JP5164020B2 - Fuel cell system and starting method thereof - Google Patents

Description

  The present invention relates to a fuel cell system and a starting method thereof. More specifically, the present invention relates to an improvement in processing at the start-up of the fuel cell system.

  In general, a fuel cell (for example, a polymer electrolyte fuel cell) is configured by stacking a plurality of cells each having an electrolyte sandwiched between separators. In addition to such a fuel cell, fuel is supplied by a piping system for supplying and discharging reaction gas (hydrogen gas and air) to the fuel cell, a power system for charging and discharging power, a control system for overall control of the system, and the like. A battery system is configured.

  Some of such fuel cell systems undergo a so-called start-up inspection (start-up check) when the system is started (see, for example, Patent Document 1). In the start-up inspection, for example, the pressure drop of hydrogen gas is monitored at the time of system start-up, and leakage of the hydrogen gas is detected.

By the way, if a current is consumed during the start-up inspection, the fuel (hydrogen gas) is consumed accordingly and the pressure is lowered, which may lead to erroneous detection of hydrogen leakage. On the other hand, if current is not allowed to flow during start-up inspection, the fuel cell may become an open-circuit voltage or open-circuit voltage (OCV) from the start of fuel supply to the completion of start-up inspection, which may lead to deterioration (in general, In such a fuel cell, the voltage tends to decrease as the current increases. In particular, the fuel cell voltage when the fuel cell current decreases and reaches 0 is referred to as an open circuit voltage in this specification). One of the processes that can solve the problem of erroneous detection of hydrogen leakage and deterioration of the fuel cell at the same time is to prevent air from being supplied to the fuel cell after the hydrogen leakage detection is completed so that an open voltage state is not obtained. The thing to do is mentioned.
JP 2006-339080 A

  However, such processing takes time when the system is started.

  In view of the above, an object of the present invention is to provide a fuel cell system and a start method thereof that can reduce the time required for starting the system while suppressing erroneous detection of hydrogen leakage and deterioration of the fuel cell.

  In order to solve this problem, the present inventor has made various studies. For example, when air is supplied to the fuel cell by a compressor, a certain amount of time is required until the air supply reaches a specified amount after the compressor is started. Further, as described above, since this operation is performed after the completion of the hydrogen leak detection, the time required for starting the system is increased accordingly. From these viewpoints, the present inventor who has repeatedly studied focusing on shortening the start-up time has obtained new knowledge that leads to the solution of such problems.

  The starting method of the fuel cell system according to the present invention is based on such knowledge, and includes a fuel cell that generates electric power by an electrochemical reaction between the fuel gas and the oxidizing gas, and an oxidizing gas supply path for supplying the oxidizing gas to the fuel cell. An oxidizing gas supply device for sending an oxidizing gas to the oxidizing gas supply path, an oxidizing off gas discharge path for discharging the oxidizing off gas from the fuel cell, an oxidizing gas supply path cutoff valve provided in the oxidizing gas supply path, An oxidation off-gas discharge passage cutoff valve provided in the oxidation off-gas discharge passage, an oxidation gas bypass passage connecting the oxidation gas supply passage and the oxidation off-gas discharge passage, and a fuel cell bypass valve provided in the oxidation gas bypass passage; A start method of the system in a fuel cell system comprising: an oxidant gas supply passage shut-off valve and an oxidant off-gas exhaust when the system is started Close the shutoff valve and open the fuel cell bypass valve, bypass the oxidant gas fed by the oxidant gas supply device to the oxidant gas bypass flow path, perform the start-up inspection of the system, and complete the start-up inspection. The gas supply path shut-off valve and the oxidizing off-gas discharge path shut-off valve are opened, the fuel cell bypass valve is closed, and the oxidizing gas is supplied to the fuel cell.

  In this start-up method, the start-up inspection is performed in a state where supply oxidant gas (for example, air) sent to the fuel cell is bypassed to the oxidant gas bypass passage. According to this, it is possible to avoid an electrochemical reaction in the fuel cell and to suppress current consumption and fuel (hydrogen gas) consumption during start-up inspection. Detection can be avoided. In addition, the start-up inspection is performed in a state where the supply oxidizing gas is bypassed to avoid the occurrence of an electrochemical reaction, and after the start-up inspection is completed, the oxidizing gas is supplied to the fuel cell. Can be prevented from becoming an open circuit voltage state.

  Moreover, in the starting method according to the present invention, the oxidizing gas supply device is continuously operated while bypassing the oxidizing gas during the start-up inspection. For this reason, if the oxidizing gas path is switched after completion of the start-up inspection, the supply amount to the fuel cell reaches the specified flow rate within a relatively short time. Therefore, it is possible to shorten the processing time required for starting the system.

  The start-up inspection in the above-described start method detects, for example, whether or not fuel gas leaks in the fuel cell system. In this case, it is preferable to inspect the leakage of the fuel gas based on the monitoring result of the pressure drop of the fuel gas.

  In addition, a fuel cell system according to the present invention includes a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidizing gas, an oxidizing gas supply path for supplying the oxidizing gas to the fuel cell, and an oxidizing gas supply path. An oxidant gas supply device for sending oxidant gas, an oxidant off gas discharge passage for discharging the oxidant off gas from the fuel cell, an oxidant gas supply passage shut-off valve provided in the oxidant gas supply passage, and an oxidant off gas discharge passage. An oxidant-off gas discharge passage shut-off valve, an oxidant gas bypass passage connecting the oxidant gas supply passage and the oxidant off-gas exhaust passage, and a fuel cell bypass valve provided in the oxidant gas bypass passage, and starting the system At that time, the oxidant gas supply path shut-off valve and the oxidant off-gas exhaust path shut-off valve are closed and the fuel cell bypass valve is opened and fed by the oxidant gas supply device The oxidant gas is bypassed to the oxidant gas bypass flow path, and after completion of the system start-up inspection, the oxidant gas supply path shut-off valve and the oxidant off-gas discharge path shut-off valve are opened, and the fuel cell bypass valve is closed. The oxidant gas is controlled to be supplied to the fuel cell.

  According to the present invention, it is possible to reduce the time required for system startup while suppressing erroneous detection of hydrogen leakage and deterioration of the fuel cell.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings. In the following, the overall configuration of the fuel cell system 1 including the fuel cell 2 and the like will be described first, and then the configuration and processing contents for the start-up inspection in the fuel cell system 1 will be described.

  FIG. 1 shows a schematic configuration of the fuel cell system 1. The fuel cell system 1 is applicable as, for example, an on-vehicle power generation system of a fuel cell vehicle (FCHV), but is not particularly limited to this. ) And robots can also be applied as a power generation system mounted on a self-propelled device.

  The fuel cell system 1 in the present embodiment includes a fuel cell 2 that generates electric power by an electrochemical reaction upon receiving supply of reaction gas (oxidation gas and fuel gas), and an oxidation that supplies air as the oxidation gas to the fuel cell 2. A gas piping system 3, a fuel gas piping system 4 for supplying hydrogen gas as a fuel gas to the fuel cell 2, a refrigerant piping system 5 for supplying a refrigerant to the fuel cell 2 and cooling the fuel cell 2, and a system An electric power system 6 that charges and discharges electric power and a control unit 7 that performs overall control of the entire system are provided.

  The fuel cell 2 is, for example, a polymer electrolyte fuel cell, and has a stack structure in which a large number of single cells are stacked. The single cell has an air electrode on one surface of an electrolyte composed of an ion exchange membrane, a fuel electrode on the other surface, and a structure having a pair of separators so as to sandwich the air electrode and the fuel electrode from both sides. It has become. In this case, the fuel gas is supplied to the fuel gas flow path of one separator, the oxidizing gas is supplied to the oxidizing gas flow path of the other separator, and electric power is generated by the chemical reaction of these reaction gases. The fuel cell 2 is provided with a current sensor 2a for detecting a current during power generation (see FIG. 1).

  The oxidizing gas piping system 3 has an air supply passage 11 through which oxidizing gas supplied to the fuel cell 2 flows, and an exhaust passage 12 through which oxidizing off-gas discharged from the fuel cell 2 flows. The air supply flow path 11 is provided with an air compressor 14 as an oxidizing gas supply device that takes in the oxidizing gas through the filter 13 and a humidifier 15 that humidifies the oxidizing gas fed by the air compressor 14. . The air compressor 14 takes in the oxidizing gas in the atmosphere by driving a motor (not shown). Further, the oxidizing off gas flowing through the exhaust passage 12 passes through the back pressure regulating valve 16 and is subjected to moisture exchange by the humidifier 15, and is finally exhausted into the atmosphere outside the system as exhaust gas.

  The fuel gas piping system 4 includes a fuel tank 21 as a hydrogen supply source, a hydrogen supply passage 22 through which hydrogen gas supplied from the fuel tank 21 to the fuel cell 2 flows, and hydrogen off-gas (fuel) discharged from the fuel cell 2. Off-gas) to the junction A1 of the hydrogen supply flow path 22, a hydrogen pump 24 for pumping the hydrogen off-gas in the circulation flow path 23 to the hydrogen supply flow path 22, and a branch to the circulation flow path 23 And an exhaust drainage flow path 25 connected thereto.

  The fuel tank 21 is composed of, for example, a high-pressure tank or a hydrogen storage alloy and is mounted on the fuel cell vehicle in the present embodiment, and is configured to be able to store, for example, 35 MPa hydrogen gas. When a shut-off valve 26 described later is opened, hydrogen gas flows out from the fuel tank 21 to the hydrogen supply passage 22. The hydrogen gas is finally depressurized to about 200 kPa, for example, by a regulator 27 and an injector 28 described later, and supplied to the fuel cell 2.

  The hydrogen supply channel 22 is provided with a shutoff valve 26 that shuts off or allows the supply of hydrogen gas from the fuel tank 21, a regulator 27 that adjusts the pressure of the hydrogen gas, and an injector 28. A pressure sensor 29 that detects the pressure of the hydrogen gas in the hydrogen supply flow path 22 is provided on the downstream side of the injector 28 and upstream of the junction A1 between the hydrogen supply flow path 22 and the circulation flow path 23. It has been. Further, a pressure sensor and a temperature sensor (not shown) for detecting the pressure and temperature of the hydrogen gas in the hydrogen supply flow path 22 are provided on the upstream side of the injector 28. Information regarding the gas state (pressure, temperature) of the hydrogen gas detected by the pressure sensor 29 or the like is used for feedback control and purge control of an injector 28 described later.

  The regulator 27 is a device that regulates the upstream pressure (primary pressure) to a preset secondary pressure. In this embodiment, a mechanical pressure reducing valve that reduces the primary pressure is employed as the regulator 27. The mechanical pressure reducing valve has a structure in which a back pressure chamber and a pressure adjusting chamber are formed with a diaphragm therebetween, and the primary pressure is reduced to a predetermined pressure in the pressure adjusting chamber by the back pressure in the back pressure chamber. Thus, a publicly known configuration for the secondary pressure can be employed.

  The injector 28 is an electromagnetically driven on-off valve capable of adjusting the gas flow rate and gas pressure by driving the valve body directly with a predetermined driving cycle with an electromagnetic driving force and separating it from the valve seat. The injector 28 includes a valve seat having an injection hole for injecting gaseous fuel such as hydrogen gas, a nozzle body for supplying and guiding the gaseous fuel to the injection hole, and an axial direction (gas flow direction) with respect to the nozzle body. And a valve body that is movably accommodated and opens and closes the injection hole. In the present embodiment, such an injector 28 is arranged on the upstream side of the junction A1 between the hydrogen supply channel 22 and the circulation channel 23 (see FIG. 1). In addition, as shown by a broken line in FIG. 1, when a plurality of fuel tanks 21 are used as a fuel supply source, a portion where hydrogen gas supplied from these fuel tanks 21 merges (hydrogen gas joining portion A2). The injector 28 is arranged on the downstream side.

  An exhaust / drain channel 25 is connected to the circulation channel 23 via a gas / liquid separator 30 and an exhaust / drain valve 31. The gas-liquid separator 30 collects moisture from the hydrogen off gas. The exhaust / drain valve 31 operates in response to a command from the control unit 7, so that moisture collected by the gas-liquid separator 30 and hydrogen off-gas (fuel off-gas) containing impurities in the circulation channel 23 are externally provided. It is to be discharged (purged). When the exhaust / drain valve 31 is opened, the concentration of impurities in the hydrogen off-gas in the circulation passage 23 decreases and the concentration of hydrogen in the hydrogen off-gas supplied in circulation increases. An upstream pressure sensor 32 and a downstream pressure sensor 33 for detecting the pressure of the hydrogen off gas are provided at the upstream position (on the circulation flow path 23) and the downstream position (on the exhaust drain flow path 25) of the exhaust drain valve 31, respectively. It has been.

  The refrigerant piping system 5 includes a refrigerant channel 41 communicating with the cooling channel in the fuel cell 2, a cooling pump 42 provided in the refrigerant channel 41, and a radiator 43 that cools the refrigerant discharged from the fuel cell 2. And a temperature sensor 44 for detecting the temperature of the refrigerant discharged from the fuel cell 2. The cooling pump 42 circulates and supplies the refrigerant in the refrigerant passage 41 to the fuel cell 2 by driving a motor (not shown). The temperature of the refrigerant detected by the temperature sensor 44 (= temperature of hydrogen off-gas discharged from the fuel cell 2) is used for purge control described later.

  The power system 6 includes a high-voltage DC / DC converter 61, a battery 62, a traction inverter 63, a traction motor 64, various auxiliary machine inverters not shown, and the like. The high-voltage DC / DC converter 61 is a direct-current voltage converter, which adjusts the direct-current voltage input from the battery 62 and outputs it to the traction inverter 63 side, and the direct-current input from the fuel cell 2 or the traction motor 64. And a function of adjusting the voltage and outputting it to the battery 62. With such a function of the high voltage DC / DC converter 61, charging / discharging of the battery 62 is realized. Further, the output voltage of the fuel cell 2 is controlled by the high voltage DC / DC converter 61.

  The battery 62 is configured such that battery cells are stacked and a constant high voltage is used as a terminal voltage, and surplus power can be charged or power can be supplementarily supplied under the control of a battery computer (not shown). The traction inverter 63 converts a direct current into a three-phase alternating current and supplies it to the traction motor 64. The traction motor 64 is, for example, a three-phase AC motor, and constitutes a main power source of a fuel cell vehicle on which the fuel cell system 1 is mounted.

  The control unit 7 detects an operation amount of an operation member (accelerator or the like) for acceleration provided in the vehicle, and receives control information such as an acceleration request value (for example, a required power generation amount from a load device such as the traction motor 64). To control the operation of various devices in the system. In addition to the traction motor 64, the load device includes auxiliary devices (for example, motors for the air compressor 14, the hydrogen pump 24, the cooling pump 42, etc.) necessary for operating the fuel cell 2, and traveling of the vehicle. Electric power consuming devices including actuators used in various devices involved (transmission, wheel control unit, steering device, suspension device, etc.), air conditioners (air conditioners) in the passenger space, lighting, audio, and the like can be included.

  Such a control part 7 is comprised by the computer system which is not shown in figure. Such a computer system is provided with a CPU, ROM, RAM, HDD, input / output interface, display, and the like. The CPU reads various control programs recorded in the ROM and executes desired calculations to perform feedback control and purge. Various processes and controls such as control are performed.

  Next, the configuration and processing contents for performing the start-up inspection in the fuel cell system 1 as described above will be described (see FIGS. 2 to 4).

  The oxidizing gas piping system 3 of the fuel cell system 1 is provided with an oxidizing gas bypass passage 8 that connects an air supply passage (oxidizing gas supply passage) 11 and an exhaust passage (oxidation off-gas discharge passage) 12. The oxidizing gas bypass channel 8 is provided with a fuel cell bypass valve 17 that opens and closes the oxidizing gas bypass channel 8 (see FIG. 2). The air supply passage 11 is provided with an inlet shut-off valve (oxidation gas supply passage shut-off valve) 18, and the exhaust passage 12 is provided with an outlet shut-off valve (oxidation off-gas discharge passage shut-off valve) 19 (see FIG. 2). ). The inlet shut-off valve 18 is a shut-off valve that can shut off the air supply passage 11, and the outlet shut-off valve 19 is a shut-off valve that can shut off the exhaust passage 12. By adjusting the opening degree of these various valves (fuel cell bypass valve 17, inlet shutoff valve 18, outlet shutoff valve 19), the flow rate (flow rate ratio) of the oxidizing gas flowing through the air supply passage 11 and the oxidizing gas bypass passage 8 is adjusted. ) And the supply amount of the oxidizing gas to the fuel cell 2 can be appropriately changed.

  Reference numeral 82 denotes a humidity sensor 82 provided on the air supply channel 11 as a device for measuring the timing of channel switching by the fuel cell bypass valve 17 and the inlet shut-off valve 18 described above. The humidity sensor 82 is provided, for example, between the inlet shutoff valve 18 and the fuel cell 2, and can detect the humidity in the humidifier 15 (or the humidity in the flow path from 15 to the fuel cell 2). It has become.

  Although not particularly shown, the fuel cell system 1 of the present embodiment includes an FC relay. The FC relay switches connection / disconnection between the fuel cell 2 and the various load devices described above under the control of the control unit 7.

  Next, processing contents at the time of start-up inspection in the fuel cell system 1 having the above-described configuration will be described (see FIG. 3).

  When the fuel cell system 1 is started, processing associated with the start-up inspection is started (step S1). At this time, first, the fuel cell bypass valve 17 is opened, the inlet shut-off valve (oxidizing gas supply passage shut-off valve) 18 and the outlet shut-off valve (oxidizing off-gas discharge passage shut-off valve) 19 are closed (step S2), and the air compressor 14 sends the fuel. The oxidizing gas to be bypassed is bypassed by the oxidizing gas bypass passage 8.

  Next, the start-up inspection of the fuel cell system 1 is performed (step S3). The start-up inspection detects, for example, whether fuel gas leaks in the fuel cell system 1. The leakage of the fuel gas can be inspected based on the monitoring result of the pressure drop of the fuel gas by the pressure sensor 29 or the like.

  After completion of the start-up inspection (YES in step S4), the fuel cell bypass valve 17 is closed, the inlet cutoff valve 18 and the outlet cutoff valve 19 are opened (step S5), and the oxidizing gas is supplied to the fuel cell 2. This completes the process associated with the start-up inspection of the fuel cell system 1 (step S6).

  Further, the above processing contents will be described with reference to a time chart (see FIG. 4).

  First, in the fuel cell system 1 at the stage before receiving the start command, the voltage (FC voltage) of the fuel cell 2 is 0, and hydrogen is not supplied. Moreover, regarding the air supply system, an inlet shut-off valve (inlet SV in FIG. 4) 18, an outlet shut-off valve (exit SV in FIG. 4) 19, and a fuel cell bypass valve (FC bypass valve in FIG. 4) 17 are all included. In the closed state, the air compressor 14 is not operating. Further, the FC relay for switching connection / disconnection between the fuel cell 2 and various load devices is open, and the voltage command from the control unit 7 is 0V. The start check has not started.

  Here, the fuel cell system 1 that has received the start command starts a start-up inspection (start check). At this time, the hydrogen supply is disclosed by opening the shutoff valve 26 and the like. Further, the fuel cell bypass valve (FC bypass valve) 17 is opened with the inlet shutoff valve (inlet SV) 18 and outlet shutoff valve (outlet SV) 19 closed, and the operation of the air compressor 14 is started, and the oxidizing gas bypass flow path 8 To bypass the oxidizing gas. Simultaneously with these operations, the FC relay is closed.

  When the start-up inspection is completed, the inlet cutoff valve (inlet SV) 18 and the outlet cutoff valve (outlet SV) 19 are opened, and then the fuel cell bypass valve (FC bypass valve) 17 is closed. As a result, the supply path of the oxidizing gas is switched, the oxidizing gas is supplied to the fuel cell 2, and the voltage (FC voltage) of the fuel cell 2 rises due to an electrochemical reaction.

  According to the starting method of the present embodiment in accordance with the above-described time chart, the start-up inspection (with the supply oxidizing gas (air) sent toward the fuel cell 2 bypassed to the oxidizing gas bypass flow path 8 ( Therefore, it is possible to avoid an electrochemical reaction in the fuel cell 2 and to suppress current consumption and hydrogen gas consumption during the start-up inspection. Therefore, it is possible to suppress a pressure drop caused by the consumption of hydrogen gas and to avoid erroneous detection of hydrogen leakage.

  Further, in the present embodiment, during the start-up inspection, the oxidation gas is bypassed to avoid an electrochemical reaction, and when the start-up inspection is completed, the valves are switched and the oxidant gas is immediately sent to the fuel cell 2. To send it to. That is, for example, since the oxidizing gas (air) is supplied after the hydrogen leak detection is completed, the open-circuit voltage in the fuel cell 2 can be suppressed (see (a) in FIG. 4).

  Moreover, in the starting method of the present embodiment, the air compressor 14 is continuously operated while the oxidizing gas is bypassed during the start-up inspection. For this reason, after the start-up inspection is completed, the oxidizing gas supply amount to the fuel cell 2 can reach the specified flow rate within a relatively short time by switching the oxidizing gas path. Therefore, it is possible not to cause a delay in air supply, and to shorten the processing time required at the time of starting the system (see (b) in FIG. 4).

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the example in which the oxidizing gas bypass channel 8 is arranged on the front side of the humidifier 15 (the side opposite to the fuel cell 2) is shown, but this is only an example, and the arrangement of the oxidizing bypass channel 8 is shown. The connection method is not particularly limited.

It is a figure which shows the structural example of the fuel cell system concerning this invention. It is a figure which shows the structural example of the oxidizing gas piping system in this embodiment. It is a flowchart which shows an example of the processing content at the time of the test | inspection at the time of starting in a fuel cell system. It is a time chart which shows an example of the processing content at the time of the test | inspection at the time of starting in a fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel cell, 8 ... Oxidation gas bypass flow path, 11 ... Air supply flow path (oxidation gas supply path), 12 ... Exhaust flow path (oxidation off-gas discharge path), 14 ... Air compressor (oxidation) Gas supply device), 17 ... Fuel cell bypass valve, 18 ... Inlet shut-off valve (oxidation gas supply path shut-off valve), 19 ... Outlet shut-off valve (oxidation off-gas discharge path shut-off valve)

Claims (4)

A fuel cell that generates electric power by an electrochemical reaction of fuel gas and oxidant gas; an oxidant gas supply passage for supplying oxidant gas to the fuel cell; an oxidant gas supply device that feeds oxidant gas into the oxidant gas supply passage; An oxidation off-gas discharge path for discharging the oxidation off-gas from the fuel cell; an oxidation gas supply path cutoff valve provided in the oxidation gas supply path; and an oxidation off-gas discharge path cutoff valve provided in the oxidation off-gas discharge path; An oxidizing gas bypass passage connecting the oxidizing gas supply passage and the oxidizing off-gas discharge passage; a fuel cell bypass valve provided in the oxidizing gas bypass passage;
A method for starting the system in a fuel cell system comprising:
When starting the system, close the oxidizing gas supply passage shutoff valve and the oxidizing offgas discharge passage shutoff valve and open the fuel cell bypass valve,
Bypass the oxidizing gas fed by the oxidizing gas supply device to the oxidizing gas bypass flow path,
Performing a start-up test to detect whether the fuel gas is leaking in the system;
A fuel cell system starting method for opening an oxidizing gas supply passage shut-off valve and an oxidizing off-gas discharge passage shut-off valve, closing the fuel cell bypass valve, and supplying oxidizing gas to the fuel cell after completion of the start-up inspection. The leakage of the fuel gas, the method of starting the fuel cell system of claim 1, inspected on the basis of the monitoring result of the pressure drop of the fuel gas. A fuel cell that generates electric power by an electrochemical reaction of fuel gas and oxidant gas; an oxidant gas supply passage for supplying oxidant gas to the fuel cell; an oxidant gas supply device that feeds oxidant gas into the oxidant gas supply passage; An oxidation off-gas discharge path for discharging the oxidation off-gas from the fuel cell; an oxidation gas supply path cutoff valve provided in the oxidation gas supply path; and an oxidation off-gas discharge path cutoff valve provided in the oxidation off-gas discharge path; An oxidizing gas bypass passage connecting the oxidizing gas supply passage and the oxidizing off-gas discharge passage, and a fuel cell bypass valve provided in the oxidizing gas bypass passage,
At the time of starting the system, the oxidizing gas supply passage cutoff valve and the oxidizing off gas discharge passage cutoff valve are closed, the fuel cell bypass valve is opened, and the oxidizing gas fed by the oxidizing gas supply device is supplied to the oxidizing gas bypass passage. And after completion of the start-up inspection for detecting whether or not the fuel gas leaks in the system , the oxidizing gas supply passage shut-off valve and the oxidizing off-gas discharge passage shut-off valve are opened, A fuel cell system that is controlled so that the fuel cell bypass valve is closed and oxidant gas is supplied to the fuel cell.   The fuel cell system according to claim 3, wherein the fuel gas leakage is inspected based on a monitoring result of a pressure drop of the fuel gas.

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