Due to mass constraints, composite materials are possible candidates to replace metal alloys for electromagnetic shielding applications. The design of standard metallic shielding enclosures often relies on finite-element calculations. But in the case of composite materials, the strong dependence on the shielding properties to the microstructure makes the finite-element approach almost impossible. Indeed meshing the microstructure would imply a huge number of elements, incompatible with usual computational resources. We propose in this paper to develop homogenization tools to define the effective electromagnetic properties of composite materials at microwave frequencies. The ratio between the characteristic size of the microstructure and the wavelength is shown to be a key parameter in the homogenization process. The effective properties can then be used as an input for electromagnetic compatibility standard tools, designed for homogeneous media.Index Terms-Effective medium, heterogeneous materials, homogenization, inclusion problem, Maxwell-Garnett model, shielding effectiveness.

This paper focuses on the design of a contactless charging system for Electric Vehicle (EV) using inductive loops connected to a resonance converter. The study carries out the system operation, electromagnetic radiation and testing. It is shown that the presence of the chassis leads to a double resonance and has a strong influence on the radiated fields. Index Terms-EV, inductive charging, resonance converter, radiated EMF.0018-9545 (c)

International audienceThis paper presents an evaluation of the EMFs in the human body exposed to the wireless inductive charging system of electric vehicles such that the compliance of this charging system with respect to human EM exposure limits can be examined. A magnetic resonance imaging-derived and high-resolution model of the human body is used. An exposure assessment of a representative wireless inductive charging system, under a limited set of operating conditions, is provided to estimate the induced EMFs. The numerical analysis is performed with the finite element method. Numerical modeling of the system next to a standing human model shows that the EM exposure limits can be absolutely satisfied even when the transmitter coil is very close to the body. Furthermore, the worst configuration for the exposure evaluation of the wireless charging system is taken into consideration. This paper provides a useful guideline for the industry to develop inductive charging systems following the safety standards of radiation protection

International audienceReflectometry-based methods are the standard choice for fault detection techniques in wire networks. While effective when dealing with simple networks and relatively hard faults, their results can be of more difficult interpretation if a network presents more than two branches. In this paper we propose the use of an alternative technique based on a coherent multi-port characterization of a network under test. The data thus collected are used to define excitation signals that will be focusing over the position of a fault, following a method already successfully applied in geophysical prospection techniques and non-destructive testing, namely the DORT method, based on the synthesis of time-reversed signals. It is shown that a direct transposition of this technique to wire networks is not possible, due to the guided nature of wave propagation in wire networks, leading to the impossibility of assuming a dominant direction of propagation, as opposed to the case of propagation in open media. A differential version of the DORT method is introduced, enabling an accurate identification of the original position of faults. Numerical and experimental results are presented to demonstrate the feasibility of this approach

This paper proposes a methodology for the assessment of the human exposure to magnetic fields generated by dynamic inductive power transfer systems for automotive applications. Since the magnetic field is pulsed, current safety standards and guidelines require the use of time-domain approaches to evaluate the peak exposure which has to be limited under the prescribed limits. This paper shows that, for these kind of systems, the peak exposure can be efficiently evaluated by means of a time-harmonic formulation. Furthermore, a methodology to identify the worst case scenario is proposed.

International audienceA new technique is proposed to reconstruct faulty wiring networks from the time-domain reflectometry (TDR) response. The developed method is also for characterization of defects in the branches of the network. The direct problem (propagation along the cables) is modeled by RLCG circuit parameters computed by finite element method (FEM) and the finite-difference time domain (FDTD) method. Genetic algorithms (GAs) are used to solve the inverse problem. The proposed method allows to accurately locate wire faults. Some examples are presented to validate and illustrate the ability of this reconstruction method

This paper deals with magnetic source characterization in time domain. The basic idea is to solve the inverse problem using the measured near field radiation cartography. In order to ensure the identification procedure, the Time Reversal (TR) technique is used. This procedure allows both the spatial and temporal focusing determination by forcing waves to virtually converge to their initial source. The originality of the proposed methodology is to present a full time domain study of a magnetic source reconstruction. Indeed, this approach is particularly suitable for structures that emit non-sinusoidal radiations such as power electronic systems. First, the Electromagnetic Time Reversal (EMTR) basis are introduced. Then a simulation case study is discussed. Finally, results from an experiment test are presented to verify the proposed methodology. The measured results are in good agreement with the calculated electromagnetic fields. The experimental validation shows that compared to other identification techniques, especially those developed in the frequency domain, the proposed approach is more efficient and simple.

Decomposition of the time reversal operator (DORT) was recently applied to the problem of detection and location of soft faults in wire networks and proved effectual when dealing with a single fault, even in the case of complex network configurations. In this paper, the case of location of multiple faults is addressed, first proving that the standard DORT formulation does not allow to take a clear decision about the individual position of each fault. An alternative version of the DORT, based on an updating procedure, is presented and demonstrated to enable accurate and selective location of multiple soft faults. The proposed procedure is also shown to allow estimating the reflection coefficient of each fault, thus giving access to their severity.