Scientific direction Development of key enabling technologies
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PhD : selection by topics

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

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Statistical modelling of coupled heat and air transfer in buildings

Département des Technologies Solaires (LITEN)

Laboratoire d'Intégration des Systèmes Energétiques

01-09-2021

SL-DRT-21-0212

aurelie.foucquier@cea.fr

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

The demand for air conditioning of buildings is bound to increase in the next decades, due to the combined effects of climate change and increasing comfort standards in all countries. The need to reduce the energy demand for cooling has led practitioners to reinstate and adapt traditional natural cooling practices, some of which have existed for centuries: ventilative cooling, cool roofs, green roofs, evaporative cooling, etc. The main barrier to a successful generalisation of natural cooling is the difficulty to ensure its performance. Accurate predictions of air flow rates are a necessary condition for a reliable design, but are also very uncertain. Moreover, once a natural cooling solution has been implemented, there is no way of assessing its effectiveness on thermal comfort. In order to address these challenges, we propose the development of data-driven modelling of coupled heat and air transfer in buildings, especially in warm weather conditions. The strategy of the project lays on using statistical learning methods for the characterisation and prediction of heat and air flow. The proposed Ph.D. thesis will have two main work packages: - The application of statistical models for time series (dynamic Bayesian networks, hidden Markov models, auto-regressive models, regime-switching models?) to learning the coupled heat and air transfer in buildings, and detecting events that influence it: occupation, windows opening, etc. - The monitoring of an experimental test house, in order to gather data for model training and validation.

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DC/DC converter based on piezoelectric material

Département Systèmes (LETI)

Laboratoire Electronique Energie et Puissance

01-10-2020

SL-DRT-21-0277

ghislain.despesse@cea.fr

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

The aim of this thesis is to design high-efficiency power converters based on resonating piezoelectric transducers. A large part of the work is to develop the electrical cycle able to energetically maintain the piezoelectric resonator in resonance and ensure zero-voltage switching, for electrical energy transfer from the source to the piezoelectric resonator or from the piezoelectric resonator to the output, in order to minimize the losses. An electronic power management circuit will be designed to enable this ideal energetic cycle. This electronic circuit will include several regulation loops to ensure the system stability and regulate the electrical output power. Finally, a study of the piezoelectric transducer size reduction will be done in view of a MEMS (Micro Electro Mechanical System) integration.

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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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High-effiency power hub for energy transition

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Electronique avancée, Energie et Puissance

01-10-2021

SL-DRT-21-0403

xavier.maynard@cea.fr

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

This subject addresses the scientific developments needed to design a power hub allowing, in a single stage of power electronics, to manage all the household energy flows: photovoltaic supply (...) , storage including the battery of electric vehicles (V2G), connection to the network (smart grid), etc. Previous works at CEA have already dealt with advanced high-efficiency high-frequency converter topologies, in particular using GaN components. We propose to go further, by studying the coupling of various energy sources and receivers using a single-stage converter. The design of the converter should take into account all parasitic components, and as far as possible minimize them. This approach is based on simulation (LTspice and / or Ansys Q3D) and testing tools allowing the development of a system with high efficiency. The purpose of the study will be the realization of the complete system integrating as far as possible an active filter for EMC.

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High-effiency power hub for energy transition

Département Systèmes (LETI)

Laboratoire Electronique Energie et Puissance

01-10-2021

SL-DRT-21-0609

sebastien.carcouet@cea.fr

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

This subject addresses the scientific developments needed to design a power hub allowing, in a single stage of power electronics, to manage all the household energy flows: photovoltaic supply (...) , storage including the battery of electric vehicles (V2G), connection to the network (smart grid), etc. Previous works at CEA have already dealt with advanced high-efficiency high-frequency converter topologies, in particular using GaN components. We propose to go further, by studying the coupling of various energy sources and receivers using a single-stage converter. The design of the converter and control policies will be carried out using a Model Based Design approach, involving numerical simulation and design tools in the same integrated development environment. The study will end with the implementation of control laws on a prototype elaborated in the laboratory.

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Short loop recycling study for permanents magnets with high content of heavy rare earth

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Matériaux et Composants Magnétiques

01-10-2021

SL-DRT-21-0637

sorana.luca@cea.fr

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

Thanks to their outstanding magnetic performance, NdFeB magnets dominate the permanent magnet market. The demand for these high-tech materials is growing rapidly with the development of clean energy (electric cars, wind turbines, etc.) and their environmental and economic impact is strong. Among the critical materials, heavy rare earths (HRE) enter in the composition of high performance NdFeB magnets, so there is a growing need for less costly and more environmentally friendly recycling technologies. The CEA/LITEN has been integrated into projects aiming at magnet recycling, including REE4EU (H2020), RECVAL (ANR), Permafrost (EIT Climate) and more recently VALOMAG (EIT Raw Materials). In addition, this topic is the subject of discussions industrial partners for the implementation of a French magnet recycling industry. The development of the new low content HRE magnets should aim to locate these critical elements at the periphery of the magnetic grains, where it is necessary to strengthen the resistance to de-magnetization. This also reduces the total amount contained in the magnets, compared to the conventional methods of dilution of HRE in the alloy. The PhD work fits in the «short-loop» recycling topic of NdFeB magnets with a high content of HRE (5 to 10 weight % of Dy or Tb). The idea consists on powdering the magnets and then the modification of their composition, microstructure and grain size will allow releasing the HRE they contain more easily. The powder microstructure will be characterized by SEM or TEM, at the end of the different steps of the pulverization process. The optimized powders will serve as a source of HRE that will be relocated to the periphery of the virgin powder grains during sintering. These techniques of mixing powders and localization of HRE will not only help to recover the coercive effect of the starting magnet but also, to go further, to improve it. The work will continue with the implementation of conventional powder metallurgy or netshape processes (LPBF, SPS, PIM) to make the most of the availability of these Dy-rich powders in short-loop recycling cycles. The results obtained will feed into LCA or technico-economic studies. Microstructure and magnetic properties of sintered magnets will validate the best recycling paths. This work will use the equipment of the Poudr'Innov 2.0 platform and the skills of the LMCM in powder metallurgy, magnetism and net-shape processes, combined with the skills of the PFNC and IRIG to characterize and quantify the location of TRL through their expertise.

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Crystalline anisotropic diffusion model of Heavy Rare Earths in NdFeB permanent magnets

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Matériaux et Composants Magnétiques

01-10-2021

SL-DRT-21-0673

cyril.rado@cea.fr

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

Neodymium-iron-boron (Nd-Fe-B) permanent magnets are today's best performing magnets. They represent a strategic challenge for the development of more efficient engines and generators (hybrid vehicles, wind turbines). The major issue is the availability of temperature-stable permanent magnets in a context of limited resources in Heavy Rare Earths (HRE : Dy, Tb). They are used by manufacturers to obtain a high coercivity of NdFeB magnets, i.e. their capacity to maintain their initial magnetization in the demagnetizing field imposed by the application. The increasing demand for NdFeB requires a significant reduction in the content of Heavy Rare Earth while maintaining the high coercivity of these magnets. The development of new magnets must focus on localizing these elements at the periphery of the grains of the magnetic phase, where it is necessary to strengthen the resistance to demagnetization. The aim of the thesis is therefore to control the diffusion of heavy rare earths at the periphery of the magnetic phase. The PhD work will combine an advanced experimental approach (development of single crystals, characterization of diffusion profiles, manufacture of magnets) with a modeling of diffusion kinetics, to understand and define the optimal conditions of localization at the periphery of the grains of the magnetic phase.

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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

jerome.pouvreau@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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Ecodesign applied to battery systems

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Prototypage et Procédés Système

01-10-2021

SL-DRT-21-0772

remy.panariello@cea.fr

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

The environmental impact of an electric vehicle, when used in a country such as France, is dominated by the production of the battery packs it contains. Work is on-going to find more sustainable battery chemistries. But in the meantime, is it possible to substantially reduce the environmental impact of a battery pack, by only working on the parts and assemblies surrounding the cells such as: mechanical structure, thermal management system, or embedded electronics? In this project, we propose to identify and evaluate various alternative designs aiming to reduce the environmental impact of automotive battery packs, focusing on "climatic impact" and "mineral raw materials" criteria. We will rely on Life Cycle Assessment and eco-design methods to assess state-of-the-art packs, and identify promising ways of improvement: new thermal or electrical management strategies, new mechanical designs, material selection or new material development. The evaluation and research for trade-offs should be carried out with of the help of simulation tools. We will then assess the viability of some of the solutions by building physical demonstrator(s), especially with the help of additive manufacturing processes. The project will happen in Grenoble (France), in close collaboration between various research units: department for Energy applied to transports (DEHT), department for new materials (DTNM), Life Cycle Assessment and eco-design lab (G-SCOP). It will cover various scientific domains such as: Life Cycle Assessment, numerical simulation, materials sciences, mechanical design, or manufacturing processes.

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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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