Sylvie Baranowski

Modeling Methodology of Automotive Electronic Equipment Assessed on a Realistic Subsystem

Conducted disturbances induced into automotive electronic equipment can be predicted in the early design phase by numerical simulation. This supposes a realistic modeling of the cable harness, as well as the electronic equipment. This paper evaluates a modeling method by the results obtained on a realistic automotive subsystem. The latter is composed of two pieces of electronic equipment connected to each other by a cable harness. This test case was performed on printed circuit boards (PCBs) with full or partial ground planes and using a representative sample of harnesses. Simulation results are compared with measurement results using multiple cable harness samples. A good agreement between measurement and simulation can be obtained for PCBs with full ground plane, provided that fringing effects of the electronic components are taken into account in the equipment model.

Determination of the high frequency parameters of the power transformer used in the railway substation

The paper deals with the modeling method of the power transformers (three phases) used in the railway substation. In order to propose a high frequency model, which will be valid in the frequency band varying from 10 kHz to 30 MHz, it is necessary to identify the various impedances with a good accuracy. Often, these impedances are measured with an impedance analyzer, but for high power transformers, like those used in railway substation, these measurements are more difficult to carry out due to low power level delivered by the impedance analyzer. In this paper, we propose to use measurements in the time domain to identify the transformer impedances. These impedances can be obtained through measurements in various test configurations of the transformer. In the second part of the paper, a high frequency model, using the electrical equivalent circuit, is proposed and validated by the measurement data.

Time-frequency processing adapted for the different electromagnetic compatibility issues in the railway domain

The railway environment is very rich in terms of electromagnetic disturbances. The variety of the transient and permanent interferences and the current evolution of the communication and signaling railway systems require the adaptation of EMC railway standards. In particular, standardized emission measurement methodologies are not fully adapted to measure transient interferences which can significantly affect new railway signaling and communication systems. In this paper, we study a new time-frequency processing specifically designed for railway EMC issues, which could be implemented on real time spectrum analyzers. A flexible methodology is proposed offering an optimum analysis in relation with the technical specifications of the different railway signaling and communication systems.

Time frequency processing dedicated to electromagnetic compatibility issues in the railway domain

The railway environment is characterized by various electromagnetic interferences (EMI) due to the large number of EMIs sources. In parallel, due to the variety of vulnerable systems (location, signalization, communication…) embedded or in the train vicinity, different techniques are required to study EMC issues. This work is focused on time-frequency tool adapted to the analysis of different EMI, whereas their significant differences in terms of frequency, power and time characteristics. Such tools could be integrated in real time spectrum analyzers in order to optimize measurements for railway EMC issues.

AN OPTICAL APPROACH TO DETERMINE THE STATISTICAL FEATURES OF THE FIELD DISTRIBUTION IN MODE STIRRED REVERBERATION CHAMBER

Frequency limitation of classical method requires the use of asymptotic approach, like ray tracing and image theory, to compute the field at high frequency. Due to the high conductivity of the metallic walls of the cavity (and then, to high reflection coefficients), the main problem of these methods is the difficulty to reach the convergence of the results during a reasonable computation time. As an example, simulation of an empty cavity with our computer can use few minutes for 90 points with N=10 but 6 hours for N=50! Comparison between simulation and theoretical χ distribution has been chosen in order to reduce the number of reflections per ray taken into account in the model. Nevertheless, this reduction allows the exact determination of the impulse response and then, the quality factor of the chamber (Tesche, 1997). The amplitude of the field computed in these conditions is not exact but its statistical behavior is correctly predicted, thus this model can be used as a tool to compare different characteristics of reverberation chambers: shape, material, ... The first results, in an empty cavity, are interesting but have still to be improved in order to introduce metallic objects inside the chamber and at last the stirrer in the model.