Calculation of Eddy Current Losses in Iron Core of Transformer

The direct coil cooling method is one of the existing cooling techniques for electric machines with concentrated windings, in which cooling tubes of conductive material are inserted between the windings. In such cases, eddy current losses are induced in those cooling tubes because of the time variant magnetic field. To compute the cooling tubes losses, either a transient finite element simulation (mostly based on commercial software), or a full analytical method, which is more complex to be constructed, is required. Instead, this paper proposes a simple and an accurate combined semi-analytical-finite element method to calculate the losses of electric machines having cooling tubes. The 2D magnetostatic solution of the magnetic field is obtained e.g., using the free package “FEMM”. Then, the eddy current losses in the tubes are computed using simple analytical equations. In addition, the iron core losses could be obtained. In order to validate the proposed method, two cases are investigated. In Case 1, a six-toothed stator of a switched reluctance machine (SRM), without rotor, is employed in which six cooling tubes are used while in Case 2 a complete rotating SRM is studied. The proposed method is validated by a 2D transient simulation in the commercial software “ANSYS Maxwell” and also by experimental measurements. Evidently, the proposed method is simple and fast to be constructed and it is almost free of cost.

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

Journal of Science and Technology Issue on Information and Communications Technology ◽

10.31130/b2018-110 ◽

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.

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

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-11-54-58 ◽

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.

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Numerical analysis of eddy current losses in infinitely long, thin non-magnetic conductive plates.

IEEJ Transactions on Power and Energy ◽

10.1541/ieejpes1972.109.339 ◽

1989 ◽

Vol 109 (8) ◽

pp. 339-346

Author(s):

Takao Takahashi

Keyword(s):

Numerical Analysis ◽

Eddy Current ◽

Eddy Current Losses

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Losses in ac of BSCCO-2223 superconducting monofilament and multifilament tapes at power frequencies

Journal of Materials Research ◽

10.1557/jmr.1997.0401 ◽

1997 ◽

Vol 12 (11) ◽

pp. 3085-3089

Author(s):

S. Mench ◽

M. Lelovic ◽

T. Deis ◽

N. G. Eror ◽

U. Balachandran ◽

...

Keyword(s):

Eddy Current ◽

Anisotropy Field ◽

Magnetic Losses ◽

Field Orientation ◽

Eddy Current Losses ◽

Order Of Magnitude

The ac magnetic losses at power frequencies (60 Hz) were investigated for mono- and multifilament Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3Oy (BSCCO-2223) tapes with similar Ic values at 77 K. The multifilament sample exhibited higher losses than the monofilament under the same conditions. Loss peaks are discussed in terms of intergranular, intragranular, and eddy current losses. Because of BSCCO's anisotropy, field orientation has a large effect on the magnitude of these peaks, even at relatively small angles. Losses for fields applied parallel to the c-axis of the textured BSCCO grains are larger by over an order of magnitude than those applied perpendicular.

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