Contribution à la caractérisation et à la modélisation de composants grand gap GaN–Application à un convertisseur en environnement sévère

This thesis focuses on the study of new gallium nitride-based power components and the characterisation of a high-temperature coffered ceramic substrate with a view to designing an integrated power converter operating in harsh environments. The work carried out during this thesis is part of the MEMPHIS/GALION (Module Électronique Miniature de Puissance Hermétique Innovant pour applications en environnement Sévère) project, the aim of which is to produce a demonstrator that reflects the expected improvements in power electronics: operation at higher converter switching frequencies and/or operation at higher temperatures. This work is dedicated to the electrical and thermal study of a switching cell (inverter arm) based on GaN components capable of operating at a switching frequency greater than 1 MHz. This component is characterised statically and then during switching, providing a reliable electrothermal behavioural model at ambient temperature and up to 190°C. These characterisations are used to produce a model of the complete structure of a chopper with its load in order to assess switching losses and the phenomena causing losses in the transistors and to understand their origins. These results are used to study and predimension a resonant structure (LLC) suitable for operation at switching frequencies above megahertz using the GaN transistors studied.