Contribution à la conception d'onduleurs multicellulaires parallèles : Comparaison de topologies et analyse des imperfections des coupleurs magnétiques

In the aim of limiting the environmental footprint of current aircrafts, the electrification of non-propulsive systems and of the propulsion chain is a promising way forward. The aeronautical field has set ambitious objectives in terms of limiting polluting emissions, especially CO2, leading to the necessity of integrating new system architectures. Thus, the replacement of mechanical, hydraulic and pneumatic systems by lighter electrical systems is becoming essential to reduce weight and limit fuel consumption. This thesis is set in this perspective, and plans to study structures of parallel multilevel inverters to follow the rise in power of the converters without drastically increasing the voltage level. Thus, a 4-leg parallel-interleaved multilevel inverter with a capacitive bridge is studied in this thesis. This structure uses magnetic coupling between the inductances of each leg using InterCell transformers (ICT). This allows an improvement of the signals quality as well as a reduction of the volume and weight of the output filtering components. Two coupling topologies are studied in detail. The Secondary Loop topology, which is not well developed in the literature, has shown promising results in terms of availability in case of failure, compared to the Cyclic Cascade topology, which is generally used for this type of application. The analytical modeling, control and sizing of the ICT at 25 kW/phase of these two coupling topologies is discussed and compared. Despite the higher availability of the Secondary Loop topology, its sizing results show that it requires twice the iron surface as the Cyclic Cascade topology, to transmit the same power. The experimental validations on a prototype up to 15 kW/phase show a very good adequacy with the simulation results. These validations also demonstrate the sensitivity of the structure due to imperfections in the ICT and inverter legs. A detailed study on the impacts of component mismatches when sizing of the ICT in the case of the Cyclic Cascade topology is evaluated. Finally, the ability of the control to correct these imbalances is also presented.