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In a previous paper, we introduced a modified Steinmetz equation to account for dc-bias field effects, which requires only a simple dc permeability measurement to predict total power loss. In this paper, we expanded our investigation to include Finemet nanocrystalline material and found that our modified Steinmetz formalism was effective in predicting dc-bias-related losses for this system as well. In this paper, it was observed that Finemet cores exhibit lower losses than Metglas cores under identical test frequencies and bias fields. In addition, we show that a full characterization of the dc loss component necessitates the consideration of higher order ( $n>1$ ) harmonic components. In order to quantify these higher frequency loss components, a dc–dc converter-based test system was built to intentionally introduce inductor current harmonics by varying the filter capacitance and parasitic inductance of the test system. Both core types were evaluated under fundamental frequencies of 20 to 150 kHz and dc-bias fields of up to 1.3 kA/m, with the inclusion of distorted waveforms obtained by varying filter capacitance. At higher frequencies, the Metglas cores were found to exhibit greater loss fractions associated with the higher order harmonic components. A detailed summary of the measured core loss characteristics for both core types is included and discussed. This paper includes the details of the measurements, the modified Steinmetz relation, and the loss extraction algorithm used for analysis. [ABSTRACT FROM PUBLISHER]

The quantitative analysis of the iron loss taking magnetic hysteresis behavior into account is essential for the development of high-efficiency electric machines. In a previous paper, a novel magnetic circuit model incorporating a play model, which is one of the phenomenological models of magnetic hysteresis, was proposed. It was clear that the proposed model can calculate the hysteresis loop of a ring core with high speed and high accuracy. However, this method was applied only for the objects with simple shapes. Thus, it is necessary to extend the applicable range for the objects with more complicated shapes. This paper presents a novel reluctance network analysis (RNA) model incorporating the play model and indicates the validity of the proposed RNA model by using a three-phase-laminated-core variable inductor as an object of discussion. [ABSTRACT FROM AUTHOR]

A variable inductor consists of a magnetic core, primary dc windings, and secondary ac windings. The effective inductance of the secondary ac winding can be controlled by the primary dc current because of its nonlinear magnetic characteristic. Hence, variable inductors can be applied as a reactive power compensator for voltage stabilization in electric power systems, and have desirable features such as a simple and robust structure, low cost, and high reliability. In a previous paper, a concentric-winding-type three-phase variable inductor with a 2-D structure has been proposed. It was demonstrated that the 2-D variable inductor has good controllability and a low distortion current. To further increase productivity and reduce costs, this paper presents a novel concentric-winding-type three-phase variable inductor with a 3-D structure. It is demonstrated that the leakage flux of the proposed 3-D variable inductor is reduced by more than 30%. Furthermore, a 6.6 kV–100 kVA 3-D variable inductor is designed and compared to its 2-D counterpart. It is proved that eddy current loss, which is induced within an oil-immersed self-cooled tank because of leakage flux from the variable inductor, can be reduced to one-third of that of the 2-D variable inductor. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study on different microfabricated inductors (microtransformers), which are suitable for high-frequency power application. The main topic of this study is comparing and analyzing the effect of some factors such as material type, number of turns, and coil form on microinductor performance considering a fixed chip size, fixed magnetic core size, and core form. Two different microtransformer designs with different magnetic core materials are considered in this work. The core materials used in this work are NiFe45/55 and CoFe45/55. Also, two types of device packages are developed, namely, Quad Flat No-Lead and FR4 embedded packages. For device testing, different high-frequency switching regulators available on the market are used. This study shows the influence of different parameters on the performance of a certain high-frequency application. In this paper, we discuss the influence of the design, magnetic material, and package type on thermal performance and the efficiency of the power application. [ABSTRACT FROM AUTHOR]

This paper presents integrated inductors with Co-Zr-Ta-B (CZTB) thin films on flexible organic substrates for MHz–GHz applications. This paper demonstrated the fabrication and characterization of magnetic thin-film inductors on flexible organic substrates, such as polyimide and Ajinomoto build-up film thin films. These films have thicknesses of only tens of micrometer and thus are very flexible compared to the same inductor structures fabricated on rigid substrates, such as quartz. The magnetic films on flexible substrates were observed to maintain similar magnetic properties compared with those on Si substrate, but with greater coercivity likely due to the increased roughness of the substrate surface. The fabricated thin-film inductors on organic substrates with inductance $L$ , measured by RF characteristics, have shown significantly increased inductance compared to air-core inductors (without magnetic core materials). This paper also demonstrated a high frequency response, clearly over GHz, consistent with the CZTB type of materials. The frequency response, as well as inductance and Q values, remains similar even after many iterations of bending to a large degree, indicating the robustness of the inductor on flexible organic substrates, as well as that of the magnetic thin films. [ABSTRACT FROM AUTHOR]

This paper introduces a three-phase reversible transformer model for the study of low-frequency transients. The model topology is obtained from the direct application of the principle of duality by drawing basic circuit elements on top of the transformer frame. The model parameters are obtained from terminal and physical size measurements as well as the characteristics of the iron core. The implementation of the model is based on standard drag-and-drop circuit elements available in electric circuit simulation programs. The model is validated with inrush current and normal open circuit laboratory measurements. The main advantage of this model is that the parameters remain the same for the simulation of different operating conditions from all terminals. This is true for transients involving deep saturation, normal loading operation, or open circuit. [ABSTRACT FROM AUTHOR]

In this paper, we highlight the influence of geometrical uncertainties (winding pattern and wire diameter) on the $RLC$ parameters of wound magnetic components. To that end, the finite-element method is embedded in a Monte Carlo simulation in order to compute probability distributions of the parameters. An algorithm to randomly generate realistic winding configurations is also proposed. [ABSTRACT FROM AUTHOR]

This paper introduces a novel identification method of the magnetization properties of the core material for an inductor from measured inductance data. The proposed method allows us to obtain the magnetic hysteresis characteristics without a special measurement instrument for material $B - H$ properties. The proposed method determines the parameters included in the distribution function for the Preisach model from the measured $L - I$ characteristics. It is shown that the identified initial magnetization curve and the minor loops are in good agreement with the original $B - H$ curves. The uniqueness for the identification problem is numerically verified. [ABSTRACT FROM AUTHOR]

In this paper, one proposes a model-assisted probability of detection approach to study the reliability of detecting special defects. The approach is based on a 3-D finite-element T– $\Omega $ formulation with circuit coupling. This model is then applied to calculate performances of induction thermography method to detect thin open cracks in vessel reactor shell in nuclear installation. [ABSTRACT FROM AUTHOR]

A variable inductor, which consists of only magnetic core and primary dc and secondary ac windings, can control effective inductance of the secondary ac winding by the primary dc current due to the magnetic saturation effect. Hence, the variable inductor can be applied as a VAR compensator for voltage regulation in electric power systems. In a previous paper, a novel concentric-winding type three-phase variable inductor was proposed, in which the primary dc and secondary ac windings are concentrically wound on the same leg. It was indicated by a numerical analysis that the proposed variable inductor has good controllability and low distortion current. This paper presents the experimental results of a 4 kVA concentric-winding type threephase variable inductor. Furthermore, to prove the advantage of the proposed variable inductor, copper and iron losses, leakage flux, and reactive power per weight are compared with those of the previous variable inductor. It is demonstrated that the copper loss of the proposed variable inductor is improved by 40%, the leakage flux is reduced by half, and the weight can be reduced by 40% in comparison with the previous variable inductor. [ABSTRACT FROM AUTHOR]

This paper provides a first tunable low-noise amplifier (LNA) design with Permalloy (Py) enabled inductors. Tunable inductor is an important passive device in adaptive radio frequency circuit design. In this paper, a new integrated tunable inductor is implemented utilizing novel slow-wave transmission lines that are built with coplanar waveguide having alternative high and low impedance signal sections, and the Py thin films are deposited and patterned on the signal line of narrow section to provide higher and tunable inductance density. The inductance per unit length has been increased from 877 to 949 nH/m with 100 nm Py thin film at 5 GHz. A tunable 5 GHz LNA utilizing SWLTs is developed, where the tunability of power reflection and power gain of LNA are demonstrated with variable inductors. [ABSTRACT FROM AUTHOR]

In order to reduce the vibration of shunt reactors with gapped iron-core structure, accurate stress computation should be carried out. The magnetization and magnetostrictive anisotropy should be considered in the calculation. In this paper, the magnetization and magnetostrictive properties of non-oriented silicon steel sheets along the rolling direction and the transverse direction are first measured by a magnetization and magnetostriction tester. Based on the measurement results, an electromagneto–mechanical coupled numerical model for shunt reactors, considering magnetization and magnetostrictive anisotropy, has been developed. Then, the stress distribution of the reactor core is calculated and that between isotropy and anisotropy numerical model is compared. From the computation results, it can be seen that magnetization and magnetostrictive anisotropy greatly influences the stress distribution of the reactor core. [ABSTRACT FROM AUTHOR]

This paper deals with the harmonic-balance (HB) finite-element (FE) analysis of a multi-turn winding device coupled to electrical circuits comprising nonlinear components. The eddy-current effects in the windings are accounted for via a frequency-dependent reluctivity and impedance determined with a homogenization technique. The proposed multi-frequency approach is validated through a single-phase four-diode rectifier with an axisymmetric FE model of an inductor. The system of nonlinear algebraic equations is solved by means of the Newton–Raphson method. The HB results are validated with classical time-stepping simulations. The computational cost is briefly discussed. [ABSTRACT FROM AUTHOR]

In this paper, a new design of a heterogeneous integrated wireless sensor for displacement measurement is presented. The designed sensor consists of an inductor fabricated in printed circuit board technology, as an essential part, a spacer, and an electrode on a flexible polyimide foil as membrane. The proposed design of a sensor enables wireless displacement measurements using an external inductor as an antenna. Deflecting the polyimide membrane draws the electrode close to the coil of inductor (as bottom electrode) and causes an increase in the capacitance between them which changes the resonant frequency of the sensor. Displacement is wirelessly measured by phase-dip method determining the change of the resonant frequency of the antenna sensor system. The measurement of the sensor is performed and the characteristic of the sensor is obtained. Displacement is measured up to 500 \mu \textm in the steps of 50 \mu \textm , and the resulting sensitivity of designed sensor is 16.2 kHz/ \mu \textm . [ABSTRACT FROM AUTHOR]

Magnetic-valve controllable reactor (MCR) has been widely applied in many kinds of industries, such as power systems and ferrous metallurgy. As electrical equipment, MCR can adjust its reactance smoothly and continuously, which has advantages like low dissipation and maintenance costs, high reliability. In this paper, a precise 2-D field-circuit coupling model of MCR is established by the finite element analysis software-ANSYS, and then the analysis of the harmonic characteristics of this model is presented in detail. Compared with the conventional numeric method, the proposed method could obtain more practical and accurate results and also has the ability to analyze electromagnetic field. Meanwhile, an experimental platform of a 2200 VA/380 V MCR is built. This paper provides detailed harmonic characteristics analysis of simulation and experiment. The simulation and experimental results verify that the proposed method is more accurate than using conventional ways. [ABSTRACT FROM PUBLISHER]

This paper examines the process challenges in developing high aspect-ratio copper structures for improving microinductor performance. With increased miniaturization, increasing windings losses become a major challenge limiting the microinductor efficiency. It was also identified that within constraint footprints coil thickness to spacing ratio increase can reduce dc resistance significantly. In this paper, we present a reliable process for developing high aspect ratio ( $\sim 5.8$ ) resist moulds for copper electrodeposition. This resist provided coil spacings 10 $\mu $ m for 58 $\mu $ m resist thickness; this in turn reduces the dc resistance of a typical microinductor by more than 17% when compared with a similar device reported previously. [ABSTRACT FROM AUTHOR]

A scalable, broadband, and physics-based compact model for on-chip spiral inductors with rectangular outline shape is demonstrated for the first time in this paper. A simple dc inductance model is developed based on the current sheet approximation. The reduction in inductance due to the flow of eddy current in a back metal plate is considered using the method of images. A three-ladder network is shown to be sufficient to accurately model skin effect caused due to the magnetic field setup at high frequencies. Geometry-dependent expression suitable for rectangular cross-sectional metal strips is presented to predict the proximity effect. Physics-based expression for the substrate capacitance is derived. The proposed model is also shown to have a good correlation in the presence of a patterned ground shield. The proposed model is verified across CMOS process parameters that affect the inductor performance, such as metal thickness, substrate resistivity, and substrate thickness. Furthermore, model accuracy is also validated across design parameters such as spiral width, spacing between turns, number of turns, and diameter. The model is shown to have a good agreement with both EM simulations and measurements. [ABSTRACT FROM AUTHOR]

The emerging contactless cell membrane permeabilization methodology (magnetoporation) based on high pulsed magnetic field (PMF) is highly dependent on the applied pulse parameters. Due to the lack of magnetic experimental infrastructure, the parametric analysis of PMF-induced effects, scatter, and consolidation of research in this field is limited. Therefore, this paper presents a flexible high dB/dt magnetic field pulser, which is easy to reproduce. The generator is applicable in the area of contactless biological cell membrane permeabilization or study of the biological effects of PMF. The pulse forming circuit is based on the high-power ignitron switch (20 kV, up to 100 kA), which is driven by an array of silicon control rectifiers. The generator is capable of forming repetitive pulses with sub-microsecond rise time, which ensures induced electric field in the range of several tens to hundreds of V/cm. The generator is compact, programmable and includes an emergency discharge circuit for safety reasons. The setup may find direct application as a platform for basic magnetoporation experiments. [ABSTRACT FROM AUTHOR]

In this paper, the magnetostrictive orthogonal calculation method is used to simulate the vibration of iron cores of the transformer and shunt reactor models. The two models have the same size except there is a 2 mm air gap in the middle core of the reactor model. The Maxwell stress and total stress on the two cores are quantitatively calculated. The calculated results show that the air gap has a great influence on the vibration of the shunt reactor core. The Maxwell stress is the main reason for the vibration of the reactor core, but the vibration of the transformer core is mainly caused by magnetostriction. Finally, the experimental platform is built to measure the vibration accelerations of the two models and verify the results of the simulation. [ABSTRACT FROM AUTHOR]

Applying the Jiles-Atherton (JA) model to simulate the dynamics of power electronics circuit is a challenge but very attractive since it is possible to carry out continuous simulation with only several input parameters. Although other methods such as the Preisach-model can result in approximate waveforms for such applications, it is still a far distance to reach exact ones to suit chaos and other high accuracy-requiring researches. In this paper, the JA model has been successfully applied to model the dynamics of resonant inverter for driving a nonlinear load: a fluorescent lamp. The circuit is driven by a high frequency square wave voltage source. A semi-theoretical fluorescent lamp model developed from HID lamp model is adopted in the modeling. The simulation waveforms of voltage across the lamp and current through it are close to those measured ones reported in the literature papers. [ABSTRACT FROM AUTHOR]

To miniaturize the non-isolated converter, the use of high driving frequencies is an effective means of downsizing inductors. However, the loss of inductors increases along with driving frequencies. In this paper, we considered means of reducing two types of loss in inductors, namely, iron loss using magnetic composite materials and copper loss using a vacant space. The Q factor can be effectively improved by providing vacant space that width of the vacant space is preferably slightly smaller than that of the copper plate above and below the copper plate. And the efficiency of the non-isolated dc–dc converter applied the inductor with vacant space is increased compared with that of the without vacant. [ABSTRACT FROM AUTHOR]

This paper proposes a fast, in situ demagnetization method for protection current transformers (CTs). Simulations show that the method can automatically demagnetize a CT within 300 ms in situ, i.e., while the CT is deenergized but still connected to the substation. Therefore, unlike existing methods that require the CT to be disconnected from the substation, this new method can be used to demagnetize a CT during a short interruption, e.g., the time it takes an autorecloser to operate, rather than requiring an extended outage of the substation. This will dramatically increase the number of opportunities for the demagnetization of protection CTs, which will alleviate the threat of remanent flux in the CT from causing saturation and compromising the performance of power system protection. Furthermore, by demagnetizing the CT in situ, the method avoids the risk of the improper reconnection of the CT, creating a source of hidden failure. The new method uses the existing dc voltage source in the substation to charge the CT and a parallel-connected inductor. An automatic control scheme is presented that manages the charge/discharge of the inductor, and thereby the demagnetization, by controlling three switches that reconfigure an $RLC$ circuit. The additional hardware required by the method is the three switches, the switch controller, and the $RLC$ circuit. The new method is tested for different hysteresis characteristics, levels of remanent flux, and errors in the assumed element parameters and measured hysteresis characteristics using EMTP-RV simulations. The results indicate that the proposed method can quickly and effectively demagnetize a protection CT in situ. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to carry out an analysis of the electromagnetic (EM) aspects involved in magnetic forming processes. Moreover, we shall address two specific issues: 1) modeling of Maxwell equations and comparison between the classical quasi-static approach and the full dynamic model (inclusion of displacement currents) and 2) modeling the electric circuit parameters involved in a typical EM forming process. In order to carry out this work, a 3-D finite-element model has been developed in our laboratory. This model can also be used for benchmarking an EM solver aimed at magnetic pulse forming applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel adaptive subdomain model order reduction (MOR) based on proper orthogonal decomposition (POD) and discrete empirical interpolation (DEI) methods for nonlinear magneto-quasi-static (MQS) problems. In this method, a nonlinear region is decomposed into two regions, where one of the regions includes all those finite elements that have a particularly strong saturation and the other region does not. MOR based on POD and DEI methods is applied only to the latter region. Both the regions are determined automatically at each time step. It is shown that this method can effectively reduce the computational time to solve the nonlinear MQS problems without losing the quality of accuracy. [ABSTRACT FROM AUTHOR]

This paper presents the generation of equivalent circuits from a finite-element (FE) model of electromagnetic devices using proper orthogonal decomposition (POD). This method effectively computes the frequency response of the reduced FE model constructed by the POD-based model order reduction. Then, the circuit parameters are determined so as to minimize the error between the frequency responses of the reduced FE model and equivalent circuit. The frequency characteristics of an inductor and the induction heating machine evaluated by the equivalent circuit are shown to be in good agreement with those computed from the original FE model. [ABSTRACT FROM AUTHOR]

This paper describes an analysis method for inductance and iron loss considering the magnetic hysteresis property in reactors. We discuss inductance calculation methods based on magnetization curves and hysteresis loops. Furthermore, we propose a novel iron loss analysis method under ac excitation with single high-frequency ripples with low computational cost. These numerical results are compared with the experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes an equivalent-circuit generation from the finite-element (FE) model of electromagnetic devices using a model order reduction (MOR). In this method, an equivalent circuit is directly generated from the reduced transfer function obtained using MOR based on Padé approximation via the Lanczos process. It is shown that the generated circuit yields sufficiently accurate results in both frequency and time domains. Moreover, the computational time of the present method is much shorter than that of the circuit generation based on frequency sweep using the conventional FE analysis. [ABSTRACT FROM AUTHOR]

This paper describes the design, fabrication, and electric performances of planar inductors with Fe0.76B0.12Si0.04C0.08 (Fe–B–Si–C) flakes composite. These inductors were designed with the help of an analytical magnetic circuit calculation, a finite-element method electromagnetic field simulator, and the Jiles–Atherton hysteresis model with the segmentation model so as to attain the desired inductance of 0.5~\mu H and dc resistance of 100 ~{\rm m}\Omega . To verify the simulation results, the planar inductors with Fe–B–Si–C flake composite were fabricated, and their electric performances were investigated. The inductance of the fabricated inductor is 4–4.5 times as high as that of the air-core inductor. The dc superimposed inductance at 1 MHz with output current of 1.4 A is \sim 0.58~\mu$ H, which is only 17% less than the no-load inductance. Therefore, the fabricated planar inductors meet all of the required electric performances. In addition, the maximum efficiency reached 91.7% for 4 V input and 3 V output of a system in package dc-to-dc converter integrated with the inductor and a CMOS IC. [ABSTRACT FROM AUTHOR]

Current-controlled variable inductors adjust the inductance of an alternating current (ac) coil by applying a controlled dc current to saturate the iron cores of the ac coil. The controlled dc current has to be maintained during operation, which results in increased power losses. This paper presents a new stress-based variable inductor to control inductance using the inverse magnetostrictive effect of a magnetostrictive material. The stress can be applied by a piezoelectrical material, and thus a voltage-controlled variable inductor can be realized with zero-power consumption. The new stress-based variable inductor concept is validated using a 3-D finite-element analysis. A prototype was manufactured, and the experimental results are presented. A linear relationship between inductance and applied stress can be achieved. [ABSTRACT FROM AUTHOR]

This paper examines the nonlinear behavior of inserted type integrated magnetics used in linear level control converters. Due to the nonlinear behavior of the magnetics, an implementation of the insertion type magnetic integration needs to be carefully considered. The saturation of magnetics is normally not a concern in high-voltage input applications, but becomes a serious issue when designing for low-voltage input and high power applications. In this paper, the inserted type integrated magnetics has been categorized into two types according to their magnetic integration configurations. Investigation and discussion of their nonlinear behavior will be presented with the assistance of 3-D simulation results based on the finite-element method. A case study of a 350 W dc–dc converter is used throughout this paper for the ease of illustration. [ABSTRACT FROM AUTHOR]

This paper studies the dc bias phenomenon and integrated magnetic technology in a single-phase transformer. A new transformer with the function of dc bias elimination based on the nano-composite magnetic material is designed, and a controllable reactor is integrated into the transformer by integrated magnetic technology. The mathematical model of hysteresis is established, and the correspondence relationship between coercivity and remanence of this material is determined; dc bias magnetic potential in the transformer core can directionally be eliminated using the conversion of coercivity and remanence of the nano-composite magnetic material. The integrated controllable reactor has the notable characteristics of decoupling with other windings, high linearity, less extra covering area, and energy saving. The prototype experimental results verify the correctness of the design. [ABSTRACT FROM AUTHOR]

This paper presents the modeling of a tunable inductor using a low-temperature co-fired ceramic (LTCC)-ferrite tape and subsequent development of a loaded transmission line phase shifter using these inductors. The inductors are initially realized in the form of circular disks fabricated from commercially available ferrite tape (ESL 40011) wound with a copper wire. A complete model of this inductor is obtained between 0.3 and 4 GHz and validated by measurements. The phase shifter comprises these inductors in shunt, thus minimizing the effect of low-field magnetic losses in $L$ -band. The magnetic material is operated below the resonance region in a partially magnetized state with the help of a bias current that configures the phase shifter electronically. The phase shifter exhibits an insertion loss of 2 ± 0.5 dB and a differential phase shift varying between 35° and 10° in the above band. Finally, to demonstrate the feasibility of integration with other RF components, a working prototype of the same phase shifter that is fully integrated in LTCC is also presented with measurements. [ABSTRACT FROM AUTHOR]

This paper presents a design study of novel geometrical configurations for miniaturized toroidal planar core thin-film inductors. A standard core with square-shaped toroidal geometry is compared with a new core with serpentine toroidal geometry. A design procedure is provided to maximize the inductance value of a square toroid in a certain footprint area. In addition, the mathematical model of the inductor demonstrates the possibility to further increase the maximum inductance value for closed or air-gap core inductors in a given footprint area (up to 35% in 16 mm ^\mathrm 2) , by means of a more efficient use of the core surface area in the case of serpentine geometry, assuming the same coupling factor for both windings. Furthermore, the presented serpentine geometry increases performances in terms of magnetic energy density and quality factor, while retaining higher inductance values, at the cost of a limited increase of layout complexity. This paper also provides a more accurate estimation of the inductance of a square-shaped toroidal inductor based on the evaluation of the mean magnetic path length accounting for the non-uniformity of the magnetic flux density in the core cross section and for the corner effect. [ABSTRACT FROM PUBLISHER]

We report a significant fractal-scaled increase in inductance for conductive pathways oriented in a fractal loop-based layout for a suite of planar inductors, which effectively occupy the same layout space and require only a single fabrication layer. These are closely predicted using a fractal scaling model for generalized loop-based inductors elucidated in this paper. Single-layer planar fractal structures were investigated with the loop inductor serving as the base construct. Thin sub-200 nm Cr/Au metal films compatible with flexible and stretchable substrates were used. It was found that while higher fractal orders did improve the inductive performance (over nine times from zeroth to third order), it is met with increased resistance. However, when compared with its equivalent series orientation, the effective sheet resistance of the simple fractal strategy demonstrated a clear advantage of up to four times. When the inductor is normalized for thickness, a quality factor Q greater than 40 is observed for all structures. Finally, the inductance quality gain figure of merit showing the optimal geometrical approach is introduced to quantify the quality of the structure’s inductance over its resistance. [ABSTRACT FROM AUTHOR]

In this paper, the electromagnetic interference reduction effect of a magnetorheological (MR) fluid-gap inductor in a dc/dc converter is investigated. For a realistic electromagnetic simulation, a prototype MR fluid-gap inductor is built and put in a typical buck converter setup, and the current waveform of the inductor is measured. Based on the measured current waveform, a 3-D time domain finite element electromagnetic analysis is performed considering non-linearity of an MR fluid and complex geometry of the winding. The rms and maximum values of the leakage flux and eddy current losses of the MR fluid-gap inductor are calculated and compared with those of the air-gap inductor. It is predicted that the eddy current heat source due to the leakage flux from the gap is reduced by as much as 75.6% for the MR fluid-gap inductor. To verify the simulation data, the leakage fluxes of both MR fluid-gap and air-gap types of inductors are measured in a dc/dc converter setup, and their experimental results are compared with calculated ones. [ABSTRACT FROM PUBLISHER]

In this paper, we present the modeling, fabrication, measurement techniques, and characterization results of multilayer miniature coplanar waveguide (CPW) meander-type inductors for high-frequency applications. Detailed procedure of the fabrication process based on using ink-jet printing technology is given. Silver nanoparticle ink that contains 20 wt% of silver was printed on a flexible polyimide foil 50 \(\mu \) m thick in one, two, and three layers. It is shown that multilayer CPW inductors have improved performance. Almost two times better \(Q\) -factor value was achieved. This is an encouraging result for multilayer printing in ink-jet technology. [ABSTRACT FROM AUTHOR]

The control element drive mechanism is one of the major equipment of a nuclear reactor, and it controls the reactivity by providing linear movement to the control elements. It should provide highly reliable up and down movements to control elements during reactor normal operation and release the control elements freely when the scram is required to shutdown a reactor immediately in case of a reactor emergency. The control elements complete full stroke drop by gravity in a few seconds for scram. Because of these essential- and safety-related operations, the performance of a control element drive mechanism should be verified experimentally. In this paper, the test results from the lifting force test, which is one of performance verification tests for nuclear equipment, are presented, and they are compared with the finite element analysis results. [ABSTRACT FROM AUTHOR]

To realize the basic technology of a package-level dc power grid for the next generation power delivery to large scale integrated circuits (LSIs), two types of planar spiral inductors embedded in an organic interposer, for several tens of megahertz switching power supply integrated in LSI package, have been proposed. One is a Zn–Fe ferrite core spiral inductor, and another is a hybrid core spiral inductor, with quasi closed magnetic circuit consisting of the bottom Zn–Fe ferrite core and top carbonyl-iron/epoxy composite core. In this paper, the two types of planar spiral inductors have been fabricated and evaluated. From the experimental results, it was found that the hybrid core planar spiral inductor exhibited higher \(Q\) -factor and larger rating dc current than the Zn–Fe ferrite core inductor. [ABSTRACT FROM AUTHOR]

This paper presents a new technique of shape optimization of devices taking into account acceptable tolerances of their dimensions. The technique is based on a combination of classic optimization procedures and a sensitivity analysis carried out in several steps in the course of the optimization process. This analysis is able to decide whether the given variant is worth further optimizing or the changes in the objective functions are unacceptably high even with small variations of parameters (such a variant is immediately rejected). The power of the methodology is illustrated on an example of induction brazing, whose results are discussed. [ABSTRACT FROM AUTHOR]

Air gaps are often used in a design of power inductors. Different arrangements of air gap in a magnetic circuit influence the parameters of an inductor. Understanding this dependence allows a design of more efficient inductors. In this paper, the influence of different air-gap arrangements on the distribution of the magnetic flux density, the value of saturation current, and the power losses is presented. The 3-D finite-element analyses and laboratory measurements were realized for the exemplary inductor made of grain-oriented steel and copper foil. Additionally, the main rules of the design of inductors with distributed air-gap arrangement are also given. [ABSTRACT FROM AUTHOR]

Premagnetization of inductors with a permanent magnet seems to be a constantly recurring subject for power magnetic designers. Perhaps because there is not much literature on this topic available, the common considerations about it focus on obvious problems of the use of permanent magnets in high-frequency magnetic fields. This paper discusses the main degradation mechanisms of permanent magnets in premagnetized inductors and how they can be calculated in applications. After a short introduction to magnetic materials this paper addresses the reliability concerns and discusses degradation effects and their calculations. The calculations of acceleration factors are shown, which are important for the calculation of the reliability based on mission profiles. [ABSTRACT FROM PUBLISHER]

In this paper, we present an analytical procedure to predict the ac resistance of litz-wire windings considering air gap fringing fields. For this purpose, an equivalent complex permeability model is derived for hexagonally packed wires. We show how the real as well as the imaginary parts of the complex permeability can be determined with the copper filling factor as a parameter. An analytical 2-D model is deduced to describe the air gap fringing fields of gapped inductors. Accordingly, the proximity losses of the litz-wire winding are determined correctly and the ac resistance of practical inductors can be predicted over a wide frequency range with high accuracy. This offers the opportunity to optimize such components. Finally, the influence of various parameters on the copper losses is investigated and verified by means of experimental data drawn from impedance measurements. [ABSTRACT FROM AUTHOR]

The saturated core fault current limiter (SFCL) is one of the most effective methods for limiting fault current. A permanent magnet (PM)-biased SFCL (PFCL) can reduce dc bias current and additional energy consumption. However, the thermal stability of NdFeB PMs in PFCL poses a major challenge. This paper proposes a novel hybrid-type SFCL (HSFCL) topology that can reduce this risk. In the HSFCL, a hybrid PM/dc coil is designed to saturate the core, and a fault-limiting reactor is used to guarantee fault-clipping performance. The new structure provides air-gap branches for the time-varying magnetic field produced by alternating current, which reduces the eddy current in the PMs and enhances their stability. Electromagnetic coupling is used to analyze the operating principles and characteristics of HSFCL. Finite-element analysis simulations were performed using Maxwell and compared with verification experiments, proving that HSFCL is efficient in fault clipping and PM reliability enhancement. [ABSTRACT FROM AUTHOR]

Magnetic vector potential (MVP) formulations are widely used in the electromagnetic (EM) field computation. For problems with both inductive and capacitive effects, existing full-wave MVP formulations are mostly nonuniquely solvable, and sophisticated preconditioners are indispensable when solving these resultant linear matrix equations. To find a stable formulation with a unique solution, it is important to incorporate the necessary physics equations and the gauge condition properly. Traditional Coulomb-gauged formulation using the penalty technique does not work for edge elements, since the divergence of the edge element basis function is zero within each element. In this paper, a novel MVP formulation with Coulomb gauge for full-wave Maxwell equations using edge elements is proposed in the frequency domain. Extensive numerical examples are computed to show that the proposed formulation is stable even for tiny frequencies, which is very useful in full-wave engineering EM field computation. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present an improved design of a wireless inductive sensor with novel compressive parts and its integration with a suitable mechanical device. The proposed system can be used as a seat occupancy detector with adjustable weight threshold. It consists of a sensor (inductor, steel springs, and ferrite plate), an antenna, and a mechanical device for transferring the scaled weight to the sensor. The sensor is designed in such a way that the weight applied to its surface causes the built-in springs to compression, and as a result, the reduction of the distance between the inductor and the ferrite plate, which in turn changes in the sensor’s inductance, and consequently the antenna-sensor resonant frequency, which is used as the electric output. The mechanical device, which serves as a weight converter, has also been developed. The prototype of the system is fabricated and experimentally tested in order to confirm its functionality and performance. A three-segment linear characteristic is obtained with the following sensitivities: 0.9 MHz/kg for the weights of 0–20 kg, 1.86 MHz/kg for the weights of 20–40 kg, and 0.19 MHz/kg for the weights of 40–50 kg. These results show that the developed system can detect the presence of weight and, therefore, can be used for seat occupancy detection in a vehicle safety restraint and airbag systems. It can also be used as the indicator in the airbag safety restraint systems when the occupant’s weight exceeds the defined weight threshold for the airbag activation. [ABSTRACT FROM PUBLISHER]

Microwave properties of a novel and functional composite inorganic materials based on barium hexaferrite (BaFe12O19) were measured and simulated. Three different inks with flake and sphere shape particles were developed and printed on the top of meander-shaped microwave inductor on alumina substrate. Several types of meandered inductors with a different number of turns were investigated for the verification of obtained results. The results show relative permeability values of 1.3, 2.2, and 1.5 for composite layers printed from the inks with flake shape at 41.5 wt.%, flake shape plus dodecyl benzene sulphonic acid (DBsa) at 44.4 wt.%, and sphere-like shape at 55.6 wt.% of BaFe12O19, respectively, at 3 GHz. Corresponding magnetic loss tangents were 0.015, 0.04, and 0.02. This novel inductor composite material can be applied for mobile telecommunication operations at 0.5 to 3 GHz frequency range. [ABSTRACT FROM AUTHOR]

Shunt reactors are important components for the development of UHV power systems since they compensate large capacitive currents generated by HV transmission lines over great distances. Shunt reactors can also limit over voltages resulting from load shedding operations or from a line-to-ground fault. With regard to construction, shunt reactors are designed in distributed gapped-core which has one winding and a core divided into several laminated magnetic steel disks separated by air-gap wedges. The Volume of the gap is in relation with reactive power (Q) of the reactor and maximum magnetic flux density (Bm) as well. After calculating the gap volume, the way for separating of the gap area (Ag) and length (\sum lg) is an important matter. It plays main role in reactor dimensions, used materials and power losses. In this paper a method based on minimizing the cost is presented for selecting the gap area and length by finding an optimum value for Ag/\sum lg ratio with constant volume constraint. [ABSTRACT FROM PUBLISHER]

This paper examines high-frequency losses of thick rectangular and round wire windings due to the fringing fields of an air-gap. It derives formulas for the losses and validates them numerically using the 2-D finite-element method (FEM). It also provides a procedure for including the effect of self and proximity fields in the loss calculations, using the principle of superposition and a one-dimensional model of self and proximity fields. The paper validates the latter procedure numerically, using a 2-D finite element model. [ABSTRACT FROM AUTHOR]

This paper considers high-frequency (200 kHz-1.0 MHz) losses in MnZn power ferrites and shows that none of the three well-known magnetic loss mechanisms (namely, hysteresis, classical eddy-current loss, and excess eddy-current loss) can account for the experimentally observed dependence of the loss on the frequency and flux density. In order to investigate the origin of this discrepancy, the electric field that is induced in the typical core when the material is driven at high frequencies and flux densities was estimated. The estimates show that these electric fields can be quite large. The paper presents experimental data on the electrical conductivity for such large electric fields, which shows a highly nonlinear behavior that can give rise to a modified eddy-current loss mechanism. By a simple curve fit to the nonlinear conductivity, the experimentally observed flux density dependence of the high-frequency loss, which previously could not be explained, can be reproduced by using this modified eddy-current loss mechanism. A modified ferrite structure can eliminate most of these extra losses by reducing the electric field generated at the grain boundaries due to high frequencies and flux densities. [ABSTRACT FROM AUTHOR]

The integration of voltage regulator on the chip substrate in system on chip can reduce interconnect resistive losses, facilitates real-time power management with control of the supply voltage, and requires to manufacture small inductors with high inductance density, power density, and efficiency with large current carrying capability. In this paper, we fabricated a strip-line on-chip inductor with separate conductive windings wrapped by boron-incorporated amorphous Co–Zr–Ta–B film. We examined its response of inductance and quality factor as a function of an applied dc current and its large current density capability. [ABSTRACT FROM PUBLISHER]