Asymptotic Expansion Applied to the Bie Method for Skin Effect Eddy Current Problems of Slender Parallel Conductors

2005 ◽  
Author(s):  
S.V. Yuferev ◽  
V.S. Yuferev
Keyword(s):  
Asymptotic Expansion ◽  
Eddy Current ◽  
Skin Effect

scholarly journals A Novel Approach on the Unipolar Axial Type Eddy Current Brake Model Considering the Skin Effect

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1561
Author(s):  
Hery Tri Waloyo ◽  
U Ubaidillah ◽  
Dominicus Danardono Dwi Prija Tjahjana ◽  
Muhammad Nizam ◽  
Muhammad Aziz
Keyword(s):  
Correction Factor ◽  
Eddy Current ◽  
High Speed ◽  
Skin Effect ◽  
Actual Condition ◽  
Average Error ◽  
Low Speed ◽  
Novel Approach ◽  
Calculation Results ◽  
Braking Torque

The braking torque mathematical modelling in electromagnetic eddy current brake (ECB) often ignores the skin effect that occurrs during operation. However this phenomenon can not be simply neglected. Therefore, this paper presents a mathematical model of braking torque for a unipolar axial type of ECB system with a non-magnetic disk, which considers the skin effects. The use of mathematical models that consider the existence of skin effects is significant in approaching the braking torque according to the actual condition. The utilization of generic calculations to the model of the ECB braking torque leads to invalid results. Hence, in this paper, the correction factor was added to improve the braking torque calculation as a comparator to the proposed equation. However, the modification and addition of the correction factor were only valid to estimate the low-speed regimes of torque, but very distant for the high-speed condition. From the comparison of calculated values using analytical and 3D modelling, the amount of braking torque at a low speed was found to have an average error for the equation using a correction factor of 1.78 Nm, while after repairing, a value of 1.16 Nm was obtained. For the overall speed, an average error of 14.63 Nm was achieved, while the proposed equation had a small difference of 1.79 Nm. The torque difference from the calculation results of the proposed model with the measurement value in the experiment was 4.9%. Therefore, it can be concluded that the proposed equation provided a better braking torque value approach for both low and high speeds.

Investigation of magnet segmentation techniques for eddy current losses reduction in permanent magnets electrical machines

2015 ◽  
Vol 34 (1) ◽  
pp. 46-60 ◽  
Author(s):  
Belli Zoubida ◽  
Mohamed Rachid Mekideche
Keyword(s):  
Genetic Algorithm ◽  
Finite Elements ◽  
Eddy Current ◽  
Permanent Magnets ◽  
Skin Effect ◽  
Electrical Machines ◽  
Design Parameters ◽  
Finite Elements Analysis ◽  
Eddy Current Losses ◽  
Content Type

Purpose – Reducing eddy current losses in magnets of electrical machines can be obtained by means of several techniques. The magnet segmentation is the most popular one. It imposes the least restrictions on machine performances. This paper investigates the effectiveness of the magnet circumferential segmentation technique to reduce these undesirable losses. The full and partial magnet segmentation are both studied for a frequency range from few Hz to a dozen of kHz. To increase the efficiency of these techniques to reduce losses for any working frequency, an optimization strategy based on coupling of finite elements analysis and genetic algorithm is applied. The purpose of this paper is to define the parameters of the total and partial segmentation that can ensure the best reduction of eddy current losses. Design/methodology/approach – First, a model to analyze eddy current losses is presented. Second, the effectiveness of full and partial magnet circumferential segmentation to reduce eddy loss is studied for a range of frequencies from few Hz to a dozen of kHz. To achieve these purposes a 2-D finite element model is developed under MATLAB environment. In a third step of the work, an optimization process is applied to adjust the segmentation design parameters for best reduction of eddy current losses in case of surface mounted permanent magnets synchronous machine. Findings – In case of the skin effect operating, both full and partial magnet segmentations can lead to eddy current losses increases. Such deviations of magnet segmentation techniques can be avoided by an appropriate choice of their design parameters. Originality/value – Few works are dedicated to investigate partial magnet segmentation for eddy current losses reduction. This paper studied the effectiveness and behaviour of partial segmentation for different frequency ranges. To avoid eventual anomalies related to the skin effect an optimization process based on the association of the finite elements analysis to genetic algorithm method is adopted.

A new eddy current probe with deep penetrating field trajectories for the inspection of deep cracks in metal materials

2020 ◽  
Vol 62 (7) ◽  
pp. 402-407
Author(s):  
Meixian Wu ◽  
Dongli Zhang ◽  
Chuanglong Wang
Keyword(s):  
Penetration Depth ◽  
Eddy Current ◽  
Performance Index ◽  
Eddy Currents ◽  
Skin Effect ◽  
Excitation Frequency ◽  
Metal Materials ◽  
Deep Crack

The detectability of deep cracks in metal materials is an important performance index of eddy current probes. However, because of the limitations of the skin effect of eddy currents, it is difficult to obtain deep crack information in materials using an ordinary probe. This paper proposes a new probe with deep penetrating field trajectories for the inspection of deep cracks. To optimise its performance, contributions of the coil radius, the pick-up position and the excitation frequency to penetration depth of eddy currents are studied. The results show that the capability of the new probe in the inspection of deep cracks is greatly improved when compared to traditional pancake probes.

Zum normalen Skin-Effekt unter Berücksichtigung der magnetischen Widerstandsänderung

1964 ◽  
Vol 19 (11) ◽  
pp. 1273-1276
Author(s):  
Rudolf Klein
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Eddy Current ◽  
Magnetic Field Dependence ◽  
Skin Effect ◽  
Normal Skin ◽  
Maximum Value ◽  
High Fields ◽  
The Magnetic Field ◽  
Normal Skin Effect

The penetration of a magnetic field into an infinite metallic half-space is altered due to the presence of the magnetoresistance of the medium. MAXWELL’S equations modified by the magnetic field dependence of the conductivity are solved for the case where the field at the surface is switched on immediately and is constant afterwards. It is shown that due to magnetoresistance the field runs into the medium quicker compared to the case of the pure normal skin effect. The induced eddy current has its maximum value no longer at the surface of the specimen. The results are discussed in connection with pulse methods for the measurement of magnetoresistance in high fields.

Comparing a one-dimensional skin effect equation with through transmission eddy current phenomena

1990 ◽  
Vol 23 (6) ◽  
pp. 359 ◽  
Author(s):  
S. Sullivan ◽  
D.L. Atherton ◽  
T.R. Schmidt
Keyword(s):  
Eddy Current ◽  
Skin Effect ◽  
One Dimensional

Performance Comparison between Surface-Mounted and Interior Brushless DC Motor

2013 ◽  
Vol 416-417 ◽  
pp. 133-138
Author(s):  
Nan Nan Zhao ◽  
Qian Yang ◽  
Ming Hui Zhang ◽  
Wei Guo Liu
Keyword(s):  
Permanent Magnet ◽  
Flux Density ◽  
Eddy Current ◽  
Skin Effect ◽  
Performance Comparison ◽  
Brushless Dc Motor ◽  
Eddy Current Losses ◽  
Cogging Torque ◽  
Brushless Dc ◽  
Copper Loss

In this paper, the cogging torque, airgap flux density, back-emf, and losses of a surface-mounted and a hybrid magnetization interior brushless machines with the same stator, airgap width, armature core length, material, permanent magnet consumption, speed and copper loss are compared. The analysis reveals that the loss in rotor back iron of interior motor is higher than that in surface-mounted motor due to the skin effect while the eddy current losses in sleeve and magnets of surface-mounted motor are significant, causing the total losses of surface-mounted motor are higher than that of interior motor.

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