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Article
Publication date: 20 January 2020

Suqi Liu and Yuping Liu

The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power…

Abstract

Purpose

The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power transfer projects. However, it remains a challenge to obtain the constant output power and transfer efficiency in a fixed-frequency mode during variations in transfer distance and orientation of the coils. In this paper, using two series transmitting coils to achieve the constant output power and transfer efficiency is used.

Design/methodology/approach

First, the circuit model is established and transfer characteristics are studied. Second, using the two series transmitting coils to achieve the constant output power and transfer efficiency is investigated. Finally, the experimental system is designed; it can optimize the transfer performances by itself; the constant output power and transfer efficiency are achieved in the fixed-frequency mode.

Findings

When the receiving coil moves between the two series transmitting coils, the tolerance of the output power and transfer efficiency is less than 5 per cent.

Research limitations/implications

When a receiving coil is placed between the two series transmitting coils, there are space limits. The receiving coil only shifts between the two transmitting coils.

Practical implications

However, the rail guide vehicle may achieve constant output power and transfer efficiency when it moves on the rail guide. So, this topology may provide a practical solution.

Originality/value

In this research, the three-coil MCR-WPT system including two series transmitting coils is presented. In a fixed-frequency mode, the constant output power and transfer efficiency is achieved in experiments during variations in transfer distance and orientation of the coils. The fluctuation of the output power and transfer efficiency is less than 5 per cent.

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Article
Publication date: 10 May 2019

Shogo Fujita and Hajime Igarashi

The tensor complex permeability of a multi-turn coil with elliptic cross-section is analytically expressed. In field analysis, a multi-turn coil can be modeled by the…

Abstract

Purpose

The tensor complex permeability of a multi-turn coil with elliptic cross-section is analytically expressed. In field analysis, a multi-turn coil can be modeled by the uniform material that has the present tensor complex permeability. It is shown that the frequency characteristic of the present tensor complex permeability is in good agreement with that evaluated by finite element method applied to a unit cell of the multi-turn coil region.

Design/methodology/approach

The authors introduce a new method to evaluate the complex permeability of a multi-turn rectangular coil. To obtain the complex permeability of a rectangular coil in a closed form, it is approximated as an elliptic coil. Because the rectangular coil has different complex permeabilities in the vertical and horizontal directions, the complex permeability have to be defined in a tensor form. It suffices to discretize the coil region into rather coarse finite elements without considering the skin depth in contrast to the conventional finite element method.

Findings

The proposed method is shown to give the impedance of multi-turn coils which is in good agreement with results obtained by the conventional finite element (FE) analysis. By extending the proposed approach, the authors can easily perform 3D FE analysis without difficulty in discretization of the coil region with fairly fine finite elements. Moreover, they found that the approximation of rectangular coils as the elliptic coils is valid for analysis of quasi-static fields using this homogenization method.

Originality/value

The novelty of this study is in the approximation of the rectangular coils with elliptic coils, and the complex permeability for them is formulated here in a closed form. The proposed formula includes that for the round coils. Using the present method, the authors analyze the rectangular coils without fine discretization.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 6 July 2015

Mihaela Cretu and Dan Doru Micu

– The purpose of this paper is to evaluate the response of the spinal cord, the transmembrane potential, during lumbar magnetic stimulation, using a figure of eight coil.

Abstract

Purpose

The purpose of this paper is to evaluate the response of the spinal cord, the transmembrane potential, during lumbar magnetic stimulation, using a figure of eight coil.

Design/methodology/approach

In order to obtain a precise stimulation of the spinal cord and not the nearby nervous fibres, the coil from the electric circuit of the magnetic stimulator is optimized. The new proposed design is based on the turns’ placement inside the coil, the number of turns required to produce activation. Once the coil configuration is established, the paper addresses other issues that need to be solved: reducing power consumption (the low efficiency of power transfer from the coil to the tissue is a major drawback) and reducing coil heating.

Findings

The traditional commercial coils, used for magnetic stimulation in some preliminary experiments, had proved their inability to specifically stimulate the target tissue, without activating the surrounding areas and the low efficiency of power transfer from the coil to the nervous tissue. A more realistic modelling of the stimulating coil, based on the distribution of turns inside the coil can lead to directly stimulation of the spinal cord, during lumbar magnetic stimulation.

Practical implications

If the electrical circuit of the magnetic stimulator is improved, the direct stimulation of the spinal cord is obtained; so, this technique could facilitate functional motor activities, including standing and stepping in paralyzed people, without requiring implantation of electrodes like in electrical stimulation.

Originality/value

The authors underlined that the spinal cord stimulation can be achieved by magnetic stimulation, only if the parameters of the stimulator circuit are optimized. Therefore an original and realistic modelling of the inductive coil was proposed based on number and turns’ distribution within the coil. The coil is designed so that reducing the excessive heating makes it difficult in obtaining a more frequent repetition of stimulus.

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

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Article
Publication date: 1 December 1976

AMERICUS

Industry growth in the field of coil coatings has been impressive as several of the articles abstracted below attest. The advantages inherent in coil coatings from the…

Abstract

Industry growth in the field of coil coatings has been impressive as several of the articles abstracted below attest. The advantages inherent in coil coatings from the points of view of economy, adaptability to automation, and adaptability of the final product to fabrication are impressive ones that industry is taking full advantage of. There are, to be sure, some problems associated with the use of precoated steel, such as destruction of the coating during weldability, but techniques have been devised, including mechanical fastening, to circumvent such problems.

Details

Pigment & Resin Technology, vol. 5 no. 12
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 27 November 2019

Suqi Liu and Jianping Tan

This paper aims to find an approach that achieves constant output power and transfer efficiency in an open space, such as charging pads.

Abstract

Purpose

This paper aims to find an approach that achieves constant output power and transfer efficiency in an open space, such as charging pads.

Design/methodology/approach

In this study, a topology of the five-coil system including two transmitting coils is presented. Also, in a fixed-frequency mode and an open space, this study focuses on the two transmitting coils to achieve the uniform magnetic field and ultimately, attain the constant output power and transfer efficiency.

Findings

In a fixed-frequency mode and an open space, the constant output power and transfer efficiency is then achieved in experiments by inserting the relay loop into the uniform magnetic field.

Practical implications

An approach that achieves constant output power and transfer efficiency in an open space. The topology of the five-coil magnetically coupled resonant-wireless power transfer (MCR-WPT) system shows prospective value for various applications, which could be used at designing of wireless battery charger dedicated for cars or mobile phones.

Originality/value

By comparing the simulation and experimental results, the topology can be optimized in the transmission performance by itself. By doing so, the constant output power and transfer ef?ciency are achieved in the constant frequency mode.

Details

Circuit World, vol. 46 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 13 July 2010

Sanjay Jayaram

Recent advances in nano and picosatellite missions and future such missions require three axis attitude control system hardware for attitude control purposes. A simple…

Abstract

Purpose

Recent advances in nano and picosatellite missions and future such missions require three axis attitude control system hardware for attitude control purposes. A simple, cost effective, yet an efficient devise that is used for active attitude control is magnetic torquer coil. The purpose of this paper is to describe the design and fabrication of a template to manufacture magnetic torquer coils of varying sizes and shapes.

Design/methodology/approach

Details about the development of the template design, analysis, and fabrication are discussed. The development status of the system is outlined and the working prototype of the device is described and some preliminary test results are given.

Findings

A fully functional prototype of the template has been developed and testing has been conducted that demonstrated the effectiveness of the device. Magnetic torquer coils of varying sizes were fabricated and tested. A finite element analysis was performed by modeling the characteristics of the fabricated coils to determine thermally induced stresses and deformations during its space operations.

Practical implications

The paper illustrates and demonstrates an effective application of torquer coil template in the satellite fabrication industry. The benefits from the approach are generally applicable to any future university and industry missions using picosatellite technology.

Originality/value

The designed template satisfied all the constraints and requirements. Furthermore, its advantages include scalability, modularity, and its capability to fabricate magnetic torquer coils of varying sizes and shapes.

Details

Journal of Engineering, Design and Technology, vol. 8 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

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Article
Publication date: 4 July 2016

Hua Li and Wolfgang Rucker

The purpose of this paper is to present an accurate and efficient hybrid method for the calculation of the inductance of a coil and its inductance change due to deformed…

Abstract

Purpose

The purpose of this paper is to present an accurate and efficient hybrid method for the calculation of the inductance of a coil and its inductance change due to deformed turns using numerical methods.

Design/methodology/approach

The paper opted for finite element method coupled with analytical method (FCA) to accurately calculate the inductance of a coil, which is used as reference value. An algorithm with a power function is presented to approximate the partial inductance matrix with the purpose of obtaining the percentage change of the inductance due to deformed turns by using the partial element equivalent circuit (PEEC) with an approximated model and an optimization process. The presented method is successfully validated by the numerical results.

Findings

The paper provides a systematic investigation of the inductance of an arbitrary shaped coil and shows how to accurately and efficiently evaluate the inductance change of a coil due to its deformed turns. It suggests that the inductance of a coil can be accurately calculated by using FCA and its percentage change due to deformed turns can be efficiently calculated by using the PEEC_Approximation.

Research limitations/implications

As this research is for the magnetostatics, the skin- and proximity-effects have not been taken into account.

Practical implications

The paper includes implication for the worst-case analysis of the coil’s inductance due to mechanical damage or manufacturing tolerance.

Originality/value

This paper fulfills an identified need to study how the inductance change of a coil can be obtained accurately and efficiently.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 24 October 2021

Siquan Zhang

In eddy current nondestructive testing, a probe with a ferrite core such as an E-core coil is usually used to detect and locate defects such as cracks and corrosion in…

Abstract

Purpose

In eddy current nondestructive testing, a probe with a ferrite core such as an E-core coil is usually used to detect and locate defects such as cracks and corrosion in conductive material. However, the E-core coil has some disadvantages, such as large volume and difficulty in the process of winding the coils. This paper aims to present a novel T-core probe and its analytical model used for evaluating hidden holes in a multi- layer conductor.

Design/methodology/approach

By using a cylindrical coordinate system, the solution domain is truncated in the radial direction. The magnetic vector potential of each region excited by a filamentary coil is derived, and the expansion coefficients of the solutions are obtained by matching the boundary and interface conditions between the regions. By using the truncated region eigenfunction expansion method, the final expression in closed form for the impedance of the multi-turn coil is worked out, and the impedance calculation is performed in Mathematica. For frequencies ranging from 100 Hz to 100 kHz, both the impedance changes of the T-core coil above the multi-layer conductor without a hidden hole and in the absence of the layered conductor were calculated, and the influence of a hidden hole in the multi-layer conducting structure on the impedance change was investigated.

Findings

The correctness of the analytical model of the T-core coil was verified by the finite element method and experiments. The proposed T-core coil has higher sensitivity than an air-core coil, and similar sensitivity and smaller size than an E-core coil.

Originality/value

A new T-core coil probe and its accurate theoretical model for defect evaluation of conductor were presented; probe and analytical model can be used in probe design, detection process simulation or can be directly used in defect evaluation of multi-layer conductor.

Details

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

Keywords

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Article
Publication date: 30 July 2021

Adesuwa Annabelle Ebuehi, Gift Okeoghene Eric and Benjamin Akinloye

The difficulty in winding coil-based electrical and electronic devices manually lies in the fact that it takes so much time and effort to perform. Furthermore, it is…

Abstract

Purpose

The difficulty in winding coil-based electrical and electronic devices manually lies in the fact that it takes so much time and effort to perform. Furthermore, it is difficult to achieve accuracy manually, as it is possible to lose count of the number of turns being wound. The purpose of this paper is to detail the design methods and calculations used to achieve a cost-effective, significantly accurate and more efficient method of winding coils.

Design/methodology/approach

A program flowchart was designed as a guideline for writing the program. An AT89C52 microcontroller was used to control the movement of the two direct current (DC) motors used in the construction of the machine. The circuit design obtained was then simulated using Proteus to test the functionality of the components together.

Findings

An electromechanical automatic coil winding machine for the coiling of simple, small-sized, coil-based electrical devices was successfully designed and fabricated. The machine was tested by winding a 1 kVA transformer. Diagrams, calculations, results and observations obtained during the design and construction are detailed in this paper.

Originality/value

This machine solves the problem of tediousness in coil winding, stably and precisely winding 60 turns/min at a 24 V supply and providing a keypad input method. Although portable automatic coil winding machines have been rendered previously, most have applied the use of stepper motors. The application of brushed DC motors alongside an AT89C52 microcontroller is a variation to the pool of renditions, offering better controllability and a sustained output.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

Keywords

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Article
Publication date: 9 December 2020

Xinning Tang, Yong Dai, Yunhui Ma and Bingyin Ren

This study aims to solve the problem of the existing metal foreign object (MFO) detecting systems, which are not sensitive to the small size MFO in wireless charging…

Abstract

Purpose

This study aims to solve the problem of the existing metal foreign object (MFO) detecting systems, which are not sensitive to the small size MFO in wireless charging region of electric vehicle (EV) because of the extremely complex signal noise in the process of wireless charging of EV.

Design/methodology/approach

A method for MFO detection based on the principle that MFOs can cause mistuned resonance of detection coil resonant circuit is proposed. The general scheme of detecting system is proposed. The design method for detection coils which is effective to small MFOs detection in large-area region of wireless charging of EV is presented. The design of time-sharing driving circuit and amplifying circuit of high frequency exciting signal for detection coils is introduced. The design scheme of signal processing circuit (including filter and rectifier) of detection coil terminal voltage is also proposed.

Findings

The influence of exciting frequency of detection coils on detecting sensitivity and the anti-noise feature of system are analyzed according to the experiment results.

Originality/value

The experiment of MFO detection indicates that the proposed method can effectively detect the coin-sized small MFO in the process of wireless charging of EV.

Details

Sensor Review, vol. 41 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

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