International Journal of Applied Electromagnetics and Mechanics - Volume 54, issue 3

Authors: Bao, Xiaohua | Zhang, Cheng | Hu, Yunpeng | Chen, Yuanyang | Sheng, Zhicai

Article Type: Research Article

Abstract: The multilayer magnetic shielding of the air-core reactor in power supply of Experimental Advanced Superconducting Tokomak (EAST) poloidal field (PF) is used as a model in this paper to analyze the eddy-current loss of shielding structure. Analytical method is adopted to deduce the eddy current loss of magnetic shielding. Then, several different combinations are established to calculate the total eddy current losses of multilayer shielding. 3D-finite element models (FEM) are applied to calculate the eddy current losses with different interlayer spacing and arrangement of layers. Those models are used to find out the changing characteristics of interlayer spacing and arrangement.These …methods mentioned in this paper can be applied for the further designing of low loss multilayer magnetic shielding. Show more

Keywords: EAST, poloidal field supply, combined shielding, eddy-current loss

DOI: 10.3233/JAE-160099

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 289-299, 2017

Authors: Yan, Liang | Zhang, Lu | Zhao, Yijing | Jiao, Zongxia

Article Type: Research Article

Abstract: Arrangement of permanent magnet (PM) poles and windings influences the magnetic field and force output of linear machines significantly. Various designs of PM linear machines have been proposed by researchers, either putting PM poles inside and coils outside, or vice versa. However, there is no systematic comparison of these two types of designs in literatures. The purpose of this study is to compare the magnetic field and force output of linear machines with different PM and winding structure topologies. Halbach array can not only produce high flux density, but also has self-shielding effect. So it is employed for the analysis. …Tubular structure is used because it helps to reduce flux leakage and enhance the system output performance. The magnetic field distribution of tubular linear motors with internal and external PM poles are formulated with Bessel functions, and the force output is thus obtained from Lorenz force law. The analytical models of magnetic field and force output are then validated with numerical computations. By utilizing the verified analytical models, design optimization is conducted with penalty functions for the two machine structures. The magnetic field and force output performance are then compared. It shows that the machine structure with internal PM poles helps to generate high force output. The study in this paper can also be implemented for the design of rotary machines. Show more

Keywords: Halbach array, linear machine, magnetic field, force output, optimization

DOI: 10.3233/JAE-160100

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 301-314, 2017

Authors: Hu, Jianxiong | Yi, Hong | Yin, Qifeng | Zhou, Xinlong | Lu, Rongsheng | Ni, Zhonghua

Article Type: Research Article

Abstract: Permanent magnet is the key component of nuclear magnetic resonance (NMR) instrument. Based on the principle of Halbach array, this study designs and optimizes a multilayer Halbach permanent magnet for human finger NMR detection. The quality factor (QF) is introduced to represent the performance of magnetic field, firstly. The impact on magnetic performance, caused by various magnet heights, is analyzed using Finite Element Method (FEM). In order to compensate the end effect, the radial adjustment method is proposed, combining the adjustments of the radial size and the radial position of the magnet blocks. Comparing the effect on magnetic field of …three different plans, the results show that combining the adjustments of inner radius and outer radius shims the field dramatically. Finally the designed construction is stacked by 11 layers of magic rings and each layer is composed of 8 trapezoid-shaped magnets. The magnetic field of the center cylindrical region (ϕ20 × 20 mm) of the structure is calculated, whose final strength achieves up to 447 mT and homogeneity is within 500 ppm. The designed magnet structure is manufactured and the measurement is finished in the end. The proposed construction has the advantages of small size and high uniformity, which has an extensive application prospect in portable NMR system. Show more

Keywords: NMR, permanent magnet, Halbach array, multilayer, radial adjustment

DOI: 10.3233/JAE-160101

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 315-327, 2017

Authors: Zhang, Yu | Huang, Songling | Zhao, Wei | Wang, Shen | Wang, Qing

Article Type: Research Article

Abstract: An increasing number of buried oil-gas pipelines are generated in recent years and defects occur with higher probability in their long-running process. This work proposes an electromagnetic ultrasonic guided wave (EUGW) long-term monitoring scheme for buried oil-gas pipelines and a data difference adaptive extraction method for the monitoring data. The T (0,1) mode guided wave is selected because of its non-dispersive characteristic. For the electromagnetic acoustic transducer (EMAT), a circumferentially magnetized nickel strap is bonded on the pipe to provide the bias magnetic field and the excitation coils are winded on the nickel strap to provide the dynamic magnetic field. …A detection stub is planted on the ground and the connector of buried coils is installed in the stub. The difference array is constructed and adaptive gain and attenuation are performed in the data difference adaptive extraction method. The EUGW long-term monitoring scheme is on-site applied for buried oil pipes in Jinan city, Shandong province, China. The EMAT is installed and buried with the pipe, and the periodical detection is conducted from December 2015 till now, once per month. A pit is found and verified by excavation at the distance 9.25 m from the buried EMAT on the flow direction. On-site detection results show that the data extraction method can dramatically improve the signal to noise ratio of the monitoring data and accurately extract the difference and variation of the pipe's structural health condition that occurred in the long-term service. The EUGW long-term monitoring scheme is proved to be a feasible method with prosperous prospect for the structural health monitoring of buried oil-gas pipelines. Show more

Keywords: Buried oil-gas pipeline, structural health monitoring, electromagnetic ultrasonic guided wave testing, data difference extraction

DOI: 10.3233/JAE-160115

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 329-339, 2017

Authors: Dalcalı, Adem | Akbaba, Mehmet

Article Type: Research Article

Abstract: Two 15W shaded pole motors with bridged and without bridge type stators were modeled using 2D and 3D analysis were performed using finite element analyzes. The magnetic behavior of the motor was determined by obtaining the magnetic flux density over the cross section of the motor and the air gap flux waveforms. Recently, a new modified structure of these motors has started to be seen in the literature, and this structure is called the bridged structure. The flux value transferred to the rotor in bridgeless motors is greater than with the bridged stator type. The harmonic components were obtained by …making the Finite Fourier analyses of the waveforms of flux densities. It was determined that the bridged structure had the disadvantage of having stronger harmonics than the bridgeless structure. The magnetic performances of 4 different rotor structures were examined in the rotor part of the bridgeless-type motor. The number of rotor slots were modified between 16 and 32 by selecting Type 1 on these different rotors. The optimum number of rotor slots was determined to be 26. It was stated that determining the optimum number of slots in the design of these motors would provide significant improvement in the performance. Show more

Keywords: Shaded pole motor, Finite Element Method, stator and rotor structure, optimum number of rotor slots

DOI: 10.3233/JAE-160133

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 341-350, 2017

Authors: Zeng, Zhiqiang | Lu, Qinfen | Ye, Yunyue

Article Type: Research Article

Abstract: The E-core hybrid-excitation linear switched-flux permanent magnet machine (LSFPMM) is low cost, which not only accommodates armature and permanent magnets (PMs) in short primary, but also cuts half of PM volumes compared with its C-core counterpart. It also can easily adjust the air gap magnetic field flexibly through the injection of different DC currents. This paper introduces E-HELSFM with different end shapes firstly, while a shape with the best symmetry of flux and minimal detent force is developed and further investigated. Based on finite element model, the flux-adjusting principle of the proposed hybrid-excitation motor is presented, and certain geometric parameters …are optimized for better flux-regulating capability and larger thrust force density. Then, the field ratio, which means the ratio of field area to a single slot area, is optimized to reach a tradeoff between force density and flux-adjusting capability. For the optimized model, the flux-adjusting as well as thrust force performances under different excitation conditions are investigated. Then, the flux-weakening control under different excitation levels is discussed. The simulated results show that the optimized machine exhibits good constant power operation capability through flux-weakening control and enhanced overload ability by flux-enhancing control. Show more

Keywords: Flux-adjusting, flux-weakening control, hybrid-excitation, optimization design, performance analysis, switched-flux

DOI: 10.3233/JAE-160138

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 351-366, 2017

Authors: Tian, Lisi | Yu, Qiang

Article Type: Research Article

Abstract: In this paper, a novel wide-speed-range sensorless control scheme for interior permanent magnet synchronous machines (IPMSMs) is proposed. At mid-high speed range, the super-twisting observer (STO) is designed to estimate the extended electromotive force (EMF). Adoption of sign function ensures the estimation accuracy without compromising the benefits of the standard sliding mode. The improved observation model combining the super-twisting algorithm (STA) alleviates the chattering problem. A new procedure of obtaining the position estimation error is proposed to eliminate the effects due to the change of the rotation direction. At low speed range, position error is obtained directly by extracting the …high frequency current from the sample data. The high frequency signal is further improved by introducing a novel adaptive filter to weaken DC bias component. The transition function provides the position error signal for the speed estimator and ensures a smooth switch between the two methods in the transition zone. The effectiveness of the proposed control scheme has been validated by the experimental results. Show more

Keywords: Permanent-magnet synchronous motor (PMSM), sensorless control, adaptive filter, super-twisting observer (STO), sliding-mode observer (SMO)

DOI: 10.3233/JAE-160150

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 367-387, 2017

Authors: Hedlund, Magnus | Abrahamsson, Johan | Pérez-Loya, Jesús José | Lundin, Johan | Bernhoff, Hans

Article Type: Research Article

Abstract: Two types of passive magnetic lift bearings were evaluated in terms of thrust force and eddy current losses. The first type of bearings were based on two sets of segmented Halbach arrays mounted in repulsive mode, and the second type was based on ring-magnets. The eddy-currents studied arose in the bearing due to manufacturing variations of magnetic remanence, and due to non-radial magnetization. Both a 3D time-dependent and a quasi-stationary Finite-Element Method (FEM) formulation were used, and the simulated results were compared with lift-force measurements from experiment. The losses were found (by FEM) to be in the order of 25 …W at a rotational speed of 30000 rpm while lifting a 45 kg rotor with a stiffness of 359 N/mm. Show more

Keywords: Flywheel energy storage, magnetic bearings, FEM, eddy-currents

DOI: 10.3233/JAE-160151

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 389-404, 2017

Authors: Xie, Nailiu | Zhang, Zhendong | Yin, Congbo

Article Type: Research Article

Abstract: The thermal field as a vinculum between electromagnetic and fluid flow of the solenoid fuel injector (SFI) which greatly impact on its comprehensive performances. For internal combustion engines, the higher fuel temperature is beneficial to generate smaller fuel droplets and faster evaporation. In order to reveal the coupling relationship among the multi-physical fields, a SFI is designed and manufactured, and four driving strategies circuits are designed. It is found that, for the certain magnetic circuit structure, the driving strategy is one of the most important factors that impact on the power losses and thermodynamic of the SFI. The power losses …are the main heat source generating high temperature for the coil. However, the high temperature of the coil is a disaster for the dynamic response and lifetime of the SFI, this phenomenon has been investigated by Finite Element Method (FEM) coupling simulation and experiments. The theoretical models of different power losses are carried out to investigate, and an experimental apparatus is designed and established to measure the temperature distribution of SFI magnetic circuit. Show more

Keywords: SFI, power losses, thermodynamic, multi-physical fields, coupling simulation

DOI: 10.3233/JAE-150143

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 405-419, 2017

Authors: Cheng, Xin | Liu, Han | Song, Shao | Hu, Yefa | Wang, Bo | Li, Yujia

Article Type: Research Article

Abstract: Towards at the active radial magnetic bearing with tightly-coupled redundant supporting structure, we propose a kind of fault-tolerant control strategy to make the remaining structures, under the failures of some electromagnetic actuators, reconfigured by compensating the magnetic flux loss to provide expected supporting force continually. By using FSS (fault status series) to describe the fault status of actuators, an index rule of the current distribution scheme has been designed to resolve different failure conditions of actuators. Fault-tolerant control model has been established to verify the electromagnetic force generation in tightly-coupled redundant supporting structures after failure of actuators. The influence characteristic …and mechanism of the bias current coefficient to electromagnetic force generation have been analyzed. The application example shows that fault-tolerant control strategy discussed can restrain the influence of the disturbing force to stabilize the rotor even under the failures of some actuators. In addition, inappropriate selection of the bias current coefficient will be easy to cause electromagnetic force limited by saturation constraint, and unable to provide the desired supporting force, which leads to rotor drop. Improving the real-time performance will effectively reduce the rotor jitter in the reconfiguration of redundant structure discussed. Show more

Keywords: Reconfiguration, active magnetic bearing, tightly-coupled redundant structure, fault-tolerant control

DOI: 10.3233/JAE-160113

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 421-432, 2017

Authors: Di Barba, Paolo | Liu, Bo | Mognaschi, Maria Evelina | Venini, Paolo | Wiak, Slawomir

Article Type: Research Article

Abstract: In the paper, the optimization of an electro-thermo-elastic microactuator is proposed. In particular, the maximum temperature of the actuator is to be minimized, while the total displacement is to be maximized. For solving this problem, the Adaptive Gaussian Process-Assisted Differential Evolution AGDEMO method is applied.

Keywords: Electro-thermo-elastic microactuator, multiphysics, finite-element analysis, efficient multiobjective design optimization

DOI: 10.3233/JAE-160118

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 433-448, 2017

Authors: Vértesy, G. | Balassa, P. | Gasparics, A. | Tomáš, I. | Mészáros, I.

Article Type: Research Article

Abstract: Improved eddy current techniques and a method of magnetic hysteresis measurement were applied for nondestructive inspection of thickness of the hardened surface layer of the steel injectors of diesel engines. A monotonic correlation was found with enough sensitivity and acceptable signal/noise ratio between the electromagnetic parameters and the thickness of the layer. Both the hysteresis and the eddy current methods show very similar types of the correlation. Based on these results, practical application of these novel methods can be realized instead of the presently used destructive tests for inspection of the steel injectors of diesel engines.

Keywords: Electromagnetic nondestructive testing, diesel engine injector, eddy current testing, magnetic hysteresis measurements, magnetic Adaptive Testing

DOI: 10.3233/JAE-160124

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 3, pp. 449-459, 2017