Magnetic Iron Core Research Articles

Magnetic, conductive nanoparticles as building blocks for steerable micropillar-structured anodic biofilms

In bioelectrochemical systems (BES), biofilm formation and architecture are of crucial importance, especially for flow-through applications. The interface between electroactive microorganisms and the electrode surface plays an important and often limiting role, as the available surface area influences current generation, especially for poor biofilm forming organisms. To overcome the limitation of the available electrode surface, nanoparticles (NPs) with a magnetic iron core and a conductive, hydrophobic carbon shell were used as building blocks to form conductive, magnetic micropillars on the anode surface. The formation of this dynamic three-dimensional electrode architecture was monitored and quantified in situ using optical coherence tomography (OCT) in conjunction with microfluidic BES systems. By cyclic voltammetry the assembled three-dimensional anode extensions were found to be electrically conductive and increased the available electroactive surface area. The NPs were used as controllable carriers for the electroactive model organisms Shewanella oneidensis and Geobacter sulfurreducens, resulting in a 5-fold increase in steady-state current density for S. oneidensis, which could be increased 22-fold when combined with Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) aggregates. In the case of G. sulfurreducens, the steady-state current density was not increased, but was achieved four times faster. The study presents a controllable, scalable and easy-to-use method to increase the electrode surface area in existing BES by applying a magnetic field and adding conductive magnetic NPs. These findings can most likely also be transferred to other electroactive microorganisms.

Research on magnetic field characteristics of amorphous alloy and grain‐oriented silicon steel hybrid magnetic circuit iron core

AbstractAmorphous alloy and grain‐oriented silicon steel are commonly employed as soft magnetic materials for the preparation of transformer cores, but both materials have their advantages and disadvantages. Using only silicon steel or amorphous alloy for the preparation of the core makes it difficult to achieve both high design density and low no‐load loss characteristics. In order to achieve the magnetic performance advantages of both amorphous alloy and silicon steel in transformer core development and application, the authors design and develop a kind of amorphous alloy and grain‐oriented silicon steel hybrid magnetic circuit core to explore the amorphous alloy and grain‐oriented silicon steel at different ratios under the magnetic properties of matching law. Based on the amorphous alloy and grain‐oriented silicon steel core magnetic performance comparison characteristics, the authors establish a core magnetic circuit model and design a hybrid magnetic circuit core structure with different material ratios. The hybrid magnetic circuit core model is simulated and analysed to obtain the magnetic density distribution of the hybrid magnetic circuit core. A number of hybrid magnetic circuit core experimental models are produced, and the use of a magnetic property measurement platform is made for the hybrid magnetic circuit core measurements, to reveal the magnetic performance matching law of the hybrid magnetic circuit core, providing a good solution for power distribution in the hybrid magnetic circuit.

Study on the magnetic self-levitation of the ring permanent magnet with inserted inner cores in ferrofluid

The self-levitation of a magnetized object composed of ring permanent magnet, soft magnetic pure iron core (Fe-core), and nonmagnetic aluminum core (Al-core) in ferrofluid (FF) is studied, and the focus is the influence of Fe-core (Al-core) on the magnetic fluid levitation force (MFLF) received by the immersed magnetized object. The formula for calculating MFLF is derived focusing on the gas–liquid and solid–liquid boundary interface between FF and surroundings, and experiments have been done to study the dependence between MFLF and the levitation height of the magnetized object and mass of FF. Researches show that Fe-core has a significant influence on MFLF, and the influence is determined by the magnetization of Fe-core and the distance between Fe-core and the boundary interface. In a word, the use of Fe-core is beneficial to obtain a smaller MFLF, the greater the magnetization of the Fe-core is and the closer it is to the boundary interface of FF, the smaller the MFLF is. The Fe-core near the bottom surface of the ring magnet tends to reduce the maximum MFLF corresponds to an approximate horizontal gas–liquid boundary interface when the levitation height is constant, and the Fe-core near the top surface of the ring magnet is more likely to reduce the change of MFLF caused by the disappearance of surface instability of FF. Or, in other words, the Fe-core near the top surface of the ring magnet tends to reduce the MFLF when magnetized object moves upward, and vice versa.

Design of a Coreless Multi-Phase Electric Motor Using Magnetic Resonant Coupling

With the emergence of electric vehicles and electric aircraft technologies, lightweight motors have become a requirement. Conventional motors are generally made up of coils, permanent magnets, heavy iron stators, and rotor cores. This article presents complete analytical modeling and design of a novel coreless multi-phase magnetic resonant motor (MMRM), conceptualized through the approach of magnetic resonance coupling. The removal of magnetic iron cores drastically reduces the weight of the resulting motor. The stator and rotor cores of the motor are made of reinforced plastic fibers and can be 3-D printed. Unrelated to the general operating principle of the existing conventional electric motors, resonant wireless power transfer (WPT) is the key feature of these motors. All the essential machine characteristics, such as self-inductance, mutual inductance, torque, and frequency domains, are fully developed. The mathematical modeling of the machine’s physical phenomena is linked to its operation by simulation. This article shows the design concept and discusses the simulation procedure used to verify the developed analytical model through a finite-element analysis (FEA) from the established modeling topology equivalent to the proposed configuration motor model. Although the design is straightforward, an accurate analytical modeling and analysis are significant challenges to consider.

Characteristic analysis of conventional pole and consequent pole IPMSM for electric vehicle application

On December 12, 2020, President Xi Jinping announced at the Climate Ambition Summit that China will increase its nationally determined contribution, adopt more powerful policies and measures, and strive to reach the peak of carbon dioxide emissions by 2030, and strive to achieve carbon neutrality by 2060. As far as the automotive industry is concerned, replacing traditional fuel vehicles with electric vehicles is an important starting point for achieving carbon peak and carbon neutral goals. Inspired by the triangular permanent magnets of 2008 Lexus LS600H and 2012 Nissan LEAF, a 48-slot 8-pole conventional pole triangular interior permanent magnet synchronous machine (IPMSM) model and a 48-slot 8-pole consequent pole triangular interior permanent magnet synchronous machine model are created separately in this paper. The consequent pole IPMSM uses magnetic iron core instead of a part of the permanent magnet to reduce the amount of permanent magnets to make the processing process cleaner and lower carbon. The magnetic line of force of consequent pole IPMSM can be concentrated by the magnetic iron core to form a magnetic pole in order to reduce the dosage of the permanent magnet. Firstly, the finite element analysis (FEA) is used to optimize air gap flux density and confirm geometrical parameter of conventional pole IPMSM, then the FEA is used to confirm the geometrical parameter of consequent pole IPMSM machine by optimizing the output torque Tavg and torque ripple Tripple so that the Tavg of consequent pole IPMSM are similar to that of conventional pole IPMSM and Tripple of consequent pole IPMSM is lower than that of conventional pole IPMSM. The following analysis contents include no-load air gap magnetic density, back-EMF, cogging torque, torque ripple, loss and efficiency, flux-weakening performance. Finally, the following conclusion could be drawn that although Tavg of consequent pole IPMSM is slightly reduced compared to the conventional pole IPMSM, it uses fewer permanent magnets to meet output requirements and has better flux-weakening performance.

A core-shell Mn–C@Fe nanocatalyst under ozone activation for efficient organic degradation: Surface-mediated non-radical oxidation

A non-radical catalytic ozonation process functionalized by Mn(II)-sites was found effective to degrade oxalic acid as a typical refractory compound that is hard to remove through catalytic ozonation with hydroxyl radical oxidation. Specifically, we prepared functional Mn–C@Fe nanoparticles with carbon shell supporting Mn3O4 for catalysis while encapsulating magnetic iron core for recycle. Batch study shows its excellent catalytic reactivity on the degradation of organics particular for the ozone-recalcitrant oxalic acid (20 min for 90.9% removal, kinetics constant of 0.045 min−1). Our mechanism study ruled out the hydroxyl radical oxidation, and highlighted the formation of a heptavalent Mn intermediate oxidant responsible for the fast degradation that was initiated via ozone activation of Mn(II)-sites on the carbon shell. Our findings underscore a non-radical catalytic ozonation as a promising alternative technology for the abatement of aqueous organic pollutants.

Zero-valent iron core–iron oxide shell nanoparticles coated with silica and gold with high saturation magnetization

A new type of gold-coated magnetic nanoparticle with strongly magnetic zero-valent iron core–iron oxide shell were synthesized.

Design and Performance Analysis of a Saturated Iron-Core Superconducting Fault Current Limiter for DC Power Systems

A saturated iron-core superconducting fault current limiter (SI-SFCL) can significantly limit the magnitude of the fault current and reduce the stress on circuit breakers in direct current (DC) power systems. The SI-SFCL consists of three main parts: one magnetic iron-core, one normal conductive primary coil (CPC), and one superconducting secondary coil (SSC). This paper deals with the design options for the coil system of the SI-SFCL and confirms their operating characteristics through a physical experiment. The electromagnetic characteristics and operational features of the SI-SFCL was analyzed by a 3D finite element method simulation model. The design of the SSC was based on shape, wire types, required fault current limit and protection aspects. In the CPC, the bobbin was designed based on material selection, cost, structural design, and the effects of the SI-SFCL on the fault current limit. Based on these simulation results, a laboratory-scale SI-SFCL was developed, specifically fabricated to operate on a 500 V, 50 A direct current (DC) power system. In the experiment, the operating characteristics of each coil were analyzed, and the fault current limit of the SI-SFCL according to the operating currents of the SSC and bobbin design of the CPC were confirmed. Finally, the cost analysis of the SI-SFCL with the proposed design options of the coil system was implemented. The results obtained through this study can be effectively used to large-scale SI-SFCL development studies for high-voltage direct current (HVDC) power systems.

Studies of magnetic and thermodynamic characteristics iron core under high frequencies for traction motors

The Electrical Vehicle industry has developed rapidly in recent years, and the demand for new energy-driven motor systems has also increased. Permanent Magnet Synchronous Machine (PMSM) are high performance drive motors. In this paper, a new type of GO silicon steel material assembled stator core is proposed, compared with conventional Non Grain-Oriented (NGO) silicon steel stator, and the magnetic properties of the motor are analyzed. The method of assembling the stator core is given, in which the GO silicon steel sheets are stacked as the teeth of the stator core. GO silicon steel has low iron loss and large saturation magnetic density, which is more conducive to improving motor efficiency. The teeth of the stator core tend to have higher magnetic density and are more prone to sustain a higher iron loss. This research ensures the reliability of the test results through simulation analysis and physical test verification.

FEM Analysis of Iron Core Losses in Magnetically Controlled Shunt Reactor with Distributed Magnetic Valves

In this paper, the MCR with distributed magnetic valves is proposed. The magnetic valve is equally distributed in iron core, which is piled up by silicon-steel sheets and epoxy sheets. Field-circuit coupled simulation model is established in ANSYS software. The wave forms of electrical state variables, magnetic flux density distribution and iron core losses are acquired. The comparison with the MCRs with a single-stage magnetic valves and multiple-stage magnetic valves demonstrates the advantage of proposed magnetic valve structure.

Proposal of a compact magnetically levitated transverse flux permanent magnet linear synchronous motor as a 6‐DOF transport carrier

In this study, a novel 6-degree of freedom compact carrier using magnetically levitated transverse flux permanent magnet linear synchronous motor is proposed and initial design characteristics are analysed. Motor structure is compact with magnetic iron cores for thrust and levitation, arranged orthogonally. This allows reduced magnetic coupling between linear synchronous motor (LSM) and electromagnets despite their close proximity. Such configuration also ensures independent design for propulsion and suspension. Furthermore, by virtue of the proposed configuration, yaw and lateral motion are inherently stable, leaving the required active actuators to merely four for thrust, pitch, roll, and heave active control. Preliminary characteristics are analysed using 3D finite element method and performance considerations for the simultaneous design of LSM and electromagnets are discussed thoroughly.

Effect of Magnetic Iron Core–Carbon Shell Nanoparticles in Chemical Enhanced Oil Recovery for Ultralow Interfacial Tension Region

Some of the advantages of the simultaneous use of surfactants and nanoparticles in enhanced oil recovery (EOR) processes are the increase in the efficiency of injection fluid for sweeping, the redu...

Design and Performance Analysis of Single-Phase Pre-Saturated Core Fault Current Limiters

The technology of a presaturated core fault current limiter (PCFCL) has particular importance due to its instantaneous limitation of the fault current in electric power grids and keeping its value below the ratings of the switchgear or circuit breakers with a reasonable safety margin. In this paper, a design methodology of single-phase, simple nonsuperconducting magnetic coils, PCFCL is proposed based on extensive electromagnetic time-domain finite-element simulations taking into account the relative performances of the constructive design parameters. These controlled finite-element simulations allow fine realistic details, such as the nonlinear magnetic saturation behavior of the iron core to be included, and studying the effect on general performance during dynamic reactions of the system. Moreover, the dynamic behavior of PCFCL is characterized in terms of steady-state voltage drop across its terminals, counter electromotive force induced on the dc coil terminals, and limitation factor of the fault current. Dual-core and single-core designs are investigated with a comparison of their ability of limiting the fault current. Results reveal that the dual-core design has superior performance than that of the single-core one. Finally, a design methodology flowchart has been proposed which depends on the extensive simulation results of different PCFCL topologies and published experimental results, where changing either the governing constructive parameters or the magnetic iron core design are considered.

A Novel Five-Leg Design for Performance Improvement of Three-Phase Presaturated Core Fault-Current Limiter

In this paper, a novel five-leg design of non-superconducting, three-phase, presaturated core fault-current limiter (PCFCL) is proposed based on the time-domain, electromagnetic finite-element simulations to overcome the main drawbacks of the well-known topologies of PCFCLs. These drawbacks are large volume of magnetic iron core, high total power loss under steady-state condition, high-induced voltage across the dc coil terminals during the fault condition, and the technical risks of high-temperature superconducting coil and cryogenics in the case of superconducting fault-current limiter (SFCLs). The general performance of PCFCL can be expressed through the steady-state power loss and voltage drop, and fault-current clipping ratio and the induced voltage across the dc coil terminals during the fault condition. Different topologies of three-phase PCFCLs are considered with the comparison of their limiting capability for different types of faults. The results reveal that the proposed design of PCFCL has superior properties in limiting any type of fault currents with reduced volume of the magnetic iron core, total power loss, and the induced voltage across the dc coil terminals in comparison with those of the well-known dual-core PCFCL design. Furthermore, a performance analysis of the novel five-leg design is considered throughout an extensive simulation of the constructive controlling parameters to study their relative effects on the general performance of operation.

Inspired by efficient cellulose-dissolving system: Facile one-pot synthesis of biomass-based hydrothermal magnetic carbonaceous materials

The core-shell structure of carbon encapsulated magnetic nanoparticles (CEMNs) displays unique properties. Enhancing the magnetization of iron core, in parallel, improving the encapsulation of carbon shell are the two major challenges in the synthesis of CEMNs. Inspired by efficient cellulose-dissolving system, carbon encapsulated magnetic nano-Fe3O4 particles (Fe3O4@C) with ∼10.0nm Fe3O4 cores and 1.9–3.3nm carbon shell, were successfully one-pot synthesized via a novel hydrothermal carbonization (HTC) process. The dissolving process in ionic liquids ([Emim]Ac and [Amim]Cl) completely cleaved the intra- and intermolecular H-bonds in cellulose, and favored the incorporation of Fe3O4 nanoparticles into the cellulose H-bonds systems during the regeneration process. Some stable linkages were formed in Fe3O4@C, taking Fe3O4 nanoparticles as a structure guiding agent. The morphology and properties of Fe3O4@C depended strongly on the type of carbon precursors and pyrolysis temperature. Well encapsulated nanostructure was obtained at HTC temperature 280°C, when [Emim]Ac-treated holocellulose was used as the carbon source. Meanwhile, the thickness of the amorphous shell and magnetization increased with HTC temperature. More importantly, a novel elements for understanding the growth mechanism for the Fe3O4@C composite under HTC conditions was proposed.

Reduced graphene oxide wrapped Fe3O4–Co3O4 yolk–shell nanostructures for advanced catalytic oxidation based on sulfate radicals

In this work, we designed and synthesized a high performance catalyst of reduced graphene oxide (RGO) wrapped Fe3O4–Co3O4 (RGO/Fe3O4–Co3O4) yolk–shell nanostructures for advanced catalytic oxidation based on sulfate radicals. The synergistic catalytic action of the RGO/Fe3O4–Co3O4 yolk–shell nanostructures activate the peroxymonosulfate (PMS) to produce sulfate radicals (SO4−) for organic dyes degradation, and the Orange II can be almost completely degradated in 5min. Meanwhile the RGO wrapping prevents the loss of cobalt in the catalytic process, and the RGO/Fe3O4–Co3O4 can be recycled after catalyzed reaction due to the presence of magnetic iron core. What’s more, it can maintain almost the same high catalytic activity even after 10 cycles through repeated NaBH4 reduction treatment. Hence, RGO/Fe3O4–Co3O4 yolk–shell nanostructures possess a great opportunity to become a promising candidate for waste water treatment in industry.

Continental Drift and Plate Tectonics vis-a-vis Earth’s Expansion:Probing the Missing Links for Understanding the Total Earth System

Hypotheses like continental drift, plate tectonics or Earth’s expansion should not be considered as viable in view of solid and rigid state of mantle which, in contrast, would resist such phenomena. Based on Hilgenberg’s model of Earth’s expansion (1933), the author elucidates that before expansion when the Earth was small and devoid of oceans, its mantle must have been sufficiently fluid owing to association of ocean-forming water. Further, matching thickness of fluid outer core and extent of radial expansion of the Earth strongly support that the outer core was opened up as a void geosphere owing to planetary expansion. At the deep interior of the planet, owing to occurrence of a void or pseudo-fluid geosphere separating basaltic mantle and solid iron core, an additional force of reverse gravity would develop acting in opposite direction of normal inwardly directed force of gravity. This postulation leads us to consider that in the deep interior of the planet an upwardly directed force of gravitational attraction would act in a predominant manner, thereby sustaining sufficiently low temperature and pressure condition and magnetic nature of the inner core which completely agrees with observed features of terrestrial magnetism. Over the Earth’s surface the crustal layer was fragmented due to expansion while through the expansion cracks widespread incidences of magma emission occurred forming rudimentary ocean basins. With further expansion, these basins were expanded and filled up with water that degassed from the mantle associated with the process of magma emission while owing to desiccation, the mantle itself eventually turned into a rigid body. Before expansion of the planet when the iron core and the mantle were juxtaposed to each other, due to external magnetic influence the magnetic iron core was deflected causing major change in polar and equatorial disposition of the planet. Subsequently in younger geological period when due to expansion a major void geosphere was opened up between the iron core and mantle, external magnetic influences caused the magnetic core to execute smooth revolutions giving rise to new magnetic phenomena like pole reversal and polar wandering, documented over the planet’s younger strata. It may be noted that while due to expansion, the continental fragments would tend to move away from one another, owing to rotation of the planet along its axis of rotation some continental fragments came closer to each other or even collided to form mountain ranges.

Study on No-Insulation HTS Pancake Coils With Iron Core for Superconducting DC Induction Heaters

This paper focuses on no-insulation (NI) HTS pancake coils with iron core for superconducting dc induction heaters. A superconducting coil without turn-to-turn insulation and its conventional counterpart with insulation are wound with YBCO-coated tapes. An iron core is built for a laboratory-scale dc induction heater. The electromagnetic characteristics of the two coils with the iron core are studied focusing on the charging and sudden-discharging processes at 77 K. Three variables are measured, i.e., current, terminal voltage, and magnetic field induced. The results show that NI coil with the iron core incurs a significant delay in the charging and discharging process due to the influence of the iron core. A terminal voltage pulse is observed at the beginning of the sudden-discharging process, which is more than five times of its normal value. A circuit-field coupled method is proposed to analyze the electromagnetic characteristics of the NI coil with an iron core. The results from experiment and simulation exhibits good agreement. The research shows that it is possible to use the NI technique to build a HTS iron core magnet for a dc induction heater, which can simplify the quench protection system.

Electrical breakdown in dielectric liquids-a short overview

Power transformers are utilized to convert high voltages normally used in electrical power transmission to lower voltages more suitable for consumers. A transformer consists essentially of a magnetic iron core with primary and secondary copper windings. The alternating current flowing in the primary winding induces a magnetic flux in the core, which in turn creates a current in the secondary windings. If there is a difference in the number of turns in the primary and secondary windings, the secondary voltage will be scaled up or down proportionally to the ratio of the turns. In this way, a high voltage can be transformed to a low voltage. However, the desire to convert increasingly greater electrical loads using smaller power transformers results in both higher electrical and thermal stresses. The materials utilized to insulate the different electrically conductive components from each other must be designed to withstand those stresses. The insulating media often consist of pressboard and an insulating liquid. The liquid performs a double duty as it not only insulates the conductive parts but also functions as a liquid coolant. Here we are primarily interested in the oil as an insulating medium.

Electrical Insulation of HTS Coils in Saturated Iron Core Superconducting Fault Current Limiter

HTS coil is a key component for saturated iron core superconducting fault current limiter (SISFCL), which does not quench during all kinds of operation conditions of SISFCL. Voltages of the HTS coils have big differences among different operation conditions of SISFCL. During the normal operation, large dc current loaded on the HTS coils magnetize the iron core to saturated, and voltage on the HTS coils is very low. When a short-circuit fault occurs in the grid, dc current is cut off in milliseconds, resulting in high induced voltage on the HTS coils. After the fault is clear, a dc voltage is applied on the HTS coils for rapid magnetization of iron core. Design of electrical insulation for HTS coils is based on the above working conditions. In this paper, a dc breakdown test results of HTS tapes wrapped with Kapton as turn insulation, and the insulation structure, and the electrical test results of the HTS coils in 220 kV SISFCL are introduced in detail. Now, in-live operation of the 220 kV SISFCL also shows that the electric insulation of HTS coils is satisfied, reliable, and safe.