Impact of control strategies on the degradation of hybrid hydrogen-battery powertrains in railway applications

Hybrid hydrogen-battery powertrains represent a promising solution for sustainable transport. In these systems, a fuel cell converts hydrogen into electricity to power the motors and charge a battery, which in turn manages power fluctuations and enables regenerative braking. This study investigates degradation in hybrid powertrain components for the railway sector, focusing on optimizing their operation to enhance durability. The analysis, applied to a real case study on a non-electrified railway line in northern Italy, evaluates different operating strategies by constraining the fuel cell current ramp. The results show that operating the fuel cell with minimal power fluctuations – while relying on the battery to handle power peaks – offers a clear advantage. Specifically, reducing the maximum fuel cell current ramp from 1500 A/s (load-following operation) to 1 A/s (near-constant operation) extends fuel cell lifetime by 50.5%, though at the expense of a 25.1% reduction in battery lifetime.