scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Effects of eddy currents in transformer windings

01 Aug 1966-Vol. 113, Iss: 8, pp 1387-1394
TL;DR: In this article, the effect of eddy currents on transformer windings is considered and a method is derived for calculating the variation of winding resistance and leakage inductance with frequency for transformers with single-layer, multilayer and sectionalised windings.
Abstract: The effects of eddy currents in transformer windings are considered, and a method is derived for calculating the variation of winding resistance and leakage inductance with frequency for transformers with single-layer, multilayer and sectionalised windings. The method consists in dividing the winding into portions, calculating the d.c. resistances and d.c. leakage inductances of each of these portions, and then multiplying the d.c. values by appropriate factors to obtain the corresponding a.c. values. These a.c. values are then referred to, say, the primary winding and summed to give the total winding resistance and leakage inductance of the transformer. Formulas are derived and quoted for calculating the d.c. resistances and leakage inductances of the winding portions. Theoretical expressions are derived for the variation with frequency etc. of the factors by which the d.c. values must be multiplied to obtain the corresponding a.c. values. These expressions are presented in the form of graphs, permitting the factors to be read as required.
Citations
More filters
Proceedings ArticleDOI
01 Nov 2019
TL;DR: In this article, the authors proposed a further arrangement of PCB windings to minimize the PCB wire losses, where the magnetic circuit is analogous to electrical circuit, and the magnetic core structure shape the footprint of the PCB winding.
Abstract: High frequency PCB windings magnetic is one of the key components in high power density and high efficiency MHz power converter. High frequency PCB windings magnetic losses are the main limitation for the whole converter efficiency and power density, while the PCB windings losses are the main part of the magnetic losses. Currently, the Dowell’s model is used for the layout of PCB windings. However, the Dowell’s model has its restrictions, namely, magnetic field is assumed to be distributed evenly in one direction. But the magnetic field around the windings are three-dimensional and unevenly. Therefore, further arrangement of PCB windings is proposed to minimize the PCB windings losses. Besides, the magnetic circuit is analogous to electrical circuit, and the magnetic core structure shape the footprint of the PCB winding, so different magnetic core structure can be proposed for the trade-off design among the high power density, high efficiency, and low temperature stress. Therefore, both PCB winding layout and magnetic core structure design are important for the optimization of high frequency magnetic components.

4 citations

Journal ArticleDOI
01 Nov 1998
TL;DR: In this paper, a small prototype inductively-coupled fault current limiter (FCL) is described, which has an unusual toroidal geometry in which primary and secondary coils are interleaved to minimize leakage fields and leakage inductance and maximise the effective utilisation of superconducting material.
Abstract: The characteristics and performance of a small prototype inductively-coupled fault current limiter (FCL) are described. The FCL in question has an unusual toroidal geometry in which primary and secondary coils are interleaved to minimise leakage fields and leakage inductance and maximise the effective utilisation of superconducting material. The paper investigates the effect of winding configurations and geometry on the electromagnetic properties of the FCL. The construction of the prototype uses superconducting secondary coils made from double-sided YBCO thick film layers on ring shaped zirconia substrates. The primary windings were made of planar coils of copper wire. An interleaved winding structure produces a leakage inductance that is less than one-tenth of that obtained with an equivalent 'E' core transformer. Computed and measured leakage impedance are shown to be in good agreement. Transient and current limiting measurements demonstrate that the proposed FCL displays typical characteristics. The advantages of interleaved winding configurations are demonstrated directly by varying the degree of interleaving of the windings on the prototype FCL.

4 citations

08 Jul 2014
TL;DR: In this paper, a philosophie mixant analyses physiques, formulations empiriques issues de bases de donnees and caracterisations experimentales is proposed to constrain les modeles des principaux acteurs des etages de puissance that sont les composants actifs and passifs, associes selon les cas a des vecteurs de refroidissements.
Abstract: Le choix d'une architecture de convertisseur puis la conception d'un prototype demonstrateur, pour repondre a une specification donnee, reste un exercice difficile dans une jungle topologique et technologique. Le developpement d'outils d'aide a la conception est donc un passage oblige pour faciliter la tâche des concepteurs mais aussi pour optimiser veritablement les solutions. La puissance sans cesse croissante des plates-formes logicielles et des ordinateurs personnels offre un potentiel largement suffisant pour atteindre des objectifs ambitieux dans cette assistance a la conception. Cela dit, de nombreux problemes restent a resoudre et parmi eux, la synthese de modeles realistes et utilisables dans l'optimisation d'un systeme complet n'est pas le moindre. Cette contribution propose une philosophie mixant analyses physiques, formulations empiriques issues de bases de donnees et caracterisations experimentales pour construire les modeles des principaux acteurs des etages de puissance que sont les composants actifs et passifs, associes selon les cas a des vecteurs de refroidissements.

4 citations

Proceedings ArticleDOI
11 Oct 2020
TL;DR: An isolated Triple Active Bridge converter for Solar Photovoltaic (PV) and battery (ES) integration is discussed in this paper and several case scenarios are simulated to demonstrate advantages of the proposed approach in enabling high RES penetration.
Abstract: Integrating Energy Storage (ES) with intermittent Renewable Energy Sources (RES) is critical for wide-spread adoption of RES. Such systems offer several system-level advantages such as participation in demand response programs, demand charge reduction, arbitrage to maximize time-of-use rates, and increase resilience. For efficient and cost-effective integration of ES with RES, a Multi-Port Converter (MPC) is highly desirable. An isolated Triple Active Bridge (TAB) converter for Solar Photovoltaic (PV) and battery (ES) integration is discussed in this paper. Multi-objective optimization of this topology, for interfacing 10 kVA PV-ES system with 240 V AC grid, is conducted with the objectives to reduce losses and overall volume of the MPC. Finite Element Analysis (FEA) is performed to validate the outcome of the analytical modeling based optimization procedure. A control scheme to manage power flow between AC grid, PV, and ES is designed, and several case scenarios are simulated to demonstrate advantages of the proposed approach in enabling high RES penetration.

4 citations

Dissertation
18 Jul 2012
TL;DR: In this paper, a methode numerique permettant des calculs rapides is proposed for a filtre CEM, in order to solve different aspects magnetiques du problems.
Abstract: La tendance de l'integration en electronique de puissance accentue naturellement les effets electromagnetiques parasites. Tout systeme d'energie electrique devient alors source de perturbations EM aussi bien conduites que rayonnees. Mais dans le cadre de ces travaux, nous nous sommes focalise sur l'organe de filtrage des perturbations conduites : le filtre CEM. En haute frequence, il s'avere que ce type de systeme voit son comportement degrade en raison des differents phenomenes parasites apparaissant au sein meme du dispositif. Seuls les aspects magnetiques du probleme ont neanmoins ete traites (i.e. inductances partielles & couplages magnetiques parasites). Differentes methodes ont ete mises au point par le passe dans le but d'ameliorer facilement la reponse du filtre. Cependant, il s'agit de procedes empiriques ne pouvant garantir l'optimalite de la solution de filtre construite. Les travaux realises au cours de cette these ont donc consiste a developper une nouvelle methode d'optimisation d'un filtre CEM, et plus precisement de son routage. L'objectif est alors d'exploiter les differents phenomenes magnetiques parasites intrinseques au montage. Calculer ce type d'elements a donc necessite l'utilisation d'un outil de modelisation PEEC ; methode numerique permettant des calculs rapides en raison d'un maillage relativement limite.

3 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, a multilayer winding carrying an alternating current, such as the windings illustrated in figures 1, 2, and 3, each layer of copper lies in the alternating magnetic field set up by the current in all the other layers.
Abstract: IN any multilayer winding carrying an alternating current, such as the windings illustrated in figures 1, 2, and 3, each layer of copper lies in the alternating magnetic field set up by the current in all the other layers. Eddy currents are set up in each layer in a direction to partly neutralize the magnetic intensities in the interior of the copper wire in each layer. As a result of the eddy-current losses in the copper, the effective resistance of the winding to the alternating current it carries may be many times its resistance to continuous currents.

103 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the more important causes of eddy currents in heavy conductors carrying alternating currents and surrounded on three sides by iron, and propose a method to identify the most important causes.
Abstract: The object of the present paper is the discussion of the more important causes of eddy currents in heavy conductors carrying alternating currents and surrounded on three sides by iron.

93 citations

Journal ArticleDOI
TL;DR: In this article, it is shown 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.
Abstract: 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 formulae 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.

49 citations

Journal ArticleDOI
TL;DR: In this article, the authors show how hyperbolic functions of complex angles may be applied to the solution of the problem of heat losses in rectangular conductors that are embedded in open slots.
Abstract: The principal object of this paper is to show how hyperbolic functions of complex angles may be applied to the solution of the problem of heat losses in rectangular conductors that are embedded in open slots. A certain knowledge of the functions themselves is presupposed. Inasmuch, however, as they are handled like trigometric functions of real angles?except in regard to the plus and minus signs?it is a simple matter to acquire the requisite technical skill to use them. The hyperbolic function of a complex angle, consisting as it does of a real and an imaginary part, may represent a vector?the real part being the component of the vector along the horizontal, and the imaginary part, component along the vertical. Thus, for example, A sinh (x + j x) represents a vector just as A e j ? A/?, A (cos ? + j sin ?) represent vectors. Considerable experience has shown that the vector method for handling a-c. problems is much superior to the original method in which simple trigonometric functions were used. With this lesson before us, it should require but little contact with the problem at hand to demonstrate the superiority of the vector method, even though it employs the possibly unfamiliar hyperbolic quantities. These hyperbolic vectors have been used for a number of years in the analysis of problems involving a-c. circuits, which have distributed inductance and capacitance, and have proved their usefulness.

27 citations