KR101844285B1 - Fuel cell system and control method for the same - Google Patents

Abstract

The fuel cell system determines the supply state of fuel and air based on the generation voltage of the fuel cell confirmed at least at one point in time from the start of supply of fuel and air until the target voltage is reached, and a control method thereof.
A fuel cell system according to an embodiment includes a fuel cell stack in which a plurality of unit cells including an air electrode and a fuel electrode are stacked; And checking the generation voltage of each of the plurality of unit cells at least at a time point after the start of supply of the fuel and the air until the generation voltage of the fuel cell stack reaches a target voltage, A control unit for determining a supply state of the fuel and the air based on the control signal; . ≪ / RTI >

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fuel cell system,

The present invention relates to a fuel cell system that generates electricity using supplied fuel and air, and a control method thereof.

The fuel cell is a power generation system that converts chemical energy of fuel (hydrogen, methanol, coal, natural gas, petroleum, biomass gas, landfill gas, etc.) directly into electric energy by electrochemical reaction. It is a technology that simultaneously produces electricity and heat while reducing the generation efficiency and emissions of pollutants.

The fuel cell stack is composed of unit cells arranged in series. Each unit cell has a membrane-electrode assembly (MEA) located in the innermost part thereof. The membrane- And an electrode layer coated on both surfaces of the electrolyte membrane so that hydrogen and oxygen can react with each other.

The fuel cell can output a predetermined target voltage when fuel and air are supplied. The time required for the output voltage to finally reach the target voltage is referred to as a delay time. At this time, the delay time may vary depending on the mechanical and electrical resistance of the fuel / air supply means, the humidity inside the fuel cell, the temperature, and the like.

According to an embodiment of the disclosed invention, there is provided a fuel cell system for determining a supply state of fuel and air based on a generation voltage of a fuel cell identified at least at a time point from the start of supply of fuel and air until reaching a target voltage, System and a control method thereof.

A fuel cell system according to an embodiment includes a fuel cell stack in which a plurality of unit cells including an air electrode and a fuel electrode are stacked; And checking the generation voltage of each of the plurality of unit cells at least at a time point after the start of supply of the fuel and the air until the generation voltage of the fuel cell stack reaches a target voltage, A control unit for determining a supply state of the fuel and the air based on the control signal; . ≪ / RTI >

The control unit may control the fuel cell stack based on a difference between a first generation voltage of each of the plurality of unit cells and a predetermined reference generation voltage after a predetermined first reference time from the start of supply of fuel and air to the fuel cell stack, The supply state of the fuel and the air can be determined.

The control unit may be configured to check the first generation voltage of each of the plurality of unit cells with respect to each of the plurality of fuel cell stacks if the fuel cell stack is a plurality, The supply state of the fuel and the air can be determined by comparing the generated voltage patterns.

In addition, the control unit may abnormally determine the supply state of the fuel and the air if the difference between the at least two first generation voltage patterns of the plurality of fuel cell stacks exceeds a predetermined reference difference.

Also, the control unit refers to the second generation voltage of each of the plurality of unit cells after a predetermined second reference time from the time when the fuel and air are supplied to the fuel cell stack, The state can be determined.

The control unit may store the second generation voltage before the start of supply of the fuel and the air after interrupting the fuel and the air supplied to the fuel cell stack, When the supply is started, the stored second generation voltage can be referred to.

The control unit may determine the supply state of the air based on a delay time from when the fuel and the air are supplied until the power generation voltage of the fuel cell stack reaches a predetermined reference power generation voltage.

A fuel supply unit including a purge valve provided in a first path through which the fuel is discharged from the fuel cell stack and a drain valve provided in a second path through which water is discharged from the fuel cell stack; And an air shutoff valve provided in a third path through which the air is supplied to the fuel cell stack; And the control unit may check the state of the purge valve, the drain valve, and the air shutoff valve when the supply state of the fuel and the air is determined to be abnormal.

The purge valve, the drain valve, and the drain valve may be connected to the fuel cell stack so that the fuel is normally supplied to the fuel cell stack when the state of the purge valve, the drain valve, It can be opened and closed periodically.

The control unit may periodically open / close the air shutoff valve to normally supply the air to the fuel cell stack when the purge valve, the drain valve, and the air shutoff valve are confirmed as normal.

A control method of a fuel cell system according to an embodiment includes: supplying fuel and air to a fuel cell stack;

Confirming a generation voltage of each of the plurality of unit cells at least at a time point after the start of supply of the fuel and the air until a generation voltage of the fuel cell stack reaches a target voltage; And determining a supply state of the fuel and the air based on the detected generation voltage; . ≪ / RTI >

The step of confirming the generation voltage of each of the plurality of unit cells may include the step of determining a first generation voltage of each of the plurality of unit cells after a predetermined first reference time from the start of supply of fuel and air to the fuel cell stack And determining the supply state of the fuel and the air may determine the supply state of the fuel and the air based on a difference between the first generation voltage and a predetermined reference generation voltage.

The step of verifying the generation voltage of each of the plurality of unit cells may further include checking the first generation voltage of each of the plurality of unit cells with respect to each of the plurality of fuel cell stacks when the fuel cell stack is a plurality, The step of determining the supply state of the fuel and the air may determine the supply state of the fuel and the air by comparing the first generation voltage pattern of each of the plurality of fuel cell stacks.

In addition, the step of determining the supply state of the fuel and the air may include: when the difference between the at least two first generation voltage patterns of the plurality of fuel cell stacks exceeds a predetermined reference difference, The state can be determined abnormally.

The step of determining the supply state of the fuel and the air may include determining a supply state of the fuel and the air based on a second generation voltage of each of the plurality of unit cells after a predetermined second reference time, The supply state of the fuel and the air can be determined.

Storing the second generation voltage before the supply of the fuel and the air is started after the fuel and the air supplied to the fuel cell stack are cut off; As shown in FIG.

The step of determining the supply state of the fuel and the air may further include determining a supply state of the fuel and the air based on the delay time until the generation voltage of the fuel cell stack reaches a predetermined reference generation voltage, The supply state of the air can be determined.

A first path through which the fuel is discharged from the fuel cell stack, a second path through which water is discharged from the fuel cell stack, and a second path through which the fuel is discharged from the fuel cell stack when the supply state of the fuel and the air is determined to be abnormal. Confirming whether the third path to which air is supplied is normally connected and disconnected; As shown in FIG.

In addition, if it is confirmed that the first path, the second path, and the third path are normally connected and disconnected, at least one of the first path and the second path may be provided so that the fuel is normally supplied to the fuel cell stack Periodically connecting and blocking; As shown in FIG.

Periodically connecting and disconnecting the third path so that the air is normally supplied to the fuel cell stack if it is confirmed that the first path, the second path, and the third path are normally opened and closed; As shown in FIG.

According to one embodiment of the disclosed vehicle and its control method, it is possible to avoid cases where the supply of fuel and air can not reach the target voltage after the start of the supply. As a result, the durability and efficiency of the fuel cell can be improved.

1 is a view showing a unit cell structure of a fuel cell stack according to an embodiment.
2 is a schematic diagram of a fuel cell system according to an embodiment.
FIG. 3 is a graph showing a time-dependent power generation voltage of different unit cells of the fuel cell stack according to an exemplary embodiment of the present invention.
4 is a flowchart of a fuel cell system control method according to an embodiment.
5 is a flowchart of a fuel cell system control method according to another embodiment.

Hereinafter, a fuel cell system and a control method thereof will be described with reference to the accompanying drawings.

The fuel cell is a power generation system that converts chemical energy of fuel (hydrogen, methanol, coal, natural gas, petroleum, biomass gas, landfill gas, etc.) directly into electric energy by electrochemical reaction. It is a technology that simultaneously produces electricity and heat while reducing the generation efficiency and emissions of pollutants.

A fuel cell vehicle is a type of electric vehicle driven by an electric vehicle produced from a fuel cell, and a peripheral device (Balance of Plant) necessary for driving the vehicle is placed around the fuel cell. These peripherals provide the fuel and air needed for the fuel cell according to the driving conditions of the vehicle and also return the cooling water to maintain the proper temperature. Hereinafter, the fuel cell and peripheral devices necessary for driving the fuel cell are collectively referred to as a fuel cell system.

Hereinafter, the fuel cell system and its control method according to the present invention will be described in detail with reference to the case where the fuel cell system is mounted on the fuel cell vehicle.

First, a method of generating a fuel cell system will be described using a unit cell.

1 is a view showing a unit cell structure of a fuel cell stack according to an embodiment.

1, a unit cell 130-1 of a fuel cell stack 130 according to an embodiment includes a membrane electrode assembly (MEA) 10 and a membrane electrode assembly 10 And a gas diffusion layer 30 disposed so as to be adjacent to the water electrolytic layer 20. [ Specifically, the unit cell may have a structure in which the electrolytic solution layer 20, the gas diffusion layer 30, and the separation plate 40 are stacked in order on the left and right sides of the central membrane electrode assembly 10 at the center.

The membrane electrode assembly 10 is provided with a fuel electrode 12 (also referred to as an anode, a hydrogen electrode or an oxidant electrode) and an air electrode 13 (also referred to as a cathode, an oxygen electrode or a reducing electrode) on both sides of the polymer electrolyte membrane 11 . At this time, the membrane electrode assembly 10 has two electrodes integrated with the polymer electrolyte membrane 11, and the structure and performance of the membrane electrode assembly 10 can play a key role in the polymer electrolyte fuel cell.

High-quality hydrogen is supplied to the fuel electrode 12 to cause an electrochemical reaction, and the supplied hydrogen can be separated into hydrogen ions and electrons by the catalyst to generate electricity. A water decomposition catalyst adapted to electrolyze water around the fuel electrode 12 may be applied to the fuel electrode 12 when reverse voltage is applied between the electrodes. For example, a water decomposition catalyst such as manganese phosphate may be applied to the anode 12. However, the examples of the water decomposition catalyst applicable to the fuel electrode 12 are not limited to these examples, and may include examples of ranges easily conceivable to those skilled in the art.

The water decomposition catalyst can promote electrolysis of water generated around the fuel electrode 12 when a reverse voltage is applied, thereby preventing damage to the electrode due to application of reverse voltage.

Air containing oxygen is supplied to the air electrode 13 to generate an electrochemical reaction, and the supplied oxygen can be combined with hydrogen ions and electrons generated in the fuel electrode 12 to generate water.

The gas diffusion layer 30 is provided between the separation plate 40 and the electrodes to distribute the reactive gas uniformly and to transfer the generated electrical energy.

The separation plate 40 is for moving reaction gases and cooling water, and a flow path may be formed therein. Thereby, the separator plate 40 can supply reactants to the membrane electrode assembly 10 and remove water. In addition, the separator plate 40 may serve as a current collector for allowing electrons to move to an external circuit.

Based on this, a method of generating the unit cells of the fuel cell stack will be described in detail.

1, when hydrogen as a fuel and oxygen (air) as an oxidizer are supplied to the fuel electrode 12 and the air electrode 13 of the membrane electrode assembly through the flow path of the separator 40, hydrogen is supplied to the fuel electrode 12 And oxygen (air) may be supplied to the air electrode 13. [0050]

Hydrogen supplied to the fuel electrode 12 is decomposed into hydrogen ions (Proton, H +) and electrons (Electron, e) by the catalyst of the electrode layer provided on both sides of the polymer electrolyte membrane 11, The polymer electrolyte membrane 11 which is a cation exchange membrane is selectively transferred to the air electrode 13 while the electrons can be transmitted to the air electrode 13 through the gas diffusion layer 30 and the separator 40 which are conductors.

In the air electrode 13, the hydrogen ions supplied through the polymer electrolyte membrane 11 and the electrons transferred through the separator 40 meet with oxygen in the air supplied to the air electrode 13 to generate water have. The flow of electrons through the external conductor is generated by the movement of hydrogen ions generated along with the reaction of generating water, and current can be generated by the flow of electrons.

A plurality of the above-described unit cells may be stacked to form one fuel cell stack. The unit cells are connected to each other in series to constitute one fuel cell stack 130, and the fuel cell stack 130 can generate a higher voltage than one unit cell.

Hereinafter, the fuel cell system 100 including the fuel cell stack 130 will be described.

2 is a schematic diagram of a fuel cell system according to an embodiment. In FIG. 2, arrows denoted by general solid lines denote fuel and air supply paths, and arrows denoted by thick solid lines denote control directions.

2, the fuel cell system 100 includes a fuel cell stack 130; An air supply unit 110 for supplying air to the fuel cell stack 130; A fuel supply unit 120 for supplying fuel to the fuel cell stack 130; A control unit 140 for controlling the air supply unit 110 and the fuel supply unit 120; . ≪ / RTI >

The fuel cell stack 130 can generate electrical energy using a redox reaction of hydrogen and oxygen. Specifically, the fuel cell stack 130 combines hydrogen and oxygen to produce water, and the chemical energy generated at this time can be used as electric energy. Since the fuel cell stacks 130 and 130 generate electrical energy by chemical reaction between oxygen and hydrogen supplied from the outside, they do not need to be charged and are environmentally friendly because there is no combustion reaction of the fuel.

To this end, the fuel cell stack 130 may have a structure in which a plurality of unit cells 130-1 of FIG. 1 are stacked. As described above, the unit cell 130-1 may include the air electrode 13 and the fuel electrode 12, which are the same as those described in FIG.

The air supply unit 110 can supply air containing oxygen to the fuel cell stack 130. To this end, the air supply unit 110 includes an air pump 111 which pressurizes and supplies air from the outside; A humidifier 112 for humidifying the air supplied from the air pump 111; And an air shutoff valve (113) provided in a path through which air humidified by the fuel cell stack (130) is supplied; . ≪ / RTI >

The air pump 111 is capable of providing air required for the fuel cell stack 130 by controlling the number of revolutions in accordance with the set point of the predetermined air supply amount. For this purpose, the air pump 111 can be controlled by feedforward control and / or feedback control by a control unit 140, which will be described later. The control logic for feedback and feedforward is a well known technique and will not be described in detail.

The humidifier 112 can humidify the air supplied from the air pump 111. [ The air humidified by the humidifier 112 can be supplied to the air electrode 13 of the fuel cell stack 130.

The air shutoff valve 113 may be provided on the air supply path formed between the humidifier 112 and the air electrode 13 of the fuel cell stack 130. Air is supplied to the fuel cell stack 130 only when the air shutoff valve 113 is opened. Therefore, the air shutoff valve 113 can be selectively opened and closed under the control of the control unit 140, which will be described later.

In addition, the air supply unit 110 may discharge surplus air, fuel, and water from the fuel cell stack 130. For this purpose, the air supply unit 110 may form an air discharge path, a fuel discharge path, and a water discharge path in relation to the fuel cell stack 130, and each path may be common or separate in some or all of the sections have.

The fuel supply unit 120 may supply the fuel including the hydrogen to the fuel cell stack 130. To this end, the fuel supply unit 120 includes a fuel processing unit 121 that processes externally supplied fuel to generate hydrogen; A fuel shutoff valve 123 provided in a path where the generated hydrogen is supplied to the fuel cell stack 130; A purge valve 124 provided in a path through which fuel is discharged from the fuel cell stack 130; A water trap 122 for storing and discharging water discharged from the fuel cell stack 130; And a drain valve 125 provided on a discharge path of water discharged from the water trap 122; . ≪ / RTI >

The fuel processor 121 may reform and purify the fuel to generate hydrogen and supply the generated hydrogen to the fuel electrode 12 of the fuel cell stack 130. [ As described above, the fuel processor 121 can reform the hydrocarbon-based fuel (reforming fuel) as a reformer to produce high-quality hydrogen.

The fuel cutoff valve 123 may be provided on the fuel supply path formed between the fuel processing unit 121 and the fuel electrode 12 of the fuel cell stack 130. [ Since the fuel is supplied to the fuel cell stack 130 only when the fuel cutoff valve 123 is opened, the fuel cutoff valve 123 can be selectively opened and closed under the control of the control unit 140, which will be described later.

The purge valve 124 may be provided on the path through which the fuel is discharged. Specifically, the purge valve 124 may be provided on a path for discharging surplus fuel of the fuel electrode 12 out of the fuel cell stack 130 to the outside. Since the fuel in the fuel cell stack 130 is discharged only when the purge valve 124 is opened, the purge valve can be selectively opened and closed under the control of the control unit 140, which will be described later.

The water trap 122 may temporarily store the water discharged from the fuel cell stack 130. Specifically, water is discharged together with the fuel at the fuel electrode 12 of the fuel cell stack 130. The water trap 122 temporarily stores the water therein and can supply the hydrogen to the fuel cell stack 130 again have.

The drain valve 125 may be provided on the water discharge path to discharge the water temporarily stored in the water trap 122 to the outside. The water in the fuel cell stack 130 is discharged only when the drain valve 125 is opened so that the drain valve 125 can be selectively opened and closed under the control of the controller 140 to be described later.

The unit cells 130-1 constituting the fuel cell stack 130 may have different fuel and air supply conditions. For example, the fuel supply unit 120 for supplying fuel to each unit cell 130-1, and the mechanical and electrical resistance of the air supply unit 110, the humidity of each unit cell 130-1, The output result of the generated voltage may be changed depending on conditions such as temperature.

In particular, the time required for reaching the target voltage to be output, that is, the delay time may be different for each unit cell 130-1. This will be described with reference to Fig.

FIG. 3 is a graph showing a time-dependent power generation voltage of different unit cells of the fuel cell stack according to an exemplary embodiment of the present invention. In FIG. 3, G1 is a power generation voltage graph of the first unit cell 130-1 constituting one fuel cell stack 130, G2 is a graph of power generation voltage of the second unit cell 130 -1). In the case of FIG. 3, it is assumed that the first unit cell 130-1 and the second unit cell 130-1 finally reach the target voltage V _G.

Referring to FIG. 3, although the first unit cell 130-1 and the second unit cell 130-1 constitute the same fuel cell stack 130, they may have different power generation voltage graphs. Particularly, it is confirmed that the output voltage of the first unit cell 130-1 is V1 while the output voltage of the second unit cell 130-1 is V2 after a predetermined reference time tr from the start of the supply of fuel and air have.

As a result, it can be estimated that the supply of fuel and air to the first unit cell 130-1 is not smooth more than the second unit cell 130-1, and the degree is determined based on the difference between V1 and V2 . At this time, the greater the difference between V1 and V2, the greater the difference in fuel and air supply to each unit cell 130-1 constituting one fuel cell stack 130. Therefore, the difference between V1 and V2 The fuel and air supply states of the fuel cell stack 130 can be determined.

Further, the fuel and air supply state of the fuel cell stack 130 may be determined based on the delay time of each unit cell 130-1. Here, the delay time may mean the time required for the power generation voltage of the unit cell 130-1 to reach the target voltage after the fuel and air are supplied.

Referring to FIG. 3, it can be seen that the delay time of the first unit cell 130-1 is t _d1 while the delay time of the second unit cell 130-1 is t _d2 . The greater the difference between the delay time thus determined and the predetermined reference delay time, the less smooth the supply of fuel and air. The delay time t _d1 of the first unit cell 130 - The larger the difference between the delay time t _d2 of the delay circuit 130-1 It may mean that the supply of fuel and air is abnormal.

That is, the generation voltage of each of the plurality of unit cells 130-1, which has been confirmed at least at a time point from when the supply of fuel and air is started until the generation voltage of the fuel cell stack 130 reaches the target voltage, May be used to determine fuel and air supply conditions for the stack 130.

As described above, in order to determine the state of the fuel and the air supply to the fuel cell stack 130, the control unit 140 determines that the generation voltage of the fuel cell stack 130 reaches the target voltage The supply state of the fuel and the air can be determined based on the generation voltage of each of the plurality of unit cells 130-1 identified at least at a point in time before the fuel cell and the unit cell 130-1.

In detail, the controller 140 controls the first power generation of each unit cell 130-1 after a predetermined first reference time from the start of supply of fuel and air to the fuel cell stack 130, The voltage can be checked. At this time, the first reference time may be predetermined to be equal to or shorter than a delay time required for the generated voltage to reach the target voltage.

Then, the control unit 140 can compare the difference between the first generation voltage and a predetermined reference generation voltage. In this case, the reference generation voltage may mean the minimum generation voltage of the unit cell 130-1 after the first reference time when the fuel and air supply conditions are normal. The reference generation voltage may be statistically determined by checking the first generation voltage of the plurality of unit cells 130-1, or may be determined mathematically according to a predetermined calculation process.

If the first generation voltage of the plurality of unit cells 130-1 constituting the fuel cell stack 130 is equal to or higher than the reference generation voltage, the controller 140 controls the fuel and air supply state Can be determined to be normal. If the first generation voltage of at least one of the plurality of unit cells 130-1 constituting the fuel cell stack 130 is less than the reference generation voltage, the control unit 140 controls the fuel and the fuel for the fuel cell stack 130, It can be determined that the air supply state is abnormal.

Unlike the method of determining the fuel and air supply states by individually comparing one first generation voltage with the reference generation voltage, the controller 140 controls the plurality of unit cells 130- 1) The fuel and air supply state may be determined based on the first generation voltage pattern obtained by checking each first generation voltage.

Specifically, the control unit 140 can obtain the first generation voltage pattern by plotting the first generation voltage of each of the plurality of unit cells 130-1 on the graph. Then, the controller 140 can determine the supply state of the fuel and the air to the fuel cell stack 130 by checking whether the first generation voltage pattern is less than the reference generation voltage.

If the first generation voltage of at least one of the plurality of unit cells 130-1 is below the reference generation voltage, the control unit 140 for determining the fuel and air supply states for the fuel cell stack 130 as abnormal . However, the control unit 140 may determine the fuel and air supply states according to the number of the unit cells 130-1 having the first power generation voltage less than the reference power generation voltage among the plurality of unit cells 130-1. For example, the control unit 140 obtains the ratio (%) of the unit cell 130-1 having the first generation voltage that is less than the reference generation voltage with respect to the total number of the unit cells 130-1, Fuel and air supply conditions can be determined. Alternatively, the control unit 140 may determine the fuel and air supply states by obtaining an average of the first generation voltages of the plurality of unit cells 130-1 and comparing the obtained average value with the reference generation voltage.

As described above, the control unit 140 can be variously implemented in the technical idea of determining the fuel and air supply state based on the first generation voltage of each of the plurality of unit cells 130-1.

In addition, the control unit 140 according to another embodiment can confirm the delay time until the power generation voltage of the fuel cell stack 130 reaches a predetermined reference power generation voltage after the fuel and air are supplied. Then, the control unit 140 can compare the confirmed delay time with a predetermined reference delay time.

In this case, the reference delay time may be a time required for the generated voltage of the unit cell 130-1 to reach the target voltage when the fuel and air supply conditions are normal. The reference delay time may be statistically determined by checking the delay time of the population of a plurality of unit cells 130-1 or mathematically determined according to a predetermined calculation process.

Alternatively, the control unit 140 may compare the delay times of the unit cells 130-1 to determine the fuel and air supply states. For example, if the delay time difference between the unit cells 130-1 is greater than or equal to the threshold value, it can be determined that the fuel and air supply conditions are abnormal.

The case where the fuel cell system 100 includes one fuel cell stack 130 has been described as a premise. Alternatively, it may be possible to include a plurality of fuel cell stacks 130 in which the fuel cell system 100 is physically separated. At this time, the plurality of physically separated fuel cell stacks 130 may be electrically connected in series.

In this case, the smaller the difference in the output voltages of the fuel cell stacks 130, the more the fuel cell system 100 operates. Therefore, the controller 140 controls the first The fuel and air supply conditions can be determined by comparing the output voltage pattern.

For example, when the fuel cell system 100 includes the first fuel cell stack 130 and the second fuel cell stack 130 connected in series, the controller 140 controls the first fuel cell stack 130, And the second output voltage pattern of the second fuel cell stack 130, respectively. The control unit 140 may then compare these patterns to determine the fuel and air supply status for the entire fuel cell stack 130.

Specifically, when the difference between the respective first output voltage patterns exceeds a predetermined reference difference, the control unit 140 can determine the state of supply of fuel and air abnormally. Here, the reference difference may mean the maximum value of the output voltage difference between the unit cells 130-1 constituting each of the plurality of fuel cell stacks 130 connected in series when the fuel and air supply states are normal.

If the difference between the first output voltage patterns of the first fuel cell stack 130 and the second fuel cell stack 130 exceeds the reference difference, And the air supply state can be determined abnormally.

The control unit 140 controls each of the individual unit cells 130 constituting the respective fuel cell stacks 130 in such a manner that the first output voltage patterns of the first fuel cell stack 130 and the second fuel cell stack 130 are compared. 130-1 may be compared with each other or the average of the first output voltage patterns may be compared. Also, the control unit 140 may compare an area below the reference output voltage among the first output voltage patterns.

As described above, the control unit 140 can be variously implemented in a technical concept of comparing differences of at least two first generation voltage patterns among the plurality of fuel cell stacks 130. [

In addition, the controller 140 acquires the second generation voltage of each of the plurality of unit cells 130-1 after the second reference time from the time point of the fuel and air supplied to the fuel cell stack 130, 2 It is also possible to determine the state of supply of fuel and air with reference to the generated voltage.

Since the change in the voltage output according to the supply of the fuel and the air corresponds to the change in the voltage output according to the cutoff of the fuel and the air, the controller 140 can refer to the second generation voltage have.

In particular, when the fuel and air supply conditions are determined to be abnormal, the control unit 140 determines the fuel and air supply conditions based on the second generation voltage, and refers to the second generation voltage based on the first generation voltage, The air supply state can be determined.

For this, the control unit 140 may store the second power generation voltage in advance before the supply of the fuel and the air is started again after the fuel and air supplied to the fuel cell stack 130 are cut off. In particular, the controller 140 may store the second generation voltage only when the fuel and air supply conditions are determined to be abnormal based on the second generation voltage.

If the supply state of the fuel and the air is determined to be abnormal according to the above-described method, the control unit 140 may perform an operation for improving the supply state of fuel and air. The control unit 140 can check whether the air shutoff valve 113, the purge valve 124, and the drain valve 125 are normally opened or closed. Here, the fact that the valve is normally opened or closed means that the path where the valve is provided is closed when the valve is opened, and the path where the valve is provided is closed when the valve is closed.

In order to check whether the air shutoff valve 113, the purge valve 124 and the drain valve 125 are normally opened or closed, the control unit 140 may adopt at least one of the known valve inspection methods.

If the state of at least one valve is confirmed to be abnormal as a result of checking the valve, it is necessary that repair or replacement of the valve is performed in order for the fuel cell system 100 to operate normally.

On the other hand, if all of the valves are found to be normal, the controller 140 can supply fuel and air to the fuel cell stack 130 in order to improve the fuel and air supply.

Specifically, the control unit 140 may oscillate the air to the fuel cell stack 130 to improve the air supply state. To this end, the control unit 140 may periodically open / close the air shutoff valve 113 provided on the air supply path. As a result, the air supply state to the fuel cell stack 130 can be improved.

In addition, the control unit 140 may supply the fuel to the fuel cell stack 130 to improve the fuel supply state. To this end, the control unit 140 may periodically open and close the purge valve 124 and the drain valve 125 provided in the fuel discharge path and the water discharge path, respectively. As a result, the fuel supply state to the fuel cell stack 130 can be improved.

If the state of the fuel and the air is determined to be abnormal based on the second output voltage as described above, the control unit 140 closes the air shutoff valve 113, and after the air is oscillated and supplied, . In addition, the control unit 140 may discharge the entire amount of the fuel after the purge valve 124 and the drain valve 125 are closed.

As a result, the inside of the fuel cell stack 130 is reset, and when the fuel and air are supplied again, the control unit 140 can re-check the supply state of fuel and air.

4 is a flow chart of a method of controlling a fuel cell system according to an embodiment, and specifically shows a method for determining the state of supply of fuel and air.

First, the fuel cell system 100 can confirm that the fuel cell has started to be generated. (800) Here, the start of the generation means that the fuel and air are being supplied to the fuel cell stack 130 have. If power generation is not started, the fuel cell system 100 can repeatedly confirm this.

On the other hand, if the power generation has started, the fuel cell system 100 can acquire the power generation voltage V1 of the fuel cell stack 130 after a predetermined reference time tr from the power generation start point. (810) Here, the predetermined reference time tr May be predetermined to be less than or equal to the delay time required for the generated voltage to reach the target voltage. The generated voltage V1 of the fuel cell stack 130 may indicate the generated voltages of the individual unit cells 130-1 constituting the fuel cell stack 130 or may include a mean value, a maximum value, a minimum value, etc. .

Finally, the fuel cell system 100 compares the obtained V1 with the reference generation voltage Vr to determine the supply state of the fuel and the air. (820) At this time, the reference generation voltage Vr becomes It can mean the minimum generation voltage of the unit cell 130-1 after the reference time in normal case. The reference generation voltage may be statistically determined by checking the first generation voltage of the plurality of unit cells 130-1, or may be determined mathematically according to a predetermined calculation process.

Through such a method, the fuel cell system 100 can judge the supply state of the fuel and the air, and perform a corresponding operation when the supply state of the fuel and the air is abnormal.

5 is a flowchart of a fuel cell system control method according to another embodiment, and specifically shows a method for improving the supply state of fuel and air

First, the fuel cell system 100 can confirm whether the supply state of the fuel and the air is abnormal. (900) A method of confirming the supply state of fuel and air is as described in FIG. If the fuel and air supply conditions are normal, the procedure is terminated.

The fuel cell system 100 can confirm whether the air shutoff valve 113, the purge valve 124 and the drain valve 125 are normally opened or closed. (910) Here, The fact that the valve is normally opened or closed means that the path where the valve is provided is opened when the valve is opened, and the path where the valve is provided is closed when the valve is closed.

If the valve is not normally opened or closed, the procedure is terminated. In this case, it is necessary to repair or replace the valve that is not normally opened or closed.

On the other hand, if the valve is normally opened and closed, the fuel cell system 100 can periodically open and close the air shutoff valve 113, the purge valve 124, and the drain valve 125. (920) Fuel and air are supplied to the stack 130 in an oscillation manner, and finally the state of supply of fuel and air can be improved.

100: Fuel cell system
110: air supply part
113: Air shutoff valve
120: fuel supply unit
124: purge valve
125: drain valve
130: Fuel cell stack
130-1: Unit cell
140:

Claims (20)

A fuel cell stack in which a plurality of unit cells including an air electrode and a fuel electrode are stacked; And
After confirming the generation voltage of each of the plurality of unit cells at least one time point after the start of supply of the fuel and the air until the generation voltage of the fuel cell stack reaches the target voltage, A controller for determining a supply state of the fuel and the air; Lt; / RTI >
Wherein,
A fuel cell for determining a supply state of the fuel and the air by referring to a second generation voltage of each of the plurality of unit cells after a predetermined second reference time from a time point at which the fuel and air are supplied to the fuel cell stack, system. The method according to claim 1,
Wherein the control unit controls the fuel and the air based on a difference between a first generation voltage of each of the plurality of unit cells and a predetermined reference generation voltage after a predetermined first reference time from the start of supply of fuel and air to the fuel cell stack, And determines the supply state of the air. 3. The method of claim 2,
Wherein,
The first generation voltage of each of the plurality of unit cells is checked for each of the plurality of fuel cell stacks and the first generation voltage pattern of each of the plurality of fuel cell stacks is compared And determines the supply state of the fuel and the air. The method of claim 3,
Wherein,
Wherein the supply state of the fuel and the air is determined to be abnormal if the difference between the at least two first generation voltage patterns of the plurality of fuel cell stacks exceeds a predetermined reference difference. delete The method according to claim 1,
Wherein,
Storing the second generation voltage before starting supply of the fuel and the air after interrupting the fuel and the air supplied to the fuel cell stack, and when the supply of the fuel and the air to the fuel cell stack is started, And the second generated voltage is referred to. The method according to claim 1,
Wherein,
Wherein the supply state of the air is determined based on a delay time after the start of supply of the fuel and the air until the generation voltage of the fuel cell stack reaches a predetermined reference generation voltage. The method according to claim 1,
A fuel supply unit including a purge valve provided in a first path through which the fuel is discharged from the fuel cell stack and a drain valve provided in a second path through which water is discharged from the fuel cell stack; And
An air supply unit including an air shutoff valve provided in a third path through which the air is supplied to the fuel cell stack; Further comprising:
Wherein,
And the state of the purge valve, the drain valve, and the air shutoff valve is checked if the supply state of the fuel and the air is determined to be abnormal. 9. The method of claim 8,
Wherein,
And a fuel cell stack for periodically opening and closing at least one of the purge valve and the drain valve so that the fuel is normally supplied to the fuel cell stack when the state of the purge valve, the drain valve, system. 9. The method of claim 8,
Wherein,
And the air shutoff valve is periodically opened and closed so that the air is normally supplied to the fuel cell stack when the purge valve, the drain valve, and the air shutoff valve are confirmed as normal. Supplying fuel and air to a fuel cell stack in which a plurality of unit cells are stacked;
Confirming a generation voltage of each of the plurality of unit cells at least at a time point after the start of supply of the fuel and the air until a generation voltage of the fuel cell stack reaches a target voltage; And
Determining a supply state of the fuel and the air based on the identified generation voltage; Lt; / RTI >
Wherein the step of determining the supply state of the fuel and the air comprises:
A fuel cell for determining a supply state of the fuel and the air by referring to a second generation voltage of each of the plurality of unit cells after a predetermined second reference time from a time point at which the fuel and air are supplied to the fuel cell stack, Method of controlling the system. 12. The method of claim 11,
Wherein the step of verifying the generation voltage of each of the plurality of unit cells comprises:
Checking a first generation voltage of each of the plurality of unit cells after a predetermined first reference time from when fuel and air are supplied to the fuel cell stack,
Wherein the step of determining the supply state of the fuel and the air comprises:
Wherein the supply state of the fuel and the air is determined based on a difference between the first generation voltage and a predetermined reference generation voltage. 13. The method of claim 12,
Wherein the step of verifying the generation voltage of each of the plurality of unit cells comprises:
The first power generation voltage of each of the plurality of unit cells is checked for each of the plurality of fuel cell stacks if the fuel cell stack is a plurality,
Wherein the step of determining the supply state of the fuel and the air comprises:
And comparing the first generation voltage pattern of each of the plurality of fuel cell stacks to determine a supply state of the fuel and the air. 14. The method of claim 13,
Wherein the step of determining the supply state of the fuel and the air comprises:
Wherein the supply state of the fuel and the air is determined to be abnormal if a difference between at least two of the plurality of fuel cell stacks exceeds a predetermined reference difference. delete 12. The method of claim 11,
Storing the second generation voltage before starting supply of the fuel and the air after interrupting the fuel and the air supplied to the fuel cell stack; Further comprising the steps of: 12. The method of claim 11,
Wherein the step of determining the supply state of the fuel and the air comprises:
Wherein the supply state of the air is determined based on a delay time after the start of supply of the fuel and the air until the generation voltage of the fuel cell stack reaches a predetermined reference generation voltage. 12. The method of claim 11,
A first path through which the fuel is discharged from the fuel cell stack, a second path through which water is discharged from the fuel cell stack when the supply state of the fuel and the air is determined to be abnormal, Confirming whether or not the supplied third path is normally connected and disconnected; Further comprising the steps of: 18. The method of claim 17,
At least one of the first path and the second path is periodically connected and blocked so that the fuel is normally supplied to the fuel cell stack when the first path, the second path, and the third path are confirmed to be normally connected and disconnected, ; Further comprising the steps of: 18. The method of claim 17,
Periodically connecting and disconnecting the third path so that the air is normally supplied to the fuel cell stack if it is confirmed that the first path, the second path, and the third path are normally opened and closed; Further comprising the steps of:

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