Convertisseur à fort courant et faible tension de sortie, utilisant des transistors GaN, pour applications spatiales

This thesis explores the development of a non-isolated power converter based on GaN transistors intended for space applications. The new generation of computing units used in space applications, such as FPGAs, require converters capable of delivering voltages between 0.6V and 1.5V for currents up to 120A. The main objective of this work was to design a high-density POL converter capable of regulating input voltages from 5V to 12V for outputs ranging from 0.6V to 1.5V, with an output power greater than 100W. To overcome the limitations of existing converters, this thesis explores several innovations : an integrated current measurement within the PCB, optimization of the passive components of the selected topology, a non-linear multi-phase control technique implemented in analog, and the parallel operation of converters. The work presented is divided into three main axes. The first axis laid the design foundations necessary for realizing a synchronous Buck converter surpassing the performance of converters using the same topology in space applications. It also introduced an integrated current measurement and an associated optimization method, making this approach particularly competitive compared to traditional methods in this type of application. In the second axis, passive components from state-of-the-art topologies in terrestrial applications were optimized and compared to select the most efficient one for the targeted application. The algorithm developed for this optimization coupled SPICE simulations, using SPICE models from manufacturers for active components, theoretical calculations, and manufacturer data for magnetics. This optimization led to a double step-down buck converter topology and a two-phase, two-level topology. This was implemented and experimentally validated through a prototype to confirm its functionality and a second as an integrated power module demonstrating its compactness. The third axis of this thesis focused on the parallel operation of the previously developed SPOL40A converter. Several parallel operation techniques were compared based on various criteria, such as the ability to balance the currents supplied by each converter, ease of implementation using discrete analog components, and minimizing interconnections between modules. The active voltage positioning technique was selected and implemented. An analog schematic was proposed and experimentally implemented to validate its operation. A final prototype was built, enabling the conversion of an input voltage between 5V and 12V to 1V , delivering over 120A of current, exceeding the current state-of-the-art in space applications.