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1 – 10 of over 1000
Article
Publication date: 2 March 2015

Marcin Ziolkowski and Stanislaw Gratkowski

In many different engineering fields often there is a need to protect regions from electromagnetic interference. According to static and low-frequency magnetic fields the common…

Abstract

Purpose

In many different engineering fields often there is a need to protect regions from electromagnetic interference. According to static and low-frequency magnetic fields the common strategy bases on using a shield made of conductive or ferromagnetic material. Another screening technique uses solenoids that generate an opposite magnetic field to the external one. The purpose of this paper is to discuss the shielding effect for a magnetic and conducting cylindrical screen rotating in an external static magnetic field.

Design/methodology/approach

The magnetic flux density is expressed in terms of the magnetic vector potential. Applying the separation of variables method analytical solutions are obtained for an infinitely long magnetic conducting cylindrical screen rotating in a uniform static transverse magnetic field.

Findings

Analytical formulas of the shielding factor for a cylindrical screen of arbitrary conductivity and magnetic permeability are given. A magnetic Reynolds number is found to be an appropriate indication of the change in magnetic field inside the screen. Useful simplified expressions are presented.

Originality/value

This paper treats in a qualitative way the possibility of static magnetic field shielding by using rotating conducting magnetic cylindrical screens. Analytical solutions are given. If the angular velocity is equal to zero or the relative permeability of the shield is equal to one the shielding factor has forms well known from literature.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 June 2005

H. Waki, H. Igarashi and T. Honma

To analyze effectively magnetic shielding effects by shields with fine structure.

Abstract

Purpose

To analyze effectively magnetic shielding effects by shields with fine structure.

Design/methodology/approach

Simplification of the fine structure makes it possible to analyze them efficiently. The authors have introduced a homogenization method to estimate effective permeability of magnetic composite structure for the static field. The homogenization method is applied to the analysis of magnetic shields composed of steel plates and steel rods against DC power lines to test its feasibility.

Findings

The properties of the magnetic shielding are analyzed by using the homogenization method. The errors of the magnetic fields increase in case of very few layers.

Originality/value

The simplification of the magnetic shields with fine structure by using the homogenization method makes it possible to analyze efficiently magnetic shielding effects, although the accuracy becomes worse in case of very few layers.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 December 2005

Peter Sergeant, Luc Dupré, Lode Vandenbossche and Jan Melkebeek

To study the magnetic shielding and the losses of non‐linear, hysteretic multilayered shields by using fast to evaluate analytical expressions.

Abstract

Purpose

To study the magnetic shielding and the losses of non‐linear, hysteretic multilayered shields by using fast to evaluate analytical expressions.

Design/methodology/approach

In order to evaluate the shield in the frequency domain, the non‐linear shield is divided into a sufficient number of piecewise linear sublayers. Each sublayer has a permeability that is constant (space independent) and complex (to model hysteresis). This expression for the permeability is found from the Preisach model by a Fourier transform. Once H is known in the entire shield, analytical expressions calculate the eddy current losses and hysteresis losses in the material. The validity of the analytical expressions is verified by numerical experiments.

Findings

In the Rayleigh region, the shielding factor of perfectly linear material is better than the one of non‐linear metal sheets, but also the eddy current losses are higher. The results of the optimization show that steel is only a useful shielding material at low frequencies.

Research limitations/implications

The analytical method is valid for infinitely long shields and for weak imposed fields in the Rayleigh region.

Practical implications

As the analytical expressions can be evaluated very fast (in comparison with slow finite elements models), many magnetic shields can be compared in parametric studies.

Originality/value

Analytical expressions exist for the shielding factor and the losses of linear materials. In this paper, the method is extended for non‐linear hysteretic materials. The effects of several parameters (material parameters, incident fields parameters) on the shielding and the losses are shown.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 11 September 2009

A. Canova and L. Giaccone

The purpose of this paper is to present a new concept of passive loop technique called “high magnetic coupling passive loop” (HMCPL) (suitable for buried power lines) along with…

Abstract

Purpose

The purpose of this paper is to present a new concept of passive loop technique called “high magnetic coupling passive loop” (HMCPL) (suitable for buried power lines) along with optimised design parameters.

Design/methodology/approach

The optimal design (geometrical displacement and shielding current intensity and phase) for the mitigation of magnetic field produced by flat and trefoil configuration of the power line is carried out by means of genetic algorithm.

Findings

Different layouts for the source (flat and trefoil configuration) and the shield (introduction of the phase splitting technique) are designed. The optimization parameters are the coordinates of the shield conductors and the transformer ratio of the magnetic core that couple the source and the shield. Moreover, physical constraints as maximum depth of excavation and geometric interference between cables were introduced in the optimization procedure.

Originality/value

The paper deals with a very new technology for field mitigation called HMCPL. Actually, the base layout of the HMCPL does not need an optimal design. On the other hand, in some applications the base layout cannot be used, therefore, the introduction of an optimal design cannot be avoided. In this paper, the optimal design of several configurations is performed showing that the performances of the HMCPL are very interesting even if the base layout cannot be used.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 16 April 2020

Paul Clérico, Xavier Mininger, Laurent Prévond, Thierry Baudin and Anne-Laure Helbert

This paper aims to investigate the efficiency of a laminated composite for shielding applications. The solution has to be efficient not only for the shield against static magnetic

Abstract

Purpose

This paper aims to investigate the efficiency of a laminated composite for shielding applications. The solution has to be efficient not only for the shield against static magnetic fields but also “for low-frequency ones, in order to be well-suited for applications with electromagnetic perturbations in the frequency range DC to 100 kHz.”

Design/methodology/approach

The composite constituted of a steel sheet taken in a sandwich between two aluminum (Al) sheets is produced by cold roll bonding. A good adherence between Al and steel sheets, ensuring a good mechanical resistance, is obtained with a specific process. A previous study has shown that the optimal trade-off between adherence and magnetic shielding effectiveness (SEH) is obtained with a 230 µm composite produced with an initial thickness of Al and steel sheets, respectively, of 250 and 100 µm. In this paper, the 230 µm Al/steel/Al composite is used in three applications modelized by two-dimensional numerical simulations. To obtain reasonable computation time for the simulations, a homogenization method is applied to the composite. Studied applications are a cylindrical box containing a coil, a square box under an external magnetic field and a high voltage cable.

Findings

In each application, SEH is calculated at low frequency and different materials (Al/steel/Al, Al, steel and copper) are compared. It is observed that, in each application, the composite presents higher SEH at equal mass, especially for frequencies between 5 and 100 kHz.

Originality/value

The proposed approach, from the material point of view to the system consideration, shows that the thin bimetallic composite is an innovative and promising solution for magnetic shielding in the case of applications with both DC and low-frequency perturbations.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 39 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Open Access
Article
Publication date: 28 April 2022

Shichao Jiang, Xinliang Lu, Hongliang Wang, Kai Song and Yuanyuan Jiang

Detection of hidden defects of aluminum alloy plate with damping coating is a challenging problem. At present, only a few non-destructive testing methods exist to address this…

Abstract

Purpose

Detection of hidden defects of aluminum alloy plate with damping coating is a challenging problem. At present, only a few non-destructive testing methods exist to address this engineering problem. Without the restriction of skin effect, remote field eddy current (RFEC) overcomes the interference caused by the damping coating. The RFEC, which has potential advantages for detecting the hidden defects of aluminum plate with damping coating, can penetrate the metal plate to detect buried depth defects. This study aims to test how thick the RFEC sensor can penetrate the metal plate to detect the buried defects.

Design/methodology/approach

The magnetic field distribution characteristics are analyzed, the magnetic field intensity distribution is calculated, and the structure and parameters of the coil, magnetic circuit and shielding damping are determined through the two- and three-dimensional finite element simulation methods. Optimal excitation frequency is obtained, and the distance between the excitation coil and detection coil is determined by analyzing the relationship between excitation frequency and remote field points.

Findings

Simulation and experimental results verify the feasibility of applying the RFEC detection technology in detecting the hidden defects of aluminum alloy plate with damping coating.

Originality/value

In this paper, the RFEC testing model of hidden defects in aluminum plate sample with damping coating is established by using the finite element method.

Details

Sensor Review, vol. 42 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 16 August 2021

Zhiguang Cheng, Behzad Forghani, Zhenbin Du, Lanrong Liu, Yongjian Li, Xiaojun Zhao, Tao Liu, Linfeng Cai, Weiming Zhang, Meilin Lu, Yakun Tian and Yating Li

This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside magnetic

126

Abstract

Purpose

This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside magnetic and non-magnetic components under harmonics-direct current (HDC) hybrid excitations. As a new member-set (P21e) of the testing electromagnetic analysis methods Problem 21 Family, the focus is on efficient analysis methods and accurate material property modeling under complex excitations.

Design/methodology/approach

This P21e-based benchmarking covers the design of new benchmark models with magnetic flux compensation, the establishment of a new benchmark measurement system with HDC hybrid excitation, the formulation of the testing program (such as defined Cases I–V) and the measurement and prediction of material properties under HDC hybrid excitations, to test electromagnetic analysis methods and finite element (FE) computation models and investigate the electromagnetic behavior of typical magnetic and electromagnetic shields in electrical equipment.

Findings

The updated Problem 21 Family (V.2021) can now be used to investigate and validate the total power loss and the different shielding performance of magnetic and electromagnetic shields under various HDC hybrid excitations, including the different spatial distributions of the same excitation parameters. The new member-set (P21e) with magnetic flux compensation can experimentally determine the total power loss inside the load-component, which helps to validate the numerical modeling and simulation with confidence. The additional iron loss inside the laminated sheets caused by the magnetic flux normal to the laminations must be correctly modeled and predicted during the design and analysis. It is also observed that the magnetic properties (B27R090) measured in the rolling and transverse directions with different direct current (DC) biasing magnetic field are quite different from each other.

Research limitations/implications

The future benchmarking target is to study the effects of stronger HDC hybrid excitations on the internal loss behavior and the microstructure of magnetic load components.

Originality/value

This paper proposes a new extension of Problem 21 Family (1993–2021) with the upgraded excitation, involving multi-harmonics and DC bias. The alternating current (AC) and DC excitation can be applied at the two sides of the model’s load-component to avoid the adverse impact on the AC and DC power supply and investigate the effect of different AC and DC hybrid patterns on the total loss inside the load-component. The overall effectiveness of numerical modeling and simulation is highlighted and achieved via combining the efficient electromagnetic analysis methods and solvers, the reliable material property modeling and prediction under complex excitations and the precise FE computation model using partition processing. The outcome of this project will be beneficial to large-scale and high-performance numerical modeling.

Article
Publication date: 6 July 2015

Elzbieta Lesniewska

The purpose of this paper is to discuss the operation of new generation electromagnetic current-to-voltage transducer. The aim of research was analysis of behaviour of considered…

Abstract

Purpose

The purpose of this paper is to discuss the operation of new generation electromagnetic current-to-voltage transducer. The aim of research was analysis of behaviour of considered current-to-voltage transducers during operation. The main problem was to estimate whether the external fields are able to change the value of the secondary voltage and that the replacement of the casing material by a conductive or ferromagnetic material will increase the immunity of the transducer to external magnetic fields. The immunity of current-to-voltage transducers to the external fields is very important because it influences the proper functioning of the protection system.

Design/methodology/approach

The use of analytical methods to assess the influence of external fields was impossible due to the complexity of the geometry. The 3D computations were necessary because of different cross sections of circuit boards at different heights. Therefore the numerical 3D field-and-circuit method based on finite element method was applied. The wide range of dimensions in computation system, ranging from 0.15 mm (print paths) to 0.22 m, made it necessary to use the mesh of millions of elements. The division of this type of system into elements requires a diverse and extremely dense mesh in the area of printed circuits board (PCBs).

Findings

The 3D analysis of magnetic field distribution was performed for different external field effect upon a current-to-voltage transducer. The magnetic field distributions and the induced secondary voltage for several different cases were presented. As a conclusion it can be said that in this particular case the magnetic shield is most effective. The influence of external magnetic fields caused by currents passing through the other neighbouring phase bars near are insignificant for the transducer with non-magnetic core.

Practical implications

Commonly used in measuring and protection systems of the transmission lines are induction instrument transformers. The instrument transformers are very precise devices and their errors are counted in tenths of a per cent, and phase displacement of signals in minutes. Especially in HV systems they are very big and their cores are heavy. Replacement of instrument transformers by the current to voltage transducers cooperating with electronic measuring systems will reduce the size and cost of devices.

Originality/value

The requirements set for protective current transformers concern the transformation of currents, with high accuracy, especially at transient states. Therefore magnetic characteristics of their cores should be linear. It causes that cores are large and have some air gaps. Current-to-voltage transducers based on Rogowski coil are particularly suitable for the replacement of the protective current transformers because of their linearity. The traditional technologies used for making Rogowski coil consisted in winding a wire on a non-magnetic carcass. The development of technology has enabled the use of new technologies PCB high density interconnect in the production of Rogowski coil.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 December 2005

Peter Sergeant, Luc Dupré and Jan Melkebeek

To design an optimal active shield for the mitigation of the magnetic stray field around an induction heating device.

Abstract

Purpose

To design an optimal active shield for the mitigation of the magnetic stray field around an induction heating device.

Design/methodology/approach

The active shield consists of several compensation coils in series and generates a counter field opposite to the main field. One extra compensation winding – the “generating compensation winding” (GCW) – is positioned close to the excitation coil and works as the secondary winding of a transformer. The power in this winding is used to drive the other compensation coils (the active shield), which are the load of the transformer. A circuit with passive components is inserted between the GCW and the other compensation coils. The shield is optimal if it achieves a high field reduction, while the energy dissipation is low. By using a genetic algorithm (GA) that minimizes an objective function, the optimization algorithm finds the optimal geometry and the optimal current for the GCW and the other compensation coils. The objective function uses time harmonic and axisymmetric finite element calculations.

Findings

The transformer driven active shield reduces the magnetic field effectively. It is cheap and easy to build, but it works well only for one frequency.

Research limitations/implications

The shield is sensitive to tuning of the passive circuit and to changes in the frequency of the induction heater.

Practical implications

This transformer driven shield is an alternative for the classical active shield with external power supply.

Originality/value

An active shield that does not need an external power supply is a cheap solution for the shielding of magnetic fields.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 14 June 2022

Rie Isshiki, Ryota Kawamata, Shinji Wakao and Noboru Murata

The density method is one of the powerful topology optimization methods of magnetic devices. The density method has the advantage that it has a high degree of freedom of shape…

Abstract

Purpose

The density method is one of the powerful topology optimization methods of magnetic devices. The density method has the advantage that it has a high degree of freedom of shape expression which results in a high-performance design. On the other hand, it has also the drawback that unsuitable shapes for actually manufacturing are likely to be generated, e.g. checkerboards or grayscale. The purpose of this paper is to develop a method that enables topology optimization suitable for fabrication while taking advantage of the density method.

Design/methodology/approach

This study proposes a novel topology optimization method that combines convolutional neural network (CNN) as an effective smoothing filter with the density method and apply the method to the shield design with magnetic nonlinearity.

Findings

This study demonstrated some numerical examples verifying that the proposed method enables to efficiently obtain a smooth and easy-to-manufacture shield shape with high shielding ability. A network architecture suitable as smoothing filter was also exemplified.

Originality/value

In the field of magnetic field analysis, very few studies have verified the usefulness of smoothing by using CNN in the topology optimization of magnetic devices. This paper develops a novel topology optimization method that skillfully combines CNN with the nonlinear magnetic field analysis and also clarifies a suitable network architecture that makes it possible to obtain a target device shape that is easy to manufacture while minimizing the objective function value.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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