International Journal of Applied Electromagnetics and Mechanics - Volume 47, issue 3

Authors: Cao, Quanliang | Han, Xiaotao | Li, Liang

Article Type: Research Article

Abstract: A simple active microfluidic mixing system based on magnetic actuation strategy of fluids in the microchannel under a hybrid gradient magnetic field was proposed. The hybrid magnetic field, combined of a static gradient magnetic field and an external AC uniform magnetic field, is specially designed to generate periodic magnetic body forces acting on the mixed fluids. Two-dimensional numerical simulation has been performed to investigate the mixing behavior caused by the interactions of magnetic field, fluid flow …and convection-diffusion. Numerical results show that the proposed mixer system achieved up to 97% mixing of the two fluids with a small current flowing in micromagnets. Show more

Keywords: Microfluidic mixing, gradient magnetic field, magnetic force, finite element analysis

DOI: 10.3233/JAE-140057

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 583-592, 2015

Authors: Su, Jen-Pao | Wu, Jong-Shinn | Lee, Ya-Wei

Article Type: Research Article

Abstract: In this study, an electromagnetically controlled cooling device (ECCD) is proposed, employing magnetic nanofluid (MNF) and electromagnetohydrodynamics to ameliorate the waste-heat dissipation of mechatronic systems. The MNF was charged in a condenser chamber as an auxiliary coolant, and was prepared from fine ferromagnetic particles of iron ferrite by using a chemical coprecipitation technique. A radial basis function neural network-based training model was employed for examining the electromagnetic resonance of the ECCD at …a wide heating range. Satisfactory agreement between the experimental and predicted results indicated the accuracy of the model in capturing the ECCD dynamics. The nonlinearity of ECCD dynamics were also identified as a feature of frequency resonance by mapping a discrete-time model into generalized frequency response functions (GFRFs). Accordingly, the effect of electromagnetic induction relating to ECCD performance can be further confirmed. Show more

Keywords: Electromagnetically controlled, magnetic nanofluid (MNF), radial basis function neural network (RBF NN), generalized frequency response functions (GFRFs)

DOI: 10.3233/JAE-140062

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 593-605, 2015

Authors: Hoole, S. Ratnajeevan H. | Karthik, Victor U. | Sivasuthan, Sivamayam | Rahunanthan, Arunasalam | Thyagarajan, Ravi S. | Jayakumar, Paramsothy

Article Type: Research Article

Abstract: This paper reviews mathematical optimization in synthesis and nondestructive evaluation (NDE) by the finite element method in magnetics because background work has been inadequately attributed in the literature. The review identifies the earliest papers and reports new work in nondestructive evaluation and GPU-based matrix solution to save time and memory. Although the genetic algorithm has been applied in optimization, in coupled systems the number of object function evaluations doubles. We therefore examine the use of …graphics processing units (GPUs) to handle the immense computational load. GPU memory limits are often not recognized and are critically limiting when parallelizing the several solutions required in optimization. To overcome this limit, element-by-element finite element matrix processing is employed, making coupled problems practicable on GPUs. We overcome the memory limits element-by-element processing, however, and achieve a GPU speedup of 147 by Jacobi conjugate gradients while forming the matrix of coefficients and of 80 (and growing indefinitely) by Gauss iterations without forming the matrix for situations where memory is scarce such as genetic algorithm optimization where several copies of the matrix have to be held on threads. Show more

Keywords: Review, optimization, finite elements, GPU, NDE, ground vehicles

DOI: 10.3233/JAE-140061

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 607-627, 2015

Authors: Zhou, Yunfei | Liu, Guangdou | Zhou, Rougang | Huo, Ligang | Ming, Wuyi

Article Type: Research Article

Abstract: In this paper the Halbach array with different segments per pole are modeled and compared. The unified harmonic model for the magnetic flux density distribution of the Halbach array with different segments per pole is derived by using Fourier series and magnetic scalar potential. The coil power dissipation and higher harmonics are compared with the Halbach arrays, respectively. The dimension parameter of magnet array is optimized on the basis of minimum coil power dissipation by taking …the magnetically levitated planar motor with moving magnets for example. The genetic algorithm is used to minimize the higher harmonics in z-component of the magnetic flux density distribution. Then the dimension parameters of magnet arrays are obtained, according to that the arrays are compared on the ratio between the higher harmonics and analytical model of z-component of the magnetic flux density distribution and the peak value of z- and x-component of the magnetic flux density distribution. The Halbach array with 3 segments per pole is chosen on the basis of the above comparison. Show more

Keywords: Halbach array, harmonic model, genetic algorithm, power dissipation, planar motor

DOI: 10.3233/JAE-130113

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 629-641, 2015

Authors: Reddy, C.S. | Sharma, A. | Mittal, K.C.

Article Type: Research Article

Abstract: The recovery in a spark gap for repetitive switching has been a long research interest. The surface temperature variation of the anode during switching plays decisive role in recovery of spark gap. This paper presents a method to estimate the effect of anode temperature rise and decay on repetition rate of spark gap. By using this method, the behavior of copper and stainless steel materials were studied for a current pulse of 30 kA. During the pulse …period of 10 μs, the temperature rise for SS is higher than Copper. After current zero, the anode temperature decays to the vaporization temperature of the material and determines the recovery time of the spark gap. This temperature decay is also verified by a heat transient computational model developed in FEM based software. Simulations has been carried out for different materials including Cu and SS. Some simulations are in good agreement with existing experimental data. The decay time for current pulses 5 kA, 10 kA, 15 kA, 20 kA, 25 kA and 30 kA are estimated. The simulation shows higher decay rate for tungsten and lower decay rate for graphite. Similar trend has been observed for silver and copper. Theoretical analysis of recovery times, heat transfer simulation model for different anode materials are presented and the results are discussed. Show more

Keywords: Anode temperature recovery, anode materials, spark gap recovery, specific heat flux, vaporization

DOI: 10.3233/JAE-140049

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 643-651, 2015

Authors: Tsai, Yi-Hsien | Hsue, Ching-Wen | Chen, I-Fong

Article Type: Research Article

Abstract: In this paper, a discrete-time domain synthesizing method was presented to design and implement the active integrator in the microwave frequency range. The frequency-domain GaAs Filed Effect Transistor (FET) scattering parameters are converted into the Z-domain representations. The transfer functions of the networks are formulated in the Z domain and implemented by using cascade serial line and GaAS FET. There are good agreement between the experimental results and the theoretical values.

Keywords: Active integrator, microwave, Z transforms

DOI: 10.3233/JAE-140042

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 653-660, 2015

Authors: Dash, S.K. | Swarup, K.S. | Rajan, K.K.

Article Type: Research Article

Abstract: Magnetic Bearing, especially Active Magnetic Bearing (AMB) is arguably most preferred bearing for the process dealing with highly reactive environment, high speed operation and where the process required least contamination. They are also being tried for Fly wheels and Wind generators. They continue to be evolved since last several decades. Quite a few processes like application of AMB in high temperature Liquid Sodium high temperature applications call for development of large-working-gap active magnetic bearings …(AMB). Smooth operation of AMB depends on hypersensitive position stiffness and Current stiffness, which fluctuates due to differential-thermal-expansion induced air gap variation. So, large gap, necessitates flatter open loop position stiffness than that of contemporary magnetic actuators. In this work, a goal seeking optimization methodology is employed for double acting AMB system where a combination of higher (CRGO electrical steel) and lower saturating magnetic material (Mu metal) is used. A less variant position stiffness across the air gap was arrived at after getting optimized design variables constituting geometry and excitation current parameters. This investigation opens up a new way to attain position stiffness in AMB system which is less sensitive to positional variation of rotor in air gap. This paper proposes an innovative and first-of-its-kind bi-material core material with goal driven optimized magnetic actuator design which can afford to have air gap variation during operation. Show more

Keywords: Thrust magnetic bearing, position stiffness, goal driven optimization, evolution strategy, bi-materialactuator

DOI: 10.3233/JAE-140041

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 661-680, 2015

Authors: Yang, Wan'an | Zhao, Xin | Hu, Chao | Qin, Fengqing

Article Type: Research Article

Abstract: In order to actively maneuver the robotic capsule and make it small to swallow easily, we propose that the capsule incorporating the circuits, batteries, imaging device, etc. is looped by a magnet ring with 1 mm thickness. Another cuboidal or cylindrical permanent magnet attracts or pushes or rotates the robotic capsule to make closer scrutiny for the interesting area. Before designing the control system, the force regarding distance between cuboidal or cylindrical magnet and magnet ring …should be known in advance. The mathematic model of magnetic force that the cuboidal or cylindrical permanent magnet exerts on the magnet ring is given for that purpose. The experiments state that the force the robotic capsule requires can be produced by cuboidal or cylindrical magnet when it's moving forward in the pig's small bowel. The experiments also show the relationships between the force and the shape of cuboidal magnet or cylindrical magnet, which can help to choose the magnets with optimal dimensions. Show more

Keywords: Maneuver, robotic capsule, permanent-magnet ring, force model, optimal dimension

DOI: 10.3233/JAE-140034

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 677-689, 2015

Authors: Peng, Cong | Fang, Jiancheng | Wang, Chun'e

Article Type: Research Article

Abstract: This paper focuses on the steering law for a magnetically suspended momentum wheel (MSMW) cluster with vernier gimballing capability. Firstly, the dynamical model of the spacecraft equipped with the MSMW cluster is constructed in a generalized form. Then a new steering law for the MSMW cluster is proposed to switch between two operation modes: the conventional momentum wheel mode for outputting spin torque, and the double gimbaled wheel mode for outputting the gyroscopic torques. Compared with …the traditional steering law, the proposed steering law with two modes switch can avoid the small vernier gimbal angles saturation. Finally, simulation results demonstrate the merits of using vernier gimballing capability and the effectiveness of the proposed steering law in providing the command torques and avoiding the saturation of the vernier gimbal angles. Show more

Keywords: Magnetic bearing, magnetically suspended momentum wheel, MSMW application, vernier gimballing, steering law

DOI: 10.3233/JAE-140024

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 691-704, 2015

Authors: Liu, Shuang | Li, Xue | Zhao, Shuangshuang | Li, Haibin

Article Type: Research Article

Abstract: Considering the torsional vibration in transmission system driven by AC asynchronous motor, this paper proposes a dynamical model of nonlinear electromechanical coupling system by using the energy method. The effect of electromagnetic factors on nonlinear dynamic performance of the electromechanical coupling system is investigated. Firstly, the static bifurcation characteristic under the non-autonomous condition is studied based on the singularity theory of nonlinear system. Secondly, the Hopf bifurcation point and the direction of …bifurcation are determined based on the Hopf bifurcation theory. Finally, the bifurcation diagram, Poincare map and the largest Lyapunov exponent are given, which show the influence of electromagnetic stiffness and electromagnetic damping on the chaotic motions of the system. Show more

Keywords: Electromechanical coupling, the energy method, bifurcation, chaos

DOI: 10.3233/JAE-140059

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 705-717, 2015

Authors: Bu, Yinggang | Nishiyama, Masahiro | Yamamoto, Tatsuya | Mizuno, Tsutomu | Tsuchiya, Shigeaki

Article Type: Research Article

Abstract: The use of magneto-plated wire (MPW) allows for reduction of winding loss component from the proximity effect. compared with a copper wire (COW). A MPW is a COW with a circumference that is plated with a magnetic thin film. In this paper, we clarify the basic characteristics and the efficiency characteristics of a transformer using a MPW and a COW. We found that the resistances of a primary coil made of COW and MPW at a frequency f=500 kHz …are 1.56 Ω and 1.12 Ω, respectively, and decreased 28%. The short circuit inductances of the COW and the MPW at a frequency f=500 kHz are 26 μH and 29.6 μH, respectively, and increased 13.8%. The efficiencies of an LLC resonant converter using the COW and the MPW at a frequency f=500 kHz are 90.2% and 92.2%, respectively, and increased 2%. Show more

Keywords: Magnetoplated wire, copper wire, AC resistance, LLC resonance, transformer

DOI: 10.3233/JAE-140070

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 719-727, 2015

Authors: Dincer, Furkan | Karaaslan, Muharrem | Unal, Emin | Sabah, Cumali

Article Type: Research Article

Abstract: Tunable and multi-band metamaterial (MTM) based perfect microwave absorber (MA) is designed, implemented, and characterized. Firstly, dual-band MA with has two distinct resonances is investigated both numerically and experimentally which is also tested according the incident angle and polarization independencies. Then, the modified versions of MA are investigated and compared with respect to their absorbance, mechanical tunability, and multi-band characters. As a result, the suggested MAs with perfect absorption (including incident angle …and polarization independencies) display good performance among their counterparts and can be used in myriad potential applications such as high frequency and sensor applications which are also presented. Show more

Keywords: Absorber, dual-band, metamaterial, tunable, sensor

DOI: 10.3233/JAE-140073

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 729-735, 2015

Authors: Cong, Haoxi | Li, Qingmin | Chen, Quan | Xing, Jinyuan

Article Type: Research Article

Abstract: Secondary arc is a complicated and critical physical phenomenon with power transmission lines. An arc chain model was employed with a view to establish the governing velocity equations, in which the multiple forces impacts upon each element were specifically incorporated including electromagnetic force, wind load, air resistance and thermal buoyancy. Based on the proposed model for secondary arc dynamics, simulations were then carried out and further validated through physical experiments on a test platform, …which showed good coincidence between the two. The research can provide fundamentals for understanding the physical nature especially the extinction mechanism of secondary arcs, and lays theoretical basis for optimal design of the transmission lines' auto-reclosing strategy. Show more

Keywords: Secondary arc, arc column form, motion characteristics, mathematical modeling

DOI: 10.3233/JAE-140079

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 737-746, 2015

Authors: Zhang, Zhi-Ya | Zuo, Shao-Li | Zhao, Jia-Yue | Wang, Shao-Chuan | Fu, Guang

Article Type: Research Article

Abstract: The paper proposes a wideband bowtie antenna for indoor base station applications. By using the inverted L-shaped coupling feed structure, the impedance bandwidth of the lower band is improved; while using the four tuning stubs, the upper band is enhanced. Thus, a wide impedance bandwidth of about 77.8% (VSWR les; 2) ranging from 1.38 to 3.14 GHz is obtained. In addition, by connecting two folded elements to the patches of the bowtie dipole, the compact dimensions …of the antenna can be achieved. It also provides stable peak gain, unidirectional radiation patterns and low cross-polarization over the whole operating band. Owing to these good performances, the proposed antenna is very suitable for the recent indoor base station wireless communication services such as 3G, WiFi, WiMax, Bluetooth and LTE applications, etc. Show more

Keywords: Wideband bowtie antenna, inverted L-shaped coupling feed, tuning stubs, impedance bandwidth

DOI: 10.3233/JAE-140086

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 745-752, 2015

Authors: Zhou, Guohua | Liu, Shengdao | Xiao, Changhan | Liu, Daming

Article Type: Research Article

Abstract: Integral equation method is widely used in magnetic field modeling of ships, but its nonsymmetric and dense coefficient matrix results in low computation efficiency and large memory, which limits its application in large scale problems. An approach for a fast computation of induced magnetic field created by ships was presented based on multiple layers fast multipole method and vector integral equation method. The numerical implementation of the proposed approach was described in detail. It is shown …by an analytical sphere example and a simplified mock-up experiment that the proposed approach can reduce computation time and memory cost in induced magnetic field modeling of ferromagnetic objects. Show more

Keywords: Vector integral equation method, fast multipole method, induced magnetic field, magnetic silencing

DOI: 10.3233/JAE-140113

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 753-765, 2015

Authors: Wang, Jian | Xia, Yin-Shui | Wang, Lun-Yao

Article Type: Research Article

Abstract: Electromagnetic responses of a metallic conical frustum cabin with one coaxial feeding monopole antenna, illuminated by an intentional electromagnetic pulse (IEMP), are studied in this paper. There are several slots on the cabin wall with different sizes and orientations. The mathematical treatment is based on novel hybrid finite difference time domain (FDTD) method, where coaxial feeding, transfer impedance coupling and thin wire antenna models are integrated together for handling such a complex three-dimensional (3D) …composite structure. The revised antenna port coupling model is verified by comparing the calculated terminal voltage responses of the coaxial feeding cable with that of commercial CST Microwave Studio. Parametric studies are further carried out to show the variations of its terminal voltages for different IEMP waveforms, incident directions and polarizations. Show more

Keywords: Intentional electromagnetic pulse (IEMP), hybrid FDTD method, coaxial feeding cable, transfer impedance

DOI: 10.3233/JAE-140112

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 765-776, 2015

Authors: Xu, Zheng | Meng, Kaikai | Cheng, Jiangyan

Article Type: Research Article

Abstract: This study presents a high-performance single-sided portable nuclear magnetic resonance (NMR) sensor. The magnet array, which is composed of five identical cuboid permanent magnet blocks and two passive shimming sheets, generates a highly uniform B_{0} field in a 10 × 10 mm^{2} lateral area. Along the two orthogonal lines in this lateral area, the measured B_{0} strength variation is less than 338 ppm. Vertically, the …measured B_{0} magnitude decreases from 144.387 mT to 130.603 mT, with a constant gradient of 4.6 T/m from 0.15 mm to 3.15 mm above the magnet surface. A planar radiofrequency coil is optimized according to the signal-to-noise ratio level of the coil. A one-dimensional profiling experiment on an oil film shows that a vertical resolution of approximately 1.7 μm can be achieved. As an application, the silicone rubber insulators are measured using the NMR sensor. Results demonstrate that the silicone rubber insulators with different service times can be distinguished through the transverse relaxation time T_{2} of the silicone rubber insulators. Show more

Keywords: Single-sided NMR, high uniformity, constant gradient, aging level, silicone rubber insulator

DOI: 10.3233/JAE-140123

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 777-790, 2015

Authors: Yang, Fan | Dai, Feng | Liu, Xinghua | Yang, Yongming | He, Wei

Article Type: Research Article

Abstract: When HVDC transmission lines operate in the monopole ground return mode or asymmetric bipolar mode, DC current flows in the earth and DC magnetic bias will arise in neutral point grounding (NPG) transformers. In this work, the model to calculate the potential distribution for multi-layer soil structure is set up, then the magnetic bias current (MBC) is calculated. The magnetic field distribution in the NPG transformer is obtained according to MBC, and electromagnetic energy and force in the …transformer are calculated. Finally, the influence on MBC, electromagnetic energy and force caused by soil parameters are investigated. Results indicate that thickness of the first layer and resistivity of the second layer have a greater contribution to MBC, electromagnetic energy and force. To avoid excessive vibration of the NPG transformer, the soil at grounding electrode with a greater thickness in the first layer and lower resistivity in the second layer is preferred. Show more

Keywords: DC current, electromagnetic energy, force, magnetic bias current (MBC), transformer

DOI: 10.3233/JAE-140122

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 791-804, 2015

Authors: Ghaffar, A. | Alkanhal, Majeed A.S.

Article Type: Research Article

Abstract: In this paper, analysis and theoretical formulations are developed for the reflected and the transmitted waves from a planar interface of isotropic chiral-uniaxally anisotropic chiral media with optical axis normal to interface. General expressions for the reflection and transmission coefficients for right circularly polarized (RCP) and left circularly polarized (LCP) incident waves are derived. The results of the reflected and transmitted powers for materials with different isotropic chirality and uniaxial chirality values …for both RCP and LCP incident waves are presented. The effects of the uniaxial chirality on three other cases of dielectric constant combinations are also studied. The numerical results computed by the developed transfer matrix technique expressions are found to coincide with published results obtained by computational techniques for special material cases. Show more

DOI: 10.3233/JAE-130161

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 805-817, 2015

Authors: Fan, Fang-Fang | Yan, Ze-Hong | Wang, Jin-Hiu

Article Type: Research Article

Abstract: A wideband microstrip planar radial 1:19 power divider is developed in this study. The power divider design is simple with conventional impedance-transformation method, and a single substrate is employed, thereby reducing the cost for the antenna. To verify our design, the power divider was fabricated and tested. It can be observed that it achieves an impedance bandwidth of 29.4{\% (1.98 GHz–2.67 GHz) (VSWR ⩽ 2), the transmitted magnitude and phase imbalance for 19 outputs are ± 0.1 dB and ± 1 deg, respectively. The power divider is also integrated into the 19-element circularly polarized (CP) antenna array as the feed …network; the simulated results show that the power divider can apply appropriate amplitudes and phases for the antenna array to obtain the good CP performance. Show more

Keywords: Planar power divider, radial power divider, array antenna

DOI: 10.3233/JAE-140075

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 819-825, 2015

Authors: Naeem, Nadeem | Ismail, Alyani | Alhawari, Adam Reda Hassan | Mahdi, Mohd Adzir

Article Type: Research Article

Abstract: This study reports new shape of meta-material array structures having electric and magnetic resonances designed for terahertz (THz) frequency band. The proposed structures exhibit left handed meta-material propertiesin THz frequency band. The introduced meta-material split ring resonators in this paper are constructed using a single loop of conducting wire strip printed over a very thin low permittivity polyimide dielectric substrate. The effective parameters like permeability and negative index are extracted from the …simulated complex scattering parameters using direct retrieval method. Unloaded Q-factor is calculated for proposed terahertz metamaterial resonators. The proposed arrays are tested by loading different dielectric samples in order to confirm the testing capability. Significant shift in the transmission is observed. The reported array structures are novel in terms of their left handed behavior in THz frequencies. High values of Q-factor reported here, are suitable for near field sensing applications. Show more

Keywords: Metamaterial array, permeability, negative index, terahertz, near field, dielectric sensing

DOI: 10.3233/JAE-140107

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 827-836, 2015

Authors: Wang, Jingang | Yang, Jie | Luo, Ruixi

Article Type: Research Article

Abstract: Online transformer monitoring and protective relaying require voltage sensors with fast response and high precision. Traditional devices, such as resistive and capacitive dividers, have disadvantages in measuring transient voltage, e.g., oscillation, narrow bandwidth, and large size. This paper introduces a new D-dot probe for transient measurement. The difference input circuit structure is presented on the basis of the operating principle of the D-dot probe. Paralleled multiple electrodes are applied to gain the mutual …capacitance value of the probe to achieve a large divide ratio and make the probe work in a self-integrating mode. Pspice simulation is conducted to find a way to minimize probe error. The probe is manufactured into printed circuit boards (PCB). The steady state linearity and transient response of the probe are tested. Results show that the probe has fast response and broad bandwidth. Show more

Keywords: Transient voltage measurement, D-dot probe, self-integrating, printed circuit boards electrodes

DOI: 10.3233/JAE-140111

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 837-845, 2015

Authors: Ye, Zhitong | Duan, Zhiyong | Su, Liushuai | Takahata, Kenichi | Su, Yufeng

Article Type: Research Article

Abstract: This paper presents theoretical analysis and verification of a micro vibration energy harvester based on magnetic levitation using diamagnetic structures. The analysis verifies that diamagnetic material experiences anti-magnetic force in magnetic field and that it can be used for stable magnetic levitation. This study proposes a novel design that is comprised of a lifting permanent magnet, an upper pyrolytic graphite sheet, a floating permanent magnet, and a lower pyrolytic graphite sheet, with copper spiral …coils formed on the two pyrolytic graphite sheets. The gravity of the floating permanent magnet is balanced by the attractive force between the lifting and floating magnets. The diamagnetic force exerted on the levitated magnet by the two pyrolytic graphite sheets serves as a restoring force, forcing the floating permanent magnet return to the equilibrium position. Through finite element analysis, the maximum movable range of the floating magnet is defined to be 1.3 mm. Comparative analysis of the attractive magnetic force and the anti-magnetic force is performed to determine the key parameters of the structure. The characteristics of vertical and horizontal motion of the magnet are also studied in detail. The results validate the effectiveness of the proposed design for harvesting multi-dimensional, low-frequency vibration energy. The diamagnetic levitation mechanism without conventional mechanical suspensions eliminates loss of vibration energy and resultant thermal issues. The system is potentially promising, through further miniaturization, in providing sustainable power for micro-electro-mechanical systems. Show more

Keywords: Micro-vibration energy harvester, diamagnetic, levitation, multi-dimension, micro-electro-mechanical system (MEMS)

DOI: 10.3233/JAE-140120

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 847-860, 2015

Authors: Hu, Chao | Sun, Yue | Lv, Xiao | Wang, Zhihui | Xiong, Qingyu

Article Type: Research Article

Abstract: Magnetic coupler is the most critical part to achieve high power transmitting capability in an inductive power transfer (IPT) system. This paper introduces a design procedure of magnetic coupler. Based on the design procedure, the main parameters that affect the output power and power loss of the magnetic coupler have been found. In order to stable the operating frequency, equations which calculate the receiver self-inductance and the magnetic coupler mutual inductance are developed and analyzed. Moreover, …the parameters of Double-Layer-Double-D (DLDD) coil which is designed for electric vehicles' (EVs') wireless charging are derived according to the magnetic coupler design procedure. The experimental results show that the power transfer efficiency (PTE) of an IPT system with DLDD coil can be as high as 85.1% with a transmitting distance of 15 cm, while the output power is 10 kW. Show more

Keywords: Inductive power transfer (IPT), electric vehicle (EV), magnetic coupler, design procedure

DOI: 10.3233/JAE-140146

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 861-873, 2015