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
16 Mar 2014
TL;DR: In this article, a phase shift full bridge (PSFB) DC/DC converter based input series and output parallel structure (ISOP) is selected due to the high input voltage and large output current operation condition.
Abstract: Energy efficiency of typical data centers is less than 50% where more than half of the power is consumed during power conversion, distribution, cooling, etc. In this paper, a single power stage architecture that converts 400 V to 1 V directly targeting high system efficiency is proposed. A phase shift full bridge (PSFB) DC/DC converter based input series and output parallel structure (ISOP) is selected due to the high input voltage and large output current operation condition. The latest Gallium Nitride (GaN) FETs are implemented in the prototype circuit because of their low output junction capacitance and zero reverse recovery charge. The high frequency planar transformer is designed correspondingly with consideration of GaN FETs on the primary side. A prototype of the PSFB converter is designed, built, and tested. Preliminary experimental results are provided to verify the design.
21 citations
01 Sep 2018
TL;DR: This paper investigates proximity and skin effects winding losses in a high performance and high frequency brushless permanent magnet machine designed for electric sport racing application, where such losses have a relevant impact.
Abstract: This paper investigates proximity and skin effects winding losses in a high performance and high frequency brushless permanent magnet machine designed for electric sport racing application, where such losses have a relevant impact. A detailed finite element analysis (FEA), with all conductors per slot modelled, is performed for various winding configurations, with single and multiple strands-in-hand, considering random conductors placement within the stator slots. A new hybrid analytical-FEA method is proposed for speeding up the losses calculation and then validated against pure FEA method. The proposed method can be further used in accurate and fast estimation of the motor performance and in optimization procedures, avoiding heavy computational burden of full FEA simulations.
21 citations
01 Jan 2001
TL;DR: Modeling and design of magnetics for switching converters is the topic of Part III of this book.
Abstract: Magnetics are an integral part of every switching converter. Often, the design of the magnetic devices cannot be isolated from the converter design. The power electronics engineer must not only model and design the converter, but must model and design the magnetics as well. Modeling and design of magnetics for switching converters is the topic of Part III of this book.
20 citations
TL;DR: In this article, the design of the required passive component values to be integrated, a comprehensive electromagnetic model based on energy storage is presented, and the overall structure losses including winding, core and dielectric losses are also estimated through the development of a partly one-dimensional electromagnetic field approximation.
Abstract: Over the past few years, the electromagnetic integration of multiple passive components into a single integrated planar power passive module has been shown viable, not only for resonant structures, but recently also for nonresonant applications. In this paper, the development of an electromagnetic model for a resonant integrated spiral planar power passive (ISP/sup 3/) structure is presented. For the design of the required passive component values to be integrated, a comprehensive electromagnetic model based on energy storage is presented. The overall structure losses including winding, core and dielectric losses are also estimated through the development of a partly one-dimensional electromagnetic field approximation. Finally, these electromagnetic models for design and loss estimation are compared to experimental results for three different prototypes of a particular design. The results show agreement to well within 10% of component and loss values in almost all cases.
20 citations
TL;DR: A comprehensive review on advancement of soft magnetic materials for high-power-density magnetic devices and advanced technologies for characterizations and optimal design of HFTs is presented.
Abstract: With the development of advanced soft magnetic materials of high-saturation flux density and low specific core loss and semiconductor power devices, the high-frequency transformer (HFT) has received significant attention in recent years for its widespread emerging applications. The optimal design of high-power-density HFTs for high-performance energy conversion systems is, however, a multiphasic problem that needs special considerations on various aspects such as core material selection, minimization of parasitic components, and thermal management. This paper presents a comprehensive review on advancement of soft magnetic materials for high-power-density magnetic devices and advanced technologies for characterizations and optimal design of HFTs. The future research and development trends are also discussed.
20 citations
References
More filters
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
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
64 citations
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
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