling effect and the coupling characteristics under fault conditions are analyzed first based on the modeling of parallel transmission lines and the traveling wave theory. Then the mechanism of CF caused by line coupling effect is investigated with the consideration of different fault conditions, different line structures, and different system operation modes. Based on the above analyses, prevention strategies for CFs of non-fault poles in single- and double-circuit systems are proposed. Finally, the simulation results verify the correctness of the theoretical analyses and the effectiveness of the proposed control strategies.

Co‐Ni Electromagnetic Coupling in Hollow Mo2C/NC Sphere for Enhancing Electromagnetic Wave Absorbing Performance†

Comprehensive SummaryFor enhancing the electromagnetic wave (EW) attenuation and adsorption, rational constructing and homogeneously distributing bimetallic electromagnetic coupling units in hollow structure is an effective way, but hard to achieve. Herein, a CoNi‐doped hybrid zeolite imidazole framework was synthesized as precursor, which was further converted into a hollow CoNi‐bimetallic doped molybdenum carbide sphere (H‐CoNi@MoC/NC) through a two‐step etching and calcination strategy. At the loading amount of 15 wt%, a strong absorption of minimum reflection loss (RLmin) of –60.05 dB at 7.2 GHz with the thickness of 3.1 mm and a wide effective adsorption bandwidth (EAB) of 3.52 GHz at the thickness of 2.5 mm were achieved, which was far beyond the reported MoC‐based metallic hybrids. The crucial synergistic Co‐Ni electromagnetic coupling effect in the composite was characterized, not only enhancing the dipolar/interfacial polarization, but also promoting the impedance matching, displaying the optimized EW absorbing performance.

Broadband spectral induced polarization for the detection of Permafrost and an approach to ice content estimation – a case study from Yakutia, Russia

Abstract. The reliable detection of subsurface ice using non-destructive geophysical methods is an important objective in permafrost research. The ice content of the frozen ground is an essential parameter for further interpretation, for example in terms of risk analysis and for the description of permafrost carbon feedback by thawing processes. The high-frequency induced polarization method (HFIP) enables the measurement of the frequency-dependent electrical conductivity and permittivity of the subsurface, in a frequency range between 100 Hz and 100 kHz. As the electrical permittivity of ice exhibits a strong characteristic behaviour in this frequency range, HFIP in principle is suitable to estimate ice content. Here, we present methodological advancements of the HFIP method and suggest an explicit procedure for ice content estimation. A new measuring device, the Chameleon-II (Radic Research), was used for the first time. Compared to a previous generation, the new system is equipped with longer cables and higher power, such that we can now achieve larger penetration depths up to 10 m. Moreover, it is equipped with technology to reduce electromagnetic coupling effects which can distort the desired subsurface signal. The second development is a method to estimate ice content quantitatively from five Cole–Cole parameters obtained from spectral two-dimensional inversion results. The method is based on a description of the subsurface as a mixture of two components (matrix and ice) and uses a previously suggested relationship between frequency-dependent electrical permittivity and ice content. In this model, the ice relaxation is considered the dominant process in the frequency range around 10 kHz. Measurements on a permafrost site near Yakutsk, Russia, were carried out to test the entire procedure under real conditions at the field scale. We demonstrate that the spectral signal of ice can clearly be identified even in the raw data and show that the spectral 2-D inversion algorithm is suitable to obtain the multidimensional distribution of electrical parameters. The parameter distribution and the estimated ice content agree reasonably well with previous knowledge of the field site from borehole and geophysical investigations. We conclude that the method is able to provide quantitative ice content estimates and that relationships that have been tested in the laboratory may be applied at the field scale.

Near-Field Electromagnetic Coupling Effects in Dimers of Three-Layer Metalorganic Nanoparticles with a J-Aggregate Dye Outer Shell

Near-Field Electromagnetic Coupling Effects in Dimers of Three-Layer Metalorganic Nanoparticles with a J-Aggregate Dye Outer Shell