Fuel cell startup control system and method

Abstract

A startup control system and method for a fuel cell, the system comprising: a fuel cell configured to generate electricity based on receipt of air and fuel; an air supply system configured to supply air to the cathode of the fuel cell through an air supply line; a fuel supply system configured to supply fuel to the anode of the fuel cell through a fuel supply line, the fuel supply line recirculating fuel discharged from the outlet of the anode of the fuel cell to the inlet of the anode to supply fuel; an air controller configured to control the air supply system so that when a startup ON signal is input, air flowing into the air supply line bypasses the cathode of the fuel cell; and a fuel controller configured to supply new fuel to the fuel supply line when a startup ON signal is input, and to control the fuel supply system to purge the fuel supply line of fuel in a case where air in the air supply line bypasses the cathode of the fuel cell.

Description

Technical Field

[0001] The present invention relates to a fuel cell startup control system and method, and more particularly, to a sequence when restarting a fuel cell in a case where power generation is stopped. Background Art

[0002] Fuel cells are used as power generation equipment, directly converting chemical energy generated by the oxidation of a fuel into electrical energy. The reactions in fuel cells are similar to those in chemical cells, which utilize oxidation and reduction reactions. However, unlike chemical cells, which perform reactions within a closed system, in fuel cells, reactants are continuously supplied from the outside, and reaction products are continuously removed from the system. Fuel cell power generation systems have recently entered practical use, and because the reaction product of fuel cells is pure water, research into their use as a power source for environmentally friendly vehicles has been actively pursued.

[0003] A fuel cell system includes a fuel cell stack that generates electricity through a chemical reaction, an air supply device that supplies air to the cathode of the fuel cell stack, and a hydrogen supply device that supplies hydrogen to the anode of the fuel cell stack. Specifically, air containing oxygen is supplied to the cathode of the fuel cell stack, and hydrogen is supplied to the anode of the fuel cell stack.

[0004] In a fuel cell, when power generation is stopped, the hydrogen concentration in the anode decreases due to crossover and the reaction of residual hydrogen and oxygen. Therefore, when the fuel cell is restarted, the anode hydrogen concentration, which was reduced when the fuel cell power generation was stopped, needs to be increased. Specifically, an optimal startup sequence is required to quickly ensure anode hydrogen concentration while meeting emission regulations.

[0005] What is described as the prior art is only provided to help understanding the background of the present invention and should not be considered as corresponding to the prior art known to one of ordinary skill in the art. Summary of the Invention

[0006] An object of the present invention is to provide a fuel cell startup control system and method that can quickly restore power generation of the fuel cell while meeting emission regulations.

[0007] According to an embodiment of the present invention, a startup control system of a fuel cell includes: a fuel cell configured to generate electricity when receiving air and fuel; an air supply system configured to supply air to the cathode of the fuel cell through an air supply line; a fuel supply system configured to supply fuel to the anode of the fuel cell through a fuel supply line, and the fuel supply line recirculates the fuel discharged from the outlet of the anode of the fuel cell to the inlet of the anode to supply the fuel; an air controller configured to control the air supply system so that when a startup ON signal is input, the air flowing into the air supply line bypasses the cathode of the fuel cell; and a fuel controller configured to supply new fuel to the fuel supply line when a startup ON signal is input, and to control the fuel supply system to purge the fuel supply line of the fuel when the air in the air supply line bypasses the cathode of the fuel cell.

[0008] The air supply system may include: an air compressor configured to supply air to the air supply line; and a bypass line branched from the air supply line at an inlet of a cathode of the fuel cell and configured to join the air supply line at an outlet of the cathode by bypassing the fuel cell.

[0009] The air supply system may include a control valve provided in the air supply line at the inlet or outlet of the cathode of the fuel cell and configured to control the amount of air flowing into the cathode of the fuel cell through the air supply line.

[0010] The air controller may control the control valve so that the amount of air flowing into the cathode of the fuel cell or the opening of the control valve is gradually increased according to a preset increase rate.

[0011] The air controller may further include a power controller configured to control the air supply system so that when the hydrogen concentration of the fuel supply line is greater than or equal to a preset concentration or when the purging of the fuel supply line is completed, air is supplied to the cathode of the fuel cell through the air supply line, and the power controller is configured to control the output voltage of the fuel cell to a preset voltage or to control the output current of the fuel cell to remain below a preset current.

[0012] The fuel supply system may include: a discharge line that branches from the fuel supply line at the outlet of the anode of the fuel cell and is connected to the outlet of the cathode; and a discharge valve that is provided at the discharge line; and the fuel controller is configured to purge the fuel of the fuel supply line to the air supply line by opening the discharge valve.

[0013] The drain line may be connected to a water trap that collects moisture in the fuel supply line, and wherein the fuel controller is configured to control an opening time of the drain valve based on a water level of the water trap and a pressure of the water trap.

[0014] According to another embodiment of the present invention, a startup control method for a fuel cell includes the following steps: receiving a startup ON signal when power generation of the fuel cell is stopped; controlling the air supply system so that the air flowing into the air supply line bypasses the cathode of the fuel cell, and at the same time, supplying new fuel to the fuel supply line in response to receiving the startup ON signal, the fuel supply line supplies fuel to the anode of the fuel cell; and controlling the fuel supply system so that the fuel of the fuel supply line is purged when the air of the air supply line bypasses the cathode of the fuel cell.

[0015] The startup control method may further include: after controlling the fuel supply system to purge fuel from the fuel supply line, when a hydrogen concentration of the fuel supply line is higher than or equal to a preset concentration or when purging of the fuel supply line is completed, controlling the air supply system to supply air to a cathode of the fuel cell through the air supply line.

[0016] In controlling the air supply system to supply air to the cathode of the fuel cell, the hydrogen concentration of the fuel supply line can be estimated based on the amount of fuel supplied to the fuel supply line, the amount of fuel purged in the fuel supply line, and the crossover amount between the anode and cathode.

[0017] In controlling the air supply system to supply air to the cathode of the fuel cell, the control valve in the air supply line arranged at the inlet or outlet of the cathode of the fuel cell can be controlled so that the amount of air flowing into the cathode of the fuel cell or the opening of the control valve gradually increases according to a preset increase rate.

[0018] The startup control method may further include controlling an output voltage of the fuel cell to a preset voltage or controlling an output current of the fuel cell to remain below a preset current after controlling the air supply system to supply air to a cathode of the fuel cell.

[0019] The startup control method may further include: after receiving the startup ON signal, connecting the fuel cell to a cathode oxygen consumption (COD) resistor to consume the output voltage; and connecting a relay that relays between an output terminal of the fuel cell and a consumer that consumes power generated by the fuel cell.

[0020] The fuel supply system is controlled to purge the fuel in the fuel supply line to the air supply line by opening a purge valve provided at a purge line connected from the fuel supply line to the air supply line.

[0021] In controlling the fuel supply system to purge fuel from the fuel supply line, an opening time of the drain valve is controlled based on a water level of a water trap that collects moisture from the fuel supply line and a pressure of the water trap. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A start-up control sequence of a fuel cell according to the prior art is shown.

[0023] Figure 2 The configuration of a startup control system for a fuel cell according to an embodiment of the present invention is shown.

[0024] Figure 3 A start-up control sequence of a fuel cell according to an embodiment of the present invention is shown.

[0025] Figure 4 Purge control according to the opening of the exhaust valve according to an embodiment of the present invention is shown.

[0026] Figure 5 is a flowchart of a startup control method of a fuel cell according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The specific structural and functional descriptions of the embodiments of the present invention disclosed in this specification are only for illustrative purposes to describe the embodiments of the present invention, and the embodiments of the present invention can be implemented in various ways and are not to be construed as limiting the embodiments described herein.

[0028] In the present invention, various modifications and various modes can be implemented, and therefore, specific embodiments will be illustrated in the drawings and described in detail in this specification. However, it is not intended to limit the present invention to the specific disclosed form, and it will be understood that the present invention includes all changes, equivalents, and substitutes included within the concept and technical scope of the present invention.

[0029] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from other elements. 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 it is mentioned that a certain element is “connected to” or “electrically connected to” a second element, the first element may be directly connected to or electrically connected to the second element, but it should be understood that a third element may be interposed therebetween. On the other hand, when it is mentioned that a certain element is “directly connected to” or “directly electrically connected to” a second element, it should be understood that no third element is interposed therebetween. Other terms used to describe the relationship between constituent elements, such as “between” and “directly between” or “adjacent to” and “directly adjacent to”, are to be interpreted in the same manner.

[0031] The terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention. As long as they can be clearly distinguished in the context, singular expressions include plural expressions. In this application, it should be understood that terms such as "comprises" and "includes" are intended to indicate the presence of features, quantities, steps, operations, constituent elements, parts or combinations thereof described in the specification, and do not exclude the presence or addition of one or more other features, quantities, steps, operations, constituent elements, parts or combinations thereof.

[0032] Unless defined differently, all terms used herein, including technical and scientific terms, have the same meaning as understood by those skilled in the art to which the present invention belongs. These terms, as defined in commonly used dictionaries, should be interpreted as having the same meaning as in the context of the relevant technology, and should not be interpreted as having an ideal or excessive formal meaning unless explicitly defined in this application.

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which the same constituent elements are denoted by the same reference numerals.

[0034] Figure 1 A start-up control sequence of a fuel cell according to the prior art is shown.

[0035] refer to Figure 1 , when a start-up control signal of the fuel cell is input, hydrogen and air are supplied to the fuel cell.

[0036] Specifically, by referring to Figure 2 To help understand the structure only, with the control valve 24 of the air supply line 21 supplying air to the cathode of the fuel cell 10 closed, air is supplied to the bypass line 23 bypassing the cathode of the fuel cell 10 to remove residual hydrogen in the air supply line 21.

[0037] Thereafter, hydrogen remaining in the cathode of the fuel cell 10 is discharged while air is supplied to the cathode of the fuel cell 10 through the air supply line 21 by opening the control valve 24, and then, purge control of the fuel supply line 31 is performed.

[0038] However, according to the related art, since the concentration of hydrogen supplied to the anode of the fuel cell 10 through the fuel supply line 31 cannot be sufficiently ensured, even if air is supplied to the cathode of the fuel cell 10, it takes an unnecessary period of time to increase the output voltage of the fuel cell 10.

[0039] Figure 2 is a configuration of a startup control system of the fuel cell 10 according to an embodiment of the present invention, and Figure 3A start-up control sequence of the fuel cell 10 according to the embodiment of the present invention is shown.

[0040] refer to Figure 2 and Figure 3 , a startup control system of a fuel cell according to an embodiment of the present invention includes: a fuel cell 10, configured to generate electricity based on received air and fuel; an air supply system 20, configured to supply air to the cathode of the fuel cell 10 through an air supply line 21; a fuel supply system 30, configured to supply fuel to the anode of the fuel cell 10 through a fuel supply line 31, which recirculates the fuel discharged from the outlet of the anode of the fuel cell 10 to the inlet of the anode to supply fuel; an air controller, configured to control the air supply system 20 so that when a startup ON signal is input, the air flowing into the air supply line 21 bypasses the cathode of the fuel cell 10; and a fuel controller 50, configured to supply new fuel to the fuel supply line 31 when a startup ON signal is input, and to control the fuel supply system 30 to purge the fuel of the fuel supply line 31 when the air of the air supply line 21 bypasses the cathode of the fuel cell 10.

[0041] The air controller 40, fuel controller 50 and power controller 70 according to the exemplary embodiment of the present invention can be implemented by an algorithm configured to control various components of the vehicle, a non-volatile memory (not shown) configured to store data about software commands for reproducing the algorithm, and a processor (not shown) configured to perform the operations described below using the data stored in the corresponding memory. Here, the memory and the processor can be implemented as separate chips. Alternatively, the memory and the processor can be implemented as a single chip integrated with each other. The processor can take the form of one or more processors.

[0042] The fuel cell 10 may be a fuel cell stack including a membrane electrode assembly (MEA) therein. When oxygen and hydrogen in the air supplied from the air supply system 20 and the fuel supply system 30 chemically react with each other in the fuel cell 10, electric energy may be generated.

[0043] The air supply system 20 may be connected to the cathode of the fuel cell 10 to supply air to the inside of the fuel cell 10. Specifically, the air supply system 20 may draw in external air and supply the air to the fuel cell 10 and may discharge air exhausted from the fuel cell 10 to the outside again.

[0044] The fuel supply line 31 may be connected to the anode of the fuel cell 10 to supply fuel to the interior of the fuel cell 10. Specifically, the fuel supplied to the anode may be hydrogen. More specifically, the fuel supply system 30 may include a hydrogen tank storing hydrogen therein, and the hydrogen stored in the hydrogen tank may be supplied to the fuel supply line 31, which recirculates the hydrogen-containing gas exhausted from the anode to the anode.

[0045] When the start-up ON signal is input, the air controller 40 can immediately control the supply of air to the air supply line 21. The supply of air to the air supply line 21 can be controlled by driving an air compressor 22 connected to the air supply line 21 to be described later, etc. Specifically, the air controller 40 can control the air supply to bypass the cathode of the fuel cell 10 while discharging or diluting the residual hydrogen in the air supply line 21.

[0046] The fuel controller 50 can supply new fuel to the fuel supply line 31 so that the fuel is circulated through the fuel supply line 31. Specifically, the fuel controller 50 can control the fuel supply by opening a hydrogen supply valve connected to a hydrogen tank. In one embodiment, the hydrogen tank can be connected to the fuel supply line 31 via an injector so that hydrogen from the hydrogen tank can be supplied to the fuel supply line 31 and the gas containing hydrogen inside the fuel supply line 31 can be circulated.

[0047] At the same time, the fuel controller 50 may control the fuel supply system 30 to purge the fuel supply line 31. In one embodiment, in the purge control of the fuel supply system 30, the gas containing the fuel from the fuel supply line 31 is discharged to the air supply line 21. Therefore, the hydrogen concentration in the recirculated fuel supply line 31 may be increased.

[0048] For the startup control according to an embodiment of the present invention, when the startup ON signal is input, the hydrogen concentration in the anode of the fuel cell 10 can be quickly ensured, and at the same time, the hydrogen is diluted in the air bypassing the cathode of the fuel cell 10, thereby obtaining the effect of meeting emission regulations.

[0049] More specifically, the air supply system 20 may include: an air compressor 22 that supplies air to the air supply line 21; and a bypass line 23 that branches from the air supply line 21 at the inlet of the cathode of the fuel cell 10 and joins to the air supply line 21 at the outlet of the cathode by bypassing the fuel cell 10.

[0050] The air compressor 22 may be located at an inlet of the air supply line 21 , draw in external air, and supply the drawn in air to the air supply line 21 .

[0051] The bypass line 23 may branch from the air supply line 21 and rejoin the air supply line 21 by bypassing the cathode of the fuel cell 10. That is, the air flowing into the air supply line 21 may flow into the cathode of the fuel cell 10 or may bypass the fuel cell 10 through the bypass line 23 and be discharged to the outside.

[0052] The air supply system 20 may include a control valve 24 located in the air supply line 21 at the inlet or outlet of the cathode of the fuel cell 10 and controlling the amount of air flowing into the cathode of the fuel cell 10 through the air supply line 21 .

[0053] In one embodiment, the control valve 24 may be a two-way valve located at the inlet of the cathode of the fuel cell 10 at a point downstream from the point where it branches off from the bypass line 23, or at the outlet of the cathode of the fuel cell 10 at a point upstream from the point where it joins the bypass line 23. The air flowing into the air supply line 21 can be caused to flow into the cathode of the fuel cell 10 by opening the control valve 24.

[0054] In another embodiment, the control valve 24 may be a three-way valve located at the point where the air supply line 21 and the bypass line 23 branch or join.

[0055] The air controller 40 may control the control valve 24 so that the amount of air flowing into the cathode of the fuel cell 10 or the opening degree of the control valve 24 is gradually increased according to a preset increase rate.

[0056] In one embodiment, the air controller 40 may control the control valve 24 such that the amount of air flowing from the air supply line 21 to the cathode of the fuel cell 10 is gradually increased according to a preset increase rate.

[0057] In another embodiment, the air controller 40 can control the control valve 24 so that the opening of the control valve 24 increases gradually according to a preset increase rate. The air controller 40 can control the opening of the control valve 24 to increase linearly at a constant rate as time passes, such as Figure 3 shown.

[0058] The air controller 40 may also include a power controller 70, which controls the air supply system 20 to supply air to the cathode of the fuel cell 10 through the air supply line 21 when the hydrogen concentration of the fuel supply line 31 is higher than or equal to a preset concentration or when the purging of the fuel supply line 31 is completed, controls the output voltage of the fuel cell 10 to be a preset voltage, or controls the output current of the fuel cell 10 to be maintained at a certain level below the preset current.

[0059] When the hydrogen concentration of the fuel supply line 31 is greater than or equal to the preset concentration, the fuel controller 50 may determine that the purging of the fuel supply line 31 is completed. After the purging of the fuel supply line 31 is completed, the air controller 40 may supply air to the cathode of the fuel cell 10 through the air supply line 21.

[0060] When air is supplied to the cathode of the fuel cell 10, electricity may be generated within the fuel cell 10 through a chemical reaction between oxygen in the air and the fuel at the anode. The power controller 70 may control the output power of the fuel cell 10.

[0061] Specifically, when a start ON signal is input, air is supplied to the air supply line 21 while hydrogen is supplied to the fuel supply line 31 , and at the same time, the power controller 70 may connect the fuel cell 10 to a cathode oxygen consumption (COD) resistor to consume output voltage.

[0062] When the COD control for connecting the fuel cell 10 to the COD resistor is completed, the power controller 70 may connect the relay 60 that relays between the output terminal of the fuel cell 10 and the consumer 61 that consumes the power generated by the fuel cell 10 .

[0063] Here, the consumer equipment 61 as an equipment that consumes the power generated by the fuel cell 10 may be a drive motor, an auxiliary device, or a high-voltage battery (in a charged state).

[0064] Specifically, after starting to supply air to the cathode of the fuel cell 10 , the power controller 70 may control the output voltage of the fuel cell 10 to be a preset voltage or control the output current of the fuel cell 10 to be maintained below a preset current.

[0065] Here, the preset voltage may be a voltage at which the durability of the fuel cell 10 does not deteriorate as the output voltage of the fuel cell 10 increases in the light-load output range of the fuel cell 10. For example, the preset voltage may be a voltage at which the cell voltage of the fuel cell 10 is approximately 0.8 V, at which durability degradation is prevented.

[0066] Specifically, the power controller 70 may increase the output voltage of the fuel cell 10 to follow a preset voltage, and control the output voltage of the fuel cell 10 not to exceed the preset voltage.

[0067] In addition, the power controller 70 can control the output current of the fuel cell 10 to remain below a preset current. Specifically, the power controller 70 can limit the output current of the fuel cell 10 so that the output current of the fuel cell 10 does not increase to become the output voltage of the fuel cell 10.

[0068] In one embodiment, the preset current may be a current at which the output of the fuel cell 10 is maximized according to the performance curve IV of the fuel cell 10. When the output current of the fuel cell 10 is the preset current, the output voltage of the fuel cell 10 may be less than the preset voltage.

[0069] The fuel supply system 30 may include a discharge line 32, which branches from the fuel supply line 31 at the outlet of the anode of the fuel cell 10 and is connected to the outlet of the cathode of the fuel cell 10, and a discharge valve 33, which is arranged at the discharge line 32; and the fuel controller 50 can purge the fuel in the fuel supply line 31 to the air supply line 21 by opening the discharge valve 33.

[0070] More specifically, the drain line 32 may be connected to a water collector 34 that collects moisture in the fuel supply line 31. The water collector 34 may be located in the fuel supply line 31 downstream of the anode of the fuel cell 10 and may collect moisture generated by power generation in the fuel cell 10 and transfer it to the anode side. The drain line 32 may discharge the moisture in the water collector 34 to the air supply line 21.

[0071] The fuel controller 50 may purge the fuel-containing gas of the fuel supply line 31 to the air supply line 21 by opening the discharge valve 33. When the discharge valve 33 is opened, moisture collected by the water collector 34 may be initially discharged, and when moisture discharge is completed, the fuel-containing gas may be discharged.

[0072] Figure 4 Purge control according to the opening of the discharge valve 33 according to the embodiment of the present invention is shown.

[0073] refer to Figure 4 , the fuel controller 50 may control the opening time of the discharge valve 33 based on the water level of the water collector 34 and the pressure of the water collector 34 .

[0074] Specifically, the water collector 34 may further include a water level sensor for sensing collected moisture, and the fuel controller 50 may control the opening time of the discharge valve 33 based on the water level of the water collector 34 .

[0075] More specifically, when the water level of the water collector 34 is less than a preset minimum measurement value of the water level sensor, the fuel controller 50 may control the initial purge time (a+t) based on a previously mapped control map.

[0076] In contrast, when the water level of the water collector 34 is higher than or equal to a preset minimum measurement value of the water level sensor, the fuel controller 50 may control the initial purge time (a+b+t) based on the water level sensed by the water level sensor and a preset control map.

[0077] Specifically, the fuel controller 50 may predict the time when the water is discharged based on the water level sensed by the water level sensor and the pressure difference between the pressure of the water collector 34 and the atmospheric pressure.

[0078] The fuel controller 50 may control to remove moisture collected in the water collector 34 at the first purge, and after the first purge, assuming that no new moisture is present in the fuel cell 10 , the fuel controller 50 may control using a preset purge time.

[0079] The purge time and purge interval may be preset based on the amount of air supplied to the air supply line 21. The number of purge times may be set based on the hydrogen concentration in the fuel supply line 31. Specifically, the fuel controller 50 may perform the purge until the hydrogen concentration in the fuel supply line 31 is higher than or equal to a preset concentration.

[0080] In addition, the discharge valve 33 can control the opening time of the discharge valve 33 based on the pressure of the water collector 34. Specifically, the discharge valve 33 can estimate the amount of gas containing hydrogen discharged when the discharge valve 33 is opened over time based on the pressure difference between the pressure of the water collector 34 and the atmospheric pressure, and control the opening time of the discharge valve 33 based on the estimated amount of gas.

[0081] In another embodiment, the discharge line 35 and the discharge valve 36 may be further provided separately from the discharge valve 33 , and the fuel controller 50 may control the discharge valve 33 and the discharge valve 36 individually.

[0082] The fuel controller 50 may estimate the hydrogen concentration of the fuel supply line 31 based on the amount of fuel supplied to the fuel supply line 31 , the amount of fuel purged at the fuel supply line 31 , and the amount of crossover between the anode and the cathode.

[0083] Specifically, when the fuel cell 10 is restarted using the hydrogen concentration of the fuel supply line 31 estimated at the start-up of the fuel cell 10, the fuel controller 50 can estimate the amount of nitrogen (the number of moles of nitrogen) and the amount of steam (the number of moles of steam), and monitor the hydrogen concentration of the fuel supply line 31 by reflecting the estimated amounts of nitrogen and steam, the crossover amount of nitrogen and steam, and the purge amount of nitrogen and steam.

[0084] In one embodiment, the hydrogen concentration of the fuel supply line 31 estimated at the start-up of the fuel cell 10 may be estimated by a map mapped in advance according to a time during which the fuel cell 10 stops generating power.

[0085] The hydrogen concentration of the fuel supply line 31 can be monitored using the amount of hydrogen calculated by subtracting the amount of nitrogen and the amount of steam from the total amount of gas in the fuel supply line 31 .

[0086] The total amount of gas (n) in the fuel supply line 31 can be estimated from the ideal gas state equation as shown in the following equation using the gas pressure (P), volume (V), and temperature (T) of the fuel supply line 31. An ).

[0087] n An =(P An ·V An )RT[mol]

[0088] Here, R is the gas constant, which is 8.314 [J / molK].

[0089] The gas diffusion rate may be inversely proportional to the thickness of the electrolyte membrane of the fuel cell stack 10 and may be proportional to the gas partial pressure difference between the anode side and the cathode side. Specifically, the crossover gas amount may be calculated by applying FICK's law (diffusion law) as follows.

[0090]

[0091] here, is the mass diffusion rate of the gas (g / s), A is the diffusion area, D is the gas diffusion coefficient, x is the diffusion distance, c is the gas concentration, R is the universal gas constant (8.314 J / mol), P is the gas pressure, T is the gas temperature, and M is the molar mass of the gas (g / mol). This can be summarized as follows.

[0092]

[0093]

[0094] here, is the gas diffusion rate (mol / s).

[0095] That is, the gas crossover amount between the electrolyte membranes of the fuel cell 10 can be calculated by the following equation.

[0096]

[0097] here, is the diffusion rate of nitrogen, P is the pressure, [kPa], R is the gas constant δ8.314 [J / mol / K], T is the temperature, [K], D is the diffusion coefficient, A is the area of the electrolyte membrane, is the thickness of the electrolyte membrane, and P Ca,N2 is the partial pressure of nitrogen on the cathode side of the fuel cell 10, and P An,N2 is the partial pressure of nitrogen on the anode side of the fuel cell 10 .

[0098]

[0099] here, is the diffusion rate of vapor; P is the pressure, [kPa]; R is the gas constant, 8.314 [J / mol / K]; T is the temperature, [K], D is the diffusion coefficient; A is the area of the electrolyte membrane; δ is the thickness of the electrolyte membrane; P Ca,V is the partial pressure of the vapor on the cathode side of the fuel cell 10; and P An,V is the partial pressure of the vapor on the anode side of the fuel cell 10 .

[0100] Conversely, hydrogen may cross from the anode side to the cathode side of the fuel cell 10 .

[0101]

[0102] here, is the diffusion rate of hydrogen, P is the pressure, [kPa], R is the gas constant, 8.314 [J / mol / K], T is the temperature, [K], D is the diffusion coefficient, A is the area of the electrolyte membrane, δ is the thickness of the electrolyte membrane, and P An,H2 is the hydrogen partial pressure on the anode side, and P Ca,H2 is the hydrogen partial pressure on the cathode side.

[0103] In addition, the gas diffusion rate may be proportional to the gas diffusion coefficient, and the gas diffusion coefficient may vary according to the moisture content and temperature of the electrolyte membrane located between the anode side and the cathode side of the fuel cell 10 .

[0104] The gas diffusion coefficient D may be a fixed constant value, but to further improve accuracy, the gas diffusion coefficient D may be a value that varies according to conditions such as the degree of degradation and the temperature of the fuel cell 10. More specifically, the gas diffusion coefficient D may be calculated using a value that varies depending on the moisture content and temperature of the electrolyte membrane located between the anode side and the cathode side of the fuel cell 10. In addition, the gas diffusion coefficient D may be calculated to vary with degradation of the electrolyte membrane of the fuel cell 10.

[0105] Gas removal rate Can be compared with the gas pressure on the anode side (P An ) and external air pressure (P out ) is proportional to the pressure difference between the external air pressure (P out ) may be the gas pressure on the cathode side. The specific equation may be as follows.

[0106]

[0107] Here, P wt is the pressure of the water collector 34, P ambis the atmospheric pressure, and C is a purge gain value determined according to the purge cycle, the opening of the discharge valve 33, and the opening time of the discharge valve 33 at the time of purge.

[0108] Specifically, the nitrogen removal rate can be expressed as follows: Vapor removal rate Hydrogen removal rate To calculate the removal rate for each gas.

[0109]

[0110]

[0111]

[0112] The initial amount of nitrogen and the initial amount of steam in the fuel supply line 31 can be predicted respectively, the amount of nitrogen and steam crossed on the anode side and the amount of nitrogen and steam purged on the anode side can be calculated respectively, and the current amount of nitrogen in the fuel supply line 31 can be calculated based on the amount of crossed nitrogen and the amount of purged nitrogen, and the current amount of steam in the fuel supply line 31 can be calculated based on the predicted initial amount of steam, the amount of crossed nitrogen, and the amount of purged steam.

[0113] That is, the current amount of nitrogen and the current amount of steam can be calculated by integrating the diffusion rate and the removal rate per unit time with respect to the initial amount over time using the above equations.

[0114] The current amount of hydrogen may be calculated by subtracting the current amount of nitrogen and the current amount of steam from the amount of gas in the fuel supply line 31 .

[0115] Therefore, assuming that the gas concentration of the fuel supply line 31 is uniform, the hydrogen concentration of the fuel supply line 31 can be monitored by calculating the total gas amount of the fuel supply line 31, the current amount of nitrogen, the current amount of steam, and the current amount of hydrogen.

[0116] Therefore, the hydrogen concentration, which is difficult to estimate from the nitrogen amount and the steam amount due to the reaction with oxygen, can be continuously monitored by calculating the hydrogen concentration.

[0117] In addition, when the water level does not change according to the critical time after the discharge valve 33 is opened, the hydrogen concentration may be estimated by adding the critical time.

[0118] The fuel controller 50 may set the amount of purge by comparing the estimated hydrogen concentration of the fuel supply line 31 with a preset concentration. Here, the preset concentration may be set to, for example, approximately 60%.

[0119] Figure 51 is a flowchart of a startup control method of the fuel cell 10 according to an embodiment of the present invention.

[0120] Further references Figure 5 According to an embodiment of the present invention, the startup control method of the fuel cell 10 includes: a step of receiving a startup ON signal when power generation of the fuel cell 10 is stopped (S100); a step of controlling the air supply system 20 so that the air flowing into the air supply line 21 bypasses the cathode of the fuel cell 10, and at the same time, supplying new fuel to the fuel supply line 31 when the startup ON signal is input (S200), and the fuel supply line 31 supplies fuel to the anode of the fuel cell 10; and a step of controlling the fuel supply system 30 so that the fuel of the fuel supply line 31 is purged when the air of the air supply line 21 bypasses the cathode of the fuel cell 10 (S500).

[0121] In the step of receiving the start-ON signal ( S100 ), an ignition start signal may be input from an electronic control unit (ECU).

[0122] The startup control method may further include, after controlling the fuel supply system 30 to purge the fuel of the fuel supply line 31 (S500), when the hydrogen concentration of the fuel supply line 31 is higher than or equal to a preset concentration or when the purging of the fuel supply line 31 is completed (S600), controlling the air supply system 20 to supply air to the cathode of the fuel cell 10 through the air supply line 21 (S700).

[0123] In the step (S700) of controlling the air supply system 20 to supply air to the cathode of the fuel cell 10, the hydrogen concentration of the fuel supply line 31 can be estimated based on the amount of fuel supplied to the fuel supply line 31, the amount of fuel purged in the fuel supply line 31, and the crossover amount between the anode and the cathode.

[0124] In the step (S700) of controlling the air supply system 20 to supply air to the cathode of the fuel cell 10, the control valve 24 in the air supply pipeline 21 located at the inlet or outlet of the cathode of the fuel cell 10 can be controlled so that the amount of air flowing into the cathode of the fuel cell 10 or the opening of the control valve 24 gradually increases according to a preset increase rate.

[0125] The startup control method of the fuel cell 10 may further include, after the step (S700) of controlling the air supply system 20 to supply air to the cathode of the fuel cell, a step (S800) of controlling the output voltage of the fuel cell 10 to a preset voltage or controlling the output current of the fuel cell 10 to remain below a preset current.

[0126] The startup control method of the fuel cell 10 may also include, after receiving the startup ON signal (S100), a step (S310) of connecting the fuel cell 10 to a cathode oxygen consumption (COD) resistor to consume the output voltage, and a step (S320) of connecting a relay that relays the connection between the output terminal of the fuel cell 10 and a consumer device 61 that consumes the power generated by the fuel cell 10.

[0127] In the step (S500) of controlling the fuel supply system 30 to purge the fuel of the fuel supply line 31, the fuel of the fuel supply line 31 can be purged to the air supply line 21 by opening the discharge valve 33, which is provided at the discharge line 32 connected from the fuel supply line 31 to the air supply line 21.

[0128] The startup control method of the fuel cell 10 may further include the step of determining whether draining of the fuel supply line 31 can be controlled ( S400 ) before the step of controlling the fuel supply system 30 to purge the fuel supply line 31 of the fuel ( S500 ).

[0129] In the step (S400) of determining whether the discharge of the fuel supply line 31 can be controlled, it can be determined whether it is lower than the temperature at which water freezes (0°C), and if the temperature is lower than the temperature at which water freezes, if the water level of the water collector 34 is lower than or equal to a preset water level (e.g., 5 mm) when it has been closed before startup, it can be determined that the discharge cannot be controlled.

[0130] In addition, the inclination of the vehicle may be received, and when the inclination of the vehicle is greater than or equal to a preset inclination, it is determined that the moisture stored in the sump 34 is frozen and the discharge valve 33 is closed, thus disabling discharge.

[0131] In the step ( S500 ) of controlling the fuel supply system 30 to purge the fuel supply line 31 of fuel, the opening time of the drain valve 33 may be controlled based on the water level of the water collector 34 of moisture collected in the fuel supply line 31 and the pressure of the water collector 34 .

[0132] According to the startup control system and method of the fuel cell of the present invention, when the startup ON signal is input, the hydrogen concentration is quickly ensured at the anode of the fuel cell.

[0133] Additionally, emissions regulations can be met due to the dilution of hydrogen purged in the air that bypasses the cathode of the fuel cell.

[0134] Additionally, by estimating the hydrogen concentration in the fuel supply line and performing purge control at the start of startup, unnecessary hydrogen emissions are prevented, thereby improving fuel efficiency.

[0135] While the present invention has been shown and described with respect to the particular embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1. A fuel cell startup control system, comprising: a fuel cell configured to generate electricity upon receiving air and fuel; an air supply system configured to supply air to the cathode of the fuel cell through an air supply line; a fuel supply system configured to supply fuel to the anode of the fuel cell through a fuel supply line, wherein the fuel supply line recirculates the fuel discharged from the outlet of the anode of the fuel cell to the inlet of the anode to supply the fuel; an air controller configured to control the air supply system so that, when a start-up ON signal is input, air flowing into the air supply line bypasses the cathode of the fuel cell; as well as A fuel controller is configured to supply new fuel to the fuel supply line when the start-up ON signal is input, and control the fuel supply system to purge fuel from the fuel supply line in a case where air from the air supply line bypasses the cathode of the fuel cell.

2. The startup control system according to claim 1, wherein: The air supply system comprises: an air compressor configured to supply air to the air supply line; and A bypass line branches from the air supply line at an inlet of a cathode of the fuel cell and is configured to be joined to the air supply line at an outlet of the cathode by bypassing the fuel cell.

3. The startup control system according to claim 1, wherein: The air supply system includes a control valve provided in the air supply line at an inlet or an outlet of a cathode of the fuel cell and configured to control an amount of air flowing into the cathode of the fuel cell through the air supply line.

4. The startup control system according to claim 3, wherein: The air controller controls the control valve so that the amount of air flowing into the cathode of the fuel cell or the opening degree of the control valve increases stepwise according to a preset increase rate.

5. The startup control system according to claim 1, wherein: The air controller also includes a power controller, which is configured to control the air supply system so that when the hydrogen concentration of the fuel supply line is greater than or equal to a preset concentration or when the purging of the fuel supply line is completed, air is supplied to the cathode of the fuel cell through the air supply line, and the power controller is configured to control the output voltage of the fuel cell to a preset voltage or to control the output current of the fuel cell to remain below a preset current.

6. The startup control system according to claim 1, wherein: The fuel supply system comprises: a discharge line branched from the fuel supply line at an outlet of the anode of the fuel cell and connected to an outlet of the cathode; and a discharge valve provided at the discharge line; and Wherein, the fuel controller is configured to purge fuel from the fuel supply line to the air supply line by opening the drain valve.

7. The startup control system according to claim 6, wherein: The drain line is connected to a water trap that collects moisture in the fuel supply line, and The fuel controller is configured to control the opening time of the discharge valve based on the water level of the water collector and the pressure of the water collector.

8. A fuel cell startup control method, comprising the following steps: When the power generation of the fuel cell is stopped, a start-up ON signal is received; controlling an air supply system so that air flowing into an air supply line bypasses a cathode of the fuel cell while supplying new fuel to a fuel supply line that supplies fuel to an anode of the fuel cell in response to receiving a start-up ON signal; as well as The fuel supply system is controlled so that the fuel supply line is purged of fuel while air from the air supply line bypasses the cathode of the fuel cell.

9. The startup control method according to claim 8, further comprising: After controlling the fuel supply system to purge the fuel supply line of fuel, when the hydrogen concentration of the fuel supply line is higher than or equal to a preset concentration or when purging of the fuel supply line is completed, controlling the air supply system to supply air to the cathode of the fuel cell through the air supply line.

10. The startup control method according to claim 9, wherein: Controlling the air supply system to supply air to the cathode of the fuel cell includes estimating a hydrogen concentration of the fuel supply line based on an amount of fuel supplied to the fuel supply line, an amount of fuel purged in the fuel supply line, and an amount of crossover between the anode and the cathode.

11. The startup control method according to claim 9, wherein: Controlling the air supply system to supply air to the cathode of the fuel cell includes: controlling the control valve in the air supply line arranged at the inlet or outlet of the cathode of the fuel cell so that the amount of air flowing into the cathode of the fuel cell or the opening of the control valve gradually increases according to a preset increase rate.

12. The startup control method according to claim 9, further comprising: After controlling the air supply system to supply air to the cathode of the fuel cell, the output voltage of the fuel cell is controlled to be a preset voltage or the output current of the fuel cell is controlled to be maintained below a preset current.

13. The startup control method according to claim 8, further comprising: After receiving the start-up ON signal, connecting the fuel cell to a cathode oxygen consumption resistor to consume the output voltage; as well as A relay is connected between the output terminal of the fuel cell and a consumer device that consumes the power generated by the fuel cell.

14. The startup control method according to claim 8, wherein: Controlling the fuel supply system to purge the fuel supply line of fuel includes purging the fuel supply line of fuel to the air supply line by opening a purge valve provided at a purge line connected from the fuel supply line to the air supply line.

15. The startup control method according to claim 14, wherein: Controlling the fuel supply system to purge the fuel supply line of the fuel includes controlling an opening time of the drain valve based on a water level of a water collector collecting moisture in the fuel supply line and a pressure of the water collector.

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