Method for optimizing performance in fuel cell system

1. A fuel cell system comprising:

a cooling fan configured to cool a coolant;

a pump configured to pump the coolant; and

a controller communicatively connected with the cooling fan and the pump,

wherein the controller is configured to:

retrieve a preset cooling-fan RPM and a preset pump RPM,

optimize the cooling-fan RPM and the pump RPM through a decrease of the cooling-fan RPM and an increase of the pump RPM such that a coolant temperature at an inlet of a fuel cell stack satisfies a specified temperature condition and a total power consumption is minimized, wherein the total power consumption is a sum of a power consumption corresponding to the cooling-fan RPM and a power consumption corresponding to the pump RPM, and

store the optimized cooling-fan RPM and the optimized pump RPM,

wherein the controller is further configured to:

determine whether the coolant temperature at the retrieved cooling-fan RPM and the retrieved pump RPM exceeds a target temperature,

optimize the cooling-fan RPM and the pump RPM to lower the coolant temperature to the target temperature or less when the coolant temperature exceeds the target temperature, and

optimize the cooling-fan RPM and the pump RPM such that a difference between the coolant temperature and the target temperature is smaller than or equal to a threshold value and the total power consumption is minimized when the coolant temperature is lower than or equal to the target temperature,

wherein the controller is further configured to:

decrease the cooling-fan RPM and increase the pump RPM when the coolant temperature is lower than or equal to the target temperature,

compare a first total power consumption corresponding to the decreased cooling-fan RPM and the increased pump RPM with a second total power consumption corresponding to the retrieved cooling-fan RPM and the retrieved pump RPM,

decrease the cooling-fan RPM and increase the pump RPM when the first total power consumption is less than the second total power consumption, and

determine the retrieved cooling-fan RPM and the retrieved pump RPM to be optimized values when the first total power consumption is greater than or equal to the second total power consumption.

2. The fuel cell system of claim 1 , wherein the controller includes:

a cooling fan controller configured to control an RPM of the cooling fan; and

a pump controller configured to control an RPM of the pump.

3. The fuel cell system of claim 2 , wherein the cooling fan controller and the pump controller are integrated into a single module.

4. The fuel cell system of claim 1 , wherein the controller is further configured to:

determine whether the cooling-fan RPM is equal to a specified maximum RPM when the coolant temperature exceeds the target temperature, and

optimize the pump RPM through an increase of the pump RPM such that the coolant temperature satisfies the target temperature when the cooling-fan RPM is equal to the specified maximum RPM.

5. The fuel cell system of claim 4 , wherein the controller is further configured to output a cooling load limit notification when the cooling-fan RPM and the pump RPM are maximal.

6. The fuel cell system of claim 1 , further comprising:

a first cooling line through which a first coolant circulates, the first cooling line being configured to pass through the fuel cell stack;

a first radiator disposed on the first cooling line and configured to cool the first coolant;

a second cooling line through which a second coolant circulates, the second cooling line being configured to pass through a power electronic part;

a second radiator disposed on the second cooling line and configured to cool the second coolant; and

a heat exchanger configured to allow the first coolant and the second coolant to exchange heat with each other,

wherein the pump is disposed on the second cooling line, and

wherein the cooling fan is configured to cool at least one of the first radiator or the second radiator.

7. The fuel cell system of claim 1 , further comprising:

a first cooling line through which a first coolant circulates, the first cooling line being configured to pass through the fuel cell stack;

a first radiator disposed on the first cooling line and configured to cool the first coolant;

a second cooling line through which a second coolant circulates, the second cooling line being configured to pass through a power electronic part;

a second radiator disposed on the second cooling line and configured to cool the second coolant; and

a heat exchanger configured to allow the first coolant and the second coolant to exchange heat with each other,

wherein the pump is disposed on the first cooling line, and

wherein the cooling fan is configured to cool at least one of the first radiator or the second radiator.

8. A method for operating a fuel cell system, the method comprising:

retrieving a preset cooling-fan RPM and a preset pump RPM;

optimizing the cooling-fan RPM and the pump RPM through a decrease of the cooling-fan RPM and an increase of the pump RPM such that a coolant temperature satisfies a specified temperature condition and a total power consumption is minimized, wherein the total power consumption is a sum of a power consumption corresponding to the cooling-fan RPM and a power consumption corresponding to the pump RPM; and

storing the optimized cooling-fan RPM and the optimized pump RPM,

wherein the optimizing of the cooling-fan RPM and the pump RPM includes:

determining whether the coolant temperature at the retrieved cooling-fan RPM and the retrieved pump RPM exceeds a target temperature; and

optimizing the cooling-fan RPM and the pump RPM to lower the coolant temperature to the target temperature or less when the coolant temperature exceeds the target temperature, or optimizing the cooling-fan RPM and the pump RPM such that a difference between the coolant temperature and the target temperature is smaller than or equal to a threshold value and the total power consumption is minimized when the coolant temperature is lower than or equal to the target temperature,

wherein the optimizing of the cooling-fan RPM and the pump RPM includes:

decreasing the cooling-fan RPM and increasing the pump RPM when the coolant temperature is lower than or equal to the target temperature;

comparing a first total power consumption corresponding to the decreased cooling-fan RPM and the increased pump RPM with a second total power consumption corresponding to the retrieved cooling-fan RPM and the retrieved pump RPM; and

decreasing the cooling-fan RPM and increasing the pump RPM when the first total power consumption is less than the second total power consumption, or determining the retrieved cooling-fan RPM and the retrieved pump RPM to be optimized values when the first total power consumption is greater than or equal to the second total power consumption.

9. The method of claim 8 , wherein the optimizing of the cooling-fan RPM and the pump RPM includes:

determining whether the cooling-fan RPM is equal to a specified maximum RPM when the coolant temperature exceeds the target temperature; and

optimizing the pump RPM through an increase of the pump RPM such that the coolant temperature satisfies the target temperature when the cooling-fan RPM is equal to the specified maximum RPM.