WO2013150619A1 - Fuel cell system - Google Patents

Fuel cell system Download PDF

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Publication number
WO2013150619A1
WO2013150619A1 PCT/JP2012/059216 JP2012059216W WO2013150619A1 WO 2013150619 A1 WO2013150619 A1 WO 2013150619A1 JP 2012059216 W JP2012059216 W JP 2012059216W WO 2013150619 A1 WO2013150619 A1 WO 2013150619A1
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WO
WIPO (PCT)
Prior art keywords
fuel cell
temperature
power
secondary battery
voltage
Prior art date
Application number
PCT/JP2012/059216
Other languages
French (fr)
Japanese (ja)
Inventor
道仁 田中
Original Assignee
トヨタ自動車株式会社
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Publication date
Application filed by トヨタ自動車株式会社 filed Critical トヨタ自動車株式会社
Priority to PCT/JP2012/059216 priority Critical patent/WO2013150619A1/en
Publication of WO2013150619A1 publication Critical patent/WO2013150619A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0432—Temperature; Ambient temperature
    • H01M8/04365—Temperature; Ambient temperature of other components of a fuel cell or fuel cell stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/04537—Electric variables
    • H01M8/04544—Voltage
    • H01M8/04559—Voltage of fuel cell stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
    • H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane
    • 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
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/40—Application of hydrogen technology to transportation, e.g. using fuel cells

Definitions

  • the present invention relates to a fuel cell system.
  • a fuel cell in which fuel cells included in the system are arranged with an electrolyte membrane interposed therebetween, and each has a fuel electrode having a catalyst and an oxidant electrode. Further, when the fuel cell does not generate power, the voltage of the fuel cell is controlled, and the oxidant electrode is controlled to have a potential of 0.8 V to 0.9 V with respect to the standard hydrogen electrode, such as platinum.
  • Patent Document 1 discloses that the catalyst is not eluted.
  • Patent Document 1 The above-described fuel cell system described in Patent Document 1 is an excellent system from the aspect of suppressing the elution of the catalyst of the fuel cell. However, if the control is performed so that the output terminal voltage of the fuel cell is maintained at the open end voltage, no current flows out from the fuel cell, so that the output terminal voltage of the fuel cell does not exceed the high potential avoidance voltage lower than the open end voltage. When the control is performed, the current corresponding to the difference flows out.
  • the present invention has been made in view of such problems, and an object of the present invention is a fuel cell system including a fuel cell, which can improve fuel efficiency while suppressing catalyst elution of the fuel cell. It is to provide a battery system.
  • a fuel cell system includes a fuel cell having a cell stack composed of a plurality of single cells that generate power upon receiving a supply of a reaction gas, and a stack temperature measuring unit that measures the temperature of the cell stack And a load that is electrically connected to the fuel cell, and an output supply unit that supplies the required power required by the load while adjusting the power supplied from the fuel cell.
  • the output supply unit controls the supply of the reaction gas to the fuel cell when the required power is less than the predetermined power, and controls the output voltage of the fuel cell to be maintained at a high potential avoidance voltage lower than the open-circuit voltage.
  • the output voltage of the fuel cell is controlled with the high potential avoidance voltage as an upper limit, and the high potential avoidance voltage is set according to the measured and / or estimated temperature of the cell stack. adjust.
  • the inventors of the present invention have focused on the fact that the degree of catalyst elution when the output voltage of the fuel cell fluctuates across the redox potential varies depending on the temperature of the cell stack. Specifically, it has been found that when the temperature of the cell stack is low, the elution degree of the catalyst falls within an allowable range even if the high potential avoidance voltage is increased to some extent.
  • the present invention is based on this finding, and by adjusting the high potential avoidance voltage according to the measured and / or estimated temperature of the cell stack, fuel elution can be improved while suppressing catalyst elution of the fuel cell. It can be planned.
  • the output supply unit has a second temperature lower than the first temperature than the first high potential avoidance voltage when the cell stack temperature is the first temperature. In this case, it is also preferable to set the second high potential avoidance voltage high.
  • the second high potential avoidance voltage when the cell stack temperature is the second temperature lower than the first temperature is higher than the first high potential avoidance voltage when the cell stack temperature is the first temperature. Therefore, the high potential avoidance voltage when the temperature of the cell stack is low can be increased, and surplus power of the cell stack can be suppressed.
  • the outside air temperature measuring unit for measuring the outside air temperature the elapsed time measuring unit for measuring the elapsed time after the stop of the fuel cell system, and the outside air temperature at the start of the fuel cell system It is preferable to include a correlation holding unit that stores a correlation between the stop temperature of the cell stack at the time of stop and the elapsed time after the stop and the temperature of the cell stack corresponding to the stop time.
  • the output supply unit corresponds to the outside temperature measured by the outside temperature measuring unit, the temperature of the cell stack at the time of stop measured by the stack temperature measuring unit, and the elapsed time after the stop measured by the elapsed time measuring unit.
  • the temperature of the cell stack is acquired from the correlation holding unit, and the acquired temperature is regarded as the temperature of the cell stack at the start, and the high potential avoidance voltage is adjusted.
  • the high potential avoidance voltage is adjusted according to the measured and / or estimated temperature of the cell stack.
  • an alternative is to measure the outlet temperature of the cooling water of the cell stack.
  • the outlet temperature of the cooling water may be regarded as the temperature of the cell stack.
  • the cooling water does not circulate, and the cooling water often does not accurately represent the temperature of the cell stack.
  • the correlation holding unit includes the outside air temperature at the start of the fuel cell system, the stop temperature of the cell stack at the time of stop, the elapsed time after the stop, and the temperature of the cell stack corresponding thereto.
  • the correlation is stored, and the output supply unit acquires the temperature of the cell stack using the actually measured outside air temperature, the temperature of the cell stack, and the elapsed time after the stop.
  • a secondary battery capable of charging and discharging electricity
  • a battery temperature measuring unit for measuring the temperature of the secondary battery
  • a charging rate for measuring the charging rate of the secondary battery
  • the correlation holding unit preferably stores a correlation between the temperature of the secondary battery, the charging rate of the secondary battery, and the maximum absorbable power of the secondary battery corresponding to the temperature.
  • the output supply unit supplies power corresponding to the required power required by the load while adjusting the power supplied from the fuel cell and the power supplied from the secondary battery.
  • the maximum absorbable power of the secondary battery corresponding to the temperature of the secondary battery measured by the temperature measuring unit and the charging rate of the secondary battery measured by the charging rate measuring unit is acquired from the correlation holding unit, and the acquired maximum The high potential avoidance voltage is adjusted using the absorbable power.
  • the correlation holding unit stores the correlation between the temperature of the secondary battery, the charging rate of the secondary battery, and the maximum absorbable power of the secondary battery corresponding to them, and supplies the output. The unit acquires the maximum absorbable power using the measured temperature and charging rate of the secondary battery.
  • the present invention it is possible to provide a fuel cell system capable of improving fuel consumption while suppressing catalyst elution of the fuel cell.
  • FIG. 1 is a schematic configuration diagram showing a configuration of a fuel cell system according to an embodiment of the present invention. It is a timing chart which shows the operation control of the fuel cell system shown in FIG. It is a graph which shows the relationship between the performance fall of a fuel cell, and temperature. It is a graph which shows the relationship between the temperature of a cell stack, and an upper limit voltage. It is a graph which shows the relationship between temperature, the output of a fuel cell, temperature, and secondary battery allowable power.
  • FIG. 1 is a diagram showing a system configuration of a fuel cell system FS that functions as an in-vehicle power supply system for a fuel cell vehicle.
  • the fuel cell system FS can be mounted on a vehicle such as a fuel cell vehicle (FCHV), an electric vehicle, or a hybrid vehicle.
  • FCHV fuel cell vehicle
  • the fuel cell system FS includes a fuel cell FC, an oxidizing gas supply system ASS, a fuel gas supply system FSS, a drive system HVS, and a cooling system CS.
  • the oxidizing gas supply system ASS is a system for supplying air as oxidizing gas to the fuel cell FC.
  • the fuel gas supply system FSS is a system for supplying hydrogen gas as fuel gas to the fuel cell FC.
  • the drive system HVS is a system that drives by supplying electric power to the drive motor DMa, and constitutes a hybrid system.
  • the cooling system CS is a system for cooling the fuel cell FC.
  • the drive motor DMa is a motor that drives the wheels 92 and 92.
  • the fuel cell system FCS will be described.
  • the fuel cell FC included in the fuel cell system FCS is configured as a solid polymer electrolyte type cell stack formed by stacking a number of cells CE (a single battery (a power generator) including an anode, a cathode, and an electrolyte) in series.
  • CE a single battery (a power generator) including an anode, a cathode, and an electrolyte
  • the fuel cell FC undergoes an oxidation reaction of formula (1) at the anode and a reduction reaction of formula (2) at the cathode.
  • the fuel cell FC as a whole undergoes an electromotive reaction of the formula (3).
  • the fuel cell system FCS has a hydrogen pump HPa and an exhaust / drain valve EVc in a region connecting the fuel cell FC and the fuel gas supply system FSS.
  • the fuel gas supplied to the fuel cell FC contributes to the electromotive reaction inside the fuel cell FC, and is discharged from the fuel cell FC as off-gas.
  • Part of the fuel off-gas discharged from the fuel cell FC is recirculated by the hydrogen pump HPa and re-supplied to the fuel cell FC together with the fuel gas supplied from the fuel gas supply system FSS. Further, part of the fuel off-gas is discharged together with the oxidation off-gas through the fuel off-gas flow path FS2 by the operation of the exhaust drain valve EVc.
  • the exhaust / drain valve EVc is a valve for discharging the fuel off-gas containing impurities in the circulation flow path and moisture to the outside by operating according to a command from the controller ECU.
  • the exhaust / drain valve EVc By opening the exhaust / drain valve EVc, the concentration of impurities in the fuel off-gas in the circulation flow path can be lowered, and the hydrogen concentration in the fuel off-gas circulating in the circulation system can be increased.
  • the fuel off-gas discharged through the exhaust / drain valve EVc is mixed with the oxidant off-gas flowing through the oxidant off-gas passage AS2, diluted by a diluter (not explicitly shown in FIG. 1), and sent to the muffler (not explicitly shown in FIG. 1). Supplied.
  • the fuel gas supply system FSS has a high-pressure hydrogen tank FS1 and a solenoid valve DVa.
  • the high-pressure hydrogen tank FS1 stores high-pressure (for example, 35 MPa to 70 MPa) hydrogen gas.
  • the solenoid valve DVa is a valve that adjusts the supply / stop of the fuel gas to the fuel cell FC while adjusting the supply pressure of the fuel gas to the fuel cell FC.
  • the fuel gas is decompressed to about 200 kPa, for example, by the electromagnetic valve DVa and supplied to the fuel cell FC.
  • the oxidizing gas supply system ASS includes an air compressor 62, an FC inlet three-way valve TVa, and an integrated valve DVb.
  • the oxidant gas supply system ASS has an oxidant gas passage AS1 through which air as an oxidant gas supplied to the cathode of the fuel cell FC flows, and an oxidant offgas passage AS2 through which the oxidant offgas discharged from the fuel cell FC flows. ing.
  • the air compressor 62 and the FC inlet three-way valve TVa are sequentially arranged from the inlet side of the oxidizing gas flow path AS1 toward the fuel cell FC.
  • the integrated valve DVb is disposed in the oxidation off gas flow path AS2.
  • the integrated valve DVb functions as a back pressure adjustment valve.
  • the FC inlet three-way valve TVa is a valve for adjusting the air flowing through the oxidizing gas passage AS1 to the fuel cell FC side and the air flowing through the bypass passage 69 connecting the oxidizing gas passage AS1 and the oxidizing off-gas passage AS2. It is. If a large amount of air is required on the fuel cell FC side, adjust the opening so that a large amount of air flows on the fuel cell FC side. If a large amount of air is not required on the fuel cell FC side, bypass it. The opening degree is adjusted so that a large amount of air flows to the flow path 69 side.
  • a pressure sensor Pt is provided between the fuel cell FC and the integrated valve DVb.
  • the drive system HVS includes a fuel cell booster, a power control unit, and a secondary battery BTa.
  • the fuel cell boosting unit includes a fuel cell boosting converter (output supply unit) and a relay.
  • the fuel cell boost converter boosts DC power generated by the fuel cell FC and supplies the boosted DC power to the power control unit.
  • the voltage conversion control by the boost converter controls the operating point (output terminal voltage, output current) of the fuel cell FC.
  • the power control unit has a battery boost converter and a traction inverter.
  • the electric power supplied from the fuel cell boost converter is supplied to the battery boost converter and the traction inverter.
  • the battery boost converter boosts the DC power supplied from the secondary battery BTa and outputs it to the traction inverter, and reduces the DC power generated by the fuel cell FC and the regenerative power recovered by the drive motor DMa by regenerative braking. And has a function of charging the secondary battery BTa.
  • the secondary battery BTa functions as a surplus power storage source, a regenerative energy storage source during regenerative braking, and an energy buffer during load fluctuations associated with acceleration or deceleration of the fuel cell vehicle.
  • a secondary battery such as a nickel / cadmium storage battery, a nickel / hydrogen storage battery, or a lithium secondary battery is suitable.
  • the secondary battery BTa is provided with an SOC sensor Tg for measuring the charging rate.
  • Traction inverter is connected to the drive motor DMa.
  • the traction inverter is, for example, a PWM inverter driven by a pulse width modulation method.
  • the traction inverter converts the DC voltage output from the fuel cell FC or the secondary battery BTa into a three-phase AC voltage in accordance with a control command from the controller ECU, and controls the rotational torque of the drive motor DMa.
  • the drive motor DMa is a three-phase AC motor, for example, and constitutes a power source of the fuel cell vehicle.
  • the cooling system CS has a main radiator RMa and a water pump WPa.
  • the main radiator RMa is provided with a main radiator fan.
  • the main radiator RMa radiates and cools the coolant for cooling the fuel cell FC.
  • the water pump WPa is a pump for circulating the coolant between the fuel cell FC and the main radiator RMa. By operating the water pump WPa, the coolant flows from the main radiator RMa to the fuel cell FC through the coolant forward path.
  • This fuel cell system FS includes a controller ECU (output supply unit) as an integrated control means.
  • the controller ECU is a computer system including a CPU, a ROM, a RAM, and an input / output interface, and controls each part of the fuel cell system FS. For example, when the controller ECU receives the start signal IG output from the ignition switch, the controller ECU starts the operation of the fuel cell system FS. Thereafter, the controller ECU obtains the required power of the entire fuel cell system FS based on the accelerator opening signal ACC output from the accelerator sensor, the vehicle speed signal VC output from the vehicle speed sensor, and the like. The required power of the entire fuel cell system FS is the total value of the vehicle travel power and the auxiliary power.
  • auxiliary electric power includes electric power consumed by in-vehicle auxiliary equipment (humidifier, air compressor, hydrogen pump, cooling water circulation pump, etc.), and equipment required for vehicle travel (transmission, wheel control device, steering) Power consumed by devices, suspension devices, etc.), power consumed by devices (air conditioners, lighting equipment, audio, etc.) disposed in the passenger space, and the like.
  • in-vehicle auxiliary equipment humidity, air compressor, hydrogen pump, cooling water circulation pump, etc.
  • equipment required for vehicle travel transmission, wheel control device, steering
  • devices air conditioners, lighting equipment, audio, etc.
  • the controller ECU determines the distribution of output power between the fuel cell FC and the secondary battery BTa.
  • the controller ECU controls the oxidizing gas supply system ASS and the fuel gas supply system FSS so that the power generation amount of the fuel cell FC matches the target power, and also controls the FC booster FDC to operate the fuel cell FC. (Output voltage, output current) is controlled.
  • the controller ECU outputs, for example, each of the U-phase, V-phase, and W-phase AC voltage command values to the traction inverter as a switching command so that a target torque corresponding to the accelerator opening is obtained, and the drive motor DMa Controls output torque and rotation speed. Further, the controller ECU controls the cooling system CS so that the fuel cell FC reaches an appropriate temperature.
  • FIG. 2 is a timing chart showing operation control of the fuel cell system FS. 2, (A) shows the control flag, (B) shows the output voltage of the fuel cell FC, (C) shows the output current of the fuel cell FC, and (D) shows the air The drive current of the compressor 62 is shown, (E) shows the battery power of the secondary battery BTa.
  • the fuel cell system FS improves the power generation efficiency by switching the operation mode of the fuel cell FC according to the operation load.
  • the fuel cell system FS controls the operation by setting the power generation command value of the fuel cell FC to zero in a low load region where the power generation efficiency is low (an operation region where the power generation request is less than a predetermined value), and is required for vehicle travel. Electric power and electric power necessary for system operation are covered by electric power from the secondary battery BTa (hereinafter referred to as first operation mode).
  • the power generation command value of the fuel cell FC is calculated based on the accelerator opening, the vehicle speed, etc.
  • the necessary power and the power necessary for system operation are covered only by the power generated by the fuel cell FC or by the power generated by the fuel cell FC and the power from the secondary battery BTa (hereinafter referred to as the second operation mode).
  • the fuel cell system FS monitors a control flag indicating the operation mode at a constant cycle. When the control flag is turned on, the fuel cell system FS controls the operation in the first operation mode. When the control flag is turned off, the fuel cell system FS enters the second operation mode. Control the operation. In any operation mode, the output voltage of the fuel cell FC during normal operation is basically limited to the operation range between the upper limit voltage V1 and the lower limit voltage V2.
  • the use upper limit voltage V1 is preferably a voltage that satisfies the condition that the platinum catalyst contained in the catalyst layer of the fuel cell FC is in a voltage range that does not elute, and in addition to that condition, the fuel cell A condition that the voltage range is such that the power generated by the fuel cell FC can be consumed by the auxiliary equipment when the output voltage of the fuel cell FC is maintained at the upper limit voltage V1 while the supply of the reactive gas to the FC is stopped. It is preferable that the voltage satisfies the above. In the fuel cell FC, there is a possibility that the platinum catalyst in the catalyst layer may be eluted particularly when the potential of the cathode electrode is kept high, such as during low density current operation or idle operation.
  • controlling the output voltage of the fuel cell FC to the use upper limit voltage V1 or less and maintaining the durability of the fuel cell FC is referred to as high potential avoidance control.
  • the upper limit voltage V1 is the high potential avoidance voltage described above.
  • high potential avoidance control is executed in principle in any operation mode.
  • the use upper limit voltage V1 is adjusted according to the temperature of the fuel cell FC (the mode of adjustment will be described later).
  • the lower limit voltage V2 is preferably a voltage that satisfies the condition that the cell voltage does not fall into the reduction region.
  • the output voltage of the fuel cell FC during normal operation is controlled to be equal to or higher than the use lower limit voltage V2, so that a decrease in durability of the fuel cell FC can be suppressed.
  • the lower limit voltage V2 is preferably set so that the voltage is about 0.8 V per cell, for example.
  • the output voltage of the fuel cell FC during normal operation is controlled between the upper limit voltage V1 and the lower limit voltage V2, but the output voltage of the fuel cell FC is set to the upper limit for system operation.
  • the voltage is controlled to be equal to or higher than the voltage V1, or is controlled to be lower than the use lower limit voltage V2.
  • the SOC of the secondary battery BTa is greater than or equal to a predetermined value
  • the output voltage of the fuel cell FC is raised to the open end voltage.
  • the catalyst activation process is performed, the output voltage of the fuel cell FC is lowered to the use lower limit voltage V2 or less.
  • the controller ECU sets the power generation command value to zero, stops the reaction gas supply to the fuel cell FC, and sets the voltage command value to the fuel cell boost converter to the use upper limit voltage V1. (Time t0 to t4). Even after the supply of the reaction gas is stopped, the unreacted reaction gas remains in the fuel cell FC, so the fuel cell FC generates a small amount of power for a while.
  • the period from time t0 to t2 is a power generation period in which a minute amount of power generation is continued by converting the chemical energy of the residual reaction gas into electric energy.
  • the residual reaction gas has enough energy for the output voltage of the fuel cell FC to maintain the use upper limit voltage V1, so the output voltage of the fuel cell FC continues to maintain the use upper limit voltage V1.
  • the electric power generated during this power generation period is consumed by the auxiliary machinery, but when the auxiliary machinery cannot fully consume it, the secondary battery BTa is charged.
  • the period from the time t2 to the time t4 is a power generation stop period in which the output voltage of the fuel cell FC can no longer be maintained at the use upper limit voltage V1 due to the consumption of the residual reaction gas and the power generation is stopped.
  • the power generation is stopped, and the output voltage of the fuel cell FC gradually decreases.
  • the power generation energy of the fuel cell FC becomes zero, so the power supplied from the secondary battery BTa to the auxiliary machines is almost constant.
  • the oxidizing gas supply system ASS is driven to supply the fuel cell FC with oxidizing gas. Since the fuel cell FC generates electric power upon replenishment of the oxidizing gas, the output voltage of the fuel cell FC starts to increase. When the output voltage of the fuel cell FC is increased to a predetermined voltage, the oxidizing gas supply is finished. As described above, during the power generation stop period, the oxidant gas is appropriately supplied whenever the output voltage of the fuel cell FC decreases to the use lower limit voltage V2, and the output voltage is controlled not to fall below the use lower limit voltage V2.
  • the controller ECU calculates the power generation command value according to the required load, controls the supply of the reaction gas to the fuel cell FC, and operates the fuel cell FC operating point (The output voltage and output current are controlled (time t4 to time t5). At this time, the voltage command value to the fuel cell boost converter is limited to an operation range between the upper limit voltage V1 and the lower limit voltage V2.
  • the controller ECU and the fuel cell boost converter functioning as the output supply unit adjust the power supplied from the fuel cell FC to the required power required by the load (drive motor DMa and auxiliary machinery). Supply.
  • the output supply unit suppresses the supply of the reaction gas to the fuel cell FC and maintains the output voltage of the fuel cell FC at a high potential avoidance voltage lower than the open-circuit voltage.
  • the output voltage of the fuel cell is controlled with the high potential avoidance voltage as the upper limit.
  • the controller ECU and the fuel cell boost converter functioning as an output supply unit adjust the high potential avoidance voltage according to the measured and / or estimated temperature of the fuel cell FC (cell stack).
  • the controller ECU and the fuel cell boost converter functioning as an output supply unit adjust the high potential avoidance voltage according to the measured and / or estimated temperature of the fuel cell FC (cell stack).
  • the controller ECU functioning as an output supply unit and the fuel cell boost converter have a temperature of the fuel cell FC (cell stack) higher than the first high potential avoidance voltage when the temperature of the fuel cell FC (cell stack) is the first temperature.
  • the second high potential avoidance voltage in the case of the second temperature lower than the first temperature is set high.
  • the second high potential avoidance voltage when the temperature of the fuel cell FC (cell stack) is the second temperature lower than the first temperature is the same as that when the temperature of the fuel cell FC (cell stack) is the first temperature. Since it is set higher than the first high potential avoidance voltage, the high potential avoidance voltage can be increased when the temperature of the fuel cell FC (cell stack) is low, and the surplus power of the fuel cell FC (cell stack) is suppressed. Can do.
  • FIG. 3 is a graph showing the relationship between the decrease in performance of the fuel cell and the temperature.
  • the horizontal axis indicates the temperature (temperature of the cell stack of the fuel cell FC), and the vertical axis indicates the activation overvoltage increase amount indicating the amount of performance decrease of the fuel cell FC.
  • the thick line in the graph shown in FIG. 3 is the upper limit of the activation overvoltage increase amount as the allowable range, and control is required so that the activation overvoltage increase amount falls below the thick line.
  • the temperature of the cell stack of the fuel cell FC is 0 ° C., even if the high potential avoidance voltage is 1.0 V, the performance degradation of the fuel cell FC is within an allowable range.
  • the high potential avoidance voltage may be 0.95V
  • the temperature of the cell stack of the fuel cell FC is 40 ° C., the high potential avoidance voltage May be 0.9V.
  • the graph shown in FIG. 4 shows the relationship between the temperature of the cell stack of the fuel cell FC and the upper limit voltage based on such a relationship.
  • the horizontal axis represents temperature (temperature of the cell stack of the fuel cell FC), and the vertical axis represents high potential avoidance voltage (upper limit voltage).
  • the upper limit voltage when the temperature is 0 ° C. or lower is 1.0 V
  • the upper limit voltage when 0 to 20 ° C. is 0.95 V
  • the upper limit voltage when 20 to 40 ° C. is 0.93 V
  • 40 to The upper limit voltage at 60 ° C. is 0.90 V
  • the upper limit voltage at 60 to 80 ° C. is 0.87 V
  • the upper limit voltage at 80 to 100 ° C. is 0.85 V.
  • the controller ECU has a function as an elapsed time measuring unit that measures the elapsed time after the fuel cell system FS is stopped.
  • the controller ECU determines the outside air temperature at the start of the fuel cell system FS, the temperature of the fuel cell FC (cell stack) at the time of stop, the elapsed time after the stop, and the temperature of the fuel cell FC (cell stack) corresponding thereto , And a function as a correlation holding unit for storing the correlation.
  • the controller ECU measures the outside air temperature measured by the temperature sensor Tf functioning as the outside air temperature measurement unit, the temperature of the fuel cell FC (cell stack) at the time of stop measured by the temperature sensor Td functioning as the stack temperature measurement unit, and the post-stop The temperature of the fuel cell FC (cell stack) corresponding to the elapsed time is acquired.
  • the controller ECU regards the obtained temperature of the fuel cell FC (cell stack) as the temperature of the fuel cell FC (cell stack) at the time of starting, and adjusts the high potential avoidance voltage.
  • the high potential avoidance voltage is adjusted according to the measured and / or estimated temperature of the fuel cell FC (cell stack).
  • the outlet of the cooling water of the fuel cell FC (cell stack) It is replaced by measuring temperature.
  • the outlet temperature of the cooling water may be regarded as the temperature of the fuel cell FC (cell stack).
  • the cooling water does not circulate, and the cooling water often does not accurately represent the temperature of the fuel cell FC (cell stack).
  • the outside air temperature at the start of the fuel cell system FS the stop temperature of the fuel cell FC (cell stack) at the time of stop, the elapsed time after the stop, and the temperature of the fuel cell FC (cell stack) corresponding thereto , And the temperature of the fuel cell FC (cell stack) is acquired using the measured outside air temperature, the temperature of the fuel cell FC (cell stack), and the elapsed time after the stop.
  • the temperature thus obtained as the temperature of the fuel cell FC (cell stack) at the time of starting the temperature of the fuel cell FC (cell stack) at the time of starting can be estimated more accurately, and the high potential avoidance voltage The adjustment will be appropriate.
  • the secondary battery BTa capable of charging and discharging electricity
  • the temperature sensor Th as a battery temperature measuring unit for measuring the temperature of the secondary battery BTa
  • an SOC sensor Tg as a charge rate measuring unit to be measured.
  • the controller ECU as the correlation holding unit stores the correlation between the temperature of the secondary battery BTa and the charging rate of the secondary battery BTa, and the maximum absorbable power of the secondary battery BTa corresponding to them.
  • the controller ECU, the fuel cell boost converter, and the battery boost converter functioning as an output supply unit are supplied with power supplied from the fuel cell FC and the secondary battery BTa according to the required power required by the load.
  • the power is supplied while adjusting the power, and the temperature of the secondary battery BTa measured by the temperature sensor Th that is a battery temperature measuring unit and the charging of the secondary battery BTa measured by the SOC sensor Tg that is a charging rate measuring unit.
  • the maximum absorbable power of the secondary battery BTa corresponding to the rate is acquired, and the high potential avoidance voltage is adjusted using the acquired maximum absorbable power.
  • the controller ECU stores the correlation between the temperature of the secondary battery BTa, the charging rate of the secondary battery BTa, and the maximum absorbable power of the secondary battery BTa corresponding to them, and the output supply unit Then, the maximum absorbable power is acquired using the actually measured temperature and charging rate of the secondary battery BTa.
  • FIG. 5 shows the relationship between the output of the fuel cell FC and the allowable power (maximum absorbable power) of the secondary battery BTa.
  • FIG. 5A shows the output of the fuel cell FC
  • FIG. 5B shows the maximum absorbable power of the secondary battery BTa.
  • the maximum power that can be absorbed by the secondary battery BTa is extremely small, and the degree of reduction is greater than the reduction in the output of the fuel cell FC. Therefore, as described above, it is preferable to estimate the maximum absorbable power of the secondary battery BTa according to the temperature.

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Abstract

This fuel cell system adjusts an upper limit voltage, which is a voltage for avoiding high potential in a fuel cell, according to the measured and/or estimated temperature of a cell stack.

Description

燃料電池システムFuel cell system
　本発明は、燃料電池システムに関する。 The present invention relates to a fuel cell system.
　このような燃料電池システムとして、システムに含まれる燃料電池が、電解質膜を挟んで配置され、それぞれが触媒を有する燃料極および酸化剤極を有する燃料電池であるものが知られている。さらに、燃料電池が発電を行わない場合には、燃料電池の電圧を制御し、酸化剤極を標準水素電極に対して０．８Ｖから０．９Ｖの電位となるように制御し、例えば白金などの触媒が溶出しないようにするものが下記特許文献１に開示されている。 As such a fuel cell system, there is known a fuel cell in which fuel cells included in the system are arranged with an electrolyte membrane interposed therebetween, and each has a fuel electrode having a catalyst and an oxidant electrode. Further, when the fuel cell does not generate power, the voltage of the fuel cell is controlled, and the oxidant electrode is controlled to have a potential of 0.8 V to 0.9 V with respect to the standard hydrogen electrode, such as platinum. Patent Document 1 below discloses that the catalyst is not eluted.
特開２００８－２１８３９８号公報JP 2008-218398 A
　上述した特許文献１に記載の燃料電池システムは、燃料電池の触媒溶出を抑制する効果の側面からは優れたシステムである。しかしながら、燃料電池の出力端子電圧を開放端電圧に維持するように制御すれば燃料電池から電流が流出しないところ、燃料電池の出力端子電圧を開放端電圧よりも低い高電位回避電圧を超えないように制御すると、その差分に応じた電流が流出する。 The above-described fuel cell system described in Patent Document 1 is an excellent system from the aspect of suppressing the elution of the catalyst of the fuel cell. However, if the control is performed so that the output terminal voltage of the fuel cell is maintained at the open end voltage, no current flows out from the fuel cell, so that the output terminal voltage of the fuel cell does not exceed the high potential avoidance voltage lower than the open end voltage. When the control is performed, the current corresponding to the difference flows out.
　従って、触媒保護の観点からは高電位回避電圧を超えないように燃料電池を制御することが好ましいものの、燃費の観点からは出力端子電圧を上げて電流の流出を抑制することが好ましい。 Therefore, although it is preferable to control the fuel cell so as not to exceed the high potential avoidance voltage from the viewpoint of catalyst protection, it is preferable to suppress the outflow of current by increasing the output terminal voltage from the viewpoint of fuel consumption.
　本発明はこのような課題に鑑みてなされたものであり、その目的は、燃料電池を備える燃料電池システムであって、燃料電池の触媒溶出を抑制しつつ燃費の向上も図ることが可能な燃料電池システムを提供することにある。 The present invention has been made in view of such problems, and an object of the present invention is a fuel cell system including a fuel cell, which can improve fuel efficiency while suppressing catalyst elution of the fuel cell. It is to provide a battery system.
　上記課題を解決するために本発明に係る燃料電池システムは、反応ガスの供給を受けて発電する複数の単セルからなるセルスタックを有する燃料電池と、セルスタックの温度を測定するスタック温度測定部と、燃料電池に電気的に接続されてなる負荷と、負荷が必要とする要求電力を、燃料電池から供給される電力を調整しながら供給する出力供給部と、を備える。出力供給部は、要求電力が所定電力未満の場合に、燃料電池への反応ガス供給を抑制すると共に燃料電池の出力電圧が開放端電圧よりも低い高電位回避電圧に維持されるように制御し、要求電力が所定電力以上の場合、高電位回避電圧を上限として燃料電池の出力電圧を制御するものであって、測定され及び／又は推測されたセルスタックの温度に応じて高電位回避電圧を調整する。 In order to solve the above problems, a fuel cell system according to the present invention includes a fuel cell having a cell stack composed of a plurality of single cells that generate power upon receiving a supply of a reaction gas, and a stack temperature measuring unit that measures the temperature of the cell stack And a load that is electrically connected to the fuel cell, and an output supply unit that supplies the required power required by the load while adjusting the power supplied from the fuel cell. The output supply unit controls the supply of the reaction gas to the fuel cell when the required power is less than the predetermined power, and controls the output voltage of the fuel cell to be maintained at a high potential avoidance voltage lower than the open-circuit voltage. When the required power is equal to or higher than the predetermined power, the output voltage of the fuel cell is controlled with the high potential avoidance voltage as an upper limit, and the high potential avoidance voltage is set according to the measured and / or estimated temperature of the cell stack. adjust.
　本発明者は、燃料電池の出力電圧が酸化還元電電位を跨いで変動した場合の触媒溶出の度合いが、セルスタックの温度に依存して変動することに着目した。具体的には、セルスタックの温度が低い場合には、高電位回避電圧をある程度上げたとしても触媒の溶出度合いが許容範囲内に収まることを見出した。本発明はこの知見に基づくものであり、測定され及び／又は推測されたセルスタックの温度に応じて高電位回避電圧を調整することで、燃料電池の触媒溶出を抑制しつつ、燃費の向上も図ることができるものとしている。 The inventors of the present invention have focused on the fact that the degree of catalyst elution when the output voltage of the fuel cell fluctuates across the redox potential varies depending on the temperature of the cell stack. Specifically, it has been found that when the temperature of the cell stack is low, the elution degree of the catalyst falls within an allowable range even if the high potential avoidance voltage is increased to some extent. The present invention is based on this finding, and by adjusting the high potential avoidance voltage according to the measured and / or estimated temperature of the cell stack, fuel elution can be improved while suppressing catalyst elution of the fuel cell. It can be planned.
　また本発明に係る燃料電池システムでは、出力供給部は、セルスタックの温度が第一温度の場合の第一高電位回避電圧よりも、セルスタックの温度が第一温度よりも低い第二温度の場合の第二高電位回避電圧を高く設定することも好ましい。 In the fuel cell system according to the present invention, the output supply unit has a second temperature lower than the first temperature than the first high potential avoidance voltage when the cell stack temperature is the first temperature. In this case, it is also preferable to set the second high potential avoidance voltage high.
　この好ましい態様では、セルスタックの温度が第一温度よりも低い第二温度の場合の第二高電位回避電圧を、セルスタックの温度が第一温度の場合の第一高電位回避電圧よりも高く設定するので、セルスタックの温度が低い場合の高電位回避電圧を上げることができ、セルスタックの余剰電力を抑制することができる。 In this preferred embodiment, the second high potential avoidance voltage when the cell stack temperature is the second temperature lower than the first temperature is higher than the first high potential avoidance voltage when the cell stack temperature is the first temperature. Therefore, the high potential avoidance voltage when the temperature of the cell stack is low can be increased, and surplus power of the cell stack can be suppressed.
　また本発明に係る燃料電池システムでは、外気温度を測定する外気温度測定部と、この燃料電池システムの停止後の経過時間を測定する経過時間測定部と、この燃料電池システムの始動時の外気温度、停止時におけるセルスタックの停止温度、及び停止後の経過時間と、それらに対応するセルスタックの温度と、の相関関係を格納する相関保持部と、を備えることが好ましい。この好ましい態様において出力供給部は、外気温度測定部が測定した外気温度、スタック温度測定部が測定した停止時におけるセルスタックの温度、及び経過時間測定部が測定した停止後の経過時間に対応するセルスタックの温度を相関保持部から取得し、当該取得した温度を始動時のセルスタックの温度とみなし、高電位回避電圧を調整する。 Further, in the fuel cell system according to the present invention, the outside air temperature measuring unit for measuring the outside air temperature, the elapsed time measuring unit for measuring the elapsed time after the stop of the fuel cell system, and the outside air temperature at the start of the fuel cell system It is preferable to include a correlation holding unit that stores a correlation between the stop temperature of the cell stack at the time of stop and the elapsed time after the stop and the temperature of the cell stack corresponding to the stop time. In this preferred embodiment, the output supply unit corresponds to the outside temperature measured by the outside temperature measuring unit, the temperature of the cell stack at the time of stop measured by the stack temperature measuring unit, and the elapsed time after the stop measured by the elapsed time measuring unit. The temperature of the cell stack is acquired from the correlation holding unit, and the acquired temperature is regarded as the temperature of the cell stack at the start, and the high potential avoidance voltage is adjusted.
　本発明では上述したように、測定され及び／又は推測されたセルスタックの温度に応じて高電位回避電圧を調整する。セルスタックの温度をより正確に知るためにはセルスタックの温度を直接測定することが望ましいけれども、実際にはセルスタックの冷却水の出口温度を測定することで代替することが行われている。燃料電池システムが運転状態にあり冷却水が循環している状態では、冷却水の出口温度をセルスタックの温度とみなしてよい。しかしながら、燃料電池システムが停止状態にあると冷却水は循環しておらず、冷却水がセルスタックの温度を的確に表していないことが多い。そこでこの好ましい態様では、相関保持部に、この燃料電池システムの始動時の外気温度、停止時におけるセルスタックの停止温度、及び停止後の経過時間と、それらに対応するセルスタックの温度と、の相関関係を格納しておき、出力供給部が、実測した外気温度、セルスタックの温度、及び停止後の経過時間を用いてセルスタックの温度を取得する。このように取得した温度を始動時のセルスタックの温度とみなすことで、より的確に始動時のセルスタックの温度を推測することができ、高電位回避電圧の調整が適切なものとなる。 In the present invention, as described above, the high potential avoidance voltage is adjusted according to the measured and / or estimated temperature of the cell stack. Although it is desirable to directly measure the temperature of the cell stack in order to know the temperature of the cell stack more accurately, in practice, an alternative is to measure the outlet temperature of the cooling water of the cell stack. When the fuel cell system is in an operating state and the cooling water is circulating, the outlet temperature of the cooling water may be regarded as the temperature of the cell stack. However, when the fuel cell system is in a stopped state, the cooling water does not circulate, and the cooling water often does not accurately represent the temperature of the cell stack. Therefore, in this preferred embodiment, the correlation holding unit includes the outside air temperature at the start of the fuel cell system, the stop temperature of the cell stack at the time of stop, the elapsed time after the stop, and the temperature of the cell stack corresponding thereto. The correlation is stored, and the output supply unit acquires the temperature of the cell stack using the actually measured outside air temperature, the temperature of the cell stack, and the elapsed time after the stop. By regarding the temperature thus obtained as the temperature of the cell stack at the time of starting, the temperature of the cell stack at the time of starting can be estimated more accurately, and the adjustment of the high potential avoidance voltage becomes appropriate.
　また本発明に係る燃料電池システムでは、電気を充電及び放電することが可能な二次電池と、二次電池の温度を測定する電池温度測定部と、二次電池の充電率を測定する充電率測定部と、を備え、相関保持部は、二次電池の温度及び二次電池の充電率と、それらに対応する二次電池の最大吸収可能電力と、の相関関係を格納することが好ましい。この好ましい態様において出力供給部は、負荷が必要とする要求電力に応じた電力を、燃料電池から供給される電力および二次電池から供給される電力を調整しながら供給するものであって、電池温度測定部が測定した二次電池の温度と、充電率測定部が測定した二次電池の充電率とに対応する二次電池の最大吸収可能電力を相関保持部から取得し、当該取得した最大吸収可能電力を用いて高電位回避電圧を調整する。 In the fuel cell system according to the present invention, a secondary battery capable of charging and discharging electricity, a battery temperature measuring unit for measuring the temperature of the secondary battery, and a charging rate for measuring the charging rate of the secondary battery The correlation holding unit preferably stores a correlation between the temperature of the secondary battery, the charging rate of the secondary battery, and the maximum absorbable power of the secondary battery corresponding to the temperature. In this preferred embodiment, the output supply unit supplies power corresponding to the required power required by the load while adjusting the power supplied from the fuel cell and the power supplied from the secondary battery. The maximum absorbable power of the secondary battery corresponding to the temperature of the secondary battery measured by the temperature measuring unit and the charging rate of the secondary battery measured by the charging rate measuring unit is acquired from the correlation holding unit, and the acquired maximum The high potential avoidance voltage is adjusted using the absorbable power.
　本発明では上述したように、セルスタックの温度が低い場合の高電位回避電圧を上げることができ、セルスタックの余剰電力を抑制することができる。更に、電気を充電及び放電可能な二次電池を備える場合には、余剰電力を二次電池で吸収することができるので、二次電池の最大吸収可能電力を考慮することが好ましい。そこでこの好ましい態様では、相関保持部に、二次電池の温度及び二次電池の充電率と、それらに対応する二次電池の最大吸収可能電力と、の相関関係を格納しておき、出力供給部が、実測した二次電池の温度及び充電率を用いて最大吸収可能電力を取得する。このように取得した最大吸収可能電力を用いて高電位回避電圧を調整することで、特に低温度領域で余力がなくなると想定される最大吸収可能電力に対応した余剰電力を発生させることができ、二次電池の耐久性悪化が抑制できる。 In the present invention, as described above, the high potential avoidance voltage when the temperature of the cell stack is low can be increased, and surplus power of the cell stack can be suppressed. Furthermore, when a secondary battery capable of charging and discharging electricity is provided, surplus power can be absorbed by the secondary battery, and therefore it is preferable to consider the maximum absorbable power of the secondary battery. Therefore, in this preferred embodiment, the correlation holding unit stores the correlation between the temperature of the secondary battery, the charging rate of the secondary battery, and the maximum absorbable power of the secondary battery corresponding to them, and supplies the output. The unit acquires the maximum absorbable power using the measured temperature and charging rate of the secondary battery. By adjusting the high potential avoidance voltage using the maximum absorbable power acquired in this way, it is possible to generate surplus power corresponding to the maximum absorbable power that is assumed to have no remaining power, particularly in the low temperature region, The deterioration of the durability of the secondary battery can be suppressed.
　本発明によれば、燃料電池の触媒溶出を抑制しつつ燃費の向上も図ることが可能な燃料電池システムを提供することができる。 According to the present invention, it is possible to provide a fuel cell system capable of improving fuel consumption while suppressing catalyst elution of the fuel cell.
本発明の実施形態に係る燃料電池システムの構成を示す概略構成図である。1 is a schematic configuration diagram showing a configuration of a fuel cell system according to an embodiment of the present invention. 図１に示す燃料電池システムの運転制御を示すタイミングチャートである。It is a timing chart which shows the operation control of the fuel cell system shown in FIG. 燃料電池の性能低下と温度との関係を示すグラフである。It is a graph which shows the relationship between the performance fall of a fuel cell, and temperature. セルスタックの温度と上限電圧との関係を示すグラフである。It is a graph which shows the relationship between the temperature of a cell stack, and an upper limit voltage. 温度と燃料電池の出力及び温度と二次電池許容電力との関係を示すグラフである。It is a graph which shows the relationship between temperature, the output of a fuel cell, temperature, and secondary battery allowable power.
　以下、添付図面を参照しながら本発明の実施の形態について説明する。説明の理解を容易にするため、各図面において同一の構成要素に対しては可能な限り同一の符号を付して、重複する説明は省略する。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.
　最初に、本発明の実施形態である燃料電池車両に搭載される燃料電池システムＦＳについて図１を参照しながら説明する。図１は燃料電池車両の車載電源システムとして機能する燃料電池システムＦＳのシステム構成を示す図である。燃料電池システムＦＳは、燃料電池自動車（ＦＣＨＶ）、電気自動車、ハイブリッド自動車などの車両に搭載することができる。 First, a fuel cell system FS mounted on a fuel cell vehicle according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a system configuration of a fuel cell system FS that functions as an in-vehicle power supply system for a fuel cell vehicle. The fuel cell system FS can be mounted on a vehicle such as a fuel cell vehicle (FCHV), an electric vehicle, or a hybrid vehicle.
　燃料電池システムＦＳは、燃料電池ＦＣと、酸化ガス供給系ＡＳＳと、燃料ガス供給系ＦＳＳと、駆動系ＨＶＳと、冷却系ＣＳと、を備えている。 The fuel cell system FS includes a fuel cell FC, an oxidizing gas supply system ASS, a fuel gas supply system FSS, a drive system HVS, and a cooling system CS.
　酸化ガス供給系ＡＳＳは、酸化ガスとしての空気を燃料電池ＦＣに供給するための系である。燃料ガス供給系ＦＳＳは、燃料ガスとしての水素ガスを燃料電池ＦＣに供給するための系である。駆動系ＨＶＳは、駆動モーターＤＭａに電力を供給して駆動する系であって、ハイブリッドシステムを構成する系である。冷却系ＣＳは、燃料電池ＦＣを冷却するための系である。駆動モーターＤＭａは、車輪９２，９２を駆動するモーターである。 The oxidizing gas supply system ASS is a system for supplying air as oxidizing gas to the fuel cell FC. The fuel gas supply system FSS is a system for supplying hydrogen gas as fuel gas to the fuel cell FC. The drive system HVS is a system that drives by supplying electric power to the drive motor DMa, and constitutes a hybrid system. The cooling system CS is a system for cooling the fuel cell FC. The drive motor DMa is a motor that drives the wheels 92 and 92.
　燃料電池系ＦＣＳについて説明する。燃料電池系ＦＣＳが含む燃料電池ＦＣは、多数のセルＣＥ（アノード、カソード、及び電解質を備える単一の電池（発電体））を直列に積層してなる固体高分子電解質形のセルスタックとして構成されている。燃料電池ＦＣでは、通常の運転において、アノードにおいて（１）式の酸化反応が生じ、カソードにおいて（２）式の還元反応が生じる。燃料電池ＦＣ全体としては（３）式の起電反応が生じる。
Ｈ2→２Ｈ+＋２ｅ-　　　　　　　　　　　（１）
（１／２）Ｏ2＋２Ｈ+＋２ｅ-→Ｈ2Ｏ　　　　（２）
Ｈ2＋（１／２）Ｏ2→Ｈ2Ｏ　　　　　　　　（３） The fuel cell system FCS will be described. The fuel cell FC included in the fuel cell system FCS is configured as a solid polymer electrolyte type cell stack formed by stacking a number of cells CE (a single battery (a power generator) including an anode, a cathode, and an electrolyte) in series. Has been. In a normal operation, the fuel cell FC undergoes an oxidation reaction of formula (1) at the anode and a reduction reaction of formula (2) at the cathode. The fuel cell FC as a whole undergoes an electromotive reaction of the formula (3).
H 2 → 2H + + 2e − (1)
(1/2) O 2 + 2H + + 2e − → H 2 O (2)
H 2 + (1/2) O 2 → H 2 O (3)
　更に、燃料電池系ＦＣＳは、燃料電池ＦＣと燃料ガス供給系ＦＳＳとを繋ぐ領域に、水素ポンプＨＰａと、排気排水弁ＥＶｃと、を有している。 Furthermore, the fuel cell system FCS has a hydrogen pump HPa and an exhaust / drain valve EVc in a region connecting the fuel cell FC and the fuel gas supply system FSS.
　燃料電池ＦＣに供給された燃料ガスは、燃料電池ＦＣの内部で起電反応に寄与し、オフガスとして燃料電池ＦＣから排出される。燃料電池ＦＣから排出された燃料オフガスは、一部は水素ポンプＨＰａによって還流され、燃料ガス供給系ＦＳＳから供給される燃料ガスと共に燃料電池ＦＣに再供給される。また、燃料オフガスの一部は排気排水弁ＥＶｃの作動によって、燃料オフガス流路ＦＳ２を通って、酸化オフガスと共に排出される。 The fuel gas supplied to the fuel cell FC contributes to the electromotive reaction inside the fuel cell FC, and is discharged from the fuel cell FC as off-gas. Part of the fuel off-gas discharged from the fuel cell FC is recirculated by the hydrogen pump HPa and re-supplied to the fuel cell FC together with the fuel gas supplied from the fuel gas supply system FSS. Further, part of the fuel off-gas is discharged together with the oxidation off-gas through the fuel off-gas flow path FS2 by the operation of the exhaust drain valve EVc.
　排気排水弁ＥＶｃは、コントローラーＥＣＵからの指令によって作動することにより、循環流路内の不純物を含む燃料オフガスと水分とを外部に排出するための弁である。排気排水弁ＥＶｃの開弁により、循環流路内の燃料オフガス中の不純物の濃度が下がり、循環系内を循環する燃料オフガス中の水素濃度を上げることができる。 The exhaust / drain valve EVc is a valve for discharging the fuel off-gas containing impurities in the circulation flow path and moisture to the outside by operating according to a command from the controller ECU. By opening the exhaust / drain valve EVc, the concentration of impurities in the fuel off-gas in the circulation flow path can be lowered, and the hydrogen concentration in the fuel off-gas circulating in the circulation system can be increased.
　排気排水弁ＥＶｃを介して排出される燃料オフガスは、酸化オフガス流路ＡＳ２を流れる酸化オフガスと混合され、希釈器（図１に明示せず）によって希釈されマフラー（図１に明示せず）に供給される。 The fuel off-gas discharged through the exhaust / drain valve EVc is mixed with the oxidant off-gas flowing through the oxidant off-gas passage AS2, diluted by a diluter (not explicitly shown in FIG. 1), and sent to the muffler (not explicitly shown in FIG. 1). Supplied.
　続いて、燃料ガス供給系ＦＳＳについて説明する。燃料ガス供給系ＦＳＳは、高圧水素タンクＦＳ１と、電磁弁ＤＶａとを有している。 Subsequently, the fuel gas supply system FSS will be described. The fuel gas supply system FSS has a high-pressure hydrogen tank FS1 and a solenoid valve DVa.
　高圧水素タンクＦＳ１は、高圧（例えば、３５ＭＰａ～７０ＭＰａ）の水素ガスを貯蔵するものである。 The high-pressure hydrogen tank FS1 stores high-pressure (for example, 35 MPa to 70 MPa) hydrogen gas.
　電磁弁ＤＶａは、燃料ガスの燃料電池ＦＣに対する供給圧力を調整しつつ、燃料ガスの燃料電池ＦＣへの供給・停止を調整する弁である。燃料ガスは、電磁弁ＤＶａにより、例えば、２００ｋＰａ程度まで減圧されて、燃料電池ＦＣに供給される。 The solenoid valve DVa is a valve that adjusts the supply / stop of the fuel gas to the fuel cell FC while adjusting the supply pressure of the fuel gas to the fuel cell FC. The fuel gas is decompressed to about 200 kPa, for example, by the electromagnetic valve DVa and supplied to the fuel cell FC.
　続いて、酸化ガス供給系ＡＳＳについて説明する。酸化ガス供給系ＡＳＳは、エアコンプレッサー６２と、ＦＣ入口三方弁ＴＶａと、統合弁ＤＶｂとを備えている。酸化ガス供給系ＡＳＳは、燃料電池ＦＣのカソードに供給される酸化ガスとしての空気が流れる酸化ガス流路ＡＳ１と、燃料電池ＦＣから排出される酸化オフガスが流れる酸化オフガス流路ＡＳ２とを有している。 Subsequently, the oxidizing gas supply system ASS will be described. The oxidizing gas supply system ASS includes an air compressor 62, an FC inlet three-way valve TVa, and an integrated valve DVb. The oxidant gas supply system ASS has an oxidant gas passage AS1 through which air as an oxidant gas supplied to the cathode of the fuel cell FC flows, and an oxidant offgas passage AS2 through which the oxidant offgas discharged from the fuel cell FC flows. ing.
　エアコンプレッサー６２と、ＦＣ入口三方弁ＴＶａとは、酸化ガス流路ＡＳ１の入口側から燃料電池ＦＣに向かって順に配置されている。統合弁ＤＶｂは、酸化オフガス流路ＡＳ２に配置されている。統合弁ＤＶｂは、背圧調整弁として機能する。 The air compressor 62 and the FC inlet three-way valve TVa are sequentially arranged from the inlet side of the oxidizing gas flow path AS1 toward the fuel cell FC. The integrated valve DVb is disposed in the oxidation off gas flow path AS2. The integrated valve DVb functions as a back pressure adjustment valve.
　ＦＣ入口三方弁ＴＶａは、酸化ガス流路ＡＳ１を燃料電池ＦＣ側に流す空気と、酸化ガス流路ＡＳ１と酸化オフガス流路ＡＳ２とを繋ぐバイパス流路６９へ流す空気とを調整するための弁である。燃料電池ＦＣ側に多くの空気が必要とされる場合は、燃料電池ＦＣ側に多くの空気を流すように開度を調整し、燃料電池ＦＣ側に多くの空気が必要とされない場合は、バイパス流路６９側へ多くの空気を流すように開度を調整する。燃料電池ＦＣと統合弁ＤＶｂとの間には、圧力センサＰｔが設けられている。 The FC inlet three-way valve TVa is a valve for adjusting the air flowing through the oxidizing gas passage AS1 to the fuel cell FC side and the air flowing through the bypass passage 69 connecting the oxidizing gas passage AS1 and the oxidizing off-gas passage AS2. It is. If a large amount of air is required on the fuel cell FC side, adjust the opening so that a large amount of air flows on the fuel cell FC side. If a large amount of air is not required on the fuel cell FC side, bypass it. The opening degree is adjusted so that a large amount of air flows to the flow path 69 side. A pressure sensor Pt is provided between the fuel cell FC and the integrated valve DVb.
　続いて、駆動系ＨＶＳについて説明する。駆動系ＨＶＳは、燃料電池昇圧部と、パワーコントロールユニットと、二次電池ＢＴａと、を備える。燃料電池昇圧部は、燃料電池昇圧コンバーター（出力供給部）と、リレーとを有している。燃料電池昇圧コンバーターは、燃料電池ＦＣが発電した直流電力を昇圧してパワーコントロールユニットに供給する。この昇圧コンバーターによる電圧変換制御により、燃料電池ＦＣの運転ポイント（出力端子電圧、出力電流）が制御される。 Subsequently, the drive system HVS will be described. The drive system HVS includes a fuel cell booster, a power control unit, and a secondary battery BTa. The fuel cell boosting unit includes a fuel cell boosting converter (output supply unit) and a relay. The fuel cell boost converter boosts DC power generated by the fuel cell FC and supplies the boosted DC power to the power control unit. The voltage conversion control by the boost converter controls the operating point (output terminal voltage, output current) of the fuel cell FC.
　パワーコントロールユニットは、バッテリー昇圧コンバーターと、トラクションインバーターと、を有している。燃料電池昇圧コンバーターから供給された電力は、バッテリー昇圧コンバーター及びトラクションインバーターに供給される。 The power control unit has a battery boost converter and a traction inverter. The electric power supplied from the fuel cell boost converter is supplied to the battery boost converter and the traction inverter.
　バッテリー昇圧コンバーターは、二次電池ＢＴａから供給される直流電力を昇圧してトラクションインバーターに出力する機能と、燃料電池ＦＣが発電した直流電力、回生制動により駆動モーターＤＭａが回収した回生電力を降圧して二次電池ＢＴａに充電する機能を有する。 The battery boost converter boosts the DC power supplied from the secondary battery BTa and outputs it to the traction inverter, and reduces the DC power generated by the fuel cell FC and the regenerative power recovered by the drive motor DMa by regenerative braking. And has a function of charging the secondary battery BTa.
　二次電池ＢＴａは、余剰電力の貯蔵源、回生制動時の回生エネルギー貯蔵源、燃料電池車両の加速又は減速に伴う負荷変動時のエネルギーバッファとして機能する。二次電池ＢＴａとしては、例えば、ニッケル・カドミウム蓄電池、ニッケル・水素蓄電池、リチウム二次電池等の二次電池が好適である。二次電池ＢＴａには、充電率を測定するＳＯＣセンサＴｇが設けられている。 The secondary battery BTa functions as a surplus power storage source, a regenerative energy storage source during regenerative braking, and an energy buffer during load fluctuations associated with acceleration or deceleration of the fuel cell vehicle. As the secondary battery BTa, for example, a secondary battery such as a nickel / cadmium storage battery, a nickel / hydrogen storage battery, or a lithium secondary battery is suitable. The secondary battery BTa is provided with an SOC sensor Tg for measuring the charging rate.
　トラクションインバーターは、駆動モーターＤＭａに繋がれている。トラクションインバーターは、例えば、パルス幅変調方式で駆動されるＰＷＭインバーターである。トラクションインバーターは、コントローラーＥＣＵからの制御指令に従って、燃料電池ＦＣ又は二次電池ＢＴａから出力される直流電圧を三相交流電圧に変換して、駆動モーターＤＭａの回転トルクを制御する。駆動モーターＤＭａは、例えば、三相交流モーターであり、燃料電池車両の動力源を構成する。 Traction inverter is connected to the drive motor DMa. The traction inverter is, for example, a PWM inverter driven by a pulse width modulation method. The traction inverter converts the DC voltage output from the fuel cell FC or the secondary battery BTa into a three-phase AC voltage in accordance with a control command from the controller ECU, and controls the rotational torque of the drive motor DMa. The drive motor DMa is a three-phase AC motor, for example, and constitutes a power source of the fuel cell vehicle.
　続いて、冷却系ＣＳについて説明する。冷却系ＣＳは、メインラジエーターＲＭａと、ウォーターポンプＷＰａとを有している。 Subsequently, the cooling system CS will be described. The cooling system CS has a main radiator RMa and a water pump WPa.
　メインラジエーターＲＭａには、メインラジエーターファンが設けられている。メインラジエーターＲＭａは、燃料電池ＦＣを冷却するための冷却液を放熱して冷却するものである。 The main radiator RMa is provided with a main radiator fan. The main radiator RMa radiates and cools the coolant for cooling the fuel cell FC.
　ウォーターポンプＷＰａは、冷却液を燃料電池ＦＣとメインラジエーターＲＭａとの間で循環させるためのポンプである。ウォーターポンプＷＰａが作動することで、冷却液はメインラジエーターＲＭａから燃料電池ＦＣへと冷却液往路を通って流れる。 The water pump WPa is a pump for circulating the coolant between the fuel cell FC and the main radiator RMa. By operating the water pump WPa, the coolant flows from the main radiator RMa to the fuel cell FC through the coolant forward path.
　この燃料電池システムＦＳは統合的な制御手段としてのコントローラーＥＣＵ（出力供給部）を備えている。コントローラーＥＣＵは、ＣＰＵ、ＲＯＭ、ＲＡＭ、及び入出力インタフェースを備えるコンピュータシステムであり、燃料電池システムＦＳの各部を制御するものである。例えば、コントローラーＥＣＵは、イグニッションスイッチから出力される起動信号ＩＧを受信すると、燃料電池システムＦＳの運転を開始する。その後、コントローラーＥＣＵは、アクセルセンサから出力されるアクセル開度信号ＡＣＣや、車速センサから出力される車速信号ＶＣなどを基に、燃料電池システムＦＳ全体の要求電力を求める。燃料電池システムＦＳ全体の要求電力は、車両走行電力と補機電力との合計値である。 This fuel cell system FS includes a controller ECU (output supply unit) as an integrated control means. The controller ECU is a computer system including a CPU, a ROM, a RAM, and an input / output interface, and controls each part of the fuel cell system FS. For example, when the controller ECU receives the start signal IG output from the ignition switch, the controller ECU starts the operation of the fuel cell system FS. Thereafter, the controller ECU obtains the required power of the entire fuel cell system FS based on the accelerator opening signal ACC output from the accelerator sensor, the vehicle speed signal VC output from the vehicle speed sensor, and the like. The required power of the entire fuel cell system FS is the total value of the vehicle travel power and the auxiliary power.
　ここで、補機電力には、車載補機類（加湿器、エアコンプレッサー、水素ポンプ、及び冷却水循環ポンプ等）で消費される電力、車両走行に必要な装置（変速機、車輪制御装置、操舵装置、及び懸架装置等）で消費される電力、乗員空間内に配設される装置（空調装置、照明器具、及びオーディオ等）で消費される電力などが含まれる。 Here, auxiliary electric power includes electric power consumed by in-vehicle auxiliary equipment (humidifier, air compressor, hydrogen pump, cooling water circulation pump, etc.), and equipment required for vehicle travel (transmission, wheel control device, steering) Power consumed by devices, suspension devices, etc.), power consumed by devices (air conditioners, lighting equipment, audio, etc.) disposed in the passenger space, and the like.
　そして、コントローラーＥＣＵは、燃料電池ＦＣと二次電池ＢＴａとのそれぞれの出力電力の配分を決定する。コントローラーＥＣＵは、燃料電池ＦＣの発電量が目標電力に一致するように、酸化ガス供給系ＡＳＳ及び燃料ガス供給系ＦＳＳを制御するとともに、ＦＣ昇圧部ＦＤＣを制御して、燃料電池ＦＣの運転ポイント（出力電圧、出力電流）を制御する。 Then, the controller ECU determines the distribution of output power between the fuel cell FC and the secondary battery BTa. The controller ECU controls the oxidizing gas supply system ASS and the fuel gas supply system FSS so that the power generation amount of the fuel cell FC matches the target power, and also controls the FC booster FDC to operate the fuel cell FC. (Output voltage, output current) is controlled.
　コントローラーＥＣＵは、アクセル開度に応じた目標トルクが得られるように、例えば、スイッチング指令として、Ｕ相、Ｖ相、及びＷ相の各交流電圧指令値をトラクションインバーターに出力し、駆動モーターＤＭａの出力トルク、及び回転数を制御する。更に、コントローラーＥＣＵは、冷却系ＣＳを制御して燃料電池ＦＣが適切な温度になるように制御する。 The controller ECU outputs, for example, each of the U-phase, V-phase, and W-phase AC voltage command values to the traction inverter as a switching command so that a target torque corresponding to the accelerator opening is obtained, and the drive motor DMa Controls output torque and rotation speed. Further, the controller ECU controls the cooling system CS so that the fuel cell FC reaches an appropriate temperature.
　図２は燃料電池システムＦＳの運転制御を示すタイミングチャートである。図２において、（Ａ）は制御フラグを示しており、（Ｂ）は燃料電池ＦＣの出力電圧を示しており、（Ｃ）は燃料電池ＦＣの出力電流を示しており、（Ｄ）はエアコンプレッサー６２の駆動電流を示しており、（Ｅ）は二次電池ＢＴａのバッテリーパワーを示している。 FIG. 2 is a timing chart showing operation control of the fuel cell system FS. 2, (A) shows the control flag, (B) shows the output voltage of the fuel cell FC, (C) shows the output current of the fuel cell FC, and (D) shows the air The drive current of the compressor 62 is shown, (E) shows the battery power of the secondary battery BTa.
　燃料電池システムＦＳは、運転負荷に応じて、燃料電池ＦＣの運転モードを切り替えることにより発電効率の向上を図る。例えば、燃料電池システムＦＳは、発電効率の低い低負荷領域（発電要求が所定値未満となる運転領域）では、燃料電池ＦＣの発電指令値をゼロに設定して運転制御し、車両走行に要する電力やシステム運用上必要な電力を二次電池ＢＴａからの電力によって賄う（以下、第１の運転モード）。一方、発電効率の高い高負荷領域（発電要求が所定値以上となる運転領域）では、アクセル開度や車速などを基に燃料電池ＦＣの発電指令値を算出して運転制御し、車両走行に要する電力やシステム運用上必要な電力を燃料電池ＦＣによる発電電力のみによって又は燃料電池ＦＣによる発電電力と二次電池ＢＴａからの電力とによって賄う（以下、第２の運転モード）。 The fuel cell system FS improves the power generation efficiency by switching the operation mode of the fuel cell FC according to the operation load. For example, the fuel cell system FS controls the operation by setting the power generation command value of the fuel cell FC to zero in a low load region where the power generation efficiency is low (an operation region where the power generation request is less than a predetermined value), and is required for vehicle travel. Electric power and electric power necessary for system operation are covered by electric power from the secondary battery BTa (hereinafter referred to as first operation mode). On the other hand, in the high load region where the power generation efficiency is high (the operation region where the power generation request exceeds a predetermined value), the power generation command value of the fuel cell FC is calculated based on the accelerator opening, the vehicle speed, etc. The necessary power and the power necessary for system operation are covered only by the power generated by the fuel cell FC or by the power generated by the fuel cell FC and the power from the secondary battery BTa (hereinafter referred to as the second operation mode).
　燃料電池システムＦＳは、運転モードを示す制御フラグを一定周期で監視しており、制御フラグがオンになると第１の運転モードにて運転制御し、制御フラグがオフになると第２の運転モードにて運転制御する。何れの運転モードにおいても、通常運転時における燃料電池ＦＣの出力電圧は、原則として、使用上限電圧Ｖ１と使用下限電圧Ｖ２との間の運転範囲に制限される。 The fuel cell system FS monitors a control flag indicating the operation mode at a constant cycle. When the control flag is turned on, the fuel cell system FS controls the operation in the first operation mode. When the control flag is turned off, the fuel cell system FS enters the second operation mode. Control the operation. In any operation mode, the output voltage of the fuel cell FC during normal operation is basically limited to the operation range between the upper limit voltage V1 and the lower limit voltage V2.
　使用上限電圧Ｖ１としては、燃料電池ＦＣの触媒層に含まれている白金触媒が溶出しない程度の電圧範囲であるという条件を満たす電圧であることが好ましく、更にはその条件に加えて、燃料電池ＦＣへの反応ガス供給を停止した状態で燃料電池ＦＣの出力電圧を使用上限電圧Ｖ１に維持したときに、燃料電池ＦＣが発電する電力を補機類によって消費できる程度の電圧範囲であるという条件を満たす電圧であることが好ましい。燃料電池ＦＣでは、特に低密度電流運転時やアイドル運転時のようなカソード極の電位が高く保持されるような場合に、触媒層の白金触媒が溶出する可能性がある。本実施形態では、燃料電池ＦＣの出力電圧を使用上限電圧Ｖ１以下に制御し、燃料電池ＦＣの耐久性を維持することを高電位回避制御と称する。また使用上限電圧Ｖ１は、上述した高電位回避電圧である。本実施形態では、何れの運転モードにおいても、原則として、高電位回避制御が実行される。使用上限電圧Ｖ１は、燃料電池ＦＣの温度に応じて調整されるものである（調整の態様については、後述する）。 The use upper limit voltage V1 is preferably a voltage that satisfies the condition that the platinum catalyst contained in the catalyst layer of the fuel cell FC is in a voltage range that does not elute, and in addition to that condition, the fuel cell A condition that the voltage range is such that the power generated by the fuel cell FC can be consumed by the auxiliary equipment when the output voltage of the fuel cell FC is maintained at the upper limit voltage V1 while the supply of the reactive gas to the FC is stopped. It is preferable that the voltage satisfies the above. In the fuel cell FC, there is a possibility that the platinum catalyst in the catalyst layer may be eluted particularly when the potential of the cathode electrode is kept high, such as during low density current operation or idle operation. In the present embodiment, controlling the output voltage of the fuel cell FC to the use upper limit voltage V1 or less and maintaining the durability of the fuel cell FC is referred to as high potential avoidance control. The upper limit voltage V1 is the high potential avoidance voltage described above. In this embodiment, high potential avoidance control is executed in principle in any operation mode. The use upper limit voltage V1 is adjusted according to the temperature of the fuel cell FC (the mode of adjustment will be described later).
　使用下限電圧Ｖ２としては、セル電圧が還元領域に低下しない程度の電圧範囲であるという条件を満たす電圧であることが好ましい。燃料電池ＦＣを酸化領域にて連続運転し続けると、触媒層に含まれる白金触媒の表面に酸化皮膜が形成されることにより白金触媒の有効面積が減少する。すると、活性電圧が増大するので、燃料電池ＦＣのＩ－Ｖ特性が低下する。触媒活性化処理を実施することにより、酸化皮膜を還元し、白金触媒から酸化皮膜を除去することで、Ｉ－Ｖ特性を回復させることができるが、セル電圧を酸化領域と還元領域との間で頻繁に遷移させると、燃料電池ＦＣの耐久性が低下する。また、セル電圧を還元領域にまで下げた後に、要求負荷の増大に応じてセル電圧を酸化領域まで引き上げると、白金触媒を担持するカーボンが酸化する場合がある。このような事情を勘案し、通常運転時における燃料電池ＦＣの出力電圧を使用下限電圧Ｖ２以上に制御することで、燃料電池ＦＣの耐久性低下を抑制することができる。使用下限電圧Ｖ２は、例えば一つのセルあたりに電圧が０．８Ｖ程度になるように設定するのが好適である。 The lower limit voltage V2 is preferably a voltage that satisfies the condition that the cell voltage does not fall into the reduction region. When the fuel cell FC is continuously operated in the oxidation region, an effective area of the platinum catalyst is reduced by forming an oxide film on the surface of the platinum catalyst included in the catalyst layer. Then, since the activation voltage increases, the IV characteristics of the fuel cell FC deteriorate. By performing the catalyst activation treatment, the oxide film is reduced and the oxide film is removed from the platinum catalyst, so that the IV characteristics can be recovered, but the cell voltage is changed between the oxidation region and the reduction region. If the transition is made frequently, the durability of the fuel cell FC decreases. Further, when the cell voltage is raised to the oxidation region in accordance with an increase in the required load after the cell voltage is lowered to the reduction region, carbon carrying the platinum catalyst may be oxidized. In consideration of such circumstances, the output voltage of the fuel cell FC during normal operation is controlled to be equal to or higher than the use lower limit voltage V2, so that a decrease in durability of the fuel cell FC can be suppressed. The lower limit voltage V2 is preferably set so that the voltage is about 0.8 V per cell, for example.
　尚、通常運転時における燃料電池ＦＣの出力電圧は、原則として、使用上限電圧Ｖ１と使用下限電圧Ｖ２との間に制御されるが、システム運用の必要上、燃料電池ＦＣの出力電圧を使用上限電圧Ｖ１以上に制御したり、或いは使用下限電圧Ｖ２以下に制御したりする場合がある。例えば、二次電池ＢＴａのＳＯＣが所定以上のとき、ガス漏れ検出を実施するとき、回生制動により回生電力を回収するときなどは、燃料電池ＦＣの出力電圧は、開放端電圧まで引き上げられる。また、触媒活性化処理を実施するときには、燃料電池ＦＣの出力電圧は使用下限電圧Ｖ２以下に引き下げられる。 In general, the output voltage of the fuel cell FC during normal operation is controlled between the upper limit voltage V1 and the lower limit voltage V2, but the output voltage of the fuel cell FC is set to the upper limit for system operation. In some cases, the voltage is controlled to be equal to or higher than the voltage V1, or is controlled to be lower than the use lower limit voltage V2. For example, when the SOC of the secondary battery BTa is greater than or equal to a predetermined value, when gas leak detection is performed, or when regenerative power is recovered by regenerative braking, the output voltage of the fuel cell FC is raised to the open end voltage. Further, when the catalyst activation process is performed, the output voltage of the fuel cell FC is lowered to the use lower limit voltage V2 or less.
　第１の運転モードでは、コントローラーＥＣＵは、発電指令値をゼロに設定し、燃料電池ＦＣへの反応ガス供給を停止するとともに、燃料電池昇圧コンバーターへの電圧指令値を使用上限電圧Ｖ１に設定する（時刻ｔ０～ｔ４）。反応ガス供給を停止した後においても、燃料電池ＦＣ内部には、未反応の反応ガスが残留しているので、燃料電池ＦＣは、暫く微量に発電する。 In the first operation mode, the controller ECU sets the power generation command value to zero, stops the reaction gas supply to the fuel cell FC, and sets the voltage command value to the fuel cell boost converter to the use upper limit voltage V1. (Time t0 to t4). Even after the supply of the reaction gas is stopped, the unreacted reaction gas remains in the fuel cell FC, so the fuel cell FC generates a small amount of power for a while.
　時刻ｔ０～ｔ２の期間は、残留反応ガスが有する化学エネルギーが電気エネルギーに変換されることにより、微量発電が継続されている発電期間である。この発電期間では、燃料電池ＦＣの出力電圧が使用上限電圧Ｖ１を維持できるだけのエネルギーを残留反応ガスが有しているので、燃料電池ＦＣの出力電圧は使用上限電圧Ｖ１を維持し続ける。この発電期間中に発電された電力は、補機類にて消費されるが、補機類にて消費しきれない場合には、二次電池ＢＴａに充電される。 The period from time t0 to t2 is a power generation period in which a minute amount of power generation is continued by converting the chemical energy of the residual reaction gas into electric energy. In this power generation period, the residual reaction gas has enough energy for the output voltage of the fuel cell FC to maintain the use upper limit voltage V1, so the output voltage of the fuel cell FC continues to maintain the use upper limit voltage V1. The electric power generated during this power generation period is consumed by the auxiliary machinery, but when the auxiliary machinery cannot fully consume it, the secondary battery BTa is charged.
　時刻ｔ０～ｔ１の期間では、燃料電池ＦＣの発電エネルギーが補機類の消費容量を超えているため、発電エネルギーの一部が二次電池ＢＴａに充電されている。ところが、残留反応ガスの消費に応じて燃料電池ＦＣから放出される発電エネルギーは、次第に減少していくので、時刻ｔ１の時点では、燃料電池ＦＣから放出される発電エネルギーと、補機類の消費容量とがバランスし、二次電池ＢＴａに充電される電力はゼロとなる。そして、時刻ｔ１～時刻ｔ２の期間では、燃料電池ＦＣから放出される発電エネルギーでは、補機類の消費電力を賄うことができなくなるので、その不足電力を補うため、二次電池ＢＴａから補機類に電力が供給されるようになる。 During the period from time t0 to t1, since the generated energy of the fuel cell FC exceeds the consumption capacity of the auxiliary machinery, a part of the generated energy is charged in the secondary battery BTa. However, since the power generation energy released from the fuel cell FC in accordance with the consumption of the residual reaction gas gradually decreases, at time t1, the power generation energy released from the fuel cell FC and the consumption of auxiliary machinery The capacity is balanced and the power charged in the secondary battery BTa is zero. In the period from time t1 to time t2, the power generation energy released from the fuel cell FC cannot cover the power consumption of the auxiliary machinery. Power is supplied to the kind.
　時刻ｔ２～ｔ４の期間は、残留反応ガスの消費により、燃料電池ＦＣの出力電圧をもはや使用上限電圧Ｖ１に維持することができなくなり、発電停止に至る発電停止期間である。燃料電池ＦＣの出力電圧を使用上限電圧Ｖ１に維持するために必要なエネルギーを残留反応ガスが有しなくなると、発電停止に至り、燃料電池ＦＣの出力電圧は、次第に低下していく。この発電停止期間では、燃料電池ＦＣの発電エネルギーはゼロとなるので、二次電池ＢＴａから補機類に供給される電力はほぼ一定となる。 The period from the time t2 to the time t4 is a power generation stop period in which the output voltage of the fuel cell FC can no longer be maintained at the use upper limit voltage V1 due to the consumption of the residual reaction gas and the power generation is stopped. When the residual reaction gas does not have the energy necessary for maintaining the output voltage of the fuel cell FC at the upper limit voltage V1, the power generation is stopped, and the output voltage of the fuel cell FC gradually decreases. In this power generation stop period, the power generation energy of the fuel cell FC becomes zero, so the power supplied from the secondary battery BTa to the auxiliary machines is almost constant.
　燃料電池ＦＣの出力電圧が使用下限電圧Ｖ２まで低下する時刻ｔ３では、酸化ガス供給系ＡＳＳを駆動し、燃料電池ＦＣに酸化ガスを補給する。燃料電池ＦＣは、酸化ガスの補給を受けて発電するので、燃料電池ＦＣの出力電圧は上昇に転じる。燃料電池ＦＣの出力電圧が所定電圧まで昇圧した段階で、酸化ガス補給を終了する。このように、発電停止期間中では、燃料電池ＦＣの出力電圧が使用下限電圧Ｖ２まで低下する度に酸化ガスが適宜補給され、出力電圧が使用下限電圧Ｖ２を下回らないように制御される。 At time t3 when the output voltage of the fuel cell FC drops to the lower limit voltage V2, the oxidizing gas supply system ASS is driven to supply the fuel cell FC with oxidizing gas. Since the fuel cell FC generates electric power upon replenishment of the oxidizing gas, the output voltage of the fuel cell FC starts to increase. When the output voltage of the fuel cell FC is increased to a predetermined voltage, the oxidizing gas supply is finished. As described above, during the power generation stop period, the oxidant gas is appropriately supplied whenever the output voltage of the fuel cell FC decreases to the use lower limit voltage V2, and the output voltage is controlled not to fall below the use lower limit voltage V2.
　第２の運転モードでは、コントローラーＥＣＵは、要求負荷に応じて発電指令値を算出し、燃料電池ＦＣへの反応ガス供給を制御するとともに、燃料電池昇圧コンバーターを介して燃料電池ＦＣの運転ポイント（出力電圧、出力電流）を制御する（時刻ｔ４～時刻ｔ５）。このとき、燃料電池昇圧コンバーターへの電圧指令値は、使用上限電圧Ｖ１と使用下限電圧Ｖ２との間の運転範囲に制限される。 In the second operation mode, the controller ECU calculates the power generation command value according to the required load, controls the supply of the reaction gas to the fuel cell FC, and operates the fuel cell FC operating point ( The output voltage and output current are controlled (time t4 to time t5). At this time, the voltage command value to the fuel cell boost converter is limited to an operation range between the upper limit voltage V1 and the lower limit voltage V2.
　上述したように、出力供給部として機能するコントローラーＥＣＵ及び燃料電池昇圧コンバーターは、負荷（駆動モーターＤＭａや補機類）が必要とする要求電力を、燃料電池ＦＣから供給される電力を調整しながら供給する。出力供給部は、要求電力が所定電力未満の場合に、燃料電池ＦＣへの反応ガス供給を抑制すると共に燃料電池ＦＣの出力電圧が開放端電圧よりも低い高電位回避電圧に維持されるように制御し、要求電力が所定電力以上の場合、高電位回避電圧を上限として燃料電池の出力電圧を制御するものである。 As described above, the controller ECU and the fuel cell boost converter functioning as the output supply unit adjust the power supplied from the fuel cell FC to the required power required by the load (drive motor DMa and auxiliary machinery). Supply. When the required power is less than the predetermined power, the output supply unit suppresses the supply of the reaction gas to the fuel cell FC and maintains the output voltage of the fuel cell FC at a high potential avoidance voltage lower than the open-circuit voltage. When the required power is equal to or higher than the predetermined power, the output voltage of the fuel cell is controlled with the high potential avoidance voltage as the upper limit.
　特に本実施形態では、出力供給部として機能するコントローラーＥＣＵ及び燃料電池昇圧コンバーターは、測定され及び／又は推測された燃料電池ＦＣ（セルスタック）の温度に応じて高電位回避電圧を調整する。このように、測定され及び／又は推測されたセルスタックの温度に応じて高電位回避電圧を調整することで、燃料電池ＦＣの触媒溶出を抑制しつつ、燃費の向上も図ることができる。 Particularly in this embodiment, the controller ECU and the fuel cell boost converter functioning as an output supply unit adjust the high potential avoidance voltage according to the measured and / or estimated temperature of the fuel cell FC (cell stack). As described above, by adjusting the high potential avoidance voltage according to the measured and / or estimated temperature of the cell stack, it is possible to improve fuel efficiency while suppressing catalyst elution of the fuel cell FC.
　出力供給部として機能するコントローラーＥＣＵ及び燃料電池昇圧コンバーターは、燃料電池ＦＣ（セルスタック）の温度が第一温度の場合の第一高電位回避電圧よりも、燃料電池ＦＣ（セルスタック）の温度が第一温度よりも低い第二温度の場合の第二高電位回避電圧を高く設定する。このように、燃料電池ＦＣ（セルスタック）の温度が第一温度よりも低い第二温度の場合の第二高電位回避電圧を、燃料電池ＦＣ（セルスタック）の温度が第一温度の場合の第一高電位回避電圧よりも高く設定するので、燃料電池ＦＣ（セルスタック）の温度が低い場合の高電位回避電圧を上げることができ、燃料電池ＦＣ（セルスタック）の余剰電力を抑制することができる。 The controller ECU functioning as an output supply unit and the fuel cell boost converter have a temperature of the fuel cell FC (cell stack) higher than the first high potential avoidance voltage when the temperature of the fuel cell FC (cell stack) is the first temperature. The second high potential avoidance voltage in the case of the second temperature lower than the first temperature is set high. Thus, the second high potential avoidance voltage when the temperature of the fuel cell FC (cell stack) is the second temperature lower than the first temperature is the same as that when the temperature of the fuel cell FC (cell stack) is the first temperature. Since it is set higher than the first high potential avoidance voltage, the high potential avoidance voltage can be increased when the temperature of the fuel cell FC (cell stack) is low, and the surplus power of the fuel cell FC (cell stack) is suppressed. Can do.
　本実施形態においてこのように高電位回避電圧を調整するのは、温度によって燃料電池ＦＣの低下量が異なるためである。図３は、燃料電池の性能低下と温度との関係を示すグラフである。図３では、横軸に温度（燃料電池ＦＣのセルスタックの温度）をとり、縦軸に燃料電池ＦＣの性能低下量を示すものとして活性化過電圧増加量を取っている。 The reason why the high potential avoidance voltage is adjusted in this embodiment is that the amount of decrease of the fuel cell FC varies depending on the temperature. FIG. 3 is a graph showing the relationship between the decrease in performance of the fuel cell and the temperature. In FIG. 3, the horizontal axis indicates the temperature (temperature of the cell stack of the fuel cell FC), and the vertical axis indicates the activation overvoltage increase amount indicating the amount of performance decrease of the fuel cell FC.
　図３に示すグラフの太い線が、許容範囲としての活性化過電圧増加量の上限であり、その太い線よりも下に活性化過電圧増加量が収まるように制御することが求められる。図３に示されるように、燃料電池ＦＣのセルスタックの温度が０℃であれば、高電位回避電圧を１．０Ｖにしても、燃料電池ＦＣの性能低下は許容範囲内になる。同様に、燃料電池ＦＣのセルスタックの温度が２０℃であれば、高電位回避電圧を０．９５Ｖにしてもよく、燃料電池ＦＣのセルスタックの温度が４０℃であれば、高電位回避電圧を０．９Ｖにしてもよい。 The thick line in the graph shown in FIG. 3 is the upper limit of the activation overvoltage increase amount as the allowable range, and control is required so that the activation overvoltage increase amount falls below the thick line. As shown in FIG. 3, if the temperature of the cell stack of the fuel cell FC is 0 ° C., even if the high potential avoidance voltage is 1.0 V, the performance degradation of the fuel cell FC is within an allowable range. Similarly, if the temperature of the cell stack of the fuel cell FC is 20 ° C., the high potential avoidance voltage may be 0.95V, and if the temperature of the cell stack of the fuel cell FC is 40 ° C., the high potential avoidance voltage May be 0.9V.
　このような関係に基づいて、燃料電池ＦＣのセルスタックの温度と上限電圧との関係を示したものが、図４に示すグラフである。図４では、横軸に温度（燃料電池ＦＣのセルスタックの温度）をとり、縦軸に高電位回避電圧（上限電圧）をとっている。図４に示す例では、０℃以下の場合の上限電圧が１．０Ｖ、０～２０℃の場合の上限電圧が０．９５Ｖ、２０～４０℃の場合の上限電圧が０．９３Ｖ、４０～６０℃の場合の上限電圧が０．９０Ｖ、６０～８０℃の場合の上限電圧が０．８７Ｖ、８０～１００℃の場合の上限電圧が０．８５Ｖである。 The graph shown in FIG. 4 shows the relationship between the temperature of the cell stack of the fuel cell FC and the upper limit voltage based on such a relationship. In FIG. 4, the horizontal axis represents temperature (temperature of the cell stack of the fuel cell FC), and the vertical axis represents high potential avoidance voltage (upper limit voltage). In the example shown in FIG. 4, the upper limit voltage when the temperature is 0 ° C. or lower is 1.0 V, the upper limit voltage when 0 to 20 ° C. is 0.95 V, the upper limit voltage when 20 to 40 ° C. is 0.93 V, 40 to The upper limit voltage at 60 ° C. is 0.90 V, the upper limit voltage at 60 to 80 ° C. is 0.87 V, and the upper limit voltage at 80 to 100 ° C. is 0.85 V.
　また本実施形態では、コントローラーＥＣＵは、燃料電池システムＦＳの停止後の経過時間を測定する経過時間測定部としての機能を有している。コントローラーＥＣＵは、燃料電池システムＦＳの始動時の外気温度、停止時における燃料電池ＦＣ（セルスタック）の温度、及び停止後の経過時間と、それらに対応する燃料電池ＦＣ（セルスタック）の温度と、の相関関係を格納する相関保持部としての機能を有している。 In the present embodiment, the controller ECU has a function as an elapsed time measuring unit that measures the elapsed time after the fuel cell system FS is stopped. The controller ECU determines the outside air temperature at the start of the fuel cell system FS, the temperature of the fuel cell FC (cell stack) at the time of stop, the elapsed time after the stop, and the temperature of the fuel cell FC (cell stack) corresponding thereto , And a function as a correlation holding unit for storing the correlation.
　コントローラーＥＣＵは、外気温度測定部として機能する温度センサＴｆが測定した外気温度、スタック温度測定部として機能する温度センサＴｄが測定した停止時における燃料電池ＦＣ（セルスタック）の温度、及び停止後の経過時間に対応する燃料電池ＦＣ（セルスタック）の温度を取得する。コントローラーＥＣＵは、この取得した燃料電池ＦＣ（セルスタック）の温度を始動時の燃料電池ＦＣ（セルスタック）の温度とみなし、高電位回避電圧を調整する。 The controller ECU measures the outside air temperature measured by the temperature sensor Tf functioning as the outside air temperature measurement unit, the temperature of the fuel cell FC (cell stack) at the time of stop measured by the temperature sensor Td functioning as the stack temperature measurement unit, and the post-stop The temperature of the fuel cell FC (cell stack) corresponding to the elapsed time is acquired. The controller ECU regards the obtained temperature of the fuel cell FC (cell stack) as the temperature of the fuel cell FC (cell stack) at the time of starting, and adjusts the high potential avoidance voltage.
　本実施形態では上述したように、測定され及び／又は推測された燃料電池ＦＣ（セルスタック）の温度に応じて高電位回避電圧を調整する。燃料電池ＦＣ（セルスタック）の温度をより正確に知るためには燃料電池ＦＣ（セルスタック）の温度を直接測定することが望ましいけれども、実際には燃料電池ＦＣ（セルスタック）の冷却水の出口温度を測定することで代替している。燃料電池システムＦＳが運転状態にあり冷却水が循環している状態では、冷却水の出口温度を燃料電池ＦＣ（セルスタック）の温度とみなしてよい。しかしながら、燃料電池システムＦＳが停止状態にあると冷却水は循環しておらず、冷却水が燃料電池ＦＣ（セルスタック）の温度を的確に表していないことが多い。そこで、この燃料電池システムＦＳの始動時の外気温度、停止時における燃料電池ＦＣ（セルスタック）の停止温度、及び停止後の経過時間と、それらに対応する燃料電池ＦＣ（セルスタック）の温度と、の相関関係を格納しておき、実測した外気温度、燃料電池ＦＣ（セルスタック）の温度、及び停止後の経過時間を用いて燃料電池ＦＣ（セルスタック）の温度を取得する。このように取得した温度を始動時の燃料電池ＦＣ（セルスタック）の温度とみなすことで、より的確に始動時の燃料電池ＦＣ（セルスタック）の温度を推測することができ、高電位回避電圧の調整が適切なものとなる。 In this embodiment, as described above, the high potential avoidance voltage is adjusted according to the measured and / or estimated temperature of the fuel cell FC (cell stack). Although it is desirable to directly measure the temperature of the fuel cell FC (cell stack) in order to know the temperature of the fuel cell FC (cell stack) more accurately, in reality, the outlet of the cooling water of the fuel cell FC (cell stack) It is replaced by measuring temperature. When the fuel cell system FS is in an operating state and the cooling water is circulating, the outlet temperature of the cooling water may be regarded as the temperature of the fuel cell FC (cell stack). However, when the fuel cell system FS is stopped, the cooling water does not circulate, and the cooling water often does not accurately represent the temperature of the fuel cell FC (cell stack). Therefore, the outside air temperature at the start of the fuel cell system FS, the stop temperature of the fuel cell FC (cell stack) at the time of stop, the elapsed time after the stop, and the temperature of the fuel cell FC (cell stack) corresponding thereto , And the temperature of the fuel cell FC (cell stack) is acquired using the measured outside air temperature, the temperature of the fuel cell FC (cell stack), and the elapsed time after the stop. By considering the temperature thus obtained as the temperature of the fuel cell FC (cell stack) at the time of starting, the temperature of the fuel cell FC (cell stack) at the time of starting can be estimated more accurately, and the high potential avoidance voltage The adjustment will be appropriate.
　また本実施形態では、電気を充電及び放電することが可能な二次電池ＢＴａと、二次電池ＢＴａの温度を測定する電池温度測定部としての温度センサＴｈと、二次電池ＢＴａの充電率を測定する充電率測定部としてのＳＯＣセンサＴｇと、を備えている。相関保持部としてのコントローラーＥＣＵは、二次電池ＢＴａの温度及び二次電池ＢＴａの充電率と、それらに対応する二次電池ＢＴａの最大吸収可能電力と、の相関関係を格納している。出力供給部として機能するコントローラーＥＣＵ、燃料電池昇圧コンバーター、及びバッテリー昇圧コンバーターは、負荷が必要とする要求電力に応じた電力を、燃料電池ＦＣから供給される電力および二次電池ＢＴａから供給される電力を調整しながら供給するものであって、電池温度測定部である温度センサＴｈが測定した二次電池ＢＴａの温度と、充電率測定部であるＳＯＣセンサＴｇが測定した二次電池ＢＴａの充電率とに対応する二次電池ＢＴａの最大吸収可能電力を取得し、当該取得した最大吸収可能電力を用いて高電位回避電圧を調整する。 In this embodiment, the secondary battery BTa capable of charging and discharging electricity, the temperature sensor Th as a battery temperature measuring unit for measuring the temperature of the secondary battery BTa, and the charging rate of the secondary battery BTa And an SOC sensor Tg as a charge rate measuring unit to be measured. The controller ECU as the correlation holding unit stores the correlation between the temperature of the secondary battery BTa and the charging rate of the secondary battery BTa, and the maximum absorbable power of the secondary battery BTa corresponding to them. The controller ECU, the fuel cell boost converter, and the battery boost converter functioning as an output supply unit are supplied with power supplied from the fuel cell FC and the secondary battery BTa according to the required power required by the load. The power is supplied while adjusting the power, and the temperature of the secondary battery BTa measured by the temperature sensor Th that is a battery temperature measuring unit and the charging of the secondary battery BTa measured by the SOC sensor Tg that is a charging rate measuring unit. The maximum absorbable power of the secondary battery BTa corresponding to the rate is acquired, and the high potential avoidance voltage is adjusted using the acquired maximum absorbable power.
　本実施形態では上述したように、燃料電池ＦＣ（セルスタック）の温度が低い場合の高電位回避電圧を上げることができ、燃料電池ＦＣ（セルスタック）の余剰電力を抑制することができる。更に、余剰電力を二次電池ＢＴａで吸収することができるので、二次電池ＢＴａの最大吸収可能電力を考慮することが好ましい。そこで、コントローラーＥＣＵに、二次電池ＢＴａの温度及び二次電池ＢＴａの充電率と、それらに対応する二次電池ＢＴａの最大吸収可能電力と、の相関関係を格納しておき、出力供給部が、実測した二次電池ＢＴａの温度及び充電率を用いて最大吸収可能電力を取得する。このように取得した最大吸収可能電力を用いて高電位回避電圧を調整することで、特に低温度領域で余力がなくなると想定される最大吸収可能電力に対応した余剰電力を発生させることができ、二次電池ＢＴａの耐久性悪化が抑制できる。 In this embodiment, as described above, the high potential avoidance voltage when the temperature of the fuel cell FC (cell stack) is low can be increased, and surplus power of the fuel cell FC (cell stack) can be suppressed. Furthermore, since surplus power can be absorbed by the secondary battery BTa, it is preferable to consider the maximum absorbable power of the secondary battery BTa. Therefore, the controller ECU stores the correlation between the temperature of the secondary battery BTa, the charging rate of the secondary battery BTa, and the maximum absorbable power of the secondary battery BTa corresponding to them, and the output supply unit Then, the maximum absorbable power is acquired using the actually measured temperature and charging rate of the secondary battery BTa. By adjusting the high potential avoidance voltage using the maximum absorbable power acquired in this way, it is possible to generate surplus power corresponding to the maximum absorbable power that is assumed to have no remaining power, particularly in the low temperature region, The deterioration of the durability of the secondary battery BTa can be suppressed.
　燃料電池ＦＣの出力と、二次電池ＢＴａの許容電力（最大吸収可能電力）との関係を図５に示す。図５の（Ａ）は、燃料電池ＦＣの出力を示し、（Ｂ）は二次電池ＢＴａの最大吸収可能電力を示している。図５に示されるように、低温領域では、二次電池ＢＴａの最大吸収可能電力に極端に余力がなくなり、燃料電池ＦＣの出力低下よりもその低下度合いが大きい。そのため、上述したように、温度に応じた二次電池ＢＴａの最大吸収可能電力を推定することが好ましいものである。 FIG. 5 shows the relationship between the output of the fuel cell FC and the allowable power (maximum absorbable power) of the secondary battery BTa. FIG. 5A shows the output of the fuel cell FC, and FIG. 5B shows the maximum absorbable power of the secondary battery BTa. As shown in FIG. 5, in the low temperature region, the maximum power that can be absorbed by the secondary battery BTa is extremely small, and the degree of reduction is greater than the reduction in the output of the fuel cell FC. Therefore, as described above, it is preferable to estimate the maximum absorbable power of the secondary battery BTa according to the temperature.
６２   エアコンプレッサー
６９   バイパス流路
９２，９２    車輪
ＡＳ１ 酸化ガス流路
ＡＳ２ 酸化オフガス流路
ＡＳＳ 酸化ガス供給系
ＢＴａ 二次電池
ＣＥ   セル
ＣＳ   冷却系
ＤＭａ 駆動モーター
ＤＶａ 電磁弁
ＤＶｂ 統合弁
ＥＣＵ コントローラー
ＥＶｃ 排気排水弁
ＦＣ   燃料電池
ＦＣＳ 燃料電池系
ＦＤＣ 昇圧部
ＦＳ   燃料電池システム
ＦＳ１ 高圧水素タンク
ＦＳ２ 燃料オフガス流路
ＦＳＳ 燃料ガス供給系
ＨＰａ 水素ポンプ
ＨＶＳ 駆動系
Ｐｔ   圧力センサ
ＲＭａ メインラジエーター
Ｔｄ   温度センサ
Ｔｆ   温度センサ
Ｔｇ   センサ
Ｔｈ   温度センサ
ＴＶａ 入口三方弁
ＷＰａ ウォーターポンプ 62 Air compressor 69 Bypass channel 92, 92 Wheel AS1 Oxidizing gas channel AS2 Oxidizing off gas channel ASS Oxidizing gas supply system BTa Secondary battery CE Cell CS Cooling system DMa Drive motor DVa Electromagnetic valve DVb Integrated valve ECU Controller EVc Exhaust drain valve FC fuel cell FCS fuel cell system FDC booster FS fuel cell system FS1 high-pressure hydrogen tank FS2 fuel off-gas flow path FSS fuel gas supply system HPa hydrogen pump HVS drive system Pt pressure sensor RMa main radiator Td temperature sensor Tf temperature sensor Tg sensor Th temperature Sensor TVa Inlet three-way valve WPa Water pump

Claims (4)

  1. 　燃料電池システムであって、
    　反応ガスの供給を受けて発電する複数の単セルからなるセルスタックを有する燃料電池と、
    　前記セルスタックの温度を測定するスタック温度測定部と、
    　前記燃料電池に電気的に接続されてなる負荷と、
    　前記負荷が必要とする要求電力を、前記燃料電池から供給される電力を調整しながら供給する出力供給部と、を備え、
    　前記出力供給部は、
    　前記要求電力が所定電力未満の場合に、前記燃料電池への反応ガス供給を抑制すると共に前記燃料電池の出力電圧が開放端電圧よりも低い高電位回避電圧に維持されるように制御し、前記要求電力が所定電力以上の場合、前記高電位回避電圧を上限として前記燃料電池の出力電圧を制御するものであって、
    　測定され及び／又は推測された前記セルスタックの温度に応じて前記高電位回避電圧を調整することを特徴とする燃料電池システム。     A fuel cell system,
    A fuel cell having a cell stack composed of a plurality of single cells that generate power by receiving supply of a reaction gas;
    A stack temperature measuring unit for measuring the temperature of the cell stack;
    A load electrically connected to the fuel cell;
    An output supply unit that supplies the required power required by the load while adjusting the power supplied from the fuel cell;
    The output supply unit
    When the required power is less than a predetermined power, the supply of the reaction gas to the fuel cell is suppressed and the output voltage of the fuel cell is controlled to be maintained at a high potential avoidance voltage lower than the open-circuit voltage, When the required power is equal to or higher than a predetermined power, the output voltage of the fuel cell is controlled with the high potential avoidance voltage as an upper limit,
    A fuel cell system, wherein the high potential avoidance voltage is adjusted according to the measured and / or estimated temperature of the cell stack.
  2. 　前記出力供給部は、前記セルスタックの温度が第一温度の場合の第一高電位回避電圧よりも、前記セルスタックの温度が前記第一温度よりも低い第二温度の場合の第二高電位回避電圧を高く設定することを特徴とする請求項１に記載の燃料電池システム。 The output supply unit has a second high potential when the temperature of the cell stack is a second temperature lower than the first temperature than a first high potential avoidance voltage when the temperature of the cell stack is a first temperature. The fuel cell system according to claim 1, wherein the avoidance voltage is set high.
  3. 　外気温度を測定する外気温度測定部と、
    　この燃料電池システムの停止後の経過時間を測定する経過時間測定部と、
    　この燃料電池システムの始動時の外気温度、停止時における前記セルスタックの停止温度、及び停止後の経過時間と、それらに対応する前記セルスタックの温度と、の相関関係を格納する相関保持部と、を備え、
    　前記出力供給部は、前記外気温度測定部が測定した外気温度、前記スタック温度測定部が測定した停止時における前記セルスタックの温度、及び前記経過時間測定部が測定した停止後の経過時間に対応する前記セルスタックの温度を前記相関保持部から取得し、当該取得した温度を始動時の前記セルスタックの温度とみなし、前記高電位回避電圧を調整することを特徴とする請求項２に記載の燃料電池システム。     An outside temperature measuring unit for measuring outside temperature;
    An elapsed time measuring unit for measuring an elapsed time after the stop of the fuel cell system;
    A correlation holding unit for storing a correlation between an outside air temperature at the start of the fuel cell system, a stop temperature of the cell stack at the stop, an elapsed time after the stop, and a temperature of the cell stack corresponding to them; With
    The output supply unit corresponds to the outside temperature measured by the outside temperature measuring unit, the temperature of the cell stack at the time of stopping measured by the stack temperature measuring unit, and the elapsed time after stopping measured by the elapsed time measuring unit. The temperature of the cell stack is acquired from the correlation holding unit, the acquired temperature is regarded as the temperature of the cell stack at the time of starting, and the high potential avoidance voltage is adjusted. Fuel cell system.
  4. 　電気を充電及び放電することが可能な二次電池と、
    　前記二次電池の温度を測定する電池温度測定部と、
    　前記二次電池の充電率を測定する充電率測定部と、を備え、
    　前記相関保持部は、前記二次電池の温度及び前記二次電池の充電率と、それらに対応する前記二次電池の最大吸収可能電力と、の相関関係を格納し、
    　前記出力供給部は、
    　前記負荷が必要とする要求電力に応じた電力を、前記燃料電池から供給される電力および前記二次電池から供給される電力を調整しながら供給するものであって、
    　前記電池温度測定部が測定した前記二次電池の温度と、前記充電率測定部が測定した前記二次電池の充電率とに対応する前記二次電池の最大吸収可能電力を前記相関保持部から取得し、当該取得した最大吸収可能電力を用いて前記高電位回避電圧を調整することを特徴とする請求項２に記載の燃料電池システム。     A secondary battery capable of charging and discharging electricity;
    A battery temperature measuring unit for measuring the temperature of the secondary battery;
    A charge rate measuring unit for measuring the charge rate of the secondary battery,
    The correlation holding unit stores the correlation between the temperature of the secondary battery and the charging rate of the secondary battery, and the maximum absorbable power of the secondary battery corresponding to them,
    The output supply unit
    Supplying power corresponding to the required power required by the load while adjusting the power supplied from the fuel cell and the power supplied from the secondary battery,
    The maximum absorbable power of the secondary battery corresponding to the temperature of the secondary battery measured by the battery temperature measuring unit and the charging rate of the secondary battery measured by the charging rate measuring unit is obtained from the correlation holding unit. 3. The fuel cell system according to claim 2, wherein the high potential avoidance voltage is acquired by using the acquired maximum absorbable power.
PCT/JP2012/059216 2012-04-04 2012-04-04 Fuel cell system WO2013150619A1 (en)

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