JP2013101844A - Fuel cell system and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system and a control method for the same, capable of minimizing the deterioration of a fuel cell catalyst in a fuel cell system.SOLUTION: A fuel cell system 100 includes: a fuel cell 10 being as a supply source of an electric power; and a secondary battery 81 functioning as a supply source of an electric power along with the fuel cell 10. A control part 20 of the fuel cell system 100 carries out a temporal electric voltage drop processing that temporarily reduces the voltage of the fuel cell 10 and increases the generated water in the fuel cell 10 after detecting a condition in which the operation temperature of the fuel cell 10 is higher than a prescribed value. The control part 20 changes a content of the temporal voltage drop processing depending on the secondary battery 81 charging state and the fuel battery 10 operation state when carrying out a temporal voltage drop processing.

Description

  The present invention relates to a fuel cell.

  A polymer electrolyte fuel cell (hereinafter simply referred to as “fuel cell”) usually includes a membrane electrode assembly in which electrodes are arranged on both sides of an electrolyte membrane having proton conductivity as a power generator. A catalyst for promoting the fuel cell reaction is supported on the electrode. By the way, in a fuel cell system mounted on a fuel cell vehicle or the like, there is a case where a high load operation requiring a remarkably high output is continued for a long period of time. If the fuel cell is continuously operated at a high voltage, the operating temperature of the fuel cell rises, an oxide film is formed on the surface of the catalyst, and the catalyst performance may be deteriorated (the following Patent Document 1, etc.). ).

  In a fuel cell system in which a secondary battery is mounted as an auxiliary power source, when the high load operation as described above is continued, the fuel cell is allowed to generate power so that catalyst deterioration does not proceed. It is possible to make the secondary battery compensate for the shortage. However, the capacity of the secondary battery is limited. Therefore, in order to continue high-load operation in the fuel cell system while suppressing deterioration of the catalyst of the fuel cell, it is desirable that the output of the fuel cell and the output of the secondary cell be controlled more efficiently. .

JP 2010-027297 A JP 2005-129252 A JP 2010-153079 A

  An object of this invention is to provide the technique which can suppress deterioration of the catalyst of a fuel cell in a fuel cell system.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A fuel cell system, a fuel cell that is a power supply source, a secondary battery that functions as a power supply source together with the fuel cell, and an operating state that detects an operating state of the fuel cell including an operating temperature of the fuel cell A detection unit; a charge state detection unit that detects a charge state of the secondary battery; and a control unit that controls an output of the fuel cell, wherein the control unit has a predetermined operating temperature of the fuel cell. After detecting a high temperature state higher than the temperature of 1, the voltage of the fuel cell is temporarily reduced to execute a temporary voltage reduction process for increasing the generated water in the fuel cell. A fuel cell system that changes processing contents of the temporary voltage reduction processing based on a charged state of a secondary battery and an operating state of the fuel cell.
With this fuel cell system, after the high temperature state of the fuel cell is detected, the generated water in the fuel cell is increased by a temporary voltage reduction process, thereby suppressing the deterioration of the catalyst of the fuel cell. Further, in this fuel cell system, the processing content of the temporary voltage reduction process is changed based on both the operating state of the fuel cell and the charged state of the secondary battery. Therefore, the temporary voltage reduction process can be executed with appropriate processing contents according to the operating state of the fuel cell and the charged state of the secondary battery.

[Application Example 2]
The fuel cell system according to Application Example 1, wherein the control unit detects the operating state of the fuel cell before executing the temporary voltage reduction process, while the fuel cell is in the high temperature state. According to the accumulated time or the power generation characteristics specified by the current and voltage of the fuel cell, setting a set value of a voltage drop period, which is a period for dropping the voltage in the temporary voltage drop process, When the temporary voltage reduction process is executed using the set value of the voltage reduction period and the preset value of the voltage reduction amount that is an amount to reduce the voltage in the preset temporary voltage reduction process, The secondary battery obtains a predicted value of the amount of power that is stored or discharged, and based on the predicted value and the charged amount of the secondary battery obtained based on the state of charge of the secondary battery, Temporary voltage drop Physical processing conditions, or to change the method of reducing the voltage of the fuel cell in the temporary voltage drop process, the fuel cell system.
In this fuel cell system, when the temporary voltage reduction process is executed, the temporary voltage reduction process is performed based on the amount of power stored in the secondary battery or the predicted amount of power discharged by the secondary battery. It is possible to appropriately change the processing conditions and the voltage reduction method. Therefore, it is possible to execute a process for suppressing deterioration of the catalyst performance of the fuel cell by using the secondary battery more efficiently.

[Application Example 3]
In the fuel cell system according to Application Example 2, the temporary voltage reduction process is accompanied by an increase in current according to the power generation characteristics of the fuel cell when the voltage drops, and the control unit In the case where the temporary voltage reduction process is executed while supplying power according to the demand, the predicted value of the amount of power discharged from the secondary battery when the temporary voltage reduction process is executed, and the second Based on the amount of electric power that can be discharged by the secondary battery, when the temporary voltage reduction process is executed, the set value of the voltage reduction period, so that the amount of electric power discharged by the secondary battery is not insufficient, or A fuel cell system that changes at least one of the set values of the voltage drop amount and executes the temporary voltage drop process.
With this fuel cell system, even if the amount of power stored in the secondary battery is insufficient during execution of the temporary voltage reduction process, the execution is ensured by changing the processing conditions of the temporary voltage reduction process. Is done. Therefore, it is possible to more reliably suppress the deterioration of the catalyst performance of the fuel cell.

[Application Example 4]
The fuel cell system according to any one of Application Examples 1 to 3, wherein the control unit is configured such that an operating temperature of the fuel cell is lower than the first temperature after the fuel cell is in the high temperature state. A fuel cell system that executes the temporary voltage reduction process when a high temperature elimination state that is lower than a second temperature is detected.
With this fuel cell system, it is possible to generate a larger amount of generated water after being removed from the high temperature state, and it is possible to execute a temporary voltage reduction process in a temperature range where the effect of recovering the performance of the fuel cell is enhanced. . Therefore, it is possible to more efficiently suppress the deterioration of the catalyst performance of the fuel cell.

[Application Example 5]
In the fuel cell system according to Application Example 4, after the execution of the temporary voltage reduction process, the control unit further detects the current and voltage of the fuel cell as the operating state of the fuel cell, Based on the power generation characteristics of the fuel cell specified by the current and voltage of the fuel cell, the fuel cell voltage is lower than the detected voltage while maintaining the power being output by the fuel cell. A fuel cell system that performs a constant output voltage reduction process that temporarily decreases the voltage to 2 to increase the current of the fuel cell.
In this fuel cell system, in addition to the temporary voltage reduction process using the secondary battery, the output constant voltage reduction process for reducing the voltage while maintaining the output power of the fuel cell is executed. Degradation of the catalyst performance of the fuel cell can be suppressed.

[Application Example 6]
The fuel cell system according to Application Example 5, wherein the control unit controls a supply amount of a reaction gas to the fuel cell, and the control unit reduces the stoichiometric ratio of the reaction gas and then outputs the constant output voltage. A fuel cell system that executes a reduction process.
With this fuel cell system, it is possible to change the power generation characteristics of the fuel cell due to the reduction in the stoichiometric ratio and ensure the execution of the output constant voltage reduction process.

[Application Example 7]
The fuel cell system according to any one of Application Examples 2 to 5, wherein the control unit is in a state where the fuel cell is in the high temperature state and the power of the fuel cell is not supplied to an external load. When executing the temporary voltage reduction process during a certain high-temperature standby state, when the temporary voltage reduction process is executed, the predicted value of the amount of power stored in the secondary battery, and the second A method for reducing the voltage of the fuel cell in the temporary voltage reduction process based on the processing conditions of the temporary voltage reduction process based on the available capacity of the secondary battery acquired from the storage amount of the secondary battery Change the fuel cell system.
With this fuel cell system, it is possible to execute a temporary voltage reduction process for recovering the performance of the fuel cell by effectively using the standby time of the fuel cell. And execution of a temporary voltage reduction process is securable by changing the processing content of a temporary voltage reduction process based on the empty capacity of a secondary battery.

[Application Example 8]
In the fuel cell system according to Application Example 7, in the case where the control unit executes the temporary voltage reduction process during the high-temperature standby state, when the temporary voltage reduction process is executed, A fuel cell that executes the temporary voltage reduction process by changing at least one of the set value of the voltage drop period or the set value of the voltage drop amount so that the free capacity of the secondary battery is not insufficient. system.
With this fuel cell system, it is possible to execute a temporary voltage reduction process for recovering the performance of the fuel cell by effectively using the standby time of the fuel cell. And the electric power which a fuel cell outputs at the time of execution of a temporary voltage reduction process can be reliably accumulate | stored in a secondary battery.

[Application Example 9]
The fuel cell system according to Application Example 7, further including a short circuit that short-circuits the anode and cathode of the fuel cell to reduce the voltage of the fuel cell, and the control unit is in the high-temperature standby state. In the meantime, as the temporary voltage drop process,
(I) a first voltage reduction process for temporarily increasing the current by temporarily reducing the voltage of the fuel cell and storing the power output from the fuel cell in the secondary battery;
(Ii) a second voltage reduction process for temporarily reducing the voltage of the fuel cell by the short circuit;
The control unit selects and executes either the first or second temporary voltage reduction process based on the predicted value and the free capacity of the secondary battery. A fuel cell system.
With this fuel cell system, when the temporary voltage drop processing is executed using the standby time of the fuel cell, if the secondary battery has insufficient free space, the secondary battery need not be used. Reduce the fuel cell voltage in a viable way. Therefore, it is possible to ensure execution of the temporary voltage reduction process regardless of the available capacity of the secondary battery.

[Application Example 10]
The fuel cell system according to Application Example 7, further including a gas supply unit capable of bypassing the anode gas to the cathode side of the fuel cell, wherein the control unit is configured to perform the temporary voltage during the high-temperature standby state. As a reduction process,
(I) a first voltage reduction process for temporarily increasing the current by temporarily reducing the voltage of the fuel cell and storing the power output from the fuel cell in the secondary battery;
(Iii) a third voltage reduction process for temporarily reducing the voltage of the fuel cell by bypassing the anode gas to the cathode side of the fuel cell by the gas supply unit;
And the control unit selects and executes either the first or the third temporary voltage reduction process based on the predicted value and the free capacity of the secondary battery. A fuel cell system.
With this fuel cell system, if the secondary battery runs out of free space when the temporary voltage drop process is executed using the standby time of the fuel cell, it is executed without using the secondary battery. Reduce the voltage of the fuel cell in a possible way. Therefore, it is possible to ensure execution of the temporary voltage reduction process regardless of the available capacity of the secondary battery.

[Application Example 11]
The fuel cell system according to Application Example 7, further including an external power source capable of applying a voltage with the cathode side set to plus and the anode side set to minus to the fuel cell, and the control unit is in the high-temperature standby state During the temporary voltage drop process,
(I) a first voltage reduction process for temporarily increasing the current by temporarily reducing the voltage of the fuel cell and storing the power output from the fuel cell in the secondary battery;
(Iv) In a state where supply of the reaction gas to the fuel cell is stopped, a voltage is applied to the fuel cell by the external power source to reduce the voltage of the fuel cell, and then the supply of the reaction gas is performed. A fourth voltage drop process for restarting and recovering the voltage of the fuel cell;
The control unit selects and executes either the first or the fourth temporary voltage reduction process based on the predicted value and the free capacity of the secondary battery. A fuel cell system.
With this fuel cell system, when the temporary voltage drop processing is executed using the standby time of the fuel cell, if the secondary battery has insufficient free space, the secondary battery need not be used. Reduce the fuel cell voltage in a viable way. Therefore, it is possible to ensure execution of the temporary voltage reduction process regardless of the available capacity of the secondary battery.

[Application Example 12]
A control method for a fuel cell system, comprising: a fuel cell that is a power supply source; and a secondary battery that functions as a power supply source together with the fuel cell,
(A) detecting an operating temperature of the fuel cell;
(B) Temporary voltage reduction processing for increasing the generated water in the fuel cell by temporarily reducing the voltage of the fuel cell after detecting a high temperature state where the operating temperature of the fuel cell is higher than a predetermined temperature. A step of executing
With
The step (b) changes the processing contents of the temporary voltage reduction process based on the state of charge of the secondary battery and the operating state of the fuel cell before executing the temporary voltage reduction process. The control method including the process to do.
With this fuel cell system, after the high temperature state of the fuel cell is detected, the generated water in the fuel cell is increased by a temporary voltage reduction process, thereby suppressing the deterioration of the catalyst of the fuel cell. Further, in this fuel cell system, the processing content of the temporary voltage reduction process is changed based on both the operating state of the fuel cell and the charged state of the secondary battery. Therefore, the temporary voltage reduction process can be executed with appropriate processing contents according to the operating state of the fuel cell and the charged state of the secondary battery.

  The present invention can be realized in various forms, for example, in the form of a fuel cell system, a vehicle equipped with the fuel cell system, and the like. The present invention can also be realized in the form of a control method for a fuel cell system, a control device and program for executing the control method, a recording medium on which the program is recorded, and the like.

Schematic which shows the structure of a fuel cell system. Schematic which shows the electrical structure of a fuel cell system. Explanatory drawing which shows the control procedure by the control part of a fuel cell system. Explanatory drawing for demonstrating the output control of the fuel cell system at the time of normal operation execution. Explanatory drawing for demonstrating performance degradation of the catalyst in a high temperature state. Explanatory drawing for demonstrating the processing content of a temporary voltage reduction process. Explanatory drawing for demonstrating the change of the electric power generation characteristic of the fuel cell by a temporary voltage reduction process. Explanatory drawing which shows the control procedure of performance recovery driving | operation. Explanatory drawing for demonstrating the relationship between high temperature exposure time and the upper limit of a voltage fall period. Explanatory drawing which shows an example of the voltage change of a fuel cell during performance recovery operation being performed repeatedly. Explanatory drawing which shows the control procedure of the performance recovery driving | operation as 2nd Example. Explanatory drawing which shows an example of the voltage change of a fuel cell while the temporary voltage reduction process of 2nd Example is performed repeatedly. Explanatory drawing which shows the control procedure of the performance recovery driving | operation as 3rd Example. Explanatory drawing which shows the map for acquiring the voltage fall period with respect to the cell voltage of a fuel cell. Explanatory drawing which shows the control procedure of the performance recovery driving | operation as 4th Example. Schematic which shows the electrical structure of the fuel cell system as 5th Example. Explanatory drawing which shows the control procedure in the performance recovery driving | operation of 5th Example. Explanatory drawing which shows the control procedure of the performance recovery driving | operation as another structural example of 5th Example. Schematic which shows the structure of the fuel cell system as a 6th Example. Explanatory drawing which shows the control procedure in the performance recovery driving | operation of 6th Example. Explanatory drawing which shows the control procedure of the performance recovery driving | operation as another structural example of 6th Example. Schematic which shows the electrical structure of the fuel cell system as a 7th Example. Explanatory drawing which shows the control procedure in the performance recovery driving | operation of 7th Example. Explanatory drawing which shows the control procedure of the performance recovery driving | operation as another structural example of 7th Example. Explanatory drawing which shows the control procedure of the system control by the control part of the fuel cell system of 8th Example. Explanatory drawing which shows the control procedure of the performance recovery driving | operation in 8th Example. Explanatory drawing which shows the control procedure of the system control by the control part of the fuel cell system of 9th Example. The schematic diagram for demonstrating the fall cause of the pressure loss of the anode gas in a fuel cell. Explanatory drawing for demonstrating the determination process based on the IV characteristic and IP characteristic of a fuel cell. Explanatory drawing which shows the control procedure of the system control by the control part of the fuel cell system of 10th Example. Explanatory drawing which shows the control procedure of the performance recovery driving | operation accompanied by a change of stoichiometric ratio. Explanatory drawing for demonstrating the change of the IV characteristic and the IP characteristic of the fuel cell 10 by the fall of a stoichiometric ratio.

A. First embodiment:
FIG. 1 is a schematic diagram showing the configuration of a fuel cell system as an embodiment of the present invention. The fuel cell system 100 is mounted on a fuel cell vehicle or the like, and outputs electric power used as a driving force in response to a request from a driver. The fuel cell system 100 includes a fuel cell 10, a control unit 20, a cathode gas supply unit 30, a cathode gas discharge unit 40, an anode gas supply unit 50, an anode gas circulation discharge unit 60, and a refrigerant supply unit 70. Is provided.

  The fuel cell 10 is a polymer electrolyte fuel cell that generates power by receiving supply of hydrogen (anode gas) and air (cathode gas) as reaction gases. The fuel cell 10 has a stack structure in which a plurality of power generators 11 called single cells are stacked. Each power generation body 11 has a membrane electrode assembly (not shown) that is a power generation body in which electrodes are arranged on both surfaces of the electrolyte membrane, and two separators (not shown) that sandwich the membrane electrode assembly. .

  Here, the electrolyte membrane can be composed of a solid polymer thin film that exhibits good proton conductivity in a wet state. The electrode can be composed of conductive particles carrying a catalyst for promoting a power generation reaction. As the catalyst, for example, platinum (Pt) can be adopted, and as the conductive particles, for example, carbon (C) particles can be adopted.

  The control unit 20 is configured by a microcomputer including a central processing unit and a main storage device. The control unit 20 receives a request for output power and controls each component described below to cause the fuel cell 10 to generate power in response to the request.

  The cathode gas supply unit 30 includes a cathode gas pipe 31, an air compressor 32, an air flow meter 33, an on-off valve 34, and a humidification unit 35. The cathode gas pipe 31 is a pipe connected to the cathode side of the fuel cell 10. The air compressor 32 is connected to the fuel cell 10 via the cathode gas pipe 31 and supplies air compressed by taking in outside air to the fuel cell 10 as cathode gas.

  The air flow meter 33 measures the amount of outside air taken in by the air compressor 32 on the upstream side of the air compressor 32, and transmits it to the control unit 20. The control unit 20 controls the amount of air supplied to the fuel cell 10 by driving the air compressor 32 based on the measured value.

  The on-off valve 34 is provided between the air compressor 32 and the fuel cell 10 and opens and closes according to the flow of supply air in the cathode gas pipe 31. Specifically, the on-off valve 34 is normally closed and opens when air having a predetermined pressure is supplied from the air compressor 32 to the cathode gas pipe 31.

  The humidifying unit 35 humidifies the high-pressure air sent out from the air compressor 32. The control unit 20 controls the humidification amount of air supplied to the fuel cell 10 by the humidification unit 35 in order to maintain the wet state of the electrolyte membrane and obtain good proton conductivity, so that the humidity inside the fuel cell 10 is increased. Adjust the condition. In addition, the humidification part 35 is connected with the cathode exhaust gas piping 41, and uses the water | moisture content in waste gas for humidification of high pressure air.

  The cathode gas discharge unit 40 includes a cathode exhaust gas pipe 41, a pressure regulating valve 43, and a pressure measurement unit 44. The cathode exhaust gas pipe 41 is a pipe connected to the cathode side of the fuel cell 10, and discharges the cathode exhaust gas to the outside of the fuel cell system 100. The pressure regulating valve 43 adjusts the pressure of the cathode exhaust gas in the cathode exhaust gas pipe 41 (back pressure on the cathode side of the fuel cell 10). The pressure measurement unit 44 is provided on the upstream side of the pressure regulating valve 43, measures the pressure of the cathode exhaust gas, and transmits the measured value to the control unit 20. The control unit 20 adjusts the opening degree of the pressure regulating valve 43 based on the measurement value of the pressure measurement unit 44.

  The anode gas supply unit 50 includes an anode gas pipe 51, a hydrogen tank 52, an on-off valve 53, a regulator 54, a hydrogen supply device 55, and a pressure measurement unit 56. The hydrogen tank 52 is connected to the anode of the fuel cell 10 through the anode gas pipe 51, and supplies hydrogen filled in the tank to the fuel cell 10. The fuel cell system 100 may include a reforming unit that reforms a hydrocarbon-based fuel to generate hydrogen instead of the hydrogen tank 52 as a hydrogen supply source.

  The on-off valve 53, the regulator 54, the hydrogen supply device 55, and the pressure measuring unit 56 are provided in the anode gas pipe 51 in this order from the upstream side (hydrogen tank 52 side). The on-off valve 53 opens and closes according to a command from the control unit 20 and controls the inflow of hydrogen from the hydrogen tank 52 to the upstream side of the hydrogen supply device 55. The regulator 54 is a pressure reducing valve for adjusting the pressure of hydrogen on the upstream side of the hydrogen supply device 55, and its opening degree is controlled by the control unit 20.

  The hydrogen supply device 55 can be configured by, for example, an injector that is an electromagnetically driven on-off valve. The pressure measurement unit 56 measures the pressure of hydrogen on the downstream side of the hydrogen supply device 55 and transmits it to the control unit 20. The control unit 20 controls the amount of hydrogen supplied to the fuel cell 10 by controlling the hydrogen supply device 55 based on the measurement value of the pressure measurement unit 56.

  The anode gas circulation discharge unit 60 includes an anode exhaust gas pipe 61, a gas-liquid separation unit 62, an anode gas circulation pipe 63, a hydrogen circulation pump 64, an anode drain pipe 65, a drain valve 66, and a pressure measurement unit 67. With. The anode exhaust gas pipe 61 is a pipe that connects the outlet of the anode of the fuel cell 10 and the gas-liquid separator 62, and anode exhaust gas containing unreacted gas (such as hydrogen and nitrogen) that has not been used for power generation reaction. Guide to the gas-liquid separator 62.

  The gas-liquid separator 62 is connected to the anode gas circulation pipe 63 and the anode drain pipe 65. The gas-liquid separator 62 separates the gas component and moisture contained in the anode exhaust gas, guides the gas component to the anode gas circulation pipe 63, and guides the moisture to the anode drain pipe 65.

  The anode gas circulation pipe 63 is connected downstream of the hydrogen supply device 55 of the anode gas pipe 51. The anode gas circulation pipe 63 is provided with a hydrogen circulation pump 64, and hydrogen contained in the gas component separated in the gas-liquid separation unit 62 by the hydrogen circulation pump 64 is supplied to the anode gas pipe 51. Sent out. As described above, in the fuel cell system 100, hydrogen contained in the anode exhaust gas is circulated and supplied to the fuel cell 10 again to improve the utilization efficiency of hydrogen.

  The anode drain pipe 65 is a pipe for discharging the water separated in the gas-liquid separator 62 to the outside of the fuel cell system 100. The drain valve 66 is provided in the anode drain pipe 65 and opens and closes according to a command from the control unit 20. During operation of the fuel cell system 100, the control unit 20 normally closes the drain valve 66 and opens the drain valve 66 at a predetermined drain timing set in advance or a discharge timing of the inert gas in the anode exhaust gas. .

  The pressure measuring unit 67 of the anode gas circulation discharge unit 60 is provided in the anode exhaust gas pipe 61. The pressure measurement unit 67 measures the pressure of the anode exhaust gas (the back pressure on the anode side of the fuel cell 10) in the vicinity of the outlet of the hydrogen manifold of the fuel cell 10 and transmits the control unit 20.

  The refrigerant supply unit 70 includes a refrigerant pipe 71, a radiator 72, a three-way valve 73, a refrigerant circulation pump 75, and two refrigerant temperature measuring units 76a and 76b. The refrigerant pipe 71 is a pipe for circulating a refrigerant for cooling the fuel cell 10, and includes an upstream pipe 71a, a downstream pipe 71b, and a bypass pipe 71c.

  The upstream side pipe 71 a connects the refrigerant outlet manifold provided in the fuel cell 10 and the inlet of the radiator 72. The downstream pipe 71 b connects the refrigerant inlet manifold provided in the fuel cell 10 and the outlet of the radiator 72. One end of the bypass pipe 71c is connected to the upstream pipe 71a via the three-way valve 73, and the other end is connected to the downstream pipe 71b. The control unit 20 controls the opening and closing of the three-way valve 73, thereby adjusting the amount of refrigerant flowing into the bypass pipe 71c and controlling the amount of refrigerant flowing into the radiator 72.

  The radiator 72 is provided in the refrigerant pipe 71 and cools the refrigerant by exchanging heat between the refrigerant flowing through the refrigerant pipe 71 and the outside air. The refrigerant circulation pump 75 is provided on the downstream side pipe 71b on the downstream side (the refrigerant inlet side of the fuel cell 10) from the connection point of the bypass pipe 71c, and is driven based on a command from the control unit 20.

  The two refrigerant temperature measuring units 76 a and 76 b are provided in the upstream pipe 71 a and the downstream pipe 71 b, respectively, and transmit the measured values to the control unit 20. The control unit 20 detects the operating temperature of the fuel cell 10 from the difference between the measured values of the refrigerant temperature measuring units 76a and 76b. Further, the control unit 20 adjusts the operating temperature of the fuel cell 10 by controlling the rotational speed of the refrigerant circulation pump 75 based on the detected operating temperature of the fuel cell 10.

  The fuel cell system 100 further includes an outside air temperature sensor 101 and a vehicle speed sensor 102 for acquiring vehicle information of the fuel cell vehicle. The outside air temperature sensor 101 detects the temperature outside the fuel cell vehicle and transmits it to the control unit 20. The vehicle speed sensor 102 detects the current speed of the fuel cell vehicle and transmits it to the control unit 20. The control unit 20 appropriately uses information obtained from these sensors for output control of the fuel cell 10.

  FIG. 2 is a schematic diagram showing an electrical configuration of the fuel cell system 100. The fuel cell system 100 includes a secondary battery 81, a DC / DC converter 82, and a DC / AC inverter 83. The fuel cell system 100 also includes a cell voltage measurement unit 91, a current measurement unit 92, an impedance measurement unit 93, and an SOC detection unit 94.

  The fuel cell 10 is connected to a DC / AC inverter 83 via a DC wiring DCL, and the DC / AC inverter 83 is connected to a motor 200 that is a driving force source of the fuel cell vehicle. The secondary battery 81 is connected to the DC wiring DCL via the DC / DC converter 82.

  The secondary battery 81 functions as a power supply source together with the fuel cell 10. The secondary battery 81 can be composed of, for example, a lithium ion battery. The control unit 20 controls the DC / DC converter 82 to control the current / voltage of the fuel cell 10 and the charging / discharging of the secondary battery 81 and variably adjust the voltage level of the DC wiring DCL.

  An SOC detector 94 is connected to the secondary battery 81. The SOC detection unit 94 detects a state of charge (SOC) that is a charged state of the secondary battery 81 and transmits the detected state to the control unit 20. Here, the SOC of the secondary battery 81 means the ratio of the remaining charge (charged amount) of the secondary battery 81 to the charge capacity of the secondary battery 81. The SOC detection unit 94 detects the SOC of the secondary battery 81 by measuring the temperature, power, and current of the secondary battery 81.

  Control unit 20 controls charging / discharging of secondary battery 81 based on the detection value of SOC detection unit 94 such that the SOC of secondary battery 81 falls within a predetermined range. Specifically, when the SOC of the secondary battery 81 acquired from the SOC detection unit 94 is lower than a preset lower limit value, the control unit 20 controls the secondary battery 81 with the power output from the fuel cell 10. Charge. When the SOC of the secondary battery 81 is higher than a preset upper limit value, the secondary battery 81 is discharged.

  The DC / AC inverter 83 converts DC power obtained from the fuel cell 10 and the secondary battery 81 into AC power and supplies the AC power to the motor 200. When regenerative power is generated by the motor 200, the DC / AC inverter 83 converts the regenerative power into DC power. The regenerative power converted into direct current power is stored in the secondary battery 81 via the DC / DC converter 82.

  The cell voltage measurement unit 91 is connected to each power generator 11 of the fuel cell 10 and measures the voltage (cell voltage) of each power generator 11. The cell voltage measurement unit 91 transmits the measurement result to the control unit 20. Note that the cell voltage measurement unit 91 may transmit only the lowest cell voltage among the measured cell voltages to the control unit 20.

  The current measuring unit 92 is connected to the direct current wiring DCL, measures the current value output from the fuel cell 10, and transmits it to the control unit 20. When there is a difference between the measured value and the target value (control value) of the cell voltage and current, the control unit 20 corrects the control value so that the difference is converged, so-called Execute feedback control.

  The impedance measuring unit 93 is connected to the fuel cell 10, measures the impedance of the entire fuel cell 10 by applying an alternating current to the fuel cell 10, and transmits the measured impedance to the control unit 20. The control unit 20 manages the wet state of the electrolyte membrane of the fuel cell 10 based on the measurement result of the impedance measurement unit 93. The open / close switch 95 is provided in the DC wiring DCL, and controls electrical connection between the fuel cell 10 and the secondary battery 81 and the motor 200 based on a command from the control unit 20.

  FIG. 3 is a flowchart showing a control procedure of system control by the control unit 20 of the fuel cell system 100. When the fuel cell system 100 is activated, the control unit 20 starts executing a normal operation for causing the fuel cell 10 to generate power based on a drive request from the driver to the fuel cell vehicle (step S10). Details of output control of the fuel cell 10 during execution of normal operation will be described later.

  The control unit 20 detects the operating temperature of the fuel cell 10 at a predetermined cycle during execution of the normal operation, and determines whether or not the fuel cell 10 is in a high temperature state (step S20). Here, in this specification, the “high temperature state” means a state in which the operating temperature of the fuel cell 10 is higher than a preset threshold (for example, about 80 ° C.). When the fuel cell 10 is not in a high temperature state, the control unit 20 resumes normal operation control (step S10).

  Here, as will be described later, in a fuel cell, when the operation in a high temperature state is continued, the performance of the catalyst supported on the electrode may be deteriorated, and the power generation performance may be lowered. Therefore, in the fuel cell system 100 of the present embodiment, when the fuel cell 10 is in a high temperature state, the control unit 20 starts a performance recovery operation for executing a temporary voltage lowering process described later, and the fuel cell 10 The performance deterioration of the catalyst is suppressed (step S30). It should be noted that this performance recovery operation is periodically repeated while the normal operation of step S10 is performed while the fuel cell 10 is in a high temperature state. A specific control procedure in the performance recovery operation will be described later.

FIG. 4 is an explanatory diagram for explaining output control of the fuel cell system 100 during execution of normal operation. FIG. 4 shows a graph G _IV showing the _IV characteristics of the fuel cell 10 and a graph G _IP showing the _IP characteristics, with the left and right vertical axes representing voltage and power, and the horizontal axis representing current. is there. Usually, the IV characteristic of a fuel cell is represented as a horizontal S-shaped curve graph that decreases as the current increases. In addition, the IP characteristic of the fuel cell is expressed as an upwardly convex curve graph.

  The control unit 20 stores in advance information representing IV characteristics and IP characteristics of the fuel cell 10 as control information for the fuel cell 10. In addition, since the IV characteristic and the IP characteristic of the fuel cell 10 change according to the operating conditions such as the operating temperature of the fuel cell 10, the control unit 20 displays the control information for each of the operating conditions. It is preferable to have.

  The control unit 20 acquires a target current It that should be output by the fuel cell 10 with respect to the required power Pt based on the IP characteristic of the fuel cell 10. Then, the control unit 20 acquires the target voltage Vt of the fuel cell 10 for outputting the target current It based on the IV characteristic of the fuel cell 10. The control unit 20 causes the fuel cell 10 and the secondary battery 81 to output the required power Pt by causing the DC / DC converter 82 to set the voltage of the DC wiring DCL to the target voltage Vt.

  Here, in the fuel cell system 100 of the present embodiment, in order to suppress the deterioration of the catalyst performance of the fuel cell 10 due to the continuation of the operation in the high temperature state, in the performance recovery operation (step S30 in FIG. 3). Then, the temporary voltage drop process described below is executed. In the following, after describing the deterioration of the catalyst performance of the fuel cell due to the continuation of operation in a high temperature state, the specific processing contents of the temporary voltage reduction processing executed by the fuel cell system 100 of the present embodiment will be described.

  FIGS. 5A and 5B are explanatory diagrams for explaining the deterioration of the catalyst performance in a high temperature state. 5A and 5B schematically show a part of the cathode electrode 2 formed on the surface of the electrolyte membrane 1 inside the fuel cell. In FIGS. 5A and 5B, for the convenience of explanation, the upper side of the drawing is shown as having a higher potential. FIG. 5A illustrates the state of the cathode electrode 2 when the normal operation is performed, and FIG. 5B illustrates the state of the cathode electrode 2 in a high temperature state.

In the cathode electrode 2, the catalyst support particles 3 in which the catalyst 3 c is supported on the conductive particles 3 p are included in the ionomer 4 that is the same as or similar to the electrolyte membrane 1 in a porous array. ing. During execution of normal operation, protons (H ⁺ ) conducted from the anode side through the electrolyte membrane 1 can sufficiently reach a region having a high potential through a path formed by moisture in the ionomer 4. (FIG. 5A).

  On the other hand, in the cathode electrode 2 in a high temperature state, a region having a higher potential is dried, and a dry region DA illustrated by a broken line may be formed (FIG. 5B). In this dry area DA, the movement of protons is limited due to low moisture. Therefore, protons are suppressed from reaching the high potential region of the cathode electrode 2, the potential in the dry region DA is not lowered, and the oxide film OL is easily formed on the surface of the catalyst 3c existing in the dry region DA. . When the oxide film OL is formed on the surface of the catalyst 3c, the catalytic performance of the cathode electrode 2 is lowered, which causes a reduction in the power generation performance of the fuel cell.

  Here, when the normal operation is performed, the amount of water generated by the fuel cell reaction is larger because the voltage of the fuel cell 10 is lower and the current is higher than that in the high temperature state. Therefore, during the normal operation, the poisoning substance generated at the cathode electrode 2 can be discharged by the moisture generated in the fuel cell reaction, and the adsorption of the poisoning substance on the outer surface of the catalyst 3c is suppressed. . Further, when the normal operation is performed, even when the oxide film OL has been formed on the surface of the catalyst 3c, as described above, the catalyst 3c is sufficiently in the high potential region. In order to spread, the oxide film OL can be eliminated by a reduction reaction.

  As described above, the deterioration of the catalyst performance during the operation in the high temperature state is mainly caused by the decrease in the proton transfer path and the decrease in the discharge ability of the poisonous substance due to the lack of the moisture amount inside the fuel cell. Therefore, in the fuel cell system 100 of the present embodiment, when the temperature becomes high, the temporary voltage reduction process is executed in the performance recovery operation. In the temporary voltage lowering process of the present embodiment, the current of the fuel cell 10 can be temporarily increased by temporarily lowering the voltage of the fuel cell 10, and the amount of water generated in the fuel cell 10 can be increased. Accordingly, the dry area DA in the cathode electrode 2 is reduced, a proton transfer path to the high potential area can be secured, and the discharge of poisoning substances generated in the cathode electrode 2 can be promoted.

  FIG. 6 is an explanatory diagram for explaining the processing content of the temporary voltage drop processing. FIG. 6 shows an example of the voltage change of the fuel cell 10 when the temporary voltage lowering process is executed, as a graph with the vertical axis representing voltage and the horizontal axis representing time. In the temporary voltage reduction process, the control unit 20 controls the voltage of the fuel cell 10 as follows. The control unit 20 controls the DC / DC converter 82 to reduce the voltage of the fuel cell 10 from the original voltage Vo to Vc, and maintains the reduced voltage Vc for a certain period th.

  Hereinafter, in this specification, the difference Vd between the original voltage Vo and the voltage Vc after the decrease in the temporary voltage decrease process is referred to as a “voltage decrease amount Vd”. In addition, the period th in which the voltage Vc after the decrease in the temporary voltage decrease process is held is referred to as a “voltage decrease period th”.

  After the elapse of the voltage drop period th, the control unit 20 restores the voltage of the fuel cell 10. When the power output from the fuel cell 10 is insufficient with respect to the required power during the voltage reduction period th during which the temporary voltage reduction processing is being performed, the shortage is compensated by the power of the secondary battery 81. Is done. By the way, as shown in FIG. 6, the voltage of the fuel cell 10 after the return is a voltage Vr higher than the original voltage Vo. The reason for this will be described below.

  FIGS. 7A and 7B are explanatory diagrams for explaining changes in the power generation characteristics of the fuel cell due to the temporary voltage drop processing. FIG. 7 (A) is a graph showing the time change of the current of the fuel cell, and FIG. 7 (B) is a graph showing the time change of the voltage of the fuel cell. The graphs of FIGS. 7A and 7B are obtained by experiment, and the time axes on the horizontal axis correspond to each other.

In this experiment, between times t ₁ ~t _2, the current of the fuel cell increases from I ₁ to I _2, was held in I _2, was reduced to I ₁ again (FIG. 7 (A)) . At this time, the voltage of the fuel cell decreased from V ₁ to V _{2 as} the current increased, but when the current was returned to the original current value I ₁ (time t ₂ ), the original voltage next higher voltage V ₃ than V _1, a voltage higher than even V ₁ then is kept for a while (Fig. 7 (B)).

  As described above, after the current is temporarily increased, the current and voltage of the fuel cell no longer correspond to each other because the power generation characteristic of the fuel cell is changed by temporarily increasing the current. . More specifically, the increase in current increases the water content in the fuel cell, promotes the reduction of the oxide film of the catalyst and the discharge of poisonous substances, and restores and improves the power generation performance of the fuel cell. .

  In the fuel cell system 100 of the present embodiment, the current is temporarily increased in the temporary voltage reduction process, as shown in FIG. Therefore, when the voltage is restored in the temporary voltage reduction process, the fuel cell 10 outputs the same power as the power generation performance of the fuel cell 10 is improved. The voltage Vr is higher than the voltage Vo (FIG. 6). Since the improvement in power generation performance is temporary, the voltage of the fuel cell 10 gradually decreases with time.

  Here, as described with reference to FIG. 3, while the fuel cell 10 is in a high temperature state, the normal operation and the performance recovery operation are periodically and alternately performed in the fuel cell system 100. That is, while the fuel cell 10 is in a high temperature state, the above temporary voltage reduction process is repeatedly executed at a constant cycle. As described above, the temporary voltage reduction process can obtain a temporary improvement effect of the power generation characteristics of the fuel cell 10 each time it is executed. Therefore, while the temporary voltage reduction process is repeatedly performed periodically, not only the deterioration of the catalyst performance is suppressed, but also the temporary power generation performance improvement effect can be repeatedly obtained, and the power generation efficiency Will be improved accordingly. Therefore, an increase in the operating temperature of the fuel cell 10 can be suppressed.

  FIG. 8 is a flowchart showing a control procedure of the performance recovery operation in which the temporary voltage lowering process is executed. As described above, this performance recovery operation is repeated periodically while the fuel cell 10 is in a high temperature state (FIG. 3). In step S100, the control unit 20 determines the accumulated time after the fuel cell 10 is detected to have entered the high temperature state, that is, the accumulated time td during which the fuel cell has been exposed to the high temperature state (hereinafter, “high temperature exposure time td”). ").

  Here, the measurement of the high temperature exposure time td is started when the high temperature state of the fuel cell 10 is detected for the first time, that is, at the first execution of the performance recovery operation. Accordingly, when performing the first performance recovery operation, the high temperature exposure time td may be set to a preset initial value in step S100. The high temperature exposure time td may be reset after the fuel cell 10 recovers from the high temperature state and a predetermined period elapses.

  In step S110, the control unit 20 determines the voltage drop period th based on the high temperature exposure time td acquired in step S100. By the way, in general, a fuel cell has a high possibility that its performance deteriorates as the time of exposure to a high temperature state increases. On the other hand, the inventor of the present invention has found through experiments that the degree to which the performance of the fuel cell, which has deteriorated due to the high temperature state, recovers as the voltage drop period th is increased. Then, the present inventors have found that the voltage drop period th has an upper limit at which an improvement in the degree of performance recovery cannot be expected. Therefore, in the fuel cell system 100 of the present embodiment, the control unit 20 uses the relationship between the high-temperature exposure time td and the voltage reduction period th described below, which is prepared in advance, to reduce the voltage in the temporary voltage reduction process. The period th is set to be the upper limit or a value close to the upper limit.

  FIG. 9 is a graph obtained by the experiment of the inventors of the present invention, in which the horizontal axis is the high temperature exposure time and the vertical axis is the upper limit of the voltage drop period. The inventor of the present invention executes a temporary voltage drop process for each fuel cell whose exposure time is changed at a high temperature, and changes the voltage drop period, so that the desired recovery of the IV characteristic of the fuel cell is not observed. The voltage drop period was measured as the upper limit. From this experiment, the relationship between the high temperature exposure time and the upper limit of the voltage drop period is obtained as a graph that draws a convex curve that increases the upper limit of the voltage drop period as the high temperature exposure time increases. I was able to.

  In the fuel cell system 100 of the present embodiment, the control unit 20 stores in advance a map representing the above relationship, and acquires the voltage decrease period th corresponding to the high temperature exposure time td using the map. Thus, in the fuel cell system 100, the temporary voltage reduction process is suppressed from being executed in a long voltage reduction period th that reduces the efficiency of performance recovery.

  Here, in the fuel cell system 100 of the present embodiment, the temporary voltage lowering process is periodically repeated while the high temperature state continues, and the fuel cell 10 is being executed during the temporary voltage lowering process. When the output power is insufficient, the power of the secondary battery 81 is compensated. However, the amount of electricity stored in the secondary battery 81 is limited, and depending on the amount of electricity stored in the secondary battery 81, it may be difficult to repeatedly execute the temporary voltage reduction process. Therefore, in the fuel cell system 100 of the present embodiment, when there is a possibility that the amount of power stored in the secondary battery 81 is insufficient when the temporary voltage lowering process is executed, the processing conditions for the temporary voltage lowering process are changed. To ensure its execution. Specifically, it is as follows.

In step S120, the control unit 20 predicts the amount of power that is deficient when the voltage is reduced to the preset voltage drop amount Vd during the voltage drop period th set in step S110, that is, a secondary value. A predicted value E _P of the electric energy that the battery 81 compensates is calculated. In step S120, when the predicted value E _P is 0 or less, that is, when compensation by the secondary battery 81 is not necessary, the processing in steps S130 to S150 described below is omitted and temporarily performed. The target voltage lowering process (step S160) may be executed.

In step S <b> 130, control unit 20 detects the current SOC of secondary battery 81 by SOC detection unit 94. In step S140, the control unit 20 determines whether or not the insufficient power amount represented by the predicted value E _P calculated in step S110 by the secondary battery 81 can be compensated with the current SOC of the secondary battery 81. To do. Specifically, the control unit 20 obtains electric power that can be output by the secondary battery 81 that is obtained based on the predicted value E _P of the electric energy that the secondary battery 81 compensates and the current SOC of the secondary battery 81. The amount E _S is compared to determine whether the amount of power E _S is sufficiently larger than the predicted value E _P. Alternatively, the control unit 20 is, for example, the secondary battery 81 can output a power amount E _S, may be intended to determine greater or not than the threshold value set based on the predicted value E _P. In this determination process, even if the temporary power reduction process is repeatedly executed, the secondary battery 81 is compensated in the subsequent temporary power reduction process so that the output of the secondary battery 81 is secured. It is good also as what considers the electric energy to do.

If it is determined in step S140 that the current SOC of the secondary battery 81 makes it difficult to compensate for the insufficient power, the control unit 20 can execute a temporary voltage reduction process using the current SOC of the secondary battery 81. The voltage drop period th is corrected so as to become (step S150). That is, the control unit 20, the value of the voltage drop period th, the secondary battery 81 is correct is executed to reduce in accordance with the currently available output power amount E _S, to obtain the voltage drop period th _c corrected. For example, the control unit 20 may correct the voltage drop period th using the following formula (1).
Voltage drop period after correction th _c = (E _S / (α × E _P )) × th (1)
Here, α is an arbitrary real number of 1 or more. In step S140, the secondary battery 81 is compensated for in the subsequent temporary power reduction process so that the output of the secondary battery 81 is ensured even when the temporary power reduction process is repeatedly executed. Correction may be executed in consideration of the amount of power to be used.

In step S160, the control unit 20 decreases the voltage of the fuel cell 10 by Vd during the voltage decrease period th acquired in step S110 or the corrected voltage decrease period th _c . Thereafter, the control unit 20 resumes normal operation. As described above, while the high temperature state of the fuel cell 10 is continued, the performance recovery operation is periodically repeated.

FIG. 10 is a graph showing an example of a voltage change of the fuel cell 10 while the performance recovery operation is repeatedly executed. In this example, the temporary voltage drop process is executed at each time t _n , t _{n + 1} , t _{n + 2} , t _{n + 3} , t _{n + 4} (n is an arbitrary natural number) at intervals of a constant period T. Has been. In the temporary voltage drop processing at the first to fourth times t _{n to} t _{n + 3} , since the voltage drop period th corresponding to the high temperature exposure time td is executed, the period held at a low voltage However, it is getting longer. Then, the temporary voltage drop process at the fifth time t _{n + 4} is executed by the voltage drop period th _c corrected by the shortage of the charged amount of the secondary battery 81. Therefore, in the temporary voltage drop process at the fifth time t _{n + 4,} the period during which the low voltage is held is shorter than in the temporary voltage drop process at the previous fourth time t _{n + 3} . .

  As described above, in the fuel cell system 100 according to the present embodiment, when the fuel cell 10 is in a high temperature state, the temporary voltage lowering process is executed, and deterioration of the catalyst performance is suppressed. In the fuel cell system 100 of the present embodiment, the voltage reduction period th that is a processing condition of the temporary voltage reduction processing is set according to the high temperature exposure time td that is one of the elements indicating the operation state of the fuel cell 10. After that, the secondary battery 81 is changed based on the amount of electricity stored. More specifically, when there is a sufficient margin in the storage amount of the secondary battery 81, the voltage drop period th is an upper limit effective for recovering the performance of the fuel cell 10 with respect to the time during which the high temperature state is continued. (If the value is less than this value, an effect is obtained). The voltage drop period th is corrected to be short when the amount of power stored in the secondary battery 81 is likely to be insufficient in the temporary voltage drop process. Therefore, the operation for suppressing the deterioration of the catalyst performance of the fuel cell 10 can be efficiently executed within a range in which the output of the secondary battery 81 is ensured.

B. Second embodiment:
FIG. 11 is a flowchart showing the control procedure of the performance recovery operation as the second embodiment of the present invention. FIG. 11 is substantially the same as FIG. 8 except that step S151 is provided instead of step S150. The configuration of the fuel cell system in the second embodiment is the same as that described in the first embodiment (FIGS. 1 and 2). Further, the system control executed by the control unit 20 in the fuel cell system of the second embodiment is the same as that described in the first embodiment (FIG. 3).

In the fuel cell system according to the second embodiment, when there is a possibility that the amount of power stored in the secondary battery 81 is insufficient when the temporary voltage reduction process is executed, the temporary voltage reduction process can be executed. As described above, a correction process for changing the voltage drop amount Vd is executed (step S151). That is, the control unit 20, the value of the voltage drop amount Vd, the secondary battery 81 to perform a correction to reduce in accordance with the currently available output power amount E _S. For example, the control unit 20 may correct the voltage drop amount Vd using the following formula (2).
Corrected voltage drop amount _{Vd c = (E S / (} α × E P)) × Vd ... (2)
Here, α is an arbitrary real number of 1 or more. The voltage drop amount Vd is preferably corrected so as to ensure the repeated execution of the temporary voltage drop process.

FIG. 12 is a graph showing an example of a voltage change of the fuel cell 10 while the temporary voltage lowering process of the second embodiment is repeatedly executed. In this example, the temporary voltage lowering process is executed at each time t _n , t _{n + 1} , t _{n + 2} , t _{n + 3} (n is an arbitrary natural number) with a constant period T interval. Then, a temporary voltage drop process at each time t _n ~t _n + ₃ is performed by the voltage drop period th in accordance with the high-temperature exposure time td, the period held at a low voltage, has gradually increased . However, the temporary voltage drop process in the fourth time t _{n + 3,} are executed by the voltage drop amount Vd _c corrected for the amount of charge in the secondary battery 81 is insufficient, the range of decrease of the voltage is reduced ing.

  As described above, in the fuel cell system of the second embodiment, when there is a sufficient margin in the amount of power stored in the secondary battery 81, the voltage drop period th is less than the time during which the high temperature state is continued. The upper limit value is set so that the performance recovery effect of the battery 10 can be obtained. When there is a possibility that the storage amount obtained based on the SOC of the secondary battery 81 is insufficient in the temporary voltage reduction process, the voltage reduction amount Vd is set so that the amount of power discharged from the secondary battery 81 is not insufficient. Is reduced to ensure the execution of the temporary voltage drop process. Therefore, when the high temperature state of the fuel cell 10 is continued, the temporary voltage reduction process can be executed effectively and efficiently.

C. Third embodiment:
FIG. 13 is a flowchart showing the control procedure of the performance recovery operation as the third embodiment of the present invention. FIG. 13 is the same as FIG. 8 except that steps S101 and S111 are provided instead of steps S100 and S110. The configuration of the fuel cell system in the third embodiment is the same as that described in the first embodiment (FIGS. 1 and 2). Further, the procedure of system control executed by the control unit 20 in the fuel cell system of the third embodiment is the same as that described in the first embodiment (FIG. 3).

  In the fuel cell system of the third embodiment, when the execution of the temporary voltage lowering process is started, the control unit 20 detects the current current and cell voltage of the fuel cell 10 in step S101. Here, in the fuel cell system of the third embodiment, the control unit 20 displays a map for determining the voltage drop period th for each current value of the fuel cell 10 with respect to the current cell voltage of the fuel cell 10. Pre-stored. In step S <b> 111, the control unit 20 reads a map corresponding to the detected value of the current of the fuel cell 10, and acquires the voltage decrease period th with respect to the detected value of the cell voltage of the fuel cell 10 using the map.

FIG. 14 is an explanatory diagram showing an example of the map used in step S111 as a graph in which the horizontal axis is the cell voltage and the vertical axis is the voltage drop period. This map is set based on the experimental results of experiments conducted by the inventors of the present invention. In this map, when the cell voltage Vc is equal to or lower than V ₁ , th _max having the highest voltage drop period th is set. Then, when the cell voltage Vc is greater than V ₁ was, the higher the cell voltage Vc, the voltage drop period th is set to be shorter. In the cell voltage Vc is V ₁ larger area, the relationship between the cell voltage Vc and the voltage drop period th is set to draw a curve convex curve below.

  Here, in the fuel cell, in general, the lower the cell voltage value for a certain current value, the higher the possibility that the power generation characteristics of the fuel cell represented by the IV characteristics and the IP characteristics are degraded. There is a high possibility that the power generation performance of the battery is degraded. As described above, this map is prepared for each current value of the fuel cell 10, and can be interpreted as a map that can acquire the voltage drop period th according to the change in the power generation characteristics of the fuel cell 10. Note that the voltage drop period th acquired in the map shown in FIG. 14 cannot be expected to improve the desired level of performance recovery even if the low voltage is held for a longer period in the temporary voltage drop process. The upper limit of the voltage drop period.

  In the fuel cell system of the third embodiment, the voltage drop period th is set according to the power generation characteristics of the fuel cell 10 indicating the current operating state of the fuel cell 10. When the amount of power stored in the secondary battery 81 is sufficient, a temporary voltage reduction process is executed during the voltage reduction period th. When the amount of power stored in the secondary battery 81 is insufficient, the voltage decreases. Correction for reducing the period th is performed to ensure execution of the temporary voltage recovery processing. As described above, in the fuel cell system of the third embodiment, a higher effect can be obtained in a range where the performance recovery operation corresponding to the power generation characteristics of the fuel cell 10 is allowed by the amount of power stored in the secondary battery 81. Can be executed as

D. Fourth embodiment:
FIG. 15 is a flowchart showing the control procedure of the performance recovery operation as the fourth embodiment of the present invention. FIG. 15 is substantially the same as FIG. 8 except that step S125 is added and that steps S121, S141, and S161 are provided instead of steps S120, S140, and S160. The configuration of the fuel cell system of the fourth embodiment is the same as that of the first embodiment (FIGS. 1 and 2), and the control procedure of the system control by the control unit 20 is as described in the first embodiment. The same is true (FIG. 3).

  In the fuel cell system of the fourth embodiment, the temporary voltage drop process is performed while the fuel cell vehicle is stopped, that is, in the standby state of the fuel cell 10 in which the supply of power to the motor 200 is stopped, so-called idling state. When to run. Then, the electric power output from the fuel cell 10 in the temporary voltage reduction process is charged in the secondary battery 81. Specifically, the temporary voltage reduction process is executed as follows.

When the control unit 20 detects that the fuel cell 10 is in a high temperature state during the normal operation, the voltage drop corresponding to the high temperature exposure time td is performed by the same process as described in the first embodiment. The period th is acquired (steps S100 and S110). Then, when the temporary voltage drop processing is executed using the voltage drop period th and the voltage drop amount Vd set as the initial value, the amount of power that will be charged to the secondary battery 81 A predicted value E _P is calculated (step S121).

  In step S125, the control unit 20 determines whether power supply to the motor 200 is stopped and the fuel cell 10 is in a standby state. When the fuel cell 10 is not in the standby state, the control unit 20 returns to the normal operation control from the performance recovery operation. On the other hand, when the fuel cell 10 is in the standby state, the control unit 20 detects the SOC of the secondary battery 81 (step S130).

And the control part 20 determines whether a temporary voltage reduction process is executable based on SOC of the secondary battery 81 (step S141). Specifically, it is determined whether or not the secondary battery 81 can be charged with the amount of power corresponding to the predicted value E _P calculated in step S121. If it is determined in step S141 that the secondary battery 81 does not have sufficient free capacity for charging, the control unit 20 corrects the voltage drop period th as described in the first embodiment. (Step S150). Then, the temporary voltage drop process is executed using the corrected voltage drop period th _c .

  On the other hand, if it is determined in step S141 that the secondary battery 81 has sufficient free capacity, the control unit 20 performs a temporary voltage reduction process according to the voltage reduction period th set in step S110 ( Step S161). In step S161, the power output from the fuel cell 10 is stored in the secondary battery 81.

  As described above, according to the fuel cell system of the fourth embodiment, when the fuel cell 10 is in a high temperature state when the fuel cell vehicle is stopped, the process for recovering the catalyst performance of the fuel cell 10 is performed. Is executed. Therefore, the performance degradation of the fuel cell 10 can be suppressed by effectively utilizing the time such as idling of the fuel cell vehicle. Further, the processing conditions of the temporary voltage lowering process are changed according to the SOC of the secondary battery 81, and the electric power output from the fuel cell 10 can be reliably stored in the temporary voltage lowering process. The waste of energy is suppressed.

E. Example 5:
FIG. 16 is a schematic diagram showing an electrical configuration of a fuel cell system 100A as a fifth embodiment of the present invention. FIG. 16 is substantially the same as FIG. 2 except that the short circuit 110 is connected to the fuel cell 10 and an open / close switch 96 is provided between the secondary battery 81 and the fuel cell 10. The remaining structure of the fuel cell system 100A of the fifth embodiment is the same as that of the first embodiment (FIG. 1). Further, in the fuel cell system 100A of the fifth embodiment, the control unit 20 continuously performs the normal operation until the high temperature state is detected, and after the high temperature state is detected, as in the first embodiment. Performs the performance recovery operation periodically and repeatedly while the high temperature state continues (FIG. 3).

  In the fuel cell system 100A of the fifth embodiment, an open / close switch 96 is provided in the direct current wiring DCL so that the electrical connection between the fuel cell 10 and the secondary battery 81 can be disconnected. The control unit 20 controls the opening / closing operation of the opening / closing switch 96. Further, the fuel cell system 100A of the fifth embodiment is provided with a short circuit 110 capable of short-circuiting the anode and the cathode of the fuel cell 10.

  The short circuit 110 includes a wiring 111 that connects two electrodes of the fuel cell 10, a variable resistor 112, and an open / close switch 113. The variable resistor 112 and the open / close switch 113 are each provided in the wiring 111. The control unit 20 controls the opening / closing of the open / close switch 113 of the short circuit 110 and the resistance of the variable resistor 112.

  The control unit 20 arbitrarily reduces the voltage of the fuel cell 10 by adjusting the resistance of the variable resistor 112 in a state where the electrical connection between the fuel cell 10 and the secondary battery 81 is disconnected by the open / close switch 96. It is possible. In the fuel cell system 100A of the fifth embodiment, a temporary voltage reduction process using the short circuit 110 is executed in the performance recovery operation described below.

  FIG. 17 is a flowchart showing a control procedure in the performance recovery operation executed in the fuel cell system 100A of the fifth embodiment. FIG. 17 is substantially the same as FIG. 15 except that step S162 is provided instead of step S150. In the performance recovery operation of the fifth embodiment, as described in the fifth embodiment, the temporary voltage reduction process is executed while the fuel cell vehicle is stopped, and the output of the fuel cell 10 at that time is secondary. The battery 81 is charged. However, it differs from the performance recovery operation of the fifth embodiment in the points described below.

  In the performance recovery operation of the fifth embodiment, when it is determined that the available capacity of the secondary battery 81 is not sufficient before the execution of the temporary voltage reduction process, the temporary voltage reduction process is performed by the short circuit 110. Is executed (step S162). Specifically, the control unit 20 opens the open / close switch 96, disconnects the electrical connection between the fuel cell 10 and the secondary battery 81, and closes the open / close switch 113 of the short circuit 110 so that the fuel cell 10 Short-circuit the anode and cathode.

  At this time, the supply of the reaction gas to the fuel cell 10 is continued, but the voltage of the fuel cell 10 decreases due to a short circuit between the anode and the cathode. The control unit 20 decreases the voltage of the fuel cell 10 by the voltage decrease amount Vd during the voltage decrease period th. Note that the control unit 20 can adjust the voltage drop amount of the fuel cell 10 by adjusting the resistance value of the variable resistor 112. That is, in the fuel cell system of the fifth embodiment, the temporary voltage reduction process can be executed without charging the secondary battery 81 by using the short circuit 110.

  As described above, in the fuel cell system 100A according to the fifth embodiment, even if the rechargeable battery 81 has insufficient chargeable capacity, the voltage drop can be reduced without correcting the voltage drop period th. The temporary voltage drop process is executed by changing the method. Therefore, reliable performance recovery of the fuel cell 10 exposed to a high temperature state is possible.

E-1. Other configuration examples of the fifth embodiment:
FIG. 18 is a flowchart showing a control procedure of performance recovery operation as another configuration example of the fifth embodiment. FIG. 18 is substantially the same as FIG. 17 except that steps S121, S130, S141, and S161 are omitted, and step S162 is provided after the determination process of step S125. In this configuration example, the configuration of the fuel cell system is the same as that of the fuel cell system 100A of the fifth embodiment described above (FIG. 16). The control procedure of the system control by the control unit 20 is substantially the same as the control procedure described in the fifth embodiment except that the control procedure of the performance recovery operation described below is different.

  In this configuration example, in the performance recovery operation, a temporary voltage lowering process for lowering the voltage by the short circuit 110 is executed regardless of the SOC of the secondary battery 81. That is, if it is determined in step S125 that the fuel cell 10 is in standby, the control unit 20 directly short-circuits the anode and cathode of the fuel cell 10 by the short circuit 110, and the fuel cell 10 Is temporarily reduced (step S162). As described above, in this configuration example, it is possible to execute the process for recovering the performance of the fuel cell 10 regardless of the SOC of the secondary battery 81.

F. Example 6:
FIG. 19 is a schematic diagram showing a configuration of a fuel cell system 100B as a sixth embodiment of the present invention. FIG. 19 is substantially the same as FIG. 1 except that the bypass gas flow path portion 120 is provided. The remaining configuration of the fuel cell system 100B of the sixth embodiment is the same as that of the first embodiment (FIG. 1). Further, in the fuel cell system 100B of the sixth embodiment, the control unit 20 continuously performs the normal operation until the high temperature state is detected, as in the first embodiment, and after the high temperature state is detected. Performs the performance recovery operation periodically and repeatedly while the high temperature state continues (FIG. 3).

  The fuel cell system 100B of the sixth embodiment is provided with a bypass gas flow path section 120 that connects the cathode gas supply section 30 and the anode gas supply section 50. In the fuel cell system 100 </ b> B of the sixth embodiment, the anode gas can be bypassed to the cathode side of the fuel cell 10 by the bypass gas flow path unit 120.

  The bypass gas flow path unit 120 includes a bypass pipe 121, an on-off valve 122, and a pressure regulating valve 123. One end of the bypass pipe 121 is connected to the downstream side of the hydrogen supply device 55 of the anode gas pipe 51, and the other end is connected to the downstream side of the humidifying unit 35 of the cathode gas pipe 31. The on-off valve 122 is provided on the anode gas supply unit 50 side of the bypass pipe 121, and the pressure regulating valve 123 is provided on the cathode gas supply unit 30 side of the bypass pipe 121. The control unit 20 controls the on-off valve 122 and the pressure regulating valve 123 to adjust the flow rate of the anode gas that is bypassed to the cathode gas supply unit 30.

  In the fuel cell system 100B of the sixth embodiment, a temporary voltage reduction process using the bypass gas flow path unit 120 is executed in the performance recovery operation described below. In addition, the bypass gas flow path part 120 is the state by which the on-off valve 122 was closed except at the time of execution of the temporary voltage reduction process demonstrated below.

  FIG. 20 is a flowchart showing a control procedure in the performance recovery operation executed in the fuel cell system 100B of the sixth embodiment. FIG. 20 is substantially the same as FIG. 17 except that step S163 is provided instead of step S162. That is, the performance recovery operation of the sixth embodiment is different from the performance recovery operation of the fifth embodiment except that the contents of the temporary voltage drop process executed when the available capacity of the secondary battery 81 is insufficient are different. It is almost the same.

  In the fuel cell system 100B of the sixth embodiment, when the free capacity of the secondary battery 81 is insufficient, the control unit 20 opens the on-off valve 122 of the bypass gas flow path unit 120 only during the voltage drop period th. Open temporarily. At this time, the control unit 20 also adjusts the opening degree of the pressure regulating valve 123 according to the voltage drop amount Vd.

  By opening the on-off valve 122, part of the anode gas in the anode gas pipe 51 flows into the cathode gas pipe 31, and the anode gas is introduced to the cathode side of the fuel cell 10. As a result, the voltage of the fuel cell 10 can be reduced, and the amount of water inside the fuel cell 10 can be increased by the reaction between the anode gas introduced into the cathode side and the cathode gas. Therefore, recovery of the catalyst performance in the fuel cell 10 is possible.

  As described above, in the fuel cell system 100B of the sixth embodiment, even if the available capacity of the secondary battery 81 is not sufficient, the temporary voltage reduction process does not correct the voltage reduction period th. It is executed by changing the method of voltage drop. Therefore, reliable performance recovery of the fuel cell 10 exposed to a high temperature state is possible.

F-1. Other configuration examples of the sixth embodiment:
FIG. 21 is a flowchart showing a control procedure of performance recovery operation as another configuration example of the sixth embodiment. FIG. 21 is substantially the same as FIG. 18 except that step S163 is provided instead of step S162. The configuration of the fuel cell system in this configuration example is the same as that of the fuel cell system 100B of the sixth embodiment described above (FIG. 19). Further, the control procedure of the system control by the control unit 20 is substantially the same as the control procedure described in the sixth embodiment except that the control procedure of the performance recovery operation described below is different.

  In this configuration example, in the performance recovery operation, the temporary voltage reduction process is executed using the bypass gas flow path unit 120 regardless of the SOC of the secondary battery 81. That is, if the control unit 20 determines in step S125 that the fuel cell 10 is in a standby state, the control unit 20 causes the bypass gas channel unit 120 to bypass the anode gas to the cathode side of the fuel cell 10 with a temporary voltage. A reduction process is executed (step S163). Thus, with this configuration example, regardless of the SOC of the secondary battery 81, the process for restoring the performance of the fuel cell 10 can be reliably executed.

G. Seventh embodiment:
FIG. 22 is a schematic diagram showing an electrical configuration of a fuel cell system 100C as a seventh embodiment of the present invention. FIG. 22 is substantially the same as FIG. 16 except that a voltage application unit 130 is provided instead of the short circuit 110. The remaining configuration of the fuel cell system 100C of the seventh embodiment is the same as that of the first embodiment (FIG. 1). Further, in the fuel cell system 100C of the seventh embodiment, the control unit 20 continuously performs the normal operation until the high temperature state is detected, as in the first embodiment, and after the high temperature state is detected. Performs the performance recovery operation periodically and repeatedly while the high temperature state continues (FIG. 3).

  The fuel cell system 100C of the seventh embodiment is provided with a voltage application unit 130 that applies a voltage to the fuel cell 10 according to a command from the control unit 20. The voltage application unit 130 includes a power supply device 131, a wiring 132, and an open / close switch 133.

  The power supply device 131 is a DC power supply device, and is connected to the fuel cell 10 via the wiring 132 with the cathode side set to minus and the anode side set to plus. The open / close switch 133 is provided on the wiring 132. The control unit 20 controls opening / closing of the open / close switch 133 to switch ON / OFF of the electrical connection between the fuel cell 10 and the power supply device 131. In the fuel cell system 100C of the seventh embodiment, a temporary voltage reduction process using the voltage application unit 130 is executed in the performance recovery operation described below.

  FIG. 23 is a flowchart showing a control procedure in the performance recovery operation executed in the fuel cell system 100C of the seventh embodiment. FIG. 23 is substantially the same as FIG. 20 except that steps S170 to S172 are provided instead of step S163. That is, the performance recovery operation of the seventh embodiment is the same as that of the fifth embodiment or the sixth embodiment except that the contents of the temporary voltage reduction process executed when the charge capacity of the secondary battery 81 is insufficient are different. This is almost the same as the performance recovery operation. In the fuel cell system 100C of the seventh embodiment, when the free capacity of the secondary battery 81 is insufficient, the temporary voltage reduction process is executed according to the following procedure.

  The control unit 20 causes the cathode gas supply unit 30 and the anode gas supply unit 50 to stop supplying the reaction gas (step S170). Then, the open / close switch 133 of the voltage application unit 130 is closed to connect the fuel cell 10 and the power supply device 131. During the voltage drop period th, the fuel cell 10 is negative on the cathode side and positive on the anode side. Is applied (step S171). The applied voltage is set according to the voltage drop amount Vd. Then, when the voltage drop period th elapses, the control unit 20 disconnects the electrical connection between the voltage application unit 130 and the fuel cell 10 and restarts the supply of the reaction gas to the fuel cell 10 (step) S172).

  Here, normally, when the supply of the reaction gas is stopped in the fuel cell, a gradual voltage drop occurs with the consumption of the reaction gas remaining in the fuel cell 10. In the fuel cell system of the seventh embodiment, a voltage is applied to the fuel cell 10 from which the supply of the reaction gas has been stopped by the power supply device 131 to induce protons on the anode side of the fuel cell 10 to the cathode side ( Hydrogen pump), which speeds up the voltage drop. Even in the temporary voltage reduction process using the voltage drop after the supply of the reactive gas is stopped, the amount of water generated in the fuel cell 10 can be temporarily increased, and the catalyst performance of the fuel cell 10 can be recovered.

  As described above, in the fuel cell system according to the seventh embodiment, even if the SOC of the secondary battery 81 is insufficient, the temporary voltage reduction process is executed by changing the voltage reduction method. .

G-1: Other configuration example of the seventh embodiment:
FIG. 24 is a flowchart showing a control procedure of performance recovery operation as another configuration example of the seventh embodiment. FIG. 24 is substantially the same as FIG. 21 except that steps S170 to S172 are provided instead of step S163. In this configuration example, the configuration of the fuel cell system is the same as that of the fuel cell system 100C of the seventh embodiment described above (FIG. 19). Further, the control procedure of the system control by the control unit 20 is substantially the same as the control procedure described in the seventh embodiment except that the control procedure of the performance recovery operation described below is different.

  In this configuration example, the temporary voltage reduction process using the voltage application unit 130 is executed in the performance recovery operation regardless of the SOC of the secondary battery 81. That is, if it is determined in step S125 that the fuel cell 10 is in standby, the control unit 20 temporarily stops the supply of the reaction gas to the fuel cell 10 during the voltage drop period th ( Step S170). Then, a voltage is applied to the fuel cell 10 by the voltage application unit 130, the voltage of the fuel cell 10 is temporarily reduced to a predetermined value (step S171), and after the low voltage state is maintained for a predetermined period, the reaction is performed. The supply of gas is resumed (step S172), and the voltage is restored. In this configuration example, regardless of the SOC of the secondary battery 81, the temporary voltage lowering process for recovering the performance of the fuel cell 10 is reliably performed.

H. Example 8:
FIG. 25 is a flowchart showing a control procedure of system control by the controller 20 of the fuel cell system according to the eighth embodiment of the present invention. FIG. 25 is substantially the same as FIG. 3 except that steps S21 and S25 are provided between steps S20 and S30 and that step S40 is added after step S30. The configuration of the fuel cell system of the eighth embodiment is almost the same as that of the fuel cell system 100 of the first embodiment (FIGS. 1 and 2).

  In the fuel cell system of the eighth embodiment, when there is a history that the fuel cell 10 has been operated in a high temperature state, the temperature of the fuel cell 10 is high when the fuel cell 10 is on standby, such as when the fuel cell vehicle is stopped. The performance recovery operation for recovering the performance of the fuel cell 10 deteriorated by the operation in the state is executed. Specifically, it is as follows.

  In the fuel cell system according to the eighth embodiment, the control unit 20 detects that the operation temperature of the fuel cell 10 is higher than the first temperature (for example, about 90 ° C.) during normal operation. However, control of normal operation is continued as it is (steps S20 and S21). Then, it was detected that the operating temperature of the fuel cell 10 was lower than the second temperature (for example, about 60 ° C.) while the normal operation control continued in step S21 was being executed. Sometimes the performance recovery operation is started (step S30).

  FIG. 26 is a flowchart showing a control procedure in the performance recovery operation executed in the fuel cell system of the eighth embodiment. FIG. 26 is substantially the same as FIG. 8 except that step S100 is omitted and step S111 is provided instead of step S110. When the performance recovery operation is started, the control unit 20 sets the processing conditions (the voltage reduction period th and the voltage reduction amount Vd) of the temporary voltage reduction process to preset values (initial values) (step S111). .

In steps S120 to S150, the necessity of correcting the voltage drop period th is determined based on the current SOC of the secondary battery 81 as described in the first embodiment, and if necessary, The voltage drop period th is corrected according to the amount of power stored in the secondary battery 81. In step S160, the temporary voltage reduction process is executed by the voltage reduction period th set in step S111 or the voltage reduction period th _c corrected in step S150.

  After executing the performance recovery operation, the control unit 20 determines whether or not the performance of the fuel cell 10 has been recovered (step S40 in FIG. 25). Specifically, for example, the voltage and current of the fuel cell 10 are detected, and the power generation characteristics (IV characteristic and IP characteristic) of the fuel cell indicate characteristics within an allowable range at the current operating temperature. It is determined whether or not. While it is determined that the performance of the fuel cell 10 is not recovered, the control unit 20 repeatedly performs the performance recovery operation so that the temporary voltage reduction process is periodically repeated. On the other hand, when it is determined that the performance of the fuel cell 10 is recovered, the normal operation is resumed (step S10).

  As described above, in the fuel cell system according to the eighth embodiment, the catalyst performance of the fuel cell 10 that has decreased in the high temperature operation is recovered by the temporary voltage reduction process after the operating temperature of the fuel cell 10 has decreased. If the operating temperature of the fuel cell 10 is lowered, the wet state inside the fuel cell 10 is likely to be improved. If the temporary voltage reduction process is executed when the wet state is improved, the poisoning substance accumulated in the cathode electrode 2 can be discharged more reliably. Further, protons can surely reach the catalyst 3p where the oxide film has been generated. Therefore, the catalyst performance of the fuel cell 10 can be recovered more effectively.

  In the above description, the voltage drop period th is set to a predetermined initial value in step S111. However, the voltage drop period th is the accumulated time during which the high temperature state is continued, as in the first embodiment. It may be set according to a certain high temperature exposure time td (FIG. 9). Alternatively, as described in the third embodiment, the voltage drop period th may be set according to the current IV characteristic of the fuel cell 10 (FIG. 14). Furthermore, the voltage drop amount Vd may be reduced as the operating temperature of the fuel cell 10 at the time of executing the temporary voltage reduction process is lowered, and the temporary voltage reduction process may be executed.

I. Ninth embodiment:
FIG. 27 is a flowchart showing a control procedure of system control executed by the control unit 20 in the fuel cell system as the ninth embodiment of the invention. FIG. 27 is substantially the same as FIG. 25 except that step S22 is provided instead of step S21 and steps S27, S31, and S32 are provided instead of step S30. The configuration of the fuel cell system of the ninth embodiment is substantially the same as that of the fuel cell system of the eighth embodiment (FIGS. 1 and 2). In the fuel cell system according to the ninth embodiment, after a high temperature state is detected, a temporary voltage lowering process with different processing contents is executed based on the operating state of the fuel cell 10 and the charged state of the secondary battery 81. The Specifically, it is as follows.

  In the fuel cell system of the ninth embodiment, the first performance recovery operation is repeatedly executed while the fuel cell 10 is in a high temperature state (steps S22 and S25). In the first performance recovery operation, operation control similar to any one of the performance recovery operations described in the first to third embodiments is executed (FIGS. 8, 11, and 13). In the first performance recovery operation, the temporary voltage reduction process is executed after changing the processing conditions depending on the current amount of power stored in the secondary battery 81.

  When the operation temperature of the fuel cell 10 falls below a predetermined temperature while the first performance recovery operation is being repeated, the control unit 20 detects deterioration of the current power generation state in the fuel cell 10 ( Step S26). Specifically, in the fuel cell system of the ninth embodiment, in step S26, for example, by detecting a decrease in the pressure loss of the anode gas of the fuel cell 10 that exceeds a specified level, the power generation state in the fuel cell 10 is deteriorated. To detect.

  FIGS. 28A to 28C are schematic diagrams for explaining the cause of the decrease in the pressure loss of the anode gas in the fuel cell 10. 28A to 28C are schematic diagrams of the membrane electrode assembly 15 of the fuel cell 10 as viewed in the direction along the plane on the lower side of the drawing, with the upper side of the drawing being the cathode side, The lower side is shown as the anode side. A graph showing an example of the current density distribution is shown on the upper side of the drawing in correspondence with the left and right positions of the membrane electrode assembly 15 shown on the lower side of the drawing.

  Here, in the fuel cell 10, the reaction gas flows in a direction facing each other with the membrane electrode assembly 15 interposed therebetween (arrows CF, AF). 28A to 28C, the left side of the drawing is illustrated as the upstream side of the cathode gas (downstream side of the anode gas). Further, in FIGS. 28A to 28C, the circulation of moisture in the membrane electrode assembly 15 is schematically shown by a broken line arrow WF, and a portion in the dry state in the membrane electrode assembly 15 is a broken line DA. It is shown by.

  FIG. 28A shows an example of an ideal current density distribution in the fuel cell 10 and a water circulation state at the operating temperature (about 60 ° C. to 80 ° C.) at which the normal operation is performed. In this state, the current density is higher toward the upstream side of the cathode gas (on the left side of the drawing), and a moisture circulation system is formed throughout the membrane electrode assembly 15.

  FIG. 28B shows an example of the current density distribution and the water circulation state in the fuel cell 10 after the operation in the high temperature state. In this state, the membrane electrode assembly 15 is in a dry state on the upstream side of the cathode gas due to the high temperature operation, and the moisture circulation path is formed in a region biased to the downstream side of the cathode gas. However, on the anode side of the membrane electrode assembly 15, the moisture slightly moves to the downstream side due to the flow of the anode gas. In this state, the performance of the catalyst on the upstream side of the cathode gas begins to deteriorate, and the current density distribution is also biased toward the downstream side of the cathode gas.

  FIG. 28C shows an example of the current density distribution and the water circulation state in the fuel cell 10 when the high temperature operation is further continued from the state of FIG. In this state, the downstream side of the cathode gas is almost dried, and no movement of moisture to the downstream side of the anode gas is observed on the anode side. The current is concentrated in a region biased to the downstream side of the cathode gas.

  Here, in the state of FIGS. 28B and 28C, most of the anode gas is consumed in the upstream region (the region on the right side of the drawing). Therefore, the pressure loss is reduced in the anode gas flow path in these states.

  In step S26 (FIG. 27), the control unit 20 determines the anode of the fuel cell 10 from the measurement value of the pressure measurement unit 56 of the anode gas supply unit 50 and the measurement value of the pressure measurement unit 67 of the anode gas circulation discharge unit 60. The pressure loss on the side is detected and compared with a predefined threshold. When the detected pressure loss is within the allowable range, the normal operation (step S10) is resumed.

  On the other hand, when it is determined that the detected pressure loss is higher than the specified value and the power generation state of the fuel cell 10 is deteriorated, the control unit 20 executes the process of step S27. In step S27, the control unit 20 detects the IV characteristic and the IP characteristic of the fuel cell 10 based on the current detected value of the current and voltage of the fuel cell 10, and the current output power of the fuel cell 10. It is determined whether or not the voltage of the fuel cell 10 can be reduced while maintaining the above.

  FIG. 29 is an explanatory diagram for explaining a determination process based on the IV characteristic and the IP characteristic of the fuel cell 10 in step S27. FIG. 29 shows an example of a graph showing the IV characteristics and the IP characteristics of the fuel cell 10 similar to those described in FIG. As described with reference to FIG. 4, in normal operation, the voltage Vt and current It of the fuel cell 10 for outputting the required output Pt are determined based on the IV characteristic and the IP characteristic of the fuel cell 10.

  Here, the IV characteristic and the IP characteristic of the fuel cell 10 change according to the operating temperature of the fuel cell 10. If the operating temperature of the fuel cell 10 is a normal temperature (about 60 ° C. to about 80 ° C.), as shown in FIG. 29, the curve graph showing the IP characteristic of the fuel cell 10 shows the current value at the apex. There is a region showing a higher current value (hereinafter referred to as a “high current region”).

  On the other hand, when the fuel cell 10 is in a high temperature state (the operation temperature is about 90 ° C. or higher), there is a high possibility that the high current region hardly exists in the curve indicating the IP characteristic of the fuel cell 10. In normal operation, the output of the fuel cell 10 is controlled in a current region (hereinafter referred to as a “low current region”) on the side lower than the current value at the top of the curve graph showing the IP characteristic (hereinafter referred to as “low current region”). The

In the graph showing the IP characteristics of the fuel cell 10, when a high current region exists, the current value for the required output Pt includes It _high which is a current value higher than It, along with It used in normal operation. To do. As a voltage value for the required output Pt, Vt _low that is a voltage value lower than Vt exists together with Vt used in normal operation.

In step S27 (FIG. 27), the control unit 20 can output the required output Pt at the voltage Vt _low based on the current power generation characteristics (IV characteristics and IP characteristics) of the fuel cell 10. Is determined, the second performance recovery operation is executed (step S31). In the second performance recovery operation, a temporary voltage lowering process is executed to temporarily reduce the voltage to the high current region side voltage Vt _low while causing the fuel cell 10 to output the required output Pt.

On the other hand, if the control unit 20 determines in step S27 that the voltage Vt _low with respect to the requested output Pt does not exist based on the current IV characteristics and the IP characteristics of the fuel cell 10, the third performance is provided. Recovery operation is executed (step S32). This third performance recovery operation is executed by the same control procedure (FIG. 26) as the performance recovery operation executed in the eighth embodiment. That is, first, the processing condition of the temporary voltage drop process is set to the initial value. And if the amount of charge of the secondary battery 81 is sufficient, the temporary voltage drop process is executed in the set voltage drop period, and if the amount of charge of the secondary battery 81 is not enough, it is corrected. Temporary voltage drop processing is executed during the voltage drop period.

  In the fuel cell system of the ninth embodiment, after the second performance recovery operation (step S31) or the third performance recovery operation (step S32), the power generation state deterioration determination process in step S26 is performed again. Is executed. That is, in the fuel cell system of the ninth embodiment, during the operation of either the second performance recovery operation or the third performance recovery operation until the pressure loss of the anode gas falls within the allowable range, The voltage reduction process is executed at a predetermined cycle.

  As described above, in the fuel cell system according to the ninth embodiment, when the fuel cell 10 is in a high temperature state, the first performance recovery operation is executed, and deterioration of the catalyst performance of the fuel cell 10 is suppressed. Then, while the first performance recovery operation is being repeated, efficient operation with the power generation of the fuel cell 10 temporarily improved is possible, so that the temperature of the fuel cell 10 is further increased. Avoided. In the fuel cell system according to the ninth embodiment, when it is detected that the power generation state of the fuel cell 10 has deteriorated due to the operation in the high temperature state, the second or third performance recovery operation is performed. Is executed, and the degradation of the power generation state is resolved. In particular, in the second performance recovery operation, power compensation by the secondary battery 81 can be omitted by maintaining the output of the fuel cell 10, so that the performance recovery of the fuel cell 10 can be achieved more efficiently. It is.

J. Tenth embodiment:
FIG. 30 is a flowchart showing a control procedure of system control executed by the control unit 20 in the fuel cell system as the tenth embodiment of the present invention. FIG. 30 is substantially the same as FIG. 27 except that step S33 is provided instead of step S31. The configuration of the fuel cell system of the tenth embodiment is almost the same as that of the fuel cell system of the ninth embodiment (FIGS. 1 and 2). In the fuel cell system of the tenth embodiment, system control similar to that of the fuel cell system of the ninth embodiment is executed except that a performance recovery operation (step S33) accompanied by a change in the stoichiometric ratio described below is executed. Is done.

  FIG. 31 is a flowchart showing the control procedure of the performance recovery operation accompanied by the change in the stoichiometric ratio executed in step S33. In this performance recovery operation, after the fuel cell 10 goes through a high temperature state, deterioration of the power generation state is detected in the fuel cell 10, and further, based on the IV characteristics and the IP characteristics of the fuel cell 10, the fuel cell 10 It is executed when it is determined that the voltage can be lowered while maintaining the output.

  In step S <b> 200, the control unit 20 controls the cathode gas supply unit 30 to execute a process for reducing the stoichiometric ratio in the fuel cell 10. Here, the “stoichiometric ratio” means the ratio of the actual supply amount of cathode gas to the amount of cathode gas theoretically required (theoretical consumption of cathode gas) with respect to the power generation amount of the fuel cell. In step S200, the control unit 20 causes the cathode gas supply unit 30 to reduce the supply amount of the cathode gas. Thus, by reducing the stoichiometric ratio in the fuel cell 10, the IV characteristics and the IP characteristics of the fuel cell 10 can be changed.

FIG. 32 is an explanatory diagram for explaining changes in the IV characteristic and the IP characteristic of the fuel cell 10 due to a decrease in the stoichiometric ratio. FIG. 32 shows an example of a graph showing the IV characteristics and the IP characteristics of the fuel cell 10. In FIG. 32, graphs PG _IV and PG _IP showing the _IV characteristics and the _IP characteristics of the fuel cell 10 before the stoichiometric ratio change are shown by broken lines, and the _IV of the fuel cell 10 after the stoichiometric ratio change is shown. The graphs G _IV and G _IP showing the characteristics and the _IP characteristics are shown by solid lines.

  Generally, in a fuel cell, when the stoichiometric ratio is lowered, the power generation characteristics are lowered. That is, the graph showing the IV characteristic is lowered as a whole, and the graph showing the IP characteristic is shifted toward the region of higher current as the apex position is lowered. It changes to a gentle curve.

Here, in the example of FIG. 32, before the stoichiometric ratio change, based on the graphs PG _IV and PG _IP of the _IV characteristics and the _IP characteristics, the first and second voltages Vt, Vt _low (Vt> Vt _low ) can be acquired. After the stoichiometric ratio is changed, based on the graphs G _IV and G _IP of the _IV characteristics and the _IP characteristics, as the voltages for the same required output Pt, from the first and second voltages Vt and Vt _{low described} above. The lower third and fourth voltages Vt ₁ and Vt ₂ (Vt ₁ > Vt ₂ ) can be acquired.

Thus, by lowering the stoichiometric ratio, there may be a case where the fuel cell 10 can set a lower voltage value for the same required output Pt as before the stoichiometric ratio is changed. In the fuel cell system of the tenth embodiment, in step S210, the voltage Vt ₂ of FIG. 32 is obtained with respect to the current required output in the IV characteristics and the IP characteristics of the fuel cell 10 after the change in the stoichiometric ratio. It is determined whether or not the corresponding voltage on the high current region side can be set.

When the voltage on the high current region side can be set, the control unit 20 executes a temporary voltage reduction process for temporarily reducing the voltage to that voltage (step S220). On the other hand, when the voltage on the high current region side cannot be set, the control unit 20 temporarily reduces the voltage to the voltage on the low current region side corresponding to the voltage Vt ₁ in FIG. Is executed (step S225).

  After executing the temporary voltage reduction process in step S220 or step S225, the control unit 20 returns the stoichiometric ratio of the fuel cell 10 to the stoichiometric ratio before executing step S200 (step S230). In this performance recovery operation, the temporary voltage reduction process in step S220 or step S225 may be repeatedly executed at a predetermined period and for a predetermined period before the stoichiometric ratio is restored. Accordingly, the temporary voltage reduction process can be repeated a plurality of times by changing the stoichiometric ratio once, which is more efficient.

Thus, according to the fuel cell system of the tenth embodiment, as in the fuel cell system of the ninth embodiment, when the fuel cell 10 is in a high temperature state, the fuel cell system 10 While the deterioration of the catalyst performance is suppressed, further temperature increase of the fuel cell 10 is avoided. Further, in the fuel cell system according to the tenth embodiment, when the deterioration of the power generation state of the fuel cell 10 is detected by the operation in the high temperature state, the performance recovery operation with the change in the stoichiometric ratio, or the first The performance recovery operation 3 is executed, and the degradation of the power generation state is solved. In particular, in the performance recovery operation accompanied by the change in the stoichiometric ratio, by reducing the stoichiometric ratio, the voltage reduction range can be further expanded in the temporary voltage lowering process while maintaining the output power of the fuel cell 10. . Therefore, the performance of the fuel cell 10 can be recovered more efficiently.
K. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

K1. Modification 1:
In each of the above embodiments, the fuel cell system is mounted on the fuel cell vehicle. However, the fuel cell system of each embodiment does not have to be mounted on the fuel cell vehicle. The fuel cell system may be mounted on another device, system, or the like as a power supply source that supplies power according to a request from the outside.

K2. Modification 2:
In the above embodiment, the temporary voltage lowering process is executed when the fuel cell 10 is in a high temperature state or when the fuel cell 10 is in a state where the fuel cell 10 is lowered from the high temperature state to an operating temperature lower than a predetermined operating temperature. However, the temporary voltage reduction process may be executed at other timing as long as the high temperature state is detected. As described above, by executing the temporary voltage reduction process based on the change in the operating temperature of the fuel cell 10, it is possible to more effectively suppress the performance degradation of the fuel cell 10 due to being exposed to a high temperature state.

K3. Modification 3:
In the above embodiment, when the temporary voltage reduction process is executed, the secondary battery 81 acquires the predicted value E _{P of the} amount of power stored or discharged, and the predicted value E _P and the current secondary voltage Based on the state of charge of the battery 81 (charged amount and available capacity), the processing conditions of the temporary voltage reduction processing, the processing contents such as the voltage reduction means of the fuel cell 10 were changed. However, the above-described predicted value E _P does not have to be acquired, and the processing content of the temporary voltage reduction process may be changed based on the charged state of the secondary battery 81 and the operating state of the fuel cell 10.

  The “processing conditions for the temporary voltage reduction process” include the voltage value after reduction, the execution period of the temporary voltage reduction process, and the like in addition to the voltage reduction period th and the voltage reduction amount Vd. It is good as well. The “operating state of the fuel cell 10” includes the current power generation characteristics of the fuel cell 10, the current impedance / cell resistance of the fuel cell 10, the reaction gas in the fuel cell 10, in addition to the high temperature exposure time td described above. It is also possible to include factors such as pressure loss.

K4. Modification 4:
In each of the above embodiments, a map prepared in advance is used for setting the voltage drop period th and the voltage drop amount td. However, the voltage drop period th and the voltage drop amount td may be set without using a map. The voltage drop period th and the voltage drop amount td may be set using preset initial values or mathematical expressions. Further, the voltage drop period th and the voltage drop amount td may be set based on a relationship with a high temperature exposure time td prepared in advance and other operating conditions of the fuel cell 10.

K5. Modification 5:
In the above embodiment, the performance recovery operation is executed when the fuel cell 10 is in a high temperature state or when the fuel cell 10 is at a normal operation temperature after being in a high temperature state. However, the performance recovery operation may be executed when a decrease in the power generation performance of the fuel cell 10 is detected.

K6. Modification 6:
In the above embodiment, when the control unit 20 determines whether or not it is possible to compensate for the power shortage in the temporary voltage reduction process with the current SOC of the secondary battery 81, The processing conditions for the temporary voltage drop processing were corrected. However, the performance recovery operation may be forcibly terminated when it is determined in the determination process that it is difficult to execute the temporary voltage reduction process even by correction. Specifically, for example, in the temporary voltage reduction process, the predicted value E _{P of the} amount of power to be discharged or stored in the secondary battery 81, the amount of power that can be output from the secondary battery 81, or the secondary battery 81 The performance recovery operation may be forcibly terminated when the difference from the free space is larger than a predetermined threshold.

K7. Modification 7:
In the ninth embodiment, in step S26 (FIG. 27), the presence or absence of deterioration of the power generation state of the fuel cell 10 is determined by detecting the pressure loss of the anode gas. However, in step S26, the presence or absence of deterioration of the power generation state of the fuel cell 10 may be determined based on other factors. For example, the current density distribution in the fuel cell 10 may be detected, and deterioration of the power generation state in the fuel cell 10 may be detected from the current density distribution.

K8. Modification 8:
In the above embodiment, the voltage drop period th or the voltage drop amount vd is corrected as the processing condition of the temporary voltage drop process in a predetermined case. However, in the correction of the processing conditions of the temporary voltage drop process, both the voltage drop period th and the voltage drop amount vd may be corrected, or other process conditions may be corrected.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 2 ... Cathode electrode 3 ... Catalyst support particle 3c ... Catalyst 3p ... Conductive particle 4 ... Ionomer 10 ... Fuel cell 11 ... Electric power generation body 15 ... Membrane electrode assembly 20 ... Control part 30 ... Cathode gas supply part 31 ... Cathode gas piping 32 ... Air compressor 33 ... Air flow meter 34 ... Open / close valve 35 ... Humidification unit 40 ... Cathode gas discharge unit 41 ... Cathode exhaust gas piping 43 ... Pressure control valve 44 ... Pressure measurement unit 50 ... Anode gas supply unit 51 ... Anode gas piping DESCRIPTION OF SYMBOLS 52 ... Hydrogen tank 53 ... On-off valve 54 ... Regulator 55 ... Hydrogen supply apparatus 56 ... Pressure measuring part 60 ... Anode gas circulation discharge part 61 ... Anode exhaust gas pipe 62 ... Gas-liquid separation part 63 ... Anode gas circulation pipe 64 ... For hydrogen circulation Pump 65 ... Anode drain piping 66 ... Drain valve 67 ... Pressure measuring unit 70 ... Refrigerant supply unit 71 Refrigerant piping 71a ... Upstream piping 71b ... Downstream piping 71c ... Bypass piping 72 ... Radiator 73 ... Three-way valve 75 ... Refrigerant circulation pumps 76a, 76b ... Refrigerant temperature measuring unit 81 ... Secondary battery 82 ... DC / DC converter 83 ... DC / AC inverter 91 ... Cell voltage measurement unit 92 ... Current measurement unit 93 ... Impedance measurement unit 94 ... SOC detection unit 95 ... Open / close switch 96 ... Open / close switch 100, 100A to 100C ... Fuel cell system 101 ... Outside air temperature sensor 102 ... Vehicle speed sensor 110 ... Short circuit 111 ... Wiring 112 ... Variable resistance 113 ... Open / close switch 120 ... Bypass gas flow passage 121 ... Bypass piping 122 ... Open / close valve 123 ... Pressure regulating valve 130 ... Voltage application unit 131 ... Power supply device 132 ... Wiring 133 ... Open / close switch 200 ... motor DA ... drying area CL ... DC wiring OL ... oxide coating

Claims (12)

A fuel cell system,
A fuel cell as a power supply source;
A secondary battery that functions as a power supply source together with the fuel cell;
An operating state detector for detecting an operating state of the fuel cell including an operating temperature of the fuel cell;
A charge state detection unit for detecting a charge state of the secondary battery;
A control unit for controlling the output of the fuel cell;
With
The control unit temporarily decreases the voltage of the fuel cell to increase the generated water in the fuel cell after detecting a high temperature state in which the operating temperature of the fuel cell is higher than a predetermined first temperature. Perform a voltage drop process,
The said control part is a fuel cell system which changes the processing content of the said temporary voltage reduction process based on the charge condition of the said secondary battery, and the driving | running state of the said fuel cell. The fuel cell system according to claim 1, wherein
The control unit, before executing the temporary voltage drop process,
The temporary voltage according to a cumulative time during which the fuel cell is in the high temperature state, or a power generation characteristic specified by the current and voltage of the fuel cell, detected as the operating state of the fuel cell. Set the set value of the voltage drop period, which is the period to drop the voltage in the drop process,
When the temporary voltage reduction process is executed using the set value of the voltage drop period and the preset value of the voltage drop amount that is the amount of voltage drop in the preset temporary voltage drop process , Obtaining a predicted value of the amount of power that the secondary battery stores or discharges,
Based on the predicted value and the charged amount of the secondary battery acquired based on the state of charge of the secondary battery, in the processing condition of the temporary voltage reduction process, or in the temporary voltage reduction process, the A fuel cell system for changing a method for reducing the voltage of a fuel cell. The fuel cell system according to claim 2, wherein
The temporary voltage reduction process involves an increase in current according to the power generation characteristics of the fuel cell when the voltage drops,
In the case where the control unit executes the temporary voltage reduction process while supplying power according to a request from an external load,
When the temporary voltage reduction process is executed based on the predicted value of the amount of power that the secondary battery discharges when the temporary voltage reduction process is executed and the amount of power that the secondary battery can discharge In addition, the temporary voltage reduction process is executed by changing at least one of the set value of the voltage drop period or the set value of the voltage drop amount so that the amount of power discharged from the secondary battery is not insufficient. A fuel cell system. The fuel cell system according to any one of claims 1 to 3,
When the control unit detects a high temperature cancellation state in which the operating temperature of the fuel cell is lower than a second temperature lower than the first temperature after the fuel cell is in the high temperature state, A fuel cell system that performs a temporary voltage drop process. The fuel cell system according to claim 4, wherein
The control unit further executes the temporary voltage drop process,
As the operating state of the fuel cell, the current and voltage of the fuel cell are detected,
Based on the power generation characteristics of the fuel cell specified by the current and voltage of the fuel cell, the fuel cell voltage is lower than the detected voltage while maintaining the power being output by the fuel cell. A fuel cell system that performs a constant output voltage reduction process that temporarily decreases the voltage to 2 to increase the current of the fuel cell. The fuel cell system according to claim 5, wherein
The control unit controls the amount of reaction gas supplied to the fuel cell,
The said control part is a fuel cell system which performs the said output constant voltage reduction process, after reducing the stoichiometric ratio of a reactive gas. It is a fuel cell system as described in any one of Claims 2-5,
The control unit executes the temporary voltage reduction process during a high-temperature standby state in which the fuel cell is in the high-temperature state and power of the fuel cell is not supplied to an external load. in case of,
Based on the predicted value of the amount of power stored in the secondary battery when the temporary voltage reduction process is executed, and the free capacity of the secondary battery obtained from the stored amount of the secondary battery, A fuel cell system that changes a processing condition of a temporary voltage reduction process or a method of reducing the voltage of the fuel cell in the temporary voltage reduction process. The fuel cell system according to claim 7, wherein
In the case where the controller performs the temporary voltage reduction process during the high temperature standby state,
When performing the temporary voltage drop process, change the setting value of the voltage drop period or the set value of the voltage drop amount so as not to run out of available capacity of the secondary battery, A fuel cell system that executes the temporary voltage reduction process. The fuel cell system according to claim 7, further comprising:
Short-circuiting the anode and cathode of the fuel cell, comprising a short circuit that reduces the voltage of the fuel cell;
The control unit, as the temporary voltage reduction process during the high temperature standby state,
(I) a first voltage reduction process for temporarily increasing the current by temporarily reducing the voltage of the fuel cell and storing the power output from the fuel cell in the secondary battery;
(Ii) a second voltage reduction process for temporarily reducing the voltage of the fuel cell by the short circuit;
Run one of the
The said control part is a fuel cell system which selects and performs any one of the said 1st or 2nd voltage reduction process based on the said estimated value and the empty capacity of the said secondary battery. The fuel cell system according to claim 7, further comprising:
A gas supply unit capable of bypassing the anode gas to the cathode side of the fuel cell;
The control unit, as the temporary voltage reduction process during the high temperature standby state,
(I) a first voltage reduction process for temporarily increasing the current by temporarily reducing the voltage of the fuel cell and storing the power output from the fuel cell in the secondary battery;
(Iii) a third voltage reduction process for temporarily reducing the voltage of the fuel cell by bypassing the anode gas to the cathode side of the fuel cell by the gas supply unit;
Run one of the
The said control part is a fuel cell system which selects and performs any one of the said 1st or 3rd voltage reduction process based on the said estimated value and the empty capacity of the said secondary battery. The fuel cell system according to claim 7, further comprising:
The fuel cell includes an external power source capable of applying a voltage with the cathode side being positive and the anode side being negative,
The control unit, as the temporary voltage reduction process during the high temperature standby state,
(I) a first voltage reduction process for temporarily increasing the current by temporarily reducing the voltage of the fuel cell and storing the power output from the fuel cell in the secondary battery;
(Iv) In a state where supply of the reaction gas to the fuel cell is stopped, a voltage is applied to the fuel cell by the external power source to reduce the voltage of the fuel cell, and then the supply of the reaction gas is performed. A fourth voltage drop process for restarting and recovering the voltage of the fuel cell;
Run one of the
The said control part is a fuel cell system which selects and performs any one of the said 1st or 4th voltage reduction process based on the said estimated value and the empty capacity of the said secondary battery. A control method for a fuel cell system, comprising: a fuel cell that is a power supply source; and a secondary battery that functions as a power supply source together with the fuel cell,
(A) detecting an operating temperature of the fuel cell;
(B) Temporary voltage reduction processing for increasing the generated water in the fuel cell by temporarily reducing the voltage of the fuel cell after detecting a high temperature state where the operating temperature of the fuel cell is higher than a predetermined temperature. A step of executing
With
The step (b) changes the processing contents of the temporary voltage reduction process based on the state of charge of the secondary battery and the operating state of the fuel cell before executing the temporary voltage reduction process. The control method including the process to do.

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