JP2012064539A - Fuel cell system and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system which can raise the internal temperature quickly while also restricting cell degradation in a low temperature environment.SOLUTION: The fuel cell system comprises: a fuel cell; a gas passage for feeding reaction gas; a coolant passage for circulating coolant; a temperature acquisition unit for reflecting the internal temperature; a storage unit which stores beforehand therein a correspondence between the amount of electricity and the amount of reaction heat at the time when power is generated from the fuel cell while supply of reaction gas is halted in a low temperature environment; an electricity amount acquisition unit which acquires the amount of electricity at the time when power is generated from the fuel cell while supply of reaction gas is halted when the internal temperature is below a reference temperature; and an operation control unit which finds an estimate reaction heat derived by applying a correspondence to the amount of electricity acquired by the electricity amount acquisition unit, determines from the found estimate reaction heat an operating condition including a coolant circulation related condition, under which power is to be generated from the fuel cell, and generates power from the fuel cell according to the determined operating condition.

Description

  The present invention relates to a fuel cell system and a control method for the fuel cell system.

  The fuel cell is desirably operated in a predetermined temperature range from the viewpoint of power generation efficiency. A fuel cell system including such a fuel cell is provided with a cooling system for managing a temperature change of the fuel cell due to reaction heat generated by an electrochemical reaction in the fuel cell. As the cooling system, one that circulates a refrigerant (for example, cooling water) through a refrigerant flow path provided inside the fuel cell is known.

  In such a cooling system, a technique for stopping the circulation of the refrigerant to the refrigerant flow path inside the fuel cell is known in order to quickly increase the temperature of the fuel cell at the start of operation at a low temperature (for example, below freezing point). (For example, Patent Document 1).

JP 2003-36874 A JP 2006-100093 A JP 2006-100094 A

  However, in the conventional technology, the circulation of the refrigerant to the refrigerant flow path is uniformly stopped in a low temperature environment. Therefore, when the power generation of the fuel cell is continued in such a state, a temperature difference occurs in the cell surface of the fuel cell. Due to this temperature difference, for example, stress may occur in the constituent members of the cell, leading to deterioration or damage of the cell.

  An object of the present invention is to provide a fuel cell system capable of quickly raising an internal temperature while suppressing cell deterioration in a low-temperature environment.

  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;
A gas flow path for supplying and discharging reaction gas to and from the fuel cell;
A refrigerant flow path for circulating a refrigerant for cooling the fuel cell;
A temperature acquisition unit that reflects the internal temperature of the fuel cell;
A storage unit for storing in advance a correspondence relationship between the amount of electricity and the amount of reaction heat when the fuel cell is generated in a state where the supply of the reaction gas is stopped in a low temperature environment;
An electric quantity acquisition unit for acquiring an electric quantity generated when the fuel cell is caused to generate electric power in a state where supply of the reaction gas is stopped when the internal temperature reflected in the temperature acquisition unit is equal to or lower than a reference temperature; ,
The estimated amount of reaction heat derived by applying the amount of electricity acquired by the amount-of-electricity acquisition unit to the corresponding relationship is obtained, and the fuel cell including the condition relating to the circulation of the refrigerant is generated from the obtained estimated amount of reaction heat. A fuel cell system comprising: an operation control unit configured to determine an operation condition at the time and generate power according to the determined operation condition.
With such a configuration, the electric quantity acquisition unit generates power in the state where the supply of the reaction gas is stopped when the internal temperature of the fuel cell reflected in the temperature acquisition unit is equal to or lower than the reference temperature. The operation control unit obtains the amount of electricity generated when the fuel cell is caused to generate power with the reaction gas supply stopped in a low temperature environment and the amount of reaction heat. In order to determine the estimated reaction calorific value derived by applying the correspondence, and to determine the operating conditions for power generation of the fuel cell including the conditions related to the circulation of the refrigerant from the calculated estimated calorific value, the deterioration of the cell is suppressed in a low temperature environment. However, it is possible to provide a fuel cell system capable of quickly raising the internal temperature.

[Application Example 2]
A fuel cell system according to Application Example 1,
The operation controller is
When the estimated reaction heat amount is equal to or greater than a predetermined first threshold, the operation condition is determined as a first operation mode for generating power in a state where the refrigerant is circulated through the refrigerant flow path,
When the estimated amount of reaction heat is less than the first threshold value and greater than or equal to a predetermined second threshold value, the second operating condition is to generate power in a state where circulation of the refrigerant to the refrigerant flow path is stopped. Determine the operation mode,
The fuel cell system, wherein when the estimated amount of reaction heat is less than the second threshold, the operation condition is determined as a third operation mode in which power generation is not performed.
With such a configuration, when the estimated reaction heat amount is equal to or greater than a predetermined first threshold, the operation control unit generates power in a state in which the operating conditions of the fuel cell are circulated through the refrigerant flow path. If the estimated reaction heat quantity is less than the first threshold value and greater than or equal to the second threshold value determined in advance, the operation condition of the fuel cell is set to stop the circulation of the refrigerant to the refrigerant flow path. When the estimated reaction heat amount is less than the second threshold value, the fuel cell operating condition is determined as the third operating mode in which power generation is not performed. In other words, if the reaction heat quantity is estimated to such an extent that a sufficient temperature increase can be expected even if the temperature increase of the fuel cell itself is suppressed by the circulation of the refrigerant, the decrease in the power generation performance of the fuel cell due to cell deterioration or the like is suppressed. From the point of view, if the fuel cell is generated with the refrigerant circulated and the temperature rise of the fuel cell itself is suppressed by the circulation of the refrigerant, a sufficient temperature rise cannot be expected, but the refrigerant circulation is stopped to generate the fuel cell. If the amount of reaction heat that can be expected to increase sufficiently within a predetermined time is estimated, the fuel cell is generated with the refrigerant circulation stopped, giving priority to the temperature increase of the fuel cell. Can be made. As a result, it is possible to provide a fuel cell system capable of quickly raising the internal temperature while suppressing cell deterioration in a low temperature environment.

[Application Example 3]
A fuel cell system according to Application Example 2,
The operation control unit further includes:
Before starting power generation of the fuel cell in the first operation mode, the estimated reaction heat amount is compared with a reference value obtained by adding a predetermined value to the first threshold,
When the estimated amount of reaction heat is less than the reference value, a selection of an operation condition to be executed is accepted from the first operation mode and the second operation mode, and the fuel according to the accepted operation condition A fuel cell system that generates power from a battery.
With such a configuration, the operation control unit compares the estimated reaction heat amount with a reference value obtained by adding a predetermined value to the first threshold before starting the power generation of the fuel cell in the first operation mode. If the estimated reaction heat quantity is less than the reference value, the selection of the operation condition to be executed is accepted from the first operation mode and the second operation mode, and the fuel cell is caused to generate power under the accepted operation condition. Therefore, convenience can be improved.

[Application Example 4]
A fuel cell system according to application example 2 or 3,
The operation control unit further includes:
An index value for evaluating the power generation performance of the fuel cell is acquired after a lapse of a predetermined time from the start of power generation of the fuel cell in the first operation mode, and the acquired index value is the amount of electricity acquired. A fuel cell system that switches the operating condition of the fuel cell to the second operating mode when inferior to the index value acquired in advance at the time of acquisition of the amount of electricity by the unit.
With such a configuration, the operation control unit acquires an index value for evaluating the power generation performance of the fuel cell after a lapse of a predetermined time from the start of power generation of the fuel cell in the first operation mode, When the acquired index value is inferior to the index value acquired in advance at the time of acquiring the amount of electricity by the amount of electricity acquisition unit, the circulation of the refrigerant is stopped as the operating condition of the fuel cell. Therefore, the temperature of the fuel cell can be easily increased.

[Application Example 5]
The fuel cell system according to any one of Application Examples 2 to 4,
The operation control unit further includes:
After starting the power generation of the fuel cell in the second operation mode, the internal temperature is periodically acquired, and when the internal temperature becomes higher than the reference temperature, the operating condition of the fuel cell is set to the A fuel cell system for switching to the first operation mode.
With such a configuration, the operation control unit periodically acquires the internal temperature after starting the power generation of the fuel cell in the second operation mode, and when the internal temperature becomes higher than the reference temperature, the fuel cell Since the operation condition is switched to the first operation mode, it is possible to suppress a decrease in the power generation performance of the fuel cell due to cell deterioration or the like.

[Application Example 6]
The fuel cell system according to any one of Application Examples 2 to 5,
The operation control unit further includes:
In the third operation mode, the fact that the power generation of the fuel cell is impossible, and the increase value of the internal temperature necessary for switching the operation condition of the fuel cell to another operation condition, A fuel cell system that notifies at least one of them to the outside.
With such a configuration, the operation control unit is necessary to switch the fuel cell operating condition to another operating condition and that the fuel cell cannot generate power in the third operation mode. Because at least one of the internal temperature rise value and the outside is notified to the outside, the convenience can be improved.

  The present invention can be realized in various forms. For example, it is realizable with aspects, such as a fuel cell system, a control method of a fuel cell system, and a mobile object provided with them. In addition, the present invention does not necessarily have all the various features described above, and may be configured by omitting some of them.

It is explanatory drawing which shows schematic structure of the fuel cell system as one Example of this invention. It is explanatory drawing which shows the structure of the single cell in a fuel cell. It is explanatory drawing about the acquisition method of the electric quantity which arises with the residual oxygen in a fuel cell. It is explanatory drawing which shows an example of the driving control map used in driving mode determination control. It is a flowchart which shows the procedure of the operation mode determination control in a fuel cell system.

  Next, embodiments of the present invention will be described in the following order based on examples.

A. Example:
(A-1) Configuration of fuel cell system:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system 10 as an embodiment of the present invention. The fuel cell system 10 is mounted on an automobile (not shown), and is connected via an inverter 60 to a motor (not shown) for applying a propulsive force to the automobile. The fuel cell system 10 operates a fuel cell 20 that generates electric power through an electrochemical reaction between hydrogen and oxygen in order to supply electric power to the outside.

  The fuel cell 20 of the fuel cell system 10 is a polymer electrolyte fuel cell that generates electric power upon receiving a reaction gas. In the present embodiment, the reaction gas supplied to the fuel cell 20 includes a fuel gas containing hydrogen and air that is an oxidizing gas containing oxygen. The fuel gas supplied to the fuel cell 20 decreases in hydrogen concentration as the electrochemical reaction between hydrogen and oxygen proceeds, and is discharged outside the fuel cell 20 as an anode off-gas. The oxidizing gas supplied to the fuel cell 20 decreases in oxygen concentration as the electrochemical reaction between hydrogen and oxygen proceeds, and is discharged to the outside of the fuel cell 20 as a cathode offgas.

  The fuel cell 20 includes a plurality of single cells 21 that constitute a basic structure that directly extracts electric energy from fuel gas, and the plurality of single cells 21 are electrically stacked in series. Details of the configuration of the single cell 21 will be described later. Further, the fuel cell 20 is provided with a current measurement unit 217, a cell voltage measurement unit 218, and an internal temperature measurement unit 219.

  The current measurement unit 217 is connected to the DC power supply line DCL of the fuel cell 20, measures the current value output from the fuel cell 20, and transmits the measurement result to the control unit 90. The cell voltage measurement unit 218 is connected to each single cell 21 of the fuel cell 20. The cell voltage measurement unit 218 measures the potential difference between the anode electrode and the cathode electrode in each unit cell 21, that is, the voltage (cell voltage) of each unit cell 21, and transmits the measurement result to the control unit 90. The internal temperature measurement unit 219 as a temperature acquisition unit measures the internal temperature of the fuel cell 20 and transmits the measurement result to the control unit 90. The internal temperature measurement unit 219 can be configured by a thermocouple, for example.

  The fuel cell system 10 includes a hydrogen supply unit 30, a cooling unit 40, an air supply unit 50, and a control unit 90 as a configuration for operating the fuel cell 20.

  The hydrogen supply unit 30 supplies hydrogen, which is a fuel gas, to the fuel cell 20 based on an instruction from the control unit 90. In this embodiment, the hydrogen supply unit 30 is a device that supplies hydrogen from a tank that compresses and stores hydrogen, but may be a device that supplies hydrogen from a hydrogen storage alloy that stores hydrogen, for example. Alternatively, an apparatus may be used that supplies hydrogen from a reformer that reforms a hydrocarbon-based fuel such as natural gas, methanol, or gasoline to extract hydrogen.

  The hydrogen supply unit 30 includes an anode supply path 310 and an anode discharge path 320 for supplying the fuel gas to the fuel cell 20 and discharging the reaction gas from the fuel cell 20. The anode supply path 310 forms a flow path for flowing fuel gas from the hydrogen supply unit 30 to the fuel cell 20. An anode supply valve 312 is provided in the anode supply path 310. The anode supply valve 312 has a function of adjusting the amount of fuel gas supplied to the fuel cell 20 in accordance with an instruction from the control unit 90. The anode discharge path 320 forms a flow path through which the anode off gas flows from the fuel cell 20.

  The air supply unit 50 supplies air, which is an oxidizing gas, to the fuel cell 20 based on an instruction from the control unit 90. In this embodiment, the air supply unit 50 is a device that supplies air taken in from the atmosphere by a pump.

  The air supply unit 50 includes a cathode supply path 510 and a cathode discharge path 520 for supplying an oxidizing gas to the fuel cell 20 and discharging a reaction gas from the fuel cell 20. The cathode supply path 510 forms a flow path for flowing oxidizing gas from the air supply unit 50 to the fuel cell 20. A cathode supply valve 512 is provided in the cathode supply path 510. The cathode supply valve 512 has a function of adjusting the supply amount of the oxidizing gas supplied to the fuel cell 20 in accordance with an instruction from the control unit 90. The cathode discharge channel 520 forms a channel through which the cathode off gas flows from the fuel cell 20. Note that the anode supply path 310, the anode discharge path 320, the cathode supply path 510, and the cathode discharge path 520 are collectively referred to simply as “gas flow path”.

  The cooling unit 40 cools the fuel cell 20 by dissipating the heat of the cooling water into the atmosphere while circulating the cooling water (antifreeze) as a refrigerant between the inside of the fuel cell 20.

  The cooling unit 40 includes a cooling water forward path 410 and a cooling water return path 420 for circulating the cooling water. The cooling water forward path 410 forms a flow path for flowing cooling water from the cooling unit 40 to the fuel cell 20. A forward valve 412 is provided in the cooling water forward path 410. The forward valve 412 has a function of adjusting the amount of cooling water circulated to the fuel cell 20 in accordance with an instruction from the control unit 90. The cooling water return path 420 forms a flow path for flowing cooling water from the fuel cell 20 to the cooling unit 40. A return valve 422 is provided in the cooling water return path 420. It has a function of adjusting the amount of cooling water circulated to the fuel cell 20 in accordance with instructions from the return valve 422 and the control unit 90. The cooling water forward path 410 and the cooling water return path 420 are collectively referred to simply as “refrigerant flow path”.

  The control unit 90 has a function of controlling each unit of the fuel cell system 10. The control unit 90 includes an operation control unit 910, a storage unit 920, and an interface 930. The operation control unit 910 performs control related to the operation of the fuel cell 20. The storage unit 920 stores various programs and data. The interface 930 electrically connects each part of the fuel cell system 10.

  The operation control unit 910 performs operation mode determination control (details will be described later) executed when power generation by the fuel cell 20 is started. The operation control unit 910 further includes a gas control unit 912, a refrigerant control unit 914, and an electric quantity acquisition unit 916. In the present embodiment, the functions of the operation control unit and each of the units included in the operation control unit are based on a central processing unit (CPU) of the operation control unit 910 based on a control program 922 stored in advance in the storage unit 920. ) Is implemented. Note that at least some of the functions of the operation control unit 910 may be realized by an electronic circuit of the operation control unit 910 operating based on its physical circuit configuration.

  The gas control unit 912 starts / stops supply of hydrogen to the anode electrode and supply of air to the cathode electrode in order to start / stop power generation by the fuel cell 20. The gas control unit 912 outputs control signals to the hydrogen supply unit 30 and the air supply unit 50 via the interface 930 in order to start supply of hydrogen and air to the fuel cell 20. The hydrogen supply unit 30 that has received the control signal opens the anode supply valve 312. When the anode supply valve 312 is opened, the hydrogen delivered from the hydrogen supply unit 30 is supplied to the anode electrode of the fuel cell 20 via the anode supply path 310. Similarly, the air supply unit 50 that has received the control signal opens the cathode supply valve 512. By opening the cathode supply valve 512, the air sent from the air supply unit 50 is supplied to the cathode electrode of the fuel cell 20 via the cathode supply path 510.

  The gas control unit 912 outputs control signals to the hydrogen supply unit 30 and the air supply unit 50 via the interface 930 in order to stop the supply of hydrogen and air to the fuel cell 20. The hydrogen supply unit 30 that has received the control signal closes the anode supply valve 312. Thereby, the supply of hydrogen to the anode electrode is stopped. Similarly, the air supply unit 50 that has received the control signal closes the cathode supply valve 512. Thereby, the supply of air to the cathode electrode is stopped.

  The refrigerant control unit 914 starts / stops the circulation of the cooling water to the fuel cell 20. The refrigerant control unit 914 outputs a control signal to the cooling unit 40 via the interface 930 in order to start circulation of the cooling water to the fuel cell 20. The cooling unit 40 that has received the control signal circulates the cooling water after opening the forward valve 412 and the return valve 422. Further, the refrigerant control unit 914 outputs a control signal to the cooling unit 40 via the interface 930 in order to stop the circulation of the cooling water to the fuel cell 20. The cooling unit 40 that has received the control signal closes the forward valve 412 and the return valve 422 and then stops the circulation of the cooling water.

  The electric quantity acquisition unit 916 has a function of acquiring an electric quantity generated in a state where supply of the reaction gas to the fuel cell 20 is stopped. Details will be described later. The storage unit 920 includes a control program 922 and an operation control map 924. Details of the operation control map 924 will be described later. The interface 930 electrically connects the operation control unit 910, the storage unit 920, and each unit of the fuel cell system 10.

(A-2) Configuration of fuel cell:
FIG. 2 is an explanatory diagram showing the configuration of the single cell 21 in the fuel cell 20. The unit cell 21 of the fuel cell 20 includes a membrane electrode assembly (hereinafter also referred to as “MEA”) 24, an anode separator 23, and a cathode separator 25. In the single cell 21, the MEA 24 is sandwiched between the anode separator 23 and the cathode separator 25.

  The MEA 24 of the single cell 21 includes an anode diffusion layer 241, an anode catalyst layer 242, an electrolyte membrane 244, a cathode catalyst layer 245, and a cathode diffusion layer 246, and these layers are integrally laminated in this order. Has been. The anode diffusion layer 241 and the anode catalyst layer 242 are stacked on the anode side surface of the electrolyte membrane 244 to constitute the anode electrode 243. The cathode diffusion layer 246 and the cathode catalyst layer 245 are stacked on the cathode side surface of the electrolyte membrane 244 to constitute the cathode electrode 247. Therefore, the electrolyte membrane 244 in the MEA 24 is in a state of being sandwiched between the anode electrode 243 and the cathode electrode 247. The anode electrode 243 and the cathode electrode 247 are collectively referred to simply as “electrodes”.

  The electrolyte membrane 244 of the MEA 24 is formed of a proton conductor having proton conductivity. In this embodiment, the electrolyte membrane 244 is a perfluorosulfonic acid ion exchange membrane using an ionomer resin which is one of proton conductors.

  The anode catalyst layer 242 and the cathode catalyst layer 245 of the MEA 24 are made of a material having gas permeability, conductivity, and water repellency in addition to a catalytic function for promoting an electrochemical reaction between hydrogen and oxygen performed through the electrolyte membrane 244. Is formed. In this embodiment, the anode catalyst layer 242 and the cathode catalyst layer 245 are formed of a material obtained by mixing an ionomer resin, which is a proton conductor, on a carbon support carrying a platinum-based catalyst containing platinum.

  The anode diffusion layer 241 and the cathode diffusion layer 246 of the MEA 24 are formed of a material having gas permeability, conductivity, and water repellency. The anode diffusion layer 241 diffuses fuel gas into the anode catalyst layer 242 and the cathode diffusion layer 246 diffuses oxidizing gas into the cathode catalyst layer 245. In this embodiment, the anode diffusion layer 241 and the cathode diffusion layer 246 are impregnated with a water-repellent water-repellent resin (for example, polytetrafluoroethylene (PTFE)) in carbon cloth or carbon paper, which is a carbon porous body. It is made of the material made.

  The anode separator 23 of the single cell 21 forms an anode flow path 232 for flowing fuel gas on the anode side surface of the MEA 24, and the cathode separator 25 of the single cell 21 is a cathode flow for flowing oxidizing gas to the cathode side surface of the MEA 24. A path 252 is formed. The anode separator 23 and the cathode separator 25 are made of a material (for example, stainless steel, carbon resin, conductive ceramic) having sufficient strength and gas impermeability for flowing fuel gas and oxidizing gas. .

(A-3) Method for measuring the amount of electricity generated by residual oxygen:
FIG. 3 is an explanatory diagram of a method for acquiring the amount of electricity generated by residual oxygen in the fuel cell. When the fuel cell is started under a low temperature condition (for example, 0 ° C. or lower), the liquid water remaining in the fuel cell and the generated water generated by the power generation are transferred onto the electrode (FIG. 2: anode catalyst layer 242, The cathode catalyst layer 245), the gas flow path (FIG. 2: anode diffusion layer 241 and cathode diffusion layer 246), and the electrolyte membrane (FIG. 2: electrolyte membrane 244) may be frozen. When liquid water freezes on the electrode or in the gas flow path, the gas flow in the fuel cell is hindered, and the power generation of the fuel cell is suppressed. In addition, when liquid water freezes in the electrolyte membrane, proton movement in the electrolyte membrane is suppressed, and power generation of the fuel cell is suppressed. Therefore, if the fuel cell is generated in a state where the supply of the reaction gas to the fuel cell is stopped and the amount of electricity generated at that time is acquired, the power generation performance of the fuel cell is reduced due to freezing of the liquid water as described above. You can know the degree.

In the present embodiment, specifically, the amount of electricity generated when the fuel cell is caused to generate power in a state where the supply of the reaction gas is stopped is acquired by the following procedure.
a) First, the electric quantity acquisition unit 916 (FIG. 1) cooperates with the gas control unit 912 to instruct the hydrogen supply unit 30 and the air supply unit 50 to start sending the reaction gas (hydrogen, air). Thereby, the reaction gas is filled in the fuel cell 20.
b) After a predetermined time has elapsed, the electric quantity acquisition unit 916 cooperates with the gas control unit 912 to instruct the air supply unit 50 to stop sending air.
c) After stopping the air supply, the electric quantity acquisition unit 916 discharges the single cell 21 by applying the voltage to the single cell 21 while sweeping it at high speed, and acquires the current measured by the current measurement unit 217. To do. FIG. 3 shows a current behavior measured when a voltage is swept at 200 mV / second in a range from 0.05 V to 1 V with respect to a single cell 21 according to the procedure c. In FIG. 3, the voltage (V) applied on the vertical axis and the current density (mA / cm ² ) of the measured current are shown on the horizontal axis, respectively.
d) The electric quantity acquisition unit 916 obtains the integrated value of the current measured by the procedure c (that is, the area of the portion indicated by hatching in FIG. 3) of the air as the reaction gas for a certain single cell 21. The amount of electricity generated in a state where supply is stopped (in other words, the amount of electricity generated by residual oxygen) is obtained.
e) The electric quantity acquisition unit 916 executes steps c and d for all the single cells 21. Then, the amount of electricity obtained in step d for all the single cells 21 is integrated, and the total value is obtained as the amount of electricity (C) generated by the residual oxygen in the fuel cell 20.

(A-4) Configuration of operation control map:
FIG. 4 is an explanatory diagram showing an example of an operation control map 924 used in the operation mode determination control. The storage unit 920 (FIG. 1) of the fuel cell system 10 stores an operation control map as illustrated in advance. In the operation control map 924, a plurality of fuel cell samples are prepared, an experiment is performed on the prepared plurality of fuel cell samples, and the amount of electricity (C) generated by the residual oxygen of the fuel cell is plotted on the horizontal axis. The amount of generated water (mg / cm ² ) generated by the power generation of the fuel cell was plotted, and an approximate curve AP was obtained.

  The value of the horizontal axis (the amount of electricity generated by residual oxygen) is determined by causing a fuel cell sample to generate power according to the procedure described in (A-3) in a low-temperature environment (−10 ° C. in this example). It is obtained by determining the amount of electricity (C) generated by residual oxygen. The value of the vertical axis (the amount of produced water) was obtained by generating a fuel cell sample for a predetermined time in a low temperature environment (−10 ° C. in this example) while continuing to supply the reaction gas. Obtained by measuring the amount of product water.

  It can be seen from the operation control map 924 in FIG. 4 that the amount of water generated in the fuel cell in a low temperature environment increases as the amount of electricity generated by the residual oxygen in the fuel cell increases. In the fuel cell, an electromotive force is obtained by an electrochemical reaction between hydrogen and oxygen at each electrode, and when such an electrochemical reaction proceeds, produced water is generated on the cathode side. It can be said that the amount of power generation in the fuel cell is proportional. In addition, in a fuel cell, the greater the amount of power generated, the greater the amount of reaction heat (heat generated by the electrochemical reaction between hydrogen and oxygen). That is, the amount of water produced in the fuel cell and the amount of reaction heat in the fuel cell are proportional. I understand that For this reason, in the operation control map 924 in the present embodiment, the amount of water produced by the fuel cell is used as an index for knowing the amount of reaction heat of the fuel cell. That is, the operation control map 924 includes an amount of electricity generated when a plurality of fuel cells are generated in a low temperature environment, and a reaction heat amount estimated to be generated when a plurality of fuel cells are generated in a low temperature environment. The correspondence relationship is shown.

  From the above, it can be said that the operation control map 924 in FIG. 4 shows that the amount of reaction heat of the fuel cell in a low temperature environment increases as the amount of electricity generated by the residual oxygen of the fuel cell increases. It is estimated that the reaction heat amount of the fuel cell when generating power for a predetermined time in a low temperature environment is high, that is, if the power generation is performed for a certain time even in a low temperature environment, the temperature of the fuel cell itself will rise to some extent. It shows what you can do. If the temperature of the fuel cell itself becomes high, the liquid water frozen inside the fuel cell can be thawed, so that the reduction in power generation performance of the fuel cell due to the freezing of liquid water as described above can be eliminated. .

  Further, the rise in the temperature of the fuel cell itself is related to whether or not the cooling water is circulated. Specifically, when the fuel cell is generated with the cooling water being circulated, the cooling water circulates while taking heat inside the fuel cell, so that the temperature rise of the fuel cell itself is suppressed. On the other hand, when the fuel cell is generated with the cooling water circulation stopped, the temperature rise of the fuel cell itself is not suppressed, but the temperature rises quickly at the portion where the fuel cell is likely to generate electricity, and it is difficult to generate electricity. The temperature rise is slow at the part (part with a lot of liquid water, etc.). As a result, a temperature difference occurs in the cell plane, and stress is generated in the constituent members of the cell due to the temperature difference, which may cause deterioration or damage of the cell. Further, the temperature rises sharply in the cell surface where power generation is likely to occur, and part of the cell surface may dry up. Therefore, by repeating these, the power generation performance of the fuel cell may be reduced.

From the above, even if the temperature rise of the fuel cell itself can be estimated even if the temperature rise of the fuel cell itself is suppressed by the circulation of the cooling water, the viewpoint of suppressing the power generation performance reduction of the fuel cell due to cell deterioration or the like Therefore, it is preferable to generate power in the fuel cell with the cooling water circulated. For this reason, in the operation mode determination control described later, the operation condition of the fuel cell when the amount of generated water in the low temperature environment is equal to or greater than the threshold value S1 (20 mg / cm ² ) is that the fuel cell is operated with the cooling water circulated. The first possible operation mode is determined. The “operating condition” in the present embodiment means whether or not the reactant gas is supplied and whether or not the refrigerant is circulated when generating power in the fuel cell.

In addition, if the increase in the temperature of the fuel cell itself is suppressed by circulating the cooling water, a sufficient increase in the temperature of the fuel cell cannot be expected. If it can be estimated that the temperature of the fuel cell will increase, it is preferable to prioritize the temperature increase of the fuel cell to eliminate the decrease in power generation performance due to freezing of liquid water inside the fuel cell. The predetermined time means a short time that does not cause a problem of reduction in power generation performance of the fuel cell due to cell deterioration or the like, and can be arbitrarily determined. Therefore, in the operation mode determination control will be described later, below water quantity threshold S1 in the low temperature environment (20mg / cm ^2), the operating conditions of the fuel cell when the threshold value S2 (8mg / cm ²⁾ or more, the cooling water Is determined as a second operation mode in which the fuel cell can be operated in a state where the circulation of the fuel cell is stopped.

Further, in the operation mode determination control described later, the operation condition of the fuel cell when the amount of generated water in the low temperature environment is less than the threshold value S2 (8 mg / cm ² ) is determined as the third operation mode in which power generation is not performed. This is because the fuel cell is caused to generate power for a long time in a state where the circulation of the cooling water is stopped, and there is a possibility that the power generation performance of the fuel cell is lowered due to deterioration of the cell or the like. The threshold values S1 and S2 are examples, and arbitrary values can be adopted depending on the design. Since the amount of water produced in the fuel cell and the amount of reaction heat in the fuel cell are proportional, the threshold value S1 in FIG. 4 indirectly indicates the “first threshold value” in the claims, and the threshold value S2 is in the claims. The “second threshold value” in FIG.

(A-5) Operation of fuel cell system:
FIG. 5 is a flowchart showing a procedure of operation mode determination control in the fuel cell system 10. The operation mode determination control is a process executed by the operation control unit 910 (FIG. 1) when power generation by the fuel cell 20 is started (for example, when the control unit 90 receives an operation start request for the fuel cell 20). is there.

  When the operation mode determination control is started, the electric quantity acquisition unit 916 cooperates with the gas control unit 912 (FIG. 1) to send the reaction gas to the fuel cell 20 (step S100). The details are the same as (A-3) Procedure a. Next, the operation control unit 910 acquires the internal temperature of the fuel cell 20 measured by the internal temperature measurement unit 219, and determines whether or not this internal temperature is higher than 0 ° C. (step S102). When the internal temperature of the fuel cell 20 is higher than 0 ° C. (step S102: YES), the operation control unit 910 determines that the normal operation is possible and starts the power generation of the fuel cell 20 by a normal method. Thereafter, the process is terminated (step S116). Specifically, the operation control unit 910 requests the gas control unit 912 to start sending reaction gases (hydrogen, air) from the hydrogen supply unit 30 and the air supply unit 50. Further, the operation control unit 910 requests the refrigerant control unit 914 to start the refrigerant circulation by the cooling unit 40.

  On the other hand, when the internal temperature of the fuel cell 20 is equal to or lower than the reference temperature (0 ° C. in the present embodiment) (step S102: NO), the electric quantity acquisition unit 916 stops sending air to the fuel cell (step S104). ). Details are the same as (A-3) step b. After the air supply is stopped, the electricity quantity acquisition unit 916 obtains the electricity quantity caused by the residual oxygen in the fuel cell 20 (step S106). The details are the same as (A-3) procedures c to e.

  Next, the operation control unit 910 determines whether or not the fuel cell can be operated in a state where the cooling water is circulated (step S108). Specifically, the operation control unit 910 refers to the operation control map 924 stored in the storage unit 920, the approximate curve AP (FIG. 4) of the operation control map 924, and the fuel cell 20 obtained in step S106. The estimated amount of water produced by the fuel cell 20 estimated from the amount of electricity (that is, the value on the vertical axis) is obtained. Since the amount of water generated in the fuel cell and the amount of reaction heat in the fuel cell are proportional, the estimated amount of generated water obtained here indirectly indicates the “estimated amount of heat of reaction” in the claims.

  When the estimated amount of generated water is less than the threshold value S1 (FIG. 4), the operation control unit 910 determines that the operation of the fuel cell in a state where the cooling water is circulated is impossible, and the process proceeds to step S110. (Step S108: NO). On the other hand, when the estimated amount of generated water is equal to or greater than the threshold value S1, the operation control unit 910 determines that the fuel cell can be operated in a state where the cooling water is circulated, and causes the process to transition to step S120 (step S108). : YES).

  In step S110, the operation control unit 910 further determines whether or not the fuel cell can be operated if the circulation of the cooling water is stopped. Specifically, the operation control unit 910 determines whether or not the estimated generated water amount obtained in step S108 is equal to or greater than a threshold value S2 (FIG. 4). When the estimated amount of generated water is equal to or greater than the threshold value S2, the operation control unit 910 determines that the fuel cell can be operated if the circulation of the cooling water is stopped, and the process proceeds to step S112 (step S112). S110: YES).

  In step S112, the operation control unit 910 starts power generation of the fuel cell 20 in a state where the circulation of the cooling water is stopped. Specifically, the operation control unit 910 requests the gas control unit 912 to start sending reaction gases (hydrogen, air) from the hydrogen supply unit 30 and the air supply unit 50. Thereafter, the operation control unit 910 periodically acquires the internal temperature of the fuel cell 20 measured by the internal temperature measurement unit 219 and continues monitoring. When the internal temperature of the fuel cell 20 becomes higher than 0 ° C., the operation control unit 910 requests the refrigerant control unit 914 to start the circulation of the refrigerant by the cooling unit 40, and then ends the processing (step) S114).

  On the other hand, when the estimated amount of generated water is less than the threshold value S2 in step S110, the operation control unit 910 determines that the fuel cell cannot be operated even when the cooling water circulation is stopped, and the operation is performed. The user is notified of the impossibility and how many times the internal temperature of the fuel cell will become possible to operate the fuel cell (step S118). Specifically, the operation control unit transmits a request for guidance display to the control unit 90. The control unit 90 that has received the request notifies the user by displaying the requested content on a display unit such as a monitor (not shown).

  In this way, the user can know the cause of why the fuel cell system cannot be activated, and thus it is possible to suppress erroneous determination of failure by the user. Furthermore, since the user can know how long to wait before the fuel cell system can be activated, convenience is improved. Note that either one of the notifications in step S118 may be omitted. Moreover, it is good also as acquiring outside temperature, acquiring the time estimated to be required before starting using external temperature and internal temperature, and guiding this time.

  In step S120, the operation control unit 910 determines whether or not the operation start time of the fuel cell 20 needs to be shortened. Specifically, when the estimated amount of generated water obtained in step S108 is compared with the threshold value S1 (FIG. 4), it can be determined that the estimated amount of generated water is sufficiently larger than the threshold value S1 (for example, the specified amount of generated water ≧ the threshold value S1). ) + The predetermined value), the operation control unit 910 determines that it is not necessary to shorten the starting time, and causes the process to transition to step S122 (step S120: NO).

  On the other hand, when the estimated generated water amount obtained in step S108 is compared with the threshold value S1 (FIG. 4) and it cannot be determined that the estimated generated water amount is sufficiently larger than the threshold value S1 (for example, the designated generated water amount <the value of the threshold value S1 + The operation control unit 910 once determines that it is necessary to shorten the operation start time. This is because when the estimated amount of generated water of the fuel cell 20 is in the vicinity of the threshold S1, the temperature rise when the fuel cell is generated is small, so the time until the start of the operation of the fuel cell 20 (in other words, the fuel This is because much time is required until the temperature of the battery 20 rises.

  Therefore, once it is determined that the operation start time needs to be shortened, the operation control unit 910 starts the power generation of the fuel cell in a state where the circulation of the cooling water is stopped (that is, shortens the operation start time). Or) whether to start power generation of the fuel cell in a state where the cooling water is circulated (that is, whether to prioritize suppression of power generation performance reduction of the fuel cell over reduction of the operation start time) Display the screen to the user. Specifically, the operation control unit 910 transmits a request for displaying a selection screen to the control unit 90 as in step S118. By doing so, the user can select between shortening the operation start time and suppressing the decrease in the power generation performance of the fuel cell, so that convenience can be improved.

  When shortening the operation start time is selected (step S120: YES), the operation control unit 910 starts power generation of the fuel cell 20 in a state where the circulation of the cooling water is stopped (step S128). Details are the same as in step S112. Thereafter, the operation control unit 910 causes the process to transition to step S114.

  On the other hand, when priority is given to suppressing the reduction in power generation performance of the fuel cell over shortening of the operation start time (step S120: NO), the operation control unit 910 performs the fuel cell circulation with cooling water. 20 power generation is started (step S122). Details are the same as in step S116.

  After starting the power generation of the fuel cell 20, the operation control unit 910 determines whether or not the power generation performance of the fuel cell 20 is insufficient (step S124). Specifically, the operation control unit 910 waits for a predetermined time (for example, the time when the temperature inside the fuel cell 20 is expected to rise sufficiently from the amount of electricity obtained in step S106) after the start of power generation by the fuel cell 20. After that, the value of the output current measured by the current measuring unit 217 is acquired. Then, the operation control unit 910 compares the acquired output current value with the current value measured in step S106.

  When the acquired output current value is smaller, the operation control unit 910 determines that the power generation performance is insufficient as compared with the estimation in step S108 (step S124: YES). This is due to the fact that the liquid water remaining on the anode catalyst layer 242 (FIG. 2) or in the anode diffusion layer 241 (FIG. 2) is still frozen. In steps S106 and S108, since the value of the output current is measured in a state where the supply of air is stopped (that is, in a state where oxygen is depleted), it is determined in step S124 that there is a problem on the anode side. can do.

  If it is determined that the power generation performance is insufficient (step S124: YES), the operation control unit 910 continues the power generation of the fuel cell 20 after stopping the circulation of the cooling water (step S126). Specifically, the operation control unit 910 requests the refrigerant control unit 914 to stop the circulation of the refrigerant by the cooling unit 40, and then ends the process (step S114). In this case, since the circulation of the cooling water is stopped, the temperature of the fuel cell 20 is likely to rise, so that it is possible to promote the melting of the liquid water frozen inside the fuel cell 20.

  On the other hand, when it is determined that the power generation performance is not sufficient (step S124: NO), the operation control unit 910 continues the power generation of the fuel cell 20 in a state where the cooling water is circulated (step S130).

  As described above, according to the embodiment, the electric quantity acquisition unit 916 performs the case where the internal temperature of the fuel cell 20 reflected in the temperature acquisition unit (internal temperature measurement unit 219) is equal to or lower than the reference temperature (0 ° C.). The amount of electricity generated when the fuel cell 20 is generated with the supply of the reaction gas being stopped is acquired. Then, the operation control unit 910 uses the operation control map 924 (indirectly calculates the amount of electricity and the amount of reaction heat generated when the fuel cell is generated in a state where the supply of the reaction gas is stopped in a low temperature environment). The estimated reaction heat quantity derived by applying to the estimated relationship water quantity shown in Fig. 5) is calculated, and the fuel cell 20 including the conditions relating to the circulation of the refrigerant (cooling water) is generated from the obtained estimated reaction heat quantity. Determine operating conditions.

  Specifically, the operation control unit 910 circulates the cooling water as the operation condition of the fuel cell 20 when the estimated reaction heat amount (estimated generated water amount) is equal to or greater than a predetermined first threshold value (threshold value S1). When the first operation mode for generating power in a state is determined, and the estimated reaction heat amount (estimated generated water amount) is less than the first threshold value (threshold value S1) and is equal to or greater than a predetermined second threshold value (threshold value S2) When the operation condition of the fuel cell 20 is determined as the second operation mode in which power generation is performed with the circulation of the cooling water stopped, and the estimated reaction heat amount (estimated generated water amount) is less than the second threshold value (threshold value S2), The operation condition of the fuel cell 20 is determined as the third operation mode in which power generation is not performed.

  In other words, if the reaction heat quantity is estimated to such an extent that a sufficient temperature rise can be expected even if the temperature rise of the fuel cell 20 itself is suppressed by circulation of the cooling water, the fuel due to cell deterioration or the like can be obtained. If the fuel cell 20 is generated in a state where the cooling water is circulated from the viewpoint of suppressing a decrease in the power generation performance of the battery 20, and the temperature rise of the fuel cell 20 itself is suppressed by the circulation of the cooling water, a sufficient temperature rise cannot be expected. However, when the fuel cell 20 is generated by stopping the circulation of the cooling water, if the amount of reaction heat that can be expected to increase sufficiently within a predetermined time is estimated, priority is given to the temperature increase of the fuel cell 20. Thus, the fuel cell 20 can be generated with the cooling water circulation stopped. As a result, it is possible to provide a fuel cell system capable of quickly raising the internal temperature while suppressing cell deterioration in a low temperature environment.

  Further, the operation control unit 910 performs an index value (measured by the current measurement unit 217) for evaluating the power generation performance of the fuel cell 20 after a predetermined time has elapsed since the start of power generation of the fuel cell 20 in the first operation mode. Output current value), and the obtained index value is compared with the index value (the current value measured in step S106) acquired in advance when the amount of electricity is acquired by the amount-of-electricity acquisition unit. If it is inferior, the operating condition of the fuel cell 20 is switched to the second operation mode in which the circulation of the cooling water is stopped, so that the temperature of the fuel cell 20 can be easily increased.

  Furthermore, after starting the power generation of the fuel cell 20 in the second operation mode, the operation control unit 910 periodically acquires the internal temperature of the fuel cell 20, and the internal temperature becomes higher than the reference temperature (0 ° C.). In this case, since the operating condition of the fuel cell 20 is switched to the first operation mode, it is possible to suppress a decrease in the power generation performance of the fuel cell 20 due to cell deterioration or the like.

B. Variations:
In addition, this invention is not restricted to said Example and embodiment, A various structure can be taken in the range which does not deviate from the summary. For example, a function realized by software may be realized by hardware. In addition, the following modifications are possible.

B1. Modification 1:
In the said Example, it illustrated about the structure of the fuel cell system. However, these configurations can be arbitrarily determined without departing from the scope of the present invention.

  For example, the cell voltage sensor (FIG. 1) is a sensor that detects each cell voltage of all the single cells in the fuel cell, but other modes may be employed. For example, the cell voltages of some representative single cells among the plurality of single cells constituting the fuel cell may be detected.

  For example, as a means for measuring the internal temperature of the fuel cell, the internal temperature is measured based on a detection signal from a temperature sensor (internal temperature sensor: FIG. 1) directly provided in the fuel cell. Other aspects may be employed. For example, after providing a temperature sensor in the cooling water return path, the temperature measurement unit may measure the cell temperature based on a detection signal output from the temperature sensor in the cooling water return path.

B2. Modification 2:
In the above embodiment (A-3) method for measuring the amount of electricity generated by residual oxygen, one mode for measuring the amount of electricity generated by residual oxygen in the fuel cell has been illustrated. However, this quantity of electricity can be measured by various methods.

  For example, after acquiring the amount of electricity of each single cell, the total value obtained by integrating the amounts of electricity of all the single cells was obtained and used as the amount of electricity of the fuel cell. It can also be obtained as the amount of electricity of the fuel cell.

  For example, in the procedure b, the electric quantity acquisition unit is instructed to stop sending air, but may be instructed to stop sending hydrogen in addition to air.

B3. Modification 3:
In the above embodiment (A-5) operation of the fuel cell system (FIG. 5), one mode of the operation mode determination control is exemplified. The operation mode determination control can be variously modified.

  For example, instead of determining the operation condition by obtaining the estimated amount of generated water as the whole fuel cell estimated from the approximate curve AP (FIG. 4) of the operation control map and the amount of electricity of the fuel cell, The operation condition is determined by obtaining the estimated amount of generated water of the single cell estimated from the approximate curve AP (FIG. 4) and the amount of electricity of the single cell, executing this for all the cells, and determining the distribution. May be.

  For example, although the cooling water is stopped as a means for promoting the temperature rise of the fuel cell itself, conditions relating to the circulation of the refrigerant that can be adopted to promote the temperature rise of the fuel cell can be arbitrarily determined. . Specifically, instead of the presence or absence of circulation of the cooling water, the flow rate of the circulating cooling water may be adjusted. If it does in this way, the power generation performance fall of a fuel cell by degradation of a cell, etc. can be controlled, reducing the temperature rise suppression effect of the fuel cell by circulation of cooling water.

  For example, the reference temperature in steps S102 and S114 is 0 ° C. (that is, below freezing point). However, this reference temperature can be set arbitrarily.

  For example, in step S118, one mode of processing in the third operation mode (that is, notifying that the fuel cell cannot be operated without operating the fuel cell) is illustrated. However, in the third operation mode, other processing modes can be employed. For example, the fuel cell may be operated while circulating cooling water that has been heated using a heater or the like.

  For example, in step S124, the index value for evaluating the power generation performance of the fuel cell used for determining the lack of hydrogen is the value of the output current measured by the current measuring unit. However, other values (for example, the internal temperature of the fuel cell and the elapsed time from the start of power generation of the fuel cell) can be adopted as the index value.

B4. Modification 4:
In the above embodiment, the fuel cell system is a system mounted on a vehicle that travels using the power generated by the fuel cell, but other modes can also be adopted. For example, the fuel cell system may be applied to a system installed as a power source for a house or facility, or may be applied to a system mounted as a power source on an electromechanical device that operates by electricity.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 20 ... Fuel cell 21 ... Single cell 23 ... Anode separator 25 ... Cathode separator 30 ... Hydrogen supply part 40 ... Cooling part 50 ... Air supply part 60 ... Inverter 90 ... Control part 217 ... Current measurement part 218 ... Cell Voltage measurement unit 219 ... Internal temperature measurement unit 232 ... Anode flow path 241 ... Anode diffusion layer 242 ... Anode catalyst layer 243 ... Anode electrode 244 ... Electrolyte membrane 245 ... Cathode catalyst layer 246 ... Cathode diffusion layer 247 ... Cathode electrode 252 ... Cathode flow Path 310 ... Anode supply path 312 ... Anode supply valve 320 ... Anode discharge path 410 ... Cooling water forward path 412 ... Outbound valve 420 ... Cooling water return path 422 ... Return path valve 510 ... Cathode supply path 512 ... Cathode supply valve 520 ... Cathode discharge path 910 ... Operation control unit 12 ... gas control unit 914 ... refrigerant controller 916 ... electric quantity acquiring unit 920 ... storage unit 922 ... control program 924 ... operation control map 930 ... interface

Claims (7)

A fuel cell system,
A fuel cell;
A gas flow path for supplying and discharging reaction gas to and from the fuel cell;
A refrigerant flow path for circulating a refrigerant for cooling the fuel cell;
A temperature acquisition unit that reflects the internal temperature of the fuel cell;
A storage unit for storing in advance a correspondence relationship between the amount of electricity and the amount of reaction heat when the fuel cell is generated in a state where the supply of the reaction gas is stopped in a low temperature environment;
An electric quantity acquisition unit for acquiring an electric quantity generated when the fuel cell is caused to generate electric power in a state where supply of the reaction gas is stopped when the internal temperature reflected in the temperature acquisition unit is equal to or lower than a reference temperature; ,
The estimated amount of reaction heat derived by applying the amount of electricity acquired by the amount-of-electricity acquisition unit to the corresponding relationship is obtained, and the fuel cell including the condition relating to the circulation of the refrigerant is generated from the obtained estimated amount of reaction heat. A fuel cell system comprising: an operation control unit configured to determine an operation condition at the time and generate power according to the determined operation condition. The fuel cell system according to claim 1, wherein
The operation controller is
When the estimated reaction heat amount is equal to or greater than a predetermined first threshold, the operation condition is determined as a first operation mode for generating power in a state where the refrigerant is circulated through the refrigerant flow path,
When the estimated amount of reaction heat is less than the first threshold value and greater than or equal to a predetermined second threshold value, the second operating condition is to generate power in a state where circulation of the refrigerant to the refrigerant flow path is stopped. Determine the operation mode,
The fuel cell system, wherein when the estimated amount of reaction heat is less than the second threshold, the operation condition is determined as a third operation mode in which power generation is not performed. The fuel cell system according to claim 2, wherein
The operation control unit further includes:
Before starting power generation of the fuel cell in the first operation mode, the estimated reaction heat amount is compared with a reference value obtained by adding a predetermined value to the first threshold,
When the estimated amount of reaction heat is less than the reference value, a selection of an operation condition to be executed is accepted from the first operation mode and the second operation mode, and the fuel according to the accepted operation condition A fuel cell system that generates power from a battery. The fuel cell system according to claim 2 or 3, wherein
The operation control unit further includes:
An index value for evaluating the power generation performance of the fuel cell is acquired after a lapse of a predetermined time from the start of power generation of the fuel cell in the first operation mode, and the acquired index value is the amount of electricity acquired. A fuel cell system that switches the operating condition of the fuel cell to the second operating mode when inferior to the index value acquired in advance at the time of acquisition of the amount of electricity by the unit. A fuel cell system according to any one of claims 2 to 4,
The operation control unit further includes:
After starting the power generation of the fuel cell in the second operation mode, the internal temperature is periodically acquired, and when the internal temperature becomes higher than the reference temperature, the operating condition of the fuel cell is set to the A fuel cell system for switching to the first operation mode. A fuel cell system according to any one of claims 2 to 5,
The operation control unit further includes:
In the third operation mode, the fact that the power generation of the fuel cell is impossible, and the increase value of the internal temperature necessary for switching the operation condition of the fuel cell to another operation condition, A fuel cell system that notifies at least one of them to the outside. A control method of a fuel cell system including a fuel cell,
(A) reflecting the internal temperature of the fuel cell;
(B) When the internal temperature reflected by the step (a) is equal to or lower than a reference temperature, the amount of electricity generated when the fuel cell is caused to generate power in a state where supply of the reaction gas to the fuel cell is stopped A process of obtaining
(C) The amount of electricity acquired in step (b) is applied to the correspondence between the amount of electricity generated when the fuel cell is generated in a state where the supply of the reaction gas is stopped in a low temperature environment and the amount of reaction heat. The estimated reaction heat quantity derived from the above is obtained, and the operating conditions for generating the fuel cell including the conditions relating to the circulation of the refrigerant used for cooling the fuel cell are determined from the obtained estimated reaction heat quantity, and the determined Generating the fuel cell according to operating conditions;
A control method for a fuel cell system, comprising:

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