Presentation
Kenza Hassani obtained a Master's degree in Electronics, Electrical Energy and Automation (EEEA), Communicating Systems pathway, awarded jointly by Sorbonne Université and the CFA des Sciences. She is currently doctoral fellow in Electromagnetic Compatibility at Centrale Lyon.
Thesis project
- Study of the conducted immunity of power electronic converters based on large-gap semiconductor components.
In today's complex avionics system, several types of energy are used: mechanical, hydraulic, pneumatic and electrical. Aircraft manufacturers are increasingly convinced of the benefits of electrifying the aircraft, replacing non-propulsive systems (hydraulic and pneumatic) with electromechanical conversion chains. This electrification makes the sub-systems more powerful, dynamic and precise, with shorter maintenance times than with a hydraulic sub-system. They are also easier to maintain. As a result, the more electric avionics system can be increasingly economical by optimizing the management of sources and loads. In recent years, the Safran Group has been working on electrification and hybridization solutions to increase overall power density and reduce greenhouse gas emissions. From these research studies based on new technologies, it has been demonstrated that increasing the frequency and power of electronic power converters is necessary. Increasing the switching frequency and reducing the switching times of semiconductor switches on these converters makes electromagnetic compatibility between the building blocks that make up this equipment, as well as between the converter and its power supply network, the hard points of this electrified system. These challenges are driving research into the use of switches based on GaN-type semiconductor material in power converters, with a two-decade increase in switching frequency (from a few tens of kHz at present to several tens of MHz, which is the target for achieving the desired power densities). These new-generation converters represent a real breakthrough in power electronics, in terms of integration and power density gains. On the other hand, new methodological and technological approaches are required for safe use in increasingly electric aircraft. The use of converters with switching frequencies in the radio frequency range poses new challenges, as the robustness and reliability of these new structures are much more complex to define and ensure. Indeed, the interactions between these power converters and their environment are proving crucial, as not only are they sources of conducted and radiated disturbances in a much wider frequency range than before (MHz => GHz), but these switches based on GaN-type materials are also extremely sensitive in terms of their control stages, which are by nature very low impedance. Usually, conducted emissions from static converters are studied in order to dimension the countermeasures (EMC filters, shielding, etc.) required to comply with standards. In this study, it is proposed to study the electromagnetic susceptibility (EMC) of each technological brick of this converter (FPGA, isolation interface, close control stages and isolated power supplies, inverter arms, interconnection cabling) to assess the reliability of each subsystem that makes up a converter, as well as at the level of the converter itself (system). Indeed, EMC studies and related standards are in force to guarantee the operation of each device within its electromagnetic environment. These aspects of operating safety are obviously crucial in the air transport sector.
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