Estimation of the liquid water saturation in PEM fuel cells: A low-power peaking-free dead-zone observer approach.

Water management in polymer electrolyte membrane fuel cells (PEMFCs) is one of the most challenging issues affecting PEMFC efficiency and lifetime. The unavailability of reliably liquid water saturation sensors hinders the applicability of liquid water active control and supervision techniques. A promising technique that can be applied in this context are high-gain observers. However, the performance of this type of observer is significantly limited by the peaking phenomena and its noise sensibility. In general, this performance is not adequate for the considered estimation problem. For this reason, this work proposes a new high-gain observer without peaking and with reduced noise sensibility. The convergence of the observer is proven through rigorous arguments. Moreover, the algorithm is shown to be applicable in PEMFC systems through numerical simulations and experimental validation. It is shown that the proposed approach achieves a reduction of 32.3% of the mean square error in the estimation while maintaining the convergence rate and robustness of classical high-gain observers.