Fuel cell module

Abstract

To provide a configuration that can determine whether a cross leak abnormality has occurred in a fuel cell unit regardless of the operating status of a fuel cell module.SOLUTION: A fuel cell module includes a fuel cell including multiple fuel cells and a control unit that controls the state of the fuel cell on the basis of commands from a host system. When a command to shut down the fuel cell is received, the control unit initiates a shutdown sequence to shut down the fuel cell and determines whether a cross leak abnormality has occurred in the fuel cell during the shutdown sequence.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fuel cell module, and more particularly to a fuel cell module used in a generator.

Background Art

[0002] A fuel cell module generates electric power by electrochemically reacting hydrogen and oxygen through an electrolyte. For example, in response to a request from an external load, by adjusting the amount of hydrogen and / or air supplied to the fuel cell, the electric power required by the external load is generated.

[0003] A fuel cell is composed of a cell stack in which a plurality of fuel cell cells are stacked. Each fuel cell cell is composed of a membrane / electrode assembly in which an electrolyte membrane is sandwiched between a pair of electrodes, and a pair of separators that sandwich it from both sides. Then, power is generated by the redox reaction between the air (i.e., air) supplied through the cathode-side separator and the hydrogen gas supplied through the anode-side separator. In the following description, the electrolyte membrane in each cell may be referred to as the "cell membrane". Also, a fuel cell in which a plurality of fuel cell cells are stacked may be referred to as an "FC (Fuel Cell) stack".

[0004] In such an FC stack, when a failure such as "hole opening" where a hole forms in the cell membrane or "membrane tearing" where the cell membrane tears occurs, a cross-leakage abnormality occurs in which the cross-leakage between the anode and the cathode increases. Here, cross-leakage is a phenomenon in which gas components penetrate bidirectionally through the cell membrane between the anode and the cathode during non-power generation. And when a cross-leakage abnormality occurs, the cell voltage may decrease. For this reason, a method for detecting the presence or absence of the occurrence of a cross-leakage abnormality has been proposed. As an example, a method has been proposed in which, based on the cell voltage of each of a plurality of fuel cell cells, when the decrease width of the cell voltage at a predetermined time is equal to or greater than a threshold value, it is determined that a cross-leakage abnormality has occurred (for example, Patent Document 1).

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, by measuring the cell voltage (or other parameters), cross-leakage abnormalities can be detected. However, this measurement cannot be performed when the FC stack is stopped. Also, it is difficult to perform this measurement during the period when the FC stack is generating power. Therefore, as one embodiment, a procedure for measuring the cell voltage (or other parameters) during the period when the FC stack is in the idle state and determining the presence or absence of cross-leakage abnormalities can be considered.

[0007] However, after the FC stack is started, the FC stack may stop without passing through the idle state. For example, when a fuel cell module is used as a generator, an operating situation is assumed in which the FC stack continuously generates power and supplies it to a load, and no idle state occurs. And in such a case, there is a possibility that the presence or absence of cross-leakage abnormalities cannot be determined.

[0008] An object related to one aspect of the present invention is to provide a configuration capable of determining the presence or absence of cross-leakage abnormalities in fuel cell cells regardless of the operating situation of the fuel cell module.

Means for Solving the Problems

[0009] A fuel cell module according to one aspect of the present invention includes a fuel cell including a plurality of fuel cell cells, and a control unit configured to control the state of the fuel cell based on a command given from an upper system. When receiving the command instructing the stop of the fuel cell, the control unit starts a stop sequence for stopping the fuel cell and determines the presence or absence of a cross leak abnormality in the fuel cell cells during the stop sequence.

[0010] According to this configuration, regardless of the usage form of the fuel cell module, the presence or absence of a cross leak abnormality is determined at the time of its stop. Therefore, damage to the electrolyte membrane of the fuel cell cell can be detected at an early stage.

[0011] The fuel cell module having the above configuration may further include a pressure sensor configured to detect the pressure of the anode gas of the fuel cell. In this case, in the stop sequence, the control unit seals the cathode of the fuel cell, reduces the output voltage of the fuel cell to a predetermined threshold value or less, increases the pressure of the anode gas to a specified value, and determines the presence or absence of a cross leak abnormality based on the rate of decrease in the pressure of the anode gas detected by the pressure sensor. According to this configuration, by monitoring the pressure of the anode gas in the stop sequence of the fuel cell module, damage to the electrolyte membrane of the fuel cell cell can be detected.

[0012] Further, the fuel cell module having the above configuration may further include a DC / DC converter configured to boost or buck the output of the fuel cell and supply power to a load. In this case, in the stop sequence, the control unit operates the load to supply power from the DC / DC converter to the load, thereby reducing the output voltage of the fuel cell to a value below the threshold. According to this configuration, in the stop sequence, the charge in the fuel cell can be efficiently extracted to consume oxygen, so that the time required for the procedure for determining the presence or absence of a cross leak abnormality can be shortened.

Advantages of the Invention

[0013] According to the above aspect, it is possible to determine the presence or absence of a cross leak abnormality in the fuel cell cells regardless of the operating conditions of the fuel cell module.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0015] FIG. 1 shows an example of a fuel cell module according to an embodiment of the present invention. The fuel cell module 1 according to the embodiment of the present invention includes an FC stack (fuel cell) 11. The FC stack 11 is configured by stacking a plurality of fuel cells. Further, by connecting a plurality of fuel cells in series, the FC stack 11 can output a desired voltage. Furthermore, the fuel cell module 1 includes a voltage sensor 12 that detects the output voltage of the FC stack 11. Note that the voltage sensor 12 may detect the voltage of each fuel cell constituting the FC stack 11.

[0016] A fuel cell includes an electrolyte membrane between an anode and a cathode. Then, hydrogen is supplied to the anode side, and air containing oxygen is supplied to the cathode side. Thereby, the FC stack 11 generates electricity by an electrochemical reaction between hydrogen and oxygen, and water (hereinafter sometimes referred to as “generated water”) is generated in the process of the reaction. Therefore, a hydrogen supply channel 21 for supplying hydrogen to the anode and an air supply channel 41 for supplying air to the cathode are connected to the FC stack 11. Note that hydrogen is an example of a fuel gas, and air is an example of an oxidizing gas.

[0017] The hydrogen supply passage 21 is a passage for supplying the hydrogen stored in the hydrogen tank 22 to the anode of the FC stack 11. And, a main valve 23, a regulator 24, and an injector 25 are provided in the hydrogen supply passage 21. The main valve 23 permits or shuts off the supply of hydrogen from the hydrogen tank 22 to the FC stack 11. The regulator 24 adjusts the pressure of the hydrogen gas supplied from the hydrogen tank 22 via the main valve 23. The injector 25 incorporates an injector valve (not shown), and by controlling this injector valve, supplies the necessary amount of hydrogen to the FC stack 11. Note that the main valve 23, the regulator 24, and the injector 25 are controlled by a control unit 71 described later.

[0018] Pressure sensors 26 to 27 are provided in the hydrogen supply passage 21. The pressure sensor 26 detects the pressure of the hydrogen gas in the hydrogen supply passage 21 on the upstream side of the injector 25. The pressure sensor 27 detects the pressure of the hydrogen gas in the hydrogen supply passage 21 on the downstream side of the injector 25. Note that the values detected by the pressure sensors 26 to 27 are notified to the control unit 71 described later.

[0019] The air supply passage 41 is a passage for supplying the air in the atmosphere to the cathode of the FC stack 11. And, an air compressor 42 and an air shut-off valve 43 are provided in the air supply passage 41. The air compressor 42 compresses the air sucked from the atmosphere and supplies it to the FC stack 11 via the air supply passage 41. The air shut-off valve 43 can shut off the supply of air to the FC stack 11. Note that the air compressor 42 and the air shut-off valve 43 are controlled by a control unit 71 described later.

[0020] The FC stack 11 is connected to a circulation flow path 51 and an exhaust flow path 61. The circulation flow path 51 is provided to return the hydrogen contained in the anode off-gas (the gas exhausted from the anode compartment) discharged from the FC stack 11 to the hydrogen supply flow path 21. Further, the exhaust flow path 61 is provided to discharge the cathode off-gas (the gas exhausted from the cathode compartment) exhausted from the FC stack 11 to the outside.

[0021] The circulation flow path 51 is provided with a gas-liquid separator 52 and a hydrogen circulation pump 53. The anode off-gas exhausted from the FC stack 11 contains hydrogen remaining without reacting with oxygen and water generated by the electrochemical reaction. Then, the gas-liquid separator 52 separates the anode off-gas exhausted from the FC stack 11 into gas and liquid. At this time, most of the hydrogen in the anode off-gas is led from the gas-liquid separator 52 to the hydrogen circulation pump 53. The hydrogen circulation pump 53 causes the hydrogen gas separated by the gas-liquid separator 52 to flow into the hydrogen supply flow path 21. Note that the hydrogen circulation pump 53 is controlled by a control unit 71 described later.

[0022] The remaining anode off-gas is led from the gas-liquid separator 52 to the diluter 63 via the exhaust drain valve 54. The anode off-gas led to the diluter 63 contains water and hydrogen that could not be completely extracted by the gas-liquid separator 52.

[0023] The exhaust flow path 61 is provided with an air pressure regulating valve 62. The air pressure regulating valve 62 adjusts the pressure of the cathode off-gas exhausted from the FC stack 11. Here, the air pressure regulating valve 62 is controlled by a control unit 71 described later. Then, the cathode off-gas whose pressure has been adjusted by the air pressure regulating valve 62 is led to the diluter 63.

[0024] The diluter 63 mixes the anode off-gas and the cathode off-gas. Thereby, the hydrogen contained in the anode off-gas is diluted using the cathode off-gas (i.e., air). That is, the diluter 63 reduces the concentration of hydrogen exhausted from the fuel cell module 1.

[0025] The control unit 71 includes a processor and memory, and controls the operation of the fuel cell module 1. Here, the control unit 71 controls the operation of the fuel cell module 1 in accordance with a startup command and a power generation command given from a higher-level system. For example, when the fuel cell module 1 is mounted on a generator, the higher-level system corresponds to the control system of the generator. In this case, the startup command is generated in response to the key-on of the main switch of the generator. Also, the power generation command is generated in response to an operation for supplying power from the generator to a load.

[0026] The control unit 71 may also control the operation of the fuel cell module 1 based on the pressures detected by the pressure sensors 26-27 and the FC voltage / cell voltage detected by the voltage sensor 12. Alternatively, the control unit 71 may control the operation of the fuel cell module 1 in response to a request from a load of the fuel cell module 1. In this case, the control unit 71 controls the main valve 23, the injector 25, the air compressor 42, the air shutoff valve 43, the hydrogen circulation pump 53, the exhaust drain valve 54, and the air pressure regulating valve 62 based on these parameters (sensor values, command values). The load is an electrical device that consumes the power generated by the fuel cell module 1, and includes, for example, electrical appliances to which power is supplied via a power conditioner connected to the generator when the fuel cell module 1 is mounted on a generator.

[0027] The DC / DC converter 81 boosts or lowers the output voltage of the FC stack 11 to supply power to a load. The DC / DC converter 81 may also charge a power storage device (not shown). Furthermore, the auxiliary equipment of the fuel cell module 1 (air compressor 42, hydrogen circulation pump 53, water pump (not shown), etc.) may operate with power provided via the DC / DC converter 81.

[0028] Figure 2 shows an example of the state transition of the fuel cell module 1. In the example shown in FIG. 2A, when the control unit 71 receives the start command ON from the upper system, it starts the FC stack 11. As a result, the FC stack 11 transitions from the stopped state to the idle state. Here, in the idle state, although the FC stack 11 is in a non-power generation state, the supply of air to the FC stack 11 is ensured so that each fuel cell maintains a predetermined voltage. At this time, the pressure of the hydrogen gas supplied to the anode of the FC stack 11 is controlled within a predetermined range. In the following description, the pressure of the hydrogen gas supplied to the anode of the FC stack 11 may be referred to as the "anode gas pressure". Further, the start command ON is generated, for example, by turning on the key of the main switch of the generator when the fuel cell module 1 is mounted on the generator and used.

[0029] Figure 3 shows an example of the operation of the fuel cell module 1 in the idle state. In the idle state, as described above, the anode gas pressure is controlled within a predetermined range. That is, when the supply of hydrogen to the FC stack 11 is stopped, the anode gas pressure gradually decreases as it penetrates to the cathode side through the electrolyte membrane, as shown by the broken line in FIG. 3. Then, when the anode gas pressure drops to the lower limit level of the predetermined range, the control unit 71 controls the injector 25 to increase the anode gas pressure. After that, again, the anode gas pressure gradually decreases. Thereafter, this operation is repeated, and the anode gas pressure is maintained within a predetermined range.

[0030] In this way, in the idle state, hydrogen is intermittently supplied to the anode of the FC stack 11 so that the anode gas pressure is maintained within a predetermined range. Therefore, in the following description, the idle state may be referred to as "intermittent operation".

[0031] In the idle state, when the control unit 71 receives a power generation command ON from the upper system, it causes the FC stack 11 to generate power. Specifically, hydrogen and air are supplied to the anode and cathode of the FC stack 11, respectively. As a result, the operation mode of the FC stack 11 shifts from the idle state to the power generation state. Note that the power generation command ON is generated, for example, when power is supplied from the generator to the load.

[0032] When the control unit 71 receives a power generation command OFF from the upper system, it stops the power generation of the FC stack 11. As a result, the operation mode of the FC stack 11 returns from the power generation state to the idle state. Note that the power generation command OFF is generated, for example, when the supply of power from the generator to the load is terminated.

[0033] Furthermore, when the control unit 71 receives a start command OFF from the upper system, it stops the FC stack 11. Here, the start command OFF is generated, for example, by turning off the key of the main switch of the generator on which the fuel cell module 1 is mounted. Then, a stop sequence is executed in response to the start command OFF. In the stop sequence, the control unit 71 may first charge an auxiliary power source (not shown) such as a capacitor. After that, the control unit 71 executes a stop process. That is, the control unit 71 stops the supply of hydrogen from the hydrogen tank 22 to the FC stack 11 by controlling the main valve 23 and the injector 25. Also, the control unit 71 stops the supply of air to the FC stack 11 by controlling the air compressor 42 and the air shut-off valve 43.

[0034] In the fuel cell module 1 configured as described above, the control unit 71 determines whether there is a cross-leakage abnormality in the fuel cell. Specifically, the control unit 71 determines whether there is a cross-leakage abnormality when the fuel cell module 1 is in the idle state (i.e., during intermittent operation).

[0035] When the electrolyte membrane of each fuel cell is not damaged and there is no cross-leakage abnormality, as shown by the dashed line in FIG. 3, the anode gas pressure gradually decreases. On the other hand, when damage such as "hole opening" where a hole appears in the cell membrane or "membrane tearing" where the cell membrane tears occurs, and a cross-leakage abnormality occurs in which the cross-leakage between the cathode and the anode increases, the anode gas penetrates to the cathode side in a short time. As a result, as shown by the solid line in FIG. 3, the anode gas pressure rapidly decreases.

[0036] As described above, when a cross-leakage abnormality occurs, the anode gas pressure rapidly decreases. However, when the FC stack 11 is generating power, since the anode gas (i.e., hydrogen) is consumed in the FC stack 11, it is not possible to determine the presence or absence of a cross-leakage abnormality even by monitoring the anode gas pressure. Therefore, the control unit 71 determines the presence or absence of a cross-leakage abnormality based on the anode gas pressure in the idle state (i.e., during intermittent operation).

[0037] However, the fuel cell module 1 does not always operate as shown in FIG. 2A. For example, in the case shown in FIG. 2B, a power generation command ON is generated immediately after the start command ON. In this case, the FC stack 11 starts generating power immediately after the fuel cell module 1 is started. Also, a start command OFF is generated immediately after the power generation command OFF. In this case, the fuel cell module 1 stops immediately after the FC stack 11 stops generating power. That is, in these cases, the operation sequence is such that there is substantially no idle state. And in this case, the opportunity to determine the presence or absence of a cross-leakage abnormality is lost or reduced. Therefore, the fuel cell module 1 according to the embodiment of the present invention has a function capable of determining the presence or absence of a cross-leakage abnormality regardless of the usage form.

[0038] FIG. 4 shows an example of a method for determining a cross leak abnormality by the fuel cell module 1 according to an embodiment of the present invention. In this embodiment, it is assumed that a start command OFF is generated at time T0 and given to the control unit 71. Note that the stack voltage is the output voltage of the FC stack 11 and is detected by the voltage sensor 12. Further, the anode gas pressure represents the hydrogen input pressure to the anode of the FC stack 11 and is detected by the pressure sensor 27.

[0039] When the start command OFF is given, the control unit 71 consumes oxygen in the FC stack 11. Specifically, the control unit 71 controls the air shut-off valve 43 and the air pressure regulating valve 62 to stop the supply of air to the cathode of the FC stack 11. Thereby, the cathode is sealed. Further, the control unit 71 controls the injector 25 to stop the supply of hydrogen to the anode of the FC stack 11. However, at this point, hydrogen and oxygen remain in the FC stack 11, and power generation by the remaining gas is possible. Subsequently, the control unit 71 operates the DC / DC converter 81 and the auxiliary machines provided in the fuel cell module 1. The DC / DC converter 81 supplies the power generated by the remaining hydrogen and oxygen to the auxiliary machines. Note that the auxiliary machines provided in the fuel cell module 1 correspond to, for example, the air compressor 42 shown in FIG. 1, the hydrogen circulation pump 53, or a water pump (not shown).

[0040] By operating the DC / DC converter 81 and auxiliary equipment, the charge in the FC stack 11 is extracted, and the output voltage and anode gas pressure of the FC stack 11 gradually decrease. At this time, the control unit 71 monitors the output voltage of the FC stack 11 using the voltage sensor 12 and monitors the anode gas pressure using the pressure sensor 27. Then, when the output voltage of the FC stack 11 drops to a predetermined threshold level, the control unit 71 controls the injector 25 to supply hydrogen to the anode of the FC stack 11 to raise the anode gas pressure to a specified value. In the embodiment shown in FIG. 4, when the output voltage of the FC stack 11 drops to a predetermined threshold level at time T1, the control unit 71 raises the anode gas pressure to a specified value. Here, the threshold level corresponds to a state where, for example, the concentration of oxygen in the FC stack 11 decreases and each fuel cell cannot generate electricity sufficiently. Also, the specified value is not particularly limited, but may be, for example, the average anode gas pressure during power generation of the FC stack 11. After this, the control unit 71 stops supplying hydrogen to the anode of the FC stack 11.

[0041] Note that it is preferable for the control unit 71 to stop the DC / DC converter 81 and auxiliary equipment when the output voltage of the FC stack 11 drops to a predetermined threshold level. Also, the control unit 71 may monitor the anode gas pressure instead of the output voltage of the FC stack 11 and raise the anode gas pressure to a specified value when the anode gas pressure drops to a predetermined threshold level.

[0042] In the FC stack 11, cross leakage occurs between the anode and the cathode. At this time, the hydrogen supplied to the anode penetrates through the electrolyte membrane and permeates to the cathode side. For this reason, the anode gas pressure decreases. Here, if the electrolyte membrane is in a normal state, the anode gas pressure gradually decreases. On the other hand, in the case where a cross leakage abnormality due to damage such as "hole opening" or "membrane tearing" occurs, the anode gas pressure should rapidly decrease. Therefore, after pressurizing the anode gas, the control unit 71 detects the rate of decrease of the anode gas pressure.

[0043] In the embodiment shown in FIG. 4, the anode gas pressure is measured at time T2 and time T3, respectively. Then, based on the difference ΔP between the pressure P2 detected at time T2 and the pressure P3 detected at time T3, the control unit 71 determines whether or not there is a cross leak abnormality. Specifically, if the difference ΔP is smaller than a predetermined threshold value, it is determined that the rate of decrease in the anode gas pressure is slow and no cross leak abnormality has occurred. On the other hand, when the difference ΔP is larger than the threshold value, it is determined that the rate of decrease in the anode gas pressure is fast and a cross leak abnormality has occurred. Note that the interval between time T2 and time T3 is about several seconds and is determined based on the structure of the fuel cell stack or the like, or by prior simulation or the like. Also, this measurement may be performed immediately after the anode gas is pressurized, or may be performed after several seconds have elapsed since the anode gas was pressurized.

[0044] As described above, according to the embodiment of the present invention, when a command to stop the fuel cell module 1 is generated, the control unit 71 starts a stop sequence for stopping the FC stack 11 and determines whether or not there is a cross leak abnormality during the stop sequence. Therefore, even when the fuel cell module 1 stops without shifting to the idle state (or intermittent operation), it is possible to determine whether or not there is a cross leak abnormality. For example, even in a case where a start command OFF is generated immediately after the power generation command OFF, it is possible to determine whether or not there is a cross leak abnormality. Thus, it is possible to detect early damage such as "hole opening" where a hole is formed in the cell membrane or "membrane rupture" where the cell membrane is torn.

[0045] FIG. 5 is a flowchart showing an example of a cross leak abnormality determination method according to an embodiment of the present invention. The processing of this flowchart is executed when the fuel cell module 1 is operating. Then, in S1, the control unit 71 waits for a start command OFF. In this embodiment, as described above, the start command OFF is generated by turning off the key of the generator on which the fuel cell module 1 is mounted and instructs the stop of the fuel cell module 1. When the start command OFF is received, the control unit 71 executes the processing after S2.

[0046] In S2, the control unit 71 seals the cathode of the FC stack 11. At this time, at least the air shut-off valve 43 and the air pressure regulating valve 62 are closed. In S3, the control unit 71 stops the supply of hydrogen to the FC stack 11. At this time, at least the injector 25 is controlled.

[0047] In S4, the control unit 71 operates the DC / DC converter 81 and the auxiliary machine of the fuel cell module 1. Then, the DC / DC converter 81 supplies the power generated by the FC stack 11 to the auxiliary machine. As a result, charge is drawn from the FC stack 11, and its output voltage decreases. Also, since hydrogen and oxygen in the FC stack 11 are consumed, the anode gas pressure also decreases.

[0048] In S5, the control unit 71 monitors the output voltage of the FC stack 11. When the output voltage of the FC stack 11 drops to a predetermined threshold level, the control unit 71 executes S6 - S8.

[0049] In S6, the control unit 71 raises the anode gas pressure to a specified level. At this time, at least the injector 25 is controlled. Subsequently, in S7 - S8, the control unit 71 measures the rate of decrease of the anode gas pressure using the pressure sensor 27. Specifically, the control unit 71 acquires the output values of the pressure sensor 27 at two different times and calculates the difference therebetween. In the example shown in FIG. 4, the difference ΔP between the pressure P2 detected at time T2 and the pressure P3 detected at time T3 is calculated. This difference ΔP corresponds to the rate of decrease of the anode gas pressure.

[0050] If the rate of decrease in the anode gas pressure is slower than a predetermined threshold level (S8: No), the control unit 71 determines that no cross-leakage abnormality has occurred. That is, it is determined that the cell membranes of the respective fuel cells constituting the FC stack 11 are not damaged. On the other hand, if the rate of decrease in the anode gas pressure is faster than the threshold level (S8: Yes), the control unit 71 determines that a cross-leakage abnormality has occurred. That is, it is determined that the cell membranes of at least one of the fuel cells constituting the FC stack 11 are damaged. Note that this threshold level is determined based on the structure of the fuel cell or the like, or based on prior simulations or the like.

[0051] <Variation> In the above-described embodiment, in the procedure for determining the presence or absence of a cross-leakage abnormality, oxygen in the FC stack 11 is consumed by supplying power from the DC / DC converter 81 to the auxiliary equipment of the fuel cell module 1. However, the embodiment of the present invention is not limited to this configuration. For example, the control unit 71 may charge a power storage device (not shown) using the output of the DC / DC converter 81 during the procedure for determining the presence or absence of a cross-leakage abnormality.

[0052] Also, in the above-described embodiment, the control unit 71 that has received the start command OFF starts a stop sequence for stopping the fuel cell and determines the presence or absence of a cross-leakage abnormality during the stop sequence. However, the embodiment of the present invention is not limited to this configuration. For example, the control unit 71 that has received the start command OFF may start a stop sequence and perform intermittent operation for a predetermined time during the stop sequence. Then, the control unit 71 may determine the presence or absence of a cross-leakage abnormality during this intermittent operation.

[0053] Furthermore, in the above-described embodiments, the presence or absence of cross leak abnormality is determined based on the rate of decrease in the anode gas pressure. However, the embodiments of the present invention are not limited to this configuration. For example, when hydrogen is supplied to the anode in a non-power generation state, the output voltage of the FC stack 11 or the output voltage of each fuel cell cell decreases due to the progress of cross leak. Therefore, instead of monitoring the anode gas pressure, the control unit 71 may determine the presence or absence of cross leak abnormality based on the rate of decrease in the output voltage of the FC stack 11 or the output voltage of each fuel cell cell.

Explanation of Signs

[0054] 1 Fuel cell module 11 FC stack 12 Voltage sensor 21 Hydrogen supply flow path 22 Hydrogen tank 23 Main valve 24 Regulator 25 Injector 26, 27 Pressure sensor 41 Air supply flow path 42 Air compressor 43 Air shut-off valve 53 Hydrogen circulation pump 71 Control unit 81 DC / DC converter

Claims

1. A fuel cell including a plurality of fuel cells, and a control unit configured to control the state of the fuel cell based on a command given from an upper system, wherein when receiving the command for instructing stop of the fuel cell, the control unit starts a stop sequence for stopping the fuel cell and determines presence or absence of a cross leak abnormality in the fuel cells during the stop sequence. A fuel cell module characterized by the above.

2. The fuel cell module according to claim 1, further comprising a pressure sensor configured to detect pressure of anode gas supplied to the fuel cell, wherein in the stop sequence, the control unit seals a cathode of the fuel cell, lowers an output voltage of the fuel cell to a predetermined threshold value or less, raises the pressure of the anode gas to a specified value, and determines presence or absence of the cross leak abnormality based on a rate of decrease in the pressure of the anode gas detected by the pressure sensor. The fuel cell module according to claim 1, further comprising a pressure sensor configured to detect pressure of anode gas supplied to the fuel cell, wherein

3. The fuel cell module according to claim 2, further comprising a DC / DC converter configured to boost or buck an output of the fuel cell to supply power to a load, wherein in the stop sequence, the control unit operates the load to supply power from the DC / DC converter to the load, thereby lowering the output voltage of the fuel cell to the threshold value or less. The fuel cell module according to claim 2, further comprising a DC / DC converter configured to boost or buck an output of the fuel cell to supply power to a load, wherein

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