Numerical calculation of transients in electrical circuits containing elements with nonlinear eddy-current skin effect

1987 ◽  
Vol 134 (9) ◽  
pp. 741 ◽  
Author(s):  
S. Wiak ◽  
K. Zakrzewski
Keyword(s):  
Numerical Calculation ◽  
Eddy Current ◽  
Skin Effect ◽  
Electrical Circuits

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 Working of Eddy Current Transducers under Control of Ferromagnetic Pipes in Condition of Insufficient Magnetic Saturation

2013 ◽  
Vol 467 ◽  
pp. 528-530
Author(s):  
Kai Yu Hao ◽  
Vadim Miroshnikov
Keyword(s):  
Electromagnetic Field ◽  
Numerical Calculation ◽  
Eddy Current ◽  
Maxwell Equations ◽  
Control Sample ◽  
Magnetic Saturation ◽  
Method Of Calculation ◽  
Current Transducer ◽  
Object Of Control ◽  
Eddy Current Transducer

The numerical method of calculation of electromagnetic field in a control sample at a time of work of encircling eddy current transducer is offered. The method is based on a numerical solution of the two Maxwell equations, which connect a change of electrical and magnetic fields. It allows to make calculations taking into account the actual value of magnetic inductivity of metal and to get results in any form, convenient for further interpretations. For the calculation of the encircling eddy current transducer the equivalent circuit of defect as step junction is offered. The numerical calculation shows, that the greatest sensitivity of the transducer is achieved when the value of magnetic permeability of the object of control is approximately 10-30. Therefore, it is not necessary to lead the material of the object of control up to satiety, as it considered before.

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.

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