JP2005158552A - Fuel cell system and control method of fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of restraining carbon poisoning by sucking air staying in the cathode-side inside of a fuel cell to reduce an oxygen quantity in the cathode-side inside; and to provide its control method. <P>SOLUTION: This fuel cell system has: the fuel cell; a hydrogen supply means for supplying hydrogen to the anode-side inside of the fuel cell; an air supply means for supplying air to the cathode-side inside of the fuel cell; an air pressure regulation valve for regulating the pressure of the air discharged from the cathode-side inside; and a control means for controlling the air supply means and the air pressure regulation valve so that the pressure of at least a part of the air in the cathode-side inside is set negative in at least a part of a period until the fuel cell starts to generate power. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system and a control method thereof, and more particularly, to a control technique at the time of starting the fuel cell system.

  In recent years, fuel cells have attracted attention as highly efficient energy conversion devices. In particular, solid polymer fuel cells that use a solid polymer electrolyte membrane with proton conductivity as the electrolyte can be operated with a simple system because they have a compact structure and high power density. It is attracting attention not only as a distributed power source but also as a power source for automobiles and homes. In addition, fuel cells using proton conductive membranes other than solid polymer electrolyte membranes, direct methanol fuel cells, and the like are also in the spotlight. Among them, the fuel cell for automobiles has a global competition for development, such as a global alliance.

  In general, a polymer electrolyte fuel cell is a fuel cell system in which a fuel cell body that generates power by reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen is integrated with the peripheral system and peripheral devices. It is configured as. In the fuel cell main body, an electrode structure in which two gas diffusion electrodes corresponding to a fuel electrode (anode) and an oxidant electrode (cathode) are arranged on both surfaces of a solid polymer electrolyte membrane is a fuel gas and an oxidant on the anode and the cathode. It has a side-by-side laminated structure in which a plurality of layers are laminated via a separator having gas flow paths for supplying gas and a cooling plate through which an antifreeze liquid as a cooling medium flows.

Conventionally, a pair of electrode catalyst layers in which carbon particles (such as carbon black) carrying catalyst particles such as platinum are integrated by an ion conductive polymer binder containing fluorine in the molecular structure, and both electrode catalyst layers 2. Description of the Related Art An electrode structure for a polymer fuel cell is known that includes a polymer electrolyte membrane sandwiched between and a gas diffusion electrode corresponding to an anode and a cathode (see, for example, Patent Document 1).
JP 2002-373664 A (for example, paragraph [0022] and FIG. 1)

When the cathode and the anode are left without being connected to the load while the cathode and the anode are not connected at the time of stopping, or when hydrogen is started to be supplied to the anode at the start-up, the anode is in a state where hydrogen and oxygen are mixed. Then, proton H ⁺ moves from the anode to the cathode, and the transferred H ⁺ reacts with oxygen at the cathode to generate water. While being is required, electrons e because the load is not connected ^{- -} In this reaction the electrons e do not come move through the load. Therefore, water present on the cathode reacts with carbon on the electrolyte membrane (C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻ ), and electrons e ⁻ generated by this reaction are used for the cathode water generation reaction. At this time, carbon on the electrolyte membrane is deprived and the electrolyte membrane deteriorates. At the anode, mixed oxygen, H ⁺ transferred from the cathode, and electrons e ⁻ generated by protonation of hydrogen react to generate water. When the open-circuit voltage is high, electron transfer is difficult to occur, and these chemical reactions are promoted, and carbon poisoning of the electrolyte membrane catalyst occurs.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel that suppresses carbon poisoning by sucking air inside the cathode side of the fuel cell and reducing the amount of oxygen inside the cathode side. A battery system and a control method thereof are provided.

  A first feature of the present invention is a fuel cell, a hydrogen supply means for supplying hydrogen into the anode side of the fuel cell, an air supply means for supplying air into the cathode side of the fuel cell, and an inside of the cathode side An air pressure regulating valve for adjusting the pressure of the discharged air, an air supply means so that the pressure of at least a part of the air inside the cathode side becomes a negative pressure during at least a part of the period until the fuel cell starts to generate power, and The gist of the present invention is a fuel cell system having control means for controlling an air pressure regulating valve.

  The second feature of the present invention is that hydrogen supply means for supplying hydrogen into the anode side of the fuel cell, air supply means for supplying air into the cathode side of the fuel cell, and pressure of air discharged from the cathode side A control method for a fuel cell system comprising an air pressure regulating valve that regulates at least part of the interior of the cathode side during at least a part of the period from when the fuel cell system starts to when the fuel cell begins to generate power The gist of the present invention is to have an air pressure control stage for controlling the air supply means and the air pressure regulating valve so that the air pressure becomes negative.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which suppresses carbon poisoning by attracting the air inside the cathode side of a fuel cell, and reducing the oxygen amount inside a cathode side can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

<Fuel cell system>
As shown in FIG. 1, a fuel cell system according to an embodiment of the present invention includes a fuel cell 1, hydrogen supply means (for example, a hydrogen tank) 2 for supplying hydrogen to the anode 32 a side of the fuel cell 1, An air supply means (for example, a compressor) 10 for supplying air into the cathode 32b side of the fuel cell 1, an air pressure regulating valve 11 for adjusting the pressure of air discharged from the cathode 32b side, and the fuel cell 1 generate electric power. Control means 38 for controlling the compressor 10 and the air pressure regulating valve 11 so that the pressure of at least a part of the air inside the cathode 32b side becomes negative during at least a part of the period until the start, and the fuel cell 1 side or the fuel Air that selectively supplies air to the bypass side of the battery and allows air to flow from the fuel cell 1 side to the bypass side when the bypass side is selected. Connected to the bypass valve 41, the air supply pipe 40 that connects the air three-way valve 23 and the fuel cell 1, the bypass pipe 41 that bypasses the fuel cell 1 from the air three-way valve 23 and exhausts air, and the bypass pipe 41. , A water storage means (for example, a pure water tank) 13 for holding water for humidifying the fuel cell 1, and a dilution means (for example, dilution) connected to the anode side for diluting the exhaust hydrogen discharged from the fuel cell 1. Blower) 9.

  In a fuel cell system, a fuel cell body that generates electricity by reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen is integrated with the peripheral system and peripheral devices. The fuel cell 1 shown in FIG. 1 corresponds to a “fuel cell main body”. The fuel cell 1 includes two sheets corresponding to a solid polymer electrolyte membrane (hereinafter abbreviated as “electrolyte membrane”) 31, a fuel electrode (anode) 32a sandwiching both surfaces of the electrolyte membrane 31, and an oxidant electrode (cathode) 32b. Gas diffusion electrode, a separator 33 composed of a porous plate arranged outside the two gas diffusion electrodes 32a and 32b, a pure water electrode 34 adjacent to the cathode-side separator 33, and a pure water electrode 34 And a cooling water channel 36 adjacent to the separator 35.

  A platinum catalyst is applied to both surfaces of the electrolyte membrane 31 as a reaction catalyst. Since platinum catalysts are expensive, in general, fine carbon is used as a support, and by applying a platinum catalyst on the surface of carbon to increase the reaction area, the reaction efficiency can be increased even with a small amount of platinum catalyst. . Hydrogen gas is supplied to the anode 32a and air is supplied to the cathode 32b, and the electrode reactions shown in the equations (1) and (2) proceed to generate electricity.

Anode (hydrogen electrode): H ₂ → 2H ⁺ + 2e ⁻ (1)
Cathode (oxygen electrode): 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)
Hydrogen is supplied to the anode 32a through the hydrogen tank 2, the hydrogen tank main valve 3, the pressure reducing valve 22, and the hydrogen supply valve 4. The high pressure hydrogen supplied from the hydrogen tank 2 is mechanically reduced to a predetermined pressure by the pressure reducing valve 22, and the hydrogen pressure inside the anode side of the fuel cell 1 is controlled to a desired hydrogen pressure by the hydrogen supplying valve 4. . An ejector 5 and a hydrogen circulation pump 8 are connected between the supply port and the discharge port for the anode 32a. The ejector 5 and the hydrogen circulation pump 8 are respectively installed to recirculate hydrogen that has not been consumed by the anode 32a. The hydrogen circulation pump 8 compensates for hydrogen recirculation in the region where the ejector 5 does not operate. The control unit 38 controls the hydrogen pressure of the anode 32a by driving the hydrogen supply valve 4 by feeding back the hydrogen pressure detected by the pressure sensor 6a. By controlling the hydrogen pressure to be constant, the hydrogen consumed by the fuel cell 1 is automatically supplemented. A purge valve 7 is connected to the discharge port of the anode 32a. The role of the purge valve 7 is (A) exhausting nitrogen accumulated in the hydrogen system to ensure the hydrogen circulation function, and (B) water clogging in the gas flow path to restore the cell voltage. And (C) in order to prevent deterioration of the fuel cell 1, the gas in the hydrogen system is replaced with hydrogen while consuming the oxygen inside the cathode 32 b at the time of start and stop. A dilution blower 9 is connected to the tip of the purge valve 7. The dilution blower 9 dilutes with hydrogen so that the concentration of hydrogen discharged from the purge valve 7 is less than the flammable concentration, and then discharges hydrogen out of the system.

  Air is supplied to the cathode 32b by the compressor 10. An air three-way valve 23 is installed downstream of the compressor 10, an air supply pipe 40 connects one outlet of the air three-way valve 23 and the fuel cell 1, and a bypass pipe 41 connects to the other outlet of the air three-way valve 23. The pure water tank 13 is connected. The air three-way valve 23 will be described later with reference to FIG. The control means 38 controls the air pressure inside the cathode 32b side by driving the air pressure regulating valve 11 by feeding back the air pressure detected by the pressure sensor 6b.

  Pure water is supplied to the pure water electrode 34 through the pure water tank 13 and the pure water pump 12. The control means 38 sets the aerodynamic force, hydrogen power, and pure water pressure in consideration of power generation efficiency and water balance, and manages them at a predetermined differential pressure so as not to cause distortion in the electrolyte membrane 31 and the separators 33 and 35. . By driving the pure water recovery valves 14a, 14b, and 14c, the pure water electrode 34 of the fuel cell 1 and the pure water in the pure water system pipe are recovered to the pure water tank 13 by air pressure. If the system is stopped with the pure water remaining in the pure water electrode 34, the pure water may expand below the freezing point and the fuel cell 1 may be broken. Therefore, when the system is stopped, the pure water is supplied to the pure water tank 13. to recover. The pure water recovery valves 14d and 14b are pure water shut valves having a shut function. When pure water is not circulated to the pure water electrode 34 at the time of starting or stopping the system and hydrogen is supplied to the anode 32a, both the pure water shut valves 14b and 14d are closed to bring the pure water into the pure water piping. Suppresses hydrogen leakage.

  The cooling water is supplied to the cooling water passage 36 by the cooling water pump 15. A cooling water pump 15, a cooling water three-way valve 16, and a radiator 17 are connected on the cooling water flow path. The cooling water three-way valve 16 switches or diverts the cooling water flow path to the radiator 17 direction and the radiator bypass direction. The radiator fan 18 passes air to the radiator 17 to cool the cooling water in the radiator 17. The control means 38 adjusts the temperature of the cooling water by feeding back the cooling water temperature detected by the temperature sensor 19 and driving the cooling water three-way valve 16 and the radiator fan 18.

  The power generated by the fuel cell 1 is taken out by the power manager 20. The power manager 20 supplies this electric power to a motor (not shown) that drives the vehicle. Electric power is taken out from the fuel cell 1 according to the voltage and elapsed time of the fuel cell detected by the voltage sensor 21 when the fuel cell power plant system is started or stopped, and oxygen in the cathode 32b is consumed.

  As shown in FIG. 2A, the air three-way valve has a drive valve 37 that controls the flow of air. The drive valve 37 can be closed to the pure water tank 13 side, but cannot be closed to the fuel cell 1 side. As shown in FIG. 2 (b), the drive valve 37 closes the pure water tank 13 side and transfers all the air supplied from the compressor 10 to the fuel cell 1 during normal operation. As shown in FIG. 2C, the air three-way valve transfers the air supplied from the compressor 10 to the pure water tank 13 at the time of suction for sucking the air inside the cathode 32b. In the case where the pure water tank 13 is frozen below the freezing point, the air from the compressor 10 is supplied to the pure water tank 13 to raise the temperature of the air and assist defrosting of the pure water. At this time, a negative pressure is generated by the venturi effect, and the air on the cathode 32 b side is sucked into the pure water tank 13. Therefore, the pressure of the air inside the cathode 32b side becomes a negative pressure.

<Control method of fuel cell system>
Next, a control method of the fuel cell system shown in FIGS. 1 and 2 will be described with reference to the flowchart of FIG.

  (A) First, in step S1, the fuel cell system shown in FIG. 1 is started.

  (B) In step S2, the measured values of the pressure sensors 6a and 6b and the temperature sensor 19 of the fuel cell system and the time Te from the previous stop time to the present time (fuel cell) are read.

  (C) In step S3, it is determined whether the time Te during which the fuel cell system has been stopped is equal to or greater than a predetermined threshold value Ti1. If the time Te is less than the threshold Ti1 (NO in step S3), the process proceeds to S7, and if the time Te is greater than or equal to the threshold Ti1 (YES in step S3), the process proceeds to S4. The threshold value Ti1 here is set to 5 hours, for example.

  (D) In step S4, the control means 38 controls the air pressure regulating valve 11 and the air three-way valve 23 so that the pressure of at least a part of the air inside the cathode 32b becomes negative when the compressor 10 is driven. . Step S4 is referred to as “pneumatic control step”. Specifically, in the air pressure control stage, the air pressure regulating valve 11 is fully closed so that air is supplied from the cathode 32b side of the fuel cell 1 to the pure water tank 13 side by the venturi effect. The opening degree of the drive valve of the valve 23 is adjusted.

  (E) In step S5, hydrogen is supplied into the anode 32a side of the fuel cell 1 and at the same time, air is supplied from the compressor 10 to generate a negative pressure due to the venturi effect on the cathode 32b side of the fuel cell 1 to thereby generate the fuel cell. The air present on the cathode 32b side of the first is sucked, and the supply of air to the pure water tank 13 is started. The S5 stage is called a “fuel supply stage”. The fuel supply stage includes a procedure for increasing the pressure of the air supplied by the compressor 10. That is, the compressor 10 is operated at a pressure higher than the normal air supply pressure. Note that the fuel supply stage is performed during the entire period or a part of the period from when the fuel cell system is activated to when the fuel cell 1 starts generating power.

  (F) In step S6, it is determined whether or not the time Tt when the supply of air from the compressor 10 is started is longer than the threshold value Ti2. If longer than the threshold value Ti2 (YES in step S6), the process proceeds to step S7, and if it is equal to or lower than the threshold value Ti2 (NO in step S6), the air supply from the compressor 10 is continued. The threshold value Ti2 here is, for example, 30 seconds.

  (G) In step S7, the opening of the air pressure regulating valve 11 and the air three-way valve 23 is adjusted. For example, the air pressure regulating valve 11 is fully opened, and the opening degree of the air three-way valve 23 is adjusted so that air is supplied to the fuel cell side.

  (H) In step S8, the pure water pump 12 is driven to start the supply of pure water to the pure water electrode 34 of the fuel cell 1.

  In addition, although hydrogen and air began to be simultaneously supplied to the fuel cell 1 in the step S5, the present invention is not limited to this. The hydrogen supply unit and the air supply unit (compressor) 10 may be controlled to start supplying hydrogen after starting to supply air.

  As described above, the amount of oxygen in the cathode 32b is sucked by sucking the air in the cathode 32b by performing control so that all or part of the inside of the cathode 32b of the fuel cell 1 becomes negative pressure when the system is started. The carbon poisoning generated on the cathode 32b side of the fuel cell 1 can be suppressed by suppressing the increase in the open-circuit voltage.

  In the whole period or a part of the period from when the system is started to when the fuel cell 1 starts to generate power, the control means 38 controls the bypass side (pure water tank 13 side) while keeping the air pressure regulating valve 11 fully closed. The air three-way valve 23 is controlled so as to supply air. Thus, all or part of the cathode 32b side of the fuel cell 1 can be set to a negative pressure with a simple configuration.

  The control means 38 starts supplying hydrogen and air simultaneously to the fuel cell 1 when the fuel cell system is activated, or supplies hydrogen after starting supplying air (for example, a hydrogen supply valve). 4) and the compressor 10 are controlled. As a result, the hydrogen supply is controlled to be after the air supply, so that the amount of oxygen is reduced by the negative air suction on the cathode 32b side, and the hydrogen is supplied from the anode 32a side at the same time or after the air suction. Therefore, hydrogen is not supplied in a state where there is a high concentration of oxygen, and a high potential is suppressed.

  Furthermore, the oxygen concentration in the cathode 23b can be reduced in a shorter time by reducing the oxygen concentration due to the reaction between hydrogen and oxygen and the consumption of oxygen.

  The control means 38 raises the pressure of the air supplied by the compressor 10 when performing control so that the negative pressure is obtained. Since the fuel cell system performs control to increase the supply pressure of the compressor 10 and raise the air temperature, it is possible to supply high-temperature air, so that air is sucked from the cathode 32 b side of the fuel cell 1. The thawing time of pure water frozen below freezing point can be further shortened.

As shown in FIG. 5A, when the fuel cell system is stopped, left standing, or started, oxygen and hydrogen remain in the cathode 32b and the anode 32a without being connected to the load, When hydrogen is started to be supplied to the anode 32a at the time of starting the battery system, the anode 32a is in a state where hydrogen and oxygen are mixed. Accordingly, the proton H ⁺ moves from the anode 32a to the cathode 32b, and the moved H ⁺ reacts with oxygen at the cathode 32b to generate water. While being is required, electrons e because the load is not connected ^{- -} In this reaction the electrons e do not come move through the load. For this reason, the water present in the cathode 32b reacts with the electrode catalyst layer 39 carrying the platinum catalyst on the carbon support, and the electrons e ⁻ generated by this reaction are used for the cathode water generation reaction. At this time, the carbon of the electrode catalyst layer 39 is taken and the electrolyte membrane 31 deteriorates. At the anode 32a, mixed oxygen, H ⁺ transferred from the cathode, and electrons e ⁻ generated by protonation of hydrogen react to generate water. When the open-circuit voltage is high, the movement of electrons is difficult to occur, and these chemical reactions are promoted, and the carbon poisoning of the electrolyte membrane 31 becomes intense. The carbon poisoning of the electrolyte membrane 31 affects the IV characteristics of the fuel cell system, i.e., the voltage drops, and a large generated power cannot be obtained.

  As shown in FIG. 5B, when the fuel cell system is stopped (leaved), (1) oxygen remains in the cathode 32b, (2) hydrogen remains in the anode 32a, and oxygen is externally present. (3) When there is no power extraction (no load connection), (4) When the open-circuit voltage is high, a reverse current flows and carbon of the platinum catalyst carrier on the electrolyte membrane 31 causes carbon poisoning. . As countermeasures against this, (A) the oxygen inside the cathode 32b side is consumed, (B) the open-circuit voltage is reduced by the oxygen consumption inside the cathode 32b side, and (C) a short circuit between the cathode 32b and the anode 32a. For example, connecting a resistor.

  On the other hand, when the fuel cell system is started up, (1) oxygen enters the cathode 32b from the outside, (2) when hydrogen is supplied into the anode 32a, it mixes with oxygen, and (3) power is not taken out (power (4) When the open circuit voltage is high, reverse current flows and carbon of the platinum catalyst carrier on the electrolyte membrane 31 causes carbon poisoning. As countermeasures against this, (A) the oxygen inside the cathode 32b side is consumed, (B) the hydrogen inside the anode 32a side is replaced, and (C) the open end voltage is reduced by the oxygen consumption inside the cathode 32b side. ,and so on.

  In order to solve the above problem, according to the fuel cell system and the control method thereof according to the embodiment of the present invention, the air pressure adjusting valve 11 is completely closed and the opening degree of the air three-way valve 23 is adjusted to adjust the air supply means (compressor). ) By supplying air from 10, the air inside the cathode 32b side of the fuel cell 1 is sucked and the amount of oxygen inside the cathode 32b side can be reduced to suppress carbon poisoning.

  Further, if the fuel cell does not humidify the electrolyte membrane 31, the electrolyte membrane dries out due to heat generated from the fuel cell itself at the same time as power generation and moisture taken out by the supply gas, resulting in performance degradation. Therefore, it is necessary to supply humidified pure water from the outside. However, if the pure water for humidification freezes below freezing point, the pure water for humidification cannot be supplied to the fuel cell, so it is necessary to quickly thaw the pure water for humidification of the fuel cell. According to the fuel cell system and the control method thereof according to the embodiment of the present invention, the air three-way valve 23 is adjusted and the air is supplied from the compressor 10 when the deterioration of the fuel cell is suppressed. At the same time as the internal air is sucked, the air whose temperature has been raised to 0 ° C. or higher by the compressor 10 is supplied to the pure water tank 13, which helps defrost the pure water in the pure water tank 13. Further, by adjusting the opening degree of the air three-way valve 23 and increasing the discharge pressure of the compressor 10, it is possible to supply higher temperature air to the pure water tank 13.

(Modification)
As shown in FIG. 4, the fuel cell system according to the modification of the embodiment of the present invention is provided with a pipe connecting the dilution blower 9 and the air three-way valve 23 as compared with the fuel cell system shown in FIG. However, the other configuration is the same and the description is omitted.

  In the fuel cell system of FIG. 1, by sucking air from the cathode 32 b side of the fuel cell 1, the increase in the open circuit voltage is suppressed and the carbon poisoning of the fuel cell 1 is suppressed. Then, in order to suppress carbon poisoning, a negative pressure is generated on the cathode 32b side of the fuel cell 1 to suck air and supply the sucked air to the dilution blower 9 to obtain a higher dilution effect. it can.

  That is, in order to suppress carbon poisoning of the fuel cell 1, hydrogen supplied to the anode 32 a side is mixed with exhausted hydrogen using air sucked on the cathode 32 b side of the fuel cell 1 to reduce the hydrogen concentration. Can be exhausted.

  As described above, the present invention has been described by way of one embodiment and modifications thereof. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. That is, it should be understood that the present invention includes various embodiments not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

1 is a block diagram showing a fuel cell system according to an embodiment of the present invention. 2 (a) is a cross-sectional view showing the configuration of the air three-way valve shown in FIG. 1, and FIG. 2 (b) is a cross-sectional view showing the position of the drive valve and the air flow in the normal state. c) is a sectional view showing the position of the drive valve and the flow of air during suction. 3 is a flowchart showing a control method of the fuel cell system shown in FIGS. 1 and 2. It is a block diagram which shows the fuel cell system concerning the modification of embodiment of this invention. FIG. 5A is a diagram for explaining a reaction process of carbon poisoning of a fuel cell, and FIG. 5B is a diagram summarizing conditions for causing carbon poisoning and means for solving them.

Explanation of symbols

1: Fuel cell 2: Hydrogen tank 3: Hydrogen tank main valve 4: Hydrogen supply valve 5: Ejectors 6a, 6b: Pressure sensor 7: Purge valve 8: Hydrogen circulation pump 9: Dilution blower 10: Compressor 11: Air pressure adjustment valve 12 : Pure water pump 13: Pure water tanks 14 a to 14 d: Valve 15: Cooling water pump 16: Cooling water three-way valve 17: Radiator 18: Radiator fan 19: Temperature sensor 20: Power manager 21: Voltage sensor 22: Pressure reducing valve 23: Air three-way valve 31: electrolyte membrane 32a: anode 32b: cathode 33: separator (porous plate)
34: Pure water electrode 35: Separator (solid plate)
36: Cooling water flow path 37: Drive valve 38: Control means

Claims (10)

A fuel cell;
Hydrogen supply means for supplying hydrogen into the anode side of the fuel cell;
Air supply means for supplying air into the cathode side of the fuel cell;
An air pressure regulating valve for adjusting the pressure of the air discharged from the cathode side;
Control for controlling the air supply means and the air pressure regulating valve so that the pressure of at least a part of the air inside the cathode side becomes a negative pressure during at least a part of the period until the fuel cell starts to generate power. And a fuel cell system. Three-way air that selectively supplies the air to the fuel cell side or the bypass side of the fuel cell and allows the flow of air from the fuel cell side to the bypass side when the bypass side is selected A valve,
An air supply pipe connecting the air three-way valve and the fuel cell;
A bypass pipe that bypasses the fuel cell from the air three-way valve and exhausts the air;
In at least a part of the period until the fuel cell starts to generate power, the control means controls the air three-way valve so that air is supplied to the bypass side while the air pressure regulating valve is fully closed. The fuel cell system according to claim 1, wherein:   The control means starts supplying the hydrogen and the air to the fuel cell simultaneously when the fuel cell system starts up, or starts supplying the hydrogen after starting supplying the air. 3. The fuel cell system according to claim 2, wherein the air supply means is controlled.   3. The fuel cell system according to claim 2, further comprising water storage means connected to the bypass pipe for holding water for humidifying the fuel cell.   2. The fuel cell system according to claim 1, wherein the control means increases the pressure of the air supplied by the air supply means when performing control so as to be a negative pressure. Further comprising dilution means for diluting the exhaust hydrogen discharged from the fuel cell connected to the anode side;
The fuel cell system according to claim 2, wherein the dilution unit is connected to the bypass pipe. Hydrogen supply means for supplying hydrogen to the anode side of the fuel cell, air supply means for supplying air to the cathode side of the fuel cell, and an air pressure regulating valve for adjusting the pressure of the air discharged from the cathode side A control method for a fuel cell system comprising:
The air supply means so that the pressure of at least a part of the air inside the cathode side becomes a negative pressure in at least a part of a period from when the fuel cell system is started to when the fuel cell starts to generate power; A control method for a fuel cell system, comprising: an air pressure control step for controlling the air pressure regulating valve. The fuel cell system selectively supplies the air to the fuel cell side or the bypass side of the fuel cell, and the air from the fuel cell side to the bypass side when the bypass side is selected. A three-way air valve that allows flow;
8. The fuel cell system according to claim 7, wherein the air pressure control step is a step of controlling the air three-way valve so as to supply air to the bypass side while the air pressure regulating valve is fully closed. Control method.   The hydrogen supply means and the air supply means start supplying the hydrogen and the air to the fuel cell at the same time when the fuel cell system is activated, or start supplying the hydrogen after starting supplying the air. The fuel cell system control method according to claim 8, further comprising a fuel supply step for controlling the fuel cell.   8. The method of controlling a fuel cell system according to claim 7, wherein the air pressure control step includes a step of increasing the pressure of the air supplied by the air supply means.

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