High Resonance Frequency Research Articles

Chain-arranged Ni1-xCox micro/nano particles prepared via a magnetic field-assisted reduction for enhanced electromagnetic wave absorption

Transition metal magnetic alloys have garnered extensive interests in electromagnetic wave absorption due to the remarkable magnetic loss capacity and unique magnetism-frequency characteristics. Herein, we report a novel magnetic absorbent of Ni1-xCox micro chains that synthesized through a magnetic field-assisted reduction method. The precipitated Ni1-xCox particles could be connected and aligned during the magnetic reduction process. Due to the modified electronic structure of the Co active site by Ni, the particle size in the Ni1-xCox micro chains noticeably increases with increased x. Meanwhile, the complex dielectric constants exhibit a decreasing trend, which contributes to the improved impedance matching and higher resonance frequencies. The connected Ni1-xCox micro/nano particles not only benefit to the conductive loss, but also strengthened the polarization loss on the contacted interfaces among the particles. As a result, significantly enhanced electromagnetic wave absorption performance was obtained with the minimum reflection loss of −21.0 dB and the effective absorption bandwidth of 3.92 GHz at a thickness of only 1.35 mm. Overall, this work has demonstrated the strategy of designing aligned bimetallic absorbent, possessing great potentials in improving their microwave absorption properties.

Ultrasensitive liquid sensor based on an embedded microchannel bulk acoustic wave resonator

The high-frequency and high-quality factor characteristics of bulk acoustic wave (BAW) resonators have significantly advanced their application in sensing technologies. In this work, a fluidic sensor based on a BAW resonator structure is fabricated and investigated. Embedded microchannels are formed beneath the active area of the BAW device without the need for external processes. As liquid flows through the microchannel, pressure is exerted on the upper wall (piezoelectric film) of the microchannel, which causes a shift in the resonant frequency. Using density functional theory, we revealed the intrinsic mechanism by which piezoelectric film deformation influences BAW resonator performance. Theoretically, the upwardly convex piezoelectric film caused by liquid flow can increase the resonant frequency. The experimental results obtained with ethanol solutions of different concentrations reveal that the sensor, which operates at a high resonant frequency of 2.225 GHz, achieves a remarkable sensitivity of 5.1 MHz/% (221 ppm/%), with an ultrahigh linearity of 0.995. This study reveals the intrinsic mechanism of liquid sensing based on BAW resonators, highlights the potential of AlN/Al0.8Sc0.2N composite film BAW resonators in liquid sensing applications and offers insights for future research and development in this field.

An electromagnetic indirect-driving scanning mirror for wide-field coaxial LiDAR applications

This paper reports an electromagnetic indirect-driving scanning mirror with an enlarged mirror plate (17mm×17mm) supported by high-strength polymer hinges for wide-field coaxial LiDAR (Light Detection and Ranging) applications. An indirect-driving mechanism was developed to achieve large tilting angle through mechanical amplification, while maintaining a relatively high resonance frequency of the enlarged mirror plate. A prototype mirror was designed, fabricated, and tested. A Hall scan position sensor was integrated to monitor the pose of the mirror in real time. The testing results show a coupled resonance frequency of 54.9 Hz with an optical tilting angle of ±60°, corresponding to a field of view (FoV) of 120°. A wide-field coaxial LiDAR system was also built based on the indirect-driving scanning mirror, and 2D imaging was demonstrated.

Research on the application of second-order HR in attenuating tire cavity resonance noise

Tire cavity resonance noise (TCRN) is well-known as one of the significant sources causing the interior noise at low-frequency band. Previous research shows that Helmholtz resonator (HR) array in an automotive wheel may obviously attenuate TCRN. To further improve the effect, the second-order HRs in the HR array are introduced here. Firstly, the theoretical model of second-order HR is established, and the results are verified by finite element method. The results show that the second-order HR with the same cavity volume may produce two transmission loss peaks, and a higher peak than that of the original first-order HR in the specified frequency band. Then, the optimization is performed to obtain a higher effect of attenuating TCRN at the original design frequency and a certain effect of attenuating road noise in the specified lower-frequency band. The results indicate that the desired effect may be achieved, and the higher resonance frequency can easily fall in the frequency band below 600Hz although hard to fall in the frequency band of TCRN. So the second-order HR is helpful to improve attenuating road noise including TCRN.

Infrequent trigonal crystal system CoNb thin films: investigation of growth behavior, microstructure and magnetic properties

Magnetic films with excellent initial permeability, high resonance frequency, suitable anisotropy fields, and well compatibility are highly desirable for on-chip inductors and transformers. Here, Co90Nb10 thin films with different thicknesses are grown on Si substrates of different orientations using an electron beam evaporation technique. A rare trigonal crystal structure of the CoNb films was observed and was virtually unaffected by substrate orientation. Films grown exhibit thickness-dependent magnetic behavior: coercivity initially decreases and then increases, while the in-plane anisotropy field progressively diminishes. Meanwhile, the initial permeability increases initially before decreasing, and the resonance frequency continuously decreases as the thickness increases. The resultant Co90Nb10/Si (111)-50 nm film displays a high μi of 496 and a great fr of 2.1GHz. The improved magnetic performance originates from the smaller crystallite size, smoother surface roughness, and suitable in-plane anisotropy field. Moreover, the in-plane anisotropy transition to the out-of-plane anisotropy in the Co90Nb10 films whose thickness exceeds 70nm, which is attributed to the growth of the coarse columnar grains once the critical thickness is exceeded. This study demonstrates the correlation between the growth behavior, microstructure, and magnetic properties of CoNb thin films, presenting a new potential for utilizing Co-based thin films in high-frequency applications.

High-frequency Resonance Suppression of Railway Traction Power Supply System Based on the Combination of Single-tuned and C-type Filters

Background: Railroad transportation in the actual operation process, there are also many dangerous accidents caused by resonance, which greatly affect the safety of railroad transportation. A comprehensive examination of the operational dynamics within the power branch of a traction substation is imperative for sustaining system equilibrium. Discrepancies between these facets pose a potential threat to the safety of railway transport. Thus, a meticulous analysis of highfrequency resonance characteristics and the formulation of effective suppression techniques become paramount. Objective: Harmonics from grid-side locomotive traction braking are scrutinized under different operational scenarios and different train runs. The aim is to develop an effective harmonic management strategy to normalize the THD and thus maintain the traction power supply system to become more stable. Methods: This study investigates the high-frequency harmonic resonance characteristics using a control variable approach. Harmonics and negative sequences generated during locomotive traction braking under different operating conditions are investigated by means of extensive analysis. These challenges require the implementation of a harmonic management method. This method uses a combination of two monotonic filters and a C filter in parallel. This method applies to different operating conditions and can dynamically adapt harmonics to changes in the number of trains, which is related to the actual dynamics of the traction power system closely. Results: A comparative evaluation of seven operating conditions shows that the filter in this patent exceeds the efficiency of existing methods. The filter reduces the fluctuations during spectral changes, and the voltage distortion rate decreases from the previous 2.33% to 0.55%, making it more adaptable and promising effective harmonic management in high voltage and high current situations. Conclusion: Through multiple simulation tests, a synergistic configuration involving the C-type filter and two single-tuned parallel connections under regenerative braking conditions emerges. This refined, patented filter design not only mitigates the impact of negative sequence during the filtration process but also substantially diminishes high harmonics and THD.

Analysis of Influence of Grid-Following and Grid-Forming Static Var Generators on High-Frequency Resonance in Doubly Fed Induction Generator-Based Wind Farms

In Doubly Fed Induction Generator (DFIG)-based wind farms with Static Var Generators (SVGs), high-frequency resonance will be more like to occur when an unloaded cable is put into operation, which will threaten the stable operation of the wind farm. To address this issue, the influence of power outer loops on the impedance of grid-connected inverters is considered. Based on harmonic linearization, theoretical models for the sequence impedances of DFIGs, Grid-following (GFL) SVGs, and Grid-forming (GFM) SVGs are established. The correctness of the three models is verified by impedance scanning using the frequency sweep method. Through a comparative analysis of these sequence impedances, it is found that unlike the GFM SVG (which exhibits inductive impedance), the GFL SVG exhibits capacitive impedance in the high-frequency band, which leads to negative damping characteristics in the high-frequency band for the wind farm system with the grid-following SVG; thereby, the risk of high-frequency resonance also increases accordingly. On the contrary, GFM control adopted by SVGs can effectively eliminate the negative damping region in the high-frequency band for wind farms to suppress high-frequency resonance. Meanwhile, for grid-forming SVGs, the parameter variations in power synchronous loops have no significant impact on the suppressing effect of high-frequency resonance for wind farms. Finally, an electromagnetic simulation model for a DFIG-based wind farm system with an SVG is established using the StarSim-HIL (hardware-in-the-loop) experiment platform, and the simulation results validate the correctness of the theoretical analysis.

Design and Modelling of MEMS Vibrating Internal Ring Gyroscopes for Harsh Environments.

This paper presents a design, model, and comparative analysis of two internal MEMS vibrating ring gyroscopes for harsh environmental conditions. The proposed design investigates the symmetric structure of the vibrating ring gyroscopes that operate at the identical shape of wine glass mode resonance frequencies for both driving and sensing purposes. This approach improves the gyroscope's sensitivity and precision in rotational motion. The analysis starts with an investigation of the dynamic behaviour of the vibrating ring gyroscope with the detailed derivation of motion equations. The design geometry, meshing technology, and simulation results were comprehensively evaluated on two internal vibrating ring gyroscopes. The two designs are distinguished by their support spring configurations and internal ring structures. Design I consists of eight semicircular support springs and Design II consists of sixteen semicircular support springs. These designs were modelled and analyzed using finite element analysis (FEA) in Ansys 2023 R1 software. This paper further evaluates static and dynamic performance, emphasizing mode matching and temperature stability. The results reveal that Design II, with additional support springs, offers better mode matching, higher resonance frequencies, and better thermal stability compared to Design I. Additionally, electrostatic, modal, and harmonic analyses highlight the gyroscope's behaviour under varying DC voltages and environmental conditions. Furthermore, this study investigates the impact of temperature fluctuations on performance, demonstrating the robustness of the designs within a temperature range from -100 °C to 100 °C. These research findings suggest that the internal vibrating ring gyroscopes are highly suitable for harsh conditions such as high temperature and space applications.

Induction Coil Design Considerations for High-Frequency Domestic Cooktops

The use of wide band gap (WBG) semiconductor switches in power converters is increasing day by day due to their superior chemical and physical properties, such as electrical field strength, drift speed, and thermal conductivity. These new-generation power switches offer advantages over traditional induction cooker systems, such as fast and environmentally friendly heating. The size of passive components can be reduced, and the decreasing inductance value of induction coils and capacitors with low ESR (equivalent series resistance) values contributes to total efficiency. Other design parameters, such as passive components with lower values, heatsinks with low volumes, cooling fans with low power, and induction coils with fewer turns, can offset the cost of WBG power devices. High-frequency operation can also be effective in heating non-ferromagnetic materials like aluminum and copper, making them suitable for heating these types of pans without complex induction coil and power converter designs. However, the use of these new generation power switches necessitates a re-examination of induction coil design. High switching frequency leads to a high resonance frequency in the power converter, which requires lower-value passive components compared to conventional cookers. The most important component is the induction coil, which requires fewer turns and magnetic cores. This study examines the induction heating equivalent circuit, discusses the general structure and design parameters of the induction coil, and performs FEM (finite element method) analyses using Ansys Maxwell. The results show that the induction coil inductance value in new-generation cookers decreases by 80% compared to traditional cookers, and the number of windings and magnetic cores decreases by 50%. These analyses, performed for high-power applications, are also performed for low-power applications. While the inductance value of the induction coil is 90 μH at low frequencies, it is reduced to the range of 5 μH to 20 μH at high frequencies. The number of windings is reduced by half or a quarter. The new-generation cooker system experimentally verifies the coil design based on the parameters derived from the analysis.

Electrical Detection of Acoustic Antiferromagnetic Resonance in Compensated Synthetic Antiferromagnets.

Compensated synthetic antiferromagnets (SAFs) stand out as promising candidates to explore various spintronic applications, benefitting from high precession frequency and negligible stray field. High-frequency antiferromagnetic resonance in SAFs, especially the optic mode (OM), is highly desired to attain fast operation speed in antiferromagnetic spintronic devices. SAFs exhibit ferromagnetic configurations above saturation field; however in that case, the intensity of OM is theoretically zero and hard to be detected in well-established microwave resonance experiments. To expose the hidden OM, the exchange symmetry between magnetic layers must be broken, inevitably introducing remanent magnetization. Here, we experimentally demonstrate a feasible method to break the symmetry via surface acoustic waves with the maintenance of compensated SAF structure. By introducing an out-of-plane strain gradient inside the Ir-mediated SAFs, we successfully reveal the hidden OM. Remarkably, the OM intensity can be effectively modulated by controlling strain gradients in SAFs with different thicknesses, confirmed by finite-element simulations. Our findings provide a feasible scheme for detecting the concealed OM, which would trigger future discoveries in magnon-phonon coupling and hybrid quasiparticle systems.

Branch spiral beam harvester for uni-directional ultra-low frequency excitations

In recent years, there has been a growing interest in piezoelectric energy harvesting systems, particularly for their potential to recharge or replace batteries in energy-efficient electronic devices and wireless sensor networks. Nonetheless, the conventional linear piezoelectric energy harvesters (PEH) face limitations in ultra-low frequency vibrations (1–10 Hz) due to their narrow operating bandwidth and higher resonance frequencies. To address this, researchers explored compact shaped geometries, with spiral PEH being one such design to lower resonance frequencies by reducing structural stiffness. While trying to achieve this lower resonance frequency, spiral designs overlooked that they were spreading the stress across the structure. This was a significant drawback because it reduced the structure's ability to stress the piezoelectric transducer. The issue remains unaddressed, limiting the power generation of spiral beam harvesters. Furthermore, spiral structures also fail to broaden the operating bandwidth, posing additional constraints on their effectiveness. This study introduces a novel solution – the “branch spiral beam harvester,” combining the benefits of both spiral and branch beam designs. The integration of the branch beam concept into the spiral structure aimed to broaden the effective frequency range and establish a concentrated stress area for the placement of the piezoelectric transducer. Finite Element Analysis (FEA) was employed to assess operating bandwidth and stress distribution, while experimental studies evaluated voltage and power generation. Once the workability was confirmed, a statistical optimisation method was introduced to tailor the harvester for specific frequencies in the ultra-low frequency range. Results indicated that the branch spiral beam harvester exhibits a wider operating bandwidth with six natural frequencies in the ultra-low frequency range. It harnessed significantly higher output voltages and power compared to conventional linear PEH. This innovation presents a promising advancement in piezoelectric energy harvesting, offering improved performance without the need for proof masses or additional accessories.

A Comparison Study on Detailed Strengthening mechanism analysis on micro structure and mechanical properties of 3 phases FGM Material with vibrational behavior analysis is fabricated using WAAM process and traditional method

Additive Manufacturing (AM) techniques implement the surface thickness accumulating through the support of CAD/CAM model for improving the 3D (three dimensional) products. Metal Additive Manufacturing provides design versatility as well as the freedom in fabricating the materials. The preparation technology of the metal composites integrates pressure leaching, agitation casting, powder metallurgy and friction stirring. The strengthening mechanism of the metal composites comprises of ceramic particle, short fiber and whisker etc. The two common strengthening mechanism to attain the high performing material composite are ceramic particulate reinforced composites (CPRCs) and precipitation hardening (PH). Thus, the current study evaluates the strengthening mechanism of fabricated material along with vibrational behavior using Wire Arc Additive Manufacturing (WAAM). The study fabricated three functionally graded material. The FGM materials are SS316L, SS316L+Inconel 625 + Ti6Al4V and SS316L+Inconel 625 + Inconel 718. The three phase FGM material is annealed at 700⁰C, 900⁰C and 1200⁰C for 60 min. Later, it have been air-cooled to the room temperature. The heating process strengthens the three phase FGM materials. The heating process of FGM material results in the precipitation which might not improve the mechanical properties. Nonetheless, the varied annealing temperature such as 900⁰C and 1200⁰C has enhanced the mechanical properties of the three phase FGM materials. As per the analysis, 60 % SS316L+20 % INCONEL 625+20 % Ti6Al4V material has been completely broken whereas 60 % SS316L+20 % INCONEL 625+20 % Inconel 718 has slight crack which show the increased strength of the material. The resonance frequency in conventional part is lower than the AM part. The resonance is oscillated with greater amplitude at certain frequencies. In damping, a higher resonance frequency is less vibrated in common frequencies. Thus, the study concludes that 60 % SS316L+20 % INCONEL 625+20 % Ti6Al4V and 60 % SS316L+20 % INCONEL 625+20 % Inconel 718 has significant strength compared to parent material SS316L. Moreover, AM has better vibration behavior compared to the conventional manufacturing.

Study on the high resistivity and resonant frequency characteristics of Eu-doped NiZnCo ferrites

To fulfill the urgent demand for materials suitable for contemporary high-frequency applications, Eu-substituted Ni0.55Zn0.35Co0.1EuxFe2-xO4 (NZCEF, 0 ≤ x ≤ 0.10) composite ferrites were successfully synthesized by a solid-state reaction method, demonstrating characteristics apt for high-frequency functionalities. Detailed examination via SEM and EDS confirmed the compositional purity of these ferrites. Microstructural analysis indicates that the incorporation of europium results in a reduction of the average grain size in NZCEF composites, enhancing the material's densification. Measurements of resistivity and dielectric properties reveal that Eu doping affects the concentration of Fe2+ and Fe3+ ions as well as lattice defects within the ferrite, thereby leading to higher dielectric constants and resistivity (ρ, 6.51 × 108 Ω m). Magnetic analysis confirms that the substitution with Eu ions significantly increases both the coercivity and the ferromagnetic resonance frequency (fr), from 25.7 Oe and 445 MHz to 45.73 Oe and 1.22 GHz, respectively. This improvement is attributed to changes in grain size and domain wall motion. Consequently, Eu3+-substituted NZCEF ferrites exhibit superior electromagnetic properties, making them ideal candidates for advanced high-frequency material applications.

Johnson-noise-limited cancellation-free microwave impedance microscopy with monolithic silicon cantilever probes

Microwave impedance microscopy (MIM) is an emerging scanning probe technique for nanoscale complex permittivity mapping and has made significant impacts in diverse fields. To date, the most significant hurdles that limit its widespread use are the requirements of specialized microwave probes and high-precision cancellation circuits. Here, we show that forgoing both elements not only is feasible but also enhances performance. Using monolithic silicon cantilever probes and a cancellation-free architecture, we demonstrate Johnson-noise-limited, drift-free MIM operation with 15 nm spatial resolution, minimal topography crosstalk, and an unprecedented sensitivity of 0.26 zF/√Hz. We accomplish this by taking advantage of the high mechanical resonant frequency and spatial resolution of silicon probes, the inherent common-mode phase noise rejection of self-referenced homodyne detection, and the exceptional stability of the streamlined architecture. Our approach makes MIM drastically more accessible and paves the way for advanced operation modes as well as integration with complementary techniques.

Development of an inertia-driven resonant piezoelectric stack pump based on the flexible support structure

This paper proposes an inertia-driven resonant piezoelectric stack pump based on a flexible support structure to solve the problem that the piezoelectric stack cannot effectively drive the diaphragm pump to transport liquid due to too small output displacement and too high resonant frequency when one end is fixed. Under the inertial force generated by the vibration of the piezoelectric stack’s mass center during its deformation, the whole piezoelectric stack will vibrate with the flexible support structure; and a large displacement and inertial force can be achieved to drive the pump at the resonant frequency. Piezoelectric pumps are designed with a diaphragm pump and a piezoelectric stack based on the flexible support structure. The piezoelectric vibrator includes a piezoelectric stack, a preloading component and a flexible support plate. A fixed support plate and three flexible support plates with different stiffnesses were fabricated and assembled with the same piezoelectric stack and diaphragm pump respectively to construct four piezoelectric pump prototypes with different resonant frequencies. The temperature rise characteristics of the piezoelectric stack were experimentally studied to determine the safe range of the driving voltage and frequency. Then the output performances of the piezoelectric pumps were tested. Under a sinusoidal driving voltage of 100 Vpp, the piezoelectric pump based on the fixed support structure cannot pump water, while the piezoelectric pumps based on the flexible support structure achieved the maximum flow rates of 89.0 ml min−1, 123.4 ml min−1 and 197.4 ml min−1 at the resonant frequencies of 262 Hz, 297 Hz and 354 Hz, and the maximum backpressures of 4.4 kPa, 7.5 kPa and 11.0 kPa at 266 Hz, 309 Hz and 365 Hz.

Simulation of Piezoelectric Transducer Microphone Diaphragm Based on Different Materials

Piezoelectric microphone which utilizes MEMS technology is a type of transducer that converts an input acoustic signal into an output electrical signal. The characteristics of the microphone diaphragm such as the diaphragm design features and the type of piezoelectric materials used will affect the performance of the microphone in terms of sensitivity. It is hard to control the stress of the diaphragm used in the MEMS transducer microphone. A modification of the diaphragm is done in this project to reduce the residual stress of the piezoelectric transducer. In addition, finite element analysis namely structural, modal and harmonic were carried out using Ansys 15.0 to simulate the mechanical and dynamic behaviour of the microphone diaphragm. Two types of diaphragm structure were designed, namely square and circular, while three types of piezoelectric material which are AlN, PZT and ZnO were used as the diaphragm material. The structural analysis findings of the diaphragm subjected to 1 Pa pressure revealed that the circular diaphragm made of AlN material exhibited the highest stress, reaching 43.05 GPa, surpassing the stresses observed in the other two materials. On the contrary, the square diaphragm composed of PZT material demonstrated the lowest stress, with only 1.55 GPa. In terms of resonance frequency, the circular AlN diaphragm achieved the highest resonant frequency, reaching 449.84 kHz, whereas the square PZT diaphragm exhibited the lowest frequency at 200.25 kHz. In general, the circular diaphragm design consistently yielded higher first resonant frequencies compared to the square design.The results show that the circular diaphragm with AlN piezoelectric materials is the ideal diaphragm in the microphone because of the highest stress generated and the first resonant frequency. The stress is related to the sensitivity of a microphone while the high resonant frequency can lead to the better optimization of signal to noise ratio control.

High-Frequency Resonance Suppression Based on Cross-Coupled Filter and Improved Passive Damper for MMC-HVDC System

High-Frequency Resonance Suppression Based on Cross-Coupled Filter and Improved Passive Damper for MMC-HVDC System

Mechanical and modal analysis of different implant strategies for loss of three teeth with bone atrophy in the maxillary posterior region

Purpose: This study aimed to evaluate the stress distribution and secondary stability involved in five implant strategies, including implant-supported prostheses (ISP) and tooth-implant-supported prostheses (TISP), used for bone atrophy in the maxillary posterior region with teeth loss using finite element analysis, and to explore the more desirable implant methods. Methods: Five implant strategies were made to analyze and compare: M1, implant-supported prosthesis consisting of a short implant with a regular implant; M2, implant-supported prosthesis consisting of a tilted implant with a regular implant; M3, cantilever structure; M4, tooth-implant-supported prosthesis consisting of a short implant with a regular implant; M5, tooth-implant-supported prosthesis consisting of a regular implant, and M6, with only the natural teeth as a control group. Dynamic loading of the above models was performed in finite element analysis software to assess the stress distribution of the bone tissue and implants using the von Mise criterion. Finally, the secondary stability of different models was evaluated by modal analysis. Results: The maximum stress distribution in the cortical bone in M1(60 MPa) was smaller than that in M2(97 MPa) and M3(101 MPa), The first principal strain minimum was obtained in M2 (2271 μ ε ). M4 (33 MPa, 10085 Hz) with the best mechanical properties and highest resonance frequency. But increased the loading on the natural teeth. Conclusions: Short implants and tilted implants are both preferred implant strategies, if cantilever construction is necessary, a tooth-implant-supported prosthesis consisting of a short implant and a regular implant is recommended.

Magnetic and Thermal Behavior of a Planar Toroidal Transformer

This paper presents a study on the magnetic and thermal behaviors of a planar toroidal transformer, comprising two planar toroidal coils. In our configuration, the primary coil consists of twenty turns, while the secondary coil consists of ten turns. This design combines the advantages of both toroidal and planar transformers: it employs flat coils, akin to those utilized in planar transformers, while retaining a toroidal shape for its magnetic core. This combination enables leveraging the distinctive characteristics of both transformer types. This study delves into electromagnetic and thermal behaviors. Electromagnetic behavior is elucidated through Maxwell’s equations, offering insights into the distribution of magnetic fields, potentials, and electric current densities. Fluid flow is modeled via the Navier–Stokes equations. By coupling these equation sets, a more comprehensive and accurate portrayal of the thermal phenomena surrounding electrical equipment is attained. Such research is invaluable in the design and optimization of electrical systems, empowering engineers to forecast and manage thermal effects more efficiently. Consequently, this aids in enhancing the reliability, durability, and performance optimization of electrical equipment. The mathematical model was solved using the finite element method integrated into the COMSOL Multiphysics software v. 6.0. The COMSOL Multiphysics simulation showed correct behavior of potential, electric field, current density, and uniformly distributed temperature. In addition, this planar toroidal coil transformer model offers many advantages, such as small dimensions, high resonance frequency, and high operating reliability. This study made it possible to identify the range of its optimal functioning.

High-performance CeFeCo/FeSiAl soft magnetic composites for megahertz power devices

Soft magnetic composites (SMCs) play a crucial role in modern electronics and electrical devices, for which challenges remain in maintaining magnetic performance and reducing loss at megahertz (MHz) frequencies. Here, CeFeCo/FeSiAl@ polyurethane (PU) SMCs have been rationally designed with the simultaneous achievement of large relative permeability, high domain-wall resonance frequency, and low power loss. As a rare-earth soft magnetic alloy, the CeFeCo is promising for high-frequency applications due to its easy-plane anisotropy, whereas FeSiAl is advantageous with increased electrical resistivity as well as approaching-zero magnetocrystalline anisotropy and magnetostriction. Hot pressing has been adopted to achieve a dense and homogeneous distribution of CeFeCo and FeSiAl powders in the PU for reduced magnetic dilution and eddy current loss. The resultant SMCs exhibit optional soft magnetic performance with large relative permeability of 21.0, low power loss of 3677.5 kW·m−3 at 5 MHz, and high domain-wall resonance frequency of 386.1 MHz. As such this work provides insights into the design of high-frequency SMCs incorporating novel rare-earth soft magnetic alloys.