1,721,029 research outputs found
Optimization of magnetic multilayered shields
No full textIn this paper a procedure for the optimization of multilayered shields for low-frequency magnetic fields is presented. The shield is optimized with respect to the total volume of the composing materials, being the magnetic flux density magnitude at test points in the shielded region smaller than a given threshold value. For simplicity, shields composed of two different materials only are considered. The number and thickness of the shield layers belong to the set of the control variables. Only one layer thickness at a time is allowed to vary. The procedure is repeated for the different multilayered shield configurations, starting from the single-layer ones for each material, until the optimum shield volume is reached
A numerical model for the calculation of electromagnetic interference from power lines on nonparallel underground pipelines
Full text linkThis work proposes a numerical methodology for the calculation of currents and voltages induced on underground pipelines by nearby overhead power lines. A previously developed quasi-3D methodology is extended, allowing the investigation of nonparallel routings of the pipelines with respect to the power lines. The proposed technique is based on a discretization of the pipeline path into several segments parallel to the power line. The section of the corridor corresponding to each pipeline segment is regarded as an electrical multi-port component, whose electrical parameters are extracted via finite element 2D analysis. Then, the obtained components are integrated into a network embodying the physical characteristics of the whole corridor. In this way, the circuital analysis is used to extend the capabilities of a standard two-dimensional field analysis. The proposed methodology is employed to simulate a pipeline running parallel to a power line for a distance of 12km. Afterwards, several nonparallel configurations – consisting of crossings between a pipeline and a power line – are assessed. The physical consequences of the crossing are discussed and a convergence study is performed to investigate the optimal pipeline subdivision procedure to be adopted for a set of different crossing angles
Multifrequency optimization of multilayered shields
No full textA procedure for the optimization of planar multilayered shielding structures for magnetic fields, at frequencies for which the quasimagnetostatic description can be adopted, is presented in this paper. The optimum thickness of multilayered shields is found under the constraint of a minimum threshold value for the magnetic shielding effectiveness (SE) at a certain distance from a given source. The design of the shield with respect to the number and type of layers is carried out adopting the particle swarm optimization (PSO) method. Multilayered shields composed of selected materials are considered, and the optimal configuration in a source of a periodic triangular-wave current at the frequency of 10 kHz is investigated
Inductive coupling on metallic pipelines: Effects of a nonuniform soil resistivity along a pipeline-power line corridor
Full text linkMetallic buried pipelines sharing the same corridor with AC power lines are subjected to AC interference, potentially harmful to personnel and equipment. The inductive coupling depends, among other factors, on the physical characteristics of the soil. This work presents an analysis of the effects of soil resistivity nonuniformities spanning along the length of a corridor. The investigation is performed by assessing several realistic configurations suited to highlight the various mechanisms affecting the phenomenon. The calculations are carried out employing an ad-hoc developed numerical tool, where the network analysis is used to enforce physical constraints on a 2D finite element analysis. The obtained results show that longitudinal nonuniformities in the soil resistivity can significantly affect the induced currents, depending on the particular configuration of the power line under exam
Shielding effectiveness of multilayered shields for magnetic field nonsinusoidal sources
No full textThe magnetic field generated by a nonsinusoidal periodic source is shielded by a planar infinite multilayered shield composed of high permeability and high conductivity materials. By means of a transform analytical approach the shielding effectiveness is calculated
Erratum: Peculiar Role of Holes and Electrons in the Degradation of CdTe Thin Films (IEEE Transactions on Device and Materials Reliability Jun. 2015. vol. 15, no. 2, (pp. 198-205))
No full textInput Current of H-bridge Inverters with Asymmetric Switch Parameters for Wireless Power Transfer Applications
No full textIn modern DC distribution networks both consumer and prosumer devices are interfaced to the grid via power converters equipped with suitable filtering circuitry to mitigate conducted electromagnetic interference (EMI), also referred to as conducted emissions (CE). However, the presence of asymmetries in the converter, such as the deviation of the component parameters from the designed ones and possible device failure, can significantly alter the input current and voltage waveforms while the device still works satisfactorily. This inevitably leads to an increase in the harmonic pollution in the power grid, being the EMI filters designed for acting on different waveforms. This paper investigates the effect that non-idealities of power switches have on the input current of an H-bridge inverter
A solution to the problem of determining X-points in magnetic induction fields
No full textA procedure which exploits a sufficient condition for determining X-points in quasistatic magnetic induction fields characterized by translational or axisymmetrical geometry is presented. The validity of the procedure and usefulness of the theorem are illustrated via a numerical example
Simple Formula for the Calculation of Shielding Effectiveness of Finite Width Conductive Shields
No full textIn this paper, a fast and simple analytical formulation for the calculation of the shielding effectiveness of finite width conductive shields at extremely low frequency is proposed. The magnetic field generated by a current loop is analysed considering a conductive shield of various widths and for different distances of the source from the shield and from the field point. The effect of the system parameters on the shielding effectiveness is investigated. A formula for the shielding effectiveness of finite width conductive shields at extremely low frequency is derived from the values of the magnetic field in absence of the shield and in presence of a shield of infinite extension
Fast Calculation of Shielding Effectiveness in Wireless Power Transfer Systems
No full textThis paper proposes a fast analytical procedure to evaluate the shielding effectiveness (SE) of conductive shields in wireless power transfer (WPT) systems. The methodology exploits the current image method combined with a compact SE calculation formulation, which can also be extended to multilayered shields. A standard case study is considered, and the results are validated through finite-element method (FEM) simulations
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