Ferrite Core Research Articles

Analysis and Design of a Recyclable Inductive Power Transfer System for Sustainable Multi-Stage Rocket Microgrid with Multi-Constant Voltage Output Characteristics—Theoretical Considerations

After a traditional one-time rocket is launched, most of its parts will fall into the atmosphere and burn or fall into the ocean. The parts cannot be recycled, so the cost is relatively high. Multi-stage rockets can be recovered after launch, which greatly reduces the cost of space launches. Moreover, recycling rockets can reduce the generation of waste and reduce pollution and damage to the environment. With the reduction in rocket launch costs and technological advances, space exploration and development can be carried out more frequently and economically. It provides technical support for the sustainable use of space resources. It not only promotes the sustainable development of the aerospace field but also has a positive impact on global environmental protection, resource utilization, and economic development. In order to adapt to the stage-by-stage separation structure of the rocket, this paper proposes a new multi-stage rocket inductive power transfer (IPT) system to power the rocket microgrid. The planar coil structure is used to form wireless power transfer between each stage of the rocket, reducing the volume of the magnetic coupling structure. The volume of the circuit topology structure is reduced by introducing an auxiliary coil. An equivalent three-stage S/T topology is proposed, and the constant voltage output characteristics of multiple loads are analyzed. A multi-stage coil structure is proposed to supply power to multiple loads simultaneously. In order to eliminate undesired magnetic coupling between coils, ferrite cores are added between coils for effective electromagnetic shielding. The parameters of the magnetic coupling structure are optimized based on the finite element method (FEM). A prototype of the proposed IPT system is built to simulate a multi-stage rocket. A series of experiments are conducted to verify the advantages of the proposed IPT system, and the three-stage rocket system efficiency reached 88.5%. This project is theoretical. Its verification was performed only in the laboratory conditions.

Investigation of a Magnetic Levitation Architecture with a Ferrite Core for Energy Harvesting

This work presents the development of a magnetic levitation system with a ferrite core, designed for electromagnetic energy harvesting from mechanical vibrations. The system consists of a fixed enamel-coated copper coil and five neodymium-iron-boron permanent magnets housed within a PVC spool. To enhance magnetic flux concentration, a manganese-zinc ferrite (Mn-Zn) ring was employed within the spool. Experimental tests were conducted at frequencies up to 20 Hz, demonstrating the device’s potential for harvesting energy from small vibrations, such as those generated by human biomechanical movements, achieving operating voltages up to 3 V. Additionally, the architecture is scalable for larger systems and allows for the integration of multiple transducers without magnetic field interference, independent of the frequency or excitation phase of each transducer.

Binder jet 3D printing of Mn–Zn ferrite soft magnet toroidal cores

Traditional powder processing methods for Mn–Zn ferrites limits design freedom and scalability of producing customized soft magnetic cores. In this work, binder jet 3D printing techniques were applied to commercially available Mn–Zn ferrite powders and toroidal cores were successfully fabricated. As-printed Mn–Zn ferrite powders were sintered at different temperatures between 1300 and 1400 °C, resulted in an optimized single-phase spinel at 1350 °C. Microstructural characterization revealed high porosity remained for binder jetted materials and various magnetic property measurements were performed on sintered cores. Despite high porosity, the saturation moments normalized by mass remained similar between binder jetted and traditionally compacted samples. Two-winding method measurements indicated a large demagnetizing field for binder jetted samples. Effective medium theory model was used to estimate the effect of remnant porosity on measured magnetic permeabilities. Importance of novel concepts to successfully realize dense cores through additive manufacturing pathways such as binder jetting is highlighted.

Influence of inhomogeneous magnetic field source location on the intensity of thermomagnetic convection in a closed loop

Purpose. Obtaining information on the influence of the location of the inhomogeneous magnetic field source relative to the heated section of a vertical hydrodynamic loop filled with magnetic fluid on the intensity of convective heat transfer along the loop.Methods. Experiments were carried out using a hydrodynamic loop made of a thin tube of circular cross-section and placed in a vertical plane. Heat source was carried out by a heater on a short vertical section of the loop, and heat removal was implement out by blowing the entire surface of the tube with thermostated air. The source of the magnetic field was the flat pole tips of the ferrite magnetic core, in the gap between which the heater was located. The position of the pole tips relative to the heater varied vertically in the experiments. In the control experiments, the source of the magnetic field was deleted. The circuit was filled with medium concentrated magnetic liquid of the type "magnetite - kerosene - oleic acid". The intensity of steady-state convective heat flow along the tube was calculated from the results of measuring the tube surface temperature by copper-constantane thermocouples. The measurement results were presented in dimensionless form - the relationship between the Nusselt number and Rayleigh number.Results. The unfluctuating mixed, thermomagnetic and gravitational, convection of the magnetic fluid in the loop was observed at any location of the pole tips of the magnetic core relative to the heater. At location of pole tips above the heater, competition of gravitational and thermomagnetic convection was observed, and the heat flux was weak. When the pole tips were placed below the heater, the Nusselt number was 2 - 4 times higher than in the control tests (only gravitational convection) with equal Rayleigh numbers. The highest Nusselt numbers were obtained when the field source was placed in center of the heater.Conclusion. Information on the influence of the relative location of the magnetic field source and the heater on convective heat transfer by magnetic fluid in a hydrodynamic loop is obtained experimentally. The optimal concerning of heat transfer intensity position of the field source was found.

Effect of Ferrite Core Modification on Electromagnetic Force Considering Spatial Harmonics in an Induction Cooktop

This study investigates the influence of ferrite shape modifications on the performance and noise characteristics of an induction cooktop. The goal is to optimize the air gap dimensions between ferrites and cookware, enhancing efficiency while managing noise levels. Using finite element method (FEM) simulations, we analyze the spatial distribution of magnetic forces and their harmonics. Eight ferrite shape models were examined, focusing on both outer and inner air gaps. Model #8 (reduced outer air gap) and Model #9 (reduced inner air gap) were experimentally validated. Noise measurements indicated that Model #8 reduced 120 Hz harmonic noise components, while Model #9 increased them due to enhanced excitation forces. Current measurements confirmed that Model #9 achieved higher efficiency, with RMS current reduced to 94.54% of the base model. The study reveals a trade-off between performance and noise: inner air gap reduction significantly boosts efficiency but raises noise levels, whereas outer air gap reduction offers balanced improvements. These findings provide insights for optimizing induction cooktop designs, aiming for quieter operation without compromising efficiency.

A Lightweight Segmented RFID Tag Antenna With a Combined Ferrite Core for Underground Applications

A Lightweight Segmented RFID Tag Antenna With a Combined Ferrite Core for Underground Applications

Research and design of multi‐stage multi‐load wireless power supply system for high voltage online monitoring equipment

AbstractMany online monitoring devices in substations are placed at high potential differences from the ground, and it is not possible to supply power to these devices directly from the ground through wires. Placing magnetically coupled structures inside the substation pillar insulators for inductive power transfer is considered a feasible solution, and at this stage of research, systems that add multi‐stage repeating coil structures are mostly used to achieve stable power supply for individual online monitoring devices. However, the monitoring point generally requires multiple devices to monitor together, and the power requirements of different devices are different, so adding multiple repeating coils at the same time will increase the complexity of the system design, which is not conducive to engineering applications. Therefore, this paper designs and optimizes a multi‐stage multi‐load wireless power supply system magnetic coupling structure, using a three‐dimensional hollow solenoid combined with a ferrite core as the system repeating coil structure and an embedded magnetic coupling structure as the receiver end structure to reduce the number of system repeating coils while supplying power to devices with different power requirements. A prototype with a transmission distance of 1.02 m was built in the experiment, and the experimental results showed that the highest transmission efficiency of the system was 44.3% and 39.2% under single load and double load conditions, respectively. As the load resistance increases, the system can achieve constant voltage output under both single‐load and dual‐load operating conditions. Adjusting the number of turns of the receiving coil can change the output characteristics of the system and achieve constant voltage output of different voltage levels or constant current output of different current levels, which can meet the power supply needs of different loads.

Hybrid Aerosol Jet Printing and Electrodeposition of Ferrite-Sandwiched Inductors

The additive manufacturing (AM) of inductors of suitable size to be integrated into packaged electronics is attractive to customize the device characteristics for the specific application. Magnetic ferrite cores are widely used in conventional inductors, however, wire wound inductors can be brittle, heavy, bulky. Planar spiral inductors in a sandwich configuration present a promising alternative. Aerosol jet printing, a direct write AM technology, can deposit metal inks at a resolution of < 10 µm. Metal nanoparticle inks have limited conductivity at < 40% bulk. Building a higher profile may result in loss of resolution. Electrodeposition offers the ability to plate thick layers of highly conductive metals, including copper and nickel which are normally hard to access as nanoparticle inks compatible with aerosol jetting. We have previously shown the construction of a multi-layer flyback transformer with this hybrid aerosol jet and electrodeposition method. [1]We present a three-layer planar inductor with the first layer being a 1.3mm stack of ferrite sheets (Fair-Rite) with a 9 mm x 9 mm footprint integrated onto a circuit board. The intermediate layer consists of a spiral inductor made by aerosol jet printing UTDots Ag40X silver nanoparticle ink as the seed layer. To achieve high accuracy, the inductor was printed with a rotary axis stage. Electrodeposition in an acidic CuSO4 plating bath on top of the Ag seed layer resulted in thicknesses of 50 µm. A submicron layer of Ni is added for oxidation protection by electrodeposition from a Ni-Sulfamate bath. Lastly, a top 1.3 mm ferrite stack, with laser cut holes, is added to provide pass throughs for wire bonding. Figure 1 shows a micrograph of an inductor as printed, after electrodeposition, and with the top ferrite layer. Electrical measurements including impedance characteristics will be presented.SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. The SAND No. is SAND2023-14571A.Figure 1. Construction of a ferrite-sandwiched inductor with (a) the aerosol jet printing of an Ag seed layer, (b) after electroplating of Cu and Ni.

Development and Evaluation of Ferrite Core Inductively Coupled Plasma Radio Frequency Ion Source for High-Current Ion Implanters in Semiconductor Applications.

This study presents the development of a ferrite core inductively coupled plasma (ICP) radio frequency (RF) ion source designed to improve the lifetime of ion sources in commercial ion implanters. Unlike existing DC methods, this novel approach aims to enhance the performance and lifetime of the ion source. We constructed a high-vacuum evaluation chamber to thoroughly examine RF ion source characteristics using a Langmuir probe. Comparative experiments assessed the extraction current of two upgraded ferrite core RF ion sources in a commercial ion implanter setting. Additionally, we tested the plasma lifetime of the ICP source and took temperature measurements of various components to verify the operational stability and efficiency of the innovative design. This study confirmed that the ICP RF ion source operated effectively under a high vacuum of 10-5 torr and in a high-voltage environment of 30 kV. We observed that the extraction current increased linearly with RF power. We also confirmed that BF3 gas, which presents challenging conditions, was stably ionized in the ICP RF ion sources.

Transformer coupled toroidal wave-heated remote plasma sources operating in Ar/NF3 mixtures

Remote plasmas are used in semiconductor device manufacturing as sources of radicals for chamber cleaning and isotropic etching. In these applications, large fluxes of neutral radicals (e.g. F, O, Cl, H) are desired with there being negligible fluxes of potentially damaging ions and photons. One remote plasma source (RPS) design employs toroidal, transformer coupling using ferrite cores to dissociate high flows of moderately high pressure (up to several Torr) electronegative gases. In this paper, results are discussed from a computational investigation of moderate pressure, toroidal transformer coupled RPS sustained in Ar and Ar/NF3 mixtures. Operation of the RPS in 1 Torr (133 Pa) of argon with a power of 1.0 kW at 0.5 MHz and a single core produces a continuous toroidal plasma loop with current continuity being maintained dominantly by conduction current. Operation with dual cores introduces azimuthal asymmetries with local maxima in plasma density. Current continuity is maintained by a mix of conduction and displacement current. Operation in NF3 for the same conditions produces essentially complete NF3 dissociation. Electron depletion as a result of dissociative attachment of NF3 and NF x fragments significantly alters the discharge topology, confining the electron density to the downstream portion of the source where the NF x density has been lowered by this dissociation.

Comparative investigation of magneto-fluorescent core@shell nanostructures prepared using hard and soft ferrite as core

The paper focuses on the potential of magneto-fluorescent nanostructures intended to join simultaneously several functions of dissimilar core and shell material into a single entity. Two different types of magneto-fluorescent nanostructures with a broad array of physicochemical properties are premeditated and collated here. Strontium hexaferrite (Hard ferrite) core with CdS shell and Nickel Zinc ferrite (Soft ferrite) core with CdS shell are the two sets of magneto fluorescent nanostructures that were designed. Magnetic and optical analysis of both sets provides divergent outcomes. The shape of the derivative hysteresis curve gives a direct indication of the dissimilar nature (superparamagnetic & Permanent magnetic) of magnetic cores respectively. Optical results depict that both sets of magneto-fluorescent nanostructures are highly stable showing emission only in the position of the CdS shell only.

Analytical model of an I-core coil inside a metal tube of finite length

An analytical solution is presented for the interaction of an I-core coil with a metal tube of finite length. Using the Truncated Region Eigenfunction Expansion (TREE) method, the impedance variation of the I-core coil is expressed in a closed form. Notably, the 1D finite element method (1D FEM) is adopted to calculate the complex eigenvalues and eigenfunctions of the steel tube, by which the overflow issue of complex eigenfunctions has been surmounted. And the 1D FEM also simplifies the calculation in the ferrite core region immensely. A performant algorithm is obtained due to the matrix formalization and the high speed of the sparse eigenvalue solver. The tubes made of aluminum alloy and stainless steel are investigated by the proposed method and tested in the experiment. The high reliability and efficiency of the proposed method are proved, and the results are also validated by the comparison with simulation and measurement data.

Modelling of negative equivalent magnetic reluctance structure and its application in weak-coupling wireless power transmission

In weak-coupling wireless power transmission, increasing operating frequency, and incorporating metamaterials, resonance structures or ferrite cores have been explored as effective solutions to enhance power efficiency. However, these solutions present significant challenges that need to be addressed. The increased operating frequency boosts ferrite core losses when it exceeds the working frequency range of the material. Existing metamaterial-based solutions present challenges in terms of requiring additional space for slab installation, resulting in increased overall size. In addition, limitations are faced in using Snell’s law for explaining the effects of metamaterial-based solutions outside the transmission path, where the magnetic field can not be reflected or refracted. To address these issues, in this work, the concept of a negative equivalent magnetic reluctance structure is proposed and the metamaterial theory is extended with the proposed magnetic reluctance modelling method. Especially, the negative equivalent magnetic reluctance structure is effectively employed in the weak-coupling wireless power transfer system. The proposed negative equivalent magnetic reluctance structure is verified by the stacked negative equivalent magnetic reluctance structure-based transformer experiments and two-coil mutual inductance experiments. Besides, the transmission gain, power experiments and loss analysis experiments verify the effectiveness of the proposed structure in the weak-coupling wireless power transfer system.

Misalignment tolerance improvement of loosely coupled transformer with ferromagnetic materials via genetic algorithm

AbstractIn wireless power transfer (WPT) systems, misalignment between the primary and secondary coils can decrease the transmission efficiency of the loosely coupled transformer (LCT). Adding ferromagnetic materials or a relay coil is an effective solution for efficiency and misalignment tolerance improvement if extra eddy current loss and hysteresis loss on the ferromagnetic materials or the conduction loss caused by the relay coil is well controlled. The effect of ferrite cores on the transmission efficiency of two‐coil and three‐coil LCTs is analysed from the perspective of loss. By finite element analysis, the dimension of ferrite cores is optimised via the genetic algorithm to improve the efficiency and misalignment tolerance of the LCT. Optimal ferrite core dimension is also verified in a 1‐kW WPT prototype, and experimental results show that, after optimisation, transmission efficiency of the two‐coil LCT can be improved by 2.681% and 8.930% under alignment and the 200‐mm misalignment, and with the proposed control strategy, transmission efficiency of the LCT is always above 94.925% under various misalignment conditions.

Manufacturing and performances of MnZn ferrite cores with thin walls prepared by paste material extrusion 3D printing

The 3D printing technique using material extrusion of a paste filled with ferrite powder (Mn,Zn)Fe2O4 and organic additives has been successfully improved to produce sintered samples for studying their magnetic and structural properties. The rheological behaviour of the pastes and the printing parameters have been optimised to obtain parts with regular geometries, in particular by minimising sagging effect during filament deposition. Printing is followed by a debinding and sintering stage, for which the temperature and oxygen partial pressure conditions were adjusted. These conditions enable the densification of the (Mn,Zn)Fe2O4 material in the spinel structure without parasitic phases, with a low grain size dispersion and a relative density of 91 %. The core loss has been measured on the 3D printed samples to be 144 mW/cm3 at a frequency of 500 kHz and an induction of 50 mT. This performance is comparable to the nominal value of a part produced by the conventional process. This work paves the way for an advantageous manufacturing method in terms of accessible geometries, while maintaining satisfactory magnetic characteristics.

Decoupled dual‐channel loosely coupled transformer with hybrid nanocrystalline and ferrite core for current sharing of modular wireless power transfer system

AbstractCross‐coupling and current sharing are the main problems faced by modular wireless power transfer (WPT) systems for electric vehicle (EV) applications. In this study, a decoupled dual‐channel wireless power transfer loosely coupled transformer (LCT) with a hybrid core composed of nanocrystalline and ferrite is proposed for modular WPT systems, as well as WPT systems with specific hybrid topology or detuned compensation. Firstly, the requirements of the LCT for modular parallel dual‐channel WPT system and detuned compensation are discussed. For these requirements, the structure and corresponding optimization design method of the decoupled dual‐channel LCT with a hybrid core is then proposed, and an LCT is designed with this method for the case study. Furthermore, the LCT is analysed by the finite element method (FEM). It is revealed that the mutual inductances of the proposed LCT between transmitting and receiving coils can be symmetrical under misalignment in multiple directions, while the cross‐coupling is eliminated. Finally, the designed LCT is manufactured and verified in a modular parallel dual‐channel WPT system. The experimental results show that the current and power sharing is realized under misalignment in multiple directions.

Design of a high‐frequency transformer based on amorphous cut cores for insulation breakdown testing

AbstractInnovative test methods are required to keep up with the increased demand for insulation materials which can withstand the high‐frequency square‐wave voltages generated by power‐electronic equipment. Test systems using high‐voltage, high‐frequency transformers have proven versatile and easy to realise. The authors investigate the application of amorphous cut cores in such transformers. Analytical and numerical models for the transformer and its frequency response are developed, aiding the design process. An amorphous core‐based transformer is designed for 8 kVpk output at 100 kHz and compared to two previous designs based on ferrite cores. The frequency and pulse response, as well as the high‐voltage and thermal performance, are evaluated. The comparison shows that while the low parasitics of the amorphous‐based transformer allow for superior frequency response, they are unsuitable for long‐duration tests with high pulse repetition frequencies (25–100 kHz) due to increased core losses. The partial discharge inception and flashover voltage are comparable to the ferrite‐based transformers.

"Core/Shell" Nanocomposites as Photocatalysts for the Degradation of the Water Pollutants Malachite Green and Rhodamine B.

"Core/shell" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO2, and the other is a semiconductor, TiO2. These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the "core/shell" МFe2O4/SiO2/TiO2 (М = Zn(II), Co(II)) type are synthesized with a core of MFe2O4 produced by two different methods, namely the sol-gel method (SG) using propylene oxide as a gelling agent and the hydrothermal method (HT). SiO2 and TiO2 layer coating is performed by means of tetraethylorthosilicate, TEOS, Ti(IV) tetrabutoxide, and Ti(OBu)4, respectively. A combination of different experimental techniques is required to prove the structure and phase composition, such as XRD, UV-Vis, TEM with EDS, photoluminescence, and XPS. By Rietveld analysis of the XRD data unit cell parameters, the crystallite size and weight fraction of the polymorphs anatase and rutile of the shell TiO2 and of the ferrite core are determined. The magnetic properties of the samples, and their activity for the photodegradation of the synthetic industrial dyes Malachite Green and Rhodamine B are measured in model water solutions under UV light irradiation and simulated solar irradiation. The influence of the water matrix on the photocatalytic activity is determined using artificial seawater in addition to ultrapure water. The rate constants of the photocatalytic process are obtained along with the reaction mechanism, established using radical scavengers where the role of the radicals is elucidated.

The Magnetized Capacitance, First Resonant Frequency, and Electromagnetic Analysis of Inductors With Ferrite Cores

The Magnetized Capacitance, First Resonant Frequency, and Electromagnetic Analysis of Inductors With Ferrite Cores

A stacking machine‐learning based method for accelerating magnetic coupler design with ferrite cores in inductive power transfer applications

AbstractThis paper presents a magnetic coupler design method for WPT systems based on stacking machine‐learning algorithms. A synthetic dataset generated by ANSYS Maxwell is used for training and evaluating machine‐learning models. Stacking technology effectively combines the results from multiple models and make best predictions. The designed model allows us to obtain the optimal values of the coil inner radius and number of turns , when other coil design parameters such as the coil outer radius , the wire diameter , and the coil inductance , are given based on the application environment. The proposed method provides practical solutions meeting design requirements quickly, easily accommodating magnetic couplers with ferrite cores, and showing advantages in designing magnetic couplers with optimal power transfer efficiency.