IEEE Transactions on Magnetics最新文献

{"title":"Thermal Design and Comparison of Inner- and Outer-Rotor High-Power-Density PM Motors for Industrial Drone Applications","authors":"Deniz Bulut;Hasan Karabay;Metin Aydin","doi":"10.1109/TMAG.2026.3699803","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3699803","url":null,"abstract":"High-power-density permanent magnet (PM) motors used in industrial drone propulsion systems operate under severe thermal constraints due their compact structures and high electromagnetic loading. Effective thermal management is therefore essential to ensure reliable operation and prevent insulation degradation and magnet demagnetization. This article presents a comparative thermal analysis of inner-rotor and outer-rotor high-power-density PM motors designed under identical geometric constraints and similar electromagnetic loading conditions. Loss distributions obtained from electromagnetic finite-element analysis are used as heat sources in a lumped-parameter thermal network model. The influence of stator epoxy impregnation on thermal behavior is investigated, and different air-cooling strategies for the inner-rotor motor housing are evaluated. In addition, axial and radial cooling fin configurations are analyzed using computational fluid dynamics to assess their impact on convective heat transfer. The results show that epoxy impregnation significantly reduces winding temperatures, while the inner-rotor topology provides shorter thermal paths and lower stator temperatures compared to the outer-rotor configuration. Although axial fins improve cooling performance by approximately <inline-formula> <tex-math>$6~^{circ }$ </tex-math></inline-formula>C, radial fins are preferred due to their simpler manufacturing process. Experimental measurements on a prototype motor validate the proposed thermal modeling approach.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"8204606-8204606"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel PCB Coil Design for Internally Illuminated Photoreactors","authors":"Bruno Ortner;Alexander Sutor","doi":"10.1109/TMAG.2026.3693540","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3693540","url":null,"abstract":"Wireless light emitters (WLEs) powered by an alternating magnetic field can be used to illuminate photoreactors internally. State-of-the-art WLEs have a diameter of 10 mm and consist of an iron-core receiver coil, a capacitor, and a light-emitting diode (LED). Since the iron-core inductor restricts the available design space, particularly for the integration of a second LED, it shall be replaced by a printed circuit board (PCB) coil. This work proposes a multilayer PCB coil design that satisfies the size constraint while achieving comparable performance. The design features an area-efficient trace layout that maximizes the effective conductor length and inductive coupling. A generalized design methodology is introduced, allowing the concept to be adapted to different coil diameters, layer counts, and manufacturing constraints. Evaluation by finite element method (FEM) simulations and measurements of fabricated PCB coils shows that the proposed multilayer PCB approach is a promising alternative to conventional iron-core receiver coils for compact WLEs.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"8400506-8400506"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11520416","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytical Design of High-Frequency Magnetic Coupling Inductive Transformer","authors":"Ping Jin;Junshun Wang;Yujing Guo;Tianrui Zhou;Gang Lei;Jianguo Zhu","doi":"10.1109/TMAG.2026.3697843","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3697843","url":null,"abstract":"High-frequency magnetic coupling inductive transformer (MCIT) is a critical component of short-range wireless power transfer (WPT). However, existing designs focus on MCIT's electromagnetic rather than its frequency domain characteristics and lack fully analytical design methods. This article proposes an analytical design for adjacent tank MCIT using an improved area product (AP) method. Considering the influence of the air-gap’s fringing effect and the distribution parameters caused by the electric field on the design of MCIT, the structure of MCIT is determined based on the frequency-domain characteristics of the input admittance and voltage gain.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"8400908-8400908"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reverse Design of Cylindrical Uniform Magnetic Field Coils Based on Target Field Method and Its Optical Path Integration Optimization","authors":"Yi Liu;Xueping Xu;Zhenkai Zhao;Xuefeng Zhang;Chunbo Han","doi":"10.1109/TMAG.2026.3702085","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3702085","url":null,"abstract":"Uniform field coils are a key factor influencing the performance and integration of spin-exchange relaxation-free (SERF) atomic magnetometers. To balance the requirements for high uniformity and the provision of an optical path within structural constraints, this study proposes a design method based on the target field method (TFM). This method is tailored for cylindrical radial uniform field coils and supports the integration of a central optical aperture. This method employs a Fourier series expansion to describe the surface current density on a predefined cylindrical geometry, establishes an inverse solution model by combining it with the target magnetic field distribution, and introduces Tikhonov regularization to overcome ill-posed issues during the solution process. Unlike conventional applications, this method incorporates a piecewise current density model and a central exclusion zone parameter <inline-formula> <tex-math>$z_{0}$ </tex-math></inline-formula>. This allows for the flexible definition of current-free regions in the central area of the coil, thereby natively integrating the optical detection pathway. Using a cylindrical coil with a radius of 20 mm and a height of 50 mm as an example, two types of radial field-flattening coils were designed and fabricated: one without a central aperture and the other with a 5 mm optical aperture. Experimental results indicate that the coil without a central aperture achieved a volume fraction of 84.42%, where the magnetic field inhomogeneity within the target spherical region was better than 10<inline-formula> <tex-math>${}^{-4}$ </tex-math></inline-formula>, validating the effectiveness of this method in enhancing magnetic field uniformity. The design incorporating the optical aperture successfully maintained optical functionality whilst retaining relatively high uniformity. This study provides a highly reliable coil design scheme for miniaturized atomic magnetometers intended for wearable magnetoencephalography (MEG), balancing magnetic field performance with optical path integration.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"7503906-7503906"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Contact Measurement of Non-Metallic Scale Thickness on the Back Side of Ferromagnetic Materials Using Electromagnetic Force-Induced Vibration","authors":"Makoto Tohara;Kohei Okuma;Yuji Gotoh","doi":"10.1109/TMAG.2026.3695830","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3695830","url":null,"abstract":"Large-diameter pipes in industrial plants often suffer from scale buildup on their inner surfaces, which reduces flow efficiency and the overall performance of the facility. Although radiographic testing is commonly used to evaluate scale thickness, its high inspection cost limits the frequency of inspections. Electromagnetic force-based inspection methods offer a lower cost alternative but typically rely on contact-type accelerometers that are susceptible to damage. This study investigates a non-contact inspection method using a microphone to measure scale thickness on ferromagnetic steel plates and demonstrates its effectiveness through experimental validation and the 3-D nonlinear finite-element method (FEM).","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"6200805-6200805"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Local Hybrid Method With Middle-Layer Airgap Fourier Model and FEM for Electromagnetic Performance Computation of PM Machines","authors":"Wentao Gao;Feng Xiao;Yi Du;Xiaoyong Zhu","doi":"10.1109/TMAG.2026.3701718","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3701718","url":null,"abstract":"This article proposes a novel 2-D local hybrid computational method for permanent magnet (PM) machines, in which the airgap is divided into three distinct layers. The middle layer is analytically modeled using a Fourier model as a connection domain, while the adjacent stator and rotor layers remain governed by the finite element method (FEM). By constraining the analytical boundaries entirely within the airgap region, severe permeability variations at the interface are avoided. Furthermore, a rigorous boundary coupling matrix is formulated to seamlessly connect the stationary and rotating domains. This cohesive formulation integrates the discrete Fourier transform (DFT) for Dirichlet condition extraction, analytical gradient edge integrals for Neumann condition enforcement, and FEM static condensation. Consequently, the boundary coupling problem of conventional hybrid methods is solved for PM motors, the multi-order harmonics are handled naturally by the Fourier model, and the global matrix dimension is reduced compared with the conventional analytical–FEM hybrid method. Finally, the accuracy and efficiency of the proposed method are comprehensively verified by FEM and experimental measurements of a PM Vernier machine (PMVM), demonstrating its superiority.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"7402505-7402505"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combining Unequal Bit Islands and Coding Design for Areal Density Enhancing in Dual-Layer Bit-Patterned Magnetic Recording Systems","authors":"R. Sriyapai;N. Rueangnetr;S. Koonkarnkhai;C. Warisarn","doi":"10.1109/TMAG.2026.3692544","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3692544","url":null,"abstract":"In this work, we propose an alternating media structure for a dual-layer bit-patterned magnetic recording (DL-BPMR), in which the diameters of the bit islands in the bottom and top layers differ, with the bottom diameter four times that of the top. We then propose an encoding scheme that uses the larger bit island in the bottom layer for a parity bit to detect errors during decoding. Moreover, we suggest that the log-likelihood ratio (LLR) flipping technique to improve the decoding capability, which operates jointly during decoding. Simulation results show that at the same user density (UD), our proposed systems outperform the conventional single-layer (SL) BPMR. For instance, at a bit error rate (BER) of 10−3 and total UDs of 2.0 or 3.2 terabit per square inch (Tb/in2), the proposed systems provide approximately 0.8 and 1.2 dB, respectively, over the conventional SL-BPMR systems.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"3100305-3100305"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Partitioning Areal Density Gain of Shingled Magnetic Recording","authors":"Xuan Zheng;Chris Rea;Jason Gadbois","doi":"10.1109/TMAG.2026.3694264","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3694264","url":null,"abstract":"Shingled magnetic recording (SMR) provides areal density gain over conventional magnetic recording (CMR), but the realized gain has been smaller than projected. To assess the limiting factors, spin stand tests have been developed to partition the difference between the two recording formats into components of adjacent track erasure (ATE) and side reading interference. The results show that the gain is 13% and 16% for two different heat-assisted magnetic recording (HAMR) head designs, dominated by the reduction in ATE, which originates from reducing the number of adjacent track writes and removing one adjacent track to the background. This ATE reduction is less than 1 dB, which translates to limited areal density gain. The gain is further penalized by worse side reading interference for SMR. Techniques to cancel side reading interference will elevate the areal density of shingle magnetic recording more than that of CMR, increasing the areal density gain.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"3100404-3100404"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149250408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of the Apparent-Density Field in Ferrofluids Under Gradient Magnetic Fields: Theory and Quantification Through Magnetic Additional Pressure","authors":"Ge Yao;Decai Li;Zengrui Zhao;Jisheng Yang","doi":"10.1109/TMAG.2026.3730154","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3730154","url":null,"abstract":"Spatially nonuniform magnetic fields generate magnetic body forces in ferrofluids, causing internal pressure redistribution and altering the effective buoyancy of immersed objects. This effect is often described as an apparent-density field, yet direct quantification remains difficult in opaque ferrofluids under strong field gradients. Here, we establish a quantitative relationship between magnetic additional pressure and apparent density. Internal pressure is directly measured using an immersed pressure sensor, and the apparent-density distribution is reconstructed accordingly. The model is validated by experiments and multiphysics simulations incorporating measured magnetization curves rather than assuming saturation. Infrared thermography of density-calibrated spheres is used to identify equilibrium levitation positions and independently assess the predicted field. The measured pressure agrees closely with simulations. The inferred apparent density matches levitation positions with a mean relative error of 3.9%, while reconstructed profiles agree with simulations, with errors below 10% for water-based ferrofluid and below 5% for oil-based ferrofluid.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"4600412-4600412"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149249226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Axial-Field Switched-Reluctance Machine for In-Wheel Motor Applications: Hybrid Analytical Modeling (Reluctance Network and Formal Analytical Solution) and Inductance Measurements","authors":"Imane Belmahi;Salim Asfirane;Georges Barakat;Ferhat Chabour;Yacine Amara","doi":"10.1109/TMAG.2026.3691974","DOIUrl":"https://doi.org/10.1109/TMAG.2026.3691974","url":null,"abstract":"The aim of this article is to study the possibilities of an axial-field switched-reluctance machine (AFSRM). The analytical model established from the solution of Maxwell’s equations is developed and combined with a lumped parameter electromagnetic equivalent circuit model (expert reluctance network) to account for the analytical model’s lack of consideration of magnetic saturation of ferromagnetic material. This is based on the correction of air-gap flux density computed via the analytical model with the reluctance network, which significantly improves the results. A prototype has been built, and the tests allow for the evaluation of the capabilities of switched-reluctance axial-field structures for in-wheel motor applications. Results on self-inductance estimation show that the hybrid analytical model (HAM) allows for corrections of the analytical model, showing a better agreement with measurements and the 3-D finite element method (FEM) model.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 10","pages":"7001705-7001705"},"PeriodicalIF":1.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149249317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}