International Journal of Applied Electromagnetics and Mechanics - Volume 56, issue 2

Authors: Li, Jinbang | Liu, Shuo | Qu, Jianjun | Cui, Yuguo | Liu, Yang

Article Type: Research Article

Abstract: The preload and load torque are two important operating parameters of traveling wave ultrasonic motors (TWUSMs), which have strong effects on the contact of stator and rotor. First, the effects of preload and load torque on vibrations of stator were investigated in this paper. A laser Doppler vibrometer was used to measure the vibration velocities of stator. According to the results, the vibration velocity curve of free stator is basically sinusoid. As the preload and load torque applied, the fluctuations in the peaks and troughs of the velocity curve are increased, which indicates that the movement trajectory of the particle …on stator surface is changed. The stator amplitude is not the only parameter which represents the drive capability of stator. The drive capability of stator is also related to the movement trajectory of the particle on stator surface. Then, the preload coefficient and load torque coefficient were proposed. Using the two coefficients, the effective amplitude could be obtained. Finally, the contact model considering preload and load torque was established. The performances of the motor were analyzed using the proposed contact model and the calculated results shown good agreements to the measured values. Show more

Keywords: Contact model, ultrasonic motor, contact mechanism, analytical method, vibration

DOI: 10.3233/JAE-160134

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 151-164, 2018

Authors: Golak, Sławomir | Przylucki, Roman | Smolka, Jacek | Bulinski, Piotr | Cieplinski, Piotr

Article Type: Research Article

Abstract: Cold crucible furnaces are widely used in multiple special applications. Unfortunately, the efficiency of this type of furnace is significantly lower than that of other induction units. The paper presents methodology and the analysis results of influence of the cold crucible components geometry on efficiency of transfer energy from an inductor to a charge. Distribution and the total value of the Joule heat generated in the charge inside an induction furnace with a cold crucible were determined for various modifications of construction of the typical furnace. The obtained results allowed for proposing a solution of the cold crucible with a …lowered, in comparison to the crucible wall, bottom and a reduced number of segments. Show more

Keywords: Cold crucible, electrical efficiency, numerical modelling

DOI: 10.3233/JAE-170026

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 165-172, 2018

Authors: Shi, Wenze | Wu, Yunxin | Gong, Hai | Zhang, Tao | Tan, Liangchen | Han, Lei

Article Type: Research Article

Abstract: The application of Electromagnetic Acoustic Transducers (EMATs) into metal materials has been hard to implement for the technical problems of low transduction efficiency and high sensitivity of lift-off variation. The process of transmission and detection of a shear wave in a spiral coil EMAT is established based on a 2-D axisymmetric model using finite element method. A new equivalent reception circuit for an EMAT receiver is provided, and it takes the open-circuit voltage of a receiving coil, the coil equivalent impedance, impedance matching network, and the input impedance of a preamplifier into consideration. On this basis, the conversion efficiency and …lift-off performance of the EMAT transmitter and receiver are investigated with respect to coil equivalent impedance, coil conductor diameter, impedance matching parameters, plate-to-coil distance and backplate thickness. Results indicate that compared with the specified EMAT without a backplate at a lift-off of 2 mm, the conversion efficiency and lift-off performance of the transmitting EMAT with a plate-to-coil distance of 1.5 mm can be respectively improved by 103.5% and 2.4 dB/mm, and the conversion efficiency and lift-off performance of the receiving EMAT with a plate-to-coil distance of 1.5 mm can be respectively enhanced by 85.5% and 1.6 dB/mm. Show more

Keywords: Spiral coil EMAT, transmitter and receiver, lift-off performance, conversion efficiency, equivalent reception circuit

DOI: 10.3233/JAE-170027

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 173-194, 2018

Authors: Cong, Haoxi | Du, Shiyue | Shu, Xiang | Li, Qingmin

Article Type: Research Article

Abstract: Secondary arc is widely existed in the power system, especially on the high-voltage transmission lines. The extinction of secondary arc is important to the single phase self-reclosing on power transmission lines. In this paper, based on the research of physical characteristics and modelling methods of secondary arcs in recent decades, the research status of the arc experiments, circuit simulation models, arc dynamic models and the extinction criteria were analyzed. The future research prospect of secondary arc is proposed, and the solutions to the key problems are provided. Combining with the dynamic model of the secondary arc, the space-time evolution characteristics …can be analyzed, and an on-line suppression method for the dynamic compensation of secondary arc is further proposed. Show more

Keywords: Secondary arc, physical characteristics, arc model, extinction criteria, suppression method

DOI: 10.3233/JAE-170041

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 195-209, 2018

Authors: Gao, Yucheng | Zhao, Wei | Qu, Kaifeng | Li, He | Shao, Haiming | Wang, Qing | Huang, Songling

Article Type: Research Article

Abstract: Heavy current transformers (HCTs) for large generators are intensively interfered by the stray magnetic field produced by heavy adjacent currents, and therefore, anti-interference testing is a crucial process to assure the robustness of HCT products. However, the generation of the interference involves multiphase heavy currents, which are difficult to produce in testing environments, and equivalent testing coils have become an emerging solution to the testing. In this paper, an improved parameter determination algorithm is proposed for the traditional two-segment testing coil configuration, and furthermore, a novel multi-segment testing coil configuration is proposed for better equivalence of the multiphase interference. The …effectiveness of the two configurations are thoroughly analyzed by FEM-based simulations as well as physical experiments. Show more

Keywords: Electromagnetic interference, heavy current transformers, partial coil, magnetic shielding, testing

DOI: 10.3233/JAE-170052

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 211-223, 2018

Authors: Lyu, Jiangwei | Zhou, Kai | Rong, Hai | Mao, Feilong

Article Type: Research Article

Abstract: This paper has proposed a 48/36 multiplicity SRM for a direct-drive rotary table of turn-milling machine tools which requires high torque, minimum torque ripple in milling mode and a wide constant power speed range in turning mode. Generally, rotary tables have a rotor with a large outside diameter to improve their torque output capability, hence a SRM with multiplicity topology is appropriate for such applications. However the design of multiplicity SRMs is not methodical yet. Thus a design methodology of multiplicity SRMs based on theoretical and finite-element analysis has been established and a method of estimating the number of turns …based on the supply voltage and the rated speed has been proposed. The static and dynamic characteristics of the proposed SRM are achieved by the finite-element method and a reasonable selection of the stator and rotor pole arc is fulfilled in compromise to satisfy the requirements of high torque, minimum torque ripple and a wide constant power speed range simultaneously. Besides, the dynamic simulation has validated the method of estimating the number of turns. Finally, flux linkage and torque static measurement have been carried out. The results show there a satisfactory agreement between the experimental measurement and finite element analysis results, thus validating the designed motor’s static performance. Show more

Keywords: Constant power speed range, direct-drive, design methodology, finite-element analysis (FEA), multiplicity, switched reluctance motors (SRM), torque ripple

DOI: 10.3233/JAE-170071

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 225-241, 2018

Authors: Coufal, Oldřich | Radil, Lukáš | Toman, Petr

Article Type: Research Article

Abstract: The article provides a comprehensive idea of the calculating the magnetic field and forces in a pair of parallel solid conductors. The conductors are connected to a sinusoidal voltage source of a frequency that does not exceed 1 MHz. Thus the current density over the conductor cross sections is not constant. Its distribution depends on the distance of the conductors and their resistivity, on the shape of conductor cross sections, and on the voltage source frequency. The distribution of current density over the conductor cross sections affects not only the magnetic field produced by the conductors but also the forces acting …on the conductors. For the acting forces, general conclusions are derived that hold for conductors of arbitrary shape of cross section. Specifically, pairs of conductors of rectangular, circular and triangular cross section are examined. Show more

Keywords: Applied classical electromagnetism, magnetic induction, dynamics of rigid bodies, forces and toques, numerical simulation

DOI: 10.3233/JAE-170077

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 243-261, 2018

Authors: Guo, Liyan | Xia, Changliang | Wang, Zhiqiang | Shi, Tingna

Article Type: Research Article

Abstract: When the interior permanent magnet (PM) machine operates under load condition, the armature current is ahead of the back electromotive force. However, the advanced armature current produces the demagnetizing field, which makes the irreversible demagnetization appeared in PMs easily. In this paper, aiming at the U-type PM structure, the expressions of the flux density components in the corresponding magnetizing directions of PMs at each node of PMs are derived. A calculation model to analyze the demagnetization in PMs is established in the Finite Element software by utilizing the derived expressions. Several improved geometries for rotor are proposed in this paper …to strengthen the anti-demagnetization ability of PM. Based on the established calculation model, effects of variables in the improved geometries on the demagnetization in PMs and the rated electromagnetic torque are analyzed in detail. Based on the analysis results, optimized improved rotor geometry is achieved giving consideration to the anti-demagnetization ability of PM and rated electromagnetic torque. Show more

Keywords: U-type PM structure, interior PM machine, improved rotor geometry, irreversible demagnetization

DOI: 10.3233/JAE-170084

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 263-274, 2018

Authors: Wen, Tao | Ming, Zhengfeng | Zhu, Zhanxia | Zhu, Wenzhi | Yuan, Jianping

Article Type: Research Article

Abstract: Magnetic suspension is a good choice for high precision manipulation. Several magnetic suspension systems have been proposed and shown to be effective for precision positioning. Most of these systems work with small air gaps and have a small movement range for suspended-load. Increasing the air gap will introduce uncertainty into the modeling and control of the system but is required for specific applications. The Large-Gap Magnetic Suspension and Balance System (LGMSBS) is a conceptual design for experiments which could be used to investigate the technology issues associated with magnetic suspension and accurate suspended-load control at large gaps. This paper investigates …regulation and the control methods of magnetic suspension, and proposed a novel design comprised of a cylindrical element containing a permanent magnet, a planar electromagnet array, a position sensing system, a control system. In order to increase the uniformity of the magnetic field and have control over the distribution of the magnetic field, a new structure called planar electromagnet array is established. The magnetic properties are investigated through the mathematical modeling method. Since the magnetic suspension system is highly nonlinear and inherently unstable in operation, this paper deals with the problems of modeling and control strategy for the LGMSBS with 3D-movement control, and numerical simulations and experiments are provided to demonstrate the effectiveness and validity of our conclusions. Show more

Keywords: Large-gap magnetic suspension and balance system, planar array of electromagnets, 3D-movement control

DOI: 10.3233/JAE-170087

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 275-291, 2018

Authors: He, Wei | Huang, Zheng-Yu | Li, Yue-Bo | Sun, Zheng | Zhou, Ying-Hui

Article Type: Research Article

Abstract: The orthogonal expansion based unconditionally stable FDTD method has been developed and attracted much attention recently. It can be implemented by two schemes: marching-on-in-order and paralleling-in-order solution, which respectively use weighted Laguerre polynomials (WLP) and associated Hermite (AH) functions as temporal expansions and testing functions. This paper proposed to use Legendre polynomials as another kind of orthogonal basis to make a new paralleling-in-order based unconditionally stable FDTD method. Numerical result shows it has much better performance in long time simulation case when compared with AH FDTD method.

Keywords: Finite difference time domain (FDTD), Legendre polynomials, paralleling-in-order, unconditionally stability

DOI: 10.3233/JAE-170093

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 2, pp. 293-299, 2018