Fuel cell power system having DC to DC conversion, method of distributing DC power, and method of operating a fuel cell power system

A fuel cell power system, comprising:

• a fuel cell which generates DC voltage;
• a plurality of ultracapacitors selectively electrically coupled with the fuel cell, and which each have an operational voltage range;
• batteries coupled in parallel with respective ultracapacitors;
• first circuitry electrically coupling the fuel cell with the ultracapacitors and which maintains the respective ultracapacitors in the operational voltage range;
• and
• second circuitry which electrically couples and de-couples a number of the ultracapacitors to a load which has a voltage requirement, and wherein the number of ultracapacitors coupled to the load approximates the voltage requirement of the load.

A fuel cell power system, comprising:

• a plurality of fuel cells which respectively generate DC voltage while operating;
• a plurality of ultracapacitors, a group of one or more of the ultracapacitors being associated with one of the fuel cells, and each ultracapacitor having a voltage condition;
• circuitry which, when operating, electrically couples a fuel cell to its associated group in response to the voltage of that group being less than a first predetermined voltage, and electrically de-couples the fuel cell from its associated group in response to the voltage of that group being greater than a second predetermined voltage;
• and
• circuitry which, when operating, selectively electrically couples and de-couples the ultracapacitors to and from a load, the circuitry selecting the number of ultracapacitors electrically coupled to the load at a particular time based upon the power demands of the load at the time.

A fuel cell power system comprising:

• a plurality of fuel cells, each fuel cell being defined by a plurality of fuel cell subsystems electrically coupled together in series, each fuel cell subsystem, in operation, producing direct current electrical energy;
• a plurality of ultracapacitors, a group of one or more ultracapacitors being associated with each fuel cell, and each ultracapacitor having a voltage condition;
• a switch electrically coupled to each fuel cell to selectively electrically couple the fuel cell to its associated group;
• control circuitry to cause the switches, for each fuel cell, to electrically couple the fuel cell to the associated group in response to the voltage condition of that group being less than a first predetermined voltage, and to electrically de-couple the fuel cell from the associated group in response to the voltage condition of that group being greater than a second predetermined voltage, the control circuitry further causing the switches to couple and de-couple the ultracapacitors to and from a load at different times, the number of ultracapacitors electrically coupled to the load at any selected times being chosen by the control circuitry based upon the voltage requirements of the load and the voltage condition of the ultracapacitors.

A fuel cell power system comprising:

• a plurality of fuel cells, each fuel cell being defined by a plurality of fuel cell subsystems electrically coupled together in series, and wherein each fuel cell subsystem, in operation, produces direct current electrical energy;
• a plurality of ultracapacitors, each ultracapacitor being associated with a fuel cell, and each ultracapacitor having a voltage condition;
• a second fuel cell, defined by a second plurality of fuel cell subsystems, electrically coupled together in series, and associated with at least one of the ultracapacitors, and wherein the second fuel cell is in parallel with the first fuel cell which is associated with that ultracapacitor;
• a switch electrically coupled to each fuel cell to selectively electrically couple the fuel cell to its associated ultracapacitor;
• and
• control circuitry to cause the switches, for each fuel cell, to electrically couple the fuel cell to the associated ultracapacitor in response to the voltage of that ultracapacitor being less than a first predetermined voltage, and to electrically de-couple the fuel cell from the associated ultracapacitor in response to the voltage of that ultracapacitor being greater than a second predetermined voltage, the control circuitry further causing the switches to couple and de-couple ultracapacitors to and from a load at different times, the number of ultracapacitors electrically coupled to the load at a selected time being chosen by the control circuitry based upon the voltage requirements of the load and the voltage of the ultracapacitors.

A method of operating a fuel cell power system, comprising:

• providing a plurality of fuel cells which, in operation, respectively produce direct current electrical energy;
• providing a plurality of ultracapacitors, each ultracapacitor having a voltage condition;
• electrically coupling a fuel cell to an ultracapacitor when the voltage of that ultracapacitor is less than a first predetermined voltage, and electrically de-coupling the fuel cell from the ultracapacitor when the voltage of that ultracapacitor is greater than a second predetermined voltage;
• and
• selectively coupling and de-coupling ultracapacitors to and from a load, the number of ultracapacitors electrically coupled to the load at a certain time being selected based on the power demands of the load.

A method of distributing electrical DC power, which is generated by a fuel cell power system, to a load, comprising:

• defining a plurality of fuel cells, by electrically coupling a plurality of fuel cell subsystems together in series to define each fuel cell;
• providing a plurality of ultracapacitors, each ultracapacitor being associated with a fuel cell, each ultracapacitor having a voltage condition;
• providing a switch associated with each fuel cell, and which selectively electrically couples the fuel cell to its associated ultracapacitor;
• selectively controlling the switches to electrically couple a fuel cell to the associated ultracapacitor when the voltage of that ultracapacitor is less than a first predetermined voltage, and to electrically de-couple the fuel cell from the associated ultracapacitor when the voltage of that ultracapacitor is greater than a second predetermined voltage, and further causing the switches couple and de-couple ultracapacitors to and from a load at different times, the number of ultracapacitors electrically coupled to the load at one time being selected by the control circuitry based on the voltage requirements of the load and the voltages of the ultracapacitors.

A method of distributing electrical DC power, which is generated by a fuel cell power system, to a load, comprising:

• defining a plurality of fuel cells, by electrically coupling a plurality of fuel cell subsystems together in series to define each fuel cell;
• providing a plurality of ultracapacitors, each ultracapacitor being associated with a fuel cell, each ultracapacitor having a voltage condition;
• providing one or more additional fuel cells in parallel with one or more of the first mentioned fuel cells;
• providing a switch associated with each ultracapacitor, and which selectively electrically couples the fuel cell to its associated fuel cell and any additional fuel cells parallel to the associated fuel cell;
• selectively controlling the switches to electrically couple an ultracapacitor to an associated fuel cell and any additional fuel cells parallel to the associated fuel cell when the voltage of that ultracapacitor is less than a first predetermined voltage, and to electrically de-couple the ultracapacitor from the associated fuel cell and any additional fuel cells parallel to the associated fuel cell when the voltage of that ultracapacitor is greater than a second predetermined voltage, and further causing the switches couple and de-couple ultracapacitors to and from a load at different times, the number of ultracapacitors electrically coupled to the load at a particular time being selected based on the power requirements of the load.