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

Authors: Aguilar, Arturo | Rubio, José de Jesús | Meda-Campaña, Jesús A. | Martinez, Dany Ivan | Vargas, Tomas Miguel | Garcia, Victor | Novoa, Juan Francisco | Mujica-Vargas, Dante | Pacheco, Jaime | Gutierrez, Guadalupe Juliana

Article Type: Research Article

Abstract: In this article, the mathematical model of a machine with eight immovable magnets and two movable magnets, and the machine with four immovable magnets and two movable magnets are introduced for the electricity creation. The proposed machines are based on the machine with two immovable magnets and two movable magnets, but they have two main differences: they have more interactions between the immovable and movable magnets, and they create more electricity. Experiments are included to validate that the proposed mathematical models represent a prototype and to observe which machine creates more electricity.

Keywords: Machines, immovable magnets, movable magnets, electricity creation, mathematical models

DOI: 10.3233/JAE-190087

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-20, 2020

Authors: Wang, Shaopeng | Ma, Jinguang | Liu, Chengcheng | Wang, Youhua | Lei, Gang | Guo, Youguang | Zhu, Jianguo

Article Type: Research Article

Abstract: To improve output torque ability and reduce torque ripple in traditional synchronous reluctance motor (TSynRM), a new synchronous reluctance motor (NSynRM) is proposed in this paper. The rotor of NSynRM is composed of both grain-oriented silicon steel and non-oriented silicon steel. With the reasonable design of rotor structure, the torque of NSynRM has been improved and its torque ripple has been reduced greatly. Firstly, TSynRM and NSynRM are qualitatively compared by using the magnetic network method. Secondly, the main parameters of these two machines are optimized by using finite element method (FEM). Then the performance comparison between two optimized machines …are carried out. Finally, the equivalent stress of these two machines at the maximum speed are analyzed. It can be seen that NSynRM can have 6.8% higher torque under rated load, 8% higher torque under maximum load, 17.5% wider constant torque operation region, and lower torque ripple compared with the TSynRM. Show more

Keywords: Synchronous reluctance machine, grain-oriented silicon steel, reluctance torque, magnetic network analysis, finite element method

DOI: 10.3233/JAE-190109

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-17, 2020

Authors: Shen, Sheng | Wu, Jiamin | Guo, Pan | Wang, Hongyi | Chen, Fangge | Meng, Fanqin | Xu, Zheng

Article Type: Research Article

Abstract: Comparing with superconducting and permanent magnet magnetic resonance imaging (MRI) system, ultra-low- field MRI (uMRI) system has a much lower weight, which can be used in some special scenes, such as real-time image monitoring on bedside or in the ambulance for human brain disease (stroke). In order to make the uMRI system more compact, lighter, and smaller, in this work, we proposed a hybrid method for designing uMRI electromagnet. The method consists of integer linear programming (ILP) and nonlinear optimization, which were bridged by empirical principles. ILP was used to determine the coil distribution of uMRI electromagnet. Considering that the …coil distribution, acquired with ILP, is not conducive for magnet processing, two empirical principles were applied to adjust the coil distribution with decreasing electromagnet performance as little as possible. At last, nonlinear optimization was exploited to eliminate the negative influence on magnetic field distribution which is introduced by coil adjustment and make electromagnet satisfy the design requirement of magnetic field homogeneity. This hybrid method combines mathematical models and empirical principles, which provides a way to design electromagnet efficiently. A small electromagnet with homogeneity of 10 ppm in a sphere region of interest (ROI) with diameter of 80 mm is designed and built in this paper. Show more

Keywords: Ultra-low-field MRI, electromagnet design, integer linear programming, nonlinear optimization

DOI: 10.3233/JAE-190051

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

Authors: Bu, Wenshao | Tu, Xiaowan | Lu, Chunxiao | Pu, Yi

Article Type: Research Article

Abstract: In order to solve the unbalanced vibration problem of bearingless induction motor caused by the rotor mass eccentricity, an adaptive feedforward vibration compensation control strategy is researched. Firstly, the inverse dynamic decoupling control method of torque system and the steady-state stochastic displacement feedback control of magnetic suspension system are introduced in brief. Then the feedforward compensation control strategy of unbalanced vibration displacement is discussed, taking the minimum mean square error of rotor radial displacement as a goal, an adaptive feedforward compensation control algorithm for unbalanced vibration displacement is designed, and by changing the amplitude and phase of the compensation signal …of unbalanced vibration displacement step by step iteratively, the influence of periodic unbalanced excitation force is suppressed or counteracted. Finally, the feedforward compensation control method is simulated and validated, and the influence of the detection deviation of motor speed on the vibration compensation effect is analyzed. The simulation experiment results show that the adaptive feedforward vibration compensation control strategy can significantly suppress the unbalanced vibration displacement during the sudden change of motor speed, and can eliminate the unbalanced vibration displacement in the steady state, and then the suspension control accuracy of the rotor is greatly improve. Show more

Keywords: Bearingless induction motor, unbalanced vibration displacement, adaptive feedforward vibration compensation, step by step iteratively

DOI: 10.3233/JAE-190092

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-17, 2020

Authors: Si, Zhanchao | Yang, Fan | Yao, Degui | Zhang, Guangzhou | Kou, Xiaoshi | Gao, Bing | Feng, Zhihui

Article Type: Research Article

Abstract: The UHV transmission lines usually have large regional spans and involve various weather conditions, which will have different effects on the circuit design and electromagnetic environment. However, the existing research lacks the ion flow field analysis of AC and DC parallel lines under different weather conditions. Hence, we studied the distribution law of the ion flow field of ±800 kV DC and 500 kV AC parallel transmission lines under different weather conditions, and compared the calculated results with measured results. First, we used the meshless method to model the ion flow field of AC and DC parallel lines in different weathers. Then, …the influence of environmental factors on the ion flow field was analyzed. The effects of temperature, humidity and haze on the distribution of the ion flow field were obtained based on long-term monitoring and measurement. Results show that the ion flow field of the theoretical calculation results was basically in accord with the actual measurement. The ion flow field of parallel lines increases with the rise of temperature, first increases and then decreases with the rise of humidity, and increases with the rise of haze. Show more

Keywords: Ion flow field, weather conditions, parallel lines, meshless method

DOI: 10.3233/JAE-190113

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

Authors: Qiu, Li | Deng, Kui | Li, Yantao | Tian, Xi | Xiong, Qi | Chang, Peng | Su, Pan | Huang, Lantao

Article Type: Research Article

Abstract: The long-life driving coil is the prerequisite for electromagnetic forming industrial application. Up to date, the temperature rise is one of the major factors that restrain its working life. For the purpose of reducing the temperature rise of the driving coil, this paper proposes a new coupled cooling method, in which an extra cooling coil is placed on one side of the driving coil, then the Joule heating is coupledly transferred by delaying the breakover control of the driving coil. To achieve this purpose, a finite element simulation model of Electrical Circuit- Electromagnetic Field-Thermal Coupling in the plates setting of …the electromagnetic forming is established, after which the influence rules of coil turns, cross-sectional area and materials of cooling coil on temperature rise are analyzed. Then, this paper also establishes a coupled cooling circuit model, in which the influence of cooling coil structure parameters on the Joule heating of driving coil is analyzed. Furthermore, Simulation results show that effective Joule heating transfer can be reached by the best optimization scheme of the cooling driving coil. Specifically, the average temperature rise reduces by 13 degrees, namely 22.8% by using this new method. Show more

Keywords: Electromagnetic forming, driving coil, temperature rise, Joule heating

DOI: 10.3233/JAE-190062

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2020

Authors: Zhang, Yunfeng | Gu, Jialiang | Zhang, Erchun

Article Type: Research Article

Abstract: Studying underground propagation effects of lightning electromagnetic fields in different geological environments will contribute to more reasonable designs for protecting underground cables and electronic equipment. In this paper, we have analyzed influences of different geological environments, depths and soil water content on underground propagation of lightning electromagnetic fields in detail by using the nite difference time domain (FDTD) method in the 2-D cylindrical coordinate system to calculate components of underground electromagnetic fields at a horizontal distance of 200 m, including vertical electric field E z , horizontal electric field E r and azimuthal magnetic field H 𝜑 …. The results show that the underground electric field is predominantly horizontal. Propagation of lightning electromagnetic fields in wet clay and wet limestone environment changes significantly compared to freshwater environment. Attenuation is larger with depth in wet clay and wet limestone, while propagation is unaffected in freshwater. When water content in soils ranges from 5% to 25%, the vertical electric field has the largest attenuation and the azimuthal magnetic field has the least attenuation. The electromagnetic fields in clay are most sensitive to changes in water content. Show more

Keywords: FDTD, lightning electromagnetic fields, different geological environments, water content, underground propagation

DOI: 10.3233/JAE-190112

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

Authors: Yang, Xiaolong | Sun, Peng | Hao, Fuxiang

Article Type: Research Article

Abstract: In order to improve the pressure capability of the ferrofluid seal under the condition of large sealing gap, a diverging stepped ferrofluid seal with a large gap and two magnetic sources was designed. The magnetic field distributions in the gap of the ferrofluid seal were calculated by finite element method. The effects of the pole teeth number, the height of the pole teeth and the sealing gap on the pressure capabilities of the diverging stepped ferrofluid seal are studied and compared with ordinary ferrofluid seal. The results show that the change of the radial pole teeth number has little effect …on the pressure capability of the stepped ferrofluid seal. The pressure capability of stepped ferrofluid seal decreases with the increase of the axial pole teeth number. The pressure capability of the stepped ferrofluid seals reach maximum when the radial and axial pole teeth height is 0.6 mm. The pressure capability of stepped ferrofluid seal decreases as the radial sealing gap increases. The pressure capability of stepped ferrofluid seal decreases firstly and then increases with the increase of the axial sealing gap. Comparing with ordinary ferrofluid seal, the stepped ferrofluid seal has better pressure capability. Show more

Keywords: Large gap, diverging, ferrofluid, seal, numerical simulation

DOI: 10.3233/JAE-190127

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2020

Authors: Zhang, Jin | Zhang, Qiuju

Article Type: Research Article

Abstract: The purpose of this paper is to optimize the PM arc ratio of consequent pole permanent magnet vernier machine (CP_PMVM). The operation principle of the CP_PMVM is discussed. An optimization parameter K 𝛼 related to the PM arc ratio is derived. For the CP_PMVM, the amplitudes of the 4th and 14th order harmonics of the air-gap flux density, the amplitude of the back electromotive force (back-EMF) and the average torque all have positive correlations with K 𝛼 . The optimal PM arc ratio is 0.64. The three phase inductances are approximately constants, and the d -axis inductance is equal …to the q -axis inductance. The PM flux linkages are sinusoidal. The no-load back-EMF waveform of the measured phase is nearly sinusoidal. The gear ratio of the CP_PMVM evaluated from the back-EMF is close to the design value. Furthermore, a controller according to the mathematical model is designed. The CP_PMVM vector control with a sliding-mode (SM) speed controller exhibits a smooth starting, and has an anti-jamming capability. Show more

Keywords: Consequent pole (CP) rotor, permanent magnet vernier machines (PMVM), sliding mode (SM), vector control

DOI: 10.3233/JAE-190061

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

Authors: Hasan, Alfaisal A. | Mekheimer, Khaled S. | Tantawy, Bassem E.

Article Type: Research Article

Abstract: The present work studies magnetohydrodynamic stability with streaming resistive triple superposed fluid layers. This system is influenced by an oblique magnetic field. The solution of motion equations by using the method of perturbation analysis under the boundary conditions which leads to deriving the dispersion relationship describing the behaviour of the perturbed and unperturbed system. The effect of different parameters on the stability and the instability of this system was studied. Regions of stability and instability are identified by drawning the curves to illustrate the regions of stability and instability behaviour. It is found that the magnetic field permeability coefficient, the …intensity of the magnetic field values, the increase of the fluids density values and the streaming velocity have destabilizing influences on the considered system. The presence of an oblique magnetic field plays a stabilizing role and can be used to retard the destabilizing influence. Show more

Keywords: Self-gravitating, resistive, superposed fluids, streaming, oblique magnetic fields

DOI: 10.3233/JAE-190110

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2020