Power Management Investigations on a Fuel Cell-based Hybrid HiL Powertrain 2010-01-1090

In this paper, a fuel cell-based/SuperCapacitor (SuperCap) hybrid electric powertrain concept is studied for different power management strategies. For a series hybrid, range extender topology and a given load profile different power management strategies are structurally compared. Furthermore considerations about principal optimization approaches will be introduced. First, a power management with the usage of a rate limiter on the fuel cell power is studied. The usage of a rate limiter mitigates fast deterioration of the fuel cell service life. The limited power rate affects the power demand from the hybrid secondary power source, i.e. the SuperCaps, and a compromise needs to be found. A second power management focuses the use of fuel cells as a range extender for charging when a lower limit for the State-of-Charge (SOC) of the SuperCaps is reached. The charging however is done at the maximum power output of the fuel cells and stops, when a certain SOC is reached. Finally, a third power management algorithm is considered keeping the SOC at a constant level. The SOC level is chosen to keep the overall systems efficiency point of the hybrid powertrain. The three power management strategies are considered numerically and valided experimentally in a Hardware in the Loop (HiL)-environment, therefore thoroughly evaluated. For comparison different evaluation criteria is chosen, such as the difference between demanded and actual vehicle velocity, the fuel consumption, and the fuel cell life deterioration, which is assumed to be measured through the standard deviation of the fuel cell power output for each cycle.