Comparison of Biot–Savart’s Law and 3D FEM in the Study of Electromagnetic Forces Acting on End Winding

Ki-Chan Kim 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.3

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot?Savart’s law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

Comparison of Biot-Savart's Law and 3D FEM in the Study of Electromagnetic Forces Acting on End Winding

Kim, Ki-Chan The Korean Institute of Electrical Engineers 2011 Journal of Electrical Engineering & Technology Vol.6 No.3

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

Comparison of Biot–Savart’s Law and 3D FEM in the Study of Electromagnetic Forces Acting on End Winding

김기찬 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.3

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore,designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot–Savart’s law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

Evaluation of AC Resistance in Litz Wire Planar Spiral Coils for Wireless Power Transfer

Xiaona Wang,Pan Sun,Qijun Deng,Wengbin Wang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

A relatively high operating frequency is required for efficient wireless power transfer (WPT). However, the alternating current (AC) resistance of coils increases sharply with operating frequency, which possibly degrades overall efficiency. Hence, the evaluation of coil AC resistance is critical in selecting operating frequency to achieve good efficiency. For a Litz wire coil, AC resistance is attributed to the magnetic field, which leads to the skin effect, the proximity effect, and the corresponding conductive resistance and inductive resistance in the coil. A numerical calculation method based on the Biot–Savart law is proposed to calculate magnetic field strength over strands in Litz wire planar spiral coils to evaluate their AC resistance. An optimized frequency can be found to achieve the maximum efficiency of a WPT system based on the predicted resistance. Sample coils are manufactured to verify the resistance analysis method. A prototype WPT system is set up to conduct the experiments. The experiments show that the proposed method can accurately predict the AC resistance of Litz wire planar spiral coils and the optimized operating frequency for maximum efficiency.

Evaluation of AC Resistance in Litz Wire Planar Spiral Coils for Wireless Power Transfer

Wang, Xiaona,Sun, Pan,Deng, Qijun,Wang, Wengbin The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

A relatively high operating frequency is required for efficient wireless power transfer (WPT). However, the alternating current (AC) resistance of coils increases sharply with operating frequency, which possibly degrades overall efficiency. Hence, the evaluation of coil AC resistance is critical in selecting operating frequency to achieve good efficiency. For a Litz wire coil, AC resistance is attributed to the magnetic field, which leads to the skin effect, the proximity effect, and the corresponding conductive resistance and inductive resistance in the coil. A numerical calculation method based on the Biot-Savart law is proposed to calculate magnetic field strength over strands in Litz wire planar spiral coils to evaluate their AC resistance. An optimized frequency can be found to achieve the maximum efficiency of a WPT system based on the predicted resistance. Sample coils are manufactured to verify the resistance analysis method. A prototype WPT system is set up to conduct the experiments. The experiments show that the proposed method can accurately predict the AC resistance of Litz wire planar spiral coils and the optimized operating frequency for maximum efficiency.

New Experimental Investigation of Magnetic and Electric Fields in the Vicinity of High-Voltage Power Lines

Said Ghnimi,Adnen Rajhi,Ali Gharsallah 한국자기학회 2016 Journal of Magnetics Vol.21 No.1

In this paper, the theoretical and experimental characteristics of magnetic and electric fields in the vicinity of high voltage lines are investigated. To realize these measurements and calculations, we have developed some equations for two overhead power line configurations of 150 ㎸ (single circuit, double circuit), based on Biotsavart law, image and Maxwell theories, in order to calculate the magnetic and electric fields. The measurements were done to a maximum distance from the tower of 50 m, at a height of 1m from the ground. These experiments take into consideration the real situations of the power lines and associated equipment. The experimental results obtained are near to that of the Biot-Savart theoretical results for a far distance from the tower; and for a distance close to the power line, the results from the image theory are in good agreement with the experimental results.

Fast Magnetic Field Simulation with Linear System Approach

Jaeho Lim,Chang-Beom Kim,Sunglok Choi,HyoBong Hong,JongWon Park 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

In this research, we propose a noble methodology for modeling and simulation of the intensity and direction of the magnetic fields generated by coils in a limited 3-dimensional region. This method was strictly based on the Biot-Savart’s law determining the magnetic fields induced by currents flowing through the coils. We also used Finite Element Method (FEM), a numerical technique for finding a solution for each subdivision of a whole domain within the regions of interest. Based on the introduction of rotational transform method for an arbitrary axis, this method possesses a strong analysis capability for the magnetic fields in the vicinity of the coil at an arbitrary position in 3-dimensional region. In addition, a linear calculation system adopted in the simulation process was able to carry on high-performance analysis for the magnetic fields generated by even multiple coils. We strongly propose that this noble method would be a powerful simulation tool for the design of a system that can generate magnetic fields within a 3-dim region of interest considering both the intensity and direction.

지중송전계통에서 선로의 구성방식에 따른 자계 해석

이재명(Jae-Myeong Lee),이종범(Jong-Beom Lee) 대한전기학회 2015 전기학회논문지 Vol.64 No.12

This paper describes magnetic field on power cable in underground transmission systems. Based on specification which is being used in domestic power utility, magnetic field was analyzed in accordance with line arrangement, line burial depth and phase spacing. Magnetic field magnitude and its trend were understood in each circuit type such as double circuits, triple circuits and quadruple circuits of underground transmission systems. In addition, magnetic field was analyzed according to phase arrangement changing in each circuit. Finally, the proper phase arrangement configuration type was suggested by the evaluation of analysis result. Magnetic field was calculated by using Biot-Savart"s law. According to the evaluated magnetic fields based on phase layout configuration in each circuit, it figured out that each of magnetic fields was different. As a result, this paper proposes a proper phase layout configuration for generating minimum magnetic field. It is evaluated that the phase layout configuration in each circuit proposed in this paper can be used at actual underground transmission systems.

Wireless power transfer system for angled concave conditions utilizing quasi-bowl-shaped couplers

Chen, Chen,Li, Jiangui,Wang, Longyang,Nie, Hui,Li, Qiang The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.7

Wireless power transfer (WPT) is favored by consumers due to its convenience, safety, and flexible layout. Circular and rectangular coils are the most common coil structures in WPT systems. However, they are not suitable for installation conditions with angled groove areas such as railways, conveyors, and so on. To fully utilize installation space and to improve transfer efficiency, this paper has proposed a quasi-bowl-shaped (QBS) magnetic coupler, which can suitably fit on angled grooves. First, a QBS coupler model was presented. Second, formulas of its spatial magnetic field density were derived. Third, the influences of the bending distance and bending angle on the coupler coefficient were analyzed. Fourth, five magnetic core types were presented and analyzed for coupler optimization. Finally, QBS WPT performances were tested on a newly built experiment platform. Experimental results show that the QBS coupler can realize a constant transfer efficiency of 92.36% at an axial distance of 6 cm, and it can realize a constant transfer efficiency of 84.17% at an axial distance of 10 cm.

Topological Configuration Design without Direct Solving Differential Equations

Min Tae Kim(김민태),Woochul Kim(김우철),Yoon Young Kim(김윤영) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

A new method for topological configuration design in electromagnetic systems without directly solving differential equation is proposed. Topology optimization is usually formulated using the finite element method, but the novel feature of this method is that no such partial differential equation solver is employed during the whole optimization process. To avoid solving the governing Maxwell equation numerically for analysis of electromagnetic systems, the concept of equivalent magnetizing current based on an equivalent source model is employed. As a specific application, we consider the design of two-dimensional fine-pattern coils of an optical pickup actuator that can maximize the Lorentz force. The proposed design method can be also applied to the design of electric coils and permanent magnet.