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To optimize cost and weight and streamline the manufacturing process of existing soft magnetic components, which currently rely on metallic soft magnetic particles, an innovative approach involving the preparation of high-performance magnetic polymeric composites is proposed. These composites are based on soft magnetic ferrite particles with high Curie temperature and magnetic saturation, along with low coercivity and remanent magnetization, and are used as fillers in thermoplastic polymers. To achieve these goals, cobalt ferrite (CoFe2O4) micro- and nanoparticles were synthesized by two different methos: solid-state reaction and coprecipitation. The as-obtained particles were used to fabricate soft magnetic polymer composites by extrusion and injection molding methods. The successful synthesis of cobalt ferrite was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The magnetic behavior of cobalt ferrites and polymer composites was also investigated by vibrating sample magnetometry (VSM). This study shows that these new high-performance soft magnetic polymer composites can be used as alternative materials for the manufacture of magnetic components such as inductors and transformers and that their low cost and lightweight make them suitable for the manufacture of magnetic components. [ABSTRACT FROM AUTHOR]

[Introduction] The purpose of this study is to explore the impact of the spatial magnetic field generated by nuclear fusion devices on magnetic devices and to gain an in-depth understanding of the magnetic field shielding characteristics in a complex electromagnetic environment. [Method] In the research process, the switch power supply and electronic transformer in the nuclear fusion internal power supply system were selected as the specific research objects. By analyzing in detail the impact of the magnetic field on the loss and the characteristic changes under different directions of the magnetic field, as well as by exploring the key factors affecting the magnetic field shielding effectiveness and the application of different materials, the research objectives were achieved. [Result] The results indicate that the loss of magnetic components significantly increases in a strong magnetic field environment, and the degree of influence of different directions of magnetic fields on component characteristics varies. By comparing and analyzing the shielding effects of different materials, it is found that materials with high conductivity and magnetic permeability have better application prospects in shielding design. Additionally, optimizing the shielding structure can further improve shielding effectiveness and reduce the impact of magnetic fields on magnetic components. [Conclusion] By systematically analyzing the impact of strong magnetic fields on magnetic components and the shielding effectiveness of nuclear fusion devices, key references are provided for testing the equipment's magnetic field tolerance and verifying shielding design. Future work will focus on further optimizing shielding materials and structural design to improve the stability and reliability of magnetic components in strong magnetic field environments.

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Estimating losses accurately for magnetic materials in power conversion circuits is a challenging task. Solving the partial differential equations in a complex geometry of inductive components such as filter-integrated transformers is an additional prominent challenge. While there are some commercially available finite element simulation tools that provide loss calculations in time-domain for multi-dimensional geometries of magnetic materials, the principle of analysis is not fully disclosed and less flexible for engineers to use. In this paper, we introduce a comprehensive method for systematically and flexibly applying time-domain dynamic loss equations to geometric finite element methods in multi-dimensions. The developed post-process framework for magnetic core loss calculations is coded in an open-source programming language, Python, and verified by comparison with analytical solutions for a filter integrated isolation transformer under a variety of operating conditions. Parallel processing is used to deal with the large datasets associated with element-by-element numerical calculations in the time domain. A high level of accuracy is achieved and verified. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In gapped inductors, the fringing field of the air gaps causes additional eddy current losses in the windings and an increase of the inductance. Since this impact of the fringing field is very significant, calculating the additional eddy current losses and the inductance increase is important in the design of inductors. This article proposes analytical formulas to accurately calculate the inductance and the additional eddy current losses in gapped inductors with solid round wire and Litz wire windings. The analytical formulas are verified by measurements, showing that the proposed models are accurate over a wide-frequency range. [ABSTRACT FROM AUTHOR]

The design and optimization of coils for Inductive Power Transfer (IPT) systems is an iterative process conducted in Finite Element (FE) tools that takes a lot of time and computational resources. In order to overcome such limitations in the design process, new empirical equations for the evaluation of the self-inductance and mutual inductance values are proposed in this work. By means of a multi-objective genetic programming algorithm, the self-inductance, the mutual inductance and the coupling factor values obtained from FE simulations of IPT link are accounted by analytical equations, based on the geometric parameters defining the IPT link. The behavioral modeling results are compared with both FE-based and experimental results, showing a good accuracy.

Biomedical applications often require high-performance power supplies for diagnosis and treatment systems. In particular, modern electroporation techniques for cancer treatment require high-voltage generators with versatile waveform generation. In this context, sinusoidal waveform generation has been recently identified as beneficial for electrochemotherapy cancer treatments. This paper proposes the design of a high-voltage high-frequency arbitrary waveform generator taking advantage of Gallium Nitride (GaN) devices. The proposed converter has been designed and implemented, achieving a 1-MHz 2000-V output voltage. It has been electrically tested and applied to electrochemotherapy treatments in mice, demonstrating the feasibility of this proposal.

Development of power electronic converters tend to achieve high efficiency and at the same time high power density in many industrial applications. In recent years, with emerging third-generation semiconductor materials i.e. Silicon Carbide (SiC) and Gallium Nitride (GaN), the switching frequency of several MHz has become a widely studied frequency band, therefore traditional technology can no longer meet the demand, and many new challenges appear. This paper presents a comprehensive review of high frequency (HF) converters, the essential challenges are analyzed such as topology selection, soft-switching technologies, resonant gate drivers, magnetic components design and optimization.

Parametric transformers are magnetic components which employ a variable inductance to generate parametric oscillations in a secondary resonant tank. Power conversion with parametric transformer can provide constant output voltage regulation, short‐circuit protection, input over‐voltage and under‐voltage protection, and bidirectional filtering. In spite of these benefits, parametric transformers did only experience small scientific attention during the 1970s. Due to the low energy density and low efficiency of the topologies developed at the time, parametric transformers were discarded in favour of the more common power converters based on the magnetic amplifier. In spite of the great developments in power semiconductors, magnetic amplifier control still remains a competitive option in present‐day power electronic applications benefiting from its high robustness. This publication presents a new topology of parametric transformer based on permanent magnet (PM)‐inductors, presenting higher efficiency and higher energy density. Finite element method magnetics simulations are used to analyse the variable inductance mechanisms. A physical prototype is developed and tested empirically in an AC/DC power converter. The prototype verifies all the mentioned benefits of parametric power conversion, and presents an efficiency and energy density equivalent to presently employed solutions for voltage regulation, using power semiconductor magnetic amplifiers. [ABSTRACT FROM AUTHOR]

A conventional pulse frequency modulation (PFM) controlled LLC resonant converter requires a wide switching frequency operating range to regulate the output voltage. There are some disadvantages of PFM LLC resonant converters: (i) the design and optimisation of magnetic components and gate driver circuitry are challenging; (ii) due to the variable switching frequency operating range, electro‐magnetic interference performance of the converter is degraded; (iii) efficiency degradation; (iv) inability to achieve independent control in multiple‐output applications. To address the above‐mentioned problems and achieve fixed switching frequency operation, a variable magnetising inductance control (VMIC) strategy is proposed. In the proposed VMIC control strategy, the operating switching frequency of the primary switch is fixed and the duty cycle remains constant at 0.5. At the resonant frequency operating point, the output voltage is independent of both the magnetising inductance and load. In addition, the zero current turn‐off operation of the secondary rectifier requires that the switching frequency be designed below the resonant frequency. The operational principles and design considerations of the LLC resonant converter with VMIC are presented. Experimental results from a 200 W prototype are presented to validate the theoretical analysis and the effectiveness of the proposed VMIC control strategy. [ABSTRACT FROM AUTHOR]

This article studies design guidelines to optimize the inductive coils for electric vehicles by replacing the standard compact ferrite core with a compound of polymers, nanoparticles, and tile-links of ferrite and by reviewing different aspects of the winding to improve mechanical behavior and efficiency. A system composed of the studied vehicle assembly and ground assembly from the society of automotive engineers’ recommended practice is defined. Fast three-dimensional (3-D) finite element simulations are performed by evaluating different geometric aspects of the vehicle assembly. In doing so, the variation of coupling factor and inductance related to the geometry can be observed and compared in order to analyze the performance when the amount of compact ferrite is reduced. The polymer bonded magnetic is, then, incorporated to improve the decreased magnetic behavior due to the reduction in ferrite. In previous works, the modeling of the litz-wire and polymer bonded magnetic were developed to accelerate the simulations. In this article, we include the modeling of the compact ferrite tile-links to further reduce the time consumption of these simulations. Moreover, simple two-dimensional simulations are described to study the windings’ parasitic capacitances. The design guidelines, based on fast 3-D simulations, are detailed and validated with particular prototypes. [ABSTRACT FROM AUTHOR]

New compound magnetic material based on parallel continuous ferromagnetic microwires (e.g., based on cobalt) embedded in a body made of polymeric material can potentially offer significant mechanical advantages over well-known fragile ferrite in some applications where the magnetic material has to withstand mechanical vibrations. The diameter of the magnetic microwires is minimal (3–60  $\mu$ m) compared to the rest of the dimensions (80–300 mm) and the number of microwires is in the order of 1000 s. It requires extremely fine meshes, then brute force simulation by the finite element method is not possible. In this article, a method to overcome this limitation is proposed, which is based on the substitution of the original material by a homogenous material that behaves, in a macroscopic sense, as the compound material. The physical properties of the homogeneous material are obtained in different spatial directions, due to the inherent anisotropy of the compounded magnetic component, through analytical equations. [ABSTRACT FROM AUTHOR]

It is necessary to have a model to design magnetic gear (MG) optimally and to investigate the effective parameters on its performance. This study proposed a two‐dimensional (2D) model to predict the magnetic components of coaxial MG (CMG). This model is based on the mesh analysis method considering core nonlinear B‐H curve. In the proposed model, the radial and tangential components of flux densities, magnetic fluxes as well as the inner/outer rotor torque are estimated by extraction of the magnetic equivalent circuit (MEC). The effect of non‐linear B‐H magnetising curve is considered on the MEC model and it is compared with linear core (constant probability). Furthermore, the dynamic model of CMG is presented and its torque‐angle curve and consequently its pull‐out torque is obtained. To validate the proposed model, the 2D MEC model results are compared with results of finite element method analysis. [ABSTRACT FROM AUTHOR]

The near magnetic field emitted from magnetic components may generate electromagnetic interference (EMI) and degrade EMI filter's performance. This article discussed the near magnetic field emission from toroidal inductors. The emission mechanisms are analyzed for different inductor winding structures with either common-mode (CM) or differential-mode (DM) excitation. The winding structures with low near magnetic field emission are identified. A CM inductor structure is proposed to improve inductor's high-frequency CM performance and greatly reduce its near magnetic field emission due to DM currents. The improvements are achieved with a small extra toroid. The proposed structure can also increase CM inductor's DM inductance for DM noise reduction at the expense of a reduced DM saturation current. To avoid saturation, a design procedure is developed for the proposed CM inductor to achieve desired CM inductance, minimized near magnetic field emission, high DM inductance, and optimal magnetic flux density. Three-dimensional (3-D) finite-element analysis models were developed and experiments were conducted to validate the developed theory and techniques. EMI measurement results show that the proposed CM inductor has a better performance for both DM and CM noise reduction than a conventional CM inductor. [ABSTRACT FROM AUTHOR]

In this article, a method to replace conductors, in one or multiple layers, by an equivalent layer with homogeneous current distribution is proposed to allow complex 3-D finite element simulations. This equivalent layer needs a coarser mesh, then the simulations are accelerated. The electromagnetic properties of this equivalent layer will be defined to match skin and proximity losses of actual round and Litz-wire conductors. Analytical and empirical equations to obtain these parameters will be provided and the method is validated in several inductive power transfer coils with three dimensional geometries. [ABSTRACT FROM AUTHOR]

Sophisticated techniques are required for getting accuracy in high frequency power losses of magnetic. This paper presents a high frequency power loss measurement platform (full bridge) that provides accurate assessing of losses in magnetic components. This is obtained by a construction of a thermal shunt with radiator to measure the losses of the bridge. An aluminium strip is used as a 'thermal resistor'. Two negative temperature coefficient resistors measure the temperature drop across the aluminium strip. The magnetic device loss equals the DC input power of the platform minus the bridge loss. The copper loss can be estimated while using litz wire. Using litz wire windings with sufficiently low diameter of the strands allows neglecting eddy current losses, thus measuring only DC resistance is enough for calculating of copper losses. It can be checked by an RLC metre if the assumption is reasonable. The proposed approach and platform are verified by realisation and experiments with a full-bridge converter based on SiC switches and operating in frequency range of 50 kHz–1 MHz. The proposed platform can be used for obtaining the frequency dependence of core losses of magnetic materials. [ABSTRACT FROM AUTHOR]

The article considers the issues of additional extraction of iron and its oxidized compounds from steelmaking slags SC "Uzbeksteel". It is shown that after the separation of the magnetic components in the dump slags a significant amount of iron remains, the concentration of which is comparable to the poor iron ores of Uzbekistan. [ABSTRACT FROM AUTHOR]

To increase power density and simplify the process of integrating magnetic components to power electronics circuits, a commercial multiextruder paste-extrusion three-dimensional (3-D) printer was used to process both metal and magnetic pastes into 3-D structures of magnetic components. A magnetic-filled-benzocyclobutene composite, termed poly-mag paste, was formulated and used as a magnetic core feedstock for the printer, and a commercial nanosilver paste was used as a conductive winding feedstock for the printer. A toroid inductor was 3-D printed by using metal and magnetic pastes, and it was cured at 250 °C for a half hour without any external pressure to form the structure. The inductance of the 3-D-printed toroid inductor was measured to be 167–143 nH in the frequency range of 1 kHz to 3 MHz. The dc resistance of the winding was 0.1 Ω. These results are in good agreement with a finite-element analysis simulation. Both the winding and core magnetic properties can be improved by adjusting the feed paste's formulations and flow characteristics, and by fine tuning the printer parameters, such as motor speeds, extrusion rate, and nozzle sizes. [ABSTRACT FROM PUBLISHER]

In this paper, it is theoretically shown and experimentally verified that operation of switch-mode power supplies in burst mode (BM) results in lower audible noise than operation in frequency-foldback mode (FFM). However, the selection of the switching frequency in a burst package can have a significant impact on the audible noise. In both BM and FFM, the audible noise can be reduced by decreasing the peak value of current pulses and proportionally increasing the burst frequency in BM and the switching frequency in FFM. In BM, the audible noise can be further reduced if instead of increasing the burst frequency, the number of burst pulses is increased without changing the burst frequency. The presented BM and FFM audible noise analyses are experimentally verified on a dc–dc boost test circuit. [ABSTRACT FROM AUTHOR]

This paper presents novel single-phase pulse width modulation (PWM) ac-ac converters that can solve the commutation problem in single-phase direct PWM ac-ac converters without sensing the input voltage polarity. By using a basic switching cell structure and coupled inductors, the proposed ac-ac converters can be short- and open-circuited without damaging the switching devices. Neither lossy RC snubber nor dedicated soft commutation strategy is required in the proposed converter. By replacing the conventional phase-leg of the PWM ac-ac converters with the switching cell structure and the coupled inductor, three novel buck, boost, and buck-boost type PWM ac-ac converters are developed. Although two coupled inductors are required for the proposed converter, the input inductor of the proposed converter can be much smaller than that of the conventional PWM ac-ac converters. The volume of the magnetic components can be further reduced by increasing switching frequency of the converter because very fast recovery diodes can be selected externally. In order to verify performance and robustness of the proposed converter, a 200-W boost type prototype converter was built and tested with both mismatched gate signals and highly distorted input voltage. [ABSTRACT FROM AUTHOR]

In power electronics applications, magnetic components are often subjected to nonsinusoidal waveforms, variable frequencies, and dc bias conditions. These operating conditions generate different losses in the core compared to sinusoidal losses provided by manufacturers. In the conception and design stage, lack of precise losses diagnosis has unacceptable effects on system's efficiency, reliability, and power consumption. Since virtual prototyping is used to predict and improve system's behavior before realization, losses and behavior prediction of components is possible. Circuit simulators and their compatible components models are required. This paper is summarized by proposing nonlinear dynamic model of powdered material magnetic core for use in circuit simulators. It includes the material's nonlinear hysteresis behavior with accurate winding and core modeling. The magnetic component model is implemented in circuit simulation software “Simplorer” using VHDL-AMS modeling language. Waveforms and losses of a powder core inductor in a buck converter application are simulated and compared to measured ones. The model is validated for different ripple currents, different loads, and a wide frequency range. DC bias is taken into account in both continuous and discontinuous conduction modes. [ABSTRACT FROM AUTHOR]