Soft FerritesߞProperties and Applications
TL;DR: In this paper, the authors discuss the properties and applications of soft and hard ferrites and their applications in search-works, including the application of soft ferrite material from emc to rfid.
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Citations
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TL;DR: The squared-field-derivative method for calculating eddy-current (proximity effect) losses in round-wire or litz-wire transformer and inductor windings is derived in this paper.
Abstract: The squared-field-derivative method for calculating eddy-current (proximity-effect) losses in round-wire or litz-wire transformer and inductor windings is derived. The method is capable of analyzing losses due to two-dimensional and three-dimensional field effects in multiple windings with arbitrary waveforms in each winding. It uses a simple set of numerical magnetostatic field calculations, which require orders of magnitude less computation time than numerical eddy-current solutions, to derive a frequency-independent matrix describing the transformer or inductor. This is combined with a second, independently calculated matrix, based on derivatives of winding currents, to compute total AC loss. Experiments confirm the accuracy of the method.
344 citations
TL;DR: In this article, the relationship between wire size, normalized cost, and normalized loss is shown to have a general form that applies to a wide range of designs, and a practical design procedure is provided, applied to an example design, it leads to less than half the original loss at lower than the original cost, or, alternatively, under one fifth the original costs with the same loss as the original design.
Abstract: Design of litz-wire windings subject to cost constraints is analyzed. An approximation of normalized cost is combined with analysis of proximity effect losses to find combinations of strand number and diameter that optimally trade off cost and loss. The relationship between wire size, normalized cost, and normalized loss is shown to have a general form that applies to a wide range of designs. A practical design procedure is provided, Applied to an example design, it leads to less than half the original loss at lower than the original cost, or, alternatively, under one fifth the original cost with the same loss as the original design.
233 citations
Cites background from "Soft FerritesߞProperties and Applic..."
...The actual cost of the wire with an odd strand size may depend on the quantity purchased, and so it is not possible here to determine when it is economically advantageous....
[...]
TL;DR: In this paper, the two-port network approach and the step-response approach are used for determining stray capacitances in a two-winding high frequency transformer for circuit simulation and computeraided design purposes.
Abstract: This paper presents practical techniques for determining stray capacitances in a two-winding high frequency transformer for circuit simulation and computer-aided design purposes. These techniques fall into two categories: The two-port network approach; and the step-response approach. The first approach can be employed for high frequency transformer circuit models with the effect of stray capacitances modeled as a /spl pi/-shape network of three lumped stray capacitances. The second approach is useful for the transformer circuit model with the overall effects of stray capacitances modeled as lumped stray-capacitance connected cross the primary side. These techniques have been verified in the modeling and numerical simulation of a 500 W 25 kHz two winding E-core transformer. The merits and limitations of these techniques are also discussed.
200 citations
01 Sep 2015
TL;DR: In this paper, the design of power magnetic components for operation at high frequency (HF, 3-30 MHz) has been hindered by a lack of magnetic material performance data and by the limited design theory in that frequency range.
Abstract: The design of power magnetic components for operation at high frequency (HF, 3–30 MHz) has been hindered by a lack of magnetic material performance data and by the limited design theory in that frequency range. To address these deficiencies, we have measured and present core loss data for a variety of commercially available magnetic materials in the HF range. In addition, we extend the theory of performance factor for appropriate use in the HF design. Since magnetic materials suitable for HF applications tend to have low permeability, we also consider the impact of low permeability on design. We conclude that, with appropriate material selection and design, increased frequencies can continue to yield improved power density well into the HF regime.
160 citations
Cites background from "Soft FerritesߞProperties and Applic..."
...Values of k and β for all measured materials at all measured frequencies are listed in Table II....
[...]
21 Jun 2010
TL;DR: In this paper, the Steinmetz premagnetization graph (SPG) is introduced to calculate core losses under DC bias conditions, and a detailed description of the test system is given, as high accuracy is crucial.
Abstract: When designing inductive components, calculating core losses is a difficult and not yet entirely solved problem. In particular it is impossible to predict the influence of a DC premagnetization on the losses without performing extensive measurements. For this work, different materials have been tested to gain information how core losses are influenced by a premagnetization. Measurements on molypermalloy powder, silicon steel, nanocrystalline material, and ferrite cores have been performed. Of the tested materials, a premagnetization mainly influences losses in ferrites and nanocrystalline materials, whereas the influence of a premagnetization in molypermalloy powder cores, and cores of silicon steel is negligible. The Steinmetz Premag-netization Graph (SPG) that shows the dependency of the Steinmetz parameters (α, β and k) on premagnetization is introduced. This permits the calculation of core losses under DC bias conditions. Such graphs are given for different materials and different operating temperatures. In addition, a detailed description of the test system is given, as high accuracy is crucial.
158 citations
Cites background from "Soft FerritesߞProperties and Applic..."
...The most used equation that characterizes core losses is the power equation [1]1...
[...]
References
More filters
TL;DR: The squared-field-derivative method for calculating eddy-current (proximity effect) losses in round-wire or litz-wire transformer and inductor windings is derived in this paper.
Abstract: The squared-field-derivative method for calculating eddy-current (proximity-effect) losses in round-wire or litz-wire transformer and inductor windings is derived. The method is capable of analyzing losses due to two-dimensional and three-dimensional field effects in multiple windings with arbitrary waveforms in each winding. It uses a simple set of numerical magnetostatic field calculations, which require orders of magnitude less computation time than numerical eddy-current solutions, to derive a frequency-independent matrix describing the transformer or inductor. This is combined with a second, independently calculated matrix, based on derivatives of winding currents, to compute total AC loss. Experiments confirm the accuracy of the method.
344 citations
TL;DR: In this article, the relationship between wire size, normalized cost, and normalized loss is shown to have a general form that applies to a wide range of designs, and a practical design procedure is provided, applied to an example design, it leads to less than half the original loss at lower than the original cost, or, alternatively, under one fifth the original costs with the same loss as the original design.
Abstract: Design of litz-wire windings subject to cost constraints is analyzed. An approximation of normalized cost is combined with analysis of proximity effect losses to find combinations of strand number and diameter that optimally trade off cost and loss. The relationship between wire size, normalized cost, and normalized loss is shown to have a general form that applies to a wide range of designs. A practical design procedure is provided, Applied to an example design, it leads to less than half the original loss at lower than the original cost, or, alternatively, under one fifth the original cost with the same loss as the original design.
233 citations
TL;DR: In this paper, the two-port network approach and the step-response approach are used for determining stray capacitances in a two-winding high frequency transformer for circuit simulation and computeraided design purposes.
Abstract: This paper presents practical techniques for determining stray capacitances in a two-winding high frequency transformer for circuit simulation and computer-aided design purposes. These techniques fall into two categories: The two-port network approach; and the step-response approach. The first approach can be employed for high frequency transformer circuit models with the effect of stray capacitances modeled as a /spl pi/-shape network of three lumped stray capacitances. The second approach is useful for the transformer circuit model with the overall effects of stray capacitances modeled as lumped stray-capacitance connected cross the primary side. These techniques have been verified in the modeling and numerical simulation of a 500 W 25 kHz two winding E-core transformer. The merits and limitations of these techniques are also discussed.
200 citations
01 Sep 2015
TL;DR: In this paper, the design of power magnetic components for operation at high frequency (HF, 3-30 MHz) has been hindered by a lack of magnetic material performance data and by the limited design theory in that frequency range.
Abstract: The design of power magnetic components for operation at high frequency (HF, 3–30 MHz) has been hindered by a lack of magnetic material performance data and by the limited design theory in that frequency range. To address these deficiencies, we have measured and present core loss data for a variety of commercially available magnetic materials in the HF range. In addition, we extend the theory of performance factor for appropriate use in the HF design. Since magnetic materials suitable for HF applications tend to have low permeability, we also consider the impact of low permeability on design. We conclude that, with appropriate material selection and design, increased frequencies can continue to yield improved power density well into the HF regime.
160 citations
21 Jun 2010
TL;DR: In this paper, the Steinmetz premagnetization graph (SPG) is introduced to calculate core losses under DC bias conditions, and a detailed description of the test system is given, as high accuracy is crucial.
Abstract: When designing inductive components, calculating core losses is a difficult and not yet entirely solved problem. In particular it is impossible to predict the influence of a DC premagnetization on the losses without performing extensive measurements. For this work, different materials have been tested to gain information how core losses are influenced by a premagnetization. Measurements on molypermalloy powder, silicon steel, nanocrystalline material, and ferrite cores have been performed. Of the tested materials, a premagnetization mainly influences losses in ferrites and nanocrystalline materials, whereas the influence of a premagnetization in molypermalloy powder cores, and cores of silicon steel is negligible. The Steinmetz Premag-netization Graph (SPG) that shows the dependency of the Steinmetz parameters (α, β and k) on premagnetization is introduced. This permits the calculation of core losses under DC bias conditions. Such graphs are given for different materials and different operating temperatures. In addition, a detailed description of the test system is given, as high accuracy is crucial.
158 citations