Carlos Sartori

An analytical-FDTD method for near LEMP calculation

The paper presents a hybrid method for evaluating the electromagnetic field in the vicinity of the lightning channel base. Several models have been proposed for this purpose, but, in spite of general agreement on the magnetic field results, the literature shows quite different results concerning the intensity and waveshape of the near electric field. The proposed method is an alternative approach that takes advantage of this fact to calculate, first, the magnetic field, and, secondly, based partially on the FDTD method, the electric field. The suitability of this procedure is checked through the comparison with another method, for a particular configuration proposed in the literature.

Transient induced voltage computation in a high building struck by lightning

The effects resulting from direct lightning strikes to buildings may affect the reliable operation of electric and electronic systems installed inside. The influence of such phenomena on equipment and systems depends on the immunity levels, and on the magnetic field intensity due to the lightning current. In this paper, a time-domain simulation of the lightning induced voltage on electric circuits (open metal loops) located inside a high building, a steel structure, is presented. In order to make an extensive analysis, the simulation is carried out considering different regions within the building. The results related to magnetic flux density and induced effects, helpful in determining the critical positions of equipment, are presented, and some of them are compared with those obtained from other methodologies proposed in the literature.

EMC aspects in a steel structure struck by lightning

The EMC analysis of a complex steel structure struck by a direct lightning, based on a simulation model developed by the authors, is here presented. For this proposal, simulations of the resulted magnetic field, as a function of the time, in the places where the higher susceptibility equipment will be installed, considering different lightning struck points, are carried out and these results are compared with some established limits. Some conclusions are presented, pointing out the advantages of the considered EMI prediction model during the design of the electrical and electronic installations, when lightning effects should be considered.

Numerical Evaluation of Noncanonical Reverberation Chamber Configurations

This paper aims to present an evaluation of noncanonical mode stirred chambers, whose excitation is carried out by transmission lines. Many configurations are taken into account regarding the influence of the wire arrangement and their phase shift excitation on the field homogeneity. The simulations were carried out within the framework of finite integration technique (FIT) and transmission-line modeling (TLM) methods. Experimental and theoretical results are presented regarding the chamber suitability to electromagnetic compatibility (EMC) tests. It is emphasized the viability of extending the present standard frequency range recommendation to lower frequency values.

Maximum Working Volume Evaluation in a Non-Canonical Reverberation Chamber

This paper presents a procedure for evaluating the performance of reverberation chambers, by approximating the maximum working volume in a given configuration. The evaluation of this volume is based on the geometrical and physical constraints, e.g., the ones related to the internal E-field distribution recommended by standards. The importance of the present work is related to the development of a non-canonical reverberation chamber configuration, whose excitation is carried out by transmission lines, instead of antennas plus paddles.

Using Equivalent Emission Sources to Evaluate the Coupling Between Components

The electromagnetic interference between the electronic systems or their components influences the performance of the systems. For that reason, it is important to model these interferences in order to optimize the position of the systems or their components. In this paper, a method is proposed to construct the equivalent emission source models of systems. The proposed method is based on the multipolar expansion by representing the radiated emission of generic structures in a spherical reference (r,θ,φ). Some results are presented illustrating our method.

Fault Classification and Detection by Wavelet-Based Magnetic Signature Recognition

A noninvasive methodology to evaluate and classify electrical system failures is presented in this work. It is based on the electrical system magnetic signature recognition by using the wavelet signal decomposition and the resulting variance spectrum evaluation, respectively. The proposed methodology was validated by comparing theoretical and experimental results. The finite-element method was used in the numerical simulations of the magnetic flux density, and a postprocessing approach was adopted in the signal decomposition and analyses. An experimental setup was built to obtain the magnetic signature regarding some preselected fault configurations.

Contribuição a aplicação das wavelets na eletrostática

This work presents the methodology from the determination the charges superficial density, in two simple structure a to straight thread and in plane plates, both finite and submitted to a constant potential. That involves the method of the moments using as expansion function the wavelets instead of the pulse function, in order to reach a good precision and reducing the computational execution time. We also intends to take advantages of the wavelets application through the Cholesky decomposition, talking about formation of scattered matrixes, and the detection of nulls values.

Evaluation of electromagnetic interference from railway electric power system harmonics

This work shows an evaluation methodology for the occurrence of electromagnetic interference in signaling and control equipment of a DC electrified railway under contingency conditions in which the traction rectifying unit works with 6 pulses instead of the 12 pulses of its normal operation. Thus, electromagnetic interference can result from the direct interaction of the magnetic fields close to the rails as well as the resultant induction in the cables that interconnect the signaling and control equipment

Overview on the Evolution of Near Magnetic Field Coupling Prediction Using Equivalent Multipole Spherical Harmonic Sources

In the electromagnetic compatibility behavior of power electronic converters, parasitic magnetic couplings between components are one of the main causes of dysfunctions or poor filtering. These couplings may be either conducted or near-field interferences. To handle interaction problems, full knowledge of these magnetic couplings is essential. This paper is an overview of the work on near magnetic field interference undertaken in the last 15 years by the International Maxwell Laboratory. This paper details a predictive method that accurately and efficiently calculates near magnetic field coupling between two sources. The method uses near-field multipolar expansion in spherical harmonics of electromagnetic sources to determine close magnetic coupling between two sources from their equivalent models. This paper also shows how theoretical developments of large loop antennas have evolved from the van Veen antenna, a model with only two degrees of freedom, to a more complex model in terms of degrees, order, and types of harmonics. In parallel, it describes developments in the measurement method that provides input to the theoretical model. To illustrate how the research has evolved, we discuss coupling between two complex sources to assess the accuracy of this predictive method.