JP2009043448A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system which carries out an appropriate water control according to changes in configurations of a catalyst electrode. <P>SOLUTION: The fuel cell system 1 is provided with: a membrane electrode assembly having an electrolyte portion and catalyst electrode portions which have pores in which a reaction gas flows and are arranged interposing the electrolyte portion; a humidity control means 5A which controls the humidity of the reaction gas flowing in the pores to a control target value; a power generation capacity detecting means 5B which detects deterioration of power generation capacity of the membrane electrode assembly due to blocking of the flow of the reaction gas flowing in the pores by water staying in the pores; and a control target value correction means 5C which corrects the control target value so that the flow of the reaction gas in the pores is not blocked by water staying in the pores, when the power generation capacity detecting means 5B detects deterioration of the power generation capacity of the membrane electrode assembly. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

  A fuel cell generates power by an electrochemical reaction between a fuel gas and an oxidizing gas. The electrochemical reaction is performed in a fuel cell carrying a membrane electrode assembly or a gas diffusion layer.

For example, Patent Document 1 describes a technique for controlling humidification according to temperature. Patent Document 2 describes a technique for controlling the amount of hydrogen and the amount of oxygen in accordance with variations in cell voltage. Patent Document 3 describes a technique for controlling the amount of humidification according to the cell voltage. Patent Document 4 describes a technique for purging water clogging when it is detected. Patent Document 5 describes a technique for reducing the water content of the membrane electrode assembly and suppressing the deterioration of the catalyst layer by supplying a dry gas when the cell voltage reaches a predetermined value or more. Patent Document 6 describes a technique for limiting the electrical output in accordance with the degree of deterioration.
JP-A-2005-142018 JP 2002-289235 A JP 2003-51329 A JP 2002-260704 A JP 2006-202718 A JP 2006-164555 A

  The catalyst electrode of the fuel cell generates protons from the fuel gas through the catalyst, or combines protons and oxidizing gas. In order to increase the contact between the catalyst and the reaction gas, the catalyst electrode has a surface area expanded by pores.

  The catalyst electrode is attached with water produced by an electrochemical reaction between a fuel gas, which is a reaction gas, and an oxidizing gas. When the generated water accumulates in the pores of the catalyst electrode, the flow of the reaction gas flowing through the pores is hindered, so that the electrochemical reaction is weakened and the electric output of the fuel cell is lowered.

  The form of the catalyst electrode gradually changes as power generation is repeated. For example, when the shape of the pores of the catalyst electrode changes, the ease with which generated water that accumulates in the pores also changes. The fuel battery cell needs to prevent the contact between the catalyst and the reaction gas from being disturbed while providing appropriate moisture to the electrolyte membrane. For this reason, it is necessary to perform appropriate water management for the fuel cell, but when the form of the catalyst electrode changes, the parameter of the optimum humidification amount and the like also change.

  In view of the above-described problems, an object of the present invention is to provide a fuel cell system that performs appropriate water management in accordance with a change in the shape of a catalyst electrode.

  In order to solve the above-described problems, the present invention corrects the control target value of the humidity of the reaction gas when detecting a decrease in the power generation capability of the membrane electrode assembly accompanying the change in the shape of the pores of the catalyst electrode.

Specifically, it is a fuel cell system that generates electric power by an electrochemical reaction between a fuel gas, which is a reaction gas, and an oxidizing gas, and has an electrolyte part and a hole through which the reaction gas flows, and is disposed across the electrolyte part. And a humidity that controls the humidity of the reaction gas flowing through the holes to a control target value that does not hinder the flow of the reaction gas by water accumulated in the holes. And a power generation capability for detecting a decrease in the power generation capability of the membrane electrode assembly caused by the flow of the reaction gas flowing through the pores being inhibited by water accumulated in the pores due to deformation of the pores. When the detection means and the power generation capacity detection means detect a decrease in the power generation capacity of the membrane electrode assembly, the control target is set so that the flow of the reactive gas in the holes is not hindered by the water accumulated in the holes. Control eye to correct the value It comprises a value correcting means.

  The fuel cell system includes a membrane electrode assembly for electrochemically reacting a fuel gas, which is a reaction gas, and an oxidizing gas. This membrane electrode assembly is arranged with the electrolyte portion sandwiched between the catalyst electrode portions, and protons generated on the anode side of the catalyst electrode portion move to the cathode side of the catalyst electrode portion via the electrolyte portion. .

  In order for protons to move, the electrolyte part needs to contain water. Since the electrolyte part is sandwiched between the catalyst electrode parts, in order to give water to the electrolyte part, the fuel gas and the oxidizing gas flowing through the catalyst electrode part are humidified. The catalyst electrode portion has a surface area widened by pores in order to enhance the function as a catalyst. When the humidity of the reaction gas is high, sufficient water is given to the electrolyte part, but the pores of the catalyst electrode are blocked with water, and the function of the catalyst is lowered. When the humidity of the reaction gas is low, the pores of the catalyst electrode are not blocked by water, so the function of the catalyst does not deteriorate, but sufficient water is not given to the electrolyte part, and protons moving from the anode side to the cathode side decrease. For this reason, the fuel cell system needs to perform appropriate water management in order to increase the power generation capacity. Therefore, the humidity control means controls the humidity of the reaction gas flowing through the holes so that the water flow in the holes does not hinder the flow of the reaction gas.

  The form of the catalyst electrode portion changes due to repeated starting and stopping. When the shape of the catalyst electrode portion is changed, the holes are also deformed. When the holes are deformed, the holes may be easily blocked with water. Here, unless the control target value of the humidity of the reaction gas is changed, the holes are likely to be clogged with water as the catalyst electrode portion changes in form. Thereby, the power generation capability of the membrane electrode assembly is lowered. Therefore, the control target value correcting means corrects the control target value of the humidity control means for controlling the humidity of the reactive gas when detecting a decrease in the power generation capacity of the membrane electrode assembly accompanying the change in the shape of the catalyst electrode portion. The control target value correction means reduces the water accumulated in the holes by lowering the control target value of the humidity control means, and restores the flow of gas flowing through the holes. Note that a decrease in the power generation capability of the membrane electrode assembly is detected by the power generation capability decrease detection means.

  As mentioned above, according to the fuel cell system concerning the present invention, it becomes possible to perform appropriate water management according to the change in form of the catalyst electrode.

  Here, the power generation capacity detection means detects an electrical output detection means for detecting a decrease in the electrical output of the membrane electrode assembly, and the electrical output detection means detects a decrease in the electrical output of the membrane electrode assembly, The flow rate changing means for increasing the flow rate of the reaction gas flowing through the holes, and the electrical output detection based on the amount of change in the electrical output of the membrane electrode assembly when the flow rate change means increases the flow rate of the reaction gas. Flooding detection means for detecting whether or not the decrease in electrical output of the membrane electrode assembly detected by the means is due to flooding, and the decrease in electrical output detected by the electrical output detection means due to flooding When it is detected by the flooding detection means that the electric power is not, it is detected that the decrease in the electric output is a decrease in the power generation capacity due to the deformation of the holes. It may be.

  When the power generation capacity of the membrane electrode assembly decreases, the electric output decreases. The power generation capability detection means detects a decrease in the power generation capability of the membrane electrode assembly by detecting a decrease in the electrical output by the electrical output detection means.

  The case where the electrical output of the membrane electrode assembly decreases due to water adhering to the surface of the catalyst electrode (in the case of flooding) can be mentioned in addition to the decrease due to the change in the shape of the catalyst electrode. In the case of flooding, the water adhering to the surface of the catalyst electrode moves by changing the flow rate of the reaction gas. When water adhering to the surface of the catalyst electrode moves, the electrical output of the membrane electrode assembly changes. Therefore, the power generation capacity detecting means increases the flow rate of the reaction gas by the flow rate changing means in order to distinguish between a decrease in the electrical output due to a change in the shape of the catalyst electrode and a decrease in the electrical output due to flooding. The flooding detection means monitors the amount of change in electrical output when the flow rate changing means increases the flow rate of the reaction gas. The flooding detection means detects whether or not the membrane electrode assembly is in a flooding state from the amount of change in the electrical output. The power generation capacity detection unit determines that the decrease in the electrical output is due to deformation of the holes when the decrease in the electrical output detected by the electrical output detection unit is not due to flooding. As described above, it is possible to detect a change in the shape of the catalyst electrode.

  Here, the control target value correcting means, when the power generation capacity detecting means detects a decrease in the power generation capacity of the membrane electrode assembly, temporarily changes the control target value and outputs the electrical output of the membrane electrode assembly. It is also possible to acquire a value when the value becomes the highest and correct the acquired value to a new control target value of the humidity control means.

  When the shape of the catalyst electrode changes, it is necessary to correct the control target value of the humidity control means to an appropriate value. An appropriate value is a value at which water that inhibits the flow of the reaction gas does not accumulate in the pores, and is, for example, a value at which the electrical output of the membrane electrode assembly is the highest. Since the control target value correction means acquires the value when the electric output becomes the highest, when the power generation capability of the membrane electrode assembly decreases, the control target value of the humidity control means is temporarily changed. That is, when the control target value correcting unit detects a decrease in the power generation capacity, the control target value correcting unit temporarily decreases or increases the control target value of the humidity control unit while monitoring the electrical output. When the control target value correcting means obtains the value when the electric output becomes the highest, it sets this as a new control target value for the humidity control means. This makes it possible to maximize the power generation capability of the membrane electrode assembly even when the form of the catalyst electrode changes.

  Here, when the control target value correcting means detects a decrease in the power generation capability of the membrane electrode assembly caused by deformation of the holes due to aging of the catalyst electrode, the flow of the reaction gas flowing through the holes The control target value may be corrected so as not to be hindered by water accumulated in the holes.

  The change in the shape of the catalyst electrode gradually proceeds with repeated power generation over a long period of time. By detecting such a decrease in power generation capacity due to aging and performing appropriate water management in accordance with changes in the shape of the catalyst electrode, sufficient power generation capacity of the membrane electrode assembly can be obtained even if the catalyst electrode deteriorates over time. It will be possible to demonstrate.

  Further, the present invention is a fuel cell system that generates electric power by an electrochemical reaction between a fuel gas that is a reaction gas and an oxidizing gas, and includes an electrolyte part and a catalyst electrode part that is disposed across the electrolyte part. Membrane electrode assembly, humidity control means for controlling the humidity of the reaction gas flowing through the membrane electrode assembly to a control target value corresponding to the state of water adhering to the membrane electrode assembly, and the membrane electrode assembly The flow of the reaction gas flowing through the catalyst electrode part of the membrane electrode assembly is reduced by the change in the physical state of the catalyst electrode part associated with the behavior of water adhering to the catalyst electrode part of the membrane electrode assembly A power generation capacity detecting means for detecting a decrease in the power generation capacity of the membrane electrode assembly due to being blocked by water adhering to the catalyst electrode part, and the power generation capacity detection means reduces the power generation capacity of the membrane electrode assembly When the catalyst electrode is detected, A control target value correcting means for correcting the control target value so as not to be inhibited by water adhering to the catalyst electrode part flow of the reaction gas flowing through, may be provided with a.

  The power generation capacity detecting means of this fuel cell system detects a decrease in power generation capacity due to a change in the physical state of the membrane electrode assembly that changes the water state of the membrane electrode assembly. Here, the change in the physical state of the membrane electrode assembly is a change in the physical state of the catalyst electrode portion related to the behavior of water adhering to the catalyst electrode portion of the membrane electrode assembly, and is optimal for power generation. This is a change in the physical state in which the humidity control target value changes.For example, the water repellency and hydrophilicity affected by deformation of the pores of the catalyst electrode and alteration of the material, etc. And changes in water absorption characteristics. In this fuel cell system, the humidity control target value is corrected in accordance with a change in the physical state relating to water, so that the power generation capability of the membrane electrode assembly is sufficiently exhibited.

  According to the fuel cell system of the present invention, appropriate water management can be performed in accordance with the change in the shape of the catalyst electrode.

<Embodiment>
Hereinafter, embodiments of the present invention will be exemplarily described. Embodiment shown below is an illustration and this invention is not limited to these.

<Configuration of Embodiment>
FIG. 1 is a configuration diagram of a fuel cell system 1 according to the present embodiment. As shown in FIG. 1, the fuel cell system 1 includes a fuel cell stack 2, a hydrogen storage tank 3 that supplies hydrogen as fuel gas to the anode side of the fuel cell stack 2, and an oxidizing gas on the cathode side of the fuel cell stack 2. And an air compressor 4 for supplying air containing oxygen. The fuel cell system 1 includes a control device 5 (ECU: Electronic Control Unit) that controls each device. The fuel cell system 1 according to the present embodiment is premised on being mounted on a fuel cell vehicle that runs on an electric motor. However, the present invention is not limited to this, and may be installed on the ground or mounted on a moving medium other than an automobile.

The fuel cell stack 2 is a polymer electrolyte fuel cell (PEFC) suitable for a moving medium such as a fuel cell vehicle, and generates power by being supplied with hydrogen and oxygen. The fuel cell stack 2 includes a number of membrane electrode assemblies (MEA) that generate electricity by an electrochemical reaction between hydrogen, which is a fuel gas, and oxygen, which is an oxidizing gas, and a fuel having these membrane electrode assemblies. The battery cells are stacked so as to output a desired voltage.

  The fuel cell system 1 includes a hydrogen inlet valve 6 in the middle of a passage for supplying hydrogen from the hydrogen storage tank 3 to the fuel cell stack 2. The hydrogen inlet valve 6 is a control valve whose opening degree can be adjusted by a command from the control device 5, and controls hydrogen flowing from the hydrogen storage tank 3 to the fuel cell stack 2.

  Further, the fuel cell system 1 includes a hydrogen outlet valve 7 in the middle of a passage for discharging anode off gas from the anode side of the fuel cell stack 2 to the atmosphere. The hydrogen outlet valve 7 is a control valve whose opening degree can be adjusted by a command from the control device 5 and controls the anode off-gas released to the atmosphere.

  In addition, the fuel cell system 1 includes a humidifier 8 in the middle of a passage for supplying air from the air compressor 4 to the fuel cell stack 2. The humidifier 8 adjusts the humidity of the air flowing from the air compressor 4 to the fuel cell stack 2 in accordance with a command from the control device 5.

Further, the fuel cell system 1 includes an air outlet valve 9 in the middle of a passage for releasing cathode off gas from the cathode side of the fuel cell stack 2 to the atmosphere. The air outlet valve 9 is a control valve whose opening degree can be adjusted by a command from the control device 5, and controls the cathode off-gas released to the atmosphere.

The control device 5 includes a CPU (Central Processing Unit), a RAM (Random Access Memory).
), A ROM (Read Only Memory), an input / output interface, and the like, and controls the air compressor 4, the humidifier 8, the air outlet valve 9, the hydrogen inlet valve 6, and the hydrogen outlet valve 7.

  The control device 5 is electrically connected to a voltage sensor 10 that measures the output voltage of the fuel cell stack 2 and a current sensor 11 that measures the output current of the fuel cell stack 2. Obtain voltage and output current.

  FIG. 2 is a functional block diagram of the control device 5. The control device 5 includes a control unit 5A (humidity control referred to in the present invention) that controls a valve, a humidifier 8, and other auxiliary devices by cooperation of a CPU, RAM, ROM, and an input / output interface (not shown). A power generation capacity detector 5B (corresponding to the power generation capacity detector in the present invention) that detects a decrease in power generation capacity of the membrane electrode assembly, and a control that corrects the control target value of the humidity controller 5A. The function of the target value correcting unit 5C (corresponding to the control target value correcting means in the present invention) is realized.

  The control unit 5A is provided with a map indicating control target values such as an optimal humidification amount and valve opening, which are determined in advance according to the output voltage and output current of the fuel cell stack 2 and the supply flow rates of hydrogen and oxygen. Yes. When the fuel cell system 1 is activated, the control unit 5A controls the auxiliary devices such as the valves and the humidifier 8 based on this map.

  The power generation capability detector 5B detects a decrease in the power generation capability of the membrane electrode assembly due to a change in the shape of the catalyst electrode (for example, a change in water retention capacity that changes with the aging of the catalyst). The power generation capacity detector 5B includes an electrical output detector 5B-a that detects a decrease in electrical output of the membrane electrode assembly based on signals sent from the voltage sensor 10 and the current sensor 11. In addition, the power generation capacity detection unit 5B is configured to change the opening degree of the air outlet valve 9 in order to distinguish between a temporary decrease in electric output due to the flooding phenomenon and a decrease in power generation capacity due to deterioration of the catalyst electrode. 5B-b and a flooding detection unit 5B-c that detects the presence or absence of flooding from the amount of change in electrical output when the flow rate changing unit 5B-b changes the opening degree of the air outlet valve 9. In the power generation capacity detection unit 5B, when the electrical output detection unit 5B-a detects a decrease in the electrical output of the membrane electrode assembly, the flow rate changing unit 5B-b increases the flow rate of the air. When flooding occurs, water adhering to the membrane electrode assembly moves when the air flow rate is increased, so that the reaction gas and the catalyst easily come into contact with each other, and the electric output fluctuates. Therefore, the flooding detection unit 5B-c detects the presence or absence of flooding based on the amount of change in the electrical output of the membrane electrode assembly when the flow rate changing unit 5B-b increases the air flow rate. The flooding detection unit 5B-c determines that the power generation capability of the membrane electrode assembly is reduced when the decrease in the electrical output of the membrane electrode assembly is not due to flooding.

  When the power generation capacity detector 5B detects a decrease in the power generation capacity of the membrane electrode assembly, the control target value corrector 5C corrects the control target value indicated by the map of the humidity controller 5A.

<Control Flow of Embodiment>
Next, operation control of the fuel cell system 1 according to the present embodiment will be described. FIG. 3 is a control flow diagram of the fuel cell system 1. Hereinafter, the operation control of the fuel cell system 1 will be described with reference to the control flowchart shown in FIG.

(Step S101: Start of power generation) When the fuel cell system 1 is started by the driver who has boarded the fuel cell vehicle, the control unit 5A opens the hydrogen inlet valve 6 and the hydrogen outlet valve 7 to supply hydrogen to the fuel cell stack 2. At the same time, the air outlet valve 9 is opened to activate the air compressor 4, and air whose humidity is controlled according to the control target value of the map is supplied to the fuel cell stack 2. When the control unit 5 </ b> A starts supplying hydrogen and oxygen to the fuel cell stack 2, the control unit 5 </ b> A connects an electrical load to the fuel cell stack 2. As a result, hydrogen and oxygen undergo an electrochemical reaction in the membrane electrode assembly in the fuel cell stack 2, and power generation is started.

(Step S102: Electric Output Monitoring) When the control unit 5A executes the process of step S101 to start power generation, the electric output detection unit 5B-a outputs the electric output of the fuel cell stack 2 with the voltage sensor 10 and the current sensor 11. Monitor. In FIG. 4, the change of the electrical output accompanying aged deterioration is shown. As shown in FIG. 4, the electrical output detector 5B-a changes the flow rate of the air supplied to the fuel cell stack 2 when the reduction amount (ΔV ₁ ) of the electrical output of the fuel cell stack 2 reaches a predetermined value or more. The process to perform (step S103) is executed. The predetermined value is a value stored in advance in a ROM or the like. For example, the predetermined value is an electric output of the membrane electrode assembly when the deterioration of the catalyst electrode progresses and it is desirable to correct the control target value. is there.

  (Step S103: Flow Rate Change) The flow rate change unit 5B-b temporarily increases the opening of the air outlet valve 9 when the electric output detection unit 5B-a detects a decrease in the electric output of the fuel cell stack 2, and again Return to the original opening. Since the flow rate changing unit 5B-b increases the opening degree of the air outlet valve 9, the flow rate of the air flowing on the cathode side of the fuel cell stack 2 is increased, so that when the generated water adheres to the membrane electrode assembly, Water flows downstream.

  (Step S104: Flooding Detection) The flooding detection unit 5B-c monitors the change in the electrical output of the fuel cell stack 2 when the flow rate changing unit 5B-b changes the opening of the air outlet valve 9. That is, the flooding detection unit 5B-c is configured so that the flow rate change unit 5B-b increases the electrical output of the fuel cell stack 2 before the air outlet valve 9 is opened and the fuel after the air outlet valve 9 is opened. The electric output of the battery stack 2 is compared and the change of the electric output is monitored. If the electrical output of the fuel cell stack 2 increases after the flow rate change unit 5B-b changes the flow rate, the flooding detection unit 5B-c reduces the decrease in the electrical output detected by the electrical output detection unit 5B-a in step S102. Judging by flooding. On the other hand, if the electric output of the fuel cell stack 2 does not increase after the flow rate change unit 5B-b changes the flow rate, the flooding detection unit 5B-c detects the electric output detected by the electric output detection unit 5B-a in step S102. This decrease is not due to flooding, but is determined to be a decrease in power generation capability of the membrane electrode assembly due to a change (deterioration) in the shape of the catalyst electrode. That is, the flooding detection unit 5B-c determines that the carbon carrier of the catalyst electrode is oxidized due to aging, the pores between the carbon carriers are reduced, the generated water is easily collected, and the power generation capacity is reduced.

(Step S105: Control Target Value Correction) The control target value correction unit 5C corrects the control target value indicated by the map of the humidity control unit 5A when the power generation capability detection unit 5B detects a decrease in the power generation capability of the membrane electrode assembly. . In the correction, the control target value correcting unit 5C corrects the control target value to an arbitrary value lower than that before the correction. When the control target value correction unit 5C corrects the control target value, the amount of humidification of the air supplied to the fuel cell stack 2 decreases. The control target value correction unit 5C sets various values different from each other when correcting the control target value, and sets the value when the electric output of the fuel cell stack 2 is highest as a new control target value. In FIG. 5, the relationship with the electrical output when the amount of humidification is changed is shown by the graph of time passage. As shown in FIG. 5, the control target value correction unit 5C sets various values (humidification amounts A, B, C, D...) Different from each other when correcting the control target value, and each electric output (W _A , W _B , W _C , W _D ,...) Are acquired, and the humidification amount at the time when the output becomes the highest is examined and corrected to a new control target value. The control objective point correction unit 5C is If changing the humidification amount not electrical output is high (i.e., when the electric output W ₁ is the highest), the next to the control unit 5A without changing the control target value The process of step S106 is executed.

  (Step S106: Continue Operation) After the process in step S104 or step S105 is completed, the control unit 5A controls auxiliary devices such as the valves and the humidifier 8 to continue power generation. In the case after the process of step S105 is completed, the control unit 5A controls the humidifier 8 and other auxiliary devices based on the control target value of the map corrected by the control target value correction unit 5C. Continue power generation.

<Effect of embodiment>
As described above, according to the fuel cell system 1 according to the present embodiment, a behavior in which the voltage change per unit time is large, such as flooding, a rapid decrease in the cell voltage due to lack of reaction gas, and resistance due to drying of the membrane electrode assembly. And a secular change with a relatively long time axis, which is a change in the shape of the catalyst electrode, and water management is performed according to the secular change, so that efficient power generation can be performed.

  In the present embodiment, the correction of the control target value is performed for the humidity control of the air flowing on the cathode side, but the present invention is not limited to this. That is, in the present invention, the water management of the electrolyte membrane may be appropriately performed by correcting the control target value of the humidity of hydrogen flowing on the anode side.

  In the present embodiment, the fuel cell system 1 detects a decrease in the electrical output of the membrane electrode assembly by the electrical output detector 5B-a monitoring the electrical output of the entire fuel cell stack 2. The present invention is not limited to this. That is, in the fuel cell system according to the present invention, the electric output detector 5B-a individually acquires the electric output of each fuel cell, and the fuel cell having the highest electric output and the fuel cell having the lowest electric output. When the difference in the electrical output with respect to exceeds a certain value, or when the electrical output of the fuel cell having the lowest electrical output falls below a certain value, the processing after step S103 may be executed.

  Further, in the present embodiment, the fuel cell system 1 corrects the control target value of the humidifier 8 that humidifies the air supplied from the air compressor 4, but the present invention is not limited to this. . That is, in the fuel cell system according to the present invention, when the reaction gas supplied to the fuel cell stack is humidified, the off-gas is cooled to condense the water contained in the off-gas, and the condensed water is used to humidify the reaction gas. An exchange system may be used.

  In the present embodiment, the fuel cell system 1 corrects the control target value in accordance with the change in the shape of the pores of the catalyst electrode, but the present invention is not limited to this. That is, the fuel cell system according to the present invention has a change in the physical state of the catalyst electrode of the membrane electrode assembly (a change in the physical state of the catalyst electrode such that the control target value of humidity optimum for power generation changes). Yes, for example, outflow and alteration of the water repellent material of the catalyst electrode (catalyst layer), aging of the electrolyte membrane, changes in the surface condition of the flow path (change in water repellency, hydrophilicity, etc.) The control target value may be corrected accordingly.

1 is a configuration diagram of a fuel cell system according to an embodiment. The functional block diagram of the control apparatus which concerns on embodiment. The control flow figure of the fuel cell system concerning an embodiment. The graph which shows the change of the electrical output accompanying aged deterioration. The graph which shows the relationship with the electrical output when the humidification amount is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system 2 ... Fuel cell stack 3 ... Hydrogen storage tank 4 ... Air compressor 5 ... Control apparatus 5A ... Control Unit 5B ... Power generation capacity detection unit 5B-a Electric output detection unit 5B-b Flow rate change unit 5B-c Flooding detection unit 5C ... Control target value correction unit 6 ... · Hydrogen inlet valve 7 ··· Hydrogen outlet valve 8 ··· Humidifier 9 ··· Air outlet valve 10 ··· Voltage sensor 11 ··· Current sensor

Claims (5)

A fuel cell system that generates power by an electrochemical reaction between a fuel gas, which is a reactive gas, and an oxidizing gas,
A membrane electrode assembly having an electrolyte part and a catalyst electrode part having a hole through which the reaction gas flows and sandwiching the electrolyte part;
Humidity control means for controlling the humidity of the reaction gas flowing through the holes to a control target value that does not impede the flow of the reaction gas by the water accumulated in the holes;
Power generation capacity detecting means for detecting a decrease in power generation capacity of the membrane electrode assembly due to the deformation of the holes, and the flow of the reaction gas flowing through the holes is blocked by water accumulated in the holes;
When the power generation capacity detecting means detects a decrease in the power generation capacity of the membrane electrode assembly, the control target value is corrected so that the flow of the reaction gas in the holes is not hindered by water accumulated in the holes. And a control target value correcting means. The power generation capacity detecting means is
An electrical output detecting means for detecting a decrease in electrical output of the membrane electrode assembly;
When the electrical output detection means detects a decrease in electrical output of the membrane electrode assembly, flow rate changing means for increasing the flow rate of the reaction gas flowing through the holes,
The decrease in the electrical output of the membrane electrode assembly detected by the electrical output detection means is flooded based on the amount of change in the electrical output of the membrane electrode assembly when the flow rate changing means increases the flow rate of the reaction gas. Flooding detection means for detecting whether or not
When the flooding detection means detects that the decrease in electrical output detected by the electrical output detection means is not due to flooding, it detects that the decrease in electrical output is a decrease in power generation capacity due to deformation of the holes. To
The fuel cell system according to claim 1. The control target value correcting means, when the power generation capacity detecting means detects a decrease in the power generation capacity of the membrane electrode assembly, temporarily changes the control target value to provide the highest electrical output of the membrane electrode assembly. Is obtained, and the obtained value is corrected to a new control target value of the humidity control means.
The fuel cell system according to claim 1 or 2. When the control target value correcting means detects a decrease in power generation capability of the membrane electrode assembly caused by deformation of the pores due to aging of the catalyst electrode, the flow of the reaction gas flowing through the pores becomes the void. Correcting the control target value so as not to be hindered by water accumulated in the hole,
The fuel cell system according to any one of claims 1 to 3. A fuel cell system that generates power by an electrochemical reaction between a fuel gas, which is a reactive gas, and an oxidizing gas,
A membrane electrode assembly having an electrolyte part, and a catalyst electrode part disposed across the electrolyte part,
Humidity control means for controlling the humidity of the reaction gas flowing through the membrane electrode assembly to a control target value corresponding to the state of water adhering to the membrane electrode assembly;
A decrease in power generation capacity due to a change in physical state of the catalyst electrode part related to the behavior of water adhering to the catalyst electrode part of the membrane electrode assembly, which flows through the catalyst electrode part of the membrane electrode assembly Power generation capacity detecting means for detecting a decrease in power generation capacity of the membrane electrode assembly due to the flow of the reaction gas being inhibited by water adhering to the catalyst electrode part;
When the power generation capacity detection means detects a decrease in the power generation capacity of the membrane electrode assembly, the control target value is set so that the flow of the reaction gas flowing through the catalyst electrode section is not hindered by water adhering to the catalyst electrode section. And a control target value correcting means for correcting the fuel cell system.

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