Device and method for controlling a fuel cell stack

Abstract

Device for controlling a fuel cell stack, comprising: a characteristic curve memory (10) configured to store a stoichiometric ratio (SR) characteristic curve in which a target air SR of the stack corresponding to an open-circuit decay time (ODT) is recorded, an operating temperature characteristic curve in which a target operating temperature of the stack corresponding to an outside temperature is recorded, and an operating temperature offset characteristic curve in which a target operating temperature offset of the stack corresponding to an ODT is recorded; a sensor (20) that is set up to detect an outside temperature; an ODT measuring device (30) configured to measure the time required for a cell voltage to reduce from a reference voltage to a threshold voltage when the supply of air to the stack is interrupted; and a fuel cell controller (40) configured to detect a target operating temperature of the stack corresponding to the outside temperature detected by the sensor (20), and to detect a target air SR of the stack and a target operating temperature offset of the stack corresponding to an ODT measured by the ODT measuring device (30), based on the SR characteristic, the operating temperature characteristic and the operating temperature offset characteristic.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a device and a method for controlling a fuel cell stack and in particular a technology for improving the performance of a fuel cell stack that has been reduced due to deterioration, based on an open-circuit decay time (ODT) which specifies the time required for a cell voltage to be reduced from a reference voltage to a threshold voltage when the supply of air to the fuel cell stack is interrupted / blocked. BACKGROUND

[0002] A fuel cell is a device that generates electricity by converting chemical energy from a fuel into electrical energy through an electrochemical reaction within a fuel cell stack, rather than converting the chemical energy from the fuel into heat through combustion. Fuel cells provide energy for industries, homes, and vehicles, and can also be used to power small electrical / electronic products, especially portable devices.

[0003] Proton exchange membrane fuel cells (PEMFCs), also known as polymer electrolyte membrane fuel cells, which have the highest power density among fuel cells, are currently being investigated as an energy source for powering vehicles. PEMFCs exhibit a fast start-up time and a fast power conversion response time due to their low operating temperature.Such a PEMC comprises: a membrane electrode assembly (MEA) featuring catalyst electrode layers in which an electrochemical reaction takes place, located on both sides of a solid polymer electrolyte membrane through which hydrogen ions migrate; gas diffusion layers (GDLs) that serve to distribute reaction gases evenly and to supply the generated electrical energy; seals and coupling elements to maintain an airtight seal for the reaction gases and coolant and a suitable clamping pressure; and bipolar plates that allow the reaction gases and coolant to move through them.

[0004] When such unit cells are assembled to form a fuel cell stack, a combination of key components, the MEA and GDL, is arranged in the innermost section of the cell. The MEA comprises the catalyst electrode layers, i.e., an anode and a cathode with a catalyst applied to both surfaces of the polymer electrolyte membrane to enable hydrogen and oxygen to react. The GDLs, seals, and other components are stacked on top of the anode and cathode in an outer section of the cell. The bipolar plates, each containing its own flow fields, are positioned outside the GDLs. These flow fields supply the reaction gases (hydrogen as a fuel and oxygen or air as an oxidizer) and allow the coolant to flow through them.

[0005] After the majority of unit cells are stacked in the arrangement / configuration described above, current collectors, insulating plates, and end plates for supporting the stacked cells are connected in the outermost section of the stack. The unit cells are repeatedly stacked and assembled between the end plates to form the fuel cell stack. To obtain the electrical potential required in a vehicle, it is necessary to stack the number of unit cells corresponding to the required amount of electrical potential energy, and the stacked unit cells are referred to as a stack. For example, the electrical potential generated by a single unit cell is approximately 1.3V, and to generate the power required to propel a vehicle, the majority of cells can be stacked in series.

[0006] Such a fuel cell stack suffers deterioration when driving time, mileage / mileage, and vehicle start frequency increase. This is not temporary deterioration resulting from a dry or overflow condition, but rather deterioration of the stack's membrane itself, which can reduce the fuel cell stack's output power, thus decreasing fuel efficiency and limiting the vehicle's starting power. Conventionally, when the fuel cell stack suffers deterioration, some of the cells within the stack are repaired or replaced to restore its performance. While such a conventional approach can be a basic solution, disassembling and reassembling the fuel cell stack is time-consuming and incurs replacement costs.

[0007] From DE 10 2007 037 628 A1, an electrochemical conversion arrangement is known with a plurality of electrochemical conversion cells arranged in a conductively coupled fuel cell stack, a state sensor operatively connected to the fuel cell stack, and a programmable controller operatively connected to the state sensor and the fuel cell stack. The state sensor is designed to measure a hydration change rate at the proton exchange membrane, and either the state sensor or the programmable controller is designed to generate a signal indicating the measured hydration change rate. The programmable controller is designed to facilitate the control of at least one operating parameter of the electrochemical conversion arrangement by monitoring the signal indicating the measured hydration change rate.The condition sensor can be designed to detect a change in size or pressure of the conductively coupled fuel cell stack while the membrane hydration changes.

[0008] DE 11 2007 000 141 T5 also discloses a fuel cell system comprising: a fuel cell including a plurality of unit cells to which a specific gas is supplied for generating electricity; means for calculating the stoichiometric ratio of the cell for calculating a stoichiometric ratio of the cell for the specific gas for each unit cell when the fuel cell is started; and means for increasing the amount of gas to increase the amount of the specific gas supplied when the stoichiometric ratio of the cell falls below a specified value. OVERVIEW

[0009] The object of the present disclosure is to provide a device and a method for controlling a fuel cell stack that improves the performance (output power) of the fuel cell stack, which suffers from degradation, by setting a stoichiometric ratio (SR) of air supplied to the fuel cell stack and an operating temperature of the fuel cell stack based on an open-circuit decompression time (ODT), which specifies the time required for a cell voltage to be reduced from a reference voltage (for example, approximately 1V) to a threshold voltage (for example, approximately 0.75V) when the supply of air to the fuel cell stack is interrupted / disconnected.

[0010] The problem is solved by a device having the features of claim 1 and a method having the features of claim 5. Advantageous embodiments are found in the dependent claims. The object of the present disclosure is not limited to the aforementioned problem, and all further objects and advantages not mentioned herein can be clearly understood from the following description. The present inventive concept will be better understood with reference to exemplary embodiments of the present disclosure. In addition, it is obvious that the objects and advantages of the present disclosure can be achieved by the elements claimed in the claims and a combination thereof.

[0011] According to one embodiment of the present disclosure, a device for controlling a fuel cell stack may comprise: a characteristic curve storage device (characteristic map storage device) configured to record an SR characteristic curve or SR map in which a target air SR of the stack corresponding to an ODT is recorded, an operating temperature characteristic curve or operating temperature map in which a target operating temperature of the stack corresponding to an outside temperature is recorded, and an operating temperature offset characteristic curve or operating temperature offset map in whichin which a target operating temperature offset of the stack, corresponding to an ODT, is recorded; a sensor configured to detect an outside temperature; an ODT measuring device configured to measure a time (ODT) required for a cell voltage to be reduced from a reference voltage to a threshold voltage when the air supply to the stack is interrupted / disconnected; and a fuel cell controller configured to detect a target operating temperature of the stack corresponding to the outside temperature detected by the sensor, and to detect a target air SR of the stack and a target operating temperature offset of the stack corresponding to a time measured by the ODT measuring device, based on the SR characteristic (SR map), the operating temperature characteristic (operating temperature map), and the operating temperature offset characteristic (operating temperature offset map).

[0012] According to a further embodiment of the present disclosure, a method for controlling a fuel cell stack may comprise: storing, by means of a characteristic curve memory (map memory), an SR characteristic curve in which a target air SR of the stack corresponding to an ODT is recorded, an operating temperature characteristic curve (operating temperature map) in which a target operating temperature of the stack corresponding to an outside temperature is recorded, and an operating temperature offset characteristic curve (operating temperature offset map) in which a target operating temperature offset of the stack corresponding to an ODT is recorded; detecting, by means of a sensor, an outside temperature; detecting, by means of a fuel cell controller, a target operating temperature of the stack corresponding to the detected outside temperature, based on the operating temperature characteristic curve (operating temperature map);Measuring, by an ODT measuring device, the time (ODT) required for a cell voltage to reduce from a reference voltage to a threshold voltage when the air supply to the stack is interrupted / disconnected; and acquiring, by the fuel cell controller, a target air SR of the stack and a target operating temperature offset of the stack corresponding to the measured ODT, based on the SR characteristic (SR map) and the operating temperature offset characteristic (operating temperature offset map). BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and further tasks, features and advantages of the present disclosure will become more apparent from the following detailed description in conjunction with the accompanying drawings. Fig. 1 represents the configuration / arrangement of a device for controlling a fuel cell stack according to an embodiment of the present disclosure; Fig. 2 represents an SR characteristic curve according to an embodiment of the present disclosure; Fig. Figure 3 represents an operating temperature characteristic curve according to an embodiment of the present disclosure; Fig. 4 represents the operating temperature offset characteristic curve according to an embodiment of the present disclosure; Fig. 5 presents the analysis of the performance of a fuel cell stack controlled by a new method according to an embodiment of the present disclosure; Fig. Section 6 presents the analysis of the performance of a fuel cell stack controlled by a new method according to a further embodiment of the present disclosure; and Fig. Figure 7 represents a flowchart of a method for controlling a fuel cell stack according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0014] It is understood that the term "vehicle" or "vehicle-" or other equivalent terms as used herein include motor vehicles in general, such as passenger cars including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft including a variety of boats and ships, aircraft and the like, and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other vehicles powered by alternative fuels (for example, fuel derived from sources other than petroleum). As referenced herein, a hybrid vehicle is a vehicle having two or more sources of propulsion, such as both gasoline-powered and electric-powered vehicles.

[0015] Although the embodiment is described as using a plurality of units to perform the exemplary process, it is understood that the exemplary processes can also be performed by one or more modules. Furthermore, it is understood that the term controller / control unit refers to a hardware device comprising memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute said modules to perform one or more processes, which are described below.

[0016] Furthermore, the control logic of the present invention can be implemented as non-volatile, computer-readable media on a computer-readable medium comprising executable program instructions that are executed by a processor, a controller / control unit, or the like. Examples of computer-readable storage media include, without limitation, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium can also be decentralized in networked computer systems, so that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0017] The terminology used herein is intended for the purpose of describing certain embodiments and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It is further understood that the expressions "possess" and / or "possessing," when used in this description, describe the presence of the specified features, numbers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more features, numbers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated listed elements.

[0018] Unless expressly stated otherwise or evident from the context, the term "approximately" as used herein shall be understood to mean that the value lies within a range of standard tolerances in the prior art, for example, within two standard deviations of the mean values. "Approximately" may be understood to mean that the value lies within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise indicated by the context, all numerical values ​​provided herein shall be modified by the term "approximately".

[0019] The above and further tasks, features, and advantages of the present disclosure will become more readily apparent from the following detailed description in conjunction with the accompanying drawings, so that a person skilled in the art to whom the present disclosure applies will be able to implement the technical ideas described herein in a straightforward manner. Furthermore, a detailed description of known techniques related to the present disclosure is omitted in order to avoid unnecessarily obscuring the main point of the present disclosure. Exemplary embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0020] Fig. Figure 1 represents the configuration / arrangement of a device for controlling a fuel cell stack according to an embodiment of the present disclosure. As in Fig. As shown in Figure 1, the device for controlling a fuel cell stack according to the embodiment of the present disclosure can comprise a characteristic curve storage / map storage 10, an outside temperature sensor 20, an open-circuit decay time (ODT) measuring device 30, a fuel cell controller 40, an air blower 50 and a temperature controller 60.

[0021] With respect to each of the aforementioned elements, the characteristic curve memory may initially be set up to store a characteristic curve (hereinafter referred to as the "air-SR characteristic curve") in which a stoichiometric ratio (SR) of the target air of the stack corresponding to an ODT is recorded, a characteristic curve (hereinafter referred to as the "operating temperature characteristic curve") in which a target operating temperature of the stack corresponding to an outside temperature is recorded, and a characteristic curve (hereinafter referred to as the "operating temperature offset characteristic curve") in which a target operating temperature offset of the stack corresponding to an ODT is recorded.

[0022] In this embodiment of the present disclosure, the characteristic curve storage 10 can be provided as a separate module; however, in some embodiments, the fuel cell controller 40 can be configured to include the characteristic curve storage 10. The SR characteristic curve, the operating temperature characteristic curve, and the operating temperature offset characteristic curve are described below with reference to the Fig. Sections 2 to 4 are described in detail.

[0023] Fig. 2 represents an SR characteristic curve according to an embodiment of the present disclosure. As in Fig. Figure 2 shows that if the ODT is less than or equal to ten seconds, it can be determined that the fuel cell stack is suffering from deterioration, and the target air SR of the stack can be increased. Increasing the target air SR of the stack can improve the stack's performance.

[0024] For example, if the ODT is less than or equal to approximately five seconds, the deterioration of the fuel cell stack can be determined to be severe, and the target air SR of the stack can be set to 2.5; if the ODT exceeds five seconds and is less than or equal to approximately ten seconds, the target air SR of the stack can be linearly reduced from 2.5 to 2; and if the ODT exceeds ten seconds, the deterioration of the stack can be determined to be insignificant, and the target air SR of the stack can be set to 2. In particular, ODT reference points (five seconds, ten seconds) for determining the target air SR of the stack, and the corresponding target air SR of the stack, can be modified based on a designer's proposal.

[0025] Fig. Figure 3 represents an operating temperature characteristic curve according to an embodiment of the present disclosure. As in Fig. As shown in Figure 3, according to embodiments of the present disclosure, a target operating temperature of the stack can be set based on the outside temperatures.

[0026] For example, if the outside temperature is approximately -18°C, the target operating temperature of the stack can be set to approximately 65°C; if the outside temperature is approximately -10°C, the target operating temperature of the stack can be set to approximately 63°C; if the outside temperature is approximately 0°C, the target operating temperature of the stack can be set to approximately 62°C; if the outside temperature is approximately 15°C, the target operating temperature of the stack can be set to approximately 60°C; if the outside temperature is approximately 27°C, the target operating temperature of the stack can be set to approximately 58°C; and if the outside temperature is approximately 32°C, the target operating temperature of the stack can be set to approximately 56°C.

[0027] Fig. Figure 4 represents the operating temperature offset characteristic curve according to an embodiment of the present disclosure. As in Fig. As shown in Figure 4, according to embodiments of the present disclosure, if an ODT is less than or equal to approximately ten seconds, it can be determined that the fuel cell stack is suffering from deterioration, and the target operating temperature offset can be set to a negative value. By setting the target operating temperature offset to a negative value (e.g., a negative value) to reduce the target operating temperature and increase the relative humidity, the stack's performance can be improved.

[0028] For example, if the ODT is less than or equal to approximately five seconds, the deterioration of the fuel cell stack can be determined to be severe, and the target operating temperature of the stack can be set to approximately -6.0°C; if the ODT exceeds approximately five seconds and is less than or equal to approximately ten seconds, the target operating temperature of the stack can be increased linearly from approximately -6.0°C to 0°C; and if the ODT exceeds approximately ten seconds, the deterioration of the stack can be determined to be negligible, and the target operating temperature of the stack can be set to approximately 0°C. In particular, ODT reference points (e.g., approximately five seconds, ten seconds) for determining the target operating temperature offset and the corresponding target operating temperature offset can be modified based on a designer's proposal.

[0029] If, meanwhile, the target operating temperature offset is approximately 0°C, the target operating temperature does not necessarily need to be varied. In other words, although the target operating temperature offset of approximately 0°C can be added to the target operating temperature, this yields the target operating temperature. Furthermore, the outside temperature sensor 20 can be configured to detect an outside temperature. The ODT measuring device 30 can be configured to measure the time (hereinafter referred to as "ODT") required for a cell voltage to decrease from a reference voltage (for example, approximately 1V) to a threshold value (for example, approximately 0.75V) when the air supply to the stack is interrupted. The ODT can be used as a criterion for estimating the degree of deterioration of the stack. In particular, the air supply can be interrupted by the fuel cell controller 40.

[0030] The fuel cell controller 40 can be configured to operate the aforementioned respective elements in order to perform their functions in a normal manner. In particular, the fuel cell controller 40 can be configured to detect a target operating temperature of the stack, corresponding to the outside temperature detected by the outside temperature sensor 20, and a target air SR of the stack and a target operating temperature offset of the stack, corresponding to the ODT measured by the ODT measuring device 30, based on the SR characteristic, the operating temperature characteristic, and the operating temperature offset characteristic stored in the characteristic curve memory 10.

[0031] In other words, the fuel cell controller 40 can be configured to determine the target air SR of the stack, which corresponds to the ODT measured by the ODT measuring device 30, based on the SR characteristic curve stored in the characteristic curve memory 10; to determine the target operating temperature of the stack, which corresponds to the outside temperature detected by the outside temperature sensor 20, based on the operating temperature characteristic curve stored in the characteristic curve memory 10; and to determine the target operating temperature offset of the stack, which corresponds to the ODT measured by the ODT measuring device 30, based on the operating temperature offset characteristic curve stored in the characteristic curve memory 10.

[0032] Additionally, the fuel cell controller 40 can be configured to acquire and record an ODT in real time while the vehicle is being driven, using an internal variable "Std_OdtTi". The air blower 50 can be configured to supply air to the fuel cell stack based on the stack's target air supply (A_FC_target) as detected by the fuel cell controller 40. The temperature controller 60 can be configured to set a final target operating temperature for the stack by adding the stack's target operating temperature offset detected by the fuel cell controller 40 to the stack's target operating temperature as detected by the fuel cell controller 40, and to adjust the stack's operating temperature based on the final target operating temperature.In particular, the temperature controller 60 can be configured to receive the final target operating temperature of the stack from the fuel cell controller 40.

[0033] For example, if the target operating temperature of the stack is approximately 60°C and the target operating temperature offset of the stack is approximately -6.0°C, the final target operating temperature of the stack can be set to approximately 54°C.For example, the temperature controller 60 may include a cooler 610 and a fan / radiator fan 611 for dissipating heat from a coolant to the external environment, a coolant line 620 connecting the fuel cell stack and the cooler 610 to allow the coolant to circulate, a bypass line 630 bypassing the cooler 610 to prevent the coolant from flowing through it, a 3-way valve 640 adjusting the amount of coolant flowing through the cooler 610 and the bypass line 630, a pump 650 pumping the coolant from the coolant line 620, a water temperature sensor 660 configured to detect a stack inlet coolant temperature (T_FC), and a valve control 670.

[0034] The 3-way valve 640 can be an electronic valve whose opening is set based on an electrical signal (a control signal) from an external controller. Specifically, the electronic valve can be an electronic thermostat using a wax pellet or an electronic 3-way valve driven by a solenoid or motor, with its opening controlled. The opening control of the 3-way valve 640 can depend on the control signal output by the valve controller 670. The valve controller 670 can receive a stack inlet coolant target temperature (T_FC_Target) and a stack inlet coolant temperature (T_FC) from the fuel cell controller 40 and control the opening of the 3-way valve 640 based on the received values ​​to allow the stack inlet coolant temperature to reach the target value.The stack inlet coolant temperature value can indicate the final target operating temperature of the stack.

[0035] If the opening of the 3-way valve 640 is controlled by the angular rotation of a valve body by the motor, the valve control 670 can be configured to apply a motor control signal to the 3-way valve 640 to set a rotation angle (e.g., an opening angle) of the valve body. If the amount of coolant flowing through the cooler 610 and the bypass line 630 via the 3-way valve 640 is adjusted, the temperature of the coolant supplied to the fuel cell stack, i.e., the stack inlet coolant temperature, can be set, and thus the operating temperature of the fuel cell stack can be set / adjusted.

[0036] Additionally, the stack inlet coolant temperature (T_FC) detected in real time by the water temperature sensor 660 can be input into the fuel cell controller 40, and the fuel cell controller 40 can be configured to receive an outside temperature detection signal from the outside temperature sensor 20. In this embodiment of the present disclosure, the fuel cell controller 40 and the valve controller 670 are provided as separate modules by way of example; however, the fuel cell controller 40 and the valve controller 670 can be provided as a single integrated controller configured to receive output signals from the ODT measuring device 30, the water temperature sensor 660, and the outside temperature sensor 20 in order to calculate the stack inlet coolant temperature setpoint (T_FC_Setpoint) and to directly operate and adjust the 3-way valve 640.In particular, the stack inlet coolant temperature setpoint (T_FC_Setpoint) can be used to set the opening of the 3-way valve 640, and the opening of the 3-way valve 640 can be set based on the setpoint and the stack inlet coolant temperature value (T_FC) detected by the water temperature sensor 660.

[0037] Fig. Section 5 presents the analysis of the performance of a fuel cell stack controlled by a new method according to an embodiment of the present disclosure. Fig. 5 denotes “510” the power output of a fuel cell stack controlled by a conventional method, and “520” denotes the power output of a fuel cell stack controlled by a novel method according to an embodiment of the present disclosure. As in Fig. As can be seen in Figure 5, the fuel cell stack 520 controlled by the new method according to the embodiment of the present disclosure outputs a higher voltage at the same current than the fuel cell stack 510 controlled by the conventional method. In other words, it shows Fig. 5, that the performance of the fuel cell stack 520, which was controlled by the new method according to the embodiment of the present disclosure, showed a significant improvement compared to the conventional method.

[0038] Specifically, when the target operating temperature of the stack was reduced by approximately 6°C and the target air SR was increased by approximately 0.2 compared to corresponding conditions of the conventional process, the following results were obtained: the operating temperature of the stack was reduced by approximately 5.94°C, the air SR of the stack was increased by approximately 0.08, the relative humidity was increased by approximately 8.29%, and fuel efficiency was increased by approximately 1.4%. In particular, the conditions of the conventional process state that the target operating temperature of the stack was not reduced by 6°C and the target air SR was not increased by 0.2.

[0039] Fig. Section 6 presents the analysis of the performance of a fuel cell stack controlled by a new method according to a further embodiment of the present disclosure. Fig. 6 “610” denotes the power output of a fuel cell stack controlled by a conventional method, and “620” denotes the power output of a fuel cell stack controlled by a new method according to an embodiment of the present disclosure. As in Fig. As can be seen in Figure 6, the fuel cell stack 620 controlled by the new method according to the embodiment of the present disclosure outputs a higher voltage at the same current than the fuel cell stack 610 controlled by the conventional method. In other words, it shows Fig. 6, that the performance of the fuel cell stack 620, which was controlled by the new method according to the embodiment of the present disclosure, showed a significant improvement compared to the conventional method.

[0040] In particular, when, compared to the corresponding conditions of the conventional process, the target operating temperature of the stack was reduced by approximately 6°C and the target air SR was increased by approximately 0.2, the following results were obtained compared with the results of the conventional process: the operating temperature of the stack was reduced by approximately 8.22°C, the air SR of the stack was increased by approximately 1.2, the relative humidity was increased by approximately 10.48%, and the fuel efficiency was increased by approximately 2.3%. Under the same conditions, the reason why the in Fig. 5 experimental results shown and those in Fig. The experimental results shown in the 6 exhibit different results from each other, such that the degree of deterioration of the condition in the experiment of Fig. 5 fuel cell stacks used and the degree of deterioration of the one used in the experiment of Fig. 6 fuel cell stacks used differ from each other.

[0041] Fig. Figure 7 presents a flowchart of a method for controlling a fuel cell stack according to an embodiment of the present disclosure. Initially, the characteristic curve storage unit 10 can be configured to store, in process 701, an SR characteristic curve in which a target air SR corresponding to an ODT is recorded, an operating temperature characteristic curve in which a target operating temperature of the stack corresponding to an outside temperature is recorded, and an operating temperature offset characteristic curve in which an operating temperature offset of the stack corresponding to an ODT is recorded.

[0042] Furthermore, the outdoor temperature sensor 20 can be configured to detect an outdoor temperature in step 702. The fuel cell controller 40 can be configured to detect a target operating temperature of the stack, corresponding to the outdoor temperature measured by the outdoor temperature sensor 20, based on the operating temperature characteristic in step 703. Then, the ODT measuring device 30 can be configured in step 704 to measure the time (ODT) required for a cell voltage to decrease from a reference voltage to a threshold voltage when the air supply to the stack is interrupted.

[0043] The fuel cell controller 40 can then be configured to determine a target air SR of the stack and a target operating temperature offset of the stack, corresponding to an ODT measured by the ODT measuring device 30, based on the SR characteristic and the operating temperature offset characteristic in step 705. The air blower 50 can then be configured to supply air to the stack based on the target air SR of the stack in step 706. The temperature controller 60 can then be configured in step 707 to set a final target operating temperature by adding the target operating temperature offset to the target operating temperature of the stack and to set an operating temperature of the stack based on the final target operating temperature.

[0044] Meanwhile, the method described above can be written as a computer program according to the embodiment of the present disclosure. The codes and code segments forming the program can be easily derived by a programmer / expert. Furthermore, the written program can be stored on a non-volatile, computer-readable medium (an information storage medium) and read and executed by a computer, thereby implementing / realizing the method according to the embodiment of the present disclosure. The recording medium includes all types of computer-readable recording media.

[0045] As explained above, the device and method for controlling a fuel cell stack can improve the performance (output power) of the fuel cell stack, which has suffered from degradation, by setting / adjusting a stoichiometric ratio (SR) of the air supplied to the fuel cell stack and an operating temperature of the fuel cell stack based on an open-circuit decay time (ODT), which is the time required for a cell voltage to decrease from a reference voltage (for example, approximately 1 V) to a threshold voltage (for example, approximately 0.75 V) when the air supply to the fuel cell stack is interrupted / disconnected. Additionally, applying the present inventive concept to a fuel cell vehicle can improve the fuel cell vehicle's fuel efficiency. REFERENCE MARK OF EACH OF THE ELEMENTS IN THE FIGURES 10 PERFORMANCE CURVE MEMORY 20 Outdoor temperature sensor 30 ODT measuring device 40 FUEL CELL CONTROL 50 air blowers 610 COOLERS 640 3-WAY VALVE 670 VALVE CONTROL 701 SAVE AIR-SR CHARACTERISTIC CURVE, OPERATING TEMPERATURE CHARACTERISTIC CURVE AND OPERATING TEMPERATURE OFFSET CHARACTERISTIC CURVE 702 DETECT OUTSIDE TEMPERATURE 703 Determine the target operating temperature of the stack corresponding to the outside temperature, based on the operating temperature characteristic curve 704 ODT MEASURES 705 Determine the target air temperature and the corresponding ODT target operating temperature offset of the stack based on the air temperature characteristic curve and the operating temperature offset characteristic curve. 706 Supply air to the fuel cell stack based on the stack's target air supply. 707 FINAL SET OPERATING TEMPERATURE BY ADDING THE FINAL OPERATIONAL TEMPERATURE OFFSET TO THE FINAL OPERATIONAL TEMPERATURE OF THE STACK AND CONTROL THE STACK OPERATING TEMPERATURE BASED ON THE FINAL OPERATING TEMPERATURE

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