Fuel cell/battery passive hybrid power source for electric powertrains

The concept of passive hybrid, i.e. the direct electrical coupling between a fuel cell system and a battery without using a power converter, is presented as a feasible solution for powertrain applications. As there are no DC/DC converters, the passive hybrid is a cheap and simple solution and the power losses in the electronic hardware are eliminated. In such a powertrain topology where the two devices always have the same voltage, the active power sharing between the two energy sources can not be done in the conventional way. As an alternative, control of the fuel cell power by adjusting its operating pressure is elaborated. Only pure H2/O2 fuel cell systems are considered in this approach. Simulation and hardware in the loop (HIL) results for the powertrain show that this hybrid power source is able to satisfy the power demand of an electric vehicle while sustaining the battery state of charge.

► Fuel cell hybrid vehicles are under consideration.
► We consider the direct electrical coupling of a fuel cell and a battery.
► The fuel cell power is actively controlled by adjusting its operating pressure.
► The power demand of a vehicle is fulfilled while sustaining the battery SOC.
► Without DC/DC converter, the hybrid powertrain becomes simpler and cheaper.