Fuel cell system

Abstract

This fuel cell system includes a plurality of power generation units and a control unit. The plurality of power generation units is electrically connected in series. The power generation units include a fuel cell. The fuel cell generates power using fuel gas and air. The fuel gas is supplied from a first supply system. Air is supplied from a second supply system. The control unit checks the state of at least one of the first supply system and the second supply system when the difference between the voltages in each of the plurality of power generation units exceeds a voltage threshold.

Description

fuel cell system CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2024-045282, filed on March 21, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a fuel cell system.

[0003] A fuel cell system in which a plurality of fuel cell stacks are connected in series is known (see Patent Document 1).

[0004] Patent No. 6475023

[0005] A fuel cell system according to a first aspect comprises: a plurality of power generation units electrically connected in series, each including a fuel cell that generates electricity using a fuel gas supplied from a first supply system and air supplied from a second supply system; and a control unit that checks the status of at least one of the first supply system and the second supply system when a difference in voltage between the plurality of power generation units exceeds a voltage threshold.

[0006] It is a configuration diagram showing the schematic configuration of a fuel cell system according to the present embodiment. It is a configuration diagram showing the schematic configuration of a power generation unit of Fig. 1. It is a flowchart for explaining a confirmation process executed by a control unit of Fig. 1.

[0007] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals.

[0008] As shown in FIG. 1 , a fuel cell system 10 according to an embodiment of the present disclosure includes a plurality of power generation units 11 and a control unit 12 .

[0009] The multiple power generation units 11 are electrically connected in series. In Fig. 1, two power generation units 11 are illustrated as the multiple power generation units 11, but the number is not limited to two. As shown in Fig. 2, the power generation unit 11 includes a fuel cell 13. The power generation unit 11 may further include a combustion unit 14, a reformer 15, a first supply system 16, a second supply system 17, a third supply system 18, a voltage sensor 19, and a temperature sensor 28.

[0010] The fuel cell 13 generates electricity through an electrochemical reaction using a fuel gas and air. The fuel gas may include, for example, hydrogen gas. Specifically, the fuel cell 13 performs an electrochemical reaction using oxygen gas in the air. The fuel cell 13 may include a fuel cell unit. The fuel cell 13 may include a plurality of fuel cell units. The plurality of fuel cell units may form a cell stack. The fuel cell unit may be a solid oxide fuel cell unit. In the fuel cell 13, not all of the fuel gas and oxygen gas in the air may undergo an electrochemical reaction, and unreacted fuel gas and oxygen gas may be discharged.

[0011] The combustion unit 14 may combust unreacted fuel gas in the fuel cell 13 using unreacted oxygen gas. The combustion unit 14 may heat the reformer 15 using heat generated by burning the unreacted fuel gas. The combustion unit 14 may heat the reformer 15 to provide energy for a steam reforming reaction in the reformer 15. The combustion unit 14 may be located in a direction opposite to the first direction from the reformer 15 to effectively heat the reformer 15. In the fuel cell system 10, the first direction is a direction that is assumed to be directed vertically upward when the fuel cell system 10 is installed. The combustion unit 14 may be, for example, a space in the first direction from the fuel cell 13. Unreacted fuel gas and unreacted oxygen gas injected from an outlet of the fuel cell 13 may be combusted in the space. Alternatively, the combustion unit 14 may be, for example, a burner located in the first direction from the fuel cell 13.

[0012] The reformer 15 may generate fuel gas by steam reforming raw fuel and water. The raw fuel may include light hydrocarbons such as methane. The reformer 15 may contain a reforming catalyst. The reforming catalyst may generate fuel gas from the raw fuel and water. Steam may be supplied to the reformer 15 as liquid reforming water and vaporized into steam in a vaporization unit provided in the reformer 15.

[0013] The first supply system 16 may directly or indirectly supply the fuel gas to the fuel cell 13. For example, the first supply system 16 may indirectly supply the fuel gas to the fuel cell 13 by supplying raw fuel to the reformer 15. In the following description, the fuel gas will be described as being indirectly supplied to the fuel cell 13 via the reformer 15.

[0014] The first supply system 16 may include a first supply path 20 and a first supply unit 21. The first supply path 20 may be a pipeline through which fuel gas and raw fuel gas flow. The first supply unit 21 may cause the fuel gas to flow through the first supply path 20. The first supply unit 21 may cause the fuel gas to flow, for example, by increasing the pressure of the fuel gas or raw fuel. The first supply unit 21 may be capable of adjusting the flow rate of the fuel gas according to the operating intensity. The operating intensity is a variable value that contributes to an increase in the flow rate by the first supply unit 21. The operating intensity is, for example, the rotation speed in a configuration in which the first supply unit 21 is a turbo pump. The first supply unit 21 may be, for example, a pump with a variable duty ratio.

[0015] The first supply system 16 may be provided with a first flow rate sensor 22. The first flow rate sensor 22 may detect the flow rate of the fluid flowing in the first supply path 20. The first flow rate sensor 22 may provide the detected flow rate as information to the control unit 12.

[0016] The second supply system 17 may supply air to the fuel cell 13. The second supply system 17 may include a second supply path 23 and a second supply unit 24. The second supply path 23 may be a pipe through which air flows. The second supply unit 24 may cause air to flow in the second supply path. The second supply unit 24 may cause air to flow, for example, by increasing the pressure of the air. The second supply unit 24 may be capable of adjusting the flow rate of the air according to the operating intensity. The operating intensity is a variable value that can contribute to an increase in the flow rate of the second supply unit 24. The operating intensity is, for example, the rotation speed in a configuration in which the second supply unit 24 is a centrifugal blower. The second supply unit 24 may be, for example, a centrifugal blower with a variable duty ratio.

[0017] The second supply system 17 may be provided with a second flow rate sensor 25. The second flow rate sensor 25 may detect the flow rate of the fluid flowing in the second supply path 23. The second flow rate sensor 25 may provide the detected flow rate as information to the control unit 12.

[0018] The third supply system 18 may supply water to the reformer 15. The third supply system 18 may include a third supply path 26 and a third supply unit 27. The third supply path 26 may be a pipe through which water flows. The third supply unit 27 may pressurize the water to cause it to flow within the third supply path 26. The third supply unit 27 may be capable of adjusting the amount of water supplied. The third supply unit 27 may be, for example, a pump whose duty ratio is variable.

[0019] The voltage sensor 19 may detect the voltage of the fuel cell 13. The voltage sensor 19 may provide the detected voltage to the control unit 12 as information.

[0020] The temperature sensor 28 may detect the temperature of the power generation unit 11. The temperature sensor 28 is, for example, a temperature sensor such as a thermocouple or a thermistor.

[0021] The control unit 12 is configured to include at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for specific processing. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like. The control unit 12 may control the operation of the fuel cell system 10.

[0022] The control unit 12 may further include a storage unit. The storage unit may include any storage device, such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The storage unit may store various programs that cause the control unit 12 to function and various information used by the control unit 12.

[0023] For example, the memory unit may store a correspondence relationship between the range of the operation index of the first supply unit 21 and the flow rate of fuel gas in the first supply system 16. Also, for example, the memory unit may store a correspondence relationship between the range of the operation index of the second supply unit 24 and the flow rate of air in the second supply system 17. This correspondence relationship is not limited to a one-to-one relationship, and one value may correspond to the other value as a range. This correspondence relationship may be, for example, a relational expression or a correspondence table.

[0024] The operation index of the first supply unit 21 is a detectable numerical value that indicates the operation status of the first supply unit 21, corresponding to the flow rate of fuel gas flowing through the first supply path 16 when the first supply path 16 is normal. The operation index of the second supply unit 24 is a detectable numerical value that indicates the operation status of the second supply unit 24, corresponding to the flow rate of air flowing through the second supply path 17 when the second supply path 17 is normal. The operation index is, for example, the rotation speed, the current value, drive voltage, input power (current x voltage) etc. that are supplied to the turbo pump when the first supply unit 21 is a turbo pump, or the rotation speed, the current value, drive voltage, input power (current x voltage) etc. that are supplied to the centrifugal blower when the second supply unit 24 is a centrifugal blower.

[0025] The control unit 12 may acquire information about the voltages of the power generation units 11 from the voltage sensors 19 provided in the power generation units 11. The control unit 12 may calculate the difference between the voltages. The difference may be, for example, an absolute deviation with the average voltage value as a reference value, or the absolute value of the difference between two arbitrarily selected power generation units 11.

[0026] If the calculated voltage difference exceeds the voltage threshold, the control unit 12 checks the state of at least one of the first supply system 16 and the second supply system 17. The state check is, for example, checking for the occurrence of a blockage.

[0027] To check the status, the control unit 12 may acquire the operation indexes of the first supply unit 21 and the second supply unit 24 from sensors or the like provided in the first supply unit 21 and the second supply unit 24. In checking the status, the control unit 12 may perform at least one of a first comparison and a second comparison. In the first comparison, the control unit 12 may compare the flow rate of fuel gas acquired as information from the first flow rate sensor 22 with the operation index of the first supply unit 21. In a configuration in which a reformer 15 is provided, the flow rate of fuel gas in the first comparison may be the flow rate of the raw fuel. In the second comparison, the control unit 12 may compare the flow rate of air acquired as information from the second flow rate sensor 25 with the operation index of the second supply unit 24.

[0028] Specifically, the control unit 12 may perform a first comparison with the power generation unit 11 with the lowest voltage among the power generation units 11 whose voltage difference exceeds the voltage threshold. In a configuration in which the difference is an absolute deviation, the power generation unit 11 with the lowest voltage is the power generation unit 11 whose voltage is lower than the reference value. The control unit 12 may compare the operation index of the first supply unit 21 in the power generation unit 11 with the lowest voltage with an operation index based on a correspondence relationship between the fuel gas flow rate acquired from the first flow sensor 22 of the power generation unit 11. The operation index based on the correspondence relationship is not limited to a value uniquely determined for the fuel gas flow rate, as described above, and may have a range including tolerance. If the operation index of the first supply unit 21 deviates from the operation index based on the correspondence relationship with the fuel gas flow rate, the control unit 12 may determine that there is an abnormality in the first supply system 16 of the power generation unit 11.

[0029] In the power generation unit 11, the supply amounts of fuel gas, air, and water are determined as flow rates based on the required current, etc., and the first supply unit 21, the second supply unit 24, and the third supply unit 27 operate to achieve the determined flow rates. Therefore, for example, in a configuration in which the operation index is the rotational speed, if a blockage occurs in the first supply system 16, the rotational speed is increased to achieve the specified flow rate. As a result, the rotational speed, which is the detected operation index, is higher than the rotational speed corresponding to the detected fuel gas flow rate, compared to when the first supply system 16 is normal.

[0030] Furthermore, because the workload of a turbo pump is pressure x flow rate, if a blockage occurs during constant pump drive control, the flow rate decreases, and so the workload also decreases. Therefore, in a configuration in which the operation index is the current flowing through the turbo pump motor, if a blockage occurs in the first supply system 16, the current value decreases. Furthermore, when the pump is driven under constant flow rate control, the drive voltage increases and the input power (voltage x current) changes.

[0031] Specifically, the control unit 12 may perform a second comparison on the power generation unit 11 with the higher voltage among the power generation units 11 whose voltage difference exceeds the voltage threshold. In a configuration in which the difference is an absolute deviation, the power generation unit 11 with the higher voltage is the power generation unit 11 whose voltage is higher than the reference value. The control unit 12 may compare the operation index of the second supply unit 24 in the power generation unit 11 with the higher voltage with an operation index based on a correspondence relationship between the air flow rate acquired from the second flow sensor 25 of the power generation unit 11. The operation index based on the correspondence relationship is not limited to a value uniquely determined for the fuel gas flow rate, as described above, but may have a range including tolerance. If the operation index of the second supply unit 24 deviates from the operation index corresponding to the air flow rate, the control unit 12 may determine that there is an abnormality in the second supply system 17 of the power generation unit 11.

[0032] Furthermore, for example, in a configuration in which the operation index is the rotational speed, if a blockage occurs in the second supply system 17, the rotational speed is increased so as to achieve the specified flow rate. As a result, the rotational speed, which is the detected operation index, becomes larger than the rotational speed corresponding to the detected air flow rate, compared to when the second supply system 17 is normal.

[0033] Furthermore, because the workload of a centrifugal blower is pressure x flow rate, if a blockage occurs during constant blower drive control, the flow rate decreases, and so the workload also decreases. Therefore, in a configuration in which the operation index is the current flowing through the centrifugal blower motor, if a blockage occurs in the second supply system 17, the current value decreases. Furthermore, when the blower is driven under constant flow rate control, the drive voltage increases and the input power (voltage x current) changes.

[0034] When the control unit 12 determines that there is an abnormality in the first supply system 16, it may increase the operating intensity of the first supply unit 21 for a predetermined time. When the control unit 12 determines that there is an abnormality in the second supply system 17, it may increase the operating intensity of the second supply unit 24 for a predetermined time.

[0035] When the control unit 12 determines that there is an abnormality in at least one of the first supply system 16 and the second supply system 17, it notifies the user of the abnormality. The notification is made, for example, by issuing a notification instruction to an output device communicating with the control unit 12, causing the output device to output information indicating the abnormality. The output device is, for example, a display, a warning lamp, or a speaker.

[0036] The control unit 12 may perform the above-described state check when the temperatures of the plurality of power generation units 11 are within a predetermined temperature range. The predetermined temperature range is a temperature range assumed during normal operation for the voltage of the fuel cell 13 of the power generation unit 11.

[0037] Next, the confirmation process executed by the control unit 12 in this embodiment will be described with reference to the flowchart of Fig. 3. The confirmation process is started periodically, for example.

[0038] In step S100, the control unit 12 calculates the difference in voltage between the multiple power generation units 11. In the description of this flowchart, the voltage difference is an absolute deviation with the average value of the voltages of the multiple power generation units 11 as a reference value, but is not limited to this. After the calculation, the process proceeds to step S101.

[0039] In step S101, the control unit 12 determines whether or not there is a power generation unit 11 among the multiple power generation units 11 whose difference calculated in step S100 exceeds the voltage threshold. If there is a power generation unit 11 whose difference exceeds the voltage threshold, the process proceeds to step S102. If there is no power generation unit 11 whose difference exceeds the voltage threshold, the confirmation process ends.

[0040] In step S102, the control unit 12 determines whether the temperature detected by the temperature sensor 28 provided in the power generation unit 11, whose difference was determined to exceed the voltage threshold in step S101, is within a predetermined temperature range. If the temperature is within the predetermined temperature range, the process proceeds to step S103. If the temperature is outside the predetermined temperature range, the confirmation process ends.

[0041] In step S103, the control unit 12 determines whether there is a power generation unit 11 with a lower voltage. As described above, a lower voltage power generation unit 11 is a power generation unit 11 whose voltage is lower than the reference value. If there is a power generation unit 11 with a lower voltage, the process proceeds to step S104. If there is no power generation unit 11 with a lower voltage, the process proceeds to step S106.

[0042] In step S104, the control unit 12 determines whether the operation index of the first supply unit 21 in the power generation unit 11 with the smaller voltage confirmed in step S103 deviates from the operation index based on the correspondence relationship with the fuel gas flow rate acquired from the first flow rate sensor 22 of that power generation unit 11. If the operation index of the first supply unit 21 deviates, the process proceeds to step S105. If the operation index of the first supply unit 21 does not deviate, the process proceeds to step S106.

[0043] In step S105, the control unit 12 determines that there is an abnormality in the first supply system 16 of the power generation unit 11 whose operation index state was confirmed in step S104. After this determination, the process proceeds to step S106.

[0044] In step S106, the control unit 12 determines whether there is a power generation unit 11 with a higher voltage. As described above, a higher voltage power generation unit 11 is a power generation unit 11 whose voltage is higher than the reference value. If there is a power generation unit 11 with a higher voltage, the process proceeds to step S107. If there is no power generation unit 11 with a higher voltage, the process proceeds to step S109.

[0045] In step S107, the control unit 12 determines whether the operation index of the second supply unit 24 in the power generation unit 11 having the higher voltage confirmed in step S106 deviates from the operation index based on the correspondence relationship with the air flow rate acquired from the second flow rate sensor 25 of that power generation unit 11. If the operation index of the second supply unit 24 deviates, the process proceeds to step S108. If the operation index of the second supply unit 24 does not deviate, the process proceeds to step S109.

[0046] In step S108, the control unit 12 determines that there is an abnormality in the second supply system 17 of the power generation unit 11 whose operation index state was confirmed in step S107. After this determination, the process proceeds to step S109.

[0047] In step S109, the control unit 12 determines whether or not there is an abnormality in at least one of the first supply system 16 and the second supply system 17 of any of the power generation units 11. If there is an abnormality, the process proceeds to step S110. If there is no abnormality in the first supply system 16 or the second supply system 17 of any of the power generation units 11, the confirmation process ends.

[0048] In step S110, the control unit 12 increases, for a predetermined time, the operating intensity of at least one of the first supply system 16 and the second supply system 17 of the power generation unit 11 that is determined to have an abnormality. After the increase, the process proceeds to step S111.

[0049] In step S111, the control unit 12 notifies the user that an abnormality has occurred, and then the confirmation process ends.

[0050] The fuel cell system 10 of this embodiment, configured as described above, includes a plurality of power generation units 11 electrically connected in series, each including a fuel cell 13 that generates electricity using fuel gas supplied from a first supply system 16 and air supplied from a second supply system 17, and a control unit 12 that checks the status of at least one of the first supply system 16 and the second supply system 17 when the difference in voltage between the plurality of power generation units 11 exceeds a voltage threshold. A malfunction in the first supply system 16 or the second supply system 17 disrupts normal operation of the fuel cell 13. Therefore, it is desirable to appropriately check the status of the first supply system 16 and the second supply system 17. However, constantly checking the status is undesirable because it places unnecessary strain on the control unit 12, and reducing the frequency of status checks can lead to delays in detecting malfunctions. To address such issues, the fuel cell system 10 configured as described above checks the status based on an increase in the voltage difference that may occur when a malfunction occurs in the first supply system 16 or the second supply system 17. Therefore, the fuel cell system 10 can appropriately check for malfunctions. The control unit 12 may constantly check the state of at least one of the first supply system 16 and the second supply system 17 .

[0051] Furthermore, the fuel cell system 10 checks the status when the temperatures of the multiple power generation units 11 are within a predetermined temperature range. If there is a difference in voltage among the multiple power generation units 11, it is possible that at least one of the fuel gas and air is not at an appropriate flow rate. In response to such an event, the fuel cell system 10 having the above-described configuration checks the status under more limited conditions, making it possible to more appropriately confirm the occurrence of a malfunction.

[0052] In the fuel cell system 10, the first supply system 16 includes a first supply path 20 and a first supply unit 21 that causes fuel gas to flow through the first supply path 20, and the second supply system 17 includes a second supply path 23 and a second supply unit 24 that causes air to flow through the second supply path 23. In checking the status, the control unit 12 performs at least one of comparing the flow rate of fuel gas through the first supply path 16 with the operation index of the first supply unit 21 and comparing the flow rate of air through the second supply path 17 with the operation index of the second supply unit 24. With this configuration, the fuel cell system 10 compares the operation index corresponding to the flow rate through each of the paths 20 and 23 with the actual operation index of each of the supply units 21 and 24, thereby estimating the actual operating state. Therefore, the fuel cell system 10 can check the status of the supply systems 16 and 17 with higher accuracy, thereby determining the cause of voltage variations among the multiple power generation units 11.

[0053] Furthermore, the fuel cell system 10 determines that there is an abnormality in the first supply system 16 when the operation index of the first supply unit 21 in the power generation unit 11 with the lower voltage among the power generation units 11 whose voltage difference exceeds the voltage threshold deviates from the operation index based on the correspondence relationship with the fuel gas flow rate in the first supply path 20 to that power generation unit 11. In the power generation unit 11 with the lower voltage, it is assumed that the concentration of fuel gas in the fuel cell 13 is lower than normal. Therefore, there is a high possibility that there is a malfunction in the fuel gas supply in the power generation unit 11 with the lower voltage. In such an event, the fuel cell system 10 having the above-described configuration checks the state of the first supply system 16 in a situation where there is a high possibility that there is a malfunction in the first supply system 16, thereby enabling more appropriate confirmation of the occurrence of a malfunction.

[0054] Furthermore, the fuel cell system 10 determines that there is an abnormality in the second supply system 17 when the operation index of the second supply unit 24 of the power generation unit 11 with the higher voltage among the power generation units 11 whose voltage difference exceeds the voltage threshold deviates from the operation index based on the correspondence relationship with the air flow rate in the second supply path 23 to that power generation unit 11. In the power generation unit 11 with the higher voltage, it is expected that cooling of the power generation unit 11 by air within the fuel cell 13 is suppressed. Therefore, there is a high possibility that there is a malfunction in the air supply to the power generation unit 11 with the higher voltage. In such an event, the fuel cell system 10 having the above-described configuration checks the status of the second supply system 17 in a situation where there is a high possibility that there is a malfunction in the second supply system 17, thereby more appropriately confirming the occurrence of the malfunction.

[0055] Furthermore, when the fuel cell system 10 determines that there is an abnormality in the first supply system 16, it increases the operating intensity of the first supply unit 21 for a predetermined time, and when it determines that there is an abnormality in the second supply system 17, it increases the operating intensity of the second supply unit 24 for a predetermined time. A major cause of abnormalities in the first supply system 16 and the second supply system 17 can be clogging due to foreign matter or the like. In response to such an event, the fuel cell system 10 having the above-described configuration can blow away the foreign matter or the like by increasing the operating intensity. Therefore, the fuel cell system 10 can return the abnormal state of the first supply system 16 and the second supply system 17 to a normal state.

[0056] Furthermore, the fuel cell system 10 notifies the maintenance personnel of the fuel cell system 10 when it determines that there is an abnormality in at least one of the first supply system 16 and the second supply system 17. With this configuration, the fuel cell system 10 can notify the maintenance personnel of the fuel cell system 10 that an abnormality has occurred in at least one of the first supply system 16 and the second supply system 17. Therefore, the fuel cell system 10 can prompt the maintenance personnel to confirm the abnormal state and perform maintenance work.

[0057] In one embodiment, (1) a fuel cell system includes a plurality of power generation units electrically connected in series, each including a fuel cell that generates electricity using fuel gas supplied from a first supply system and air supplied from a second supply system, and a control unit that checks the status of at least one of the first supply system and the second supply system when a difference in voltage between the plurality of power generation units exceeds a voltage threshold.

[0058] (2) In the fuel cell system of (1) above, the control unit performs the state check when the temperatures of the plurality of power generation units are within a predetermined temperature range.

[0059] (3) In the fuel cell system of (2) above, the first supply system has a first supply path and a first supply unit that causes the fuel gas to flow through the first supply path, the second supply system has a second supply path and a second supply unit that causes the air to flow through the second supply path, and in the state confirmation, the control unit performs at least one of comparing the flow rate of the fuel gas in the first supply path with an operation index in the first supply unit, and comparing the flow rate of air in the second supply path with an operation index in the second supply unit.

[0060] (4) In the fuel cell system of (3) above, the control unit determines that there is an abnormality in the first supply system when the operation index of the first supply unit in the power generation unit with the lower voltage among the power generation units whose voltage difference exceeds the voltage threshold deviates from the operation index based on the correspondence with the flow rate of fuel gas in the first supply path to the power generation unit.

[0061] (5) In the fuel cell system of (3) or (4) above, the control unit determines that there is an abnormality in the second fuel supply system if the operation index of the second supply unit in the power generation unit with the higher voltage among the power generation units whose voltage difference exceeds the voltage threshold deviates from the operation index based on the correspondence with the air flow rate in the second supply path to the power generation unit.

[0062] (6) In any of the fuel cell systems (3) to (5) above, in the fuel cell system according to any one of claims 3 to 5, the control unit increases the operating intensity of the first supply unit for a predetermined time when it determines that there is an abnormality in the first supply system, and increases the operating intensity of the second supply unit for the predetermined time when it determines that there is an abnormality in the second supply system.

[0063] (7) In the fuel cell system of any one of (3) to (6) above, the control unit notifies the abnormality when determining that there is an abnormality in at least one of the first supply system and the second supply system.

[0064] The above has described an embodiment of the fuel cell system 10, but the present disclosure can also be embodied as a method or program for implementing the device, as well as a storage medium on which a program is recorded (for example, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a hard disk, or a memory card).

[0065] Furthermore, the implementation form of the program is not limited to application programs such as object code compiled by a compiler or program code executed by an interpreter, but may also be in the form of a program module incorporated into an operating system. Furthermore, the program may or may not be configured so that all processing is performed solely by the CPU on the control board. The program may also be configured so that part or all of it is executed by another processing unit mounted on an expansion board or expansion unit added to the board as needed.

[0066] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0067] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art could make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined or divided into one.

[0068] All of the features described in this disclosure and / or all steps of all disclosed methods or processes may be combined in any combination except combinations in which these features are mutually exclusive. Furthermore, each feature described in this disclosure may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless expressly denied. Thus, unless expressly denied, each disclosed feature is only one example of a generic series of identical or equivalent features.

[0069] Furthermore, embodiments of the present disclosure are not limited to the specific configurations of any of the above-described embodiments, but rather extend to any novel feature or combination thereof described herein, or any novel method or process step or combination thereof described herein.

[0070] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, the configurations distinguished by descriptions such as "first" and "second" can have their numbers exchanged. For example, the first supply system can exchange the identifiers "first" and "second" with the second supply system. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the identifier exchange. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number.

[0071] REFERENCE SIGNS LIST 10 fuel cell system 11 power generation unit 12 control unit 13 fuel cell 14 combustion unit 15 reformer 16 first supply system 17 second supply system 18 third supply system 19 voltage sensor 20 first supply path 21 first supply unit 22 first flow rate sensor 23 second supply path 24 second supply unit 25 second flow rate sensor 26 third supply path 27 third supply unit 28 temperature sensor

Claims

1. A fuel cell system comprising: a plurality of power generation units electrically connected in series, each including a fuel cell that generates electricity using fuel gas supplied from a first supply system and air supplied from a second supply system; and a control unit that checks the status of at least one of the first supply system and the second supply system when the difference in voltage between the plurality of power generation units exceeds a voltage threshold.

2. A fuel cell system according to claim 1, wherein the control unit performs the state check when the temperatures of the plurality of power generation units are within a predetermined temperature range.

3. A fuel cell system as claimed in claim 2, wherein the first supply system has a first supply path and a first supply unit that causes the fuel gas to flow through the first supply path, the second supply system has a second supply path and a second supply unit that causes the air to flow through the second supply path, and the control unit, in checking the state, performs at least one of comparing the flow rate of the fuel gas in the first supply path with an operation index in the first supply unit, and comparing the flow rate of air in the second supply path with an operation index in the second supply unit.

4. A fuel cell system as described in claim 3, wherein the control unit determines that there is an abnormality in the first supply system when the operation index of the first supply unit in the power generation unit with the lower voltage among the power generation units whose voltage difference exceeds the voltage threshold deviates from the operation index based on the correspondence with the flow rate of fuel gas in the first supply path to the power generation unit.

5. A fuel cell system according to claim 3 or 4, wherein the control unit determines that there is an abnormality in the second supply system when the operation index of the second supply unit in the power generation unit with the higher voltage among the power generation units whose voltage difference exceeds the voltage threshold deviates from the operation index based on the correspondence with the air flow rate in the second supply path to the power generation unit.

6. A fuel cell system according to any one of claims 3 to 5, wherein the control unit increases the operating intensity of the first supply unit for a predetermined time when it determines that there is an abnormality in the first supply system, and increases the operating intensity of the second supply unit for the predetermined time when it determines that there is an abnormality in the second supply system.

7. A fuel cell system according to any one of claims 3 to 6, wherein the control unit notifies the abnormality when it determines that there is an abnormality in at least one of the first supply system and the second supply system.

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