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1

Extraction of Fringing-Effect Power Loss from Total Dissipation in Magnetic Component

Kasikowski Rafał

Pomiary Automatyka Robotyka

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2023

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R. 27, nr 4

33--38

EN

Power magnetics in the energy storage configuration are not able to handle a significant amount of power without the introduction of a physical discontinuity in their magnetic path. This frequently takes the form of a discrete air gap giving rise to certain consequences such as extra power dissipation in the coils mounted on gapped cores. The ascertainment of the impact of the fringing magnetic field at the air gap on the efficiency of power conversion is highly problematic due to the complex nature of the phenomenon. The fringing-effect power loss typically coexists and is combined with all the other power-dissipation mechanisms, which greatly complicates the extraction of losses brought about solely by the fringing flux at the air gap from the total amount of dissipation in a given magnetic component. Magnetic cores of composite materials do not require a discrete air gap, as the air gap in them is distributed throughout the entire material, thus preventing the fringing magnetic flux from forming. However, there is a downside to this approach, as power loss in the material is comparably greater and so are the manufacturing costs. As shown here, distributed-gap-type core materials, due to the absence of physical discontinuity, and hence the lack of registerable fringing-effect power loss, can be utilized to comparatively ascertain and extract the extra power dissipation due to the fringing effect phenomenon in gapped magnetic components.

PL

Elementy indukcyjne konwertujące i magazynujące moc elektryczną nie są w stanie przetworzyć znacznej ilości mocy bez wprowadzenia fizycznej nieciągłości w przestrzeń ich obwodów magnetycznych. Przerwa ta często przybiera formę dyskretnej szczeliny powietrznej, co pociąga za sobą pewne następstwa głównie w postaci dodatkowych start mocy w uzwojeniach tak skonstruowanych elementów indukcyjnych. Oszacowanie wpływu rozproszonego pola magnetycznego przy szczelinie powietrznej na sprawność przetwarzania energii jest bardzo problematyczne przede wszystkim ze względu na złożony charakter zjawiska. Ta dodatkowa strata mocy występuje zwykle wspólnie i łączy się z pozostałymi mechanizmami rozpraszania mocy, co znacznie komplikuje ekstrakcję strat spowodowanych wyłącznie przez strumień rozproszonego pola magnetycznego przy szczelinie powietrznej z całkowitej mocy rozproszonej w danym elemencie indukcyjnym. Rdzenie magnetyczne z materiałów kompozytowych nie wymagają dyskretnej szczeliny powietrznej, gdyż szczelina powietrzna jest w nich rozłożona w objętości całego materiału, a tym samym brakuje fizycznego mechanizmu powodującego powstawanie strumienia rozproszenia. Rozwiązanie to ma jednak wadę w postaci zwiększonych strat w materiale rdzenia. Jak zademonstrowano, rdzenie o szczelinie rozproszonej nie wykazują strat mocy spowodowanych strumieniem rozproszenia, a tym samym mogą stanowić podstawę do wyodrębnienia strat mocy wyłącznie z powodu tego zjawiska w elementach indukcyjnych z dyskretną szczeliną powietrzną.

2

Reduction of Fringing-Effect in Inductors by Quasi-Distributed-Gap Method

Kasikowski Rafał

Measurement Automation Monitoring

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2019

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Vol. 65, No. 2

48--51

EN

The fringing-field phenomenon can have a significant impact on the key performance parameters of magnetic components with an air gap. The fringing magnetic flux at the air gap has an effect on a component’s inductance, power loss and temperature distribution in copper windings. The induced excess eddy currents in the windings due to the fringing effect cause localized heating and reduce the overall efficiency of power conversion. This effect can be analysed by infra-red thermography to demonstrate the potential hazards of designing magnetic components with an air gap. Design engineers are frequently forced to design around the problem by employing a number of available techniques. The quasi-distributed-gap technique combats the issue at the origin as it essentially constrains the fringing magnetic flux at the downsized air gaps to their immediate vicinity. The selection of the length of the individual air gaps as well as their placement is not straightforward, as the phenomenon is a function of the air gap length and geometry. The resulting inductance of the component has to be the same or at least comparable to the original value in order to maintain the operating conditions of the application which the component is part of. This paper examines the effects of splitting a discrete air gap on the electromagnetic and thermal properties of inductors and presents a method to aid the design of quasi-distributed-gap inductors based on finite-element simulations as well as measurements. An analytic expression, which closely approximates the required length of quasi-distributed gaps, is developed.

3

Algorytmy ruchu wzbudników w indukcyjnym nagrzewaniu powierzchni walcowej

Frączyk A., Kucharski J., Urbanek P.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

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2015

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z. 126

51--62

PL

W artykule przedstawiono wybrane problemy związane z nagrzewaniem indukcyjnym obracającego się walca, z wykorzystaniem ruchomych wzbudników. Zaproponowano dwa algorytmy ruchu wzbudników i przeanalizowano ich cechy charakterystyczne. Prostsze z rozwiązań polega na systematycznym ruchu wzbudników wzdłuż tworzącej walca, przypominjącym ruch windy, a w bardziej zawansowanym podejściu algorytm wyszukuje miejsca na powierzchni walca, których temperatura najbardziej odbiega od wartości zadanej i tam kierowane są wzbudniki. Oba rozwiązania zostały przeanalizowane z wykorzystanie formalnego opisu, symulacji komputerowych oraz na drodze eksperymentalnej.

EN

In the paper some problems of induction heating of a rotating cylinder using moving inductors have been presented. Two algorithms applied for inductors’ movement control were proposed and their features were discussed. The simple approach assumes a systematic movement of inductors, resembling lift movement, while the more advanced one searches these places of cylindrical surface whose temperature differs significantly from the reference value. Both solutions were analyzed using formal description, computer simulations and experimental set-up.

4

Thermal analytical winding size optimization for different conductor shapes

Wojda R. P.

Archives of Electrical Engineering

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2015

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Vol. 64, nr 2

197--214

EN

The aim of this paper is to derive an analytical equations for the temperature dependent optimum winding size of inductors conducting high frequency ac sinusoidal currents. Derived analytical equations are useful designing tool for research and development engineers because windings made of foil, square-wire, and solid-round-wire windings are considered. Temperature dependent Dowell’s equation for the ac-to-dc winding resistance ratio is given and approximated. Thermally dependent analytical equations for the optimum foil thickness, as well as valley thickness and diameter of the square-wire and solid-round-wire windings are derived from approximated thermally dependent ac-to-dc winding resistance ratios. Minimum winding ac resistance of the foil winding and local minimum of the winding ac resistance of the solid-round-wire winding are verified with Maxwell 3D Finite Element Method simulations.

5

Microstructure and electromagnetic properties of microwave sintered CoCuZn ferrites

Patankar K. K.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 1

1-8

EN

Co-Cu-Zn ferrite material has been extensively used in multilayer chip inductors because of their good electromagnetic properties at higher frequencies and low sintering temperatures. In this research work, a comparative study on Co-Cu-Zn ferrite prepared from two different routes is reported. The two different routes are conventional ceramic sintering method (CS) and is microwave sintered (MS) method. The former route is most commonly used while the latter one is now gaining popularity in sintering processes. The work highlights that the sintering temperature and time were significantly reduced from 4 h and 1250 °C for the CS process to 20 min and 900 °C for MS process. Moreover, microwave sintering also improves the physical and electromagnetic properties of ferrite.

6

Particularities of Capacitor Bank Overstressing within Detuned Filters

Baloi A., Pana A.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 4

190-193

EN

Detuned filters are frequently used for reactive power compensation in electrical distribution network harmonically polluted. These kinds of filters are series LC circuits formed by filtering inductors and capacitors. The filtering inductor decrease the harmonic voltage at the terminals of the capacitor within the filter, but the value of the fundamental voltage at the terminals of the capacitor will increase. The paper presents a comparative study for two values of tuning frequencies used by the manufacturers of detuned filters.

PL

Rozstrojone filtry są często używane do kompensacji mocy biernej. Indukcyjności filtru zmniejszają liczbę harmonicznych ale wartość składowej podstawowej napięcia wzrasta na pojemnościach. W artykule analizuje się filtr przy dwóch częstotliwościach strojenia.

7

Foil Winding Resistance and Power Loss in Individual Layers of Inductors

Kazimierczuk M. K., Wojda R. P.

International Journal of Electronics and Telecommunications

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2010

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Vol. 56, No. 3

237-246

EN

This paper presents an estimation of high-frequency winding resistance and power loss in individual inductor layers made of foil, taking into account the skin and proximity effects. Approximated equations for power loss in each layer are given and the optimal values of foil thickness for each layer are derived. It is shown that the winding resistance of individual layers significantly increases with the operating frequency and the layer number, counting from the center of an inductor. The winding resistance of each foil layer exhibits a minimum value at an optimal layer thickness. The total winding resistance increases with the total number of layers.

8

A New Model for a Frequency-Dependent Non-Linear Reactor

Mokhtari H., Ghodsinya S. R. M., Rajabi A.

Electrical Power Quality and Utilisation. Journal

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2009

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Vol. 15, iss. 1

15--18

EN

Increase of power electronic devices has resulted in current/voltage harmonic pollution in power systems. Harmonics have adverse effects on equipment with magnetic materials. This paper investigates effects of harmonics on inductors and proposes a new model for a non-linear frequency-dependent inductor. Tbe study is based on experiments in which inductors are subjected to sinusoidal inputs at different frequencies. The accuracy of the proposed formula is also investigated.

9

Elektrotermiczny model cewki z rdzeniem ferrytowym do analizy przetwornic dc-dc

Górecki K.

Elektronika : konstrukcje, technologie, zastosowania

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2008

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Vol. 49, nr 4

194-198

PL

Zaproponowano nowy elektrotermiczny model cewki z rdzeniem ferrytowym przeznaczony do analizy przetwornic dc-dc w programie SPICE. Przedstawiono postać modelu, sposób jego implementacji w programie SPICE oraz wyniki jego weryfikacji doświadczalnej. Przedstawiono również wyniki analiz przetwornicy boost ilustrujące wpływ samonagrzewania w cewce na charakterystyki tej przetwornicy.

EN

In the paper the new electrothermal model of the inductor with the ferrite core, dedicated for the analysis of dc-dc converters in SPICE, is proposed. The method of the implementation of the model in SPICE is shown and some results of the experimental verification of the presented model are presented and discussed. Some results of the analysis of the boost converter, showing the influence of selfheating in the inductor on the converters characteristics are presented, as well.

10

A SiGe bipolar WCDMA power amplifier with 52% PAE at 3.3 V

Kitlinski K., Donig G., Bakalski W., Kapfelsperger B., Weigel R.

Kwartalnik Elektroniki i Telekomunikacji

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2004

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Vol. 50, z. 4

539-551

EN

A monolithic radio frequency power amplifier for WCDMA handheld applications has been fabricated in a 0.35 um, 40 GHz fT - volume production SiGe bipolar technology. The process technology features a doped ground connection for on-chip devices to improve the overall performance. At 3.3 V supply voltage saturated output power of 29 dBm with a PAE of 52% has been achieved; simultaneously OP1 dB reaches 28 dBm and the small signal gains is 32 dB.