Electromagnetic Coupling Mechanism Research Articles

Wearable bio-adhesive metal detector array (BioMDA) for spinal implants

Dynamic tracking of spinal instrumentation could facilitate real-time evaluation of hardware integrity and in so doing alert patients/clinicians of potential failure(s). Critically, no method yet exists to continually monitor the integrity of spinal hardware and by proxy the process of spinal arthrodesis; as such hardware failures are often not appreciated until clinical symptoms manifest. Accordingly, herein, we report on the development and engineering of a bio-adhesive metal detector array (BioMDA), a potential wearable solution for real-time, non-invasive positional analyses of osseous implants within the spine. The electromagnetic coupling mechanism and intimate interfacial adhesion enable the precise sensing of the metallic implants position without the use of radiation. The customized decoupling models developed facilitate the precise determination of the horizontal and vertical positions of the implants with incredible levels of accuracy (e.g., <0.5 mm). These data support the potential use of BioMDA in real-time/dynamic postoperative monitoring of spinal implants.

A substrate-integrated waveguide-based wideband circularly polarized slot antenna using the parasitic square patch array

In this paper, a planar low-profile wideband circularly polarized substrate-integrated waveguide (SIW) based antenna is investigated. The antenna comprises two substrates stacked over each other. The top layer of the antenna is loaded with a 4 × 4 array of parasitic square patches stacked over a spiral slot loaded in the SIW cavity. The spiral slot is utilized for the generation of narrow band circular polarization and to enhance the CP bandwidth, the parasitic patch array is excited through the electromagnetic coupling mechanism without any air gap between them. The antenna is fabricated and tested to validate the simulated results. A wide relative impedance bandwidth of 33% (8.25–11.55 GHz) and the axial ratio bandwidth of 8.55–9.70 GHz (12.60%) is exhibited. The broadside radiation characteristics are achieved with peak gain of 8.05dBic at 9 GHz. The overall size of the antenna structure is 0.8λ0 × 0.8λ0. The proposed antenna is suitable for various satellite applications.

Comparison and Analysis of Electromagnetic Characteristics of Basic Structure of Wireless Power Coil for Permanent Magnet Motors in Electric Vehicles

The purpose of this paper is to compare and analyze the electromagnetic characteristics of the basic structure of the coil in the electromagnetic coupling mechanism for the wireless power supply of permanent magnet motors in electric vehicles. The electromagnetic coupling mechanism is one of the key technologies for wireless power transmission and the coil structure plays a key role in the transmission performance of the coupling mechanism, and different structures can achieve different performances. The central objective of coil structure studies is to investigate how the coupling coefficient can be increased to achieve greater transmitted power and higher efficiency. In this paper, we investigate two basic coil configurations, circular and square, by studying their flux density variations when used as transmitting coils and their electromagnetic coupling characteristics when used as receiving coils. Three couplers consisting of circular and square coils are also analyzed in simulations and experiments are carried out on couplings containing circular and square coils of the same area. The results of the study show that the qualitative analysis, simulation analysis and experimental results are in high agreement. The results of this paper are an important reference for the design and optimization of wireless power coils for permanent magnet motors in electric vehicles.

An efficient modeling approach of 1D-planar metamaterials in the high-frequency regime

PurposeThe purpose of this paper is to present an alternative modeling approach in terms of the determination of a physically equivalent circuit model for one-dimensional (1D) planar metamaterials in the high-frequency regime, without a postprocessing optimization procedure. Thereby, an efficient implementation of physical relationships is aimed.Design/methodology/approachIn this paper, a method based on quasi-stationary simulations and mathematical conversions to derive the values for a physically equivalent circuit model is proposed. Because the electromagnetic coupling mechanisms are investigated in detail, a simplification for the considered multiconductor transmission line structure is achieved.FindingsThe results show that the proposed modeling approach is an efficient and physically meaningful alternative to classical full-wave simulation techniques for the investigated inhomogeneous transmission line structure in both the time domain as well as in the frequency domain. In the course of this, the effort is reduced while a comparable accuracy is maintained, whereby specific coupling mechanisms are considered in circuit simulations.Originality/valueThe process to obtain information about physically interpretable lumped element values for a given structure or to determine a layout for known ones is simplified with the aid of the proposed approach. An advantageous adaption of the presented procedure to other areas of application is well conceivable.

Transmission Enhancement through Sub-Wavelength Aperture Based on Regulable Water-Based Metamaterial

A realization form of the Mie resonance with adjustable characteristics based on a water-based metamaterial is proposed. A novel local electromagnetic field coupling mechanism based on a water-based metamaterial is established, which is used for transmission enhancement through the sub-wavelength aperture for the first time. The water-based metamaterial particle for transmission enhancement at a specific frequency is designed. By designing the microfluidic control system to control the water filling (i.e., height) of the metamaterial particle, the adjustable transmission enhancement characteristics are realized. The influence of bilateral symmetry and flexible deformation of the metamaterial particle on the transmission characteristics is analyzed. The influence of the design parameters on the enhanced transmission characteristics is discussed.

A study on the effects of electromagnetic coupling mechanisms in the event of an indirect lightning strike near photovoltaic arrays

Indirect lightning strikes hitting near photovoltaic installations are much more frequent than direct hits, and can generate overvoltage in their electric circuitry. The authors developed a method to estimate the induced overvoltage on single photovoltaic modules. Using a model of the whole array also including Inter-Module Coupling Mechanisms (IMCMs), a new approach to estimate overvoltage induced on full arrays is presented in this paper. The procedure first estimates lumped parameters, modelling either the coupling between the lightning channel and each module in the array or between each couple of modules in array. Several circuital simulations are then run using suitable equivalent circuits. The aim is to consider different array configurations and groundings schemes. This allows extracting the most relevant configuration parameters influencing overvoltage/overcurrent. Results show that the groundings scheme impacts negligibly, but the single module electric stress is decreased by 35% in the case of ungrounded configurations. Among the considered array configurations, the honey-comb and total cross-tied showed the smallest impact on overvoltage. Statistical analysis on random LC tortuous geometry leads to a non-negligible rise of overvoltage peak values, up to 24%. Finally, the relevance of different IMCMs is analysed, showing a strong impact just on frame-ground voltages and currents.

Design of Coupling Coil Parameters for Wireless Charging Tram Based on Electromagnetic Safety

As a new type of urban rail transit tram, wireless charging tram uses high frequency electromagnetic field to conduct inductive power transmission, which gets rid of the traditional overhead catenary network, but inevitably causes electromagnetic radiation to the surrounding environment. Research shows that excessive electromagnetic radiation will affect the normal operation of equipment and the safety of human body. This paper analyzes the structure and coil configuration of the dynamic charging system for wireless charging tram. Aiming at the problem of electromagnetic radiation, a mathematical model with minimum electromagnetic radiation as the target and system parameters as the constraint condition is established. Finally, the system parameters of the electromagnetic coupling mechanism of the wireless charging tram are designed and optimized. The simulation and experimental results show that the method can meet the operating requirements of the system and reduce the electromagnetic radiation to the surrounding environment.

A Wireless Power Transmission System With High Misalignment Tolerance and High Efficiency for Autonomous Underwater Vehicles

Based on the principle of magnetic coupling resonance, a wireless power transmission system with electromagnetic coupling mechanism based on E-type magnetic core is designed for autonomous underwater vehicle (AUV). Firstly, according to the special circular structure of AUV and the effect of seawater mobility, an electromagnetic coupling structure that can be used in AUV is proposed. The performance of the electromagnetic coupling mechanism is tested by simulation and experiment. The coupling coefficient of the coupling mechanism can reach 0.64, and it has good magnetic field confinement ability. Secondly, in order to improve the robustness of the system, the compensation network of the LCL/S topology is used. Finally, an experimental platform is built. When the incandescent lamp is used as the load, the output power is 120W, and the efficiency can reach 96%. When the load changes, the output voltage can remain constant. When the relative positions of the transmitting and receiving coils are changed at the same time, axial misalignment and rotational misalignment experiments are carried out. In the experiment, the output voltage is relatively stable, which indicates that the system has high misalignment tolerance ability.

Bandpass filters based on integrated aperture‐ and gap‐coupled discontinuities

An electromagnetic coupling mechanism is discussed for distributed-element aperture- and gap-coupled discontinuities based on rigorous lumped-element equivalent circuit analysis. The two discontinuities are analysed in terms of their transmission poles and transmission zeros for the selectivity enhancement of microwave and or millimetre-wave components. The integration of these two discontinuities is put forward for bandpass filter design. A frequency-dependent lumped-element equivalent circuit is employed to study the behaviour of the two distributed-element discontinuities in the transverse direction. Bandpass filters are characterised based on the dual aperture- and gap-coupled discontinuities integrated within substrate integrated waveguide structures. It is shown that multiple transmission zeros close to transmission poles are realised due to the magnetic and electric field cancelation in the gap-coupled discontinuity, while the aperture-coupled discontinuity contributes to a resonator with a higher quality factor. The integration of both aperture- and gap-coupled discontinuities shows the priority of this kind of microwave resonator in terms of selectivity, size, and upper stopband in comparison with the conventional aperture-coupled one.

An improved quantitative assessment method on hazardous interference of power lines to the signal cable in high‐speed railway

High-speed railway (HSR) presents the characteristics of a heavy load, large traction current, and ballastless track-bed. As the 'neural network' of the signalling system, the line-side signal cable may threaten both human safety and control information transmission for an HSR operation when interfered with by a strong traction current. This study comprehensively investigates the electromagnetic interference (EMI) factors of the traction power supply system (TPSS) and the integrated earthing system (IES) to a signal cable and completes the electromagnetic coupling mechanism analysis of longitudinal electromotive force (LEF). Then, an improved theoretical calculation method is proposed for the multi-conductor power line network of the HSR instead of the traditional look-up table method. Regarding the essential influence of different earthing methods and cable laying conditions, the quantitative calculation of the LEF on the cable is evaluated. The validity of the theoretical method is verified through finite element simulation. Finally, the solutions to suppress the EMI are put forward for cable laying. This work provides an accurate quantitative basis for the implementation of the on-site LEF test, is significant for the design of cable laying schemes in railway engineering, and is also beneficial to ensure the safe operation of HSR.

Coil Design and Optimization of Inductive Power Transfer System for Tram

As a new type of urban transit vehicle, Non-catenary trams using inductive power transmission technology get rid of the traditional overhead catenary. In engineering applications, coils assembled on the different tram bodies have inevitable differences due to the restrictions on the production process and other factors. Research shows tiny differences in self-inductance always lead to system detuning so as to causes an extreme descent of the system power factor. From the perspective of hardware design, the paper analyzes the system architecture and coil configuration for the dynamic charging trams with considering cost, system reliability, etc. Then, for the problem of power factor reduction caused by the differences in the self-inductance of the secondary windings, the article establishes a mathematical model with the maximum power factor as the goal and system parameters as constraints. And a complete system parameters design method is proposed. Finally, the global design and optimization of tram's electromagnetic coupling mechanism parameters are performed using the group method. The simulation result indicates that the method can meet the requirements of system operation and has a higher tolerance to the self-inductance differences of the secondary coils.

Topology Optimization and Design Realization of Magnetically-Coupled Resonant Wireless Power Transfer System with LCL-S Structure

Magnetically-coupled resonant wireless power transfer (MCR-WPT) system with LCL-S structure is developing for higher transmission characteristics. This paper improves the resonance topology structure by adding a compensation capacitor in the transmitting side and proposes a parameter configuration method with equivalent impedance. The transmission characteristics are analyzed first based on simulation method to determine the parameters for the system requirements of 3 kW output power at working frequency of 85 kHz. Then the improved MCR-WPT system is developed. The realization methods of key modules such as electromagnetic coupling mechanism and drive circuit are given. The experiments are designed and are used to analyze the effect of different frequency and different distance on transmission characteristics. Output power and transmission efficiency of the designed system can be 3141 W and 91% respectively. In addition, the inverter’s performance and the system electromagnetic radiation state are evaluated. The results show that the designed system can provide an effective means for 3 kW WPT application at 85 kHz.

Analysis of a Novel Dual-Rotor Induction Motor for Pulsed Power Driving System

A novel dual-rotor induction motor (DRIM) is proposed as a potential substitution of the traditional motor/generator with a flywheel (MGFW) used in the pulsed power driving system (PPDS) which is especially deployed in mobile platforms. The DRIM is based on the integration of flywheel energy storage and electromagnetic slip coupling mechanism. The DRIM utilizes its outer rotor as a flywheel to store the input mechanical energy. By the interaction between the excitation field produced by the outer rotor and the eddy current induced on the surface of the inner rotor, an electromagnetic torque is generated and simultaneously acted on the two rotors. So the stored energy in the outer rotor can be directly transferred to the inner rotor with the mechanical load through the torque. The substitution of MGFW with DRIM holds potential for simplifying the PPDS and improving its compactness. The configuration and operation mechanism of the DRIM are firstly introduced in this paper. Then transient characteristics of the DRIM are analyzed by the 2D finite element method (FEM). The influences of the excitation pole number and the excitation coil turns on the performance of the DRIM are investigated. Finally, the feasibility of the DRIM is experimentally verified by a prototype.

Research on Series Arc Fault Detection Based on Higher-Order Cumulants

At present, the detection methods on series arc faults are mainly based on the current of the main circuit, which probably results in misjudgment because of the singularity of the normal working current in a nonlinear load. What’s worse, is the arc fault characteristic in the small power branch is easily ignored in the current of the main circuit, which leads to missed judgment. To solve these problems, a detection method based on coupling signal acquisition and higher-order cumulant identification is presented, through the electromagnetic coupling mechanism of high frequency current. By analyzing the coupling signal of the high-frequency current and using the higher-order cumulant algorithm during arcing process, the kurtosis of the coupling signal is calculated. In this paper, the unified threshold value on the kurtosis in various conditions is obtained. The results show that the novel method can be effectively used to detect and identify the series arc faults.

Design of a bistable electromagnetic coupling mechanism for underactuated manipulators

Electromagnetic clutches have been widely used in underactuated lightweight manipulator designs as a coupling mechanism due to their advantages of fast activation and electrical controllability. However, an electromagnetic clutch consumes electrical energy continuously during its operation. Furthermore, conventional electromagnetic clutches are not fail-safe in unexpected power failure conditions. These factors have a significant impact on the energy efficiency and the safety of the design, and these are vital aspects for underactuated lightweight manipulators. This paper introduces a bistable electromagnetic coupling mechanism design, with reduced energy consumption and with a fail-safe mechanism. The concept of a bistable electromagnetic mechanism consists of an electromagnet with two permanent magnets. The design has the capability to maintain stable mechanism states, either engaged or disengaged, without a continuous electrical power supply, thus enhancing fail-safety and efficiency. Moreover, the design incorporates the advantages of conventional electromagnetic clutches such as rapid activation and electrical controllability. The experimental results highlight the effectiveness of the proposed mechanism in reducing electric energy consumption. Besides this, a theoretical model is developed and a good correlation is achieved between the theoretical and experimental results. The reduced electric energy consumption and fail-safe design make the bistable electromagnetic mechanism a promising concept for underactuated lightweight manipulators.

Energy harvesting from quasi-periodic vibrations using electromagnetic coupling with delay

In this paper, we study quasi-periodic vibrational energy harvesting in a delayed self-excited oscillator with a delayed electromagnetic coupling. The energy harvester system consists in a delayed van der Pol oscillator with delay amplitude modulation coupled to a delayed electromagnetic coupling mechanism. It is assumed that time delay is inherently present in the mechanical subsystem of the harvester, while it is introduced in the electrical circuit to control and optimize the output power of the system. A double-step perturbation method is performed near a delay parametric resonance to approximate the quasi-periodic solutions of the harvester which are used to extract the quasi-periodic vibration-based power. The influence of the time delay introduced in the electromagnetic subsystem on the performance of the quasi-periodic vibration-based energy harvesting is examined. In particular, it is shown that for appropriate values of amplitudes and frequency of time delay the maximum output power of the harvester is not necessarily accompanied by the maximum amplitude of system response.

CST闪电间接效应研究

闪电通过飞机开口缝隙耦合进入飞机内部，产生电磁干扰。本文利用CST仿真软件在787模型上设置开口缝隙结构，对其电磁耦合机理进行验证；选取了不同型号的传输线，对比分析其电磁屏蔽性能，为线缆铺设改装提供依据。 Lightning is coupled into the airplane through the gap of the aircraft, which produces electromagnetic interference. In this paper, the CST simulation software is used to set up the slot structure on the 787 model to verify its electromagnetic coupling mechanism; this simulation selects different kinds of cables, analyzing their electromagnetic shielding performance by comparison and providing the basis for the cable laying and modification.

Plasmon hybridization in pyramidal metamaterials: a route towards ultra-broadband absorption.

Pyramidal metamaterials are currently developed for ultra-broadband absorbers. They consist of periodic arrays of alternating metal/dielectric layers forming truncated square-based pyramids. The metallic layers of increasing lengths play the role of vertically and, to a less extent, laterally coupled plasmonic resonators. Based on detailed numerical simulations, we demonstrate that plasmon hybridization between such resonators helps in achieving ultra-broadband absorption. The dipolar modes of individual resonators are shown to be prominent in the electromagnetic coupling mechanism. Lateral coupling between adjacent pyramids and vertical coupling between alternating layers are proven to be key parameters for tuning of plasmon hybridization. Following optimization, the operational bandwidth of Au/Ge pyramids, i.e. the bandwidth within which absorption is higher than 90%, extends over a 0.2-5.8 µm wavelength range, i.e. from UV-visible to mid-infrared, and total absorption (integrated over the operational bandwidth) amounts to 98.0%. The omni-directional and polarization-independent high-absorption properties of the device are verified. Moreover, we show that the choice of the dielectric layer material (Si versus Ge) is not critical for achieving ultra-broadband characteristics, which confers versatility for both design and fabrication. Realistic fabrication scenarios are briefly discussed. This plasmon hybridization route could be useful in developing photothermal devices, thermal emitters or shielding devices that dissimulate objects from near infrared detectors.

PIC/MCC simulation of the ionization process of SWP influenced by gas pressure and SPP

A surface-wave plasma (SWP) source based on surface plasmon polariton (SPP) has fine performances such as high density, low temperature, high production, and so on. It is applied in electronic device micro or nano processing, material modification, etc. Because the ionization of SWP heated by SPP is difficult to describe by theoretical analysis and experimental measurement, the ionization process of producing uniform stable SWP source is not yet well understood. The method in this paper is a numerical simulation of SWP discharges. The electromagnetic energy coupling mechanism of ionization process, influenced by gas pressure, which is studied by combining particle-in-cell (PIC) simulation of reciprocity between plasma and electromagnetic wave with Monte Carlo Collide (MCC) method in merit of dealing with particle collision. Simulated results suggest that the efficient production of SWP is induced by locally enhanced electric field of SPP, and the gas pressure influences the ionization process of SWP by altering the appearance time of wave-mode resonant conversion. Results of this paper show the ionization process of SWP discharge maintained by SPP, and further provide some advices for designing the parameter optimization of next generation meter-scale SWP source.

Plasmonic Chiroptical Response of Silver Nanoparticles Interacting with Chiral Supramolecular Assemblies

Silver nanoparticles were prepared in aqueous solutions of chiral supramolecular structures made of chiral molecular building blocks. While these chiral molecules display negligible circular dichroism (CD) as isolated molecules, their stacking produced a significant CD response at room temperature, which could be eliminated by heating to 80 °C due to disordering of the stacks. The chiral stack-plasmon coupling has induced CD at the surface plasmon resonance absorption band of the silver nanoparticles. Switching between two plasmonic CD induction mechanisms was observed: (1) Small Ag nanoparticles coated with large molecular stacks, where the induced plasmonic CD decayed together with the UV molecular CD bands on heating the solution, indicating some type of electromagnetic or dipole coupling mechanism. (2) Larger Ag nanoparticles coated with about a monolayer of molecules exhibited induced plasmonic CD that was temperature-independent. In this case it is estimated that the low chiroptical response of a molecular monolayer is incapable of inducing such a large chiroptical effect, and a model calculation shows that the plasmonic CD response may be the result of a slight chiral shape distortion of the silver nanoparticles.