International Journal of Applied Electromagnetics and Mechanics - Volume 66, issue 2

Authors: Li, Xiangchao | Chu, Lei | Luo, Hua | Wen, Qiaoli | Ouyang, Wen

Article Type: Research Article

Abstract: Base on the analysis of the coaxial coupling theory, the experimental model of the coaxial cable short-range coupling lightning electromagnetic pulse is established to study the problem of coaxial cable short-range coupling lightning electromagnetic pulse on the ship mast and high tower. The combination wave generator is used to simulate the 8/20 μs lightning current waveform, and the metal bar with the length of 1 m and diameter of 0.016 m is used to simulate the lightning channel as the radiation source. The length of the coaxial cable and the distance from the radiation source are changed for the test. The conclusion is …as follows: when the coaxial cable is coupled with lightning wave in a short distance, the voltage waveform of cable terminal is still double exponential wave, with strong damping oscillation at 0.1 ∼0.4 μs. When the cable terminal is open circuit or connected with matching resistance, the rising time is shorter, about 1 μs; when the cable terminal shielding layer is grounded, the rising time is longer, about 10 μs. The peak voltage and energy coupled to the coaxial cable at short distance are positively correlated with the cable length, and inversely correlated with the distance from the radiation source. The energy that the cable is coupled to mainly comes from the low-frequency part, and there are multiple energy peaks below 100 Hz. Using fitting curve and experimental data, when the coaxial cable terminal is open circuit, the lightning current reaches 30 kA, the cable length is 30 m, and the distance from the lightning channel is 0.15 m, the peak value of the voltage coupled to the cable terminal is 66 V. It has certain guiding significance and value in the practical application of electromagnetic pulse protection. Show more

Keywords: Coaxial cable, 8/20 μs lightning wave, coupling, peak voltage, energy

DOI: 10.3233/JAE-190153

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 66, no. 2, pp. 205-223, 2021

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. 66, no. 2, pp. 225-236, 2021

Authors: Zhang, Xiwei | Li, Lin | Pang, Jian

Article Type: Research Article

Abstract: In this paper, both nanocrystalline alloy (Fe73.5 Cu1 Nb3 Si15.5 B7 ) ribbon samples and toroidal samples (wound ribbon) are annealed at different temperatures in order to consider the influence of inner stress on the magnetization properties. Then the AC magnetization properties of these samples are measured. Combined with the measured results, the influence of inner stress on nanocrystalline alloy’s microstructure is analyzed quantitatively based on the loss separation principle and the statistical theory of loss. By comparing measured macroscopic magnetization characteristics and excess loss, the equivalent stress state of the toroidal sample is evaluated. Furthermore, two kinds of samples’ …excess loss under different annealing temperatures are analyzed, and the effectiveness of stress relief at optimal annealing temperature is validated. Show more

Keywords: Nanocrystalline alloy, loss separation, excess loss, annealing, stress relief

DOI: 10.3233/JAE-201532

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 66, no. 2, pp. 237-247, 2021

Authors: Heya, Akira | Hirata, Katsuhiro

Article Type: Research Article

Abstract: Space recognition is a crucial issue for autonomous systems such as unmanned aerial vehicles, walking robots, and autonomous cars. These systems are necessary to obtain information using a camera while moving. However, reduction in recognition accuracy and system size increase has created problems. To solve these problems, we proposed the three-degree-of-freedom (DOF) actuator for image stabilization. This paper proposes a novel initial position estimation method and sensorless attitude estimation method for the three-DOF actuator to further downsize and reduce weight. The effectiveness of the proposed methods is verified by a magnetic field analysis, using a three-dimensional finite element method and …numerical simulations. Show more

Keywords: Multiple-degree-of-freedom actuator, three-degree-of-freedom actuator, electromagnetic actuator, sensorless position estimation, image stabilization

DOI: 10.3233/JAE-201537

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 66, no. 2, pp. 249-263, 2021

Authors: Li, Zixuan | Yang, Guolai | Wang, Liqun

Article Type: Research Article

Abstract: This paper investigates the damping and demagnetization effect of an electromagnetic buffer (EMB) under impact load. The motional eddy currents are calculated first, and the Ampere circuital theorem is employed to calculate the induced magnetic field. The demagnetization effect is formulated by the magnetic Reynolds number with a correction coefficient k m . Following this, the time-step finite element (FE) model of the buffering system is constructed based on the nonlinear B–H curve. The accuracy and feasibility of the FE model is preliminarily verified by small-scale impact test. The characteristics of damping displacement, velocity, damping force and damping coefficient are …obtained. Then, the demagnetization effect is analysed by eddy current, magnetic field distribution, through the intensive impact load test at room temperature and time-step FE model. The value of k m is obtained through the intensive impact test and the simplified expression of critical velocity. The results show that the demagnetization effect is obvious with the increase of velocity. By introducing the correction coefficient of magnetic Reynolds number, the eddy current demagnetization process is more realistic. Show more

Keywords: EMB, intensive impact load, demagnetization, magnetic Reynolds number, critical velocity

DOI: 10.3233/JAE-201556

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 66, no. 2, pp. 265-282, 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. 66, no. 2, pp. 283-295, 2021

Authors: Chen, Jun-Wei

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. 66, no. 2, pp. 297-312, 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. 66, no. 2, pp. 313-338, 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. 66, no. 2, pp. 339-357, 2021

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. 66, no. 2, pp. 359-368, 2021