FUEL CELL SYSTEM AND PURGING CONTROL METHOD THEREOF

1 . A fuel cell system comprising:

an air pump configured to inject air into a fuel cell stack;

a purge valve configured to perform hydrogen purging based on an opening degree of the purge valve; and

a controller configured to calculate a cumulative current of the fuel cell stack and perform at least one of a first operation of controlling a number of rotations of the air pump based on the cumulative current, a second operation of controlling the opening degree of the purge valve, or a combination of the first operation and the second operation.

2 . The fuel cell system of claim 1 , wherein the controller is configured to reduce the number of rotations of the air pump in response to a result that the cumulative current is greater than or equal to a first value.

3 . The fuel cell system of claim 2 , wherein the controller is configured to control the purge valve by opening the purge valve to cause the purge valve to perform the hydrogen purging in response to a result that the cumulative current is greater than or equal to a reference value.

4 . The fuel cell system of claim 3 , wherein the reference value is set greater than the first value.

5 . The fuel cell system of claim 3 , wherein the controller is configured to adjust the reference value based on an output efficiency of the fuel cell stack.

6 . The fuel cell system of claim 5 , wherein the controller is configured to determine a reference efficiency based on the output efficiency.

7 . The fuel cell system of claim 6 , wherein the controller is configured to adjust the reference value from a second value to a third value in response to a result that the output efficiency is greater than or equal to the reference efficiency, and

wherein the third value is set greater than the second value.

8 . The fuel cell system of claim 7 , wherein the controller is configured to adjust the reference value from the third value to the second value in response to a result that the output efficiency is less than the reference efficiency after being equal to or greater than the reference efficiency.

9 . The fuel cell system of claim 5 , wherein the controller is configured to adjust the first value based on the reference value.

10 . A purging control method for a fuel cell stack, comprising:

calculating a cumulative current of the fuel cell stack; and

performing at least one of a first operation of controlling a number of rotations of an air pump based on the cumulative current, a second operation of controlling an opening degree of a purge valve, or a combination of the first operation and the second operation.

11 . The purging control method of claim 10 , wherein the performing of the at least one of the first operation of controlling the number of rotations of the air pump based on the cumulative current, the second operation of controlling the opening degree of the purge valve, or the combination of the first operation and the second operation includes:

comparing the cumulative current with a first value; and

reducing the number of rotations of the air pump when the cumulative current is equal to or greater than the first value.

12 . The purging control method of claim 10 , wherein the performing of the at least one of the first operation of controlling the number of rotations of the air pump based on the cumulative current, the second operation of controlling the opening degree of the purge valve, or the combination of the first operation and the second operation includes:

comparing the cumulative current with a second value; and

opening the purge valve when the cumulative current is greater than or equal to the second value.