Reduce Eddy Current Loss Research Articles

The role of Cr in optimizing properties of Fe–B–C–P–Si–Mo–Cr metallic glasses for applications

With the rapid development of third-generation semiconductors, there is an urgent need to develop high-performance soft magnetic Fe-based metallic glasses tailored particularly for their high-frequency applications. In this work, new Fe76−yB7C7P7Si3Moy−xCrx (y = 0, 1, 2, 3 at.%, x ≤ y) alloys with relatively high glass-forming ability (GFA) were developed. The effects of replacing Mo with Cr on GFA, thermodynamic properties, soft magnetic properties, electrical resistivity (ρ), and corrosion resistance at different Fe contents were systematically studied. The possible causes of GFA variation were discussed. The results show that the addition of a small amount of Cr replacing Mo under different Fe contents would not lead to a decrease in GFA. The critical sizes of Cr-containing glassy alloys are 1–2.5 mm. These alloys possess relatively high saturation magnetization (Ms) of 1.29–1.41 T and lower coercivity (Hc) of 0.7–1.8 A/m, contributing to the reduction of hysteresis loss. In addition, Cr increases ρ of the alloys, reaching up to 162 μΩ cm, which is beneficial to reducing eddy current loss at high frequency. Furthermore, Cr effectively enhances corrosion resistance, thereby increasing the service life of the alloys in harsh environments. The role of Cr in these aspects makes it a beneficial element in soft magnetic metallic glasses for high-frequency applications.

Co-hydrolysis of TEOS and DDS to obtain a modified hydrophobic SiO2 insulation layer for FeSiBC amorphous magnetic powder core with low energy loss

The hysteresis effect and eddy currents caused by alternating magnetic fields greatly impede the improvement of the working efficiency and performance stability of soft magnetic powder cores. In this work, modified hydrophobic SiO2 nanoparticles were prepared by tetraethyl orthosilicate (TEOS) and dimethyl-diethoxy-silane (DDS) as co-precursors through sol–gel methods. The effect of different proportions of DDS and TEOS on the amorphous magnetic powder cores performance was studied. It was demonstrated that the insulation layer in DDS and TEOS co-precursors hydrolyzed composite powders exhibited more uniform distribution compared with TEOS hydrolyzed alone counterpart. The introduction of methyl groups reduced the accumulation of hydrolysis intermediates on the surface of FeSiBC powders. Furthermore, the addition of DDS reduced eddy current loss significantly with a low hysteresis loss. The total energy loss of the DDS and TEOS co-hydrolysis powder core were reduced by 16.1 % and 7.7 % at 1 MHz, 0.05 T compared to the uncoated powder core and the TEOS hydrolysis alone counterpart, respectively. The presented results provide insights into improving the application range and energy utilization efficiency for the magnetic powder cores.

Potential of powder metallurgical methods to fabricate Fe-6.5Si soft magnetic components

The soft magnetic Fe-6.5Si alloy is well known for its excellent soft magnetic properties but its usage is limited due to fabricational constrains by conventional methods. Powder metallurgical processing of Fe-6.5Si is possible by a variety of different methods shown here, sinter-based screen printing (SP), electron beam powder bed fusion (E-PBF) and field-assisted sintering (field-assisted sintering/spark plasma sintering, FAST/SPS). The microstructure of the components varies strongly by process and powder used which is directly influencing their soft magnetic properties. The correlation between powder properties and processing parameters on the structural and magnetic properties is established. Lowest coercivity ( H c = 7 A m−1) is achieved by E-PBF due to large grain size minimising hysteresis losses necessary for direct current applications. SP can provide sheets with low coercivity ( H c = 21 A m−1) and adjustable thickness reducing eddy current losses especially suitable for alternating current application at higher frequencies. FAST/SPS can be used for a large range of powder particle sizes which is suitable to tune the soft magnetic properties in a wide range between 40 and 210 A m−1.

Ultralow-loss soft magnetic composites with temperature-resistant and insulated Al2O3/SiO2 layers through pyrolysis

Soft magnetic composites (SMCs) with low power loss are urgently needed to meet the increasing demand for high frequency and miniaturized inductors and transformers. Ultrathin cladding with good insulation and high temperature resistance is the key to achieve low-loss SMCs. In this study, we used MQ silicon resin as precursor to produce in-situ grown Al2O3/SiO2 composite insulating layer in FeSiAl SMCs through pyrolysis process and high-temperature reaction. The morphologies, microstructures and compositions of the coatings on the surface were characterized by SEM, TEM, EDS, TG, XRD, FTIR and XPS, and the results show FeSiAl powders are evenly and entirely covered with an inner Al2O3 and outer SiO2 composite insulating layer. The results of powder resistivity show that the insulating layer still maintains very high resistance after annealing at 750 °C. The composite insulating layer had high resistivity and reduced eddy current loss, while the high temperature annealing process reduced stress and defects and resulted in low hysteresis loss. The best magnetic properties were obtained from samples coated with 2.0 wt% MQ and annealed at 750 °C, with an effective permeability of 76 and the lowest power loss of 72.2 mW/cm3 at 50 mT/100 kHz, 88.5 mW/cm3 at 100 mT/50 kHz and 304.1 mW/cm3 at 100 mT/100 kHz.

A new approach in the implementation of insulating layers in soft magnetic composite materials

Soft Magnetic Composite (SMC) materials show a high potential for growth in the electrification of several industrial sectors for two main reasons: the reduced eddy current losses and the 3D magnetic path which allows to redesign magnetic circuits without geometrical constraints. On the other hand, some material limitations and process restrictions limit the use of SMC on a large scale; this contribution aims to overcome such constraints through a novel surface approach using a Layer-by-Layer (LbL) technique that allows to coat each particle with a nanostructured layer, providing electrical insulation enhanced mechanical strength and withstanding higher treatment temperatures. Four SMCs encompassing the developed innovative multi-functional layers have been prepared and deeply analyzed with a characterization campaign through the study of the surface morphology with a Scanning Electron Microscope (SEM), the magnetic properties with a Single Sheet Tester (SST) and the mechanical strength through the “Transverse Rupture Strength” (or TRS) test. The discussion on the results has to be considered a starting point for future investigations, as each of the four different systems represents a partial solution to a specific SMC problem. Also, some considerations on the possible application are proposed.

Investigation of structural, electrical and thermoelectric properties of cobalt-zinc ferrites/graphene nanocomposite

The present work was related to synthesis of graphene (0, 1.25 and 2.5 %) incorporation in cobalt-zinc ferrites by using sol–gel auto combustions method. The face center cubic (FCC) crystal structure and crystallite size varies from 16 to 18 nm was examined by XRD analysis. While as the irregular, non-uniform and flake like surface morphology of cobalt zinc/graphene nanocomposite (Co-Zn-G NCs) were observed via SEM images. In addition, the phase identification and presence of different functional groups such as M−O (metal oxide), OH, C-C, C = O and C = C were investigated by Raman spectroscopy and FTIR analyses. Further, I-V two probe method was used to observed the resistivity decrease (7.5x 108 to 2.5x 106 ohm-cm) and conductivity increased (1.2x10-9 to 3.8x10-7S/cm) of Co-Zn-G NCs. After that the thermoelectric behavior of Co-Zn-G NCs indicated that due to increase the temperature then seebeck coefficient decrease as vice versa. The overall result shows that the 2.5 % graphene incorporation in Co-Zn ferrites expressed the excellent electrical and thermoelectric properties. In future the Co-Zn-G nanocomposite used for the development of temperature sensor, reduce eddy current loss and spintronic devices.

Research on Transient Electromagnetic Field and Eddy Current Losses Reduction in End of Large-Capacity Synchronous Condenser During UHVDC System Faults

Research on Transient Electromagnetic Field and Eddy Current Losses Reduction in End of Large-Capacity Synchronous Condenser During UHVDC System Faults

Improved design and analysis for electromagnetic performance of magnetic geared permanent magnet machine according to winding pattern and segmentation of permanent magnet

This paper presents an analysis of the operating principle of magnetic geared permanent magnet machines (MGPMMs), electromagnetic analysis results according to the winding pattern, and a method for improving power factor and loss characteristics. To improve electromagnetic performance, the air gap magnetic flux density was calculated using the finite element method, and the harmonics of the inner and outer air gap magnetic flux densities was analyzed using the fast Fourier transform (FFT). From the FFT results, harmonic orders that affect electromagnetic performance were presented, and the electromagnetic analysis results were compared to derive correlations with torque ripple and losses. In addition, a design method for improving electromagnetic performance and operating characteristics was proposed by comparing power factors according to winding pattern. In particular, to improve the robust design and efficiency of MGPMM, a method of reducing eddy current loss by segmenting permanent magnets was addressed. The proposed analysis and design method can be widely used in the design and characteristic analysis of MGPMM.

Unequal Thickness Flat Wire Winding-Based Eddy Current Loss Reduction for Coreless Axial Flux Permanent Magnet Synchronous Machine Adapted to Extended-Range Electric Vehicles

Unequal Thickness Flat Wire Winding-Based Eddy Current Loss Reduction for Coreless Axial Flux Permanent Magnet Synchronous Machine Adapted to Extended-Range Electric Vehicles

Reduction of power loss in easy-plane FeSi soft magnetic composite under a weak bias magnetic field

This paper investigates the impact of a weak bias magnetic field (Hbias) along the easy magnetization plane direction on the power loss of easy-plane Fe-6.5 wt%Si (FeSi) soft magnetic composite (SMC). The results demonstrate that the power loss (Pcv) decreases by 18 % when the Hbias is 11.6 kA/m. Furthermore, it is found that the reduction in Pcv is not only attributed to decreases in hysteresis loss but also involves a decrease in excess loss. The causes of hysteresis loss and excess loss reduction are further investigated and it is found that the effect of the Hbias on the magnetization state plays an important role in the reduction of hysteresis loss. Additionally, the decrease in excess loss can be attributed to the reduction in local eddy current losses caused by non-uniform domain wall motion. These findings provide valuable insights for achieving high-frequency (MHz), high-efficiency, and miniaturized power electronic devices.

A Study on Eddy Current Reduction Shape of Single-Phase Claw-Pole Motor

The claw-pole motor, known for its simple structure, is widely used in various fields due to its cost competitiveness. However, a drawback of the fixed-stator-type claw-pole motor is its vulnerability to eddy current losses. Therefore, this paper presents a single-phase claw-pole motor applied as a motor for cooling fans, with the aim of reducing eddy current losses and improving performance based on shape optimization, ultimately resulting in a single-phase claw-pole motor that meets the desired performance. The validity of this approach is verified through 3D finite element analysis (FEA).

PM Eddy-Current Loss Reduction of Axial Flux PM Wheel Motor With Arc Incompletion Segmentation

The high permanent magnet (PM) eddy-current loss will inevitably cause the risk of irreversible demagnetization, and the PM complete segmentation (CS) method is a common method to reduce the PM eddy-current loss. However, PM CS design will increase the cost and difficulty of assembly process, especially for axial flux PM (AFPM) machines. To address this issue, a new arc incompletion segmentation (AIS) method is proposed to reduce the PM eddy current loss and cost, including double-side AIS and single-side AIS designs. Then, some of the key parameters are optimized. In addition, the PM eddy current loss, cost, and torque performance are studied and compared with different segmentation methods under different conditions based on 3-D finite element method (FEM). Finally, two different 25kW prototypes are manufactured and tested to validate the proposed method and analysis.

Preparation and magnetic properties of high DC-bias performance Fe-Si-Nb-B-Cu/carbonyl iron chip inductors

In this study, a gradient temperature rise technique was employed to prepare ultra-fine nanocrystalline alloy magnetic powder with excellent high-frequency and low-loss characteristics. It was found that increasing the holding time effectively refines the grain structure in the perpendicular direction of the Fe-Si-Nb-B-Cu alloy's (220) crystal plane. This refinement contributes to a reduction in eddy current losses within the soft magnetic composite material. The addition of carbonyl iron to the nanocrystalline magnetic powder resulted in further enhancements in the density, strength, and magnetic properties of soft magnetic composites under high-frequency magnetic fields. Consequently, soft magnetic composites exhibiting superior DC bias performance were successfully obtained, with a power loss of 2629.50 kW/m3 at a magnetic induction of 20 mT and a frequency of 3 MHz, and more than 70 % percent permeability in a DC biased magnetic field of 7.96 kA/m. The relationship between relative permeability and quasi-static hysteresis loops was established. Additionally, the dynamic hysteresis loops of the soft magnetic composites revealed a relaxation phenomenon, which elucidated the mechanism behind the variations in power loss with changes in magnetic induction strength and frequency. Finally, through simulations, it was determined that the number of turns and the winding method significantly influenced the internal magnetic field and inductance of the chip inductor. Utilizing this information, a chip inductor with ultra-small inductance, compact size, and excellent DC bias characteristics for 10 A circuits was successfully fabricated.

Prospects of Using Fe-Ga Alloys for Magnetostrictive Applications at High Frequencies

Fe-Ga is a promising magnetostrictive rare-earth free alloy with an attractive combination of useful properties. In this review, we consider this material through the lens of its potential use in magnetostrictive applications at elevated frequencies. The properties of the Fe-Ga alloy are compared with other popular magnetostrictive alloys. The two different approaches to reducing eddy current losses for such applications in the context of the Fe-Ga alloy, in particular, the fabrication of thin sheets and Fe-Ga/epoxy composites, are discussed. For the first time, the results of more than a decade of research aimed at developing each of these approaches are analyzed and summarized. The features of each approach, as well as the advantages and disadvantages, are outlined. In general, it has been shown that the Fe-Ga alloy is the most promising magnetostrictive material for use at elevated frequencies (up to 100 kHz) compared to analogs. However, for a wide practical application of the alloy, it is still necessary to solve several problems, which are described in this review.

A Novel Sleeve Design to Reduce the Eddy Current Loss of High-Speed Electrical Machines

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying the retaining sleeve to the rotor is essential. However, when using sleeves, there is a problem of reducing efficiency due to eddy current loss. In this paper, a study was conducted on a motor for a 100 kW building air conditioning system operating at a speed of 20,000 rpm. The purpose of the study is to reduce eddy current loss by optimizing the sleeve geometry. To this end, 3D finite element analysis (FEA) using JMAG 22.1 was conducted to analyze eddy current loss, the minimum safety factor was analyzed through mechanical stiffness analysis using ANSYS Workbench, and the validity of sleeve shape was proved through cause analysis. Through the research results, it is expected that the shape change of the sleeve will have the effect of reducing eddy current loss.

Investigation of an unconventional exciter of a toothed stator using software by the finite element method

In this article we investigate an unconventional design of an exciter having a toothed stator. The main purpose is to check whether the proposed machine can meet the operating parameters specified in the specification. This chapter begins with a description of a current exciter with protruding poles and a description of a design with teeth. The toothed stator is also distinguished by being made of an inexpensive ferromagnetic material such as cast iron. When choosing cast iron, they are guided by the fact that it is already used in industry in other components of alternators, such as bearings and some connecting bushings. The use of cast iron also reduces eddy current losses compared to solid steel parts. Since the path of the magnetic flux in the stator is three-dimensional, the study is carried out using software for 3D finite element calculation. The model of the machine is compared with the experimental results obtained on the layout. Then we make changes to the geometry of the machine to improve its characteristics. In conclusion, we present the balance of active substances of the gear structure and the balance. The obtained results allow us to establish a good consistency of the finished element model with the test results.

Microstructure and magnetic properties of the FeSiAl soft magnetic composite with a NiFe2O4-doped phosphate insulation coating

Novel FeSiAl soft magnetic composites (SMCs) with a phosphate insulation coating doped with magnetic NiFe2O4 nanocrystalline particles were prepared. They exhibited high permeability, ultra-low loss, and high thermal stability. The saturation magnetization of the FeSiAl SMC increased, while the coercivity decreased due to the exchange coupling of the magnetic nanocrystalline particles. The total loss of the novel SMC decreased to 139.93 kW/m3 at 100 mT and 100 kHz, which is only one-third of that of common commercially available Sendust composites, while the permeability was up to 62 for the reduced demagnetization field. Furthermore, three-dimensional loss separation was performed based on the nonlinear regression method, and the complex permeability was separately addressed as the domain-wall movement and spin resonance parts. The minimum total loss was ascribed to the significantly reduced hysteresis loss and the slightly reduced eddy current loss, corresponding to the low coercivity (Hc = 0.341 Oe) and high impedance (|Z| = 67.1 MΩ). This was attributed to the improved magnetic properties and resistance of the insulation coating, which was related to the magnetic nanoparticles embedded in the insulation coating. The permeability was mainly derived from the spin resonance due to the complete insulation coating and ultrafine particles. This novel SMC with a phosphate insulation coating doped with magnetic NiFe2O4 nanocrystalline particles provides a high-efficiency, high-frequency, and high-saturation soft magnetic device for switching power supplies, photovoltaic inverter boost inductors, and other applications.

Ultra-low core loss FeSiAl soft magnetic composites with in-situ double oxidation layers of outer Fe3O4 layer and inner super-thin Al2O3/SiO2 hybrid layer

How to synchronously reduce eddy current loss and hysteresis loss still remains a challenge for achieving low core loss of soft magnetic composite (SMC). In-situ surface oxide effectively combines the formation of insulating layer and the release of internal stress during the molding process. In this study, FeSiAl SMC has been fabricated by powder metallurgy method with in-situ oxidated FeSiAl powder, in which FeSiAl powder are covered by outer Fe3O4 insulating layer and inter super-thin Al2O3/SiO2 hybrid layer. Fe3O4 layer alleviates dilution magnetic effect, ensuring high saturated magnetization and effective permeability. The super-thin Al2O3/SiO2 hybrid layer enhances electrical resistance, reducing eddy loss. Effects of the in-situ oxidation time on insulating layer and soft magnetic performances of SMC are investigated in detail. Synchronous reduction of eddy current loss and hysteresis loss is achieved through high resistance accompanied with proper insulating layer thickness and low coercive force provided by the special microstructure. For powder with 90 min oxidation at 500 °C, core loss of SMC is low up to 64 mW/cm3 at 50 mT and 100 kHz and 363 mW/cm3 at 100 mT and 100 kHz, while the permeability is kept at 50 until 1100 kHz and is stable until 140 °C. Meanwhile, DC bias performance reaches 51.2% at 100 Oe applied field and Q value is 104.8 at 400 kHz.

Design Optimization of Four-Layer Fraction Slot Concentrated Winding Spoke-Type Interior Permanent Magnetic Machine for Range Extender

<div>In this article, the design optimization of a four-layer fractional slot concentrated winding (FSCW) interior permanent magnet (IPM) machine for range extender is proposed for high energy efficiency and excellent torque/back-electromotive force (EMF) performance. The design starts with the comparison of four-layer FSCW patterns in terms of efficiency distribution based on a predesign spoke-type rotor model. Magnet segments and rotor auxiliary notches (ANs) are applied and optimized to reduce eddy current losses and torque ripples in the permanent magnets (PMs). Then, an efficient two-step optimization of multiple performances for a machine is presented. The rotor parameters are designed by an analytical model with a Pareto optimizer for torque capacity and ripple. An interpolation-based design method for adaptive stator slot parameters and winding configurations is presented to quickly obtain the optimal stator slot winding designs corresponding to the rotor design to achieve optimal efficiency. The multi-bridge design is applied to rotor laminations to suppress flux leakage, making the rotor core easy to manufacture. Finally, an 18s-16p four-layer FSCW prototype was built and tested to verify the design optimization results, with a maximum efficiency of 96% and rated shaft ripple as low as 3%.</div>

Selective oxidation of rare metal oxide insulation layers on particle substrates for optimizing the performance of FeSiCr-based soft magnetic composites

This study introduces an approach to fabricating soft magnetic composites (SMCs) that effectively address core loss while maintaining high magnetic conductivity. During the sintering process in a water vapor environment, the CeO2 insulation layer facilitates the selective oxidation of Si while simultaneously impeding the outward diffusion of Fe and Cr. Consequently, a CeO2·SiO2 composite insulation layer forms within the FeSiCr-based SMCs. The FeSiCr-based SMCs with the CeO2·SiO2 composite insulation layer achieve a saturation magnetization of 153.1 emu/g, which is 10.9% lower than that of FeSi3.7Cr4.5 compacts, and exhibits a deterioration rate lower than previously reported values. Moreover, the permeability of the FeSiCr-based SMCs remains highly stable, demonstrating outstanding insulation characteristics. The total core loss and core loss separation results further corroborate that incorporating a CeO2·SiO2 composite insulation layer leads to a more pronounced reduction in interparticle eddy current loss than using a CeO2 insulating layer alone. This performance enhancement can be attributed to the selective oxidation of a rare metal oxide insulation layer on a ferromagnetic metal particle substrate, a technique applied to SMCs for the first time. These findings hold significant implications for the design of high-performance SMCs in miniaturized and lightweight electromagnetic devices.