Abstract: A fuel cell system electrically couples a battery in parallel with the fuel cell stack to power a load. An operational condition of the battery is compared to a desired operating condition and a partial pressure of a reactant flow to at least a portion of the fuel cell stack is adjusted based on the determined amount of deviation. The operational condition can include voltage, charge of the battery. Individual fuel cell systems can be combined in series and/or parallel to produce a combined fuel cell system having a desired output voltage and current.

Abstract: A fuel cell system determines each of a battery charging current error, a battery voltage error, and a stack current error. The fuel cell system regulates current through a series pass element in response to a greater of the determined errors, operating in three modes: battery voltage limiting mode, stack current limiting mode and battery charging current limiting mode. Additionally, there can be a fourth “saturation” mode where the stack voltage VS drops below the battery voltage VB. A voltage difference across the series pass element is compared to a desired condition such as a saturation level, and a partial pressure of a reactant flow to the fuel cell stack adjusted based on the determined amount of deviation limiting the energy dissipated by the series pass element. Individual fuel cell systems can be combined in series and/or parallel to produce a combined fuel cell system having a desired output voltage and current.

Abstract: A power generating system which comprises a fuel cell and a rechargeable storage battery coupled together via a DC-DC converter. A reactant for the fuel cell is obtained by processing a suitable raw material. The processor is controlled on the basis of the current demanded by the external load and by the storage battery, and the fuel cell current drawn by the DC-DC converter is controlled on the basis of the amount of reactant available from the processor.