Fuel cell system

Abstract

To provide a fuel cell system that, when the fuel cell system is an open cathode system, can prevent a fuel cell from overheating when intermittent stop control is performed to stop charging of a battery.SOLUTION: In a fuel cell system 1 according to an embodiment of the present disclosure, when an intermittent stop request is made because the SOC of a battery 12 is equal to or greater than a predetermined value V1, a control unit 14 operates a fan 83 at a high rotation speed R1, i.e., increases the supply volume of the fan 83 to a value greater than that when an FC stack 11 is generating electricity, and then performs cooling control to cool the FC stack 11, and then performs intermittent stop control to stop the fan 83.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a fuel cell system having a fuel cell that generates electricity when supplied with a fuel gas and an oxidant gas. [Background technology]

[0002] Patent Document 1 discloses a fuel cell system having a fuel cell that receives a supply of fuel gas from a fuel gas system and a supply of oxidant gas from an oxidant gas system to generate electricity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-185247 Summary of the Invention [Problem to be solved by the invention]

[0004] In a fuel cell system without a DC-DC converter between the fuel cell and the battery, i.e., a DC-DC converterless fuel cell system, the fuel cell generates power as it goes according to the battery voltage. Therefore, if the power generated by the fuel cell continues to be charged into the battery, there is a risk that the battery's SOC (i.e., charging rate) will become too high. Therefore, when the SOC becomes higher than a predetermined value, it is possible to perform intermittent stop control, which stops the fuel cell from generating power and stops charging the battery.

[0005] However, when this intermittent stop control is performed, the fuel gas remaining in the fuel cell reacts with the oxidant gas, causing the fuel cell to generate a small amount of electricity and a small current to flow, which may generate heat. When performing intermittent stop control, the oxidant gas supply device is stopped, halting the supply of oxidant gas to the fuel cell. If the fuel cell system is an open cathode system, cooling the fuel cell with the oxidant gas supplied from the oxidant gas supply device to the fuel cell is also halted. This causes the temperature of the fuel cell to rise, potentially causing the fuel cell to overheat.

[0006] However, Patent Document 1 does not disclose any measures to prevent the fuel cell from overheating in this manner.

[0007] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a fuel cell system that can prevent the fuel cell from overheating when intermittent stop control is performed to stop charging of the battery when the fuel cell system is an open cathode type system. [Means for solving the problem]

[0008] One aspect of the present disclosure made to solve the above problem is a fuel cell system having a fuel cell that generates electricity by receiving a supply of fuel gas and an oxidant gas, a fuel gas supply device that supplies the fuel gas to the fuel cell, an oxidant gas supply device that supplies the oxidant gas to the fuel cell, and a control unit that controls the fuel gas supply device and the oxidant gas supply device, wherein the fuel cell system is an open cathode type system that uses the oxidant gas as a gas for cooling the fuel cell, and the output current of the fuel cell depends on the voltage of a battery that charges with the electricity generated by the fuel cell, and when an intermittent stop request is made when the charging rate of the battery is equal to or higher than a first predetermined value, the control unit performs cooling control to cool the fuel cell by increasing the supply amount of the oxidant gas supply device to be greater than the amount during power generation, and then performs intermittent stop control to stop the oxidant gas supply device.

[0009] According to this aspect, the cooling control can be performed to cool the fuel cell in advance before performing the intermittent stop control, which stops the cooling of the fuel cell by the oxidant gas supplied from the oxidant gas supply device to the fuel cell. Therefore, even if a small current flows and heat is generated by the reaction between the remaining fuel gas and the oxidant gas in the fuel cell to generate electricity during the intermittent stop control, an increase in the temperature of the fuel cell can be suppressed. Therefore, overheating of the fuel cell can be suppressed.

[0010] In the above aspect, it is preferable that, after starting the cooling control, the control unit terminates the cooling control and performs the intermittent stop control when the temperature of the fuel cell falls below a first predetermined temperature, or when the charging rate of the battery reaches or exceeds a second predetermined value that is higher than the first predetermined value.

[0011] According to this aspect, the intermittent stop control is performed after the fuel cell has been sufficiently cooled by the cooling control, so that the fuel cell can be more reliably prevented from overheating when the intermittent stop control is being performed.

[0012] Furthermore, even if the battery's charging rate becomes high after the cooling control is started, the cooling control is terminated and the intermittent stop control is performed, thereby preventing the battery's charging rate from becoming too high.

[0013] In the above aspect, it is preferable that after starting the intermittent stop control, when the charging rate of the battery becomes equal to or lower than a third predetermined value lower than the first predetermined value, or when the temperature of the fuel cell becomes equal to or higher than a second predetermined temperature, the control unit sets the supply pressure of the fuel gas supply device to the pressure during power generation, terminates the intermittent stop control, performs the cooling control, sets the supply amount of the oxidant gas supply device to the amount during power generation, and performs restart control to restart power generation of the fuel cell.

[0014] According to this aspect, when the battery's charging rate becomes sufficiently low after performing intermittent stop control, or when the fuel cell temperature becomes high after performing intermittent stop control, cooling control is performed before restart control. As a result, even if the fuel cell generates heat during intermittent stop control and its temperature becomes high, the fuel cell can be sufficiently cooled before power generation by the fuel cell can be restarted.

[0015] In the above aspect, when performing the restart control, it is preferable that after starting the cooling control, the control unit terminates the cooling control when the temperature of the fuel cell becomes equal to or lower than a first predetermined temperature, and sets the supply amount of the oxidant gas supply device to the amount during power generation.

[0016] According to this aspect, the supply amount of the oxidant gas from the oxidant gas supply device is set to the amount during power generation after the fuel cell has been sufficiently cooled, so that even if the temperature of the fuel cell rises during intermittent stop control, the fuel cell can be more reliably cooled sufficiently before power generation by the fuel cell is restarted.

[0017] In the above aspect, it is preferable that the control unit performs the cooling control when the temperature of the fuel cell is higher than a third predetermined temperature at the time of the intermittent stop request.

[0018] According to this aspect, cooling control is performed only when it is necessary to cool the fuel cell before performing intermittent stop control, which prevents excessive cooling control from being performed more than necessary and thereby prevents an excessive supply of oxidant gas to the fuel cell.

[0019] In the above aspect, it is preferable that the control unit performs the cooling control for a predetermined time.

[0020] According to this aspect, the cooling control is not terminated by checking the temperature of the fuel cell, but is performed for a predetermined period of time and then terminated, which eliminates the need for equipment and the effort required to measure the temperature of the fuel cell. [Effects of the Invention]

[0021] According to the fuel cell system of the present disclosure, in the case where the fuel cell system is an open cathode system, overheating of the fuel cell can be prevented when intermittent stop control is performed to stop charging of the battery. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing an example of the FC current, FC voltage, battery current, and battery voltage when power is consumed in the inverter in a DC-DC converter-less fuel cell system. [Figure 3] FIG. 10 is a diagram showing an example of the FC current, FC voltage, battery current, and battery voltage when there is no power consumption in the inverter in a DC-DC converter-less fuel cell system. [Figure 4] FIG. 3 is a flowchart showing the contents of control performed by a control unit in the first embodiment. [Figure 5] FIG. 10 is a flowchart showing the contents of control performed by a control unit in a modified example of the first embodiment. [Figure 6] FIG. 10 is a flowchart showing the contents of control performed by a control unit in the second embodiment. [Figure 7] FIG. 10 is a flowchart showing the contents of control performed by a control unit in a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of a fuel cell system according to the present disclosure will be described.

[0024] (Configuration of fuel cell system) 1, in the fuel cell system 1 of this embodiment, an FC stack 11, a battery 12, and an inverter 13 (or a motor) are connected in parallel, forming a simple system configuration without a DC-DC converter. In other words, the fuel cell system 1 is a DC-DC converter-less system.

[0025] The DC-DC converter is a device that converts the FC voltage supplied to the battery 12. The FC stack 11 is an example of a "fuel cell" in this disclosure. The FC voltage is the voltage of the power generated by the FC stack 11.

[0026] The fuel cell system 1 also has a hydrogen system 21 and an air system / cooling system 22 .

[0027] The FC stack 11 generates power by receiving a supply of fuel gas and an oxidant gas. In this embodiment, the fuel gas is hydrogen gas, and the oxidant gas is air. That is, the FC stack 11 generates power by receiving a supply of hydrogen gas from a hydrogen system 21 and a supply of air from an air system / cooling system 22. The power generated by the FC stack 11 is then supplied to a battery 12 and an inverter 13. The FC stack 11 is provided with a temperature sensor 11a as a temperature measurement unit that measures the temperature of the FC stack 11.

[0028] The battery 12 is connected to the FC stack 11 and is charged with the power generated by the FC stack 11. The battery 12 is also connected to the inverter 13 and supplies the inverter 13 with the charged power.

[0029] The hydrogen system 21 is provided on the anode side of the FC stack 11. The hydrogen system 21 includes a hydrogen supply passage 31, a hydrogen discharge passage 32, and a filling passage 33.

[0030] The hydrogen supply passage 31 is a passage for supplying hydrogen gas from a hydrogen tank 41 in which hydrogen gas is stored to the FC stack 11. The hydrogen discharge passage 32 is a passage for discharging hydrogen gas (i.e., hydrogen off-gas) discharged from the FC stack 11. The filling passage 33 is a passage for filling hydrogen gas into the hydrogen tank 41 from a filling port 51.

[0031] The hydrogen system 21 includes, in order from the hydrogen tank 41 side, a valve 61, a pressure reducing valve 62, an injector 63, and a pressure sensor 64 in the hydrogen supply passage 31. The injector 63 is an example of the "fuel gas supply device" of the present disclosure.

[0032] Valve 61 switches between supplying and blocking hydrogen gas from hydrogen tank 41 to hydrogen supply passage 31. Pressure reducing valve 62 is a pressure regulating valve for reducing the pressure of hydrogen gas. Injector 63 is a device that injects hydrogen gas guided from hydrogen tank 41 downstream, and supplies hydrogen gas to FC stack 11. Pressure sensor 64 is a pressure measuring unit that measures the outlet fuel pressure of injector 63 (i.e., the pressure of hydrogen gas at the outlet of injector 63).

[0033] In addition, the hydrogen system 21 is provided with an exhaust drain valve 71 in the hydrogen discharge passage 32, which switches between discharging and blocking the discharge of hydrogen off-gas and moisture.

[0034] On the other hand, the air system and cooling system 22 is provided on the cathode side of the FC stack 11. This air system and cooling system 22 includes an air supply passage 81, an air discharge passage 82, and a fan 83. The fan 83 is an example of the "oxidant gas supply device" of the present disclosure.

[0035] The air supply passage 81 is a passage for supplying air from outside the fuel cell system 1 to the FC stack 11. The air discharge passage 82 is a passage for discharging air discharged from the FC stack 11 (i.e., air off-gas).

[0036] The fan 83 supplies air to the FC stack 11 via the air supply passage 81 and discharges air off-gas from the FC stack 11 via the air discharge passage 82 .

[0037] In this embodiment, the fan 83 not only serves to supply air to the FC stack 11 via the air supply passage 81, and use that air to cause the FC stack 11 to generate electricity, but also to cool the FC stack 11. In this way, the fuel cell system 1 of this embodiment is an open cathode system that uses the air supplied to the FC stack 11 by the fan 83 as a cooling gas for the FC stack 11.

[0038] The fuel cell system 1 further includes a control unit 14. The control unit 14 is a device having, for example, an arithmetic processing unit such as a CPU, a storage unit such as a ROM for storing control programs and control data processed by the CPU and a RAM used as various work areas for control processing, and an input / output interface unit. The control unit 14 performs various controls of the fuel cell system 1 according to the control programs stored in the storage unit.

[0039] In this embodiment, the control unit 14 controls various parts of the fuel cell system 1, such as the inverter 13, valve 61, pressure reducing valve 62, injector 63, exhaust drain valve 71, and fan 83. The control unit 14 also obtains measurement results of the temperature of the FC stack 11 from the temperature sensor 11a, and measurement results of the outlet fuel pressure of the injector 63 from the pressure sensor 64.

[0040] (Fuel cell system operation) In the fuel cell system 1 configured as described above, the hydrogen gas supplied from the hydrogen supply passage 31 to the FC stack 11 is used for power generation in the FC stack 11, and then discharged from the FC stack 11 as hydrogen off-gas via the hydrogen discharge passage 32 to the outside of the fuel cell system 1. In addition, the air supplied from the air supply passage 81 to the FC stack 11 is used for power generation in the FC stack 11, and then discharged from the FC stack 11 as air off-gas via the air discharge passage 82 to the outside of the fuel cell system 1.

[0041] The electric power generated by the FC stack 11 is supplied to the battery 12 to charge the battery 12, or is supplied to the inverter 13 to drive the inverter 13. The inverter 13 is also supplied with electric power from the battery 12.

[0042] (About DC / DC converter-less systems) As shown in Fig. 1, the fuel cell system 1 of this embodiment is a so-called DCDC converter-less system in which no DCDC converter is arranged between the FC stack 11 and the battery 12. Therefore, in the fuel cell system 1, the FC voltage is equal to (or approximately equal to) the battery voltage, and the FC current depends on the battery voltage. In other words, the fuel cell system 1 supplies the power generated in the FC stack 11 to the battery 12 and inverter 13 without converting the FC voltage. The FC current is the current of the power generated in the FC stack 11. The battery voltage is the voltage of the battery 12.

[0043] In the fuel cell system 1, the FC voltage is equal to the battery voltage in this way, so the FC stack 11 generates power as it goes according to the battery voltage.

[0044] For example, as shown in FIG. 2, if there is power consumption in the inverter 13 and the battery voltage is 47V, the FC voltage will be equal to the battery voltage, 47V. This will result in the FC current being 50A. Therefore, the FC output = 47V × 50A = 2.3kW, and the battery output = 47V × 100A = 4.7kW. By adding up these FC output and battery output, the power consumption in the inverter 13 = 47V × 150A = 7.0kW can be obtained. The FC output is the power generated in the FC stack 11 and output from the FC stack 11. The battery output is the power output from the battery 12.

[0045] 3, if there is no power consumption in inverter 13 and the battery voltage is 49 V, the FC voltage will be equal to the battery voltage, 49 V. This will result in the FC current being 30 A. Therefore, the FC output = 49 V × 30 A = 1.5 kW, and the battery output = 49 V × -30 A = -1.5 kW.

[0046] (Measures to prevent fuel cell overheating by implementing intermittent shutdown control) In the DC-DC converter-less fuel cell system 1, the FC stack 11 generates power as it goes according to the battery voltage. Therefore, if the power generated by the FC stack 11 continues to charge the battery 12, there is a risk that the SOC (i.e., the charging rate) of the battery 12 will become too high. Therefore, in this embodiment, when the SOC of the battery 12 becomes higher than a predetermined value, the control unit 14 performs intermittent stop control to stop power generation by the FC stack 11 and stop charging of the battery 12.

[0047] However, when this intermittent stop control is performed, there is a risk that the hydrogen gas remaining in the FC stack 11 and other components will react with the air, causing a small amount of electricity to be generated in the FC stack 11 and a small current to flow, which may generate heat. When performing intermittent stop control, the fan 83 is stopped, halting the supply of air to the FC stack 11. At this time, because the fuel cell system 1 is an open cathode system, cooling of the FC stack 11 by the air supplied from the fan 83 to the FC stack 11 will also be stopped. This will cause the temperature of the FC stack 11 to rise, and there is a risk that the FC stack 11 will overheat.

[0048] Therefore, in this embodiment, when the fuel cell system 1 is an open cathode system and intermittent stop control is performed to stop charging of the battery 12, the control unit 14 performs the following control to prevent the FC stack 11 from overheating.

[0049] <First Example> First, the first embodiment will be described.

[0050] In this embodiment, as shown in FIG. 4, the control unit 14 determines whether the SOC of the battery 12 is equal to or greater than a predetermined value V1 (e.g., 80%) (step S1). That is, the control unit 14 determines whether the current time corresponds to an intermittent stop request, in which intermittent stop control is required due to a high SOC. Here, in this embodiment, "intermittent stop control" refers to control that stops charging of the battery 12 by stopping the fan 83 and stopping power generation by the FC stack 11. The predetermined value V1 is also an example of a "first predetermined value" in the present disclosure.

[0051] If the SOC is equal to or greater than the predetermined value V1 (step S1: YES), the control unit 14 first operates the fan 83 at a high rotation speed R1 (e.g., duty 80%) before performing intermittent stop control (step S2). In this way, when an intermittent stop request is made, the control unit 14 first increases the rotation speed of the fan 83 to perform cooling control to cool the FC stack 11. Note that the high rotation speed R1 is a rotation speed higher than the normal rotation speed R0, which is the rotation speed when the FC stack 11 is generating electricity. Also, "duty 80%" means that the duty ratio of the voltage applied to the motor provided in the fan 83 is set to 80%.

[0052] Then, after starting the cooling control, when the temperature of the FC stack 11 becomes equal to or lower than a predetermined temperature T1 (e.g., 40°C) or when the SOC becomes equal to or higher than a predetermined value V2 (e.g., 90%) (step S3: YES), the control unit 14 sets the injector outlet target fuel pressure to a predetermined pressure P1 (e.g., 5 kPaG or lower) (step S4), terminates the cooling control, and stops the fan 83 (step S5).

[0053] The temperature of the FC stack 11 is the temperature measured by the temperature sensor 11a. The predetermined temperature T1 is an example of the "first predetermined temperature" of the present disclosure. The predetermined value V2 is a value higher than the predetermined value V1 and is an example of the "second predetermined value" of the present disclosure. The injector outlet target fuel pressure is a target value for the outlet fuel pressure of the injector 63 and is an example of the "supply pressure of the fuel gas supply device" of the present disclosure. The predetermined pressure P1 is a pressure lower than the normal predetermined pressure P0, which is the pressure when the FC stack 11 is generating electricity.

[0054] In this way, the control unit 14 operates the fan 83 by setting the rotation speed of the fan 83 to the high rotation speed R1, i.e., by increasing the amount of air supplied by the fan 83 to the FC stack 11 compared to the amount when the FC stack 11 is generating electricity, thereby performing cooling control to cool the FC stack 11, and then performs intermittent stop control to reduce the injector outlet fuel pressure and stop the fan 83.

[0055] Then, after starting intermittent stop control, when the SOC falls below a predetermined value V3 (e.g., 30%) or when the temperature of the FC stack 11 reaches a predetermined temperature T2 (e.g., 60°C) or higher (step S6: YES), the control unit 14 sets the injector outlet target fuel pressure to the normal predetermined pressure P0 (e.g., 50 kPaG) (step S7).In this way, the control unit 14 sets the amount of hydrogen gas supplied to the FC stack 11 by the injector 63 to the amount when the FC stack 11 is generating electricity.

[0056] The predetermined value V3 is a value lower than the predetermined value V1 and the predetermined value V2, and is an example of the "third predetermined value" in the present disclosure. The predetermined temperature T2 is a temperature higher than the predetermined temperature T1, and is an example of the "second predetermined temperature" in the present disclosure.

[0057] Next, the control unit 14 operates the fan 83 at the high rotation speed R1 (step S8). That is, the control unit 14 ends the intermittent stop control and performs cooling control.

[0058] Thereafter, when the temperature of the FC stack 11 becomes equal to or lower than the predetermined temperature T1 (step S9: YES), the control unit 14 operates the fan 83 at the normal rotation speed R0 (for example, DUTY 20% (i.e., )) (step S10). Note that "DUTY 20%" means that the duty ratio of the voltage applied to the motor provided in the fan 83 is set to 20%.

[0059] In this way, after performing cooling control (more specifically, after starting cooling control, the control unit 14 ends the cooling control when the temperature of the FC stack 11 falls below the predetermined temperature T1), it performs restart control to set the amount of air supplied to the FC stack 11 by the fan 83 to the amount when the FC stack 11 is generating electricity, and restart the power generation of the FC stack 11.

[0060] The order of steps S7 to S10 may be changed. For example, control unit 14 may operate fan 83 at high rotation speed R1 (step S8 in FIG. 4), and when the temperature of FC stack 11 becomes equal to or lower than predetermined temperature T1 (step S9 in FIG. 4: YES), operate fan 83 at normal rotation speed R0 (step S10 in FIG. 4), and set the injector outlet target fuel pressure to the normal predetermined pressure P0 (step S7 in FIG. 4).

[0061] In addition, the control unit 14 may simultaneously perform control to set the injector outlet target fuel pressure to the normal predetermined pressure P0 (step S7 in FIG. 4) and control to operate the fan 83 at the normal rotation speed R0 (step S10 in FIG. 4).

[0062] Furthermore, as a modified example of this embodiment, as shown in FIG. 5, the difference from FIG. 4 is that the control unit 14 may perform control to operate the fan 83 at a high rotation speed R1, i.e., cooling control, for a predetermined time t (e.g., 10 seconds) (steps S102 and S107).

[0063] As described above, according to this embodiment, when an intermittent stop request is made, the control unit 14 performs cooling control and then performs intermittent stop control.

[0064] This makes it possible to perform cooling control in advance to cool the FC stack 11 before performing intermittent stop control, which stops the fan 83 and stops cooling the FC stack 11. Therefore, even if a small current flows and heat is generated when intermittent stop control is being performed and the remaining hydrogen gas in the FC stack 11 reacts with the air to generate electricity, it is possible to prevent the temperature of the FC stack 11 from rising. As a result, it is possible to prevent the FC stack 11 from overheating.

[0065] Furthermore, after starting the cooling control, the control unit 14 terminates the cooling control and performs intermittent stop control when the temperature of the FC stack 11 becomes equal to or lower than a predetermined temperature T1, or when the SOC becomes equal to or higher than a predetermined value V2.

[0066] In this way, intermittent stop control is performed after cooling control has been performed to sufficiently cool the FC stack 11. Therefore, overheating of the FC stack 11 can be more reliably prevented when intermittent stop control is being performed.

[0067] Furthermore, after the cooling control is started, when the SOC becomes equal to or greater than the predetermined value V2, the cooling control is terminated and the intermittent stop control is performed, thereby preventing the SOC from becoming too high.

[0068] Furthermore, after starting intermittent stop control, when the SOC falls below a predetermined value V3, or when the temperature of the FC stack 11 reaches a predetermined temperature T2 or higher, the control unit 14 performs restart control to restart power generation in the FC stack 11. When performing restart control, the injector outlet target fuel pressure is set to the normal predetermined pressure P0, the intermittent stop control is ended, cooling control is performed, the fan 83 is operated at the normal rotation speed R0, and the supply amount of fan 83 (i.e., the amount of air supplied from fan 83 to FC stack 11) is set to the amount when the FC stack 11 is generating power.

[0069] In this way, when the SOC becomes sufficiently small after performing intermittent stop control, or when the temperature of the FC stack 11 becomes high after performing intermittent stop control, cooling control is performed and then restart control is performed. As a result, even if the FC stack 11 generates heat during intermittent stop control and the temperature of the FC stack 11 becomes high, the FC stack 11 can be sufficiently cooled before power generation of the FC stack 11 can be restarted.

[0070] Furthermore, when the control unit 14 performs restart control, after starting the cooling control, when the temperature of the FC stack 11 falls below a predetermined temperature T1, the control unit 14 ends the cooling control, operates the fan 83 at the normal rotation speed R0, and sets the supply volume of the fan 83 to the volume when the FC stack 11 is generating electricity.

[0071] In this way, after the FC stack 11 has been sufficiently cooled, the supply volume of the fan 83 is set to the volume during power generation of the FC stack 11. As a result, even if the temperature of the FC stack 11 rises while intermittent stop control is being performed, power generation of the FC stack 11 can be restarted more reliably after the FC stack 11 has been sufficiently cooled.

[0072] Furthermore, the control unit 14 may perform the cooling control for a predetermined time t.

[0073] In this way, cooling control is performed for a predetermined time t and then terminated, rather than terminating the cooling control by checking the temperature of the FC stack 11. This makes it possible to save the equipment (for example, temperature sensor 11a) and the effort required to measure the temperature of the FC stack 11.

[0074] <Second Example> Next, the second embodiment will be described focusing on the differences from the first embodiment, and a description of the commonalities with the first embodiment will be omitted.

[0075] In this embodiment, the difference from the first embodiment is that, as shown in FIG. 6, when the SOC is equal to or greater than a predetermined value V1 (step S201: YES), the control unit 14 determines whether the temperature of the FC stack 11 is equal to or less than a predetermined temperature T3 (e.g., 50°C) (step S202).

[0076] The predetermined temperature T3 is a temperature between the predetermined temperature T1 and the predetermined temperature T2, that is, a temperature higher than the predetermined temperature T1 but lower than the predetermined temperature T2, and is an example of the "third predetermined temperature" of the present disclosure.

[0077] If the temperature of the FC stack 11 is equal to or lower than the predetermined temperature T3 (step S202: YES), the control unit 14 sets the injector outlet target fuel pressure to the predetermined pressure P1 (step S203) and stops the fan 83 (step S204). In this way, in this embodiment, the control unit 14 performs intermittent stop control when an intermittent stop request is made and the temperature of the FC stack 11 is equal to or lower than the predetermined temperature T3.

[0078] On the other hand, if the temperature of the FC stack 11 is higher than the predetermined temperature T3 (step S202: YES), the control unit 14 sets the injector outlet target fuel pressure to the normal predetermined pressure P0 (step S206) and operates the fan 83 at the high rotation speed R1 (step S207). In this way, in this embodiment, the control unit 14 performs cooling control when an intermittent stop request is made and the temperature of the FC stack 11 is higher than the predetermined temperature T3.

[0079] Furthermore, as a modified example of this embodiment, as shown in FIG. 7, the difference from FIG. 6 is that the control unit 14 may perform control to operate the fan 83 at a high rotation speed R1, i.e., cooling control, for a predetermined time t (step S307).

[0080] As described above, according to this embodiment, the control unit 14 performs cooling control when an intermittent stop request is made and the temperature of the FC stack 11 is higher than the predetermined temperature T3.

[0081] As a result, before performing intermittent stop control, cooling control is performed only when it is necessary to cool the FC stack 11 because the temperature of the FC stack 11 is high. Therefore, it is possible to prevent excessive air being supplied to the FC stack 11 by performing cooling control more than necessary.

[0082] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible within the scope of the gist of the present disclosure.

[0083] For example, the "oxidant gas supply device" of the present disclosure is not limited to the fan 83, but may be any device that supplies air (oxidant gas) to the FC stack 11 (fuel cell). Also, the "fuel gas supply device" of the present disclosure is not limited to the injector 63, but may be any device that supplies hydrogen gas (fuel gas) to the FC stack 11 (fuel cell). [Explanation of symbols]

[0084] 1. Fuel cell system 11 FC stack 11a Temperature sensor 12 Battery 13 Inverter (or motor) 14 Control Unit 21 Hydrogen 22 Air and cooling systems 31 Hydrogen supply passage 63 Injector 64 Pressure Sensor 81 Air supply passage 83 Fans V1 Predetermined value V2 predetermined value V3 Predetermined value R1 High RPM R0 Normal rotation speed T1 Predetermined temperature T2 Predetermined temperature T3 Predetermined temperature P1 specified pressure P0 Normal specified pressure t predetermined time

Claims

1. a fuel cell that generates electricity by receiving a supply of fuel gas and an oxidant gas; a fuel gas supply device for supplying the fuel gas to the fuel cell; an oxidant gas supply device for supplying the oxidant gas to the fuel cell; a control unit that controls the fuel gas supply device and the oxidant gas supply device; In a fuel cell system having The fuel cell system includes: An open cathode system in which the oxidant gas is used as a cooling gas for the fuel cell, and a system in which the output current of the fuel cell depends on the voltage of a battery that charges the power generated by the fuel cell, The control unit When an intermittent stop request is made and the charging rate of the battery is equal to or higher than a first predetermined value, After performing cooling control to cool the fuel cell by increasing the supply amount of the oxidant gas from the oxidant gas supply device to a value greater than the amount during power generation, performing intermittent stop control to stop the oxidant gas supply device; A fuel cell system characterized by:

2. 2. The fuel cell system of claim 1, The control unit After the cooling control is started, When the temperature of the fuel cell becomes equal to or lower than a first predetermined temperature, Alternatively, when the charging rate of the battery becomes equal to or greater than a second predetermined value that is higher than the first predetermined value, Ending the cooling control and performing the intermittent stop control. A fuel cell system characterized by:

3. 3. The fuel cell system according to claim 1, The control unit After the intermittent stop control is started, When the charging rate of the battery becomes equal to or lower than a third predetermined value that is lower than the first predetermined value, Alternatively, when the temperature of the fuel cell reaches or exceeds a second predetermined temperature, The supply pressure of the fuel gas supply device is set to a pressure during power generation, The intermittent stop control is terminated and the cooling control is performed. the supply amount of the oxidant gas from the oxidant gas supply device is set to the amount required for power generation; performing restart control to restart power generation of the fuel cell; A fuel cell system characterized by:

4. 4. The fuel cell system of claim 3, when performing the restart control, after starting the cooling control, when the temperature of the fuel cell becomes equal to or lower than a first predetermined temperature, the control unit ends the cooling control and sets the supply amount of the oxidant gas from the oxidant gas supply device to the amount during power generation; A fuel cell system characterized by:

5. 3. The fuel cell system according to claim 1, the control unit performs the cooling control when the temperature of the fuel cell is higher than a third predetermined temperature at the time of the intermittent stop request; A fuel cell system characterized by:

6. 2. The fuel cell system of claim 1, the control unit performs the cooling control for a predetermined time; A fuel cell system characterized by:

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