Thèse Batterie Ac Modulaire Principe et Pertinence pour les Véhicules Électriques et le Stockage d'Énergie Stationnaire H/F - Doctorat.Gouv.Fr

Établissement : Institut National Polytechnique de Toulouse École doctorale : GEETS - Génie Electrique Electronique,Télécommunications et Santé : du système au nanosystème Laboratoire de recherche : LAPLACE - Laboratoire PLAsma et Conversion d'Énergie Direction de la thèse : Guillaume GATEAU ORCID 0000000187744819 Début de la thèse : 2027-09-01 Date limite de candidature : 2026-11-23T23:59:59 L'objectif de ce travail est d'étudier la pertinence et la définition d'une architecture de batterie modulaire destinée aux applications haute tension, en s'appuyant sur les possibilités offertes par les composants semi-conducteurs à grand gap, notamment le SiC et le GaN, dans le domaine de l'électronique de puissance.
L'étude cherchera à déterminer une architecture élémentaire capable de répondre aux contraintes spécifiques des véhicules électriques, notamment en matière de tension, de puissance, de rendement, de masse, de densité de puissance et de sûreté de fonctionnement, tout en évaluant son potentiel pour les applications de stockage stationnaire.
Bien que ces deux domaines présentent des contraintes différentes - masse et volume pour l'automobile, capacité et disponibilité pour le stationnaire - ils partagent un certain nombre de problématiques communes : conversion bidirectionnelle, fonctionnement haute tension, gestion du SOC et du SOH, équilibrage des modules, optimisation du rendement, gestion thermique, tolérance aux défauts et besoin de contrôle intelligent.
Ces similitudes pourraient permettre d'envisager la définition d'un bloc élémentaire commun de stockage et de conversion, qui serait ensuite assemblé et adapté en fonction de l'application finale. Une telle approche permettrait de mutualiser une partie des développements matériels et logiciels et d'envisager une plateforme modulaire commune, déclinable aussi bien pour les systèmes de traction électrique que pour les systèmes de stockage connectés au réseau.

The transition toward an increasingly electrified society is driving a profound evolution in electrical energy conversion and storage systems. The development of electric vehicles, increasing industrial demand, the growth of data centers, and the electrification of heating and transportation are all contributing to a significant increase in electricity demand. According to the International Energy Agency, global electricity consumption increased by 4.4% in 2024 and by 3% in 2025, while an average annual growth rate of 3.6% is expected between 2026 and 2030.
At the same time, electricity generation is evolving with the increasing integration of renewable energy sources such as photovoltaic and wind power. These sources have the advantage of producing low-carbon energy, but their variable and difficult-to-dispatch nature introduces new constraints for the electrical grid. The power system therefore needs greater flexibility in order to continuously adapt generation to consumption.
In this context, batteries are gradually becoming much more than a simple means of storing energy. They can constitute active elements of the electrical system, capable of rapidly absorbing or delivering power, contributing to grid stabilization, and shifting renewable generation over time. Batteries therefore represent a major flexibility tool for integrating solar and wind generation, providing grid-support services, and meeting the increasing demand from new loads such as electric vehicles and data centers.
This new modular approach opens up numerous opportunities for energy optimization, module utilization, aging management, operational continuity, and system control.
Principle of a Modular AC Battery
In a conventional electric vehicle architecture, the battery consists of a set of cells connected in series and parallel to obtain a voltage and capacity suitable for the application. It essentially acts as a high-voltage DC voltage source.

From the high-voltage battery, electrical energy is then distributed to different converters:
- High-Voltage DC Battery DC/AC Powertrain
- High-Voltage DC Battery DC/DC Power Distribution
For DC or AC charging, the principle is similar and involves an onboard charger (OBC):
- AC Grid isolated AC/DC charger batterie DC
- DC Grid isolated DC/DC charger batterie DC
This architecture therefore requires separate power converters, generally grouped into dedicated pieces of equipment.

The new modular battery concept proposes a different approach. The power electronics are integrated directly at the battery-module level and placed as close as possible to the cells. The voltage level of each module is therefore reduced, leading to lower voltage ratings for the power switches. This reduction in voltage rating generally results in improved module efficiency. The proposed architecture also makes it possible to integrate charger and inverter functions directly into the battery.
The evolution of the architecture can thus be conceptually represented by a series connection of elementary modules, each consisting of a battery (low voltage) paired with a power converter. The number of modules connected in series in this way depends on the voltage to be supplied. The battery thus becomes an integrated energy storage and power conversion system.

Each module can be associated with power electronics capable of controlling its contribution to the overall operation. Voltage, current, and power can therefore be managed at a much finer level than with a monolithic battery.
This evolution represents a significant change in philosophy. The battery is no longer considered merely as an electrochemical assembly providing a DC voltage; it becomes a set of intelligent energy modules capable of individually participating in energy conversion and management.

Increasing Voltage Levels in Electric Vehicles

One of the major developments in electric powertrains concerns the increase in operating voltage.
The first generations of electric vehicles largely used architectures around 400 V DC. 800 V architectures are now increasingly being adopted, particularly in vehicles requiring high charging power. Recent developments in automotive power electronics notably show a trend toward high-voltage architectures combined with the use of wide-bandgap semiconductor devices, particularly SiC.
This increase in voltage makes it possible to reduce losses and thermal constraints and potentially reduce the mass of cables and interconnections. It is particularly relevant for ultra-fast charging systems, where several hundred kilowatts must be transferred.
An architecture operating at around 1200 V DC could therefore represent an important evolution for future electric vehicles. However, this does not constitute an advantage alone: it also introduces new constraints related to insulation, creepage and clearance distances, component voltage withstand capability, electromagnetic compatibility, and personnel safety.
The modular architecture then becomes particularly attractive. It makes it possible to distribute electrical stresses and power conversion rather than concentrating all functions in a single high-power converter.

New Generation of Power Devices : SiC et GaN

The increase in voltage and converter switching frequency is accompanied by an evolution in the semiconductor devices used in power electronics.
Traditional silicon (Si) devices are progressively reaching their limits for certain high-voltage, high-frequency, and high-power-density applications. Materials known as Wide Bandgap (WBG) semiconductors, particularly silicon carbide (SiC) and gallium nitride (GaN), make it possible to explore new architectures.
SiC is particularly well suited to high-power and high-voltage applications. Its properties make it possible to consider faster switching, higher operating temperatures, and lower losses compared with certain silicon-based solutions. It is currently being extensively studied for high-voltage traction inverters and grid-connected converters.
GaN, on the other hand, offers particularly attractive characteristics for applications requiring very high switching frequencies. It can in particular be considered for DC-DC converters and certain chargers, with the objective of reducing the size of passive components and increasing power density.
In a modular battery, the integration of these wide-bandgap devices can therefore represent a particularly interesting area for improvement.
Thus, the combination of Modular Battery / Distributed Power Conversion + SiC/GaN could simultaneously explore several optimization levers:
- Increase in switching frequency;
- Reduction in conversion losses;
- Increase in power density;
- Reduction in the volume of magnetic and passive components;
- Reduction in cooling requirements;
- Increase in operating voltage;
- Increased integration of power electronics within the battery module.
SiC appears particularly relevant for high-voltage power functions associated with architectures capable of reaching 800 to 1200 V, while GaN can be investigated for certain functions requiring very high switching frequencies. However, the choice of semiconductor device will have to result from a trade-off between efficiency, cost, frequency, voltage, cooling, and reliability.


Optimization of Module Utilization and SoC Balancing

Modularity provides another fundamental advantage: the possibility of individually managing the different storage elements. In a conventional battery composed of numerous cells connected in series, the current is strongly constrained by the most limiting element. Differences in capacity, internal resistance, temperature, or aging can progressively lead to discrepancies between cells.
A modular architecture equipped with distributed power electronics, by contrast, makes it possible to take into account the individual state of each module. A module with a high SOC can be used more extensively during a discharge phase, while a module with a low SOC can temporarily be used less. During charging, the strategy can be reversed in order to bring the SOC levels closer together. This capability makes it possible to transform battery balancing into an active energy-management problem.
The control strategy can also take into account:
- SOC (State of Charge);
- SOH (State of Health);
- Temperature;
- Internal resistance;
- Current limits;
- Maximum available power;
- Estimated module aging.
The objective is therefore no longer simply to balance the cells, but to determine how each module can be used intelligently. This approach can make it possible to prevent an aging or temporarily constrained module from determining the performance of the entire system on its own.
It also opens the possibility of predictive aging management: certain modules can deliberately be subjected to lower levels of stress in order to homogenize the overall aging of the battery.


Operational Continuity and the 'Fail operational' concept.

Operational continuity is probably one of the most important advantages of a truly modular battery architecture.
In a highly centralized system, a failure of the main converter can lead to the shutdown of the entire function. This is referred to as a Single Point of Failure.
The modular architecture makes it possible to reduce or even eliminate this dependency. If a module becomes faulty, it can potentially be isolated while the other modules continue to operate. The maximum available power is then reduced, but the system does not necessarily have to shut down. The maximum available power can also be guaranteed through a specific sizing strategy including an additional module, referred to as a standby module.
This is the principle of Fail Operational, which must be distinguished from the Fail Safe principle. A Fail Safe architecture primarily seeks to place the system in a safe state in the event of a failure. A Fail Operational architecture, on the other hand, seeks to maintain the function despite the failure, potentially with degraded performance.
In an electric vehicle, this can be particularly interesting for the traction function. The loss of one module could result in a reduction in available power while still allowing the vehicle to continue moving, particularly in the case of autonomous vehicles.
In a stationary application, the issue may be even more important. An installation rated at several hundred kilowatts should not necessarily become completely unavailable because a single module has failed.
Modularity therefore makes it possible to consider an architecture in which the failure of one module does not necessarily mean the shutdown of the entire system. The resulting sequence can be described as follows: [Module failure module isolation power redistribution degraded operation or integration of a standby module]. This capability can significantly improve the overall availability of the system.


Application to Stationary Energy Storage and Electrical Grid Support

The benefits of a modular battery architecture are not limited to electric vehicles. Stationary energy storage is probably one of the applications in which the properties of modularity, distributed power conversion, and operational continuity are most meaningful.
The electrical system is currently undergoing a dual transformation: increasing consumption and changing generation patterns. Demand is increasing due to the electrification of transportation, heating, and industry, as well as the development of new high-power loads such as data centers. At the same time, the share of variable renewable energy sources is increasing rapidly. This situation creates a fundamental problem: consumption is not always synchronized with generation.
A photovoltaic panel primarily produces energy during the day, and its output varies according to solar irradiance. A wind turbine, meanwhile, depends on weather conditions. Electricity generation is therefore becoming increasingly variable. Energy storage makes it possible to introduce a temporal degree of freedom by absorbing renewable energy when it is available and delivering it later.
The modular battery ultimately makes it possible to consider a new generation of energy-storage systems in which the battery is no longer simply a set of cells associated with a BMS and an inverter. It becomes a set of intelligent modules integrating storage, conversion, measurement, and control.
Each module can determine its own state and adapt its contribution to the system. The global controller coordinates the system without necessarily imposing centralized control on every component. This architecture is particularly well suited to stationary energy storage because it makes it possible to consider scalable installations. New modules can be added to increase power or capacity, while existing modules can be individually replaced.

Profil Ingénieur avec Spécialisation en Electronique de Puissance

Application link: https://edd-projets.utoulouse.fr/