Startup control method and control system for fuel cell

1. A startup control method for a fuel cell, comprising:

calculating, by a controller, available power of a first-voltage battery when a startup of the fuel cell is requested;

comparing, by the controller, the calculated available power of the first-voltage battery with driving power required for driving an air compressor at a predetermined fixed target rotation speed, wherein in response to determining that the available power of the first-voltage battery is less than the driving power of the air compressor, the target rotation speed is varied to adjust the driving of the air compressor;

driving, by the controller, the air compressor based on a calculated magnitude of the available power of the first-voltage battery and the target rotation speed varying in response to an increasing change rate of the rotation speed of the air compressor; and

charging, by the controller, a second-voltage battery with the power of the first-voltage battery after the driving of the air compressor is completed,

wherein the first-voltage battery has a higher voltage than the second-voltage battery, and

wherein the driving of the air compressor further includes:

determining, by the controller, an opening degree of a pressure control valve formed in an air discharge line of the fuel cell in response to the increasing change rate of the rotation speed of the air compressor; and

operating, by the controller, the pressure control valve based on the determined opening degree,

wherein the opening degree of the pressure control valve is inversely proportional to the increasing change rate of the rotation speed of the air compressor according to the available power of the first-voltage battery.

2. The startup control method of claim 1 , wherein in response to determining that the available power of the first-voltage battery is equal to or greater than the driving power of the air compressor, the air compressor is operated at the predetermined fixed target rotation speed.

3. The startup control method of claim 1 , wherein the available power of the first-voltage battery is calculated based on a temperature and a state of charge (SOC) of the first-voltage battery at the time of the startup request of the fuel cell.

4. The startup control method of claim 1 , wherein the increasing change rate of the rotation speed of the air compressor is determined based on the calculated magnitude of the available power of the first-voltage battery.

5. The startup control method of claim 4 , wherein the increasing change rate of the rotation speed of the air compressor is determined to be increased as the magnitude of the available power of the first-voltage battery is increased.

6. The startup control method of claim 1 , further comprising:

operating, by a controller, a converter disposed between the first-voltage battery and the second-voltage battery to charge the second-voltage battery.

7. A startup control system for a fuel cell, comprising:

a fuel cell;

an air compressor configured to supply air to the fuel cell;

a second-voltage battery configured to supply power to electric parts;

a first-voltage battery configured to supply stored power to the air compressor or the second-voltage battery, wherein the first-voltage battery has a higher voltage than the second-voltage battery;

a pressure control valve disposed on an air discharge line of the fuel cell; and

a controller configured to:

calculate available power of the first-voltage battery when the startup of the fuel cell is requested;

compare the calculated available power of the first-voltage battery with driving power required for driving the air compressor at a predetermined fixed target rotation speed, wherein in response to determining that the available power of the first-voltage battery is less than the driving power of the air compressor, the target rotation speed is varied to adjust the driving of the air compressor;

drive the air compressor based on a calculated magnitude of the available power of the first-voltage battery and the target rotation speed varying in response to an increasing change rate of the rotation speed of the air compressor; and

charge the second-voltage battery using the power of the first-voltage battery after the driving of the air compressor is completed,

wherein the controller is configured to determine an opening degree of the pressure control valve formed on the air discharge line of the fuel cell in response to the determined increasing change rate of the rotation speed of the air compressor and operate the pressure control valve based on the determined opening degree, and

wherein the opening degree of the pressure control valve is inversely proportional to the increasing change rate of the rotation speed of the air compressor according to the available power of the first-voltage battery.

8. The startup control system of claim 7 , wherein the increasing change rate of the rotation speed of the air compressor is determined based on the calculated magnitude of the available power of the first-voltage battery.

9. The startup control system of claim 7 , further comprising:

a converter disposed between the first-voltage battery and the second-voltage battery, wherein the controller is configured to operate the converter to charge the second-voltage battery with the power of the first-voltage battery.