WO2016125231A1 - Système de pile à combustible et procédé de commande de système de pile à combustible - Google Patents

Système de pile à combustible et procédé de commande de système de pile à combustible Download PDF

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Publication number
WO2016125231A1
WO2016125231A1 PCT/JP2015/052831 JP2015052831W WO2016125231A1 WO 2016125231 A1 WO2016125231 A1 WO 2016125231A1 JP 2015052831 W JP2015052831 W JP 2015052831W WO 2016125231 A1 WO2016125231 A1 WO 2016125231A1
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WIPO (PCT)
Prior art keywords
fuel cell
cathode gas
flow rate
supply
cathode
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PCT/JP2015/052831
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English (en)
Japanese (ja)
Inventor
青木　哲也
隼人 筑後
敏和 小高
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日産自動車株式会社
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Application filed by 日産自動車株式会社 filed Critical 日産自動車株式会社
Priority to PCT/JP2015/052831 priority Critical patent/WO2016125231A1/fr
Publication of WO2016125231A1 publication Critical patent/WO2016125231A1/fr

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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
    • 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

  • the present invention relates to a fuel cell system for supplying a cathode gas and an anode gas to a fuel cell, and a control method for the fuel cell system.
  • Japanese Unexamined Patent Application Publication No. 2008-166019 discloses a fuel cell system that feedback-controls a gas supply device using a deviation between an actual flow rate of gas supplied from the gas supply device to the fuel cell and a target value.
  • the integral gain used for feedback control is changed according to the deviation between the actual gas flow rate and the target value, thereby suppressing the overshoot of the gas supply flow rate when the load fluctuation of the fuel cell is large.
  • the supply amount of the cathode gas supplied to the fuel cell is feedback-controlled in accordance with the fluctuation of the load connected to the fuel cell.
  • the gas distributed to each of the fuel cells It is necessary to consider variations in supply amount and gas transport resistance of each fuel cell.
  • the supply amount of the cathode gas supplied to the fuel cell is controlled more than the supply amount that satisfies the load requirement.
  • the power consumed by the gas supply device increases.
  • the present invention has been made paying attention to such problems, and suppresses a decrease in power generation efficiency of the fuel cell, while reducing an increase in power consumption in an apparatus for supplying a cathode gas to the fuel cell.
  • the purpose is to provide a system.
  • the fuel cell system detects the wet state of the electrolyte membrane, detects the supply state of the cathode gas supplied to the electrolyte membrane, and based on the signal detecting the wet state, the cathode gas supplied to the electrolyte membrane The power generation state is controlled by controlling the supply amount.
  • the fuel cell system determines that the supply amount of the cathode gas is insufficient based on the signal that has detected the supply state, the fuel cell system has priority over the signal that has detected the wet state and uses the signal that has detected the supply state.
  • the power generation state is controlled by controlling the supply amount of the cathode gas.
  • FIG. 1 is a diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention.
  • FIG. 2 is a diagram illustrating an example of a functional configuration of a controller that controls the fuel cell system.
  • FIG. 3 is a diagram illustrating an example of a functional configuration for calculating an excess amount of the cathode gas supply flow rate as a supply state of the cathode gas supplied to the fuel cell.
  • FIG. 4A is a diagram showing an equivalent circuit of the fuel cell.
  • FIG. 4B is a diagram relating to a method of calculating the reaction resistance of the cathode electrode in the fuel cell.
  • FIG. 1 is a diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention.
  • FIG. 2 is a diagram illustrating an example of a functional configuration of a controller that controls the fuel cell system.
  • FIG. 3 is a diagram illustrating an example of a functional configuration for calculating an excess amount of the cathode gas supply flow
  • FIG. 5 is a diagram showing an example of a functional configuration for calculating the reaction resistance of the cathode electrode as the supply state of the cathode gas.
  • FIG. 6 is a diagram illustrating an example of a functional configuration that feedback-controls the cathode gas supply flow rate according to the wet state of the electrolyte membrane formed in the fuel cell.
  • FIG. 7 is a diagram showing the relationship between the output of the fuel cell and the target wet state of the electrolyte membrane.
  • FIG. 8 is a diagram illustrating an example of a functional configuration that prevents an excessive decrease in the cathode gas supply flow rate.
  • FIG. 9 is a flowchart showing an example of a control method for controlling the fuel cell system in the present embodiment.
  • FIG. 9 is a flowchart showing an example of a control method for controlling the fuel cell system in the present embodiment.
  • FIG. 10 is a flowchart illustrating an example of a process for calculating an excess amount of the cathode gas supply flow rate.
  • FIG. 11 is a flowchart illustrating an example of processing for calculating the reaction resistance of the cathode electrode.
  • FIG. 12 is a flowchart illustrating an example of a process for predicting a shortage of the cathode gas supply flow rate.
  • FIG. 13 is a flowchart illustrating an example of a process for preventing the cathode gas supply flow rate from being excessively lowered.
  • FIG. 14 is a time chart showing an example of a change in the cathode gas supply amount when the process shown in FIG. 13 is executed.
  • FIG. 14 is a time chart showing an example of a change in the cathode gas supply amount when the process shown in FIG. 13 is executed.
  • FIG. 15 is a diagram illustrating an example of a functional configuration for changing a gain used for feedback control in the second embodiment of the present invention.
  • FIG. 16 is a diagram illustrating an example of a functional configuration for changing the integral gain in accordance with a change in the degree of oxygen deficiency in the fuel cell.
  • FIG. 17 is a flowchart showing an example of a control method of the fuel cell system in the present embodiment.
  • FIG. 18 is a flowchart showing an example of processing for changing the gain used for feedback control in accordance with the degree of oxygen deficiency of the fuel cell.
  • FIG. 19 is a time chart showing the change in overshoot of the cathode gas supply flow rate when the gain used for feedback control is reduced.
  • FIG. 20 is a time chart showing an example of a change in the cathode gas supply amount when the control method shown in FIG. 17 is executed.
  • FIG. 21 is a diagram showing the configuration of the fuel cell system according to the third embodiment of the present invention.
  • FIG. 22 is a diagram illustrating an example of a functional configuration for calculating the cathode gas supply flow rate.
  • FIG. 23 is a flowchart showing an example of a control method of the fuel cell system in the present embodiment.
  • FIG. 24 is a flowchart illustrating an example of a process for calculating a surplus amount of the cathode gas supply flow rate in the control method illustrated in FIG.
  • FIG. 25 is a flowchart showing an example of processing for calculating the cathode gas supply flow rate in the processing shown in FIG. FIG.
  • FIG. 26 is a diagram showing a configuration of a fuel cell system according to the fourth embodiment of the present invention.
  • FIG. 27 is a flowchart showing an example of a control method of the fuel cell system in the present embodiment.
  • FIG. 28 is a flowchart illustrating an example of a process for calculating an excess amount of the cathode gas supply flow rate in the control method illustrated in FIG.
  • FIG. 29 is a diagram illustrating an example of the configuration of the impedance measuring apparatus.
  • FIG. 1 is a diagram illustrating an example of a configuration of a fuel cell system 100 according to the first embodiment of the present invention.
  • the fuel cell system 100 constitutes a power supply system that supplies an anode gas and a cathode gas necessary for power generation from the outside to the fuel cell, and generates the fuel cell according to an electric load.
  • the fuel cell system 100 includes a fuel cell stack 1, an anode gas supply / discharge device 2, a cathode gas supply / discharge device 3, a stack cooling device 4, a load 5, an impedance measurement device 6, and a controller 200.
  • the fuel cell stack 1 is a stacked battery that is connected to the load 5 and supplies power to the load 5.
  • the fuel cell stack 1 generates a DC voltage of, for example, several hundred V (volts).
  • a fuel cell includes an anode electrode (fuel electrode), a cathode electrode (oxidant electrode), and an electrolyte membrane sandwiched between the anode electrode and the cathode electrode.
  • an anode gas (fuel gas) containing hydrogen in the anode electrode and a cathode gas (oxidant gas) containing oxygen in the cathode electrode cause an electrochemical reaction (power generation reaction) in the electrolyte membrane.
  • the following electrochemical reaction proceeds at the anode electrode and the cathode electrode.
  • Anode electrode 2H 2 ⁇ 4H + + 4e ⁇ (1)
  • Cathode electrode 4H ++ 4e- + O 2 ⁇ 2H 2 O (2)
  • the fuel cell stack 1 is supplied with the anode gas from the anode gas supply / discharge device 2 and the cathode gas from the cathode gas supply / discharge device 3.
  • the anode gas supply / discharge device 2 is a device that supplies anode gas to the fuel cell stack 1 and circulates anode off-gas discharged from the fuel cell stack 1 to the fuel cell stack 1. That is, the anode gas supply / discharge device 2 constitutes anode gas supply means for supplying anode gas to the electrolyte membrane of the fuel cell stacked on the fuel cell stack 1.
  • the anode gas supply / discharge device 2 includes a high-pressure tank 21, an anode gas supply passage 22, an anode pressure regulating valve 23, an ejector 24, an anode gas circulation passage 25, and an anode circulation pump 26.
  • the high pressure tank 21 stores the anode gas supplied to the fuel cell stack 1 in a high pressure state.
  • the anode gas supply passage 22 is a passage for supplying the anode gas stored in the high-pressure tank 21 to the fuel cell stack 1.
  • One end of the anode gas supply passage 22 is connected to the high-pressure tank 21, and the other end is connected to the anode gas inlet hole of the fuel cell stack 1.
  • the anode pressure regulating valve 23 is provided in the anode gas supply passage 22 between the high pressure tank 21 and the ejector 24.
  • an electromagnetic valve capable of changing the opening degree of the valve stepwise is used as the anode pressure regulating valve 23.
  • the anode pressure regulating valve 23 is controlled to be opened and closed by the controller 200. By this opening / closing control, the pressure of the anode gas supplied to the fuel cell stack 1 is adjusted.
  • the ejector 24 is provided in the anode gas supply passage 22 between the anode pressure regulating valve 23 and the fuel cell stack 1.
  • the ejector 24 is a mechanical pump that joins the anode gas circulation passage 25 to the anode gas supply passage 22.
  • the ejector 24 sucks the anode off gas from the fuel cell stack 1 by accelerating the flow rate of the anode gas supplied from the anode pressure regulating valve 23 to generate a negative pressure.
  • the ejector 24 discharges the anode off gas together with the anode gas supplied from the anode pressure regulating valve 23 to the fuel cell stack 1.
  • the ejector 24 includes a cylindrical nozzle having an opening that narrows as the fuel cell stack 1 is approached, and a diffuser that has a confluence passage communicating with the anode off-gas suction port coaxially with the nozzle.
  • the anode gas circulation passage 25 is a passage through which the anode off gas from the fuel cell stack 1 is circulated to the anode gas supply passage 22.
  • One end of the anode gas circulation passage 25 is connected to the anode gas outlet hole of the fuel cell stack 1, and the other end is connected to the suction port of the ejector 24.
  • the anode circulation pump 26 is provided in the anode gas circulation passage 25.
  • the anode circulation pump 26 circulates the anode off gas through the fuel cell stack 1 via the ejector 24.
  • the rotation speed of the anode circulation pump 26 is controlled by the controller 200.
  • a gas-liquid separator, a purge valve, or the like may be provided in the anode gas circulation passage 25 so that nitrogen gas or water vapor in the anode off-gas is discharged to the outside.
  • the cathode gas supply / discharge device 3 is a device that supplies cathode gas to the fuel cell stack 1 and discharges cathode off-gas discharged from the fuel cell stack 1 to the atmosphere. That is, the cathode gas supply / discharge device 3 constitutes a cathode gas supply means for supplying cathode gas to the electrolyte membrane of the fuel cell stacked on the fuel cell stack 1.
  • the cathode gas supply / discharge device 3 includes a cathode gas supply passage 31, a compressor 32, a cathode gas discharge passage 33, and a cathode pressure regulating valve 34.
  • the cathode gas supply passage 31 is a passage for supplying cathode gas to the fuel cell stack 1. One end of the cathode gas supply passage 31 is open, and the other end is connected to the cathode gas inlet hole of the fuel cell stack 1.
  • the compressor 32 is provided in the cathode gas supply passage 31.
  • the compressor 32 takes in oxygen-containing air from the opening of the cathode gas supply passage 31 and supplies the air as the cathode gas to the fuel cell stack 1.
  • the rotation speed of the compressor 32 is controlled by the controller 200.
  • the cathode gas discharge passage 33 is a passage for discharging the cathode off gas from the fuel cell stack 1.
  • One end of the cathode gas discharge passage 33 is connected to the cathode gas outlet hole of the fuel cell stack 1, and the other end is opened.
  • the cathode pressure regulating valve 34 is provided in the cathode gas discharge passage 33.
  • the cathode pressure regulating valve 34 for example, an electromagnetic valve capable of changing the opening degree of the valve stepwise is used.
  • the cathode pressure regulating valve 34 is controlled to be opened and closed by the controller 200. By this open / close control, the pressure of the cathode gas supplied to the fuel cell stack 1 is adjusted to a desired pressure.
  • the cathode pressure regulating valve 34 opens as the opening degree of the cathode pressure regulating valve 34 increases, and the cathode pressure regulating valve 34 closes as the opening degree of the cathode pressure regulating valve 34 increases.
  • the stack cooling device 40 is a device that adjusts the fuel cell stack 1 to a temperature suitable for power generation using a refrigerant.
  • the stack cooling device 40 includes a cooling water circulation passage 41, a cooling water pump 42, a radiator 43, a bypass passage 44, a thermostat 45, a stack inlet water temperature sensor 46, and a stack outlet water temperature sensor 47.
  • the cooling water circulation passage 41 is a passage for circulating cooling water as a refrigerant in the fuel cell stack 1.
  • One end of the cooling water circulation passage 41 is connected to the cooling water inlet hole of the fuel cell stack 1, and the other end is connected to the cooling water outlet hole of the fuel cell stack 1.
  • the cooling water pump 42 is provided in the cooling water circulation passage 41.
  • the cooling water pump 42 supplies cooling water to the fuel cell stack 1 via the radiator 43.
  • the rotation speed of the cooling water pump 42 is controlled by the controller 200.
  • the radiator 43 is provided in the cooling water circulation passage 41 downstream of the cooling water pump 42.
  • the radiator 43 cools the cooling water heated by the fuel cell stack 1.
  • the bypass passage 44 is a passage that bypasses the radiator 43 and directly circulates the cooling water to the fuel cell stack 1.
  • One end of the bypass passage 44 is connected to a cooling water circulation passage 41 provided with a cooling water pump 42, and the other end is connected to a thermostat 45.
  • a heater for warming up the fuel cell stack 1 at the time of starting below zero may be provided in the bypass passage 44.
  • the thermostat 45 is composed of a three-way valve.
  • the thermostat 45 is provided in a portion where the bypass passage 44 joins the cooling water circulation passage 41 between the radiator 43 and the cooling water inlet hole of the fuel cell stack 1.
  • the thermostat 45 when the temperature of the cooling water is below a predetermined valve opening temperature, the cooling water passage from the radiator 43 to the fuel cell stack 1 is closed, and only the cooling water that has passed through the bypass passage 44 is used as the fuel cell. Supply to stack 1. As a result, cooling water having a temperature higher than that of the cooling water passing through the radiator 43 flows through the fuel cell stack 1.
  • the thermostat 45 when the temperature of the cooling water becomes higher than the above-described valve opening temperature, the cooling water passage from the radiator 43 to the fuel cell stack 1 begins to open gradually.
  • the thermostat 45 mixes the cooling water that has passed through the bypass passage 44 and the cooling water that has passed through the radiator 43 and supplies the mixed water to the fuel cell stack 1. As a result, cooling water having a temperature lower than that of the cooling water passing through the bypass passage 44 flows through the fuel cell stack 1.
  • the stack inlet water temperature sensor 46 is provided in the cooling water circulation passage 41 located in the vicinity of the cooling water inlet hole of the fuel cell stack 1.
  • the stack inlet water temperature sensor 46 detects the temperature of cooling water flowing into the fuel cell stack 1 (hereinafter referred to as “stack inlet water temperature”).
  • the stack inlet water temperature sensor 46 outputs a detection signal indicating the detected temperature to the controller 200.
  • the stack outlet water temperature sensor 47 is provided in the cooling water circulation passage 41 located in the vicinity of the cooling water outlet hole of the fuel cell stack 1.
  • the stack outlet water temperature sensor 47 detects the temperature of the cooling water discharged from the fuel cell stack 1 (hereinafter referred to as “stack outlet water temperature”).
  • the stack outlet water temperature sensor 47 outputs a detection signal indicating the detected temperature to the controller 200.
  • the load 5 is a load device that is driven by the power generated by the fuel cell stack 1.
  • the load 5 includes, for example, an electric motor that drives the vehicle, an auxiliary device that assists the power generation of the fuel cell stack 1, a control unit that controls the electric motor, and the like.
  • Examples of the auxiliary equipment of the fuel cell stack 1 include a compressor 32 and a heater (not shown) provided in the bypass passage 44.
  • the load 5 includes a DC / DC converter, an electric motor inverter is connected to one of the DC / DC converters, a battery is connected to the other, and a power supply line between the DC / DC converter and the battery is supplemented.
  • a configuration in which a part of the machine is connected may be used.
  • the control unit that controls the load 5 outputs the required power required for the fuel cell stack 1 to the controller 200. For example, the required power required for the fuel cell stack 1 increases as the amount of depression of the accelerator pedal increases.
  • a current sensor 51 and a voltage sensor 52 are provided between the load 5 and the fuel cell stack 1.
  • the current sensor 51 is connected to a power supply line between the positive electrode terminal 11 of the fuel cell stack 1 and the load 5.
  • the current sensor 51 detects a current output from the fuel cell stack 1 to the load 5 (hereinafter referred to as “stack output current”).
  • the current sensor 51 outputs a detection signal indicating the detected stack output current to the controller 200.
  • the voltage sensor 52 is connected between the positive electrode terminal 11 and the negative electrode terminal 12 of the fuel cell stack 1.
  • the voltage sensor 52 detects an inter-terminal voltage (hereinafter referred to as “stack output voltage”) between the positive terminal 11 and the negative terminal 12 of the fuel cell stack 1.
  • the voltage sensor 52 outputs a detection signal indicating the detected stack output voltage to the controller 200.
  • the impedance measuring device 6 is a device that detects the wet state of the electrolyte membrane laminated on the fuel cell stack 1.
  • the impedance measuring device 6 measures the internal impedance of the fuel cell stack 1 correlated with the wet state of the electrolyte membrane.
  • the smaller the water content of the electrolyte membrane, that is, the dryr the electrolyte membrane the greater the electrical resistance component of the internal impedance.
  • the greater the moisture content of the electrolyte membrane, that is, the wetter the electrolyte membrane the smaller the electrical resistance component of the internal impedance.
  • the fuel cell stack 1 includes a positive electrode tab connected in series with the positive electrode terminal 11 and a negative electrode tab connected in series with the negative electrode terminal 12, and the impedance measuring device 6 is provided in each of the positive electrode tab and the negative electrode tab. Is connected.
  • the impedance measuring device 6 supplies an alternating current having a frequency suitable for detecting the electric resistance of the electrolyte membrane to the positive electrode terminal 11.
  • the frequency suitable for detecting the electric resistance of the electrolyte membrane is hereinafter referred to as “electrolyte membrane response frequency”.
  • the impedance measuring device 6 detects an AC voltage generated between the positive electrode terminal 11 and the negative electrode terminal 12 by an AC current having an electrolyte membrane response frequency, and the amplitude of the detected AC voltage is supplied to the positive electrode terminal 11.
  • the internal impedance is calculated by dividing by.
  • a halfway tab is provided in a fuel cell located in the middle, and the impedance measuring device 6 is also connected to the middle tab. Then, the impedance measuring device 6 may supply an alternating current having an electrolyte membrane response frequency to both the positive electrode terminal 11 and the negative electrode terminal 12. In this case, the midway tab is grounded via the capacitor in the impedance measuring device 6.
  • the impedance measuring device 6 calculates the internal impedance on the positive electrode side by dividing the amplitude of the alternating voltage between the positive electrode terminal 11 and the halfway tab by the amplitude of the alternating current supplied to the positive electrode terminal 11. Further, the impedance measuring device 6 calculates the internal impedance on the negative electrode side by dividing the amplitude of the alternating voltage between the negative electrode terminal 12 and the halfway tab by the amplitude of the alternating current supplied to the negative electrode terminal 12.
  • HFR High Frequency Resistance
  • the controller 200 includes a microcomputer that includes 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 200 receives the output values of the current sensor 51, the voltage sensor 52 and the impedance measuring device 6 and the required power of the load 5. Based on these parameters, the controller 200 controls the rotation speed of the compressor 32 and the opening degree of the cathode pressure regulating valve 34.
  • the controller 200 changes the cathode gas target flow rate and the anode gas target flow rate according to the required power required from the load 5.
  • the controller 200 controls the rotation speed of the compressor 32 and the opening of the cathode pressure regulating valve 34 based on the cathode gas target flow rate, and the opening degree of the anode pressure regulating valve 23 and the anode circulation pump based on the anode gas target flow rate. 26 rotation speeds are controlled.
  • the controller 200 calculates the average value of the stack inlet water temperature and the stack outlet water temperature as the temperature of the fuel cell stack 1, and controls the rotation speed of the cooling water pump 42 based on the average value. For example, the controller 200 increases the rotation speed of the coolant pump 42 as the temperature of the fuel cell stack 1 increases.
  • FIG. 2 is a block diagram showing a functional configuration of the controller 200 in the present embodiment.
  • the controller 200 includes a film wet state detection unit 210, a gas supply state detection unit 220, and a power generation control unit 300.
  • the membrane wet state detection unit 210 acquires the HFR of the fuel cell stack 1 from the impedance measuring device 6 as wet state information indicating the wetness (water content) of the electrolyte membrane.
  • the HFR output from the impedance measurement device 6 is referred to as “measurement HFR”.
  • the film wet state detection unit 210 outputs the measured HFR to the gas flow rate F / B control unit 301.
  • the membrane wet state detection unit 210 may generate wet state information based on the temperature of the fuel cell stack 1.
  • the membrane wet state detection unit 210 acquires the stack inlet water temperature and the stack outlet water temperature from the stack inlet water temperature sensor 46 and the stack outlet water temperature sensor 47 as wet state information.
  • the membrane wet state detection unit 210 calculates the average value of the stack inlet water temperature and the stack outlet water temperature as the temperature of the fuel cell stack 1, and refers to a predetermined wet estimation map and associates it with the calculated average value. Generating wet state information.
  • the film wet state detection unit 210 may generate wet state information based on the required power of the load 5.
  • the film wet state detection unit 210 acquires the required power from the control unit of the load 5, refers to a predetermined wet estimation map, and obtains wet state information associated with the acquired required power. Generate.
  • the membrane wet state detection unit 210 increases the wetness indicated in the wet state information because the amount of generated water increases as the required power increases.
  • the membrane wet state detection unit 210 may correct the measured HFR from the impedance measuring device 6 according to the temperature of the fuel cell stack 1 and the required power of the load 5.
  • the membrane wet state detection unit 210 constitutes a wet state detection unit that detects the wet state of the electrolyte membrane in the fuel cell stack 1.
  • the gas supply state detection unit 220 determines the oxygen deficiency degree indicating the oxygen deficiency state of the fuel cell in the fuel cell stack 1 based on the supply state information indicating the supply flow rate and supply pressure of the cathode gas supplied to the fuel cell stack 1. Ask.
  • the gas supply state detection unit 220 acquires the required power of the load 5, the rotational speed of the compressor 32, and the opening of the cathode pressure regulating valve 34 as cathode gas supply state information. For example, the gas supply state detection unit 220 obtains the actual value of the rotational speed of the compressor 32 from the rotational speed sensor provided in the compressor 32, and from the opening degree sensor provided in the cathode pressure regulating valve 34, the cathode pressure regulating valve. The actual value of the opening of 34 is acquired. The gas supply state detection unit 220 may obtain the rotational speed of the compressor 32 and the opening of the cathode pressure regulating valve 34 based on the command values of the compressor 32 and the cathode pressure regulating valve.
  • the gas supply state detection unit 220 acquires the stack output current from the current sensor 51 and the stack output voltage from the voltage sensor 52 as the output power of the fuel cell stack 1 as the supply state information.
  • the gas supply state detection unit 220 outputs the stack output voltage to the power generation control unit 300 as the first parameter indicating the degree of oxygen deficiency.
  • the gas supply state detection unit 220 may determine that the supply state of the cathode gas is approaching an insufficient state as the voltage of the fuel cell stack 1 decreases, and output the determination result. By using this measurement result, the degree of oxygen deficiency of the fuel cell can be estimated.
  • the gas supply state detection unit 220 determines the cathode gas supply flow rate based on the required power of the load 5, the rotational speed of the compressor 32 and the opening of the cathode pressure regulating valve 34, which are control amounts of the cathode gas supply / discharge device 3. Estimate the surplus.
  • the gas supply state detection unit 220 outputs the excess amount of the cathode gas supply flow rate to the power generation control unit 300 as the second parameter indicating the degree of oxygen deficiency.
  • the gas supply state detection unit 220 determines that the supply state of the cathode gas approaches the shortage state as the supply amount of the cathode gas calculated based on the control amount of the cathode gas supply / exhaust device 3 increases. The determination result may be output.
  • the gas supply state detection unit 220 acquires, as supply state information, the internal impedance measured at a frequency lower than the HFR measurement frequency from the impedance measurement device 6.
  • the internal impedance measured at a frequency lower than the measurement frequency of the HFR is referred to as LFI (Low Frequency Frequency Impedance).
  • the gas supply state detection unit 220 calculates an electrical resistance value (hereinafter referred to as “cathode electrode reaction resistance”) due to an electrode reaction occurring at the cathode electrode of the fuel cell, based on the low frequency impedance LFI.
  • cathode electrode reaction resistance an electrical resistance value due to an electrode reaction occurring at the cathode electrode of the fuel cell
  • the electrode reaction at the cathode electrode is less likely to occur as the amount of oxygen to the fuel cell stack 1 becomes smaller than the minimum amount of oxygen necessary to cover the required power of the load 5 by the power generation of the fuel cell stack 1. As a result, the cathode reaction resistance increases.
  • the gas supply state detection unit 220 outputs the cathode reaction resistance to the power generation control unit 300 as a third parameter indicating the degree of oxygen deficiency.
  • the gas supply state detection unit 220 determines that the cathode gas supply state is approaching an insufficient state as the reaction resistance of the cathode electrode calculated based on the impedance of the fuel cell increases, and outputs the determination result. You may make it do.
  • the gas supply state detection unit 220 constitutes supply state detection means for detecting the supply state of the cathode gas supplied to the fuel cells in the fuel cell stack 1.
  • the power generation control unit 300 controls the power generation of the fuel cell stack 1 by mutually controlling the anode gas supply by the anode pressure regulating valve 23 and the anode circulation pump 26 and the cathode gas supply by the compressor 32 and the cathode pressure regulating valve 34.
  • the control means is configured.
  • the power generation control unit 300 controls the supply amount of the cathode gas supplied to the fuel cell stack 1 based on a signal including three parameters indicating the wet state from the membrane wet state detection unit 210. Thus, the power generation state of the fuel cell stack 1 is controlled.
  • the power generation control unit 300 supplies the fuel cell stack 1 to the fuel cell stack 1 as compared with the supply amount of the cathode gas necessary to generate the required power of the load 5. It is determined whether or not the cathode gas supply amount is insufficient.
  • the power generation control unit 300 prioritizes the signal indicating the wet state from the membrane wet state detection unit 210 and determines the degree of oxygen deficiency from the gas supply state detection unit 220.
  • the power generation state is controlled by controlling the cathode gas supply amount using the signal shown.
  • the power generation control unit 300 includes a gas flow rate F / B control unit 301 and a priority control unit 302.
  • the gas flow rate F / B control unit 301 supplies the cathode gas supplied to the fuel cell stack 1 based on the deviation between the signal indicating the wet state from the membrane wet state detection unit 210 and the target value regarding the wet state of the electrolyte membrane. Feedback (F / B) control.
  • the gas flow rate F / B control unit 301 calculates the cathode gas supply flow rate so that the measured HFR of the fuel cell stack 1 matches the target HFR that is the target value in the wet state.
  • the gas flow rate F / B control unit 301 outputs the calculated cathode gas supply flow rate to the priority control unit 302 as a wet request flow rate.
  • the gas flow rate F / B control unit 301 decreases the required wet flow rate as the target HFR decreases.
  • the gas flow rate F / B control unit 301 further lowers the required wet flow rate from the cathode gas supply flow rate in the steady state until the cathode gas supply flow rate decreases to the steady state. That is, the gas flow rate F / B control unit 301 causes an overshoot when lowering the cathode gas supply flow rate.
  • the priority control unit 302 gives priority to the signal indicating the degree of oxygen deficiency from the gas supply state detection unit 220 in preference to the signal indicating the wet state from the membrane wet state detection unit 210.
  • Priority control means for controlling the cathode gas supply flow rate is configured.
  • the priority control unit 302 includes a transient gas flow rate reduction width limiting unit 320, a gas deficiency determining unit 330, a target flow rate setting unit 340, and a gas supply system command unit 350.
  • the transient gas flow rate reduction width restriction unit 320 restricts the required wet flow rate calculated by the gas flow rate F / B control unit 301 in a transient state where the cathode gas supply flow rate sharply decreases as the target HFR decreases.
  • the transient gas flow rate reduction width limit unit 320 reduces the cathode gas supply flow rate calculated by the gas flow rate F / B control unit 301 based on a signal indicating the degree of oxygen deficiency from the gas supply state detection unit 220. Limit.
  • the transient gas flow rate reduction width limiting unit 320 sets the lower limit flow rate that is the lower limit value of the cathode gas supply flow rate based on the required power of the load 5 or the output power of the fuel cell stack 1. Calculate the supply flow required for power generation.
  • the transient gas flow rate reduction width limiting unit 320 outputs the lower limit flow rate of the cathode gas to the target flow rate setting unit 340.
  • the gas deficiency determination unit 330 determines whether or not the cathode gas supply flow rate is likely to be insufficient based on a signal indicating the degree of oxygen deficiency from the gas supply state detection unit 220. That is, the gas deficiency determination unit 330 predicts whether or not the fuel cell is in an oxygen deficient state (hereinafter referred to as “oxygen deficient state”) according to the supply state of the cathode gas supplied to the fuel cell stack 1. .
  • the gas deficiency determination unit 330 sets an oxygen deficiency flag indicating that the fuel cell may be in an oxygen deficiency state to ON. Thereby, a determination signal of H (High) level is supplied from the gas deficiency determination unit 330 to the target flow rate setting unit 240.
  • the gas deficiency determination unit 330 sets the oxygen deficiency flag to OFF. As a result, an L (Low) level determination signal is supplied from the gas deficiency determination unit 330 to the target flow rate setting unit 240.
  • the target flow rate setting unit 340 limits the cathode gas target flow rate, which is the target value of the cathode gas supply flow rate, based on the setting state of the oxygen deficiency flag.
  • the target flow rate setting unit 340 sets the required wet flow rate from the gas flow rate F / B control unit 301 and the lower limit flow rate from the transient gas flow rate reduction width limiting unit 320. Based on this, the cathode gas target flow rate is set.
  • the target flow rate setting unit 340 outputs the cathode gas target flow rate to the gas supply system command unit 350.
  • the target flow rate setting unit 340 sets the required wet flow rate to the cathode gas target flow rate when the oxygen shortage flag is set to ON and the required wet flow rate of the cathode gas is equal to or higher than the lower limit flow rate. On the other hand, when the required wet flow rate of the cathode gas is lower than the lower limit flow rate, the target flow rate setting unit 340 limits the cathode gas target flow rate to the lower limit flow rate.
  • the target flow rate setting unit 340 sets the required wet flow rate from the gas flow rate F / B control unit 301 to the cathode gas target flow rate.
  • the target flow rate setting unit 340 outputs the cathode gas target flow rate to the gas supply system command unit 350.
  • the gas supply system command unit 350 controls the operation of the cathode gas supply / discharge device 3 based on the cathode gas target flow rate from the target flow rate setting unit 340.
  • the gas supply system command unit 350 determines the rotation speed command value of the compressor 32 and the cathode pressure regulating valve 34 based on the cathode gas target pressure based on the operating state of the fuel cell stack 1 and the cathode gas target flow rate. Calculate the opening command value.
  • the gas supply system command unit 350 outputs the rotational speed command value of the compressor 32 to the compressor 32 and outputs the opening command value of the cathode pressure regulating valve 34 to the cathode pressure regulating valve 34.
  • the cathode gas target pressure is calculated based on the temperature of the fuel cell stack 1, for example.
  • the reason for this setting is that as the temperature of the fuel cell stack 1 increases, the partial pressure of water vapor in the cathode gas increases and the partial pressure of oxygen decreases, making it difficult to secure the required power of the load 5. Because. Therefore, the controller 200 increases the cathode gas target pressure as compared to the atmospheric pressure as the temperature of the fuel cell stack 1 increases in order to maintain the oxygen partial pressure in the cathode gas.
  • the cathode gas target pressure is changed according to the anode gas supply pressure supplied to the fuel cell stack 1. This is to prevent the differential pressure between the anode gas supply pressure and the cathode gas supply pressure from exceeding the allowable pressure of the electrolyte membrane.
  • the gas supply system command unit 350 calculates the opening command value of the anode pressure regulating valve 23 and the rotational speed command value of the anode circulation pump 26 based on the anode gas target flow rate and the anode gas target pressure.
  • the gas supply system command unit 350 outputs the opening command value of the anode pressure regulating valve 23 to the anode pressure regulating valve 23 and outputs the rotation speed command value of the anode circulation pump 26 to the anode circulation pump 26.
  • the anode gas target flow rate is calculated based on the required power of the load 5
  • the anode gas target pressure is calculated based on, for example, the partial pressure of water vapor in the anode gas.
  • FIG. 3 is a block diagram illustrating a part of the functional configuration of the gas supply state detection unit 220. Here, a configuration for calculating the surplus amount ⁇ Q of the cathode gas supply flow rate as a signal indicating the degree of oxygen deficiency is shown.
  • the gas supply state detection unit 220 includes a cathode gas supply flow rate estimation unit 221, a load request flow rate calculation unit 222, and an oxygen deficiency degree calculation unit 223.
  • the cathode gas supply flow rate estimation unit 221 estimates the supply flow rate Qc of the cathode gas supplied to the fuel cell stack 1 based on the opening degree of the cathode pressure regulating valve 34 and the rotational speed of the compressor 32.
  • the cathode gas supply flow rate estimation unit 221 includes a supply passage pressure loss characteristic extraction unit 2211, a compressor operation characteristic extraction unit 2212, and an intersection extraction unit 2213.
  • a supply passage pressure loss map is recorded in advance.
  • a pressure loss characteristic indicating the relationship between the discharge flow rate of the compressor 32 and the pressure loss of the cathode gas supply passage 31 is set for each opening of the cathode pressure regulating valve 34.
  • the supply passage pressure loss characteristic extraction unit 2211 refers to the supply passage pressure loss map and extracts the pressure loss characteristic specified by the acquired detection value.
  • the supply passage pressure loss characteristic extraction unit 2211 outputs the extracted pressure loss characteristic to the intersection extraction unit 2213.
  • the compressor operation characteristic extraction unit 2212 records a compressor operation characteristic map in advance.
  • a discharge flow rate characteristic indicating a relationship between the discharge flow rate of the compressor 32 and the pressure loss of the cathode gas supply passage 31 is set for each rotation speed of the compressor 32.
  • Compressor operation characteristic extraction unit 2212 when acquiring the detected value of the rotation speed of compressor 32, refers to the compressor dynamic characteristic map and extracts the discharge flow rate characteristic specified by the acquired detection value.
  • the compressor operation characteristic extraction unit 2212 outputs the extracted discharge flow characteristic to the intersection extraction unit 2213.
  • intersection point extraction unit 2213 identifies the intersection point between the pressure loss characteristic from the supply passage pressure loss characteristic extraction unit 2211 and the discharge flow rate characteristic from the compressor operation characteristic extraction unit 2212.
  • the intersection extraction unit 2213 outputs the discharge flow rate specified by the intersection to the oxygen deficiency degree calculation unit 223 as the estimated value Qc of the cathode gas supply flow rate.
  • the cathode gas supply flow rate estimation unit 221 specifies the pressure loss characteristic with respect to the supply flow rate of the cathode gas supply passage 31 based on the opening degree of the cathode pressure regulating valve 34, and against the pressure loss based on the rotation speed of the compressor 32. Specify the discharge flow rate characteristics. Then, the cathode gas supply flow rate estimation unit 221 estimates the cathode gas supply flow rate Qc by obtaining the intersection of the pressure loss characteristic of the cathode gas supply passage 31 and the discharge flow rate characteristic of the compressor 32.
  • the load request flow rate calculation unit 222 calculates the cathode gas supply flow rate that is at least necessary for power generation of the fuel cell stack 1 based on the stack target current that is the target value of the output current of the fuel cell stack 1.
  • the above stack target current is determined based on the required power of the load 5. For example, when the required power of the load 5 is acquired, the controller 200 refers to the current voltage (IV) characteristics of the fuel cell stack 1 and calculates the current value that is the required power of the load 5 as the stack target current.
  • IV current voltage
  • a power generation request flow rate map indicating the relationship between the stack target current and the cathode gas supply flow rate is recorded in advance. Then, when the stack target current is acquired, the load request flow rate calculation unit 222 refers to the power generation request flow map and calculates the cathode gas supply flow rate related to the acquired stack target current. The load request flow rate calculation unit 222 outputs the cathode gas supply flow rate to the oxygen deficiency degree calculation unit 223 as the load request flow rate Qr_l.
  • the oxygen deficiency degree calculation unit 223 calculates the surplus amount ⁇ Q of the cathode gas supply flow rate by subtracting the load request flow rate Qr_l from the cathode gas supply flow rate Qc.
  • the oxygen deficiency degree calculation unit 223 outputs the excess amount ⁇ Q of the cathode gas supply flow rate as a parameter indicating the degree of oxygen deficiency to the transient gas flow rate reduction width restriction unit 320 and the gas deficiency determination unit 330.
  • FIG. 4A is a diagram showing an equivalent circuit of a fuel cell stacked on the fuel cell stack 1.
  • the equivalent circuit of the fuel cell includes an anode electrode reaction resistance Ra and an anode electrode electric double capacity Ca, an electrolyte membrane resistance Rm, a cathode electrode reaction resistance Rc, and a cathode electrode electric double capacity Cc.
  • anode electrode reaction resistance Ra and an anode electrode electric double capacity Ca an electrolyte membrane resistance Rm, a cathode electrode reaction resistance Rc, and a cathode electrode electric double capacity Cc.
  • a capacitor Cb is connected in series.
  • the anode electrode reaction resistance Ra is an electric resistance caused by an electrochemical reaction at the anode electrode, and increases or decreases according to the electrochemical reaction of the anode gas. In a state where the electrochemical reaction of the anode gas does not proceed smoothly, for example, in a state where the anode gas is insufficient, the anode electrode reaction resistance Ra tends to increase.
  • the anode electrode electric double capacity Ca is an electric capacity of the anode electrode, and is determined by a material constituting the anode electrode, a surface area of the anode electrode, and the like.
  • the electrolyte membrane resistance Rm is the electrical resistance of the electrolyte membrane, and increases or decreases depending on the wetness of the electrolyte membrane. Generally, as the electrolyte membrane dries, the electrolyte membrane resistance Rm tends to increase.
  • the cathode electrode reaction resistance Rc is an electric resistance caused by an electrochemical reaction at the cathode electrode, and increases or decreases according to the electrochemical reaction of the cathode gas.
  • the cathode reaction resistance Rc tends to increase.
  • the cathode electrode electric double capacity Cc is an electric capacity of the cathode electrode, and is determined by a material constituting the cathode electrode, a surface area of the cathode electrode, and the like.
  • the path of the current flowing through the equivalent circuit varies depending on the change in the frequency of the alternating current supplied to the fuel cell. That is, the equivalent circuit of the fuel cell has frequency dependency. Therefore, the impedance Z of the fuel cell is expressed as the following equation (3).
  • j means an imaginary unit
  • ⁇ is the angular frequency of the alternating current.
  • the angular frequency ⁇ is obtained by multiplying the frequency f of the alternating current by “2 ⁇ ”.
  • the electrical characteristics in the fuel cell stack 1 when power is being supplied from the fuel cell stack 1 to the load 5 are several Hz even if the frequency is large considering the speed of the accelerator operation of the driver and the response delay of the cathode gas. What is necessary is to assume output characteristics in a low frequency band up to (Hertz).
  • the cathode gas response delay is a response delay until the cathode gas discharged from the compressor 32 reaches the fuel cell stack 1.
  • the electrical characteristics in the fuel cell stack 1 when power is supplied from the fuel cell stack 1 to the load 5 are obtained by using the characteristics when the angular frequency ⁇ in the equation (3) is 0 (zero). Can be approximated.
  • the internal impedance Z of the fuel cell stack 1 in such a steady state is expressed by the following equation (4).
  • the electrical characteristics of the fuel cell stack 1 in the steady state are the current-voltage (IV) characteristics of the fuel cell stack 1. For this reason, the internal impedance Z of the fuel cell stack 1 in the steady state can be obtained by obtaining the slope ( ⁇ V / ⁇ I) of the IV characteristic of the fuel cell stack 1.
  • the electrolyte membrane resistance Rm is obtained by measuring the HFR of the fuel cell stack 1 by the alternating current of the electrolyte membrane response frequency. Therefore, if the anode reaction resistance Ra can be obtained, the cathode reaction resistance Rc can be derived as shown in the following equation (5).
  • FIG. 4B is a diagram showing a current path for deriving the anode electrode reaction resistance Ra in the equivalent circuit shown in FIG. 4A.
  • the frequency band that forms the current path as shown in FIG. 4B is hereinafter referred to as “anode pole response frequency band”.
  • the anode pole response frequency band is, for example, a frequency range from several tens Hz to several hundreds Hz.
  • the internal impedance Z measured by the frequency in the anode pole response frequency band is expressed by the following equation (6).
  • This internal impedance Z is the above-mentioned low frequency impedance LFI.
  • the second term and the third term on the right side of Equation (7) are the intercept a.
  • the intercept a is expressed as the following formula (8).
  • the intercept a is calculated based on the real parts Zr of the plurality of LFIs measured at the frequency of at least two points in the anode pole response frequency band. For example, in the coordinate space in which the horizontal axis is the square of the angular frequency ⁇ 2 and the vertical axis is the reciprocal (1 / Zr) of the real part of the LFI, the measurement was performed using the two frequencies f1 and f2 of the anode pole response frequency band. Plot the real part Zr of LFI (f1) and the real part Zr of LFI (f2). Then, by calculating the point where the straight line connecting the real part Zr of LFI (f1) and the real part Zr of LFI (f2) intersects the vertical axis, the intercept a is obtained.
  • the anode electrode reaction resistance Ra can be obtained as shown in the following formula (9).
  • the LFI of the fuel cell stack 1 is measured at the frequency of at least two points in the anode pole response frequency band, and the intercept a is obtained based on the measured real parts of the at least two points of the LFI.
  • the anode electrode reaction resistance Ra is obtained by substituting the values of the intercept a, the real part Zr of the LFI, and the electrolyte membrane resistance Rm into the equation (9).
  • the cathode electrode reaction The resistance Rc can be obtained.
  • FIG. 5 is a block diagram showing an example of a functional configuration for calculating the cathode electrode reaction resistance Rc in the gas supply state detection unit 220.
  • the gas supply state detection unit 220 includes a stack internal resistance calculation unit 224, an electrolyte membrane resistance setting unit 225, an anode electrode reaction resistance calculation unit 226, and a cathode electrode reaction resistance calculation unit 227.
  • the stack internal resistance calculator 224 calculates the overall resistance component including the anode reaction resistance Ra, the electrolyte membrane resistance Rm, and the cathode reaction resistance Rc of the fuel cell stack 1.
  • the IV characteristic of the fuel cell stack 1 is held in the stack internal resistance calculation unit 224.
  • the IV characteristics of the fuel cell stack 1 are predetermined.
  • the stack internal resistance calculator 224 calculates the slope ( ⁇ V / ⁇ I) of the IV characteristic of the fuel cell stack 1 as the overall resistance component.
  • the IV characteristics of the fuel cell stack 1 vary depending on the stack temperature. Therefore, the IV characteristics of the fuel cell stack 1 may be set in the stack internal resistance calculation unit 224 for each stack temperature. In this case, when the stack internal resistance calculation unit 224 acquires the stack temperature obtained by using the stack inlet water temperature sensor 46 and the stack outlet water temperature sensor 47, the stack internal resistance calculation unit 224 refers to the IV characteristic specified by the stack temperature and the inclination thereof. Is calculated. Alternatively, the stack output current may be changed within a predetermined range, and the IV characteristics of the fuel cell stack 1 may be estimated based on the stack output current and the stack output voltage.
  • the electrolyte membrane resistance setting unit 225 sets the measurement HFR from the impedance measuring device 6 as the electrolyte membrane resistance Rm.
  • the anode electrode reaction resistance calculation unit 226 outputs a command for switching the frequency of the alternating current supplied from the impedance measuring device 6 to the fuel cell stack 1 from the electrolyte membrane response frequency band to the anode electrode response frequency band to the impedance measuring device 6. .
  • the anode reaction resistance calculation unit 226 was measured from the impedance measurement device 6 by LFI (f1) measured by the alternating current of the first frequency f1 in the anode response frequency band and the alternating current of the second frequency f2.
  • LFI (f2) is acquired. Note that LFI (f1) and LFI (f2) include values of the real part Zr and the imaginary part Zx, respectively.
  • the anode electrode reaction resistance calculation unit 226 calculates the intercept a shown in Expression (8) based on the real part Zr of LFI (f1) and the real part Zr of LFI (f2).
  • the anode reaction resistance calculator 226 calculates the anode reaction resistance Ra using the values of the intercept a, the real part Zr of the LFI, and the electrolyte membrane resistance Rm, as shown in Expression (9).
  • the anode reaction resistance calculator 226 outputs the anode reaction resistance Ra to the cathode reaction resistance calculator 227.
  • the cathode electrode reaction resistance calculation unit 227 calculates the cathode electrode reaction resistance Rc based on the anode electrode reaction resistance Ra, the resistance component ( ⁇ V / ⁇ I) of the entire fuel cell stack 1, and the electrolyte membrane resistance Rm.
  • the cathode reaction resistance calculator 227 adds the value obtained by adding the anode reaction resistance Ra and the electrolyte membrane resistance Rm to the resistance component ( ⁇ V / ⁇ I of the entire fuel cell stack 1 as shown in Expression (5). ) To calculate the cathode reaction resistance Rc.
  • the cathode electrode reaction resistance calculation unit 227 outputs the cathode electrode reaction resistance Rc to the transient gas flow rate reduction width limit unit 320 and the gas deficiency determination unit 330 as the third parameter indicating the degree of oxygen deficiency.
  • the anode reaction resistance calculation unit 226 has described an example in which the intercept a is calculated based on the LFI at two different frequencies. However, the anode reaction resistance calculation unit 226 has three or more frequencies in the anode response frequency band. The intercept a may be calculated based on the LFI.
  • FIG. 6 is a block diagram illustrating an example of a functional configuration of the gas flow rate F / B control unit 301.
  • the gas flow rate F / B control unit 301 controls the cathode gas supply flow rate so that the electrolyte membrane of the fuel cell stack 1 is transitioned to a wet state at an early stage by using overshoot associated with feedback control.
  • the gas flow rate F / B control unit 301 includes a target HFR calculator 311, a subtractor 312, a proportional unit 313, an adder 314, a delay unit 315, an integrator 316, and an adder 317.
  • the target HFR calculator 311 calculates a target HFR in order to control the wet state of the electrolyte membrane in the fuel cell stack 1 to a target state according to the operating state of the fuel cell stack 1.
  • a film wetting control map showing the relationship between the stack target current and the target HFR is recorded in advance in the target HFR calculator 311.
  • the film wetting control map will be described in detail with reference to FIG.
  • the target HFR calculator 311 acquires the stack target current calculated based on the required power of the load 5
  • the target HFR calculator 311 refers to the film wetting control map and calculates the target HFR related to the stack target current.
  • the target HFR calculator 311 outputs the target HFR to the subtracter 312.
  • the target HFR calculator 311 may calculate a target HFR based on the stack target current using a predetermined calculation formula.
  • the target HFR calculator 311 may calculate the target HFR based on the stack output current output from the current sensor 51 instead of the stack target current.
  • the subtractor 312 calculates a deviation between the target HFR and the measured HFR by subtracting the measured HFR from the film wet state detection unit 210 from the target HFR. Then, the subtracter 312 outputs the calculated deviation to the proportional device 313 and the adder 314.
  • the proportional device 313 multiplies the deviation output from the subtractor 312 by a proportional gain Gp for feedback control, and outputs the multiplied value to the adder 317.
  • the proportional gain Gp is appropriately determined by experimental data or the like.
  • the adder 314 adds the deviation output from the subtractor 312 in the current cycle to the integrated value obtained by integrating the previous (past) deviations for a predetermined period, for example, 20 cycles from the previous cycle. Then, the integrated value of the deviation of each cycle is newly calculated. Adder 314 outputs the integrated value to delay unit 315 and integrator 316.
  • the delay unit 315 holds the current integrated value output from the adder 314 and outputs this integrated value to the adder 314 in the next cycle. Thereby, each deviation of a predetermined period is integrated.
  • the integrator 316 multiplies the integrated value output from the adder 314 by an integral gain Gi for feedback control, and outputs the multiplied value to the adder 317.
  • the integral gain Gi is appropriately determined by experimental data or the like.
  • the adder 317 adds the value output from the proportional device 313 and the value output from the integrator 316, and outputs the added value as the wet requested flow rate Qr_w of the cathode gas.
  • the gas flow rate F / B control unit 301 feedback-controls the supply flow rate of the cathode gas supplied to the fuel cell stack 1 using the HFR correlated with the wet state of the electrolyte membrane.
  • FIG. 7 is a conceptual diagram showing an example of a film wetting control map recorded in the target HFR calculator 311.
  • the horizontal axis represents the stack target current, and the output power of the fuel cell stack 1 increases as the stack target current increases.
  • the vertical axis is the target HFR. The larger the target HFR is, the more the operation for drying the electrolyte membrane of the fuel cell stack 1 is promoted, and the smaller the target HFR is, the more the operation for moistening the electrolyte membrane is promoted.
  • the flow of cathode gas or anode gas is caused by liquid water staying in the cathode gas flow path or cathode electrode in the fuel cell stack 1 or liquid water staying in the anode gas flow path or anode electrode.
  • the target HFR is set so as not to be disturbed.
  • the target HFR decreases as the stack target current increases.
  • the reason for setting in this way is that the smaller the supply flow rate of the cathode gas supplied to the fuel cell stack 1, the more easily the cathode gas flow is hindered by the liquid water staying in the cathode gas flow path. For this reason, the target HFR is set higher than in the normal operation in the low load operation state where the required power of the load 5 is low.
  • the target HFR in the large current range is set to a constant value that is smaller than the target HFR in the small current range.
  • FIG. 8 is a block diagram illustrating an example of a detailed configuration of the transient gas flow rate reduction width limiting unit 320 in the priority control unit 302.
  • the transient gas flow rate reduction width restriction unit 320 includes an oxygen deficiency prevention flow rate calculation unit 321 and a flow rate restriction unit 322.
  • the oxygen deficiency prevention flow rate calculation unit 321 calculates a cathode gas supply flow rate (hereinafter referred to as “oxygen deficiency prevention flow rate”) Qs for preventing the fuel cell from being deficient based on the output current of the fuel cell stack 1. To do.
  • oxygen deficiency prevention flow rate a cathode gas supply flow rate
  • the oxygen deficiency prevention flow rate Qs is a cathode gas flow rate that is at least required for power generation of the fuel cell stack 1.
  • the oxygen deficiency prevention flow rate Qs is determined in consideration of variations in the flow rate of gas distributed to each fuel cell of the fuel cell stack 1 and variations in gas transport resistance of each fuel cell.
  • an oxygen deficiency prevention flow map showing the relationship between the output current of the fuel cell stack 1 and the oxygen deficiency prevention flow rate Qs of the cathode gas is recorded in the oxygen deficiency prevention flow rate calculation unit 321 in advance.
  • the oxygen deficiency prevention flow rate Qs increases gradually as the stack output current Is increases.
  • the oxygen deficiency prevention flow rate calculation unit 321 calculates the oxygen deficiency prevention flow rate Qs related to the stack output current Is with reference to the oxygen deficiency prevention control map.
  • the oxygen deficiency prevention flow rate calculation unit 321 outputs the oxygen deficiency prevention flow rate Qs to the flow rate restriction unit 332.
  • the flow restriction unit 322 restricts the wet request flow rate Qr_w from the gas flow rate F / B control unit 301 using the oxygen deficiency prevention flow rate Qs.
  • the flow rate limiting unit 322 outputs the larger one of the required wet flow rate Qr_w and the oxygen deficiency prevention flow rate Qs to the target flow rate setting unit 340 as the lower limit flow rate Qlim of the cathode gas.
  • the target flow rate setting unit 340 switches the cathode gas target flow rate Qt from the required wet flow rate Qr_w to the lower limit flow rate Qlim according to the setting state of the oxygen deficiency flag by the gas deficiency determination unit 330.
  • the target flow rate setting unit 340 sets the wet request flow rate Qr_w to the cathode gas target flow rate Qt.
  • the target flow rate setting unit 340 switches the cathode gas target flow rate Qt to the oxygen deficiency prevention flow rate Qs.
  • the target flow rate setting unit 340 prevents the lower limit flow rate Qlim of the cathode gas from lacking oxygen only when the required wet flow rate Qr_w is lower than the oxygen deficiency prevention flow rate Qp.
  • the flow rate is limited to Qp.
  • FIG. 9 is a flowchart showing an example of a control method for controlling the fuel cell system 100 in the present embodiment. This control method is repeatedly executed at predetermined time intervals.
  • step S1 the controller 200 detects the operating state of the fuel cell stack 1. Specifically, the controller 200 detects the HFR of the fuel cell stack 1 using the impedance measuring device 6, detects the output voltage of the fuel cell stack 1 using the voltage sensor 52, and determines the rotational speed of the compressor 32 and the cathode. The opening degree of the pressure regulating valve 34 is detected.
  • step S2 the controller 200 estimates the wet state of the electrolyte membrane based on the detection signal.
  • the controller 200 acquires the measured HFR from the impedance measuring device 6 as wet state information indicating the wet state of the electrolyte membrane.
  • step S3 the controller 200 feedback-controls the supply flow rate of the cathode gas supplied to the fuel cell stack 1 based on the wet state of the electrolyte membrane. For example, as shown in FIG. 6, the controller 200 calculates the required wet flow rate Qr_w of the cathode gas so that the deviation between the measured HFR of the fuel cell stack 1 and the target HFR converges to zero, and calculates the required wet flow rate Qr_w.
  • the cathode gas target flow rate Qt is set.
  • Step S3 corresponds to a control step of controlling the supply amount of the cathode gas supplied to the fuel cell stack 1 based on the signal output from the membrane wet state detection unit 210.
  • step S4 the controller 200 acquires the stack output voltage Vs from the voltage sensor 52 as the first parameter indicating the degree of oxygen deficiency of the fuel cell.
  • step S5 the controller 200 executes a process of calculating the surplus amount of the cathode gas supply flow rate as the second parameter indicating the degree of oxygen deficiency of the fuel cell. Details of this processing will be described later with reference to FIG.
  • step S6 the controller 200 executes a process of calculating the cathode reaction resistance as the third parameter indicating the degree of oxygen deficiency of the fuel cell. Details of this processing will be described later with reference to FIG.
  • step S7 the controller 200 executes a fuel cell oxygen deficiency prediction process based on the three parameters calculated by the processes from step S4 to step S6. That is, the controller 200 determines whether or not the supply flow rate of the cathode gas supplied to the fuel cell stack 1 is insufficient. Details of the oxygen deficiency prediction process will be described later with reference to FIG.
  • step S8 the controller 200 confirms whether or not it is determined by the oxygen deficiency prediction process in step S7 that the fuel cell can be in an oxygen deficient state. If it is not determined that the fuel cell can be in an oxygen deficient state, the controller 200 proceeds to the process of step S10.
  • step S9 when it is determined that the fuel cell can be in an oxygen deficient state, the controller 200 executes a process for preventing the cathode gas supply flow rate from being excessively lowered. That is, the controller 200 calculates the cathode gas deficiency prevention flow rate Qp and switches the cathode gas target flow rate Qt from the wet request flow rate Qr_w to the oxygen deficiency prevention flow rate Qp. Details of the process for preventing the cathode gas supply flow rate from being excessively lowered will be described later with reference to FIG.
  • step S9 when it is determined by the signal from the gas supply state detection unit 220 that the supply amount of the cathode gas is insufficient, the gas supply state detection unit has priority over the signal from the film wet state detection unit 210. This corresponds to a priority control step of controlling the power generation state of the fuel cell stack 1 by controlling the supply amount of the cathode gas by a signal from 220.
  • step S10 the controller 200 controls the rotation speed of the compressor 32 and the opening of the cathode pressure regulating valve 34 based on the cathode gas target flow rate Qt.
  • FIG. 10 is a flowchart showing an example of a cathode gas surplus amount calculation process executed in step S5.
  • step S51 the controller 200 acquires the rotation speed of the compressor 32 and the opening of the cathode pressure regulating valve 34.
  • the controller 200 acquires a detection signal from a rotation speed sensor provided in the compressor 32 and a detection signal from an opening degree sensor provided in the cathode pressure regulating valve 34.
  • step S52 the controller 200 identifies the pressure loss characteristic of the cathode gas supply passage 31 based on the opening degree of the cathode pressure regulating valve 34.
  • the pressure loss characteristic of the cathode gas supply passage 31 indicates the relationship between the discharge flow rate of the cathode gas discharged from the compressor 32 and the pressure loss of the cathode gas supply passage 31 from the compressor 32 to the fuel cell stack 1.
  • the pressure loss characteristic of the cathode gas supply passage 31 is stored in advance for each opening degree of the cathode pressure regulating valve 34 in the supply passage pressure loss characteristic extraction unit 2211 of the controller 200.
  • the supply passage pressure loss characteristic extraction unit 2211 acquires the detection value from the opening degree sensor of the cathode pressure regulating valve 34, the supply passage pressure loss characteristic extraction unit 2211 extracts the pressure loss characteristic specified by the detection value.
  • step S53 the controller 200 specifies the discharge flow rate characteristic of the compressor 32 based on the rotation speed of the compressor 32.
  • the discharge flow rate characteristic of the compressor 32 here indicates the relationship between the cathode gas supply passage 31 from the compressor 32 to the fuel cell stack 1 and the discharge flow rate of the cathode gas discharged from the compressor 32.
  • the discharge flow rate characteristic of the compressor 32 is stored in advance for each rotation speed of the compressor 32 in the compressor operation characteristic extraction unit 2212 of the controller 200.
  • the compressor operation characteristic extraction unit 2212 acquires a detection value from the rotation speed sensor of the compressor 32
  • the compressor operation characteristic extraction unit 2212 extracts a discharge flow rate characteristic that is characterized by the detection value.
  • step S54 the intersection extraction unit 2213 of the controller 200 extracts an intersection when the discharge flow rate characteristic extracted by the process of step S53 and the pressure loss characteristic extracted by the process of step S54 are overlapped with each other. Then, the intersection extraction unit 2213 sets the discharge flow rate specified by the intersection as the cathode gas supply flow rate Qc.
  • step S55 the required load flow rate calculation unit 222 of the controller 200 calculates the required load flow rate Qr_l of the cathode gas based on the stack target current.
  • the required load flow rate Qr_l is a cathode gas supply flow rate that is at least necessary for generating the required power of the load 5 by the fuel cell stack 1.
  • step S56 the oxygen deficiency calculating unit 223 of the controller 200 calculates the surplus amount ⁇ Q of the cathode gas supply flow rate by subtracting the load request flow rate Qr_l from the estimated supply flow rate Qc of the cathode gas.
  • step S6 is executed.
  • FIG. 11 is a flowchart showing an example of the cathode reaction resistance calculation process executed in step S6 shown in FIG.
  • step S61 the gas supply state detection unit 220 of the controller 200 calculates the resistance component of the fuel cell stack 1 in the steady state based on the IV characteristics of the fuel cell stack 1.
  • the gas supply state detection unit 220 divides the voltage width ⁇ V per unit current ⁇ I in the IV characteristics of the fuel cell stack 1 by the unit current ⁇ I, so that the slope of the IV characteristics of the fuel cell stack 1 ( ⁇ V / ⁇ I) is calculated as a resistance component.
  • step S62 the gas supply state detection unit 220 sets the measurement HFR output from the impedance measurement device 6 as the electrolyte membrane resistance Rm.
  • step S63 the gas supply state detection unit 220 commands the impedance measurement device 6 to measure the LFI of the fuel cell stack 1 at two frequencies in the anode pole response frequency band lower than the measurement frequency of HFR. Then, the gas supply state detection unit 220 acquires the LFI measured at two frequencies in the anode pole response frequency band from the impedance measurement device 6.
  • step S64 the gas supply state detection unit 220 calculates the anode electrode reaction resistance Ra based on the two LFIs in the anode electrode response frequency band. As described with reference to FIG. 4B, the gas supply state detection unit 220 calculates the intercept a of the equation (8) based on the two real parts of the LFI in the anode pole response frequency band, and the intercept a and the electrolyte membrane resistance Rm.
  • the anode reaction resistance Ra is calculated by substituting the values of LFI and the real part Zr of LFI into equation (9).
  • step S65 the gas supply state detection unit 220 uses the resistance component ( ⁇ V / ⁇ I) of the fuel cell stack 1, the electrolyte membrane resistance Rm, and the anode electrode reaction resistance Ra, as shown in the equation (5), to the cathode electrode reaction resistance. Rc is calculated. Then, the cathode electrode reaction resistance calculation process ends. Thereafter, returning to the process of step S6 shown in FIG. 9, the gas supply state detection unit 220 outputs the cathode reaction resistance Rc as the third parameter indicating the degree of oxygen deficiency, and proceeds to the process of step S7.
  • FIG. 12 is a flowchart showing an example of the fuel cell oxygen deficiency prediction process executed in step S7 shown in FIG.
  • step S71 the gas deficiency determination unit 330 of the controller 200 determines whether or not the stack output voltage Vs is larger than the voltage threshold Th_v.
  • the voltage threshold Th_v is an oxygen deficiency threshold determined for determining whether or not the output voltage of the fuel cell stack 1 has decreased due to oxygen deficiency in the fuel cell.
  • the voltage threshold Th_v is determined in advance by experimental data or the like, and is set to several tens of volts (volts), for example.
  • the voltage threshold Th_v may be changed based on the stack target current, for example.
  • the gas deficiency determination unit 330 determines that the fuel cell is in an oxygen deficient state, and proceeds to the process of step S75. On the other hand, when the stack output voltage Vs is equal to or lower than the voltage threshold Th_v, the gas deficiency determination unit 330 determines that the fuel cell does not become in an oxygen deficient state, and proceeds to the process of step S72.
  • step S72 the gas deficiency determination unit 330 determines whether or not the excess amount ⁇ Q of the cathode gas supply flow rate is larger than the gas flow rate threshold Th_q.
  • the gas flow rate threshold Th_q is set to zero, for example. Note that the gas flow rate threshold Th_q may be set to a predetermined value larger than zero in consideration of a determination error or the like, or may be changed to a large value according to the increase amount of the stack target current per unit time. It may be a thing.
  • the gas deficiency determination unit 330 determines that the fuel cell is in an oxygen deficient state and proceeds to the process of step S75. On the other hand, if the surplus amount ⁇ Q is equal to or less than the gas flow rate threshold Th_q, the gas deficiency determination unit 330 determines that the fuel cell is not in an oxygen deficient state, and proceeds to the process of step S73.
  • step S73 the gas deficiency determination unit 330 determines whether or not the cathode reaction resistance Rc is smaller than the reaction resistance threshold Th_r.
  • the reaction resistance threshold Th_r is an oxygen deficiency threshold determined to determine whether or not the cathode reaction resistance of the fuel cell stack 1 has increased due to oxygen deficiency in the fuel cell.
  • the reaction resistance threshold Th_r is predetermined by experimental data or the like, and is set to several tens of ohms (ohms), for example.
  • the gas deficiency determination unit 330 determines that the fuel cell is in an oxygen deficient state, and proceeds to the process of step S75. On the other hand, if the cathode reaction resistance Rc is equal to or greater than the reaction resistance threshold Th_r, the gas deficiency determination unit 330 determines that the fuel cell is not in an oxygen deficient state, and proceeds to the process of step S74.
  • step S74 the gas deficiency determination unit 330 determines that the acid output is higher when the stack output voltage Vs is larger than the voltage threshold Th_v, the surplus amount ⁇ Q is larger than the gas flow threshold Th_q, and the cathode reaction resistance Rc is smaller than the reaction resistance threshold Th_r. Set the missing flag to OFF. That is, the gas deficiency determination unit 330 sets the oxygen deficiency flag to OFF when determining that the fuel cell is not in an oxygen deficiency state.
  • step S75 the gas deficiency determination unit 330 determines that the stack output voltage Vs is equal to or less than the voltage threshold Th_v, the surplus amount ⁇ Q is equal to or less than the gas flow rate threshold Th_q, or the cathode reaction resistance Rc is equal to or greater than the reaction resistance threshold Th_r.
  • the oxygen deficiency flag is set to ON. That is, the gas deficiency determination unit 330 sets the oxygen deficiency flag to ON when determining that the fuel cell is in an oxygen deficiency state. Thereby, the process for preventing the cathode gas supply flow rate from being excessively lowered in step S9 shown in FIG. 9 is executed.
  • step S74 or S75 the fuel cell oxygen deficiency prediction process is completed, and the process returns to the process of step S7 shown in FIG. 9, and the gas deficiency determination unit 330 uses the oxygen deficiency flag setting information as the target flow rate. It outputs to the setting part 340 and the process of step S8 is performed.
  • FIG. 13 is a flowchart showing an example of the process for preventing the cathode gas supply flow rate from being excessively lowered, which is executed in step S9.
  • step S91 the controller 200 acquires the stack output current Is from the current sensor 51.
  • step S92 the transient gas flow rate reduction width limiting unit 320 of the controller 200 obtains the stack output current Is, and based on the stack output current Is, sets the oxygen deficiency prevention flow rate Qp for preventing the fuel cell from lacking oxygen. calculate.
  • step S93 the target flow rate setting unit 340 of the controller 200 determines whether or not the required wet flow rate Qr_w calculated in step S3 of FIG. 9 is greater than the oxygen deficiency prevention flow rate Qp.
  • step S94 the target flow rate setting unit 340 sets the required wet flow rate Qr_w to the cathode gas target flow rate Qt when the required wet flow rate Qr_w is larger than the oxygen deficiency prevention flow rate Qp.
  • step S95 the target flow rate setting unit 340 sets the oxygen deficiency prevention flow rate Qp to the cathode gas target flow rate Qt when the required wet flow rate Qr_w is equal to or less than the oxygen deficiency prevention flow rate Qp. Thereby, it can prevent that each fuel cell laminated
  • step S94 or S95 When the process in step S94 or S95 is completed, the process for preventing the cathode gas supply flow rate from being excessively lowered is completed. Thereafter, the process returns to the process of step S9 shown in FIG. 9, the target flow rate setting unit 340 outputs the cathode gas target flow rate Qt to the gas supply system command unit 350, and the process of step S10 is executed.
  • FIG. 14 is a time chart showing a change in the cathode gas supply flow rate when the wet control for moistening the electrolyte membrane in the fuel cell stack 1 is executed.
  • the supply flow rate of the cathode gas is lowered so that the stack output current Is becomes smaller than the predetermined current value Ip and the electrolyte membrane shifts to a wet state (Wet).
  • Wet wet state
  • the wetting control for moistening the electrolyte membrane is also referred to as “WET operation”.
  • FIG. 14A is a diagram showing a change in the actual wet state when the target wet state, which is the target wet state of the electrolyte membrane, is lowered.
  • the target wet state is indicated by a broken line
  • the actual wet state is indicated by a solid line.
  • FIG. 14 (b) is a diagram showing a change in the supply flow rate of the cathode gas supplied to the fuel cell stack 1 by the wetting control shown in FIG. 14 (a).
  • the cathode gas supply flow rate is indicated by a solid line
  • the required wetness flow rate Qr_w is indicated by a broken line
  • the oxygen deficiency prevention flow rate Qp is indicated by a dotted line.
  • the horizontal axis of Fig.14 (a) and FIG.14 (b) is a mutually common time axis.
  • the target wet state is sharply lowered so that the required power of the load 5 is increased and the electrolyte membrane becomes wet. .
  • the deviation between the measured HFR and the target HFR becomes smaller than zero, and the wet required flow rate Qr_w output from the gas flow rate F / B control unit 301 decreases accordingly, and FIG. As shown in b), the cathode gas supply flow rate decreases.
  • the actual wet state is moistened so as to follow the target wet state as shown by the solid line in FIG. Transition to the state.
  • the cathode gas supply flow rate is determined from the supply flow rate required to maintain the target wet state in order to quickly transition the actual wet state to the target wet state. Further lowered. That is, the controller 200 causes the cathode gas supply flow rate to overshoot (undershoot) when the target wet state is switched from the dry-side state to the wet-side state.
  • the excess amount ⁇ Q of the cathode gas supply flow rate becomes smaller than the gas flow rate threshold Th_q, and the oxygen deficiency determination unit 330 sets the oxygen deficiency flag to ON.
  • the target flow rate setting unit 340 switches the cathode gas target flow rate to the output value of the transient gas flow rate reduction width limiting unit 320.
  • the surplus amount ⁇ Q of the cathode gas supply flow rate becomes larger than the gas flow rate threshold Th_q, so that the oxygen deficiency determination unit 330 sets the oxygen deficiency flag to OFF. Accordingly, the target flow rate setting unit 340 switches the cathode gas target flow rate Qt to the required wet flow rate Qr_w.
  • the gas flow rate F / B control unit 301 feedback-controls the cathode gas supply flow rate by feeding back the value obtained by detecting the wet state of the electrolyte membrane. Thereby, when the wet control is executed, the cathode gas supply flow rate can be further reduced from the steady state flow rate, and the wet state of the electrolyte membrane can be shifted to the target wet state at an early stage.
  • the cathode gas supply flow rate is determined from the required wet flow rate Qr_w to prevent oxygen deficiency.
  • the flow rate is switched to Qp.
  • the amount of decrease in the cathode gas supply flow rate and the distribution to each fuel cell are compared with the case where feedback control is performed based on the required power of the load 5.
  • the allowance considering the flow rate error can be reduced. For this reason, since it is less likely that the cathode gas supply flow rate is excessively increased, an increase in power consumption of the compressor 32 can be reduced.
  • the wet state of each electrolyte membrane in the fuel cell stack 1 can be shifted to the target wet state at an early stage, and the power consumption of the fuel cell system 100 can be reduced.
  • the fuel cell system 100 includes an anode gas supply / discharge device 2 that supplies an anode gas to the electrolyte membrane of the fuel cell in the fuel cell stack 1, and a cathode gas that is supplied to the electrolyte membrane. And a cathode gas supply / discharge device 3.
  • the fuel cell system 100 includes a power generation control unit 300 of a controller 200 that controls power generation of the fuel cell by controlling supply of cathode gas by the cathode gas supply / discharge device 3 and supply of anode gas by the anode gas supply / discharge device 2. including.
  • the fuel cell system 100 includes an impedance measuring device 6 and a membrane wet state detection unit 210 as wet state means for detecting the wet state of the electrolyte membrane.
  • the voltage sensor 52, the impedance measuring device 6, and the gas supply state detection unit 220 are provided as supply state detection means for detecting the supply state of the cathode gas supplied to the electrolyte membrane.
  • the power generation control unit 300 includes a priority control unit 302, and controls the amount of cathode gas supplied to the electrolyte membrane based on the signal output from the membrane wet state detection unit 210, thereby generating power from the fuel cell. Control the state.
  • a priority control unit 302 controls the amount of cathode gas supplied to the electrolyte membrane based on the signal output from the membrane wet state detection unit 210, thereby generating power from the fuel cell. Control the state.
  • the target wet state greatly decreases with a change in the required power of the load 5 and the like, the supply amount of the cathode gas overshoots, so that the wet state of the electrolyte membrane is quickly changed to the target wet state. Can be migrated.
  • the cathode gas supply amount is controlled based on the required power of the load 5
  • an overshoot of the cathode gas supply amount is avoided in order to avoid a decrease in power generation efficiency due to lack of oxygen in the fuel cell.
  • an error in the flow rate distributed to each fuel cell, an error in the gas transport resistance of the gas diffusion layer, and the like are considered.
  • the supply amount of the cathode gas is set to be larger than the supply amount necessary for the power generation of the fuel cell stack 1, so that the power consumption of the compressor 32 steadily increases. .
  • the cathode gas supply amount is controlled based on the signal from the membrane wet state detection unit 210. Therefore, the error in the flow rate distributed to each fuel cell and the gas transport resistance are controlled. There is no fear that the power generation efficiency of the fuel cell will be reduced due to the fact that no error is taken into account. For this reason, since it is not necessary to take a large allowance, the power consumption of the compressor 32 can be reduced.
  • the priority control unit 302 When it is determined by the signal from the gas supply state detection unit 220 that the supply amount of the cathode gas is insufficient, the priority control unit 302 has priority over the signal from the film wet state detection unit 210 and the gas supply state detection unit The power generation state is controlled by controlling the supply amount of the cathode gas by a signal from 220.
  • the cathode gas supply amount is maintained at the minimum supply amount necessary for power generation of the fuel cell stack 1. Therefore, it is possible to suppress a decrease in power generation efficiency due to the lack of oxygen in the fuel cell.
  • the priority control unit 302 determines that the supply amount of the cathode gas is insufficient, and then the signal from the gas supply state detection unit 220 is higher than the predetermined threshold value so that the supply amount is not insufficient. Until the determination is made, the supply amount of the cathode gas is controlled based on the output power of the fuel cell stack 1.
  • the gas supply amount necessary for the power generation of the fuel cell is ensured, so that an oxygen deficiency state of the fuel cell can be avoided, and the fuel cell A decrease in power generation efficiency can be prevented.
  • the gas flow rate F / B control unit 301 of the power generation control unit 300 determines the deviation between the signal (measurement HFR) from the film wet state detection unit 210 and the target value (target HFR) of the wet state. Based on this, a required wet flow rate for controlling the supply amount of the cathode gas is calculated.
  • the priority control unit 302 determines that the required wet flow rate is lower than the supply amount based on the output power of the fuel cell stack 1 (oxygen deficiency prevention flow rate). Sets the supply amount of the cathode gas to the supply amount based on the output power of the fuel cell stack 1. Thereby, it is possible to prevent the supply amount of the cathode gas from changing sharply.
  • the gas supply state detection unit 220 is based on at least one parameter among the voltage of the fuel cell stack 1, the control amount of the cathode gas supply / discharge device 3, and the internal impedance of the fuel cell stack 1.
  • the supply state of the cathode gas supplied to the fuel cell stack 1 is detected.
  • the supply amount of the cathode gas supplied to the fuel cell stack 1 becomes in a state where the supply amount necessary for the power generation of the fuel cell stack 1 is insufficient, that is, the fuel cell is in an oxygen deficient state in advance. Can be predicted.
  • the gas supply state detection unit 220 increases the output signal output to the priority control unit 302 as the output voltage Vs of the fuel cell stack 1 detected by the voltage sensor 52 becomes lower than a predetermined value.
  • the gas supply state detection unit 220 calculates the surplus amount ⁇ Q of the cathode gas supply flow rate based on the rotation speed of the compressor 32 and the opening of the cathode pressure regulating valve 34 which are control amounts of the cathode gas supply / discharge device 3.
  • the output signal may be increased as the surplus amount ⁇ Q decreases.
  • the gas supply state detection unit 220 calculates the cathode reaction resistance Rc based on the internal impedance of the fuel cell stack 1 measured at a plurality of different frequencies, and the output signal increases as the cathode reaction resistance Rc increases. You may make it do.
  • the priority control unit 302 can more accurately determine the oxygen deficiency state of the fuel cell by combining a plurality of output signals indicating the above-mentioned deficiency. For example, the priority control unit 302 may estimate the oxygen deficiency state of the fuel cell using the output voltage Vs of the fuel cell stack 1 and the excess amount ⁇ Q of the cathode gas supply flow rate, and the output voltage Vs of the fuel cell stack 1 may be estimated. And the cathode reaction resistance Rc may be used to estimate the oxygen deficiency state of the fuel cell. Alternatively, the priority control unit 302 may estimate the oxygen deficiency state of the fuel cell using the cathode reaction resistance Rc and the excess amount ⁇ Q of the cathode gas supply flow rate.
  • the F / B gain of the gas flow rate F / B control unit 301 that is, the proportional gain Gp and the integral gain Gi are fixed to large values so that the cathode gas supply flow rate overshoots. Therefore, when the cathode gas target flow rate is switched from the oxygen deficiency prevention flow rate to the wet request flow rate after avoiding oxygen deficiency in the fuel cell, there is a concern that the cathode gas supply flow rate may fluctuate.
  • the transient gas flow rate reduction width limiting unit 320 is based on the signal indicating the degree of oxygen deficiency from the gas supply state detection unit 220 so that the reduction rate of the cathode gas supply flow rate is reduced.
  • the transient gas flow rate reduction width restriction unit 320 changes at least one of the proportional gain Gp and the integral gain Gi used for feedback control when a signal indicating the degree of oxygen deficiency exceeds a predetermined threshold.
  • FIG. 15 is a block diagram showing an example of a functional configuration of the transient gas flow rate reduction width limiting unit 320 according to the second embodiment of the present invention.
  • the transient gas flow rate reduction width restriction unit 320 changes the proportional gain Gp
  • the transient gas flow rate reduction width restriction unit 320 changes the integral gain Gi
  • the configuration other than the transient gas flow rate reduction width limiting unit 320 is the same as that of the fuel cell system 100 in the first embodiment. Therefore, in the following, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
  • the transient gas flow rate reduction width limitation unit 320 includes a first proportional gain calculation unit 323A, a second proportional gain calculation unit 323B, A third proportional gain calculation unit 323C and a proportional gain setting unit 324 are included.
  • FIG. 15 only the configuration other than the oxygen deficiency prevention flow rate calculation unit 321 and the flow rate restriction unit 322 is illustrated.
  • the first proportional gain calculation unit 323A calculates the proportional gain Gp based on the voltage of the fuel cell stack 1, which is a first parameter indicating the degree of oxygen deficiency. For example, the first proportional gain calculation unit 323A decreases the proportional gain Gp because the degree of oxygen deficiency increases as the voltage of the fuel cell stack 1 decreases.
  • a first proportional gain control map indicating the relationship between the stack output voltage and the proportional gain Gp is stored in advance in the first proportional gain calculation unit 323A.
  • the proportional gain is set to the reference value Gp_b within the range of the stack output voltage from the second voltage value v2 to the maximum output voltage value.
  • the reference value Gp_b of the proportional gain is set using experimental data or the like so that when the target HFR decreases, the electrolyte membrane shifts to a wet state at an early stage. That is, the proportional gain reference value Gp_b is set so that the cathode gas supply flow rate overshoots in a transient state where the target HFR decreases.
  • the proportional gain Gp decreases as the stack output voltage Vs decreases.
  • the lower the stack output voltage Vs the smaller the decrease in the cathode gas supply flow rate.
  • the reason why the proportional gain Gp is smoothly changed according to the stack output voltage is to prevent the cathode gas supply flow rate fluctuation that may occur when the proportional gain setting is sharply switched from the reference value Gp_b to the lower limit value. It is.
  • the proportional gain Gp is set to a predetermined lower limit value. Thereby, the overshoot of the cathode gas supply flow rate is suppressed.
  • Such a first proportional gain control map is recorded in the first proportional gain calculation unit 323A.
  • the first proportional gain calculation unit 323A refers to the first proportional gain control map and calculates the proportional gain Gp related to the acquired stack output voltage Vs.
  • the first proportional gain calculation unit 323A outputs the proportional gain Gp to the proportional gain setting unit 324.
  • the second proportional gain calculation unit 323B calculates the proportional gain Gp based on the surplus amount ⁇ Q of the cathode gas supply flow rate that is the second parameter indicating the degree of oxygen deficiency. For example, the second proportional gain calculation unit 323B decreases the proportional gain Gp because the degree of oxygen deficiency increases as the excess amount ⁇ Q decreases.
  • a second proportional gain control map indicating the relationship between the excess amount of the cathode gas supply flow rate and the proportional gain Gp is stored in advance in the second proportional gain calculation unit 323B.
  • the proportional gain Gp is set to the reference value Gp_b while the surplus amount ⁇ Q of the cathode gas supply flow rate is within the range from the second flow rate q2 to the maximum flow rate.
  • the proportional gain reference value Gp_b is the same value as that set in the first proportional gain control map.
  • the proportional gain Gp decreases as the surplus amount ⁇ Q decreases.
  • the smaller the surplus amount ⁇ Q the smaller the decrease in the cathode gas supply flow rate.
  • the reason why the proportional gain Gp is smoothly changed in this way is to prevent a change in the cathode gas supply flow rate that may occur when the setting of the proportional gain Gp is sharply switched from the reference value Gp_b to the lower limit value.
  • the proportional gain Gp is set to a predetermined lower limit value. Thereby, the overshoot of the cathode gas supply flow rate is suppressed.
  • Such a second proportional gain control map is recorded in the second proportional gain calculation unit 323B.
  • the second proportional gain calculation unit 323B acquires the surplus amount ⁇ Q from the oxygen deficiency degree calculation unit 223 of the gas supply state detection unit 220
  • the second proportional gain calculation unit 323B refers to the second proportional gain control map and is related to the acquired surplus amount ⁇ Q.
  • the proportional gain Gp is calculated.
  • the second proportional gain calculation unit 323B outputs the proportional gain Gp to the proportional gain setting unit 324.
  • the third proportional gain calculation unit 323C calculates the proportional gain Gp based on the cathode reaction resistance Rc that is the third parameter indicating the degree of oxygen deficiency. For example, the third proportional gain calculation unit 323C decreases the proportional gain Gp because the degree of oxygen deficiency increases as the cathode reaction resistance Rc increases.
  • a third proportional gain control map indicating the relationship between the cathode reaction resistance and the proportional gain Gp is stored in advance in the third proportional gain calculation unit 323C.
  • the proportional gain Gp is set to the reference value Gp_b within the range where the cathode reaction resistance is from zero to the first resistance value r1.
  • the proportional gain reference value Gp_b is the same value as that set in the first proportional gain control map.
  • the proportional gain Gp decreases as the cathode reaction resistance Rc decreases.
  • the lower the cathode electrode reaction resistance Rc the smaller the decrease in the cathode gas supply flow rate.
  • the reason why the proportional gain Gp is smoothly changed in this way is to prevent a change in the cathode gas supply flow rate that may occur when the setting of the proportional gain Gp is sharply switched from the reference value Gp_b to the lower limit value.
  • the proportional gain Gp is set to a predetermined lower limit value. Thereby, the overshoot of the cathode gas supply flow rate is suppressed.
  • Such a third proportional gain control map is recorded in the third proportional gain calculation unit 323C.
  • the third proportional gain calculation unit 323C acquires the cathode reaction resistance Rc from the gas supply state detection unit 220
  • the third proportional gain calculation unit 323C refers to the third proportional gain control map, and the proportional gain Gp related to the acquired cathode reaction resistance Rc. Is calculated.
  • the third proportional gain calculation unit 323C outputs the proportional gain Gp to the proportional gain setting unit 324.
  • the proportional gain setting unit 324 selects the proportional gain Gp set in the proportional device 313.
  • the proportional gain setting unit 324 sets the smallest value among the three proportional gains output from the first to third proportional gain calculation units 323A to 323C in the proportional device 313.
  • the smallest value among the three output values it is possible to more reliably prevent the lack of oxygen in the fuel cell.
  • FIG. 16 is a block diagram showing an example of a functional configuration for changing the integral gain Gi in the transient gas flow rate reduction width limiting unit 320.
  • the transient gas flow rate reduction width limiting unit 320 includes a first integral gain calculator 325A, a second integral gain calculator 325B, a third integral gain calculator 325C, And a gain setting unit 326.
  • the first to third integral gain calculators 325A to 325C have the same configuration as the first to third proportional gain calculators 323A to 323C, respectively. That is, the first integral gain calculator 325A stores a first integral gain control map, the second integral gain calculator 325B stores a second integral gain control map, and the third integral gain control map 325A stores the second integral gain control map.
  • the calculation unit 325C stores a third integral gain control map.
  • the reference value Gi_b and the lower limit value of the integral gain in the first to third integral gain control maps are set based on experimental data and the like in the same way as the reference value Gp_b and the lower limit value of the proportional gain.
  • the integral gain setting unit 326 selects the integral gain Gi set in the integrator 316.
  • the integral gain setting unit 326 sets the smallest value among the three integral gains output from the first to third integral gain calculation units 325A to 325C in the integrator 316.
  • the proportional gain Gp and the integral gain are set so that the reduction rate of the cathode gas supply flow rate becomes small. Gi is changed. For example, when the stack output voltage Vs is smaller than the first voltage value v1, it is determined that the fuel cell can be deficient, and the proportional gain Gp and the integral gain Gi are set to values smaller than the reference value. . Thereby, when the target HFR is switched to a value smaller than the previous value, the cathode gas supply flow rate can be smoothly reduced.
  • FIG. 17 is a flowchart showing an example of a control method of the fuel cell system 100 in the present embodiment.
  • each processing from steps S11 to S13 is added. Therefore, only each process from step S11 to step S13 is demonstrated here.
  • step S11 the priority control unit 302 determines whether or not a WET operation, which is a wetting control for moistening the electrolyte membrane, is performed after the processing in step S6 is completed. That is, when the WET operation is executed, the priority control unit 302 has a supply amount of the cathode gas supplied to the fuel cell stack 1 that is less than a supply amount that is minimum required for power generation of the fuel cell stack 1. Judging that there is a possibility of.
  • the priority control unit 302 determines that the WET operation is executed when a value obtained by subtracting the current target HFR from the previous target HFR, that is, a reduction amount of the target HFR exceeds a predetermined value.
  • the priority control unit 302 may determine that the WET operation is executed when the value obtained by subtracting the target HFR from the measured HFR exceeds a predetermined value.
  • the priority control unit 302 proceeds to the process of step S12.
  • step S12 the transient gas flow rate reduction width restriction unit 320 of the priority control unit 302 suppresses the reduction range of the cathode gas supply flow rate based on the parameter signal indicating the degree of oxygen deficiency from the gas supply state detection unit 220. Execute.
  • the transient gas flow rate reduction width limiting unit 320 reduces both the proportional gain Gp and the integral gain Gi in the gas flow rate F / B control unit 301 based on three parameters indicating the degree of oxygen deficiency. That is, when it is determined that the WET operation is performed, the priority control unit 302 responds to the signal from the gas supply state detection unit 220 so that the cathode gas supply state approaches the oxygen deficient state. Reduce the amount of supply reduced.
  • Such a cathode gas supply flow rate reduction width suppression process will be described later with reference to FIG.
  • step S8 a process for preventing the cathode gas supply flow rate from being excessively lowered is executed in step S9. That is, when the supply state of the cathode gas reaches a state in which a decrease in the supply amount of the cathode gas cannot be allowed, the priority control unit 302 limits the supply amount of the cathode gas based on the output power of the fuel cell stack 1.
  • step S10 the control method for the fuel cell system 100 is completed.
  • step S11 determines in step S11 that the WET operation is not executed. If the priority control unit 302 determines in step S11 that the WET operation is not executed, the process proceeds to step S13.
  • step S13 the transient gas flow rate reduction width limiting unit 320 sets the proportional gain Gp in the gas flow rate F / B control unit 301 to the reference value Gp_b, and sets the integral gain Gi to the reference value Gi_b. That is, the transient gas flow rate reduction width restriction unit 320 sets the F / B gain set in the gas flow rate F / B control unit 301 to a default value. Thereafter, a series of processing from step S7 to step S10 is executed, and the control method of the fuel cell system 100 is completed.
  • the priority control unit 302 determines whether or not the cathode gas supply flow rate decrease width suppression process is necessary according to whether or not the WET operation is performed. . Therefore, the cathode gas supply flow rate decrease width suppression process is executed only when the WET operation is performed, and the cathode gas supply flow rate decrease width suppression process is not performed when the WET operation is not performed. Processing can be reduced.
  • step S11 is added after the process of step S6, but the process of step S11 may be added between the process of step S4 and the process of step S5.
  • FIG. 18 is a flowchart showing an example of the cathode gas supply flow rate reduction width suppression process executed in step S12 shown in FIG.
  • the first proportional gain calculator 323A calculates the proportional gain Gp based on the stack output voltage Vs. For example, the first proportional gain calculation unit 323A decreases the proportional gain Gp because the degree of oxygen deficiency increases as the stack output voltage Vs decreases.
  • the second proportional gain calculator 323B calculates the proportional gain Gp based on the surplus amount ⁇ Q of the cathode gas supply flow rate. For example, the second proportional gain calculation unit 323B decreases the proportional gain Gp because the degree of oxygen deficiency increases as the excess amount ⁇ Q of the cathode gas supply flow rate decreases.
  • step S123 the third proportional gain calculator 323C calculates the proportional gain Gp based on the cathode electrode reaction resistance Rc. For example, the third proportional gain calculation unit 323C decreases the proportional gain Gp because the degree of oxygen deficiency increases as the cathode reaction resistance Rc increases.
  • step S124 the proportional gain setting unit 324 outputs the smallest value among the three proportional gains Gp calculated in the processes from step S121 to step S123 to the proportional device 313.
  • the closer the fuel cell approaches an oxygen-deficient state the smaller the decrease in the cathode gas supply flow rate.
  • the first integral gain calculator 325A calculates the integral gain Gi based on the stack output voltage Vs. For example, the first integral gain calculation unit 325A decreases the integral gain Gi because the degree of oxygen deficiency increases as the stack output voltage Vs decreases.
  • the second integral gain calculator 325B calculates the integral gain Gi based on the surplus amount ⁇ Q of the cathode gas supply flow rate. For example, the second integral gain calculation unit 325B decreases the integral gain Gi because the degree of oxygen deficiency increases as the excess amount ⁇ Q of the cathode gas decreases.
  • step S127 the third integral gain calculator 325C calculates an integral gain Gi based on the cathode reaction resistance Rc. For example, the third integral gain calculation unit 325C decreases the integral gain Gi because the degree of oxygen deficiency increases as the cathode reaction resistance Rc increases.
  • step S1208 the integral gain setting unit 326 outputs the smallest value among the three integral gains Gi calculated in the processes from step S125 to step S127 to the integrator 316.
  • the closer the fuel cell approaches an oxygen-deficient state the smaller the decrease in the cathode gas supply flow rate.
  • step S128 When the process of step S128 is completed, the cathode gas supply flow rate decrease width suppression process is completed, and the process returns to step S12 shown in FIG. Then, the transient gas flow rate reduction width restriction unit 320 changes the proportional gain Gp of the proportional device 313 and the integral gain Gi of the integrator 316, and proceeds to the process of step 13.
  • FIG. 19 is a diagram showing a change in overshoot when the proportional gain Gp and the integral gain Gi are reduced when the WET operation is executed.
  • FIG. 14A the change in the decrease amount of the cathode gas supply flow rate when the target HFR rapidly decreases is shown.
  • the priority control unit 302 decreases the amount of decrease in the cathode gas supply flow rate per unit time as the cathode gas supply state approaches the oxygen deficient state. .
  • FIG. 20 is a time chart showing an example of a change in the cathode gas supply flow rate when the WET operation is executed.
  • the operating state of the fuel cell system 100 when the cathode gas supply flow rate reduction width suppression process is executed is indicated by a solid line, and the fuel cell system 100 when the cathode gas supply flow rate reduction width reduction process is not executed is shown.
  • the operating state is indicated by a one-dot chain line. Further, only the output voltage of the fuel cell stack 1 is used as a parameter indicating the degree of oxygen deficiency.
  • FIG. 20A is a diagram illustrating a change in the measurement HFR output from the impedance measurement device 6.
  • FIG. 20B is a diagram showing a change in the proportional gain Gp set in the proportional device 313 based on the measured HFR shown in FIG.
  • FIG. 20C is a diagram showing a change in the integral gain Gi set in the integrator 316 based on the measured HFR shown in FIG.
  • FIG. 20 (d) is a diagram showing a change in the cathode gas supply flow rate in accordance with the change in the proportional gain Gp and the integral gain Gi shown in FIGS. 20 (b) and 20 (c).
  • FIG. 20 (e) is a diagram showing a change in the output voltage Vs of the fuel cell stack 1 accompanying a change in the cathode gas supply flow rate shown in FIG. 20 (d).
  • the horizontal axis of each drawing from FIG. 20A to FIG. 20D is a common time axis.
  • the target HFR calculator 311 sets the target HFR to a value lower than the measured HFR. That is, a WET operation for moistening the electrolyte membrane is executed.
  • the required wet flow rate Qr_w is calculated by the gas flow rate F / B control unit 301 so that the measured HFR drops to the target HFR, and this required wet flow rate Qr_w is set as the cathode gas target flow rate Qt.
  • the output voltage of the fuel cell stack 1 decreases to the first voltage value v1. Therefore, as shown in FIGS. 20B and 20C, as the output voltage of the fuel cell stack 1 decreases, the proportional gain Gp is set to a value smaller than the reference value Gp_b, and the integral gain Gi is set to a value smaller than the reference value Gp_b.
  • the decrease amount of the cathode gas supply flow rate indicated by the solid line becomes smaller than the decrease amount of the cathode gas supply flow rate indicated by the alternate long and short dash line. That is, the priority control unit 302 reduces the amount of decrease in the supply amount of cathode gas as the supply state of the cathode gas supplied to the fuel cell stack 1 approaches a state where the supply amount is insufficient.
  • the output voltage of the fuel cell stack decreases to the voltage threshold Th_v as shown in FIG. Can be prevented. That is, it is possible to prevent the lack of oxygen in the fuel cell due to excessive reduction in the cathode gas supply flow rate.
  • the cathode gas supply flow rate increases to the contrary, and the amount of water vapor discharge increases accordingly. As indicated by the chain line, the measured HFR becomes high. Thereafter, the cathode gas supply flow rate sharply decreases at time t23.
  • the cathode gas supply flow rate greatly fluctuates in a short time. It gets bigger. Furthermore, as shown in FIG. 20 (a), the time until the fuel cell stack 1 reaches the target HFR becomes longer by the period from time t24 to time t25.
  • the cathode gas supply flow rate reduction width suppression process is executed during the WET operation, it is possible to prevent the cathode gas supply flow rate from being excessively reduced and to smoothly reduce the cathode gas supply flow rate. . Therefore, the fuel cell stack 1 can be shifted to the target wet state at an early stage while avoiding the fuel cell from being deficient in oxygen.
  • the priority control unit 302 when it is determined that the WET operation is performed, that is, when it is determined that the supply amount of the cathode gas is insufficient, the priority control unit 302 is the gas supply state detection unit. In accordance with the signal from 220, the amount of decrease in the supply amount of the cathode gas is reduced. That is, the priority control unit 302 decreases the amount of decrease in the supply amount of the cathode gas as the supply state of the cathode gas supplied to the fuel cell stack 1 approaches an oxygen deficient state in which the supply amount of the cathode gas is insufficient.
  • the oxygen depletion of the fuel cell in the fuel cell stack 1 can be prevented, and the state of the electrolyte membrane can be shifted to a moist state at an early stage. Furthermore, by reducing the amount by which the cathode gas supply amount is reduced only when the WET operation is performed, useless processing can be reduced, and processing in the power generation control unit 300 can be reduced.
  • the priority control unit 302 performs the process of step S8 when it is determined in step S11 of FIG. 17 that the WET operation is executed based on the signal from the film wet state detection unit 210. Thus, it is determined whether or not the supply amount of the cathode gas is insufficient. When it is determined that the supply amount of the cathode gas is insufficient, the priority control unit 302 controls the supply amount of the cathode gas based on the stack output current Is from the current sensor 51 as in the process of step S9. On the other hand, when it is not determined that the supply amount of the cathode gas is insufficient, the priority control unit 302 restricts (prohibits) the control of the supply amount of the cathode gas based on the stack output current Is.
  • the gas deficiency determination unit 330 performs the degree of oxygen deficiency from the gas supply state detection unit 220 as in the process of step S8 in FIG. It is determined whether or not the signal indicating the value exceeds a predetermined threshold value. Then, as in the process of step S9, when the signal indicating the degree of oxygen deficiency exceeds a predetermined threshold value, that is, when the supply state of the cathode gas has reached the oxygen deficiency state, the priority control unit 302 performs the fuel cell stack 1 The supply amount of the cathode gas is controlled on the basis of the output power.
  • the supply amount of the cathode gas is the minimum supply necessary for power generation of the fuel cell stack 1. It can be reliably prevented that the amount is lower than the amount (oxygen deficiency prevention flow rate).
  • FIG. 21 is a diagram showing a configuration of the fuel cell system 101 according to the third embodiment of the present invention.
  • the fuel cell system 101 includes a bypass passage 35 and a bypass valve 36 in addition to the configuration of the fuel cell system 100 shown in FIG. Since the configuration other than the bypass passage 35 and the bypass valve 36 is the same as the configuration of the fuel cell system 100, the same reference numerals are given and detailed description thereof is omitted.
  • the bypass passage 35 is a passage for bypassing the fuel cell stack 1 and discharging a part of the cathode gas supplied from the compressor 32 to the fuel cell stack 1 to the outside.
  • bypass passage 35 One end of the bypass passage 35 is connected to the cathode gas supply passage 31 downstream from the compressor 32, and the other end is connected to the cathode gas discharge passage 33 downstream from the cathode pressure regulating valve 34. That is, the bypass passage 35 branches from the cathode gas supply passage 31 downstream of the compressor 32 and joins the cathode gas discharge passage 33 downstream of the cathode pressure regulating valve 34.
  • the bypass valve 36 is provided in the bypass passage 35.
  • As the bypass valve 36 for example, an electromagnetic valve capable of changing the opening degree of the valve stepwise is used.
  • the bypass valve 36 is controlled to open and close by the controller 200. By this opening / closing control, the supply flow rate of the cathode gas supplied to the fuel cell stack 1 is adjusted to a desired flow rate.
  • the bypass valve 36 opens as the opening degree of the bypass valve 36 increases, and the bypass valve 36 closes as the opening degree of the bypass valve 36 increases.
  • the controller 200 controls the opening degree of the bypass valve in addition to the rotation speed of the compressor 32 and the opening degree of the cathode pressure regulating valve 34 in order to adjust the supply flow rate of the cathode gas supplied to the fuel cell stack 1.
  • the controller 200 increases the opening degree of the bypass valve 36 without reducing the rotational speed of the compressor 32 below a predetermined value in order to avoid the surge of the compressor 32. As a result, the supply flow rate of the cathode gas is reduced, so that the electrolyte membrane in the fuel cell stack 1 can be in a wet state.
  • FIG. 22 is a block diagram showing an example of a functional configuration of the cathode gas supply flow rate estimation unit 221A in the present embodiment.
  • the cathode gas supply flow rate estimation unit 221A corresponds to the cathode gas supply flow rate estimation unit 221 shown in FIG.
  • the cathode gas supply flow rate estimation unit 221A is configured to supply the cathode gas supply flow rate Qc to the fuel cell stack 1 based on the opening degree of the cathode pressure regulating valve 34, the opening degree of the bypass valve 36, and the rotational speed of the compressor 32. Is estimated.
  • the cathode gas supply flow rate estimation unit 221A includes a main passage pressure loss characteristic extraction unit 2211A, a bypass passage pressure loss characteristic extraction unit 2211B, a pressure loss synthesis unit 2211C, and a cathode gas supply flow rate calculation unit 2214.
  • the configurations of the compressor operation characteristic extraction unit 2212 and the intersection point extraction unit 2213 are the same as the configurations of the cathode gas supply flow rate estimation unit 221, and thus the same reference numerals are given and description thereof is omitted here.
  • a main passage pressure loss map is recorded in advance.
  • a pressure loss characteristic ⁇ Pa indicating the relationship between the discharge flow rate of the compressor 32 and the pressure loss of the main passage constituting the cathode gas supply passage 31 is set for each opening of the cathode pressure regulating valve 34.
  • the main passage here is a passage from a branch portion of the cathode gas supply passage 31 to the bypass passage 35 to a portion where the cathode gas discharge passage 33 joins the bypass passage 35 through the fuel cell stack 1. .
  • the main passage pressure loss characteristic extraction unit 2211A refers to the main passage pressure loss map and extracts the pressure loss characteristic specified by the acquired detection value.
  • the main passage pressure loss characteristic extraction unit 2211A outputs the extracted pressure loss characteristic ⁇ Pa to the pressure loss synthesis unit 2211C.
  • bypass passage pressure loss characteristic extraction unit 2211B a bypass passage pressure loss map is recorded in advance.
  • a pressure loss characteristic ⁇ Pb indicating the relationship between the discharge flow rate of the compressor 32 and the pressure loss of the bypass passage 35 is set for each opening degree of the bypass valve 36.
  • bypass passage pressure loss characteristic extraction unit 2211B When the bypass passage pressure loss characteristic extraction unit 2211B acquires the detection value of the opening degree of the bypass valve 36, the bypass passage pressure loss characteristic extraction unit 2211B refers to the bypass passage pressure loss map and extracts the pressure loss characteristic specified by the acquired detection value.
  • the bypass passage pressure loss characteristic extraction unit 2211B outputs the extracted pressure loss characteristic ⁇ Pb to the pressure loss synthesis unit 2211C.
  • the pressure loss synthesis unit 2211C obtains the pressure loss characteristic ⁇ Pa of the main passage from the main passage pressure loss characteristic extraction unit 2211A and the pressure loss characteristic ⁇ Pb of the bypass passage 35 from the bypass passage pressure loss characteristic extraction unit 2211B. Then, the pressure loss synthesis unit 2211C calculates the pressure loss characteristic ⁇ P of the entire passage in the cathode gas supply / discharge device 3 based on the pressure loss characteristic ⁇ Pa of the main passage and the pressure loss characteristic ⁇ Pb of the bypass passage 35.
  • the pressure loss combining unit 2211C uses the pressure loss characteristic ⁇ Pc of the common portion in addition to the pressure loss characteristic ⁇ Pa of the main passage and the pressure loss characteristic ⁇ Pb of the bypass passage 35 as shown in the following equation. Then, the pressure loss characteristic ⁇ P of the entire passage is calculated.
  • the pressure loss characteristic ⁇ Pc of the common portion referred to here is the pressure loss characteristic of the portion of the cathode gas supply passage 31 and the cathode gas discharge passage 33 excluding the main passage and the bypass passage 35.
  • the pressure loss synthesis unit 2211C outputs the pressure loss characteristic ⁇ P of the entire passage calculated according to the above equation (10) to the intersection extraction unit 2213.
  • the intersection extraction unit 2213 extracts an intersection between the pressure loss characteristic ⁇ P from the pressure loss synthesis unit 2211C and the operation characteristic from the compressor operation characteristic extraction unit 2212.
  • the intersection extraction unit 2213 specifies the discharge flow rate Qg discharged from the compressor 32 to the entire passage by the intersection, and outputs the discharge flow rate Qg to the cathode gas supply flow rate calculation unit 2214.
  • the cathode gas supply flow rate calculation unit 2214 determines the amount of cathode gas supplied to the fuel cell stack 1 based on the discharge flow rate Qg of the entire passage, the pressure loss characteristic ⁇ Pa of the main passage, and the pressure loss characteristic ⁇ Pb of the bypass passage 35. An estimated value Qc of supply flow rate is calculated.
  • the cathode gas supply flow rate calculation unit 2214 calculates the discharge flow rate of the main passage when the pressure loss ⁇ Pa of the main passage and the pressure loss ⁇ Pb of the bypass passage 35 coincide with each other in the discharge flow rate Qg of the entire passage. Calculated as an estimated value Qc of the gas supply flow rate.
  • the cathode gas supply flow rate estimation unit 221A identifies the pressure loss characteristic ⁇ P of the entire passage based on the opening degree of the cathode pressure regulating valve 34 and the bypass valve 36, and the pressure loss characteristic ⁇ P and the discharge flow rate characteristic of the compressor 32. And the discharge flow rate Qg is estimated. Then, the cathode gas supply flow rate estimation unit 221A distributes the discharge flow rate Qg to the main passage and the bypass passage 35, and the cathode gas flowing in the main passage when the pressure loss of the main passage matches the pressure loss of the bypass passage 35. Is specified as the cathode gas supply flow rate Qc.
  • FIG. 23 is a flowchart showing an example of a control method of the fuel cell system 101 in the present embodiment.
  • step S21 is executed instead of the process of step S11 shown in FIG.
  • the other processes are the same as those shown in FIG. 17, and thus description thereof is omitted here.
  • step S21 the priority control unit 302 determines whether the opening degree of the bypass valve 36 is greater than zero.
  • the priority control unit 302 determines that the fuel cell can be in an oxygen deficient state, and proceeds to the process of step S12. That is, when the bypass valve 36 is opened, the priority control unit 302 determines that the supply amount of the cathode gas supplied to the fuel cell stack 1 is lower than the supply amount that is minimum required for power generation of the fuel cell stack 1. Judge that there may be a shortage.
  • the priority control unit 302 determines that the fuel cell cannot be in an oxygen deficient state, and proceeds to the process of step S13.
  • FIG. 24 is a flowchart illustrating an example of the cathode gas surplus amount calculation processing in step S5 in the present embodiment.
  • steps S511, S521 to S523, and S541 to S542 are executed instead of the steps S51, S52, and S54 shown in FIG.
  • Other processing is the same as the processing shown in FIG. 10, and thus description thereof is omitted here.
  • the cathode gas supply flow rate estimation unit 221A acquires the opening degree of the bypass valve 36 as a control amount of the cathode gas supply / discharge device 3 in addition to the rotation speed of the compressor 32 and the opening degree of the cathode pressure regulating valve 34.
  • the cathode gas supply flow rate estimation unit 221A acquires, for example, a detection signal from an opening degree sensor provided in the bypass valve 36.
  • step S521 the main passage pressure loss characteristic extraction unit 2211A specifies the pressure loss characteristic ⁇ Pa of the main passage based on the opening of the cathode pressure regulating valve 34 as described in FIG.
  • step S522 the bypass passage pressure loss characteristic extraction unit 2211B specifies the pressure loss characteristic ⁇ Pb of the bypass passage 35 based on the opening degree of the bypass valve 36 as described in FIG.
  • step S523 the pressure loss synthesizing unit 2211C is based on the pressure loss characteristic ⁇ Pa of the main passage, the pressure loss characteristic ⁇ Pb of the bypass passage 35, and the pressure loss characteristic ⁇ Pc of the common portion as shown in the equation (10). Then, the pressure loss characteristic ⁇ P of the entire passage is calculated.
  • step S53 the compressor operation characteristic extraction unit 2212 identifies the discharge flow rate characteristic of the compressor 32 based on the rotation speed of the compressor 32 as described in FIG.
  • step S541 the intersection extraction unit 2213 calculates the intersection when the discharge flow rate characteristic of the compressor 32 extracted in the process of step S53 and the pressure loss characteristic ⁇ P of the entire passage calculated in the process of step S523 are superimposed on each other. Identify. The intersection extraction unit 2213 calculates the discharge flow rate of the compressor 32 specified by the intersection, that is, the total flow rate Qg of the cathode gas.
  • step S542 the cathode gas supply flow rate calculation unit 2214 calculates the cathode gas supply flow rate Qc based on the discharge flow rate of the compressor 32, the pressure loss characteristic ⁇ Pa of the main passage, and the pressure loss characteristic ⁇ Pb of the bypass passage 35. Execute. Details of such cathode gas supply flow rate calculation processing will be described later with reference to FIG.
  • step S55 the load request flow rate calculation unit 222 calculates the load request flow rate Qr_l of the cathode gas based on the stack target current as described in FIG.
  • step S56 the oxygen deficiency degree calculation unit 223 calculates the cathode gas supply flow rate surplus ⁇ Q by subtracting the load request flow rate Qr_l from the cathode gas supply flow rate Qc as described in FIG. The quantity calculation process ends.
  • FIG. 25 is a flowchart showing an example of the cathode gas supply flow rate calculation process executed in step S542.
  • step S5421 the cathode gas supply flow rate calculation unit 2214 sets the value (Qg / 2) obtained by halving the discharge flow rate Qg of the compressor 32 to the temporary supply flow rate Qtc of the main passage and the temporary bypass flow rate Qtb of the bypass passage 35 as initial values. Set both.
  • step S5421 the cathode gas supply flow rate calculation unit 2214 refers to the pressure loss characteristic ⁇ Pa of the main passage specified in the process of step S521, and calculates a pressure loss ⁇ Pta corresponding to the provisional supply flow rate Qtc.
  • step S5422 the cathode gas supply flow rate calculation unit 2214 calculates the pressure loss ⁇ Ptb corresponding to the provisional bypass flow rate Qtb with reference to the pressure loss characteristic ⁇ Pb of the bypass passage specified in the process of step S522.
  • step S5424 the cathode gas supply flow rate calculation unit 2214 determines whether or not the main channel pressure loss ⁇ Pta and the bypass channel pressure loss ⁇ Ptb are equal to each other. Specifically, the cathode gas supply flow rate calculation unit 2214 calculates the absolute value of the difference between the pressure loss ⁇ Pta of the main passage and the pressure loss ⁇ Ptb of the bypass passage, and determines whether the absolute value is equal to or less than a predetermined value. to decide. Note that the predetermined value is obtained by adding a value that takes into account an error associated with the calculation to zero.
  • step S5425 when the absolute value of the difference between the pressure loss ⁇ Pta of the main passage and the pressure loss ⁇ Ptb of the bypass passage is larger than a predetermined value, the cathode gas supply flow rate calculation unit 2214 Qtb are mutually changed.
  • the cathode gas supply flow rate calculation unit 2214 multiplies the value obtained by subtracting the pressure loss ⁇ Ptb of the bypass passage from the pressure loss ⁇ Pta of the main passage by the coefficient F, and subtracts this multiplied value from the provisional supply flow rate Qtc.
  • the cathode gas supply flow rate calculation unit 2214 newly sets the subtracted value (Qtc ⁇ ( ⁇ Pta ⁇ Ptb) ⁇ F) as the temporary supply flow rate Qtc, and then subtracts the temporary supply flow rate Qt from the discharge flow rate Qg. A new temporary bypass flow rate Qtb is set.
  • the cathode gas supply flow rate calculation unit 2214 repeats a series of processing from step S5422 to step S5425 until the absolute value of the difference between the pressure loss ⁇ Pta of the main passage and the pressure loss ⁇ Ptb of the bypass passage becomes equal to or less than a predetermined value. .
  • step S5426 the cathode gas supply flow rate calculation unit 2214 supplies the provisional supply flow rate Qtc to the cathode gas supply when the absolute value of the difference between the pressure loss ⁇ Pta of the main passage and the pressure loss ⁇ Ptb of the bypass passage is equal to or less than a predetermined value. Set to flow rate Qc. Then, the cathode gas supply flow rate calculation process ends. Thereafter, the process returns to step S542 shown in FIG. 21, and the cathode gas supply flow rate calculation unit 2214 outputs the cathode gas supply flow rate Qc to the oxygen deficiency degree calculation unit 223.
  • the cathode gas supply flow rate Qc is estimated using the relationship in which the pressure losses in the main passage and the bypass passage are equal to each other.
  • bypass passage 35 and the bypass valve 36 are provided as bypass means for bypassing the cathode gas supplied from the compressor 32 to the fuel cell stack 1.
  • the priority control unit 302 determines whether or not the bypass valve 36 is open.
  • the priority control unit 302 responds to a signal indicating the degree of oxygen deficiency from the gas supply state detection unit 220. Change the F / B gain to reduce the decrease in cathode gas supply flow rate.
  • the priority control unit 302 limits the cathode gas target flow rate Qt to the oxygen deficiency prevention flow rate Qp when the fuel cell can be in an oxygen deficiency state when the bypass valve 36 is opened. Thereby, similarly to 1st Embodiment, the fall of the power generation efficiency of a fuel cell can be suppressed, moistening the electrolyte membrane of the fuel cell stack 1 at an early stage.
  • the gas supply state detection unit 220 calculates the total flow rate Qg of the cathode gas by utilizing the relationship in which the pressure losses in the main passage and the bypass passage are equal to each other, and indicates the degree of oxygen deficiency based on the total flow rate Qg.
  • the excess amount ⁇ Q of the cathode gas is estimated.
  • the surplus amount ⁇ Q of the cathode gas can be estimated without detecting the total flow rate Qg of the cathode gas discharged from the compressor 32. Therefore, the sensor for detecting the flow rate of the cathode gas can be omitted, and the configuration of the fuel cell system 102 can be reduced. It can be simplified.
  • FIG. 26 is a diagram showing a configuration of the fuel cell system 102 according to the fourth embodiment of the present invention.
  • the fuel cell system 102 includes a flow rate sensor 37 for detecting the total flow rate Qg of the cathode gas supplied to the cathode gas supply passage 31 in addition to the configuration of the fuel cell system 101 shown in FIG.
  • a flow rate sensor 37 for detecting the total flow rate Qg of the cathode gas supplied to the cathode gas supply passage 31 in addition to the configuration of the fuel cell system 101 shown in FIG.
  • symbol is attached
  • the flow sensor 37 constitutes a measuring means for measuring the amount of cathode gas sucked into the cathode gas supply / discharge device 3.
  • the flow sensor 37 is provided in the cathode gas supply passage 31 upstream of the compressor 32 and detects the intake flow rate of the cathode gas sucked into the compressor 32.
  • the flow sensor 37 outputs the detected intake flow rate to the controller 200 as the total flow rate Qg of the cathode gas.
  • the controller 200 calculates the surplus amount ⁇ Q of the cathode gas supplied to the fuel cell stack 1 based on the total flow rate Qg of the cathode gas output from the flow sensor 37.
  • the controller 200 changes the proportional gain Gp and the integral gain Gi using the surplus amount ⁇ Q as a parameter indicating the degree of oxygen deficiency of the fuel cell, and the fuel cell can be in an oxygen deficient state. It is determined whether or not. When it is determined that the fuel cell can be in an oxygen deficient state, the controller 200 switches the cathode gas target flow rate Qt from the required wet flow rate Qr_w to the oxygen deficiency prevention flow rate Qp.
  • FIG. 27 is a flowchart showing an example of a control method of the fuel cell system 102.
  • the process of step S21 is executed between the process of step S3 and the process of step S4.
  • step S21 the priority control unit 302 proceeds to the process of step S4 only when the opening degree of the bypass valve 36 is larger than zero, that is, when the bypass valve 36 is opened.
  • step S13 when the opening degree of the bypass valve 36 is zero, that is, when the bypass valve 36 is closed, the priority control unit 302 executes the process of step S13 and then executes the processes of steps S4 to S9.
  • the process of step S10 is executed without executing the process of step S12.
  • FIG. 28 is a flowchart illustrating an example of the cathode gas surplus amount calculation processing in step S5 in the present embodiment.
  • the pressure loss synthesis unit 2211C, the compressor operation characteristic extraction unit 2212, and the intersection extraction unit 2213 illustrated in FIG. 22 are omitted.
  • step S512 is executed instead of the process of step S511 shown in FIG. 24, and the process of step S540 is executed instead of the processes of steps S523, S53, and S541. Since the other processes are the same as those shown in FIG. 24, description thereof is omitted here, and only the processes of steps S512 and S540 are described.
  • step S512 the cathode gas supply flow rate estimation unit 221A determines the intake flow rate of the compressor 32 output from the flow rate sensor 37 in addition to the rotation speed of the compressor 32, the opening degree of the cathode pressure regulating valve 34, and the opening degree of the bypass valve 36. get.
  • step S540 the cathode gas supply flow rate calculation unit 2214 sets the suction flow rate of the compressor 32 acquired in step S512 as the total flow rate Qg of the cathode gas.
  • step S542 the cathode gas supply flow rate calculation unit 2214 calculates the cathode gas supply flow rate Qc based on the total cathode gas flow rate Qg, the pressure loss characteristic ⁇ Pa of the main passage, and the pressure loss characteristic ⁇ Pb of the bypass passage. Execute.
  • step S55 the required load flow rate Qr_l is calculated in step S55, and the excess amount ⁇ Q of the cathode gas supply flow rate is calculated as a parameter indicating the degree of oxygen deficiency in step S56, and then the cathode gas surplus amount calculation processing is completed.
  • the cathode gas supply flow rate estimation unit 221A measures the intake flow rate of the compressor 32 by using the flow rate sensor 37, so that the processes of steps S523, S53, and S541 in the third embodiment can be omitted. . For this reason, the fuel cell system 102 can reduce the amount of calculation of the cathode gas supply flow rate calculation processing of step S5 compared with 3rd Embodiment.
  • the flow sensor 37 is provided as measurement means for measuring the intake amount of the cathode gas sucked into the compressor 32. It has been.
  • the priority control unit 302 determines whether the bypass valve 36 is open. If the bypass valve 36 is open, the priority control unit 302 determines whether the acid from the gas supply state detection unit 220 is open. The amount of decrease in the cathode gas supply flow rate is reduced according to the signal indicating the degree of lack.
  • the priority control unit 302 supplies the cathode gas supply amount based on the cathode gas supply amount Qc calculated by the gas supply state detection unit 220 when a part of the cathode gas is bypassed by the bypass valve 36. Limit the amount to reduce. Thereby, similarly to the third embodiment, when the wet control for moistening the electrolyte membrane of the fuel cell stack 1 is being performed, it is possible to suppress the fluctuation in the cathode gas supply flow rate accompanying the feedback control.
  • the priority control unit 302 limits the cathode gas target flow rate Qt to the oxygen deficiency prevention flow rate Qp when the fuel cell can be in an oxygen deficiency state when the bypass valve 36 is opened. Thereby, like 3rd Embodiment, the fall of the power generation efficiency of a fuel cell can be suppressed, moistening the electrolyte membrane of the fuel cell stack 1 at an early stage.
  • the priority control unit 302 does not execute the cathode gas supply flow rate decrease width suppression process in step S5 and the cathode gas supply flow rate decrease prevention process in step S9. Arithmetic processing can be reduced.
  • the cathode gas supply flow rate estimation unit 221A acquires the suction flow rate output from the flow rate sensor 37 as the total flow rate Qg of the cathode gas, and estimates the surplus amount ⁇ Q of the cathode gas indicating the degree of oxygen deficiency. For this reason, it is possible to reduce the calculation amount of the cathode gas surplus amount calculation processing as compared with the third embodiment.
  • FIG. 29 is a block diagram showing an example of the configuration of the impedance measuring device 6.
  • the impedance measuring device 6 is connected to the intermediate terminal 1C in addition to the positive electrode terminal (cathode electrode side terminal) 1B and the negative electrode terminal (anode electrode side terminal) 1A of the fuel cell stack 1. The portion connected to the midway terminal 1C is grounded.
  • the impedance measuring device 6 includes a positive side voltage measurement sensor 61 that measures the positive side AC potential difference V1 of the positive terminal 1B with respect to the midway terminal 1C, and a negative side voltage measurement that measures the negative side AC potential difference V2 of the negative terminal 1A with respect to the midway terminal 1C. Sensor 62.
  • the impedance measuring device 6 applies an alternating current I2 to a positive side AC power supply unit 63 that applies an alternating current I1 to a circuit that includes the positive terminal 1B and the intermediate terminal 1C, and a circuit that includes the negative terminal 1A and the intermediate terminal 1C.
  • the controller 65 Based on the negative electrode side AC power supply unit 64, the controller 65 that adjusts the amplitude and phase of the AC current I1 and the AC current I2, and the positive side AC potential differences V1 and V2 and the AC currents I1 and I2, the inside of the fuel cell stack 1 And an impedance calculation unit 66 for calculating the impedance Z.
  • the controller 65 adjusts the amplitude and phase of the alternating current I1 and the alternating current I2 so that the positive side AC potential difference V1 and the negative side AC potential difference V2 are equal.
  • the impedance calculation unit 66 includes hardware such as an AD converter and a microcomputer chip (not shown) and a software configuration such as a program for calculating impedance.
  • the impedance calculator 66 calculates the internal impedance Z1 from the halfway terminal 1C to the positive terminal 1B by dividing the positive side AC potential difference V1 by the AC current I1, and divides the negative side AC potential difference V2 by the AC current I2. An internal impedance Z2 from the midway terminal 1C to the negative electrode terminal 1A is calculated. Further, the impedance calculator 66 calculates the total impedance Z of the fuel cell stack 1 by taking the sum of the internal impedance Z1 and the internal impedance Z2.
  • the impedance calculation unit 66 calculates the real part component of the positive-side AC potential difference V1 by multiplying the positive-phase AC potential difference V1 by an in-phase signal having the same phase as that of the AC current I1, and thereby calculates the positive-side AC current difference. Based on the real part component of the potential difference V1, the real part of the internal impedance Z1 is calculated. Similarly, the impedance calculation unit 66 calculates an imaginary part component of the positive-side AC potential difference V1 by multiplying the positive-side AC potential difference V1 by an orthogonal signal whose phase is orthogonal to the alternating current I1, and calculates an imaginary part of the positive-side AC potential difference V1. An imaginary part of the internal impedance Z1 is calculated based on the part component.
  • the impedance calculation part 66 calculates the real part of the internal impedance Z by taking the sum of the real part of the internal impedance Z1 and the real part of the internal impedance Z2, and the imaginary part of the internal impedance Z1 and the imaginary part of the internal impedance Z2.
  • the imaginary part of the internal impedance Z is calculated by taking the sum of The impedance calculator 66 outputs the real part and the imaginary part of the internal impedance Z to the controller 200 shown in FIG.
  • the impedance measuring device 6 is connected to the fuel cell stack 1 and outputs AC currents I 1 and I 2 to the fuel cell stack 1, and the positive electrode of the fuel cell stack 1.
  • the positive side AC potential difference V1 which is a potential difference obtained by subtracting the potential of the middle portion 1C from the potential of the side 1B
  • the negative polarity which is a potential difference obtained by subtracting the potential of the middle portion 1C from the potential of the negative side 1A of the fuel cell stack 1.
  • the controller 65 as an AC adjusting unit that adjusts the AC currents I1 and I2 based on the side AC potential difference V2, and the fuel based on the adjusted AC currents I1 and I2, the positive side AC potential difference V1, and the negative side AC potential difference V2
  • the controller 65 is configured so that the positive-side AC potential difference V1 on the positive side of the fuel cell stack 1 and the negative-side AC potential difference V2 on the negative side substantially coincide with the alternating current I1 and the negative electrode applied by the positive-side AC power supply unit 63.
  • the amplitude and phase of the alternating current I2 applied by the side alternating-current power supply unit 64 are adjusted.
  • the amplitude of the positive-side AC potential difference V1 is equal to the amplitude of the negative-side AC potential difference V2, so that the positive terminal 1B and the negative terminal 1A are substantially equipotential (hereinafter, this is referred to as equipotential control). ). Therefore, since the alternating currents I1 and I2 for impedance measurement are prevented from flowing to the load 5, the power generation by the fuel cell 1 is prevented from being affected.
  • an alternating current may be supplied to the fuel cell stack 1 from a predetermined current source, an output alternating voltage may be measured, and an impedance may be calculated based on the alternating current and the output alternating voltage.
  • the voltage sensor 52 detects the output power Vs of the fuel cell stack 1, but may detect the cell voltage of at least one fuel cell stacked on the fuel cell stack 1. Even in this case, similarly to the output voltage Vs that is the total voltage of each fuel cell, the priority control unit 302 can predict the oxygen deficiency state of the fuel cell based on the cell voltage of the fuel cell stack 1. it can.

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Abstract

La présente invention concerne un système de pile à combustible, dans lequel un gaz d'anode est alimenté à une membrane d'électrolyte d'une pile à combustible et un gaz de cathode est alimenté à la membrane d'électrolyte, commande la fourniture du gaz de cathode et la fourniture du gaz d'anode, de manière à commander la génération d'électricité de la pile à combustible. Ce système de pile à combustible détecte l'état humide de la membrane d'électrolyte et l'état d'alimentation du gaz de cathode fourni à la membrane d'électrolyte et, sur la base du signal de la détection d'état humide, commande la quantité d'alimentation du gaz de cathode alimenté à la membrane d'électrolyte, de manière à commander l'état de génération d'électricité de la pile à combustible. Si la quantité d'alimentation du gaz de cathode est déterminée comme étant insuffisante en fonction du signal à partir duquel l'état d'alimentation est détecté, ce système de pile à combustible place en priorité le signal de détection d'état humide, et commande l'état de génération d'électricité de la pile à combustible par contrôle de la quantité d'alimentation du gaz de cathode en fonction du signal à partir duquel l'état d'alimentation est détecté.
PCT/JP2015/052831 2015-02-02 2015-02-02 Système de pile à combustible et procédé de commande de système de pile à combustible WO2016125231A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007115488A (ja) * 2005-10-19 2007-05-10 Toyota Motor Corp 燃料電池のカソードガス制御方法および燃料電池システム
WO2012077450A1 (fr) * 2010-12-10 2012-06-14 日産自動車株式会社 Appareil de mesure de résistance interne de batteries en couches
WO2013105590A1 (fr) * 2012-01-10 2013-07-18 日産自動車株式会社 Système de pile à combustible
WO2014103589A1 (fr) * 2012-12-28 2014-07-03 日産自動車株式会社 Système de pile à combustible et procédé pour sa commande

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007115488A (ja) * 2005-10-19 2007-05-10 Toyota Motor Corp 燃料電池のカソードガス制御方法および燃料電池システム
WO2012077450A1 (fr) * 2010-12-10 2012-06-14 日産自動車株式会社 Appareil de mesure de résistance interne de batteries en couches
WO2013105590A1 (fr) * 2012-01-10 2013-07-18 日産自動車株式会社 Système de pile à combustible
WO2014103589A1 (fr) * 2012-12-28 2014-07-03 日産自動車株式会社 Système de pile à combustible et procédé pour sa commande

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