THESIS SUBJECT

“Model based method dedicated to the diagnosis of Proton Exchange Membrane Fuel Cells”

About this thesis

Nowadays, Fuel cells (FCs) are considered as an attractive technological solu-tion for energy storage. In addition to their high efficiency conversion to electrical energy and their high energy density, FCs are a potential candidate to reduce the environmental impact of aircrafts. The present PhD thesis can be located within this context, and especially contributes to the development of methodologies dedicated to the monitoring of the state of health (SoH) of Proton Exchange Membrane Fuel Cells (PEMFCs).

FCs are submitted to ageing and various operating conditions leading to several failures or abnormal operation modes. Hence, there is a need to develop tools dedicated to the diagnosis and fuel cell ageing monitoring. One of reliable approaches used for the FC SoH monitoring is based on parametric identification of a model through experimental data.

Widely used for the FC characterization, the polarization curve (V-I) and the Electrochemical Impedance Spectroscopy (EIS) coupled with a model describing the involved phenomena may provide further information about the FC SoH. Two models were thus developed: a quasi-static model whose parameters are identified from the polarization curve and a dynamic one identified from EIS data. The need to develop a dynamic model whose formulation may vary over time “without a priori” has been reported in this thesis.

The original approach of this thesis is to consider conjointly both characterizations during all the proposed analysis process. This global strategy ensures the separation of the different fuel cell phenomena in the quasi-static and dynamic domains by introducing into each parametrization process (one for the quasi-static model and one for the dynamic model) parameters and/or laws stemming from the other part. The global process starting from the a priori knowledge until the identification of the models parameters was developed during the chapters of this thesis. In addition to the good reproduction of experimental data and the separation of the losses in both static and dynamic domains, the method makes it possible to monitor the FC SoH via the evolution of models parameters.

The fact to take into account the coupling between quasi-static and dynamic models revealed the notion of a “residual impedance”. This impedance makes it possible to overcome the recurrent experimental observation made by the daily users of EIS: there is a not-clearly explained difference between the low frequency resistance of the EIS and the slope of the polarization curve for a given current density. Theoretically the two quantities have to tend towards the same value. In others words, a part of the impedance spectra is not clearly and easily exploitable to characterize fuel cell performance. This topic has been discussed in the literature in the last years. An attempt to explain physico-chemical phenomena related to this impedance is also a part of objectives of this thesis.

From an experimental point of view, before applying this method to ageing monitoring, it was indeed necessary to “calibrate” it regarding its relative complex-ity. In this way, experiments with a single cell with different sets of internal components (different membrane thicknesses and different platinum loadings in the Active Layer (AL)) were achieved and analyzed by applying the proposed method. Therefore, the method was evaluated in the framework of three ageing campaigns carried out with three 1 kW PEM stacks.

FUCHYA PROJECT

The characterization and modelling of mature aeronautical fuel cells for use on the ground and in the automotive industry. Evaluating new electro-mechanical couples.

JURY

Delphine RIU	Rapporter	Professor at Grenoble INP
Nadia STEINER	Rapporter	Researcher at Université Franche-Comté
Jean-Baptiste JOLLYS	Examiner	Engineer at Safran Power Units
Théophile HORDÉ	Examiner	Engineer at Airbus
Julien D’ARBIGNY	Examiner	Engineer at Alstom
Bruno AUVITY	Examiner	Professor at Université de Nantes
François LAPIQUE	Examiner	Researcher at LRGP / Université de Lorraine
Christophe TURPIN	Thesis Director	Researcher at LAPLACE, Toulouse INP
Jérémi REGNIER	Thesis Co-Director	Researcher at LAPLACE, Toulouse INP

PUBLICATIONS

• Time constant based method for PEM fuel cell model characterization – S. El Aabid, J. Regnier, O. Rallières, C. Turpin, G. Gager, J. D’Arbigny, T. Hordé, L. Prissé – FDFC 2017 (7th International Conference on Fundamentals and Development of Fuel Cells) – Stuttgart, Germany
• Time constant based method for PEM fuel cell model characterization – S. El Aabid, J. Regnier, O. Rallières, C. Turpin, G. Gager, J. D’Arbigny, T. Hordé, L. Prissé – ELECTRIMACS 2017 (12th International Conference on Modelling and Simulation of Electric Machine, Converters and Systems) – Toulouse, France
• Calibration of a model approach based method dedicated to the diagnosis of Polymer Electrolyte Membrane Fuel Cell (PEMFC) – S. El Aabid – Congrès GEET 2018 – Toulouse, France
• Méthodes fines de diagnostic de l’état de santé d’une pile à combustible PEMFC en vue de sa maintenance – S. El Aabid, J. Regnier, C. Turpin, O. Rallières, E. Soyez, J. D’Arbigny, T. Hordé, JB. Jollys, E. Foch – GdR HySPàC 2018 – Grenoble, France
• A global approach for a consistent identification of static and dynamic phenomena in PEM Fuel Cell – S. El Aabid, J. Regnier, C. Turpin, O. Rallières, E. Soyez, N. Chadourne, J. D’Arbigny, T. Hordé, E. Foch – Mathematics and Computers in Simulation – 2019 – vol. 158, pp. 432-452 – DOI
• Monitoring of ageing campaigns of PEM fuel cell stacks using a model-based method – S. El Aabid, C. Turpin, J. Regnier, N. Chadourne, J. D’Arbigny, T. Hordé, G. Peres – FDFC 2019 (8th International Conference on Fundamentals and Development of Fuel Cells) – Nantes, France