Ferromagnetic Core Research Articles

Development of a Multiturn Linear Variable Reluctance Resolver With Integrated Ferromagnetic Core

Development of a Multiturn Linear Variable Reluctance Resolver With Integrated Ferromagnetic Core

Modeling the Influence of Thermal Phenomena in Inductors and Capacitors on the Characteristics of the SEPIC Converter

The paper presents the results of measurements and calculations of the SEPIC converter characteristics, taking into account thermal phenomena in semiconductor devices and passive elements. Compact electrothermal models of the MOSFET transistor, diode, capacitor, and inductor are proposed. Parasitic phenomena are also included in these models. The form of the developed models and the method of determining the values of their parameters are presented. The correctness of the formulated models was verified experimentally. Calculations and measurements of the characteristics of SEPIC converters containing inductors with ferromagnetic cores made of different materials were carried out. The obtained results of the investigations are discussed, and the range of applicability of the formulated models is described. It was shown that, at the considered operating conditions at an ambient temperature equal to 22 °C, the temperature of capacitors can exceed 40 °C, whereas the temperatures of inductors can even reach 50 °C.

Development of calibration samples made of steel 45 and 09G2S for eddy current structuroscope by carburizing

The paper describes the process of carburizing and hardening of 45 and 09G2S steels for the production of samples for the development of a technique for eddy current testing of the quality and thickness of hardened layers on ferromagnetic cores. Structural analysis of samples in the initial state, in the hardened state, as well as after carburizing and hardening was carried out. As a result of metallographic studies it was obtained that the depth of the cemented layer of steel 45 was equal to 250 microns, and in case of steel 09G2C it is in the range of 550-800 microns.

Role of the magnetic layer interface, roughness, and thickness in the temperature-dependent magnetic properties of Al2O3/Co/CoO thin films deposited by magnetron sputtering

Using the methods of atomic force and electron microscopy and the magneto-optical Kerr effect, the role of the interface, roughness, and thickness of the magnetic layer in the temperature-dependent magnetic properties of thin Al2O3–Co films with a naturally oxidized cobalt surface was studied. The layers were deposited by magnetron sputtering. The thickness of the cobalt layer varied from 2 to 100 nm. For the first time, the dependences of coercive forces and exchange displacements on the thickness of the cobalt film in the temperature range from 80 to 300 K were obtained and analyzed. The contribution to the coercive force and exchange displacement from the oxidized cobalt surface increases as the temperature decreases below 160 K. The magnitude of the contribution depends on the base material on which the cobalt film is deposited and is maximum for a cobalt film with a thickness of ∼20 nm in the Al2O3/Co structure. A weakly magnetic layer was found at the Al2O3/Co interface. The behavior of the exchange bias in this layer is similar to the behavior of a ferromagnetic Co core with a naturally oxidized CoO shell. The thickness of this layer depends on the speed and order of deposition of the layers. When the order of deposition of layers (Co/Al2O3) changes, the behavior of the exchange displacement of the interface becomes similar to that observed in the ferromagnet/antiferromagnet system. That is, when the deposition order changes, the value of the exchange shift changes sign when the cobalt layer thickness is below 10 nm.

Integration of Sm2Co17 Micromagnets in a Ferromagnetic Multipolar Microrotor to Enhance MEMS and Micromotor Performance.

MEMS and micromotors may benefit from the increasing complexity of rotors by integrating a larger number of magnetic dipoles. In this article, a new microassembly and bonding process to integrate multiple Sm2Co17 micromagnets in a ferromagnetic core is presented. We experimentally demonstrate the feasibility of a multipolar micrometric magnetic rotor with 11 magnetic dipoles made of N35 Sm2Co17 micromagnets (length below 250 μm and thickness of 65 μm), integrated on a ferromagnetic core. We explain the micromanufacturing methods and the multistep microassembly process. The core is manufactured on ferromagnetic alloy Fe49Co49V2 and has an external diameter of 800 μm and a thickness of 200 μm. Magnetic and geometric measurements show good geometric fitting and planarity. The manufactured microrotor also shows good agreement among the magnetic measurements and the magnetic simulations which means that there is no magnetic degradation of the permanent magnet during the manufacturing and assembly process. This technique enables new design possibilities to significantly increase the performance of micromotors or MEMS.

Copper permalloys for fluxgate magnetometer sensors

Abstract. Fluxgate magnetometers are commonly used to provide high-fidelity vector magnetic field measurements. The magnetic noise of the measurement is typically dominated by that intrinsic to a ferromagnetic core used to modulate (gate) the local field as part of the fluxgate sensing mechanism. A polycrystalline molybdenum–nickel–iron alloy (6.0–81.3 Mo permalloy) has been used in fluxgates since the 1970s for its low magnetic noise. Guided by previous investigations of high-permeability copper–nickel–iron alloys, we investigate alternative materials for fluxgate sensing by examining the magnetic properties and fluxgate performance of that permalloy regime in the range 28 %–45 % Cu by weight. Optimizing the alloy constituents within this regime enables us to create fluxgate cores with both lower noise and lower power consumption than equivalent cores based on the traditional molybdenum alloy. Racetrack geometry cores using six layers of ∼30 mm long foil washers consistently yield magnetic noise around 4–5 pT/Hz at 1 Hz and 6–7 pT/Hz at 0.1 Hz, meeting the 2012 1 s INTERMAGNET standard of less than 10 pT/Hz noise at 0.1 Hz.

Dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks.

Pulsed power generators utilizing magnetic switch technology within the 100ns scale have become widespread for surface treatment, high power microwave generation, and food processing, in which the dynamic characteristics of the magnetic switch perform an important function. The saturation process, electric field between layers, and energy loss are closely associated with the applied time scale of the magnetic core, which affects the dynamic characteristics of the switch. However, compared with the study within the microsecond scale, the dynamic characteristics of magnetic switches within the 100ns scale have not been studied in depth. In this paper, the dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks (PFNs) are studied via both field-loop co-simulation and scaled experimental test. It is found that increasing PFN section number (Ns) leads to an acceleration in the saturation process of the core, which helps understand the switch performance of the magnetic core more clearly. With respect to a specific magnetic switch based on a ferromagnetic core, it is quantitatively analyzed that increasing Ns from 1 to 10 leads to a 16.1% reduction in core saturation time (tsat), a 13.4% increase in eddy loss (EET), and a 5.7% rise in maximum interlamination field strength (Emax) under the 100ns scale; however, tsat is reduced by 19.3%, EET increases by 5.2%, and Emax rises by 2.3% under the microsecond scale. The results could provide a design reference for magnetic switches in pulsed power generators.

Effects of Ferromagnetic Cores in Wireless Power Transfer System for Charging Electric Vehicles

Wireless Power Transfer (WPT) technology for charging Electric Vehicle (EV) batteries is promising technology. System performance improvement and reducing Electromagnetic field (EMF) leakage are the key factors in designing an optimum charger. In this paper, adding ferrite disk to the WPT resonator is intensively studied. Three case studies are proposed, including coils only without ferrite, ferrite disk is used to the transmitting coil, and ferrite disks are used with the two coils. Finite Element Method (FEM) software is used for designing 3 kW-class, 20cm transfer distance, 85 kHz charger. The simulation results are recorded andcompared with regard to the system coil-to-coil efficiency and the EMF levels above the receiving coil and inside the air-gap. The results show that adding ferrite disks is significantly enhanced the system performance as well as reduced the EMF surrounding the charger.

Advantages of Bistable Microwires in Digital Signal Processing.

The advantageous applications of magnetic bistable microwires have emerged during long-lasting research. They have a wide range of applications in the scientific sphere or technical practice. They can be used for various applications, including magnetic memories, biomedicine, and sensors. This manuscript is focused on the last-mentioned application of microwires-sensors-discussing various digital signal processing techniques used in practical applications. Thanks to the highly sensitive properties of microwires and their two stable states of magnetization, it is possible to perform precise measurements with less demanding digital processing. The manuscript presents four practical signal-processing methods of microwire response using three different experiments. These experiments are focused on detecting the signal in a simple environment without an external magnetic background, measuring with the external background of a ferromagnetic core, and measuring in harsh conditions with a strong magnetic background. The experiments aim to propose the best method under various conditions, emphasizing the quality and signal processing speed of the microwire signal.

Mathematical Model of a Nonlinear Power Transformer for Needs of Relay Protection

In this work, a mathematical model of a three-phase nonlinear transformer is suggested. The model enables simulating the transformer operation with allowance for its nonlinearity and covers needs of the relay protection. Our model has been developed on the basis of a mathematical model with phase coordinates, where differential equations are composed by the Kirchhoff’s phase-voltage law. Based on this model, we first compose a mathematical model for simulating steady-state operation modes of a transformer, taking into account the asymmetry and nonlinearity of its ferromagnetic core. In this model, the initial values of inductances and mutual inductances of loops are determined from the main phase inductance calculated by the experimentally found no-load current, and their current values are determined from the currents in windings and the magnetic fluxes in legs of the transformer core. The magnetic fluxes are calculated by the nodal-pair method. This improved mathematical model is verified through a comparison between the calculated harmonic components of the phase currents and the experimental results. The harmonic components are calculated with the use of Fourier expansion of the calculated phase currents. Their experimental values are determined with a spectrum analyzer. The calculated and experimental harmonic components of the currents of phase A during no-load and rated-load operation of the transformer are tabulated. The comparison of these results shows that the mathematical model of a three-phase transformer we suggest makes it possible to simulate currents in transformer windings under steady-state operation modes with accuracy acceptable for relay protection.

Sample-tracking vibration isolation with rigid negative stiffness for broad bandwidth

Sample-tracking vibration isolators position their mover such that the distance to a targeted sample is constant to provide a vibration-free environment, for example, for inline metrology with high resolution. To achieve high vibration isolation and rejection especially at low frequencies, this paper proposes a sample-tracking vibration isolator that integrates a flexure-guided hybrid reluctance actuator (HRA) with a negative stiffness for quasi-zero stiffness (QZS). The negative stiffness cancels the flexure stiffness for QZS, by which vibrations transmitted from the actuator’s stator can be significantly reduced. Unlike conventional QZS systems, the negative stiffness is magnetically realized with rigid components such as a permanent magnet and ferromagnetic cores. Consequently, the proposed vibration isolator has mechanical resonant frequencies of around 2.5kHz and higher. This hardware design with a feedback controller realizes a motion with nanometer resolution and a high closed-loop control bandwidth of 991Hz for further vibration isolation and sample tracking. To evaluate the performances of the proposed vibration isolator, the negative stiffness is tuned to cancel a flexure stiffness at experiments. Experimental results show that the fine tuning decreases transmissibility from −30dB to −62dB by a factor of 40 at a low frequency of 10Hz. Furthermore, the tracking error of the mover position is measured for a demonstration of the vibration rejection performance in the time domain. The results also show that the stiffness cancellation decreases the tracking error with feedback control from 2.7 nm (rms) to 1.3 nm (rms) by 52% at a steady state. The proposed sample-tracking vibration isolator successfully demonstrates high vibration isolation performance by utilizing the rigid negative stiffness of the HRA.

Optimized Ferromagnetic Core Magnetorquer Design and Testing for LEO Nanosatellite Attitude Control

Magnetorquers are a very suitable solution for the nanosatellite’s attitude and orbital control of low Earth orbit (LEO) given its constraints: small available volume, limited power consumption, and maximum weight limitation. In this work, an optimized ferromagnetic core magnetorquer is designed for LEO nanosatellites, considering the geometrical, electrical, and magnetic parameters in an electromagnetic finite element analysis (FEA). The final design dimensions are 10.9 mm diameter and 100 mm in length, with a ferromagnetic core made of high performance soft magnetic alloy Vacoflux50 measuring 5 mm diameter and 100 mm in length. Magnetorquer geometry has been optimized to achieve a very high compactness, reaching an optimal combination of high specific magnetic moment and magnetic moment-input power ratio at the same time. It shows a maximum magnetic moment of 1.42 Am2, a magnetic moment-input power ratio of 2.52 Am2/W, and a specific magnetic moment of 22.5 Am2/kg, with a power consumption of 0.565 W and 0.5 A. Such a combination of high-performance values has not been previously found. Furthermore, it has displayed higher magnetic moment and specific magnetic moment than previous prototypes in literature. The simulated model is validated with the experimental testing of a manufactured prototype, by measuring the magnetic and electric variables.

Electromagnetic Characterization of Silicon–Iron Additively Manufactured Cores for Electric Machines

This paper deals with the electromagnetic characterization of a laminated toroidal ferromagnetic core made through additive manufacturing, specifically using the laser powder bed fusion process. The continuing demand for increasingly efficient, lightweight, and higher performance electric machines is creating huge challenges in the design and realization of new electric motor solutions. The constant improvements in additive manufacturing technologies have prompted researchers to investigate the possibility of adopting these production techniques for the manufacture of high-value electric motors. For these reasons, this paper investigates the ferromagnetic characteristics of an additively manufactured core made with FeSi6.5 powder. The BH curve and the specific iron losses of the processed material have been measured so that they can be compared with a commercial lamination, and have the possibility of carrying out more precise finite element simulations.

Modeling and Simulation of a High-Performance Magnetic Biosensor for Biomedical Sensing

The current magnetic-based biosensor technologies are expensive and intricate, making them unsuitable for meeting the requirements of point-of-care medical diagnosis. This research introduces a straightforward magnetic biosensor architecture that includes an L-shaped ferromagnetic core with UL dimensions. The design involves an air gap being replaced with highly porous aluminum or copper foam, offering a potentially cost-effective and uncomplicated solution for point-of-care diagnosis based on the magnetic field effect. The foam serves as a medium for hosting biological samples, such as proteins and DNA, which are labeled with high-permeability ferromagnetic nanoparticles. The biosensor operates by detecting labeled biological molecules through magnetic field interactions. The electrical parameters of the system underwent methodical optimization to enhance overall performance. The investigation delved into the influence of various materials on the magnetic properties of the air gap. It also examined the relationships between permeability, output-induced voltage, input voltage, and input frequency. The findings reveal that utilizing materials with elevated magnetic permeability, such as Magnetite (Fe3 O4 ) or Cobalt ferrite (CoFe2 O4 ) ferrofluids, significantly enhances the biosensor's performance by optimizing magnetic coupling between primary and secondary windings. This innovative magnetic biosensor exhibits potential applications in diverse fields, including molecular biology and medical diagnostics. The study contributes valuable insights into the design and optimization of magnetic biosensors, offering opportunities for heightened sensitivity and selectivity in the detection of ferromagnetic nanoparticles labeled biomolecules such as DNA or proteins.

Modelling and Analysis of Electromechanical Stress in Transformers Caused by Short-Circuits

A common reason for internal faults in transformers windings is the weakness insulation caused by vibration / deformation related to electromechanical forces produced by high short circuit currents. This phenomenon significantly reduces the transformer life expectancy and may even lead to its instantaneous or timing destruction. Focusing this subject this paper is aimed at presenting the performance of a time domain model inserted in a finite element program i.e. the 3D software package and the investigation of the relationship between high current levels occurring at transformer windings and the internal mechanical stresses. To highlight the overall model and the software performance, a laboratory 15 kVA transformer is utilized to show the programme facilities and potentially. The transformer has been built with concentric double-layer windings and ferromagnetic core with three columns and this equipment has been submitted to a balanced three-phase short- circuit. In addition, the computational simulations were carried out using distinct geometries to the windings i.e. with and without deformation.

Pretreatment of anaerobic fermentation feedstock in a vortex layer apparatus: Effect of the working chamber ferromagnetic core on biogas production

Currently, the volume of waste generation is growing at a high rate. Anaerobic digestion is an effective way to process organic waste to produce biogas. To increase the bioavailability and efficiency of mass transfer between feedstock particles and microorganisms, it is advisable to pretreat organic waste using various methods. One of the most promising and energy-efficient methods for preparing a feedstock for anaerobic bioconversion is its processing in a vortex layer apparatus (VLA). However, there are some limitations in the VLA operation. Therefore, to exclude the stagnant central zone from the volume of the VLA working chamber and increase the magnitude of the magnetic field in the VLA working chamber, a ferromagnetic core in the form of a steel pipe was coaxially mounted. Thus, the purpose of this work is to experimentally study the effect of the ferromagnetic core of the VLA working chamber on the production of biogas during anaerobic bioconversion of a model of organic waste from the agricultural sector. To achieve this goal, an experimental plant was developed and created. The experimental data obtained suggest the high efficiency of pretreatment of the feedstock in VLA with a ferromagnetic core in the working chamber before anaerobic bioconversion. The developed anaerobic bioconversion system made it possible to increase the methane production rate by 287 % at hydraulic retention time (HRT) of 4 days and by 3.5 times at HRT of 2 days compared to the control. At the same time, the methane yield at HRT of 4 days increased by 43 %, and at HRT of 2 days it decreased by 14 %. The hydrogen sulfide content in biogas also increased more than three times, while no hydrogen was detected in the biogas. Thus, pretreatment of the feedstock in VLA with a ferromagnetic core to produce biohythane in a one-stage anaerobic bioconversion system at 55.1 °C is impractical.

ПОВЫШЕНИЕ ЭНЕРГОЭФФЕКТИВНОСТИ СИСТЕМЫ ОБРАБОТКИ ПОБОЧНЫХ ПРОДУКТОВ ЖИВОТНОВОДСТВА, ОСНОВАННОЙ НА ИХ АНАЭРОБНОЙ БИОКОНВЕРСИИ

One of the anaerobic bioconversion process’s significant disadvantage at organic waste and animal by products’ treatment is the limiting stage, namely hydrolysis existing. A number of wellknown methods of livestock organic waste and by products before methane fermentation’s pretreatment are described. To eliminate this disadvantage and hydrolysis process accelerating, it was proposed to use an improved vortex layer apparatus with an integrated ferromagnetic core located coaxially in the apparatus vortex layer’s working chamber pretreatment system using. This system allows to accelerate not only hydrolysis, but also to introduce additionally iron particles into the substrate, which are a catalyst for methanogenesis using. In addition, the iron particles anaerobic oxidation products are nutrients for methanogenic microorganisms. At the same time, it is known that the vortex layer apparatus consumed energy significant part into waste heat, that can be disposed by a pump’s compression heat using is converted. An experimental installation was developed and created, and its operation’s description is given. The energy consumption’s investigated system structure for animal by products processing based on their anaerobic bioconversion was also determined. By the response surface methodology using, key factors’ influence was studied, namely, of the initial substrate’s pumping rate, the vortex layer apparatus cooling system for pumps’ circulation supply and electromagnetic field in the vortex layer apparatus’ coil frequency on the coolants’ temperatures in the heat pump’s compression evaporator and condenser and the initial substrate’s temperature’s changing and, as a result, the energy efficiency process preprocessing. By the central composite experiment’s design using, these factors’ optimal values with an electricity coefficient conversion into heat optimized value based on previously defined optimization’s criteria were found. The obtained experimental data allow to talk about in both the electricity conversion’s coefficient spent on the ABC operation and the energy system’s efficiency as a whole increasing.

Analysis of traditional Indian system of medicine (Ayush)

Even as equity but instead company worth of an innate prescription drugs would be going to expand enormously, verification after all safety, value but instead validity after all reparative crops but instead homegrown talent products are popping into such an essential factor. A need for significant significance would be to nurture of one specific research methods but very much started planning processes again for generalization after all homegrown talent naturally occurring substances but instead organic define. Bhasma is more or less named dusts which really is a ferromagnetic core fully prepared whilst also contemporary narcotic practices and so too plays a key component through intensifies, sub-intense, but also progression diseases. Its proposed will include its twist of fate as well as acceptance of selected Vedic describing in detail operatively rani lehyam (kl) whilst also going to decide various physicochemical as well as phytoconstituents limits. Kuantan had been revealed to specific flavonoid trying to separate proposal to find distinctive bioactive components current throughout Kuantan description.

Development of spiral square coils for magnetic labelling detection in microfluidic systems

Due to the development of microfluidic systems biomedical microelectromechanical systems (BioMEMS) for magnetic labelling detection by magnetic microbeads circling in microfluidic channels, we used the magnetic field created by microcoils. The magnetic field associated with the electric current, but with negatively affects if its value increases too much. Handling bio-species in the microfluidic chip requires that the temperature maintained to keep the cells to prevent their destruction. In this paper we have described the spiral square coil design of different structures to produce an effective magnetic flux density. The simulation of the magnetic flux density is carried out with the help of the COMSOL software. We have presented an optimization of the geometric parameters of the microcoil for a better performance and a miniaturization of the structure with copper wire section S=25 µm<sup>2</sup> and inter-wire space a=5 µm. We have also developed this microcoil by adding a ferromagnetic core to the inner center, the results obtained in this work shown that the magnetic flux density increases around 1.07 times in Bx and 1.45 times in Bz. This new approach in designing a microcoil allows to obtaining a fast trapping of the microbeads and a highly sensitive biological element detection and avoiding increase heat ratio in microfluidic systems.

Design and testing of a switched reluctance motor with additively manufactured ferromagnetic cores

Design and testing of a switched reluctance motor with additively manufactured ferromagnetic cores