Fuel cell system and control method for a fuel cell system

Abstract

Provided is a fuel cell system capable of accurately determining the presence or absence of cross leakage, and a control method for a fuel cell system. The fuel cell system includes a plurality of fuel cell stacks, anode and cathode piping, anode discharge valves, cathode supply and discharge valves, anode and cathode pressure sensors, and a control device. The control device determines the presence or absence of abnormal permeation of fuel gas or oxidant gas between the anode and the cathode, i.e., cross leakage, based on the pressure difference between the pressure of the fuel gas and the pressure of the oxidant gas, or the change in the pressure difference, detected by the anode and cathode pressure sensors, in a state in which power generation by the plurality of fuel cell stacks is stopped.

Description

[0001] This application is based on Japanese Patent Application No. 2021-045534 filed on March 19, 2021, the content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to a fuel cell system and a control method of a fuel cell system. BACKGROUND

[0003] In the past, there has been known a fuel cell system which determines the presence or absence of a crossover leakage of a fuel or an oxidizer between an anode and a cathode, for example, based on a change in pressure in an anode system which is sealed at the time of power generation stop (for example, refer to Japanese Patent Application Publication No. 2012-133997). SUMMARY

[0004] However, in the above-described fuel cell system, since the pressure in the anode system is merely detected, in the case where there is a leak in a pipe or the like in the anode system, for example, there is a problem that the presence or absence of the crossover leakage cannot be determined with good accuracy.

[0005] The present application provides a fuel cell system and a control method of a fuel cell system which can determine the presence or absence of a crossover leakage with good accuracy.

[0006] To solve the above problem and achieve the above object, the present application adopts the following aspect.

[0007] (1) A fuel cell system according to an aspect of the present application includes: a fuel cell that generates electricity using a fuel supplied to an anode and an oxidizer supplied to a cathode; an anode opening and closing portion that switches opening and closing of an anode flow path that communicates with the anode and through which the fuel flows; a cathode opening and closing portion that switches opening and closing of a cathode flow path that communicates with the cathode and through which the oxidizer flows; an anode pressure detection portion that detects pressure of the fuel in the anode flow path; a cathode pressure detection portion that detects pressure of the oxidizer in the cathode flow path; and a control portion that controls switching of opening and closing of each of the anode opening and closing portion and the cathode opening and closing portion, and determines the presence or absence of a crossover leakage of the fuel or the oxidizer between the anode and the cathode based on a pressure difference between the pressure of the fuel and the pressure of the oxidizer detected by the anode pressure detection portion and the cathode pressure detection portion or a change in the pressure difference in a stopped state of electricity generation of the fuel cell.

[0008] (2) The fuel cell system according to (1) above includes a fuel supply section that supplies the fuel to the anode flow path, and an oxidizer supply section that supplies the oxidizer to the cathode flow path, and the control section performs processing of determining the presence or absence of the cross-over leakage based on the pressure difference or the change in the pressure difference in a state where the anode shut-off section is set to the open state, the cathode shut-off section is set to the closed state, and the supply of the fuel by the fuel supply section is performed after power generation using the fuel and the oxidizer remaining inside the fuel cell is executed by stopping the supply of the fuel by the fuel supply section and the supply of the oxidizer by the oxidizer supply section.

[0009] (3) The fuel cell system according to (1) or (2) above includes a plurality of the fuel cells, a plurality of the anode shut-off sections, a plurality of the cathode shut-off sections, a plurality of the anode pressure detection sections, and a plurality of the cathode pressure detection sections, and the control section performs processing of determining the presence or absence of the cross-over leakage based on the pressure difference or the change in the pressure difference for each of the plurality of fuel cells in a stopped state of power generation of the plurality of fuel cells, and setting the anode shut-off section and the cathode shut-off section corresponding to the fuel cell determined to have the cross-over leakage to the closed state and executing power generation of the fuel cell determined to have no cross-over leakage when power generation of at least any one of the plurality of fuel cells is executed.

[0010] (4) The fuel cell system according to (3) above includes a fuel supply section that supplies the fuel to the anode flow path of the plurality of fuel cells, and an oxidizer supply section that supplies the oxidizer to the cathode flow path of the plurality of fuel cells, and the control section performs processing of setting power generation execution and power generation stop of each of the plurality of fuel cells according to an output demand, and determining the presence or absence of the cross-over leakage based on the pressure difference or the change in the pressure difference for each of the plurality of fuel cells in a state where the plurality of anode shut-off sections are set to the open state, the plurality of cathode shut-off sections are set to the closed state, and the supply of the fuel by the fuel supply section is performed after power generation using the fuel and the oxidizer remaining inside each of the plurality of fuel cells is executed by stopping the supply of the fuel by the fuel supply section and the supply of the oxidizer by the oxidizer supply section.

[0011] (5) In a control method of a fuel cell system according to an aspect of the present application, the fuel cell system includes: a fuel cell that generates electricity using fuel supplied to an anode and oxidant supplied to a cathode; an anode opening / closing portion that communicates with the anode and switches opening and closing of an anode flow path through which the fuel flows; a cathode opening / closing portion that communicates with the cathode and switches opening and closing of a cathode flow path through which the oxidant flows; an anode pressure detection portion that detects pressure of the fuel in the anode flow path; a cathode pressure detection portion that detects pressure of the oxidant in the cathode flow path; and a control portion that controls switching of opening and closing of each of the anode opening / closing portion and the cathode opening / closing portion. The control method of the fuel cell system includes the step of determining, by the control portion, presence or absence of cross leakage of the fuel or the oxidant between the anode and the cathode based on a pressure difference between the pressure of the fuel and the pressure of the oxidant detected by the anode pressure detection portion and the cathode pressure detection portion or a change in the pressure difference in a state where electricity generation by the fuel cell is stopped.

[0012] According to the aspect (1) described above, by providing the control portion that determines presence or absence of cross leakage based on the pressure of the fuel and the pressure of the oxidant detected by the anode pressure detection portion and the cathode pressure detection portion, it is possible to improve accuracy of determination of cross leakage. As compared with a case where cross leakage is determined based on only the pressure of the anode or the pressure of the cathode, for example, it is possible to exclude leakage in a pipe or the like, and thus it is possible to accurately determine abnormal permeation of the fuel or the oxidant between the anode and the cathode.

[0013] In the aspect (2) described above, by providing the control portion that determines presence or absence of cross leakage after performing electricity generation using the fuel and the oxidant remaining in the fuel cell, it is possible to easily detect the pressure difference between the pressure of the fuel and the pressure of the oxidant detected by the anode pressure detection portion and the cathode pressure detection portion.

[0014] In the aspect (3) described above, it is possible to prevent leakage of the fuel or the oxidant from the fuel cell determined to have cross leakage to another fuel cell (i.e., a fuel cell determined to have no cross leakage), and it is possible to continue appropriate electricity generation.

[0015] In the aspect (4) described above, even in a case where there are a fuel cell in which electricity generation is performed and a fuel cell in which electricity generation is stopped, it is possible to determine presence or absence of cross leakage for a plurality of fuel cells at the same time, and thus it is possible to improve efficiency of supply control of the fuel and the oxidant for the plurality of fuel cells.

[0016] According to the aspect (5) described above, by determining the presence or absence of cross leakage based on the pressures of the fuel and the oxidizer detected by the anode pressure detection section and the cathode pressure detection section, it is possible to improve the determination accuracy of cross leakage. As compared with a case where cross leakage is determined based on only the pressure of the anode or the pressure of the cathode, for example, it is possible to exclude leakage in the piping or the like, and thus it is possible to accurately determine abnormal permeation of the fuel or the oxidizer between the anode and the cathode. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a diagram schematically showing the structure of a fuel cell system in an embodiment of the present application.

[0018] Figure 2 FIG. 2 is a flowchart showing the operation of the fuel cell system in the embodiment of the present application.

[0019] Figure 3 FIG. 3 is a diagram showing an example of the temporal change in the fuel supply and the pressure difference between the anode and the cathode at the time of cross leakage determination of the fuel cell system in the embodiment of the present application. DETAILED DESCRIPTION

[0020] Hereinafter, a fuel cell system 10 of an embodiment of the present application will be described with reference to the drawings.

[0021] Figure 1 FIG. 1 is a diagram schematically showing the structure of the fuel cell system 10 in the embodiment.

[0022] As shown in FIG. 1, the fuel cell system 10 of the embodiment is provided with a plurality of fuel cell stacks 11, a gas pump (oxidizer supply section) 13, a fuel supply section 15, a plurality of valves 17, a plurality of pressure sensors 19, and a control device 21. Figure 1

[0023] The plurality of fuel cell stacks 11 is provided with a first fuel cell stack 31 and a second fuel cell stack 33, for example. Each fuel cell stack 11 is a solid polymer fuel cell, for example. The solid polymer fuel cell is provided with a plurality of fuel cell elements stacked, and a pair of end plates sandwiching the stack of the plurality of fuel cell elements from both sides in the stacking direction. The fuel cell element is provided with an electrolyte electrode structure and a pair of separators sandwiching the electrolyte electrode structure. The electrolyte electrode structure is provided with a solid polymer electrolyte membrane 11a and a fuel electrode 11b and an oxygen electrode 11c sandwiching the solid polymer electrolyte membrane 11a. The solid polymer electrolyte membrane 11a is provided with a cation exchange membrane or the like. The fuel electrode (anode) 11b is provided with an anode catalyst and a gas diffusion layer or the like. The oxygen electrode (cathode) 11c is provided with a cathode catalyst and a gas diffusion layer or the like.

[0024] ​Each fuel cell stack 11 generates electricity by a catalyst reaction between hydrogen-containing fuel gas supplied from the fuel supply section 15 to the anode 11b and oxidant gas such as air containing oxygen supplied from the gas pump 13 to the cathode 11c.

[0025] The gas pump 13 is connected to a cathode pipe (cathode flow path) 41 that communicates with the cathodes 11c of the respective fuel cell stacks 11. The gas pump 13 supplies oxidant gas circulating in the cathode pipe 41 to the cathodes 11c of the respective fuel cell stacks 11.

[0026] The fuel supply section 15 is connected to an anode pipe (anode flow path) 43 that communicates with the anodes 11b of the respective fuel cell stacks 11. The fuel supply section 15 supplies fuel gas circulating in the anode pipe 43 to the anodes 11b of the respective fuel cell stacks 11.

[0027] The fuel supply section 15 has, for example, a fuel tank 15a that receives and stores fuel supplied from an external mobile or stationary fuel filling device, and an ejector 15b or the like for fuel circulation. The ejector 15b is provided, for example, between the fuel tank 15a and the anodes 11b of the plurality of fuel cell stacks 11, and mixes at least a portion of unreacted fuel gas discharged from the plurality of anodes 11b with fuel gas supplied from the fuel tank 15a to supply the fuel gas again to the plurality of anodes 11b.

[0028] The plurality of valves 17 has, for example, anode discharge valves (anode opening / closing sections) 51 provided to the respective fuel cell stacks 11, cathode supply valves (cathode opening / closing sections) 53 and cathode discharge valves (cathode opening / closing sections) 55, and a vent valve 57.

[0029] The anode discharge valve 51 is provided to the anode pipe 43 on the discharge side (outlet side) of the anode 11b of the respective fuel cell stacks 11. The anode discharge valve 51 is opened and closed by the control device 21, and adjusts the flow rate of fuel gas from the anode pipe 43 to the anode 11b of the respective fuel cell stacks 11.

[0030] The anode discharge valve 51 has, for example, a first anode discharge valve 51a of the first fuel cell stack 31 and a second anode discharge valve 51b of the second fuel cell stack 33.

[0031] The cathode supply valve 53 is provided to the cathode pipe 41 on the supply side (inlet side) of the cathode 11c of the respective fuel cell stacks 11. The cathode discharge valve 55 is provided to the cathode pipe 41 on the discharge side (outlet side) of the cathode 11c of the respective fuel cell stacks 11. The cathode supply valve 53 and the cathode discharge valve 55 are each opened and closed by the control device 21, and switch the sealing and opening of the cathode pipe 41.

[0032] The cathode supply valve 53 includes, for example, a first cathode supply valve 53a of the first fuel cell stack 31 and a second cathode supply valve 53b of the second fuel cell stack 33. The cathode discharge valve 55 includes, for example, a first cathode discharge valve 55a of the first fuel cell stack 31 and a second cathode discharge valve 55b of the second fuel cell stack 33.

[0033] The exhaust valve 57 is provided in the anode pipe 43 on the downstream side of the plurality of anode discharge valves 51. The exhaust valve 57 is opened and closed by the control device 21, and discharges water generated by power generation of each fuel cell stack 11 and nitrogen that has passed through the cathode 11c of each fuel cell stack 11 after passing through the anode 11b from the anode pipe 43.

[0034] The plurality of pressure sensors 19 include, for example, an anode pressure sensor (anode pressure detection portion) 61 and a cathode pressure sensor (cathode pressure detection portion) 63 of each fuel cell stack 11.

[0035] The anode pressure sensor 61 is provided in the anode pipe 43 on the supply side (inlet side) of the anode 11b of each of the plurality of fuel cell stacks 11. The anode pressure sensor 61 detects the pressure of the fuel gas flowing in the anode pipe 43 and outputs a signal of the detected value of the pressure. The anode pressure sensor 61 includes, for example, a first anode pressure sensor 61a of the first fuel cell stack 31 and a second anode pressure sensor 61b of the second fuel cell stack 33. The cathode pressure sensor 63 is provided in the cathode pipe 41 on the supply side (inlet side) of the cathode 11c of each of the plurality of fuel cell stacks 11. The cathode pressure sensor 63 detects the pressure of the oxidant gas flowing in the cathode pipe 41 and outputs a signal of the detected value of the pressure. The cathode pressure sensor 63 includes, for example, a first cathode pressure sensor 63a of the first fuel cell stack 31 and a second cathode pressure sensor 63b of the second fuel cell stack 33.

[0036] The control device 21 comprehensively controls the operation of the fuel cell system 10, for example.

[0037] The control device 21 is a software function portion that functions by executing a prescribed program using a processor such as a CPU (Central Processing Unit), for example. The software function portion is an ECU (Electronic Control Unit) that includes a processor such as a CPU, a ROM (ReadOnly Memory) that stores a program, a RAM (Random Access Memory) that temporarily stores data, and an electronic circuit such as a timer. At least a portion of the control device 21 can also be an integrated circuit such as an LSI (Large Scale Integration).

[0038] The control device 21 controls the opening and closing of the plurality of valves 17, for example, in accordance with various operation modes of the fuel cell system 10.

[0039] The control device 21 determines the presence or absence of cross leakage of each fuel cell stack 11, for example, based on a signal of a detected value of pressure received from the anode pressure sensor 61 and the cathode pressure sensor 63 of each of the plurality of fuel cell stacks 11. Cross leakage is an abnormality of permeation of fuel gas or oxidant gas between the anode 11b and the cathode 11c of each fuel cell stack 11, and is a state in which excessive permeation exceeding a prescribed level of permeation of fuel gas or oxidant gas generated in a normal solid polymer electrolyte membrane 11a occurs due to an abnormality such as breakage of the solid polymer electrolyte membrane 11a or the like.

[0040] Next, the control method of the fuel cell system 10 in the embodiment, that is, the control operation performed by the control device 21 will be described.

[0041] Figure 2 is a flowchart showing the operation of the fuel cell system 10 in the embodiment.

[0042] Figure 2 The series of processes shown in steps S01 to S10 are executed when the power generation of the fuel cell system 10 is stopped, for example, in a case where the ignition switch of a vehicle on which the fuel cell system 10 is mounted is set to off.

[0043] First, in step S01, the control device 21 performs low-oxygen power generation in which power generation is continued using fuel gas remaining in each fuel cell stack 11 in a state in which the supply of fuel gas by the fuel supply section 15 is stopped and the output of the gas pump 13 is reduced. Low-oxygen power generation is power generation in a state in which the stoichiometric ratio of oxygen of oxidant gas (= oxygen supply amount / theoretical oxygen consumption amount corresponding to the power generation current) is set to a value (for example, 1 or the like) lower than a reference value at the time of normal power generation. In the low-oxygen power generation, each of the anode exhaust valves 51a, 51b, each of the cathode supply valves 53a, 53b, and each of the cathode exhaust valves 55a, 55b is set to an open state (ON) as shown in Table 1 below.

[0044]

Table 1

[0045]

[0046] Next, in step S02, the control device 21 executes a stop process for continuing power generation using the fuel gas and the oxidant gas (residual gas) remaining in each fuel cell stack 11 by stopping the supply of the oxidant gas by the gas pump 13. In the stop process, as shown in Table 1 above, each anode exhaust valve 51a, 51b, each cathode supply valve 53a, 53b, and each cathode exhaust valve 55a, 55b are set to the ON state as with the low-oxygen power generation.

[0047] Next, in step S03, the control device 21 sets each cathode supply valve 53a, 53b and each cathode exhaust valve 55a, 55b to the OFF state after the oxidant gas remaining in each fuel cell stack 11 is consumed. The control device 21 detects whether the oxidant gas remaining in each fuel cell stack 11 is consumed based on the detected value of the power generation voltage (or power generation electric power) of each fuel cell stack 11.

[0048] Next, in step S04, the control device 21 starts the supply of the fuel gas by the fuel supply portion 15. In this case, as with the cross-leak inspection shown in Table 1 above, each cathode supply valve 53a, 53b and each cathode exhaust valve 55a, 55b are set to the OFF state, and each anode exhaust valve 51a, 51b is set to the ON state.

[0049] Next, in step S05, the control device 21 detects the pressure difference, i.e., the difference between the pressure of the fuel gas in the anode 11b and the pressure of the oxidant gas in the cathode 11c, based on the signals of the detected values of the pressures output from the anode pressure sensor 61 and the cathode pressure sensor 63 with respect to the first fuel cell stack 31 and the second fuel cell stack 33.

[0050] Next, in step S06, the control device 21 determines the presence or absence of the cross-leak of each fuel cell stack 11 based on the pressure difference or the change in the pressure difference detected in step S05. In the case where the determination result is "Yes", i.e., in the case where the cross-leak occurs in at least any one of the fuel cell stacks 11, the control device 21 causes the process to proceed to step S08. On the other hand, in the case where the determination result is "No", i.e., in the case where the cross-leak does not occur in any of the fuel cell stacks 11, the control device 21 causes the process to proceed to step S07.

[0051] Figure 3 FIG. 4 is a diagram showing an example of the time change in the fuel supply and the pressure difference between the anode 11b and the cathode 11c at the time of cross-leak determination of the fuel cell system 10 in the embodiment.

[0052] As Figure 3As shown, if the supply of fuel gas by the fuel supply section 15 is started at the time of the cross leakage check, the pressure difference between the anode 1 lb and the cathode 11c increases, for example, from the pressure difference ΔP1 at time tl toward the pressure difference ΔP2 at time t2. Also, after the time t2 at which the supply of fuel gas by the fuel supply section 15 is stopped, the pressure difference between the anode 1 lb and the cathode 11c changes in a decreasing tendency. The control device 21 determines that the cross leakage has occurred, for example, in the case where the decrease in the pressure difference after the time t2 is larger than the change at normal times.

[0053] Next, in step S07, the control device 21 permits normal power generation at the next start of the fuel cell system 10 and causes the process to proceed to the end.

[0054] In the normal power generation at the next start, the control device 21 switches and selects the normal power generation: low load (partial operation) or the normal power generation: high load (full operation) shown in Table 1 above in accordance with the output demand.

[0055] For example, in the normal power generation: low load (partial operation) selected in the case where the output demand is less than a prescribed threshold value, the first anode discharge valve 51a, the first cathode supply valve 53a, and the first cathode discharge valve 55a are set to the ON state, and the second anode discharge valve 51b, the second cathode supply valve 53b, and the second cathode discharge valve 55b are set to the OFF state, whereby power generation by only the first fuel cell stack 31 is executed.

[0056] For example, in the normal power generation: high load (full operation) selected in the case where the output demand is equal to or more than the prescribed threshold value, each of the anode discharge valves 51a, 51b, each of the cathode supply valves 53a, 53b, and each of the cathode discharge valves 55a, 55b is set to the ON state, whereby power generation by the first fuel cell stack 31 and the second fuel cell stack 33 is executed.

[0057] Next, in step S08, the control device 21 determines whether cross leakages have occurred in all of the plurality of fuel cell stacks 11.

[0058] In the case where the determination result is "Yes", the control device 21 causes the process to proceed to step S10. On the other hand, in the case where the determination result is "No", the control device 21 causes the process to proceed to step S09.

[0059] Next, in step S09, the control device 21 permits partial normal power generation at the next start of the fuel cell system 10 in which only the normal fuel cell stacks 11 (i.e., the fuel cell stacks 11 in which it is determined that no cross leakage has occurred) of the plurality of fuel cell stacks 11 are started, and notifies the user of this setting. Then, the process is caused to proceed to the end.

[0060] During the partial normal power generation at the next startup, control device 21, while only starting the first fuel cell stack 31, sets the first anode discharge valve 51a, the first cathode supply valve 53a, and the first cathode discharge valve 55a to the open state (ON), and sets the second anode discharge valve 51b, the second cathode supply valve 53b, and the second cathode discharge valve 55b to the closed state (OFF), as shown in Table 1 above for partial normal power generation. Control device 21 increases the power generation of the first fuel cell stack 31 as needed to meet output requirements. For example, if control device 21 determines that there is cross-leakage in the second fuel cell stack 33 and sets the startup of the second fuel cell stack 33 as impermissible, thus failing to meet output requirements, it increases the power generation of the first fuel cell stack 31 to meet output requirements.

[0061] Additionally, in step S10, the control device 21 sets the startup of all fuel cell stacks 11 to be disabled during the next startup of the fuel cell system 10 and notifies the user of this setting. Then, the process ends.

[0062] As described above, according to the embodiment of the fuel cell system 10 and the control method of the fuel cell system 10, the presence or absence of cross-leakage is determined based on the pressure of fuel gas and the pressure of oxidant gas detected by the anode pressure sensor 61 and the cathode pressure sensor 63, thereby improving the accuracy of cross-leakage determination. Compared with cases where cross-leakage is determined solely based on the pressure of the anode 11b or the cathode 11c, leaks in piping, etc., can be excluded, thereby enabling accurate determination of abnormal permeation of fuel gas or oxidant gas between the anode 11b and the cathode 11c.

[0063] By determining the presence or absence of cross-leakage after power generation utilizing the fuel gas and oxidant gas remaining inside the fuel cell stack 11, the pressure difference between the fuel gas pressure and the oxidant gas pressure detected by the anode pressure sensor 61 and the cathode pressure sensor 63 can be easily detected.

[0064] By disallowing the start-up of fuel cell stack 11 that is determined to have cross-leakage during the next start-up of fuel cell system 10, it is possible to prevent fuel gas or oxidant gas from fuel cell stack 11 that is determined to have cross-leakage to other fuel cell stacks 11 (i.e. fuel cell stacks 11 that are determined not to have cross-leakage) and to continue to generate electricity appropriately.

[0065] (Modified Example)

[0066] Hereinafter, variations of the embodiments will be described. It should be noted that the same reference numerals are used for the parts that are the same as those in the embodiments described above, and the descriptions are omitted or simplified.

[0067] In the above-described embodiment, the anode exhaust valve 51 provided to each fuel cell stack 11 is provided, but the present application is not limited thereto. For example, a supply valve controlled to be opened and closed can be provided in place of or in addition to the anode exhaust valve 51 on the inlet side of the anode 11b of each fuel cell stack 11.

[0068] In the above-described embodiment, the open state (ON) of the exhaust valve 57 can be controlled at least in conjunction with the open state (ON) of the first anode exhaust valve 51a or the second anode exhaust valve 51b.

[0069] In the above-described embodiment, the opening and closing of the plurality of valves 17 of each fuel cell stack 11 at the time of cross leakage determination can be simultaneously set in all of the plurality of fuel cell stacks 11. In this case, even in a case where, for example, there is a fuel cell stack 11 in which power generation is executed and a fuel cell stack 11 in which power generation is stopped, it is possible to simultaneously determine the presence or absence of cross leakage for the plurality of fuel cell stacks 11, and it is possible to improve the efficiency of the supply control of the fuel gas and the oxidant gas for the plurality of fuel cell stacks 11.

[0070] The embodiments of the present application are suggested as examples, and are not intended to limit the scope of the application. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the application. These embodiments, variations thereof, and the scope of the application, are encompassed by the scope and spirit of the application, and are also encompassed by the scope of the application and equivalents thereof described in the technical solution.

Claims

1. A fuel cell system characterized by comprising: a fuel cell that generates electricity using a fuel supplied to an anode and an oxidizing agent supplied to a cathode; an anode opening and closing portion that switches opening and closing of an anode flow path that communicates with the anode and through which the fuel flows; a cathode opening and closing portion that switches opening and closing of a cathode flow path that communicates with the cathode and through which the oxidizing agent flows; an anode pressure detection portion that detects a pressure of the fuel in the anode flow path; a cathode pressure detection portion that detects a pressure of the oxidizing agent in the cathode flow path; a control portion that controls switching of opening and closing of each of the anode opening and closing portion and the cathode opening and closing portion, and determines presence or absence of crossover leakage of the fuel or the oxidizing agent between the anode and the cathode based on a pressure difference between the pressure of the fuel and the pressure of the oxidizing agent detected by the anode pressure detection portion and the cathode pressure detection portion or a change in the pressure difference in a state where generation of electricity by the fuel cell is stopped; a fuel supply portion that supplies the fuel to the anode flow path; and an oxidizing agent supply portion that supplies the oxidizing agent to the cathode flow path, the control portion performs processing of: after performing generation of electricity using the fuel and the oxidizing agent remaining inside the fuel cell by stopping supply of the fuel by the fuel supply portion and supply of the oxidizing agent by the oxidizing agent supply portion, in a state where the anode opening and closing portion is set to an open state and the cathode opening and closing portion is set to a closed state and supply of the fuel by the fuel supply portion is performed, determining presence or absence of the crossover leakage based on the pressure difference or the change in the pressure difference.

2. The fuel cell system according to claim 1, characterized by comprising: a plurality of the fuel cells; a plurality of the anode opening and closing portions; a plurality of the cathode opening and closing portions; a plurality of the anode pressure detection portions; and a plurality of the cathode pressure detection portions, the control portion performs processing of: determining presence or absence of the crossover leakage based on the pressure difference or the change in the pressure difference for each of the plurality of fuel cells in a state where generation of electricity by the plurality of fuel cells is stopped, when performing generation of electricity by at least any one of the plurality of fuel cells, setting the anode opening and closing portion and the cathode opening and closing portion corresponding to the fuel cell determined to have the crossover leakage to a closed state, and performing generation of electricity by the fuel cell determined to have no crossover leakage.

3. The fuel cell system according to claim 2, characterized by comprising: a fuel supply portion that supplies the fuel to the anode flow path of the plurality of fuel cells; and an oxidizing agent supply portion that supplies the oxidizing agent to the cathode flow path of the plurality of fuel cells, the control portion performs processing of: setting generation of electricity by each of the plurality of fuel cells and stopping of generation of electricity according to an output demand, and ​ ​ ​ after performing power generation using the fuel and the oxidizer remaining inside each of the plurality of fuel cells by stopping the supply of the fuel by the fuel supply section and the supply of the oxidizer by the oxidizer supply section, in a state where the plurality of anode opening and closing sections are set to the open state and the plurality of cathode opening and closing sections are set to the closed state and the supply of the fuel by the fuel supply section is performed, the presence or absence of the cross-over leakage is determined based on the pressure difference or a change in the pressure difference for each of the plurality of fuel cells.

4. A control method of a fuel cell system, characterized by the fuel cell system including: a fuel cell that generates power using fuel supplied to an anode and an oxidizer supplied to a cathode; an anode opening and closing section that switches opening and closing of an anode flow path that communicates with the anode and through which the fuel flows; a cathode opening and closing section that switches opening and closing of a cathode flow path that communicates with the cathode and through which the oxidizer flows; an anode pressure detection section that detects a pressure of the fuel in the anode flow path; a cathode pressure detection section that detects a pressure of the oxidizer in the cathode flow path; a control section that controls switching of opening and closing of each of the anode opening and closing section and the cathode opening and closing section, and determines the presence or absence of a cross-over leakage, which is a permeation abnormality of the fuel or the oxidizer between the anode and the cathode, based on a pressure difference, which is a difference between the pressure of the fuel and the pressure of the oxidizer detected by the anode pressure detection section and the cathode pressure detection section, or a change in the pressure difference in a state where power generation of the fuel cell is stopped; a fuel supply section that supplies the fuel to the anode flow path; and an oxidizer supply section that supplies the oxidizer to the cathode flow path, the control method of the fuel cell system including a step in which, after performing power generation using the fuel and the oxidizer remaining inside the fuel cell by stopping the supply of the fuel by the fuel supply section and the supply of the oxidizer by the oxidizer supply section, in a state where the anode opening and closing section is set to the open state and the cathode opening and closing section is set to the closed state and the supply of the fuel by the fuel supply section is performed, the presence or absence of the cross-over leakage is determined based on the pressure difference or a change in the pressure difference.

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