Method and apparatus for controlling voltage from a fuel cell system

A method of operating a fuel cell system, comprising:

• supplying current at a number of output terminals from at least one of a fuel cell stack and a battery electrically coupled in parallel with the fuel cell stack;
• determining a current flow to and from the battery;
• determining an amount of deviation of a nominal charge of the battery from a defined desired nominal charge of the battery based on the determined current flow;
• and
• adjusting a partial pressure of a reactant flow to at least a portion of the fuel cell stack in a mathematically defined relation to the determined amount of deviation.

A method of operating a fuel cell system, comprising:

• supplying current to a number of output terminals from at least one of a fuel cell stack and a battery electrically coupled in parallel with the fuel cell stack;
• determining a voltage across the battery;
• determining an amount of deviation of the determined voltage across the battery from a defined desired nominal voltage across the battery;
• and
• adjusting a partial pressure of a reactant flow to at least a portion of the fuel cell stack in proportion to the determined amount of deviation.

A fuel cell system for providing power to a load, comprising:

• a fuel cell stack having a number of fuel cells;
• a battery having a number of battery cells electrically couplable in parallel across the fuel cell stack;
• a reactant delivery system for delivering reactant to the fuel cells, the reactant delivery system including at least a first control element adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells;
• and
• a control circuit coupled to receive signals corresponding to an operating condition of the battery and configured to determine a deviation of the operating condition of the battery from a desired operational condition of the battery based on the received signals, the control circuit further coupled to control the at least first control element based on the determined deviation.

A fuel cell system for providing power, comprising:

• a fuel cell stack having a number of fuel cells;
• a battery electrically couplable in parallel across the fuel cell stack;
• a reactant delivery system for delivering reactant to the fuel cells, the reactant delivery system including at least a first flow regulator adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells;
• and
• a control circuit coupled to receive signals corresponding to a flow of current to and from the battery and to provide a control signal to at least the first control element mathematically related to a difference between a defined desired charge on the battery and a nominal charge on the battery determined from the flow of current to and from the battery.

A fuel cell system for providing power, comprising:

• a fuel cell stack having a number of fuel cells;
• a battery electrically couplable in parallel across the fuel cell stack;
• a reactant delivery system for delivering reactant to the fuel cells, the reactant delivery system including at least a first flow regulator adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells;
• and
• a control circuit coupled to receive signals corresponding to a voltage across the battery and to provide a control signal to at least the first control element mathematically related to a difference between the voltage across the battery and a defined desired voltage across the battery.

A fuel cell system for providing power to a load, comprising:

• a fuel cell stack having a number of fuel cells;
• a battery having a number of battery cells, groups of the battery cells electrically couplable in parallel across respective groups of the fuel cells;
• and
• a reactant delivery system for delivering reactant to the fuel cells, the reactant delivery system including at least a first control element adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells.

A fuel cell system for providing power to a load, comprising:

• a fuel cell stack having a number of fuel cells;
• a battery having a number of battery cells, portions of the battery interconnected with portions of the fuel cell stack such that the battery is electrically coupled in parallel across the fuel cell stack;
• a reactant delivery system for delivering reactant to the fuel cells, the reactant delivery system including at least a first control element adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells;
• and
• a control circuit coupled to receive signals corresponding to an operating condition of the battery and configured to determine a deviation of the operating condition of the battery from a desired operational condition of the battery based on the received signals, the control circuit further coupled to control the at least first control element based on the determined deviation.

A fuel cell system to power a load, the comprising:

• means for supplying current to the load from at least one of a fuel cell stack and a battery electrically coupled in parallel with the fuel cell stack;
• means for determining an operational condition of the battery;
• means for determining an amount of deviation of the determined operational condition of the battery from a desired operational condition of the battery;
• and
• means for adjusting a partial pressure of the reactant flow based on the determined amount of deviation for at least one reactant flow to at least a portion of the fuel cell stack.

A fuel cell system for providing power to a load, comprising:

• a voltage bus;
• a first fuel cell stack having a number of fuel cells electrically couplable across the voltage bus;
• a first battery having a number of battery cells electrically couplable in parallel across the first fuel cell stack on the voltage bus;
• a first reactant delivery system for delivering reactant to the fuel cells of the first fuel cell stack, the first reactant delivery system including at least a first control element adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells of the first fuel cell stack;
• a first control circuit coupled to receive signals corresponding to an operating condition of the first battery and configured to determine a deviation of the operating condition of the first battery from a desired operational condition of the first battery based on the received signals, the first control circuit further coupled to control the at least first control element based on the determined deviation;
• a second fuel cell stack having a number of fuel cells electrically couplable across the voltage bus;
• a second battery having a number of battery cells electrically couplable in parallel across the second fuel cell stack on the voltage bus;
• a second reactant delivery system for delivering reactant to the fuel cells of the second fuel cell stack, the second reactant delivery system including at least a second control element adjustable to control a partial pressure in a flow of a reactant to at least some of the fuel cells of the second fuel cell stack;
• a second control circuit coupled to receive signals corresponding to an operating condition of the second battery and configured to determine a deviation of the operating condition of the second battery from a desired operational condition of the second battery based on the received signals, the second control circuit further coupled to control the at least second control element based on the determined deviation.