Saturation Induction Research Articles

Ni-Fe Alloys as Perspective Materials for Highly Efficient Magnetostatic Shielding

Magnetostatic shields, based on Ni-Fe alloys, were obtained via electrochemistry method with different thickness of partial magnetic layers. The experimental researches of the magnetic properties and magnetostatic shielding effectiveness of the single-layer and malty-layer cylindrical sample of the shields, based on the electrodeposited Ni80Fe20and Ni50Fe50alloy, are carried out. It has been shown that the shields of gradient type (200 μm Ni50Fe50+200 μm Ni80Fe20and 100 μm Ni50Fe50+300 μm Ni80Fe20), containing layers with different values of saturation induction (Bs), have a higher shielding efficiency than shields of symmetric type (400 μm Ni50Fe50and 400 μm Ni80Fe20). Maximum efficiency of magnetostatic shielding has been noted for 200 μm Ni50Fe50+ 200 μm Ni80Fe20sample. It opens wide prospects for practical application for protection of the microelectronics devices against permanent magnetic fields.

Tensile and torsional strain gauge based on Fe48Co32P14B6 metallic glass

Abstract We evaluate properties of the prototype of a strain gauge capable to discriminate different strain components: tension and torsion. It makes use of magnetoelastic effect in new Fe48Co32P14B6 metallic glass. As a sensing material, it surpasses characteristics of commercial Iron-Nickel Metglas® alloy: relative differential permeability of as quenched amorphous ribbon is of about 110000, the saturation induction Bs = 1.45 T, coercive field as low as 4 A/m, Curie temperature above 700 K, and significantly higher thermal stability. Different deformation components were determined through the analyses of the shape of hysteresis B-H loops. Fe-Co-P-B glass strain gauge can simultaneously detect as small tensile strains as 1.9 × 10−5 and less than 0.13 deg/cm of torsional distortions.

Strategies for achieving high‐level and stable production of toxic Streptomyces phospholipase D in Escherichia coli

AbstractBACKGROUNDPhospholipase D (PLD) has great potential in the pharmaceutical and food industries for manufacturing bioactive phospholipids. Overproduction of PLD in Escherichia coli is difficult due to its high cytotoxicity which causes plasmid instability, short‐term PLD synthesis, cell lysis and PLD leakage. To address this issue, integrated optimization of PLD production in upstream and downstream processing was performed.RESULTSEffective strategies in upstream processing include the use of plasmids containing the pSC101 par region in recA− E. coli, the use of moderately strong and tightly regulated promoter PBAD, optimization of codon usage and amino acid supplementation, maintaining the best cellular state by supplementing nutrition, and saturation induction at low temperature. Using these strategies, a large amount of PLD (1.2 × 105 U L−1, 81.5 mg L−1) was obtained in the batch culture and PLD synthesis lasted 9 h. Additionally, cell lysis did not occur –99% of the recombinant PLD remained in the periplasm. Ultimately, the PLD was purified 327‐fold by a four‐step downstream process comprising extraction with 10 mmol L−1 Ethylenediaminetetraacetic acid and 0.05% (w/v) sodium deoxycholate, ammonium sulfate precipitation, anion exchange and Ni2+‐affinity chromatography.CONCLUSIONThis study provides the basis for large‐scale production of PLD in E. coli. © 2018 Society of Chemical Industry

In-situ formation of Fe3O4 and ZrO2 coated Fe-based soft magnetic composites by hydrothermal method

In this paper, the soft magnetic composite was prepared using a powder metallurgy method with the Fe3O4 and ZrO2 co-coated iron powder which was synthesized though the in-situ hydrothermal method. Energy dispersive spectroscopy (EDS) coupled with X-ray photoelectron spectroscopy (XPS) revealed that the Fe3O4 and ZrO2 were uniformly coated on the surface of iron powders. The addition of ZrO2 in the coating effectively improves the properties of the soft magnetic composite. ZrO2 can further improve the insulating properties, and enhance the thermostability of the coating simultaneously which will lead to resistivity increase and eddy current loss decrease. By controlling the additive amount of zirconium cation and annealing temperature, high magnetic induction of 1.002 T (measured at 8000 A/m), relatively high permeability of 83 (measured at 100 kHz), and low total core loss of 255.2 W/kg (measured at 100 kHz and 50 mT) were achieved. The Fe@ZrO2&Fe3O4 SMCs show high electrical resistivity and saturation induction, which may be widely used in high speed electric motor, transformer, inductance and switching power supply.

Mechanical properties of strain annealed metal amorphous nanocomposite (MANC) soft magnetic material

Metal amorphous nanocomposites (MANCs) offer lower losses than silicon steels and higher saturation inductions than amorphous alloys. Their application in motors will require a detailed understanding of their mechanical properties. Co74.6Fe2.7Mn2.7Nb4Si2B14 was studied by nanoindentation and tensile testing to determine hardness, elongation, Young's modulus, ultimate tensile strength (UTS), and Poisson's ratio. Young's modulus was observed to increase with crystallization at 50 MPa, and then decrease when annealing under applied stress. Annealing at even higher stress resulted in no significant change in Young's modulus. This trend was replicated in nanohardness results. The UTS and elongation decrease with crystallization and show a large increase in standard deviation. Reduction in UTS and elongation has been attributed to embrittlement, as well as the high surface roughness of the ribbon material. Poisson's ratio remained relatively constant at 0.31–0.33 for all samples. X-ray diffraction (XRD) was performed on annealed samples, revealing fine nanocrystals. Profilometry indicates significant surface roughness, which contribute to reduction of UTS and elongation. Hardness, UTS, and elongation compare favorably to existing materials, but embrittlement of the material needs to be addressed to allow use in electric motor applications.

Optimal Design of High-Power Modular Multilevel Active Front-End Converter Using an Innovative Analytical Model

Optimal design and selection of arm inductances have been as a challenging subject in the field of modular multilevel converter (MMC). The average steady-state model is generally used as the analytical circuit model that neglects the switching frequency and harmonic values. Also, most of the researchers neglect the saturation effect of inductor core to simplify the analytical model. Contrary to the transformers, choosing the maximum flux density of inductance core is a sensitive issue, in order to design and minimize the inductors. Increasing the flux density reduces the inductor size, but getting close to the saturation region might alter the performance of the converter. This paper presents a systematic optimization approach to minimize high-power MMCs with saturable arm inductance considering technical, thermal, and manufacturing constraints. An accurate steady-state analytical model of MMC converter has been proposed and verified. A combination of converter circuit model and inductance electromagnetic model is employed to find the optimal arm inductances and capacitor values. The effect of nonideal inductance core on converter outputs has been investigated. A dimensioning model of inductor consisting of electromagnetic and thermal models is presented. To compute the optimal inductor size, a novel hybrid optimization loop is proposed including the analytical model of the converter and the inductor in which circuit, electromagnetic, and thermal properties are taken into consideration. In order to increase the accuracy of the dimensioning model, an internal verification loop is employed to verify and correct the analytical model using finite-element analysis. The proposed optimization loop aims to find the minimum inductor size considering technical and manufacturing constraints. Finally, the converter mass sensitivity of MMC converter versus some important constraints, such as temperature rise and capacitor ripple, has been investigated.

Ni-Fe Alloys as Perspective Materials for Highly Efficient Magnetostatic Shielding

Magnetostatic shields based on Ni-Fe alloys were obtained via electrochemistry method with different thickness of partial magnetic layers. The experimental researches of the magnetic properties and magnetostatic shielding effectiveness of the single-layer and malty-layer cylindrical sample of the shields based on the electrodeposited Ni80Fe20 and Ni50Fe50 alloy are carried out. It has been shown that shields of gradient type (200 μm Ni50Fe50+200 μm Ni80Fe20 and 100 μm Ni50Fe50+300 μm Ni80Fe20) containing layers with different values of saturation induction (Bs) have a higher shielding efficiency than shield of a symmetric type (400 μm Ni50Fe50 and 400 μm Ni80Fe20). Maximum efficiency of magnetostatic shielding has been noted for 200 μm Ni50Fe50+ 200 μm Ni80Fe20 sample. It opens wide prospects for practical application for protection of the microelectronics devices against permanent magnetic fields.

English

This work proposes NADP-ME activity as bio-indices for herbicidal sensitivity in Azolla pinnata R.Br. under 2,4-D toxicity. Azolla fronds were illuminated under saturated photosynthetic flux and bicarbonate induction. There was significant variation in the NADP-ME activity under light and dark conditions. This increased more when varying concentrations of 2,4-D were used for the up regulation of enzyme activity especially under illumination. There was evident modulation through activators (citrate and succinate) and inhibitors (pyruvate and oxaloacetate) under light and dark conditions at 2,4-D concentration. This occurs at the same time in overriding the herbicidal stress linked to the adjustment of the cellular redox of regulatory sites using dithiothreitol. This shows that Azolla can quench 2,4-D, which suggests NADP-ME as a biomarker through its sensitivity and mode of activities under xenobiotic contaminated soil. Key words: NADP-malic enzyme, aquatic fern, herbicide, modulators, malate.

Design of a Low-Stray Inductance Magnetic Switch for High Compression of the Pulse Width in a Magnetic Pulse Compressor

A magnetic pulse compressor (MPC) transfers energy via $C$ – $L$ – $C$ resonance. The pulse width of the MPC is determined by the saturation inductance of the magnetic switch (MS). When using the MS, the pulse width is limited due to the stray elements. To increase the pulse compression rate, the number of stray elements must be reduced. In this paper, we propose an optimum design for an MS having the lowest impedance of stray elements, along with its analysis and experimental verification. The proposed model is designed to have a reduced magnetic path length while retaining the same saturation inductances as that of a common MS; this is accomplished by using the relationship between the magnetic field path length and the number of inductor turns. The experimental results show that the proposed MS decreases the full width at half maximum by 18% and increases the rise rate by 69%. This result demonstrates that the proposed MS increases the pulse compression rate of the MPC by reducing impedance of stray elements in the system.

Fe-Zr-N films: Effect of nitrogen content and nitrogen-to-zirconium concentration ratio on saturation induction

Films FexZr9Ny (x = 86 ÷ 77, y = 5 ÷ 14, at.%) prepared by rf reactive magnetron sputtering were used to study the effect of nitrogen content and nitrogen-to-zirconium concentration ratio on their phase composition and saturation induction Bs. It was shown that the films containing 9 at.% Zr and characterized by the nitrogen-to-zirconium ratio ≥1 have the two-phase structure, which forms during deposition and comprises α-Fe(N) solid solution and ZrN nitride. The Bs dependence on the nitrogen content in α-Fe(N) solid solution was found to be linear.

Modeling and simulation of saturated double rotor induction machine

PurposeDouble rotor induction machine (DRIM) is a particular type of induction machine (IM) that has been introduced to improve the parameters of the conventional IM. The purpose of this study is to propose a dynamic model of the DRIM under saturated and unsaturated conditions by using the equations obtained in this paper. Also, skin and temperature effects are considered in this model.Design/methodology/approachFirst, the DRIM structure and its performance will be briefly reviewed. Then, to realize the DRIM model, the mathematical equations of the electrical and mechanical part of the DRIM will be presented by state equations in the q-d axis by using the Park transformation. In this paper, the magnetizing fluxes saturation is included in the DRIM model by considering the difference between the amplitudes of the unsaturated and saturated magnetizing fluxes. The skin and temperature effects are also considered in this model by correcting the rotor and stator resistances values during operation.FindingsTo evaluate the effects of the saturation and skin effects on DRIM performance and validate the model, the machine is simulated with/without consideration of saturation and skin effects by the proposed model. Then, the results, including torque, speed, stator and rotor currents, active and reactive power, efficiency, power factor and torque-speed characteristic, are compared. In addition, the performance of the DRIM has been investigated at different speed conditions and load variations. The proposed model is developed in Matlab/Simulink for the sake of validation.Originality/valueThis paper presents an understandable model of DRIM with and without saturation, which can be used to analyze the steady-state and transient behavior of the motor in different situations.

Grain growth effects on magnetic properties of Ni0.6Zn0.4Fe2O4 material prepared using mechanically alloyed nanoparticles

Abstract The effect of grain growth via sintering temperature on some magnetic properties is reported in this research. Ni0.6Zn0.4Fe2O4 nanoparticles were mechanically alloyed for 6 h and the sintering process starting from 600 to 1200 °C with 25 °C increment with only one sample subjected to all sintering scheme. The resulting change in the material was observed after each sintering. Single phase has been formed at 600 °C and above and the intensity peaks increased with sintering temperature as well as crystallinity increment. The morphological studies showed grain size increment as the sintering temperature increased. Moreover, the density increased while the porosity decreased with increasing sintering temperature. The saturation induction, Bs increased with the increased of grain size. On the other hand, the coercivity-vs-grain size plot reveals the critical single-domain-to-multidomain grain size to be about ∼400 nm. The initial permeability, μi value was increased with grain size enhancement. The microstructural grain growth, as exposed for the first time by this research, is shown as a process of multiple activation energy barriers.

Microstructure and magnetic properties of iron–cobalt-based alloys processed by metal injection moulding

Abstract Fe–Co-based soft magnetic alloys with excellent magnetic properties were prepared by metal injection moulding and hot isostatic pressing. The effect of processing parameters on microstructure and magnetic properties of the alloy were investigated. Good magnetic performance of Fe-50 %Co alloy with a maximum permeability of 9550, saturation induction of 2.42 T, and coercive force of 68.14 A m–1 was achieved. Hot isostatic pressing processing resulted in a near-full density and the achieved saturation induction exceeded the reported value (1.99 to 2.26 T) of Fe-50 %Co produced by metal injection moulding.

Low-firing Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ceramics modified with V2O5–ZnO–B2O3 glass addition for microwave device application

A novel V2O5–ZnO–B2O3 (VZB) glass was introduced into the Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 (LiZnTiMn) ferrites for advancing low-temperature cofired ceramics technology and fabricating microwave ferrite devices by the multilayer process. The results reveal that the addition of VZB glass is an effective way to improve the densification, microstructure, and ferrimagnetic properties of the LiZnTiMn ferrites. The relationship among dopant amount, sintering mechanism, and structural distribution characteristic was established, tailoring the foundation of ferrimagnetic performance of low-temperature fired LiZnTiMn composites. The resulting VZB glass as flux promotes the microstructural uniformity and compactness and also provides the optimized physical properties of low-temperature sintered LiZnTiMn composites. An appropriate amount of VZB glass (~0.5 wt%) could enhance the saturation magnetization (from 52.2 to 72.3 emu/g) and remanence ratio of saturation induction (from 0.76 to 0.85) and reduce the coercivity of magnetic induction intensity (from 685 to 199 A/m) of the ferrite composites sintered at ~900 °C. Moreover, the ferromagnetic resonance linewidth of LiZnTiMn composites doped with 0.5 wt% VZB glass decreased from 860 to 195 Oe because of the combined effect of good uniformity and low porosity. Thus, with a low-temperature sintering process, the VZB glass could be a promising additive for achieving low-loss LiZnTiMn ferrite used in microwave devices.

Adaptive dynamic voltage transitioning in switch mode DC–DC power converters

Higher transistor density in modern processors leads to an increase in computing power, which results in higher power consumption. To combat this, system-level power saving features like dynamic voltage transitions (DVTs) are introduced where the voltage required by the processor is varied according to computational load. In commercially available systems, the slew rate of the voltage transition is limited, which has the negative effect of increasing computational latency to ensure safe operation of the switch mode power converter. This study addresses the limitations of the existing techniques by introducing an adaptive DVT, which enables finer granularity of the operating voltage levels and promotes greater power savings. The switching surface-based analysis is performed to derive the conditions for (near) optimal voltage transitions constrained by inductor saturation limits. The results of an experimental prototype achieving the fastest safe transition response are shown to correlate well with the analysis across a wide range of DVT conditions.

Glass formation and soft magnetic properties of novel Fe-rich Fe-B-Ti-Zr bulk metallic glasses

Composition design is an important issue concerning the development of bulk metallic glasses (BMGs), especially applicable Fe-based bulk metallic glasses (BMGs). In this work, new quaternary Fe77B18TixZr5-x (x = 1–4) BMGs were developed by promoting metastable transformation in solidification process. Their glass formation, thermal and soft magnetic properties have been investigated. Thermal analysis proves that the combined additions of Ti and Zr in the alloys have significant advantage in improving the glass forming ability (GFA). However, the alloy with best GFA does not show the optimal thermal performance, and such inconformity in MGs was usually neglected previously. We further explain the origin of the improvement in GFA and the inconformity between GFA and thermal properties by investigating the phase evolution of the crystalline alloys. Proper combined additions of Ti and Zr can promote the precipitation of metastable Fe23B6 phase, which is advantageous to GFA as the diverse crystallization pathways reflect different crystallization resistances in solidification. Owing to the high Fe content, the amorphous ribbons exhibit high saturation induction of over 1.3 T.

Multiparameter method of surface hardening quality testing

Measurements of the magnetic characteristics (coercive force, residual induction, induction of saturation) of objects that had different thicknesses of the hardened layer were made. The influence of an unstressed core on the measurement results, as well as the depth of the strengthened layer on the shape of the hysteresis loop, is investigated. The conclusion is made that it is possible to estimate the properties of a hardened layer by means of a single measurement with the help of the hardware-software system DIUS-1.15M

Development of a 0.6-MV Ultracompact Magnetic Core Pulsed Transformer for High-Power Applications

The generation of high-power electromagnetic waves is one of the major applications in the field of high-intensity pulsed power. The conventional structure of a pulsed power generator contains a primary energy source and a load separated by a power-amplification system. The latter performs time compression of the slow input energy pulse and delivers a high-intensity power output to the load. Usually, either a Marx generator or a Tesla transformer is used as a power amplifier. In the present case, a system termed “module oscillant utilisant une nouvelle architecture” (MOUNA) uses an innovative and very compact resonant pulsed transformer to drive a dipole antenna. This paper describes the ultracompact multiprimary winding pulsed transformer developed in common by the Universite de Pau and Hi Pulse Company that can generate voltage pulses of up to 0.6 MV, with a rise time of less than 270 ns. The transformer design has four primary windings, with two secondary windings in parallel, and a Metglas 2605SA1 amorphous iron magnetic core with an innovative biconic geometry used to optimize the leakage inductance. The overall unit has a weight of 6 kg and a volume of only 3.4 L, and this paper presents in detail its design procedure, with each of the main characteristics being separately analyzed. In particular, simple but accurate analytical calculations of both the leakage inductance and the stray capacitance between the primary and secondary windings are presented and successfully compared with CST-based results. Phenomena such as the core losses and saturation induction are also analyzed. The resonant power-amplifier output characteristics are experimentally studied when attached to a compact capacitive load, coupled to a capacitive voltage probe developed jointly with Loughborough University. Finally, an LTspice-based model of the power amplifier is introduced and its predictions are compared with results obtained from a thorough experimental study.

Design and implementation of a MRAS sliding mode observer for the inverse of the rotor time constant of the induction motor

The paper presents an estimator for the inverse of the rotor time constant of the induction motor. Estimation is done using a sliding mode observer under the assumption that the stationary frame fluxes are known. With measured voltages, currents, and with known fluxes and speed, the paper develops an MRAS-type sliding mode observer. This works well under ideal conditions; however, if the speed is inaccurate or if the magnetising inductance saturates, the accuracy suffers. The paper develops a model for the saturated induction motor and attempts to also estimate the saturation level. In the second part, an observer with only a single set of feedback terms is developed. This is transformed into a sensorless observer by feeding it with a speed estimate (assumed inaccurate). The error in the estimated rotor time constant can be reduced by operating the motor drive with a low ratio of id to iq.

Design and implementation of a MRAS sliding mode observer for the inverse of the rotor time constant of the induction motor

The paper presents an estimator for the inverse of the rotor time constant of the induction motor. Estimation is done using a sliding mode observer under the assumption that the stationary frame fluxes are known. With measured voltages, currents, and with known fluxes and speed, the paper develops an MRAS-type sliding mode observer. This works well under ideal conditions; however, if the speed is inaccurate or if the magnetising inductance saturates, the accuracy suffers. The paper develops a model for the saturated induction motor and attempts to also estimate the saturation level. In the second part, an observer with only a single set of feedback terms is developed. This is transformed into a sensorless observer by feeding it with a speed estimate (assumed inaccurate). The error in the estimated rotor time constant can be reduced by operating the motor drive with a low ratio of id to iq.