Alimentation et commande de drivers à très forte isolation galvanique pour des convertisseurs multi-niveaux dédiés à la traction ferroviaire

This project is the result of collaboration between the EPI team of the SATIE laboratory at ENS Cachan, the LAPLACE laboratory and ALSTOM Transport in the ANR "CONCIGI HT" project. Research in the railway traction area aims to reduce the increasing size and weight of the power train. Today, the desire to reduce travel time is complemented by the desire to reduce power consumption- it is an important information for the design of traction chains. The objective of this project is to replace parts of the locomotive power supply systems to reduce their size by 30%, thus to reduce the power consumption and increase by 8.5% the number of passengers. The work presented in this thesis focuses on the design and study of the drivers power supply for HV SiC semiconductor (up to a 10 kV transient voltage). The peculiarity of these semiconductors is their application: they are placed in multi-level converters in order to replace the 25 kV / 3 kV, 50 Hz transformers currently used for rail traction. The main constraint is the dielectric strength that reaches a maximum of 60 kV due to transient present on the catenary. So, the Double Galvanic Insulation Transformer (DGIT) has been developed to adapt to the need of holding dual dielectric (10 kV and 60 kV). In a first step, a structure for the dual galvanic insulation has been developed with the objective to minimize its size and weight. Its spatial and geometrical arrangements were also taken into account (as well as many parameters both relevant and contradictory), in order to obtain the optimal system and common and differential mode distributed capacities observing the high dielectric strength. In a second step a study of the DGIT adapted power supply has been completed and tested. The combination of DGIT inductive behavior, the driver low power and the multi-level aspect, involves an atypical work of this power supply converter. For each of these parts, a structural, frequencial and electrical study was performed in order to achieve the maximum optimal device in terms of volume, weight and loss, with respect to the main constraint of VHV (Very High Voltage). Finally, in a third step we studied the possibility of subtituing the optical fibers currently used for the control of lighters with a system based on radio-frequency transmission.