KR20240016691A - Fuel cell system and flushing control method thereof - Google Patents

Abstract

A fuel cell system according to an embodiment of the present invention includes a hydrogen supply valve that regulates the supply of hydrogen on a hydrogen supply line connecting a hydrogen tank and a fuel cell stack, a purge valve that discharges hydrogen from the hydrogen electrode of the fuel cell stack, and detecting the separation history of the hydrogen supply pipe before starting the fuel cell stack, and controlling the hydrogen supply valve and the purge valve to perform flushing of the hydrogen electrode of the fuel cell stack when the separation history of the hydrogen supply pipe is detected. Includes a controller that

Description

Fuel cell system and its flushing control method {FUEL CELL SYSTEM AND FLUSHING CONTROL METHOD THEREOF}

The present invention relates to a fuel cell system and its flushing control method.

A fuel cell system can generate electrical energy using a fuel cell stack. For example, if hydrogen is used as a fuel for a fuel cell stack, it can be an alternative to solving global environmental problems, so continuous research and development is being conducted on fuel cell systems.

The fuel cell system consists of a fuel cell stack that generates electrical energy, a fuel supply device that supplies fuel (hydrogen) to the fuel cell stack, an air supply device that supplies oxygen from the air, an oxidizing agent necessary for electrochemical reactions, to the fuel cell stack, and fuel. A thermal management system (TMS) that removes the reaction heat of the cell stack to the outside of the system, controls the operating temperature of the fuel cell stack, and performs a water management function, and a fuel cell system controller that controls the overall operation of the fuel cell system. It can be included.

In a fuel cell system, electricity is generated by reacting hydrogen as a fuel with oxygen in the air in the fuel cell stack, and heat and water are discharged as reaction by-products.

These fuel cell systems can be divided into through-type, dead-end, and recirculating types depending on the hydrogen supply method. Here, fuel cells for power generation mainly use the penetrating method because foreign substances generated during the reforming process, such as carbon monoxide, can infiltrate, and mobile fuel cells mainly use the dead end method or recirculation method because they are used by charging pure hydrogen. Among equipment equipped with mobile fuel cells, small unmanned aerial vehicles use the dead end method, which has a simple configuration and is light in weight, while automobiles and construction equipment mainly use the recirculation method, which can prevent flushing even during high output and various output fluctuations. do.

In particular, the dead end method and the recirculation method do not have an outlet at the hydrogen electrode, so if foreign substances penetrate the hydrogen electrode, natural discharge of the foreign substances is not possible until flushing (purge). This causes a decrease in hydrogen concentration, which reduces the performance and lifespan of the fuel cell, so it is important to prevent the inflow of foreign substances. Accordingly, in order to prevent foreign substances from infiltrating when supplying hydrogen, a fixed hydrogen tank is generally designed so that the piping from the hydrogen tank to the fuel cell is not separated.

Meanwhile, because it is sometimes difficult for unmanned aerial vehicles to access hydrogen charging stations while moving, exchangeable hydrogen tanks are being installed. Accordingly, when replacing the hydrogen tank of an unmanned aerial vehicle, the inflow of foreign substances through the hydrogen supply pipe is inevitable. Of course, foreign substances are discharged through purge control, but frequent purging during operation of the fuel cell stack reduces fuel efficiency due to excessive hydrogen emissions.

The purpose of an embodiment of the present invention is to detect separation history that allows foreign substances to be introduced into the hydrogen supply pipe before starting the fuel cell, and to discharge the foreign substances by continuously flushing the hydrogen electrode according to the detection results. To provide a fuel cell system and its flushing control method that prevent performance degradation of the fuel cell stack.

Another object according to an embodiment of the present invention is to classify the hydrogen supply pipe into a plurality of zones, detect the separation history of the hydrogen supply pipe for each zone, and determine the flushing volume and hydrogen electrode based on the zone in which the separation history was detected. The present invention provides a fuel cell system that prevents excessive hydrogen emissions by calculating hydrogen concentration and performing flushing, and a method for controlling its flushing.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

A fuel cell system according to an embodiment of the present invention includes a hydrogen supply valve that regulates the supply of hydrogen on a hydrogen supply line connecting a hydrogen tank and a fuel cell stack, a purge valve that discharges hydrogen from the hydrogen electrode of the fuel cell stack, and detecting the separation history of the hydrogen supply pipe before starting the fuel cell stack, and controlling the hydrogen supply valve and the purge valve to perform flushing of the hydrogen electrode of the fuel cell stack when the separation history of the hydrogen supply pipe is detected. Includes a controller that

In one embodiment, the controller divides the hydrogen supply line connecting the hydrogen tank and the fuel cell stack into a plurality of zones, and detects the separation history of the hydrogen supply pipe for each divided zone. .

In one embodiment, the hydrogen supply line is a first zone that detects the separation history of the hydrogen supply pipe due to replacement of the hydrogen tank between the hydrogen tank and the hydrogen tank valve, and the hydrogen supply line between the hydrogen tank valve and the hydrogen tank supply valve. A second zone detecting the separation history of the hydrogen supply pipe due to replacement of the tank cartridge, a third zone detecting the separation history of the hydrogen supply pipe due to replacement of the pressure sensor between the hydrogen tank supply valve and the hydrogen shutoff valve, and the hydrogen A fourth zone detecting a history of separation of the hydrogen supply pipe due to replacement of the pipe between the blocking valve and the hydrogen supply valve, and separation of the hydrogen supply pipe due to replacement of the fuel cell stack between the hydrogen supply valve and the fuel cell stack. It is characterized by being classified into the 5th zone that detects history.

In one embodiment, the controller, when the value obtained by subtracting the pressure of the hydrogen tank during the previous operation from the current pressure of the hydrogen tank exceeds the preset first reference pressure, removes the hydrogen tank from the first zone or the second zone. It is characterized by detecting the history of separation of the hydrogen supply pipe due to replacement of the tank.

In one embodiment, when the controller detects a history of separation of the hydrogen supply pipe due to replacement of the hydrogen tank in the first zone or the second zone, flushing corresponding to the volume of the hydrogen supply pipe in the second zone It is characterized by setting the volume.

In one embodiment, the controller detects the hydrogen supply pressure sensor in the third zone when the pressure measured by the hydrogen supply pressure sensor disposed on the hydrogen supply line in the third zone is less than the preset second reference pressure. It is characterized by detecting the history of separation of the hydrogen supply pipe due to replacement.

In one embodiment, when a separation history of the hydrogen supply pipe due to replacement of the hydrogen supply pressure sensor is detected in the third zone, the controller sets the flushing volume in response to the volume of the hydrogen supply pipe in the third zone. It is characterized by:

In one embodiment, the controller opens the hydrogen shutoff valve when the separation history of the hydrogen supply pipe is not detected in the third zone (Z3), and uses a hydrogen supply pressure sensor before opening the hydrogen shutoff valve. If the value obtained by subtracting the pressure measured by the hydrogen supply pressure sensor after opening the hydrogen shutoff valve from the measured pressure exceeds the preset third reference pressure, the hydrogen supply pipe due to pipe replacement in the fourth zone It is characterized by detecting separation history.

In one embodiment, the controller is characterized in that, when a history of separation of the hydrogen supply pipe due to pipe replacement in the fourth zone is detected, the flushing volume is set in response to the volume of the hydrogen supply pipe in the fourth zone. .

In one embodiment, when the separation history of the hydrogen supply pipe is not detected in the first to fourth zones, the controller opens the valve disposed on the air supply line and the hydrogen supply line to form the fuel cell stack. supplies air and hydrogen, and when the value obtained by subtracting the stack measurement voltage from the stack reference voltage exceeds the preset reference voltage, the separation history of the hydrogen supply pipe due to replacement of the fuel cell stack is detected in the fifth zone. It is characterized by

In one embodiment, when a separation history of the hydrogen supply pipe due to replacement of the fuel cell stack is detected in the fifth zone, the controller sets the flushing volume corresponding to the volume of the hydrogen supply pipe in the fifth zone. It is characterized by

In one embodiment, when the controller detects a history of separation of the hydrogen supply pipe in one or more of the divided zones, the controller supplies the hydrogen until the pressure of the hydrogen electrode of the fuel cell stack reaches a preset upper operating limit pressure. The valve is opened to supply hydrogen to the hydrogen electrode.

In one embodiment, the controller, when the pressure of the hydrogen electrode exceeds the upper operating limit pressure, blocks the hydrogen supply valve and opens the purge valve to perform hydrogen purge.

In one embodiment, the controller calculates the hydrogen concentration of the hydrogen electrode based on the flushing volume, and operates the hydrogen supply valve and the purge valve until the calculated hydrogen concentration of the hydrogen electrode exceeds the reference concentration. It is characterized in that flushing of the hydrogen electrode of the fuel cell stack is performed continuously by repetitive control.

In one embodiment, the controller terminates flushing of the hydrogen electrode and starts the fuel cell stack when the calculated hydrogen concentration of the hydrogen electrode exceeds the reference concentration.

In one embodiment, the hydrogen tank is characterized as an exchangeable hydrogen tank.

In one embodiment, the fuel cell stack is characterized by a dead end type in which the fuel cell stack is operated with the discharge passage of the air electrode blocked.

In addition, the flushing control method of the fuel cell system according to an embodiment of the present invention includes detecting the separation history of the hydrogen supply pipe before starting the fuel cell stack, and when the separation history of the hydrogen supply pipe is detected, the hydrogen tank And performing flushing of the hydrogen electrode of the fuel cell stack by controlling a hydrogen supply valve that regulates the supply of hydrogen on the hydrogen supply line connecting the fuel cell stack and a purge valve that discharges hydrogen from the hydrogen electrode of the fuel cell stack. It includes steps to:

In one embodiment, the step of detecting the separation history of the hydrogen supply pipe includes dividing the hydrogen supply line connecting the hydrogen tank and the fuel cell stack into a plurality of zones, and dividing the hydrogen supply line into a plurality of zones for each divided zone. Detecting the separation history, and when the separation history of the hydrogen supply pipe is detected in one or more of the divided zones, setting the flushing volume corresponding to the volume of the hydrogen supply pipe in the corresponding zone. do.

In one embodiment, the step of performing flushing of the hydrogen electrode of the fuel cell stack includes, when a separation history of the hydrogen supply pipe is detected in one or more of the divided zones, the pressure of the hydrogen electrode of the fuel cell stack is increased. Supplying hydrogen to the hydrogen electrode by opening the hydrogen supply valve until the set operating upper limit pressure is reached; when the pressure of the hydrogen electrode exceeds the operating upper limit pressure, blocking the hydrogen supply valve, and shutting off the purge valve performing a hydrogen purge by opening, calculating the hydrogen concentration of the hydrogen electrode based on the flushing volume, and purging the hydrogen supply valve and the purge until the calculated hydrogen concentration of the hydrogen electrode exceeds the standard concentration. Continuously performing flushing of the hydrogen electrode of the fuel cell stack by repeatedly controlling a valve, and terminating flushing of the hydrogen electrode when the calculated hydrogen concentration of the hydrogen electrode exceeds a reference concentration. It is characterized by

In one embodiment, the flushing control method of the fuel cell system according to the present invention further includes the step of starting the fuel cell stack when flushing of the hydrogen electrode is completed.

According to one embodiment of the present invention, the separation history that allows foreign substances to be introduced into the hydrogen supply pipe is detected before starting the fuel cell, and the foreign substances are discharged through continuous flushing of the hydrogen electrode according to the detection results, thereby reducing the performance of the fuel cell stack. There is a preventable effect.

In addition, according to an embodiment of the present invention, the hydrogen supply pipe is classified into a plurality of zones, the separation history of the hydrogen supply pipe is detected for each zone, and the hydrogen concentration of the hydrogen electrode is calculated based on the zone in which the separation history was detected. This has the effect of preventing excessive hydrogen discharge by performing flushing.

1 is a diagram illustrating a fuel cell system according to an embodiment of the present invention.
Figure 2 is a diagram illustrating a foreign matter input event that may occur in a hydrogen supply pipe according to an embodiment of the present invention.
Figure 3 is a diagram showing the detection zone of a hydrogen supply pipe according to an embodiment of the present invention.
Figure 4 is a diagram showing a control block diagram of a fuel cell system according to an embodiment of the present invention.
Figure 5 is a diagram defining the flushing volume according to the detection history for each section of the hydrogen supply pipe according to an embodiment of the present invention.
6A and 6B are diagrams showing changes in hydrogen concentration in a fuel cell system according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating the operation flow of a flushing control method of a fuel cell system according to an embodiment of the present invention.
Figure 8 is a diagram showing the flow of a separation history detection operation of a hydrogen supply pipe according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through illustrative drawings. When adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, when describing embodiments of the present invention, if detailed descriptions of related known configurations or functions are judged to impede understanding of the embodiments of the present invention, the detailed descriptions will be omitted.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, sequence, or order of the component is not limited by the term. Additionally, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted in an ideal or excessively formal sense unless explicitly defined in the present application. No.

1 is a diagram illustrating a fuel cell system according to an embodiment of the present invention.

Referring to FIG. 1, the fuel cell system includes a fuel cell stack 100, a hydrogen supply line connected to the hydrogen electrode of the fuel cell stack 100 through which hydrogen supplied to the fuel cell stack 100 moves, and a fuel An air supply line that is connected to the air electrode of the battery stack 100 and moves the air supplied to the fuel cell stack 100, a discharge line and a purge line for discharging moisture (water) or unreacted gas, which is a reaction by-product, to the outside. It may further include.

The fuel cell stack 100 (or may be referred to as a ‘fuel cell’) is a structure capable of producing electricity through a redox reaction between fuel (e.g., hydrogen) and an oxidizing agent (e.g., air). It can be formed as

As an example, the fuel cell stack 100 is a membrane electrode assembly (MEA) with catalyst electrode layers where electrochemical reactions occur on both sides of the electrolyte membrane through which hydrogen ions move, and evenly distributes the reaction gases. A gas diffusion layer (GDL) that plays a role in transferring the generated electrical energy, a gasket and fastening device to maintain airtightness and appropriate fastening pressure of the reaction gases and coolant, and a gasket and fastener that moves the reaction gases and coolant. It may include a bipolar plate.

In the fuel cell stack 100, hydrogen as a fuel and air (oxygen) as an oxidizing agent are supplied to the anode and cathode of the membrane electrode assembly through the flow path of the separator, respectively, and hydrogen is supplied to the anode, which is the hydrogen electrode. And air can be supplied to the cathode, which is the air electrode.

The hydrogen supplied to the anode is decomposed into hydrogen ions (protons) and electrons (electrons) by the catalyst in the electrode layer formed on both sides of the electrolyte membrane, and only hydrogen ions are selectively passed through the electrolyte membrane, which is a cation exchange membrane, and transferred to the cathode. At the same time, electrons can be transferred to the cathode through the conductive gas diffusion layer and separator plate.

At the cathode, hydrogen ions supplied through the electrolyte membrane and electrons transferred through the separator meet oxygen in the air supplied to the cathode by the air supply device, causing a reaction to generate water. Due to the movement of hydrogen ions that occurs at this time, a flow of electrons occurs through the external conductor, and current can be generated through this flow of electrons.

As an example, the fuel cell stack 100 may be a dead end type that operates with the cathode discharge path blocked.

The hydrogen supply line is a line connecting the hydrogen tank 110 and the hydrogen electrode of the fuel cell stack. The hydrogen supply line includes a hydrogen tank 110, a hydrogen tank valve (Hydrogen Valve, HV) 112, and a check valve for hydrogen charging. (Hydrogen Check Valve, HCV) (114), Hydrogen Supply Valve (HSV) (116), Hydrogen Supply Pressure Regulating Valve (PRV) (118), Hydrogen Supply Pressure Sensor (Medium Pressure Sensor) , MP) (119), hydrogen cut-off valve (FCV) (120), hydrogen supply valve (FSV) (122), hydrogen ejector (Fuel Ejector, FEJ) (124), etc. can be placed.

The hydrogen tank 110 is a hydrogen reservoir that stores hydrogen supplied to the hydrogen electrode of the fuel cell stack 100, and may be provided in plural numbers. Here, the hydrogen tank 110 is an exchangeable hydrogen tank, and it is possible to exchange an individual hydrogen tank 110 with a fully charged hydrogen tank or replace a cartridge connected to a plurality of hydrogen tanks 110.

A hydrogen tank valve (HV) 112 may be placed at the outlet of each hydrogen tank 110. Here, the hydrogen tank valve (HV) 112 can control the amount of hydrogen supplied from each hydrogen tank 110 or the amount of hydrogen introduced through the charging port.

Meanwhile, each hydrogen tank 110 may be filled with hydrogen introduced through a charging port. At this time, a hydrogen charging check valve (HCV) 114 is disposed at the charging port, and serves to control the hydrogen for charging supplied through the charging port.

The hydrogen tank supply valve (HSV) 116 serves to control the amount of hydrogen supplied from the plurality of hydrogen tanks 110 to the hydrogen electrode.

The hydrogen supply pressure control valve (PRV) 118 serves to control the pressure of hydrogen supplied to the hydrogen electrode of the fuel cell stack 100. If the pressure of hydrogen flowing into the fuel cell stack 100 is high, internal rupture and damage may occur, so management of the pressure of the supplied hydrogen is very important. Accordingly, when the hydrogen supply pressure sensor (MP) 119 measures the pressure of hydrogen supplied to the fuel cell stack 100 through the hydrogen supply line, the hydrogen supply pressure control valve (PRV) 118 is a hydrogen supply pressure sensor. (MP) Adjusts the pressure of hydrogen supplied through the hydrogen supply line based on the hydrogen pressure measured by (119).

The hydrogen blocking valve (FCV) 120 is disposed between the hydrogen tank 110 and the hydrogen supply valve (FSV) 122 in the hydrogen supply line, and the hydrogen discharged from the hydrogen tank 110 is stored in the fuel cell stack 100. It serves to block the supply to the The hydrogen cut-off valve (FCV) 120 may be controlled to be open when the fuel cell system is started in an On state and closed when the fuel cell system is started in an Off state.

The hydrogen supply valve (FSV) 122 is disposed between the hydrogen cutoff valve (FCV) 120 and the hydrogen ejector (FEJ) 124 in the hydrogen supply line, and controls the hydrogen pressure supplied to the fuel cell stack 100. It plays a role. For example, the hydrogen supply valve (FSV) 122 may be controlled to open to supply hydrogen when the pressure of the hydrogen supply line decreases and to close when the pressure of the hydrogen supply line increases.

The hydrogen ejector (FEJ) 124 is placed between the hydrogen supply valve (FSV) 122 and the fuel cell stack 100 in the hydrogen supply line, and applies pressure to the hydrogen that has passed through the hydrogen supply valve (FSV) 122. It serves to supply it to the fuel cell stack 100.

The hydrogen supply line can form a hydrogen circulation route by connecting the outlet of the fuel cell stack 100 and the hydrogen ejector (FEJ) 124. Therefore, the hydrogen discharged by the hydrogen ejector (FEJ) 124 is reflected with the air within the fuel cell stack 100 to generate electrical energy, and the unreacted hydrogen is discharged through the outlet of the fuel cell stack 100. It may be re-introduced to the hydrogen ejector (FEJ) (124). In this case, the unreacted hydrogen is re-introduced to the hydrogen ejector (FEJ) 124 and supplied back to the fuel cell stack 100 to increase the hydrogen reaction efficiency.

In the process of recirculating unreacted hydrogen at the hydrogen electrode of the fuel cell stack 100, moisture present in the hydrogen supply line may be condensed. At this time, the condensed water (condensate) is transferred to a point on the hydrogen supply line where unreacted hydrogen moves from the hydrogen electrode of the fuel cell stack 100 to the hydrogen ejector (FEJ) 124 and to the air humidifier (AHF) ( It can be discharged through the first discharge line connecting 130).

A water trap (Fuel Water Trap, FWT) 136 and a drain valve (Fuel Drain Valve, FDV) 138 may be disposed on the first discharge line.

The water trap (FWT) 136 serves to store condensate flowing into the first discharge line at one point of the hydrogen supply line.

The drain valve (FDV) 138 serves to discharge condensate stored in the water trap (FWT) 136 to the humidifier (AHF) 130 along the first discharge line. Here, the drain valve (FDV) 138 is closed until the condensate stored in the water trap (FWT) 136 exceeds a certain level, and the condensate stored in the water trap (FWT) 136 exceeds a certain level. This can be controlled to open and discharge condensate along the first discharge line.

An air compressor (ACP) 132, a humidifier (AHF) 130, and an air cut-off valve (ACV) 128 may be installed in the air supply line.

The air compressor (ACP) 132 is disposed between the air intake port that sucks in external air (ambient air) from the air supply line and the humidifier (AHF) 130, sucks in external air, compresses it, and supplies compressed air. It plays a role.

The humidifier (AHF) 130 is disposed between the air compressor (ACP) 132 and the air shutoff valve (ACV) 128 in the air supply line, and uses the air sucked and compressed by the air compressor (ACP) 132. It serves to control the humidity and supply it to the air electrode of the fuel cell stack 100. When air compressed by an air compressor (ACP) 132 is introduced into the inlet of the humidifier (AHF) 130, the humidity can be adjusted by supplying moisture to the introduced air. As an example, the humidifier (AHF) 130 is supplied to the condensate introduced through the first discharge line or the air discharged through the second discharge line connecting the air electrode of the fuel cell stack 100 and the humidifier (AHF) 130. The air supplied from the air compressor (ACP) 132 can be humidified using the contained moisture.

The humidifier (AHF) 130 may be connected to the first discharge line. Accordingly, the humidifier (AHF) 130 can supply moisture to the air supplied from the air compressor (ACP) 132 using condensed water introduced through the first discharge line.

In addition, the humidifier (AHF) 130 is connected to the air outlet of the fuel cell stack 100 through a second discharge line, and the air discharged from the air electrode of the fuel cell stack 100 is discharged to the humidifier (AHF) through the second discharge line. AHF) (130). Here, because the air discharged from the air electrode of the fuel cell stack 100 contains moisture, the humidifier (AHF) 130 combines the air discharged from the air electrode of the fuel cell stack 100 with the air compressor (ACP) 132. Humidification is achieved by exchanging moisture in the air supplied from ). In this way, the air supplied with moisture by the humidifier (AHF) 130 flows into the air electrode of the fuel cell stack 100, reacts with hydrogen, and then generates water.

Meanwhile, the humidifier (AHF) 130 is connected to an external outlet through a third discharge line, and discharges air introduced through the second discharge line to the outside through the third discharge line. At this time, an air pressure controller (APC) 134 may be placed in the third discharge line.

The air cut-off valve (ACV) 128 is disposed on the air supply line connecting the fuel cell stack 100 and the humidifier (AHF) 130, and allows hydrogen discharged from the humidifier (AHF) 130 to flow to the fuel cell stack. Supply to the air electrode of 100 can be blocked, or the pressure of air supplied to the air electrode of the fuel cell stack 100 can be adjusted. As an example, the air shutoff valve (ACV) 128 may be controlled to be open when the fuel cell system is started in an On state and closed when the fuel cell system is started in an Off state.

Additionally, the air shutoff valve (ACV) 128 may be connected to a second discharge line connecting the fuel cell stack 100 and the humidifier (AHF) 130. The air shutoff valve (AC) 128 blocks the air discharged from the air electrode of the fuel cell stack 100 from being supplied to the humidifier (AHF) 130 through the second discharge line, or blocks the air discharged from the air electrode of the fuel cell stack 100. The pressure of the air discharged from the air electrode to the humidifier (AHF) 130 can be adjusted.

In Figure 1, the air shutoff valve (ACV) 128 is shown to be integrated in the air supply line and the second discharge line, but the first air shutoff valve (not shown) and the second discharge line are disposed on the air supply line. The second air blocking valves (not shown) disposed on the top may be implemented in separate forms.

Meanwhile, a purge line is connected to a point on the hydrogen supply line where hydrogen supplied from the hydrogen ejector (FEJ) 124 to the hydrogen electrode of the fuel cell stack 100 moves, and a purge valve (Fuel-line Purge) is installed on the purge line. Valve, FPV) (126) can be placed.

The purge valve (FPV) 126 is a valve that opens and closes to manage the hydrogen concentration of the fuel cell stack 100 and the hydrogen supply line, and maintains the hydrogen concentration of the fuel cell stack 100 and the hydrogen supply line within a predetermined range. It plays a role in enabling

The fuel cell stack 100 generates electrical energy by generating hydrogen and air, and the purge valve (FPV) 126 is closed while the fuel cell stack 100 is operated in a normal state.

Here, the air supplied to the fuel cell stack 100 contains nitrogen in addition to oxygen, and a crossover occurs due to the difference in nitrogen partial pressure between the hydrogen electrode and the air electrode, resulting in a decrease in cell voltage. Accordingly, the purge valve (FPV) 126 discharges residual hydrogen to increase the hydrogen concentration in the hydrogen electrode, thereby lowering the nitrogen concentration to maintain stack performance. The purge valve (FPV) 126 is opened when the charge calculated by integrating the current generated during a predetermined period in the fuel cell stack 100 exceeds the target charge amount to purge the hydrogen so that the hydrogen concentration in the hydrogen electrode is greater than a predetermined amount. It can be controlled to maintain.

Figure 2 is a diagram showing a foreign matter input event that may occur in a hydrogen supply pipe according to an embodiment of the present invention, and Figure 3 is a diagram showing a detection zone of a hydrogen supply pipe according to an embodiment of the present invention.

Referring to FIG. 2, since the fuel cell system according to an embodiment of the present invention uses an exchangeable hydrogen tank 110, foreign substances may flow into the hydrogen supply pipe during the process of replacing the hydrogen tank 110. There is a possibility that Accordingly, the fuel cell system can detect whether a hydrogen tank separation event (E1) or a cartridge separation event (E2) of the hydrogen tank 110 occurs.

Additionally, in the fuel cell system, there may be a possibility that foreign substances may flow into the hydrogen supply pipe during the process of replacing the pressure sensor, hydrogen supply pipe, or fuel cell stack. Accordingly, the fuel cell system can detect whether a pressure sensor separation event (E3), a hydrogen supply pipe separation event (E4), or a fuel cell stack separation event (E5) occurs.

Here, in order to easily detect each separation event (E1 to E5), the fuel cell system can classify the hydrogen supply line into a plurality of detection zones and detect whether a separation event occurs in each zone.

As shown in FIG. 3, a hydrogen tank separation event (E1) may occur between the hydrogen tank 110 and the hydrogen tank valve (HV) 112. Accordingly, the fuel cell system may classify the area between the hydrogen tank 110 and the hydrogen tank valve (HV) 112 as the first area (Z1) for detecting the hydrogen tank separation event (E1).

Additionally, a cartridge separation event (E2) of the hydrogen tank 110 may occur between the hydrogen tank valve (HV) 112 and the hydrogen tank supply valve (HSV) 116. Therefore, the fuel cell system uses the area between the hydrogen tank valve (HV) 112 and the hydrogen tank supply valve (HSV) 116 as a second area ( It can be classified as Z2).

Additionally, a pressure sensor separation event (E3) may occur between the hydrogen tank supply valve (HSV) 116 and the hydrogen shutoff valve (FCV) 120. Therefore, the fuel cell system may classify the area between the hydrogen tank supply valve (HSV) 116 and the hydrogen shut-off valve (FCV) 120 as the third zone (Z3) for detecting the pressure sensor separation event (E3). You can.

Additionally, a supply pipe separation event (E4) may occur between the hydrogen cutoff valve (FCV) 120 and the hydrogen supply valve (FSV) 122. Therefore, the fuel cell system can classify the area between the hydrogen cutoff valve (FCV) 120 and the hydrogen supply valve (FSV) 122 as the fourth zone (Z4) for detecting the supply pipe separation event (E4). there is.

Additionally, a fuel cell stack separation event (E5) may occur between the hydrogen supply valve (FSV) 122 and the fuel cell stack 100. Accordingly, the fuel cell system may classify the area between the hydrogen supply valve (FSV) 122 and the fuel cell stack 100 as a fifth zone (Z5) for detecting the fuel cell stack separation event (E5). Here, since the hydrogen ejector (FEJ) 124 disposed on the hydrogen supply line between the hydrogen supply valve (FSV) 122 and the fuel cell stack 100 is always open, it may not be considered in zone classification.

In the embodiment of the present invention, five events (E1 to E5) for separating the hydrogen supply pipe are mentioned as examples, but the present invention is not limited thereto.

Accordingly, the fuel cell system can detect the separation history of the hydrogen supply pipe for each zone, determine the flushing volume and hydrogen concentration of the hydrogen electrode corresponding to the zone where the separation history of the hydrogen supply pipe was detected, and determine the hydrogen concentration of the determined hydrogen electrode. Depending on the concentration, hydrogen electrode flushing may be performed before starting the fuel cell stack 100. Here, flushing is an operation of injecting hydrogen into the hydrogen electrode and purging it. By repeatedly injecting and purging hydrogen into the hydrogen electrode before starting the fuel cell stack 100, foreign substances are discharged and the hydrogen concentration of the hydrogen electrode is increased. You can do it.

Figure 4 is a diagram showing a control block diagram of a fuel cell system according to an embodiment of the present invention. Referring to FIG. 4, the fuel cell system may include a sensor 410 and a controller 450.

The detection unit 410 may include a plurality of sensors that detect the status of each component of the fuel cell system and the operating status between each component.

As an example, the detection unit 410 includes a sensor that detects the pressure and temperature of the hydrogen tank 110, a sensor that detects the pressure, temperature, and flow rate of hydrogen in the hydrogen supply pipe, and a sensor that detects the pressure and temperature of hydrogen in the fuel cell stack. , a sensor that detects concentration, etc. Additionally, the detection unit 410 may further include a sensor that detects the pressure and temperature of air within the fuel cell stack. In addition, the detection unit 410 may further include a sensor that detects the state of each component disposed on the line through which hydrogen and air move in the fuel cell system, for example, the open or blocked state of the valve.

The controller 450 is connected to each component of the fuel cell system and can perform the overall function of the fuel cell system. Here, the control unit 430 may be a hardware device such as a processor or central processing unit (CPU), or a program implemented by the processor.

Before starting the fuel cell system, the controller 450 detects the separation history of the hydrogen supply pipe for each zone classified as shown in FIG. 3 and sets the flushing volume based on the volume of the hydrogen supply pipe for each detected zone. Refer to the embodiment of FIG. 5 for the flushing volume according to the separation history detection results of the hydrogen supply pipe for each zone.

Figure 5 is a diagram defining the flushing volume according to the detection history for each section of the hydrogen supply pipe according to an embodiment of the present invention. Referring to FIGS. 3 and 5, the controller 450 detects the history of separation of the hydrogen supply pipe due to replacement of the hydrogen tank 110 in the first zone (Z1) or the second zone (Z2).

Here, the controller 450 determines whether the value obtained by subtracting the pressure of the hydrogen tank 110 during the previous operation from the current pressure of the hydrogen tank 110 exceeds the preset first reference pressure (P1). At this time, the controller 450 operates in the first zone (Z1) when the value obtained by subtracting the pressure of the hydrogen tank 110 during the previous operation from the current pressure of the hydrogen tank 110 exceeds the preset first reference pressure (P1). Alternatively, it is determined that the history of separation of the hydrogen supply pipe due to replacement of the hydrogen tank 110 in the second zone (Z2) has been detected. When the separation history of the hydrogen supply pipe in the first zone (Z1) or the second zone (Z2) is detected, the controller 450 responds to the volume (V2) of the hydrogen supply pipe in the second zone (Z2) and the flushing volume ( Set Vp) to 'V2'.

Meanwhile, the controller 450 operates in the first zone ( It is determined that no history of separation of the hydrogen supply pipe was detected in Z1) or the second zone (Z2). In this way, when the separation history of the hydrogen supply pipe is not detected in the first zone (Z1) or the second zone (Z2), the controller 450 sets the flushing volume (Vp) to '0'.

Additionally, the controller 450 detects the history of separation of the hydrogen supply pipe due to replacement of the hydrogen supply pressure sensor (MP) 119 in the third zone (Z3). Here, the controller 450 determines whether the pressure measured by the hydrogen supply pressure sensor (MP) 119 is less than the preset second reference pressure (P2). At this time, the controller 450 detects the separation history of the hydrogen supply pipe in the third zone (Z3) if the pressure measured by the hydrogen supply pressure sensor (MP) 119 is less than the preset second reference pressure (P2). decide that

When the separation history of the hydrogen supply pipe in the third zone (Z3) is detected, the controller 450 sets the flushing volume (Vp) in response to the volume (V3) of the hydrogen supply pipe in the third zone (Z3). If a history of separation of the hydrogen supply pipe in the first zone (Z1) or the second zone (Z2) has been detected, the previously set flushing volume (Vp) is added to the volume of the hydrogen supply pipe in the third zone (Z3) ( You can set it as 'V2+V3' by adding V3). Of course, if the separation history of the hydrogen supply pipe is not detected in the first zone (Z1) or the second zone (Z2), the flushing volume (Vp) corresponds to the volume (V3) of the hydrogen supply pipe in the third zone (Z3). ) can be set to 'V3'.

Here, when the separation history of the hydrogen supply pipe is detected in the third zone (Z3), the controller 450 will not detect the separation history of the hydrogen supply pipe in the fourth zone (Z4) and the fifth zone (Z5). You can.

Meanwhile, if the pressure measured by the hydrogen supply pressure sensor (MP) 119 is not less than the preset second reference pressure (P2), the controller 450 determines the separation history of the hydrogen supply pipe in the third zone (Z3). Determine that it is not detected. In this way, when the separation history of the hydrogen supply pipe is not detected in the third zone (Z3), the flushing volume (Vp) is set to '0'. If a history of separation of the hydrogen supply pipe is previously detected in the first zone (Z1) or the second zone (Z2), the previously set flushing volume (Vp) 'V2' can be maintained.

Additionally, the controller 450 detects the history of separation of the hydrogen supply pipe due to replacement of the hydrogen supply pipe in the fourth zone (Z4). Here, before detecting the separation history of the hydrogen supply pipe in the fourth zone (Z4), the controller 450 opens the hydrogen blocking valve (FCV) 120 while blocking the hydrogen supply valve (FSV) 122. Open. At this time, the controller 450 opens the hydrogen shutoff valve (FCV) 120 at the pressure measured by the hydrogen supply pressure sensor (MP) 119 before opening the hydrogen shutoff valve (FCV) 120. If the value minus the pressure measured by the supply pressure sensor (MP) 119 exceeds the preset third reference pressure (P3), it is determined that the separation history of the hydrogen supply pipe in the fourth zone (Z4) has been detected. do.

When the separation history of the hydrogen supply pipe in the fourth zone (Z4) is detected, the controller 450 sets the flushing volume (Vp) in response to the volume (V4) of the hydrogen supply pipe in the fourth zone (Z4). If a history of separation of the hydrogen supply pipe in the first zone (Z1) or the second zone (Z2) was previously detected, the previously set flushing volume (Vp) is added to the volume of the hydrogen supply pipe in the fourth zone (Z4) ( You can set it as 'V2+V4' by adding V4). Of course, if the separation history of the hydrogen supply pipe is not detected in the first zone (Z1) or the second zone (Z2), the flushing volume (Vp) corresponding to the volume (V4) of the hydrogen supply pipe in the fourth zone (Z4) ) can be set to 'V4'.

Here, when the separation history of the hydrogen supply pipe is detected in the fourth zone (Z4), the controller 450 may not detect the separation history of the hydrogen supply pipe in the fifth zone (Z5).

Meanwhile, the controller 450 opens the hydrogen supply valve (FSV) 122 at the pressure measured by the hydrogen supply pressure sensor (MP) 119 before opening the hydrogen supply valve (FSV) 122. If the value minus the pressure measured by the supply pressure sensor (MP) 119 does not exceed the preset third reference pressure (P3), the separation history of the hydrogen supply pipe is not detected in the fourth zone (Z4). decide that In this way, when the separation history of the hydrogen supply pipe is not detected in the fourth zone (Z4), the flushing volume (Vp) is set to '0'. If a history of separation of the hydrogen supply pipe is previously detected in the first zone (Z1) or the second zone (Z2), the previously set flushing volume (Vp) 'V2' can be maintained.

Additionally, the controller 450 detects the history of separation of the hydrogen supply pipe due to replacement of the fuel cell stack 100 in the fifth zone Z5. Here, the controller 450 operates the hydrogen tank valve (HV) (112) after supplying air to the air electrode only when the separation history of the hydrogen supply pipe is not detected in the first zone (Z1) to the fourth zone (Z4). ), the hydrogen tank supply valve (HSV) (116), the hydrogen cutoff valve (FCV) (120), and the hydrogen supply valve (FSV) (122) are sequentially opened to supply hydrogen to the fifth zone (Z5). Detect the separation history of hydrogen supply pipes. At this time, if the value obtained by subtracting the stack measurement voltage from the stack reference voltage exceeds the preset reference voltage (V1), the controller 450 determines that the separation history of the hydrogen supply pipe in the fifth zone (Z5) has been detected.

When the separation history of the hydrogen supply pipe in the fifth zone (Z5) is detected, the controller 450 sets the flushing volume (Vp) to 'V5' in response to the volume (V5) of the hydrogen supply pipe in the fifth zone (Z5). You can set it.

Meanwhile, the controller 450 determines that the separation history of the hydrogen supply pipe has not been detected in the fifth zone (Z5) if the value obtained by subtracting the stack measurement voltage from the stack reference voltage does not exceed the preset reference voltage (V1). do. In this way, when the separation history of the hydrogen supply pipe is not detected in the fifth zone (Z5), the flushing volume (Vp) is set to '0'.

If the controller 450 confirms that the separation history of the hydrogen supply pipe for each zone is detected, it performs hydrogen electrode flushing before starting the fuel cell stack.

For this purpose, when the separation history of the hydrogen supply pipe is detected in one or more zones, the controller 450 determines the volume (Vn) requiring flushing, that is, the volume of the area where the separation history of the hydrogen supply pipe was detected. Confirm. Here, the volume (Vn) requiring flushing refers to the volume of the area where the hydrogen concentration has decreased below the standard value as foreign substances infiltrate due to the history of separation of the hydrogen supply pipe.

In addition, the controller 450 also checks the volume (Vr) where flushing is not required, that is, the volume of the area in which the separation history of the hydrogen supply pipe has not been detected. Here, the area where the separation history of the hydrogen supply pipe is not detected is an area where foreign substances have not penetrated, so the volume (Vr) where flushing is not required means the volume of the area where the hydrogen concentration is 100%.

Here, the volume that requires flushing (Vn) and the volume that does not require flushing (Vr) can be confirmed based on the flushing volume (Vp) set in the process of detecting the separation history of the hydrogen supply pipe for each zone.

The controller 450 performs hydrogen electrode flushing when the volume (Vn) that requires flushing and the volume (Vr) that does not require flushing are confirmed. At this time, the controller 450 opens the hydrogen supply valve (FSV) 122 to supply hydrogen to the hydrogen electrode for flushing the hydrogen electrode. The controller 450 may open the hydrogen supply valve (FSV) 122 until the pressure of the hydrogen electrode reaches the upper operating pressure (MOP). In this case, the controller 450 operates not only the hydrogen supply valve (FSV) 122, but also the hydrogen tank valve (HV) 112, the hydrogen tank supply valve (HSV) 116, and the hydrogen cut-off valve (FCV) 120. They can be opened one after another.

When the pressure of the hydrogen electrode exceeds the upper operating limit pressure (MOP), the controller 450 blocks the hydrogen supply by blocking the hydrogen supply valve (FSV) 122.

After blocking the supply of hydrogen to the hydrogen electrode, the controller 450 opens the purge valve to enable purging.

The controller 450 calculates the hydrogen concentration of the hydrogen electrode and performs continuous flushing by repeatedly performing hydrogen supply and purge until the hydrogen concentration of the hydrogen electrode exceeds the standard concentration.

Here, the controller 450 refers to [Equation 1] below when calculating the concentration of the hydrogen electrode.

In [Equation 1], H _c2 is the hydrogen concentration of the hydrogen electrode at the time of hydrogen injection, H _c1 is the hydrogen concentration of the hydrogen electrode immediately before hydrogen injection, Vn is the volume that requires flushing, and Vr is the volume that does not require flushing. it means. Additionally, MOP (Maximum Operating Pressure) refers to the upper operating pressure during hydrogen injection, and AP (Atmospheric Pressure) refers to the pressure after purge.

In this way, when continuous flushing is performed, foreign substances are discharged and the hydrogen concentration in the hydrogen electrode gradually increases. As the volume requiring flushing becomes larger, the number of continuous flushing may increase. As the hydrogen concentration of the hydrogen electrode gradually increases through continuous flushing, the controller 450 terminates flushing and starts the fuel cell stack when the hydrogen concentration of the hydrogen electrode exceeds the standard concentration.

Therefore, the performance of the fuel cell stack can be prevented from being deteriorated by removing foreign substances and restoring the hydrogen concentration through continuous flushing of the hydrogen electrode before starting the fuel cell stack.

Of course, if the separation history of the hydrogen supply pipe is not detected, the controller 450 can immediately start the fuel cell stack without flushing the hydrogen electrode.

FIGS. 6A and 6B are diagrams illustrating changes in hydrogen concentration in a fuel cell system according to an embodiment of the present invention. FIG. 6A is a diagram showing the inflow of foreign substances before starting the fuel cell stack, or when the inflow of foreign substances is detected. This shows an embodiment in which the fuel cell stack is started immediately without performing flushing, and Figure 6b shows the inflow of foreign substances before starting the fuel cell stack, and after the foreign substances are discharged through continuous flushing, the fuel cell stack This shows an example of starting up.

As shown in Figure 6a, when the fuel cell stack is started immediately without detecting the inflow of foreign substances before starting the fuel cell stack, the hydrogen concentration drops significantly due to the foreign substances, and frequent hydrogen purges are required to restore the hydrogen concentration. Not only that, but as the hydrogen purge time increases, hydrogen is wasted.

On the other hand, as shown in FIG. 6b, if the inflow of foreign substances is detected before starting the fuel cell stack, starting the fuel cell stack is possible after recovering the hydrogen concentration by performing continuous flushing. In this case, not only can the hydrogen purge time be shortened to prevent hydrogen loss, but also the performance of the fuel cell stack can be prevented from being deteriorated by preventing foreign substances from entering the hydrogen electrode of the fuel cell stack.

The operational flow of the fuel cell system according to the present invention configured as described above will be described in more detail as follows.

FIG. 7 is a diagram illustrating the operation flow of a flushing control method of a fuel cell system according to an embodiment of the present invention, and FIG. 8 is a diagram showing the flow of a separation history detection operation of a hydrogen supply pipe according to an embodiment of the present invention. This is a drawing.

First, referring to FIG. 7, the fuel cell system detects the separation history of the hydrogen supply pipe for each zone classified in advance for the hydrogen supply pipe (S110). Refer to FIG. 8 for detailed operation of the process of detecting the separation history of the hydrogen supply pipe for each zone.

Referring to FIG. 8, the fuel cell system sets the initial value of the flushing volume (Vp) to '0' (S210). Thereafter, when the value obtained by subtracting the pressure of the hydrogen tank 110 during the previous operation from the current pressure of the hydrogen tank 110 exceeds the preset first reference pressure (P1) (S220), the first The separation history of the hydrogen supply pipe due to replacement of the hydrogen tank 110 is detected in the zone (Z1) or the second zone (Z2) (S230). In this case, the fuel cell system adds 'V2' to the flushing volume (Vp) corresponding to the volume (V2) of the hydrogen supply pipe in the second zone (Z2) (S240).

In the 'S220' process, if the value obtained by subtracting the pressure of the hydrogen tank 110 during the previous operation from the current pressure of the hydrogen tank 110 does not exceed the preset first reference pressure (P1), the first reference pressure (P1) is set. It is determined that no history of separation of the hydrogen supply pipe is detected in zone (Z1) or second zone (Z2).

Next, if the pressure measured by the hydrogen supply pressure sensor (MP) 119 is less than the preset second reference pressure (P2) (S250), the fuel cell system detects the hydrogen supply pressure sensor ( Detect the separation history of the hydrogen supply pipe due to replacement of MP) (119) (S260). In this case, the fuel cell system adds 'V3' to the flushing volume (Vp) corresponding to the volume (V3) of the hydrogen supply pipe in the third zone (Z3) (S270). At this time, if the separation history of the hydrogen supply pipe is detected in the first zone (Z1) or the second zone (Z2) through the 'S220' and 'S230' processes, Vp becomes 'V2' in the 'S240' process, so ' In the 'S270' process, Vp becomes 'V2+V3'. Meanwhile, if the separation history of the hydrogen supply pipe was not detected in the 'S220' process, Vp is '0', so in the 'S270' process, Vp becomes 'V3'.

Meanwhile, if the pressure measured by the hydrogen supply pressure sensor (MP) 119 in the 'S250' process is not less than the preset second reference pressure (P2), the fuel cell system connects the hydrogen supply pipe in the third zone (Z3). It is determined that the separation history of is not detected, and then a detection operation is performed for the fourth zone (Z4).

Accordingly, the fuel cell system opens the hydrogen blocking valve (FCV) 120 (S280), and the pressure measured by the hydrogen supply pressure sensor (MP) 119 before opening the hydrogen blocking valve (FCV) 120. If the value obtained by subtracting the pressure measured by the hydrogen supply pressure sensor (MP) 119 after opening the hydrogen blocking valve (FCV) 120 exceeds the preset third reference pressure (P3) (S290), The separation history of the hydrogen supply pipe is detected in the fourth zone (Z4) (S300). In this case, the fuel cell system adds 'V4' to the flushing volume (Vp) corresponding to the volume (V4) of the hydrogen supply pipe in the fourth zone (Z4) (S310). At this time, if the separation history of the hydrogen supply pipe is detected in the first zone (Z1) or the second zone (Z2) through the 'S220' and 'S230' processes, Vp becomes 'V2' in the 'S240' process, so ' In the process of ‘S310’, Vp becomes ‘V2+V4’. Meanwhile, if the separation history of the hydrogen supply pipe was not detected in the 'S220' process, Vp is '0', so in the 'S310' process, Vp becomes 'V4'.

Meanwhile, the fuel cell system opens the hydrogen blocking valve (FCV) 120 at the pressure measured by the hydrogen supply pressure sensor (MP) 119 before opening the hydrogen blocking valve (FCV) 120 in the 'S290' process. If the value obtained by subtracting the pressure measured by the hydrogen supply pressure sensor (MP) (119) after opening does not exceed the preset third reference pressure (P3), the separation history of the hydrogen supply pipe in the fourth zone (Z4) It is determined that this has not been detected, and a detection operation for the next fifth zone (Z5) is performed.

If Vp is not '0' (S320) after performing processes 'S210' to 'S310', the fuel cell system determines that the separation history of the hydrogen supply pipe has been detected and supplies hydrogen to the fifth zone (Z5). Pipe separation history detection operation is not performed.

Meanwhile, if Vp is not '0' in the 'S320' process (S320), the separation history of the hydrogen supply pipe was not detected through the previous processes, so the fuel cell system is connected to the hydrogen supply pipe to the fifth zone (Z5). Perform separation history detection operation.

Accordingly, the fuel cell system opens the valves disposed on the air supply line and the hydrogen supply line of the fuel cell stack 100 to supply air to the air electrode and supply hydrogen to the hydrogen electrode (S330).

Afterwards, when the value obtained by subtracting the stack measurement voltage from the stack reference voltage exceeds the preset reference voltage (V1) (S340), the fuel cell system detects the separation history of the hydrogen supply pipe in the fifth zone (Z5) (S350) ). In this case, since the flushing volume (Vp) is '0' in the 'S320' process, the fuel cell system sets the flushing volume (Vp) to 'V5' (S360).

Meanwhile, the fuel cell system detects the separation history of the hydrogen supply pipe in the 5th zone (Z5) if the value obtained by subtracting the stack measurement voltage from the stack reference voltage during the 'S340' process does not exceed the preset reference voltage (V1). Decide that it didn't work out.

Referring again to FIG. 7, if there is a detection history of a hydrogen supply pipe in each zone through the processes of FIG. 8 (S120), the fuel cell system performs hydrogen electrode flushing before starting the fuel cell stack.

To this end, the fuel cell system checks the volume that requires flushing (Vn) and the volume that does not require flushing (Vr) (S130), and operates the hydrogen supply valve (FSV) until the pressure of the hydrogen electrode reaches the upper operating limit pressure (MOP). (122) is opened to supply hydrogen to the hydrogen electrode (S140, S150).

Afterwards, when the pressure of the hydrogen electrode exceeds the upper operating limit pressure (MOP) in the 'S150' process, the fuel cell system blocks the hydrogen supply valve (FSV) 122 (S160) and opens the purge valve (S170). . In this process, foreign substances in the hydrogen electrode are discharged.

Afterwards, the fuel cell system calculates the hydrogen concentration of the hydrogen electrode (S180) and repeatedly performs 'S140' to 'S190' processes until the hydrogen concentration of the hydrogen electrode exceeds the standard concentration to ensure continuous flushing.

When continuous flushing is performed by repeatedly performing the 'S140' to 'S180' processes, foreign substances are discharged and the hydrogen concentration in the hydrogen electrode gradually increases. Accordingly, if the hydrogen concentration of the hydrogen electrode exceeds the standard concentration in process 'S190', the fuel cell system ends flushing and starts the fuel cell stack (S200).

Therefore, the performance of the fuel cell stack can be prevented from being deteriorated by removing foreign substances and restoring the hydrogen concentration through continuous flushing of the hydrogen electrode before starting the fuel cell stack.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention.

Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

100: fuel cell stack 110: hydrogen tank
112: Hydrogen tank valve (HV) 114: Hydrogen charging check valve (HCV)
116: Hydrogen tank supply valve (HSV) 118: Hydrogen supply pressure control valve (PRV)
119: Hydrogen supply pressure sensor (MP) 120: Hydrogen shutoff valve (FCV)
122: Hydrogen supply valve (FSV) 124: Hydrogen ejector (FEJ)
126: purge valve (FPV) 410: detection unit
450: controller

Claims (21)

A hydrogen supply valve that regulates hydrogen supply on the hydrogen supply line connecting the hydrogen tank and the fuel cell stack;
A purge valve that discharges hydrogen from the hydrogen electrode of the fuel cell stack; and
Detecting the separation history of the hydrogen supply pipe before starting the fuel cell stack, and controlling the hydrogen supply valve and the purge valve to perform flushing of the hydrogen electrode of the fuel cell stack when the separation history of the hydrogen supply pipe is detected. controller;
A fuel cell system including. In claim 1,
The controller is,
A fuel cell system characterized in that the hydrogen supply line connecting the hydrogen tank and the fuel cell stack is divided into a plurality of zones, and the separation history of the hydrogen supply pipe is detected for each divided zone. In claim 2,
The hydrogen supply line is,
A first zone detecting a history of separation of the hydrogen supply pipe due to replacement of the hydrogen tank between the hydrogen tank and the hydrogen tank valve, separation of the hydrogen supply pipe due to replacement of the cartridge of the hydrogen tank between the hydrogen tank valve and the hydrogen tank supply valve A second zone for detecting the history, a third zone for detecting the history of separation of the hydrogen supply pipe due to replacement of the pressure sensor between the hydrogen tank supply valve and the hydrogen shutoff valve, and a third zone for detecting the history of separation of the hydrogen supply pipe due to replacement of the pipe between the hydrogen tank supply valve and the hydrogen supply valve. Classified into a fourth zone that detects the separation history of the hydrogen supply pipe due to replacement of the fuel cell stack between the hydrogen supply valve and the fuel cell stack, and a fifth zone that detects the separation history of the hydrogen supply pipe due to replacement of the fuel cell stack. Characterized by a fuel cell system. In claim 3,
The controller is,
If the value obtained by subtracting the hydrogen tank pressure during the previous operation from the current pressure of the hydrogen tank exceeds the preset first reference pressure, the hydrogen supply piping due to replacement of the hydrogen tank in the first zone or the second zone A fuel cell system characterized by detecting separation history. In claim 4,
The controller is,
When a history of separation of the hydrogen supply pipe due to replacement of the hydrogen tank is detected in the first zone or the second zone, the flushing volume is set in accordance with the volume of the hydrogen supply pipe in the second zone. battery system. In claim 3,
The controller is,
If the pressure measured by the hydrogen supply pressure sensor disposed on the hydrogen supply line in the third zone is less than the preset second reference pressure, the hydrogen supply pipe is separated due to replacement of the hydrogen supply pressure sensor in the third zone. A fuel cell system characterized by detecting history. In claim 6,
The controller is,
A fuel cell system, characterized in that when a separation history of the hydrogen supply pipe due to replacement of the hydrogen supply pressure sensor is detected in the third zone, the flushing volume is set in accordance with the volume of the hydrogen supply pipe in the third zone. In claim 3,
The controller is,
If the separation history of the hydrogen supply piping is not detected in the third zone, the hydrogen shutoff valve is opened, and the hydrogen shutoff valve is opened at the pressure measured by the hydrogen supply pressure sensor before opening the hydrogen shutoff valve. A fuel cell characterized in that it detects the history of separation of the hydrogen supply pipe due to pipe replacement in the fourth zone when the value obtained by subtracting the pressure measured by the hydrogen supply pressure sensor exceeds the preset third reference pressure. system. In claim 8,
The controller is,
A fuel cell system characterized in that, when a history of separation of the hydrogen supply pipe due to pipe replacement in the fourth zone is detected, the flushing volume is set in accordance with the volume of the hydrogen supply pipe in the fourth zone. In claim 3,
The controller is,
If no separation history of the hydrogen supply pipe is detected in the first to fourth zones, the valves disposed on the air supply line and the hydrogen supply line are opened to supply air and hydrogen to the fuel cell stack, and the stack A fuel cell system characterized in that, when the value obtained by subtracting the stack measurement voltage from the reference voltage exceeds a preset reference voltage, a history of separation of the hydrogen supply pipe due to replacement of the fuel cell stack is detected in the fifth zone. In claim 10,
The controller is,
When a history of separation of the hydrogen supply pipe due to replacement of the fuel cell stack is detected in the fifth zone, the flushing volume is set in accordance with the volume of the hydrogen supply pipe in the fifth zone. In claim 2,
The controller is,
When a separation history of the hydrogen supply pipe is detected in one or more of the divided zones, the hydrogen supply valve is opened until the pressure of the hydrogen electrode of the fuel cell stack reaches the preset upper operating limit pressure, and hydrogen is supplied to the hydrogen electrode. A fuel cell system characterized in that it supplies. In claim 12,
The controller is,
When the pressure of the hydrogen electrode exceeds the upper operating limit pressure, the hydrogen supply valve is blocked and the purge valve is opened to perform hydrogen purge. In claim 13,
The controller is,
Check the flushing volume in response to the volume of the hydrogen supply valve in the area where the separation history of the hydrogen supply pipe was detected, calculate the hydrogen concentration of the hydrogen electrode based on the flushing volume, and calculate the hydrogen concentration of the hydrogen electrode. A fuel cell system characterized in that the hydrogen supply valve and the purge valve are repeatedly controlled until the concentration exceeds the standard concentration. In claim 14,
The controller is,
A fuel cell system, wherein when the calculated hydrogen concentration of the hydrogen electrode exceeds the reference concentration, flushing of the hydrogen electrode is terminated and the fuel cell stack is started. In claim 1,
The hydrogen tank is,
A fuel cell system characterized by an exchangeable hydrogen tank. In claim 1,
The fuel cell stack is,
A fuel cell system characterized by a dead end type that operates with the discharge passage of the air electrode blocked. Detecting the separation history of the hydrogen supply pipe before starting the fuel cell stack; and
When a history of separation of the hydrogen supply pipe is detected, a hydrogen supply valve that regulates the hydrogen supply on the hydrogen supply line connecting the hydrogen tank and the fuel cell stack and a purge valve that discharges hydrogen from the hydrogen electrode of the fuel cell stack are installed. Controlling and flushing the hydrogen electrode of the fuel cell stack;
A flushing control method for a fuel cell system including. In claim 18,
The step of detecting the separation history of the hydrogen supply pipe is,
Dividing the hydrogen supply line connecting the hydrogen tank and the fuel cell stack into a plurality of zones, and detecting a separation history of the hydrogen supply pipe for each divided zone; and
A flushing control method for a fuel cell system, comprising the step of setting a flushing volume corresponding to the volume of the hydrogen supply pipe in the corresponding zone when a separation history of the hydrogen supply pipe is detected in one or more of the divided zones. . In claim 19,
The step of flushing the hydrogen electrode of the fuel cell stack includes:
When a separation history of the hydrogen supply pipe is detected in one or more of the divided zones, the hydrogen supply valve is opened until the pressure of the hydrogen electrode of the fuel cell stack reaches the preset upper operating limit pressure, and hydrogen is supplied to the hydrogen electrode. supplying;
When the pressure of the hydrogen electrode exceeds the upper operating limit pressure, blocking the hydrogen supply valve and opening the purge valve to perform hydrogen purge;
calculating the hydrogen concentration of the hydrogen electrode based on the flushing volume;
Repeatedly controlling the hydrogen supply valve and the purge valve until the calculated hydrogen concentration of the hydrogen electrode exceeds the reference concentration; and
A flushing control method for a fuel cell system, comprising: terminating flushing of the hydrogen electrode when the calculated hydrogen concentration of the hydrogen electrode exceeds the reference concentration. In claim 20,
A method for controlling flushing of a fuel cell system, further comprising starting the fuel cell stack when flushing of the hydrogen electrode is completed.

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