KR20240068194A - Purge control system for fuel cell system and purge control method using the same - Google Patents

Abstract

The present invention relates to a purge control system and control method that implements a regeneration mode of the fuel cell stack after forming a nitrogen atmosphere in the air electrode through a purge process during the shutdown process of the fuel cell stack. The purge control system silver fuel cell stack; a hydrogen supply unit that supplies hydrogen to the hydrogen electrode of the fuel cell stack; an air supply unit supplying air to the air electrode of the fuel cell stack; a nitrogen supply unit connected to the hydrogen supply unit to supply purge nitrogen to the hydrogen electrode and air electrode of the fuel cell stack; and a control unit that purges the fuel cell stack with nitrogen by controlling the opening and closing operations of valves connected to the air supply unit, the hydrogen supply unit, and the nitrogen supply unit, wherein the control unit purges the hydrogen electrode and the air electrode with nitrogen gas when the fuel cell stack is turned off. After purging, the hydrogen electrode of the fuel cell stack can be controlled to be in a hydrogen atmosphere and the air electrode of the fuel cell stack can be controlled to be in a nitrogen atmosphere to diagnose the condition of the fuel cell stack and restore performance.

Description

Fuel cell system purge control system and purge control method using the same {Purge control system for fuel cell system and purge control method using the same}

The present invention relates to a fuel cell system purge control system and a purge control method using the same. More specifically, in the process of shutting down a fuel cell stack, a nitrogen atmosphere is formed in the air electrode through a purge process, and then the fuel cell stack is shut down. It relates to a fuzzy control system and control method that implements a stack regeneration mode.

A fuel cell system is a power generation device that generates electrical energy through an electrochemical reaction between hydrogen and oxygen. Fuel cells can be classified into polymer electrolyte membrane fuel cells, molten carbonate fuel cells, and solid oxide fuel cells depending on the type of electrolyte.

A polymer electrolyte fuel cell is a fuel cell that uses a polymer membrane with hydrogen ion exchange characteristics as an electrolyte. It continuously generates electrical energy and heat by electrochemically reacting fuel gas containing hydrogen and oxidizing gas containing oxygen. .

These polymer electrolyte fuel cells have excellent output characteristics, low operating temperature, and fast start-up and response characteristics compared to other fuel cells. A fuel cell system constructed using such a polymer electrolyte fuel cell is used as a mobile power source or an alternative battery power source, and has the following structure made up of relatively simple components.

The fuel cell system directly supplies air as an oxidizing gas to the fuel cell stack, and supplies pure hydrogen stored in a compressed vessel as fuel gas to the fuel cell stack. Additionally, the fuel cell system generates electrical energy by electrochemically reacting hydrogen and oxygen within the fuel cell stack. The fuel cell stack uses oxygen contained in the air through a cathode reaction and discharges water and unreacted air generated within the cathode channel to the outside.

The fuel cell stack uses a dead-end method that blocks the outlet of fuel gas. However, even if the fuel cell system uses this dead end method, the outlet of the fuel gas is periodically opened to discharge the water generated in the anode channel, thereby discharging hydrogen to the outside.

This hydrogen discharge operation is commonly referred to as a hydrogen purge method. Water generated within the fuel cell stack is mainly generated in the cathode channel and is transferred into the anode channel through the electrolyte membrane by the diffusion of water. Water present in the anode channel prevents hydrogen, a fuel gas, from being supplied to the electrode, thereby reducing the power generation performance of the fuel cell stack, and this is commonly referred to as a flooding phenomenon.

That is, the existing fuel cell system performs a hydrogen purge method to prevent this flooding phenomenon. Methods for purging hydrogen in a fuel cell system include a method of opening the purge valve at regular intervals, a method of opening the purge valve under conditions where the fuel cell voltage drops below a preset value, and a method of combining the two methods described above. This is being applied.

The hydrogen purge method of the fuel cell system improves as the hydrogen discharge pressure is higher, the purge valve opening cycle is shorter, and the purge valve opening time is longer. However, as the hydrogen purge method of this fuel cell system increases the hydrogen discharge pressure, the pressure difference between hydrogen and air on both sides of the electrolyte membrane increases.

As a result, the existing fuel cell system has a problem in that the durability of the electrolyte membrane is reduced due to the physical pressure applied to the electrolyte membrane. In addition, the hydrogen purge method of the fuel cell system may set the opening cycle of the purge valve to be short or the purge valve opening time to be long, but this increases the amount of hydrogen that is not used in the fuel cell stack and is discharged to the outside. There is a problem that the hydrogen utilization rate of the fuel cell stack is lowered.

The purpose of the present invention is to provide a fuel cell purge control system and control method that can extend fuel cell life by implementing a regeneration mode in the purge process.

Another object of the present invention is to provide a fuel cell purge control system and control method that can reduce the cost of the system by connecting a single valve only to the hydrogen electrode to purge both the hydrogen electrode and the air electrode.

A fuel cell system purge control device according to the present invention for achieving this purpose includes a fuel cell stack; a hydrogen supply unit that supplies hydrogen to the hydrogen electrode of the fuel cell stack; an air supply unit supplying air to the air electrode of the fuel cell stack; a nitrogen supply unit connected to the hydrogen supply unit to supply purge nitrogen to the hydrogen electrode and air electrode of the fuel cell stack; and a control unit that purges the fuel cell stack with nitrogen by controlling the opening and closing operations of valves connected to the air supply unit, hydrogen supply unit, and nitrogen supply unit, wherein the control unit purges the hydrogen electrode and the air electrode with nitrogen when the fuel cell stack is turned off. After purging with gas, the hydrogen electrode of the fuel cell stack is formed into a hydrogen atmosphere and the air electrode of the fuel cell stack is formed into a nitrogen atmosphere, so that the condition of the fuel cell stack is diagnosed and performance recovery is performed.

In the fuel cell system purge control device according to the present invention, the control unit can diagnose the deterioration state of the fuel cell stack by measuring the surface area of the reaction catalyst using cyclic voltammetry.

In the fuel cell system purge control device according to the present invention, the control unit measures the catalyst surface area by supplying a voltage between a lower limit voltage in the range of 0.05V to 1V and an upper limit voltage of 1.2V to the fuel cell stack at a constant voltage rate of 50mV/s. do.

In the fuel cell system purge control device according to the present invention, the control unit restores deteriorated performance of the fuel cell by supplying voltage to the fuel cell stack using a step voltage method.

In the fuel cell system purge control device according to the present invention, the control unit periodically cycles and supplies a voltage between a lower limit voltage of 0.3V and an upper limit voltage of 0.6V to the fuel cell stack.

In the fuel cell system purge control device according to the present invention, the control unit controls the hydrogen electrode of the fuel cell stack to be formed into a hydrogen atmosphere with a hydrogen concentration of 99% or more prior to diagnosing the condition of the fuel cell stack and performing performance recovery.

In the fuel cell system purge control device according to the present invention, the control unit controls nitrogen purge so that the hydrogen concentration of the hydrogen electrode of the fuel cell stack is less than 1% after diagnosing the condition of the fuel cell stack and recovering performance.

In the fuel cell system purge control device according to the present invention, the controller purges the hydrogen electrode of the fuel cell stack with nitrogen and then controls the opening and closing operation of the valve connected to the air supply unit to purge the air electrode of the fuel cell stack with nitrogen. Purge.

The fuel cell system purge control method according to the present invention includes a first purge process of purging the hydrogen electrode of the fuel cell stack with nitrogen when the fuel cell stack is turned off. A second purge process of purging the air electrode of the fuel cell stack with nitrogen by controlling a valve connected to the fuel cell stack to connect the path of the nitrogen that has passed through the hydrogen electrode of the fuel cell stack to the air electrode of the fuel cell stack; A regeneration mode process for diagnosing the condition of the fuel cell stack and restoring performance; and a third purge process for purging the hydrogen electrode of the fuel cell stack with nitrogen.

In the fuel cell system purge control method according to the present invention, the regeneration mode processing process includes a first preparation step of forming the hydrogen electrode of the fuel cell stack into a hydrogen atmosphere; A second preparation step of forming the air electrode of the fuel cell stack in a nitrogen atmosphere; and a replay mode step of diagnosing the status of the stack and restoring performance.

In the fuel cell system purge control method according to the present invention, the first preparation step includes supplying hydrogen to the hydrogen electrode of the fuel cell stack; Waiting until the hydrogen concentration of the hydrogen electrode is 99% or more; and blocking hydrogen supplied to the hydrogen electrode of the fuel cell stack.

The fuel cell system purge control device and control method according to the present invention purges both the hydrogen electrode and the air electrode with an inert gas by placing one nitrogen supply valve only on the hydrogen electrode, thereby reducing the cost of the system and purging the fuel cell during the purge process. The degree of deterioration can be identified and performance recovery procedures can be performed.

1 is an exemplary diagram showing the configuration of a fuel cell system purge control device according to the present invention.
Figure 2 is an exemplary flowchart showing a start-up procedure in the fuel cell system purge control method according to the present invention.
Figure 3 is an exemplary diagram showing the flow of nitrogen to remove oxygen from the hydrogen electrode and oxygen electrode during the startup procedure of the fuel cell system according to the present invention.
Figure 4 is an exemplary diagram showing the flow of hydrogen and air during the startup procedure of the fuel cell system according to the present invention.
Figure 5 is an example flowchart showing a shutdown procedure in the fuel cell system purge control method according to the present invention.
Figure 6 is an exemplary diagram showing the flow of nitrogen and air for hydrogen electrode purge during the shutdown procedure of the fuel cell system according to the present invention.
Figure 7 is an exemplary diagram showing the flow of nitrogen for purging the air electrode during the shutdown procedure of the fuel cell system according to the present invention.
Figure 8 is an exemplary diagram showing the flow of hydrogen and air during the regenerative mode hydrogen supply process during the shutdown procedure of the fuel cell system according to the present invention.
Figure 9 is an exemplary diagram showing the state of a valve for controlling the flow of hydrogen and air during the hydrogen blocking process in regeneration mode during the shutdown procedure of the fuel cell system according to the present invention.
Figure 10 is an exemplary diagram showing the flow of nitrogen and air for regenerative mode nitrogen purge during the shutdown procedure of the fuel cell system according to the present invention.

With respect to the embodiments of the present invention disclosed in the text, specific structural and functional descriptions are merely illustrative for the purpose of explaining the embodiments of the present invention, and the embodiments of the present invention may be implemented in various forms and are not included in the text. It should not be construed as limited to the described embodiments.

Since the present invention can be subject to various changes and can have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Terms such as first, second, etc. may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be referred to as a second component, and similarly, the second component may be referred to as a first component without departing from the scope of the present invention.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when a component is referred to as being “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between. Other expressions that describe the relationship between components, such as "between" and "immediately between" or "neighboring" and "directly adjacent to" should be interpreted similarly.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprises” or “has” are intended to designate the presence of a disclosed feature, number, step, operation, component, part, or combination thereof, and are intended to indicate the presence of one or more other features or numbers, It should be understood that this does not exclude in advance the possibility of the presence or addition of steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as indicating meanings consistent with the meanings they have in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an idealized or excessively formal sense. No.

Meanwhile, if an embodiment can be implemented differently, functions or operations specified within a specific block may occur differently from the order specified in the flowchart. For example, two consecutive blocks may actually be performed substantially simultaneously, or the blocks may be performed in reverse depending on the functions or operations involved.

Hereinafter, a fuel cell system purge control system and a purge control method using the same according to the present invention will be described with reference to the attached drawings.

1 is an exemplary diagram showing the configuration of a fuel cell system purge control device according to the present invention. The fuel cell stack 40 includes a hydrogen electrode (Anode: 41) and an air electrode (Cathode: 42). When the hydrogen inlet valve (21) is opened, hydrogen (H ₂ ) is injected into the fuel ejector (33) through the fuel block valve (31) and the fuel supply valve (32). is transmitted to the hydrogen electrode 41 of the fuel cell stack 40. The air from which impurities have been filtered out by the air filter (Filter: 11) is compressed by the air compressor (12), and the temperature is lowered by the air cooler (Air Cooler: 13) to be used in the humidifier (Air Humidifier: 14). It moves to and is delivered to the air electrode 42 of the fuel cell stack 40 through an air cut-off valve inlet (15).

The water discharged from the hydrogen electrode 41 of the fuel cell stack 40 passes through the fuel-line water trap (34) and the fuel-line drain valve (35) to the humidifier (14). ) is transmitted.

The remaining air used in the air electrode 42 of the fuel cell stack 40 is delivered to the humidifier 14 through an air cut-off valve outlet (16).

The water and remaining air delivered to the humidifier 14 are transferred to the gas-liquid separator 50 and separated into condensate and air. The air separated by the gas-liquid separator 50 is discharged to the outside through an air pressure controller (18). The condensate separated by the gas-liquid separator 50 is discharged to the outside through the condensate discharge valve 60.

At this time, the fuel-line purge valve (36), whose description is omitted, performs the function of controlling the movement of hydrogen or nitrogen provided from the hydrogen electrode 41 of the fuel cell stack 40 during the purge process. .

In order to receive certification for fuel cell systems for ships and stationary power generation, a purge is required to remove remaining hydrogen in the system in situations such as emergency stoppage, maintenance, and long-term stoppage. Conversely, during startup, it is necessary to remove oxygen inside the stack to prevent reverse voltage formation.

The fuel cell system purge control method in the starting procedure is performed as shown in FIG. 2. Figure 2 is an exemplary flowchart showing a start-up procedure among the fuel cell system purge control method according to the present invention, and Figure 3 is a flow chart for removing oxygen from the hydrogen electrode and oxygen electrode during the start-up procedure of the fuel cell system according to the present invention. This is an exemplary diagram showing the flow of nitrogen, and Figure 4 is an exemplary diagram showing the flow of hydrogen and air during the starting procedure of the fuel cell system according to the present invention.

In the following description, the operation of each valve is controlled by a control unit (not shown).

Prior to operating the fuel cell system, nitrogen is supplied (S101) until the oxygen concentration in the air electrode falls below the standard value (S102) in order to discharge the air remaining in the air electrode.

Before starting, the hydrogen remaining in the hydrogen electrode and the oxygen remaining in the air electrode must be discharged out of the system. When the nitrogen supply valve (22) is opened, nitrogen (N ₂ ) is introduced and flows through the open fuel block valve (31) and fuel supply valve (Fuel Supply Valve: 32) to the fuel ejector (Fuel Ejector: 33). ) is transmitted to the hydrogen electrode 41 of the fuel cell stack 40. Nitrogen is delivered to the opened fuel-line purge valve (Fuel-line Purge Valve: 36) through the hydrogen electrode (41). Since the air pressure controller (Air Pressure Controller: 18) is closed and the air cut-off valve outlet (ACV: 16) is open, nitrogen is delivered to the air electrode (42). Nitrogen that has passed through the air gap 42 passes through an open air input valve (ACV: Air Cut-off Valve outlet: 15) to an air cooler (13), an air compressor (12), and a filter (Filter: 11) forms a path that passes through

When nitrogen purge of the hydrogen electrode and air electrode is completed, hydrogen and air are supplied using a stack voltage monitor (not shown) until the voltage of the stack reaches the reference voltage (S104). The nitrogen supply valve 22 is closed, the hydrogen inlet valve 21 is opened to supply hydrogen (H ₂ ) to the hydrogen electrode 41, and the air filter 11 and air compressor ( 12) and the air cooler 13 operate to supply air. The air that has passed through the humidifier 14 is drawn into the air electrode 42 through the air input valve 15, is separated by the gas-liquid separator 15 through the air discharge valve 16, and is separated by the operation of the pressure controller 18. Hydrogen is discharged to the outside of the enclosure (100) (S103).

[Table 1] below shows the open/closed status of each valve during the startup procedure.

movement
situation hydrogen inlet
valve nitrogen
supply
valve FBV
/FSV FPV ACV_in
/ACV_out BPV APC ACP ignition off Closed Closed Closed Closed Closed - Closed Stop nitrogen purge Closed Open Open Open Open Closed Closed Stop hydrogen and
air supply Open Closed Open Open Open Closed Open Operate Fuel cell operation Open Closed Open - Open - Open Operate

Figure 5 is an example flowchart showing a shutdown procedure among the fuel cell system purge control method according to the present invention, Figure 6 is an example diagram showing the flow of nitrogen and air for hydrogen electrode purge, and Figure 7 is an air electrode purge. This is an example diagram showing the flow of nitrogen for.

A purge must be performed when the fuel cell system has been taken out of operation and the shutdown procedure is implemented. The present invention performs a purge operation to discharge hydrogen remaining in the hydrogen electrode and oxygen remaining in the air electrode. In addition, the fuel cell deterioration state is measured and the catalyst reactivation process is performed using an inert gas.

Figure 6 is an exemplary diagram showing the flow of nitrogen and air for hydrogen electrode purge. After completing the operation of the fuel cell system, purge is performed by supplying nitrogen to the hydrogen electrode until the concentration of hydrogen remaining in the hydrogen electrode falls below the standard value (S202) in order to discharge the hydrogen remaining in the hydrogen electrode. If the time required to remove hydrogen in the stack below a certain concentration or the stack voltage standard is satisfied, the hydrogen electrode nitrogen purge can be judged to be complete.

When the nitrogen supply valve (22) is opened, nitrogen (N ₂ ) is introduced and flows through the open fuel block valve (31) and fuel supply valve (Fuel Supply Valve: 32) to the fuel ejector (Fuel Ejector: 33). ) is transmitted to the hydrogen electrode 41 of the fuel cell stack 40. Nitrogen is delivered to the opened fuel-line purge valve (Fuel-line Purge Valve: 36) through the hydrogen electrode (41). Nitrogen gas is discharged as the air pressure controller (18) operates.

The air filter 11, air compressor 12, and air cooler 13 that form the air input path operate to supply air. The air that has passed through the humidifier 14 is drawn into the air electrode 42 through the air input valve 15, is separated by the gas-liquid separator 15 through the air discharge valve 16, and is separated by the operation of the pressure controller 18. Hydrogen is discharged to the outside of the enclosure (100) (S202).

When the hydrogen electrode and nitrogen purge are completed, the nitrogen purge operation of the air electrode is performed. Figure 7 is an exemplary diagram showing the flow of nitrogen for air gap purge. In order to discharge the oxygen remaining in the air electrode, purge is performed by supplying nitrogen to the air electrode (S203) until the concentration of oxygen remaining in the air electrode falls below the standard value (S204).

When the air pressure controller 18 is closed and the air cut-off valve outlet (ACV: 16) is opened, nitrogen is delivered to the air electrode 42. Nitrogen that has passed through the air gap 42 passes through an open air input valve (ACV: Air Cut-off Valve outlet: 15) to an air cooler (13), an air compressor (12), and a filter (Filter: 11) forms a path that passes through The time required to supply nitrogen is required so that the oxygen in the air electrode within the stack can be below a certain concentration.

Among the shutdown procedures of the fuel cell system according to the present invention, FIG. 8 shows the regeneration mode hydrogen supply process, FIG. 9 shows the regeneration mode hydrogen blocking process, and FIG. 10 shows the flows of hydrogen, nitrogen, and air for regeneration mode nitrogen purge. This is an example diagram.

In the present invention, when performing a shutdown procedure, the purge of the hydrogen electrode and the air electrode is completed (S205), and instead of stopping at a simple purge, the cyclic voltammetry method is introduced in the purge process to measure the surface area of the reaction catalyst to prevent deterioration of the fuel cell. The lifespan of the fuel cell can be increased by identifying the extent or introducing a fuel cell performance recovery procedure. That is, in the present invention, a regeneration mode processing process is performed to diagnose the condition of the fuel cell stack and restore performance during the purge process.

Prior to execution of the regeneration mode, the regeneration mode hydrogen supply process of supplying hydrogen to the hydrogen electrode and supplying air for air flow to dilute the discharged hydrogen concentration is performed as shown in FIG. 8. In the regenerative mode hydrogen supply process, hydrogen is supplied to the hydrogen electrode until the hydrogen concentration is greater than the reference value (S207). At this time, the standard concentration of the hydrogen electrode is a value of 99% or more.

When nitrogen is purged to the air electrode, the nitrogen supply valve 22 is closed and the hydrogen supply valve 21 is opened to supply hydrogen to the hydrogen enclosure 100. Hydrogen (H ₂ ) passes through the fuel block valve (31) and the fuel supply valve (32) to the hydrogen electrode (of the fuel cell stack 40) by the fuel ejector (33). 41). Hydrogen that has passed through the hydrogen electrode (41) is discharged to the outside of the hydrogen enclosure (100) by the operation of the air pressure controller (18) through the open fuel-line purge valve (36). .

At this time, the air filter 11, air compressor 12, and air cooler 13 forming the air input path operate to supply air. Since the air input valve 15 is closed, the air that has passed through the humidifier 14 passes through the bypass valve (17) and the gas-liquid separator (15) into the hydrogen enclosure (100) by the operation of the air pressure controller (18). ) is discharged to the outside (S206).

When the standard concentration of the hydrogen electrode reaches 99% or more, the supply of hydrogen is blocked, as shown in FIG. 9. Along with the blockage of hydrogen, the supply of air is cut off. That is, the hydrogen supply valve 21, fuel block valve 31, fuel supply valve 32, and fuel line purge valve 36 are closed, so that the hydrogen electrode 41 is filled with hydrogen, and the air electrode 42 is filled with hydrogen. has a nitrogen-filled state (S208).

In this prepared state, a regeneration mode processing process is performed to diagnose the condition of the fuel cell stack and restore performance.

The effective catalytic reaction area can be calculated by performing cyclic voltammetry with hydrogen at the hydrogen electrode and nitrogen at the air electrode of the fuel cell. Diagnose the deterioration of the fuel cell stack by measuring the reaction catalyst surface area. The reaction catalyst surface area is measured by supplying the fuel cell stack between a lower limit voltage in the range of 0.05V to 1V and an upper limit voltage of 1.2V at a constant voltage rate of 50mV/s. The degree of deterioration can be determined by comparing the calculated catalytic reaction area with the initial value or the status diagnosis value in the previous regeneration mode.

Deterioration of fuel cells can be divided into irreversible deterioration and reversible deterioration. Reversible deterioration can be recovered by specific methods, one of which is the step voltage method.

The step voltage method is a method of applying voltage to the stack by repeatedly cycling the voltage between the lower limit voltage (e.g. 0.4V) and the upper limit voltage (e.g. 1.0V). At this time, the lower the lower limit voltage, the better the effect. However, if oxygen is distributed in the air electrode as in the actual operating environment of a fuel cell, it may induce irreversible bonding with the catalyst and have a negative effect on the durability of the fuel cell.

However, in a situation where there is hydrogen at the hydrogen electrode and nitrogen at the air electrode, there is no need to worry about additional formation of platinum dioxide bonds even if the step voltage method is performed.

Therefore, in the performance recovery process, a step voltage method that periodically repeats the lower limit voltage (e.g., 0.2 V) and the upper limit voltage (e.g., 0.6 V) is performed to recover the reversible performance loss of the fuel cell. Condition diagnosis and performance restoration may alternate or be performed repeatedly. For example, it is possible to perform a condition diagnosis, perform performance recovery, and then perform a condition diagnosis again to determine the degree of performance recovery.

After the regeneration mode is performed, the hydrogen electrode must be purged with nitrogen. When the locked nitrogen supply valve (22) is opened, nitrogen passes through the fuel block valve (31) and the fuel supply valve (32) into the fuel cell stack by the fuel ejector (33). It is transmitted to the hydrogen electrode (41) of (40). Nitrogen that has passed through the hydrogen electrode 41 is discharged to the outside of the hydrogen enclosure 100 by the operation of the air pressure controller 18.

The air from which impurities have been filtered out by the air filter (Filter: 11) is compressed by the air compressor (12), and the temperature is lowered by the air cooler (Air Cooler: 13) to be used in the humidifier (Air Humidifier: 14). Go to Since the air input valve 15 is closed, the air that has passed through the humidifier 14 passes through the bypass valve (17) and the gas-liquid separator (15) into the hydrogen enclosure (100) by the operation of the air pressure controller (18). ) is discharged to the outside. Nitrogen purging after the regeneration mode is achieved by maintaining nitrogen supply until the hydrogen concentration of the hydrogen electrode falls below the standard value (S211). At this time, nitrogen flow continues so that the standard hydrogen concentration of the hydrogen electrode is less than 1% (S210).

[Table 2] below shows the open/closed status of each valve during the start-off process in the purge control device of the fuel cell system according to the present invention.

movement
situation hydrogen
incoming
valve nitrogen
supply
valve FBV
/FSV FPV ACV_in
/ACV_out BPV APC ACP Driving status Open Closed Open - Open - Open Operate Hydrogen purge Closed Open Open Open Open Closed Open Operate Oxygen pole purge Closed Open Open Open Open Closed Closed Stop Purge complete Closed Closed Open Open Closed Closed Closed Stop Regenerative mode hydrogen supply Open Closed Open Open Closed Open Open Operate Regeneration mode hydrogen blocking Closed Closed Closed Closed Closed Open Closed Stop Play mode Closed Closed Closed Closed Closed Open Closed Stop Play mode nitrogen purge Closed Open Open Open Closed Open Open Operate Start-upOff Closed Closed Closed Closed Closed - Closed Stop

As described above, the fuel cell system purge control device and control method connects one nitrogen supply valve to the hydrogen electrode to supply both the hydrogen electrode and the air electrode with nitrogen, an inert gas, and purges nitrogen using a simple system. can do. In addition, beyond simple purging for long-term storage, the side effect of measuring the surface area of the reaction catalyst by introducing the circulating current method in the purging process and extending the lifespan of the fuel cell system through the fuel cell performance recovery procedure can be expected.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

11: air filter 12: air compressor
13: air cooler 14: humidifier
15: air input valve 16: air discharge valve
17: Bypass valve 18: Air pressure controller
21: hydrogen inlet valve 22: nitrogen supply valve
31: fuel block valve 32: fuel supply valve
33: fuel injection unit 34: fuel line water trap
35: Fuel line drain valve 36: Fuel line purge valve
40: fuel cell stack 41: hydrogen electrode
42: air electrode 50: gas-liquid separator
60: Condensate discharge valve 100: Hydrogen enclosure

Claims (16)

fuel cell stack;
a hydrogen supply unit that supplies hydrogen to the hydrogen electrode of the fuel cell stack;
an air supply unit supplying air to the air electrode of the fuel cell stack;
a nitrogen supply unit connected to the hydrogen supply unit to supply purge nitrogen to the hydrogen electrode and air electrode of the fuel cell stack; and
A control unit that purges the fuel cell stack with nitrogen by controlling the opening and closing operations of valves connected to the air supply unit, hydrogen supply unit, and nitrogen supply unit,
The control unit,
After purging the hydrogen electrode and the air electrode with nitrogen gas when the fuel cell stack is turned off, the hydrogen electrode of the fuel cell stack is placed in a hydrogen atmosphere and the air electrode of the fuel cell stack is placed in a nitrogen atmosphere to diagnose the condition of the fuel cell stack and A fuel cell system purge control unit that controls to perform performance recovery. The method of claim 1, wherein the control unit,
A fuel cell system purge control device that diagnoses the deterioration state of the fuel cell stack by measuring the surface area of the reaction catalyst using cyclic voltammetry. The method of claim 2, wherein the control unit,
A fuel cell system purge control device that measures the catalyst surface area by supplying a voltage between a lower limit voltage in the range of 0.05V to 1V and an upper limit voltage of 1.2V to the fuel cell stack at a constant voltage rate of 50mV/s. The method of claim 1, wherein the control unit:
A fuel cell system purge control device that restores deteriorated performance of the fuel cell by supplying voltage to the fuel cell stack using a step voltage method. The method of claim 4, wherein the control unit,
A fuel cell system purge control device that periodically cycles and supplies a voltage between a lower limit voltage of 0.3V and an upper limit voltage of 0.6V to the fuel cell stack. The method of claim 1, wherein the control unit,
A fuel cell system purge control device that controls the hydrogen electrode of the fuel cell stack to be formed into a hydrogen atmosphere with a hydrogen concentration of 99% or more prior to diagnosing the condition of the fuel cell stack and recovering performance. The method of claim 1, wherein the control unit:
A fuel cell system purge control device for controlling nitrogen purge so that the hydrogen concentration of the hydrogen electrode of the fuel cell stack is less than 1% after diagnosing the condition of the fuel cell stack and performing performance recovery. The method of claim 1, wherein the control unit:
A fuel cell system purge control device that purges the hydrogen electrode of the fuel cell stack with nitrogen and then purges the air electrode of the fuel cell stack with nitrogen by controlling the opening and closing operation of the valve connected to the air supply unit. A first purge process of purging the hydrogen electrode of the fuel cell stack with nitrogen when the fuel cell stack is turned off;
A second purge process of purging the air electrode of the fuel cell stack with nitrogen by controlling a valve connected to the fuel cell stack to connect the path of the nitrogen that has passed through the hydrogen electrode of the fuel cell stack to the air electrode of the fuel cell stack;
A regenerative mode process for diagnosing the condition of the fuel cell stack and restoring performance: and
A fuel cell system purge control method comprising a third purge process of purging the hydrogen electrode of the fuel cell stack with nitrogen. The method of claim 9, wherein the play mode processing process is:
A first preparation step of forming the hydrogen electrode of the fuel cell stack in a hydrogen atmosphere;
A second preparation step of forming the air electrode of the fuel cell stack in a nitrogen atmosphere; and
A fuel cell system purge control method comprising a regeneration mode step of diagnosing the status of the stack and restoring performance. The method of claim 10, wherein the first preparation step is,
supplying hydrogen to the hydrogen electrode of the fuel cell stack;
Waiting until the hydrogen concentration of the hydrogen electrode is 99% or more; and
A fuel cell system purge control method comprising blocking hydrogen supplied to the hydrogen electrode of the fuel cell stack. The method of claim 10, wherein the regeneration mode step includes diagnosing a deterioration state of the fuel cell stack by measuring the surface area of the reaction catalyst using cyclic voltammetry. The fuel cell system purge method of claim 12, wherein the reaction catalyst surface area measurement process is measured by supplying the fuel cell stack between a lower limit voltage in the range of 0.05V to 1V and an upper limit voltage of 1.2V at a constant voltage rate of 50mV/s. Control method. The fuel cell system purge control method of claim 10, wherein the regeneration mode step includes restoring deteriorated performance of the fuel cell stack by supplying voltage to the fuel cell stack using a step voltage method. The fuel cell system purge control method of claim 14, wherein a voltage between a lower limit voltage of 0.3V and an upper limit voltage of 0.6V is periodically and repeatedly supplied to the fuel cell stack to restore performance of the fuel cell stack. The fuel cell system purge control method of claim 9, wherein the third purge process controls nitrogen purge so that the hydrogen concentration of the hydrogen electrode of the fuel cell stack is less than 1%.