Modélisation Des Systèmes électriques Sous Contraintes Actives Et Passives Combinées Dans Le Cadre de L’électrification D’avions Légers

**Modélisation des systèmes électriques sous contraintes actives et passives combinées dans le cadre de l’électrification d’avions légers**:

- Réf **ABG-131801**
- Sujet de Thèse
- 09/05/2025
- Contrat doctoral
- Laboratoire Génie de Production
- Lieu de travail- Tarbes - Occitanie - France
- Intitulé du sujet- Modélisation des systèmes électriques sous contraintes actives et passives combinées dans le cadre de l’électrification d’avions légers
- Champs scientifiques- Sciences de l’ingénieur
- Energie
- Mots clés- Modélisation, impact environnemental, Convertisseur statique

**Description du sujet**:
Due to its predominantly decarbonised nature in France, electricity represents an increasingly part of the energy sources linked to individual or collective mobility systems: electric bicycles, electric cars, autonomous electric trains, more electric aircraft, etc. This energy transition is necessarily accompanied by a policy of designing energy-saving systems with maximised efficiency. This increase of efficiency involves, for example, the use of advanced electrical energy conversion structures that use magnetic coupling materials [1]. Magnetic structures are designed using precise local finite element methods. On the opposite, the models of these structures for systemic simulations are based on global characteristics such as impedance. The two previous approaches are not directly compatible.

Magnetic materials, whether hard to generate magnets or soft to create magnetic circuits, are widely used in electrical engineering systems, ranging from the rotating motor to the transformer present in static interleaved DC/DC converters for example. Magnetic materials involves multiphysical phenomena with temperature effects on magnetism (Curie temperature), magneto-mechanical effects such as magnetostriction [2], effects due to corrosion or effects due to the nature of the material itself [3].

Many of works in our laboratory aim to model coupled phenomena within electrical engineering and power electronics systems (electrical, thermal, mechanical, etc.) [4] using the same tool for systemic representation of physical phenomena: the bond graph [5]. This tool then leads to a dynamic representation of multiphysical systems combining macroscopic and microscopic characteristics. It has also been shown that bond graphs can be adapted to systems governed by irreversible partial differential equations such as diffusion equations.

In addition, recent works at LGP have focused on identifying the characteristics of non-linear magnetic materials through the study of their hysteresis cycle [6] with the aim of including these models in a dynamic simulation of a more complex system. The limitation of these models lies in their phenomenological aspects, from which time is often excluded as a variable. Thus, these models cannot be easily inserted into a temporal systemic simulation. Moreover, locally, the electromagnetic field responds to partial differential equations, thus allowing a temporal simulation of quantities on a microscopic scale relative to the magnetic component. Moreover, the electromagnetic field can be seen as a vector field carrying power and can therefore also be represented using the bond graph tool.

The work of the thesis will thus be articulated around 2 main and complementary activities:

- Local energetic representation of electromagnetic phenomena governed by second order partial differential equations (Maxwell's equations) by bond graph,
- Taking into account the local intrinsic physical properties of the material in order to reproduce macroscopic behaviour such as hysteresis.

The work will analyse if the bond graph, due to its properties, will be able to provide complementary analysis elements on the frequency behaviour of quantities but also on the characteristics of energy transfers through electromagnetic fields. It is expected that the work will highlight the possible limitations or advantages of this representation approach in relation to existing tools widely presented in literature.

The second phase of the work will focus on physical scaling methodologies that will allow to link local properties and behaviours of magnetic materials such as the state of the material to observable and quantifiable phenomena at the macroscopic scale. This crucial work could allow, via a unique approach, to insert the local multiphysical models developed into systemic time simulations. This would allow, for example, to study the global influence of temperature on the energy performance of static converters, thus allowing the optimisation of conversion efficiencies. As a consequence, this work could allow the macroscopic magnetic analysis of a material to be compared with its health condition or ageing.

In summary, the thesis work should enable the establishment of a generic approach for the implementation of a bond graph type representation for the modelling of electromagnetic phenomena in magnetic systems included