Flat Conductor Research Articles

Efficient pure oxygen separation with the unique graded porous supported symmetric flat mixed conductor ceramic membrane

A graded porous supported symmetric (GPSS) flat ceramic membrane made of a K2NiF4+δ type oxide (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ (PLNCG) is fabricated by aqueous tape casting. This membrane design stands out for its unique structure, consisting of a thin dense layer at its core and two graded porous substrates that adhere symmetrically to this middle layer. In comparison to previously reported PLNCG hollow fiber membranes, the GPSS membrane offers superior oxygen permeation flux, exceeding that of the hollow fiber membrane by more than four times. When using air as the feed gas and even when introducing CO2 into the feed gas or sweep gas, the membrane maintains a consistent oxygen permeation flux of 4.41 mL min−1 cm−2 (STP). This work demonstrates that by paying close attention to membrane structure, the oxygen permeation flux of flat membranes can surpass that of hollow fiber membranes. Given its exceptional oxygen separation performance, the PLNCG-GPSS membrane holds great potential for practical applications such as high-purity oxygen production, pure hydrogen production, oxygen-involved catalytical reactions, and CO2 capture and storage.

Oscillating flow of viscous electron fluids

An oscillating model of femtofluid flow in flat and cylindrical conductors has been developed for the first time. Solutions are obtained analytically based on transforms from real form to complexity form and numerically using the lattice Boltzmann method (LBM). It is shown that the behavior of femtofluid is determined by three dimensionless parameters Sh, Fo and Kn. The influence of each parameter on carrier transport was studied. An explanation is given for the skin effect and the decrease in current density with increasing oscillation frequency.

Towards a Holistic Approach to Inverter-Fed Machine Design: FEM-Based PDIV Prediction of Complete Windings

The Schumann inception criterion was used to predict the partial discharge inception voltage of insulation models representing both wire wound and form wound (hairpin) low voltage machines. It was found that the fitting parameter <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> (the logarithm of the critical number of electrons that define the transition from Townsend to streamer discharge) is almost independent of material parameters when dealing with a given type of insulation (e.g., turn-to-turn using round conductors or flat conductors). These numbers can be fed to software for finite element analysis to provide a worst-case estimate of the partial discharge inception voltage.

Winding Loss Suppression in Inverter-Fed Traction Motors via Hybrid Coil Materials and Configurations

In a typical inverter-fed AC drive system, the stator windings carry a current with a large harmonics content, resulting in an increased AC loss. In this paper, the additional copper losses caused by non-sinusoidal currents are investigated for different magnet wire topologies, including the flat conductor, stranded, and litz wires. Also, a two-slot simplified model is introduced for accurate prediction of the AC losses at high frequency. It is found that one of the major issues of the conventional copper coil is that the losses are not uniformly distributed across the slot, and over 70% of the losses are concentrated near the slot opening. Moreover, using the transient finite element method, different winding topologies and arrangements are simulated at the stranded level to evaluate the losses and current density for each strand under highly distorted currents. Furthermore, different coil samples are prototyped for the same slot geometries to compare their performance under the same pulse-width modulation (PWM) waveforms for a wide range of frequencies. Finally, new hybrid coil topologies are proposed, which employ different magnet wires or materials within the same slot. The results demonstrate that utilizing a mixed wire configuration can effectively mitigate the adverse effects of eddy current losses. This approach can yield up to 16–41% lower losses while also achieving a weight savings of 36–70%.

Investigation on magnetic shield thickness of remote field eddy current probes for inspection of ferromagnetic and non-ferromagnetic plates

Since Remote field eddy current (RFEC) detection technology is barely limited by the skin effect, it can realize the defect detection of large-thickness components. Whereas, the structure of the RFEC probe for the planar conductor is complicated, resulting in an oversized probe. This hinders the application and development of the RFEC testing technology. In this paper, finite element simulations and experimental verification are used to optimize the RFEC probe structure for flat conductors. The results have shown that the thickness of the magnetic shield is the dominant factor in achieving high performance of RFEC inspection of flat conductors. When inspecting both ferromagnetic and non-ferromagnetic flat conductors, cylindrical magnetic shields with appropriate thickness and appropriate excitation frequencies are preferred for improvement of RFEC testing.

Wideband Absorbing Metasurface for Improving Axial Ratio of a Compact Archimedean Spiral Antenna

A wideband absorbing metasurface is proposed to improve the circularly polarized response of a 1–18 GHz low-profile Archimedean spiral antenna. The metasurface consisting of surface-mounted resistors between metallic patches in a circular arrangement is placed on the opposite side of the antenna substrate. After analyzing the unit cell behavior under an equivalent three-conductor transmission line, a concentric arrangement of the metasurface under the spiral is proposed. This metasurface is designed to absorb the edge-reflected waves to improve the circularly polarized response of the antenna below 6 GHz. The antenna substrate with the metasurface is placed above a flat conductor that makes an overall antenna height of 5 mm. After numerical investigations, a prototype is fabricated and characterized. The measured right-hand circularly polarized gain is positive above 2 GHz with a maximum gain of approximately 8.7 dBic at 10.6 GHz. An axial ratio (AR) better than 3 dB is observed above 1.125 GHz. The benefits of the metasurface compared to a commercially available absorbing material are highlighted, and its usefulness to design a compact spiral antenna is presented.

An Improved Parameter-Free Fault Locator for Untransposed Line With Unsynchronized Terminals

This letter presents a novel parameter-free fault location algorithm for a two-terminal single circuit untransposed line with flat and delta conductor configurations while considering unsynchronized measurements. It improves the existing works by introducing unequal angles of synchronism mismatch in pre-fault and fault conditions. EMTP-RV based simulation results corroborate the validity and accuracy of the developed fault location algorithm. Simulation results are also compared with existing methods to demonstrate improved features of the proposed algorithm. Field test results are also presented to further validate the performance of the proposed algorithm.

Multiphysics design and fabrication of 3D electroplated VIA materials topographies for next generation energy and sensor technologies

3D micro and nanoconductors have emerged as essential components of next generation energy and sensor technologies. This work investigates novel methods to tailor the topography of electroplated 3D conductive components, such as VIAs, using the FEM in COMSOL Multiphysics. This enables meeting the design specifications of flat, convex, or concave substrate-distal electroactive surfaces. Flat conductor surfaces are ideal for microbump soldering and flip-chip fabrication methods and concave/convex designs increase the number of available electrode reaction sites for sensor applications. 2D/3D multiphysics simulations are performed comprising: (1) electrochemistry modeling with the Nernst-Planck and Butler-Volmer formulations for mass transfer and reaction kinetics, and (2) a deformed geometry physics module to track the growing electrode during electrodeposition. Simulation results are compared to directly corresponding experimental work, with positive correlation. Our findings enable tailored and scalable electroactive surface processing options, which can be readily integrated into pre-existing research and industry standard operating procedures.

Mitigation of High-Frequency Eddy Current Losses in Hairpin Winding Machines

In high-speed and high-frequency electric machines, one of the major issues that impacts the performance and capability of a machine is the high-frequency eddy current losses in the windings. This work deals with AC winding losses in flat rectangular conductors. Aiming for eddy current loss mitigation, two different materials are investigated and compared for the same winding design, namely copper and aluminum. Using the finite element method (FEM), the conductor loss and current density behavior are simulated at the strand level. Further, in order to verify the simulated losses, the AC losses are measured and compared over a wide range of frequencies. Finally, recommendations are provided based on the obtained measurements to identify the best winding topology that is most suitable for automotive applications.

Performance Comparison and Analysis of Different Rotor Structures of Vehicle Permanent Magnet Synchronous Flat Wire Motor

In this paper, we designed flat conductor winding permanent magnet synchronous motors with three different rotor structures under certain boundary conditions. The causes of the noise vibration harshness and abnormal noise of permanent magnet synchronous motors are analyzed by using an analytical method. The causes of 24-order and 48-order abnormal noise are given. Based on the comparison of the performance of three rotor structures, the V+1 rotor structure has the least no-load harmonic content, the minimum cogging torque, the maximum output torque, the lowest temperature rise, and the best motor performance, and the V+1 rotor design consumes less permanent magnet material. The simulation is verified by manufacturing a prototype, and the experimental results verify the correctness of the simulation.

A Software Package for the Modeling of Electrophysiological Activity Data

A complex of programs has been developed for computer modeling of multichannel time series recorded in various experiments on electromagnetic fields created by the human body. Sets of coordinates and directions of sensors for magnetic encephalographs of several types, electroencephalographs and magnetic cardiographs are used as models of devices. To study the human brain, magnetic resonance tomograms are used as head models; to study the heart, a body model in the form of a half-space with a flat boundary is used. The sources are placed in the model space, for them the direct problem is solved in the physical model corresponding to the device used. For a magnetic encephalograph and an electroencephalograph, an equivalent current dipole model in a spherical conductor is used, for a magnetic cardiograph, an equivalent current dipole model in a flat conductor or a magnetic dipole model is used. For each source, a time dependence is set and a multichannel time series is calculated. Then the time series from all sources are summed and the noise component is added. The program consists of three modules: an input-output module, a calculation module and a visualization module. The input-output module is responsible for loading device models, brain models, and field source parameters. The calculation module is responsible for directly calculating the field and transforming coordinates between the index system and the head system. The visualization module is responsible for the image of the brain model, the position of the field sources, a graphical representation of the amplitude-time dependence of the field sources and the calculated values of the total field. The user interface has been developed. The software package provides: interactive placement of field sources in the head or body space and editing of the amplitude-time dependence; batch loading of a large number of sources; noise modeling; simulation of low-channel planar magnetometers of various orders, specifying the shape of the device, the number of sensors and their parameters. Magnetic and electric fields produced by sources in the brain areas responsible for processing speech stimuli are considered. The resulting multichannel signal can be used to test various data analysis methods and for the experiment planning.

Rigorous Electromagnetic Modeling of a Micro Strip Line Incorporating a Flat and Thick Metallic Conductor Based on the Skin Effect Phenomenon

Rigorous Electromagnetic Modeling of a Micro Strip Line Incorporating a Flat and Thick Metallic Conductor Based on the Skin Effect Phenomenon

Electric explosion of flat copper conductors in asymmetric and symmetric configurations in the current skinning mode

Plasma formation on the surface of conductors as a result of a skin explosion is one of the key issues of the efficiency of energy transportation along the vacuum lines of terawatt-level pulsed generators. Experimental studies of plasma formation on the surface of flat conductors were carried out on the MIG generator (current level ~ 2.5 MA, rise time ~ 100 ns). The magnitude of the magnetic field induction exceeded the values required for the explosion of the conductor surface facing the magnetic field in an asymmetric configuration or both surfaces of the conductor in a symmetric configuration. It was shown that in both configurations, a plasma channel is formed on the surface of a copper foil with a thickness of 100 microns along its longitudinal axis. Experimental data on the dynamics of plasma formation at the edges of a flat conductor have been obtained. A magnetohydrodynamic simulation of an explosion in strong magnetic fields of flat conductors whose width is much greater than their thickness showed that: the expansion of the plasma along the width of the conductor is suppressed, and the plasma expands mainly along its thickness. The simulation results are in good agreement with the experimental once.

A small footprint printed cross-dipole antenna with wide impedance bandwidth and circular polarization

Wideband circularly polarized (CP) cross-dipole antennas with flat, cavity and artificial magnetic conductor (AMC) reflectors are proposed. Each proposed antenna consists of a pair of driven dipoles, a pair of vacant-quarter printed rings, and a 50Ω coaxial probe. The boomerang shape has been adopted in the crossed-dipole. This shape makes the design more compact, so it can be a good candidate in the antenna array because of reducing the mutual coupling. All numerical simulation works have been done using the ANSYS electromagnetic (EM) software based on the finite element method (FEM) algorithm. The presented crossed-dipole with a cavity has the best performance compared to ones with conventional flat and AMC grounds. However, the crossed-dipole with the AMC ground is a low-profile structure. Thus, the paper investigates and discusses the results of the proposed strctures thoroughly. The obtained impedance bandwidth (IBW) is 42% (5.1-7.85 GHz) and the axial-ratio bandwidth (ARBW) is 7.72% (5.86-6.32 GHz) for the crossed-dipole with the conventional flat ground (i.e., reflector). Furthermore, the IBW and ARBW for the antenna with the cavity reflector are 50.37% (5.08-8.5 GHz) and 26.4% (5.72-7.46 GHz), respectively. The antenna with the AMC ground has the characterstics of the IBW and ARBW as 38.16% (5.36-7.89 GHz) and 15.16% (5.79-6.74 GHz), respectively. All structures are designed to operate for the C-band and wireless local area networks (WLAN) applications.

Electromagnetic Forces Acting on Thin Flat Conductors of Pulse Power Equipment

The analysis of transverse electromagnetic forces acting on the edges of thin conductors during the flow of large impulse currents is carried out. Using the obtained analytical solutions and numerical modeling, the dependence of these forces on the current rise time to the maximum, configuration, and relative position of the conductors is demonstrated. The studies were carried out for single-wire and multiwire systems of flat conductors with current rise time variation within wide limits. It is shown that, when the current distribution changes from uniform to the corresponding ideal conductivity, the forces decrease by no more than two times. It is also shown that, in a number of cases in the system conductor-ideally conducting screens-there is no dependence of the transverse forces acting on the edges of the conductor on the frequency of the current.

An analytical approach to rotor blade modulation

Scattering of electromagnetic plane waves normally incident on a flat perfect electric conductor strip in arbitrary rotational motion in its own plane is investigated in the context of Hertzian Electrodynamics. This canonical problem is an analytical-asymptotic approach that reveals the parametric dependence of interference of electromagnetic waves with rotating blades, a subject which is known as rotor blade modulation. Scattering by a stationary perfect electric conductor strip under TE and TM incidences stand as two sub-problems that are incorporated in the main formulation. These sub-problems are formulated by Wiener–Hopf Technique and solved using a spectral iteration method that converges rapidly in the solution of corresponding coupled dual Fredholm type integral equations in case of electrically wide strips. Numerical implementations that simulate electromagnetic scattering by helicopters blades and wind turbines are provided and discussed.

Fast Computation Method for Stator Winding Skin-Effect Additional Losses in Synchronous Machines With Open Slots and Arbitrary Rotor Geometry

Large medium-voltage electric machine stators are usually equipped with form wound coils made of flat conductors (strands) and embedded in open (rectangular) slots. Air-gap magnetic flux lines can enter the slot and, sweeping the strands placed nearest the slot opening, induce eddy currents in them. Such eddy currents cause additional losses which can be much higher than usual skin-effect and proximity losses. In order to avoid dangerous overheating and hot spots, the additional losses in question need to be carefully predicted in the design stage. Time-stepping finite-element analysis (TSFEA) can be used for the purpose, which however implies a large computational burden and requires the machine geometry to be modeled in detail. This article proposes alternative methods based on time-harmonic finite-element analysis (THFEA) simulations performed on highly simplified machine models and with no need to take rotor motion into account. The proposed methods are shown to produce very accurate results, compared to TSFEA, but with very significant time and computational savings.

Application of a dagger probe for soil dielectric permittivity measurement by TDR

The most basic parameter of soil is volumetric water content (VWC). This parameter is typically determined indirectly, based on other parameters. Currently, a widely used method for indirect VWC determination is a method which is based on soil dielectric permittivity (DP) measurement, using the well-known Topp formula. The paper presents a novel probe for soil VWC and electrical conductivity (EC) measurement employing the above method. The new probe is going to be adopted on a mobile plant-watering machines used in precise agriculture e.g. for plants watering, thus it features a robust mechanical design and allows for instantaneous readout of VWC and EC values. The design of the probe mimics a dagger with three flat conductors forming a short-circuited coplanar waveguide with the space between the conductors filled with a mineral cold-curing resin. The resin filling the space between the bars improves the mechanical stiffness of the probe and ensures constant electrical parameters, which increases the measurement accuracy. In the first step, Ansys HFSS software was used to perform electromagnetic (EM), numerical simulations for the proposed solution, in order to determine the optimal electrical parameters of the probe. Next, a probe prototype was made to carry out laboratory tests. The measurements were performed with the use of a vector network analyzer (VNA) in the frequency range (3.74 MHz − 3 GHz). The measured complex reflection coefficients were transformed into the time domain with the use of the inverse Discrete Fourier Transform (IDFT). Based on the time distance between the reflections of an electric pulse traveling along the probe's sensing element, bulk dielectric permittivity of soil surrounding the probe can be calculated. A linear relation between the square root of DP and the pulse propagation time was obtained. Also, the probe was calibrated for bulk electrical conductivity measurements.

THE USE OF FERROMAGNETIC AMORPHOUS MATERIALS 5BDSR IN HIGH-FREQUENCY OVERVOLTAGE PROTECTION DEVICES

The paper discusses the prospects of using nanocrystalline amorphous materials in the electric power industry. In particular, in the field of protection of electric power equipment of substations from high-frequency pulses. The effectiveness of using such materials to activate the anomalous skin effect in multilayer conductors is shown. The resulting conductors increase their resistance at lightning frequencies, thereby making it possible to create devices that effectively suppress high-frequency pulses. The authors give an example of a protective frequency-dependent device using nanocrystalline ferromagnetic material and the results of its use in trial operation. The paper shows the results of comparing round and flat frequency-dependent conductors.

Busbar Current Measurement With Elliptical Sensor Arrays Without Conductor Specific Calibration

In highly efficient power electronic systems, circular arrays of magnetic field sensors offer numerous advantages compared to older magnetic core-based sensors. They feature low power consumption, low weight, and high immunity to external magnetic fields. In power converters, conductors with a rectangular cross section, a small height, and a large width are widely used. Thus, an elliptical sensor array could reduce the space needed for the current sensor, e.g., in a power converter by a factor of four or more compared to a circular sensor array. In this work, we theoretically and experimentally study the sensitivity error caused by the change of the conductor geometry. Therefore, we calibrated different elliptical sensor arrays on a circular conductor and determined the sensitivity error for the use of flat conductors with different widths. This calibration on a circular conductor avoids a costly conductor-specific calibration of the sensor array in the application. Two different distribution methods for elliptical sensor arrays and different ratios of the semiaxes are considered. In addition, the influence of the number of sensors and the starting position for the sensors are examined. The presented elliptical sensor arrays can be used to measure the current carried by a flat conductor largely independent of its width. For some aspect ratios, they even offer a lower sensitivity error than circular sensor arrays. In this article, design considerations for those elliptic sensor arrays are given.