Fuel cell system, control device, control method

Abstract

This technology provides a way to suppress the performance degradation of fuel cells. [Solution] A fuel cell system 1 according to one embodiment comprises a solid polymer fuel cell module 10 that generates electricity by chemically reacting hydrogen and oxygen, a water quality meter 50 that acquires information on the concentration of sulfate ions contained in the generated water CW produced when the fuel cell module 10 generates electricity, and a control device 20 that controls the refresh operation of the fuel cell module 10. The control device 20 controls the frequency of the refresh operation of the fuel cell module 10 based on the information acquired by the water quality meter 50.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system and the like.

Background Art

[0002] For example, a technique for avoiding the operating state of a fuel cell from a region where a decrease in the performance of the fuel cell is predicted is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, there is room for improvement in the technology for suppressing a decrease in the performance of a fuel cell.

[0005] [[ID=3৮]] Therefore, in view of the above problems, an object is to provide a technology capable of suppressing a decrease in the performance of a fuel cell.

Means for Solving the Problems

[0006] To achieve the above object, in one embodiment of the present disclosure, a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen, a water quality meter that acquires information regarding the concentration of ions contained in the generated water generated during power generation of the fuel cell, a control device that controls the refresh operation of the fuel cell, and the control device controls the frequency of the refresh operation based on the information acquired by the water quality meter, The refresh operation includes a first refresh operation in which the stopping of the fuel cell, restarting the fuel cell, and operating the fuel cell at an output relatively high compared to a predetermined standard are performed as a series of operations. The control device causes the fuel cell to perform the first refresh operation at predetermined intervals. and In conjunction with the first refresh operation of the fuel cell at predetermined intervals, the first refresh operation of the fuel cell is performed in accordance with the information obtained by the water quality meter. A fuel cell system will be provided.

[0007] In other embodiments of this disclosure, A control device for controlling the refresh operation of a fuel cell system, comprising a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that acquires information on the concentration of ions contained in the generated water produced during the power generation of the fuel cell, wherein the control device controls the refresh operation of the fuel cell. Based on the information obtained by the water quality meter, the frequency of the refresh operation is controlled. The refresh operation includes a first refresh operation in which the stopping of the fuel cell, restarting the fuel cell, and operating the fuel cell at an output relatively high compared to a predetermined standard are performed as a series of operations. The control device causes the fuel cell to perform the first refresh operation at predetermined intervals. and In conjunction with the first refresh operation of the fuel cell at predetermined intervals, the first refresh operation of the fuel cell is performed in accordance with the information obtained by the water quality meter. A control device is provided.

[0008] Furthermore, in yet another embodiment of this disclosure, A control method performed by a control device that controls the refresh operation of a fuel cell system, comprising a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that acquires information on the concentration of ions contained in the generated water produced during the power generation of the fuel cell, wherein Based on the information obtained by the water quality meter, the frequency of the refresh operation is controlled. The refresh operation includes a first refresh operation in which the stopping of the fuel cell, restarting the fuel cell, and operating the fuel cell at an output relatively high compared to a predetermined standard are performed as a series of operations. The control device causes the fuel cell to perform the first refresh operation at predetermined intervals. and In conjunction with the first refresh operation of the fuel cell at predetermined intervals, the first refresh operation of the fuel cell is performed in accordance with the information obtained by the water quality meter. A control method is provided. [Effects of the Invention]

[0009] According to the above-described embodiment, the performance degradation of the fuel cell can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram showing the configuration of the first example of a fuel cell system. [Figure 2] This figure shows an example of the relationship between sulfate ion concentration and electrical conductivity in generated water. [Figure 3] This figure shows an example of the relationship between sulfate ion concentration and hydrogen ion concentration (pH) in the generated water. [Figure 4] This diagram illustrates a first example of a control method for stopping, restarting, and refreshing a fuel cell module. [Figure 5] This flowchart schematically shows the first example of the control process related to stopping, restarting, and refreshing a fuel cell module. [Figure 6]This is a diagram for explaining a second example of a control method for the stop / restart refresh operation of a fuel cell module. [Figure 7] This is a flowchart schematically showing a second example of a control process for the stop / restart refresh operation of a fuel cell module. [Figure 8] This is a diagram showing the configuration of a second example of a fuel cell system. [Figure 9] This is a diagram for explaining a third example of a control method for the stop / restart refresh operation of a fuel cell module. [Figure 10] This is a diagram showing the configuration of a third example of a fuel cell system. [Figure 11] This is a diagram for explaining a fourth example of a control method for the stop / restart refresh operation of a fuel cell module.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments will be described with reference to the drawings.

[0012] [First Example of Fuel Cell System] Referring to FIGS. 1 to 3, a first example of a fuel cell system 1 according to this embodiment will be described.

[0013] As shown in FIG. 1, the fuel cell system 1 outputs electric power Pout and supplies it to an external load 100. The fuel cell system 1 is, for example, a pure hydrogen type fuel cell system that stores hydrogen as fuel and generates electricity directly from hydrogen.

[0014] ​​​Furthermore, fuel cell system 1 may be a fuel cell system that generates a reformed gas containing hydrogen gas by reforming methane gas or city gas as fuel, and generates electricity from the reformed gas.

[0016] The fuel cell system 1 includes a fuel cell module 10, a control device 20, an energy storage device 30, a gas-liquid separator 40, and a water quality meter 50.

[0017] The fuel cell module 10 generates electricity (i.e., performs power generation) by chemically reacting hydrogen and oxygen. The fuel cell module 10 comprises a fuel cell stack 11, an output adjustment unit 12, a flow rate adjustment unit 13, and a control unit 14.

[0018] The fuel cell stack 11 includes multiple unit cells (fuel cell cells) composed of an air electrode, a fuel electrode, and an electrolyte, and the multiple fuel cell cells are connected in series inside the fuel cell stack 11. The fuel cell stack 11 generates electricity by chemically reacting hydrogen SH supplied to the fuel electrode with oxygen contained in the air SA supplied to the air electrode.

[0019] The fuel cell stack 11 is, for example, a polymer electrolyte fuel cell (PEFC). In this case, the fuel cell stack 11 has a stack structure in which a large number of polymer electrolyte fuel cell unit cells (fuel cell cells) are stacked.

[0020] In a fuel cell stack 11 as a polymer electrolyte fuel cell, the fuel cell cell comprises a membrane electrode assembly (MEA) including a polymer electrolyte membrane and a pair of electrodes provided on both sides of the polymer electrolyte membrane. The polymer electrolyte membrane selectively transports hydrogen ions. The polymer electrolyte membrane is formed from, for example, perfluorosulfonic acid (PFSA) polymer. Each of the pair of electrodes is formed from a porous material. Each of the pair of electrodes has, for example, a catalyst layer mainly composed of carbon powder supporting a platinum-based metal catalyst (electrode catalyst), and a gas diffusion layer that has both permeability and electronic conductivity. Furthermore, the fuel cell cell has a pair of separators that sandwich the membrane electrode assembly (MEA) from both sides.

[0021] The fuel cell stack 11 emits exhaust gas EX. Exhaust gas EX is a mixture of exhaust gas containing hydrogen that remains unreacted after a chemical reaction, emitted from the fuel electrode of the fuel cell, and exhaust gas from which oxygen has been consumed from the air SA emitted from the air electrode of the fuel cell.

[0022] Furthermore, the exhaust gas containing hydrogen that remains unreacted and is discharged from the fuel electrode of the fuel cell, and the exhaust gas from which oxygen has been consumed from the air SA discharged from the air electrode of the fuel cell, may be mixed outside the fuel cell module 10.

[0023] The output adjustment unit 12 adjusts the power output from the fuel cell stack 11 to the outside of the fuel cell module 10. For example, the output adjustment unit 12 boosts the output power p1 generated by the fuel cell stack 11 and outputs a predetermined output power P1 to the outside of the fuel cell module 10. The output adjustment unit 12 includes, for example, a DC-DC converter (Direct Current to Direct Current Converter).

[0024] The flow rate adjustment unit 13 adjusts the flow rates of hydrogen SH and air SA supplied from outside the fuel cell module 10. The flow rate adjustment unit 13 supplies the adjusted hydrogen SHs and air SAs to the fuel cell stack 11. The flow rate adjustment unit 13 includes, for example, control valves for adjusting the flow rate or pressure of hydrogen SH, and control valves or boosters for adjusting the flow rate or pressure of air SA.

[0025] The control unit 14 controls the fuel cell module 10 based on control commands from an external control device 20. For example, the control unit 14 controls the fuel cell stack 11, the output adjustment unit 12, and the flow rate adjustment unit 13.

[0026] The control device 20 performs control related to the fuel cell module 10. The control device 20 is mainly composed of a computer including, for example, a CPU (Central Processing Unit), a memory device, an auxiliary storage device, and an interface device for input / output to the outside. Alternatively, the control device 20 may be a PLC (Programmable Logic Controller).

[0027] The control device 20 can control the fuel cell module 10 through the control unit 14 by transmitting control commands to the control unit 14 of the fuel cell module 10. The control device 20 can also acquire data regarding various states of the fuel cell module 10 from the control unit 14.

[0028] The control device 20 includes a timer 21 for measuring time. The timer 21 may be a hardware timer or a software timer implemented by a program installed on the control device 20. For example, the control device 20 measures time by receiving an interrupt from the timer 21. Alternatively, the control device 20 may measure time by sequentially referencing the count value of the timer 21.

[0029] Furthermore, the functions of the timer 21 may be located outside the control device 20.

[0030] For example, the control device 20 controls the fuel cell module 10 and causes it to perform a refresh operation to restore the power generation performance of the fuel cell stack 11.

[0031] The refresh operation of the fuel cell module 10 includes, for example, a refresh operation in which the fuel cell stack 11 is stopped and restarted, and then a high-load operation is performed that outputs a relatively high power p1 (hereinafter referred to as "stop-restart refresh operation"). During the stop-restart refresh operation, the supply of hydrogen SHs and air SAs to the fuel cell stack 11 is stopped while the fuel cell stack 11 is stopped. For example, the stop-restart refresh operation of the fuel cell module 10 is performed for a period of 10 minutes or less, and the high-load operation after the restart of the fuel cell stack 11 is performed at an output of 80% or more of the maximum output.

[0032] For example, hydrogen peroxide and hydroxyl radicals contained in hydrogen SHs can accelerate the decomposition of the polymer electrolyte membrane in the fuel cell, and the decomposed resin components (e.g., fluororesin or sulfonic acid) may adhere to the catalyst. In this case, the effective surface area of ​​the catalyst decreases due to the decomposition products of the polymer electrolyte membrane that adhere to the catalyst in the fuel cell, and the amount of hydrogen peroxide generated in the fuel cell increases. As a result, a vicious cycle occurs in which the decomposition of the polymer electrolyte membrane in the fuel cell is further accelerated in accordance with the increase in the amount of hydrogen peroxide generated. Therefore, the performance of the fuel cell stack 11 may be accelerated.

[0033] In response to this, when the control device 20 causes the fuel cell module 10 to perform a stop-restart refresh operation, the decomposition products of the polymer electrolyte membrane attached to the catalyst of the fuel cell are washed away and discharged to the outside of the fuel cell stack 11 along with the liquid components contained in the exhaust gas EX. This restores the effective surface area of ​​the catalyst in the fuel cell, and as a result, restores the power generation performance of the fuel cell stack 11.

[0034] Furthermore, the refresh operation of the fuel cell module 10 includes, for example, a refresh operation in which the fuel cell stack 11 continuously performs high-load operation, which outputs a relatively high output power p1, and low-load operation, which outputs a relatively low output power p1, in a time series (hereinafter referred to as "load change refresh operation"). In load change refresh operation, for example, under the control of the control device 20, the load state of the fuel cell stack 11 changes in the order of high load, low load, high load at regular intervals. Alternatively, in load change refresh operation, under the control of the control device 20, the load state of the fuel cell stack 11 may change in the order of low load, high load, low load at regular intervals.

[0035] For example, when the fuel cell stack 11 is operated under high load for a long period of time, the air inlet of the fuel cell dries out, and excessive moisture occurs at the exhaust outlet of the fuel cell due to generated water, which may obstruct the flow of gas (exhaust). In this case, power generation is suppressed at the dry area at the air SAs inlet and the excessively humid area at the exhaust outlet of the fuel cell, causing the load on other parts to increase, and the areas with increased load become hot. As a result, the decomposition of the polymer electrolyte membrane is accelerated at the dry and hot areas of the fuel cell. When the decomposition of the polymer electrolyte membrane is accelerated, the decomposed resin components (e.g., fluororesin and sulfonic acid) adhere to the catalyst, and the adhesion of the decomposed products to the catalyst inhibits the chemical reaction, causing the voltage of the fuel cell to decrease and the current to increase, thus increasing the load on the fuel cell. As a result, the fuel cell becomes hotter with the increase in load, creating a vicious cycle in which the decomposition of the polymer electrolyte membrane in the fuel cell is further accelerated. Therefore, the performance of the fuel cell stack 11 may deteriorate.

[0036] In contrast, when the control device 20 causes the fuel cell module 10 to perform a load fluctuation refresh operation, the change in load on the fuel cell can suppress drying and over-humidification in the fuel cell. Therefore, the decomposition of the polymer electrolyte membrane caused by drying or over-humidification of the fuel cell can be suppressed, and the decrease in the power generation performance of the fuel cell stack 11 can be suppressed.

[0037] Furthermore, the functions of the control device 20 may be provided outside the fuel cell system 1. For example, the functions of the control device 20 may be provided by an external server device that is communicatively connected to the fuel cell system 1.

[0038] The energy storage device 30 supplies the starting power to the fuel cell module 10 when starting up the fuel cell module 10. The energy storage device 30 includes, for example, a lithium-ion capacitor (LIC) or an electric double-layer capacitor. The energy storage device 30 may also include a lithium-ion battery (LIB) or a solid-state battery (SSB).

[0039] The energy storage device 30 can store (charge) the power of the fuel cell module 10 after it has started operating, or store power from an external power source (not shown) (for example, an AC power grid). The energy storage device 30 may also supply power to the external load 100 as needed. For example, if the output power P1 of the fuel cell module 10 is in excess of the requirements of the external load 100, the surplus power Ps is stored. In this case, the power Pout output from the fuel cell system 1 is the output power P1 of the fuel cell module 10 minus the power Ps stored in the energy storage device 30 (Pout = P1 - Ps). Also, if the output power P1 of the fuel cell module 10 is insufficient to meet the requirements of the external load 100, the insufficient power Ps is discharged. In this case, the power Pout output from the fuel cell system 1 is the sum of the output power P1 of the fuel cell module 10 and the power Ps discharged from the energy storage device 30 (Pout = P1 + Ps).

[0040] The gas-liquid separator 40 separates the liquid component contained in the exhaust gas EX. The liquid component contained in the exhaust gas EX is water (hereinafter referred to as "generated water") produced by the chemical reaction between hydrogen and oxygen in the fuel cell stack 11. The gas-liquid separator 40 discharges the generated water CW and exhaust gas EXa, from which the liquid component (generated water CW) has been removed from the exhaust gas EX, and the exhaust gas EXa and generated water CW are discharged to the outside of the fuel cell system 1.

[0041] Water quality meter 50 is a device for measuring the water quality of the generated water CW.

[0042] For example, water quality meter 50 detects sulfate ions (SO4) contained in the generated water CW. 2- Information regarding the concentration of ) is obtained. The water quality meter 50 is, for example, an electrical conductivity meter capable of measuring the electrical conductivity of the generated water CW. This is because, as shown in Figure 2, a certain correlation can be found between the electrical conductivity of the generated water CW and the concentration of sulfate ions contained in the generated water CW. Alternatively, the water quality meter 50 may be a hydrogen ion concentration meter capable of measuring the hydrogen ion concentration (pH). This is because, as shown in Figure 3, a certain correlation can be found between the hydrogen ion concentration (pH) of the generated water CW and the concentration of sulfate ions. Alternatively, the water quality meter 50 may be an ion chromatograph capable of separating, detecting, and quantitatively analyzing sulfate ions contained in the generated water CW.

[0043] Furthermore, if the fuel cell system 1 uses reformed gas, the reformed gas contains carbon dioxide (CO2), and as a result, the generated water CW may contain dissolved carbon dioxide originating from the reformed gas. Therefore, when a water quality meter 50 that indirectly obtains information representing the sulfate ion concentration, such as an electrical conductivity meter or a hydrogen ion concentration meter, is used, the correlation between the information obtained by the water quality meter 50 and the actual sulfate ion concentration contained in the generated water CW must be defined taking into account the influence of carbon dioxide dissolved in the generated water CW.

[0044] The following explanation will focus on the case where the electrical conductivity of the generated water CW is measured using a water quality meter 50.

[0045] Information regarding the concentration of sulfate ions in the generated water CW, output from the water quality meter 50, is received by the control device 20 via a predetermined communication line, such as a one-to-one communication line or a local network.

[0046] Furthermore, the water quality meter 50 may measure the water quality of the liquid component (generated water) contained in the exhaust gas EX before it passes through the gas-liquid separator 40.

[0047] [First example of a fuel cell system control method] Referring to Figures 4 and 5, a first example of a control method for the fuel cell system 1 will be described. In this example, the explanation will focus on the case where the electrical conductivity of the generated water CW is measured by the water quality meter 50.

[0048] <Overview of the control method> Figure 4 illustrates a first example of a control method for stopping, restarting, and refreshing the fuel cell module 10. Specifically, Figure 4 shows the time change of the measured electrical conductivity EC of the generated water CW, as measured by the water quality meter 50.

[0049] In Figure 4, the open triangles represent the timing of regularly scheduled stop-restart refresh operations, while the filled triangles represent the timing of additional stop-restart refresh operations performed separately from the regularly scheduled ones. The same applies to Figures 9 and 11, which will be discussed later.

[0050] As shown in Figure 4, the control device 20 controls the fuel cell module 10 and causes it to perform a stop-restart refresh operation at regular intervals (hereinafter referred to as the "refresh cycle") T0. For example, the refresh cycle T0 is predetermined within the range of 6 to 48 hours. Specifically, the refresh cycle T0 is, for example, 12 hours. This allows the control device 20 to periodically restore the power generation performance of the fuel cell stack 11.

[0051] When the fuel cell module 10 is stopped, restarted, and refreshed, the decomposition products of the polymer electrolyte membrane that had adhered to the catalyst of the fuel cell cell are washed away, as described above. Therefore, after the start of the stop-restart-refresh operation of the fuel cell module 10, the sulfate ion concentration of the generated water CW temporarily increases, reaching a relatively high peak value, and then decreases to a relatively low base value. As a result, as shown in Figure 4, the measured value of the electrical conductivity EC of the generated water CW, which has a certain correlation with the sulfate ion concentration of the generated water CW, temporarily increases, reaching a relatively high peak value, and then decreases to a relatively low base value.

[0052] When the sulfate ion concentration of the generated water CW increases due to the stop-restart refresh operation of the fuel cell module 10, and this concentration reaches a level relatively high compared to a predetermined standard, it is presumed that a relatively large amount of decomposition products of the polymer electrolyte membrane were attached to the catalyst of the fuel cell. Furthermore, it is presumed that a relatively large amount of decomposition products of the polymer electrolyte membrane remain attached to the catalyst of the fuel cell.

[0053] Therefore, the control device 20 performs an additional stop-restart refresh operation of the fuel cell module 10 if the electrical conductivity EC of the generated water CW rises to or above the threshold ECth11 during the stop-restart refresh operation of the fuel cell module 10. The threshold ECth11 is predetermined, for example, based on experimental results regarding the relationship between the concentration of sulfate ions contained in the generated water CW and the amount of decomposition products of the polymer electrolyte membrane remaining attached to the catalyst of the fuel cell. Alternatively, the threshold ECth11 may be predetermined based on experimental results regarding the relationship between the electrical conductivity of the generated water CW and the amount of decomposition products of the polymer electrolyte membrane remaining attached to the catalyst of the fuel cell. This allows the control device 20 to more appropriately reduce the amount of decomposition products of the polymer electrolyte membrane attached to the catalyst of the fuel cell, and as a result, the power generation performance of the fuel cell stack 11 can be restored more appropriately. Therefore, the lifespan of the fuel cell stack 11 can be extended.

[0054] For example, as shown in Figure 4, following the third scheduled stop-restart refresh operation from the left, the electrical conductivity EC of the generated water CW rises to above the threshold ECth11. Therefore, the control device 20 performs an additional stop-restart refresh operation of the fuel cell module 10 (first time). In this case, the peak value of the electrical conductivity EC of the generated water CW following the first additional stop-restart refresh operation is below the threshold ECth11. Therefore, the control device 20 determines that the decomposition products of the polymer electrolyte membrane that were attached to the catalyst of the fuel cell cell have been sufficiently washed away, and does not perform any further additional stop-restart refresh operations, instead waiting for the next scheduled stop-restart refresh operation.

[0055] Furthermore, as shown in Figure 4, following the sixth scheduled stop-restart refresh operation from the left, the electrical conductivity EC of the generated water CW rises to above the threshold ECth11. Therefore, the control device 20 performs an additional stop-restart refresh operation of the fuel cell stack 11 (1st time). In this case, following the first additional stop-restart refresh operation, the electrical conductivity EC of the generated water CW rises to above the threshold ECth11. Therefore, the control device 20 determines that the decomposition products of the polymer electrolyte membrane attached to the catalyst of the fuel cell have not yet been sufficiently washed away, and performs an additional stop-restart refresh operation of the fuel cell module 10 (2nd time). In this case, the peak value of the electrical conductivity EC of the generated water CW resulting from the second additional stop-restart refresh operation is below the threshold ECth11. Therefore, the control device 20 determines that the decomposition products of the polymer electrolyte membrane attached to the catalyst of the fuel cell have been sufficiently washed away, and does not perform any further additional stop-restart refresh operations, instead waiting for the next scheduled stop-restart refresh operation.

[0056] Furthermore, the time required to perform a stop-restart refresh operation of the fuel cell module 10 is very short compared to the refresh cycle T0. Therefore, even if multiple additional stop-restart refresh operations are performed, they will not overlap with the timing of the next scheduled stop-restart refresh operation.

[0057] Thus, in this example, the control device 20 can cause the fuel cell module 10 to perform stop, restart, and refresh operations more appropriately.

[0058] <Control Processing> Figure 5 is a flowchart illustrating a schematic example of the control process for stopping, restarting, and refreshing the fuel cell module 10.

[0059] This flowchart is started when the fuel cell module 10 is powered up and is executed repeatedly while the fuel cell module 10 is in operation.

[0060] As shown in Figure 5, in step S102, the control device 20 initializes the timer 21.

[0061] Once the process in step S102 is complete, the control device 20 proceeds to step S104.

[0062] In step S104, the control device 20 determines whether the refresh period T0 has elapsed based on the output of the timer 21, with the initialization of the timer 21 as the reference point. If the refresh period T0 has elapsed, the control device 20 proceeds to step S106. If the refresh period T0 has not elapsed, the process in step S104 is repeated until the refresh period T0 has elapsed.

[0063] In step S106, the control device 20 initializes the timer 21.

[0064] Once the process in step S106 is completed, the control device 20 proceeds to step S108.

[0065] In step S108, the control device 20 controls the fuel cell module 10 and causes it to perform a stop-refresh operation at regular intervals.

[0066] Once the process in step S108 is complete, the control device 20 proceeds to step S110.

[0067] In step S110, the control device 20 determines whether the peak value ECp of the electrical conductivity EC, which occurs as a result of performing a stop-restart refresh operation, is greater than or equal to the threshold ECth11. If the peak value ECp of the electrical conductivity EC is greater than or equal to the threshold ECth11, the control device 20 proceeds to step S112. Otherwise, i.e., if the peak value ECp of the electrical conductivity EC is less than the threshold ECth11, the control device 20 returns to step S104 and repeats the processing from step S104 onward.

[0068] Alternatively, instead of performing the process in step S110, the control device 20 may sequentially determine whether the measured value of electrical conductivity EC is equal to or greater than the threshold ECth11, in parallel with the execution of the stop-restart-refresh operation in step S108. In this case, if the measured value of electrical conductivity EC becomes equal to or greater than the threshold ECth11 during the stop-restart-refresh operation period, the control device 20 proceeds to step S112; otherwise, it returns to step S104.

[0069] In step S112, the control device 20 controls the fuel cell module 10 and causes it to perform an additional stop-restart refresh operation.

[0070] Once the process in step S112 is complete, the control device 20 returns to step S110.

[0071] [Second example of a fuel cell system control method] A second example of a control method for the fuel cell system 1 will be described with reference to Figures 6 and 7.

[0072] In the following explanation, we will focus on the differences between this example and the first example of the control method described above (Figures 4 and 5).

[0073] <Overview of the control method> Figure 6 illustrates a second example of a control method for stopping, restarting, and refreshing the fuel cell module 10. Specifically, Figure 6 shows the macroscopic time variation of the measured electrical conductivity EC of the generated water CW, as measured by the water quality meter 50.

[0074] In this example, the macroscopic time change of the measured electrical conductivity EC of the generated water CW refers to the time change of the measured electrical conductivity EC, excluding the temporary increases and decreases in electrical conductivity EC associated with the refresh operation of the fuel cell module 10. In other words, it refers to the time change of the measured electrical conductivity EC under normal operating conditions, different from the refresh operation of the fuel cell module 10. The normal operating conditions of the fuel cell module 10 refer to, for example, the operating conditions for supplying power to an external load 100 in response to the demands of an external load. Hereinafter, the sulfate ion concentration and electrical conductivity EC, excluding the temporary increases and decreases in sulfate ion concentration and electrical conductivity EC associated with the refresh operation of the fuel cell module 10, may be referred to as the "base value of sulfate ion concentration" and the "base value of electrical conductivity EC," respectively.

[0075] The polymer electrolyte membrane in the fuel cell deteriorates as the cumulative operating time of the fuel cell stack 11 from the start of use (hereinafter referred to as "cumulative operating time") increases, and the amount of decomposition products increases with this deterioration. Therefore, the base value of sulfate ion concentration increases as the cumulative operating time of the fuel cell stack 11 increases. As a result, as shown in Figure 6, the base value of the electrical conductivity EC of the generated water CW, which has a certain correlation with the base value of the sulfate ion concentration of the generated water CW, also increases as the cumulative operating time of the fuel cell stack 11 increases.

[0076] Therefore, the control device 20 shortens the cycle of the stop-restart refresh operation as the base value of the electrical conductivity EC of the generated water CW increases. Thereby, the control device 20 can increase the frequency of the stop-restart refresh operation in accordance with the progress of the deterioration of the fuel cell stack 11. As a result, the performance deterioration of the fuel cell stack 11 can be suppressed, and the long life of the fuel cell system 1 can be achieved.

[0077] For example, as shown in FIG. 6, when the base value of the electrical conductivity EC of the generated water CW is less than the threshold value ECth21, the control device 20 sets the cycle of the stop-restart refresh operation of the fuel cell module 10 to the refresh cycle T1. The refresh cycle T1 is, for example, 12 hours. Further, when the base value of the electrical conductivity EC of the generated water CW is equal to or greater than the threshold value ECth21 and less than the threshold value ECth22 (>ECth21), the control device 20 sets the cycle of the stop-restart refresh operation of the fuel cell module 10 to the refresh cycle T2 (<T1). The refresh cycle T2 is, for example, 8 hours. Further, when the base value of the electrical conductivity EC of the generated water CW is equal to or greater than the threshold value ECth22 and less than the threshold value ECth23, the control device 20 sets the cycle of the stop-restart refresh operation of the fuel cell module 10 to the refresh cycle T3 (<T2). The refresh cycle T3 is, for example, 6 hours. Further, when the base value of the electrical conductivity EC of the generated water CW is equal to or greater than the threshold value ECth23, the control device 20 sets the cycle of the stop-restart refresh operation of the fuel cell module 10 to the refresh cycle T4 (<T3). The refresh cycle T4 is, for example, 4 hours.

[0078] <Control Process> FIG. 7 is a flowchart schematically showing a second example of the control process for the stop-restart refresh operation of the fuel cell module 10. FIG. 7 includes a flowchart of FIG. 7A schematically showing a specific example of the control process for causing the fuel cell module 10 to execute the stop-restart refresh operation, and a flowchart of FIG. 7B schematically showing a specific example of the process for setting the cycle of the stop-restart refresh operation of the fuel cell module 10.

[0079] The flowchart in Figure 7A is started, for example, when the fuel cell module 10 is started, and is repeatedly executed while the fuel cell module 10 is in operation. The flowchart in Figure 7B is also repeatedly executed, for example, while the fuel cell module 10 is in operation.

[0080] As shown in Figure 7A, step S202 is the same as step S102 in Figure 5, so its explanation is omitted.

[0081] Once the process in step S202 is complete, the control device 20 proceeds to step S204.

[0082] In step S204, the control device 20 determines, based on the output of the timer 21, whether the currently set refresh period Tx (x=1,2,3,4) has elapsed, with the timer 21 initialization as the reference point. If the refresh period Tx has elapsed, the control device 20 proceeds to step S206. If the refresh period Tx has not elapsed, the process in step S204 is repeated until the refresh period Tx has elapsed.

[0083] Steps S206 and S208 are the same as steps S106 and S108 in Figure 5, so their explanation is omitted.

[0084] Once the processing in step S208 is complete, the process returns to step S204.

[0085] As shown in Figure 7B, in step S210, the control device 20 determines whether or not a stop-restart refresh operation of the fuel cell module 10 is in progress. If the stop-restart refresh operation of the fuel cell module 10 is not in progress, the control device 20 proceeds to step S212. If it is in progress, the process of this flowchart is terminated.

[0086] In step S212, the control device 20 determines whether the stop-restart refresh operation cycle of the fuel cell module 10 is currently set to the refresh cycle T4. If the refresh cycle T4 is not currently set, the control device 20 proceeds to step S214; if it is currently set, it terminates the processing of this flowchart.

[0087] In step S214, the control device 20 reads a threshold ECth2x corresponding to the currently set refresh period Tx from its predetermined memory area. The threshold ECth2x corresponding to the currently set refresh period Tx is the threshold ECth2x that defines the upper limit of the range of electrical conductivity EC of the generated water CW to which the currently set refresh period Tx is applied. Specifically, the threshold ECth21 corresponds to refresh period T1, the threshold ECth22 corresponds to refresh period T2, and the threshold ECth23 corresponds to refresh period T3.

[0088] Once the process in step S214 is completed, the control device 20 proceeds to step S216.

[0089] In step S216, the control device 20 uses the threshold ECth2x read in step S214 to determine whether the measured value of the electrical conductivity EC of the generated water CW is greater than or equal to the threshold ECth2x. If the measured value of the electrical conductivity EC of the generated water CW is greater than or equal to the threshold ECth2x, the control device 20 proceeds to step S218. If it is less than the threshold ECth2x, the control device 20 terminates the process in this flowchart.

[0090] In step S218, the control device 20 sets the stop-restart-refresh operation cycle to be shortened by one step from the current refresh cycle Tx. Specifically, if the current refresh cycle T1 is set, the control device 20 changes the setting to refresh cycle T2; if the current refresh cycle T2 is set, it changes the setting to refresh cycle T3; and if the current refresh cycle T3 is set, it changes the setting to refresh cycle T4.

[0091] As a result, the settings in step S218 are reflected in the processing of step S204 in the flowchart of Figure 7A. Therefore, the control device 20 can shorten the stop-restart-refresh cycle in accordance with the increase in the measured value of the electrical conductivity EC of the generated water CW when no stop-restart-refresh operation is being performed, i.e., the base value of the electrical conductivity EC of the generated water CW.

[0092] Once the process in step S218 is complete, the control device 20 terminates the flowchart process.

[0093] [Second example of a fuel cell system] Referring to Figure 8, a second example of the fuel cell system 1 according to this embodiment will be described.

[0094] In the following examples, components identical to or corresponding to those in the first example (Figure 1) above will be denoted by the same reference numerals. The explanation will focus on the differences from the first example, and explanations of components identical to or corresponding to the first example may be omitted.

[0095] Figure 8 shows the configuration of a second example of fuel cell system 1.

[0096] In this example, the configuration of the fuel cell module 10 may be the same as in the first example (Figure 1) described above. Therefore, the illustration of the configuration of the fuel cell module 10 is omitted, and the description in Figure 1 is used instead. Also, in this example, the illustration of the energy storage device 30 and the external load 100 is omitted. The same applies to the third example of the fuel cell system 1 (Figure 10) below.

[0097] As shown in Figure 8, the fuel cell system 1 in this example differs from the first example described above mainly in that it includes multiple (four in this example) fuel cell modules 10.

[0098] Furthermore, the number of fuel cell modules 10 included in fuel cell system 1 may be two, three, or five or more. The same applies to the third example of fuel cell system 1 described below.

[0099] Multiple fuel cell modules 10 are connected in parallel to an external load 100, and the sum of the output power P1 of each of the multiple fuel cell modules 10 is output to the external load 100.

[0100] The control device 20 controls each of the multiple fuel cell modules 10 by outputting control commands to the respective control units 14 of each of the multiple fuel cell modules 10.

[0101] A gas-liquid separator 40 is provided for each of the fuel cell modules 10. In other words, the fuel cell system 1 includes a number of gas-liquid separators 40 equal to the number of fuel cell modules 10.

[0102] A water quality meter 50 is provided for each of the multiple gas-liquid separators 40 and measures the water quality of the generated water CW discharged from the target gas-liquid separator 40. In other words, the fuel cell system 1 includes multiple water quality meters 50, the same number as the fuel cell modules 10 and the gas-liquid separators 40.

[0103] [Third example of a fuel cell system control method] Referring to Figure 9, a third example of a control method for the fuel cell system 1 will be described.

[0104] In the following example, we will focus on the differences between the first example (Figures 4 and 5) and the second example (Figures 6 and 7) of the control method described above, assuming the fuel cell system 1 shown in Figure 8.

[0105] <Overview of the control method> Figure 9 illustrates a third example of a control method for stopping, restarting, and refreshing the fuel cell module 10. Specifically, Figure 9 shows the time variation of the measured electrical conductivity EC of the generated water CW, measured by each of the four water quality meters 50, and includes Figures 9A to 9D corresponding to each of the four water quality meters 50.

[0106] As shown in Figure 9, in this example, the control device 20 causes each of the multiple fuel cell modules 10 to perform a stop-restart refresh operation at each refresh cycle T0, similar to the first example of the control method described above. This allows the control device 20 to periodically restore the power generation performance of the fuel cell stack 11 for each of the multiple fuel cell modules 10.

[0107] Furthermore, in this example, the control device 20 is configured so that the timing of periodic stop-restart refresh operations is different for each of the multiple fuel cell modules 10. This allows the control device 20 to perform a stop-restart refresh operation on one fuel cell module 10 while continuing the normal operation of (N-1) of the N fuel cell modules 10, for example, when the fuel cell system 1 includes N fuel cell modules 10. Therefore, the control device 20 can maintain power supply to the external load 100 with the (N-1) fuel cell modules 10 and sequentially perform stop-restart refresh operations on all fuel cell modules 10. For example, the order in which stop-restart refresh operations are performed on N fuel cell modules 10 is predetermined, and the control device 20 performs a stop-restart refresh operation on one target fuel cell module 10 at intervals of refresh cycle T0 divided by N (=T0 / N) according to that order. In this case, the time difference in the timing of stop-restart refresh operations between the k-th (k=1,···,N-1) fuel cell module 10 and the (k+1)-th fuel cell module 10 is the refresh period T0 divided by N (=T0 / N).

[0108] Furthermore, in this example, similar to the first example of the control method described above, the control device 20 additionally performs a stop-restart refresh operation of the fuel cell module 10 if the electrical conductivity EC of the generated water CW rises to a threshold ECth11 or higher during the stop-restart refresh operation of the fuel cell module 10. This allows the control device 20 to more appropriately reduce the amount of decomposition products of the polymer electrolyte membrane attached to the catalyst of the fuel cell cell, and as a result, the power generation performance of the fuel cell stack 11 can be more appropriately restored. Therefore, the lifespan of the fuel cell stack 11 can be extended.

[0109] For example, as shown in Figure 9B, the electrical conductivity EC of the generated water CW rises to above the threshold ECth11 following the execution of a stop-restart refresh operation (see the dashed circle in the figure). Therefore, the control device 20 performs an additional stop-restart refresh operation of the fuel cell module 10 (first time). In this case, the peak value of the electrical conductivity EC of the generated water CW following the first additional stop-restart refresh operation is below the threshold ECth11. Therefore, the control device 20 determines that the decomposition products of the polymer electrolyte membrane that were attached to the catalyst of the fuel cell cell have been sufficiently washed away, and does not perform any further additional stop-restart refresh operations, instead waiting for the next scheduled stop-restart refresh operation.

[0110] Furthermore, the time required to perform a stop-restart refresh operation of the fuel cell module 10 is usually very short compared to the time difference until the next scheduled stop-restart refresh operation of the fuel cell module 10 (for example, the refresh cycle T0 divided by N). Therefore, even if multiple additional stop-restart refresh operations are performed, they will not overlap with the timing of the next scheduled stop-restart refresh operation of the fuel cell module 10.

[0111] Thus, in this example, the control device 20 can more appropriately perform stop, restart, and refresh operations for each of the multiple fuel cell modules 10.

[0112] <Control Processing> In this example, the control process is implemented by the control device 20 for each of the multiple fuel cell modules 10 using a flowchart (Figure 5) similar to the first example of the control method described above.

[0113] However, the control device 20 varies the timing of the start of the flowchart processing for each of the multiple fuel cell modules 10, in accordance with a predetermined sequence of periodic stop-restart refresh operations. For example, after the startup of N fuel cell modules 10 is complete, the flowchart processing for the first fuel cell module 10 starts immediately, and then, after a time equal to the refresh cycle T0 divided by N has elapsed, the flowchart processing for the second, third, ..., and Nth modules starts. This makes it possible to vary the timing of the stop-restart refresh operations for each of the multiple fuel cell modules 10.

[0114] [Third example of a fuel cell system] A third example of the fuel cell system 1 according to this embodiment will be described with reference to Figure 10.

[0115] In the following examples, the same or corresponding components as in the first example (Figure 1) and the second example (Figure 8) described above are denoted by the same reference numerals. The explanation will focus on the parts that differ from the first and second examples, and the explanation of parts that are the same or corresponding to the first and second examples may be omitted.

[0116] Figure 10 shows the configuration of a third example of fuel cell system 1.

[0117] As shown in Figure 10, the fuel cell system 1 in this example differs from the second example described above in that only one water quality meter 50 is provided for multiple fuel cell modules 10 (four in this example).

[0118] Unlike the second example described above, the exhaust gas EXa and generated water CW discharged from each of the multiple gas-liquid separators 40 are combined into one and discharged outside the fuel cell system 1.

[0119] The water quality meter 50 measures the quality of the generated water CW that is collected after being discharged from each of the multiple gas-liquid separators 40 and then combined.

[0120] Furthermore, if the fuel cell system 1 includes three or more fuel cell modules 10, the generated water CW from each of the multiple fuel cell modules 10 may not merge into one, but rather be consolidated into two or more channels, which is fewer than the number of fuel cell modules 10. In this case, a water quality meter 50 is provided for each consolidated channel.

[0121] [Fourth example of a control method for a fuel cell system] Referring to Figure 11, a fourth example of a control method for the fuel cell system 1 will be described.

[0122] In the following, this example will focus on explaining the differences from the first (Figures 4 and 5), second (Figures 6 and 7), and third (Figure 9) examples of the control method described above.

[0123] Figure 11 illustrates a fourth example of a control method for stopping, restarting, and refreshing the fuel cell module 10. Specifically, Figure 11 shows the macroscopic time variation of the measured electrical conductivity EC of the generated water CW, as measured by the water quality meter 50.

[0124] In Figure 11, the numbers inside the open and closed triangles, which indicate the timing of the stop-restart refresh operation, are identification numbers that identify the fuel cell module 10 currently undergoing the stop-restart refresh operation among the N fuel cell modules 10 (N=4 in this example). Specifically, the identification numbers represent the order in which the periodic stop-restart refresh operation is performed on the target fuel cell module 10 among the N fuel cell modules 10.

[0125] As shown in Figure 11, in this example, the control device 20 causes each of the multiple fuel cell modules 10 to perform a stop-restart refresh operation at each refresh cycle T0, similar to the first and third examples of the control method described above. This allows the control device 20 to periodically restore the power generation performance of the fuel cell stack 11 for each of the multiple fuel cell modules 10.

[0126] Furthermore, in this example, the control device 20 is configured so that the timing of periodic stop-restart refresh operations is different for each of the multiple fuel cell modules 10, similar to the third example of the control method described above. As a result, the control device 20 can maintain power supply to the external load 100 with (N-1) fuel cell modules 10 while sequentially performing stop-restart refresh operations for all fuel cell modules 10.

[0127] Furthermore, in this example, similar to the first and third examples of the control method described above, the control device 20 performs an additional stop-restart refresh operation of the fuel cell module 10 if the electrical conductivity EC of the generated water CW rises to a threshold ECth11 or higher during the stop-restart refresh operation of the fuel cell module 10. This allows the control device 20 to more appropriately reduce the amount of decomposition products of the polymer electrolyte membrane attached to the catalyst of the fuel cell cell, and as a result, the power generation performance of the fuel cell stack 11 can be more appropriately restored. Therefore, the lifespan of the fuel cell stack 11 can be extended.

[0128] For example, as shown in Figure 11, when the fuel cell module 10 with identification number "2" undergoes a stop-restart refresh operation, the electrical conductivity EC of the generated water CW rises to above the threshold ECth11 (see the dashed circle in the figure). Therefore, the control device 20 performs an additional stop-restart refresh operation of the fuel cell module 10 (first time). In this case, the peak value of the electrical conductivity EC of the generated water CW following the first additional stop-restart refresh operation is below the threshold ECth11. Therefore, the control device 20 determines that the decomposition products of the polymer electrolyte membrane that were attached to the catalyst of the fuel cell cell have been sufficiently washed away, and does not perform any further additional stop-restart refresh operations, instead waiting for the next scheduled stop-restart refresh operation.

[0129] Furthermore, in this example, the control device 20 can monitor changes in electrical conductivity EC associated with stopping, restarting, and refreshing multiple fuel cell modules 10 using a single water quality meter 50. This reduces the cost and space required for installing the water quality meter 50.

[0130] [Other examples of fuel cell system control methods] Other examples of control methods for fuel cell system 1 are described below.

[0131] The first to fourth examples of the control methods for the fuel cell system 1 described above may be modified or altered as appropriate. Hereinafter, examples of modifications or alterations made to the first to fourth examples of the control methods for the fuel cell system 1 described above will be referred to as "modified versions" for convenience.

[0132] For example, both the first and second examples of the control methods described above may be applied to the first example of the fuel cell system 1 described above.

[0133] Furthermore, in the second example of the fuel cell system 1 described above and its modified form, the cycle of load fluctuation refresh operation may be changed (shortened) instead of, or in addition to, the cycle of stop-restart refresh operation.

[0134] Furthermore, based on the second example of the fuel cell system 1 described above, the second example of the control method described above or a modified version thereof may be applied to each of the multiple fuel cell modules 10, instead of or in addition to the third example of the control method described above. In this case, if the condition for shortening the stop-restart-refresh operation cycle is met for any one of the fuel cell modules 10, the stop-restart-refresh operation cycle will be shortened for all of the fuel cell modules 10.

[0135] Furthermore, in the first, third, and fourth examples of the control method for the fuel cell system 1 described above, or in variations thereof, the stop-restart refresh operation may be performed irregularly. In this case as well, the control device 20 causes the fuel cell module 10 to perform an additional stop-restart refresh operation if the sulfate ion concentration of the generated water CW rises to a predetermined standard or higher as a result of the irregularly performed stop-restart refresh operation.

[0136] Furthermore, in the first to fourth examples of the control method for the fuel cell system 1 described above, and in their variations, control regarding the execution of stop, restart, and refresh operations may be performed based on the concentration of other types of ions contained in the generated water CW, instead of, or in addition to, the sulfate ion concentration of the generated water CW. Other types of ions are ions derived from the decomposition products of the polymer electrolyte membrane, which are different from sulfate ions. Other types of ions include, for example, fluoride ions (F -Fluoride ions (also called "fluoride ions") include at least one of inorganic fluoride ions and organic fluoride ions. In this case, the water quality meter 50 obtains information on the concentration of fluoride ions contained in the generated water CW. For example, the water quality meter 50 is an electrical conductivity meter capable of measuring the electrical conductivity of the generated water CW. This is because, as with the case of the sulfate ion concentration contained in the generated water CW, a certain correlation can be found between the electrical conductivity of the generated water CW and the concentration of fluoride ions contained in the generated water CW. The water quality meter 50 may also be a hydrogen ion concentration meter capable of measuring the hydrogen ion concentration (pH). This is because, as with the sulfate ion concentration contained in the generated water CW, a certain correlation can be found between the hydrogen ion concentration (pH) of the generated water CW and the concentration of sulfate ions. The water quality meter 50 may also be an ion chromatograph capable of separating, detecting, and quantitatively analyzing fluoride ions contained in the generated water CW.

[0137] [Effect] The operation of the fuel cell system and control device according to this embodiment will be described.

[0138] In a first aspect of this embodiment, the fuel cell system comprises a fuel cell, a water quality meter, and a control device. The fuel cell system is, for example, the fuel cell system 1 described above. The fuel cell is, for example, the fuel cell module 10 described above. The water quality meter is, for example, the water quality meter 50 described above. The control device is, for example, the control device 20 described above. Specifically, the fuel cell is a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen. The water quality meter acquires information regarding the concentration of ions contained in the generated water produced when the fuel cell generates electricity. The ions are, for example, ions derived from decomposition products of the polymer electrolyte membrane, such as sulfate ions and fluoride ions described above. The control device then performs control related to the refresh operation of the fuel cell. The refresh operation is, for example, the stop-restart refresh operation or the load change refresh operation described above. More specifically, the control device controls the frequency of the refresh operation based on the information acquired by the water quality meter.

[0139] Furthermore, in the first aspect of this embodiment, the control device may be provided separately from the fuel cell system.

[0140] Furthermore, in the first aspect of this embodiment, a control method may be provided for a control device that controls the refresh operation of a fuel cell system, which includes a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that acquires information on the concentration of ions contained in the generated water produced during the power generation of the fuel cell. Specifically, the control method executed by the control device controls the frequency of the refresh operation based on the information acquired by the water quality meter.

[0141] As a result, the control device can determine the concentration of ions derived from the decomposition products of the polymer electrolyte membrane in the solid polymer fuel cell, contained in the generated water, based on information obtained from the water quality meter. Therefore, the control device can appropriately control the frequency of refresh operations in accordance with the progress of the decomposition of the polymer electrolyte membrane in the solid polymer fuel cell. Thus, the control device can more effectively suppress the degradation of the fuel cell's performance.

[0142] Furthermore, in a second aspect of this embodiment, based on the first aspect described above, the refresh operation may include a first refresh operation in which the fuel cell is operated at an output relatively high relative to a predetermined standard after it has stopped and restarted. The first refresh operation is, for example, the stop-restart refresh operation described above. The predetermined standard is, for example, 80% of the maximum output of the fuel cell stack 11 described above.

[0143] This allows the control device to more effectively restore the power generation performance of the fuel cell by controlling the frequency of the first refresh operation.

[0144] Furthermore, in a third aspect of this embodiment, based on the second aspect described above, the control device may cause the fuel cell to perform the first refresh operation again if the concentration of the ions in the generated water rises to or above a first standard as a result of performing the first refresh operation of the fuel cell. The first standard is, for example, a value of sulfate ion concentration corresponding to the threshold ECth11 set for the electrical conductivity EC described above.

[0145] This allows the control device to further wash away any remaining polymer electrolyte membrane decomposition products from the fuel cell catalyst during the first refresh operation. As a result, the control device can more effectively restore the power generation performance of the fuel cell.

[0146] Furthermore, in a fourth aspect of this embodiment, based on the third aspect described above, the control device may cause the fuel cell to perform the first refresh operation at predetermined intervals, and if the concentration of the ions in the generated water rises to or above the first standard as a result of the first refresh operation of the fuel cell, the control device may cause the fuel cell to perform the first refresh operation again, and the re-execution of the first refresh operation may be repeated until the concentration of the ions in the generated water no longer rises to or above the first standard even after the first refresh operation of the fuel cell is performed. The predetermined period is, for example, the refresh period T0 described above. Alternatively, the predetermined period may be, for example, the refresh period Tx described above.

[0147] As a result, the control device can thoroughly wash away any remaining polymer electrolyte membrane decomposition products from the fuel cell catalyst during the first refresh operation. Therefore, the control device can more effectively restore the power generation performance of the fuel cell.

[0148] Furthermore, in a fifth aspect of this embodiment, based on any one of the first to fourth aspects described above, the control device may cause the fuel cell to perform the refresh operation at predetermined intervals. The predetermined period is, for example, the refresh period T0 described above. Alternatively, the predetermined period may be, for example, the refresh period Tx described above. The refresh operation period may be set to become shorter as the concentration of the ions in the generated water increases under normal operating conditions different from the refresh operation.

[0149] This allows the control device to increase the frequency of refresh operations in accordance with the progression of degradation of the fuel cell and the subsequent decomposition of the polymer electrolyte membrane. As a result, the control device can more effectively suppress the performance degradation of the fuel cell.

[0150] Furthermore, in the sixth aspect of this embodiment, assuming any one of the first to fifth aspects described above, there may be multiple fuel cells. The control device may then control the frequency of the refresh operation for each of the multiple fuel cells based on the information obtained by the water quality meter.

[0151] This allows the control device to more effectively suppress the performance degradation of each of the multiple fuel cells.

[0152] Furthermore, in the seventh aspect of this embodiment, based on the sixth aspect described above, the generated water from each of the multiple fuel cells may be aggregated into a number of channels smaller than the number of fuel cells. The water quality meter may then acquire information regarding the concentration of the ions contained in the generated water in the aggregated channels.

[0153] This allows fuel cell systems to reduce the number of water quality meters required. Therefore, fuel cell systems can be made more space-efficient and cost-effective.

[0154] Furthermore, in the eighth aspect of this embodiment, a gas-liquid separator may be provided to separate the gaseous component from the liquid component of the generated water from the exhaust of the fuel cell, based on any one of the first to seventh aspects described above. The water quality meter may then acquire information regarding the concentration of the ions contained in the generated water discharged from the gas-liquid separator.

[0155] This allows the control device to more accurately determine the concentration of ions contained in the water produced by the fuel cell.

[0156] Furthermore, in the ninth aspect of this embodiment, based on any one of the first to eighth aspects described above, the water quality meter may include at least one of the following: an electrical conductivity meter for measuring the electrical conductivity of the generated water, a hydrogen ion concentration meter for measuring the hydrogen ion concentration of the generated water, and an ion chromatograph.

[0157] This allows the control device to directly or indirectly determine the concentration of sulfate ions or fluoride ions in the fuel cell's generated water based on information obtained from the water quality meter.

[0158] Furthermore, in the tenth embodiment of this embodiment, the fuel cell system may use pure hydrogen as fuel, based on any one of the first to ninth embodiments described above.

[0159] As a result, the control device can more effectively suppress the performance degradation of the fuel cell in a fuel cell system using pure hydrogen.

[0160] Although embodiments have been described in detail above, this disclosure is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist described in the claims. [Explanation of symbols]

[0161] 1. Fuel cell system 10 Fuel Cell Modules 11 Fuel cell stack 12 Output adjustment section 13 Flow rate adjustment section 14 Control Unit 20 Control device 21 timers 30 Energy storage devices 40 Gas-liquid separator 50 Water quality meter 100 External load CW produced water T0 Refresh cycle T1 Refresh Cycle T2 Refresh Cycle T3 Refresh Cycle T4 Refresh Cycle

Claims

1. A solid polymer fuel cell generates electricity through a chemical reaction between hydrogen and oxygen, A water quality meter that acquires information regarding the concentration of ions contained in the water generated during power generation by the aforementioned fuel cell, The system includes a control device that performs control related to the refresh operation of the fuel cell, The control device controls the frequency of the refresh operation based on the information obtained by the water quality meter. The refresh operation includes a first refresh operation in which the stopping of the fuel cell, restarting the fuel cell, and operating the fuel cell at an output relatively high compared to a predetermined standard are performed as a series of operations. The control device causes the fuel cell to perform the first refresh operation at predetermined intervals, and, in conjunction with the first refresh operation of the fuel cell at predetermined intervals, causes the control device to perform the first refresh operation of the fuel cell in accordance with the information acquired by the water quality meter. Fuel cell system.

2. The control device, when the concentration of the ions in the generated water rises to or above a first standard as a result of the first refresh operation of the fuel cell at predetermined intervals, causes the fuel cell to perform the first refresh operation again. The fuel cell system according to claim 1.

3. The control device, when the concentration of the ions in the generated water rises to or above a first standard as a result of the first refresh operation of the fuel cell at predetermined intervals, causes the fuel cell to perform the first refresh operation again, and repeats the first refresh operation until the concentration of the ions in the generated water no longer rises to or above the first standard even after the first refresh operation of the fuel cell has been performed. The fuel cell system according to claim 2.

4. The control device causes the fuel cell to perform the refresh operation at predetermined intervals. The refresh operation cycle is set to become shorter as the concentration of the ions in the generated water increases under normal operating conditions different from the refresh operation. A fuel cell system according to any one of claims 1 to 3.

5. There are multiple fuel cells, The control device controls the frequency of the refresh operation for each of the plurality of fuel cells based on the information obtained by the water quality meter. A fuel cell system according to any one of claims 1 to 3.

6. The water produced by each of the multiple fuel cells is collected in a number of channels smaller than the number of fuel cells. The water quality meter acquires information regarding the concentration of the ions contained in the generated water in the aggregated flow path. The fuel cell system according to claim 5.

7. The fuel cell is equipped with a gas-liquid separator for separating the gaseous component from the liquid component of the generated water from the exhaust gas. The water quality meter acquires information regarding the concentration of the ions contained in the generated water discharged from the gas-liquid separator. A fuel cell system according to any one of claims 1 to 3.

8. The water quality meter includes at least one of an electrical conductivity meter for measuring the electrical conductivity of the generated water, a hydrogen ion concentration meter for measuring the hydrogen ion concentration of the generated water, and an ion chromatograph. A fuel cell system according to any one of claims 1 to 3.

9. It uses pure hydrogen as fuel. A fuel cell system according to any one of claims 1 to 3.

10. A control device for controlling the refresh operation of a fuel cell system, comprising a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that acquires information on the concentration of ions contained in the generated water produced during the power generation of the fuel cell, wherein the control device controls the refresh operation of the fuel cell. Based on the information obtained by the water quality meter, the frequency of the refresh operation is controlled. The refresh operation includes a first refresh operation in which the stopping of the fuel cell, restarting the fuel cell, and operating the fuel cell at an output relatively high compared to a predetermined standard are performed as a series of operations. The control device causes the fuel cell to perform the first refresh operation at predetermined intervals, and, in conjunction with the first refresh operation of the fuel cell at predetermined intervals, causes the control device to perform the first refresh operation of the fuel cell in accordance with the information acquired by the water quality meter. Control device.

11. A control method performed by a control device that controls the refresh operation of a fuel cell system, comprising a solid polymer fuel cell that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that acquires information on the concentration of ions contained in the generated water produced during the power generation of the fuel cell, wherein Based on the information obtained by the water quality meter, the frequency of the refresh operation is controlled. The refresh operation includes a first refresh operation in which the stopping of the fuel cell, restarting the fuel cell, and operating the fuel cell at an output relatively high compared to a predetermined standard are performed as a series of operations. The control device causes the fuel cell to perform the first refresh operation at predetermined intervals, and, in conjunction with the first refresh operation of the fuel cell at predetermined intervals, causes the control device to perform the first refresh operation of the fuel cell in accordance with the information acquired by the water quality meter. Control method.