Fuel cell system
First Claim
1. A fuel cell humidity determining method comprising:
- determining an absolute voltage difference between an average cell voltage for a plurality of individual cells of a fuel cell stack and a minimum cell voltage value for a voltage output by the individual cells;
comparing the absolute voltage difference with a first preset value;
selectively changing a flow rate of an oxidizer gas to change humidity in the fuel cell based on a comparison between the absolute voltage difference and the first preset value, the changing the flow rate of the oxidizer gas based on the comparison between the absolute voltage difference and the first preset value being prohibited when the absolute voltage difference is less than the first preset value so that the flow rate of the oxidizer gas is maintained, and the changing the flow rate of the oxidizer gas based on the comparison between the absolute voltage difference and the first preset value occurring when the absolute voltage difference greater than or equal the first preset value;
determining a humidity state in the fuel cell stack based on a change in the absolute voltage difference due to the change in the humidity in the fuel cell after the flow rate of the oxidizer gas has been changed, such that a change in the humidity state indicates whether the fuel cell is becoming excessively humid or insufficiently humid depending on the change in the flow rate of the oxidizer gas, wherein in the excessive humidity state, the flow rate of the oxidizer gas is increased and liquid in the fuel cell is dispersed; and
at least one of the following;
comparing the absolute voltage difference with a second preset value, which is greater than or equal to the first preset value, after the flow rate of the oxidizer gas has been increased, and determining the humidity state in the fuel cell stack being in an insufficiently humid state when the absolute voltage difference is greater than or equal to the second preset value; and
comparing the absolute voltage difference with the second preset value after the flow rate of the oxidizer gas has been increased, and determining the humidity state in the fuel cell stack being either in an excessive humid state or in an insufficient oxygen state when the absolute voltage difference is less than the second preset value.
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Accused Products
Abstract
A fuel cell system has an oxidizer gas flow rate adjuster that adjusts a flow rate of oxidizer gas of the fuel cell stack and a controller that determines a humidity state in the fuel cell stack. The controller has an average cell voltage calculator that calculates an average cell voltage, a minimum cell voltage calculator that calculates a minimum cell value, a voltage difference calculator that calculates a voltage difference between the average cell voltage and the minimum cell voltage, and a voltage comparator that compares the absolute voltage difference with a preset value. The flow rate of the oxidizer gas is changed based on a comparison between the absolute voltage difference and the preset value, and then the humidity state in the fuel cell stack is determined based on a change in the absolute voltage difference.
8 Citations
15 Claims
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1. A fuel cell humidity determining method comprising:
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determining an absolute voltage difference between an average cell voltage for a plurality of individual cells of a fuel cell stack and a minimum cell voltage value for a voltage output by the individual cells; comparing the absolute voltage difference with a first preset value; selectively changing a flow rate of an oxidizer gas to change humidity in the fuel cell based on a comparison between the absolute voltage difference and the first preset value, the changing the flow rate of the oxidizer gas based on the comparison between the absolute voltage difference and the first preset value being prohibited when the absolute voltage difference is less than the first preset value so that the flow rate of the oxidizer gas is maintained, and the changing the flow rate of the oxidizer gas based on the comparison between the absolute voltage difference and the first preset value occurring when the absolute voltage difference greater than or equal the first preset value; determining a humidity state in the fuel cell stack based on a change in the absolute voltage difference due to the change in the humidity in the fuel cell after the flow rate of the oxidizer gas has been changed, such that a change in the humidity state indicates whether the fuel cell is becoming excessively humid or insufficiently humid depending on the change in the flow rate of the oxidizer gas, wherein in the excessive humidity state, the flow rate of the oxidizer gas is increased and liquid in the fuel cell is dispersed; and at least one of the following; comparing the absolute voltage difference with a second preset value, which is greater than or equal to the first preset value, after the flow rate of the oxidizer gas has been increased, and determining the humidity state in the fuel cell stack being in an insufficiently humid state when the absolute voltage difference is greater than or equal to the second preset value; and comparing the absolute voltage difference with the second preset value after the flow rate of the oxidizer gas has been increased, and determining the humidity state in the fuel cell stack being either in an excessive humid state or in an insufficient oxygen state when the absolute voltage difference is less than the second preset value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A fuel cell system comprising:
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an oxidizer gas flow rate adjuster configured to adjust a flow rate of an oxidizer gas of a fuel cell stack; and a controller operatively coupled to the oxidizer gas flow rate adjuster to control the oxidizer gas flow rate adjuster, the controller including a voltage comparator configured to compare an absolute voltage difference between an average cell voltage for a plurality of individual cells of a fuel cell stack and a minimum cell voltage value for a voltage output by the individual cells with a first preset value, the controller being configured to selectively instruct the oxidizer gas flow rate adjuster to change the flow rate of the oxidizer gas to change humidity in the fuel cell based on a comparison between the absolute voltage difference and the first preset value, the controller being further configured to determine a humidity state in the fuel cell stack based on a change in the absolute voltage difference due to the change in the humidity in the fuel cell after the flow rate of the oxidizer gas has been changed, such that a change in the humidity state indicates whether the fuel cell is becoming excessively humid or insufficiently humid depending on the change in the flow rate of the oxidizer gas, wherein in the excessive humidity state, the flow rate of the oxidizer gas is increased and liquid in the fuel cell is dispersed; and the controller being further configured to perform at least one of the following operations; compare the absolute voltage difference with a second preset value, which is greater than or equal to the first preset value, after the flow rate of the oxidizer gas has been increased, and determine the humidity state in the fuel cell stack being in an insufficiently humid state when the absolute voltage difference is greater than or equal to the second preset value; and compare the absolute voltage difference with the second preset value after the flow rate of the oxidizer gas has been increased, and determine the humidity state in the fuel cell stack being either in an excessive humid state or in an insufficient oxygen state when the absolute voltage difference is less than the second preset value. - View Dependent Claims (15)
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Specification