Fuel cell system
View Patent ↗A fuel cell system which includes: a fuel cell fed with a reaction gas for generating power; an output detection unit which detects output current and voltage of the fuel cell; a storage unit which stores a standard current-voltage characteristic of the fuel cell, from which a standard voltage of the fuel cell at an output current thereof is obtainable; and a gas feed mismatch detection unit which detects a gas feed mismatch of the reaction gas, based on a comparison between the detected output voltage of the fuel cell and the standard voltage at the detected output current, obtained from the standard current-voltage characteristic stored.
1. A fuel cell system, comprising:
a fuel cell configured to be fed with a reaction gas and generate electric power at a predetermined required output power;
a reaction gas supply system configured to feed the reaction gas to the fuel cell at a feed rate;
an output detection unit configured to detect an output current and an output voltage of the fuel cell;
a storage unit which stores a standard current-voltage characteristic of the fuel cell, from which a standard voltage of the fuel cell at a given output current thereof is obtainable;
a gas feed mismatch detection unit configured to detect a gas feed mismatch of the reaction gas, based on a comparison between the output voltage of the fuel cell detected by the output detection unit, and the standard voltage at the output current detected by the output detection unit, obtained from the standard current-voltage characteristic stored in the storage unit; and
a gas feed control unit configured to control the gas feed of the reaction gas supply system,
wherein the gas feed control unit is configured to change the feed rate of the reaction gas from a first feed rate to a second feed rate, according to a result of the comparison between the standard voltage and the detected output voltage, when the gas feed mismatch of the reaction gas is detected by the gas feed mismatch detection unit,
wherein the first feed rate is determined as a first function of a product of the predetermined required output power and a first control stoichiometric ratio, and the second feed rate is determined as a second function of a product of the predetermined required output power and a second control stoichiometric ratio, and
wherein the gas feed control unit is configured to change the feed rate from the first feed rate to the second feed rate under a condition that the power generated by the fuel cell fed with the reaction gas at the first feed rate and the power generated by the fuel cell fed with the reaction gas at the second feed rate are maintained at the predetermined required output power.
2. The fuel cell system according to claim 1 , wherein the gas feed control unit is configured to decrease the feed rate of the reaction gas and bring the detected output voltage within a predetermined range based on the standard voltage, when the detected output voltage is higher than an upper limit of the predetermined range.
3. The fuel cell system according to claim 1 , wherein the gas feed control unit is configured to increase the feed rate of the reaction gas and bring the detected output voltage within a predetermined range based on the standard voltage, when the detected output voltage is lower than a lower limit of the predetermined range.
4. The fuel cell system according to claim 3 , wherein the gas feed control unit is configured to stop increasing the feed rate of the reaction gas even when the detected output voltage of the fuel cell is outside the predetermined range, when a rate of increase in the detected output voltage for an increase in the feed rate of the reaction gas by a predetermined amount is lower than a predetermined value.
5. The fuel cell system according to claim 1 , wherein the first control stoichiometric ratio and the second control stoichiometric ratio are different.
6. The fuel cell system according to claim 1 , wherein the first and second control stoichiometric ratios are reaction gas excess coefficients.
7. The fuel cell system according to claim 1 , wherein the first feed rate has a first fuel gas flow amount and a first oxidizer gas flow amount, and the second feed rate has a second fuel gas flow amount different from the first fuel gas flow amount and a second oxidizer gas flow amount different from the first oxidizer gas flow amount.
8. A method of operating a fuel cell system including a fuel cell which is fed with a reaction gas and generates electric power at a predetermined required output power, the method comprising:
feeding the reaction gas to the fuel cell at a feed rate;
storing a standard current-voltage characteristic of the fuel cell, from which a standard voltage of the fuel cell at a given output current thereof is obtainable;
detecting an output current and an output voltage of the fuel cell;
obtaining the standard voltage at the detected output current from the standard current-voltage characteristic;
comparing the detected output voltage with the standard voltage at the detected output current;
detecting a gas feed mismatch of the reaction gas, based on the comparison between the detected output voltage and the standard voltage at the detected output current; and
changing the feed rate of the reaction gas from a first feed rate to a second feed rate, according to a result of the comparison between the standard voltage and the detected output voltage, when the gas feed mismatch of the reaction gas is detected,
wherein the first feed rate is determined as a first function of a product of the predetermined required output power and a first control stoichiometric ratio, and the second feed rate is determined as a second function of a product of the predetermined required output power and a second control stoichiometric ratio, and
wherein the changing of the feed rate of the reaction gas from the first feed rate to the second feed rate is made under a condition that the power generated by the fuel cell fed with the reaction gas at the first feed rate and the power generated by the fuel cell fed with the reaction gas at the second feed rate are maintained at the predetermined required output power.
9. The method of operating a fuel cell system according to claim 8 , wherein the first control stoichiometric ratio and the second control stoichiometric ratio are different.
10. The method of operating a fuel cell system according to claim 8 , wherein the first and second control stoichiometric ratios are reaction gas excess coefficients.
11. The method of operating a fuel cell system according to claim 8 , wherein the first feed rate has a first fuel gas flow amount and a first oxidizer gas flow amount, and the second feed rate has a second fuel gas flow amount different from the first fuel gas flow amount and a second oxidizer gas flow amount different from the first oxidizer gas flow amount.
12. A fuel cell system, comprising:
a fuel cell configured to be fed with a reaction gas and generate electric power at a predetermined required output power;
a reaction gas supply means for feeding the reaction gas to the fuel cell at a feed rate;
output detection means for detecting an output current and an output voltage of the fuel cell;
a storage means for storing a standard current-voltage characteristic of the fuel cell, from which a standard voltage of the fuel cell at a given output current thereof is obtainable;
a gas feed mismatch detection means for detecting a gas feed mismatch of the reaction gas, based on a comparison between the output voltage of the fuel cell detected by the output detection means, and the standard voltage at the output current detected by the output detection means, obtained from the standard current-voltage characteristic stored in the storage means; and
a gas feed control means for controlling the gas feed of the reaction gas supply means,
wherein the gas feed control means is configured to change the feed rate of the reaction gas from a first feed rate to a second feed rate, according to a result of the comparison between the standard voltage and the detected output voltage, when the gas feed mismatch of the reaction gas is detected by the gas feed mismatch detection means,
wherein the first feed rate is determined as a first function of a product of the predetermined required output power and a first control stoichiometric ratio, and the second feed rate is determined as a second function of a product of the predetermined required output power and a second control stoichiometric ratio, and
wherein the gas feed control means is configured to change the feed rate from the first feed rate to the second feed rate under a condition that the power generated by the fuel cell fed with the reaction gas at the first feed rate and the power generated by the fuel cell fed with the reaction gas at the second feed rate are maintained at the predetermined required output power.
13. The fuel cell system according to claim 12 , wherein the first control stoichiometric ratio and the second control stoichiometric ratio are different.
14. The fuel cell system according to claim 12 , wherein the first and second control stoichiometric ratios are reaction gas excess coefficients.
15. The fuel cell system according to claim 12 , wherein the first feed rate has a first fuel gas flow amount and a first oxidizer gas flow amount, and the second feed rate has a second fuel gas flow amount different from the first fuel gas flow amount and a second oxidizer gas flow amount different from the first oxidizer gas flow amount.