Soft Magnetic Composite Material Research Articles

Development of soft magnetic composites for magnetized pavement to improve the efficiency of electric vehicle's wireless power transfer

Integrating the wireless power transfer (WPT) system into the pavement is an effective way to solve the inconvenience of electric vehicles (EVs)’ charging, accelerating the growth of ownership of EVs to achieve net carbon zero in transportation. However, the existence of a cement paving layer between coils was a negative impact factor. Here, two types of ferrite powders were separately mixed into the cement to prepare soft magnetic composite (SMC) material to enhance the coupling degree of coils. The magnetic and mechanical performance of the composite were tested by a vibrating sample magnetometer and compressive and flexural strength tester. Furthermore, to explore the optimal layout of the magnetized pavement structure, nine pavement layouts were designed based on the distribution of magnetic flux. Finally, the effect of SMC material on improving the charging performance was verified by WPT system test platform. Results showed that the Ni–Zn ferrite powder exhibited superior magnetic permeability due to its stronger magnetic moments and lower magnetic domain wall energy compared to Mn–Zn ferrite powder. The peak relative permeability of SMC materials reached 14.370 with an equal mass ratio of Ni–Zn ferrite powder to cement. Conversely, optimal strength was attained with a Mn–Zn ferrite to cement ratio of 0.2, resulting in a compressive strength of 36.0 MPa and a flexural strength of 4.0 MPa. Strategically placing SMC within the pavement, both in the core's interior and exterior to the coil, enhanced the coupling coefficient of coils, thereby improving the transmission efficiency of the WPT system. The incorporation of Ni–Zn ferrite powder in a 1:1 mass ratio to cement materialized the highest efficiency. Nonetheless, considering the mechanical performance, the SMC material with a 0.6 mass ratio of Mn–Zn ferrite powder to cement was recommended for magnetized pavements. The WPT system test results showed a transmission efficiency of 89.78% when utilizing magnetized pavement, surpassing the efficiency with the whole pavement material by 1.36%, which indicated great value and potential in energy conservation and carbon reduction of employing magnetized pavement in WPT technology.

High permeability Fe@SiO2@ Mn0.5Zn0.5Fe2O4 soft magnetic composite (SMC) materials which formed via high temperature in-situ reaction

The permeability of the Fe Soft Magnetic Composite (SMC) materials need further improve to broaden their application prospect. This research work presents a novel high permeability SMC material which has a low core loss (Pcv). The Fe particles formed an elongated strip shape structure through the ball milling process, and the high permeability Mn0.5Zn0.5Fe2O4 ferrite phase was formed around the elongated strip shape Fe particles via a high temperature in-situ reaction process (ZnO+MnO+Fe2O3—Mn0.5Zn0.5Fe2O4). While the added high resistive SiO2 phase aggregated at the long strip shape Fe particle outer surface and effectively increased the resistivity of the SMCs. As the percentage of the Mn0.5Zn0.5Fe2O4 ferrite coating increase, the permeability of the double layer coated SMCs gradually increased from 38 for the 1wt% Mn0.5Zn0.5Fe2O4 coated SMCs to 170 for the 18 wt% Mn0.5Zn0.5Fe2O4 coated SMCs. The 3wt% Mn0.5Zn0.5Fe2O4 coated SMCs has the lowest core loss (Pcv) of 86.9W/kg at 10mT, 500 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.

Chemical surface modification for the preparation of MgO cladding to enhance magnetic properties of Fe-Si-Nb-B-Cu nanocrystalline soft magnetic composites

This study employed chemical synthesis and decomposition techniques to fabricate MgO insulation coating on the surface of nanocrystalline soft magnetic powder. It was found that this coating effectively suppresses the time lag effect in the magnetization process of soft magnetic materials under high-frequency alternating magnetic fields, consequently reducing the overall losses of soft magnetic composite materials by mitigating the time-dependent effects during magnetization. Specifically, at an MgO content of 0.8 wt%, the power losses of nanocrystalline soft magnetic composite materials decreased from 519.13 kW/m3 and 3665.78 kW/m3 to 277.69 kW/m3 and 2718.3 kW/m3 respectively, under alternating magnetic fields with magnetic induction strengths of 20 mT and frequencies of 1 MHz and 3 MHz. The MgO insulation coating effectively mitigated the relaxation phenomenon in the dynamic hysteresis loops of nanocrystalline soft magnetic composite materials within dynamic magnetic fields, reducing the adverse effects of internal eddy currents in high-frequency alternating magnetic fields, thereby confirming the close relationship between magnetic hysteresis losses and eddy current losses in soft magnetic composite materials. Additionally, with the increase in MgO content, there was a significant improvement in the quality factor of nanocrystalline soft magnetic composite materials, showing a decreasing trend in the imaginary part of the complex permeability, which reflects the magnitude of power losses. Furthermore, the positive response of MgO coating in enhancing DC superimposition performance and reducing inductance impedance values has been validated, underscoring its crucial role in improving the stability of circuit systems.

Physical simulation and computational modelling for validation of soft magnetic composite impeder performance

Induction tube welding systems utilize an internal magnetic flux controller (impeder) to improve process efficiency. Work has previously been done showing that soft magnetic composite (SMC) materials may be suitable to improve these systems. A test stand was devised for the physical simulation of SMC impeder performance for use in induction tube welding systems. Tests were run to determine the loading and cooling conditions in which an impeder core made of SMCs could survive. Additionally, 2D thermal simulations were run to determine the cooling system thresholds given a particular magnetic loading of the core. The goal of these tests was to expand the design envelopes in which impeder cores made of SMCs could survive and validate their use in induction tube welding systems.

Finite Element Analysis of SMC Core Magnetic Gear for Vehicle Powertrain Systems

The utilization of gears as intermediary components for power transmission in electric drive systems addresses the insufficiency of electric machines in handling torque loads effectively. Gears, commonly employed in the industry, can be either mechanical or magnetic, allowing for the balanced transfer of torque and speed at specified ratios. The mechanical and electrical actuation of in-vehicle accessories persists both in traditional and next-generation vehicles. Particularly concerning safety and the sustainability of spare part production and supply, various electrical accessories continue to operate at the 12 V level in modern vehicles. In this context, the use of the Lundell alternator (claw pole) also continues in next-generation vehicles. While the mechanical accessories are driven by a belt-pulley system connected to an internal combustion engine in conventional vehicles, in next-generation vehicles, both belt-pulley systems and x-drive by wire are present. The low efficiency and operational costs of belt-pulley power transmission systems necessitate the adoption of more efficient transmission systems. This study focuses on the development of a soft magnetic composite (SMC) core magnetic gear power transmission system that can serve as an alternative to belt-pulley systems in both traditional and next-generation vehicles. In the proposed system, mechanical power transfer to the Lundell alternator is realized through the intended magnetic gear. The gear ratio is determined to ensure a speed of 1800 rpm at the input of the Lundell alternator while the drive system operates at 6000 rpm. To achieve low volume and high efficiency for the proposed magnetic gear, the SMC material is considered, and a comprehensive analysis using the Ansys Maxwell finite element software is conducted. As a result of the analyses, in the magnetic gear designed with a transmission ratio of 3:1, when a torque of 11.7547 Nm is applied to the input shaft, a torque transmission of 35.9806 Nm has been achieved with an efficiency of 84.73% through the output shaft.

Hydroxyethylidene-1,1-diphosphonic acid surface treatment as insulation technology for iron based soft magnetic composites

In this study, we employed HEDP surface treatment as an insulation coating technology for the preparation of iron-based soft magnetic composites. The coating layer primarily comprises metal chelate, alongside minor quantities of iron oxides and hydroxides. The influence of treatment time on the microstructure, corrosion resistance and electromagnetic properties of the soft magnetic composites is investigated. The findings indicate a substantial enhancement in the corrosion resistance of iron powder treated with HEDP, and the iron powder subjected to a 90-minute treatment exhibited the most uniform and dense coating, yielding optimal magnetic properties. Notably, the sample's loss after a 90-minute treatment is recorded at 360.6 mW/g, indicating a remarkable reduction of 66.88 % when compared to the untreated sample. This research offers a straightforward and cost-effective approach for the industrial-scale production of soft magnetic composite materials with exceptional magnetic characteristics.

Research on a Transverse-Dislocated Magnetic-Field Modulated Brushless Contra-Rotating Machine Adopting Different Core Material Combinations

This article proposes a transverse-dislocated magnetic-field modulated brushless contra-rotating machine (TDMFM-BCRM) with multiunit structure for the contra-rotating propulsion system. Compared with the existing contra-rotating machines, it has the advantages of equal and opposite torque at any time, no brushes and no slip rings. The improved three-dimensional (3D) magnetic-field modulation principle by considering multiunit structure of the TDMFM-BCRM is investigated. Then, due to the structural complexity of the TDMFM-BCRM, there are some challenges about its manufacturing. Therefore, the performance of the TDMFM-BCRM adopting different core material combinations including electrical steel (ES) and soft magnetic composite (SMC) material is investigated. Meanwhile, a prototype is manufactured and tested to validate the theoretical analysis, finally more manufacturing methods for the TDMFM-BCRM are comparatively studied.

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.

Evaluation of microstructure, mechanical and magnetic properties of laser powder bed fused Fe-Si alloy for 3D magnetic flux motor application

Since their high power-to-volume property, electric machines with 3D magnetic flux (3D-flux) structure are of great current interest. In them, the flux path is typically achieved by utilizing a soft magnetic composite (SMC) material to minimize the eddy current losses. Here, laser powder bed fusion (LPBF) technique is employed to manufacture a soft magnetic core (Fe-3.5 wt%Si alloy) with the following advantages: i) the (001) texture of Fe-Si alloy is well aligned with the Z direction of the 3D-flux path, which is the easiest magnetization direction in the cubic system; ii) the strength and ductility of the annealed alloy are far superior to those of SMCs. The alternating-current ring method was employed to measure the magnetic properties and a simulation of the 3D-flux electric machine was conducted. The results illustrated that the rotary torque generated with the additively manufactured alloy is 19.1% higher than that of SMCs in the weak magnetic field excited by ferrite at the 50 Hz frequency. However, it is important to note that the additively manufactured alloy also exhibited higher total iron loss in strong magnetic field and high electric frequency, indicating a need for further research to optimize the microstructure and reduce losses for medium/high frequency applications.

Energy loss and hysteresis of reversible magnetization processes in iron-based soft magnetic composites

The paper focuses on investigation of the hysteresis originating from the reversible magnetization processes and the quantification of the corresponding energy dissipation, on soft magnetic composite materials differing in various parameters so exhibiting different proportions of magnetization processes types during quasi-static magnetizing reversal under different maximum inductions. It was confirmed that reversible magnetization processes show hysteresis too and generate energy losses. These losses come from frictional effects accompanying local rotations of spins at the microscopical view of all magnetization processes including the reversible ones. It was found that the area of a hysteresis loop obtained by the integration of reversible permeability reveals approximately the proportion of reversible magnetization vector rotations, which produce energy loss much more than reversible domain wall displacements.

Design and Performance Analysis of Permanent Magnet Claw Pole Machine with Hybrid Cores

Permanent magnet claw pole machine (PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for high speed operation. However, because of its complex irregular structure, the manufacturing process using silicon sheets is complicated. Soft magnetic composite material (SMC) is manufactured by powder metallurgy technology, which can produce various shapes of stator core structures, so it is easier to produce various irregular shapes of the stator core. However, the raw SMC material is relatively expensive, and the mechanical strength of SMC is weak. In this paper, a PMCPM with hybrid cores is proposed. With the adoption of hybrid silicon sheet — SMC cores and amorphous alloy — SMC cores, the torque ability of PMCPM can be improved greatly and it can have higher efficiency for more wide operation frequency. Meanwhile, its mechanical strength has been improved and it can be designed for high torque direct drive applications as it is a modular machine. Furthermore, three methods are proposed to reduce the additional eddy current loss which resulted from the employment of hybrid cores in PMCPM.

Magnetic properties of Fe/parylene soft magnetic composites prepared via chemical vapor deposition

Iron-based soft magnetic composites with different contents of parylene were prepared by chemical vapor deposition (CVD), though this method, the edges and spikes can be coated with parylene. The morphology and magnetic properties of the materials are investigated. The self-lubricating parylene forms a thin and uniform insulating layer on the surface of iron particles, which reduces the magnetic loss of soft magnetic composite materials. The 4% parylene coated iron powder has high compression density, low hysteresis loss, excellent insulation performance, high resistivity and low eddy current loss. Compared with silicone resin and epoxy resin, the insulating layer formed by prylene has fewer holes and gaps, and the magnetic core loss is smaller.

Quantitative comparison of low-cost electrical machines with soft magnetic composite and ferrite magnet materials

Because of its special structure and manufacturing process, the soft magnetic composite (SMC) material has shown its advantages over silicon sheets, including magnetic and thermal isotropy, low high-frequency core loss, low material wastes during its manufacturing process, etc.. Considering the price of SMC raw material can be very cheap in the future, it is an ideal material for developing the low-cost electrical machine. Combined with SMC cores and low-cost ferrite magnets, some electrical machines with SMC and ferrite magnets for low-cost applications were developed in the past decades, which include the transverse flux flux switched permanent magnet motor (TFFSPMM), axial flux claw pole permanent magnet motor (AFCPM), axial flux vernier motor (AFVM), dual rotor axial flux permanent magnet motor (DRAFM) and axial radial flux permanent magnet motor (RAFM). To better utilize SMC material, all these machines are designed following the design guidelines of SMC machines. Though both of them with good performance for low-cost applications, it is necessary to know the main advantages of each machine. The main target of this paper is to compare these machines quantitatively. For obtaining the comparison results fairly all these machines are optimized by using the sequential robust Taguchi method. Finally, it can be seen that the AFVM and TFFSPMM are with relatively high torque ability and the DRAFM is with high efficiency and power factor ability.

Characterization and calculation of losses in soft magnetic composites for motors with SVPWM excitation

This study investigates the impact of space vector pulse width modulation (SVPWM) voltage excitation on the magnetic properties and losses of soft magnetic composite materials (SMCs) used in motors. This research aims to comprehend how SVPWM voltage excitation affects the magnetic properties and losses of SMCs. SVPWM voltage waveform has apparent voltage harmonics that can affect the core losses of soft magnetic materials. To measure the magnetic properties of SMCs, a test system is established that uses a range of carrier frequencies from 0 kHz to 100 kHz during SVPWM voltage excitation. The test results show that the hysteresis loop of SMCs exhibits minor loops on the major loop, which results in at least a 5.554% increase in losses when compared to sinusoidal excitation. To better predict and understand these losses, a neural network-based model is proposed for estimating losses under SVPWM excitation in SMCs. The proposed model optimizes the application of SMCs in motors and can contribute to the optimization of motor design.

Wide induction range analysis of DC magnetic properties and magnetization processes of Fe-based soft magnetic composites

The paper presents systematic analyses of a wide maximum induction range (0.001 T–1.4 T) DC magnetic properties of iron-based soft magnetic composite (SMC) materials by applying different methods to understand the specific features of magnetization reversal of this increasingly popular class of soft magnetic materials, including a hitherto less explored area of the Rayleigh region of very low magnetic fields, which has growing application potential in new, low-energy consuming electronic devices or ultra-low magnetic field shielding. The total permeability, coercive field and remanent magnetic induction were analysed in connection with the reciprocity factor and inner demagnetization factor and their relations to interparticle magnetic interaction, domain wall movability and predominance of individual magnetization processes. Their dependence on the magnetic induction and the properties of each sample were revealed and confirmed also by energy loss separation. The Rayleigh region analytical expressions for the coercive field, remanent magnetic induction, the ratio of irreversible to reversible magnetization changes and their percentages within the magnetizing cycle were used for SMCs for the first time.

Research on a Novel High-Torque-Density Axial–Radial-Flux Permanent-Magnet Motor with Annular Winding for an Elevator-Traction Machine

The traditional radial flux PMSM and axial flux PMSM have an effective air gap on only one side, between the stator and rotor, and only the effective air gap generates electromagnetic torque. There are defects in the magnetic-field utilization, and it is difficult to improve the torque density. Therefore, this paper proposes an axial–radial-flux permanent-magnet synchronous motor (ARF-PMSM), which combines radial flux with axial flux, to be used in an elevator-traction machine-drive motor. The characteristics of the ARF-PMSM are that the stator core is made of a soft magnetic composite material and the winding is annular. The motor has three effective air gaps, which can achieve high torque density without increasing the overall dimensions. In this paper, the mechanical structure and operation mechanism of the ARF-PMSM are introduced, and the characteristics of its magnetic circuit structure are analyzed by using the equivalent magnetic circuit method. The torque characteristics and other electromagnetic characteristics of the ARF-PMSM, the traditional surface-mounted PMSM, and the spoke-type PMSM are compared and analyzed using the finite element method. The research results show that the proposed motor has high torque density, which provides a new design idea in the form of a high-torque-density PMSM for use in elevator-traction machines.

Performance Comparison of Tubular Flux-Switching Permanent Magnet Machines Using Soft Magnetic Composite Material and Hybrid Material Magnetic Cores

The magnetic core of a conventional tubular flux-switching permanent magnet machine (TFSPMM) is made of axially laminated silicon steel sheets. The laminated direction is consistent with the motion direction of the mover. According to the flux-switching principle, a large amount of eddy current loss will be generated when the alternating flux passes through the silicon steel sheets vertically. The soft magnetic composite (SMC) material is magneto-thermal isotropy and has low eddy current loss, which can be used in TFSPMM. However, the permeability of SMC is much lower than that of silicon steel sheets, and the hysteresis loss is large at low frequency. When the two materials are used as the hybrid material magnetic core in the machine, their respective advantages can be used to improve the thrust force of the machine and reduce core loss. In order to study the effect of SMC core and hybrid material magnetic core on the machine, the performances of TFSPMM with different kinds of cores are calculated and compared by finite element method (FEM), including magnetic density distribution, permanent magnet (PM) flux linkage, back-electromotive force (EMF), inductance, detent force, thrust force and core loss. Finally, a prototype machine with hybrid material magnetic core is made and experimental verification is carried out.

Research on Electromagnetic System of Large Capacity Energy Storage Flywheel

A large capacity and high power flywheel energy storage system (FESS) is developed and applied to wind farms, focusing on the high efficiency design of the important electromagnetic components of the FESS, such as motor/generator, radial magnetic bearing (RMB) and axial magnetic bearing (AMB). Firstly, a axial flux permanent magnet synchronous machine (AFPMSM) based on soft magnetic composite material (SMC) is designed. Then, considering the structure of FESS and machine, a permanent magnet biased radial magnetic bearing (PMRMB) and a HALBACH axial passive magnetic bearing (PMB) is proposed which have the advantages of low power consumption and large bearing capacity, then the analyses are carried out according to the load capacity requirements. Finally, the flywheel prototype is fabricated and tested. The experimental results verify the relevant theoretical analysis, and finally can achieve stable and reliable operation.

Multi-component soft magnetic alloy FeNiCoAl0.4Mo0.1Si0.4B0.1 with high frequency stability of permeability

The concept of multicomponent magnetic high-entropy alloys (HEA) opens up great opportunities for controlling various properties in such materials. Previously, soft magnetic HEAs have been developed with a unique combination of magnetic and mechanical properties. This work is focused on the study of the possibility of obtaining a magnetic multicomponent alloy for high-frequency applications. As a result, using mechanical synthesis, an alloy FeNiCoAl0.4Mo0.1Si0.4B0.1 was fabricated, which in its pure form has an acceptable level of soft magnetic properties and a high resonant frequency of about 600 kHz. Soft magnetic composite material prepared based on this powder with the addition of 4 wt% of resin has a resonant frequency of over 100 MHz.