Storage of fuel cell energy during startup and shutdown or other power transitions
First Claim
1. A method for controlling a fuel cell power plant adapted to store energy in an energy storage system associated with said fuel cell power plant which is removed from an associated fuel cell stack during transition from being not operating to operating, and vice versa, or other power reductions, in response to a controller interconnected with said fuel cell stack and responsive to signals received by said controller to cause said fuel cell stack to start up and to cause said fuel cell stack to shut down or otherwise vary power output, said energy storage system responsive to electrical output provided thereto to store corresponding energy, said method comprising:
- during a transition selected from (a) startup of said fuel cell power plant or (b) shutdown of said fuel cell power plant or other reduction of power supplied by said fuel cell power plant, extracting, in the form of electrical output, energy generated by said fuel cell stack, said electrical output being provided to said energy storage device, thereby limiting the maximum average voltage in the fuel cells of said fuel cell stack during said transition.
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Accused Products
Abstract
During fuel cell startup and shutdown or other power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.
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Citations
3 Claims
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1. A method for controlling a fuel cell power plant adapted to store energy in an energy storage system associated with said fuel cell power plant which is removed from an associated fuel cell stack during transition from being not operating to operating, and vice versa, or other power reductions, in response to a controller interconnected with said fuel cell stack and responsive to signals received by said controller to cause said fuel cell stack to start up and to cause said fuel cell stack to shut down or otherwise vary power output, said energy storage system responsive to electrical output provided thereto to store corresponding energy, said method comprising:
during a transition selected from (a) startup of said fuel cell power plant or (b) shutdown of said fuel cell power plant or other reduction of power supplied by said fuel cell power plant, extracting, in the form of electrical output, energy generated by said fuel cell stack, said electrical output being provided to said energy storage device, thereby limiting the maximum average voltage in the fuel cells of said fuel cell stack during said transition.
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2. A method, comprising:
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operating a fuel cell power plant adapted to store energy, which is removed from an associated fuel cell stack, in an energy storage system associated with said fuel cell power plant during transitions including transitions from being not operating to being operating, and vice versa, and power reduction transitions from a first level of power demanded by a load, to a second level of power demanded by said load, said second level being lower than said first level, said energy storage system responsive to electrical output provided thereto to store corresponding energy in response to a controller interconnected with said fuel cell stack and responsive to one or more signals received by said controller to cause said fuel cell stack to start up, or to shut down, or to provide power to said load in response to demand for power by said load, said method comprising; during transitions including (a) startup of said fuel cell power plant, (b) shutdown of said fuel cell power plant, and (c) transition from providing power to said load at said first level to providing power to said load at said second level, providing to said energy storage device at least a portion of the energy generated by said fuel cell stack in the form of electrical power output which is in excess of any power demanded by said load during any of said transitions, thereby limiting the maximum average voltage in the fuel cells of said fuel cell stack during any of said transitions.
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3. A method, comprising:
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operating a fuel cell power plant to store energy in an energy storage system associated with said fuel cell power plant which is removed from an associated fuel cell stack during a power reduction transition, from a first level of power demanded by a load to a second level of power demanded by said load, said second level being lower than said first level, in response to a controller interconnected with said fuel cell stack and responsive to one or more signals received by said controller to cause said fuel cell stack to provide power to said load in response to demand for power by said load, said energy storage system responsive to electrical output provided thereto to store corresponding energy, said method comprising; providing to said energy storage device, during a transition from providing power to said load at said first level to providing power to said load at said second level, at least a portion of the energy generated by said fuel cell stack in the form of electrical power output which is in excess of the power demanded by said load, thereby limiting the maximum average voltage in the fuel cells of said fuel cell stack during said transition.
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Specification