Skin Effect Phenomenon Research Articles

On the issue of capacitively coupled circuits using to explain the mutual influence of wires

The wire, as a separate element, is practically never sanctified in the literature. There is no radio-electronic device without a wire. It is the frequency characteristics of the wire impedance that limit the frequency characteristics of the inductor impedance, i.e. limit the frequency range of the radio interference filter. Therefore, it is important to understand the physics of the processes occurring in the wire. In addition, it is important to understand how the wire “parasitic” parameters affect the other elements “parasitic” parameters. An explanation for the presence of capacitance in a wire equivalent circuit through the skin effect phenomenon is proposed in this article. The using of the concept of capacitively coupled circuits as a dual analogue of inductively coupled circuits is proposed. It is shown that the duality of inductively coupled circuits and capacitively coupled circuits is possible only due to the duality of the alternating vortex magnetic field and the alternating vortex electric field. The viability of using the concept of capacitively coupled circuits is shown using the example of the measured impedance of two wires in various variants of parallel connection.

Cool skin effect and warm skin phenomenon observed by shipboard radiometer in the Northwest Pacific

Sea surface temperature (SST) is an important variable in the study of ocean boundary layers and heat exchange. The accurate simulation and measurement of skin effects are vital to air–sea model processing and satellite SST retrieval. Shipboard measurements from eleven cruises in the Northwest Pacific between August 2015 and October 2018 were used to estimate the cool skin effect and compare model results. The temperature difference ΔT between the sea surface skin temperature (SSTskin), as measured by an infrared radiometer, and the sea surface depth temperature (SSTdepth) at around 4 meters showed a mean difference and a standard deviation of the same 0.2 K, with a total of 5-min 39909 measurements. Both daytime and nighttime ΔT values were compared to physical model simulations and were found to have relatively larger mean values. A set of new coefficients for an exponential parameterization of the cool skin effect was derived in the research area, which performed well in comparison to previous empirical models. In nighttime observations from two summer cruises, the reverse process of heat flux transfer from the air to the sea in the form of a warm skin was distinguished. There were 667 positive ΔT values out of the 1917 nighttime observations, with magnitudes ranging from around 0 to 0.3 K. A high proportion of the cases of the warm skin phenomenon occurred when the air was very humid and much warmer than the sea surface.

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

Numerical Calculation of Magnetic–Thermal Coupling and Optimization Analysis for Velocity Skin Effect

In this article, the explicit finite difference method is used to solve the magnetic-thermal coupling phenomenon of velocity skin effect (VSE), and the skin effect phenomenon at different velocities is analyzed. In order to reduce the VSE between the armature and the rail, the skin effect phenomena of the layered rail with graphite coating, the layered armature with Ti Mo Al metal, and the combined structure of the layered rail and the layered armature were studied, respectively. The results show that with the increase of velocity, the VSE gradually appears in the armature and rail, and the layered rail can weaken the adverse effect of the VSE. Although the layered armature can weaken the VSE, the physical properties of Ti Mo metal will cause the local temperature of the armature tail to be too high. Through the combination with the layered rail, the high temperature of the armature tail caused by the layered armature can be significantly improved.

Numerical investigations of heat transfer and skin effect characteristics within rods located in a 48-rod Siemens reactor heated by AC

Abstract In the polysilicon reduction furnace, all the energy is supplied by the heat generation on silicon rods which are heated up by the passage of electric current. The alternating current (AC) produces the alternating magnetic field, and the oscillating magnetic field induces the corresponding eddy current in the conductor, which causes the phenomenon of skin effect. In the present paper, the coupling model of thermal and electromagnetic field for the silicon rods has been developed by coupling Joule heating equation controlled by frequency and heat dissipation (radiation, convection and reaction energy). Comparing the calculated results with the industrial data, it is found that the average relative errors of the current intensities of the inner, middle and outer ring silicon rods are 7.55%, 5.55% and 7.43%, respectively, indicating that the model calculation results are accurate and can be used to accurately analyze the thermoelectric behavior of the silicon rods. Based on the Joule heating process of silicon rods in a 48-rod polysilicon reduction furnace, the influences of AC frequency on temperature and current density profile within rod arranged in different rings have been studied. The interesting results show that the high frequency current sources can generate an even temperature profile and an isothermal region inside the rod can be obtained when the RF increases to 10. Therefore, utilizing the high frequency current sources can decrease the temperature gradient within silicon rod effectively, which provides a method for producing larger diameter silicon rod. Furthermore, the voltage-current curves of low frequency (50 Hz) and high frequency (10 kHz and 50 kHz) can be predicted by the present Joule heating model, at the same time, a hybrid heating process of low frequency and high frequency is proposed.

Mathematical modelling of starting modes of induction motors with squirrel-cage rotor

Purpose. Development of methods and algorithms for calculation of starting modes of the induction motors with the squirrel-cage rotor. Methodology. Mathematical modelling of starting modes of asynchronous electric drives in various coordinate systems with the use of numerical methods for solving boundary problems for systems of differential equations and nonlinear systems of final equations and calculation with their use of static characteristics. Results. Methods and algorithms for numerical analysis of the starting modes of asynchronous electric drive have been developed, which make it possible to calculate the static characteristics and transients in fixed three-phase and orthogonal two-phase coordinate systems. Academic novelty. Known in the literature methods of calculation of starting modes have in their basis classical equivalent circuits with different approximate methods of calculating the parameters taking into account the saturation of a magnetic core and current displacement in a rotor winding. This approach requires a special solution of the adequacy problem for each problem. The methods described in the article for the saturation accounting use real magnetization characteristics of the main magnetic flux and leakage fluxes separately, and the skin effect phenomenon is taken into account by representing the squirrel-cage rotor winding as multilayer. Such mathematical model of the motor is universal and makes it possible to take into account the saturation and current displacement in any dynamic mode, including the start-up process. Mathematical models developed on the basis of the proposed methods provide the adequacy of results with a minimum amount of calculations and make it possible to perform optimization calculations. Practical value. Created on the basis of developed algorithms calculation programs allow to carry out with high reliability calculation of starting modes both in three-phase and two-phase axes of coordinates that gives the chance to analyze not only symmetric, but also asymmetric modes and to predict special features of functioning of system of the electric drive in the set technological conditions of operation and to form requirements to development and adjustment of starting systems with the purpose of maintenance of power effective and reliable operation of system of asynchronous electric drives.

Sequentially Coupled Simulation of Multiphysical Fields During Twin-Electrode Electroslag Remelting Process

A transient three-dimensional (3D) sequentially coupled mathematical model has been developed to explore multiphysical fields in the twin-electrode electroslag remelting (TE-ESR) furnace. The mechanical APDL module based on the finite element method and the Fluid Dynamics module based on the finite volume method were used to resolve the electromagnetic field and simulate the fluid flow, heat transfer, and solidification process, respectively. The resulting electromagnetic force and Joule heating were incorporated into the source terms of Navier–Stokes and energy conservation equations, respectively. The motion of molten metal droplets and fluctuation of slag/metal interface were tracked by the volume of fluid (VOF) approach. The enthalpy-based technique was employed to simulate the solidification. The results show that the current density is distributed uniformly due to the proximity effect. This is very different from the traditional ESR process during which the skin effect phenomenon is dominated. Besides, the current density is mainly distributed in the slag, only one-fifth flowing through the ingots. The magnitude of velocities in the molten slag is two orders of magnitude higher than those in the steel. The highest temperature zone in the TE-ESR process occurs in the middle of twin-electrode, whereas in the traditional ESR process it occurs beneath the electrode tip. Finally, parametric studies including melting rate, slag thickness, electrode diameter, and center distance have been conducted in detail.

Novel Multifrequency Eddy Current NDT Signal Inversion Scheme for Aerostructures

Abstract Flaw profile characterization from nondestructive evaluation measurements is a typical nondestructive testing (NDT) inverse problem. Flaw profiling, particularly in aerospace industry, is important, as it is a decision tool to evaluate the air worthiness of the aerostructures. Accurate flaw profiling thus ensures aircraft safety through the timely implementation of cost-effective replacement/repair actions. Eddy current (EC) NDT data acquired at multiple frequencies contain complementary information about the flaws due to the skin effect phenomenon. However, finding the exact contribution of each measurement mode while determining the solution to the inverse problem is considerably challenging. In the reported research work, a novel multifrequency EC data-based polynomial model is formulated to solve the inverse problem. The weight (coefficient) of each measurement mode in the polynomial model is computed using nonlinear optimization techniques. Actual NDT data of a retired aircraft containing mutually exclusive training and test databases has been used as a case study. Data fusion (DF)-based inversion results are compared to the results acquired using individual measurement mode data. The improved results with DF indicate the efficacy of the proposed technique.

Phenomenon of skin effect in metals due to hydrogen absorption

Experimental studies of the distribution of hydrogen in metal samples after a standardized saturation procedure in a neutral solution are described. It is shown that the hydrogen concentrates in a thin surface layer which plays the role of a shield for the further propagation of hydrogen. We refer to this phenomenon as a skin effect in the hydrogen saturation since the internal regions of the metal are not saturated by hydrogen. A review of similar experimental results for other standardized methods for saturation of metals with hydrogen (cathodic polarization, saturation in gaseous hydrogen) is provided, and the universal nature of the skin effect for metals is shown. The analysis of mechanisms of the skin effect is carried out by methods of continuum mechanics based on a bi-continual model of a solid. The problem of saturating a metal sample with hydrogen without external load is posed. It is shown that the model taking into account the mutual influence of hydrogen and mechanical stresses allows one to obtain solutions describing the highly non-uniform distribution of hydrogen at standardized saturation.

Application of the Shifted Frequency Internal Equivalence to Two Dimensional Lossy Objects

Performance of a new method, Shifted Frequency Internal Equivalence (SFIE) is studied in the analysis of scattering from two dimensional lossy objects. This method finds the solution of a wideband scattering problem faster than classical approaches.By introducing conductivity, loss shows itself as imaginary electrical permittivity. Changing conductivity also changes the distribution of electromagnetic waves and modifies RCS plots. In this study homogeneous and inhomogeneous conductive media are investigated to widen the usage of SFIE method. By increasing conductivity skin effect phenomenon is observed, electrical dimensions are decreased and RCS plots are flattened as expected.Numerical results obtained by SFIE are compared to the ones obtained by Method of Moments and the differences are shown.

PECULIARITIES OF THE MANIFESTATION AND INFLUENCE ON THE ELECTROMAGNETIC PROCESSES OF THE TRANSIENT SKIN EFFECT IN METAL CONDUCTORS WITH PULSED CURRENT

Purpose. Preparation of brief scientific review of basic results of the known theoretical researches of the electrophysics phenomenon of linear transient skin effect (TSE) in the non-magnetic homogeneous massive conductors of flat and cylindrical configurations on which in the discharge electric circuits of high-voltage electrophysical installations (EPHI) the pulsed currents ip(t) flow with given amplitude-temporal parameters (ATPs). Methodology. Theoretical bases of electrical engineering, bases of theoretical electrophysics, electrophysics bases of technique of high-voltage and high pulsed currents. Results. The brief scientific review of results of the known theoretical researches of the electrophysical phenomenon of linear TSE in non-magnetic homogeneous massive flat and cylindrical metal conductors with pulsed axial (azimuthal) current ip(t), formed in the discharge circuit of powerful high-voltage EPHI. In the generalized and systematized form the basic features of manifestation of linear TSE in the indicated conductors and influence of the considered skin effect on electromagnetic processes are presented at flow in conductors and discharge circuit of a high-voltage EPHI with the pulsed current ip(t) time-varying by law of attenuated sinewave. Influence of linear TSE is described in non-magnetic massive conductors during transient in a discharge circuit of EPHI with the pulsed current ip(t) of given ATP, depth of penetration of the electromagnetic field in materials of the indicated conductors, own integral electric parameters of the considered conductors and their good quality in the high-current discharge circuit of high-voltage EPHI. It is shown that at the analysis of electromagnetic transients in high-current discharge electric circuits of powerful high-voltage EPHI it is necessary to take into account flowing in materials of the examined massive conductors of such known electrophysical phenomenon as linear TSE. Originality. Generalization and systematization is first executed regarding domestic and foreign scientists-electrical engineers’ results of theoretical researches for long-term period of the electrophysics phenomenon of linear TSE in the flat and cylindrical metallic conductors of different thickness with the pulsed current ip(t)of given ATP. Practical value. The results presented in the generalized and systematized form will be useful for electrical engineers in deepening of understanding of basic features of manifestation in non-magnetic massive homogeneous conductors with the pulsed current ip(t) of given ATP of such widely widespread in area of high-voltage high-current pulsed technique electrophysics phenomenon as linear TSE and its influences on electromagnetic transients in similar metallic conductors and high-current discharge circuits of high-voltage EPHI.

Transient skin effect in power electronic applications

This study describes transient electromagnetic phenomena in electrical conductors that are connected to modern power electronic circuits and therefore subjected to current controlled pulses with fast rise times and high peak current ratings. Electromagnetic field diffusion is discussed and a brief review of alternating current skin effect phenomena is presented before it is generalised to transient regimes of operation. It is shown that the magnetic field diffuses into the conductor from the outside on the initiation of a current pulse and therefore the axial current density distribution inside the conductor changes with time under a transient current due to the well-known electromagnetic relations – the current begins at the conductor surface and diffuses inwards. The implications of such behaviour are briefly discussed in the context of modern power electronics and its applications.

Skin effect based technique in eddy current non‐destructive testing for thickness measurement of conductive material

This study proposes an estimation procedure for thickness measurement of conductive material by investigating the skin effect phenomenon in eddy current non-destructive testing. Both three-dimensional numerical modelling using the finite volume method and experimental analysis are considered. Before starting this investigation, the material to be measured must be recognised in terms of its electrical conductivity, and hence this study presents also an electrical conductivity characterisation which is identified by using two methods; the first one is the four-probe-based technique while the second one is an eddy current-based technique.

Synergy of Melt-Wave and Electromagnetic Force on the Transition Mechanism in Electromagnetic Launch

Synergy of melting wave and electromagnetic force on the transition mechanism is studied in this paper. The 3-D electromagnetic field, temperature field, and structure field coupling model are established to simulate the velocity skin effect and melting wave phenomenon. It is found that the melting wave and electromagnetic force together lead to the occurrence of transition. And the two are inextricably linked. The melting wave will enlarge the separating electromagnetic force on the armature trailing arm. The separating electromagnetic force may result in the reduction of contact area, which would accelerate the melting wave. It is getting worse and worse, eventually lead to the transition. And the analytical results are consistent with the experimental phenomena. The transition prediction method will be more accurate when combining the melt-wave and the electromagnetic force.

New derivation method and simulation of skin effect in biological tissue.

Based on the electrical properties of biological tissues, bioimpedance measurement technology can be employed to collect physiologic and pathologic information by measuring changes in human bioimpedance. When an alternating current (AC) is applied as a detection signal to a tissue, the current field distribution, which is affected by skin effect, is related to both the bioimpedance of the tissue and the AC frequency. These relations would possibly reduce the accuracy and reliability of the measurement. In this study, an electromagnetic theory-based method, in which cylindrical conductor were divided into layers, was used to obtain current field distribution models of human limbs. Model simulations were conducted in MATLAB. The skin effect phenomenon and its characteristics in human tissues at different frequencies were observed, thus providing essential data on skin effect, which are useful in the development of bioimpedance measurement technology.

Skin Effect Analysis for Pulse Current in the PEA Based on Frequency Domain Method

To study some of the mechanisms in passive electromagnetic armor (PEA), the pulse current skin effect and the action of the current along the length of a shaped charge jet as it passes through PEA are researched. Considering the different characteristic of the pulse current from the alternating current, a frequency domain analysis method of skin effect is introduced. With the background of PEA, time and frequency characteristics of the pulse current are analyzed based on the equivalent circuit model, and calculation method of the pulse current density distribution in shaped charge jet is obtained. Consequently, the skin depth during the discharge is researched. The validity of the method is approved by contrasting it with the Finite Element Method analysis results. Finally, a distribution of the specific action in the shaped charge jet elements is obtained based on the action time model. The results indicate that pulse current has a broadband, and its skin effect phenomenon is different from that of an alternating current. It shows that current density increases with the decrease in depth not all the time, but declines on the surface of the conductor at the trailing edge of the pulse current. And the specific action is concentrated on the tail of the jet whose velocity is less than 4 km/s. While the action in the radial direction becomes larger, the element gets closer to the surface.

Multiconductor cell analysis of skin effect in Milliken type cables

In this paper the multiconductor cell analysis (MCA) has been applied to Milliken type cables of large cross-section over 1600mm2. Since IEC 60287-1-1 does not provide values for the calculations of skin and proximity effects for these cases, these procedures become important to foresee skin effect values in the planning phase, where measurements are not possible. In order to develop a programmable procedure, an idealized M-type core with six sectors has been developed. It is composed of cylindrical wires inscribed on a hexagonal grid: it allows investigating the skin effect phenomena in many cross-sections (in the range 1600–2500mm2) without being constrained by the manufacturer techniques. The effects of lack of insulation between the wires have been also analysed. Comparisons with some measurements reported in technical literature show a good agreement.

DIFFERENCE BETWEEN OF PWM STRATEGIES FOR INVERTER FED INDUCTION MOTOR

Several sophisticated or "optimum" modulation strategies have been suggested for voltage source pulse with modulated (PWM) inverters for ac motor control. These modulation strategies may suppress specific low – order harmonics or minimize total harmonic.The effectiveness of these (PWM) techniques in minimizing harmonic and reducing torque pulsation is investigated analytically, and their performance is compared with that of the usual sinusoidal or sub-harmonic PWM approach. The influence of skin effect on motor (I2R copper losses) is taken into consideration, and harmonic core losses are compared. Peak current is also an important factor in inverter design, and the various modulation strategies are again compared on this basis. Fourier analysis techniques are used in order to allow skin effect phenomena to be taken into consideration and performance criteria are developed to allow comparisons of waveform quality with respect of harmonic copper and iron losses.

Properties of layered structures based on thin ferromagnetic films

Layered structures fabricated from thin ferromagnetic films (including structured ones) are proposed as bulk materials with high values of microwave permeability. Experimental data on microwave properties of such structures based on monolayer and multilayer nitrogen-doped iron films are presented. The influence of the skin effect, magnetostriction, and other physical phenomena on the microwave properties of such materials is discussed. The problem of the limiting values of permeability in the microwave band is considered in detail. Possible applications of such materials as radio-wave absorbing coatings and substrates for miniature stripline antennas are analyzed.

Computation of eddy-current density on ESP motor and well casings under different operating conditions

This paper presents a 2D finite-element analysis of the induced eddy currents on motor and oil well casings of an electrical submersible pump (ESP) oil lifting system. Simulation results revealed that the increase in motor-casing conductivity and/or permeability decreases the eddy-current density on the well casing, contrary to that on the motor casing. Further increase in one or both of these parameters leads to a decrease in both current densities as a result of the skin effect phenomenon. However, the increase of well casing conductivity and/or permeability increases the eddy-current density on the well casing, while that on the motor casing remains unchanged. Increasing the fluid-mixture conductivity does not have any effect on the eddy-current density on the well casing, and for further increase in the fluid conductivity it decreases drastically, contrary to that on the motor casing which remains constant. The higher the current imbalance (including single phasing) and/or motor eccentricity, the higher is the maximum eddy-current density. Consequently, the increase of eddy-current density leads to an increase of the motor and well casings’ temperature, where the latter is known to accelerate the corrosion rate. It can be concluded that the design parameters and the construction of the motor and well casings play an important role in their corrosion.