International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Fang, Hong Wei | Wang, Yu

Article Type: Research Article

Abstract: The magnetic gear integrated permanent magnet synchronous generator (MG-PMSG) can reduce the acoustic noise and mechanical loss, which are caused by the mechanical gear box. It also has the merits of increasing efficiency and reducing system volume when it is used for wave energy conversion system. In this paper, an improved bat algorithm (BA) based on velocity weighting factor is proposed. The improved BA is applied for the optimization design of permanent magnet (PM) to reduce the cogging torque of MG-PMSG. The numerical model is constructed by response surface methodology (RSM). The influences of key pole shape parameters on cogging …torque were investigated, including the eccentric distance, the pole-arc coefficient and the permanent magnet thickness. A global optimization design is then carried out by using the improved BA, so that the magnet dimensions corresponding to the optimal cogging torque are obtained. Finally, the performances of the MG-PMSG with the optimized permanent magnet are analyzed by finite element method. Results show that cogging torque, steady torque ripple and back electromotive force (EMF) waveform distortion of the optimized MG-PMSG are reduced. Show more

Keywords: Magnetic gear, wave energy conversion, cogging torque, bat algorithm, response surface methodology

DOI: 10.3233/JAE-201615

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2021

Authors: Lin, James | Harada, Akinori | Oka, Koichi

Article Type: Research Article

Abstract: This papers discusses a method of magnetic levitation which allows a levitated platform to remain both level and zero-power under arbitrary eccentric loading conditions. A hardware system is proposed and developed which laterally displaces hybrid electromagnets (HEMs) to counteract the moments caused by eccentric loads. In this system, the displaced HEMs are the same HEMs which are used for the levitation of the platform. A mathematical formulation is provided to explain the control methodology, and data from successful experimental trials of the developed hardware is discussed.

Keywords: Zero-power levitation, magnetic levitation, tip-tilt control

DOI: 10.3233/JAE-200011

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2021

Authors: Liu, Qing | Zhang, Shiping | Li, Yuanyuan | Lei, Gang | Wang, Li

Article Type: Review Article

Abstract: This paper presents a state-of-the-art survey on the development of the hybrid gas-magnetic bearing (HGMB) technology. HGMBs are proposed to complement the advantages of gas bearings and magnetic bearings for enhanced bearing performance. Nevertheless, there are a number of inherent challenges in their designs, analyses, and performance characteristics that must be taken into account for proper functionality and reliable operation. For this purpose, substantial results in theory, numerical simulations, and experiments concerning rotor dynamics, mechanical structures, control systems, and operation modes are discussed to help further investigation and implementation of HGMBs. In addition, future developments of HGMBs in industries and …remaining challenges are discussed. Show more

Keywords: Hybrid gas-magnetic bearings (HGMBs), rotor dynamics, bearing configuration, hybrid mode

DOI: 10.3233/JAE-201579

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-26, 2021

Authors: Yang, Guohui | Zhang, Chengning | Zhang, Shuo

Article Type: Research Article

Abstract: Permanent magnet synchronous machines (PMSMs) are widely used owing to high power density, high efficiency, etc. Core losses account for a significant component of the total loss in PMSMs beside winding losses. Therefore, it is necessary to consider core losses when designing PMSMs according to actual research applications. In this paper, taking four typical rotor structures (surface-mounted, embedded, “—” shape, “V” shape) as examples, an analysis method is proposed to predict the influence of different rotor structures on core loss of PMSMs. In the case of the same stator and winding structures, due to the influence of the rotor structure …on the magnetic circuit, the corresponding variation law of the magnetic field in the stator core is studied. This method analyzes the radial and tangential components of magnetic flux density vector of the 4 representative points (stator tooth tip, middle tooth and yoke part), and then evaluates the entire core loss through finite element analysis results. In order to verify the method, a prototype was manufactured. The experimental results show good performance of the proposed method of this paper. It provides reference for selecting the appropriate rotor structure and designing the corresponding PMSM according to different specification. Show more

Keywords: Permanent magnet synchronous machines, rotor structure, core loss, magnetic field distribution, magnetic flux density

DOI: 10.3233/JAE-201569

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2021

Authors: Cheng, Yuhua | Liu, Chunwu | Wang, Minghao | Wang, Gaofeng | Ghovanloo, Maysam | Li, Wenjun

Article Type: Research Article

Abstract: Recent progress on human brain science requires developing advanced neural recording system to capture the activity of large neural populations accurately, across a large area of the brain, and over extended periods. Recently proposed distributed neural recording systems with numerous implanted devices require reliably energizing them wirelessly. Random distribution of these mm-sized implants and brain motion place them at different positions and orientations with respect to the power transmitter. Therefore, traditional wireless power transfer techniques fall short of reaching sufficient power for all implants simultaneously, rendering some implants nonfunctional. In this paper, a three-layer power transmitting array with three-phase coil …excitation current is introduced, which is capable of producing omnidirectional and homogeneous magnetic field across the volume where the Rx coils are located. The individual coil dimensions in the array is optimized to improve the worst-case scenario in terms of homogeneity, which is further verified by the measurements using a scaled-up prototype system. The measurement results show that the minimum received voltages is improved from 0.34 V for 10-mm side-length hexagonal transmitting coil array to 0.83 V for the optimal case, i.e., 35 mm side-length hexagonal transmitting coil array. Show more

Keywords: Omnidirectional, distributed, wireless power transfer, three-phase three-layer coil array, coil radius, optimization

DOI: 10.3233/JAE-201582

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-19, 2020

Authors: Wu, Tong | Yu, Guoliang | Pang, Jiarui | Wang, Can | Yang, Han | Qiu, Yang | Zhang, Yi | Zhu, Mingmin | Zhou, Hao-Miao

Article Type: Research Article

Abstract: This work presents an easy way to improve the low-frequency properties in a small-size LTE/WWAN smartphone antenna by just loading a soft magnetic ferrite film on the strong radiation area. The base non-magnetic antenna, which only takes up an 11 mm × 30 mm no-ground space, can achieve hexa-band operation covering 822–914/1710–3244 MHz bands by co-designing a meandering strip and a T-shaped feeding strip. With loading a small-size ferrite film (2 mm × 15 mm) at the strong radiation strip, the frequencies can be shifted to cover the range of 692–1191/1698–3020 MHz, which shows a fully covering of octa-band operation, especially including the best long-term-evolution band, …LTE700, without enlarging the size of base antenna. In addition, the radiation characteristics of the magnetic antenna with ferrite film loading show a limited change at upper bands (1710–2690 MHz) but an acceptable level at lower bands (698–960 MHz). Both experimental and simulated results have been taken out and shown the consistent tendency. This optimization method of low-frequency properties by introducing a commercial ferrite film on the antenna has provided a simple and convenient way to solve the frequency deviation in the practical smartphone applications. Show more

Keywords: Multiband antenna, ferrite loading, frequency modulation, LTE700 band

DOI: 10.3233/JAE-201599

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2020

Authors: Nick, A.S. | Vynnycky, M. | Jönsson, P.G.

Article Type: Research Article

Abstract: A recent three-dimensional (3D) model that revisited earlier theoretical work for longitudinal electromagnetic stirring in the continuous casting of steel blooms is analyzed further to explore how the bloom width interacts with the pole pitch of the stirrer to affect the magnetic flux density. Whereas the first work indicated the presence of a boundary layer in the steel near the interface with the stirrer, with all three components of the magnetic flux density vector being coupled to each other, in the analysis presented here we find that the component along the direction of the travelling wave decouples from those in …the other two directions and can even be determined analytically in the form of a series solution. Moreover, it is found that the remaining two components can be found via a two-dimensional computation, but that it is not possible in general to determine these components without taking into account the surrounding air. The validity of the asymptotically reduced model solution is confirmed by comparing it with the results of 3D numerical computations. Moreover, the asymptotic approach provides a way to compute the time-averaged Lorentz force components that requires two orders of magnitude less computational time than the fully 3D approach. Show more

DOI: 10.3233/JAE-200010

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-27, 2020

Authors: Ma, Yuan | Feng, Wen | Yan, Zhen

Article Type: Research Article

Abstract: The buckling analyses of type-II superconducting strip under applied perpendicular magnetic field and/or distributed uniform mechanical load are investigated in this paper. Based on the Bean critical state model, the electromagnetic body force is firstly given. Then, based on the classical plate theory and two-point initial value method, the critical buckling states of the superconducting strip with different boundary conditions are analyzed. Numerical results show the effects of both the thickness and boundary conditions of superconducting strip on the corresponding critical buckling loads. The present work should be helpful to the research and application of superconducting thin strips.

Keywords: Superconducting thin strip, electromagnetic body force, buckling, critical buckling load

DOI: 10.3233/JAE-190115

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2020

Authors: Zhang, Yuanyuan | Meng, Fanhui | Liu, Zhao | Xing, Manman | Pang, Huaji | Deng, Meng

Article Type: Research Article

Abstract: A satellite remote imaging data is used to describe the actual ground surface around east of Shandong, based on Barrick’s formulations and Wait’s formulations, and considering the time errors due to elongation of the propagation path caused by mountains, this paper comprehensively analyzes the lightning vertical electric field over the actual ground surface. Furthermore, its effects on time-of-arrival (ToA)-based lighting location systems (LLS) are discussed in details and results show that wave-shape and time-delay of the electromagnetic fields can be significantly affected when they propagate over actual ground surface. The time-delay of the field waveform becomes longer with the increasing …roughness, but subtle effect on field peak. After analyzing the actual ground surface around district of Qingdao, this paper reveals the relation between azimuth, observation distance and time-delay. The location error caused by actual ground surface is about several kilometers around the district of Qingdao, and the revised stroke points which are evaluated by the improved actual ground surface propagation model are closer to the actual lightning strike points. Show more

Keywords: Digital elevation model (DEM), lightning vertical electric fields, actual ground surface propagation model

DOI: 10.3233/JAE-201506

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2020

Authors: Chen, Jun-Wei | Liu, Xing

Article Type: Research Article

Abstract: In this paper, the winding inductances of a linear ironless permanent-magnet synchronous actuator for high-precision applications is discussed. Different from rotary motors for conventional applications, high-order harmonics and the end effect due to discontinuous structure are considered. From such considerations, an improved Fourier series expansion is applied to the proposed distributed-parameter model of the linear winding. The calculated inductance matrix is of high accuracy, and presents a new non-uniform form. New features of the inductance matrix are analyzed, and the decoupling scheme is implemented via variable transformation and real-time updating inductances.

Keywords: Winding inductance, linear PM actuator, Fourier series expansion, end effect

DOI: 10.3233/JAE-201571

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-16, 2020