Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Technological challenges >> Energy efficiency for smart buildings, electrical mobility and industrial processes
3 proposition(s).

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High efficiency power electronics transformer for renewable energy sources connected to the grid

Département des Technologies Solaires (LITEN)

Laboratoire Systèmes PV

01-09-2021

SL-DRT-21-0386

jeremy.martin@cea.fr

Energy efficiency for smart buildings, electrical mobility and industrial processes (.pdf)

The primary sources of electrical energy used in renewable energy systems are mainly with DC ouputs : We can indicate below, the main voltage characteristics of the power sources : -Photovoltaïcs (1.5 kVDC) -Energy storage systems (800V-1.5kVDC) -EHT Stacks (950 VDC) -Electric vehicle batteries (800VDC) On the other hand, the new energy transmission grids are also in DC : -HVDC: 100 kVDC to 1.6 MVDC Some rail power systems are also direct current: -Rail: 1.5 kVDC, 3 kVDC, SNCF 6 kVDC (experimental network project) DC collector architectures are foreseen in the following applications: -Distribution of energy in charging stations for electric vehicles -Onboard networks of naval propulsion machinery -Electric conversion chains for electric railway traction units -Production of photovoltaic energy -Stationary storage of electrical energy The objective of this thesis will be to obtain a modular DC / DC power electronics building block compatible with the voltage levels delivered by the ENR sources and allowing injection on the medium voltage DC. The electrical insulation of the primary sources will be unchanged: it will therefore be necessary to provide,the isolation of the sources through a very high efficiency transformer technology (> 99.5%) integrated at medium frequency into the conversion stages. The transformer will be one of the key elements of the problem and as such certainly the support for many innovations in terms of the use of magnetic materials (depending on the frequency range and the specification : amorphous materials, cut nanocrystalline, or specific ferrites can be used), the mechanical arrangement of these materials (orientation, charge rate, morphology), the electrical arrangement of the windings as well as the thermal management of the assembly, while ensuring an appropriate dielectric strength. -Injection can be done on a 6 kVDC network (SNCF experimental network) -The power electronics will be produced with high-voltage SiC semiconductors whose performance are far superior to Si équivalents semiconductors . The DTNM and the Ampère laboratory will provide their expertise on magnetic materials for the sizing of the transformer integrated in the conversion stages while the DTS will provide it's expertise in prototyping of medium/high power converters, prototyping of transformers , and also characterizations of power components.

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Experimental and numerical study of heat storage with phase change material with two heat transfer circuits

Département Thermique Conversion et Hydrogène (LITEN)

Laboratoire des composants et systèmes thermiques

01-10-2021

SL-DRT-21-0684

fabrice.bentivoglio@cea.fr

Energy efficiency for smart buildings, electrical mobility and industrial processes (.pdf)

Thermal storage is a key technological component to decorrelate heat production from its use. For steam, phase change material (PCM) storage technology is particularly relevant for many applications and is benefiting from many researches. However, to make the low carbon energy transition effective, two new needs are emerging, in particular for the production of hydrogen by high temperature electrolysis (EHT) and for "Carnot batteries": use two different fluids for the supply of energy and its restitution; simultaneously load and unload storage. The aim of the thesis is to experimentally study a MCP storage with two heat transfer fluids at a laboratory size. The tests aim to understand the dynamic and thermical behavior of this type of storage, made much more complex due to two heat transfer circuits. In addition, the management of such a storage will have to be redefined compare to the strategies used for a single coolant MCP storage. A modeling part will complete the experimental one in order to define of macroscopic modeling of the storage based on the experimental results.

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High frequency inductive coupling wireless power transfer based on GaN

Département Systèmes (LETI)

Laboratoire Autonomie et Intégration des Capteurs

01-10-2021

SL-DRT-21-0862

nicolas.garraud@cea.fr

Energy efficiency for smart buildings, electrical mobility and industrial processes (.pdf)

Wireless power transmission (WPT) technologies are booming with applications in the aerospace, consumer electronics, medical, automotive and defense sectors. The purpose of these technologies is to transmit electrical energy between two elements without using a physical medium with the maximum possible efficiency. Power transmission technology using resonant inductive coupling seems to be the most promising in terms of near-field efficiency. This thesis is part of the development of the thematic on wireless power transmission and power at CEA-LETI in Grenoble. In this context, the objective of the thesis is to study, develop and test the performances of this technology over the VHF frequency range (30-300 MHz) unexploited in the literature, by integrating GaN transistor-based electronics. The candidate will develop analytical and numerical models to optimize the electromagnetic coupler, compare the performances of existing systems in the literature, and propose, develop and test the performances of innovative GaN-based topologies. The final goal of the thesis is the analysis and understanding of the advantages and limitations of this technology compared to the lower frequencies traditionally used. A multidisciplinary profile oriented towards power physics and electronics is sought for this thesis. In addition to a solid theoretical background, the PhD student will need to possess teamwork skills and an aptitude for experimentation. The PhD student will be integrated in CEA-Leti's Systems Department, within teams of researchers with strong skills in the development and optimization of power and wireless power transmission systems.

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