AC losses of Roebel and CORC® cables at higher AC magnetic fields and Ramp Rates

2021 ◽  
Author(s):  
Mike D Sumption ◽  
John Murphy ◽  
Timothy J Haugan ◽  
Milan Majoros ◽  
Danko C van der Laan ◽  
...  
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Flux Creep ◽  
Ac Losses ◽  
Radial Magnetic Field ◽  
Eddy Current Losses ◽  
Preparation Conditions ◽  
Sinusoidal Waveform ◽  
Helical Geometry ◽  
The Individual

Abstract We have measured ReBCO coated conductor-based CORC® and Roebel cables at 77 K in a Spinning Magnet Calorimeter which subjected the tapes in the samples to a radial magnetic field of 566 mT (peak) at frequencies up to 120 Hz (272 T/s, cyclic average) with an approximately sinusoidal waveform. The samples were oriented such that the field applied to the tapes within the cables was entirely radial, simplifying subsequent analysis. An expression for loss which included hysteretic, flux creep, and eddy current losses was fit to both the CORC® and the Roebel cables. This expression allowed easy comparison of the relative influence of eddy currents and flux creep (or power-law behavior) effects. The loss of both the CORC® and Roebel cables measured here were seen to be essentially the sum of the hysteretic loss, flux creep effects, and the normal metal eddy current losses of the individual tapes. The losses of these cables were measured at high B*dB/dt with no coupling current loss observed under the present preparation conditions. The influence of flux creep effects on loss were not negligible. The losses of the CORC® cable per meter of tape were seen to be reduced from the case of a flat tape because of the helical geometry of the tapes.

Determination of eddy current losses and hysteresis losses in magnetic circuits of electrical machines

2020 ◽  
pp. 54-58
Author(s):  
S. M. Plotnikov
Keyword(s):  
Eddy Current ◽  
Magnetization Reversal ◽  
Eddy Currents ◽  
Technical Problem ◽  
Electrical Machines ◽  
Eddy Current Losses ◽  
Hysteresis Losses ◽  
Magnetic Circuits ◽  
Core Losses ◽  
Reversal Frequency

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.

Eddy currents in thin circular cylinders of uniform conductivity, due to periodically changing magnetic fields, in two dimensions

1927 ◽  
Vol 23 (8) ◽  
pp. 901-906 ◽  
Author(s):  
F. W. Carter
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Two Dimensions ◽  
Circular Cylinders ◽  
Two Dimensional ◽  
Total Field ◽  
Current Field ◽  
Conducting Material ◽  
Eddy Current Losses ◽  
Three Phase

The paper deals with the eddy currents in thin circular cylinders of uniform conducting material, due to periodic currents in conductors lying parallel to the axis of the cylinder, or to the rotation of the cylinder in a two-dimensional field of force. The first of these problems was discussed by Mr M. B. Field in a paper entitled “Eddy current losses in three-phase cable sheaths,” read before the British Association at their Cambridge meeting in 1904. The solution proposed, however, although probably sufficient for the object, is mathematically defective, in that the field due to the current carried by the cable is assumed as the total field, the effect of the eddy-current field on the eddy currents themselves being left out of account.

scholarly journals Increasing the required slip range of wound induction generator in wind power systems

2020 ◽  
Vol 9 (2) ◽  
pp. 436-442
Author(s):  
Ali Dalabeeh ◽  
Al-Mofleh Anwar ◽  
Tariq M. Younes ◽  
Ayman Al-Rawashdeh ◽  
Ayman Hindi
Keyword(s):  
Power Systems ◽  
Wind Turbine ◽  
Eddy Current ◽  
Power Flow ◽  
Eddy Currents ◽  
Reactive Power ◽  
Induction Generator ◽  
Material Loss ◽  
Eddy Current Losses ◽  
Wound Induction

Eddy currents losses in the rotor in high power generators do not allow operators, under high values of slip, to regulate voltage and control of reactive power flow. The paper presents a method that can accurately estimate the eddy current losses in electric machines with a less complicated procedure. The suggested method allows researchers to analyze and reduce the losses, and consequently, to improve the wind turbine induction generators efficiencies. The given approach, based on the conventional electric machine theory and the parameters supplied by the manufacturers, predicts the eddy current losses theoretically without the need of the measured material loss data or BH curve. Increasing the range of slip variation of induction motor can be achieved by using a rotor of two layers in the radial direction with different parameters. The first layer is a laminated layer of height (h), and the second is a solid (the rotor yoke). The computation of eddy current losses is useful to change the design of the machine to minimize the losses. This paper presents a detailed modeling of the effect parameters on the eddy current losses in wind turbine induction generator.

Calculation of eddy current losses using the electrodynamic similarity laws

2014 ◽  
Vol 63 (1) ◽  
pp. 107-114
Author(s):  
Dariusz Koteras
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Numerical Calculations ◽  
Eddy Current Losses ◽  
Similarity Laws ◽  
Good Agreement ◽  
Element Method

Abstract The results of the eddy currents losses calculations with using electrodynamics scaling were presented in this paper. Scaling rules were used for obtain the values of the eddy currents losses. For the calculations Finite Element Method was used. Numerical calculations were verified by measurements and a good agreement was obtained

scholarly journals Permanent-Magnet Eddy-Current Losses: A Global Revision of Calculation and Analysis

2019 ◽  
Vol 24 (3) ◽  
pp. 67 ◽  
Author(s):  
Daoud Ouamara ◽  
Frédéric Dubas
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
Eddy Currents ◽  
Research Field ◽  
Electrical Machines ◽  
Important Research ◽  
Calculation Methods ◽  
Current Analysis ◽  
Eddy Current Losses ◽  
Reduction Techniques

Eddy-current analysis is an important research field. This phenomenon occurs in multiple areas and has several applications: electromagnetic braking, repulsive effects, levitation, etc. Thereby, this paper is limited to eddy-current study in rotating electrical machines. In the design process, if the permanent-magnet (PM) loss calculation is very important, the overheating due to eddy-currents must be taken into account. The content of this paper includes sources, calculation methods, reduction techniques, and thermal analysis of PM eddy-current losses. This review aims to act as a guide for the reader to learn about the different aspects and points to consider in studying the eddy-current.

scholarly journals Finite Element Solutions for Magnetic Field Problems in Terfenol-D Transducers

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2808
Author(s):  
Duo Teng ◽  
Yatian Li
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Eddy Current ◽  
Permanent Magnets ◽  
Eddy Currents ◽  
Iron Alloy ◽  
Current Response ◽  
Bias Magnetic Field ◽  
Field Range ◽  
Eddy Current Losses

An appropriate magnetic design helps ensure that the Terfenol-D (Terbium- Dysprosium-Iron alloy) rods in giant magnetostrictive transducers have the perfect magnetostriction ability. To determine the optimum Terfenol-D rod state, a segmented stack configuration comprised by the Terfenol-D rods and NdFeB (neodymium-iron-boron) permanent magnets is presented. The bias magnetic field distributions simulated through the finite element method indicate that the segmented stack configuration is one effective way to produce the desired bias magnetic field. Particularly for long stacks, establishing a majority of domain to satisfy the desired bias magnetic field range is feasible. On the other hand, the eddy current losses of Terfenol-D rods are also the crucial to their magnetostriction ability. To reduce eddy current losses, the configuration with digital slots in the Terfenol-D rods is presented. The induced eddy currents and the losses are estimated. The simulations reveal that the digital slots configuration decreases the eddy current losses by 78.5% compared to the same size Terfenol-D rod with only a hole. A Terfenol-D transducer prototype has been manufactured using a Terfenol-D rod with a mechanical prestress of about 10 MPa and a bias magnetic field of about 42 kA/m. Its maximum transmitting current response of 185.4 dB at 3.75 kHz indicates its practicability for application as an underwater projector.

Modeling of eddy current losses in the iron core of electrical machines by a finite element homogenization method

2018 ◽  
Vol 12 (133) ◽  
pp. 24
Author(s):  
Vương Đặng Quốc
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Source Region ◽  
Homogenization Method ◽  
Magnetic Flux Density ◽  
Iron Core ◽  
Eddy Current Losses ◽  
Density Distributions ◽  
High Frequency Effects

A finite element homogenization method is proposed for the magetodynamic h-conform finite element forumulation to compute eddy current losses in electrical steel laminations. The lamination stack is served as a source region carrying predefined current density and magnetic flux density distributions presenting the eddy current losses and skin effects in each lamination. In order to solve this problem, the stacked laminations are converted into continuums with which terms are associated for considering the eddy current loops produced by both parallel and perpendicular fluxes. An accurate model of accuracy is developed via an accurate analytical expression of the eddy currents and makes the method adapted to both low and high frequency effects to capture skin depths of fields along thicknesses of the laminations.

A new analytical approach to determine slotting based eddy current losses in permanent magnets of PMSM taking into account axial and circumferential segmentation

2015 ◽  
Vol 34 (2) ◽  
pp. 398-412 ◽  
Author(s):  
Cornelius Bode ◽  
Wolf-Rüdiger Canders ◽  
Markus Henke
Keyword(s):  
Eddy Current ◽  
Analytical Approach ◽  
Permanent Magnets ◽  
Eddy Currents ◽  
3D Fem ◽  
Eddy Current Losses ◽  
Content Type ◽  
High Frequencies ◽  
Reaction Field ◽  
3D Fea

Purpose – The purpose of this paper is to calculate slotting-based eddy currents in permanent magnet excited synchronous machine (PMSM) taking into account axial and circumferential segmentation of magnets. Design/methodology/approach – An analytical approach to calculate eddy current losses in PM caused by slotting harmonics of PMSM is presented. The eddy current reaction field is taken into account as well as axial and circumferential segmentation of the magnets. Findings – The analytical model provides results comparable to 3D-FEM calculations even at high frequencies at reduced computation costs. To generalize the results the magnetic Reynold’s number is introduced. Originality/value – Taking into account the axial and circumferential segmentation in the PDE; the approach is much more accurate compared to known approaches; accuracy is comparable to 3D-FEA.

Analysis and Experiment of the Eddy Current Losses for Canned Motor

2011 ◽  
Vol 383-390 ◽  
pp. 7521-7525
Author(s):  
Yue Jun An ◽  
Guo Ming Liu ◽  
Hong Liang Wen ◽  
Wen Qiang Zhao ◽  
Li Ping Xue ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electromagnetic Field ◽  
Eddy Current ◽  
Empirical Formula ◽  
Eddy Currents ◽  
Characteristic Parameters ◽  
Material Characteristic ◽  
Eddy Current Losses ◽  
Canned Motor

Induced eddy currents in can cause loss when the canned motor runs, the loss make the motor`s temperature rise, directly affect the canned motor pump and the entire transmission system security. Empirical formula estimates eddy current losses which has a big error, it is difficult to meet the engineering requirements. For the canned motor with Hastelloy-C alloy or Sus316L cans, analyzed electromagnetic field and calculated can loss using a finite element method of Ansoft. The paper developed four prototypes, and obtained the experimental value of can loss via simple no-load experiment by the loss separation method. The results are compared with simulation value show that the accuracy of FEM is higher accurately than empirical formula; Analysis shows that dimension of a model and can material characteristic parameters such as the resistivity influence on the calculated error of FEM, the paper proposes to correct the error in the case of considering can material characteristic parameters.

scholarly journals III. Eddy-current losses in cylindrical conductors, with special applications to the alternating current resistances of short coils

1922 ◽  
Vol 222 (594-604) ◽  
pp. 57-100 ◽  
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Alternating Current ◽  
Considerable Proportion ◽  
General Effect ◽  
Eddy Current Losses ◽  
Direct Current Resistance ◽  
Set Up ◽  
Cylindrical Conductors ◽  
Current Resistance

It is well-known that a considerable proportion of the effective resistance of inductive coils when used at radio frequencies is caused by the eddy-currents set up in the wires of the coils by the alternating magnetic field in which they are situated, and that in extreme cases the alternating current resistance may amount to more than one hundred times the direct current resistance. It is therefore important to have reliable formulæ for the eddy-current resistance of such coils in order to determine the conditions which will reduce the eddy-current losses to a minimum. The simplest case, that of a long straight cylindrical wire under the action of its own current, has been treated by Kelvin, Rayleigh, Heaviside, and others. The general effect is known as the “skin effect,” because the current tends to concentrate more and more upon the skin of the conductor as the frequency increases.

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