Fuel cell system and control method thereof

Abstract

The present invention relates to a fuel cell system and a control method thereof. A fuel cell system includes a fuel cell stack, which includes a fuel electrode and an air electrode; a fuel gas supply module, which is configured to supply hydrogen and oxygen as fuel gas to the fuel cell stack; a fuel gas supply pipeline, which includes a channel, through which the fuel gas is supplied to the fuel cell stack; a humidification module, which is arranged in the fuel gas supply pipeline and is configured to supply moisture to the fuel gas; and a controller, which is configured to control the fuel gas supply pipeline so that when it is determined that the temperature of the fuel cell stack is low in the initial stage of the operation of the fuel cell stack, the fuel gas bypasses the humidification module and is directly supplied to the fuel cell stack, and when the temperature reaches a normal temperature, the fuel gas passes through the humidification module and is supplied to the fuel cell stack.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system and a control method thereof, and more particularly, to a fuel cell system and a control method thereof, wherein in an initial stage of operation of a fuel cell stack, the fuel cell system injects dry gas into the fuel cell stack to make the fuel cell stack operate in a low output mode in order to prevent freezing when the temperature of the fuel cell stack is low, and after the temperature of the fuel cell stack rises to a normal temperature, injects humidified gas into the fuel cell stack to make the fuel cell stack operate in a normal output mode. Background Art

[0002] When used as a fuel, hydrogen does not produce any environmentally harmful products except very small amounts of nitrogen oxides, and is easily stored in various forms, such as high pressure gas, liquefied gas, or metal hydrides. For these reasons, technologies using hydrogen as an energy source have been developed in various fields.

[0003] A fuel cell is a device that supplies hydrogen as a fuel and generates electricity by electrochemically reacting with oxygen in the atmosphere. Such a fuel cell has the following advantages: there is no separate combustion process, so the power production efficiency is high; no greenhouse gases (such as carbon dioxide) are emitted, so the fuel cell is environmentally friendly; and heat is generated while generating electricity, thereby obtaining thermal energy. Small fuel cells are used as power sources or mobile power sources for vehicles, while large fuel cells are used as distributed batteries for buildings or batteries for power generation.

[0004] When the fuel cell stack is operated in a high output mode at sub-zero temperatures, water in the fuel cell stack freezes, thereby damaging the fuel cell stack and thus degrading the performance of the fuel cell stack while reducing the life of the fuel cell stack. Even for fuel cells used for power generation and in the case of using the fuel cell stack as a power source for a vehicle, there is still a problem of freezing occurring in a low temperature state where water is frozen.

[0005] Generally, a method is used to provide a separate heat sink to directly increase the temperature of the fuel cell stack or the temperature of the coolant so that the coolant exchanges heat with the fuel cell stack to prevent the fuel cell stack from freezing. However, in this method, a heat sink needs to be installed, and power is required to operate the heat sink. Therefore, in the conventional method, there are problems such as an increase in system installation cost and a decrease in efficiency of the fuel cell system in a low temperature state where freezing occurs.

[0006] The information disclosed in the Background section above is to assist in understanding the background of the present disclosure and should not be regarded as an admission that this information forms any part of the prior art. Summary of the invention

[0007] The present disclosure is made in view of the above-mentioned problems, and an object of the present disclosure is to provide a fuel cell system and a control method thereof. When it is determined that the temperature of the fuel cell stack is low, dry gas is injected into the fuel cell stack in the initial stage of the operation of the fuel cell stack so that the fuel cell stack operates in a low output mode and the temperature of the fuel cell stack is increased; and when the temperature of the fuel cell stack reaches a normal temperature, humidified gas is injected into the fuel cell stack so that the fuel cell stack operates in a normal output mode, thereby preventing damage to the fuel cell stack.

[0008] According to one aspect of the present disclosure, to achieve the above and other purposes, a fuel cell system may include: a fuel cell stack, which includes a fuel electrode and an air electrode; a fuel gas supply module, which is configured to supply hydrogen and oxygen as fuel gas to the fuel cell stack; a fuel gas supply pipeline, which includes a channel, and the fuel gas is supplied to the fuel cell stack through the channel; a humidification module, which is arranged in the fuel gas supply pipeline, the humidification module is configured to supply moisture (moisture, water vapor, moisture) to the fuel gas to humidify the fuel gas; and a controller, which is configured to control the fuel gas supply pipeline, so that when it is determined that the temperature of the fuel cell stack is low in the initial stage of the operation of the fuel cell stack, the fuel gas bypasses the humidification module and is directly supplied to the fuel cell stack, and when the temperature of the fuel cell stack reaches a normal temperature, the fuel gas passes through the humidification module and is then supplied to the fuel cell stack.

[0009] The controller can control the discharge amount of various fuel gases discharged from the fuel gas supply module, and can control the discharge amount of various fuel gases to be the rated operation amount or less when it is determined that the temperature of the fuel cell stack is low, and can control the discharge amount of various fuel gases to be the rated operation amount when the temperature of the fuel cell stack reaches a normal temperature.

[0010] The controller may control such that the operation of the humidification module is stopped when it is determined that the temperature of the fuel cell stack is low, and such that the humidification module is operated when the temperature of the fuel cell stack reaches a normal temperature.

[0011] The fuel cell system may further include a cooling module including a storage tank configured to circulate the first coolant to exchange heat with the fuel cell stack.

[0012] The cooling module may further include: a coolant tank configured to circulate the second coolant; and a heat exchanger disposed between the storage tank and the coolant tank to allow the first coolant and the second coolant to exchange heat with each other.

[0013] Furthermore, upon determining that the temperature of the first coolant is the cooling temperature or higher, the controller may control such that the coolant tank operates.

[0014] In the case where the voltage of the fuel cell stack is a reference value or higher, the controller may determine that the temperature of the fuel cell stack is a normal temperature.

[0015] The fuel cell system may further include a temperature sensor configured to measure a temperature of the fuel cell stack, wherein the controller may determine whether the temperature of the fuel cell stack is a low temperature or a normal temperature based on a value measured by the temperature sensor.

[0016] In addition, the fuel gas supply module may include a hydrogen supply system configured to supply hydrogen to the fuel cell stack and an air supply system configured to supply air including oxygen to the fuel cell stack, and the fuel gas supply pipeline may include: a hydrogen supply line, which is connected to the hydrogen supply system and to the fuel cell stack, and the hydrogen supply line is configured to supply hydrogen humidified when passing through the humidification module to the fuel electrode; an air supply line, which is connected to the air supply system and to the fuel cell stack, and the air supply line is configured to supply air humidified when passing through the humidification module to the air electrode; a first bypass line, which branches off from a point of the hydrogen supply line before the humidification module, and the first bypass line is configured to bypass the humidification module and supply hydrogen directly to the fuel electrode; and a second bypass line, which branches off from a point of the air supply line before the humidification module, and the second bypass line is configured to bypass the humidification module and supply air directly to the air electrode.

[0017] The fuel cell system may further include a control valve disposed in the fuel gas supply line, the control valve being configured to control a passage of the fuel gas supply line, wherein the controller may control the control valve so as to control the passage.

[0018] The control valve may include a first control valve located at a junction point between the hydrogen supply line and the first bypass line and a second control valve located at a junction point between the air supply line and the second bypass line, and the controller may control the first control valve and the second control valve so that hydrogen and oxygen selectively pass through the humidification module.

[0019] When it is determined that the temperature of the fuel cell stack is low, the controller may control such that the amount of each fuel gas supplied to the fuel cell stack is smaller than the amount of each fuel gas when the temperature of the fuel cell stack is determined to be a normal temperature.

[0020] According to another aspect of the present disclosure, a control method for a fuel cell system may include: measuring the temperature of a fuel cell stack and determining whether the temperature of the fuel cell stack is low; when it is determined that the temperature of the fuel cell stack is a normal temperature in an initial stage of operation of the fuel cell stack, supplying humidified gas to the fuel cell stack so that the fuel cell stack operates in a normal output mode, and when it is determined that the temperature of the fuel cell stack is low, supplying dry gas so that the fuel cell stack operates in a low output mode; and measuring the temperature of the fuel cell stack when the fuel cell stack operates in the low output mode, and supplying humidified gas when it is determined that the temperature of the fuel cell stack reaches a normal temperature so that the fuel cell stack operates in the normal output mode.

[0021] When the fuel cell stack operates in the low output mode, in the case where the voltage of the fuel cell stack is a reference value or higher, the controller may determine that the temperature of the fuel cell stack is a normal temperature and may control such that the fuel cell stack operates in the normal output mode.

[0022] Furthermore, when the fuel cell stack operates in the low output mode, the controller may control such that the amount of each fuel gas supplied to the fuel cell stack is smaller than the amount of each fuel gas supplied when the fuel cell stack operates in the normal output mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and other advantages of the present disclosure will be more clearly understood through the following detailed description in conjunction with the accompanying drawings, in which:

[0024] Figure 1 is a diagram showing a configuration of a fuel cell system according to one embodiment of the present disclosure; and

[0025] Figure 2 is a flowchart illustrating a control method according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] The specific structural or functional description of the embodiments of the present disclosure disclosed in this specification or this disclosure is only used to illustrate the embodiments of the present disclosure. The embodiments of the present disclosure can be implemented in various forms and should not be interpreted as being limited to the embodiments of the present disclosure disclosed in this specification or this disclosure.

[0027] Since the embodiments of the present disclosure can be subjected to various modifications and can have various forms, the specific embodiments will be shown in the drawings and will be described in detail in this specification or the present disclosure. However, the embodiments according to the concepts of the present disclosure are not limited to such specific embodiments, and it should be understood that the present disclosure includes all changes, equivalents and substitutions falling within the conceptual and technical scope of the present disclosure.

[0028] It will be understood that, although the terms "first", "second", etc. may be used to describe various elements herein, the corresponding elements should not be understood to be limited by these terms, which are only used to distinguish one element from another element. For example, within the scope defined in the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0029] Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0030] In the fuel cell system, hydrogen gas supplied to the fuel electrode 110 of the fuel cell stack 100 is separated into hydrogen ions and electrons, the hydrogen ions move to the air electrode 120 through the electrolyte layer, and the electrons move to the air electrode 120 through the external circuit, thereby generating electricity, water and heat. Oxygen contained in the air supplied to the air electrode 120 of the fuel cell stack 100 contacts the hydrogen ions, thereby generating water as a reaction product. The reactions occurring at the fuel electrode 110 and the air electrode 120 and the entire reaction are represented by the following reaction formula.

[0031] [Reaction formula at the fuel electrode 110] H 2 →2H + +2e -

[0032] [Reaction formula at air electrode 120] 1 / 2O 2 +2H + +2e - →H 2 O

[0033] [Entire reaction formula] H 2 +1 / 2O 2 →H 2 O

[0034] Meanwhile, hydrogen ions must pass through the electrolyte layer, and the permeability of hydrogen is set according to the water content. Therefore, in order to improve the permeability of hydrogen, a humidification module 300 configured to supply moisture to hydrogen gas and air supplied to the fuel cell stack 100 is provided.

[0035] The humidification module 300 is used to supply appropriate moisture to the hydrogen and air supplied to the fuel cell stack 100 in order to maintain the ionic conductivity of the electrolyte layer. Specifically, as the output load increases, the ionic conductivity of the electrolyte layer is more affected by the amount of humidification. Therefore, the amount of humidification is very important for the water balance of the fuel cell system.

[0036] With reference to the entire reaction formula, water is generated. In addition, moisture is supplied to the reactants. Therefore, in the case where the fuel cell system is operated at a temperature at which water can freeze, water molecules can be frozen. Specifically, for vehicles using hydrogen as fuel, there is a high possibility of a freezing phenomenon occurring because the fuel cell system is easily exposed to sub-zero temperatures. Even in a fuel cell for power generation, in the case where the system is operated in a sub-zero temperature environment, a freezing phenomenon may occur. In the case where water molecules are frozen, the flow of gases and products in the system is disturbed, so that the fuel cell stack 100 may be damaged.

[0037] With the conventional fuel cell system, a method of further installing a separate heat source to sufficiently increase the temperature of the fuel cell stack 100 and operating the fuel cell system to prevent damage due to freezing is used to prevent the freezing phenomenon.

[0038] In conventional fuel cell systems, a method of installing a heat sink such as a heater outside the fuel cell stack 100 to increase the temperature of the fuel cell stack 100 and a method of using the heat sink to increase the temperature of the coolant and allow the coolant to flow into the fuel cell stack 100 are used.

[0039] The above method requires installation of a separate heat sink, thereby increasing installation costs, and furthermore consuming electricity in order to operate the heat sink, so that electricity production costs increase, and thus electricity production efficiency decreases.

[0040] The present disclosure provides a fuel cell system and a control method thereof, which supplies dry gas to operate a fuel cell stack 100 in an initial stage of operation, and reduces the output load to operate the system in a low output mode to prevent water from freezing when the ambient temperature is a temperature at which freezing may occur, so that the system operates stably without a separate heat dissipation device.

[0041] Figure 1 is a diagram showing the configuration of a fuel cell system according to one embodiment of the present disclosure. Figure 1 , a fuel cell system according to an embodiment of the present disclosure may include a fuel cell stack 100 , a fuel gas supply module 200 , a fuel gas supply line 400 , a humidification module 300 , and a controller 600 .

[0042] The fuel cell stack 100 is a device that receives hydrogen and air to generate electricity and heat. The fuel cell stack 100 may include a plurality of cells configured to generate electricity. The fuel cell stack 100 includes a fuel electrode 110 and an air electrode 120, wherein the reactions occurring at the fuel electrode 110 and the air electrode 120 are represented by the above reaction formula.

[0043] The fuel gas supply module 200 is a device that supplies hydrogen and oxygen to the fuel cell stack 100. The fuel gas supply module 200 may include a hydrogen supply system 210 configured to supply hydrogen to the fuel cell stack 100 and an air supply system 220 configured to supply air including oxygen to the fuel cell stack 100. For example, the hydrogen supply system 210 may include a storage, a compressor, a pump, a gas channel, a valve, etc. for hydrogen, and the structure of the hydrogen supply system 210 may be a hydrogen supply system in a general fuel cell system known in the art.

[0044] In this specification, hydrogen and oxygen, which are reactants configured to generate electric energy and heat energy in the fuel cell stack 100, are defined as fuel gases. For oxygen, air in the atmosphere is supplied to the fuel cell stack 100 instead of pure oxygen, and oxygen included in the air is used as a reactant. Pure oxygen can improve the efficiency of the fuel cell system, but the weight and cost associated with oxygen storage may increase. Therefore, since a large amount of oxygen is included in the air, air is supplied.

[0045] The fuel gas supply line 400 may include a passage along which the fuel gas exhausted from the fuel gas supply module 200 is introduced into the fuel cell stack 100. The fuel gas supply line 400 may be connected to the fuel gas supply module 200 and to the fuel cell stack 100 so that the fuel gas is supplied to the fuel cell stack 100 along it.

[0046] The humidification module 300 is a device arranged in the fuel gas supply line 400 to supply moisture to the fuel gas so that the fuel gas is humidified. The polymer membrane used as the electrolyte of the fuel cell stack 100 must always be hydrated (hydrated, containing water) in order to maintain the conductivity of the hydrogen ions. In the case of drying the polymer membrane during the operation of the fuel cell stack 100, the conductivity of the hydrogen ions decreases, and due to the shrinkage of the membrane, the various electrodes are separated from the membrane, so that the contact resistance between the various electrodes and the membrane increases. The humidification module 300 is used to supply moisture to various fuel gases so that the humidified gas is supplied to the fuel cell stack 100.

[0047] The controller 600 is a device that controls the fuel gas supply module 200 to control the flow rate of various fuel gases and controls the fuel gas supply line 400 to control the fuel gas passage. The controller 600 can control the flow rate of various fuel gases and the fuel gas passage according to whether the temperature of the fuel cell stack 100 is low.

[0048] The controller 600 of the fuel cell system according to an exemplary embodiment of the present disclosure may be a processor (e.g., a computer, a microprocessor, a CPU, an ASIC, a circuit, a logic circuit, etc.). The controller 600 may be implemented by a non-transitory memory (e.g., a program, a software instruction reproduction algorithm, etc.) and a processor, which controls the operation of various components of the fuel cell system when executed, and the processor is configured to execute the program, the software instruction reproduction algorithm, etc. Herein, the memory and the processor may be implemented as separate semiconductor circuits. Alternatively, the memory and the processor may be implemented as a single integrated semiconductor circuit. The processor may be implemented as one or more processors.

[0049] When the temperature of the fuel cell stack 100 is determined to be low in the initial stage of operation of the fuel cell stack 100, the controller 600 may control the fuel gas to bypass the humidification module 300 and then be directly supplied to the fuel cell stack 100. Low temperature refers to a temperature when the ambient temperature around the system is below zero or water may be frozen.

[0050] In the case where the temperature of the fuel cell stack 100 is low, water generated in the fuel cell stack 100 or moisture contained in the fuel gas may be frozen. In the initial stage of the operation of the fuel cell stack 100, the temperature of the fuel cell stack 100 has not yet risen. Therefore, when the rated operation or high-output operation is immediately performed, the fuel cell stack 100 may be damaged. Therefore, these channels are controlled so that the fuel gas is supplied in a non-humidified state, that is, dry gas is supplied.

[0051] Since the reaction occurring in the fuel cell stack 100 is exothermic, the temperature of the fuel cell stack 100 increases. When the temperature of the fuel cell stack 100 reaches the normal temperature, the controller 600 may control the fuel gas supply line 400 so that the fuel gas passes through the humidification module 300 and is then supplied to the fuel cell stack 100. That is, when the temperature of the fuel cell stack 100 reaches the normal temperature, the controller 600 controls the passage so that the humidified gas is supplied.

[0052] In addition, the controller 600 may control the amount of various fuel gases supplied from the fuel gas supply module 200 to the fuel cell stack 100. When it is determined that the temperature of the fuel cell stack 100 is low, the controller 600 may control so that the amount of each fuel gas supplied is a rated operating amount or less, and thus a small amount of each fuel gas is introduced into the fuel cell stack 100.

[0053] Operating the fuel cell stack 100 in the low output mode gradually increases the temperature of the fuel cell stack 100, and when the temperature of the fuel cell stack 100 reaches a normal temperature, the controller 600 may control so that the amount of each fuel gas supplied is a rated operation amount. In the case where the rated operation amount of each humidified fuel gas is supplied to perform a rated operation in a state where the temperature of the fuel cell stack 100 is low, the fuel cell stack 100 may be damaged. Therefore, before the temperature of the fuel cell stack 100 is sufficiently increased, a small amount of each dry fuel gas is introduced to perform control in order to perform the low output mode.

[0054] At low temperatures, a small amount of various dry gases is supplied to operate the fuel cell stack 100 under the control of the controller 600, and the operation is defined as operation in the low output mode. At normal temperatures, rated operating amounts of various humidified fuel gases are supplied to operate the fuel cell stack 100, and the operation is defined as operation in the normal output mode.

[0055] In the case where the temperature of the fuel cell stack 100 is low, the controller 600 controls so that in the low output mode, the temperature of the fuel cell stack 100 increases without causing damage thereto, and operates the fuel cell stack 100 in the normal output mode, thereby being able to generate electrical energy and thermal energy without a separate heat dissipation device. Therefore, the power production efficiency is improved, the manufacturing cost is reduced, and the overall configuration of the system is simplified.

[0056] In addition, when it is determined that the temperature of the fuel cell stack 100 is low, the controller 600 may control so as to stop the operation of the humidification module 300. Since the fuel gas bypasses the humidification module 300 and is then supplied to the fuel cell stack 100 in the low output mode, it is not necessary to operate the humidification module 300. Therefore, control is performed so that the humidification module 300 is not operated in the low output mode in order to efficiently operate the system. When the temperature of the fuel cell stack 100 rises to a normal temperature in the low output mode, the controller 600 may control so as to operate the humidification module 300. In the normal output mode, the fuel gas passes through the humidification module 300 and the humidified gas is supplied to the fuel cell stack 100.

[0057] refer to Figure 1The fuel cell system according to an embodiment of the present disclosure may further include a cooling module 700 including a storage tank 710 , a coolant tank 720 , and a heat exchanger 730 .

[0058] The storage tank 710 is a device for circulating a first coolant configured to exchange heat with the fuel cell stack 100. The first coolant may be introduced from the storage tank 710 into the fuel cell stack 100, may exchange heat with the fuel cell stack 100, and may be introduced into the storage tank 710. In this way, the first coolant may circulate. As the temperature of the fuel cell stack 100 increases during its operation, the temperature of the first coolant gradually increases.

[0059] The coolant tank 720 is a device for circulating a second coolant configured to exchange heat with the first coolant. The heat exchanger 730 is arranged between the coolant tank 720 and the storage tank 710, and the first coolant and the second coolant can exchange heat with each other in the heat exchanger 730. That is, the first coolant in the storage tank 710 can exchange heat with the fuel cell stack 100 to directly cool the fuel cell stack 100, and the second coolant in the coolant tank 720 can exchange heat with the first coolant to indirectly cool the fuel cell stack 100.

[0060] In the case of operating the fuel cell stack 100 using dry gas in low output mode, the temperature of the first coolant will not rise to the extent that cooling is required. In this case, the operation of the coolant tank 720 is not required, and the temperature of the first coolant will not rise to the cooling temperature or higher that requires cooling. As the temperature of the fuel cell stack 100 continues to rise, the temperature of the first coolant that performs heat exchange with the fuel cell stack 100 also gradually increases. Therefore, when the temperature of the first coolant is the cooling temperature or lower, the controller 600 can control so that the coolant tank 720 is not operated, and when it is determined that the temperature of the first coolant has risen and is therefore the cooling temperature or higher, the controller 600 can control so that the coolant tank 720 is operated. Therefore, the system can be operated at optimal efficiency.

[0061] In addition, in the fuel cell system according to the embodiment of the present disclosure, it can be determined whether to operate the fuel cell stack 100 in the low output mode or in the normal output mode based on the voltage of the fuel cell stack 100. The controller 600 can compare the voltage generated by the fuel cell stack 100 with a predetermined reference value, and when the generated voltage is the reference value or higher, the controller can determine that the temperature of the fuel cell stack 100 is a normal temperature, and can control the fuel cell stack 100 to operate in the normal output mode. For example, when the reference value is set to 0.4V and the measured voltage is lower than 0.4V, the controller 600 can determine that the temperature of the fuel cell stack 100 is low and can control the fuel cell stack 100 to operate in the low output mode. When the measured voltage is 0.4V or higher, the controller 600 can determine that the temperature of the fuel cell stack 100 is a normal temperature, and can control the fuel cell stack 100 to operate in the normal output mode. In this case, even if a separate temperature sensor is not provided, the timing of the humidified gas to be supplied can be determined.

[0062] The fuel cell system according to an embodiment of the present disclosure may further include a temperature sensor (not shown). The temperature sensor may perform a function of measuring the temperature of the fuel cell stack 100. The controller 600 may determine whether the temperature of the fuel cell stack 100 is low temperature or normal temperature based on the value measured by the temperature sensor.

[0063] refer to Figure 1 , the fuel gas supply line 400 may include a hydrogen supply line 410 , an air supply line 420 , a first bypass line 411 , and a second bypass line 421 .

[0064] The hydrogen supply line 410 is connected to the hydrogen supply system 210 and to the fuel electrode 110 of the fuel cell stack 100, and is configured to extend through the humidification module 300. The hydrogen exhausted from the hydrogen supply system 210 passes through the humidification module 300 while flowing along the hydrogen supply line 410. At this time, moisture may be supplied to the hydrogen, and the humidified hydrogen may be introduced into the fuel electrode 110.

[0065] The air supply line 420 is connected to the air supply system 220 and to the air electrode 120 of the fuel cell stack 100, and is configured to extend through the humidification module 300. The air including oxygen exhausted from the air supply system 220 passes through the humidification module 300 while flowing along the air supply line 420. At this time, moisture may be supplied to the air, and the humidified air may be introduced into the air electrode 120.

[0066] The first bypass line 411 may branch from a point of the hydrogen supply line 410 before the humidification module 300, may bypass the humidification module 300, and may be connected to the fuel cell stack 100. In the case where hydrogen flows in the first bypass line 411, the hydrogen may bypass the humidification module 300 and may be directly supplied to the fuel electrode 110.

[0067] The second bypass line 421 may branch from a point of the air supply line 420 before the humidification module 300, may bypass the humidification module 300, and may be connected to the fuel cell stack 100. In the case where air including oxygen flows in the second bypass line 421, the air may bypass the humidification module 300 and may be directly supplied to the air electrode 120.

[0068] The controller 600 may control so that the fuel gas flows in the first bypass line 411 and the second bypass line 421 in the low output mode, and so that the fuel gas flows in the hydrogen supply line 410 and the air supply line 420 in the normal output mode.

[0069] In addition, the fuel cell system according to the embodiment of the present disclosure may further include a control valve 500 disposed in the fuel gas supply line 400 to control the fuel gas passage. Under the control of the controller 600, the control valve 500 may change the fuel gas passage according to the output mode.

[0070] The control valve 500 may include a first control valve 510 and a second control valve 520. The first control valve 510 may be located at a junction between the hydrogen supply line 410 and the first bypass line 411 to control a hydrogen passage.

[0071] The second control valve 520 may be located at a junction between the air supply line 420 and the second bypass line 421 to control an air passage. The controller 600 may control the first control valve 510 and the second control valve 520 so that hydrogen and oxygen selectively pass through the humidification module 300, and thus introduce dry gas or humidified gas into the fuel cell stack 100. Dry gas is supplied in the low output mode, and humidified gas is supplied in the normal output mode.

[0072] Since the fuel gas passage is controlled by the control valve 500 in the low output mode and the normal output mode, the control valve has a simple configuration, and thus the supply of dry gas and humidified gas can be easily controlled. Specifically, in the case where the passage is controlled by the control valve 500, the controller 600 can also control the operation of the humidification module 300. The controller 600 can control so that the humidification module 300 is not operated when the fuel gas bypasses the humidification module 300, thereby improving the efficiency of the system.

[0073] Figure 2is a flowchart showing a control method of a fuel cell system according to an embodiment of the present disclosure. Figure 2 A control method of a fuel cell system according to an embodiment of the present disclosure is described.

[0074] When the fuel cell stack 100 is first operated, the temperature of the fuel cell stack 100 is measured, and whether the temperature of the fuel cell stack 100 is low is determined based on the measured temperature (S100). For example, when the measured temperature is lower than a preset temperature, it can be determined that the temperature of the fuel cell stack 100 is low.

[0075] When it is determined that the temperature of the fuel cell stack 100 is a normal temperature, the humidification module 300 is operated to humidify the fuel gas, the humidified gas is supplied to the fuel cell stack 100 (S500), and the fuel cell stack 100 is operated in a normal output mode (S600). For example, when the measured temperature is at a preset temperature or higher, the temperature of the fuel cell stack 100 can be determined to be a normal temperature.

[0076] When it is determined that the temperature of the fuel cell stack 100 is low, the fuel gas bypasses the humidification module 300 and thus the dry gas is supplied to the fuel cell stack 100 (S200), and the fuel cell stack 100 is operated in the low output mode (S300). The temperature of the fuel cell stack 100 is measured, and it is determined whether the temperature of the fuel cell stack 100 is a normal temperature (S400). In the case where the temperature of the fuel cell stack 100 is not a normal temperature, the dry gas is continuously supplied to the fuel cell stack 100 (S200). When the temperature of the fuel cell stack 100 reaches the normal temperature, the humidified gas is supplied to the fuel cell stack 100 (S500), and the fuel cell stack 100 is operated in the normal output mode (S600).

[0077] Further, when the fuel cell stack 100 is operated in a low output mode, the controller 600 can measure the voltage of the fuel cell stack 100, and when the voltage is a reference value or higher, it can be determined that the temperature of the fuel cell stack 100 is a normal temperature, and humidified gas can be supplied so that the fuel cell stack 100 is operated in a normal output mode.

[0078] In the fuel cell system and the control method thereof according to the present disclosure, even in the case where a separate heat dissipation device is not provided, the system can be operated without damaging the fuel cell stack 100 .

[0079] As is apparent from the above description, in the fuel cell system according to the present disclosure, the fuel cell stack operates in a low output mode at low temperature and operates in a normal output mode after the temperature of the fuel cell stack is sufficiently increased, thereby being able to prevent damage to the fuel cell stack.

[0080] In addition, there is no need to install a separate heat sink to prevent freezing, thereby reducing the installation cost of the system and simplifying the construction of the system. In addition, the power consumption required to operate the heater is eliminated, thereby improving the efficiency of the system.

[0081] Although the preferred embodiments of the present disclosure have been described above with reference to the accompanying drawings, it will be understood by those skilled in the art that the present disclosure can be implemented in various other embodiments without changing the technical concept or features of the present disclosure.

Claims

1. A fuel cell system, comprising: A fuel cell stack, the fuel cell stack comprising a fuel electrode and an air electrode; a fuel gas supply module configured to supply hydrogen and oxygen as fuel gas to the fuel cell stack; a fuel gas supply line, the fuel gas supply line comprising a channel through which the fuel gas is supplied to the fuel cell stack; a humidification module disposed in the fuel gas supply line, the humidification module being configured to supply moisture to the fuel gas so as to humidify the fuel gas; as well as a controller configured to control the fuel gas supply line so that: When it is determined that the temperature of the fuel cell stack is low in an initial stage of operation of the fuel cell stack, the fuel gas bypasses the humidification module and is then directly supplied to the fuel cell stack, and When the temperature of the fuel cell stack reaches a normal temperature, the fuel gas passes through the humidification module and is then supplied to the fuel cell stack. Wherein, in a case where the voltage of the fuel cell stack is a reference value or higher, the controller is further configured to determine that the temperature of the fuel cell stack is a normal temperature.

2. The fuel cell system according to claim 1, wherein: The controller is further configured to: control the discharge amount of various fuel gases discharged from the fuel gas supply module, control the discharge amount of various fuel gases to be the rated operating amount or less when it is determined that the temperature of the fuel cell stack is low, and control the discharge amount of various fuel gases to be the rated operating amount when the temperature of the fuel cell stack reaches a normal temperature.

3. The fuel cell system according to claim 1, wherein: The controller is further configured to perform control such that the operation of the humidification module is stopped when it is determined that the temperature of the fuel cell stack is low, and such that the humidification module is operated when the temperature of the fuel cell stack reaches a normal temperature.

4. The fuel cell system according to claim 1, further comprising: A cooling module includes a storage tank configured to circulate a first coolant to exchange heat with the fuel cell stack.

5. The fuel cell system according to claim 4, wherein: The cooling module further includes a coolant tank configured to circulate a second coolant, and a heat exchanger disposed between the storage tank and the coolant tank to allow the first coolant and the second coolant to exchange heat with each other.

6. The fuel cell system according to claim 5, wherein: The controller is further configured to perform control such that the coolant tank is operated when it is determined that the temperature of the first coolant is a cooling temperature or higher.

7. The fuel cell system according to claim 1, further comprising: a temperature sensor configured to measure the temperature of the fuel cell stack, wherein: The controller is further configured to determine whether the temperature of the fuel cell stack is a low temperature or a normal temperature based on a value measured by the temperature sensor.

8. The fuel cell system according to claim 1, wherein: The fuel gas supply module includes a hydrogen supply system configured to supply hydrogen to the fuel cell stack and an air supply system configured to supply air including oxygen to the fuel cell stack, and The fuel gas supply pipeline comprises: a hydrogen supply line connected to the hydrogen supply system and to the fuel cell stack, the hydrogen supply line being configured to supply hydrogen humidified while passing through the humidification module to the fuel electrode; an air supply line connected to the air supply system and to the fuel cell stack, the air supply line being configured to supply air humidified while passing through the humidification module to the air electrode; a first bypass line branching from a point of the hydrogen supply line before the humidification module, the first bypass line configured to bypass the humidification module and supply hydrogen directly to the fuel electrode; and A second bypass line diverges from a point of the air supply line before the humidification module, the second bypass line being configured to bypass the humidification module and supply air directly to the air electrode.

9. The fuel cell system according to claim 8, further comprising: a control valve disposed in the fuel gas supply line, the control valve being configured to control the passage of the fuel gas supply line, wherein The controller is further configured to control the control valve to control the passage.

10. The fuel cell system according to claim 9, wherein: The control valve includes a first control valve located at a junction between the hydrogen supply line and the first bypass line and a second control valve located at a junction between the air supply line and the second bypass line, and The controller controls the first control valve and the second control valve so that hydrogen and oxygen selectively pass through the humidification module.

11. The fuel cell system according to claim 1, wherein: When it is determined that the temperature of the fuel cell stack is low, the controller controls such that the amount of each fuel gas supplied to the fuel cell stack is smaller than the amount of each fuel gas when the temperature of the fuel cell stack is determined to be a normal temperature.

12. A control method for a fuel cell system according to claim 1, the control method comprising: measuring a temperature of the fuel cell stack and determining whether the temperature of the fuel cell stack is low; When it is determined that the temperature of the fuel cell stack is a normal temperature in an initial stage of the operation of the fuel cell stack, humidified gas is supplied to the fuel cell stack so that the fuel cell stack operates in a normal output mode, and when it is determined that the temperature of the fuel cell stack is low, dry gas is supplied so that the fuel cell stack operates in a low output mode; and The temperature of the fuel cell stack is measured when the fuel cell stack operates in a low output mode, and when it is determined that the temperature of the fuel cell stack reaches a normal temperature, humidified gas is supplied to the fuel cell stack so that the fuel cell stack operates in a normal output mode.

13. The control method according to claim 12, wherein: When the fuel cell stack operates in the low output mode, the controller controls so that the fuel cell stack operates in the normal output mode.

14. The control method according to claim 12, wherein: When the fuel cell stack operates in the low output mode, the controller controls such that the amount of each fuel gas supplied to the fuel cell stack is smaller than the amount of each fuel gas supplied when the fuel cell stack operates in the normal output mode.

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