International Journal of Applied Electromagnetics and Mechanics - Volume 54, issue 1

Authors: Li, Yuanyuan | Lei, Gang | Sun, Yu | Wang, Li

Article Type: Research Article

Abstract: This paper uses finite element method to analyze the effect of brace stiffness and damping of an electromagnetic bearing on the critical speed of a flexible rotor for the rotor system of a high-speed turbo-expander. Result shows that eight orders of critical speed and eight modal shapes exist in the range of the calculation speed for the flexible rotor system of an electromagnetic bearing. The first six orders of vibrations are swing of rigid body, in which the critical speed increases with increase of the brace stiffness of the bearing. The seventh and eighth orders are first-order bending, in which …the stiffness of the bearing has little influence on the critical speed of the rotor. Adjusting the stiffness of magnetic bearing can significantly change the corresponding critical speed of the rotor during rigid body swing. However, doing so has little influence on the critical speed of the first-order bending. The rotor system experimental test results of turbo-expander electromagnetic bearing show that adjusting the brace stiffness and damping of electromagnetic bearing through the control system can change the distribution of each order of the critical speed of the rotor system to maintain a steady working speed of 30000 r/min. Moreover, the movement tracks of the rotor axis center can be maintained within 6 μ m when external influences interfere with the rotor during operation. Show more

Keywords: Active electromagnetic bearing, rotor dynamics, stiffness and damping, stability

DOI: 10.3233/JAE-160043

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 1-12, 2017

Authors: Chen, Cheng-Chang | Chen, I-Fong | Peng, Chia-Mei | Hsue, Ching-Wen | Jiang, Zong-Han | Liao, Heng-Yi

Article Type: Research Article

Abstract: A novel multi-band broadband antenna for mobile handsets application is proposed and analyzed in this paper. An asymmetric T-type monopole antenna with a shorting-line is designed to be operated in long term evolution (LTE, 698 MHz-960 MHz, 1710 MHz-2170 MHz, 2500 MHz-2690 MHz) and wireless local area network (WLAN, IEEE 802.11ac, 5150 MHz-5850 MHz) bands. A prototype of the proposed antenna with 50 mm in length and 8 mm in width is fabricated and investigated experimentally. The experimental results indicate that the bandwidths for VSWR of 3:1 achieved were 37.75%, 24.63%, 11.46% and 21.76% at 800 MHz, 1900 MHz, 2600 …MHz and 5500 MHz, respectively. The specific absorption rate (SAR) for an input power of 24 dBm in LTE band, and an input power of 13 dBm in IEEE 802.11ac band meet the SAR limit of 1.6 mW/g. Experimental results verify the prediction of the theoretical analysis. Show more

Keywords: LTE-band antenna, mobile handsets, T-type monopole, shorting-line, specific absorption rate (SAR)

DOI: 10.3233/JAE-160061

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 13-22, 2017

Authors: Li, Yunfei | Zeng, Xiangguo | Wei, Liming | Wan, Qiang

Article Type: Research Article

Abstract: Metal magnetic memory (MMM) technique can be potentially applied to evaluate early damage of ferromagnetic materials nondestructively due to its high sensitivity to stress-strain state. An experimental investigation of the characterizations of mechanical damage-induced magnetization in X80 pipeline steel specimens has been undertaken. Different degrees of plastic deformation are introduced into specimens with different initial discontinuities. The surface strain distribution and metal magnetic memory signal in specimens are measured during and after tensile testing. The experimental results indicate that, at first the magnetization direction of material depends on the loading direction and the distribution pattern of magnetization reflects the existence …of stress concentration. Second, the correlation between peak-valley amplitude of memory signal B_Z and maximum plastic deformation follows a similar formula proposed in this paper, which is independent of specimen type. The results of present work could potentially be used to quantitatively evaluate the degree of stress concentration of X80 pipeline steel components. Show more

Keywords: X80 steel, damage-induced magnetization, metal magnetic memory, plastic deformation, nondestructive evaluation

DOI: 10.3233/JAE-160074

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 23-35, 2017

Authors: Wang, Xiaoyuan | Du, Jingjuan | Gao, Peng | Lv, Haiying

Article Type: Research Article

Abstract: Thermal analysis of Electric Machine for Electric Vehicles (EVs), is crucial for precisely predicting the temperature distribution. In the paper, for a forced-air cooled induction machine, two methods of thermal models analysis are compared with measurements. The first numerical method is Computational Fluid Dynamics (CFD) over Finite Element Method (FEM). And the second one uses Lumped Parameter Method (LPM). For the analysis based on CFD over FEM, a 3D induction machine is modeled with force-air cooling housing. The air flow is simulated and the losses are calculated as heat source for thermal models. FEM is coupled with CFD to get …the thermal field distribution. For the LPM, the equivalent thermal resistance of winding, the heat transfer coefficients of the airgap and forced air are calculated in the LP thermal model. Finally, Measurement results are determined by PT100 embedded in winding end, as well by infrared instrumentation for measuring the image on the shell thermal distribution. Experimental validation is presented and the conclusion can be drawn from comparing these aspects of two methods, providing some reference for the research applied in motor for EVs. Show more

Keywords: Forced air-cooling system, thermal analysis, LPM, FEM, CFD

DOI: 10.3233/JAE-160092

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 37-56, 2017

Authors: Tu, Xiao | Zhou, Rougang | Zhou, Yunfei | Cheng, Xin

Article Type: Research Article

Abstract: This paper concerns the dynamical decoupling and feed-forward control of magnetically-levitated planar actuators (MLPAs) with moving coils when the moving stage's center-of-mass (CM) deviates from the geometric center (GC). Based on the direct wrench-current decoupling, the factors that affect the continuity of current are emphatically analyzed for a more stable current control, and the propulsion works at CM is converted at GC with Newton-Euler dynamic equation. By inverting the system dynamics, 6 degrees-of-freedom (DOF) individual control is realized and the system is simplified from MIMO to SISO. Based on the decoupling, an acceleration feed-forward controller with PID control is designed. …By studying the coupling parameter relating to feed-forward inputs and white noise, the acceleration amplification coefficient is achieved and the PID parameters will be optimized based on comparing the actual variance with the minimum achievable variance. Last, the simulation results indicate that the feed-forward compound controller applying to MLPAs system has a better performance than the general PID controller. Show more

Keywords: Magnetically levitated planar actuators, dynamical decoupling, continuity of current, center of mass deviation, inverse transformation, acceleration feed-forward controller

DOI: 10.3233/JAE-160102

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 57-76, 2017

Authors: Abu-Nabah, Bassam A.

Article Type: Research Article

Abstract: Due to their high strength characteristics and excellent corrosion resistance behavior operating at different temperature ranges, titanium and nickel alloys have been gaining rapid popularity as part of weld overlay and metal spraying technologies. This has been raising the demand for a reliable and practical nondestructive evaluation technique to assess metallic coating thicknesses over nonmagnetic metals. Because of its frequency-dependent penetration depth, eddy current technology lends itself to assess such nonmagnetic layered structures. Nevertheless, impedance forward measurement techniques are sensitive to both coating/substrate conductivities and lift-off deviations from those used over the calibration blocks. This affects the accuracy and limits …the capabilities of existing impedance-based inversion models in estimating coating thicknesses. This study takes the first step towards adopting AECC spectroscopy as an alternative forward measurement technique, which offers a reduced sensitivity to both deviations in a broad range of inspection frequencies. More importantly, a new AECC-based inversion algorithm is developed to estimate metallic coating thicknesses over nonmagnetic metals. This work is validated following the plane-wave approximation and COMSOL simulations over different coating thicknesses relevant to the industry. Show more

Keywords: Nonmagnetic, coating thickness, eddy current, nondestructive testing, inversion

DOI: 10.3233/JAE-160103

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 77-91, 2017

Authors: Cao, Yongjuan | Tao, Shaoqin | Cai, Jun | Yu, Li | Jia, Hongyun | Zhang, Tao

Article Type: Research Article

Abstract: This paper presents an analytical solution of the magnetic field in a coreless stator axial-flux permanent magnet (AFPM) machine, including axial, radial and circumferential components of the air-gap flux density. Based on the three-dimensional (3-D) analytical field solution, the paper also presents the analytical analysis of axial electromagnetic force of the rotor discs using Maxwell stress tensor method. The effect of some sizes on the axial electromagnetic force is analyzed. For the verification, 3-D finite element method (FEM) is accomplished to analyze the magnetic field and electromagnetic force. The solution and calculation are useful in design and optimization of coreless …stator AFPM machines. Show more

Keywords: Coreless stator axial-flux permanent-magnet (AFPM), electromagnetic force, magnetic field analytical solution, Maxwell stress tensor

DOI: 10.3233/JAE-160112

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 93-105, 2017

Authors: Rehman, Obaid Ur | Yang, Jiaqiang | Zhou, Qiang | Yang, Shiyou | Khan, Shafiullah

Article Type: Research Article

Abstract: Mutation operator is one of the mechanisms of evolutionary algorithms to guarantee the diversity in the search of an algorithm to help exploring undiscovered search spaces. Thus, in this work, a modified Quantum-inspired Particle Swarm Optimization (QPSO) algorithm for global optimizations of inverse problems is presented. In the proposed algorithm, a new mutation strategy is applied on the personal best particle to improve its global searching ability, also an improved Factor (iF ) is incorporated into the position update equation of QPSO to further enhance its convergence speed. In addition, a new parameter updating strategy is proposed to tradeoff between …the exploration and exploitation searches. To evaluate its performance, the proposed approach has been applied to a set of well-known mathematical test functions and an engineering inverse problem i.e. TEAM Workshop Problem 22. The experimental results demonstrate the effectiveness and advantage of the proposed method. Show more

Keywords: Global optimization, inverse problem, mutation, particle swarm optimization

DOI: 10.3233/JAE-160114

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 107-121, 2017

Authors: Zhang, Hong | Liao, Leng | Zhao, Ruiqiang | Zhou, Jianting | Yang, Mao | Zhao, Yayu

Article Type: Research Article

Abstract: This paper presents a new judging principle for corrosion testing of steel bars buried in reinforced concrete based on the self-magnetic flux leakage. The magnetic field signals decrease monotonously with the increase of the lift-off height of the magnetic sensor, which denotes the distance between the magnetic sensor and the specimen surface, for the undamaged area of the reinforcing steel bar while a reversal phenomenon appears for the corroded area. The lift-off height related to the reversal point will increase with the increase of the corrosion degree, and the corroded area could also be extracted from the magnetic field data. …The competition between the demagnetizing field and the magnetic flux leakage from the corroded area could be used to explain the phenomena. The results indicate that the lift-off height related to the reversal point can be acted as the judging criterion for assessing the corrosion degree and the corrosion area of the reinforcing steel bar. The findings have extensive application prospect for detecting and evaluating the corrosion degree of reinforced concrete in engineering practice. Show more

Keywords: Corrosion testing, self-magnetic flux leakage, steel, reinforced concrete

DOI: 10.3233/JAE-160122

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 123-130, 2017

Authors: Yu, Qiang | Wang, Xuesong | Cheng, Yuhu

Article Type: Research Article

Abstract: This paper presents the electromagnetic and thermal characteristics of a novel canned Switched Reluctance Machine (SRM) as a hydraulic pump drive. Due to considerable loss generated from the can shield in airgap, the characteristics are of fundamental differences from an ordinary machine. To identify the can effect, the magnetic field and heat transfer are respectively identified, followed by a coupled analysis due to high temperature rise on the can shield that significantly affects airgap flux. Specifically, improved thermal and electromagnetic models are respectively proposed to enhance calculation accuracy with small computation. Then, the coupling between airgap flux and temperature rise …on the can shield is studied. The electromagnetic and thermal features are validated with measurements. Show more

Keywords: Canned switched reluctance machine, can shield loss, electromagnetic analysis, coupled analysis, measurements

DOI: 10.3233/JAE-160126

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 54, no. 1, pp. 131-140, 2017