Wyniki wyszukiwania - Biblioteka Nauki

1

Method of Selection of dv/dt for EMI Current Ringing Attenuation

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Kempski A. , Smolenski R.

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tom Vol. 14, iss. 2

19--24

EN

In this paper the method of the selection of dv/dt for EMI current ringing attenuation has been presented. The mechanism for the attenuation is first identified using the theoretical approach. It is shown that the attenuation occurs for rise time of the voltage equal to the inverse of the frequency of current ringing. The concept has been experimentally verified in DC chopper and frequency converter arrangements. The proposed method of ringing attenuation can be applied in power converters with flexible gate control and can be also utilized in a wide area of electronic circuits with a trapezoidal excitation for a signal integrity improvement.

2

Design and Optimization of Rectangular Waveguide Filter based on Direct Coupled Resonators

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Damou M. , Nouri K. , Feham M. , Chetioui M.

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tom Vol. 63, No. 4

375--380

EN

The waveguide filter structure is treated by two softwares (HFSS (High Frequency Structure Simulator) and CST (Computer Simulation Technology)). Numerical example is given in this article to demonstrate, step by step, the application of the approach to the design of resonator, direct coupled waveguide and microstrip filters based on electromagnetic (EM) simulations. For this design procedure, the filter structure is simulated by successively adding one resonator at a time. To continue the work illustrates how to design a fourth order coupled resonator based rectangular waveguide circuit in the traditional way. With a large number of variables, such tuning work consumes a lot of time and the convergence of the final result is not guaranteed. A fourth order X-band bandpass filter with a center frequency of 11 GHz and a fractional bandwidth FBW = 0,0273 is designed using this procedure and presented here as an example. The simulated results by CST are presented and compared withthe results simulated by a high-frequency structure simulator. Good agreement between the simulated HFSSand simulated results by CST is observed.

3

Wiener Filtering Applied to Conducted EMI Estimation in Soft Switching Inverter

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Musznicki P. , Chrzan P. J. , Mandrek S.

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tom Vol. 14, iss. 2

25--28

EN

This paper presents an estimation method of the conducted electromagnetic interference EMI emissions in soft switching inverters. Estimation process is carried out by a number of Wiener filters, which represent different operation conditions as reflected through subsequent power converter states determined by initial commutation event conditions and propagation paths layout. Filters are fed by a semiconductor power switch voltage or current waveforms regarded as sources of perturbation. The EMI emissions are measured on the line impedance stabilization network LISN terminals. Optimal filter adaptation is effected in the frequency domain by measuring input and cross power signal spectra. Analysis of parallel quasi resonant dc link voltage inverter PQRDCLI is outlined to distinguish filters assigned for inverter operation and those for an external DC/DC converter interaction. Experimental results are given to illustrate the Wiener filtering estimation quality. Possibility of detailed decomposition of the LISN-EMI waveforms is depicted in both time and frequency domain. Comparative analysis of frequency responses for PQRDCLI link voltage changes is given.

4

The Analytical and Artificial Intelligence Methods to Investigate the Effects of Aperture Dimension Ratio on Electrical Shielding Effectiveness

100%

Basyigit I. B. , Dogan H.

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tom Vol. 65, No. 3

359--365

EN

This paper presents that the effect of single aperture size of metallic enclosure on electrical shielding effectiveness (ESE) at 0 – 1 GHz frequency range has been investigated by using both Robinson’s analytical formulation and artificial neural networks (ANN) methods that are multilayer perceptron (MLP) networks and a radial basis function neural network (RBFNN). All results including measurement have been compared each other in terms of aperture geometry of metallic enclosure. The geometry of single aperture varies from square to rectangular shape while the open area of aperture is fixed. It has been observed that network structure of MLP 3-40-1 in modeling with ANN modeled with fewer neurons in the sense of overlapping of faults and data and modeled accordingly. In contrast, the RBFNN 3-150-1 is the other detection that the network structure is modeled with more neurons and more. It can be seen from the same network-structured MLP and RBFNN that the MLP modeled better. In this paper, the impact of dimension of rectangular aperture on shielding performance by using RBFNN and MLP network model with ANN has been studied, as a novelty.

5

An adaptive neuro-fuzzy based methodology for harmonic analysis of a power transformer

67%

Urooj S. , Amir M. , Khan A. , Tariq M.

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2021

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tom Vol. 101, nr 1

1--10

EN

The interfering nature of harmonics always causes various power quality issues that impacts on both efficiency, and expected transformer life. Optimal analysis of the three-phase core power transformers using harmonic spectrum can limit these power quality issues. This paper designs the Adaptive Neuro-Fuzzy Inference System (ANFIS) based model for the estimation of losses. Further optimal parameters selection of three-phase power transformer using iron and ferrite core materials. This paper demonstrates factors that deteriorate the power quality, responsible for harmonics distortions and inefficiency in power transformers. The proposed ANFIS based analysis provides an optimal solution to harmonic reduction and improves overall efficiency. Also, providing a comparative study of various core parameters that will be suitable for a three-phase core transformer. The proposed parameters are demonstrated for improving the overall transformer efficiency using iron and ferrite core material. ANSYS Maxwell simulation estimates the Total Harmonic Distortion (THD) and enhances THD in contributing to the optimal core material. The design of a three-phase power transformer and the performance evaluation of the proposed methodology performed in MATLAB simulation environment.

6

Modeling and numerical simulation of eddy current sensors for electromagnetic characterization of fluids

67%

Miloudi K. , Moulai H. , Azizi H.

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tom R. 99, nr 10

88--92

EN

This work aims to model a device enabling a useful and accurate electromagnetic characterization of fluids. The device developed is based on a non destructive testing (NDT) control technique evolving the eddy currents induced in the fluid to be characterized. The finite element method was used in the modeling to determine the conductivity of the fluid from the induced eddy current. In addition, an experimental device has been built. It consists of an absolute probe where the fluid control is made by determining its electrical conductivity by measuring the variations of the fluid impedance as a function of the applied voltage frequency. Good agreements are found between modeling results and experimental measurements. An inverse model that converges after only 7 iterations has been also proposed for the determination of the conductivity of fluids by the use of theoretical and experimental measurements.

PL

Niniejsza praca ma na celu zamodelowanie urządzenia umożliwiającego użyteczną i dokładną charakterystykę elektromagnetyczną płynów. Opracowane urządzenie opiera się na technice kontroli badań nieniszczących (NDT), która rozwija prądy wirowe indukowane w scharakteryzowanym płynie. W modelowaniu wykorzystano metodę elementów skończonych do wyznaczenia przewodności płynu z indukowanych prądów wirowych. Ponadto zbudowano eksperymentalne urządzenie. Składa się z sondy absolutnej, w której kontrola płynu odbywa się poprzez określenie jego przewodności elektrycznej poprzez pomiar zmian impedancji płynu w funkcji przyłożonej częstotliwości napięcia. Stwierdzono dobrą zgodność między wynikami modelowania a pomiarami eksperymentalnymi. Zaproponowano również model odwrotny, który zbiega się już po 7 iteracjach, do wyznaczania przewodnictwa płynów za pomocą pomiarów teoretycznych i eksperymentalnych.