JP5765672B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system including a fuel cell including a membrane-electrode assembly in which electrodes having a catalyst layer are disposed on both sides of a polymer electrolyte membrane.

  A fuel cell stack is a power generation system that directly converts energy released during an oxidation reaction into electric energy by oxidizing fuel by an electrochemical process. The fuel cell stack has a membrane-electrode assembly in which both side surfaces of a polymer electrolyte membrane for selectively transporting hydrogen ions are sandwiched by a pair of electrodes made of a porous material. Each of the pair of electrodes is mainly composed of a carbon powder carrying a platinum-based metal catalyst, and is formed on the surface of the catalyst layer in contact with the polymer electrolyte membrane and a gas having both air permeability and electronic conductivity. And a diffusion layer.

  In this type of fuel cell system, platinum is eluted (ionized) when the cell voltage set based on the system power requirement becomes a predetermined voltage or higher and the platinum in the catalyst layer is exposed to a high potential higher than the predetermined value. The catalyst performance may be reduced, and if the operation is continued in the operation region where the cell voltage becomes the oxidation voltage, an oxide film may be formed on the platinum catalyst surface of the catalyst layer, leading to a decrease in the catalyst performance. is there.

  Patent Document 1 discloses a technique that uses an oxide film formed on the surface of a platinum catalyst as a protective film that suppresses elution of platinum. Specifically, when the target value of the cell voltage set based on the system power requirement is equal to or higher than a predetermined film elution start voltage at which platinum starts to elute, the cell voltage is set to a predetermined oxide film formation voltage. The time is maintained to form an oxide film on the platinum catalyst surface, and then the cell voltage is set to a target value.

JP 2010-067434 A

  The “predetermined time” when the cell voltage in Patent Document 1 is maintained at a predetermined oxide film forming voltage for a predetermined time to form an oxide film on the platinum catalyst surface is determined based on the chargeable amount of the power storage device. However, when the chargeable capacity of the power storage device is small, in other words, when the remaining capacity (SOC) of the power storage device is large, the surplus power generated relative to the required power of the fuel cell from the viewpoint of suppressing overcharge of the power storage device Cannot be charged in the power storage device.

  In such a case, it is necessary to increase the power generation voltage of the fuel cell, and as a result, platinum must be allowed to elute. Further, when the fuel cell operating state thereafter becomes a state where the power generation voltage of the fuel cell does not drop so much, elution of platinum with a small particle size proceeds, while precipitation of platinum with a large particle size proceeds. As a result, the surface area of the entire platinum catalyst is reduced, leading to a decrease in catalyst performance.

  Therefore, an object of the present invention is to propose a fuel cell system capable of suppressing a decrease in catalyst performance regardless of the remaining capacity of a power storage device by controlling both elution and precipitation of the catalyst.

In order to achieve the above object, the fuel cell system of the present invention comprises:
A fuel cell comprising a membrane-electrode assembly in which electrodes having a catalyst layer are disposed on both sides of a polymer electrolyte membrane;
A power storage device connected in parallel to the fuel cell with respect to a load and capable of discharging to the load and charging from the fuel cell;
A control device that sets an output voltage of the fuel cell based on a required output required for the fuel cell, and controls charging / discharging of the power storage device based on the output voltage to be set and the required output; With
When the required voltage corresponding to the required output is equal to or higher than a predetermined control start voltage and the change in the required voltage is on an ascending slope, the control device reduces the output voltage to a voltage lower than the required voltage. Setting and charging the power storage device until the remaining capacity exceeds a first predetermined value, and when the change in the required voltage changes from an ascending gradient to a descending gradient, the output voltage is maintained as it is Discharging until the remaining capacity becomes less than a second predetermined value, and setting the output voltage to a voltage lower than the control start voltage after the end of the discharge.

  In this configuration, for example, if the control start voltage is set to the catalyst elution start voltage of the catalyst layer, when the change in the required voltage for the fuel cell is on an ascending slope, catalyst elution (particularly for a catalyst having a small particle diameter). Elution) can be suppressed, and the power storage device can be charged in the meantime.

  Then, when the change in the required voltage for the fuel cell changes from the ascending gradient to the descending gradient, the output voltage of the fuel cell is set to the catalyst elution start voltage while discharging the power charged in the power storage device during the ascending gradient. By lowering the value, it is possible to deposit a large amount of the catalyst eluted during the upward gradient on the catalyst having a small particle diameter.

  In the above configuration, the control device performs charge / discharge of the power storage device that is performed when a required voltage corresponding to the required output is equal to or higher than the predetermined control start voltage so that a charge amount and a discharge amount are the same. It may be configured to control.

  According to this configuration, the total power balance at the time of output voltage control performed for suppressing elution of the catalyst and promoting deposition can be made zero, so that the output of the entire fuel cell system is stabilized.

  In the above configuration, the control device may be configured to hold the output voltage at a constant voltage while discharging the power storage device until the remaining capacity reaches a second predetermined value.

  According to this configuration, if the required voltage is in a descending gradient, the deviation width between the set output voltage and the required voltage increases with time, and the amount of discharge of the power storage device increases. Thereby, since the discharge time of the power storage device is shortened, voltage control for promoting the deposition of the catalyst can be started more quickly.

  The said structure WHEREIN: The said control apparatus may be comprised so that the said predetermined | prescribed control start voltage may be raised, when the performance fall amount of the said catalyst layer becomes below 3rd predetermined value.

  The rate of decrease in catalyst performance decreases as the catalyst performance decreases. In such a case, the frequency of the output voltage control for suppressing the elution of the catalyst and promoting the precipitation may be reduced. According to the above configuration, it is possible to reduce unnecessary implementation of the output voltage control.

  According to the present invention, it is possible to provide a fuel cell system capable of suppressing a decrease in catalyst performance regardless of the remaining capacity of the power storage device.

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a disassembled perspective view of the cell which comprises a fuel cell stack. It is a flowchart which shows the example of 1 operation control of a fuel cell system. It is a timing chart which shows the example of 1 operation control of a fuel cell system. It is the timing chart which expanded a part of FIG. It is a figure which shows an example of the relationship between an output electric current (current density) and an oxide film rate when the output voltage of a fuel cell stack is kept at a constant value.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a system configuration of a fuel cell system 10 according to an embodiment of the present invention.

  The fuel cell system 10 functions as an in-vehicle power supply system mounted on a fuel cell vehicle. The fuel cell stack 20 generates electric power by receiving supply of reaction gas (fuel gas, oxidant gas), and air as oxidant gas. Gas supply system 30 for supplying the fuel cell stack 20 with hydrogen, fuel gas supply system 40 for supplying hydrogen gas as the fuel gas to the fuel cell stack 20, and power for controlling charge and discharge of power A system 50 and a controller (control device) 60 for overall control of the entire system are provided.

The fuel cell stack 20 is a solid polymer electrolyte cell stack formed by stacking a large number of cells in series. In the fuel cell stack 20, the oxidation reaction of the formula (1) occurs at the anode electrode, and the reduction reaction of the equation (2) occurs at the cathode electrode. In the fuel cell stack 20 as a whole, the electromotive reaction of the formula (3) occurs.
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)

FIG. 2 is an exploded perspective view of the cells 21 constituting the fuel cell stack 20.
The cell 21 includes a polymer electrolyte membrane 22, an anode electrode 23, a cathode electrode 24, and separators 26 and 27. The anode electrode 23 and the cathode electrode 24 are diffusion electrodes having a sandwich structure with the polymer electrolyte membrane 22 sandwiched from both sides.

  Separators 26 and 27 made of a gas-impermeable conductive member form fuel gas and oxidizing gas flow paths between the anode electrode 23 and the cathode electrode 24 while sandwiching the sandwich structure from both sides. . The separator 26 is formed with a rib 26a having a concave cross section.

  When the anode electrode 23 comes into contact with the rib 26a, the opening of the rib 26a is closed and a fuel gas flow path is formed. The separator 27 is formed with a rib 27a having a concave cross section. When the cathode electrode 24 comes into contact with the rib 27a, the opening of the rib 27a is closed and an oxidizing gas flow path is formed.

  The anode electrode 23 is mainly composed of a carbon powder supporting a platinum-based metal catalyst (Pt, Pt—Fe, Pt—Cr, Pt—Ni, Pt—Ru, etc.), and a catalyst layer 23 a in contact with the polymer electrolyte membrane 22. And a gas diffusion layer 23b formed on the surface of the catalyst layer 23a and having both air permeability and electronic conductivity. Similarly, the cathode electrode 24 has a catalyst layer 24a and a gas diffusion layer 24b.

  More specifically, the catalyst layers 23a and 24a are made by dispersing carbon powder carrying platinum or an alloy made of platinum and another metal in an appropriate organic solvent, adding an appropriate amount of an electrolyte solution to form a paste, and forming a polymer electrolyte. Screen-printed on the film 22. The gas diffusion layers 23b and 24b are formed of carbon cloth, carbon paper, or carbon felt woven with carbon fiber yarns.

  The polymer electrolyte membrane 22 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluororesin, and exhibits good electrical conductivity in a wet state. A membrane-electrode assembly 25 is formed by the polymer electrolyte membrane 22, the anode electrode 23, and the cathode electrode 24.

  Returning to FIG. 1, a voltage sensor 71 for detecting the output voltage (FC voltage) of the fuel cell stack 20 and a current sensor 72 for detecting the output current (FC current) are attached to the fuel cell stack 20. Yes.

  The oxidizing gas supply system 30 has an oxidizing gas passage 33 through which oxidizing gas supplied to the cathode electrode of the fuel cell stack 20 flows and an oxidizing off gas passage 34 through which oxidizing off gas discharged from the fuel cell stack 20 flows. . In the oxidizing gas passage 33, an air compressor 32 that takes in the oxidizing gas from the atmosphere via the filter 31, a humidifier 35 for humidifying the oxidizing gas pressurized by the air compressor 32, and the fuel cell stack 20 are connected. A shutoff valve A1 for shutting off the oxidizing gas supply is provided.

  In the oxidizing off gas passage 34, a shutoff valve A2 for shutting off the oxidizing off gas discharge from the fuel cell stack 20, a back pressure adjusting valve A3 for adjusting the oxidizing gas supply pressure, oxidizing gas (dry gas) and oxidizing A humidifier 35 is provided for exchanging moisture with off-gas (wet gas).

  The fuel gas supply system 40 includes a fuel gas supply source 41, a fuel gas passage 43 through which fuel gas supplied from the fuel gas supply source 41 to the anode electrode of the fuel cell stack 20 flows, and fuel discharged from the fuel cell stack 20. A circulation passage 44 for returning off-gas to the fuel gas passage 43, a circulation pump 45 for pressure-feeding the fuel off-gas in the circulation passage 44 to the fuel gas passage 43, and an exhaust / drain passage 46 branched and connected to the circulation passage 44 Have.

  The fuel gas supply source 41 is composed of, for example, a high-pressure hydrogen tank or a hydrogen storage alloy, and stores high-pressure (for example, 35 MPa to 70 MPa) hydrogen gas. When the shut-off valve H1 is opened, the fuel gas flows out from the fuel gas supply source 41 into the fuel gas passage 43. The fuel gas is decompressed to about 200 kPa, for example, by the regulator H2 and the injector 42, and supplied to the fuel cell stack 20.

  The circulation passage 44 is connected to a shutoff valve H4 for shutting off the fuel off-gas discharge from the fuel cell stack 20 and an exhaust drainage passage 46 branched from the circulation passage 44. An exhaust / drain valve H5 is disposed in the exhaust / drain passage 46. The exhaust / drain valve H <b> 5 is operated according to a command from the controller 60, thereby discharging the fuel off-gas containing impurities in the circulation passage 44 and moisture to the outside.

  The fuel off-gas discharged through the exhaust / drain valve H5 is mixed with the oxidizing off-gas flowing through the oxidizing off-gas passage 34 and diluted by a diluter (not shown). The circulation pump 45 circulates and supplies the fuel off gas in the circulation system to the fuel cell stack 20 by driving the motor.

  The power system 50 includes a DC / DC converter 51, a battery (power storage device) 52, a traction inverter 53, a traction motor 54, and auxiliary machinery 55. The DC / DC converter 51 boosts the DC voltage supplied from the battery 52 and outputs it to the traction inverter 53, and the DC power generated by the fuel cell stack 20, or the regenerative power collected by the traction motor 54 by regenerative braking. And a function of charging the battery 52 by stepping down the voltage.

  The battery 52 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 battery 52, 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 battery 52 is attached with an SOC sensor for detecting an SOC (State of charge) which is the remaining capacity (charged amount).

  The traction inverter 53 is, for example, a PWM inverter driven by a pulse width modulation method, and converts a DC voltage output from the fuel cell stack 20 or the battery 52 into a three-phase AC voltage in accordance with a control command from the controller 60. The rotational torque of the traction motor 54 is controlled. The traction motor 54 is a three-phase AC motor, for example, and constitutes a power source of the fuel cell vehicle.

  Auxiliary machines 55 are motors (for example, power sources such as pumps) arranged in each part in the fuel cell system 10, inverters for driving these motors, and various on-vehicle auxiliary machines. (For example, an air compressor, an injector, a cooling water circulation pump, a radiator, etc.) is a general term.

  The controller 60 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 10. For example, when the controller 60 receives the start signal IG output from the ignition switch, the controller 60 starts the operation of the fuel cell system 10, and the accelerator opening signal ACC output from the accelerator sensor or the vehicle speed signal output from the vehicle speed sensor. The required power of the entire system is obtained based on VC or the like. The required power of the entire system is the total value of the vehicle running power and the auxiliary machine power.

  Auxiliary power includes power consumed by in-vehicle accessories (humidifiers, air compressors, hydrogen pumps, cooling water circulation pumps, etc.), and equipment required for vehicle travel (transmissions, wheel control devices, steering devices, and Power consumed by a suspension device or the like, and power consumed by a device (such as an air conditioner, a lighting fixture, or audio) disposed in the passenger space.

  The controller 60 determines the distribution of the output power of each of the fuel cell stack 20 and the battery 52, and the oxidizing gas supply system 30 and the fuel gas supply system 40 so that the power generation amount of the fuel cell stack 20 matches the target power. And the DC / DC converter 51 to adjust the output voltage of the fuel cell stack 20, thereby controlling the operation point (output voltage, output current) of the fuel cell stack 20.

<Operation control example of fuel cell system>
Next, an example of control during load operation of the fuel cell system 10 will be described with reference to the flowchart of FIG. 3 and the time charts of FIGS. 4 and 5.

  Note that in FIG. 4 and FIG. 5 that is an enlarged view of FIG. 4, a solid line indicates an operation example when voltage control according to the required output for the fuel cell stack 20 is performed, and a one-dot chain line indicates a fuel cell. The operation example at the time of performing voltage control concerning the present invention to the demand output to stack 20 is shown.

  In addition, the load operation refers to the operation control by calculating the power generation command value of the fuel cell stack 20 based on the accelerator opening, the vehicle speed, etc., and the fuel cell stack 20 supplies the power required for vehicle travel and the power required for system operation. This is an operation that is covered only by the generated power or by the power generated by the fuel cell stack 20 and the discharged power from the battery 52. The

  During the load operation, the controller 60 determines whether or not the required voltage V corresponding to the power generation command value for the fuel cell stack 20 is in a certain voltage range at a predetermined control cycle (step of FIG. 3). S1). This voltage range is a platinum elution voltage range defined by a lower limit threshold voltage (predetermined control start voltage, catalyst elution start voltage) V1 and an upper limit threshold voltage V2.

  When the determination result of step S1 is “No”, that is, when the required voltage V for the fuel cell stack 20 is less than the lower threshold voltage V1 or exceeds the upper threshold voltage V2 (interval of time T3 to T4 in FIG. 4). The controller 60 continues the normal load operation for controlling the output voltage so as to obtain the required voltage gradient with respect to the change (increase / decrease) in the required output to the fuel cell stack 20 (step S27). That is, the voltage command value for the fuel cell stack 20 is the same voltage as the required voltage.

  On the other hand, when the determination result in step S1 is “Yes”, that is, when the required voltage V for the fuel cell stack 20 is in the range of the lower limit threshold voltage V1 to the upper limit threshold voltage V2 (time T1 to time T1 in FIG. 4). T2, time T2 to T3, and time T4 to T5), in other words, in the voltage range where platinum of the catalyst layer 24a elutes, the controller 60 changes (increases or decreases) the required output to the fuel cell stack 20. It is determined whether or not the voltage gradient of the required voltage calculated from (1) exceeds “0” (step S3).

  When the determination result of step S3 is “Yes”, that is, the voltage gradient of the required voltage with respect to the fuel cell stack 20 is positive (rising gradient), in other words, when the required voltage is increasing (for example, the time in FIG. 5) In the period from t1 to t2, the controller 60 sets a new voltage gradient obtained by multiplying the voltage gradient by a predetermined coefficient α (where α <1) (step S11).

  As a result, the command voltage to the DC / DC converter 51 is set to a voltage lower than the required voltage calculated from the required output (refer to the alternate long and short dash line in the period of time t1 to t2 in FIG. 5), and the catalyst layer The platinum elution of 24a is suppressed. Then, the generated surplus power with respect to the required output at this time is charged in the battery 52.

Thereafter, the controller 60 determines whether or not the remaining capacity SOC of the battery 52 exceeds a predetermined threshold γ (first predetermined value) (step S13).
If the determination result of step S13 is “No”, that is, if the remaining capacity SOC of the battery 52 is insufficient, more specifically, the current remaining capacity SOC is determined for the requested output during the process of step S25 described later. If the power generation shortage cannot be covered by the amount of discharge from the battery 52, the controller 60 continues to charge the battery 52 (step S3).

  When the determination result of step S13 is “Yes”, that is, when the remaining capacity SOC of the battery 52 is sufficient, more specifically, the power generation is insufficient with respect to the required output during the process of step S25 described later with the current remaining capacity SOC. In the case where the amount can be covered by the amount of discharge from the battery 52, the controller 60 sets the command voltage to the DC / DC converter 51 to a voltage lower than the required voltage calculated from the required output for a predetermined time (step S25). .

  At this time, platinum deposition of the catalyst layer 24a can be promoted by setting the command voltage to the DC / DC converter 51 to a voltage that is significantly lower than the required voltage calculated from the required output. Note that the power shortage with respect to the required output at this time is covered by the discharge from the battery 52.

  Then, the controller 60 returns the command voltage to the DC / DC converter 51 to the voltage as in the normal load operation after a predetermined time has elapsed from the start of voltage control in step S25 (step S27).

  On the other hand, when the determination result of step S3 is “No”, that is, when the voltage gradient of the required voltage for the fuel cell stack 20 is zero (zero gradient) or minus (downgradient), in other words, the required voltage is constant or In the case of a decreasing trend, the controller 60 fixes the command voltage to the DC / DC converter 51 to the command voltage at that time and holds it for a predetermined time (step S21 in FIG. 4, times t2 to t3 in FIG. 5). Dash-dot line in the section of).

  Thereby, the output voltage of the fuel cell stack 20 is controlled to be a constant hold voltage V3. For example, in FIG. 4 and FIG. 5, such control is performed when the voltage gradient changes from positive to negative. Therefore, the output voltage of the fuel cell stack 20 is set to a voltage higher than the required voltage. .

Thereafter, the controller 60 determines whether or not the remaining capacity SOC of the battery 52 is less than a predetermined threshold β (second predetermined value) (step S23).
If the determination result in step S23 is “No”, that is, if the remaining capacity SOC of the battery 52 is equal to or greater than the threshold value β, the controller 60 returns the process to step S3.

  While the routines of steps S3, S21, and S23 are repeated, since the required voltage corresponding to the required output exceeds the hold voltage V3 at the beginning of voltage control at the hold voltage V3 set in step S21, the required output However, if the required output is gradually reduced and the required voltage falls below the hold voltage V3, the battery 52 is charged with a power generation shortage with respect to the required output. The capacity SOC gradually decreases.

  When the discharge of the battery 52 proceeds and the remaining capacity SOC becomes less than the threshold value β, that is, when the determination result in step S23 becomes “Yes”, the controller 60 changes the command voltage to the DC / DC converter 51 for a predetermined time. Only the required voltage calculated from the required output is set to a voltage lower than the required voltage (step S25 in FIG. 4, dash-dot line in the period from time t3 to t5 in FIG. 5).

  At this time, the command voltage to the DC / DC converter 51 is set to a voltage significantly lower than the required voltage calculated from the required output, and the platinum deposition of the catalyst layer 24a can be promoted. Note that the power shortage with respect to the required output at this time is covered by the discharge from the battery 52.

  Then, after a predetermined time has elapsed from the start of the voltage control in step S25, the controller 60 proceeds to step S27, and returns the command voltage to the DC / DC converter 51 to the voltage as in the normal load operation (time t5 in FIG. 5). dash-dot line in the section of t6).

  As described above, in the present embodiment, when the required voltage for the fuel cell stack 20 increases in the platinum elution voltage range, the output voltage of the fuel cell stack 20 is controlled to a voltage lower than the required voltage (hereinafter referred to as “the required voltage”). Such control is sometimes referred to as “elution suppression control” for convenience of explanation.) By this, elution of platinum in the catalyst layer 24a, particularly platinum having a small particle diameter, is suppressed.

  Further, in order to precipitate platinum once eluted, in order to promote the precipitation to platinum having a smaller particle size, the output voltage of the fuel cell stack 20 is significantly higher than the required voltage until it is outside the platinum elution voltage range. When a lowering control (hereinafter, this control is sometimes referred to as “deposition promotion control” for convenience of explanation) is required, the remaining capacity of the battery 52 is secured to a predetermined level or more to lower the output voltage to that level. It is necessary.

  In this respect, in the present embodiment, during the elution suppression control, it is possible to charge the power generation surplus power of the fuel cell stack 20 to the battery 52. Therefore, the deposition promotion control is performed due to the shortage of the remaining capacity of the battery 52. There is no inconvenience that is disturbed.

  In particular, when the amount of charge to the battery 52 at the time of elution suppression control is balanced with the amount of discharge from the battery 52 at the time of deposition promotion control, and the total power balance is controlled to zero or near zero, the fuel cell system 10 As a result, output stability as a fuel cell vehicle is also improved.

  As described above, according to the present embodiment, while controlling both elution and deposition of platinum in the catalyst layer 24a, the charge / discharge amount of the battery 52 is balanced and the total power balance is adjusted to zero or near zero. Therefore, it is possible to suppress a decrease in the catalyst performance regardless of the remaining capacity of the battery 52.

<Modification>
As for the catalyst performance, as the performance degradation amount (degree of performance degradation) progresses, the performance degradation speed slows down, and eventually the performance degradation stops. Therefore, based on such a phenomenon, the control exemplified below may be added to the elution suppression control and the precipitation promotion control.

  That is, the controller 60 monitors the performance degradation amount of the catalyst. When the performance degradation amount exceeds the first threshold value (third predetermined value), the controller 60 increases the lower threshold voltage V1 in step S1 of FIG. By reducing the threshold voltage V2, the execution frequency of the elution suppression control and the precipitation promotion control is reduced, and when the performance degradation amount exceeds the second threshold (second threshold> first threshold), the elution suppression control and The precipitation promotion control may not be performed.

Note that the decrease in catalyst performance can be estimated, for example, as follows.
(1) Estimate based on the time change of the output current when the fuel cell stack 20 is operated at a constant voltage. In this case, for example, a map showing the relationship between the time change (gradient) of the output current and the amount of performance degradation is prepared in the controller 60 for each voltage set to a constant value during constant voltage operation.

(2) The controller 60 measures the number of times (the number of cycles) that the output voltage of the fuel cell stack 20 has crossed a predetermined boundary voltage in the vertical direction, and the amount of performance degradation is estimated based on the number of times.

(3) For example, an experimental result as shown in FIG. 6 and a formula obtained by fitting a theoretical formula (see Formula 1) obtained by adding the concept of the oxide film ratio to the Butler-Vollmer formula, and an output current (current density) of the fuel cell 20 ) To estimate the amount of performance degradation.

  In each of the above-described embodiments, the form in which the fuel cell system 10 is used as an in-vehicle power supply system has been illustrated. However, the form of use of the fuel cell system 10 is not limited to this example. For example, the fuel cell system 10 may be mounted as a power source of a mobile body (robot, ship, aircraft, etc.) other than the fuel cell vehicle. Further, the fuel cell system 10 according to the present embodiment may be used as a power generation facility (stationary power generation system) such as a house or a building.

11 Fuel Cell System 12 Fuel Cell 20 Fuel Cell Stack (Fuel Cell)
24a catalyst layer 25 membrane-electrode assembly 51 DC / DC converter 52 battery (power storage device)
60 controller (control device)

Claims (4)

A fuel cell comprising a membrane-electrode assembly in which electrodes having a catalyst layer are disposed on both sides of a polymer electrolyte membrane;
A power storage device connected in parallel to the fuel cell with respect to a load and capable of discharging to the load and charging from the fuel cell;
A control device that sets an output voltage of the fuel cell based on a required output required for the fuel cell, and controls charging / discharging of the power storage device based on the output voltage to be set and the required output; With
When the required voltage corresponding to the required output is equal to or higher than a predetermined control start voltage and the change in the required voltage is on an ascending slope, the control device reduces the output voltage to a voltage lower than the required voltage. Setting and charging the power storage device until the remaining capacity exceeds a first predetermined value, and when the change in the required voltage changes from an ascending gradient to a descending gradient, the output voltage is maintained as it is Discharging until the remaining capacity becomes less than a second predetermined value, and setting the output voltage to a voltage lower than the control start voltage after the end of the discharge ;
The fuel cell system , wherein the control start voltage is set to a catalyst elution start voltage of the catalyst layer . The fuel cell system according to claim 1, wherein
The control device controls charge / discharge of the power storage device, which is performed when a required voltage corresponding to the required output is equal to or higher than the predetermined control start voltage, so that a charge amount and a discharge amount are the same. Battery system. The fuel cell system according to claim 1 or 2,
The control device maintains the output voltage at a constant voltage while discharging the power storage device until the remaining capacity reaches a second predetermined value. The fuel cell system according to any one of claims 1 to 3,
The said control apparatus is a fuel cell system which makes the said control start voltage larger than the said catalyst elution start voltage , when the performance fall amount of the said catalyst layer becomes below 3rd predetermined value.

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