JP2011216337A - Fuel battery power generating device, and method of monitoring fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery power generating device and a method of monitoring the fuel battery, capable of appropriately detecting the abnormality of voltage drop of a cell of the fuel battery.SOLUTION: A fuel battery power generating device 1 having a fuel battery 2 constructed by stacking in series a plurality of cell blocks 2b consisting of the prescribed number of fuel battery cells 2a stacked in series includes: a characteristic obtaining unit 21 previously obtaining the relation between an output power W of the fuel battery 2 and an output voltage V of the cell block 2b based on respective voltage-current characteristics of the cells 2a of the fuel cell; a target power obtaining unit 22 obtaining the target power of the fuel cell 2; a threshold value control unit 23 computing an abnormality detecting voltage Vof the cell block in the target power Wbased on the relation and a target power W; and an abnormality detecting unit 24 detecting the abnormality of the cell block 2b based on the magnitude relation between the output voltage V and abnormality detecting voltage Vof the cell block 2b.

Description

  The present invention relates to a fuel cell power generator and a fuel cell monitoring method.

  2. Description of the Related Art As a conventional fuel cell power generation device, one having a fuel cell configured by stacking a plurality of blocks each composed of an arbitrary number of fuel cells stacked in series is known (for example, a patent document) 1). In the fuel cell power generation device described in Patent Document 1, a voltage is detected in units of blocks, and a voltage abnormality of the fuel cells is detected using a magnitude relationship between the detected voltage and a specific threshold value preset in units of blocks. To do. The specific threshold is determined based on the total voltage of the entire fuel cell and the voltage in block units.

JP 2005-26239 A

  By the way, the desirable voltage of each fuel cell changes according to the power generation state of the fuel cell. For this reason, in the fuel cell power generation device described in Patent Literature 1, there is a possibility that voltage abnormality of individual fuel cells cannot be detected appropriately. For example, even if a specific threshold value is exceeded, depending on the power generation state of the fuel cell, there may be an undesirable situation in each fuel cell.

  Therefore, an object of the present invention is to provide a fuel cell power generation apparatus and a fuel cell monitoring method capable of appropriately detecting an abnormality in the voltage drop of the fuel cell.

  In order to solve the above-described problems, a fuel cell power generation device according to the present invention includes a fuel cell power generation including a fuel cell configured by stacking a plurality of cell blocks each including a plurality of fuel cell cells stacked in series. An apparatus for obtaining in advance a relationship between the output power of the fuel cell and the output voltage of the cell block based on the voltage-current characteristics of each of the fuel cells; and a target power of the fuel cell. Target power acquisition means for acquiring, threshold calculation means for calculating an abnormality detection voltage of the cell block at the target power based on the relationship and the target power, an output voltage of the cell block, and the abnormality detection voltage And an abnormality detecting means for detecting an abnormality of the cell block based on the magnitude relationship.

  In the fuel cell power generator according to the present invention, the relationship between the output power of the fuel cell and the output voltage of the cell block is acquired in advance based on the voltage-current characteristics of each fuel cell by the characteristic acquisition means, and the fuel is generated by the target power acquisition means. The target power of the battery is acquired, the abnormality detection voltage of the cell block at the target power is calculated based on the relationship and the target power by the threshold calculation means, and the magnitude of the output voltage and the abnormality detection voltage of the cell block is calculated by the abnormality detection means. A cell block abnormality is detected based on the relationship. As described above, the abnormality detection voltage is not a constant value but a value corresponding to the target power of the fuel cell based on the voltage-current characteristics of each fuel cell. Abnormality can be determined. For this reason, the abnormality of the voltage drop of a fuel battery cell can be detected appropriately.

  Here, the abnormality detection means includes a light emitting element that is connected to both ends of the cell block and emits light when a voltage greater than the abnormality detection voltage is applied, and a light receiving element that constitutes a photocoupler together with the light emitting element, The abnormality of the cell block may be detected based on the potential of the light receiving element.

  Further, the fuel cell power generation device determines whether or not the abnormality detection voltage is smaller than a predetermined threshold value, and when the determination means determines that the abnormality detection voltage is smaller than a predetermined threshold value, It is preferable to include threshold value fluctuation stopping means for fixing the abnormality detection voltage to a predetermined value. With this configuration, appropriate monitoring can be performed even when the information regarding the abnormality detection voltage of the fuel cell is inaccurate or when there is an abnormality in the communication path for transmitting information regarding the abnormality detection voltage. it can.

  Further, the fuel cell monitoring method according to the present invention is a fuel cell monitoring method for monitoring a voltage abnormality of a fuel cell configured by stacking a plurality of cell blocks each including a plurality of fuel cell cells stacked in series. A relationship acquisition step for acquiring in advance a relationship between the output power of the fuel cell and the output voltage of the cell block based on the voltage-current characteristics of each of the fuel cells, and during the operation of the fuel cell, Based on the target power acquisition step of acquiring the target power of the fuel cell, the relationship acquired in the relationship acquisition step, and the target power acquired in the target power acquisition step, the abnormality of the cell block in the target power A threshold calculation step for calculating a detection voltage; and the abnormality detection voltage calculated by the threshold calculation step is used as the light emitting element. Configured with the a threshold setting step of setting a predetermined voltage, and a failure detection step for detecting an abnormality of the cell blocks based on the potential of the light receiving element.

  Here, in the fuel cell monitoring method, a determination step for determining whether or not the abnormality detection voltage calculated by the threshold calculation step is smaller than a predetermined threshold, and the abnormality detection voltage by the determination step is less than a predetermined threshold. If it is determined that the threshold voltage is small, a threshold value fluctuation stopping step of fixing the abnormality detection voltage to a predetermined value may be provided.

  According to the fuel cell monitoring method of the present invention, the same effects as those of the fuel cell power generator described above can be obtained.

  According to the present invention, it is possible to appropriately detect an abnormality in the voltage drop of the fuel battery cell.

1 is a schematic configuration diagram of an embodiment of a system including a fuel cell power generator according to the present invention. It is an example of the fuel cell and voltage detection circuit which are shown in FIG. It is an example of the current-voltage characteristic of the fuel cell shown in FIG. It is an example of the power voltage characteristic of the fuel cell shown in FIG. It is a flowchart which shows the monitoring operation | movement of the fuel cell power generator of FIG. It is a graph which shows the input gas dependence of the electric current in the fuel cell shown in FIG. 1, voltage, and electric power. It is a flowchart which shows the threshold value change stop operation | movement of the fuel cell power generator of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

(First embodiment)
The fuel cell power generator according to the first embodiment is suitably employed in, for example, a household fuel cell system. FIG. 1 is a schematic configuration diagram of a fuel cell system including a fuel cell power generator 1 according to the present embodiment. As shown in FIG. 1, the fuel cell system includes a fuel cell power generator 1 having a fuel cell 2 and a control unit 20.

  The fuel cell 2 is a direct current power supply (DC power supply) and supplies power to an external load (home load) 9. As the fuel cell 2, for example, a polymer electrolyte fuel cell that generates power using a reformed gas generated by reforming raw fuel is used. The fuel cell 2 is configured by stacking an arbitrary number of fuel cells 2a in series. The fuel cell 2a includes a pair of electrodes, an anode, and a cathode, which are respectively joined to opposing surfaces of a solid polymer electrolyte membrane such as a polymer ion exchange membrane. The fuel cell 2 is supplied with reformed gas containing hydrogen and air, and an electrochemical reaction occurs in each anode and cathode of the fuel cell 2a to generate power. The cell block 2b is composed of an arbitrary number of fuel cells 2a stacked in series. For example, one cell block 2b is constituted by three fuel cells 2a.

  The control unit 20 is a computer of an electronically controlled device, and includes a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), an input / output interface, and the like. . Details of the control unit 20 will be described later.

  A power conditioner (PC) 3 is connected to the fuel cell power generator 1, and the power output from the fuel cell 2 is supplied to the power conditioner 3. The electric power of the fuel cell 2 is boosted by the booster 30 of the power conditioner 3, converted into AC power by the converter 31, and supplied to the external load 9. The external load 9 is connected to an AC power supply 8 as a system power supply, and is configured such that the power from the AC power supply 8 and the power from the fuel cell 2 can be used together. A surplus heater 4 is connected to the power conditioner 3 so that surplus power generated when the power consumption of the external load 9 rapidly decreases can be consumed. For example, an electric heater is used as the surplus heater 4.

  Further, the fuel cell system includes an exhaust heat recovery system that recovers heat generated by the surplus heater 4. The exhaust heat recovery system includes a hot water storage tank 7 in which household water is stored, a water pump 6 that circulates water in the hot water storage tank in a circulation path, and a heat exchanger 5 that is provided on the downstream side of the water pump 6. I have. The heat exchanger 5 is configured such that the circulating water in the circulation path can exchange heat of the excess heater 4. For this reason, the water in the hot water storage tank 7 is circulated in the circulation path by the water pump 6, the heat of the surplus heater 4 is recovered by the heat exchanger 5, and is stored in the hot water storage tank 7 again. The exhaust heat recovery system uses the fuel cell 2 as a power source.

  The operation of the components of the fuel cell system described above is controlled by a control device (not shown) that is, for example, electrical equipment. The control device controls the components of the fuel cell system described above in accordance with information output from sensors provided in the fuel cell system, usage status of the user, and the like.

  Here, details of the control unit 20 will be described. As shown in FIG. 1, the control unit 20 includes a characteristic acquisition unit (characteristic acquisition unit) 21, a target power acquisition unit (target power acquisition unit) 22, a threshold control unit (threshold calculation unit) 23, an abnormality detection unit (abnormality detection). Means) 24 and an operation control unit 25. The control unit 20 is connected to the above-described control device and sensors provided in the fuel cell system, and is configured to be able to acquire operation information of the fuel cell system.

  The characteristic acquisition unit 21 has a function of acquiring the characteristics of the fuel cell 2 in advance. This characteristic is a current-voltage characteristic of each fuel cell 2a of the fuel cell 2, and is, for example, measured in advance for each individual fuel cell 2a. The characteristic acquisition unit 21 has a function of calculating in advance the relationship between the output power W of the fuel cell 2 and the output voltage V of the cell block 2b based on the current-voltage characteristics of each fuel cell 2a.

Target power obtaining unit 22, for example, has a function of acquiring the target power W _K power value and the control device external load 9 is request has been set.

The threshold control unit 23 has a function of calculating a reference voltage (abnormality detection voltage V _A ) necessary for determining whether or not a voltage drop abnormality has occurred in the fuel cell 2. The threshold control unit 23, for example, the relationship between the output power W of the fuel cell 2 and the output voltage V of the cell block 2 b calculated by the characteristic acquisition unit 21, and the target power W _K acquired by the target power acquisition unit 22. The abnormality detection voltage V _A of the cell block 2b at the target power W _K is calculated based on the above. Further, the threshold control unit 23 has a function of changing a setting value of an abnormality detection unit 24 (to be described later) and changing an abnormality detection voltage _VA by PWM (Pulse Width Modulation) output, for example.

The abnormality detection unit 24 has a function of detecting whether or not a voltage drop abnormality has occurred in the fuel cell 2. For example, when the output voltage V of the cell block 2b is not larger than the abnormality detection voltage _VA calculated by the threshold control unit 23, the abnormality detection unit 24 generates an abnormality in voltage drop in the cell block 2b. It has the function to judge that it is. In order to exhibit this function, the abnormality detection unit 24 includes, for example, a photocoupler. FIG. 2 is an example of a voltage detection circuit for exhibiting the function of the abnormality detection unit 24.

  As shown in FIG. 2, a series circuit of a resistor 40, a light emitting diode (light emitting element) 41A and a diode 42 is connected to both ends of one cell block 2b in the fuel cell 2. The light emitting diode 41A constitutes a photocoupler 41 together with a phototransistor (light receiving element) 41B. The collector of the phototransistor 41B is connected to a positive potential of 5 V, for example, and the emitter is grounded. The collector of the phototransistor 41B is connected to the base of the transistor 43. The emitter of the transistor 43 is grounded, and the collector is connected to a positive potential of 5 V, for example, via the light emitting diode 44. The collector of the transistor 43 is connected to an arithmetic processing unit (not shown) of the control unit 20 via a diode 45.

The base voltage of the transistor 43 driven via the phototransistor 41B can be dynamically changed by the PWM output of the threshold control unit 23. The current flowing through the light emitting diode 41A changes according to the output voltage V of the cell block 2b, and the current drives the output side phototransistor 41B according to the current transfer rate of the photocoupler. When the output voltage V of the cell block 2b is larger than the abnormality detection voltage _VA , the diode 42 is turned on, the light emitting diode 41A emits light, and the phototransistor 41B receives light. Therefore, the base of the transistor 43 is set to 0 V (ground), and the transistor 43 is turned off. For this reason, the light emitting diode 44 is turned off, and a normal signal (for example, 0) is output from the diode 45 to the arithmetic processing unit. Further, when the output voltage V of the cell block 2b is not larger than the abnormality detection voltage _VA , the diode 42 is turned off and the light emitting diode 41A does not emit light. For this reason, the base of the transistor 43 becomes a positive potential, and the transistor 43 is turned on. For this reason, the light emitting diode 44 emits light, and an abnormal signal (for example, 1) is output from the diode 45 to the arithmetic processing unit. As described above, the abnormality detection unit 24 has a function of detecting an abnormality by determining the magnitude relationship between the output voltage of the cell block 2b and the abnormality detection voltage _VA using a photocoupler. Here, when the voltage from the threshold control unit 23 is constant, the current flowing into the base of the transistor 43 is constant. However, when the voltage from the threshold control unit becomes variable, the current flowing into the base of the transistor 43 also changes. The voltage of the cell block 2b that turns on / off the transistor 43 also changes.

  Returning to FIG. 1, the operation control unit 25 has a function of controlling the operation of the fuel cell 2. The operation control unit 25 has a function of adjusting the output power of the fuel cell 2 based on, for example, information acquired from the control device. For example, it has a function of operating the fuel cell 2 within the rated power.

  Next, the operation of the fuel cell power generator 1 according to this embodiment will be described. First, the operation of the characteristic acquisition unit 21 will be described.

  The characteristic acquisition unit 21 acquires the current-voltage characteristics of the fuel battery cell 2a from specification information, measurement, and the like. FIG. 3 is an example of a graph showing current-voltage characteristics, where the horizontal axis represents current I and the vertical axis represents voltage V. A in FIG. 3 is a current-voltage characteristic of one fuel battery cell 2a (or one cell block 2b). B in the figure indicates the current-voltage characteristics of the entire fuel cell 2, and is the same as the value obtained by accumulating all the current-voltage characteristics of the fuel cell 2a (cell block 2b). As shown in FIG. 3, in the rated operation section (250 W to 700 W), the output voltage V becomes a smooth graph with a small change rate.

The characteristic acquisition part 21 calculates the graph which shows the relationship between the output electric power W and the output voltage V of the cell block 2b using the graph shown in FIG. FIG. 4 is a graph showing the output power dependency of the output voltage V. The horizontal axis represents the output power W, and the vertical axis represents the output voltage V. As shown in FIG. 4, the characteristic acquisition unit 21 sets an abnormality detection voltage _VA that is smaller than the output voltage V by ΔV in the rated operation section. This sets abnormal detection voltage V _A dependent on the output power W, it is possible to set the abnormality detection voltage V _A in accordance with the target power W _K.

  Next, the monitoring operation of the fuel cell power generator 1 according to this embodiment will be described. FIG. 5 is a flowchart showing the monitoring operation of the fuel cell power generator 1 according to this embodiment. The control process shown in FIG. 5 is repeatedly executed at a predetermined interval from the timing when the power of the fuel cell power generator 1 is turned on, for example. Note that it is assumed that the characteristic acquisition unit 21 acquires the characteristics of the fuel cell 2 in advance before the execution of the control process shown in FIG. 5 (relation acquisition step). In consideration of ease of understanding, the monitoring operation for a predetermined cell block 2b in the fuel cell 2 will be described.

When starting the control process shown in FIG. 5, the target power acquisition unit 22 acquires the target power W _K example from the control device (target power acquisition step, S10). Thereafter, the threshold control unit 23 calculates the abnormality detection voltage V _A from the target power W _K acquired in the process of S10 and the graph shown in FIG. 4 (threshold calculation step, S12). Thereafter, the threshold control unit 23 sets the abnormality detection voltage _VA calculated in the process of S12 in the abnormality detection unit 24, and the abnormality detection unit 24 determines that the current voltage V of the cell block 2b is higher than the abnormality detection voltage _VA. It is determined whether it is larger (threshold setting step, abnormality detection step, S14). In the process of S14, when the abnormality detection unit 24 determines that the current voltage V of the cell block 2b is greater than the abnormality detection voltage _VA, no abnormality in voltage drop has occurred in the cell block 2b. Then, the operation control unit 25 performs a normal operation (S16), and the control process shown in FIG. On the other hand, in the process of S14, when the abnormality detection unit 24 determines that the current voltage V of the cell block 2b is not greater than the abnormality detection voltage _VA, an abnormality in voltage drop occurs in the cell block 2b. Therefore, the operation control unit 25 performs safety processing (S18). For example, to reduce the target power W _K itself, or cancel the operation, or an error. When the safety process ends, the control process shown in FIG. 5 ends.

This is the end of the control process shown in FIG. By executing the control process shown in FIG. 5, the abnormality detection voltage V _A is changed according to the target power W _K. For this reason, the abnormality detection voltage _VA, which is a threshold value for detecting an abnormality in voltage drop, is set to an appropriate value. Details will be described with reference to FIG. FIG. 6 is a graph in which the voltage, current, and power of the fuel cell 2a are plotted by the amount of input gas to the fuel cell 2, the vertical axis is the voltage V, current I, and power W, and the horizontal axis is the input gas amount. It is. As shown in FIG. 6, the voltage V monotonously decreases according to the amount of input gas, the current I monotonously increases according to the amount of input gas, and the electric power W increases monotonously up to a predetermined gas amount, and the amount of change thereafter. Get smaller. Here, in the case of a conventional fuel cell power generation device, a value near the minimum value of the voltage V (abnormal detection voltage V _OLD ) is set as a threshold value for detecting a voltage drop abnormality and set as a fixed value. For this reason, when the target power W _K is relatively high, the difference Y ₁ between the target output voltage V _K and the abnormality detection voltage V _OLD is small, so there is a possibility that a voltage drop abnormality may be erroneously detected due to disturbance such as noise. In addition, when the target power W _K is relatively low, the difference Y ₁ between the target output voltage V _K and the abnormality detection voltage V _OLD is large, so that there is a possibility that an abnormality in voltage drop cannot be detected appropriately.

On the other hand, in the fuel cell power generation device 1 and the fuel cell monitoring method according to the first embodiment, the output power W of the fuel cell 2 and the cell block based on the voltage / current characteristics of the fuel cell 2a by the characteristic acquisition unit 21 relationship between the output voltage V of the 2b is obtained in advance, the target power W _K of the fuel cell 2 is obtained by the target power acquisition unit 22, the target power W based on the relationship and target power W _K by the threshold control unit 23 The abnormality detection voltage _VA of the cell block 2b at _K is calculated, and the abnormality detection unit 24 detects the abnormality of the cell block 2b based on the magnitude relationship between the output voltage V of the cell block 2b and the abnormality detection voltage _VA . Thus, the abnormality detection voltage V _A is not a constant value but a value corresponding to the target power W _K of the fuel cell 2 based on the voltage-current characteristics of each of the fuel cells 2a, so that the fuel cell 2a The voltage abnormality can be determined in consideration of the characteristics. For this reason, abnormality of the voltage drop of the fuel battery cell 2a can be detected appropriately.

(Second Embodiment)
The fuel cell power generation device 1 according to the second embodiment is configured similarly to the fuel cell power generation device 1 according to the first embodiment, and a partial function of the threshold control unit 23 is different. Therefore, the second embodiment will be described with a focus on differences from the first embodiment, and a duplicate description will be omitted.

The threshold value control unit (threshold value calculation means, determination means, threshold value fluctuation stop means) 23 of the fuel cell power generation device 1 according to the present embodiment determines whether the abnormality detection voltage _VA is smaller than a predetermined threshold value X. When the detection voltage V _A is smaller than the predetermined threshold value X, there is a function of stopping the change of the abnormality detection voltage V _A and fixing it to the constant K. The predetermined threshold value X is set based on, for example, a conventional abnormality detection voltage _VOLD . Other functions are the same as those of the threshold control unit 23 of the fuel cell power generator 1 according to the first embodiment.

FIG. 7 is a flowchart showing the operation of the fuel cell power generator 1 according to this embodiment. FIG. 7 is executed by the threshold control unit 23, and is executed after the calculation (S12) of the abnormality detection voltage _VA shown in FIG. 5 and before the comparison process (S14). As shown in FIG. 7, first, the abnormality detection voltage _VA calculated in the process of S12 of FIG. 5 is input (S20). Then, the abnormality detection voltage _VA input in the process of S20 is compared with the predetermined threshold value X (determination step, S22). In the processing of S22, the abnormality when the detected voltage V _A is determined to be smaller than the predetermined threshold value X is not adopted an abnormality detection voltage V _A which is input in the process step S20 as a reference voltage for determining a voltage drop Instead, a predetermined constant K is employed (threshold change stop step, S24). Then, the control process shown in FIG. 7 ends. The constant K is set, for example, based on the conventional abnormality detection voltage V _OLD .

On the other hand, in the process of S22, when it is determined that the abnormality detection voltage _VA is not smaller than the predetermined threshold value X, the abnormality detection voltage V input in the process of S20 is used as a reference voltage for determining the voltage drop. _A is adopted, and the control process shown in FIG.

As described above, according to the fuel cell power generation device 1 according to the second embodiment, the same effect as the fuel cell power generation device 1 according to the first embodiment can be obtained, and the abnormality detection voltage V _A is set to the predetermined threshold value by the threshold control unit 23. It is determined whether or not it is smaller than X, and when it is determined that the abnormality detection voltage V _A is smaller than the predetermined threshold value X, the abnormality detection voltage V _A is fixed to a constant K. For this reason, when the information regarding the abnormality detection voltage _VA of the fuel cell 2 is inaccurate or when there is an abnormality in the communication path for transmitting information regarding the abnormality detection voltage, the change of the threshold is stopped. To avoid inappropriate monitoring.

  The present invention is not limited to the above-described embodiments.

  For example, in each of the above-described embodiments, the case where the control unit 20 and the control device of the fuel cell power generator 1 are separate has been described as an example, but may be configured integrally.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell power generation device, 2 ... Fuel cell, 2a ... Fuel cell, 2b ... Cell block, 3 ... Power conditioner, 4 ... Surplus heater, 5 ... Heat exchanger, 6 ... Water pump, 7 ... Hot water storage tank, 9 ... external load.

Claims (5)

A fuel cell power generator having a fuel cell in which a plurality of cell blocks each composed of fuel cells stacked in series are stacked in series,
Based on the voltage-current characteristics of each of the fuel cells, characteristic acquisition means for acquiring in advance the relationship between the output power of the fuel cell and the output voltage of the cell block;
Target power acquisition means for acquiring target power of the fuel cell;
Threshold calculation means for calculating an abnormality detection voltage of the cell block at the target power based on the relationship and the target power;
An anomaly detection means for detecting an anomaly of the cell block based on a magnitude relationship between the output voltage of the cell block and the anomaly detection voltage;
A fuel cell power generator comprising:   The abnormality detection means includes a light emitting element that is connected to both ends of the cell block and emits light when a voltage greater than the abnormality detection voltage is applied, and a light receiving element that constitutes a photocoupler together with the light emitting element. The fuel cell power generator according to claim 1, wherein an abnormality of the cell block is detected based on a potential. Determination means for determining whether or not the abnormality detection voltage is smaller than a predetermined threshold;
If the determination means determines that the abnormality detection voltage is smaller than a predetermined threshold value, threshold fluctuation stopping means for fixing the abnormality detection voltage to a predetermined value;
A fuel cell power generator according to claim 1 or 2. A fuel cell monitoring method for monitoring a voltage abnormality of a fuel cell configured by stacking a plurality of cell blocks made of fuel cells stacked in series in an arbitrary number,
Based on the voltage-current characteristics of each of the fuel cells, a relationship acquisition step for acquiring in advance the relationship between the output power of the fuel cell and the output voltage of the cell block;
A target power acquisition step of acquiring the target power of the fuel cell during operation of the fuel cell;
Based on the relationship acquired by the relationship acquisition step and the target power acquired by the target power acquisition step, a threshold calculation step of calculating an abnormality detection voltage of the cell block at the target power;
A threshold setting step for setting the abnormality detection voltage calculated by the threshold calculation step as a predetermined voltage of the light emitting element;
An abnormality detection step of detecting an abnormality of the cell block based on the potential of the light receiving element;
A fuel cell monitoring method comprising: A determination step of determining whether or not the abnormality detection voltage calculated by the threshold calculation step is smaller than a predetermined threshold;
When it is determined by the determination step that the abnormality detection voltage is smaller than a predetermined threshold value, a threshold value fluctuation stopping step of fixing the abnormality detection voltage to a predetermined value;
A fuel cell monitoring method according to claim 4.

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