Fuel cell power system and method of controlling a fuel cell power system
First Claim
1. A fuel cell power system comprising:
- a fuel cell which, in operation, converts chemical energy into direct current electrical energy, the fuel cell being defined by a plurality of independently operable fuel cell sub-systems;
a DC bus;
a switching circuit electrically coupled with the fuel cell sub-systems and configured to independently selectively couple the fuel cell sub-systems to the DC bus; and
an energy storage device electrically coupled with the DC bus and configured to be coupled to a load, and wherein the switching circuit selectively electrically couples a selectable number of the fuel cell sub-systems to the DC bus to supply direct current electrical energy to the energy storage device to charge the energy storage device.
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Accused Products
Abstract
A fuel cell power system includes a fuel cell which has an optimal voltage; an energy storage device having a nominal voltage substantially similar to the optimal voltage of the fuel cell; and an electrical switch that, in operation, selectively electrically couples the fuel cell and the energy storage device to charge the energy storage device. A method includes providing a fuel cell having a nominal voltage; providing an energy storage device having a nominal voltage which is substantially similar to the nominal voltage of the fuel cell and electrically coupling the energy storage device to a load; and selectively electrically coupling the fuel cell to the energy storage device to substantially maintain the energy storage device above a predetermined voltage threshold.
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Citations
25 Claims
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1. A fuel cell power system comprising:
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a fuel cell which, in operation, converts chemical energy into direct current electrical energy, the fuel cell being defined by a plurality of independently operable fuel cell sub-systems;
a DC bus;
a switching circuit electrically coupled with the fuel cell sub-systems and configured to independently selectively couple the fuel cell sub-systems to the DC bus; and
an energy storage device electrically coupled with the DC bus and configured to be coupled to a load, and wherein the switching circuit selectively electrically couples a selectable number of the fuel cell sub-systems to the DC bus to supply direct current electrical energy to the energy storage device to charge the energy storage device. - View Dependent Claims (2, 7, 8)
a power conditioner electrically coupled with the DC bus and the electrical charge storage device, and wherein the power conditioner, in operation, receives the direct current electrical energy and produces alternating current.
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7. A fuel cell power system as claimed in claim 1, and further comprising an additional fuel cell, and wherein the switching circuit is configured to independently switch the first mentioned fuel cell and the additional fuel cell for coupling to the DC bus.
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8. A fuel cell power system as claimed in claim 1, wherein the fuel cell comprises a fuel cell stack.
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3. A fuel cell power system as claimed in claim, wherein the energy storage device comprises a battery;
- an ultra-capacitor; and
/or batteries and ultra-capacitors and wherein DC electrical current from the fuel cell is selectively supplied to the battery;
ultra-capacitor; and
/or batteries and ultra-capacitors, in operation. - View Dependent Claims (4, 5, 6)
- an ultra-capacitor; and
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9. A fuel cell power system comprising:
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an inverter having a DC input and having an AC output configured to be coupled to a load;
a battery coupled to the DC input;
a plurality of fuel cell sub-systems; and
circuitry configured to measure the voltage of the battery and selectively couple a selectable number of the fuel cell sub-systems to the battery in response to the measured voltage of the battery. - View Dependent Claims (10, 11, 12, 13, 14)
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15. In a fuel cell power system including a power conditioning device having a DC input and having an electrical output which is configured to be coupled to a load;
- an energy storage device coupled to the DC input;
a plurality of fuel cell sub-systems; and
circuitry configured to measure the voltage of the energy storage device and selectively couple the fuel cell sub-systems to the energy storage device in response to the measured voltage of the energy storage device, a method comprising;(a) measuring the voltage of the energy storage device;
(b) determining if the measured voltage is less than a first threshold and, if so, proceeding to step (c) and, if not, proceeding to step (d);
(c) de-coupling all the sub-systems from the energy storage device;
(d) determining if the measured voltage is greater than or equal to a second threshold and, it so, proceeding to step (e) and, if not, proceeding to step (g);
(e) determining if all sub-systems are de-coupled from the energy storage device and, if so, proceeding to step (a) and, if not, proceeding to step (f);
(f) decoupling all of the sub-systems from the energy storage device;
(g) determining if the measured voltage is greater than or equal to a third threshold and, if so, proceeding to step (h) and, if not, proceeding to step (j);
(h) determining if all sub-systems are de-coupled from the energy storage device and, if so, proceeding to step (a) and, if not, proceeding to step (j);
(i) decoupling one of the sub-systems coupled to the energy storage device from the energy storage device;
(j) determining if the measured voltage is greater than or equal to a fourth threshold and, if so, proceeding to step (k) and, if not, proceeding to step (m);
(k) determining if all sub-systems are coupled to the energy storage device and, if so, proceeding to step (a) and, if not, proceeding to step (l);
(l) coupling one of the sub-systems de-coupled from the energy storage device to the energy storage device;
(m) determining if all sub-systems are coupled to the energy storage device and, if so, proceeding to step (a) and, if not, proceeding to step (n); and
(n) coupling all sub-systems to the energy storage device. - View Dependent Claims (16)
- an energy storage device coupled to the DC input;
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17. A method comprising:
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providing a plurality of independently operable fuel cells which convert chemical energy into direct current electrical energy;
providing an energy storage device;
coupling the energy storage device to a load;
monitoring the voltage of the energy storage device; and
varying the number of the fuel cells coupled to the energy storage device based upon the voltage of the energy storage device. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification