Condensate discharge control system and control method for fuel cell

Abstract

The present invention relates to a condensate discharge control system and a control method for a fuel cell, wherein the condensate discharge control system for a fuel cell comprises: a fuel cell stack, which is configured to generate electricity through a chemical reaction of a fuel; a fuel supply pipeline, which is configured to recirculate the fuel discharged from the fuel cell stack or to supply the fuel supplied from a fuel tank to the fuel cell stack; a water collector, which is arranged on the fuel supply pipeline and is configured to store condensate generated in the fuel cell stack; a drain valve, which is arranged at the outlet of the water collector and is configured to be opened or closed to allow or prevent the condensate stored in the water collector from being discharged; and a controller, which is configured to estimate the chemical reaction amount of the fuel, open the drain valve based on the estimated chemical reaction amount, and control the drain valve to close based on the state of the fuel being supplied to the fuel cell stack through the fuel supply pipeline when the drain valve is open.

Description

Technical Field

[0001] The present invention relates to a condensed water discharge control system and a condensed water discharge control method for a fuel cell, and more particularly to a control technology for discharging condensed water stored in a water collector even when a water level sensor of the water collector fails. Background Art

[0002] A fuel cell is a power generation device that converts chemical energy generated by the oxidation of fuel directly into electrical energy. It is similar to a chemical cell that mainly utilizes redox reactions, but it is also different from a chemical cell that performs a cell reaction in a closed system. The difference between a fuel cell and a chemical cell is that reactants are continuously supplied from outside the system, and reaction products are continuously removed to the outside. Recently, fuel cell power generation systems have been put into practical use, and since the reaction product of fuel cells is pure water, research on fuel cell power generation systems as energy sources for environmentally friendly vehicles has been actively conducted.

[0003] The fuel cell system includes: a fuel cell stack that generates electrical energy through a chemical reaction; an air supply device for supplying air to a cathode of the fuel cell stack; and a hydrogen supply device for supplying hydrogen to an anode of the fuel cell stack.

[0004] When the fuel cell stack generates electricity, water is generated in the fuel cell stack, and due to the concentration difference, a part of the water is discharged to the anode through the electrolyte membrane. The hydrogen supply device recirculates the hydrogen through the recycling device, and the water discharged from the anode is condensed and stored in a water collector included in the hydrogen supply device.

[0005] The water collector includes a water level sensor, and when the water level of the condensed water detected by the water level sensor is equal to or higher than a predetermined drain water level, the water collector opens a drain valve to discharge the stored condensed water. In addition, when the water level of the condensed water detected by the water level sensor is equal to or lower than a predetermined blocking water level, the water collector closes the drain valve to prevent hydrogen leakage.

[0006] However, when the water level sensor of the water collector fails, the water level of the condensed water stored in the water collector cannot be measured, and thus there is a problem that the drain valve cannot be properly controlled. When the condensed water of the hydrogen supply device cannot be discharged smoothly, the water cannot be discharged from the fuel cell stack to the outside, causing the flow path of the separator to be blocked, and when the drain valve is opened more than necessary, hydrogen is unnecessarily discharged, resulting in reduced fuel efficiency.

[0007] Normally, in order to prevent these problems, when the water level sensor of the water collector fails, a fault-safe control is used to open the drain valve based on the current integral value obtained by integrating the current generated by the fuel cell stack. When the current integral value reaches a predetermined constant value, the drain valve is opened. However, depending on the state of the fuel cell stack, the amount of condensed water stored in the water collector is not constant, and there is a problem that the water level of the water collector cannot be accurately measured.

[0008] The above content is only intended to help understand the background of the present invention, and is not intended to indicate that the present invention falls within the scope of the prior art known to those skilled in the art. Summary of the invention

[0009] Therefore, the present invention has taken note of the above-mentioned problems occurring in the prior art, and the present invention aims to propose a technology that can properly control a drain valve by detecting condensed water stored in a sump even when a water level sensor of the sump fails.

[0010] According to one aspect, a condensate discharge control system for a fuel cell includes: a fuel cell stack configured to generate electricity through a chemical reaction of a fuel; a fuel supply line configured to recirculate fuel discharged from the fuel cell stack or to supply fuel supplied from a fuel tank to the fuel cell stack; a water collector disposed on the fuel supply line and configured to store condensate generated in the fuel cell stack; a drain valve disposed at an outlet of the water collector and configured to be opened or closed to allow or prevent the condensate stored in the water collector from being discharged; and a controller configured to estimate a chemical reaction amount of the fuel, open the drain valve based on the estimated chemical reaction amount, and control the drain valve to close based on a state of fuel being supplied to the fuel cell stack through the fuel supply line when the drain valve is open.

[0011] The condensed water discharge control system further includes: a pressure sensor configured to measure the pressure on the anode side of the fuel cell stack, wherein the controller controls the drain valve to close according to the pressure on the anode side measured by the pressure sensor.

[0012] The condensate discharge control system further includes: a fuel supply valve disposed between the fuel tank and the fuel supply line and configured to control the fuel supplied from the fuel tank to the fuel supply line, wherein the controller controls the drain valve to close according to the opening of the fuel supply valve.

[0013] The condensate discharge control system also includes: a purge valve, which is arranged on the fuel supply pipeline and configured to control a purge process for discharging gas from the fuel supply pipeline to the outside, wherein a controller estimates a fuel discharge amount discharged to the outlet of the water collector by opening the drain valve, and controls the opening of the purge valve based on the estimated gas amount discharged to the outlet of the water collector.

[0014] According to another aspect, a condensed water discharge control method for a fuel cell includes the following steps: estimating the reaction amount of fuel in a fuel cell stack; based on the estimated reaction amount, controlling a drain valve to open, wherein the drain valve allows or prevents the discharge of condensed water stored in a water collector for storing condensed water in a fuel supply line; and in a state where the drain valve is open, controlling the drain valve to close based on a state of fuel being supplied to the fuel cell stack through the fuel supply line.

[0015] The step of estimating the reaction amount of the fuel in the fuel cell stack includes estimating the reaction amount of the fuel in the fuel cell stack based on a current integrated value obtained by integrating an output current of the fuel cell stack with an elapsed time.

[0016] In the step of controlling the drain valve to open, when the estimated reaction amount is equal to or greater than a predetermined reaction amount, the drain valve is opened.

[0017] In the step of controlling the drain valve to close, the drain valve is closed when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases at a decrease rate equal to or higher than a predetermined decrease rate.

[0018] The measured pressure on the anode side of the fuel cell stack may be equal to or greater than a target pressure set according to a required power generation amount of the fuel cell.

[0019] In the step of controlling the drain valve to close, the drain valve is closed when a value obtained by subtracting the pressure on the anode side of the fuel cell stack measured by the pressure sensor from a target pressure set according to the required power generation amount of the fuel cell is equal to or greater than a predetermined pressure difference.

[0020] In the step of controlling the closing of the drain valve, when a predetermined opening time has passed from the time point when the drain valve is controlled to open, the drain valve is closed; and when the predetermined opening time has passed and the opening of the fuel supply valve in the fuel tank is equal to or less than a predetermined threshold opening, the standard for the reaction amount used to control the opening of the drain valve is lowered.

[0021] The target pressure set according to the required power generation amount of the fuel cell is fixed during a predetermined opening time that has elapsed from the time point when the drain valve is controlled to open.

[0022] The condensate discharge control method also includes the following steps: after controlling the drain valve to close, estimating the amount of fuel discharge discharged through the outlet of the water collector; and based on the estimated amount of fuel discharge, controlling the purge valve to open, wherein the purge valve controls the purge process for discharging the gas in the fuel supply pipeline to the outside.

[0023] The step of controlling the drain valve to close includes estimating a fuel discharge amount based on a difference between a pressure on the anode side of the fuel cell stack and an external pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and other advantages of the present invention will become more apparent through the following detailed description in conjunction with the accompanying drawings, in which:

[0025] Figure 1 is a block diagram of a condensed water discharge control system for a fuel cell according to one embodiment of the present invention; and

[0026] Figure 2 is a flow chart of a condensed water discharge control method for a fuel cell according to one embodiment of the present invention. DETAILED DESCRIPTION

[0027] The specific structural and functional descriptions of the embodiments of the present invention disclosed in this disclosure or application are shown only for the purpose of describing the embodiments, and the embodiments according to the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described in this disclosure or application.

[0028] Various modifications may be made according to the embodiments of the present invention, and various forms may be provided so as to be shown in the drawings and to be described in detail in the present disclosure or application. However, it should be understood that it is not intended to limit the embodiments of the concepts according to the present invention to a specific disclosed form, but to include all modifications, equivalents and substitutions falling within the spirit and scope of the present invention.

[0029] Although the terms first, second and / or etc. may be used to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish one element from another element, for example, a first element may be named a second element, and similarly, a second element may be named a first element without departing from the scope of the present invention.

[0030] When a component is referred to as being "connected" or "coupled" to another component, it may be directly connected or coupled to the other component, but it should be understood that other components may exist between the component and the other component. Conversely, when a component is referred to as being "directly connected" or "directly coupled" to another component, it should be understood that no other components exist between the component and the other component. Other expressions describing the relationship between components, namely "between" and "directly between" or "adjacent" or "directly adjacent", are also interpreted in the same manner as above.

[0031] The terms used herein are only used for the purpose of illustrating specific embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, the singular includes the plural. In the present invention, the terms "including", "having", etc. are used to specify the presence of the features, numbers, steps, operations, components, elements, or combinations thereof described herein, without excluding the presence or addition of one or more other features, numbers, steps, operations, components, elements, or combinations thereof.

[0032] Unless defined differently, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Those terms defined in commonly used dictionaries should be interpreted as having the same meaning as the contextual meaning in the relevant field. Unless clearly defined in this application, these terms should not be interpreted as having an ideal or overly formal meaning.

[0033] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the entire drawings, the same reference numerals represent the same components.

[0034] Figure 1 is a block diagram of a condensed water discharge control system for a fuel cell according to one embodiment of the present invention.

[0035] Reference Figure 1 , a condensate discharge control system for a fuel cell according to one embodiment of the present invention includes: a fuel cell stack 10, which generates electricity through a chemical reaction of a fuel; a fuel supply line 80, which is used to recirculate the fuel discharged from the fuel cell stack 10, or to supply the fuel supplied from a fuel tank 70 to the fuel cell stack 10; a water collector 20, which is arranged on the fuel supply line 80 and is configured to store condensate generated in the fuel cell stack 10; a drain valve 30, which is arranged at the outlet of the water collector 20 and is configured to be opened or closed to allow or prevent the discharge of the condensate stored in the water collector 20; and a controller 50, which is used to estimate the chemical reaction amount of the fuel, open the drain valve 30 based on the estimated chemical reaction amount, and control the drain valve 30 to close based on the state of supplying fuel to the fuel cell stack 10 through the fuel supply line 80 when the drain valve 30 is open.

[0036] The fuel cell stack 10 generates electricity through a chemical reaction of hydrogen and oxygen received as fuel from a hydrogen electrode (anode) and an oxygen electrode (cathode). The hydrogen and oxygen react within the fuel cell stack 10 to generate condensed water.

[0037] The fuel supply line 80 supplies the fuel supplied from the fuel tank 70 to the fuel cell stack 10, recirculates the fuel exhausted from the fuel cell stack 10, and supplies the recycled fuel again to the fuel cell stack 10. In other words, the fuel supply line 80 recirculates the fuel exhausted from the fuel cell stack 10, and mixes the exhausted fuel with the fuel supplied from the fuel tank 70 to supply the mixed fuel to the fuel cell stack 10 again.

[0038] The fuel tank 70 stores high-pressure hydrogen and supplies the stored high-pressure hydrogen to the fuel supply line 80. The high-pressure hydrogen stored in the fuel tank 70 is supplied to the fuel supply line 80 after undergoing a decompression step.

[0039] The water collector 20 is provided on the fuel supply line 80 to store condensed water generated in the fuel cell stack 10. Specifically, the water collector 20 stores condensed water generated at the cathode of the fuel cell stack 10 and diffused to the anode to move to the fuel supply line 80. The outlet of the water collector 20 may be connected to the outside or to a humidifier provided at the cathode inlet of the fuel cell stack 10.

[0040] The drain valve 30 may be provided at the outlet of the water collector 20 to control the discharge of the condensed water of the water collector 20. Specifically, the drain valve 30 is opened to allow the discharge of the condensed water stored in the water collector 20; the drain valve 30 is closed to prevent the discharge of the condensed water. Generally, the drain valve 30 is controlled to be in a closed state to prevent hydrogen from being discharged through the outlet of the water collector 20, and when the condensed water is stored, the drain valve 30 is intermittently opened to discharge the condensed water to the outside.

[0041] Generally, the water level sensor 40 may be disposed at the sump 20 to detect the condensed water stored in the sump 20. Specifically, by sensing the water level of the condensed water stored in the sump 20, the water level sensor 40 may detect the amount of the stored condensed water, and may control the opening or closing of the drain valve 30 based on the water level sensed by the water level sensor 40.

[0042] Specifically, when it is determined that the stored condensed water is at a first water level or higher based on the water level sensed by the water level sensor 40, the drain valve 30 may be opened, and when it is determined that the stored condensed water is at a second water level or lower based on the water level sensed by the water level sensor 40, the drain valve 30 may be closed. However, when the water level sensor 40 fails, the opening or closing of the drain valve 30 may not be controlled based on the water level sensed by the water level sensor 40.

[0043] Therefore, the controller 50 may estimate the chemical reaction amount of the fuel, open the drain valve 30 based on the estimated chemical reaction amount, and control the drain valve 30 to be closed based on the state of fuel supplied to the fuel cell stack 10 through the fuel supply line 80 .

[0044] The controller 50 may be a separately formed controller or a separate controller for controlling the hydrogen supply system of the fuel cell, or may be included in a fuel cell controller (fuel cell control unit (FCU)) to control the hydrogen supply system of the fuel cell.

[0045] The controller 50 may include at least one memory and at least one processor programmed to perform the various functions described below.

[0046] As described below, the state of fuel supply to the fuel cell stack 10 may be determined using the pressure measured at the anode side of the fuel cell stack 10 and the pressure of the fuel supply valve 71 for controlling the supply of fuel from the fuel tank 70 to the fuel supply line 80 .

[0047] Therefore, even when the water level sensor 40 fails or is not present, the drain valve 30 can be controlled to properly drain the condensed water stored in the water collector 20, thereby preventing overflow in the fuel cell stack 10 due to excessive condensed water stored in the water collector 20, and preventing hydrogen in the fuel supply pipeline 80 from being discharged through the drain valve 30.

[0048] The present invention further includes a pressure sensor 60 for measuring the pressure on the anode side of the fuel cell stack 10 , and the controller 50 can control the drain valve 30 to close according to the pressure on the anode side measured by the pressure sensor 60 .

[0049] The pressure sensor 60 may measure the pressure on the anode side of the fuel cell stack 10. As described below, the controller 50 may control the drain valve 30 to be closed using the pressure on the anode side of the fuel cell stack 10 measured by the pressure sensor 60.

[0050] As another embodiment, the pressure sensor 60 may be provided at the fuel supply line 80 to measure the pressure of the fuel supply line 80. Specifically, the pressure sensor 60 may be provided at a position on the fuel supply line 80 connected to the inlet side of the anode of the fuel cell stack 10 to measure the pressure of the fuel supply line 80 flowing into the anode of the fuel cell stack 10.

[0051] The present invention also includes a fuel supply valve 71, which is disposed between the fuel tank 70 and the fuel supply line 80 and is configured to control the fuel supplied from the fuel tank 70 to the fuel supply line 80. The controller 50 can control the drain valve 30 to close according to the opening of the fuel supply valve 71.

[0052] The fuel supply valve 71 may be located between the fuel tank 70 and the fuel supply line 80. The opening of the fuel supply valve 71 may be controlled according to the pressure of the fuel supply line 80, or according to the pressure on the anode side measured by the pressure sensor 60, and the target pressure set according to the required power generation amount of the fuel cell. In other words, the opening of the fuel supply valve 71 may be controlled to guide the pressure on the anode side measured by the pressure sensor 60 to converge with the target pressure set according to the required power generation amount of the fuel cell.

[0053] It may also include a shut-off valve (not shown) separated from the fuel supply valve 71, which is configured to be controlled to open or close according to the opening or closing of the fuel cell system to supply or block hydrogen. The fuel supply valve 71 can be formed as an integrated valve to further perform the function of the shut-off valve (not shown).

[0054] The controller 50 may detect the discharge of the fuel from the fuel supply line 80 according to the opening degree of the fuel supply valve 71 to control the drain valve 30 to be closed.

[0055] The present invention also includes a purge valve 90, which is arranged at the fuel supply pipeline 80 and is configured to control the purge process of discharging the gas of the fuel supply pipeline 80 to the outside. The controller 50 can estimate the amount of fuel discharged to the outlet of the collector 20 according to the opening degree of the drain valve 30, and control the opening of the purge valve 90 based on the estimated amount of gas discharged to the outlet of the collector 20.

[0056] The purge valve 90 is provided at the fuel supply line 80 through which the fuel is recirculated again through the fuel cell stack 10 , and can discharge gas having a reduced hydrogen concentration in the fuel supply line 80 to the outside when the gas passes through the fuel cell stack 10 .

[0057] The controller 50 may estimate the amount of fuel discharged through the outlet of the water collector 20, and by reflecting the estimated amount of fuel discharged, reduce the opening time of the purge valve 90 or increase the opening cycle of the purge valve 90. In other words, when the fuel is discharged through the outlet of the water collector 20, the controller 50 may control the purge valve 90 to reduce the purge amount.

[0058] The control method of the controller 50 will be described in detail below.

[0059] Figure 2 is a flow chart of a condensed water discharge control method for a fuel cell according to one embodiment of the present invention.

[0060] Reference Figure 2According to one embodiment of the present invention, a condensed water discharge control method for a fuel cell may include the following steps: estimating a reaction amount in a fuel cell stack (S300); controlling a drain valve to open, wherein the drain valve is opened or closed based on the estimated reaction amount to allow or prevent the discharge of condensed water stored in a water collector storing condensed water of a fuel supply line (S400); and in an open state of the drain valve, based on a state of fuel being supplied to the fuel cell stack through the fuel supply line, controlling the drain valve to close (S800).

[0061] In the step of estimating the reaction amount in the fuel cell stack (S300), the reaction amount of hydrogen and oxygen supplied to the fuel cell stack is estimated. Although it may be different depending on the reaction environment of the fuel cell stack, the condensed water generated in the fuel cell stack and transferred to the water collector is proportional to the reaction amount in the fuel cell stack. Therefore, the reaction amount in the fuel cell stack can be estimated, and the discharge of the condensed water can be controlled based on the estimated reaction amount.

[0062] In the step of controlling the drain valve to open ( S400 ), when it is determined that a predetermined amount or more of condensed water is stored in the sump based on the estimated reaction amount, the drain valve may be opened to allow the condensed water to be discharged through the sump outlet.

[0063] In the step of controlling the drain valve to close (S800), when the drain valve is open and the condensed water is discharged through the outlet of the water collector, the fuel of the fuel supply line can be discharged to the outside. Therefore, the drain valve can be controlled to close by detecting the discharge of the fuel of the fuel supply line based on the state of supplying fuel to the fuel cell stack through the fuel supply line when the drain valve is open.

[0064] Therefore, there is an effect of effectively draining the condensed water stored in the water collector while minimizing the fuel draining of the fuel supply line.

[0065] Before estimating the reaction amount in the fuel cell stack (S300), a step of determining whether the water level sensor fails (S100) may be further included. More specifically, when determining whether the water level sensor fails (S100), when the sensing value of the water level sensor exceeds the normal sensing range, it can be determined that the water level sensor fails.

[0066] As another embodiment, when the sensing value of the water level sensor is fixed, even if the drain valve is controlled to be open, it can be determined that the water level sensor is faulty. In other words, when the water level sensed by the water level sensor does not decrease within a reference time or longer, even if the drain valve is opened, it can be determined that the water level sensor is faulty.

[0067] As another embodiment, when the sensing value of the water level sensor does not increase, even if the fuel cell stack continues to generate power in the closed state of the drain valve, it can be determined that the water level sensor has failed. Specifically, when the sensing value of the water level sensor does not increase, even if the current integral value obtained by integrating the output current of the fuel cell stack increases to exceed a predetermined current integral value, it can be determined that the water level sensor is not operating normally.

[0068] In the step of determining whether the water level sensor fails (S100), when it is determined that the water level sensor does not fail, the drain valve may be controlled based on the sensed value of the water level sensor (S200). The condensed water discharge control method for a fuel cell according to an embodiment of the present invention may be limited to the case where the water level sensor fails.

[0069] In the step of estimating the reaction amount in the fuel cell stack ( S300 ), the reaction amount in the fuel cell stack may be estimated based on a current integration value obtained by integrating an output current of the fuel cell stack with an elapsed time.

[0070] The fuel cell stack generates current through the chemical reaction between hydrogen and oxygen, and supplies the current to a load including a motor, etc. through a bus. Therefore, the current integral value obtained by integrating the output current from the fuel cell stack with the elapsed time is proportional to the reaction amount in the fuel cell stack. Therefore, the reaction amount in the fuel cell stack can be estimated using the current integral value.

[0071] In the step of controlling the drain valve to open (S400), when the estimated reaction amount is equal to or greater than a predetermined reaction amount, the drain valve may be controlled to open. In other words, when the estimated reaction amount of the fuel cell stack is equal to or greater than a predetermined reaction amount, it is determined that the condensed water stored in the water collector needs to be discharged, so that the drain valve may be controlled to open.

[0072] The predetermined reaction amount may be set through experiments, or may be set in consideration of various operating conditions of the fuel cell stack, or an average value of a rate at which condensed water is stored in the water collector in the worst case.

[0073] Specifically, in the step of estimating the reaction amount in the fuel cell stack ( S300 ), when the reaction amount in the fuel cell stack is estimated based on the current integrated value and the current integrated value is equal to or greater than a predetermined integrated value α, the drain valve may be controlled to open.

[0074] In the step of controlling the drain valve to close (S800), when the discharge of the stored condensed water is completed by opening the drain valve, the fuel of the fuel supply line is discharged through the outlet of the water collector, so that it can be detected whether the condensed water discharge is completed by determining whether the fuel of the fuel supply line is discharged (S500).

[0075] As an embodiment, in the step of controlling the drain valve to be closed (S800), when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases at a decrease rate of more than a predetermined decrease rate β (S510), the drain valve may be controlled to be closed. In other words, when the sensing value of the pressure sensor for measuring the pressure on the anode side of the fuel cell stack suddenly decreases to a decrease rate of more than a predetermined decrease rate β, it may be determined that the fuel of the fuel supply line is discharged through the outlet of the water collector, thereby having the effect of being able to estimate the discharge of the fuel through the outlet of the water collector.

[0076] Specifically, the pressure measured at the anode side of the fuel cell stack may be equal to or greater than a target pressure set according to the required power generation of the fuel cell (S510). The target pressure is a target value followed by the pressure at the anode side of the fuel cell stack and may be set in proportion to the required power generation of the fuel cell.

[0077] In other words, when the measured pressure on the anode side of the fuel cell stack is equal to or greater than the target pressure set according to the required power generation amount of the fuel cell, the pressure on the anode side of the fuel cell stack is controlled so as not to increase, so that the fuel flowing in through the fuel supply valve is minimized. Therefore, the change in the pressure on the anode side of the fuel cell stack due to the inflow of fuel through the fuel supply valve is minimized, thereby having the effect of being able to more accurately estimate whether the fuel is discharged through the outlet of the water collector.

[0078] Specifically, when the pressure on the anode side of the fuel cell stack is less than the target pressure, the required power generation of the fuel cell can be reduced. When the measured pressure on the anode side of the fuel cell stack is equal to or less than the target pressure, the fuel supply valve can be controlled to have a small opening or closed. Therefore, when the fuel cell stack generates electricity and consumes fuel from the fuel supply line, the pressure on the anode side of the fuel cell stack gradually decreases to reach the target pressure.

[0079] The predetermined decrease rate β may be set to be greater than the decrease rate that is gradually reduced to control the pressure on the anode side of the fuel cell stack to reach the target pressure when the fuel of the fuel supply line is consumed.

[0080] In other words, when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases at a rate greater than a predetermined rate β, it is determined that the fuel of the fuel supply line is being discharged through the outlet of the water collector, and the drain valve is controlled to close.

[0081] As another embodiment, in the step of controlling the drain valve to be closed (S800), when a value obtained by subtracting the pressure on the anode side of the fuel cell stack measured by the pressure sensor from the target pressure set according to the required power generation amount of the fuel cell is equal to or greater than a predetermined pressure difference (S520), the drain valve may be controlled to be closed. The predetermined pressure difference may be set to be greater than a normal pressure difference that is temporarily different from the pressure on the anode side of the fuel cell stack due to a change in the target pressure set according to the required power generation amount.

[0082] In other words, when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases by a large difference relative to the target pressure (S520), it is determined that the fuel of the fuel supply line is being discharged, and the drain valve may be controlled to be closed.

[0083] As yet another embodiment, in the step of controlling the drain valve to close (S800), when a predetermined opening time T has passed from the time point when the drain valve is controlled to open (S530), the drain valve may be controlled to close, and when the opening of the fuel supply valve in the fuel tank is equal to or less than a predetermined threshold opening X for a predetermined opening time T (S600), the standard of the reaction amount for controlling the drain valve to open may be lowered (S700).

[0084] In other words, when a predetermined opening time T elapses after a time point at which the drain valve is controlled to be opened (S520), the drain valve may be controlled to be closed.

[0085] In addition, in the step of controlling the drain valve to close (S800), the drain valve is controlled to close even when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases at a reduction rate greater than a predetermined reduction rate β (S510), or when a value obtained by subtracting the pressure on the anode side of the fuel cell stack measured by the pressure sensor from a target pressure set according to the required power generation of the fuel cell is equal to or greater than a predetermined pressure difference (S520), and when the drain valve is controlled to open, if the drain valve is not closed even after a predetermined opening time T has passed, the drain valve can also be controlled to close.

[0086] In other words, even when it is determined that the fuel of the fuel supply line is not drained, the drain valve may be controlled to close when the predetermined opening time T has elapsed. Therefore, it is possible to prevent the fuel of the fuel supply line from being drained through the outlet of the water collector.

[0087] In addition, it is possible to determine whether the opening degree of the fuel supply valve in the fuel tank is equal to or less than a predetermined threshold opening degree X for a predetermined opening time T. When the opening degree of the fuel supply valve exceeds the predetermined threshold opening degree X in a state where the drain valve is open for a predetermined opening time T, it is determined that the fuel of the fuel supply line is being discharged through the outlet of the water collector.

[0088] The predetermined threshold opening X may be set in consideration of a normal opening range for guiding the pressure on the anode side of the fuel cell stack to comply with a target pressure set according to the required power generation amount of the fuel cell.

[0089] However, when the opening of the fuel supply valve is equal to or less than the predetermined threshold opening X, the standard for controlling the reaction amount of the drain valve opening may be lowered (S700). In other words, the above-mentioned predetermined integral value α may be reduced (S700).

[0090] When the opening of the fuel supply valve is equal to or less than the predetermined threshold opening X, it may be that the condensed water stored in the water collector is not completely discharged, or the condensed water remains inside the fuel supply line or the fuel cell stack. Therefore, the predetermined reaction amount as a standard for controlling the opening of the drain valve may be reduced (S700).

[0091] Specifically, the target pressure set according to the required power generation amount of the fuel cell can be fixed from the point of time when the drain valve is controlled to open until the predetermined opening time T has passed. Therefore, it is possible to accurately detect the change in the pressure of the fuel supply line following the target pressure.

[0092] In other words, there is an effect of being able to more accurately detect that the fuel of the fuel supply line is discharged through the outlet of the water collector and thus the pressure of the fuel supply line is reduced.

[0093] In the step of controlling the drain valve to close (S800), the current integral value may be reset. In other words, the current integral value obtained by integrating the current with the elapsed time is used as a criterion for controlling the drain valve to open (S400), and when controlling the drain valve to close, the current integral value may be reset to 0, and then the output current of the fuel cell stack may be integrated again over time to control the drain valve to open.

[0094] After the step of controlling the drain valve to close (S800), it may also include estimating the amount of fuel discharge discharged through the outlet of the collector (S900), and controlling the opening of the purge valve, which is used to control the purge process of discharging the gas of the fuel supply pipeline to the outside based on the estimated fuel discharge amount (S900).

[0095] Due to cross mixing, impurities accumulate in the gas of the fuel supply line exhausted from the fuel cell stack, so the purge valve may be opened to discharge the gas of the fuel supply line to the outside. Specifically, in the step of controlling the opening of the purge valve (S900), the opening period and opening time of the purge valve may be controlled.

[0096] However, when the gas of the fuel supply line is discharged to the outside through the outlet of the water collector by opening the drain valve, the fuel discharge amount through the outlet of the water collector can be estimated and reflected to the purge valve control. Specifically, the opening cycle of the purge valve can be increased or the opening time of the purge valve can be reduced so as to reduce the purge amount through the opening of the purge valve by the estimated fuel discharge amount.

[0097] Specifically, in the step of estimating the fuel discharge amount ( S900 ), the fuel discharge amount may be estimated based on a pressure difference between a pressure on the anode side of the fuel cell stack and an external pressure.

[0098] The purge valve is arranged between the fuel supply line and the outside connected to the fuel supply line, and the outside may be the inlet of the cathode side. Therefore, the external pressure may be the pressure of the inlet of the cathode side of the fuel cell stack.

[0099] The fuel discharge amount may be proportional to the difference between the pressure on the anode side of the fuel cell stack and the external pressure, or proportional to the difference between the pressure on the anode side of the fuel cell stack and the pressure at the inlet on the cathode side of the fuel cell stack.

[0100] Specifically, the hydrogen discharge rate g / s according to the pressure of the inlet of the anode side and the cathode side of the fuel cell stack may be determined by a pre-stored table or map.

[0101] Therefore, the hydrogen emission amount g can be estimated using the determined hydrogen emission rate g / s and the closing time s between the time when the drain valve is controlled to be closed and the time when the drain valve is actually closed. The closing time s can be determined experimentally according to the specifications of the system.

[0102] Therefore, the purge control is performed by reflecting the fuel discharge amount of the fuel supply line discharged through the outlet of the water collector, thereby having the effects of improving fuel efficiency and stabilizing control by preventing unnecessary fuel discharge.

[0103] The condensed water discharge control system and the condensed water discharge control method for a fuel cell according to the present invention have the effect of properly discharging the condensed water stored in the sump by controlling the drain valve even when the water level sensor fails or there is no water level sensor.

[0104] Furthermore, the present invention has the effect of being able to prevent the fuel cell stack from flooding due to excessive condensed water stored in the water collector and hydrogen from being discharged from the fuel supply line via the drain valve.

[0105] Although specific embodiments of the present invention have been described and illustrated, it will be appreciated by those skilled in the art that various substitutions and modifications may be made without departing from the technical concept of the present invention as disclosed in the appended claims.

Claims

1. A condensate discharge control system for a fuel cell, include: a fuel cell stack configured to generate electricity through a chemical reaction of a fuel; a fuel supply line configured to recirculate fuel exhausted from the fuel cell stack or to supply fuel supplied from a fuel tank to the fuel cell stack; a water collector disposed on the fuel supply line and configured to store condensed water generated in the fuel cell stack; a drain valve disposed at an outlet of the water collector and configured to be opened or closed to allow or prevent the condensed water stored in the water collector from being drained; a controller configured to estimate a chemical reaction amount of the fuel, open the drain valve based on the estimated chemical reaction amount, and control the drain valve to close based on a state of fuel being supplied to the fuel cell stack through the fuel supply line in a state where the drain valve is open; as well as a pressure sensor configured to measure the pressure on the anode side of the fuel cell stack, The controller controls the drain valve to close according to the pressure on the anode side measured by the pressure sensor. wherein, when the drain valve is controlled to be closed, the drain valve is closed when a value obtained by subtracting the pressure on the anode side of the fuel cell stack measured by the pressure sensor from a target pressure set according to the required power generation amount of the fuel cell is equal to or greater than a predetermined pressure difference, or Wherein, in the step of controlling the drain valve to close, when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases at a decrease rate greater than a predetermined decrease rate, the drain valve is closed.

2. A condensate discharge control system for a fuel cell, include: a fuel cell stack configured to generate electricity through a chemical reaction of a fuel; a fuel supply line configured to recirculate fuel exhausted from the fuel cell stack or to supply fuel supplied from a fuel tank to the fuel cell stack; a water collector disposed on the fuel supply line and configured to store condensed water generated in the fuel cell stack; a drain valve disposed at an outlet of the water collector and configured to be opened or closed to allow or prevent the condensed water stored in the water collector from being drained; a controller configured to estimate a chemical reaction amount of the fuel, open the drain valve based on the estimated chemical reaction amount, and control the drain valve to close based on a state of fuel being supplied to the fuel cell stack through the fuel supply line while the drain valve is open; and a fuel supply valve disposed between the fuel tank and the fuel supply line and configured to control the fuel supplied from the fuel tank to the fuel supply line, Wherein, the controller controls the drain valve to close according to the opening of the fuel supply valve, and in: In the step of controlling the drain valve to close, when a predetermined opening time has elapsed from a time point when the drain valve is controlled to open, the drain valve is closed; and When a predetermined opening time has elapsed and the opening degree of the fuel supply valve in the fuel tank is equal to or smaller than a predetermined threshold opening degree, a criterion of a reaction amount for controlling the opening of the drain valve is lowered.

3. The condensate discharge control system according to claim 1 or 2, further comprising: include: a purge valve disposed on the fuel supply line and configured to control a purge process for discharging gas from the fuel supply line to the outside, The controller estimates a fuel discharge amount discharged to an outlet of the water collector by opening the drain valve, and controls the purge valve to open based on the estimated gas discharge amount to the outlet of the water collector.

4. A method for controlling condensed water discharge from a fuel cell, The following steps are involved: estimating the reaction amount of fuel in a fuel cell stack; controlling a drain valve to open based on the estimated reaction amount, wherein the drain valve allows or prevents condensed water stored in a water collector for storing condensed water of a fuel supply line from being drained; as well as In a state where the drain valve is open, the drain valve is controlled to be closed based on a state where fuel is supplied to the fuel cell stack through the fuel supply line, wherein, in the step of controlling the drain valve to be closed, when a value obtained by subtracting the pressure on the anode side of the fuel cell stack measured by the pressure sensor from a target pressure set according to the required power generation amount of the fuel cell is equal to or greater than a predetermined pressure difference, the drain valve is closed; or Wherein, in the step of controlling the drain valve to close, when the pressure on the anode side of the fuel cell stack measured by the pressure sensor decreases at a decrease rate greater than a predetermined decrease rate, the drain valve is closed.

5. A method for controlling condensed water discharge from a fuel cell, The following steps are involved: estimating the reaction amount of fuel in a fuel cell stack; controlling a drain valve to open based on the estimated reaction amount, wherein the drain valve allows or prevents condensed water stored in a water collector for storing condensed water of a fuel supply line from being drained; as well as In a state where the drain valve is open, the drain valve is controlled to be closed based on a state where fuel is supplied to the fuel cell stack through the fuel supply line, in: In the step of controlling the drain valve to be closed, when a predetermined opening time has elapsed from a time point when the drain valve is controlled to be opened, the drain valve is closed; and When a predetermined opening time has elapsed and the opening degree of the fuel supply valve in the fuel tank is equal to or smaller than a predetermined threshold opening degree, a criterion of a reaction amount for controlling the opening of the drain valve is lowered.

6. The condensed water discharge control method according to claim 4 or 5, wherein the step of estimating the reaction amount of the fuel in the fuel cell stack include: A reaction amount of fuel in the fuel cell stack is estimated based on a current integrated value obtained by integrating an output current of the fuel cell stack with an elapsed time.

7. The condensate discharge control method according to claim 4 or 5, wherein in the step of controlling the drain valve to open, when the estimated reaction amount is equal to or greater than a predetermined reaction amount, the drain valve is opened. 8 . The condensed water discharge control method of claim 4 , wherein the measured pressure on the anode side of the fuel cell stack is equal to or greater than a target pressure set according to a required power generation amount of the fuel cell.

9. The condensed water discharge control method according to claim 4, wherein the target pressure set according to the required power generation amount of the fuel cell is fixed during a predetermined opening time that has elapsed from a time point when the drain valve is controlled to be opened.

10. The condensate discharge control method according to claim 4 or 5, further comprising: The following steps are involved: estimating the amount of fuel discharge discharged through the outlet of the water collector after the step of controlling the drain valve to close; as well as Based on the estimated fuel discharge amount, a purge valve is controlled to open, wherein the purge valve controls a purge process for discharging gas of the fuel supply line to the outside.

11. The condensate discharge control method according to claim 10, wherein the step of controlling the drain valve to close include: A fuel discharge amount is estimated based on a difference between a pressure on an anode side of the fuel cell stack and an external pressure.

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