WO2014192486A1 - Fuel-cell system - Google Patents

Fuel-cell system Download PDF

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Publication number
WO2014192486A1
WO2014192486A1 PCT/JP2014/061914 JP2014061914W WO2014192486A1 WO 2014192486 A1 WO2014192486 A1 WO 2014192486A1 JP 2014061914 W JP2014061914 W JP 2014061914W WO 2014192486 A1 WO2014192486 A1 WO 2014192486A1
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WO
WIPO (PCT)
Prior art keywords
pressure
anode
gas
fuel cell
purge
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Application number
PCT/JP2014/061914
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French (fr)
Japanese (ja)
Inventor
隼人 筑後
Original Assignee
日産自動車株式会社
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Filing date
Publication date
Application filed by 日産自動車株式会社 filed Critical 日産自動車株式会社
Publication of WO2014192486A1 publication Critical patent/WO2014192486A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
    • H01M8/04225—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells during start-up
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
    • H01M8/04231—Purging of the reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/043—Processes for controlling fuel cells or fuel cell systems applied during specific periods
    • H01M8/04302—Processes for controlling fuel cells or fuel cell systems applied during specific periods applied during start-up
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0438—Pressure; Ambient pressure; Flow
    • H01M8/04395—Pressure; Ambient pressure; Flow of cathode reactants at the inlet or inside the fuel cell
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04753—Pressure; Flow of fuel cell reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04201—Reactant storage and supply, e.g. means for feeding, pipes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • This invention relates to a fuel cell system.
  • Japanese Patent Publication No. 2007-517369 discloses a fuel cell system in which a high-pressure anode gas is intermittently supplied in a pulsating manner.
  • high-pressure anode gas is supplied to the fuel cell, impurities that stay in the anode channel, that is, moisture generated during power generation and air that has permeated the electrolyte membrane from the cathode channel (mainly nitrogen) are pushed into the buffer tank. This increases the concentration of the anode gas in the anode channel.
  • the supply of the anode gas is stopped, and when power generation continues in this state, the anode gas in the anode channel is consumed, and the pressure in the anode channel decreases.
  • the fuel cell catalyst deteriorates due to the air in the anode flow path when the fuel cell is restarted. Therefore, in the fuel cell system, such air is expelled to the buffer tank at an early stage by increasing the supply pressure of the anode gas when the system is activated. Thereby, it becomes possible to cope with impurities such as air during driving.
  • the electrolyte membrane of a fuel cell is a thin member, if the anode pressure is increased without considering the pressure on the cathode side, the electrolyte membrane will be adversely affected.
  • An object of the present invention is to provide a fuel cell system capable of suppressing a decrease in durability at the time of system startup of components constituting the fuel cell.
  • a fuel cell system that intermittently pulsates the anode gas.
  • the fuel cell system includes an upper limit setting unit that sets the pulsation upper limit pressure of the anode gas according to the pressure of the cathode gas, and a purge control unit that controls the purge of the anode gas discharged from the fuel cell.
  • the fuel cell system increases the anode gas pulsation upper limit pressure to be higher than the anode gas pulsation upper limit pressure set by the upper limit setting unit at the start of the fuel cell system start-up operation, and executes the start-up operation.
  • a start-up operation executing unit, and an anode pressure control unit that lowers the pulsation upper limit pressure at the start of start-up when a predetermined period has elapsed from the start of the start-up operation.
  • FIG. 1A is a perspective view of a fuel cell according to an embodiment of the present invention.
  • FIG. 1B is a longitudinal sectional view of the fuel cell taken along the line BB in FIG. 1A.
  • FIG. 2 is a schematic configuration diagram of an anode gas non-circulating fuel cell system according to an embodiment of the present invention.
  • FIG. 3 is a diagram for explaining the pulsation operation of the fuel cell system.
  • FIG. 4 is a flowchart showing system control of the fuel cell system.
  • FIG. 5 is a flowchart showing the startup purge operation process.
  • FIG. 6 is a flowchart showing the startup purge preparation process.
  • FIG. 7 is a flowchart showing the startup purge process.
  • FIG. 1A is a perspective view of a fuel cell according to an embodiment of the present invention.
  • FIG. 1B is a longitudinal sectional view of the fuel cell taken along the line BB in FIG. 1A.
  • FIG. 2 is a schematic configuration diagram of an anode gas
  • FIG. 8 is a map for calculating the start purge end time based on the representative temperature and the atmospheric pressure.
  • FIG. 9 is a flowchart showing the decompression process.
  • FIG. 10 is a flowchart showing the pressure holding process.
  • FIG. 11 is a flowchart showing the boosting process.
  • FIG. 12 is a flowchart showing the startup purge end process.
  • FIG. 13 is a block diagram showing a method for setting the anode lower limit pressure.
  • FIG. 14 is a block diagram showing a setting unit for setting a maximum anode pressure limit value required for preventing an excessive differential pressure.
  • FIG. 15 is a time chart showing the system operation of the fuel cell system.
  • the fuel cell includes an anode electrode as a fuel electrode, a cathode electrode as an oxidant electrode, and an electrolyte membrane disposed so as to be sandwiched between these electrodes.
  • the fuel cell generates electric power using an anode gas containing hydrogen supplied to the anode electrode and a cathode gas containing oxygen supplied to the cathode electrode.
  • the electrode reaction that proceeds in both the anode electrode and the cathode electrode is as follows.
  • Anode electrode 2H 2 ⁇ 4H + + 4e ⁇ (1)
  • Cathode electrode 4H + + 4e ⁇ + O 2 ⁇ 2H 2 O (2)
  • the fuel cell generates an electromotive force of about 1 volt by the electrode reactions (1) and (1).
  • FIG. 1A and 1B are diagrams illustrating the configuration of a fuel cell 10 according to an embodiment of the present invention.
  • FIG. 1A is a schematic perspective view of the fuel cell 10
  • FIG. 1B is a cross-sectional view taken along the line BB of the fuel cell 10 of FIG.
  • An anode separator 12 and a cathode separator 13 are arranged on the front and back of the membrane electrode assembly (MEA) 11 of the fuel cell 10.
  • the MEA 11 includes an electrolyte membrane 111, an anode electrode 112, and a cathode electrode 113.
  • An anode electrode 112 is disposed on one surface side of the electrolyte membrane 111, and a cathode electrode 113 is disposed on the other surface side of the electrolyte membrane 111.
  • the electrolyte membrane 111 is a proton conductive ion exchange membrane formed of a fluorine-based resin.
  • the electrolyte membrane 111 exhibits good proton conductivity in a wet state.
  • the anode electrode 112 includes a catalyst layer 112a and a gas diffusion layer 112b.
  • the catalyst layer 112a is in contact with the electrolyte membrane 111.
  • the catalyst layer 112a is formed from carbon black particles carrying platinum or a platinum alloy.
  • the gas diffusion layer 112b is provided outside the catalyst layer 112a and is in contact with the anode separator 12.
  • the gas diffusion layer 112b is formed of a member having sufficient gas diffusibility and conductivity, for example, a carbon cloth woven with yarns made of carbon fibers.
  • the cathode electrode 113 includes a catalyst layer 113a and a gas diffusion layer 113b.
  • the anode separator 12 is in contact with the gas diffusion layer 112b.
  • the anode separator 12 has a plurality of groove-like anode gas passages 121 for supplying anode gas to the anode electrode 112 on the side in contact with the gas diffusion layer 112b.
  • the cathode separator 13 is in contact with the gas diffusion layer 113b.
  • the cathode separator 13 has a plurality of groove-like cathode gas flow paths 131 for supplying cathode gas to the cathode electrode 113 on the side in contact with the gas diffusion layer 113b.
  • the anode separator 12 and the cathode separator 13 are configured such that the flow direction of the anode gas flowing through the anode gas flow path 121 and the flow direction of the cathode gas flowing through the cathode gas flow path 131 are opposite and parallel to each other.
  • the anode separator 12 and the cathode separator 13 may be configured such that the flow directions of these gases flow in the same direction and in parallel.
  • FIG. 2 is a schematic configuration diagram of an anode gas non-circulating fuel cell system 1 according to an embodiment of the present invention.
  • the fuel cell system 1 includes a fuel cell stack 2, a cathode gas supply / discharge device 3, an anode gas supply / discharge device 4, a stack cooling device 6, and a controller 7.
  • the fuel cell stack 2 is a battery in which a plurality of fuel cells 10 are stacked.
  • the fuel cell stack 2 receives the supply of the anode gas and the cathode gas and generates electric power necessary for driving the vehicle.
  • the cathode gas supply / discharge device 3 includes a cathode gas supply passage 31, a filter 32, a cathode compressor 33, an air flow sensor 34, a cathode gas discharge passage 35, a Water Recovery Device (WRD) 36, a pressure sensor 37, Is provided.
  • a cathode gas supply passage 31 a filter 32, a cathode compressor 33, an air flow sensor 34, a cathode gas discharge passage 35, a Water Recovery Device (WRD) 36, a pressure sensor 37, Is provided.
  • RDD Water Recovery Device
  • the cathode gas supply passage 31 is a passage through which the cathode gas supplied to the fuel cell stack 2 flows. One end of the cathode gas supply passage 31 is connected to the filter 32, and the other end is connected to the cathode gas inlet hole 21 of the fuel cell stack 2.
  • the filter 32 removes foreign matters contained in the cathode gas taken into the cathode gas supply passage 31.
  • the cathode compressor 33 is provided in the cathode gas supply passage 31.
  • the cathode compressor 33 takes in air as cathode gas through the filter 32 into the cathode gas supply passage 31 and supplies it to the fuel cell stack 2.
  • the air flow sensor 34 is provided in the cathode gas supply passage 31 upstream of the cathode compressor 33.
  • the air flow sensor 34 detects the flow rate of the cathode gas flowing through the cathode gas supply passage 31.
  • the cathode gas discharge passage 35 is a passage through which the cathode off gas discharged from the fuel cell stack 2 flows. One end of the cathode gas discharge passage 35 is connected to the cathode gas outlet hole 22 of the fuel cell stack 2, and the other end is formed as an open end.
  • the WRD 36 humidifies the cathode gas supplied to the fuel cell stack 2 using the cathode off gas discharged from the fuel cell stack 2.
  • the pressure sensor 37 detects the pressure upstream of the WRD 36.
  • the anode gas supply / discharge device 4 includes a high pressure tank 41, an anode gas supply passage 42, a pressure regulating valve 43, a pressure sensor 44, a first anode gas discharge passage 45, a second anode gas discharge passage 46, a first A purge passage 47, a second purge passage 48, a first purge valve 49, a second purge valve 50, and a buffer tank 51 are provided.
  • the high pressure tank 41 stores the anode gas supplied to the fuel cell stack 2 in a high pressure state.
  • the anode gas supply passage 42 is a passage for supplying the anode gas discharged from the high-pressure tank 41 to the fuel cell stack 2.
  • One end of the anode gas supply passage 42 is connected to the high pressure tank 41, and the other end is connected to the anode gas inlet hole 23 of the fuel cell stack 2.
  • the pressure regulating valve 43 is provided in the anode gas supply passage 42.
  • the pressure regulating valve 43 adjusts the anode gas discharged from the high-pressure tank 41 to a desired pressure and supplies it to the fuel cell stack 2.
  • the pressure regulating valve 43 is an electromagnetic valve capable of adjusting the opening degree continuously or stepwise. The opening degree of the pressure regulating valve 43 is controlled by the controller 7.
  • the pressure sensor 44 is provided in the anode gas supply passage 42 downstream of the pressure regulating valve 43.
  • the pressure sensor 44 detects the pressure in the anode gas supply passage 42.
  • the pressure detected by the pressure sensor 44 is used as the pressure of the entire anode system including each anode gas flow path 121 and the buffer tank 51 of the fuel cell stack 2.
  • first anode gas discharge passage 45 One end of the first anode gas discharge passage 45 is connected to the first anode gas outlet hole 24 of the fuel cell stack 2, and the other end is connected to the buffer tank 51.
  • first anode gas discharge passage 45 a mixed gas of surplus anode gas that has not been used for the electrode reaction and an inert gas such as nitrogen or water vapor that has permeated from the cathode side to the anode gas flow path 121, so-called The anode off gas is discharged.
  • One end of the second anode gas discharge passage 46 is connected to the second anode gas outlet hole 25 of the fuel cell stack 2, and the other end is connected to the buffer tank 51.
  • the anode off gas from the fuel cell stack 2 is discharged into the second anode gas discharge passage 46.
  • One end of the first purge passage 47 is connected to the first anode gas discharge passage 45 and the other end is connected to the cathode gas discharge passage 35.
  • One end of the second purge passage 48 is connected to the second anode gas discharge passage 46, and the other end is connected to the cathode gas discharge passage 35.
  • the first purge valve 49 is provided in the first purge passage 47.
  • the first purge valve 49 is an electromagnetic valve that is fully opened or closed, and the opening degree of the first purge valve 49 is controlled by the controller 7.
  • a water jacket is formed inside the first purge valve 49, and the first purge valve 49 is configured to circulate the cooling water of the fuel cell stack 2 through the water jacket. Thereby, valve sticking resulting from freezing is prevented.
  • the second purge valve 50 is provided in the second purge passage 48.
  • the second purge valve 50 is an electromagnetic valve that is fully opened or completely closed, and the opening degree of the second purge valve 50 is controlled by the controller 7.
  • a water jacket is formed inside the second purge valve 50, and the second purge valve 50 is configured such that the cooling water of the fuel cell stack 2 circulates through the water jacket. Thereby, valve sticking resulting from freezing is prevented.
  • the discharge amount of the anode off gas discharged from the buffer tank 51 to the outside through the first purge passage 47 and the second purge passage 48 is adjusted.
  • the concentration of the anode gas in the buffer tank 51 is adjusted to a predetermined concentration.
  • the anode gas concentration in the buffer tank 51 is controlled to an appropriate value in consideration of power generation efficiency and fuel consumption.
  • the buffer tank 51 is a container that temporarily stores the anode off gas that has passed through the first anode gas discharge passage 45 and the second anode gas discharge passage 46.
  • the anode off gas in the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first purge passage 47 and the second purge passage 48 when the first purge valve 49 and the second purge valve 50 are opened.
  • a mixed gas (purge gas) of the anode off gas and the cathode off gas is discharged from the open end of the cathode gas discharge passage 35 to the outside.
  • the anode off gas is mixed with the cathode off gas and discharged, so that the hydrogen concentration in the purge gas becomes less than a predetermined combustible concentration.
  • the stack cooling device 6 is a device that cools the fuel cell stack 2 and maintains the fuel cell stack 2 at a temperature suitable for power generation.
  • the stack cooling device 6 includes a coolant circulation passage 61, a radiator 62, a bypass passage 63, a three-way valve 64, a circulation pump 65, a PTC heater 66, a first purge valve circulation passage 67, and a second purge valve circulation.
  • a passage 68, an inlet water temperature sensor 69, an outlet water temperature sensor 70, a first purge valve temperature sensor 71, and a second purge valve temperature sensor 72 are provided.
  • the cooling water circulation passage 61 is a passage through which cooling water for cooling the fuel cell stack 2 circulates.
  • One end of the coolant circulation path 61 is connected to the coolant inlet hole 26 of the fuel cell stack 2, and the other end is connected to the coolant outlet hole 27 of the fuel cell stack 2.
  • the cooling water circulation passage 61 will be described with the cooling water outlet hole 27 side as the upstream side and the cooling water inlet hole 26 side as the downstream side.
  • the radiator 62 is provided in the cooling water circulation passage 61.
  • the radiator 62 cools the cooling water discharged from the fuel cell stack 2.
  • the bypass passage 63 is a passage for bypassing the radiator 62 and circulating the cooling water. One end of the bypass passage 63 is connected to the cooling water circulation passage 61, and the other end is connected to the three-way valve 64.
  • the three-way valve 64 is provided in the cooling water circulation passage 61 on the downstream side of the radiator 62.
  • the three-way valve 64 switches the cooling water circulation path according to the temperature of the cooling water.
  • the cooling water circulation path is switched so that the cooling water discharged from the fuel cell stack 2 is supplied again to the fuel cell stack 2 via the radiator 62.
  • the coolant circulation path is such that the coolant discharged from the fuel cell stack 2 flows through the bypass passage 63 and is supplied to the fuel cell stack 2 again. Can be switched.
  • the circulation pump 65 is provided in the cooling water circulation passage 61 on the downstream side of the three-way valve 64.
  • the circulation pump 65 circulates the cooling water.
  • the PTC heater 66 is provided in the bypass passage 63.
  • the PTC heater 66 is energized when the fuel cell stack 2 is warmed up, and raises the temperature of the cooling water.
  • the first purge valve circulation passage 67 is a passage for introducing cooling water into a water jacket formed in the first purge valve 49 in order to prevent the first purge valve 49 from sticking due to freezing.
  • the first purge valve circulation passage 67 branches from the cooling water circulation passage 61 on the downstream side of the circulation pump 65 and introduces the cooling water into the water jacket of the first purge valve 49, and the first purge valve 49.
  • the second purge valve circulation passage 68 is a passage for introducing cooling water into a water jacket formed in the second purge valve 50 in order to prevent the second purge valve 50 from sticking due to freezing.
  • the second purge valve circulation passage 68 branches from the cooling water circulation passage 61 on the downstream side of the circulation pump 65 and introduces the cooling water into the water jacket of the second purge valve 50, and the second purge valve 50.
  • a second return passage 682 for returning the cooling water discharged from the water jacket to the cooling water circulation passage 61 on the upstream side of the circulation pump 65.
  • the inlet water temperature sensor 69 is provided in the cooling water circulation passage 61 near the cooling water inlet hole 26 of the fuel cell stack 2.
  • the inlet water temperature sensor 69 detects the temperature of the cooling water flowing into the fuel cell stack 2.
  • the outlet water temperature sensor 70 is provided in the cooling water circulation passage 61 near the cooling water outlet hole 27 of the fuel cell stack 2.
  • the outlet water temperature sensor 70 detects the temperature of the cooling water discharged from the fuel cell stack 2 (stack temperature).
  • the first purge valve temperature sensor 71 is provided in the first return passage 672.
  • the first purge valve temperature sensor 71 detects the temperature of the cooling water discharged from the water jacket of the first purge valve 49 (first purge valve temperature).
  • the second purge valve temperature sensor 72 is provided in the second return passage 682.
  • the second purge valve temperature sensor 72 detects the temperature of the cooling water discharged from the water jacket of the second purge valve 50 (second purge valve temperature).
  • the controller 7 includes a microcomputer having a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).
  • CPU central processing unit
  • ROM read-only memory
  • RAM random access memory
  • I / O interface input / output interface
  • the controller 7 receives detection signals from the air flow sensor 34, the pressure sensor 44, the outlet water temperature sensor 70, the first purge valve temperature sensor 71, and the second purge valve temperature sensor 72.
  • the controller 7 also includes a current sensor 73 for detecting the output current of the fuel cell stack 2, a voltage sensor 74 for detecting the output voltage of the fuel cell stack 2, and an accelerator stroke for detecting the accelerator pedal depression amount (accelerator operation amount). Signals from various sensors that detect the operating state of the fuel cell system 1, such as the sensor 75 and the atmospheric pressure sensor 76 that detects atmospheric pressure, are input.
  • the controller 7 performs pulsation operation for pulsating the anode gas by periodically opening and closing the pressure regulating valve 43 based on the system operation state, and controls the opening degree of the purge valves 47 and 48, from the buffer tank 51.
  • the anode gas concentration in the buffer tank 51 is maintained at a predetermined concentration by adjusting the flow rate of the discharged anode off gas.
  • an impure gas such as nitrogen in the anode gas passage 121 can be pushed into the buffer tank 51.
  • an impure gas such as nitrogen in the anode gas passage 121
  • stable power generation can be realized in the fuel cell system 1.
  • FIG. 3 is a diagram for explaining pulsation operation during steady operation in which the operation state of the fuel cell system 1 is constant.
  • the controller 7 calculates the target output of the fuel cell stack 2 based on the operating state of the fuel cell system 1, and calculates the lower limit pressure and pulsation pressure width of the anode gas according to the target output. Thereby, the upper limit pressure value and the lower limit pressure value of the anode gas supplied to the fuel cell stack 2 are set. As shown in FIG. 3A, in the fuel cell system 1, the anode gas pressure is periodically increased or decreased between the set upper limit pressure value and lower limit pressure value.
  • the target pressure of the anode gas is set to the lower limit pressure value, and feedback control of the anode pressure is performed.
  • the pressure regulating valve 43 is controlled to be fully closed, and the supply of the anode gas from the high-pressure tank 41 to the fuel cell stack 2 is stopped.
  • the anode gas in the fuel cell stack 2 is consumed, so the anode pressure is reduced by the amount of consumption of the anode gas.
  • the pressure in the buffer tank 51 temporarily becomes higher than the pressure in the anode gas channel 121, so that the anode off-gas flows from the buffer tank 51 to the anode gas channel 121. Backflow.
  • the anode gas remaining in the anode gas flow path 121 and the anode gas in the anode off-gas flowing back to the anode gas flow path 121 are consumed over time, and the anode pressure further decreases.
  • the pressure regulating valve 43 When the anode pressure reaches the lower limit pressure value at time t13, the pressure regulating valve 43 is opened in the same manner as at time t11. When the anode pressure reaches the upper limit pressure value again at time t14, the pressure regulating valve 43 is fully closed.
  • the anode gas concentration (hydrogen concentration) in the buffer tank 51 is too low, the anode pressure decreases and the anode off gas flows back into the fuel cell stack 2.
  • the anode gas used for the electrode reaction is insufficient in the downstream region of the gas flow path 121.
  • the anode gas used for the electrode reaction is insufficient, not only the power generation efficiency is lowered, but also the fuel cell 10 constituting the fuel cell stack 1 is deteriorated.
  • the air in the anode gas flow path 121 and the buffer tank 51 are filled with air in the atmosphere that has entered the anode system while the system is stopped. Therefore, at the time of starting the fuel cell system, it is necessary to perform a start purge operation as a preparatory operation before performing the pulsation operation.
  • the start-up purge operation the first and second purge valves 49 and 50 are opened to discharge the air in the buffer tank 51 to the outside, and the anode gas is supplied to the fuel cell stack 2 so that the anode gas concentration in the buffer tank 51 is increased. Is increased to a predetermined concentration.
  • FIG. 4 is a flowchart for explaining the main routine of the fuel cell system 1.
  • the controller 7 When the fuel cell system 1 is activated, the controller 7 repeatedly executes this routine at a predetermined calculation cycle (for example, 10 milliseconds).
  • step 1 (S1) the controller 7 reads the detection values of the various sensors described above.
  • the controller 7 determines whether or not the start purge operation end flag is set to 1.
  • the start purge operation end flag is a flag that is set to 1 after the start purge operation is completed, and is set to 0 when the system is started.
  • the controller 7 executes the process of S3 when the startup purge operation end flag is 0, and executes the process of S4 when the startup purge operation end flag is 1.
  • the controller 7 performs a startup purge operation process. Details of the startup purge operation processing will be described later with reference to FIG.
  • the controller 7 performs normal processing.
  • a pulsation operation is performed in which the anode pressure is periodically increased or decreased between the set upper limit pressure value and lower limit pressure value.
  • the controller 7 calculates the lower limit pressure and the pulsation pressure width of the anode gas according to the cathode gas pressure determined based on the operating state, whereby the upper limit pressure value (pulsation upper limit pressure) and the lower limit pressure value ( Set the pulsation lower limit pressure.
  • the controller 7 has a function of setting the pulsation upper limit pressure and the pulsation lower limit pressure of the anode gas after the startup purge operation process.
  • FIG. 5 is a flowchart for explaining the startup purge operation process.
  • the controller 7 determines whether or not the startup purge preparation end flag is set to 1.
  • the start purge preparation end flag is a flag that is set to 1 when preparation for the start purge operation is completed, and the initial value is set to 0.
  • the controller 7 executes the process of S32 when the startup purge preparation end flag is 0, and executes the process of S33 when the startup purge preparation end flag is 1.
  • the controller 7 performs a startup purge preparation process. Details of the startup purge preparation process will be described later with reference to FIG.
  • the controller 7 performs a startup purge process. Details of the startup purge process will be described later with reference to FIG.
  • FIG. 6 is a flowchart for explaining the startup purge preparation process.
  • the controller 7 sets the target value of the cathode flow rate during the startup purge operation to a predetermined startup target cathode flow rate Qs.
  • the anode gas is supplied to the buffer tank 51 in order to increase the anode gas concentration in the buffer tank 51.
  • part of the anode gas supplied to the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48. Therefore, the start target cathode flow rate Qs is a value determined in advance by experiments or the like, and is set to a value such that the anode gas concentration in the purge gas is less than the combustible concentration.
  • the controller 7 feedback-controls the cathode compressor 33 so that the cathode flow rate becomes the activation target cathode flow rate Qs.
  • the controller 7 sets the target value of the anode pressure to a predetermined activation target anode upper limit pressure Pau.
  • the activation target anode upper limit pressure Pau is a value determined in advance by experiments or the like, and is set to a value that allows the air in the anode gas flow path 121 to be pushed into the buffer tank 51 together with the anode gas. That is, the controller 7 has a function as a startup operation execution unit that sets the startup target anode upper limit pressure to a value higher than the upper limit pressure value of the anode gas set in S4 of FIG. 4 and executes the startup operation.
  • the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure becomes the activation target anode upper limit pressure Pau.
  • the controller 7 determines whether or not the cathode flow rate is equal to or higher than the activation target cathode flow rate Qs. The controller 7 ends the current process if the cathode flow rate is less than the activation target cathode flow rate Qs, and performs the process of S326 if the cathode flow rate is equal to or greater than the activation target cathode flow rate Qs.
  • step S326 if the anode pressure is less than the activation target anode upper limit pressure Pau, the controller 7 ends the current process. On the other hand, if the anode pressure is equal to or higher than the activation target anode upper limit pressure Pau, the controller 7 determines that the preparation for the activation purge operation is completed, and performs the process of S327. In step S327, the controller 7 sets the startup purge preparation end flag to 1.
  • the controller 7 opens the first purge valve 49 and the second purge valve 50.
  • the controller 7 sets the decompression flag to 1.
  • the depressurization flag is a flag that is set to 1 when the anode pressure is increased to the starting target anode upper limit pressure Pau and then decreased to a predetermined pressure (starting target anode lower limit pressure Pad).
  • the initial value is set to 0. Is set.
  • FIG. 7 is a flowchart for explaining the startup purge process.
  • the controller 7 reads the stack temperature, the first purge valve temperature, and the second purge valve temperature, and selects the highest one of these temperatures as a representative temperature.
  • the controller 7 refers to the map of FIG. 8 and calculates the start purge end time tp based on the representative temperature and the atmospheric pressure.
  • the start purge end time is a time during which it can be determined that the anode gas concentration in the buffer tank 51 has increased to a predetermined concentration at which the pulsation operation can be started by the start purge operation.
  • the start purge end time is set as a time during which it is possible to determine that a predetermined amount of the air existing in the anode system has been discharged to the outside by the start purge operation.
  • the start purge end time is set longer as the representative temperature becomes higher and the atmospheric pressure becomes higher. This is because the flow rate of the gas passing through the first purge valve 49 and the second purge valve 50 changes according to the gas temperature and the upstream and downstream differential pressures of the purge valves 49 and 50. is there. That is, the gas flow rate passing through the first purge valve 49 and the second purge valve 50 decreases as the gas temperature increases and the front-rear differential pressure decreases.
  • the temperature of the gas passing through the first and second purge valves 49 and 50 is assumed to be the highest temperature among the stack temperature, the first purge valve temperature, and the second purge valve temperature, and the first The start purge end time is determined on the assumption that the gas flow rate passing through the second purge valves 49 and 50 is the smallest. Therefore, the anode gas concentration in the buffer tank 51 can be reliably increased to a desired concentration at the start of the pulsation operation after the start purge operation is completed.
  • atmospheric pressure is used as a parameter for calculating the start purge end time. Since the differential pressure across the first purge valve 49 and the second purge valve 50 is the differential pressure between the anode pressure and the atmospheric pressure, if the atmospheric pressure is known, the differential pressure across the first purge valve 49 and the second purge valve 50 is reduced. Can be estimated. That is, it can be detected that the required purge time is shortened because the atmospheric pressure has decreased and the differential pressure across the first purge valve 49 and the second purge valve 50 has increased.
  • the controller 7 determines whether or not the purge timer t1 is equal to or longer than the startup purge end time ttp.
  • the purge timer t1 is an integrated value of the time during which the gas stored in the buffer tank 51 is discharged to the outside through the first purge passage 47 and the second purge passage 48.
  • the controller 7 executes the process of S334 if the purge timer t1 is less than the startup purge end time tp, and executes the process of S339 if the purge timer t1 is greater than or equal to the startup purge end time tp.
  • the controller 7 determines whether or not the decompression flag is set to 1. The controller 7 executes the process of S335 when the decompression flag is set to 1, and executes the process of S336 when the decompression flag is set to 0.
  • the controller 7 performs a decompression process.
  • the decompression process will be described later with reference to FIG.
  • the controller 7 determines whether or not the pressure holding flag is set to 1.
  • the pressure holding flag is a flag that is set to 1 when the anode pressure is reduced to a predetermined pressure (starting target anode lower limit pressure Pad) by the pressure reduction process, and is held at the predetermined pressure.
  • the initial value is set to 0. Is set.
  • the controller 7 executes the process of S337 when the pressure holding flag is set to 1, and executes the process of S338 when the pressure holding flag is set to 0.
  • the controller 7 performs a pressure holding process.
  • the pressure holding process will be described later with reference to FIG.
  • the controller 7 performs a boosting process.
  • the boosting process will be described later with reference to FIG.
  • the controller 7 performs a start purge end process.
  • the startup purge end process will be described later with reference to FIG.
  • FIG. 9 is a flowchart for explaining the decompression process.
  • the mixed gas of the anode gas and air in the buffer tank 51 is discharged from the first and second purge passages 47 and 48 to the cathode gas discharge passage 35, so that the anode pressure supplied to the buffer tank 51 is decreased.
  • the mixed gas flows backward from the buffer tank 51 to the first and second anode gas discharge passages 45 and 46.
  • the controller 7 sets the target value of the anode pressure to a predetermined activation target anode lower limit pressure Pad.
  • the starting target anode lower limit pressure Pad is a value determined in advance by experiments or the like, and the mixed gas in the buffer tank 51 is connected to the first anode gas discharge passage 45 and the first purge passage 47 and the second anode gas discharge passage. 46 and the second purge passage 48 are set to values pushed back to the fuel cell stack 2 side. If the anode gas does not run out in the anode gas flow path 121, the activation target anode lower limit pressure Pad may be set to a value such that the mixed gas in the buffer tank 51 flows back to the fuel cell stack 2. .
  • the above-described starting target anode lower limit pressure is set to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG. That is, the controller 7 has a function as a start-up operation execution unit that sets the start target anode lower limit pressure to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG. 4 and executes the start-up operation.
  • the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure becomes the activation target anode lower limit pressure Pad.
  • the controller 7 determines whether or not the anode pressure is equal to or lower than the activation target anode lower limit pressure.
  • the controller 7 executes the process of S3354 when the anode pressure is higher than the startup target anode lower limit pressure, and executes the process of S3355 when the anode pressure is equal to or lower than the startup target anode lower limit pressure.
  • the controller 7 maintains the decompression flag at 1. On the other hand, the controller 7 sets the pressure reduction flag to 0 in S3355, and sets the pressure holding flag to 1 in S3356.
  • FIG. 10 is a flowchart for explaining the pressure holding process.
  • the anode pressure is held at the starting target anode lower limit pressure Pad. That is, the mixed gas in the buffer tank 51 is more fuel cell stack 2 than the connection portion between the first anode gas discharge passage 45 and the first purge passage 47 and the connection portion between the second anode gas discharge passage 46 and the second purge passage 48. It is adjusted so that the state pushed back to the side is maintained. Thereby, the mixed gas in the buffer tank 51 can be continuously discharged from the first and second purge passages 47 and 48 to the cathode gas discharge passage 35. Furthermore, the anode gas concentration in the buffer tank 51 can be efficiently increased by supplying the anode gas from the upstream side during the subsequent anode pressure increase.
  • the controller 7 sets the target value of the anode pressure to the starting target anode lower limit pressure Pad. That is, the target value of the anode pressure is maintained as the starting target anode lower limit pressure Pad set during the pressure reduction process.
  • the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure is maintained at the activation target anode lower limit pressure Pad.
  • the controller 7 adds the calculation cycle ⁇ t to the previous value of the purge timer t1, and updates the purge timer t1.
  • the controller 7 adds the calculation cycle ⁇ t to the previous value of the pressure holding timer t2, and updates the pressure holding timer t2.
  • the controller 7 determines whether or not the pressure holding timer t2 is equal to or longer than a predetermined pressure holding end time tkd.
  • the controller 7 executes the process of S3376 when the pressure holding timer t2 is less than the pressure holding end time tkd, and executes the process of S3377 when the pressure holding timer t2 is equal to or longer than the pressure holding end time tkd.
  • the controller 7 When the pressure holding timer t2 is less than the pressure holding end time tkd, the controller 7 maintains the pressure holding flag at 1 in S3376.
  • the controller 7 sets the pressure holding flag to 0 in S3377, and updates the value of the pressure holding timer t2 to 0 in S3378. Thereafter, in S3379, the controller 7 sets the boost flag to 1.
  • the pressure increase flag is a flag that is set to 1 when the anode pressure is again increased to the activation target anode upper limit pressure Pau after the pressure holding process, and the initial value is set to 0.
  • FIG. 11 is a flowchart for explaining the boosting process.
  • the pressure increasing process is a process of increasing the anode pressure to the starting target anode upper limit pressure Pau again after the pressure holding process is completed, supplying the anode gas to the buffer tank 51, and increasing the anode gas concentration in the buffer tank 51.
  • the controller 7 sets the target value of the anode pressure to the starting target anode upper limit pressure Pau. Then, the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure rises to the activation target anode upper limit pressure Pau in S3382.
  • the controller 7 determines whether or not the anode pressure is equal to or higher than the activation target anode upper limit pressure.
  • the controller 7 executes the process of S3384 when the anode pressure is less than the activation target anode upper limit pressure, and executes the process of S3385 when the anode pressure is greater than or equal to the activation target anode upper limit pressure.
  • the controller 7 If the anode pressure is less than the activation target anode upper limit pressure, the controller 7 maintains the pressure increase flag at 1 in S3384. On the other hand, when the anode pressure is equal to or higher than the activation target anode upper limit pressure, the controller 7 sets the pressure increase flag to 0 in S3385 and sets the pressure decrease flag to 1 in S3386.
  • FIG. 12 is a flowchart for explaining the startup purge end process.
  • the start purge end process is a process for ending the start purge operation. As shown in FIG. 4, the normal process is executed after the startup purge end process.
  • the controller 7 updates the value of the purge timer t1 for which the startup purge end time has been set to 0. Thereafter, the controller 7 sets the start purge operation end flag to 1 in S3392, and sets the start purge preparation end flag to 0 in S3393.
  • the controller 7 After the processing of S3393, the controller 7 updates the value of the pressure holding timer t2 to 0 in S3394, and sets the decompression flag to 0 in S3395.
  • the controller 7 sets the pressure holding flag to 0. Thereafter, the controller 7 sets the boosting flag to 0 in S3397, and ends the startup purge end process.
  • the anode lower limit pressure Pad is selected from an anode pressure lower limit value map B101, a correction table B102, a multiplier B103, an adder B104, a start purge first half lower limit pressure setter B105, and a start purge second half lower limit pressure setter B106. Set by the device B107.
  • Controller 7 refers to anode pressure lower limit value map B101, and sets the anode pressure lower limit value based on the stack inlet cooling water temperature and the stack outlet cooling water temperature. If the stack outlet cooling water temperature is constant, the anode pressure lower limit value is set to a larger value as the stack inlet cooling water temperature is higher. Furthermore, if the stack inlet cooling water temperature is constant, the anode pressure lower limit value is set to a larger value as the stack outlet cooling water temperature is higher.
  • Controller 7 refers to correction table B102, and calculates a correction value based on HFR (High Frequency Resistance) of fuel cell stack 2.
  • HFR is calculated
  • the internal resistance of the fuel cell stack 2 varies depending on the wet state of the fuel electrolyte membrane 111. Therefore, the wet state of the electrolyte membrane 111 can be indirectly detected by detecting the HFR of the fuel cell stack 2. As the electrolyte membrane 111 dries, the value of HFR increases.
  • the HFR is calculated based on the AC voltage value and the AC current value detected when an AC current is superimposed on the fuel cell stack 2.
  • the method for calculating HFR is not limited to the above method, and for example, a method described in Japanese Patent Application Laid-Open No. 2012-054153 filed by the present applicant may be used.
  • the multiplier B103 multiplies the anode pressure lower limit value set based on the anode pressure lower limit value map B101 by the correction value calculated by the correction table B102. Then, the adder B104 adds the atmospheric pressure to the anode pressure lower limit value corrected by the multiplier B103.
  • the start purge first half lower limit pressure setter B105 sets the anode lower limit pressure for the first half of the start purge based on the atmospheric pressure.
  • the anode lower limit pressure in the first half of the startup purge is set to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG.
  • the starting purge latter half lower limit pressure setter B106 sets the anode lower limit pressure in the latter half of the starting purge based on the atmospheric pressure.
  • the anode lower limit pressure in the latter half of the startup purge is set to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG. Since the purging of impurities progresses in the latter half of the startup purge compared to the first half of the startup purge, the anode lower limit pressure in the latter half of the startup purge when the atmospheric pressure is the same is lower than the anode lower limit pressure in the first half of the startup purge. Is set.
  • the selector B107 selects the anode lower limit pressure calculated by the start purge first half lower limit pressure setter B105 as the anode lower limit pressure Pad. Further, if the selector B107 is the latter half of the startup purge, the selector B107 selects the anode lower limit pressure calculated by the startup purge latter half lower limit pressure setter B106 as the anode lower limit pressure Pad. Further, the selector B107 selects the output signal of the adder B104 as the anode lower limit pressure Pad if it is neither the first half of the startup purge nor the second half of the startup purge.
  • the controller 7 determines whether it is the first half of the start purge, the second half of the start purge, or other than that based on, for example, the elapsed time from when the shutoff valve of the high pressure tank 41 is opened. That is, the controller 7 determines the switching timing of the anode lower limit pressure Pad according to the elapsed time (second predetermined period) from the start of the startup purge operation. This switching timing may be corrected according to atmospheric pressure, stack temperature, or the like.
  • the setting of the anode maximum pressure limit value is executed by the controller 7.
  • the controller 7 diagnoses the differential pressure between the cathode gas flow path side pressure and the anode gas flow path side pressure, and controls the anode gas pressure and the cathode gas pressure so that the differential pressure does not become excessive.
  • the controller 7 executes the differential pressure diagnosis based on whether or not the anode side pressure exceeds the allowable value (anode maximum pressure limit value) based on the cathode side pressure.
  • the controller 7 may be configured to make a differential pressure diagnosis based on whether or not the differential pressure between the anode gas flow path side pressure and the cathode gas flow path side pressure is smaller than the allowable differential pressure (determination threshold).
  • the anode maximum pressure limit value is set by the pressure loss subtractor B201, the select high device B202, the error subtractor B203, the allowable differential pressure selector B204, and the adder B205.
  • Pressure loss subtractor B201 subtracts the maximum value (constant value) of the WRD side pressure loss (SWEEP side pressure loss) from the pressure of the cathode gas upstream of the WRD 36 that humidifies the cathode gas.
  • the select high device B202 outputs the higher one of the cathode gas pressure calculated by the pressure loss subtractor B201 and the atmospheric pressure detected by the atmospheric pressure sensor 76 as the basic cathode gas pressure.
  • the error subtractor B203 subtracts the control error (constant) from the basic cathode gas pressure output from the select high device B202. As described above, the error subtractor B203 calculates the corrected cathode gas pressure.
  • the permissible differential pressure selector B204 selects a permissible differential pressure at start-up (constant) at the time of start-up, and selects a permissible differential pressure (constant) other than at start-up that is smaller than the permissible differential pressure at start-up after a lapse of a predetermined period from the start-up.
  • the controller 7 determines the allowable differential pressure switching timing according to the elapsed time (first predetermined period) from the start of the startup purge operation. This switching timing may be corrected according to atmospheric pressure, stack temperature, or the like. Note that the switching in B204 is performed after the switching of the anode lower limit pressure Pad in the selector B107.
  • the adder B205 adds the selected allowable differential pressure to the corrected cathode gas pressure calculated by the error subtractor B203.
  • the value calculated by the adder B205 is the anode maximum pressure limit value required for preventing the differential pressure from being excessive.
  • the start purge operation end flag and the start purge preparation end flag are set to 0, so the start purge preparation process is performed (S32).
  • the cathode compressor 33 is feedback-controlled so that the cathode flow rate increases to the startup target cathode flow rate Qs at a predetermined change rate (S322), and the anode target is started at the predetermined change rate.
  • the pressure regulating valve 43 is feedback-controlled so as to increase to the upper limit pressure Pau1 (S324).
  • the startup purge preparation end flag is set to 1 (S327).
  • the first purge valve 49 and the second purge valve 50 are opened (S328).
  • the decompression flag is set to 1 (S329).
  • start purge processing is performed (S33). Since the value of the purge timer t1 is 0 and the decompression flag is 1 at the start of the startup purge process, the decompression process is performed (S335).
  • the pressure regulating valve 43 is feedback-controlled so that the anode pressure decreases to the activation target anode lower limit pressure Pad1 (S3352).
  • the pressure reduction flag is set to 0 (S3355), and the pressure holding flag is set to 1 (S3356).
  • a pressure holding process is performed (S337).
  • the anode pressure is held at the activation target anode lower limit pressure Pad1.
  • the time during which the anode pressure is held at the activation target anode lower limit pressure Pad1 is counted by the pressure holding timer t2 (S3374).
  • the mixed gas in the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48.
  • the time during which the mixed gas is actually discharged to the outside through the first and second purge passages 47 and 48 is counted by the purge timer t1 (S3373).
  • the pressure regulating valve 43 is feedback-controlled so that the anode pressure rises again to the activation target anode upper limit pressure Pau1 (S3382).
  • the anode lower limit pressure is switched to the pressure Pad2 for the second half of the start purge by the selector B107 in FIG.
  • the pressure regulating valve 43 is feedback-controlled so that the anode pressure decreases to the activation target anode lower limit pressure Pad2.
  • the allowable differential pressure selector B204 in FIG. 14 switches the allowable differential pressure from the allowable differential pressure at the time of startup to an allowable differential pressure smaller than the allowable differential pressure at the time of startup.
  • the anode maximum pressure limit value is changed.
  • the allowable differential pressure corresponds to the determination threshold value of the differential pressure diagnosis unit in the claims.
  • the anode pressure is controlled between the upper limit pressure Pau2 and the lower limit pressure Pad2, and the pressure holding process and the pressure reducing process are sequentially performed in the same manner as at times t13 to t16. To be executed.
  • the anode pressure is limited to be smaller than the anode maximum pressure limit value so that the differential pressure from the cathode pressure does not become excessive.
  • the anode gas concentration (hydrogen concentration) in the buffer tank 51 is increased to a desired concentration by repeating the depressurization process, the pressure holding process, and the pressure increase process in the first half and the second half of the startup purge as described above. Can be made.
  • the anode pressure is increased to the start target anode upper limit pressure, so that air that has entered the anode system while the system is stopped is put into the buffer tank 51 together with the anode gas. Push in. Thereafter, the mixed gas in the buffer tank 51 is caused to flow back into the first anode gas discharge passage 45 and the second anode gas discharge passage 46 by lowering the anode pressure to the target anode lower limit pressure. Further, when the fuel cell system 1 is started, the first purge valve 49 and the second purge valve 50 are controlled to open.
  • the mixed gas in the buffer tank 51 can be discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48, and the anode gas concentration in the buffer tank 51 is gradually increased. Can be raised. Therefore, even when the anode off-gas in the buffer tank 51 flows backward to the anode gas passage 121 during the pulsation operation after the start purge operation, the anode gas used for the electrode reaction is insufficient in the downstream region of the anode gas passage 121. Can be suppressed. Accordingly, a decrease in power generation efficiency in the fuel cell stack 2 can be suppressed, and further deterioration of the fuel cell stack 2 can be suppressed.
  • the purge timer t1 is counted only when the mixed gas in the buffer tank 51 is actually discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48, that is, during the pressure holding process. This is because the anode gas supplied from the high-pressure tank 41 is discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48, not the mixed gas in the buffer tank 51 during the pressure reduction processing or the pressure increase processing. This is because there is a possibility of being. By counting the purge timer t1 only during the pressure holding process, it can be accurately determined that the anode gas concentration in the buffer tank 51 has increased to the desired concentration.
  • the pressure at the start of startup is reduced when a predetermined period has elapsed from the start of the startup purge operation. That is, at the start of the startup purge operation, the controller 7 increases the pulsation upper limit pressure of the anode gas so as to be higher than the pulsation upper limit pressure of the anode gas set in S4 (normal processing) in FIG. When the predetermined period has passed, the pulsation upper limit pressure at the start of activation is lowered. Since it did in this way, the fall of durability of the components which comprise the fuel cell 10 like the electrolyte membrane 111 grade
  • the controller 7 increases the anode gas pulsation lower limit pressure to be higher than the anode gas pulsation lower limit pressure set in S4 (normal processing) in FIG.
  • the pulsation lower limit pressure at the start of start is reduced. Since it did in this way, the fall of durability of the components which comprise the fuel cell 10 like the electrolyte membrane 111 grade
  • the anode lower limit pressure is first lowered from Pad1 to Pad2, and then the allowable differential pressure (judgment threshold for differential pressure diagnosis) is lowered to increase the anode maximum The pressure limit value was lowered.
  • the decrease timing of the anode lower limit pressure is defined as being based on the second predetermined period, and the decrease timing of the allowable differential pressure (the differential pressure diagnosis determination threshold), that is, the decrease timing of the anode upper limit pressure. Is defined as being based on a predetermined period set longer than the second predetermined period.
  • the allowable differential pressure is first lowered and then the anode lower limit pressure is lowered, there is a possibility that an erroneous diagnosis occurs in the differential pressure diagnosis.
  • the anode lower limit pressure during the start purge operation is lowered, and then the allowable differential pressure is lowered to lower the anode maximum pressure limit value, thereby preventing the occurrence of misdiagnosis in the differential pressure diagnosis. Is possible.

Abstract

A fuel-cell system in which an anode gas is supplied intermittently in a pulsing manner. Said fuel-cell system is provided with the following: a ceiling setting unit that sets an anode-gas pressure-pulse ceiling in accordance with the pressure of a cathode gas; a purging control unit that controls the purging of anode gas discharged from a fuel cell; a startup-sequence execution unit that executes a fuel-cell-system startup sequence, at the beginning of which the anode-gas pressure-pulse ceiling is increased above the anode-gas pressure-pulse ceiling set by the ceiling setting unit; and an anode-pressure control unit that, once a prescribed amount of time has elapsed since the beginning of the startup sequence, decreases the pressure-pulse ceiling relative to the beginning of the startup sequence.

Description

燃料電池システムFuel cell system
　この発明は、燃料電池システムに関する。 This invention relates to a fuel cell system.
　特表２００７－５１７３６９号公報は、高圧のアノードガスが間欠的に脈動供給される燃料電池システムを開示する。高圧のアノードガスが燃料電池に供給されると、アノード流路に滞留する不純物、つまり発電時に生成された水分やカソード流路から電解質膜を透過してきた空気（主に窒素)がバッファタンクへ押し込まれ、アノード流路内のアノードガスの濃度が高くなる。その後、アノードガスの供給が停止され、この状態で発電が継続すると、アノード流路内のアノードガスが消費され、アノード流路の圧力が低下する。このようにアノード流路内の圧力が低下すると、バッファタンクから逆流してくる不純物や、カソード側からリークしてくる不純物が増加する。そのため、再び、高圧のアノードガスが燃料電池に供給される。この繰り返しによって、アノード流路内のアノードガスの濃度が維持され、発電が継続される。 Japanese Patent Publication No. 2007-517369 discloses a fuel cell system in which a high-pressure anode gas is intermittently supplied in a pulsating manner. When high-pressure anode gas is supplied to the fuel cell, impurities that stay in the anode channel, that is, moisture generated during power generation and air that has permeated the electrolyte membrane from the cathode channel (mainly nitrogen) are pushed into the buffer tank. This increases the concentration of the anode gas in the anode channel. Thereafter, the supply of the anode gas is stopped, and when power generation continues in this state, the anode gas in the anode channel is consumed, and the pressure in the anode channel decreases. When the pressure in the anode flow path decreases in this way, impurities flowing backward from the buffer tank and impurities leaking from the cathode side increase. Therefore, the high-pressure anode gas is again supplied to the fuel cell. By repeating this, the concentration of the anode gas in the anode flow path is maintained, and power generation is continued.
　燃料電池システムのアノード流路内にカソード側から透過してきた空気等が存在すると、燃料電池の再起動時に、アノード流路内の空気によって燃料電池の触媒が劣化する。そこで、燃料電池システムでは、システム起動時にアノードガスの供給圧力を高めることで、このような空気を早期にバッファタンクへと追い出す。これにより、駆動時における空気等の不純物に対応することが可能となる。しかしながら、燃料電池の電解質膜は薄い部材であるため、カソード側の圧力を考慮せずにアノード圧力を高めると、電解質膜に悪影響を及ぼしてしまう。 If air or the like permeated from the cathode side exists in the anode flow path of the fuel cell system, the fuel cell catalyst deteriorates due to the air in the anode flow path when the fuel cell is restarted. Therefore, in the fuel cell system, such air is expelled to the buffer tank at an early stage by increasing the supply pressure of the anode gas when the system is activated. Thereby, it becomes possible to cope with impurities such as air during driving. However, since the electrolyte membrane of a fuel cell is a thin member, if the anode pressure is increased without considering the pressure on the cathode side, the electrolyte membrane will be adversely affected.
　本発明の目的は、燃料電池を構成する部品のシステム起動時における耐久性の低下を抑制可能な燃料電池システムを提供することである。 An object of the present invention is to provide a fuel cell system capable of suppressing a decrease in durability at the time of system startup of components constituting the fuel cell.
　本発明のある態様によれば、アノードガスを間欠的に脈動供給する燃料電池システムが提供される。燃料電池システムは、カソードガスの圧力に応じてアノードガスの脈動上限圧を設定する上限設定部と、燃料電池から排出されたアノードガスのパージを制御するパージ制御部と、を備える。また、燃料電池システムは、前記燃料電池システムの起動運転開始時には、前記上限設定部によって設定されたアノードガスの脈動上限圧よりも高くなるようにアノードガスの脈動上限圧を上げ、起動運転を実行する起動運転実行部と、起動運転開始から所定期間が過ぎたら、起動開始時の脈動上限圧を下げるアノード圧制御部と、を備える。 According to an aspect of the present invention, there is provided a fuel cell system that intermittently pulsates the anode gas. The fuel cell system includes an upper limit setting unit that sets the pulsation upper limit pressure of the anode gas according to the pressure of the cathode gas, and a purge control unit that controls the purge of the anode gas discharged from the fuel cell. In addition, the fuel cell system increases the anode gas pulsation upper limit pressure to be higher than the anode gas pulsation upper limit pressure set by the upper limit setting unit at the start of the fuel cell system start-up operation, and executes the start-up operation. A start-up operation executing unit, and an anode pressure control unit that lowers the pulsation upper limit pressure at the start of start-up when a predetermined period has elapsed from the start of the start-up operation.
図１Ａは、本発明の一実施形態による燃料電池の斜視図である。FIG. 1A is a perspective view of a fuel cell according to an embodiment of the present invention. 図１Ｂは、図１ＡのＢ－Ｂに沿う燃料電池の縦断面図である。FIG. 1B is a longitudinal sectional view of the fuel cell taken along the line BB in FIG. 1A. 図２は、本発明の実施形態によるアノードガス非循環型の燃料電池システムの概略構成図である。FIG. 2 is a schematic configuration diagram of an anode gas non-circulating fuel cell system according to an embodiment of the present invention. 図３は、燃料電池システムの脈動運転について説明する図である。FIG. 3 is a diagram for explaining the pulsation operation of the fuel cell system. 図４は、燃料電池システムのシステム制御を示すフローチャートである。FIG. 4 is a flowchart showing system control of the fuel cell system. 図５は、起動パージ運転処理を示すフローチャートである。FIG. 5 is a flowchart showing the startup purge operation process. 図６は、起動パージ準備処理を示すフローチャートである。FIG. 6 is a flowchart showing the startup purge preparation process. 図７は、起動パージ処理を示すフローチャートである。FIG. 7 is a flowchart showing the startup purge process. 図８は、代表温度と大気圧とに基づいて起動パージ終了時間を算出するためのマップである。FIG. 8 is a map for calculating the start purge end time based on the representative temperature and the atmospheric pressure. 図９は、減圧処理を示すフローチャートである。FIG. 9 is a flowchart showing the decompression process. 図１０は、圧力保持処理を示すフローチャートである。FIG. 10 is a flowchart showing the pressure holding process. 図１１は、昇圧処理を示すフローチャートである。FIG. 11 is a flowchart showing the boosting process. 図１２は、起動パージ終了処理を示すフローチャートである。FIG. 12 is a flowchart showing the startup purge end process. 図１３は、アノード下限圧の設定方法を示すブロック図である。FIG. 13 is a block diagram showing a method for setting the anode lower limit pressure. 図１４は、差圧過大を防止するために要求されるアノード最大圧力制限値を設定する設定部を示すブロック図である。FIG. 14 is a block diagram showing a setting unit for setting a maximum anode pressure limit value required for preventing an excessive differential pressure. 図１５は、燃料電池システムのシステム動作を示すタイムチャートである。FIG. 15 is a time chart showing the system operation of the fuel cell system.
　以下、図面等を参照して、本発明の実施形態について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　燃料電池は、燃料極としてのアノード電極と、酸化剤極としてのカソード電極と、これら電極に挟まれるように配置される電解質膜と、から構成されている。燃料電池は、アノード電極に供給される水素を含有するアノードガス及びカソード電極に供給される酸素を含有するカソードガスを用いて発電する。アノード電極及びカソード電極の両電極において進行する電極反応は、以下の通りである。 The fuel cell includes an anode electrode as a fuel electrode, a cathode electrode as an oxidant electrode, and an electrolyte membrane disposed so as to be sandwiched between these electrodes. The fuel cell generates electric power using an anode gas containing hydrogen supplied to the anode electrode and a cathode gas containing oxygen supplied to the cathode electrode. The electrode reaction that proceeds in both the anode electrode and the cathode electrode is as follows.
　　　アノード電極：　２Ｈ2 → ４Ｈ+＋４ｅ-           ・・・（１）
　　　カソード電極：　４Ｈ+＋４ｅ-＋Ｏ2 → ２Ｈ2Ｏ    ・・・（２） Anode electrode: 2H 2 → 4H + + 4e − (1)
Cathode electrode: 4H + + 4e − + O 2 → 2H 2 O (2)
　この（１）及び（１）の電極反応によって、燃料電池は１ボルト程度の起電力を生じる。 The fuel cell generates an electromotive force of about 1 volt by the electrode reactions (1) and (1).
　図１Ａ及び図１Ｂは、本発明の一実施形態による燃料電池１０の構成を説明する図である。図１Ａは燃料電池１０の概略斜視図であり、図１（Ｂ）は図１（Ａ）の燃料電池１０のＢ－Ｂ断面図である。 1A and 1B are diagrams illustrating the configuration of a fuel cell 10 according to an embodiment of the present invention. FIG. 1A is a schematic perspective view of the fuel cell 10, and FIG. 1B is a cross-sectional view taken along the line BB of the fuel cell 10 of FIG.
　燃料電池１０の膜電極接合体（ＭＥＡ）１１の表裏には、アノードセパレータ１２とカソードセパレータ１３が配置される。 An anode separator 12 and a cathode separator 13 are arranged on the front and back of the membrane electrode assembly (MEA) 11 of the fuel cell 10.
　ＭＥＡ１１は、電解質膜１１１と、アノード電極１１２と、カソード電極１１３と、を備える。電解質膜１１１の一方の面側にアノード電極１１２が配置され、電解質膜１１１の他方の面側にカソード電極１１３が配置される。 The MEA 11 includes an electrolyte membrane 111, an anode electrode 112, and a cathode electrode 113. An anode electrode 112 is disposed on one surface side of the electrolyte membrane 111, and a cathode electrode 113 is disposed on the other surface side of the electrolyte membrane 111.
　電解質膜１１１は、フッ素系樹脂により形成されたプロトン伝導性のイオン交換膜である。電解質膜１１１は、湿潤状態で良好なプロトン伝導性を示す。 The electrolyte membrane 111 is a proton conductive ion exchange membrane formed of a fluorine-based resin. The electrolyte membrane 111 exhibits good proton conductivity in a wet state.
　アノード電極１１２は、触媒層１１２ａと、ガス拡散層１１２ｂとを備える。触媒層１１２ａは、電解質膜１１１と接する。触媒層１１２ａは、白金や白金合金等が担持されたカーボンブラック粒子から形成される。ガス拡散層１１２ｂは、触媒層１１２ａの外側に設けられ、アノードセパレータ１２と接する。ガス拡散層１１２ｂは、十分なガス拡散性および導電性を有する部材、例えば炭素繊維からなる糸で織成したカーボンクロス、により形成される。 The anode electrode 112 includes a catalyst layer 112a and a gas diffusion layer 112b. The catalyst layer 112a is in contact with the electrolyte membrane 111. The catalyst layer 112a is formed from carbon black particles carrying platinum or a platinum alloy. The gas diffusion layer 112b is provided outside the catalyst layer 112a and is in contact with the anode separator 12. The gas diffusion layer 112b is formed of a member having sufficient gas diffusibility and conductivity, for example, a carbon cloth woven with yarns made of carbon fibers.
　カソード電極１１３もアノード電極１１２と同様に、触媒層１１３ａと、ガス拡散層１１３ｂとを備える。 Similarly to the anode electrode 112, the cathode electrode 113 includes a catalyst layer 113a and a gas diffusion layer 113b.
　アノードセパレータ１２は、ガス拡散層１１２ｂと接する。アノードセパレータ１２は、ガス拡散層１１２ｂと接する側に、アノード電極１１２に対してアノードガスを供給するための溝状のアノードガス流路１２１を複数有する。 The anode separator 12 is in contact with the gas diffusion layer 112b. The anode separator 12 has a plurality of groove-like anode gas passages 121 for supplying anode gas to the anode electrode 112 on the side in contact with the gas diffusion layer 112b.
　カソードセパレータ１３は、ガス拡散層１１３ｂと接する。カソードセパレータ１３は、ガス拡散層１１３ｂと接する側に、カソード電極１１３に対してカソードガスを供給するための溝状のカソードガス流路１３１を複数有する。 The cathode separator 13 is in contact with the gas diffusion layer 113b. The cathode separator 13 has a plurality of groove-like cathode gas flow paths 131 for supplying cathode gas to the cathode electrode 113 on the side in contact with the gas diffusion layer 113b.
　アノードセパレータ１２及びカソードセパレータ１３は、アノードガス流路１２１を流れるアノードガスの流れ方向とカソードガス流路１３１を流れるカソードガスの流れ方向とが互いに逆向きかつ平行となるように構成されている。なお、アノードセパレータ１２及びカソードセパレータ１３は、これらガスの流れ方向が同じ向きかつ平行に流れるように構成されてもよい。 The anode separator 12 and the cathode separator 13 are configured such that the flow direction of the anode gas flowing through the anode gas flow path 121 and the flow direction of the cathode gas flowing through the cathode gas flow path 131 are opposite and parallel to each other. The anode separator 12 and the cathode separator 13 may be configured such that the flow directions of these gases flow in the same direction and in parallel.
　このような燃料電池１０を自動車用電源として使用する場合には、要求される電力が大きいため、数百枚の燃料電池１０を積層した燃料電池スタックが構成される。そして、燃料電池スタックにアノードガス及びカソードガスを供給する燃料電池システムを構成して、車両を駆動させるための電力を取り出す。 When such a fuel cell 10 is used as a power source for an automobile, a large amount of electric power is required, so that a fuel cell stack in which several hundred fuel cells 10 are stacked is configured. Then, a fuel cell system for supplying anode gas and cathode gas to the fuel cell stack is configured, and electric power for driving the vehicle is taken out.
　図２は、本発明の一実施形態によるアノードガス非循環型の燃料電池システム１の概略構成図である。 FIG. 2 is a schematic configuration diagram of an anode gas non-circulating fuel cell system 1 according to an embodiment of the present invention.
　燃料電池システム１は、燃料電池スタック２と、カソードガス給排装置３と、アノードガス給排装置４と、スタック冷却装置６と、コントローラ７と、を備える。 The fuel cell system 1 includes a fuel cell stack 2, a cathode gas supply / discharge device 3, an anode gas supply / discharge device 4, a stack cooling device 6, and a controller 7.
　燃料電池スタック２は、複数枚の燃料電池１０を積層した電池である。燃料電池スタック２は、アノードガス及びカソードガスの供給を受けて、車両の駆動に必要な電力を発電する。 The fuel cell stack 2 is a battery in which a plurality of fuel cells 10 are stacked. The fuel cell stack 2 receives the supply of the anode gas and the cathode gas and generates electric power necessary for driving the vehicle.
　カソードガス給排装置３は、カソードガス供給通路３１と、フィルタ３２と、カソードコンプレッサ３３と、エアフローセンサ３４と、カソードガス排出通路３５と、Water Recovery Device（ＷＲＤ)３６と、圧力センサ３７と、を備える。 The cathode gas supply / discharge device 3 includes a cathode gas supply passage 31, a filter 32, a cathode compressor 33, an air flow sensor 34, a cathode gas discharge passage 35, a Water Recovery Device (WRD) 36, a pressure sensor 37, Is provided.
　カソードガス供給通路３１は、燃料電池スタック２に供給するカソードガスが流れる通路である。カソードガス供給通路３１の一端はフィルタ３２に接続され、他端は燃料電池スタック２のカソードガス入口孔２１に接続される。 The cathode gas supply passage 31 is a passage through which the cathode gas supplied to the fuel cell stack 2 flows. One end of the cathode gas supply passage 31 is connected to the filter 32, and the other end is connected to the cathode gas inlet hole 21 of the fuel cell stack 2.
　フィルタ３２は、カソードガス供給通路３１に取り込むカソードガスに含まれる異物を取り除く。 The filter 32 removes foreign matters contained in the cathode gas taken into the cathode gas supply passage 31.
　カソードコンプレッサ３３は、カソードガス供給通路３１に設けられる。カソードコンプレッサ３３は、フィルタ３２を介してカソードガスとしての空気をカソードガス供給通路３１に取り込み、燃料電池スタック２に供給する。 The cathode compressor 33 is provided in the cathode gas supply passage 31. The cathode compressor 33 takes in air as cathode gas through the filter 32 into the cathode gas supply passage 31 and supplies it to the fuel cell stack 2.
　エアフローセンサ３４は、カソードコンプレッサ３３よりも上流のカソードガス供給通路３１に設けられる。エアフローセンサ３４は、カソードガス供給通路３１を流れるカソードガスの流量を検出する。 The air flow sensor 34 is provided in the cathode gas supply passage 31 upstream of the cathode compressor 33. The air flow sensor 34 detects the flow rate of the cathode gas flowing through the cathode gas supply passage 31.
　カソードガス排出通路３５は、燃料電池スタック２から排出されるカソードオフガスが流れる通路である。カソードガス排出通路３５一端は燃料電池スタック２のカソードガス出口孔２２に接続され、他端は開口端として形成される。 The cathode gas discharge passage 35 is a passage through which the cathode off gas discharged from the fuel cell stack 2 flows. One end of the cathode gas discharge passage 35 is connected to the cathode gas outlet hole 22 of the fuel cell stack 2, and the other end is formed as an open end.
　ＷＲＤ３６は、燃料電池スタック２から排出されるカソードオフガスを利用して、燃料電池スタック２に供給するカソードガスを加湿する。 The WRD 36 humidifies the cathode gas supplied to the fuel cell stack 2 using the cathode off gas discharged from the fuel cell stack 2.
　圧力センサ３７は、ＷＲＤ３６の上流の圧力を検出する。 The pressure sensor 37 detects the pressure upstream of the WRD 36.
　アノードガス給排装置４は、高圧タンク４１と、アノードガス供給通路４２と、調圧弁４３と、圧力センサ４４と、第１アノードガス排出通路４５と、第２アノードガス排出通路４６と、第１パージ通路４７と、第２パージ通路４８と、第１パージ弁４９と、第２パージ弁５０と、バッファタンク５１と、を備える。 The anode gas supply / discharge device 4 includes a high pressure tank 41, an anode gas supply passage 42, a pressure regulating valve 43, a pressure sensor 44, a first anode gas discharge passage 45, a second anode gas discharge passage 46, a first A purge passage 47, a second purge passage 48, a first purge valve 49, a second purge valve 50, and a buffer tank 51 are provided.
　高圧タンク４１は、燃料電池スタック２に供給するアノードガスを高圧状態に保って貯蔵する。 The high pressure tank 41 stores the anode gas supplied to the fuel cell stack 2 in a high pressure state.
　アノードガス供給通路４２は、高圧タンク４１から排出されたアノードガスを燃料電池スタック２に供給するための通路である。アノードガス供給通路４２の一端は高圧タンク４１に接続され、他端は燃料電池スタック２のアノードガス入口孔２３に接続される。 The anode gas supply passage 42 is a passage for supplying the anode gas discharged from the high-pressure tank 41 to the fuel cell stack 2. One end of the anode gas supply passage 42 is connected to the high pressure tank 41, and the other end is connected to the anode gas inlet hole 23 of the fuel cell stack 2.
　調圧弁４３は、アノードガス供給通路４２に設けられる。調圧弁４３は、高圧タンク４１から排出されたアノードガスを所望の圧力に調節して燃料電池スタック２に供給する。調圧弁４３は、連続的又は段階的に開度を調節することができる電磁弁である。調圧弁４３の開度は、コントローラ７によって制御される。 The pressure regulating valve 43 is provided in the anode gas supply passage 42. The pressure regulating valve 43 adjusts the anode gas discharged from the high-pressure tank 41 to a desired pressure and supplies it to the fuel cell stack 2. The pressure regulating valve 43 is an electromagnetic valve capable of adjusting the opening degree continuously or stepwise. The opening degree of the pressure regulating valve 43 is controlled by the controller 7.
　圧力センサ４４は、調圧弁４３よりも下流のアノードガス供給通路４２に設けられる。圧力センサ４４は、アノードガス供給通路４２の圧力を検出する。本実施形態では、圧力センサ４４で検出した圧力を、燃料電池スタック２の各アノードガス流路１２１とバッファタンク５１とを含むアノード系全体の圧力として代用する。 The pressure sensor 44 is provided in the anode gas supply passage 42 downstream of the pressure regulating valve 43. The pressure sensor 44 detects the pressure in the anode gas supply passage 42. In the present embodiment, the pressure detected by the pressure sensor 44 is used as the pressure of the entire anode system including each anode gas flow path 121 and the buffer tank 51 of the fuel cell stack 2.
　第１アノードガス排出通路４５の一端は燃料電池スタック２の第１アノードガス出口孔２４に接続され、他端はバッファタンク５１に接続される。第１アノードガス排出通路４５には、電極反応に使用されなかった余剰のアノードガスと、カソード側からアノードガス流路１２１へと透過してきた窒素や水蒸気などの不活性ガスとの混合ガス、いわゆるアノードオフガスが排出される。 One end of the first anode gas discharge passage 45 is connected to the first anode gas outlet hole 24 of the fuel cell stack 2, and the other end is connected to the buffer tank 51. In the first anode gas discharge passage 45, a mixed gas of surplus anode gas that has not been used for the electrode reaction and an inert gas such as nitrogen or water vapor that has permeated from the cathode side to the anode gas flow path 121, so-called The anode off gas is discharged.
　第２アノードガス排出通路４６の一端は燃料電池スタック２の第２アノードガス出口孔２５に接続され、他端はバッファタンク５１に接続される。第２アノードガス排出通路４６には、燃料電池スタック２からのアノードオフガスが排出される。 One end of the second anode gas discharge passage 46 is connected to the second anode gas outlet hole 25 of the fuel cell stack 2, and the other end is connected to the buffer tank 51. The anode off gas from the fuel cell stack 2 is discharged into the second anode gas discharge passage 46.
　第１パージ通路４７の一端は第１アノードガス排出通路４５に接続され、他端はカソードガス排出通路３５に接続される。また、第２パージ通路４８の一端は第２アノードガス排出通路４６に接続され、他端はカソードガス排出通路３５に接続される。 One end of the first purge passage 47 is connected to the first anode gas discharge passage 45 and the other end is connected to the cathode gas discharge passage 35. One end of the second purge passage 48 is connected to the second anode gas discharge passage 46, and the other end is connected to the cathode gas discharge passage 35.
　第１パージ弁４９は、第１パージ通路４７に設けられる。第１パージ弁４９は全開又は全閉する電磁弁であって、第１パージ弁４９の開度はコントローラ７によって制御される。第１パージ弁４９の内部にはウォータジャケットが形成されており、第１パージ弁４９はウォータジャケットを通じて燃料電池スタック２の冷却水が循環するように構成されている。これにより、凍結に起因する弁固着が防止される。 The first purge valve 49 is provided in the first purge passage 47. The first purge valve 49 is an electromagnetic valve that is fully opened or closed, and the opening degree of the first purge valve 49 is controlled by the controller 7. A water jacket is formed inside the first purge valve 49, and the first purge valve 49 is configured to circulate the cooling water of the fuel cell stack 2 through the water jacket. Thereby, valve sticking resulting from freezing is prevented.
　第２パージ弁５０は、第２パージ通路４８に設けられる。第２パージ弁５０は全開又は全閉する電磁弁であって、第２パージ弁５０の開度はコントローラ７によって制御される。第２パージ弁５０の内部にはウォータジャケットが形成されており、第２パージ弁５０はウォータジャケットを通じて燃料電池スタック２の冷却水が循環するように構成されている。これにより、凍結に起因する弁固着が防止される。 The second purge valve 50 is provided in the second purge passage 48. The second purge valve 50 is an electromagnetic valve that is fully opened or completely closed, and the opening degree of the second purge valve 50 is controlled by the controller 7. A water jacket is formed inside the second purge valve 50, and the second purge valve 50 is configured such that the cooling water of the fuel cell stack 2 circulates through the water jacket. Thereby, valve sticking resulting from freezing is prevented.
　第１パージ弁４９及び第２パージ弁５０を開閉することで、バッファタンク５１から第１パージ通路４７及び第２パージ通路４８を通じて外部へと排出されるアノードオフガスの排出量が調節される。このようにアノードオフガスが排出されることで、バッファタンク５１内のアノードガスの濃度が所定濃度に調整される。 By opening and closing the first purge valve 49 and the second purge valve 50, the discharge amount of the anode off gas discharged from the buffer tank 51 to the outside through the first purge passage 47 and the second purge passage 48 is adjusted. By discharging the anode off gas in this way, the concentration of the anode gas in the buffer tank 51 is adjusted to a predetermined concentration.
　バッファタンク５１内のアノードガス濃度（水素濃度）が低すぎると、脈動運転時において電極反応に使用されるアノードガスが不足し、発電効率が低下するとともに燃料電池１０が劣化する。これに対して、バッファタンク５１内のアノードガス濃度が高すぎると、パージ通路４７，４８を通じて外部へ排出されるアノードガスの量が増加し、燃費が悪化する。したがって、燃料電池システム１では、バッファタンク５１内のアノードガス濃度は、発電効率及び燃費を考慮した適切な値に制御される。 If the anode gas concentration (hydrogen concentration) in the buffer tank 51 is too low, the anode gas used for the electrode reaction during the pulsation operation is insufficient, and the power generation efficiency is lowered and the fuel cell 10 is deteriorated. On the other hand, if the anode gas concentration in the buffer tank 51 is too high, the amount of the anode gas discharged to the outside through the purge passages 47 and 48 increases, and the fuel consumption deteriorates. Therefore, in the fuel cell system 1, the anode gas concentration in the buffer tank 51 is controlled to an appropriate value in consideration of power generation efficiency and fuel consumption.
　バッファタンク５１は、第１アノードガス排出通路４５及び第２アノードガス排出通路４６を通過したアノードオフガスを一時的に蓄える容器である。バッファタンク５１内のアノードオフガスは、第１パージ弁４９及び第２パージ弁５０が開かれた時に、第１パージ通路４７及び第２パージ通路４８を通ってカソードガス排出通路３５に排出される。その結果、アノードオフガスとカソードオフガスとの混合ガス（パージガス）がカソードガス排出通路３５の開口端から外部へ排出される。このように、アノードオフガスをカソードオフガスに混合させて排出することで、パージガス中の水素濃度が所定の可燃濃度未満となるようにしている。 The buffer tank 51 is a container that temporarily stores the anode off gas that has passed through the first anode gas discharge passage 45 and the second anode gas discharge passage 46. The anode off gas in the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first purge passage 47 and the second purge passage 48 when the first purge valve 49 and the second purge valve 50 are opened. As a result, a mixed gas (purge gas) of the anode off gas and the cathode off gas is discharged from the open end of the cathode gas discharge passage 35 to the outside. In this way, the anode off gas is mixed with the cathode off gas and discharged, so that the hydrogen concentration in the purge gas becomes less than a predetermined combustible concentration.
　スタック冷却装置６は、燃料電池スタック２を冷却し、燃料電池スタック２を発電に適した温度に保つ装置である。スタック冷却装置６は、冷却水循環通路６１と、ラジエータ６２と、バイパス通路６３と、三方弁６４と、循環ポンプ６５と、ＰＴＣヒータ６６と、第１パージ弁循環通路６７と、第２パージ弁循環通路６８と、入口水温センサ６９と、出口水温センサ７０と、第１パージ弁温度センサ７１と、第２パージ弁温度センサ７２と、を備える。 The stack cooling device 6 is a device that cools the fuel cell stack 2 and maintains the fuel cell stack 2 at a temperature suitable for power generation. The stack cooling device 6 includes a coolant circulation passage 61, a radiator 62, a bypass passage 63, a three-way valve 64, a circulation pump 65, a PTC heater 66, a first purge valve circulation passage 67, and a second purge valve circulation. A passage 68, an inlet water temperature sensor 69, an outlet water temperature sensor 70, a first purge valve temperature sensor 71, and a second purge valve temperature sensor 72 are provided.
　冷却水循環通路６１は、燃料電池スタック２を冷却するための冷却水が循環する通路である。冷却水循環通路６１の一端は燃料電池スタック２の冷却水入口孔２６に接続され、他端は燃料電池スタック２の冷却水出口孔２７に接続される。以下では、冷却水循環通路６１のうち、冷却水出口孔２７側を上流側、冷却水入口孔２６側を下流側として説明する。 The cooling water circulation passage 61 is a passage through which cooling water for cooling the fuel cell stack 2 circulates. One end of the coolant circulation path 61 is connected to the coolant inlet hole 26 of the fuel cell stack 2, and the other end is connected to the coolant outlet hole 27 of the fuel cell stack 2. Hereinafter, the cooling water circulation passage 61 will be described with the cooling water outlet hole 27 side as the upstream side and the cooling water inlet hole 26 side as the downstream side.
　ラジエータ６２は、冷却水循環通路６１に設けられる。ラジエータ６２は、燃料電池スタック２から排出された冷却水を冷却する。 The radiator 62 is provided in the cooling water circulation passage 61. The radiator 62 cools the cooling water discharged from the fuel cell stack 2.
　バイパス通路６３は、ラジエータ６２をバイパスさせて冷却水を循環させるための通路である。バイパス通路６３の一端は冷却水循環通路６１に接続され、他端は三方弁６４に接続される。 The bypass passage 63 is a passage for bypassing the radiator 62 and circulating the cooling water. One end of the bypass passage 63 is connected to the cooling water circulation passage 61, and the other end is connected to the three-way valve 64.
　三方弁６４は、ラジエータ６２よりも下流側の冷却水循環通路６１に設けられる。三方弁６４は、冷却水の温度に応じて冷却水の循環経路を切り替える。冷却水温度が相対的に高い場合、燃料電池スタック２から排出された冷却水がラジエータ６２を介して再び燃料電池スタック２に供給されるように、冷却水の循環経路が切り替えられる。これに対して、冷却水温度が相対的に低い場合、燃料電池スタック２から排出された冷却水がバイパス通路６３を流れて再び燃料電池スタック２に供給されるように、冷却水の循環経路が切り替えられる。 The three-way valve 64 is provided in the cooling water circulation passage 61 on the downstream side of the radiator 62. The three-way valve 64 switches the cooling water circulation path according to the temperature of the cooling water. When the cooling water temperature is relatively high, the cooling water circulation path is switched so that the cooling water discharged from the fuel cell stack 2 is supplied again to the fuel cell stack 2 via the radiator 62. On the other hand, when the coolant temperature is relatively low, the coolant circulation path is such that the coolant discharged from the fuel cell stack 2 flows through the bypass passage 63 and is supplied to the fuel cell stack 2 again. Can be switched.
　循環ポンプ６５は、三方弁６４よりも下流側の冷却水循環通路６１に設けられる。循環ポンプ６５は、冷却水を循環させる。 The circulation pump 65 is provided in the cooling water circulation passage 61 on the downstream side of the three-way valve 64. The circulation pump 65 circulates the cooling water.
　ＰＴＣヒータ６６は、バイパス通路６３に設けられる。ＰＴＣヒータ６６は、燃料電池スタック２の暖機時などに通電されて、冷却水の温度を上昇させる。 The PTC heater 66 is provided in the bypass passage 63. The PTC heater 66 is energized when the fuel cell stack 2 is warmed up, and raises the temperature of the cooling water.
　第１パージ弁循環通路６７は、凍結による第１パージ弁４９の固着を防止するため、第１パージ弁４９内に形成されたウォータジャケットに冷却水を導入する通路である。第１パージ弁循環通路６７は、循環ポンプ６５の下流側の冷却水循環通路６１から分岐して第１パージ弁４９のウォータジャケットに冷却水を導入する第１導入通路６７１と、第１パージ弁４９のウォータジャケットから排出された冷却水を循環ポンプ６５の上流側の冷却水循環通路６１に戻す第１戻し通路６７２と、を備える。 The first purge valve circulation passage 67 is a passage for introducing cooling water into a water jacket formed in the first purge valve 49 in order to prevent the first purge valve 49 from sticking due to freezing. The first purge valve circulation passage 67 branches from the cooling water circulation passage 61 on the downstream side of the circulation pump 65 and introduces the cooling water into the water jacket of the first purge valve 49, and the first purge valve 49. A first return passage 672 for returning the cooling water discharged from the water jacket to the cooling water circulation passage 61 on the upstream side of the circulation pump 65.
　第２パージ弁循環通路６８は、凍結による第２パージ弁５０の固着を防止するために、第２パージ弁５０内に形成されたウォータジャケットに冷却水を導入する通路である。第２パージ弁循環通路６８は、循環ポンプ６５の下流側の冷却水循環通路６１から分岐して第２パージ弁５０のウォータジャケットに冷却水を導入する第２導入通路６８１と、第２パージ弁５０のウォータジャケットから排出された冷却水を循環ポンプ６５の上流側の冷却水循環通路６１に戻す第２戻し通路６８２と、を備える。 The second purge valve circulation passage 68 is a passage for introducing cooling water into a water jacket formed in the second purge valve 50 in order to prevent the second purge valve 50 from sticking due to freezing. The second purge valve circulation passage 68 branches from the cooling water circulation passage 61 on the downstream side of the circulation pump 65 and introduces the cooling water into the water jacket of the second purge valve 50, and the second purge valve 50. And a second return passage 682 for returning the cooling water discharged from the water jacket to the cooling water circulation passage 61 on the upstream side of the circulation pump 65.
　入口水温センサ６９は、燃料電池スタック２の冷却水入口孔２６近傍の冷却水循環通路６１に設けられる。入口水温センサ６９は、燃料電池スタック２に流入する冷却水の温度を検出する。 The inlet water temperature sensor 69 is provided in the cooling water circulation passage 61 near the cooling water inlet hole 26 of the fuel cell stack 2. The inlet water temperature sensor 69 detects the temperature of the cooling water flowing into the fuel cell stack 2.
　出口水温センサ７０は、燃料電池スタック２の冷却水出口孔２７近傍の冷却水循環通路６１に設けられる。出口水温センサ７０は、燃料電池スタック２から排出された冷却水の温度（スタック温度）を検出する。 The outlet water temperature sensor 70 is provided in the cooling water circulation passage 61 near the cooling water outlet hole 27 of the fuel cell stack 2. The outlet water temperature sensor 70 detects the temperature of the cooling water discharged from the fuel cell stack 2 (stack temperature).
　第１パージ弁温度センサ７１は、第１戻し通路６７２に設けられる。第１パージ弁温度センサ７１は、第１パージ弁４９のウォータジャケットから排出された冷却水の温度（第１パージ弁温度）を検出する。第２パージ弁温度センサ７２は、第２戻し通路６８２に設けられる。第２パージ弁温度センサ７２は、第２パージ弁５０のウォータジャケットから排出された冷却水の温度（第２パージ弁温度）を検出する。 The first purge valve temperature sensor 71 is provided in the first return passage 672. The first purge valve temperature sensor 71 detects the temperature of the cooling water discharged from the water jacket of the first purge valve 49 (first purge valve temperature). The second purge valve temperature sensor 72 is provided in the second return passage 682. The second purge valve temperature sensor 72 detects the temperature of the cooling water discharged from the water jacket of the second purge valve 50 (second purge valve temperature).
　コントローラ７は、中央演算装置（ＣＰＵ）、読み出し専用メモリ（ＲＯＭ）、ランダムアクセスメモリ（ＲＡＭ）、及び入出力インタフェース（Ｉ／Ｏインタフェース）を備えたマイクロコンピュータで構成される。 The controller 7 includes a microcomputer having a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).
　コントローラ７には、エアフローセンサ３４や圧力センサ４４、出口水温センサ７０、第１パージ弁温度センサ７１、第２パージ弁温度センサ７２の検出信号が入力される。また、コントローラ７には、燃料電池スタック２の出力電流を検出する電流センサ７３や、燃料電池スタック２の出力電圧を検出する電圧センサ７４、アクセルペダル踏み込み量（アクセル操作量）を検出するアクセルストロークセンサ７５、大気圧を検出する大気圧センサ７６等の燃料電池システム１の運転状態を検出する各種センサの信号が入力される。 The controller 7 receives detection signals from the air flow sensor 34, the pressure sensor 44, the outlet water temperature sensor 70, the first purge valve temperature sensor 71, and the second purge valve temperature sensor 72. The controller 7 also includes a current sensor 73 for detecting the output current of the fuel cell stack 2, a voltage sensor 74 for detecting the output voltage of the fuel cell stack 2, and an accelerator stroke for detecting the accelerator pedal depression amount (accelerator operation amount). Signals from various sensors that detect the operating state of the fuel cell system 1, such as the sensor 75 and the atmospheric pressure sensor 76 that detects atmospheric pressure, are input.
　コントローラ７は、システム運転状態に基づき、調圧弁４３を周期的に開閉することでアノードガスを脈動供給する脈動運転を実行するとともに、パージ弁４７，４８の開度を制御し、バッファタンク５１から排出されるアノードオフガスの流量を調節することで、バッファタンク５１内のアノードガス濃度を所定濃度に維持する。 The controller 7 performs pulsation operation for pulsating the anode gas by periodically opening and closing the pressure regulating valve 43 based on the system operation state, and controls the opening degree of the purge valves 47 and 48, from the buffer tank 51. The anode gas concentration in the buffer tank 51 is maintained at a predetermined concentration by adjusting the flow rate of the discharged anode off gas.
　上述のように脈動運転を行うことで、アノードガス流路１２１内の窒素等の不純ガスをバッファタンク５１に押し込むことができる。その結果、不純ガスがアノードガス流路１２１内に蓄積され、電極反応が阻害されることを抑制できる。これにより、燃料電池システム１において安定した発電が実現可能となる。 By performing the pulsation operation as described above, an impure gas such as nitrogen in the anode gas passage 121 can be pushed into the buffer tank 51. As a result, it is possible to suppress the impure gas from accumulating in the anode gas flow path 121 and inhibiting the electrode reaction. Thereby, stable power generation can be realized in the fuel cell system 1.
　図３は、燃料電池システム１の運転状態が一定の定常運転時における脈動運転について説明する図である。 FIG. 3 is a diagram for explaining pulsation operation during steady operation in which the operation state of the fuel cell system 1 is constant.
　コントローラ７は、燃料電池システム１の運転状態に基づいて燃料電池スタック２の目標出力を算出し、目標出力に応じたアノードガスの下限圧と脈動圧力幅とを算出する。これにより、燃料電池スタック２に供給されるアノードガスの上限圧力値及び下限圧力値が設定される。図３（Ａ）に示すように、燃料電池システム１では、設定された上限圧力値及び下限圧力値の間でアノードガス圧力を周期的に増減させる。 The controller 7 calculates the target output of the fuel cell stack 2 based on the operating state of the fuel cell system 1, and calculates the lower limit pressure and pulsation pressure width of the anode gas according to the target output. Thereby, the upper limit pressure value and the lower limit pressure value of the anode gas supplied to the fuel cell stack 2 are set. As shown in FIG. 3A, in the fuel cell system 1, the anode gas pressure is periodically increased or decreased between the set upper limit pressure value and lower limit pressure value.
　図３（Ａ）の時刻ｔ１１においてアノード圧が下限圧力値に達すると、アノード圧が、目標圧である上限圧力値となるように、アノード圧のフィードバック制御が実施される。これにより、図３（Ｂ）に示すように、調圧弁４３は、アノード圧を上限圧力値まで増圧させることができる開度に開弁制御される。この時、アノードガスは高圧タンク４１から燃料電池スタック２に供給され、バッファタンク５１へと排出される。 When the anode pressure reaches the lower limit pressure value at time t11 in FIG. 3A, feedback control of the anode pressure is performed so that the anode pressure becomes the upper limit pressure value that is the target pressure. As a result, as shown in FIG. 3B, the pressure regulating valve 43 is controlled to open to an opening that can increase the anode pressure to the upper limit pressure value. At this time, the anode gas is supplied from the high-pressure tank 41 to the fuel cell stack 2 and discharged to the buffer tank 51.
　時刻ｔ１２でアノード圧が上限圧力値に達すると、アノードガスの目標圧は下限圧力値に設定され、アノード圧のフィードバック制御が実施される。これにより、図３（Ｂ）に示すように調圧弁４３は全閉状態に制御され、高圧タンク４１から燃料電池スタック２へのアノードガスの供給が停止される。アノードガス供給の停止時には、燃料電池スタック２内のアノードガスが消費されるので、アノードガスの消費分だけアノード圧が低下する。 When the anode pressure reaches the upper limit pressure value at time t12, the target pressure of the anode gas is set to the lower limit pressure value, and feedback control of the anode pressure is performed. Thereby, as shown in FIG. 3B, the pressure regulating valve 43 is controlled to be fully closed, and the supply of the anode gas from the high-pressure tank 41 to the fuel cell stack 2 is stopped. When the supply of the anode gas is stopped, the anode gas in the fuel cell stack 2 is consumed, so the anode pressure is reduced by the amount of consumption of the anode gas.
　燃料電池スタック２内のアノードガスが消費されると、バッファタンク５１の圧力が一時的にアノードガス流路１２１の圧力よりも高くなるので、バッファタンク５１からアノードガス流路１２１へとアノードオフガスが逆流する。その結果、アノードガス流路１２１に残されていたアノードガスと、アノードガス流路１２１に逆流してきたアノードオフガス中のアノードガスが時間の経過とともに消費され、さらにアノード圧が低下する。 When the anode gas in the fuel cell stack 2 is consumed, the pressure in the buffer tank 51 temporarily becomes higher than the pressure in the anode gas channel 121, so that the anode off-gas flows from the buffer tank 51 to the anode gas channel 121. Backflow. As a result, the anode gas remaining in the anode gas flow path 121 and the anode gas in the anode off-gas flowing back to the anode gas flow path 121 are consumed over time, and the anode pressure further decreases.
　時刻ｔ１３でアノード圧が下限圧力値に達したら、時刻ｔ１１の時と同様に調圧弁４３が開かれる。そして、時刻ｔ１４で再びアノード圧が上限圧力値に達したら、調圧弁４３が全閉にされる。 When the anode pressure reaches the lower limit pressure value at time t13, the pressure regulating valve 43 is opened in the same manner as at time t11. When the anode pressure reaches the upper limit pressure value again at time t14, the pressure regulating valve 43 is fully closed.
　このような脈動運転を実施する燃料電池システム１では、バッファタンク５１内のアノードガス濃度（水素濃度）が低すぎると、アノード圧が低下してアノードオフガスが燃料電池スタック２に逆流する時に、アノードガス流路１２１の下流域で電極反応に使用されるアノードガスが不足する。電極反応に使用されるアノードガスが不足すると、発電効率が低下するだけでなく、燃料電池スタック１を構成する燃料電池１０の劣化を招く。 In the fuel cell system 1 that performs such pulsation operation, if the anode gas concentration (hydrogen concentration) in the buffer tank 51 is too low, the anode pressure decreases and the anode off gas flows back into the fuel cell stack 2. The anode gas used for the electrode reaction is insufficient in the downstream region of the gas flow path 121. When the anode gas used for the electrode reaction is insufficient, not only the power generation efficiency is lowered, but also the fuel cell 10 constituting the fuel cell stack 1 is deteriorated.
　ところで、燃料電池システム１の起動時には、システム停止中にアノード系内に侵入してきた大気中の空気によって、アノードガス流路１２１やバッファタンク５１に空気が充満した状態となっている。そのため、燃料電池システムの起動時には、脈動運転を実施する前の準備運転として、起動パージ運転を実施する必要がある。起動パージ運転では、第１及び第２パージ弁４９，５０を開いてバッファタンク５１内の空気を外部へ排出するとともに、燃料電池スタック２にアノードガスを供給してバッファタンク５１内のアノードガス濃度を所定濃度まで上昇させる。 Incidentally, when the fuel cell system 1 is started, the air in the anode gas flow path 121 and the buffer tank 51 are filled with air in the atmosphere that has entered the anode system while the system is stopped. Therefore, at the time of starting the fuel cell system, it is necessary to perform a start purge operation as a preparatory operation before performing the pulsation operation. In the start-up purge operation, the first and second purge valves 49 and 50 are opened to discharge the air in the buffer tank 51 to the outside, and the anode gas is supplied to the fuel cell stack 2 so that the anode gas concentration in the buffer tank 51 is increased. Is increased to a predetermined concentration.
　以下、燃料電池システム１における起動パージ運転について説明する。 Hereinafter, the startup purge operation in the fuel cell system 1 will be described.
　図４は、燃料電池システム１のメインルーチンについて説明するフローチャートである。コントローラ７は、燃料電池システム１が起動されると、本のルーチンを所定の演算周期（例えば１０ミリ秒）で繰り返し実行する。 FIG. 4 is a flowchart for explaining the main routine of the fuel cell system 1. When the fuel cell system 1 is activated, the controller 7 repeatedly executes this routine at a predetermined calculation cycle (for example, 10 milliseconds).
　ステップ１（Ｓ１）において、コントローラ７は、前述した各種センサの検出値を読み込む。 In step 1 (S1), the controller 7 reads the detection values of the various sensors described above.
　Ｓ２では、コントローラ７は、起動パージ運転終了フラグが１に設定されているか否かを判定する。起動パージ運転終了フラグは、起動パージ運転の終了後に１に設定されるフラグであって、システム起動時には０に設定される。コントローラ７は、起動パージ運転終了フラグが０である場合にはＳ３の処理を実行し、起動パージ運転終了フラグが１である場合にはＳ４の処理を実行する。 In S2, the controller 7 determines whether or not the start purge operation end flag is set to 1. The start purge operation end flag is a flag that is set to 1 after the start purge operation is completed, and is set to 0 when the system is started. The controller 7 executes the process of S3 when the startup purge operation end flag is 0, and executes the process of S4 when the startup purge operation end flag is 1.
　Ｓ３では、コントローラ７は、起動パージ運転処理を実施する。起動パージ運転処理の詳細については、図５を参照して後述する。 In S3, the controller 7 performs a startup purge operation process. Details of the startup purge operation processing will be described later with reference to FIG.
　Ｓ４では、コントローラ７は通常処理を実施する。通常処理中は、図３に示したように、設定された上限圧力値及び下限圧力値の間でアノード圧を周期的に増減させる脈動運転が実施される。コントローラ７は、運転状態に基づき決定されたカソードガスの圧力に応じてアノードガスの下限圧と脈動圧力幅とを算出することで、アノードガスの上限圧力値（脈動上限圧）及び下限圧力値（脈動下限圧）を設定する。このように、コントローラ７は、起動パージ運転処理後におけるアノードガスの脈動上限圧及び脈動下限圧を設定する機能を有している。 In S4, the controller 7 performs normal processing. During normal processing, as shown in FIG. 3, a pulsation operation is performed in which the anode pressure is periodically increased or decreased between the set upper limit pressure value and lower limit pressure value. The controller 7 calculates the lower limit pressure and the pulsation pressure width of the anode gas according to the cathode gas pressure determined based on the operating state, whereby the upper limit pressure value (pulsation upper limit pressure) and the lower limit pressure value ( Set the pulsation lower limit pressure. As described above, the controller 7 has a function of setting the pulsation upper limit pressure and the pulsation lower limit pressure of the anode gas after the startup purge operation process.
　図５は、起動パージ運転処理について説明するフローチャートである。 FIG. 5 is a flowchart for explaining the startup purge operation process.
　Ｓ３１では、コントローラ７は、起動パージ準備終了フラグが１に設定されているか否かを判定する。起動パージ準備終了フラグは、起動パージ運転の準備が終了した時に１に設定されるフラグであって、初期値は０に設定される。コントローラ７は、起動パージ準備終了フラグが０である場合にはＳ３２の処理を実行し、起動パージ準備終了フラグが１である場合にはＳ３３の処理を実行する。 In S31, the controller 7 determines whether or not the startup purge preparation end flag is set to 1. The start purge preparation end flag is a flag that is set to 1 when preparation for the start purge operation is completed, and the initial value is set to 0. The controller 7 executes the process of S32 when the startup purge preparation end flag is 0, and executes the process of S33 when the startup purge preparation end flag is 1.
　Ｓ３２では、コントローラ７は起動パージ準備処理を実施する。起動パージ準備処理の詳細については、図６を参照して後述する。 In S32, the controller 7 performs a startup purge preparation process. Details of the startup purge preparation process will be described later with reference to FIG.
　Ｓ３３では、コントローラ７は起動パージ処理を実施する。起動パージ処理の詳細については、図７を参照して後述する。 In S33, the controller 7 performs a startup purge process. Details of the startup purge process will be described later with reference to FIG.
　図６は、起動パージ準備処理について説明するフローチャートである。 FIG. 6 is a flowchart for explaining the startup purge preparation process.
　Ｓ３２１では、コントローラ７は、起動パージ運転中におけるカソード流量の目標値を、所定の起動目標カソード流量Ｑｓに設定する。起動パージ運転中は、バッファタンク５１内のアノードガス濃度を上げるために、バッファタンク５１にアノードガスが供給される。その際、バッファタンク５１に供給されるアノードガスの一部は、第１及び第２パージ通路４７，４８を通ってカソードガス排出通路３５に排出される。したがって、起動目標カソード流量Ｑｓは、予め実験等によって定められる値であって、パージガス中のアノードガス濃度が可燃濃度未満となるような値に設定される。 In S321, the controller 7 sets the target value of the cathode flow rate during the startup purge operation to a predetermined startup target cathode flow rate Qs. During the startup purge operation, the anode gas is supplied to the buffer tank 51 in order to increase the anode gas concentration in the buffer tank 51. At this time, part of the anode gas supplied to the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48. Therefore, the start target cathode flow rate Qs is a value determined in advance by experiments or the like, and is set to a value such that the anode gas concentration in the purge gas is less than the combustible concentration.
　Ｓ３２２では、コントローラ７は、カソード流量が起動目標カソード流量Ｑｓとなるように、カソードコンプレッサ３３をフィードバック制御する。 In S322, the controller 7 feedback-controls the cathode compressor 33 so that the cathode flow rate becomes the activation target cathode flow rate Qs.
　Ｓ３２３では、コントローラ７は、アノード圧の目標値を、所定の起動目標アノード上限圧Ｐａｕに設定する。起動目標アノード上限圧Ｐａｕは、予め実験等によって定められる値であって、アノードガス流路１２１内の空気をアノードガスとともにバッファタンク５１に押し込むことができる値に設定される。つまり、コントローラ７は、起動目標アノード上限圧を、図４のＳ４で設定されるアノードガスの上限圧力値よりも高い値に設定して起動運転を実行する起動運転実行部としての機能を有する。 In S323, the controller 7 sets the target value of the anode pressure to a predetermined activation target anode upper limit pressure Pau. The activation target anode upper limit pressure Pau is a value determined in advance by experiments or the like, and is set to a value that allows the air in the anode gas flow path 121 to be pushed into the buffer tank 51 together with the anode gas. That is, the controller 7 has a function as a startup operation execution unit that sets the startup target anode upper limit pressure to a value higher than the upper limit pressure value of the anode gas set in S4 of FIG. 4 and executes the startup operation.
　Ｓ３２４では、コントローラ７は、アノード圧が起動目標アノード上限圧Ｐａｕとなるように、調圧弁４３をフィードバック制御する。 In S324, the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure becomes the activation target anode upper limit pressure Pau.
　Ｓ３２５では、コントローラ７は、カソード流量が起動目標カソード流量Ｑｓ以上になっているか否かを判定する。コントローラ７は、カソード流量が起動目標カソード流量Ｑｓ未満であれば今回の処理を終了し、カソード流量が起動目標カソード流量Ｑｓ以上であればＳ３２６の処理を行う。 In S325, the controller 7 determines whether or not the cathode flow rate is equal to or higher than the activation target cathode flow rate Qs. The controller 7 ends the current process if the cathode flow rate is less than the activation target cathode flow rate Qs, and performs the process of S326 if the cathode flow rate is equal to or greater than the activation target cathode flow rate Qs.
　Ｓ３２６では、コントローラ７は、アノード圧が起動目標アノード上限圧Ｐａｕ未満であれば今回の処理を終了する。一方、コントローラ７は、アノード圧が起動目標アノード上限圧Ｐａｕ以上であれば、起動パージ運転の準備が完了したと判定し、Ｓ３２７の処理を行う。ステップＳ３２７では、コントローラ７は、起動パージ準備終了フラグを１に設定する。 In S326, if the anode pressure is less than the activation target anode upper limit pressure Pau, the controller 7 ends the current process. On the other hand, if the anode pressure is equal to or higher than the activation target anode upper limit pressure Pau, the controller 7 determines that the preparation for the activation purge operation is completed, and performs the process of S327. In step S327, the controller 7 sets the startup purge preparation end flag to 1.
　Ｓ３２８では、コントローラ７は、第１パージ弁４９及び第２パージ弁５０を開く。 In S328, the controller 7 opens the first purge valve 49 and the second purge valve 50.
　Ｓ３２９では、コントローラ７は減圧フラグを１に設定する。減圧フラグは、アノード圧を、起動目標アノード上限圧Ｐａｕまで上昇させた後、所定圧（起動目標アノード下限圧Ｐａｄ）まで減圧させるときに１に設定されるフラグであって、初期値は０に設定される。 In S329, the controller 7 sets the decompression flag to 1. The depressurization flag is a flag that is set to 1 when the anode pressure is increased to the starting target anode upper limit pressure Pau and then decreased to a predetermined pressure (starting target anode lower limit pressure Pad). The initial value is set to 0. Is set.
　図７は、起動パージ処理について説明するフローチャートである。 FIG. 7 is a flowchart for explaining the startup purge process.
　Ｓ３３１では、コントローラ７は、スタック温度、第１パージ弁温度、及び第２パージ弁温度を読み込み、それら温度のうち最も高いものを代表温度として選択する。 In S331, the controller 7 reads the stack temperature, the first purge valve temperature, and the second purge valve temperature, and selects the highest one of these temperatures as a representative temperature.
　Ｓ３３２では、コントローラ７は、図８のマップを参照し、代表温度と大気圧とに基づいて起動パージ終了時間ｔｔｐを算出する。起動パージ終了時間は、起動パージ運転によって、バッファタンク５１内のアノードガス濃度が脈動運転を開始可能な所定濃度まで上昇したと判定することができる時間である。つまり、起動パージ終了時間は、起動パージ運転によって、アノード系内に存在していた空気のうち所定量の空気を外部に排出したと判定することができる時間として設定される。 In S332, the controller 7 refers to the map of FIG. 8 and calculates the start purge end time tp based on the representative temperature and the atmospheric pressure. The start purge end time is a time during which it can be determined that the anode gas concentration in the buffer tank 51 has increased to a predetermined concentration at which the pulsation operation can be started by the start purge operation. In other words, the start purge end time is set as a time during which it is possible to determine that a predetermined amount of the air existing in the anode system has been discharged to the outside by the start purge operation.
　図８に示すように、起動パージ終了時間は、代表温度が高くなるほど、また大気圧が高くなるほど長く設定される。これは、第１パージ弁４９及び第２パージ弁５０を通過するガスの流量が、ガス温度と、各パージ弁４９，５０の上流側及び下流側の前後差圧とに応じて変化するためである。つまり、第１パージ弁４９及び第２パージ弁５０を通過するガス流量は、ガス温度が高くなるほど、また前後差圧が小さくなるほど、少なくなる。 As shown in FIG. 8, the start purge end time is set longer as the representative temperature becomes higher and the atmospheric pressure becomes higher. This is because the flow rate of the gas passing through the first purge valve 49 and the second purge valve 50 changes according to the gas temperature and the upstream and downstream differential pressures of the purge valves 49 and 50. is there. That is, the gas flow rate passing through the first purge valve 49 and the second purge valve 50 decreases as the gas temperature increases and the front-rear differential pressure decreases.
　本実施形態では、第１及び第２パージ弁４９，５０を通過するガスの温度を、スタック温度、第１パージ弁温度、及び第２パージ弁温度のうちの最も高い温度と仮定し、第１及び第２パージ弁４９，５０を通過するガスの流量が最も少ない場合を想定して、起動パージ終了時間を定めている。したがって、起動パージ運転終了後の脈動運転開始時に、バッファタンク５１内のアノードガス濃度を所望濃度まで確実に上昇させることができる。 In the present embodiment, the temperature of the gas passing through the first and second purge valves 49 and 50 is assumed to be the highest temperature among the stack temperature, the first purge valve temperature, and the second purge valve temperature, and the first The start purge end time is determined on the assumption that the gas flow rate passing through the second purge valves 49 and 50 is the smallest. Therefore, the anode gas concentration in the buffer tank 51 can be reliably increased to a desired concentration at the start of the pulsation operation after the start purge operation is completed.
　また、本実施形態では、起動パージ終了時間を算出するためのパラメータとして大気圧を用いている。第１パージ弁４９及び第２パージ弁５０の前後差圧は、アノード圧と大気圧との差圧なので、大気圧が分かれば、第１パージ弁４９及び第２パージ弁５０の前後差圧を推定することができる。つまり、大気圧が低下し、第１パージ弁４９及び第２パージ弁５０の前後差圧が大きくなったことで、必要なパージ時間が短くなったことを検出することができる。 In this embodiment, atmospheric pressure is used as a parameter for calculating the start purge end time. Since the differential pressure across the first purge valve 49 and the second purge valve 50 is the differential pressure between the anode pressure and the atmospheric pressure, if the atmospheric pressure is known, the differential pressure across the first purge valve 49 and the second purge valve 50 is reduced. Can be estimated. That is, it can be detected that the required purge time is shortened because the atmospheric pressure has decreased and the differential pressure across the first purge valve 49 and the second purge valve 50 has increased.
　図７に戻り、起動パージ処理の続きを説明する。Ｓ３３３では、コントローラ７は、パージタイマｔ１が、起動パージ終了時間ｔｔｐ以上になったか否かを判定する。パージタイマｔ１は、バッファタンク５１に溜められたガスが第１パージ通路４７及び第２パージ通路４８を通って外部に排出されている時間の積算値である。コントローラ７は、パージタイマｔ１が起動パージ終了時間ｔｔｐ未満であればＳ３３４の処理を実行し、パージタイマｔ１が起動パージ終了時間ｔｔｐ以上であればＳ３３９の処理を実行する。 Referring back to FIG. 7, the continuation of the startup purge process will be described. In S333, the controller 7 determines whether or not the purge timer t1 is equal to or longer than the startup purge end time ttp. The purge timer t1 is an integrated value of the time during which the gas stored in the buffer tank 51 is discharged to the outside through the first purge passage 47 and the second purge passage 48. The controller 7 executes the process of S334 if the purge timer t1 is less than the startup purge end time tp, and executes the process of S339 if the purge timer t1 is greater than or equal to the startup purge end time tp.
　Ｓ３３４では、コントローラ７は、減圧フラグが１に設定されているか否かを判定する。コントローラ７は、減圧フラグが１に設定されている場合にはＳ３３５の処理を実行し、減圧フラグが０に設定いる場合にはＳ３３６の処理を実行する。 In S334, the controller 7 determines whether or not the decompression flag is set to 1. The controller 7 executes the process of S335 when the decompression flag is set to 1, and executes the process of S336 when the decompression flag is set to 0.
　Ｓ３３５では、コントローラ７は減圧処理を実施する。減圧処理については、図９を参照して後述する。 In S335, the controller 7 performs a decompression process. The decompression process will be described later with reference to FIG.
　Ｓ３３６では、コントローラ７は、圧力保持フラグが１に設定されているか否かを判定する。圧力保持フラグは、減圧処理によってアノード圧を、所定圧（起動目標アノード下限圧Ｐａｄ）まで減圧させた後、その所定圧に保持させる時に１に設定されるフラグであって、初期値は０に設定される。コントローラ７は、圧力保持フラグが１に設定されている場合にはＳ３３７の処理を実行し、圧力保持フラグが０に設定されている場合にはＳ３３８の処理を実行する。 In S336, the controller 7 determines whether or not the pressure holding flag is set to 1. The pressure holding flag is a flag that is set to 1 when the anode pressure is reduced to a predetermined pressure (starting target anode lower limit pressure Pad) by the pressure reduction process, and is held at the predetermined pressure. The initial value is set to 0. Is set. The controller 7 executes the process of S337 when the pressure holding flag is set to 1, and executes the process of S338 when the pressure holding flag is set to 0.
　Ｓ３３７では、コントローラ７は圧力保持処理を実施する。圧力保持処理については、図１０を参照して後述する。 In S337, the controller 7 performs a pressure holding process. The pressure holding process will be described later with reference to FIG.
　Ｓ３３８では、コントローラ７は昇圧処理を実施する。昇圧処理については、図１１を参照して後述する。 In S338, the controller 7 performs a boosting process. The boosting process will be described later with reference to FIG.
　Ｓ３３９では、コントローラ７は起動パージ終了処理を実施する。起動パージ終了処理については、図１２を参照して後述する。 In S339, the controller 7 performs a start purge end process. The startup purge end process will be described later with reference to FIG.
　図９は、減圧処理について説明するフローチャートである。 FIG. 9 is a flowchart for explaining the decompression process.
　減圧処理は、バッファタンク５１内のアノードガスと空気の混合ガスを第１及び第２パージ通路４７，４８からカソードガス排出通路３５へ排出するため、バッファタンク５１に供給されるアノード圧を減少させ、混合ガスをバッファタンク５１から第１及び第２アノードガス排出通路４５，４６に逆流させる処理である。 In the depressurization process, the mixed gas of the anode gas and air in the buffer tank 51 is discharged from the first and second purge passages 47 and 48 to the cathode gas discharge passage 35, so that the anode pressure supplied to the buffer tank 51 is decreased. In this process, the mixed gas flows backward from the buffer tank 51 to the first and second anode gas discharge passages 45 and 46.
　Ｓ３３５１では、コントローラ７は、アノード圧の目標値を、所定の起動目標アノード下限圧Ｐａｄに設定する。起動目標アノード下限圧Ｐａｄは、予め実験等によって定められる値であって、バッファタンク５１内の混合ガスが第１アノードガス排出通路４５と第１パージ通路４７の接続部及び第２アノードガス排出通路４６と第２パージ通路４８の接続部よりも燃料電池スタック２側まで押し戻される値に設定される。なお、アノードガス流路１２１内でアノードガスが不足しないようであれば、起動目標アノード下限圧Ｐａｄはバッファタンク５１内の混合ガスが燃料電池スタック２まで逆流するような値に設定してもよい。 In S3351, the controller 7 sets the target value of the anode pressure to a predetermined activation target anode lower limit pressure Pad. The starting target anode lower limit pressure Pad is a value determined in advance by experiments or the like, and the mixed gas in the buffer tank 51 is connected to the first anode gas discharge passage 45 and the first purge passage 47 and the second anode gas discharge passage. 46 and the second purge passage 48 are set to values pushed back to the fuel cell stack 2 side. If the anode gas does not run out in the anode gas flow path 121, the activation target anode lower limit pressure Pad may be set to a value such that the mixed gas in the buffer tank 51 flows back to the fuel cell stack 2. .
　上記した起動目標アノード下限圧は、図４のＳ４で設定されるアノードガスの下限圧力値よりも高い値に設定される。つまり、コントローラ７は、起動目標アノード下限圧を、図４のＳ４で設定されるアノードガスの下限圧力値よりも高い値に設定して起動運転を実行する起動運転実行部としての機能を有する。 The above-described starting target anode lower limit pressure is set to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG. That is, the controller 7 has a function as a start-up operation execution unit that sets the start target anode lower limit pressure to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG. 4 and executes the start-up operation.
　Ｓ３３５２では、コントローラ７は、アノード圧が起動目標アノード下限圧Ｐａｄとなるように、調圧弁４３をフィードバック制御する。 In S3352, the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure becomes the activation target anode lower limit pressure Pad.
　Ｓ３３５３では、コントローラ７は、アノード圧が起動目標アノード下限圧以下になったか否かを判定する。コントローラ７は、アノード圧が起動目標アノード下限圧よりも高い場合にはＳ３３５４の処理を実行し、アノード圧が起動目標アノード下限圧以下である場合にＳ３３５５の処理を実行する。 In S3353, the controller 7 determines whether or not the anode pressure is equal to or lower than the activation target anode lower limit pressure. The controller 7 executes the process of S3354 when the anode pressure is higher than the startup target anode lower limit pressure, and executes the process of S3355 when the anode pressure is equal to or lower than the startup target anode lower limit pressure.
　Ｓ３３５４では、コントローラ７は減圧フラグを１のまま維持する。一方、コントローラ７は、Ｓ３３５５において減圧フラグを０に設定し、Ｓ３３５６において圧力保持フラグを１に設定する。 In S3354, the controller 7 maintains the decompression flag at 1. On the other hand, the controller 7 sets the pressure reduction flag to 0 in S3355, and sets the pressure holding flag to 1 in S3356.
　図１０は、圧力保持処理について説明するフローチャートである。 FIG. 10 is a flowchart for explaining the pressure holding process.
　圧力保持処理では、アノード圧が起動目標アノード下限圧Ｐａｄに保持される。つまり、バッファタンク５１内の混合ガスが、第１アノードガス排出通路４５と第１パージ通路４７の接続部及び第２アノードガス排出通路４６と第２パージ通路４８の接続部よりも燃料電池スタック２側まで押し戻された状態を維持するように調整される。これにより、バッファタンク５１内の混合ガスを、第１及び第２パージ通路４７，４８からカソードガス排出通路３５へ排出し続けることができる。さらに、その後のアノード昇圧時に上流側からアノードガスが供給されることで、バッファタンク５１内のアノードガス濃度を効率的に高めることが可能となる。 In the pressure holding process, the anode pressure is held at the starting target anode lower limit pressure Pad. That is, the mixed gas in the buffer tank 51 is more fuel cell stack 2 than the connection portion between the first anode gas discharge passage 45 and the first purge passage 47 and the connection portion between the second anode gas discharge passage 46 and the second purge passage 48. It is adjusted so that the state pushed back to the side is maintained. Thereby, the mixed gas in the buffer tank 51 can be continuously discharged from the first and second purge passages 47 and 48 to the cathode gas discharge passage 35. Furthermore, the anode gas concentration in the buffer tank 51 can be efficiently increased by supplying the anode gas from the upstream side during the subsequent anode pressure increase.
　Ｓ３３７１では、コントローラ７は、アノード圧の目標値を起動目標アノード下限圧Ｐａｄに設定する。つまり、アノード圧の目標値は、減圧処理時に設定された起動目標アノード下限圧Ｐａｄのまま保持される。 In S3371, the controller 7 sets the target value of the anode pressure to the starting target anode lower limit pressure Pad. That is, the target value of the anode pressure is maintained as the starting target anode lower limit pressure Pad set during the pressure reduction process.
　Ｓ３３７２では、コントローラ７は、アノード圧が起動目標アノード下限圧Ｐａｄに保持されるように、調圧弁４３をフィードバック制御する。 In S3372, the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure is maintained at the activation target anode lower limit pressure Pad.
　Ｓ３３７３では、コントローラ７は、パージタイマｔ１の前回値に演算周期Δｔを加算して、パージタイマｔ１を更新する。 In S3373, the controller 7 adds the calculation cycle Δt to the previous value of the purge timer t1, and updates the purge timer t1.
　Ｓ３３７４では、コントローラ７は、圧力保持タイマｔ２の前回値に演算周期Δｔを加算し、圧力保持タイマｔ２を更新する。 In S3374, the controller 7 adds the calculation cycle Δt to the previous value of the pressure holding timer t2, and updates the pressure holding timer t2.
　Ｓ３３７５では、コントローラ７は、圧力保持タイマｔ２が所定の圧力保持終了時間ｔｋｄ以上になったか否かを判定する。コントローラ７は、圧力保持タイマｔ２が圧力保持終了時間ｔｋｄ未満の場合にはＳ３３７６の処理を実行し、圧力保持タイマｔ２が圧力保持終了時間ｔｋｄ以上の場合にＳ３３７７の処理を実行する。 In S3375, the controller 7 determines whether or not the pressure holding timer t2 is equal to or longer than a predetermined pressure holding end time tkd. The controller 7 executes the process of S3376 when the pressure holding timer t2 is less than the pressure holding end time tkd, and executes the process of S3377 when the pressure holding timer t2 is equal to or longer than the pressure holding end time tkd.
　圧力保持タイマｔ２が圧力保持終了時間ｔｋｄ未満の場合、コントローラ７は、Ｓ３３７６において圧力保持フラグを１のまま維持する。 When the pressure holding timer t2 is less than the pressure holding end time tkd, the controller 7 maintains the pressure holding flag at 1 in S3376.
　これに対して、圧力保持タイマｔ２が圧力保持終了時間ｔｋｄ以上の場合、コントローラ７は、Ｓ３３７７において圧力保持フラグを０に設定し、Ｓ３３７８において圧力保持タイマｔ２の値を０に更新する。その後、Ｓ３３７９において、コントローラ７は昇圧フラグを１に設定する。昇圧フラグは、圧力保持処理後にアノード圧を再び起動目標アノード上限圧Ｐａｕまで上昇させるときに１に設定されるフラグであって、初期値は０に設定される。 On the other hand, when the pressure holding timer t2 is equal to or longer than the pressure holding end time tkd, the controller 7 sets the pressure holding flag to 0 in S3377, and updates the value of the pressure holding timer t2 to 0 in S3378. Thereafter, in S3379, the controller 7 sets the boost flag to 1. The pressure increase flag is a flag that is set to 1 when the anode pressure is again increased to the activation target anode upper limit pressure Pau after the pressure holding process, and the initial value is set to 0.
　図１１は、昇圧処理について説明するフローチャートである。 FIG. 11 is a flowchart for explaining the boosting process.
　昇圧処理は、圧力保持処理終了後にアノード圧を再び起動目標アノード上限圧Ｐａｕまで上昇させ、アノードガスをバッファタンク５１に供給し、バッファタンク５１内のアノードガス濃度を上昇させる処理である。 The pressure increasing process is a process of increasing the anode pressure to the starting target anode upper limit pressure Pau again after the pressure holding process is completed, supplying the anode gas to the buffer tank 51, and increasing the anode gas concentration in the buffer tank 51.
　Ｓ３３８１では、コントローラ７は、アノード圧の目標値を起動目標アノード上限圧Ｐａｕに設定する。そして、コントローラ７は、Ｓ３３８２においてアノード圧が起動目標アノード上限圧Ｐａｕまで上昇するように調圧弁４３をフィードバック制御する。 In S3381, the controller 7 sets the target value of the anode pressure to the starting target anode upper limit pressure Pau. Then, the controller 7 feedback-controls the pressure regulating valve 43 so that the anode pressure rises to the activation target anode upper limit pressure Pau in S3382.
　Ｓ３３８３では、コントローラ７は、アノード圧が起動目標アノード上限圧以上になったか否かを判定する。コントローラ７は、アノード圧が起動目標アノード上限圧未満の場合にはＳ３３８４の処理を実行し、アノード圧が起動目標アノード上限圧以上の場合にはＳ３３８５の処理を実行する。 In S3383, the controller 7 determines whether or not the anode pressure is equal to or higher than the activation target anode upper limit pressure. The controller 7 executes the process of S3384 when the anode pressure is less than the activation target anode upper limit pressure, and executes the process of S3385 when the anode pressure is greater than or equal to the activation target anode upper limit pressure.
　アノード圧が起動目標アノード上限圧未満である場合、コントローラ７は、Ｓ３３８４において昇圧フラグを１のまま維持する。これに対して、アノード圧が起動目標アノード上限圧以上である場合、コントローラ７は、Ｓ３３８５において昇圧フラグを０に設定し、Ｓ３３８６において減圧フラグを１に設定する。 If the anode pressure is less than the activation target anode upper limit pressure, the controller 7 maintains the pressure increase flag at 1 in S3384. On the other hand, when the anode pressure is equal to or higher than the activation target anode upper limit pressure, the controller 7 sets the pressure increase flag to 0 in S3385 and sets the pressure decrease flag to 1 in S3386.
　図１２は、起動パージ終了処理について説明するフローチャートである。起動パージ終了処理は、起動パージ運転を終了させる処理である。図４に示すように、起動パージ終了処理後には通常処理が実行される。 FIG. 12 is a flowchart for explaining the startup purge end process. The start purge end process is a process for ending the start purge operation. As shown in FIG. 4, the normal process is executed after the startup purge end process.
　図１２のＳ３３９１では、コントローラ７は、起動パージ終了時間が設定されていたパージタイマｔ１の値を０に更新する。その後、コントローラ７は、Ｓ３３９２において起動パージ運転終了フラグを１に設定し、Ｓ３３９３において起動パージ準備終了フラグを０に設定する。 In S3391 of FIG. 12, the controller 7 updates the value of the purge timer t1 for which the startup purge end time has been set to 0. Thereafter, the controller 7 sets the start purge operation end flag to 1 in S3392, and sets the start purge preparation end flag to 0 in S3393.
　Ｓ３３９３の処理後、コントローラ７は、Ｓ３３９４において圧力保持タイマｔ２の値を０に更新し、Ｓ３３９５において減圧フラグを０に設定する。 After the processing of S3393, the controller 7 updates the value of the pressure holding timer t2 to 0 in S3394, and sets the decompression flag to 0 in S3395.
　Ｓ３３９６では、コントローラ７は圧力保持フラグを０に設定する。その後、コントローラ７は、Ｓ３３９７において昇圧フラグを０に設定し、起動パージ終了処理を終了する。 In S3396, the controller 7 sets the pressure holding flag to 0. Thereafter, the controller 7 sets the boosting flag to 0 in S3397, and ends the startup purge end process.
　次に、図１３を参照して、起動パージ運転時におけるアノード下限圧Ｐａｄの設定方法について説明する。アノード下限圧の設定は、コントローラ７によって実行される。 Next, a method for setting the anode lower limit pressure Pad during the startup purge operation will be described with reference to FIG. The setting of the anode lower limit pressure is executed by the controller 7.
　アノード下限圧Ｐａｄは、アノード圧下限値マップＢ１０１と、補正テーブルＢ１０２と、乗算器Ｂ１０３と、加算器Ｂ１０４と、起動パージ前半下限圧設定器Ｂ１０５と、起動パージ後半下限圧設定器Ｂ１０６と、選択器Ｂ１０７と、によって設定される。 The anode lower limit pressure Pad is selected from an anode pressure lower limit value map B101, a correction table B102, a multiplier B103, an adder B104, a start purge first half lower limit pressure setter B105, and a start purge second half lower limit pressure setter B106. Set by the device B107.
　コントローラ７は、アノード圧下限値マップＢ１０１を参照し、スタック入口冷却水温度及びスタック出口冷却水温度に基づいて、アノード圧力下限値を設定する。アノード圧力下限値は、スタック出口冷却水温度が一定であれば、スタック入口冷却水温度が高いほど大きな値に設定される。さらに、アノード圧力下限値は、スタック入口冷却水温度が一定であれば、スタック出口冷却水温度が高いほど大きな値に設定される。 Controller 7 refers to anode pressure lower limit value map B101, and sets the anode pressure lower limit value based on the stack inlet cooling water temperature and the stack outlet cooling water temperature. If the stack outlet cooling water temperature is constant, the anode pressure lower limit value is set to a larger value as the stack inlet cooling water temperature is higher. Furthermore, if the stack inlet cooling water temperature is constant, the anode pressure lower limit value is set to a larger value as the stack outlet cooling water temperature is higher.
　コントローラ７は、補正テーブルＢ１０２を参照し、燃料電池スタック２のＨＦＲ(High Frequency Resistance)に基づいて補正値を算出する。ＨＦＲは、例えば公知の交流インピーダンス法によって求められる。燃料電池スタック２の内部抵抗は、燃電解質膜１１１の湿潤状態によって変化する。そのため、燃料電池スタック２のＨＦＲを検知することで、電解質膜１１１の湿潤状態を間接的に検知することができる。電解質膜１１１が乾燥するほど、ＨＦＲの値は大きくなる。ＨＦＲは、燃料電池スタック２に交流電流を重畳した場合に検出される交流電圧値及び交流電流値に基づいて算出される。なお、ＨＦＲの算出方法は、上記方法に限られず、例えば本出願人が出願した特開２０１２－０５４１５３号公報に記載された方法を用いてもよい。 Controller 7 refers to correction table B102, and calculates a correction value based on HFR (High Frequency Resistance) of fuel cell stack 2. HFR is calculated | required by the well-known alternating current impedance method, for example. The internal resistance of the fuel cell stack 2 varies depending on the wet state of the fuel electrolyte membrane 111. Therefore, the wet state of the electrolyte membrane 111 can be indirectly detected by detecting the HFR of the fuel cell stack 2. As the electrolyte membrane 111 dries, the value of HFR increases. The HFR is calculated based on the AC voltage value and the AC current value detected when an AC current is superimposed on the fuel cell stack 2. The method for calculating HFR is not limited to the above method, and for example, a method described in Japanese Patent Application Laid-Open No. 2012-054153 filed by the present applicant may be used.
　乗算器Ｂ１０３は、アノード圧下限値マップＢ１０１に基づき設定されたアノード圧力下限値に、補正テーブルＢ１０２で演算された補正値を乗算する。そして、加算器Ｂ１０４は、乗算器Ｂ１０３で補正されたアノード圧力下限値に、大気圧を加算する。 The multiplier B103 multiplies the anode pressure lower limit value set based on the anode pressure lower limit value map B101 by the correction value calculated by the correction table B102. Then, the adder B104 adds the atmospheric pressure to the anode pressure lower limit value corrected by the multiplier B103.
　起動パージ前半下限圧設定器Ｂ１０５は、大気圧に基づいて、起動パージ前半のアノード下限圧を設定する。起動パージ前半のアノード下限圧は、図４のＳ４で設定されるアノードガスの下限圧力値よりも高い値に設定される。 The start purge first half lower limit pressure setter B105 sets the anode lower limit pressure for the first half of the start purge based on the atmospheric pressure. The anode lower limit pressure in the first half of the startup purge is set to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG.
　起動パージ後半下限圧設定器Ｂ１０６は、大気圧に基づいて、起動パージ後半のアノード下限圧を設定する。起動パージ後半のアノード下限圧は、図４のＳ４で設定されるアノードガスの下限圧力値よりも高い値に設定される。なお、起動パージ前半に比べて起動パージ後半の方が不純物のパージが進行しているため、大気圧が同一である場合における起動パージ後半のアノード下限圧は起動パージ前半のアノード下限圧よりも低く設定される。 The starting purge latter half lower limit pressure setter B106 sets the anode lower limit pressure in the latter half of the starting purge based on the atmospheric pressure. The anode lower limit pressure in the latter half of the startup purge is set to a value higher than the lower limit pressure value of the anode gas set in S4 of FIG. Since the purging of impurities progresses in the latter half of the startup purge compared to the first half of the startup purge, the anode lower limit pressure in the latter half of the startup purge when the atmospheric pressure is the same is lower than the anode lower limit pressure in the first half of the startup purge. Is set.
　選択器Ｂ１０７は、起動パージ前半であれば、起動パージ前半下限圧設定器Ｂ１０５で算出されたアノード下限圧を、アノード下限圧Ｐａｄとして選択する。また、選択器Ｂ１０７は、起動パージ後半であれば、起動パージ後半下限圧設定器Ｂ１０６で算出されたアノード下限圧を、アノード下限圧Ｐａｄとして選択する。さらに、選択器Ｂ１０７は、起動パージ前半でも起動パージ後半でなければ、加算器Ｂ１０４の出力信号を、アノード下限圧Ｐａｄとして選択する。 If the selector B107 is the first half of the start purge, the selector B107 selects the anode lower limit pressure calculated by the start purge first half lower limit pressure setter B105 as the anode lower limit pressure Pad. Further, if the selector B107 is the latter half of the startup purge, the selector B107 selects the anode lower limit pressure calculated by the startup purge latter half lower limit pressure setter B106 as the anode lower limit pressure Pad. Further, the selector B107 selects the output signal of the adder B104 as the anode lower limit pressure Pad if it is neither the first half of the startup purge nor the second half of the startup purge.
　なお、コントローラ７は、例えば高圧タンク４１の遮断弁を開いた時からの経過時間に基づいて、起動パージ前半であるか、起動パージ後半であるか、それら以外であるかを判定する。つまり、コントローラ７は、起動パージ運転開始時からの経過時間（第２所定期間）に応じて、アノード下限圧Ｐａｄの切り替えタイミングを判断している。この切り替えタイミングについては、大気圧やスタック温度等に応じて補正してもよい。 The controller 7 determines whether it is the first half of the start purge, the second half of the start purge, or other than that based on, for example, the elapsed time from when the shutoff valve of the high pressure tank 41 is opened. That is, the controller 7 determines the switching timing of the anode lower limit pressure Pad according to the elapsed time (second predetermined period) from the start of the startup purge operation. This switching timing may be corrected according to atmospheric pressure, stack temperature, or the like.
　図１４を参照して、差圧過大を防止するために要求されるアノード最大圧力制限値の設定方法について説明する。アノード最大圧力制限値の設定は、コントローラ７によって実行される。 Referring to FIG. 14, a method for setting the anode maximum pressure limit value required to prevent excessive differential pressure will be described. The setting of the anode maximum pressure limit value is executed by the controller 7.
　燃料電池１０の電解質膜１１１は薄い部材であるので、電解質膜１１１のカソード側圧力とアノード側圧力との差圧が大きすぎると、電解質膜１１１に悪影響を及ぼす。これを回避するため、コントローラ７は、カソードガス流路側圧力とアノードガス流路側圧力との差圧を診断し、差圧が過大にならないようにアノードガス圧力及びカソードガス圧力を制御している。 Since the electrolyte membrane 111 of the fuel cell 10 is a thin member, if the differential pressure between the cathode side pressure and the anode side pressure of the electrolyte membrane 111 is too large, the electrolyte membrane 111 is adversely affected. In order to avoid this, the controller 7 diagnoses the differential pressure between the cathode gas flow path side pressure and the anode gas flow path side pressure, and controls the anode gas pressure and the cathode gas pressure so that the differential pressure does not become excessive.
　燃料電池システム１では、カソード側の圧力は、カソードコンプレッサ３３の能力や、燃料電池１０に要求される発電出力等に基づいて設定される。そのため、コントローラ７は、アノード側の圧力がカソード側の圧力をベースとした許容値(アノード最大圧力制限値)を上回っているか否かに基づいて、差圧診断を実行する。なお、コントローラ７は、アノードガス流路側圧力とカソードガス流路側圧力との差圧が許容差圧（判定閾値）よりも小さいか否かに基づいて差圧診断するように構成されてもよい。 In the fuel cell system 1, the pressure on the cathode side is set based on the capacity of the cathode compressor 33, the power generation output required for the fuel cell 10, and the like. Therefore, the controller 7 executes the differential pressure diagnosis based on whether or not the anode side pressure exceeds the allowable value (anode maximum pressure limit value) based on the cathode side pressure. The controller 7 may be configured to make a differential pressure diagnosis based on whether or not the differential pressure between the anode gas flow path side pressure and the cathode gas flow path side pressure is smaller than the allowable differential pressure (determination threshold).
　アノード最大圧力制限値は、圧損減算器Ｂ２０１と、セレクトハイ器Ｂ２０２と、誤差減算器Ｂ２０３と、許容差圧選択器Ｂ２０４と、加算器Ｂ２０５とによって設定される。 The anode maximum pressure limit value is set by the pressure loss subtractor B201, the select high device B202, the error subtractor B203, the allowable differential pressure selector B204, and the adder B205.
　圧損減算器Ｂ２０１は、カソードガスを加湿するＷＲＤ３６よりも上流のカソードガスの圧力から、ＷＲＤ側圧力損失(ＳＷＥＥＰ側圧力損失)の最大値（一定値）を減算する。 Pressure loss subtractor B201 subtracts the maximum value (constant value) of the WRD side pressure loss (SWEEP side pressure loss) from the pressure of the cathode gas upstream of the WRD 36 that humidifies the cathode gas.
　セレクトハイ器Ｂ２０２は、圧損減算器Ｂ２０１により算出されたカソードガス圧力と、大気圧センサ７６により検出された大気圧のうち、高い方を基本カソードガス圧力として出力する。 The select high device B202 outputs the higher one of the cathode gas pressure calculated by the pressure loss subtractor B201 and the atmospheric pressure detected by the atmospheric pressure sensor 76 as the basic cathode gas pressure.
　誤差減算器Ｂ２０３は、セレクトハイ器Ｂ２０２から出力された基本カソードガス圧力から制御誤差(定数)を減算する。このように、誤差減算器Ｂ２０３は、補正後カソードガス圧力を算出する。 The error subtractor B203 subtracts the control error (constant) from the basic cathode gas pressure output from the select high device B202. As described above, the error subtractor B203 calculates the corrected cathode gas pressure.
　許容差圧選択器Ｂ２０４は、起動時には起動時許容差圧(定数)を選択し、起動時から所定期間経過後には起動時許容差圧より小さい起動時以外許容差圧(定数)を選択する。コントローラ７は、起動パージ運転開始時からの経過時間（第１所定期間）に応じて、許容差圧切り替えタイミングを判断している。この切り替えタイミングについては、大気圧やスタック温度等に応じて補正してもよい。なお、Ｂ２０４における切り替えは、選択器Ｂ１０７におけるアノード下限圧Ｐａｄの切り替え後に実行される。 The permissible differential pressure selector B204 selects a permissible differential pressure at start-up (constant) at the time of start-up, and selects a permissible differential pressure (constant) other than at start-up that is smaller than the permissible differential pressure at start-up after a lapse of a predetermined period from the start-up. The controller 7 determines the allowable differential pressure switching timing according to the elapsed time (first predetermined period) from the start of the startup purge operation. This switching timing may be corrected according to atmospheric pressure, stack temperature, or the like. Note that the switching in B204 is performed after the switching of the anode lower limit pressure Pad in the selector B107.
　加算器Ｂ２０５は、誤差減算器Ｂ２０３で算出された補正後カソードガス圧力に対して、選択された許容差圧を加算する。加算器Ｂ２０５で算出された値が、差圧過大を防止するために要求されるアノード最大圧力制限値となる。 The adder B205 adds the selected allowable differential pressure to the corrected cathode gas pressure calculated by the error subtractor B203. The value calculated by the adder B205 is the anode maximum pressure limit value required for preventing the differential pressure from being excessive.
　図１５を参照して、本実施形態による燃料電池システム１の制御動作について説明する。以下の説明では、図４から図１２のフローチャートとの対応を明確にするため、フローチャートのステップ番号を併記して説明する。 The control operation of the fuel cell system 1 according to the present embodiment will be described with reference to FIG. In the following description, in order to clarify the correspondence with the flowcharts of FIGS. 4 to 12, step numbers of the flowcharts will be described together.
　時刻ｔ１１で、燃料電池システム１が起動されると、起動パージ運転終了フラグ及び起動パージ準備終了フラグがそれぞれ０に設定されているので、起動パージ準備処理が実施される（Ｓ３２）。 When the fuel cell system 1 is started at time t11, the start purge operation end flag and the start purge preparation end flag are set to 0, so the start purge preparation process is performed (S32).
　起動パージ準備処理が実施されると、カソード流量が所定の変化率で起動目標カソード流量Ｑｓまで上昇するようにカソードコンプレッサ３３がフィードバック制御され（Ｓ３２２）、アノード圧が所定の変化率で起動目標アノード上限圧Ｐａｕ１まで上昇するように調圧弁４３がフィードバック制御される（Ｓ３２４）。 When the startup purge preparation process is performed, the cathode compressor 33 is feedback-controlled so that the cathode flow rate increases to the startup target cathode flow rate Qs at a predetermined change rate (S322), and the anode target is started at the predetermined change rate. The pressure regulating valve 43 is feedback-controlled so as to increase to the upper limit pressure Pau1 (S324).
　時刻ｔ１２で、カソード流量が起動目標カソード流量まで上昇し、かつアノード圧が起動目標アノード上限圧Ｐａｕ１まで上昇すると（Ｓ３２５及びＳ３２６でＹｅｓ）、起動パージ準備終了フラグが１に設定され（Ｓ３２７）、第１パージ弁４９及び第２パージ弁５０が開かれる（Ｓ３２８）。この時、減圧フラグは１に設定される（Ｓ３２９）。 When the cathode flow rate increases to the startup target cathode flow rate and the anode pressure increases to the startup target anode upper limit pressure Pau1 at time t12 (Yes in S325 and S326), the startup purge preparation end flag is set to 1 (S327). The first purge valve 49 and the second purge valve 50 are opened (S328). At this time, the decompression flag is set to 1 (S329).
　起動パージ準備終了フラグが１に設定されると、起動パージ処理が実施される（Ｓ３３）。起動パージ処理開始時にはパージタイマｔ１の値は０であり、かつ減圧フラグは１であるので、減圧処理が実施される（Ｓ３３５）。 When the start purge preparation end flag is set to 1, start purge processing is performed (S33). Since the value of the purge timer t1 is 0 and the decompression flag is 1 at the start of the startup purge process, the decompression process is performed (S335).
　減圧処理が実施されると、アノード圧が起動目標アノード下限圧Ｐａｄ１まで低下するように調圧弁４３がフィードバック制御される（Ｓ３３５２）。時刻ｔ１３で、アノード圧が起動目標アノード下限圧Ｐａｄ１まで低下すると（Ｓ３３５３でＹｅｓ）、減圧フラグが０に設定され（Ｓ３３５５）、圧力保持フラグが１に設定される（Ｓ３３５６）。 When the decompression process is performed, the pressure regulating valve 43 is feedback-controlled so that the anode pressure decreases to the activation target anode lower limit pressure Pad1 (S3352). When the anode pressure decreases to the activation target anode lower limit pressure Pad1 at time t13 (Yes in S3353), the pressure reduction flag is set to 0 (S3355), and the pressure holding flag is set to 1 (S3356).
　圧力保持フラグが１に設定されると、圧力保持処理が実施される（Ｓ３３７）。圧力保持処理では、アノード圧が起動目標アノード下限圧Ｐａｄ１に保持される。アノード圧を起動目標アノード下限圧Ｐａｄ１に保持している時間は、圧力保持タイマｔ２によってカウントされる（Ｓ３３７４）。 When the pressure holding flag is set to 1, a pressure holding process is performed (S337). In the pressure holding process, the anode pressure is held at the activation target anode lower limit pressure Pad1. The time during which the anode pressure is held at the activation target anode lower limit pressure Pad1 is counted by the pressure holding timer t2 (S3374).
　アノード圧が起動目標アノード下限圧Ｐａｄ１に保持されている場合には、バッファタンク５１内の混合ガスは、第１及び第２パージ通路４７，４８を通じてカソードガス排出通路３５へ排出される。混合ガスが実際に第１及び第２パージ通路４７，４８を通って外部に排出される時間はパージタイマｔ１によってカウントされる（Ｓ３３７３）。 When the anode pressure is maintained at the starting target anode lower limit pressure Pad1, the mixed gas in the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48. The time during which the mixed gas is actually discharged to the outside through the first and second purge passages 47 and 48 is counted by the purge timer t1 (S3373).
　時刻ｔ１４で、アノード圧を起動目標アノード下限圧Ｐａｄ１に保持してからの経過時間が圧力保持終了時間ｔｋｄに達すると（Ｓ３３７５でＹｅｓ）、圧力保持フラグが０に設定され（Ｓ３３７７）、圧力保持タイマｔ２が０にリセットされる（Ｓ３３７８）。この時、昇圧フラグが１に設定される（Ｓ３３７９）。 When the elapsed time after holding the anode pressure at the starting target anode lower limit pressure Pad1 reaches the pressure holding end time tkd at time t14 (Yes in S3375), the pressure holding flag is set to 0 (S3377) and the pressure is held. The timer t2 is reset to 0 (S3378). At this time, the boost flag is set to 1 (S3379).
　昇圧フラグが１に設定され、かつ圧力保持処理中にカウントされたパージタイマｔ１が起動パージ終了時間ｔｔｐ未満のときは、昇圧処理が実施される（Ｓ３３８）。 When the pressure increase flag is set to 1 and the purge timer t1 counted during the pressure holding process is less than the start purge end time ttp, the pressure increase process is performed (S338).
　昇圧処理が実施されると、アノード圧が再び起動目標アノード上限圧Ｐａｕ１まで上昇するように、調圧弁４３がフィードバック制御される（Ｓ３３８２）。 When the pressure increasing process is performed, the pressure regulating valve 43 is feedback-controlled so that the anode pressure rises again to the activation target anode upper limit pressure Pau1 (S3382).
　時刻ｔ１５で、アノード圧が起動目標アノード上限圧Ｐａｕ１まで上昇すると、昇圧フラグが０に戻され（Ｓ３３８５）、減圧フラグが再び１に設定される（Ｓ３３８６）。 When the anode pressure rises to the starting target anode upper limit pressure Pau1 at time t15, the pressure increase flag is returned to 0 (S3385), and the pressure decrease flag is set to 1 again (S3386).
　その後、起動パージが前半から後半に以降する時刻ｔ１６で、図１３の選択器Ｂ１０７によってアノード下限圧が起動パージ後半用の圧力Ｐａｄ２に切り替えられ、減圧処理が実施される。これにより、アノード圧が起動目標アノード下限圧Ｐａｄ２まで低下するように、調圧弁４３がフィードバック制御される。 Then, at time t16 when the start purge is performed from the first half to the second half, the anode lower limit pressure is switched to the pressure Pad2 for the second half of the start purge by the selector B107 in FIG. Thereby, the pressure regulating valve 43 is feedback-controlled so that the anode pressure decreases to the activation target anode lower limit pressure Pad2.
　そして、高圧タンク４１の遮断弁を開いてからの経過時間、つまりシステム起動開始時からの経過時間が閾値時間（第１所定期間）を超えた場合、又はアノード圧が閾値圧を下回った場合に、図１４の許容差圧選択器Ｂ２０４によって、許容差圧が起動時許容差圧から起動時許容差圧よりも小さな許容差圧に切り替えられる。このように、時刻ｔ１７において、アノード最大圧力制限値が変更される。許容差圧は、請求の範囲の差圧診断部の判定閾値に相当する。 And when the elapsed time from opening the shutoff valve of the high-pressure tank 41, that is, the elapsed time from the start of system startup, exceeds the threshold time (first predetermined period), or when the anode pressure falls below the threshold pressure The allowable differential pressure selector B204 in FIG. 14 switches the allowable differential pressure from the allowable differential pressure at the time of startup to an allowable differential pressure smaller than the allowable differential pressure at the time of startup. Thus, at time t17, the anode maximum pressure limit value is changed. The allowable differential pressure corresponds to the determination threshold value of the differential pressure diagnosis unit in the claims.
　時刻ｔ１８でアノード圧が下限圧Ｐａｄ２まで達した後は、アノード圧は上限圧Ｐａｕ２と下限圧Ｐａｄ２との間で制御され、時刻ｔ１３～ｔ１６と同様に昇圧処理、減圧処理を圧力保持処理が順番に実行される。なお、アノード圧は、カソード圧との差圧が過大とならないように、アノード最大圧力制限値よりも小さくなるように制限されている。 After the anode pressure reaches the lower limit pressure Pad2 at time t18, the anode pressure is controlled between the upper limit pressure Pau2 and the lower limit pressure Pad2, and the pressure holding process and the pressure reducing process are sequentially performed in the same manner as at times t13 to t16. To be executed. The anode pressure is limited to be smaller than the anode maximum pressure limit value so that the differential pressure from the cathode pressure does not become excessive.
　燃料電池システム１では、上述のように起動パージ前半及び後半において減圧処理、圧力保持処理、及び昇圧処理が繰り返されることで、バッファタンク５１内のアノードガス濃度（水素濃度）が所望の濃度まで上昇させることができる。 In the fuel cell system 1, the anode gas concentration (hydrogen concentration) in the buffer tank 51 is increased to a desired concentration by repeating the depressurization process, the pressure holding process, and the pressure increase process in the first half and the second half of the startup purge as described above. Can be made.
　本実施形態によれば、燃料電池システム１の起動時に、アノード圧を起動目標アノード上限圧まで上昇させることで、システム停止中にアノード系内に侵入してきた空気をアノードガスとともにバッファタンク５１内に押し込む。その後、アノード圧を目標アノード下限圧まで低下させることで、バッファタンク５１内の混合ガスを第１アノードガス排出通路４５及び第２アノードガス排出通路４６に逆流させる。また、燃料電池システム１の起動時には、第１パージ弁４９及び第２パージ弁５０が開弁制御される。 According to the present embodiment, when the fuel cell system 1 is started, the anode pressure is increased to the start target anode upper limit pressure, so that air that has entered the anode system while the system is stopped is put into the buffer tank 51 together with the anode gas. Push in. Thereafter, the mixed gas in the buffer tank 51 is caused to flow back into the first anode gas discharge passage 45 and the second anode gas discharge passage 46 by lowering the anode pressure to the target anode lower limit pressure. Further, when the fuel cell system 1 is started, the first purge valve 49 and the second purge valve 50 are controlled to open.
　これにより、燃料電池システム１の起動時に、バッファタンク５１内の混合ガスを第１及び第２パージ通路４７，４８を通じてカソードガス排出通路３５に排出でき、バッファタンク５１内のアノードガス濃度を徐々に上昇させることができる。したがって、起動パージ運転後の脈動運転実施時に、バッファタンク５１内のアノードオフガスがアノードガス流路１２１に逆流した場合でも、アノードガス流路１２１の下流域で電極反応に使用されるアノードガスが不足することを抑制できる。したがって、燃料電池スタック２での発電効率の低下を抑制でき、さらに燃料電池スタック２の劣化も抑制できる。 Thereby, when the fuel cell system 1 is started, the mixed gas in the buffer tank 51 can be discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48, and the anode gas concentration in the buffer tank 51 is gradually increased. Can be raised. Therefore, even when the anode off-gas in the buffer tank 51 flows backward to the anode gas passage 121 during the pulsation operation after the start purge operation, the anode gas used for the electrode reaction is insufficient in the downstream region of the anode gas passage 121. Can be suppressed. Accordingly, a decrease in power generation efficiency in the fuel cell stack 2 can be suppressed, and further deterioration of the fuel cell stack 2 can be suppressed.
　本実施形態では、バッファタンク５１内の混合ガスが実際に第１及び第２パージ通路４７，４８を通じてカソードガス排出通路３５に排出されている時、つまり圧力保持処理中のみパージタイマｔ１をカウントする。これは、減圧処理中や昇圧処理中は、バッファタンク５１内の混合ガスではなく、高圧タンク４１から供給されたアノードガスが第１及び第２パージ通路４７，４８を通じてカソードガス排出通路３５に排出されている可能性があるためである。圧力保持処理中のみパージタイマｔ１をカウントすることで、バッファタンク５１内のアノードガス濃度が所望濃度まで上昇したことを精度良く判定することができる。 In this embodiment, the purge timer t1 is counted only when the mixed gas in the buffer tank 51 is actually discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48, that is, during the pressure holding process. This is because the anode gas supplied from the high-pressure tank 41 is discharged to the cathode gas discharge passage 35 through the first and second purge passages 47 and 48, not the mixed gas in the buffer tank 51 during the pressure reduction processing or the pressure increase processing. This is because there is a possibility of being. By counting the purge timer t1 only during the pressure holding process, it can be accurately determined that the anode gas concentration in the buffer tank 51 has increased to the desired concentration.
　本実施形態では、起動パージ運転開始時から所定期間が過ぎたら起動開始時の圧力を下げるようにした。つまり、コントローラ７は、起動パージ運転開始時には、図４のＳ４（通常処理）で設定されるアノードガスの脈動上限圧よりも高くなるようにアノードガスの脈動上限圧を上げ、起動パージ運転開始から所定期間が過ぎたら起動開始時の脈動上限圧を下げる。このようにしたので、電解質膜１１１等のような燃料電池１０を構成する部品の耐久性の低下を抑制することができる。 In this embodiment, the pressure at the start of startup is reduced when a predetermined period has elapsed from the start of the startup purge operation. That is, at the start of the startup purge operation, the controller 7 increases the pulsation upper limit pressure of the anode gas so as to be higher than the pulsation upper limit pressure of the anode gas set in S4 (normal processing) in FIG. When the predetermined period has passed, the pulsation upper limit pressure at the start of activation is lowered. Since it did in this way, the fall of durability of the components which comprise the fuel cell 10 like the electrolyte membrane 111 grade | etc., Can be suppressed.
　また、本実施形態では、コントローラ７は、起動パージ運転開始時には、図４のＳ４（通常処理）で設定されるアノードガスの脈動下限圧よりも高くなるようにアノードガスの脈動下限圧を上げ、起動パージ運転開始から第２所定期間が過ぎたら、起動開始時の脈動下限圧を下げる。このようにしたので、電解質膜１１１等のような燃料電池１０を構成する部品の耐久性の低下を抑制することができる。 In the present embodiment, the controller 7 increases the anode gas pulsation lower limit pressure to be higher than the anode gas pulsation lower limit pressure set in S4 (normal processing) in FIG. When the second predetermined period has elapsed from the start of the start purge operation, the pulsation lower limit pressure at the start of start is reduced. Since it did in this way, the fall of durability of the components which comprise the fuel cell 10 like the electrolyte membrane 111 grade | etc., Can be suppressed.
　さらに、本実施形態では、起動パージ運転中の目標アノード脈動圧を下げるときに、まずアノード下限圧をＰａｄ１からＰａｄ２に下げてから、許容差圧（差圧診断の判定閾値）を下げてアノード最大圧力制限値を下げるようにした。これに関し、請求の範囲では、アノード下限圧の低下タイミングは第２所定期間に基づくものとして定義されており、許容差圧（差圧診断の判定閾値）の低下タイミング、つまりアノード上限圧の低下タイミングは第２所定期間よりも長く設定された所定期間に基づくものとして定義されている。 Further, in the present embodiment, when the target anode pulsation pressure during the start-up purge operation is lowered, the anode lower limit pressure is first lowered from Pad1 to Pad2, and then the allowable differential pressure (judgment threshold for differential pressure diagnosis) is lowered to increase the anode maximum The pressure limit value was lowered. In this regard, in the claims, the decrease timing of the anode lower limit pressure is defined as being based on the second predetermined period, and the decrease timing of the allowable differential pressure (the differential pressure diagnosis determination threshold), that is, the decrease timing of the anode upper limit pressure. Is defined as being based on a predetermined period set longer than the second predetermined period.
　仮に本実施形態とは逆に、まず許容差圧を下げてからアノード下限圧を下げてしまっては、差圧診断において誤診断が発生する可能性がある。本実施形態では、まず起動パージ運転時におけるアノード下限圧を下げてから、許容差圧を下げてアノード最大圧力制限値を下げるようにしたので、差圧診断での誤診断の発生を防止することが可能となる。 Contrary to this embodiment, if the allowable differential pressure is first lowered and then the anode lower limit pressure is lowered, there is a possibility that an erroneous diagnosis occurs in the differential pressure diagnosis. In the present embodiment, first, the anode lower limit pressure during the start purge operation is lowered, and then the allowable differential pressure is lowered to lower the anode maximum pressure limit value, thereby preventing the occurrence of misdiagnosis in the differential pressure diagnosis. Is possible.
　以上、本発明の実施形態について説明したが、上記実施形態は本発明の適用例の一部を示したに過ぎず、本発明の技術的範囲を上記実施形態の具体的構成に限定する趣旨ではない。 The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.
　本願は２０１３年５月３０日に日本国特許庁に出願された特願２０１３－１１３８１６に基づく優先権を主張し、この出願の全ての内容は参照により本明細書に組み込まれる。 This application claims priority based on Japanese Patent Application No. 2013-113816 filed with the Japan Patent Office on May 30, 2013, the entire contents of which are incorporated herein by reference.

Claims (4)

  1. 　アノードガスを間欠的に脈動供給する燃料電池システムであって、
    　カソードガスの圧力に応じてアノードガスの脈動上限圧を設定する上限設定部と、
    　燃料電池から排出されたアノードガスのパージを制御するパージ制御部と、
    　前記燃料電池システムの起動運転開始時には、前記上限設定部によって設定されたアノードガスの脈動上限圧よりも高くなるようにアノードガスの脈動上限圧を上げ、起動運転を実行する起動運転実行部と、
    　起動運転開始から所定期間が過ぎたら、起動開始時の脈動上限圧を下げるアノード圧制御部と、
    　を備える燃料電池システム。     A fuel cell system that intermittently pulsates an anode gas,
    An upper limit setting unit for setting the pulsation upper limit pressure of the anode gas according to the pressure of the cathode gas;
    A purge control unit for controlling the purge of the anode gas discharged from the fuel cell;
    At the start of start-up operation of the fuel cell system, a start-up operation execution unit that increases the pulsation upper limit pressure of the anode gas so as to be higher than the pulsation upper limit pressure of the anode gas set by the upper limit setting unit, and executes the start-up operation;
    An anode pressure control unit that lowers the pulsation upper limit pressure at the start of startup when a predetermined period has passed since the start of startup operation;
    A fuel cell system comprising:
  2. 　請求項１に記載の燃料電池システムであって、
    　カソードガスの圧力に応じてアノードガスの脈動下限圧を設定する下限設定部をさらに備え、
    　前記起動運転実行部は、起動運転開始時には、前記下限設定部によって設定されたアノードガスの脈動下限圧よりも高くなるようにアノードガスの脈動下限圧を上げて起動運転を実行し、
    　前記アノード圧制御部は、起動運転開始から第２所定期間が過ぎたら、起動開始時の脈動下限圧を下げる、
    　燃料電池システム。     The fuel cell system according to claim 1,
    A lower limit setting part for setting the pulsation lower limit pressure of the anode gas according to the pressure of the cathode gas;
    The start-up operation execution unit, at the start of the start-up operation, increases the pulsation lower limit pressure of the anode gas so as to be higher than the pulsation lower limit pressure of the anode gas set by the lower limit setting unit, and executes the start-up operation,
    The anode pressure control unit lowers the pulsation lower limit pressure at the start of the start when the second predetermined period has elapsed from the start of the start-up operation.
    Fuel cell system.
  3. 　請求項２に記載の燃料電池システムであって、
    　アノード流路の圧力とカソード流路の圧力の差圧が判定閾値よりも小さいか否かを診断する差圧診断部と、
    　起動運転開始から前記所定期間が過ぎたら、前記判定閾値を小さくする閾値切替部と、をさらに備え、
    　前記所定期間は、前記第２所定期間よりも長く設定される、
    　燃料電池システム。     The fuel cell system according to claim 2, wherein
    A differential pressure diagnostic unit for diagnosing whether or not a differential pressure between the pressure of the anode channel and the pressure of the cathode channel is smaller than a determination threshold;
    A threshold value switching unit that reduces the determination threshold when the predetermined period has elapsed from the start of the startup operation; and
    The predetermined period is set longer than the second predetermined period.
    Fuel cell system.
  4. 　請求項１から請求項３までのいずれか一つに記載の燃料電池システムであって、
    　燃料電池から排出されるカソードガスを大気に導くカソードオフガス流路と、
    　燃料電池から排出されるアノードガスをバッファ部に導くアノードオフガス流路と、
    　アノードオフガス流路から分岐してカソードオフガス流路に合流するパージ流路と、
    　パージ流路に設けられるパージ弁と、をさらに備える、
    　燃料電池システム。     A fuel cell system according to any one of claims 1 to 3, wherein
    A cathode off-gas passage for guiding the cathode gas discharged from the fuel cell to the atmosphere;
    An anode off-gas passage for guiding the anode gas discharged from the fuel cell to the buffer;
    A purge flow path branched from the anode off-gas flow path and joined to the cathode off-gas flow path;
    A purge valve provided in the purge flow path,
    Fuel cell system.
PCT/JP2014/061914 2013-05-30 2014-04-28 Fuel-cell system WO2014192486A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005153852A (en) * 2003-08-26 2005-06-16 Toyota Motor Corp Moving body
JP2006253005A (en) * 2005-03-11 2006-09-21 Nissan Motor Co Ltd Fuel cell system and starting method of fuel cell system
JP2009146748A (en) * 2007-12-14 2009-07-02 Toyota Motor Corp Fuel cell system
JP2010020923A (en) * 2008-07-08 2010-01-28 Toyota Motor Corp Fuel cell system
WO2010058747A1 (en) * 2008-11-21 2010-05-27 日産自動車株式会社 Fuel cell system and method for controlling same
WO2012033003A1 (en) * 2010-09-09 2012-03-15 日産自動車株式会社 Fuel cell system and method for operating same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005153852A (en) * 2003-08-26 2005-06-16 Toyota Motor Corp Moving body
JP2006253005A (en) * 2005-03-11 2006-09-21 Nissan Motor Co Ltd Fuel cell system and starting method of fuel cell system
JP2009146748A (en) * 2007-12-14 2009-07-02 Toyota Motor Corp Fuel cell system
JP2010020923A (en) * 2008-07-08 2010-01-28 Toyota Motor Corp Fuel cell system
WO2010058747A1 (en) * 2008-11-21 2010-05-27 日産自動車株式会社 Fuel cell system and method for controlling same
WO2012033003A1 (en) * 2010-09-09 2012-03-15 日産自動車株式会社 Fuel cell system and method for operating same

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