Baptiste Trajin

Wigner distribution for the diagnosis of high frequency amplitude and phase modulations on stator currents of induction machine

This paper deals with mechanical fault monitoring in induction machines from stator current measurements. The considered faults lead to amplitude and/or phase modulations of the measured stator current. The different faults can be characterized by their time-frequency signatures via the Wigner distribution. The time-frequency representations apply to complex signals that may be obtained through the Hubert transform of the real measured signal. In case of high frequency modulations, it can not be taken advantage of the time frequency signatures. This study proposes an alternative complex signal representation for modulated stator currents. The so-called space vector is obtained through the Concordia transform. From three stator current measurements, the Concordia transform builds a complex vector which conveniently carries the information about phase and amplitude modulations. This paper applies and compares the Wigner distribution computed with the Hilbert and Concordia transforms in case of simulated and experimental signals with various modulation frequency ranges.

Electro-thermal model of an integrated buck converter

This study deals with new integrated systems for power electronic applications including wide-band gap semiconductors. The integration of Silicon carbide (SiC) components provides new perspectives such as higher temperature operating points than conventional Silicon (Si) semiconductors. The present work intends to study the electro-thermal behaviour of an integrated buck converter composed of a Silicon IGBT (Insulated-Gate Bipolar Transistor) and a Silicon carbide diode. An analysis of local heat sources due to Joule effect and compact thermal model of the assembly are proposed to predict local temperature of power electronic components.

Thermographic investigation of heat source in transversely isotropic composites

This paper deals with the estimation of heat sources from infrared thermographic measures on anisotropic CFRP (Carbon-Fibre Reinforced Composites). Such procedure combines the data processing of the thermal signal, especially as spatial and temporal derivation quantities involved in the heat equation are notably affected by the measurement noise, and the determination of thermo-physical properties of the material, especially to account for the anisotropic conductivity behavior of the material. A comparative analysis of different filtering techniques is done to define a filtering method able to decrease the noise while keeping the useful features of the signal. Then, we use a homogenization scheme based on single-inhomogeneity solutions of Eshelby to derive the transversely isotropic thermal conductivity tensor.

Thermomechanical modeling and simulation of a silicone gel for power electronic devices

The aim of the study is to develop some nodal models describing thermomechanical link in power devices. It is focused on modeling, simulating and testing a component: the silicone gel used in power electronics modules. Due to the future availability of high temperature gel, this study is a first step to establish a multi-physic model. The study aims to establish fast and compact electro-thermomechanical model than can be connected to circuit models, representing other packaging components. In the first stage, a finite element model of a commercial gel is defined and some simulation results are presented. In the second stage, an equivalent “electrical” compact model is also suggested and compared to measurements and 3D simulation results. The results presented concern temperature dispatching in both, simulations and measurements, and averaged stresses as well as displacement within the silicone. Future works will describe the thermomechanical link in nodal models, as well as real environment surrounding the silicone gel. Indeed, the silicone thermal expansion impact will be monitored.