In addition to the fuel cell itself, fuel cell vehicles are also equipped with a battery. On the one hand, the battery acts as a buffer against dynamic load changes, such as overtaking, and on the other hand, it allows for increased efficiency and reduced aging of the fuel cell. This is because the fuel cell performs better with a more stable output – the vehicle’s fluctuating power requirements in traffic are balanced by the buffer battery.
But according to the researchers, this depends on energy management, which constantly divides the load between the fuel cell and the battery. That’s where the FC-IMPACT project comes in. The challenge here is that the optimal energy distribution depends heavily on a variety of factors such as speed, altitude, traffic and weather. However, these factors are usually unknown before the flight begins – so the system is unable to calculate the optimal energy management for the route. If energy management can be improved, hydrogen consumption can be reduced and the fuel cell’s service life can be extended.
Under the leadership of Professor Christoph Hametner, a team from the Institute of Mechanics and Mechatronics at the University of Vienna is working on predictive energy management strategies. These strategies take advantage of readily available static trajectory information such as speed constraints and altitude profile to improve energy management – in theory.
In the press release, the University of Vienna gives a practical example: In the mountains, for example, the battery is charged by the fuel cell before a mountain hike so that the battery can provide maximum support on slopes with high energy demands – allowing the fuel cell to operate more efficiently. Ideally, the battery is almost empty at the summit and can be recharged during the descent using recuperation. This should lead to an even greater increase in efficiency. In addition to saving fuel, the predictive concepts also allow the service life of the fuel cell to be increased.
Within the framework of the FC-IMPACT project, Professor Hametner’s team worked closely with the Graz-based technology company AVL, which has built a fuel cell demonstration vehicle based on a Volkswagen Passat. This collaboration made it possible to validate the predictive energy management strategies, which have already been extensively tested in simulations, using a real vehicle. The validation included both real driving cycles in road traffic and tests on a dynamometer. According to the press release, the simulation results were confirmed. Hydrogen consumption was reduced by more than six percent compared to a non-predictive strategy – the impact on the service life of the fuel cell has yet to be determined. This is part of the further work: According to the team, it is already looking for concepts that will further improve energy efficiency and service life.
tuwien.at (in German)
