Apparatus and method for controlling a fuel electrode exhaust valve of a fuel cell system

Abstract

An apparatus and method for controlling a fuel electrode exhaust valve of a fuel cell system are disclosed, wherein the apparatus includes a hydrogen sensor configured to measure a concentration of hydrogen released by opening the fuel electrode exhaust valve, a first pressure sensor configured to measure an inlet pressure of the fuel electrode exhaust valve, a second pressure sensor configured to measure an outlet pressure of the fuel electrode exhaust valve, and a controller configured to control an opening area of the fuel electrode exhaust valve to a maximum value when exhausting condensate, and to control the opening area of the fuel electrode exhaust valve based on a difference between the inlet pressure and the outlet pressure of the fuel electrode exhaust valve when purging hydrogen.

Description

Technical Field

[0001] This invention relates to a technique for controlling the fuel electrode discharge valve of a fuel cell system. Background Technology

[0002] The statements in this section are provided only as background information in relation to the present invention and do not constitute prior art.

[0003] A fuel cell system is a power generation system that directly converts the chemical energy of the fuel in the fuel cell stack into electrical energy through electrochemical methods, rather than converting chemical energy into heat through combustion.

[0004] For this purpose, a fuel cell system may include a fuel cell stack that generates electrical energy; a hydrogen supply device that supplies hydrogen fuel to the fuel cell stack; an air supply device that supplies air (oxygen) to the fuel cell stack, wherein air is the oxidant for the electrochemical reaction; a thermal management system (TMS) that releases the reaction heat of the fuel cell stack to the outside, controls the operating temperature of the fuel cell stack and performs water management functions; and a control device for controlling the overall operation of the fuel cell system.

[0005] Fuel cell systems generate electricity by reacting hydrogen fuel with oxygen in the air, releasing heat and water as byproducts of the reaction.

[0006] Meanwhile, in situations such as decreased hydrogen concentration, increased nitrogen concentration, excessive current accumulation, stack reverse voltage, voltage imbalance, or excessive fuel electrode pressure, the fuel cell system opens the exhaust valve to ensure the hydrogen concentration in the fuel electrode and control the pressure in the fuel electrode.

[0007] When the discharge valve opens, condensate in the collector located upstream of the valve is released, and the fuel cell system determines that the condensate release is complete when the water level in the collector is below or equal to a reference value. Thereafter, the fuel cell system keeps the discharge valve open for the reference time to allow hydrogen to be purged.

[0008] We have found that fuel cell systems may fail to properly regulate the opening area of ​​the exhaust valve during the release of condensate and hydrogen purging. This can lead to hydrogen purging delays, reducing fuel cell stack durability, or it may promote hydrogen purging, causing the hydrogen concentration in the exhaust gas to exceed reference values.

[0009] The information disclosed in this background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain any information that does not constitute prior art or that prior art may present to those skilled in the art. Summary of the Invention

[0010] One aspect of the present invention provides an apparatus and method for controlling a fuel electrode discharge valve in a fuel cell system, wherein the apparatus and method suppress or prevent degradation in the fuel cell stack, and control the discharge valve opening area to a maximum value when discharging condensate and based on the difference between the inlet and outlet pressures of the discharge valve when purging hydrogen, thereby maintaining the hydrogen concentration in the exhaust gas at a reference value or less by purging hydrogen at an optimal time.

[0011] The technical problems to be solved by the present invention are not limited to those described above. Those skilled in the art will clearly understand from the following description any other technical problems not mentioned herein.

[0012] According to one aspect of the present invention, an apparatus for controlling a fuel electrode discharge valve of a fuel cell system includes: a hydrogen sensor for measuring the concentration of hydrogen released by opening the fuel electrode discharge valve; a first pressure sensor for measuring the inlet pressure of the fuel electrode discharge valve; a second pressure sensor for measuring the outlet pressure of the fuel electrode discharge valve; and a controller for controlling the opening area of ​​the fuel electrode discharge valve to a maximum value when discharging condensate, and controlling the opening area of ​​the fuel electrode discharge valve based on the difference between the inlet pressure and the outlet pressure of the fuel electrode discharge valve when purging hydrogen.

[0013] In one embodiment of the invention, when the hydrogen concentration measured by the hydrogen sensor exceeds a first reference value, the controller begins to purge hydrogen.

[0014] In another embodiment of the invention, the controller can keep the opening area of ​​the fuel electrode discharge valve within a reference range during hydrogen purging.

[0015] In some embodiments of the present invention, the controller may reduce the opening area of ​​the fuel electrode discharge valve as the difference between the inlet pressure and the outlet pressure of the fuel electrode discharge valve increases.

[0016] In some embodiments of the present invention, when the hydrogen concentration measured by the hydrogen sensor exceeds a second reference value, the controller can control the opening area of ​​the fuel electrode discharge valve to a minimum value.

[0017] In some embodiments of the present invention, the controller can block the fuel electrode discharge valve when conditions for blocking the fuel electrode discharge valve are met.

[0018] According to another aspect of the present invention, a method for controlling a fuel electrode discharge valve of a fuel cell system includes the following steps: measuring the concentration of hydrogen released by opening the fuel electrode discharge valve by a hydrogen sensor; measuring the inlet pressure of the fuel electrode discharge valve by a first pressure sensor; measuring the outlet pressure of the fuel electrode discharge valve by a second pressure sensor; controlling the opening area of ​​the fuel electrode discharge valve to a maximum value by a controller when discharging condensate; and controlling the opening area of ​​the fuel electrode discharge valve by the controller based on the difference between the inlet pressure and the outlet pressure of the fuel electrode discharge valve during hydrogen purging.

[0019] In some embodiments of the present invention, the step of controlling the opening area of ​​the fuel electrode discharge valve may include: determining the time when the hydrogen concentration exceeds a first reference value to begin hydrogen purging.

[0020] In some embodiments of the present invention, the step of controlling the opening area of ​​the fuel electrode discharge valve may include: controlling the opening area of ​​the fuel electrode discharge valve within a reference range during hydrogen purging.

[0021] In some embodiments of the present invention, the step of controlling the opening area of ​​the fuel electrode discharge valve may include: reducing the opening area of ​​the fuel electrode discharge valve based on an increase in the difference between the inlet pressure and the outlet pressure of the fuel electrode discharge valve.

[0022] In some embodiments of the present invention, the step of controlling the opening area of ​​the fuel electrode discharge valve may include: when the hydrogen concentration measured by the hydrogen sensor exceeds a second reference value, controlling the opening area of ​​the fuel electrode discharge valve to a minimum value.

[0023] In some embodiments of the present invention, the method further includes the step of: the controller blocking the fuel electrode discharge valve based on conditions for blocking the fuel electrode discharge valve.

[0024] Other applicable fields will become apparent from the description provided herein. It should be understood that the description and specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0025] To better understand the present invention, various embodiments thereof will be described below as examples with reference to the accompanying drawings, wherein:

[0026] Figure 1 A schematic diagram illustrating a fuel cell system to which the present invention is applied;

[0027] Figure 2 A view illustrating the construction of an apparatus for controlling a fuel electrode discharge valve in a fuel cell system according to an embodiment of the present invention;

[0028] Figure 3A view illustrating the process by which a controller included in a fuel electrode discharge valve control device of a fuel cell system according to an embodiment of the present invention adjusts the opening area of ​​the discharge valve.

[0029] Figure 4 A view illustrating the process by which a controller included in a fuel electrode discharge valve control device of a fuel cell system according to an embodiment of the present invention adjusts the opening area of ​​the discharge valve.

[0030] Figure 5 A flowchart illustrating a method for controlling a fuel electrode discharge valve in a fuel cell system according to an embodiment of the present invention; and

[0031] Figure 6 This is a block diagram illustrating a computational system for performing a method for controlling a fuel electrode discharge valve in a fuel cell system, according to an embodiment of the present invention.

[0032] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Detailed Implementation

[0033] The following description is exemplary in nature only and is not intended to limit the invention, application, or use. It should be understood that throughout the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0034] In the following, some embodiments of the invention will be described in detail with reference to the exemplary accompanying drawings. It should be noted that when adding reference numerals to components in each drawing, the same or equivalent parts are indicated by the same reference numerals even if they are shown in other drawings. Furthermore, in describing embodiments of the invention, detailed descriptions of well-known features or functions will be omitted to avoid unnecessarily obscuring the spirit of the invention.

[0035] In describing components according to embodiments of the present invention, terms such as first, second, "A", "B", (a), (b), etc., may be used. These terms are intended only to distinguish one component from another, and they do not limit the nature, order, or sequence of the components. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning equivalent to that in the context of the relevant field and should not be interpreted as having an ideal or overly formal meaning unless expressly defined as having such a meaning in this application.

[0036] Figure 1 An example diagram is shown to illustrate a fuel cell system to which the present invention is applied.

[0037] like Figure 1 As shown, a fuel cell system using the present invention may include a fuel shut-off valve (FBV) 100, a fuel supply valve (FSV) 110, a fuel injector (FE) 120, a fuel pressure sensor 1 (FPS1) 130, a fuel cell stack (FCS) 140, a fuel line water collector (FWT) 150, a fuel line drain valve (FDV) 160, etc.

[0038] The FBV 100 block is supplied with hydrogen to the fuel cell stack 140.

[0039] FSV 110 regulates the pressure of the hydrogen supplied to the fuel cell stack 140.

[0040] FE 120 supplies hydrogen to fuel cell stack 140 by applying pressure to the hydrogen.

[0041] FPS1 130 serves as the first pressure sensor, measuring the pressure of hydrogen supplied to the fuel cell stack 140. In other words, FPS1 130 measures the inlet pressure of FDV 160.

[0042] The fuel cell stack 140 generates electricity through the chemical reaction of hydrogen and oxygen.

[0043] FWT 150 stores condensate from fuel electrodes.

[0044] FDV 160 acts as a fuel electrode vent valve, purging hydrogen from the fuel cell stack 140 and discharging condensate (water) stored in FWT 150. Vent valve 160 can be implemented by a solenoid valve.

[0045] Figure 2 This is a view illustrating the construction of a device for controlling the fuel electrode discharge valve of a fuel cell system according to an embodiment of the present invention.

[0046] like Figure 2 As shown, the fuel electrode discharge valve control device 200 of the fuel cell system may include a storage device 10, a hydrogen sensor 20, FPS1 130, FPS2 30, and a controller 40. Depending on how the fuel electrode discharge valve control device 200 of the fuel cell system according to an embodiment of the present invention is implemented, these components may be combined to form a whole, or some components may be omitted.

[0047] The memory 10 can store various logics, algorithms, and programs required for determining the start time of hydrogen purging based on the hydrogen concentration at the outlet of the discharge valve 160 measured by the hydrogen sensor 20, thereby controlling the opening area of ​​the discharge valve 160 to a maximum value when discharging condensate, and adjusting the opening area of ​​the discharge valve 160 based on the difference between the inlet pressure and the outlet pressure of the discharge valve 160 during hydrogen purging.

[0048] The storage device 10 may store a first reference value (e.g., 1% to 2%) as a hydrogen concentration for determining when to start purging hydrogen, and may store a second reference value (e.g., 3% to 4%) as a second hydrogen concentration for controlling the opening area of ​​the discharge valve 160 to a minimum.

[0049] Storage device 10 may include at least one type of storage medium selected from the following types of storage media: flash memory, hard disk, micro type and card type (e.g., security digital (SD) card or eXtream digital (XD) card), random access memory (RAM), static RAM (SRAM), read-only memory (ROM), programmable ROM (PROM), electrically erasable PROM (EEPROM), magnetic RAM (MRAM), disk type and optical disk type.

[0050] The hydrogen sensor 20 can be located at the outlet of the discharge valve 160 and can measure the concentration of hydrogen released when the discharge valve 160 is open.

[0051] As a second pressure sensor, FPS2 30 can be located at the outlet of the discharge valve 160 and can measure the outlet pressure of the discharge valve 160.

[0052] Controller 40 performs overall control to allow components to perform their functions properly. Controller 40 may be implemented in hardware or software, or a combination thereof. Controller 40 may be implemented as, but is not limited to, a microprocessor.

[0053] Specifically, the controller 40 can perform various controls in determining the start time for hydrogen purging based on the hydrogen concentration at the outlet of the discharge valve 160 measured by the hydrogen sensor 20, thereby controlling the opening area of ​​the discharge valve 160 to a maximum value when discharging condensate, and adjusting the opening area of ​​the discharge valve 160 based on the difference between the inlet pressure and the outlet pressure of the discharge valve 160 during hydrogen purging.

[0054] When certain conditions are met, the controller 40 can open the discharge valve 160. That is, the controller 40 can open the discharge valve 160 under conditions such as a decrease in hydrogen concentration in the fuel cell stack 140, an increase in nitrogen concentration in the fuel cell stack 140, excessive current accumulation, reverse voltage in the fuel cell stack 140, voltage imbalance, or excessive fuel electrode pressure. The conditions used to open the discharge valve 160 are common and well-known techniques, and any of these conditions can be used when opening the discharge valve 160.

[0055] When the drain valve 160 is opened, the controller 40 can control the opening area of ​​the drain valve 160 to the maximum value to allow the condensate in the FWT 150 to be discharged quickly.

[0056] When the discharge valve 160 is opened, the controller 40 can determine when to start purging hydrogen based on the hydrogen concentration measured by the hydrogen sensor 20. That is, if the hydrogen concentration measured by the hydrogen sensor 20 exceeds a first reference value when the discharge valve 160 is opened, the controller 40 can determine that the condensate has been completely discharged and start purging hydrogen.

[0057] During hydrogen purging, the controller 40 can adjust the opening area of ​​the discharge valve 160 based on the difference between the inlet pressure of the discharge valve 160 measured by FPS1 130 and the outlet pressure of the discharge valve 160 measured by FPS230.

[0058] In the following text, reference will be made to Figure 3 The process of adjusting the opening area of ​​the discharge valve 160 by the controller 40 is described.

[0059] Figure 3 This is a view illustrating the process by which a controller included in a fuel cell system's fuel electrode discharge valve control device adjusts the opening area of ​​the discharge valve according to an embodiment of the present invention.

[0060] exist Figure 3 In the diagram, the vertical axis represents the load corresponding to the opening degree of the discharge valve 160, and the horizontal axis represents the difference between the inlet pressure and the outlet pressure of the discharge valve 160.

[0061] like Figure 3 As shown, when the drain valve 160 is opened, the controller 40 can control the opening area of ​​the drain valve 160 to the maximum value D3 to allow the condensate in the FWT 150 to be discharged quickly.

[0062] During hydrogen purging, controller 40 can adjust the opening area of ​​discharge valve 160 within a reference range of D1 to D2 based on the difference (hereinafter referred to as differential pressure) between the inlet pressure of discharge valve 160 measured by FPS1 130 and the outlet pressure of discharge valve 160 measured by FPS2 30. At this time, controller 40 can perform control such that as the differential pressure of discharge valve 160 increases, the opening area of ​​discharge valve 160 decreases. This is to reduce the amount of hydrogen released. Furthermore, controller 40 can perform control such that as the differential pressure of discharge valve 160 decreases, the opening area of ​​discharge valve 160 increases. This is to suppress or prevent delays in hydrogen purging.

[0063] When the hydrogen concentration measured by the hydrogen sensor 20 exceeds the second reference value during the adjustment of the opening area of ​​the discharge valve 160, the controller 40 controls the opening area of ​​the discharge valve 160 to a minimum value D1 to reduce or minimize the amount of hydrogen released. Even when the opening area of ​​the discharge valve 160 is controlled to the minimum value D1, it does not mean that the discharge valve 160 is in a completely closed state.

[0064] Simultaneously, when the conditions for blocking the discharge valve 160 are met, the controller 40 can block the discharge valve 160. Here, the conditions for blocking the discharge valve 160 are well-known and common techniques, and any method can be used to block the discharge valve 160.

[0065] Figure 4 This is a view illustrating the process by which a controller included in a fuel cell system's fuel electrode discharge valve control device adjusts the opening area of ​​the discharge valve in one embodiment of the present invention.

[0066] exist Figure 4 In the text, “A1” indicates the time when the conditions for opening the discharge valve 160 are met, “A2” indicates the time when the discharge valve 160 is opened, “A3” indicates the time when hydrogen purging begins, “A4” indicates the time when the hydrogen concentration measured by the hydrogen sensor 20 located at the outlet of the discharge valve 160 exceeds the second reference value, and “A5” indicates the time when the discharge valve 160 is blocked.

[0067] exist Figure 4 In the diagram, "B1" represents the normal operating interval, "B2" represents the interval during which the pressure of the fuel electrode increases, "B3" represents the interval during which the opening area of ​​the discharge valve 160 is controlled to the maximum value "D3", "B4" represents the interval during which the opening area of ​​the discharge valve 160 is adjusted within the reference range of "D1" to "D2" based on the pressure difference of the discharge valve 160, and "B5" represents the interval during which the concentration of hydrogen released from the outlet of the discharge valve 160 exceeds the second reference value and the opening area of ​​the discharge valve 160 is controlled to the minimum value "D1".

[0068] refer to Figure 4 “C1” represents the first reference value; “C2” represents the second reference value; “C3” represents the minimum differential pressure of the discharge valve 160, which is used as the condition for opening the discharge valve 160; “D3” represents the maximum opening of the discharge valve 160 when condensate is discharged; “D2” represents the maximum opening of the discharge valve 160 when hydrogen is purged, while “D1” represents the minimum opening of the discharge valve 160 when hydrogen is purged.

[0069] Figure 5 A flowchart illustrating a method for controlling a fuel electrode discharge valve in a fuel cell system according to an embodiment of the present invention is shown.

[0070] The controller 40 opens the discharge valve 160 (501). At this time, the controller 40 can open the discharge valve 160 if the conditions for opening the discharge valve 160 are met, and the opening conditions are not the subject of this invention.

[0071] The controller 40 controls the opening area of ​​the discharge valve 160 to the maximum value (502).

[0072] Hydrogen sensor 20 measures the concentration of hydrogen released from discharge valve 160 (503). At this time, hydrogen sensor 20 can periodically measure the concentration of hydrogen.

[0073] The controller 40 determines whether the concentration of hydrogen measured by the hydrogen sensor 20 exceeds a first reference value (504).

[0074] When it is determined that the hydrogen concentration does not exceed the first reference value (504), the controller 40 proceeds to step "503".

[0075] When it is determined that the hydrogen concentration exceeds the first reference value (504), the controller 40 recognizes that the hydrogen purging has started and determines whether the hydrogen concentration exceeds the second reference value (505).

[0076] When it is determined that the hydrogen concentration does not exceed the second reference value (505), the controller 40 controls the opening of the discharge valve 160 within the reference range of D1 to D2 based on the difference (differential pressure) between the inlet and outlet pressures of the discharge valve 160 (506). At this time, the controller 40 can perform control such that as the differential pressure of the discharge valve 160 decreases, the opening area of ​​the discharge valve 160 increases.

[0077] When the concentration of hydrogen is determined to exceed the second reference value (505), the controller 40 controls the opening area of ​​the discharge valve 160 to the minimum value D1 (507).

[0078] The controller 40 determines whether the conditions (508) for blocking the discharge valve 160 are met.

[0079] When it is determined that the conditions for blocking the discharge valve 160 are not met (508), the controller 40 proceeds to step "505", and when the conditions for blocking the discharge valve 160 are met, the controller 40 blocks the discharge valve 160.

[0080] Figure 6 A block diagram of a computational system for performing a method for controlling a fuel electrode discharge valve in a fuel cell system, according to an embodiment of the present invention, is shown.

[0081] refer to Figure 6 A method for controlling the fuel electrode discharge valve of a fuel cell system can be implemented through a computing system. The computing system 1000 may include at least one processor 1100, a memory 1300, a user interface input device 1400, a user interface output device 1500, a storage device 1600, and a network interface 1700, which are interconnected via a system bus 1200.

[0082] Processor 1100 may be a central processing unit (CPU) or a semiconductor device for processing instructions stored in memory 1300 and / or storage device 1600. Memory 1300 and storage device 1600 may include various types of volatile or non-volatile storage media. For example, memory 1300 may include ROM (Read-Only Memory) 1310 and RAM (Random Access Memory) 1320.

[0083] Therefore, the operation of the methods or algorithms described in conjunction with the embodiments disclosed herein can be directly implemented in hardware or software modules executed by processor 1100, or in combination thereof. The software modules can reside on storage media (i.e., memory 1300 and / or storage device 1600), such as RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, removable disk, or CD-ROM. This exemplary storage medium can be coupled to processor 1100, and processor 1100 can read information from and record information in the storage medium. Optionally, the storage medium can be integrated with processor 1100. Processor 1100 and storage medium can reside in an application-specific integrated circuit (ASIC). The ASIC can reside within a user terminal. In another case, processor 1100 and storage medium can reside as separate components in the user terminal.

[0084] As described above, according to embodiments of the present invention, an apparatus and method for controlling the fuel electrode discharge valve of a fuel cell system controls the opening area of ​​the discharge valve to a maximum value when discharging condensate, and controls the opening area of ​​the discharge valve based on the difference between the inlet pressure and the outlet pressure of the discharge valve when purging hydrogen, thereby enabling hydrogen to be purged at an optimal time, which in turn prevents degradation in the fuel cell stack and keeps the hydrogen concentration in the exhaust gas at a reference value or lower.

[0085] In the foregoing, although the present invention has been described with reference to exemplary embodiments and accompanying drawings, the present invention is not limited thereto. Those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the invention.

[0086] Therefore, exemplary embodiments of the invention are provided to illustrate the spirit and scope of the invention, but are not intended to limit them, so that the spirit and scope of the invention are not limited by form. The scope of the invention should be interpreted based on the appended claims, and all technical ideas within the scope of the claims should be included within the scope of the invention.

Claims

1. An apparatus for controlling a fuel electrode discharge valve in a fuel cell system, the apparatus comprising: A hydrogen sensor is configured to measure the concentration of hydrogen released by opening the fuel electrode discharge valve; The first pressure sensor is configured to measure the pressure of hydrogen supplied to the fuel cell stack; A second pressure sensor is configured to measure the outlet pressure of the fuel electrode discharge valve; as well as The controller is configured to: control the opening area of ​​the fuel electrode discharge valve to a maximum value during condensate discharge, and control the opening area of ​​the fuel electrode discharge valve based on the difference between the pressure of hydrogen supplied to the fuel cell stack during hydrogen purging and the outlet pressure of the fuel electrode discharge valve. The controller is configured to reduce the opening area of ​​the fuel electrode discharge valve as the difference between the inlet and outlet pressures of the fuel electrode discharge valve increases.

2. The apparatus according to claim 1, wherein, When the hydrogen concentration measured by the hydrogen sensor exceeds a first reference value, the controller is configured to start purging hydrogen.

3. The apparatus according to claim 1, wherein, The controller is configured to keep the opening area of ​​the fuel electrode discharge valve within a reference range during hydrogen purging.

4. The apparatus according to claim 1, wherein, When the hydrogen concentration measured by the hydrogen sensor exceeds a second reference value, the controller is configured to control the opening area of ​​the fuel electrode discharge valve to a minimum value, which does not mean that the fuel electrode discharge valve is in a completely closed state.

5. The apparatus according to claim 1, wherein, When the conditions for blocking the fuel electrode discharge valve are met, the controller is configured to block the fuel electrode discharge valve.

6. A method for controlling a fuel electrode discharge valve in a fuel cell system, the method comprising the following steps: The concentration of hydrogen released by opening the fuel electrode discharge valve is measured by a hydrogen sensor; The pressure of hydrogen supplied to the fuel cell stack is measured by a first pressure sensor; The outlet pressure of the fuel electrode discharge valve is measured by a second pressure sensor; During the discharge of condensate, the controller adjusts the opening area of ​​the fuel electrode discharge valve to its maximum value; and The controller controls the opening area of ​​the fuel electrode discharge valve based on the difference between the pressure of the hydrogen supplied to the fuel cell stack during hydrogen purging and the outlet pressure of the fuel electrode discharge valve. The step of controlling the opening area of ​​the fuel electrode discharge valve includes: The opening area of ​​the fuel electrode discharge valve is reduced by increasing the difference between the inlet and outlet pressures of the fuel electrode discharge valve.

7. The method according to claim 6, wherein, The steps for controlling the opening area of ​​the fuel electrode discharge valve include: Determine when the hydrogen concentration exceeds the first reference value to begin hydrogen purging.

8. The method according to claim 6, wherein, The steps for controlling the opening area of ​​the fuel electrode discharge valve include: During hydrogen purging, the opening area of ​​the fuel electrode discharge valve is controlled within a reference range.

9. The method according to claim 6, wherein, The steps for controlling the opening area of ​​the fuel electrode discharge valve include: When the hydrogen concentration measured by the hydrogen sensor exceeds the second reference value, the opening area of ​​the fuel electrode discharge valve is controlled to the minimum value, which does not mean that the fuel electrode discharge valve is in a completely closed state.

10. The method of claim 6, further comprising the following steps: The controller blocks the fuel electrode discharge valve based on conditions for blocking the fuel electrode discharge valve.

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