International Journal of Applied Electromagnetics and Mechanics - Volume 58, issue 3

Authors: Huang, Mingming | Zhang, Yang | Huang, Quanzhen | Guo, Xinjun | Qing, YuHao

Article Type: Research Article

Abstract: With the merits of permanent magnet (PM) machine combining the possibility of controllable flux by field windings, hybrid excitation synchronous machine (HESM) is a novel candidate for wide speed range regulation application. The HESM with claw pole topology incorporates the advantages of the hybrid excited synchronous machine and claw pole machine. In this paper, the topology, operating principle and basic mathematical model of HESM are analyzed and established, respectively. Then, the control model of the HESM is deduced on the basis of the space vector control method, and the operating performance of the HESM across its entire operating range is …also investigated. A new adaptive control strategy for the HESM drive system is proposed and designed on the basis of analyzing the influences of the flux-weakening coefficient, respectively, which can operate in both flux-enhancing and flux-weakening conditions. The correctness and effectiveness of the proposed adaptive control strategy and drive system design are verified by simulation and experimental results, which demonstrate that the adaptive control strategy maximizes the range of speed regulation while exhibits the high efficiency. Show more

Keywords: Hybrid excitation, speed region control, wide speed range adjusting, vector control

DOI: 10.3233/JAE-180040

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 275-287, 2018

Authors: Xie, Shejuan | Xu, Panpan | Cai, Wenlu | Chen, Hong-En | Zhou, Haiqiang | Chen, Zhenmao | Uchimoto, Tetsuya | Takagi, Toshiyuki

Article Type: Research Article

Abstract: Aluminum foam is a functional material which is highly porous with cells of stochastic geometry. In distinction to polymer foam, aluminum foam is electrically conductive and has typical applications in many engineering areas. Optimal design and manufacture of foam structure usually require detailed understanding of the electrical property of the aluminum foam. In this study, a three-dimensional finite element numerical model based on the statistic characteristics of the geometrical structure of the closed-cell aluminum foam was proposed. The proposed numerical method was applied to study the property of the current conduction and to clarify the dependence of the electrical conductivity …on the porosity as well as the cell size. A shape factor defined based on the numerical simulation results is introduced to the theoretical model of the electrical conductivity regarding porosity, which can describe the relationship between the electrical conductivity and the porosity of the closed-cell aluminum foam properly. It was found that the porosity has a negative effect on the electrical conductivity in a power law approximately, while the cell size has a slight effect on the electrical conductivity of the closed-cell aluminum foam. Finally, the simulation results were compared to the experimental ones and their good agreement demonstrated the feasibility and accuracy of the proposed numerical model of the closed-cell metallic foam. Show more

Keywords: Closed-cell aluminum foam, electrical conductivity, finite element model, porosity, cell size

DOI: 10.3233/JAE-170147

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 289-307, 2018

Authors: Ogata, Shohei | Uchimoto, Tetsuya | Takagi, Toshiyuki | Dobmann, Gerd

Article Type: Research Article

Abstract: An electromagnetic acoustic transducer (EMAT) design using an air-cored solenoid coil as a pulsed electromagnet is proposed for the high-temperature non-contact monitoring of metal processing, and the operation of a prototype device is confirmed at temperatures ranging from room temperature to 700 °C. The coil generates a biasing magnetic field that allows the device to overcome the Curie temperature limitations of conventional EMATs. Pulse-echo measurements on carbon steel are made at high temperatures, and the superposition of the n th compression method is used as a signal processing technique to confirm that the shear wave velocity decreases with increasing temperature, …and it is verified that the EMAT can operate at high temperature. Show more

Keywords: Electromagnetic acoustic transducer, high-temperature environment, signal processing, pulsed magnet

DOI: 10.3233/JAE-180016

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 309-318, 2018

Authors: Chen, Changhao | Hu, Yefa | Wu, Huachun | Song, Chunsheng

Article Type: Research Article

Abstract: The International Space Station (ISS) has been regarding as a laboratory for experiments in numerous microgravity science discipline. However, the microvibration has a serious impact on science experiments on the ISS as well as existing electromagnetic actuators could not satisfy the requirement of good linearity needed for large stroke of low frequency vibration isolation platforms. This paper aims to design a maglev actuator with good linearity, which could be applied to microgravity vibration isolation platforms. Based on the principle of Lorentz force and self-demagnetization effect, the structural form and preliminary design indices of the actuator were presented. In order to …minimize the weight and heat consumption of its coil, parametric design was carried out and multi-objective optimization was adopted for it. Moreover, to investigate the dynamic characteristics of the actuator, system identification was performed to obtain a mathematical model of its control channel, which has good fitting degree of the time and frequency domain signals. Therefore, the result provides an important basis for structural optimal design of the actuator for microgravity vibration isolation system. Show more

Keywords: Maglev actuator, multi-objective optimization, dynamic characteristic, system identification, mathematical model

DOI: 10.3233/JAE-180037

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 319-335, 2018

Authors: Li, Xiangchao | Ma, Xiaoqi | Xu, Xiaopei | Cai, Lujin

Article Type: Research Article

Abstract: Based on the radiation of the transient electromagnetic fields in lightning discharge channel, we establish the simulated model of lightning channel in the laboratory and analyze the data and waveform, which are received by the low frequency magnetic antenna and the plate capacitance electric field change instrument. Thus we draw some conclusions. In the experiment, the energy of lightning current is mainly concentrated in the low-frequency stage, and the difference of energy between two frequency point decreases with the frequency growth. The waveform of plate capacitance appears after that of magnetic antenna. As the impulse current increasing, the coupling amplitude …and energy of the antenna have an increased trend and the growth of the magnetic antenna is more stable. When distance is further, the amplitude and energy of the antenna present a tendency of decrease. And the forepart is steep and the back is flat. The results have some significance on the research of lightning return stroke and lightning electromagnetic fields. Show more

Keywords: Lightning electromagnetic fields, antenna coupling, low-frequency magnetic antenna, plate capacitor

DOI: 10.3233/JAE-180034

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 337-345, 2018

Authors: Rehman, Obaid Ur | Tu, Shanshan | Khan, Shafiullah | Khan, Hashmat | Yang, Shiyou

Article Type: Research Article

Abstract: Quantum particle swarm optimization (QPSO) is a swarm intelligence method that has been successfully applied to solve a wide scope of electromagnetic inverse problems. The method encounters into local optima and insufficient diversity at the later phase of optimization. To address this type of issue, a new methodology is used to select the fittest particle, and a novel mutation mechanism is introduced, in which a mutation technique is applied on the global best particle to avoid the population from assembling and facilitating the individual to avoid the local optimum easily. In addition, a parameter updating strategy is proposed, which facilitates …the optimizer to maintain a good balance between local and global searches. To demonstrate the merit and efficiency of the proposed methodology, the evaluated results from the case studies are presented. Show more

Keywords: Electromagnetic design problem, global optimization, mutation, quantum mechanics

DOI: 10.3233/JAE-180015

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 347-357, 2018

Authors: He, Yucheng | He, Wei | Xiong, Bingquan | Guo, Pan | Xu, Zheng

Article Type: Research Article

Abstract: Ultra-low field magnetic resonance imaging (MRI) is a popular research topic in the field of mobile medical imaging. We construct a 50 mT ultra-low field MRI system for real-time monitoring of intracranial bleeding. The region of interest is a spherical space with a diameter of 200 mm, which is sufficiently large for a brain tissue. The homogeneity of the magnetic field determines the signal-to-noise ratio of MRI directly. First, the distribution of the main magnetic field is measured and expanded by using orthogonal spherical harmonic functions. Second, a harmonic coefficient method is used to design active shim coils of the …first two orders, with each coil generating a specific harmonic magnetic field. Lastly, the contour distribution of the stream function is utilized to obtain the winding of the shim coils. Results show that each shim coil can generate a pure harmonic magnetic field within an error of 5%. The magnetic field uniformity is reduced from 137 ppm to 28 ppm by these shim coils. Show more

Keywords: Active shim coils, magnetic resonance imaging, ultra-low field

DOI: 10.3233/JAE-180025

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 359-370, 2018

Authors: Iwamoto, Yuhiro | Kondoh, Syuhei | Ido, Yasushi | Yamamoto, Hisashi | Nishida, Hitoshi | Yamasaki, Haruhiko | Yamaguchi, Hiroshi | Jeyadevan, Balachandran

Article Type: Research Article

Abstract: Thermophysical and rheological properties of magnetic suspensions, in which nm- and/or μm-sized magnetic particles disperse, are tunable by applying a magnetic field externally. In the present study, the influence of the size of magnetic particles on the thermophysical and rheological properties was investigated. Four types of the magnetic suspensions were prepared with varying the volume fractions of nm- and μm-sized magnetic particles. The total fraction of the magnetic particles in all samples was adjusted to be 6 vol.%. The thermal conductivity in the presence of homogeneous magnetic field was measured by the originally-designed transient hot-wire method (TPSY02, CLIMA-TEC). And the …steady-state rheological behaviors were investigated by a magnetorheometer (MCR302, Anton-paar). As the obtained results, the thermal conductivity was enhanced when the magnetic field was applied parallel to the temperature gradient for all samples. On the other hand, the thermal conductivity decreased when the magnetic field was applied perpendicular to the temperature gradient in the case that both the nm- and μm-sized magnetic particles were dispersed. It was also found that the fluid only with the nm-sized magnetic particles showed a Newtonian-like behavior even in the presence of magnetic field. When the μm-sized magnetic particles were mixed and the fraction increased, the rheological behavior changed from Newtonian to viscoplastic fluid. Show more

Keywords: Magnetic suspension, magnetic fluid, MR fluid, bidisperse MR fluid, thermal conductivity, steady-state rheological behavior

DOI: 10.3233/JAE-180048

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 371-385, 2018