Controller and fuel cell system

Abstract

To provide a technique that reduces noise from a compressor for a fuel cell system.SOLUTION: A controller that a fuel cell system 10 includes comprises a reception part and a control part. When the reception part receives an electric power generation stop command during a vehicle drive, the control part closes sealing valves 116, 118, and also sets an opening of a bypass valve 119 to a first opening smaller than its maximum opening and a rotation speed of a compressor 112 to a predetermined rotation speed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device and a fuel cell system.

Background Art

[0002] In recent years, in order for more people to access affordable, reliable, sustainable, and advanced energy, research and development have been carried out on fuel cells that contribute to energy efficiency.

[0003] Regarding fuel cells, there is a fuel cell system including a fuel cell stack including power generation cells. The fuel cell system can be mounted on a moving body such as a vehicle. In the fuel cell system mounted on the moving body, power generation of the power generation cells may stop even when the moving body is operating.

[0004] Patent Document 1 discloses performing idle control when receiving a signal related to power generation stop during operation of the moving body. In the idle control disclosed in Patent Document 1, power generation of the power generation cells is performed with power smaller than the power consumption of a compressor (air pump) that outputs an oxidant gas supplied to the fuel cell stack.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When the compressor is operating, noise is generated from the compressor. There is a long-felt need for a technique that contributes to noise reduction.

[0007] An object of the present invention is to solve the above-described problems.

Means for Solving the Problems

[0008] Aspects of the present invention include a fuel cell stack including a power generation cell, a battery for storing the generated power of the power generation cell, an oxidant gas supply passage connected to the fuel cell stack, an oxidant gas discharge passage connected to the fuel cell stack, a bypass passage having one end connected to the oxidant gas supply passage and the other end connected to the oxidant gas discharge passage, a compressor for supplying oxidant gas to the oxidant gas supply passage, at least one shut-off valve provided in at least one of the oxidant gas supply passage between the connection portion to which one end of the bypass passage is connected and the fuel cell stack and the oxidant gas discharge passage between the connection portion to which the other end of the bypass passage is connected and the fuel cell stack, and a bypass valve provided in the bypass passage and having an adjustable opening degree. A control device provided in a fuel cell system includes a reception unit that receives a command and a control unit that performs control based on the command. When the reception unit receives a power generation stop command for stopping the power generation of the power generation cell in a state where the fuel cell system is operating, the control unit closes the shut-off valve, sets the opening degree of the bypass valve to a first opening degree smaller than the maximum opening degree, and sets the rotation speed of the compressor to a predetermined rotation speed lower than the rotation speed during the power generation of the power generation cell.

Advantages of the Invention

[0009] According to the present invention, noise generated from the compressor can be reduced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Best Mode for Carrying Out the Invention

[0011] [1 Configuration of Fuel Cell System 10] FIG. 1 is a schematic configuration diagram of a fuel cell system 10. The fuel cell system 10 is mounted on a vehicle (fuel cell vehicle), but is not limited thereto. For example, the object on which the fuel cell system 10 is mounted may be a moving body other than a vehicle, such as a ship, an aircraft, a robot, etc. Further, the object on which it is mounted may be a stationary power source for facilities, homes, etc.

[0012] In the fuel cell system 10, a fuel gas and an oxidant gas are used as reaction gases. The fuel gas is a hydrogen-containing gas. The oxidant gas is an oxygen-containing gas such as air. Each of the fuel gas and the oxidant gas is supplied to the fuel cell stack 12 and used for an electrochemical reaction. In this specification, the fuel gas discharged from the fuel cell stack 12 without being used for the electrochemical reaction is also referred to as fuel off-gas. Also, in this specification, the oxidant gas discharged from the fuel cell stack 12 without being used for the electrochemical reaction is also referred to as oxidant off-gas.

[0013] The fuel cell system 10 includes a fuel cell stack 12, a tank 14, an anode system 16, a cathode system 18, a cooling system 20, and a control device 22. The electric power generated by the fuel cell stack 12 is supplied to a load 26. The load 26 includes a battery 26A that accumulates the generated electric power in the fuel cell stack 12 and a drive motor 26B of the vehicle. The tank 14 is filled with high-pressure fuel gas.

[0014] The fuel cell stack 12 includes a fuel gas supply port 12a for supplying fuel gas into the fuel cell stack 12 and a fuel gas discharge port 12b for discharging fuel off-gas from the inside of the fuel cell stack 12. The fuel cell stack 12 includes an oxidant gas supply port 12c for supplying oxidant gas into the fuel cell stack 12 and an oxidant gas discharge port 12d for discharging oxidant off-gas from the inside of the fuel cell stack 12. The fuel cell stack 12 includes a refrigerant supply port 12e for supplying refrigerant into the fuel cell stack 12 and a refrigerant discharge port 12f for discharging refrigerant from the inside of the fuel cell stack 12.

[0015] The fuel cell stack 12 has a plurality of power generation cells 28. The plurality of power generation cells 28 each have an equivalent configuration. The power generation cell 28 includes an electrolyte membrane-electrode structure 30, a first separator 32, and a second separator 34. The electrolyte membrane-electrode structure 30 is sandwiched between the first separator 32 and the second separator 34. One of the plurality of power generation cells 28 is illustrated in FIG. 1.

[0016] The first separator 32 and the second separator 34 are formed of a metal thin plate with a corrugated cross-section. In two adjacent power generation cells 28, the first separator 32 of one power generation cell 28 and the second separator 34 of the other power generation cell 28 are joined to each other. A cell cooling flow path (not shown) is formed between the first separator 32 and the second separator 34. The cell cooling flow path communicates with the refrigerant supply port 12e and the refrigerant discharge port 12f.

[0017] The electrolyte membrane - electrode structure 30 includes an electrolyte membrane 36, an anode electrode 38, and a cathode electrode 40. The electrolyte membrane 36 is interposed between the anode electrode 38 and the cathode electrode 40. An anode flow path 42 is formed between the first separator 32 and the anode electrode 38. A cathode flow path 44 is formed between the second separator 34 and the cathode electrode 40. The anode flow path 42 communicates with the fuel gas supply port 12a and the fuel gas discharge port 12b. The cathode flow path 44 communicates with the oxidant gas supply port 12c and the oxidant gas discharge port 12d.

[0018] A temperature sensor 46 is provided near the fuel gas discharge port 12b. For example, the temperature sensor 46 is provided in a fuel gas discharge path 86 connected to the fuel gas discharge port 12b. The temperature sensor 46 detects the temperature of the fuel gas. The temperature sensor 46 may be provided near the oxidant gas discharge port 12d. For example, the temperature sensor 46 may be provided in an oxidant gas discharge path 108 connected to the oxidant gas discharge port 12d. In this case, the temperature sensor 46 detects the temperature of the oxidant gas. The temperature of the fuel gas or the oxidant gas (gas temperature) near the discharge port of the fuel cell stack 12 is the representative temperature of the fuel cell stack 12. That is, the gas temperature corresponds to the temperature of the fuel cell stack 12 (stack temperature).

[0019] The anode system 16 includes a fuel gas supply path 84, a fuel gas discharge path 86, a circulation path 88, and a drainage path 90. The anode system 16 also includes an injector 94, an ejector 96, a gas - liquid separator 98, and a drain valve 100.

[0020] The fuel gas supply path 84 is connected to the discharge port of the tank 14 and the fuel gas supply port 12a of the fuel cell stack 12. The fuel gas supply path 84 is provided with an injector 94 and an ejector 96. The ejector 96 is arranged closer to the fuel cell stack 12 than the injector 94.

[0021] The fuel gas discharge passage 86 is connected to the fuel gas discharge port 12b of the fuel cell stack 12 and the supply port of the gas-liquid separator 98. The circulation passage 88 is connected to the exhaust port of the gas-liquid separator 98 and the ejector 96.

[0022] The drain passage 90 is connected to the drain port of the gas-liquid separator 98 and the inlet of the diluter 121. The outlet of the diluter 121 is connected to the discharge port provided in the vehicle. A drain valve 100 is provided in the drain passage 90.

[0023] The cathode system 18 includes an oxidant gas supply passage 106, an oxidant gas discharge passage 108 (discharge passage), and a bypass passage 110. The cathode system 18 also includes a compressor 112 (oxidant gas supplier), a humidifier 114, a first shutoff valve 116, a second shutoff valve 118, and a bypass valve 119.

[0024] The oxidant gas supply passage 106 is connected to the air intake port provided in the vehicle and the oxidant gas supply port 12c of the fuel cell stack 12. The oxidant gas supply passage 106 is provided with a compressor 112, a first shutoff valve 116, and a humidifier supply passage 114A of the humidifier 114. Among the oxidant gas supply passage 106, the portion arranged upstream of the humidifier 114 is referred to as the oxidant gas supply passage 106A. Among the oxidant gas supply passage 106, the portion arranged downstream of the humidifier 114 is referred to as the oxidant gas supply passage 106B. The oxidant gas supply passage 106A is provided with a compressor 112 and a first shutoff valve 116.

[0025] The compressor 112 is a device that supplies oxidant gas to the oxidant gas supply passage 106A. The compressor 112 may be a turbo compressor using an air bearing for the rotating shaft. In the turbo compressor, the rotating shaft is levitated by air. The first shutoff valve 116 is an on-off valve that opens and closes the oxidant gas supply passage 106A. The first shutoff valve 116 is arranged closer to the humidifier 114 than the compressor 112.

[0026] The oxidant gas discharge passage 108 is connected to the oxidant gas discharge port 12d of the fuel cell stack 12 and the inlet of the diluter 121. The oxidant gas discharge passage 108 is provided with the humidifier discharge passage 114B of the humidifier 114 and the second shutoff valve 118. Among the oxidant gas discharge passage 108, the portion arranged upstream of the humidifier 114 is referred to as the oxidant gas discharge passage 108A. Among the oxidant gas discharge passage 108, the portion arranged downstream of the humidifier 114 is referred to as the oxidant gas discharge passage 108B. The oxidant gas discharge passage 108B is provided with the second shutoff valve 118. The second shutoff valve 118 is an on-off valve that opens and closes the oxidant gas discharge passage 108B.

[0027] The bypass passage 110 connects the oxidant gas supply passage 106 and the oxidant gas discharge passage 108. One end of the bypass passage 110 is connected to the oxidant gas supply passage 106A between the compressor 112 and the first shutoff valve 116. The first shutoff valve 116 is located in the oxidant gas supply passage 106A between the connection portion CP1 to which one end of the bypass passage 110 is connected and the fuel cell stack 12. The other end of the bypass passage 110 is connected to the oxidant gas discharge passage 108B downstream of the second shutoff valve 118. The second shutoff valve 118 is located in the oxidant gas discharge passage 108B between the connection portion CP2 to which the other end of the bypass passage 110 is connected and the fuel cell stack 12. The bypass passage 110 is provided with a bypass valve 119. The bypass valve 119 is an adjustment valve whose opening can be adjusted. Examples of the adjustment valve include a butterfly valve. The amount of oxidant gas supplied to the fuel cell stack 12 is adjusted according to the opening of the bypass valve 119.

[0028] The cooling system 20 includes a refrigerant flow passage 120. The cooling system 20 also includes a pump 126, a radiator 128, a temperature sensor 130, and a flow control valve 132.

[0029] The refrigerant flow path 120 circulates the refrigerant between the fuel cell stack 12 and the radiator 128. The refrigerant is, for example, water containing ethylene glycol. The refrigerant flow path 120 includes a refrigerant supply path 122, a refrigerant discharge path 124, and a branch path 125. The refrigerant supply path 122 connects the fluid discharge port of the radiator 128 and the refrigerant supply port 12e of the fuel cell stack 12. The refrigerant discharge path 124 connects the refrigerant discharge port 12f of the fuel cell stack 12 and the fluid supply port of the radiator 128. The branch path 125 branches off from the refrigerant discharge path 124 and merges into the refrigerant supply path 122.

[0030] The pump 126 is provided in the refrigerant supply path 122. Incidentally, the pump 126 may be provided in the refrigerant discharge path 124. The radiator 128 is a radiator that dissipates heat from the refrigerant in the refrigerant flow path 120. The radiator 128 may be provided with a fan.

[0031] The temperature sensor 130 is provided in the refrigerant discharge path 124. The temperature sensor 130 may be provided in the refrigerant supply path 122. The temperature sensor 130 detects the temperature of the refrigerant (refrigerant temperature). The refrigerant temperature corresponds to the temperature inside the fuel cell stack 12 (stack temperature).

[0032] The flow control valve 132 is provided at the merging portion where the branch path 125 merges into the refrigerant supply path 122. Incidentally, the flow control valve 132 may be provided at the branching portion where the branch path 125 branches off from the refrigerant discharge path 124. The flow control valve 132 is adjustable in opening degree. The amount of refrigerant supplied to the radiator 128 is adjusted according to the opening degree of the flow control valve 132.

[0033] The control device 22 can be constituted by an ECU (Electronic Control Unit). The control device 22 includes an arithmetic unit 136 and a storage unit 138.

[0034] The arithmetic unit 136 is a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), for example. The arithmetic unit 136 includes a reception unit 140 and a control unit 142. The reception unit 140 receives a command from a control system that controls the vehicle. The control unit 142 performs control based on the command received by the reception unit 140. The control unit 142 has a power generation control unit 150 that performs power generation control and an idle control unit 152 that performs idle control.

[0035] The reception unit 140 and the control unit 142 operate when a program stored in the storage unit 138 is executed by the arithmetic unit 136. At least one of the reception unit 140 and the control unit 142 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Alternatively, at least one of the reception unit 140 and the control unit 142 may be realized by an electronic circuit including discrete devices.

[0036] The storage unit 138 is a computer-readable storage medium. The storage unit 138 includes a volatile memory and a non-volatile memory. The volatile memory is, for example, a RAM (Random Access Memory) or the like. The non-volatile memory is, for example, a ROM (Read Only Memory), a flash memory, or the like. Data and the like are stored in the volatile memory, for example. Programs, tables, maps, etc. are stored in the non-volatile memory, for example. At least a part of the storage unit 138 may be provided in the above-described processor, integrated circuit, etc.

[0037] [Fluid Flow in the Fuel Cell System 10] [Fluid Flow in the Anode System 16] The injector 94 injects the fuel gas supplied from the tank 14 downstream of the fuel gas supply passage 84. The fuel gas injected from the injector 94 is supplied to the fuel gas supply port 12a of the fuel cell stack 12 via the fuel gas supply passage 84. The fuel gas that has not reacted inside the fuel cell stack 12 is discharged as fuel off-gas from the fuel gas discharge port 12b of the fuel cell stack 12. The fuel off-gas contains hydrogen that has not reacted with oxygen, nitrogen in the oxidant gas that has permeated through the electrolyte membrane 36, and moisture generated by the reaction of oxygen and hydrogen.

[0038] The fuel off-gas is supplied to the gas-liquid separator 98 via the fuel gas discharge passage 86. The gas-liquid separator 98 separates the fuel off-gas into a gas component (fuel off-gas) and a liquid component (water). The fuel off-gas discharged from the gas-liquid separator 98 is supplied to the ejector 96 via the circulation passage 88. The fuel off-gas sucked from the gas-liquid separator 98 and the fuel gas injected from the injector 94 merge at the ejector 96.

[0039] The compressor 112 discharges the oxidant gas (air) sucked from outside the vehicle downstream of the oxidant gas supply passage 106. The oxidant gas discharged from the compressor 112 is supplied to the oxidant gas supply port 12c of the fuel cell stack 12 via the oxidant gas supply passage 106. The oxidant gas that has not reacted inside the fuel cell stack 12 is discharged as oxidant off-gas from the oxidant gas discharge port 12d of the fuel cell stack 12. The oxidant off-gas contains each component contained in the oxidant gas and moisture generated by the reaction of oxygen and hydrogen.

[0040] The oxidant off-gas is discharged to the diluter 121 via the oxidant gas discharge passage 108. The oxidant off-gas contains moisture. In the humidifier 114, a part of the moisture contained in the oxidant off-gas is used to humidify the oxidant gas flowing through the humidifier supply passage 114A.

[0041] ​[2-3 Fluid Flow in Cooling System 20] The pump 126 discharges the refrigerant toward the refrigerant supply port 12e of the fuel cell stack 12. The refrigerant discharged from the pump 126 is supplied to the refrigerant supply port 12e of the fuel cell stack 12 via the refrigerant supply passage 122. The refrigerant that has flowed through the inside of the fuel cell stack 12 is discharged from the refrigerant discharge port 12f of the fuel cell stack 12. The refrigerant discharged from the refrigerant discharge port 12f is supplied to the radiator 128 via the refrigerant discharge passage 124. The refrigerant that has dissipated heat in the radiator 128 reaches the pump 126.

[0042] Note that a part of the refrigerant discharged from the refrigerant discharge port 12f does not flow into the radiator 128 and flows into the refrigerant supply passage 122 via the diversion passage 125. This inflow amount is adjusted according to the opening degree of the diversion valve 132.

[0043] [3 Power Generation Control] The power generation control unit 150 controls the operations of the injector 94, the compressor 112, the pump 126, each valve, etc., to cause the power generation cell 28 to generate power.

[0044] More specifically, when the reception unit 140 receives a system start command, which is a command for starting the fuel cell system 10, the power generation control unit 150 opens the first sealing valve 116 and the second sealing valve 118. Thereafter, the power generation control unit 150 controls the injector 94, the compressor 112, and the bypass valve 119 so that the power generation power of the power generation cell 28 becomes the required power generation power. The required power generation power is calculated by the power generation control unit 150 based on, for example, the accelerator opening degree, the vehicle speed, the road gradient, etc. When the reception unit 140 receives a system stop command, which is a command for stopping the fuel cell system 10, the power generation control unit 150 closes the first sealing valve 116 and the second sealing valve 118. Further, the power generation control unit 150 stops the injector 94 and the compressor 112.

[0045] Note that the system startup command is supplied when the switch (startup switch) of the fuel cell system 10 is turned on. The system stop command is supplied when the switch of the fuel cell system 10 is turned off. The switch of the fuel cell system 10 corresponds to the ignition switch of the vehicle.

[0046] [4 Idle Control] When the reception unit 140 receives a power generation stop command during vehicle operation with the ignition switch on, the idle control unit 152 executes idle control. The power generation stop command is a command to stop the power generation of the power generation cell 28 while the fuel cell system 10 is operating. FIG. 2 is a diagram showing the fuel cell system 10 when the idle control is executed.

[0047] In the idle control, the idle control unit 152 closes the first sealing valve 116 and the second sealing valve 118 without stopping the compressor 112 and without closing the bypass valve 119. Therefore, the oxidant gas output from the compressor 112 to the oxidant gas supply path 106 flows into the oxidant gas discharge path 108 through the bypass path 110 without being supplied to the fuel cell stack 12. As a result, the power generation of the power generation cell 28 is stopped while the fuel cell system 10 is operating. Note that in the idle control, the idle control unit 152 continues to supply the fuel gas to the fuel gas supply path 84 without stopping the injector 94. Thereby, it is suppressed that a relatively high voltage is generated between the anode electrode 38 and the cathode electrode 40.

[0048] In idle control, the opening degree of the bypass valve 119 and the rotational speed of the compressor 112 are set to predetermined values. That is, the idle control unit 152 sets the opening degree of the bypass valve 119 to a first opening degree smaller than the maximum opening degree. Further, the idle control unit 152 sets the rotational speed of the compressor 112 to a predetermined rotational speed lower than the rotational speed during power generation. More specifically, the idle control unit 152 sets the rotational speed of the compressor 112 to be lower than the rotational speed corresponding to the upper limit value of the allowable noise level in the compressor 112 (noise generation upper limit rotational speed). Note that the predetermined rotational speed may be the lowest rotational speed at which the compressor 112 can rotate stably.

[0049] When the reception unit 140 receives a power consumption command that requests consumption of the power stored in the battery 26A during the execution of idle control, the idle control unit 152 changes the settings of the opening degree of the bypass valve 119 and the rotational speed of the compressor 112. More specifically, the idle control unit 152 changes the setting of the opening degree of the bypass valve 119 from the first opening degree described above to a second opening degree larger than the first opening degree. The second opening degree may be the maximum opening degree. Further, the idle control unit 152 changes the setting of the rotational speed of the compressor 112 from the predetermined rotational speed described above to a rotational speed larger than the predetermined rotational speed. Note that the power consumption command is supplied when the remaining capacity stored in the battery 26A is equal to or more than a predetermined remaining capacity threshold value.

[0050] FIG. 3 is a flowchart showing the procedure of the idle control process. FIG. 4 is a time chart showing the behavior of the fuel cell system 10 during the idle control process. When the reception unit 140 receives a power generation stop command in step S1, the idle control process proceeds to step S2.

[0051] In step S2, the idle control unit 152 closes the first sealing valve 116 and the second sealing valve 118. When the first sealing valve 116 and the second sealing valve 118 are closed, the idle control process proceeds to step S3.

[0052] In step S3, the idle control unit 152 sets the opening degree of the bypass valve 119 to the first opening degree. When the opening degree of the bypass valve 119 is set, the idle control process proceeds to step S4.

[0053] In step S4, the idle control unit 152 sets the rotational speed of the compressor 112 to a predetermined rotational speed lower than the rotational speed during power generation. The predetermined rotational speed is lower than the rotational speed corresponding to the upper limit value of the allowable noise level in the compressor 112 (noise generation upper limit rotational speed). Therefore, the flow rate of the oxidant gas output from the compressor 112 to the oxidant gas supply passage 106 becomes less than the flow rate (noise generation upper limit flow rate) LFR corresponding to the upper limit value of the allowable noise level in the compressor 112 (see FIG. 4). When the rotational speed of the compressor 112 is set, the idle control process proceeds to step S5.

[0054] In step S5, the idle control unit 152 determines whether the reception unit 140 has received a power consumption command. If the reception unit 140 has not received a power consumption command, the idle control process remains at step S5. On the other hand, if the reception unit 140 has received a power consumption command, the idle control process proceeds to step S6.

[0055] In step S6, the idle control unit 152 changes the setting of the opening degree of the bypass valve 119 from the first opening degree set in step S2 to the second opening degree. Also, the idle control unit 152 changes the setting of the rotational speed of the compressor 112 from the predetermined rotational speed set in step S4 to a rotational speed greater than the predetermined rotational speed. As a result, the flow rate of the oxidant gas output from the compressor 112 to the oxidant gas supply passage 106 increases (see FIG. 4). Along with this, the power consumption of the compressor 112 increases. When the setting of the opening degree of the bypass valve 119 and the rotational speed of the compressor 112 are changed, the idle control process proceeds to step S7.

[0056] In step S7, the idle control unit 152 determines whether the supply of the power generation stop command continues. When the reception unit 140 continues to receive the power generation stop command, the idle control unit 152 determines that the supply of the power generation stop command continues. In this case, the idle control process remains at step S7. When the reception unit 140 does not receive the power generation stop command, the idle control unit 152 determines that the supply of the power generation stop command does not continue. In this case, the idle control process ends.

[0057] [5 Effects of the above embodiment] When the control device 22 receives the power generation stop command while the vehicle is operating (during vehicle operation), the control device 22 sets the rotational speed of the compressor 112 to a predetermined rotational speed lower than the rotational speed during power generation.

[0058] At this time, the control device 22 closes the first sealing valve 116 and the second sealing valve 118 without closing the bypass valve 119. However, when the bypass valve 119 is at its maximum opening, the pressure loss is low, so even if the rotational speed of the compressor 112 is set low, the oxidant gas easily flows. As a result, there is a possibility that noise is generated from the compressor 112. In contrast, the control device 22 of the present embodiment sets the opening degree of the bypass valve 119 to a first opening degree smaller than the maximum opening degree. Thereby, compared with the case where the bypass valve 119 is at its maximum opening, the noise generated from the compressor 112 can be satisfactorily reduced. Also, the startup time of the compressor 112 can be shortened.

[0059] Even though the oxidant gas is in a state where it is relatively difficult to flow, if the rotational speed of the compressor 112 is increased, there is a possibility that the compressor 112 is damaged. In contrast, when the control device 22 of the present embodiment receives the power consumption command, the control device 22 changes the setting of the opening degree of the bypass valve 119 to a second opening degree larger than the first opening degree. Also, when the control device 22 receives the power consumption command, the control device 22 changes the setting of the rotational speed of the compressor 112 to a rotational speed larger than the predetermined rotational speed. Thereby, while suppressing damage to the compressor 112, power can be consumed by the compressor 112.

[0060] [6 Modifications of the Above Embodiment] The above embodiment may be modified as follows.

[0061] (Modification 1) In this modification, the power consumption command specifies the amount of power to be consumed from the battery 26A. In the case of this modification, in step S5 above, the idle control unit 152 changes the setting of the opening degree (second opening degree) of the bypass valve 119 according to the amount of power specified by the power consumption command. In this case, the larger the amount of power specified by the power consumption command, the larger the opening degree (second opening degree) of the bypass valve 119 is set. According to this modification, damage to the compressor 112 can be suppressed.

[0062] (Modification 2) In this modification, the power consumption command specifies the amount of power to be consumed from the battery 26A. In the case of this modification, in step S5 above, the idle control unit 152 changes the setting of the rotational speed of the compressor 112 according to the amount of power specified by the power consumption command. In this case, the larger the amount of power specified by the power consumption command, the larger the rotational speed of the compressor 112 is set. According to this modification, the power of the battery 26A can be consumed in a generally constant period regardless of the amount of power specified by the power consumption command. Note that this modification may be combined with the above Modification 1.

[0063] (Modification 3) Either the first sealing valve 116 or the second sealing valve 118 may not be provided. Even in this case, the same effects as those of the above embodiment can be obtained.

[0064] [7 Supplementary Note] Regarding the above disclosure, the following supplementary note is further disclosed.

[0065] (Supplementary Note 1) The present disclosure relates to a control device (22) provided in a fuel cell system (10) having a fuel cell stack (12) including a power generation cell (28), a battery (26A) for storing the generated power of the power generation cell, an oxidant gas supply passage (106) connected to the fuel cell stack, an oxidant gas discharge passage (108) connected to the fuel cell stack, a bypass passage (110) having one end connected to the oxidant gas supply passage and the other end connected to the oxidant gas discharge passage, a compressor (112) for supplying oxidant gas to the oxidant gas supply passage, at least one shutoff valve (116, 118) provided in at least one of the oxidant gas supply passage between the connection portion (CP1) to which one end of the bypass passage is connected and the fuel cell stack and the oxidant gas discharge passage between the connection portion (CP2) to which the other end of the bypass passage is connected and the fuel cell stack, and a bypass valve (119) provided in the bypass passage and having an adjustable opening degree. The control device includes a reception unit (140) for receiving a command and a control unit (142) for performing control based on the command. When the reception unit receives a power generation stop command for stopping power generation of the power generation cell while maintaining the operating state of the fuel cell system, the control unit closes the shutoff valve, sets the opening degree of the bypass valve to a first opening degree smaller than the maximum opening degree, and sets the rotational speed of the compressor to a predetermined rotational speed lower than the rotational speed during power generation of the power generation cell.

[0066] When the shutoff valve is closed and the rotational speed of the compressor is set to a predetermined rotational speed lower than the rotational speed during power generation, the pressure loss is low when the bypass valve is at the maximum opening degree. Therefore, even when the rotational speed of the compressor is set low, the oxidant gas easily flows, and there is a risk of noise generation from the compressor. In the present disclosure, the opening degree of the bypass valve is set to a first opening degree smaller than the maximum opening degree. Thereby, the noise generated from the compressor can be satisfactorily reduced as compared with the case where the bypass valve is at the maximum opening degree.

[0067] (Appendix 2) The control device according to Supplementary Note 1, wherein in a state where the opening degree of the bypass valve is set to the first opening degree and the rotational speed of the compressor is set to the predetermined rotational speed, when the receiving unit receives a power consumption command for requesting consumption of the power stored in the battery, the control unit may change the setting of the opening degree of the bypass valve to a second opening degree larger than the first opening degree and change the setting of the rotational speed to the rotational speed larger than the predetermined rotational speed.

[0068] Accordingly, even when a power consumption command is received while the power generation of the power generation cell is stopped in a state where the fuel cell system is operating, it is possible to consume power in the compressor while suppressing damage to the compressor.

[0069] (Supplementary Note 3) The control device according to Supplementary Note 1, wherein the predetermined rotational speed may be a rotational speed lower than the rotational speed corresponding to the upper limit value of the noise level allowed in the compressor.

[0070] Accordingly, it is possible to satisfactorily reduce the noise generated from the compressor.

[0071] (Supplementary Note 4) The control device according to Supplementary Note 2, wherein the control unit may change the setting of the opening degree of the bypass valve according to the amount of power specified by the power consumption command.

[0072] According to the above, damage to the compressor 112 can be suppressed.

[0073] (Supplementary Note 5) The control device according to Supplementary Note 2, wherein the control unit may change the setting of the rotational speed according to the amount of power specified by the power consumption command.

[0074] According to the above, regardless of the amount of power specified by the power consumption command, it is possible to consume the power of the battery in a substantially constant period.

[0075] (Appendix 6) The present disclosure relates to a fuel cell system including the control device described in any one of Appendices 1 to 5.

[0076] Note that the present invention is not limited to the above-described disclosure, and various configurations can be adopted without departing from the gist of the present invention.

Explanation of Reference Numerals

[0077] 10…Fuel cell system 12…Fuel cell stack 20…Cooling system 22…Control device 26A…Battery 28…Power generation cell 106…Oxidant gas supply passage 108…Oxidant gas discharge passage 110…Bypass passage 112…Compressor 116…First shutoff valve 118…Second shutoff valve 119…Bypass valve 140…Reception unit 142…Control unit 150…Power generation control unit 152…Idle control unit

Claims

1. A fuel cell stack including a power generation cell, a battery for storing the generated power of the power generation cell, an oxidant gas supply passage connected to the fuel cell stack, an oxidant gas discharge passage connected to the fuel cell stack, a bypass passage having one end connected to the oxidant gas supply passage and the other end connected to the oxidant gas discharge passage, a compressor for supplying oxidant gas to the oxidant gas supply passage, at least one shutoff valve provided in at least one of the oxidant gas supply passage between the connection portion where one end of the bypass passage is connected and the fuel cell stack and the oxidant gas discharge passage between the connection portion where the other end of the bypass passage is connected and the fuel cell stack, a bypass valve provided in the bypass passage and having an adjustable opening degree, A control device provided in a fuel cell system having: a reception unit that receives a command; a control unit that performs control based on the command and comprising: When the reception unit receives a power generation stop command for stopping the power generation of the power generation cell in a state where the fuel cell system is operating, the control unit closes the shutoff valve, sets the opening degree of the bypass valve to a first opening degree smaller than the maximum opening degree, and sets the rotation speed of the compressor to a predetermined rotation speed lower than the rotation speed during the power generation of the power generation cell.

2. The control device according to claim 1, wherein, when the reception unit receives a power consumption command for requesting consumption of the power stored in the battery in a state where the opening degree of the bypass valve is set to the first opening degree and the rotation speed of the compressor is set to the predetermined rotation speed, the control unit changes the setting of the opening degree of the bypass valve to a second opening degree larger than the first opening degree and changes the setting of the rotation speed to a rotation speed higher than the predetermined rotation speed.

3. The control device according to claim 1, wherein the predetermined rotation speed is a rotation speed lower than a rotation speed corresponding to an upper limit value of a noise level allowed in the compressor.

4. The control device according to claim 2, wherein the control unit changes the setting of the opening degree of the bypass valve according to the amount of power specified by the power consumption command.

5. The control device according to claim 2, The control unit is a control device that changes the setting of the rotational speed according to the amount of electric power specified by the electric power consumption command. **Claim 6** A fuel cell system comprising the control device according to any one of claims 1 to 5.

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