The durability and the reliability of fuel cells are key points to promote hydrogen. To increase the fuel cell system lifetime, diagnostic, prognostic and smart control approaches are developed by researchers. They allow detecting failures, forecasting the remaining useful lifetime and act on the system through sensors to face degradation. Nevertheless, as the ageing of the FC stack is slow, some long-term tests are needed. The aim is to develop accelerated stress tests to reduce expensive and time-consuming experiments to validate durability approaches. This paper is dedicated to studying three different experimental tests on proton exchange membrane fuel cells (PEMFC) and the degradation impact of two stress factors: the frequency and the magnitude

This paper focuses on the experimental identification of a proton exchange membrane water electrolyzer models. Two types of approaches are investigated: temporal and frequency domains identification techniques. The obtained models are validated and compared. A discussion is then provided to highlight the implications of using these identified models, particularly with respect to the choice of operating points, the impact of aging on model complexity, and their relevance for control and diagnostic purposes.

This paper is dedicated to the control of hydrogen production with an experimental proton exchange membrane water electrolyzer in the context of renewable energy sources. Two control laws, $i \mathbf{P}$ and PI controllers have been evaluated under several scenarii including renewable energy sources variations. A discussion of the performances of the controllers allows to formulate several open issues for the control of PEMWE in a renewable energy context.

An active model-free sensor fault tolerant control approach is presented in this paper. The proposed method is based on a model-free controller that has demonstrated an effective ability to work without any analytical model knowledge. The active fault tolerant control procedure has three stages: firstly, the model-free controller is designed using an ultra-local model; secondly, this ultra-local model is used to detect and estimate the sensor fault; thirdly, the obtained estimation is used to adapt the control law according to the sensor fault. The aim of the proposed active fault tolerant control procedure is to ensure that the regulated output, but not the measured one, tracks the desired trajectory despite the occurrence of a sensor fault. The developed method is validated via numerical simulations for both stable and unstable linear systems. The performances of the developed active fault tolerant control procedure for unstable systems are evaluated with and without saturation of the control input.