Advanced Electromagnetics (E-Journal)
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Proposal of C-core Type Transverse Flux Motor for Ship Propulsion – Increasing Torque Density by Dense Stator Configuration –
No full textElectric ship propulsion system has been drawing attention as a solution for savings in energy and maintenance costs. The system is mainly composed of motor, converter and gearbox and required for high torque at low speed. In this situation, transverse flux motors (TFMs) have been proposed to fulfill the low-speed high-torque characteristic due to suitable for short pole pitch and large number of poles to increase torque output. In this trend, we have proposed C-core type motors taking advantage of TFMs’ structure. In this manuscript, a simple design method based on the magnetic-circuit theory and simple modeling of the motor is proposed to search a design parameter for maximizing torque as a pre-process of numerical study. The method takes into consideration the effects of magnetic leakage flux, magnetic saturation and pole-core combination in accordance with the systematic theory. The simple modeling is conducted based on a dense armature structure in previous axial flux motors (AFMs) applied to the new motor design. The validity of the method is verified by 3-D finite element analysis (FEA) and relative error is at most 20%. The minimalist design is shown to be advantageous for effective use in 3-D FEA. As a detailed design by the FEA, high torque density and low cogging to output ratio can be achieved simultaneously in the proposed machine
Far-field flat lens based on multilayered metal- dielectric structure
No full textThe detailed investigation has been made of the lens effect in plane multilayered metal-dielectric structures (Ag-TiO2). The optical scheme of the lens has been studied with the radiation focusing in free space. The transfer function is calculated, where the phase profile determines definitely the possibility of focusing. The condition for far-field image formation is found using a flat lens. This condition is used for a numerical simulation of several lens designs with a various number of metal layers. It is found that considered flat lenses have close to limiting angular aperture and therefore the subwavelength resolution. It is established that at increase of a number of metal layers the object and image distances grow
Computational Finite Element Software Assisted Development of a 3D Inductively Coupled Power Transfer System
No full textTo date inductively coupled power transfer (ICPT) systems have already found many practical applications including battery charging pads. In fact, current charging platforms tend to largely support only one- or two-dimensional planar movement in load. This paper proposes a new concept of extending the aspect ratios of the operating power transfer volume of ICPT systems to support arbitrary three dimensional load movements with respect to the primary coils. This is done by use of modern finite element method analysis software to propose the primary and secondary magnetic structures of such an ICPT system. Firstly, two primary magnetic structures are proposed based on contrasting modes of operation and different field directions. This includes a single-phase and multi-phase current model. Next, a secondary magnetic structure is customized to be compatible with both primary structures. The resulting system is shown to produce a 3D power transfer volume for battery cell charging applications
Fabrication and characterization of micro-inductors deposited on magnetic thin and thick layers
No full textThis paper presents two fabrication techniques of spiral integrated inductors based on magnetic materials. For the first one, the magnetic core is a thin film deposited by RF magnetron sputtering, for the second technique the magnetic core is a thick layer of YIG obtained by micromachining. The addition of the magnetic material is expected to improve the performances of the integrated structure with electromagnetic shield. Low and high frequency equipment are used to characterize the manufactured components. A good correlation is obtained between the results by simulation and measurements for the two manufacturing techniques. These results show that the inductance increases when the thickness of the magnetic layer increases, we can double the inductance value for a thickness sufficiently high
Propagation Characteristics of Multilayer Hybrid Insulator-Metal-Insulator and Metal-Insulator-Metal Plasmonic Waveguides
No full textPropagation characteristics of symmetrical and asymmetrical multilayer hybrid insulator-metal-insulator (HIMI) and metal-insulator-metal (HMIM) plasmonic slab waveguides are investigated using the transfer matrix method. Propagation length (Lp) and spatial length (Ls) are used as two figures of merit to qualitate the plasmonic waveguides. Symmetrical structures are shown to be more performant (having higher Lp and lower Ls), nevertheless it is shown that usage of asymmetrical geometry could compensate for the performance degradation in practically realized HIMI waveguides with different substrate materials. It is found that HMIM slab waveguide could support almost long-range subdiffraction plasmonic modes at dimensions lower than the spatial length of the HIMI slab waveguide
Improved Formulae for the Inductance of Straight Wires
No full textThe best analytical formulae for the self-inductance of rectangular coils of circular cross section available in the literature were derived from formulae for the partial inductance of straight wires, which, in turn, are based on the well-known formula for the mutual inductance of parallel current filaments, and on the exact value of the geometric mean distance (GMD) for integrating the mutual inductance formula over the cross section of the wire. But in this way, only one term of the mutual inductance formula is integrated, whereas it contains also other terms. In the formulae found in the literature, these other terms are either completely neglected, or their integral is only coarsely approximated. We prove that these other terms can be accurately integrated by using the arithmetic mean distance (AMD) and the arithmetic mean square distance (AMSD) of the wire cross section. We present general formulae for the partial and mutual inductance of straight wires of any cross section and for any frequency based on the use of the GMD, AMD, and AMSD. Since partial inductance of single wires cannot be measured, the errors of the analytical approximations are computed with the help of exact computations of the six-dimensional integral defining induction. These are obtained by means of a coordinate transformation that reduces the six-dimensional integral to a three-dimensional one, which is then solved numerically. We give examples of an application of our analytical formulae to the calculation of the inductance of short-circuited two-wire lines. The new formulae show a substantial improvement in accuracy for short wires
Calculation of harmonic losses and ampacity in low-voltage power cables when used for feeding large LED lighting loads
No full textA numerical investigation on the harmonic disturbances in low-voltage cables feeding large LED loads is reported. A frequency domain analysis on several commercially-available LEDs was performed to investigate the signature of the harmonic current injected into the power system. Four-core cables and four single-core cable arrangements (three phases and neutral) of small, medium, and large conductor cross sections, with the neutral conductor cross section approximately equal to the half of the phase conductors, were examined. The cables were modelled by using electromagnetic finite-element analysis software. High harmonic power losses (up to 2.5 times the value corresponding to an undistorted current of the same rms value of the first harmonic of the LED current) were found. A generalized ampacity model was employed for re-rating the cables. It was found that the cross section of the neutral conductor plays an important role in the derating of the cable ampacity due to the presence of a high-level of triplen harmonics in the distorted current. The ampacity of the cables should be derated by about 40 %, almost independent of the conductor cross sections. The calculation have shown that an incoming widespread use of LED lamps in lighting could create significant additional harmonic losses in the supplying low-voltage lines, and thus more severely harmonic emission limits should be defined for LED lamps
Reconsidering Ampere’s Double Layer Representation for Magnetic Field, Evaluation in a NDE Dection of a zero volume crack
No full textThe paper has two different objectives. The first one is to show that Ampere’s double layer method, which is equivalent to one of the Maxwell equations, leads to the integration of a simple closed form expression, thus avoiding the need to solve complicated partial differential equations. The second aim is to study the case of a zero volume defect in a NDE problem by a perturbation method and the introduction of a double layer. The combination of these two techniques leads to a very fast solution of the problem. A practical example includin
UWB Miniature Antenna Based on the CRLH-TL with Increase Gain for Electromagnetic Requirements
No full textIn this paper, a novel ultra-wideband (UWB) miniature antenna based on the composite right-left handed transmission line (CRLH-TL) structure with enhancement gain is proposed and investigated. With CRLH metamaterial (MTM) technology embedded, the proposed UWB and miniature antenna is presented with best in bandwidth, size, efficiency and radiation patterns. To realize characteristics of the antenna, the printed -shaped gaps into the rectangular radiation patches are used. This antenna is constructed of the two unit cells, also presented antenna is designed from 2.25 GHz to 4.7 GHz which corresponding to 70.5% bandwidth. The overall size of the presented antenna is 10.8mm×6.9mm×0.8mm or 0.09λ0× 0.05λ0 × 0.006λ0 at the operating frequency f = 2.5 GHz (where λ0 is free space wavelength). The radiation peak gain and the maximum efficiency which occurs at 4.6 GHz, are 3.96dBi and 63.6%, respectively
Wave Concept Iterative Procedure Analysis of Patch Antennas on Nanostructured Ceramic Substrates
No full textThe wave concept iterative procedure (WCIP) is proposed to analyze rectangular and circular patch antennas on nanostructured ceramic substrates. Principles of WCIP are described and advantages are emphasized. The analysis of microstrip antennas on double layered substrates is performed in space and spectral domains. In addition, Fast Fourier Transformation (FFT) is used to improve the efficiency of the method. WCIP simulated results are compared to HFSS software ones. A good agreement is observed