International Journal of Applied Electromagnetics and Mechanics - Volume 68, issue 3

Authors: Dash, Rajib Kumar | Saha, Puspendu Bikash | Ghoshal, Dibyendu | Palai, Gopinath

Article Type: Research Article

Abstract: In this article two fractal geometry-based slotted patch antennas are designed to achieve wideband response with multiband characteristics and reduced cross polarized radiation in both E- and H-plane for all the resonating bands. The proposed antennas are fed with microstrip line feeding formed on a FR4 substrate of size 0.25𝜆0 × 0.25𝜆0 × 0.02𝜆0  mm3 and loaded with a partial ground plane at the bottom of the substrate. HFSS is used to design and simulate both the antennas. Wideband behavior and impedance matching of Antenna-1 are improved by optimizing the factor of iteration and length of the ground plane. …Due to addition of 3 identical split ring resonators (SRR) with the antenna geometry leads to achieve multiband response in Antenna-2. The dimensions of the SRR connectors and feedline have been optimized through parametric analysis to match the impedance properly at all the three resonating bands. It has been found that simulated and measurement results of both the antennas are properly matched. Show more

Keywords: Line feeding, multiband, partial ground plane, triangular slots, wideband

DOI: 10.3233/JAE-210098

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 68, no. 3, pp. 275-294, 2022

Authors: Wang, Jun-Gang | Qian, Li-Qun | Zhang, Bin

Article Type: Research Article

Abstract: Magnetic gear is a non-contact transmission mechanism, which overcomes the drawback of mechanical gear transmission. Although the series multi-stage magnetic gear can provide a large gear ratio compared to the single-stage magnetic gear, the lower torque density of the series multi-stage magnetic gear limits its use in high-power wind turbines. According to the magnetic gear field modulation mechanism and the differential transmission method, a differential multi-stage coaxial magnetic gear transmission device is proposed, which can achieve transmission with a large gear ratio and large torque density. Based on the differential multi-stage coaxial magnetic gear structure and its working principle, the …finite element method is used to simulate the electromagnetic performance of the multi-stage coaxial magnetic gear. Futhermore, the electromagnetic performance of the two stages of the proposed magnetic gear are compared. The results show that there is a significant difference between the the electromagnetic performance of the first stage and that of the second stage. The torque ripple of the first stage is more dramatic than that of the second stage. The torque ripple amplietude of the inner rotor of the first stage is 5.08‰ larger than that of the second stage. The torque ripple amplietude of the outer rotor of the first stage is 4.591‰ larger than that of the second stage. Show more

Keywords: Multi-stage, magnetic gear, gear ratio, finite element analysis, torque ripple

DOI: 10.3233/JAE-210117

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 68, no. 3, pp. 295-309, 2022

Authors: Wang, Jungang | Qian, Liqun | Xu, Shuairui | Zhang, Bin

Article Type: Research Article

Abstract: Magnetic gear has the advantages of less noise and vibration in non-contact driving and has a broad application prospect. To improve the magnetic gear’s torque performance, an improved double-flux-concentrating coaxial magnetic gear (DFC-CMG) is proposed in this paper. The DFC-CMG adopts arc-shape inner permanent magnets (PMs) and spoke-type outer PMs, which are embedded in the rotor iron yoke and tangentially magnetized along the circumference. In addition, to reduce the amount of iron, the outer rotor yoke periphery of the proposed model is slotted. The finite element method (FEM) is used to simulate conventional and improved models, respectively. The air gap …magnetic field and electromagnetic torque of the conventional model and the improved model are calculated, and the harmonic content of the inner and outer air gap magnetic density is analyzed. Simulation results show that the torque density of the improved model is 34.6% higher than that of the conventional model, and the output torque ripple of the outer rotor of the improved model is reduced by 0.58% compared to the conventional model. This paper can provide some references for high-performance magnetic gears. Show more

Keywords: Magnetic gear, permanent magnets, finite element method (FEM), torque capacity, torque ripple

DOI: 10.3233/JAE-210128

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 68, no. 3, pp. 311-328, 2022

Authors: Tian, Lei | Song, Limei | Zheng, Yu | Wang, Jinhai

Article Type: Research Article

Abstract: Multi-coil magnetic stimulation has advantages over single-coil magnetic stimulation, such as more accurate targeting and larger stimulation range. In this paper, a 4 × 4 array multichannel magnetic stimulation system based on a submillimeter planar square spiral coil is proposed. The effects of multiple currents with different directions on the electromagnetic field strength and the focusing zone of the array-structured magnetic stimulation system are studied. The spatial distribution characteristics of the electromagnetic field are discussed. In addition, a method is proposed that can predict the spatial distributions of the electric and magnetic fields when currents in different directions are applied …to the array-structured magnetic stimulation system. The study results show that in the section of z = 2 μm, the maximum and average magnetic field strengths of the array-structured magnetic stimulation system are 6.39 mT and 2.68 mT, respectively. The maximum and average electric field strengths are 614.7 mV/m and 122.82 mV/m, respectively, where 84.39% of the measured electric field values are greater than 73 mV/m. The average magnetic field strength of the focusing zone, i.e., the zone in between the two coils, is 3.38 mT with a mean square deviation of 0.18. Therefore, the array-structured multi-channel magnetic stimulation system based on a planar square spiral coil can have a small size of 412 μm × 412 μm × 1.7 μm, which helps improving the spatial distribution of electromagnetic field and increase the effectiveness of magnetic stimulation. The main contribution of this paper is a method for designing multichannel micro-magnetic stimulation devices. Show more

Keywords: Multichannel micro-magnetic stimulation, planar square spiral coils, 4 × 4 coil array, spatial distribution of electromagnetic field

DOI: 10.3233/JAE-210139

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 68, no. 3, pp. 329-346, 2022

Authors: Xia, Tian | Zhu, Falong | Kang, Peng | Sheng, Buyun | Qiu, Yiming

Article Type: Research Article

Abstract: For avoiding the damage of the insulation and permanent magnet, the temperature rise of the PMSM (permanent magnet synchronous motor) should be controlled strictly, it is usually one of the main objectives during improving the output power and torque density beyond the state-of-the-art in motor design. In this research, the coolant channel will be placed within the yoke of the stator core to enhance the heat transfer between the stator core and the coolant. Hydrophobic coating is applied to replace the metal tube for increasing the utilization of the cross area of the coolant channel. The impact of the coolant …channel on the performance of the permanent magnet motor is analyzed. A general design method of the coolant channel is presented. The result shows that the change of the stator core loss is within about 10% as the coolant channel is moved away from the slot along the radial direction while the back electromotive force of the motor could keep constant through appropriate design. The impacts of the coolant channels on the magnet performance and the heat dissipation performance could be divided completely with the design method. The method can be applied on various PMSM including SPM (surface-mounted permanent magnet motor) and IPMSM (interior permanent magnet synchronous motor). Sufficient coolant flow could be provide to help conduct the temperature rise of the motor. Show more

Keywords: Permanent magnet motor, electromagnetic performance, hydrophobic coating, coolant channel

DOI: 10.3233/JAE-210142

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 68, no. 3, pp. 347-369, 2022

Authors: Ai, Mengmeng | Liu, Wenhui | Shan, Yi

Article Type: Research Article

Abstract: In the process of Ultra high voltage direct current (UHVDC) transmission, the direct current (DC) bias of power transformer is easily induced, which makes the transformer exciting current distorted, the ferromagnetic material saturated and the magnetic leakage increased, and then leads to the increase of core vibration and noise. Aiming at this problem, taking a 240 MVA, 330 kV three-phase five-column power transformer as an example, the coupling of the electromagnetic field, structural force field and acoustic field is studied, and the influence of DC bias on vibration and noise of power transformer core is analyzed in this paper. According to the …magnetic density and electric density of transformer core under different magnetic bias degree, the structural force field is solved, and the displacement and surface acceleration of core are obtained, which can be as the excitation of sound field to determine the noise distribution of transformer. In order to avoid the natural frequencies which easily cause resonance, the modal analysis is needed to obtain the natural frequencies and modal modes of the core. The transformer noise under no-load and DC bias conditions of the prototype is tested experimentally and compared with the theoretical calculation, the results prove the accuracy of the simulation calculation method in this paper. Show more

Keywords: DC bias, transformer, modal analysis, vibration, noise

DOI: 10.3233/JAE-210159

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 68, no. 3, pp. 371-385, 2022