Electromagnetic Induction Coil Research Articles

Driving Wi-Fi IoT Sensors by a Hybrid Magneto-Mechano-Electric Energy Generator Extracting a Power of over 50mW.

Energy harvesting technology is mainly used as a power source for driving Internet of Things (IoT) devices. However, the output power of conventional harvesting devices are limited, suitable only for low-power-consumption IoT sensors based on Bluetooth communication. In contrast to Bluetooth, wireless fidelity (Wi-Fi) communication offers superior real-time monitoring and transmission capabilities, but requires more power in the range of hundreds of milliwatts or higher. Therefore, the hybridization of three energy conversion devices, namely, piezoelectric magneto-mechano-electric (MME) generator, electromagnetic (EM) induction coil, and triboelectric nanogenerator (TENG) is proposed as a standalone power source for Wi-Fi communication sensors. By integrating these three mechanisms, the hybrid MME energy harvester can achieve an output power exceeding 50mW at the second harmonic resonance condition under the alternating current (AC) magnetic field of 10Oe. Furthermore, it can successfully drive the Wi-Fi sensor, enabling continuous real-time monitoring without the degradation of charged power in a supercapacitor. These results highlight that energy harvesting technology is not limited to low-power devices but can also be applied to Wi-Fi communication sensors and beyond.

Enhancing Electrical Conductivity of Stretchable Liquid Metal-Silver Composites through Direct Ink Writing.

Structure-property-process relationships are a controlling factor in the performance of materials. This offers opportunities in emerging areas, such as stretchable conductors, to control process conditions during printing to enhance performance. Herein, by systematically tuning direct ink write (DIW) process parameters, the electrical conductivity of multiphase liquid metal (LM)-silver stretchable conductors is increased by a maximum of 400% to over 1.06 × 106 S·m-1. This is achieved by modulating the DIW print velocity, which enables the in situ elongation, coalescence, and percolation of these multiphase inclusions during printing. These DIW printed filaments are conductive as fabricated and are soft (modulus as low as 1.1 MPa), stretchable (strain limit >800%), and show strain invariant conductivity up to 80% strain. These capabilities are demonstrated through a set of electromagnetic induction coils that can transfer power wirelessly through air and water, even under deformation. This work provides a methodology to program properties in stretchable conductors, where the combination of material composition and process parameters leads to greatly enhanced performance. This approach can find use in applications such as soft robots, soft electronics, and printed materials for deformable, yet highly functional devices.

Uncovering the structural and photoelectric properties of perovskite crystals by joint multifaceted characterization and theoretical analysis

The potential of organic-inorganic hybrid perovskites, owing to their distinct photoelectric attributes and boosted photoluminescence stability, has garnered substantial attention. Despite comprehensive examinations of the synthesis and optical characteristics of FAPbBr3 crystals, the understanding of their microstructure's implication on photoelectric applications, their electronic configuration, and electron-phonon interplay remains vague. In this study, we detailed the electronic configuration, phonon dispersion, and vibrational properties using density functional theory. We further calculated the formation enthalpy stability diagram. Characterization and calculation of the crystalline structure were accomplished via Rietveld refinement. Phonon dispersion curves, as well as total and partial phonon densities of states, were also calculated. The theoretical results align well with experimental Fourier infrared and Raman spectra. Beyond elementary characterization, we explored the photoelectric qualities of FAPbBr3 crystals, thereby reaffirming the outstanding photoelectric attributes and extensive application potential. A non-contact fixed-point lighting device was designed based on the principle of electromagnetic induction coils, which proved the uniformity of crystal luminescence. According to the first principle, FAPbBr3 possesses a Poisson ratio of 0.32, indicative of high flexibility, emphasizing their superb photoelectric characteristics and vast application scope.

Self‐Powered Smart Proximity‐Detection System Based on a Hybrid Magneto‐Mechano‐Electric Generator

A hybrid magneto‐mechano‐electric (H‐MME) generator that combines a Mn‐doped Pb(Mg1/3Nb2/3)O3‐Pb(Zr,Ti)O3 piezoelectric single crystal and an electromagnetic induction coil is demonstrated to convert stray magnetic noise of 60 Hz into useful electrical energy. The authors optimize the design of the piezoelectric cantilever, the weight of the magnetic mass, and the distance between the magnet and coil through theoretical simulation and experiments to maximize each contribution for the H‐MME generator. The total root mean square output power of the H‐MME generator is 28.35 mW with a power density of 0.042 mW cm−3 Oe2 in a 5 Oe magnetic field of 60 Hz, which is sufficient for driving multiple functional Internet of Things sensors that detect temperature, humidity, light, UV radiation, air pressure, and sound. In addition, a self‐powered smart proximity‐detection system (including a microcontroller unit, an ultrasonic sensor module, a piezo speaker, and a Bluetooth module) is demonstrated by rectifying the output of the H‐MME generator and controlling it using a power management circuit. The superior output power of the H‐MME generator exceeds simple sensing functions and presents the possibility of achieving battery‐free self‐powered smart devices and systems.

Analysis of the Influence of System Parameters on Launch Performance of Electromagnetic Induction Coil Launcher

The influence of electromagnetic induction coil launcher (EICL) system parameters on the launch performance was analyzed, and a method for measuring the launch performance of an EICL system with a muzzle velocity and energy conversion efficiency was proposed. The EICL system mainly includes a pulse power supply and launcher. The parameters of the pulse power supply mainly include the discharge voltage and the capacitance value of the capacitor bank. The structural parameters of the launcher mainly include the bore size of the launcher, the air gap length between the armature and the drive coil, the length and width of the drive coil, and the trigger position of the armature. Change in single or multiple parameters in the launch system will influence the launch performance. The influence of single or multiple parameters on the launch performance was summarized, and the physical law as analyzed. The influence law of the EICL system parameters on the launch performance was obtained, which lays a theoretical foundation for the optimization design of EICL. Finally, experimental verification was carried out by a single-stage test platform.

Comparison of frequency domain and time domain methods for the numerical simulation of contactless ultrasonic cavitation

The use of a top-mounted electromagnetic induction coil has been demonstrated as a contactless alternative to traditional ultrasonic treatment (UST) techniques that use an immersed mechanical sonotrode for the treatment of metals in the liquid state. This method offers similar benefits to existing UST approaches, including degassing, grain refinement, and dispersion of nanoparticles, while also preventing contact contamination due to erosion of the sonotrode. Contactless treatment potentially extends UST to high temperature or reactive melts. Generally, the method relies on acoustic resonance to reach pressure levels suitable for inertial cavitation and as a result the active cavitation volume tends to lie deep in the melt rather than in the small volume surrounding the immersed sonotrode probe. Consequently, (i) with suitable tuning of the coil supply frequency for resonance, the treatment volume can be made arbitrarily large, (ii) the problem of shielding and pressure wave attenuation suffered by the immersed sonotrode is avoided. However, relying on acoustic resonance presents problems: (i) the emergence of bubbles alters the speed of sound, resonance is momentarily lost, and cavitation becomes intermittent, (ii) as sound waves travel through and reflect on all the materials surrounding the melt, the sound characteristics of the crucible and supporting structures need to be carefully considered. The physics of cavitation coupled with this intermittent behaviour poses a challenge to sonotrode modelling orthodoxy, a problem we are trying to address in this publication. Two alternative approaches will be discussed, one of which is in the time domain and one in the frequency domain, which couple the solution of a bubble dynamics solver with that of an acoustics solver, to give an accurate prediction of the acoustic pressure generated by the induction coil. The time domain solver uses a novel algorithm to improve simulation time, by detecting an imminent bubble collapse and prescribing its subsequent behaviour, rather than directly solving a region that would normally require extremely small time steps. This way, it is shown to predict intermittent cavitation. The frequency domain solver for the first time couples the nonlinear Helmholtz model used for studying cavitation, with a background source term for the contribution of Lorentz forces. It predicts comparable RMS pressures to the time domain solver, but not the intermittent behaviour due to the underlying harmonic assumption. As further validation, the frequency domain method is also used to compare the generated acoustic pressure with that of traditional UST using a mechanical sonotrode.

Study on the influence of different thickness of armature structure on the emission performance of electromagnetic induction coil launcher

In the armature structure of traditional electromagnetic induction coil launcher, the armature tail melted due to heat accumulation. In this paper, three new armature structures are proposed. Based on the finite element software maxwell2D, the single-stage electromagnetic induction coil launcher, model is established. The performance indexes of traditional and new armature structures are compared, and the influence of the thickness of traditional armature structure and the side thickness of new structure on temperature rise and electromagnetic performance is studied. On the basis of Maxwell-thermal finite element, the correctness of the temperature field conclusion is verified. The simulation results show that the traditional armature structure has the optimal thickness and the armature performance remains unchanged when the weight ratio and the mechanical strength of the armature are considered. Structure 3 and Structure 4 of the new structure significantly improve the temperature rise of the armature and enhance its emission performance. Due to the eddy current, the optimum side thickness of the new structure 3 and structure 4 is slightly larger than 1/2 of the armature length.

Effect of electromagnetic induction coil position on feeding effect in steel ingot

The relationship between the feeding ability of the riser and the shrinkage and porosity is always a hot investigation topic, and the interior shrinkage and porosity of the ingot is the common defect met by industries. The work on the effect of Electromagnetic Feeding Riser (EFR) on ingot solidification is approached via the interpretative of the electromagnetic heat efficiency, temperature field, and Niyama criteria. The results show that the heating effect is better when the induction coil is at L = 0 mm and the heat efficiency rapidly reduces with the induction coil away from the riser, from the view of magnetic field. An obvious improvement in the solidification process is the application of EFR from the view of temperature field. Then, the Niyama criterion was defined as 1.1 through the experiment and simulation. Electromagnetic feeding starts to restrain the appearance of the shrinkage and porosity when L = 0 mm and D = 60 mm, where the effective Joule heat generated by the induction coil occupies about 75% of the energy dissipated in the riser solidification process, at least. The better feeding effect can be obtained at L = 0 mm and D = 40 mm in consideration of the thickness of the insulation board.

Characterization of Hydraulic Fractures With Triaxial Electromagnetic Induction and Sector Coil Rotation Measurement

The characterization of hydraulic fractures is crucial for fracturing evaluation and strategy optimization. Low-frequency electromagnetic triaxial induction measurement is a promising candidate in hydraulic fracture characterization. However, it is difficult to accurately monitor fracture shape, orientation, and the multistage fracture network distribution. A novel method that combines triaxial induction measurement with sector-shaped coils axial rotation measurement (TIM-SCARM) is proposed to characterize hydraulic fractures. It is implemented by using the finite element method with transition boundary conditions (FEM-TBCs), which approximates the thin fracture as a surface to enhance the computational efficiency. The study focuses on quantitative analysis of conductivity, cross-sectional shape, half-length, and orientation of hydraulic fractures to assess their effects on specific configurations of the TIM-SCARM. Furthermore, the correlations between multicomponent signals and fracture characteristics are investigated. Numerical results indicate that the coaxial component signal in SCARM can distinguish the cross-sectional shape and orientation. The cross-polarized component signals provide important features of tilted fractures, and the 3-D signal obtained by instrument rotation could determine the spatial distribution of fracture networks. Therefore, measurements that integrate the multicomponent signals and axial information improve fracture geometry evaluation.

Influence of Dimensions on Detection Sensitivity of Position Detection Sensor for Railway Vehicle

One of the technologies for detecting the position of railway vehicles is a sensor that obtains the position information by detecting a metallic marker laid on the track and an electromagnetic induction coil mounted on a railway vehicle. The maximum distance between the marker and the coil is 250 mm. One of the methods to improve the detection sensitivity is to increase the size of the excitation coil or to increase the excitation frequency. However, these methods have the problem of limiting the installation area and radiating electromagnetic waves to other equipment. Therefore, under the condition that the size and frequency of the excitation coil are constant, we evaluate the effect of the size of the coil and the metallic marker on the detection sensitivity and proposed a method to improve the detection sensitivity of the position detection sensor for railway vehicle.

Study of magnetic pole materials for static magnetic field and dynamic magnetic field that compose an electromagnetic acoustic transducer for Lamb waves using the magnetostriction effect

For the purpose of strengthening the mechanical and thermal properties of an electromagnetic acoustic transducer (EMAT) for a Lamb wave, we considered changing the air-core electromagnetic induction coil that composes an EMAT to a structure in which a conducting wire is wound around a ferromagnetic material. Initially, as a ferromagnetic material, the structure was constructed in which an electromagnetic induction coil for a static magnetic field and an electromagnetic induction coil for a dynamic magnetic field were wound up and down on the same pole made of low carbon steel. As a result, the transmitted signal could be confirmed. Furthermore, in order to improve the received signal amplitude, we evaluated a structure that separates the magnetic poles for the static magnetic field and the magnetic poles for the dynamic magnetic field, and confirmed that the received signal amplitude can be improved. The purpose of this study is to determine the best combination and the structure of the steel, pure iron, PB perm alloy, and PC perm alloy as magnetic pole materials based on the results of this research. In the steel, pure iron, PB perm alloy, and PC perm alloy, when the material itself is not magnetized, the relative permeability decreases in the order of the PC perm alloy, PB perm alloy, pure iron, and steel. However, when the material itself is magnetized, the relative permeability decreases, and the degree of the decrease is reduced in the order of the PC perm alloy, PB perm alloy, pure iron, and steel. As a result of the experiment, the static magnetic pole and the dynamic magnetic pole are separated, and steel is suitable as the static magnetic pole, pure iron is suitable for the dynamic magnetic pole for the EMAT for transmission, and the PB perm alloy is suitable for the EMAT for reception. It was also clarified that the performance of the PC perm-alloy magnetic pole is improved by magnetically shielding the magnetic pole.

Design and Application of Early Warning Model for Electric Vehicle Charging Safety

In order to improve the charging safety of electric vehicles, it is necessary to design the early warning model of charging safety, so as to overcome the overload defects in the charging process of electric vehicles. An electric vehicle charging safety warning model was proposed based on contactless charging design. The electromagnetic induction coil and electromagnetic coupler installed on the charging pile are used to design the electromagnetic coupling induction with the driving electric vehicle tire wire, and the electromagnetic coupling control and charging stability adjustment of the electric vehicle are carried out by using the inductive power transmission technology. According to the overload regulation of electric vehicle during charging, the overload interruption control of electric vehicle charging is carried out by mutual inductance coupling method, and the parameters such as resonance frequency, mutual inductance coefficient and coil internal resistance during charging are analyzed. The parameter steady-state regulation method is used for non-contact charging, and the electric vehicle charging safety early warning control is realized, and the parameter optimization design of electric power transmission system in the process of electric vehicle charging is carried out. According to the parameter optimization result, the electric vehicle charging safety early warning test is realized. The test results show that the proposed method has good control performance and can effectively realize the wireless energy transmission of 100W in 100cm, the charging efficiency and the charging safety are improved.

Equivalent Capacitance Model of Segmented Induction Coil in Electromagnetic Exploration System for Deep Resources

The study on fixed-wing electromagnetic induction coil device is conducted according to the characteristics and requirements of deep resources aerial electromagnetic measurement system. In order to detect resources with different structures and forms, the system needs to support the measurement of varying magnetic field signals in a wide frequency range. The induction coil, as the information search probe, its equivalent capacitance parameter plays a key role in the frequency response bandwidth of the detection system. In this article, an analysis model of multi-segment coil is proposed. Through the calculation and analysis of the structural parameters of multi-segment coil, the distributed capacitance parameters of multi-segment coil can be effectively estimated to improve the design efficiency of the electromagnetic induction system. In addition, the key parameters that affect the equivalent capacitance parameters of multi-segment coils are summarized, and the key parameters of coil structure are compared and improved. Finally, the expansion of frequency response bandwidth of induction coils is realized. Through the comparative analysis of actual measurement, the working response bandwidth of the improved two structural coils is 1.29 and 1.19 times that of the original structural coils respectively, and the receiving sensitivity is also improved, which verifies the effectiveness of the proposed analytical model. The analysis shows that the equivalent capacitance parameters of the coil can be controlled more flexibly through the reasonable design of segment spacings and choosing the materials with suitable dielectric constant as the coil framework, so that the designed induction coil can be characterized by good frequency domain response.

The influence of pulse magnetic field intensity on the morphology and electrochemical properties of NiCoS alloys

In this study, we synthesized arrayed NiCoS alloys as electrode material of supercapacitors via a customized hydrothermal reaction device assisted by pulse magnetic field and studied the effect of pulse magnetic field intensity on the morphology and electrochemical performances of NiCoS alloys. The results showed that the diameter of the rod-shaped NiCoS alloys reaches its minimum value of 10 nm and the arrangement of the arrayed grains is most regular at a peak current density of 9Adm−2 flowing through the electromagnetic induction coil. Consequently, the specific capacity of that sample reaches a maximum value of 161.2 mAhg−1 at 2Ag−1, which drops to 118.7 mAhg−1when the current density increases from 2Ag−1 to 10 Ag−1. The optimized sample also exhibits an excellent long-term cycling performance with a retention ratio of 84.6% over 5000 cycles in 2 M KOH electrolyte. The remarkable electrochemical performances may be attributed to the effect of pulse magnetic field on the nucleation and growth of NiCoS alloys, which could enlarge its surface area and improve its crystal dendrite quality.

Progress in the development of a contactless ultrasonic processing route for alloy grain refinement

A high frequency tuned electromagnetic (EM) induction coil can be used to induce ultrasonic pressure waves leading to gas cavitation in alloy melts. This is a useful ‘contactless’ approach compared to the usual immersed sonotrode technique. One then expects the same benefits obtained in the traditional ultrasonic treatment (UST) of melts, such as degassing, microstructure refinement and dispersion of particles. However, such an approach avoids melt contamination due to probe erosion prevalent in immersed sonotrodes and it has the potential to be used on higher temperature and reactive alloys. Induction stirring due to the Lorentz force produced by the coil is an added benefit, allowing for the treatment of large melt volumes, a current limitation of UST systems. At ultrasonic frequencies (> 20 kHz), due to the ‘skin effect’ electromagnetic forces vibrate just a thin volume by the surface of the metal facing the induction source. These vibrations are transmitted as acoustic pressure waves into the bulk and to achieve sufficient fluctuation amplitudes for cavitation, acoustic resonance is sought by carefully adjusting the generator frequency. This is akin to the tuning of a musical instrument, where the geometry and sound properties of the metal, crucible and surrounding structure play an important part. In terms of modelling, this is a multi-physics system, since fluid flow with heat transfer and phase change are coupled to electromagnetic and acoustic fields. The various models used and their coupling are explained in this paper, together with the various complications arising by the physics of cavitation. Experimental validation is obtained on a prototype rig featuring a conical induction coil inserted into the melting crucible containing the various alloys being examined. When resonance is reached, measurements demonstrate strong stirring, evidence of cavitation and finally grain refinement.

Contactless Ultrasonic Cavitation in Alloy Melts.

A high frequency tuned electromagnetic induction coil is used to induce ultrasonic pressure waves leading to cavitation in alloy melts. This presents an alternative ‘contactless’ approach to conventional immersed probe techniques. The method can potentially offer the same benefits of traditional ultrasonic treatment (UST) such as degassing, microstructure refinement and dispersion of particles, but avoids melt contamination due to probe erosion prevalent in immersed sonotrodes, and it can be used on higher temperature and reactive alloys. An added benefit is that the induction stirring produced by the coil, enables a larger melt treatment volume. Model simulations of the process are conducted using purpose-built software, coupling flow, heat transfer, sound and electromagnetic fields. Modelling results are compared against experiments carried out in a prototype installation. Results indicate strong melt stirring and evidence of cavitation accompanying acoustic resonance. Up to 63% of grain refinement was obtained in commercial purity (CP-Al) aluminium and a further 46% in CP-Al with added Al–5Ti–1B grain refiner.

Optimised High-Order Compact Difference Schemes for Internal Acoustics Problems On Curvilinear Domains

A numerical framework is presented for the solution of 2D and 3D internal acoustics problems using a high-order accurate fully staggered formulation on curvilinear domains. Optimised compact finite difference schemes previously obtained in our previous paper are used for spatial discretisation, while a free parameter linear multistep method is used for temporal discretisation. The resulting scheme does not require any numerical filtering, and several benchmark cases are provided which demonstrate the significantly reduced phase velocity errors, and greater resolving efficiency compared to existing methods. Curvilinear domains are generated with the CRDT algorithm by Driscoll, with an 8th order accurate ODE solver. The governing equations for the curvilinear problem are based on a novel transformation of the decoupled velocity pressure wave equations, with simplifications made to reduce the need to interpolate derivatives at undefined locations which occur on staggered grids. The resulting transformed equations are valid only for orthogonal grids, but are computationally efficient and do not result in loss of accuracy or stability due to grid skewness. Finally, a potential application is shown, demonstrating the solution of a generated acoustic field within a crucible of liquid aluminium by a top loaded electromagnetic induction coil. Generated pressure fields agree with results shown in previous work, and demonstrate the potential use of this contactless electromagnetic excitation method as an alternative to the immersed sonotrode for the ultrasonic treatment of alloys.

Optimization and Analysis of Wire-Wound Coil Heads for EMI Systems

Many different coil head configurations are used in electromagnetic induction (EMI) systems for sensing buried targets; however, very little has been published on comparing the configurations. Comparing different coil head designs to one another is cumbersome because many factors determine how well different coil heads perform when constructed and attached to a system. Calculating the voltage received by a particular coil under ideal conditions is trivial, but this requires accounting for such factors as overall coil size, wire diameter, and conductivity. Comparing how only the winding geometries of various coil heads affect performance is much less straightforward. A set of normalized metrics that are independent of design decisions other than winding geometry are needed. This paper details a set of metrics for the characterization and comparison of EMI coil heads. These metrics are then used to optimize double-D, concentric, and dipole/quadrupole coil heads, which are then analyzed and compared to one another.

Effect of Coil Width on Deformed Shape and Processing Efficiency during Ship Hull Forming by Induction Heating

The main hull of a ship is made up of a large number of plates with complex curvatures. Line heating is one of the main approaches used in the forming of a ship hull plate. Because line heating is based on manual heating using a handheld oxyacetylene gun, the typical heating width is extremely narrow. With the development of computer control technology, a newly developed automated plate forming equipment is available and its heat source is typically an electromagnetic induction coil. The temperature field and the induction coil size are correlated. However, investigations into the induction coil size are scarce. In this study, the effect that the induction coil width has on both the forming shape and processing efficiency is investigated via simulation and test. The results show that a moderate expansion of the induction coil width at different input powers has an insignificant impact on forming shapes that is attainable by common line heating. However, as the heating width expands with the expansion of the induction coil width, the number of the processing lines via line heating is reduced which improves the processing efficiency.

A Pipe Inspection Using a Circumferential SH-Mode Plate Wave Generated in a Pipe by an Electromagnetic Acoustic Transducer (EMAT)

Inspection of a pipeline is essential for the safe use of such facilities. A trial sensor using an electromagnetic acoustic transducer (EMAT), which can generate the SH-mode plate wave propagating in the circumferential direction, has been developed to realize this objective. It consists of a circulating electromagnetic induction coil around the pipe and many permanent magnets arranged on the surface of the pipe in the circumferential direction. It is postulated that the intensity of the SH-mode plate wave propagating in the circumferential direction is dependent on any defects in the circumferential direction. A resonance method was then utilized to obtain a stronger received signal. As a result, it was confirmed that the resonance status can be detected. The relationship between the signal intensity and the pipe thickness was then evaluated. It was confirmed that the wall thickness of about 20% can be detected under a static condition. Finally, a moving test has been executed by using an axially traveling device manufactured by trial. The test pipes with different sizes of drilled holes were prepared. The change in the received signal intensity according to different sizes of the drilled holes was successfully detected.