Fuel cell system and control method of fuel cell system

Abstract

To discharge produced water increased in a fuel cell system properly without complicating the fuel cell system.SOLUTION: According to one embodiment, a fuel cell system S1 includes: a fuel cell stack 10; a storage part 20 that stores a water component including circulating water supplied to the fuel cell stack 10, and produced water produced in and discharged from the fuel cell stack 10; a gas outlet pipe 42 that sends a gas discharged from the fuel cell stack 10 to the storage part 20; a pressure acquisition part 44 that acquires a pressure of the gas discharged from the fuel cell stack 10; a drain pipe 21 connected to the storage part 20 to allow the water component discharged from the storage part 20 to flow; a drain valve 22 provided on the drain pipe; and a control device 100. The control device 100 controls opening and closing of the drain valve 22 based on the pressure of the gas acquired by the pressure acquisition part 44.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a fuel cell system and a method for controlling the fuel cell system.

Background Art

[0002] In a polymer electrolyte fuel cell equipped with a polymer electrolyte membrane, humidification of the supply gas is usually required to obtain sufficient power generation performance. At the same time, cooling is usually required to remove the heat generated by the battery reaction. As a method of performing such humidification and cooling simultaneously, an internal humidification and cooling method using a conductive porous plate with micropores as a separator is known. In this method, by filling the micropores of the conductive porous plate with water and controlling the differential pressure between the fuel gas, the oxidant gas, and the cooling and humidifying water within a certain range, leakage of the gas (fuel gas and oxidant gas) can be prevented. Thereby, uniform humidification and cooling within the reaction surface can be performed simultaneously. Furthermore, by setting the pressures of the fuel gas and the oxidant gas higher than the pressure of the cooling and humidifying water, the generated water due to the battery reaction is recovered through the conductive porous plate, so that a performance degradation due to flooding can be prevented.

[0003] As a technique for controlling the differential pressure between the pressures of the fuel gas and the oxidant gas and the pressure of the cooling and humidifying water within a certain range, a method is known in which the piping of the gas discharged from the fuel cell stack is connected to the cooling and humidifying water tank to keep the differential pressure between the gas and the cooling and humidifying water constant.

[0004] When connecting the pipe for the gas discharged from the fuel cell stack to the cooling and humidifying water tank as described above, a part of the generated water due to the battery reaction is usually condensed and then recovered in the above cooling and humidifying water tank. And such generated water gradually increases. Therefore, in such a configuration, in order to prevent water clogging in the pipe, usually, the drain valve is controlled to periodically discharge the stored water in the cooling and humidifying water tank mixed with the generated water to the outside of the system. As a method for determining the timing of performing such discharge, for example, a method of providing a water level gauge in the tank to monitor the amount of generated water and performing discharge according to the detection of the water level gauge is known. Also known is a method of predicting the amount of generated water based on the integrated power generation amount and performing discharge according to the predicted value.

[0005] However, the above technology regarding discharge may not always function desirably depending on the application conditions of the fuel cell system. For example, when the fuel cell system is mounted on a moving body such as an automobile or a truck, the above technology regarding discharge may not always be good.

[0006] Specifically, when the fuel cell system is mounted on a moving body, the tank water level fluctuates due to inclination, acceleration, and deceleration. Therefore, it may be difficult to accurately monitor the water level. Also, when predicting the amount of generated water based on the integrated power generation amount, for example, it is required to accurately calculate the ratio of the component that is condensed and recovered in the generated water and the ratio of the component that is discharged together with the exhaust gas as water vapor. In this case, measurement and correction by many sensors are necessary, and in a situation where the surrounding conditions and the power generation output change moment by moment like a moving body, the reliability of the predicted value may decrease. If the amount of generated water inside the system is misdetected, the drain pipe may be vented to the atmosphere at an unexpected timing. When such unnecessary draining is performed, the pressure balance inside the fuel cell system may be disrupted. As a result, there is a risk of deterioration of power generation performance and product life, and ultimately being unable to operate.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] Accordingly, the problem to be solved by the present invention is to provide a fuel cell system and a control method for the fuel cell system that can appropriately discharge the increased water component in the fuel cell system without complicating the fuel cell system. [Means for Solving the Problems]

[0009] A fuel cell system according to an embodiment includes a fuel cell stack, a storage unit that stores a water component including circulated water supplied to the fuel cell stack and circulated from the fuel cell stack, and generated water generated in the fuel cell stack and discharged from the fuel cell stack, a gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage unit, a pressure acquisition unit that acquires the pressure of the gas discharged from the fuel cell stack, a drain pipe that is connected to the storage unit and circulates the water component discharged from the storage unit, a drain valve provided in the drain pipe, and a control device that controls the opening and closing of the drain valve. The control device controls the opening and closing of the drain valve based on the pressure of the gas acquired by the pressure acquisition unit.

[0010] A fuel cell system according to an embodiment includes a fuel cell stack, a circulation water that is supplied to the fuel cell stack and circulates from the fuel cell stack, and a storage unit that stores a water component including generated water that is generated in the fuel cell stack and discharged from the fuel cell stack, a gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage unit, a pressure acquisition unit that acquires the pressure of the gas discharged from the fuel cell stack, a gas backpressure adjustment valve that adjusts the pressure of the gas discharged from the fuel cell stack based on a drive pulse signal whose duty ratio can be changed according to the pressure of the gas acquired by the pressure acquisition unit, a duty ratio acquisition unit that acquires the duty ratio of the drive pulse signal for the gas backpressure adjustment valve, a drain pipe that is connected to the storage unit and allows the water component discharged from the storage unit to flow therethrough, a drain valve provided in the drain pipe, and a control device that controls the opening and closing of the drain valve. The control device controls the opening and closing of the drain valve based on the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit.

[0011] A control method for a fuel cell system according to an embodiment is a control method for a fuel cell system including a fuel cell stack, a circulation water that is supplied to the fuel cell stack and circulates from the fuel cell stack, a storage unit that stores a water component including generated water that is generated in the fuel cell stack and discharged from the fuel cell stack, a gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage unit, a drain pipe that is connected to the storage unit and allows the water component discharged from the storage unit to flow therethrough, and a drain valve provided in the drain pipe. The method includes a pressure acquisition step of acquiring the pressure of the gas discharged from the fuel cell stack, and a control step of controlling the opening and closing of the drain valve based on the pressure of the gas acquired in the pressure acquisition step.

[0012] A control method for a fuel cell system according to an embodiment includes a fuel cell stack, circulating water supplied to the fuel cell stack and circulated from the fuel cell stack, and generated water generated in the fuel cell stack and discharged from the fuel cell stack. A storage unit for storing a water component including the above, a gas outlet pipe for sending the gas discharged from the fuel cell stack to the storage unit, a pressure acquisition unit for acquiring the pressure of the gas discharged from the fuel cell stack, and a duty ratio based on a drive pulse signal whose duty ratio can be changed according to the pressure of the gas acquired by the pressure acquisition unit. A gas backpressure adjustment valve for adjusting the pressure of the gas discharged from the fuel cell stack, a drain pipe connected to the storage unit and allowing the water component discharged from the storage unit to flow therethrough, and a drain valve provided in the drain pipe. It is a control method for a fuel cell system. The method includes a duty ratio acquisition step of acquiring the duty ratio of the drive pulse signal for the gas backpressure adjustment valve, and a control step of controlling the opening and closing of the drain valve based on the duty ratio of the drive pulse signal acquired in the duty ratio acquisition step.

Effect of the Invention

[0013] According to the present invention, without complicating the fuel cell system, the increased water component in the fuel cell system can be appropriately discharged.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0015] Hereinafter, each embodiment will be described with reference to the accompanying drawings.

[0016] <First Embodiment> FIG. 1 schematically shows a fuel cell system S1 according to the first embodiment. As shown in FIG. 1, the fuel cell system S1 includes a fuel cell stack 10, a storage unit 20, a fuel gas pipe 30, an oxidant gas pipe 40, a circulating water pipe 50, and a control device 100.

[0017] The fuel cell stack 10 is supplied with fuel gas via the fuel gas pipe 30 and supplied with oxidant gas via the oxidant gas pipe 40. Thereby, the fuel cell stack 10 generates an electrochemical reaction to generate electricity. The storage unit 20 stores circulating water described later for humidifying the fuel cell stack 10 and cooling the heat generated by the electrochemical reaction. The circulating water pipe 50 sends circulating water from the storage unit 20 to the fuel cell stack 10 and circulates the circulating water from the fuel cell stack 10 to the storage unit 20. The control device 100 controls each part of the fuel cell system S1. Hereinafter, each part constituting the fuel cell system S1 will be described in detail.

[0018] The fuel cell stack 10 reacts hydrogen (H2) contained in the fuel gas supplied via the fuel gas pipe 30 as described above with the anode electrode 12, and reacts oxygen contained in the oxidant gas supplied via the oxidant gas pipe 40 with the cathode electrode 13. FIG. 2 is a schematic cross-sectional view of the fuel cell stack 10.

[0019] As shown in FIG. 2, the fuel cell stack 10 is composed of stacking a plurality of single cells Ce. The single cell Ce includes a separator 11, an anode electrode 12, a cathode electrode 13, an anode electrode separator 14, and a cathode electrode separator 15.

[0020] In this embodiment, the fuel cell stack 10 is of a polymer electrolyte type. Therefore, the separator 11 is a solid polymer electrolyte membrane (ion exchange membrane) having ion conductivity. The anode electrode 12 is disposed so as to contact one surface of the separator 11, and the cathode electrode 13 is disposed so as to contact the other surface of the separator 11. Hereinafter, the laminate of the separator 11, the anode electrode 12, and the cathode electrode 13 may be referred to as a membrane electrode assembly.

[0021] The anode electrode separator 14 and the cathode electrode separator 15 are disposed so as to sandwich the membrane electrode assembly (11, 12, 13). The anode electrode separator 14 is disposed so as to contact the anode electrode 12, and the cathode electrode separator 15 is disposed so as to contact the cathode electrode 13. In this embodiment, the anode electrode separator 14 and the cathode electrode separator 15 are formed of a porous body such as a conductive metal, carbon, or ceramics. The anode electrode separator 14 and the cathode electrode separator 15 are plate-shaped.

[0022] When the single cells Ce described above are stacked, the single cells Ce are stacked such that one anode electrode separator 14 of two adjacent single cells Ce contacts the other cathode electrode separator 15.

[0023] The fuel cell stack 10 is provided with a fuel gas flow path 17 that at least partially faces the anode electrode 12 and circulates the above-described fuel gas to supply it to the anode electrode 12, an oxidant gas flow path 18 that at least partially faces the cathode electrode 13 and circulates the above-described oxidant gas to supply it to the cathode electrode 13, and a circulation water flow path 19 that circulates the circulating water from the storage unit 20.

[0024] Specifically, a plurality of fuel gas flow paths 17 are formed in the anode separator 14. The fuel gas flow paths 17 are, for example, in a groove shape and are formed on the surface of the anode separator 14 facing the anode electrode 12. Further, a plurality of oxidant gas flow paths 18 and a plurality of circulating water flow paths 19 are formed in the cathode separator 15.

[0025] The oxidant gas flow paths 18 are, for example, in a groove shape and are formed on the surface of the cathode separator 15 facing the cathode electrode 13. The circulating water flow paths 19 are, for example, in a groove shape and are formed on the surface of the cathode separator 15 opposite to the surface on which the oxidant gas flow paths 18 are formed. The oxidant gas flow paths 18 and the circulating water flow paths 19 are separated in the thickness direction in the cathode separator 15.

[0026] Note that the circulating water flow paths 19 may be formed in the anode separator 14 instead of the cathode separator 15. Further, a separator in which the circulating water flow paths 19 are formed may be provided separately from the anode separator 14 and the cathode separator 15, and the separator may be provided, for example, between the anode separator 14 and the cathode separator 15.

[0027] Returning to FIG. 1, the fuel gas pipe 30 has a fuel gas inlet pipe 31 and a fuel gas outlet pipe 32 that are respectively connected to the fuel cell stack 10. The fuel cell stack 10 takes in a fuel gas containing hydrogen from the fuel gas inlet pipe 31 and reacts the hydrogen with the anode electrode 12. The fuel cell stack 10 discharges the unreacted fuel gas to the fuel gas outlet pipe 32.

[0028] The fuel gas may be stored in a tank, for example. In this case, the upstream end of the fuel gas inlet pipe 31 may be connected to a tank that stores the fuel gas. Further, the fuel gas discharged from the fuel cell stack 10 to the fuel gas outlet pipe 32 may be discharged to the atmosphere, for example.

[0029] The oxidant gas pipe 40 has an oxidant gas inlet pipe 41 and an oxidant gas outlet pipe 42, each of which is connected to the fuel cell stack 10. The fuel cell stack 10 takes in an oxidant gas containing oxygen from the oxidant gas inlet pipe 41 and reacts the oxygen with the cathode electrode 13. The fuel cell stack 10 discharges the unreacted oxidant gas to the oxidant gas outlet pipe 42.

[0030] A compressor 43 is provided in the oxidant gas inlet pipe 41. The compressor 43 compresses the oxidant gas and supplies it to the fuel cell stack 10. In this case, compared with the case where the oxidant gas is not compressed, the supply amount of oxygen per unit time to the fuel cell stack 10 can be increased. Thereby, the power generation output can be increased. The oxidant gas may be air in the atmosphere. In this case, the upstream end of the oxidant gas inlet pipe 41 may be open to the atmosphere. In the configuration where the oxidant gas inlet pipe 41 is open to the atmosphere, air as the oxidant gas flows into the oxidant gas inlet pipe 41 as the compressor 43 is driven. The compressor 43 is electrically connected to the control device 100, and the drive state (discharge pressure, rotational speed) is controlled by the control device 100.

[0031] The oxidant gas outlet pipe 42 connects the fuel cell stack 10 and the storage unit 20. The oxidant gas outlet pipe 42 sends the oxidant gas discharged from the fuel cell stack 10 to the storage unit 20.

[0032] The storage unit 20 is a container that stores a water component including the circulating water supplied to the fuel cell stack 10 and circulated from the fuel cell stack 10, and the generated water generated in the fuel cell stack 10 and discharged from the fuel cell stack 10. The circulating water is stored in the storage unit 20 in advance before operation to cool and humidify the fuel cell stack 10. When the generated water is stored in the storage unit 20, the generated water can contribute to the cooling and humidification of the fuel cell stack 10 together with the circulating water.

[0033] A drain pipe 21 and a gas discharge pipe 26 are connected to the storage section 20. A drain valve 22 is provided in the drain pipe 21. The drain pipe 21 allows the water component discharged from the storage section 20 to flow through. The drain valve 22 switches between allowing and blocking the flow of the water component in the drain pipe 21 by opening and closing. When the storage amount of the generated water in the storage section 20 increases, the pressure inside the storage section 20 rises, and a situation may occur where the stability of the operation is impaired. In order to avoid such a situation, the drain pipe 21 and the drain valve 22 are provided.

[0034] In the drain pipe 21 in the present embodiment, the water intake 21A at its upstream end is provided so as to be located above the bottom surface of the storage section 20. In this case, when the water intake 21A is lower than the water level of the storage section 20, the drain operation is started by opening the drain valve 22, and when the water level of the storage section 20 drops to the position of the water intake 21A, the drain operation mechanically stops. Thereby, excessive discharge of the water component is avoided. And in the present embodiment, after the water level of the storage section 20 drops to the position of the water intake 21A, the drain valve 22 is closed, so that the drain is completely blocked. As will be described later, when the water intake 21A is located above the bottom surface of the storage section 20, as the water level of the storage section 20 drops to the position of the water intake 21A, the inflow of the oxidant gas flowing into the storage section 20 from the oxidant gas outlet pipe 42 to the water intake 21A is allowed. In the present embodiment, by enabling discharge through the water intake 21A located above the bottom surface of the storage section 20, it is possible to relatively greatly reduce the pressure inside the storage section 20 during drainage, and the drain valve 22 can be closed based on the relatively greatly reduced pressure. Thereby, while suppressing excessive discharge of the water component, it is possible to appropriately detect the closing timing of the drain valve 22 based on the pressure.

[0035] Also, the mode of stopping the drain operation using the position of the water intake 21A as described above simplifies the structure by using a mechanical configuration compared to the case of closing the drain valve 22 using a water level gauge. Also, the load on the drain valve 22 can be reduced compared to the case of closing the drain valve 22 to stop the drain operation. However, the water intake 21A of the drain pipe 21 may be connected to the bottom of the storage section 20.

[0036] The drain valve 22 is electrically connected to the control device 100 and its opening and closing are controlled by the control device 100. The drain valve 22 is an on-off valve that switches between two positions, an open state and a closed state, in the present embodiment. The switching of the opening and closing of the drain valve 22 may be performed by an electromagnetic solenoid or may be performed by shutting off the supply of air.

[0037] The gas discharge pipe 26 receives the oxidant gas that has flowed from the fuel cell stack 10 into the storage unit 20 and circulates it for exhaust. The gas discharge pipe 26 is connected to the upper part of the storage unit 20, the upper surface in this example. Specifically, the gas discharge pipe 26 is connected to the storage unit 20 at a position above the water intake 21A of the drain pipe 21. A gas backpressure regulating valve 27 is provided in the gas discharge pipe 26. The gas backpressure regulating valve 27 adjusts the flow rate of the oxidant gas flowing through the gas discharge pipe 26 by adjusting the opening degree. Thereby, the pressure in the gas phase of the storage unit 20, the pressure in the oxidant gas outlet pipe 42, and the pressure in the fuel cell stack 10 are adjusted. And as a result, the gas backpressure regulating valve 27 adjusts the pressure of the oxidant gas discharged from the fuel cell stack 10 and sent to the storage unit 20.

[0038] When the pressure in the storage unit 20 increases, a situation may occur in which the stability of the operation is impaired. In order to avoid such a situation, the gas discharge pipe 26 and the gas backpressure regulating valve 27 are provided. The gas backpressure regulating valve 27 is electrically connected to the control device 100 and its opening and closing are controlled by the control device 100. The gas backpressure regulating valve 27 is a proportional valve in the present embodiment and can adjust the opening degree. The gas backpressure regulating valve 27 may be a motor valve or a proportional solenoid valve.

[0039] The gas backpressure regulating valve 27 is controlled based on the detection value detected by the pressure acquisition unit 44. In the present embodiment, a pressure acquisition unit 44 for acquiring the pressure in the oxidant gas outlet pipe 42 is provided. The pressure acquisition unit 44 detects the pressure of the oxidant gas flowing through the oxidant gas outlet pipe 42 and provides it to the control device 100. The control device 100 controls the gas backpressure regulating valve 27 based on the pressure information provided from the pressure acquisition unit 44. That is, the gas backpressure regulating valve 27 controls the opening degree based on the pressure of the oxidant gas acquired by the pressure acquisition unit 44. Specifically, the gas backpressure regulating valve 27 is controlled such that the opening degree increases when the pressure acquired by the pressure acquisition unit 44 increases, and the opening degree decreases when the pressure acquired by the pressure acquisition unit 44 decreases.

[0040] Specifically, the gas backpressure regulating valve 27 is controlled by a drive pulse signal that is PWM (Pulse Width Modulation) - converted and provided from the control device 100.

[0041] As an example, when the pressure acquired by the pressure acquisition unit 44 is a predetermined value desirable for operation, the gas backpressure regulating valve 27 is provided with a drive pulse signal having a duty ratio of 50% from the control device 100. And when the pressure acquired by the pressure acquisition unit 44 is greater than the predetermined value desirable for operation, the gas backpressure regulating valve 27 is provided with a drive pulse signal having a duty ratio greater than 50% from the control device 100, and the opening degree is increased. The duty ratio of the drive pulse signal increases as the difference between the pressure acquired by the pressure acquisition unit 44 and the above - mentioned predetermined value increases. On the other hand, when the pressure acquired by the pressure acquisition unit 44 is less than the predetermined value desirable for operation, the gas backpressure regulating valve 27 is provided with a drive pulse signal having a duty ratio less than 50% from the control device 100, and the opening degree is decreased.

[0042] In the present embodiment, the pressure acquisition unit 44 acquires the pressure in the oxidant gas outlet pipe 42, but the pressure detection position is not limited to this mode. The pressure acquisition unit 44 may detect the pressure of the oxidant gas, for example, inside the fuel cell stack 10, or may detect the pressure of the oxidant gas inside the storage unit 20.

[0043] The circulating water pipe 50 has a supply-side pipe 51 and a return-side pipe 52 that are respectively connected to the fuel cell stack 10 and the storage unit 20. The supply-side pipe 51 is connected to the storage unit 20 such that the upstream end opens into the liquid phase portion of the storage unit 20, and the downstream end is connected to the fuel cell stack 10. The return-side pipe 52 connects the upstream end to the fuel cell stack 10, receives the water component discharged from the fuel cell stack 10, and sends it to the storage unit 20. The water component received by the return-side pipe 52 from the fuel cell stack 10 may include the circulating water for cooling and humidification previously stored in the storage unit 20 and the generated water generated in the fuel cell stack 10. A pump 53 for circulating the water component is provided in the return-side pipe 52.

[0044] In FIG. 2, schematically, a state where a fuel gas inlet pipe 31 is connected to the upstream end of the fuel gas flow path 17, a state where an oxidant gas inlet pipe 41 is connected to the upstream end of the oxidant gas flow path 18, and a state where the supply-side pipe 51 is connected to the upstream end of the circulating water flow path 19 are shown. Although not shown, a fuel gas outlet pipe 32 is connected to the downstream end of the fuel gas flow path 17, an oxidant gas outlet pipe 42 is connected to the downstream end of the oxidant gas flow path 18, and the return-side pipe 52 is connected to the downstream end of the circulating water flow path 19.

[0045] The control device 100 is electrically connected to the compressor 43, the drain valve 22, the gas back pressure regulating valve 27, and the pressure acquisition unit 44, and controls the compressor 43, the drain valve 22, and the gas back pressure regulating valve 27 among them.

[0046] The control device 100 controls the compressor 43 according to the desired power generation output, and controls the supply amount of the oxidant gas from the compressor 43. Thereby, the control device 100 can control the inside of the fuel cell stack 10 to the operating pressure corresponding to the power generation output. For example, when the desired power generation output is 10 kW, the control device 100 may set the operating pressure to 10 kPaG. For example, when the desired power generation output is 100 kW, the control device 100 may set the operating pressure to 150 kPaG.

[0047] In addition, the control device 100 controls the drain valve 22 and the gas backpressure regulating valve 27. The control device 100 generates a drive pulse signal that is PWM-converted according to the pressure acquired by the pressure acquisition unit 44 and provides it to the gas backpressure regulating valve 27. Thereby, the control device 100 controls the opening degree of the gas backpressure regulating valve 27. As an example, when the pressure acquired by the pressure acquisition unit 44 is a predetermined value desirable for operation, the control device 100 generates a drive pulse signal with a duty ratio of 50%. When the pressure acquired by the pressure acquisition unit 44 is greater than the predetermined value, the control device 100 generates a drive pulse signal with a duty ratio greater than 50%. When the pressure acquired by the pressure acquisition unit 44 is less than the predetermined value, the control device 100 generates a drive pulse signal with a duty ratio less than 50%. Thereby, when the pressure acquired by the pressure acquisition unit 44 increases, the gas backpressure regulating valve 27 is controlled to increase the opening degree, and when the pressure acquired by the pressure acquisition unit 44 decreases, the gas backpressure regulating valve 27 is controlled to decrease the opening degree.

[0048] In addition, while the control device 100 controls the gas backpressure regulating valve 27 based on the pressure of the oxidant gas acquired by the pressure acquisition unit 44 as described above, the control device 100 also controls the opening and closing of the drain valve 22 based on the pressure of the oxidant gas acquired by the pressure acquisition unit 44. Specifically, when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 is equal to or higher than the first pressure threshold value, the control device 100 opens the drain valve 22. After the control device 100 opens the drain valve 22, when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 is equal to or lower than the second pressure threshold value, the control device 100 closes the drain valve 22. Thereby, when the pressure acquired by the pressure acquisition unit 44 increases, the drain valve 22 is controlled to open, and after it is opened, when the pressure acquired by the pressure acquisition unit 44 decreases, the drain valve 22 is controlled to close.

[0049] The first pressure threshold is a value greater than the second pressure threshold. The first pressure threshold varies in an appropriate value depending on the operating pressure. Therefore, the control device 100 determines the first pressure threshold according to the operating pressure set for the fuel cell stack 10. The higher the set operating pressure, the greater the pressure fluctuations are considered to be in response to changes in the valve opening or water level. And when the set operating pressure is high and the difference between the operating pressure and the first pressure threshold is small, a situation may occur where it becomes difficult to appropriately detect the drain valve opening timing. Considering this point, the first pressure threshold may be determined such that the difference between the operating pressure and the first pressure threshold becomes larger as the set operating pressure is higher. For example, the first pressure threshold may be determined to be the operating pressure + 10% (that is, the operating pressure × 1.10) in the entire operating pressure range. In this case, for example, the first pressure threshold when the operating pressure is 10 kPaG is 11.0 kPaG, and the first pressure threshold when the operating pressure is 150 kPaG is 165 kPaG.

[0050] Similarly, the control device 100 determines the second pressure threshold according to the operating pressure set for the fuel cell stack 10. The second pressure threshold may be determined such that the difference between the operating pressure and the second pressure threshold becomes larger as the set operating pressure is higher. For example, the second pressure threshold may be determined to be the operating pressure - 5% (that is, the operating pressure × 0.95) in the entire operating pressure range. In this case, for example, the first pressure threshold when the operating pressure is 10 kPaG is 9.5 kPaG, and the first pressure threshold when the operating pressure is 150 kPaG is 142.5 kPaG.

[0051] The difference between the operating pressure set for the fuel cell stack 10 and the second pressure threshold may be smaller than the difference between the operating pressure and the first pressure threshold. In this case, by closing the drain valve 22 earlier, it can be suppressed that the stability of the operation is impaired due to excessive pressure drop. Note that the second pressure threshold may be the same value as the operating pressure.

[0052] FIG. 3 is a diagram for explaining the relationship between the pressure of the oxidant gas discharged from the fuel cell stack 10 and the drain timing of the water component in the storage unit 20.

[0053] When the fuel cell system S1 starts power generation operation, generated water is produced in the fuel cell stack 10. A part of this generated water condenses and flows into the circulating water flow path 19 through the separators (14, 15), and can be stored in the storage unit 20 from the return side pipe 52. When the water level in the storage unit 20 rises due to the increase in the generated water, the gas flow path portion (gas phase portion) in the storage unit 20 gradually becomes narrower. And as the gas flow path portion (gas phase portion) in the storage unit 20 becomes narrower, the pressure in the gas flow path portion in the storage unit 20, the pressure in the oxidant gas outlet pipe 42, and the pressure in the fuel cell stack 10 increase.

[0054] When the pressure rises as described above, the opening degree of the gas back pressure regulating valve 27 is controlled in the direction of increasing. Thereby, the optimization of the pressure of the oxidant gas is achieved. On the other hand, if the rise in the water level continues, it becomes difficult to optimize the pressure of the oxidant gas by adjusting the opening degree of the gas back pressure regulating valve 27. And as shown in the gas pressure graph in the upper part of FIG. 3, the pressure in the gas flow path portion in the storage unit 20, the pressure in the oxidant gas outlet pipe 42, and the pressure in the fuel cell stack 10 increase. Here, when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 becomes larger than the first pressure threshold value Pth1, in this embodiment, as shown in the graph of the opening / closing state of the drain valve 22 in the lower part of FIG. 3, the drain valve 22 is opened ("T1" in FIG. 3).

[0055] In the example of FIG. 3, when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 continuously becomes larger than the first pressure threshold value Pth1 over the period Tc1, the drain valve 22 is opened. However, the drain valve 22 may be opened the moment the pressure of the oxidant gas acquired by the pressure acquisition unit 44 becomes larger than the first pressure threshold value Pth1.

[0056] When the drain valve 22 opens as described above, the water level in the storage section 20 drops, and the pressure in the storage section 20 changes toward the same level as during normal operation. When the water level drops and reaches the height of the water intake 21A of the drain pipe 21, the discharge of the water component stops, and in the present embodiment, the oxidant gas is discharged through the water intake 21A of the drain pipe 21. At this time, the pressure in the storage section 20 drops, and the pressure acquired by the pressure acquisition unit 44 decreases. At this time, the gas backpressure adjustment valve 27 is controlled in a direction to reduce the opening degree so that the pressure acquired by the pressure acquisition unit 44 returns to the set operating pressure. And at this time, when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 becomes equal to or less than the second pressure threshold value Pth2, the control device 100 closes the drain valve 22 ("T2" in FIG. 3). After that, the control returns to the pressure optimization control by the gas backpressure adjustment valve 27, and then, when the water level rises, the drain control is performed.

[0057] In the example of FIG. 3, when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 continuously becomes equal to or less than the second pressure threshold value Pth2 over the period Tc2, the drain valve 22 is closed. However, the drain valve 22 may be closed at the moment when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 becomes equal to or less than the second pressure threshold value Pth2.

[0058] In the present embodiment, since the water intake 21A is above the bottom surface of the storage section 20, when the water level drops to the position of the water intake 21A, the drain operation stops. Thereby, excessive discharge of the water component is avoided. And while suppressing excessive discharge of the water component, it becomes possible to appropriately detect the closing timing of the drain valve 22 based on the pressure (the timing when the pressure in the storage section 20 has sufficiently dropped). However, even when the water intake 21A is connected to the bottom surface of the storage section 20, the same operation as the operation described above can be performed.

[0059] FIG. 4 is a flowchart for explaining an example of the operation of the fuel cell system S1 according to the present embodiment, specifically, the control operation of the drain valve 22 during operation.

[0060] The operation of FIG. 4 starts together with an instruction to start operation. At this time, first, the control device 100 closes the drain valve 22 (step S41). Then, the control device 100 determines the operating pressure based on the set power generation output (step S42). Next, the control device 100 determines a first pressure threshold value and a second pressure threshold value (opening / closing threshold value) based on the determined operating pressure (step S43). Then, the control device 100 starts the supply of fuel gas, oxidant gas, and circulating water.

[0061] Next, the control device 100 acquires the pressure of the oxidant gas discharged from the fuel cell stack 10 from the pressure acquisition unit 44 (step S44). Next, the control device 100 determines whether or not the pressure of the oxidant gas acquired in step S44 is equal to or higher than the first pressure threshold value (step S45).

[0062] When the pressure of the oxidant gas does not exceed the first pressure threshold value in step S45 (when "NO" in step S45), the process returns to step S44, and the monitoring of the pressure comparison continues. When the pressure of the oxidant gas becomes equal to or higher than the first pressure threshold value in step S45 (when "YES" in step S45), the control device 100 opens the drain valve 22 (step S46).

[0063] After that, the control device 100 acquires the pressure of the oxidant gas discharged from the fuel cell stack 10 from the pressure acquisition unit 44, and determines whether or not it is equal to or lower than the second pressure threshold value (step S47). When the pressure of the oxidant gas is greater than the second pressure threshold value in step S47 (when "NO" in step S47), the process returns to step S46, and the monitoring of the pressure comparison continues. When the pressure of the oxidant gas becomes equal to or lower than the second pressure threshold value in step S47 (when "YES" in step S47), the control device 100 returns the process to step S41 and closes the drain valve 22 (step S46).

[0064] The fuel cell system S1 according to the first embodiment described above controls the opening and closing of the drain valve 22 based on the pressure of the oxidant gas discharged from the fuel cell stack 10 acquired by the pressure acquisition unit 44. Specifically, the fuel cell system S1 opens the drain valve 22 when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 becomes equal to or higher than the first pressure threshold. Then, after opening the drain valve 22, the fuel cell system S1 closes the drain valve 22 when the pressure of the oxidant gas acquired by the pressure acquisition unit 44 becomes equal to or lower than the second pressure threshold.

[0065] According to such a configuration, since the opening and closing of the drain valve 22 are performed according to the detection of the pressure acquisition unit 44, the complication of the structure and the complication of the process for opening and closing the drain valve 22 are suppressed. Further, by using the pressure as the determination value for opening and closing the drain valve 22, it is possible to suppress an error in the determination of opening and closing the drain valve 22 due to the inclination or acceleration / deceleration occurring in the fuel cell system S1. Therefore, the generated water increased in the fuel cell system can be appropriately discharged without complicating the fuel cell system.

[0066] Further, the first pressure threshold is determined according to the operating pressure of the fuel cell stack 10. The second pressure threshold is determined according to the operating pressure of the fuel cell stack 10. Thereby, the threshold for opening and closing the drain valve 22 is appropriately determined, and an appropriate drain operation according to the operating pressure can be performed.

[0067] Further, the gas backpressure adjustment valve 27 controls the opening degree based on the pressure of the oxidant gas acquired by the pressure acquisition unit 44. In this case, the sensor part serving as the reference for the operations of the drain valve 22 and the gas backpressure adjustment valve 27 is shared. Thereby, the complication of the configuration is effectively suppressed.

[0068] Further, the drain pipe 21 is provided such that its water intake 21A is located above the bottom surface of the storage unit 20. Thereby, excessive discharge of water components during draining is avoided. Further, by allowing the inflow of the oxidant gas into the water intake 21A, it is possible to appropriately detect the closing timing of the drain valve 22 based on the pressure while suppressing the excessive discharge of water components. <Second Embodiment> Next, the fuel cell system S2 according to the second embodiment will be described with reference to FIGS. 5 to 7. The same parts as those in the first embodiment among the constituent parts in this embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0069] As shown in FIG. 5, the fuel cell system S2 includes a duty ratio acquisition unit 101 that acquires the duty ratio of a drive pulse signal for the gas back pressure adjustment valve 27. In this embodiment, the duty ratio acquisition unit 101 is configured as a part of the control device 100. Since the control device 100 generates a drive pulse signal having a determined duty ratio, the duty ratio acquisition unit 101 acquires information on the duty ratio within the control device 100. Then, the control device 100 controls the opening and closing of the drain valve 22 based on the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101.

[0070] Specifically, the control device 100 opens the drain valve 22 when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 becomes equal to or higher than a first duty threshold. When the amount of generated water stored in the storage unit 20 increases, the pressure inside the fuel cell stack 10 rises. At this time, the control device 100 generates a drive pulse signal with a large duty ratio so that the opening degree of the gas back pressure adjustment valve 27 increases. That is, in this embodiment, a pressure increase is detected based on the generation of a drive pulse signal with a large duty ratio, and the drain timing is determined in response to the pressure increase. As a result, the water level is optimized, and the pressure (operating pressure) of the oxidant gas in the fuel cell stack 10 is optimized.

[0071] Further, after opening the drain valve 22, the control device 100 closes the drain valve 22 when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 becomes equal to or lower than a second duty threshold.

[0072] The first duty threshold is a value greater than the second duty threshold. The first duty threshold varies with the operating pressure. Therefore, the control device 100 determines the first duty threshold according to the operating pressure set for the fuel cell stack 10. The greater the set operating pressure, the greater the pressure fluctuations are considered to be in response to changes in the valve opening and water level. If the first duty threshold is a large value when the set operating pressure is high, there is a possibility that the drain valve opening timing may undesirably lag. Considering this point, the first duty threshold may be determined such that the greater the set operating pressure, the smaller the first duty threshold. For example, when the operating pressure is 10 kPaG and the first duty threshold is set to 90%, the first duty threshold when the operating pressure is 150 kPaG may be set to 80%.

[0073] Similarly, the control device 100 determines the second duty threshold according to the operating pressure set for the fuel cell stack 10. The second duty threshold may be determined such that the greater the set operating pressure, the greater the second duty threshold. For example, when the operating pressure is 10 kPaG and the second duty threshold is set to 45%, the second duty threshold when the operating pressure is 150 kPaG may be set to 48%.

[0074] The difference between the duty ratio (50%) of the drive pulse signal for maintaining the opening of the gas backpressure regulating valve 27 and the second duty threshold may be smaller than the difference between the 50% duty ratio and the first duty threshold. In this case, by closing the drain valve 22 earlier, it is possible to suppress the deterioration of the operating stability due to excessive pressure drop. Note that the second duty threshold may be 50%.

[0075] FIG. 6 is a diagram for explaining the relationship between the duty ratio of the drive pulse signal for the gas backpressure regulating valve 27 and the drain timing of the water component stored in the storage section 20. That is, it is a diagram for explaining the control of the drain valve 22 by the control device 100.

[0076] When the water level in the storage unit 20 rises due to an increase in the generated water produced by the fuel cell stack 10, the gas flow passage portion (gas phase portion) in the storage unit 20 gradually becomes narrower. As the gas flow passage portion (gas phase portion) in the storage unit 20 becomes narrower, the pressure in the gas flow passage portion in the storage unit 20, the pressure in the oxidant gas outlet pipe 42, and the pressure in the fuel cell stack 10 increase.

[0077] When the pressure rises as described above, the opening degree of the gas back pressure regulating valve 27 is controlled in the direction of increasing. Thereby, the optimization of the pressure of the oxidant gas is achieved. On the other hand, if the rise in the water level continues, it becomes difficult to optimize the pressure of the oxidant gas by adjusting the opening degree of the gas back pressure regulating valve 27. At this time, as shown in the range α of the state of the drive pulse signal shown in the upper part of FIG. 6, the duty ratio of the drive pulse signal for the gas back pressure regulating valve 27 continues to be significantly larger than normal (50%). The graph in the middle in the vertical direction in FIG. 6 shows the value of the duty ratio. Here, when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 becomes larger than the first duty threshold Dth1, as shown in the graph of the opening / closing state of the drain valve 22 in the lower part of FIG. 6, the drain valve 22 is opened ("T1’" in FIG. 6).

[0078] In the example of FIG. 6, when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 continuously becomes larger than the first duty threshold Dth1 over a predetermined period, the drain valve 22 is opened. However, the drain valve 22 may be opened at the moment when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 becomes equal to or greater than the first duty threshold Dth1.

[0079] When the drain valve 22 opens as described above, the water level in the storage unit 20 drops, and the pressure in the storage unit 20 changes toward the same level as during normal operation. When the water level drops and reaches the height of the water intake 21A of the drain pipe 21, the discharge of the water component stops, and in this embodiment, the oxidant gas is discharged through the water intake 21A of the drain pipe 21. At this time, the pressure in the storage unit 20 drops, and the pressure acquired by the pressure acquisition unit 44 decreases. Therefore, the gas backpressure adjustment valve 27 is provided with a drive pulse signal having a small duty ratio as shown in the range β of the state of the drive pulse signal shown in the upper part of FIG. 6, and the opening degree is controlled in a direction to reduce so that the pressure acquired by the pressure acquisition unit 44 returns to the set operating pressure. At this time, when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 becomes equal to or less than the second duty threshold Dth2, the control device 100 closes the drain valve 22 ("T2'" in FIG. 3). Thereafter, the control returns to the pressure optimization control by the gas backpressure adjustment valve 27, and then, when the water level rises, the drain is controlled.

[0080] In the example of FIG. 6, when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 continuously becomes equal to or less than the second duty threshold Dth2 over a predetermined period, the drain valve 22 is closed. However, the drain valve 22 may be closed at the moment when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit 101 becomes equal to or less than the second duty threshold Dth2.

[0081] FIG. 7 is a flowchart for explaining an operation of the fuel cell system S2 according to the second embodiment, specifically, an example of a control operation of the drain valve 22.

[0082] The operation in FIG. 7 starts together with an instruction to start operation. At this time, first, the control device 100 closes the drain valve 22 (step S71). Thereafter, the control device 100 determines the operating pressure based on the set power generation output (step S72). Next, the control device 100 determines the first duty threshold and the second duty threshold based on the determined operating pressure (step S73). Then, the control device 100 starts the supply of the fuel gas, the oxidant gas, and the circulating water.

[0083] Next, the control device 100 acquires the duty ratio of the drive pulse signal for the gas back pressure regulating valve 27 from the duty ratio acquisition unit 101 (step S74). Next, the control device 100 determines whether the duty ratio of the drive pulse signal acquired in step S74 is equal to or greater than the first duty threshold (step S75).

[0084] If the duty ratio does not exceed the first duty threshold in step S75 (if "NO" in step S75), the process returns to step S74, and the monitoring of the duty ratio comparison continues. If the duty ratio becomes equal to or greater than the first duty threshold in step S75 (if "YES" in step S75), the control device 100 opens the drain valve 22 (step S76).

[0085] Thereafter, the control device 100 acquires the duty ratio of the drive pulse signal from the duty ratio acquisition unit 101 and determines whether it is equal to or less than the second duty threshold (step S77). If the duty ratio is greater than the second duty threshold in step S77 (if "NO" in step S77), the process returns to step S76, and the monitoring of the duty ratio comparison continues. If the duty ratio becomes equal to or less than the second duty threshold in step S77 (if "YES" in step S77), the control device 100 returns the process to step S71 and closes the drain valve 22 (step S71).

[0086] The fuel cell system S2 according to the second embodiment described above controls the opening and closing of the drain valve 22 based on the duty ratio of the drive pulse signal for the gas back pressure regulating valve 27 acquired by the duty ratio acquisition unit 101. Specifically, the fuel cell system S1 opens the drain valve 22 when the duty ratio of the drive pulse signal becomes equal to or greater than the first duty threshold. Then, after opening the drain valve 22, the fuel cell system S1 closes the drain valve 22 when the duty ratio of the drive pulse signal becomes equal to or less than the second duty threshold.

[0087] According to such a configuration, since the opening and closing of the drain valve 22 are performed according to the drive pulse signal generated to control the gas back pressure regulating valve 27, the complication of the structure and the complication of the process for the opening and closing of the drain valve 22 are suppressed. Further, by using the control signal for the gas back pressure regulating valve 27 as the determination value for the opening and closing of the drain valve 22, it is possible to suppress an error in the determination of the opening and closing of the drain valve 22 due to the inclination or acceleration / deceleration occurring in the fuel cell system S2. Therefore, the generated water increased in the fuel cell system can be appropriately discharged without complicating the fuel cell system.

[0088] As described above, each embodiment has been explained. However, the above embodiments are presented as examples and are not intended to limit the scope of the invention. Such novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Other modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof. A part of the configuration of one embodiment can be applied to other embodiments. Such a configuration is also included in the scope and gist of the invention, and is included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0089] S1, S2... fuel cell systems, 10... fuel cell stack, Ce... single cell, 11... separator, 12... anode electrode, 13... cathode electrode, 14... anode electrode separator, 15... cathode electrode separator, 17... fuel gas flow path, 18... oxidant gas flow path, 19... circulating water flow path, 20... storage section, 21... drain pipe, 22... drain valve, 26... gas discharge pipe, 27... gas back pressure regulating valve, 30... fuel gas pipe, 31... fuel gas inlet pipe, 32... fuel gas outlet pipe, 40... oxidant gas pipe, 41... oxidant gas inlet pipe, 42... oxidant gas outlet pipe, 43... compressor, 44... pressure acquisition section, 50... circulating water pipe, 51... supply side pipe, 52... return side pipe, 53... pump, 100... control device, 101... duty ratio acquisition section

Claims

1. A fuel cell stack, a storage unit that stores a water component including circulating water supplied to the fuel cell stack and circulated from the fuel cell stack, and generated water generated in the fuel cell stack and discharged from the fuel cell stack, a gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage unit, a pressure acquisition unit that acquires the pressure of the gas discharged from the fuel cell stack, a drain pipe connected to the storage unit and allowing the water component discharged from the storage unit to flow therethrough, a drain valve provided in the drain pipe, and a control device that controls the opening and closing of the drain valve, wherein the control device controls the opening and closing of the drain valve based on the pressure of the gas acquired by the pressure acquisition unit. A fuel cell system.

2. The fuel cell system according to claim 1, wherein the control device opens the drain valve when the pressure of the gas acquired by the pressure acquisition unit is equal to or higher than a first pressure threshold value.

3. The fuel cell system according to claim 2, wherein the control device determines the first pressure threshold value according to the operating pressure of the fuel cell stack.

4. The fuel cell system according to any one of claims 1 to 3, wherein the control device closes the drain valve when the pressure of the gas acquired by the pressure acquisition unit becomes equal to or lower than a second pressure threshold value after opening the drain valve.

5. The fuel cell system according to claim 4, wherein the control device determines the second pressure threshold value according to the operating pressure of the fuel cell stack.

6. A fuel cell stack, a storage unit that stores a water component including circulating water supplied to the fuel cell stack and circulated from the fuel cell stack, and generated water generated in the fuel cell stack and discharged from the fuel cell stack, a gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage unit, a pressure acquisition unit that acquires the pressure of the gas discharged from the fuel cell stack, a gas backpressure adjustment valve that adjusts the pressure of the gas sent to the storage unit based on a drive pulse signal whose duty ratio can be changed according to the pressure of the gas acquired by the pressure acquisition unit, a duty ratio acquisition unit that acquires the duty ratio of the drive pulse signal for the gas backpressure adjustment valve, a drain pipe connected to the storage unit and allowing the water component discharged from the storage unit to flow therethrough, a drain valve provided in the drain pipe, A control device that controls the opening and closing of the drain valve, and, Based on the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit, the control device controls the opening and closing of the drain valve, a fuel cell system.

7. When the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit is equal to or greater than a first duty threshold, the control device opens the drain valve, the fuel cell system according to claim 6.

8. The control device determines the first duty threshold according to the operating pressure of the fuel cell stack, the fuel cell system according to claim 7.

9. After opening the drain valve, when the duty ratio of the drive pulse signal acquired by the duty ratio acquisition unit is equal to or less than a second duty threshold, the control device closes the drain valve, the fuel cell system according to any one of claims 6 to 8.

10. The control device determines the second duty threshold according to the operating pressure of the fuel cell stack, the fuel cell system according to claim 9.

11. Further comprising a gas back pressure regulating valve that regulates the pressure of the gas discharged from the fuel cell stack, Based on the pressure of the gas acquired by the pressure acquisition unit, the gas back pressure regulating valve controls the opening degree, the fuel cell system according to claim 1.

12. The drain pipe is provided such that the water intake is located above the bottom surface of the storage portion, the fuel cell system according to claim 1 or 6.

13. A fuel cell stack and, A storage portion that stores a water component including the circulating water supplied to the fuel cell stack and circulated from the fuel cell stack, and the generated water generated in the fuel cell stack and discharged from the fuel cell stack, A gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage portion, A drain pipe connected to the storage portion and allowing the water component discharged from the storage portion to flow therethrough, and, A drain valve provided in the drain pipe, a control method for a fuel cell system, comprising: A pressure acquisition step of acquiring the pressure of the gas discharged from the fuel cell stack, A control step of controlling the opening and closing of the drain valve based on the pressure of the gas acquired in the pressure acquisition step, a control method for a fuel cell system.

14. A fuel cell stack and, A storage unit that stores a water component including circulated water supplied to the fuel cell stack and circulated from the fuel cell stack, and generated water generated in the fuel cell stack and discharged from the fuel cell stack; A gas outlet pipe that sends the gas discharged from the fuel cell stack to the storage unit; A pressure acquisition unit that acquires the pressure of the gas discharged from the fuel cell stack; A gas backpressure adjustment valve that adjusts the pressure of the gas sent to the storage unit based on a drive pulse signal whose duty ratio can be changed according to the pressure of the gas acquired by the pressure acquisition unit; A drain pipe connected to the storage unit and through which the water component discharged from the storage unit flows; A drain valve provided in the drain pipe, and a control method for a fuel cell system comprising: A duty ratio acquisition step of acquiring the duty ratio of the drive pulse signal for the gas backpressure adjustment valve; A control step of controlling the opening and closing of the drain valve based on the duty ratio of the drive pulse signal acquired in the duty ratio acquisition step. A control method for a fuel cell system.

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