Saturation Induction Research Articles

Non-Linear Inductors Characterization in Real Operating Conditions for Power Density Optimization in SMPS

The exploitation of power inductors outside their linear region in switching converters can be achieved by raising the current until a decrease in the inductance can be noticed. This allows using a smaller magnetic core, increasing the power density of the converter. On the other hand, a detailed description of the magnetization curve including the temperature is required. Since this information is often not included in the inductor’s datasheets, this paper shows how to identify the behavior of an inductor when it is operated up to saturation and its temperature rises. In order to characterize the inductor in real operating conditions, a dedicated measurement rig was developed. It consists of a switching converter that encompasses the inductor under test and is controlled by a virtual instrument developed in LabVIEW. The characterization system was tested by retrieving the inductance and the magnetization curves vs. current for two commercial inductors at core temperatures up to 105 °C. The magnetic core was then characterized by the saturation current vs. inductance, obtaining an expression for the whole family of inductors sharing the same core. Finally, we experimentally analyzed the thermal transient of the inductors in operating conditions, confirming the fundamental role of the temperature in changing the current profiles and the core saturation condition.

Effects of Bi2O3-V2O5 mixture on microstructure and magnetic properties for Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrites sintered at low temperatures

In this study, Bi2O3-V2O5 (BV) mixture was introduced to serve as a kind of sintering aid to assist the preparation of LiZn ferrites. The Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrites were successfully synthesized at relatively low temperatures, and all the samples exhibited a pure spinel phase. Meanwhile, the grain growth was significantly promoted, and the average grain size was elevated from 0.92 to 6.58 µm when the addition amount of BV mixture increased from 0.0 to 0.18 wt. %. In regard to the magnetic properties, the saturation induction (Bs) value could reach as high as 319 mT, and the coercivity (Hc) and ferromagnetic resonance linewidth (ΔH) decreased to 153 A/m and 182 Oe, respectively. It is worth noting that the proper addition amount is a key factor for enhancing the properties of ferrites, insufficient or excess BV mixture will deteriorate the properties. Therefore, it is expected that BV mixture can be employed as an effective sintering aid, which will improve the properties of ferrites and promote the development of low temperature co-fired ceramics (LTCC) technology.

A High Step-Up Switched Z-Source Converter (HS-SZC) with Minimal Components Count for Enhancing Voltage Gain

Some applications such as fuel cells or photovoltaic panels offer low output voltage, and it is essential to boost this voltage before connecting to the grid through an inverter. The Z-network converter can be used for the DC-DC conversion to enhance the output voltage of renewable energy sources. However, boosting capabilities of traditional Z-network boost converters are limited, and the utilization of higher parts count makes it bulky and expensive. In this paper, an efficient, high step-up, switched Z-source DC-DC boost converter (HS-SZC) is presented, which offers a higher boost factor at a smaller duty ratio and avoids the instability due to the saturation of inductors. In the proposed converter, the higher voltage gain is achieved by using one inductor and switch at the back end of the conventional Z-source DC-DC converter (ZSC). The idea is to utilize the output capacitor for filtering and charging and discharging loops. Moreover, the proposed converter offers a wider range of load capacity, thus minimizing the power losses and enhancing efficiency. This study simplifies the structure of conventional Z-source converters through the deployment of fewer components, and hence making it more cost-effective and highly efficient, compared to other DC-DC boost converters. Furthermore, a comparison based on the boosting capability and number of components is provided, and the performance of the proposed design is analyzed with non-ideal elements. Finally, simulation and experimental studies are carried out to evaluate and validate the performance of the proposed converter.

Development of high Bs Fe–Ni-based metal amorphous nanocomposite by optimization of glass-forming ability

Thermocalc simulations identified compositions with good glass-forming ability (GFA) by locating minima in liquidus temperature, and solidification range in (Fe70 Ni30)x(B-Si-Nb)100-x alloys with x = 82% and x = 85%, increased compared to previously developed x = 80% alloys. 3 compositions in the x = 82% system and 1 in the x = 85% system were successfully cast as amorphous magnetic ribbon. Magnetic properties of as-cast alloys showed improvements in Curie temperature and saturation induction, especially for the 85% alloy. Crystallization behavior in the 85% alloy was determined to occur as a 2-step process. Annealing studies showed (Fe70Ni30)82Nb2Si0B16 and (Fe70Ni30)82Nb3Si0B15 alloys to exhibit low coercivity and high Bs with annealing. TEM results show significant crystallization in as-cast ribbon. The (Fe70Ni30)85Nb0.5Si0B14.5 alloy as-cast has small, uniformly distributed grains, allowing a useful nanocrystalline alloy to be produced as cast. Finally, the parameter ΔTxg, the temperature range in which the material can be thermomechanically processed, was in the range of 12–23 °C.

Sensorless PMSM Drive Inductance Estimation Based on a Data-Driven Approach

In the permanent magnet synchronous motor (PMSM) sensorless drive method, motor inductance is a decisive parameter for rotor position estimation. Due to core magnetic saturation, the motor current easily invokes inductance variation and degrades rotor position estimation accuracy. For a constant load torque, saturated inductance and inductance error in the sensorless drive method are constant. Inductance error results in constant rotor position estimation error and minor degradations, such as less optimal torque current, but no speed estimation error. For a periodic load torque, the inductance parameter error periodically fluctuates and, as a result, the position estimation error and speed error also periodically fluctuate. Periodic speed error makes speed regulation and load torque compensation especially difficult. This paper presents an inductance parameter estimator based on polynomial neural network (PNN) machine learning for PMSM sensorless drive with a period load torque compensator. By applying an inductance estimator, we also proposed a magnetic saturation compensation method to minimize periodic speed fluctuation. Simulation and experiments were conducted to validate the proposed method by confirming improved position and speed estimation accuracy and reduced system vibration against periodic load torque.

Microstructural evolution and magnetic properties of pressureless-sintered nanosized iron prepared by a facile combustion-based route

High-activity iron nanopowders were prepared through a facile combustion-based route, combining solution combustion synthesis and hydrogen reduction. The as-synthesized iron nanopowders were densified by pressureless sintering. The densification behavior, microstructure, mechanical properties and magnetic properties of the iron bulk sintered at different temperatures were studied in detail. At a low sintering temperature of 700 °C, the relative density of the sintered iron reaches 97.3%, because the iron nanopowders exhibit a low sintering activation energy of 123 KJ/mol. The iron bulk sintered at 700 °C exhibits relatively regular equiaxed grains with an average grain size of 0.45 μm, and has a maximum tensile strength of 510.1 MPa, a high microhardness of 201.9 HV, and a saturation induction of 1.75 T. As the sintering temperature increases, the grain size and magnetic properties of the sintered iron enhance, while the mechanical strength decreases. For the sintered iron prepared at 1300 °C with the average grain size ~ 80.9 μm, the saturation induction value reaches 1.78 T and the tensile strength is 334.9 MPa.

Properties of intragranular-oxide-strengthened Fe alloys fabricated by a versatile facile and scalable route

The Fe-Y2O3 alloys with the evenly dispersed Y2O3 nanoparticles into the grain interior have been successfully fabricated by a versatile facile and scalable route. Firstly, Fe-Y2O3 nanocomposites were synthesized through solution combustion synthesis and hydrogen reduction. Subsequently, the Fe-Y2O3 alloys were prepared by pressureless sintering of the as-synthesized Fe-Y2O3 nanocomposites. The microstructure, mechanical and magnetic properties of the Fe-Y2O3 alloys sintered at different temperatures were studied in detail. The Fe-Y2O3 alloy sintered at 900 °C with an average grain size of 0.96 μm and the uniformly dispersed Y2O3 nanoparticles size of less than 100 nm has the tensile strength of 520.6 MPa and the saturation induction of 1.726 T. With the sintering temperature increasing, the grain size, saturation induction and elongation of the Fe-Y2O3 alloy increase, while the tensile strength, microhardness and and coercive force decrease. The saturation induction value of Fe-Y2O3 alloy sintered at 1300 °C reaches 1.742 T, the average grain size reaches 62.1 μm and the tensile strength is 353.5 MPa.

Influence of Cu Content on Structure, Thermal Stability and Magnetic Properties in Fe72-xNi8Nb4CuxSi2B14 Alloys.

The effect of substitution of Fe by Cu on the crystal structure and magnetic properties of Fe72−xNi8Nb4CuxSi2B14 alloys (x = 0.6, 1.1, 1.6 at.%) in the form of ribbons was investigated. The chemical composition of the materials was established on the basis of the calculated minima of thermodynamic parameters: Gibbs free energy of amorphous phase formation ΔGamorph (minimum at 0.6 at.% of Cu) and Gibbs free energy of mixing ΔGmix (minimum at 1.6 at.% of Cu). The characteristic crystallization temperatures Tx1onset and Tx1 of the alpha-iron phase together with the activation energy Ea for the as-spun samples were determined by differential scanning calorimetry (DSC) with a heating rate of 10–100 °C/min. In order to determine the optimal soft magnetic properties, the wound cores were subjected to a controlled isothermal annealing process in the temperature range of 340–640 °C for 20 min. Coercivity Hc, saturation induction Bs and core power losses at B = 1 T and frequency f = 50 Hz P10/50 were determined for all samples. Moreover, for the samples with the lowest Hc and P10/50, the magnetic losses were determined in a wider frequency range 50 Hz–400 kHz. The real and imaginary parts of the magnetic permeability µ′, µ″ along with the cut-off frequency were determined for the samples annealed at 360, 460, and 560 °C. The best soft magnetic properties (i.e., the lowest value of Hc and P10/50) were observed for samples annealed at 460 °C, with Hc = 4.88–5.69 A/m, Bs = 1.18–1.24 T, P10/50 = 0.072–0.084 W/kg, µ′ = 8350–10,630 and cutoff frequency at 8–9.3 × 104 Hz. The structural study of as-spun and annealed ribbons was carried out using X-ray diffraction (XRD) and a transmission electron microscope (TEM).

Enhanced magnetic properties of low-temperature sintered LiZnTiMn ferrites with Bi2O3–NiO additive

Bi2O3 significantly influences the grain growth of LiZn ferrite ceramics, whereas NiO enhances the performance of LiZn ferrites. Herein, we present the influence of Bi2O3–NiO addition on solid-state synthesis, microstructure, density and ferromagnetic performance of LiZnTiMn ferrites at low temperatures (< 960 °C). The results reveal that an optimal amount of Bi2O3–NiO endows excellent properties to LiZnTiMn ferrites after sintering at 950 °C. X-ray diffraction and scanning electron microscopy demonstrate superior densification and grain growth due to the incorporation of Bi2O3–NiO. Moreover, the corresponding ferromagnetic properties, such as saturation induction (Bs), remanence square ratio, coercivity (Hc), ferromagnetic resonance line width (ΔH) and Ms, are also investigated to demonstrate variation. At being sintered at 950 °C with Bi2O3–NiO content of 0.25 wt%, the name rendered a Bs value of 334 mT, Br/Bs ratio of 0.877, Hc of 130 Oe and ΔH of 177 Oe. These results confirm that the presence of Bi2O3–NiO lowers the firing temperature of LiZnTiMn ferrites and endows superior magnetic properties.

Suppression of ferroresonance using passive memristor emulator

Power system inherently consists of capacitance and inductance in its components. Equipment with saturable inductance and circuit capacitance provides circumstances of generating ferroresonance, resulting in overvoltage and overcurrent in the connected system. The effects of ferroresonance result in insulation failure and hence damage to the equipment is unavoidable. Though many devices are proposed for mitigating such circumstances, a promising technology of using memristors may provide better performance than others in the future. A memristor emulator using the N-channel JFET J310 is used in this work. Unlike other electronic components that replicate memristor properties, the chosen memristor emulator is a passive device since it does not need any external power supply. Simulation and experimental results verify the design of a memristor emulator and the characteristics of an ideal memristor. Experimental results prove that the memristor emulator can suppress the fundamental ferroresonance induced in a prototype single phase transformer. The results of the harmonic analysis also validate the memristor performance against the conventional technique.

A Duality Based Quasi-Steady-State Model of Three-Phase Five-Limb Sen Transformer

A three-phase five-limb transformer is a potential application form of the Sen Transformer (ST), especially for the scenarios with significantly unbalanced load conditions. This paper proposes a quasi-steady-state model of three-phase five-limb ST (TPFLST) based on duality. Firstly, an equivalent circuit model that takes into account the eddy current effect and the coupling effect involving the magnetic circuit can be derived according to the equivalent magnetic circuit of the TPFLST. The iron-core of the TPFLST may be represented by the parallel combination of the resistances reflecting the power loss of the iron-core and the saturable inductances considering the ferromagnetic hysteresis in virtue of the principle of duality. Subsequently, an electric circuit model of the voltage and current of each winding for the TPFLST is able to be accomplished on the basis of the electrical connection between the TPFLST and the external systems in accordance with Kirchhoff’s voltage and current law. Consequently, a quasi-steady-state model of the TPFLST which considers the coupling relationship involving the magnetic and electric circuits can be formed by combining the equivalent circuit model and the electric circuit model. With the help of MATLAB, the effectiveness of the proposed model may be verified by comparing the results about power flow control including power, voltage, and current with the ones from the existing literature. Furthermore, the TPFLST is found to be better-suited for the unbalanced load condition according to a comparison among the unbalanced degrees of output currents for the STs with different core structures under unbalanced load conditions.

Получение эффективных нефтесорбентов для очистки вод на основе отходов химической промышленности

It was proposed new technologies for producing effective oil sorbents based on chemical industry waste. It was shown the possibility of using PET waste as a binder in the produc- tion of oil sorbents with specific properties (hydrophobicity, oleophilicity, magnetic proper- ties) using thermally expanded and oxidized graphite (TEG and OG) and ferritized iron- containing galvanic sludge (FGS). The presence of iron ions in the galvanic sludge allows one to obtain magnetite and ferrites during ferritization, which leads to the appearance of magnetic properties in FGS, established using a vibration magnetometer, the saturation induction was ~ 0.02 T. Electroplating sludge was carried out at t ≈ 1000 oC and τ = 1.5 hr with preliminary mechanical activation. The physicomechanical, chemical, and sorption properties of the obtained oil sorbents (bulk density, abrasion, grindability, particle size distribution, oil capacity, moisture capacity, wettability, buoyancy, specific surface area, chemical composition, adsorption capacity of materials under static and dynamic conditions) are studied. It was found that sorption ma- terials have 100% buoyancy, are highly active in cleaning water surface from films of oil products with different thicknesses (1–5 mm). It was shown that sorption capacity increases with increasing film thickness and reaches a maximum value at a thickness of 3 mm. The cleaning efficiency is 99.0%. It has been established that the sorption capacity of the sorption material (SM) depends on the nature of oil products, its viscosity, solubility and initial concentration in water. It is proved that the processes of sorption of oil products proceed by the physical mechanism, which can be represented as the oleophilic interaction of particles of the Sorption material and oil products, which is confirmed by the type of sorption isotherms, which are type II and IV according to the BDT theory and type L according to the Hills classification char- acteristic of polymolecular adsorption. The obtained adsorption isotherms were processed in the framework of the Langmuir and Dubinin – Radushkevich models, and the constants of the adsorption equations were calculated.

Analysis of the influence of inductor saturation on the level of electromagnetic interference of DC/DC-converters

The results of the study on the effect of the design parameters of a nonlinear inductor on the level of electromagnetic interference generated by DC/DC converters are presented. The paper proposes models designed for the LTspice XVII environment, which allow investigating conducted interference spectra, efficiency and output voltage ripple of the converter using a nonlinear inductor model. The simulation results showed that the level of conducted interference is affected by the volume and material of the inductor core, as well as the presence of an air gap in the core. The results of measurements of conducted interference spectra at different values of the cross-sectional area of the inductor core of the DC/DC converter are presented. With the nominal cross-sectional area of the core, calculated taking into account converter output power, the study of the relationship between the level of conducted interference and the width of air gap in the inductor core is carried out. In the course of studies, using the Chan model, the influence of inductor core material on the level of interference generated by the DC/DC converter is analyzed. Analysis of the influence of the width of the air gap in the inductor core on the level of conducted interference is carried out. It is shown that air gap width should be selected taking into account inductor core material. Simulation results for a number of commonly used materials made it possible to determine the most effective one in terms of generated interference.The results obtained in the analysis of switching voltage converter operation, taking into account inductor nonlinearity, allow us to formulate recommendations to reduce the level of generated conducted interference by 4.5 to 6 dB due to the correct choice of inductor material and design parameters

Investigation of the processes of the formation of a nonequilibrium phase-structural state in FeTiB films obtained by magnetron sputtering

The main trends of modern developing magnetic microelectronics are miniaturization and speed, while ensuring efficient operation in the MHz and GHz frequency ranges of magnetic fields. Developing new magnetic materials featured by properties that ensure the implementation of these trends is the key fundamental and applied problem of materials science. In this regard, Fe-Me-X nanocrystalline soft magnetic alloys (Me is one of the metals from Group IVb of the Periodic Table, X is one of the N, C, O, B light elements) obtained in the form of films are of interest. As shown earlier by the authors of this article on Fe-Zr-N films, such films featuring by the Fe/MeX two-phase structure can provide a combination of high saturation induction (Bs), low coercive force (Hc), high hardness, and thermal stability of the structure. The films were produced by magnetron sputtering. The data obtained and published by the authors on the Fe–Ti–B films earlier indicate great prospects for their application in modern microelectronics. There are no any other published results of FeTiB film studies in the context of microelectronics applications. In this paper, we continue the studies of FeTiB films started earlier to identify the chemical and phase composition providing the level of properties required for film application in microelectronics. Nanocrystalline films containing 0 to 14.3 at.% Ti and 0 to 28.9 at.% B were obtained by DC magnetron sputtering. The phase-structural state of the films was studied by X-ray diffraction and transmission electron microscopy. All films are divided into 3 groups according to phase composition: single-phase (supersaturated solid solution of Ti in α-Fe), two-phase (α-Fe(Ti)/α-Ti, α-Fe(Ti)/TiB2, α-Fe (Ti)/FeTi, α-Fe(Ti)/Fe2B) and XRD amorphous. It is shown that XRD amorphous films feature by a mixed structure represented by a solid solution of α-Fe(Ti) with a grain size between 0.7 and 2 nm and an amorphous phase. A reasonable assumption is made on the amorphous phase enrichment by boron. A quantitative assessment of the α-Fe(Ti) phase grain size and its dependence on the chemical and phase composition of the films is given. The mechanisms of solid solution and dispersion hardening determine the grain size of this phase.

A Sensorless Current Balance Control Method for Interleaved Boost Converters Based on Output Voltage Ripple

In this article, a sensorless current balance control method for a multiple-phase interleaved boost converter is proposed. Balanced current can help an interleaved boost converter prevent imbalanced heat distribution and inductor saturation as well as improving the output voltage performance and overall system efficiency. This article analyzes the relationship equations between the periodic output voltage ripple and the phase current balance status. In the proposed method, the current sensor is eliminated, and only one voltage sensor on the output capacitor side is needed to monitor the output voltage information. The proposed sensorless current control method estimates the phase current distribution status according to the periodic output voltage peak ripple value and adjusts the phase current distribution status by changing the gate drive signal duty cycle of each phase MOSFET. To validate the proposed method, a PSIM simulation model and a two-phase interleaved boost converter test bench are set up, and the experiment waveforms verify the effectiveness of the proposed method.

Effect of Magnetic Field Annealing on Magnetic Properties of Iron–Gallium Alloys

The concentration dependence of magnetic properties of iron alloys with 3–25% of gallium is studied. It was shown that the saturation induction monotonically decreases with increasing gallium content, while the coercivity exhibits a step increase with a step from 85 to 135 A/m between 12 and 15 at % Ga. The effect of magnetic field annealing (MFA) on the behavior of the residual induction and coercive force in alloy samples containing from 3 to 18 at % Ga is studied. As a result of MFA, magnetic anisotropy is induced in the alloy: magnetic hysteresis loops become narrower, the residual induction increases, and the coercivity decreases. The MFA efficiency reaches a maximum at a Ga content of 15–18 at %. The features of the structure state of iron–gallium alloys and their role in the formation of magnetic properties during annealing in a dc magnetic field are discussed.

Influence of fibres diameter on the AC and DC magnetic characteristics of Fe/Fe3O4 fibres based soft magnetic composites

Fibres-based soft magnetic composites (FSMCs) have been prepared by using Fe fibres of different diameters (65, 125, 250 and 500 μm). The Fe fibres were coated with a 3 μm thick layer of Fe3O4 via the blackening process and subsequently compacted at 700 MPa. The X-ray diffraction analysis (XRD) was used to prove the formation of the Fe3O4 coating on the surface of the fibres. The thickness and the uniformity of the coating were analysed via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The DC measurements performed on the composite cores revealed that the saturation induction increase from 1.36 to 1.68 T, the maximum relative permeability increase from 550 to 940, and the coercive field decrease from 796 to 454 A/m as the fibre's diameter increase from 65 to 500 μm. By using thinner fibres (65 and 125 μm), composites with low losses and stable initial relative permeability, in the frequency range 50 Hz–10 kHz, can be obtained. To distinguish between different types of losses dissipated by our compacts, and the influence of the fibre's diameter on the different components of the total losses, a numerical model for loss separation is proposed. The comparative evolution of the AC magnetic characteristics of the FSMCs and powder-based SMCs is presented. According to the presented results, this new type of composites can be successfully used to prepare magnetic cores designated to work in the medium to high-frequency range.

Soft magnetic cobalt based amorphous alloys with low saturation induction

The influence of the concentration of alloying components on thermal stability, magnetic and electrical properties of amorphous alloys of Co73-66Fe4,6-3Cr0-9(B,Si)22-29 system was studied by methods of differential scanning calorimetry, XRD, resistometry and magnetometry. The crystallization of several alloys with advanced magnetic characteristics was studied. At continuous heating of the ribbons, either primary or eutectic crystallization was observed depending on the chemical composition of these alloys. Certain tendencies in the anomalous behavior of temperature dependence of electrical resistance of ribbons were revealed. By increasing chromium and metalloids concentrations, we obtained the alloys with relatively low saturation induction and large difference between the Curie temperature and the temperature of crystallization onset. The heat treatment regimes to obtain the best magnetic properties of these alloys were found. Prospective applications of Co73-66Fe4,6-3Cr0-9(B,Si)22-29 amorphous ribbons for fabrication of high sensitive sensors of magnetic field were discussed.

High-intensity pulsed ion beam treatment of amorphous iron-based metal alloy

The results of intense pulsed ion beam (IPIB) treatment of the soft magnetic amorphous alloy of a FINEMET-type are presented. Foil produced from the alloy was irradiated with short (about 100 ns) pulses of carbon ions and protons with energy of up to 300 keV and an energy density of up to 7 J/cm2. X-ray diffraction, Mössbauer spectroscopy and magnetic measurements were used to investigate structural and magnetic properties of irradiated foils. It is shown that the foil remains intact after the treatment, and the crystal structure still amorphous. Spontaneous magnetization vector is found to lie almost along perpendicular to the foil plane after irradiation, whereas for the initial amorphous foil it belongs to the plane. The magnetic properties of the foil undergo changes: the coercive force decreases, the saturation induction increases slightly, and the magnetization curve has shallower slope.

Effect of Cu2+ on structural, elastic and magnetic properties of nanostructured Mn–Zn ferrite prepared by a sol-gel auto-combustion method

The effect of Cu2+ substitution on the structural, elastic and magnetic properties of Mn0·50Zn0.50-xCuxFe2O4 (x = 0.00–0.25 and x changes at a step of 0.05) has been investigated. The compositions were made utilizing the Sol-Gel auto-ignition procedure and the X-ray diffraction (XRD) analysis confirmed the purity of the phase. Decreasing trends have been observed in the lattice constant, bulk density and Poisson's ratio but average grain size, theoretical density and porosity increases with the increasing concentration of Cu2+. Nano metric crystallite sizes have been estimated from FWHM of the X-ray diffraction peaks. Cation distribution in the present study was assessed by the XRD data. Site occupancy of cations helps to understand the variation in magnetic properties and also explains the change taking place in saturation induction, remanence induction and coercivity. The initial permeability increases with the increasing Cu2+ concentration up to x = 0.20 and above this x value it decreases. Observed variations of initial permeability have been clarified based on the increment of average grain size, which also has been conformed from optical micrographs. Saturation induction, coercivity, remanance, and squareness ratio have been considered as a component of Cu2+ content from theB−H loops of the compositions. Possible explanations for the perceived structural, elastic and magnetic behavior with Cu2+ substitutions are discussed.