Apparatus for improving the performance of a fuel cell electric power system
First Claim
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1. A power system for providing power to at least one load, the power system comprising:
- a fuel cell stack comprising a plurality of serially coupled fuel cells and operable to output a fuel cell stack voltage corresponding to a sum of an output voltage of each of the plurality of serially coupled fuel cells;
a means for shorting the fuel cell stack from time-to-time; and
a means for clamping electrically coupled in parallel with the fuel cell stack, wherein the means for clamping limits a positive value of the fuel cell stack voltage such that the fuel cell stack voltage does not exceed a maximum stack voltage limit at least during a period immediately following the shorting of the fuel cell stack.
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Abstract
Current pulsing improves the performance of fuel cells in a fuel cell stack based power system. Voltage clamping limits the voltage peaks that occur after a current pulse. In a hybrid power system, an electric storage device supplies the loads during current pulsing. The electric storage device may sink current to achieve the voltage clamping, and/or power system may employ other the voltage clamping circuits.
84 Citations
15 Claims
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1. A power system for providing power to at least one load, the power system comprising:
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a fuel cell stack comprising a plurality of serially coupled fuel cells and operable to output a fuel cell stack voltage corresponding to a sum of an output voltage of each of the plurality of serially coupled fuel cells; a means for shorting the fuel cell stack from time-to-time; and a means for clamping electrically coupled in parallel with the fuel cell stack, wherein the means for clamping limits a positive value of the fuel cell stack voltage such that the fuel cell stack voltage does not exceed a maximum stack voltage limit at least during a period immediately following the shorting of the fuel cell stack. - View Dependent Claims (2, 3, 4, 5)
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6. A power system, comprising:
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a power bus; a fuel cell stack comprising a plurality of serially coupled fuel cells, operable to output a fuel cell stack voltage corresponding to a sum of an output voltage of each of the plurality of serially coupled fuel cells, and electrically coupled in parallel with the power bus; a pulsing switch electrically coupled in parallel with the fuel cell stack and operable to current pulse the fuel cell stack; a controller coupled to selectively control the pulsing switch to current pulse the fuel cell stack from time-to-time; and a means for clamping electrically coupled in parallel with the fuel cell stack, wherein the means for clamping limits a positive value of the fuel cell stack voltage such that the fuel cell stack voltage does not exceed a maximum stack voltage limit at least during a period following the current pulsing of the fuel cell stack. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification