Method for revising a polarization curve that defines the current/voltage relationship of a fuel cell stack
First Claim
1. A method for revising a polarization curve that defines the current/voltage relationship of a fuel cell stack, said method comprising:
- defining a reference polarization curve at a first point in time;
revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is below a predetermined threshold by changing a first adaptation value; and
revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is above the predetermined threshold by changing a second adaptation value, wherein the first adaptation value defines an absolute voltage difference between the predicted average cell voltage of fuel cells in the stack and the average cell voltage of the reference polarization curve for a particular stack current density, and the second adaptation value defines a current dependent voltage difference between the predicted average of cell voltage of fuel cells in the stack and the average cell voltage of the reference polarization curve for the particular stack current density.
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Accused Products
Abstract
A method for revising a reference polarization curve of a fuel cell stack that identifies the relationship between the voltage and the current of the stack over time. When the stack is operating at a low load where kinetic voltage losses of the stack dominate, a first adaptation value is revised as the difference between the actual stack voltage and the stack voltage of the reference polarization curve. When the stack is operating at higher loads where ohmic voltage losses of the stack dominate, a second adaptation value is revised as the difference between the actual stack voltage and the stack voltage of the reference polarization curve.
7 Citations
20 Claims
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1. A method for revising a polarization curve that defines the current/voltage relationship of a fuel cell stack, said method comprising:
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defining a reference polarization curve at a first point in time; revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is below a predetermined threshold by changing a first adaptation value; and revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is above the predetermined threshold by changing a second adaptation value, wherein the first adaptation value defines an absolute voltage difference between the predicted average cell voltage of fuel cells in the stack and the average cell voltage of the reference polarization curve for a particular stack current density, and the second adaptation value defines a current dependent voltage difference between the predicted average of cell voltage of fuel cells in the stack and the average cell voltage of the reference polarization curve for the particular stack current density. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for revising a polarization curve that defines the current/voltage relationship of a fuel cell stack, said method comprising:
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defining a reference polarization curve at a first point in time; and revising the reference polarization curve to match an actual polarization curve of the stack over time when the stack current density is either below or above a predetermined threshold, wherein the predetermined threshold defines a transition between where kinetic and voltage losses are dominate and where ohmic voltage losses are dominate, where the kinetic voltage losses are dominate below the threshold and the ohmic voltage losses are dominate above the threshold. - View Dependent Claims (13)
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14. A method for revising a polarization curve that defines the current/voltage relationship of a fuel cell stack, said method comprising:
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defining a reference polarization curve at a first point in time; revising the reference polarization curve at a later point in time to match an actual polarization curve of the stack when the stack current density is below a predetermined threshold by changing a first adaptation value; and revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is above the predetermined threshold by changing a second adaptation value, wherein the predetermined threshold defines a transition between where kinetic voltage loses are dominate and where ohmic voltage loses are dominate, where the kinetic voltage loses are dominate below the threshold and the ohmic voltage loses are dominate above the threshold. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification