JP6968554B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system including a cell stack that generates electricity by reacting a fuel gas and an oxidant gas.

As a method for diagnosing deterioration of a cell stack in a fuel cell system, a method for diagnosing deterioration by changing the power generation output of the cell stack has been proposed (see, for example, Patent Document 1). As a cell stack, for example, one using a solid electrolyte is put into practical use. In this solid oxide type cell stack, a fuel electrode is arranged on one side of the solid electrolyte that conducts oxygen ions. An air electrode is arranged on the other side, and zirconia doped with itria is generally used as the material of the solid electrolyte. Fuel gas (hydrogen, carbon monoxide, etc.) is supplied to the fuel electrode side of the cell stack, and oxidant gas (air, oxygen, etc.) is supplied to the oxygen electrode side, and the fuel gas and the oxidant gas are electrically charged. Power is generated by a chemical reaction.

In the conventional cell stack deterioration diagnosis method, the output current and output voltage of the cell stack when the output power of the cell stack is changed are detected, and the IV characteristics of the cell stack are detected based on the detected current and the detected voltage. To estimate. Then, the slope of the estimated IV characteristic and the output voltage at no load (so-called estimated intercept) are obtained, and the deterioration state of the cell stack is determined based on the slope and the estimated intercept. Also, the output voltage between the two parts of the cell stack, that is, the first and second parts, is detected, the virtual open circuit voltage is calculated using these output voltages, and the virtual open circuit voltage is calculated based on these virtual open circuit voltages. Diagnosing local deterioration of the cell stack. In such a cell stack diagnostic method, since the detection outputs of the two parts of the cell stack are used, the local deterioration state of the cell stack is not affected by the temperature fluctuation of the cell stack and the composition fluctuation of the fuel gas. Can be diagnosed.

Japanese Unexamined Patent Publication No. 2012-204125

However, although this conventional deterioration diagnosis method can perform deterioration diagnosis of the cell stack, it cannot perform deterioration diagnosis of auxiliary equipment such as a fuel gas pump, a water pump, and an oxide blower. Generally, in a fuel cell system, when it is operated for a long period of time, the cell stack deteriorates and the auxiliary equipment such as a fuel gas pump also deteriorates, and it is desired to realize a system capable of diagnosing the deterioration of the auxiliary equipment. It was rare.

An object of the present invention is to provide a fuel cell system capable of diagnosing a deterioration state of an auxiliary device while operating the fuel cell system.

The fuel cell system according to claim 1 of the present invention generates power by oxidizing and reducing a reformer for reforming the fuel gas and the reformed fuel gas and the oxidizing agent reformed by the reformer. A cell stack including a plurality of fuel cell cells for performing the above, an auxiliary device for assisting the power generation of the cell stack, and a controller for controlling the auxiliary device, and the auxiliary device is the modified device. It includes a fuel gas pump for supplying fuel gas to a pledge, an oxidant blower for supplying an oxidant to the cell stack, and a water pump for supplying reformed water to the reformer. It ’s a fuel cell system.
The controller includes auxiliary equipment deterioration diagnostic means for performing deterioration diagnosis of at least one of the auxiliary equipment, and the auxiliary equipment deterioration diagnosis means is a power detection for detecting the drive power of the auxiliary equipment for performing deterioration diagnosis. The means, the moving average value calculating means for calculating the moving average value for each measurement time of the detected power of the power detecting means, and the deterioration progress state of the auxiliary device for performing deterioration diagnosis are calculated for each interval of the deterioration diagnosis period. Auxiliary equipment deterioration gradient value calculation means for calculating auxiliary equipment deterioration gradient value calculation means and auxiliary equipment prediction deterioration value calculation means for calculating auxiliary equipment prediction deterioration value in the reference life period based on the auxiliary equipment deterioration gradient value by the auxiliary equipment deterioration gradient value calculation means. And an auxiliary machine deterioration determining means for determining whether or not the deterioration of the auxiliary equipment is progressing.
The moving average value by the moving average value calculation means is updated during the deterioration diagnosis period, and the auxiliary equipment deterioration gradient value calculation means is one before the current moving average value at the lapse of the deterioration diagnosis period. The auxiliary equipment deterioration gradient value of the auxiliary equipment is calculated based on the moving average value of the deterioration diagnosis period, and the auxiliary equipment prediction deterioration value calculation means is the auxiliary machine calculated by the auxiliary equipment deterioration gradient value calculation means. The auxiliary machine prediction deterioration value in the reference life period is calculated based on the deterioration gradient value, and the auxiliary machine deterioration determination means is deteriorated based on the auxiliary machine prediction deterioration value by the auxiliary machine prediction deterioration value calculation means. It is characterized in that it is determined whether or not it is.

Further, in the fuel cell system according to claim 3 of the present invention, the auxiliary equipment deterioration diagnosis means further includes a power detection means for detecting the driving power of the auxiliary device for performing deterioration diagnosis and the power detection means. The moving average value calculation means for calculating the moving average value for each measurement time of the detected power of the above is included, and the moving average value by the moving average value calculation means is updated during the deterioration diagnosis period, and the auxiliary machine is used. The deterioration gradient value calculation means calculates the auxiliary equipment deterioration gradient value of the auxiliary device based on the current moving average value at the lapse of the deterioration diagnosis period and the previous moving average value of the previous deterioration diagnosis period. It is characterized by.

Further, in the fuel cell system according to claim 3 of the present invention, the controller further displays an auxiliary device failure determining means for diagnosing deterioration failure of at least one of the auxiliary devices and a failure of the auxiliary device. If the auxiliary equipment deterioration gradient by the auxiliary equipment deterioration gradient value calculation means tends to decrease, the auxiliary equipment failure determination means determines that the auxiliary equipment failure determination means is a deterioration failure, and the auxiliary equipment failure determination means is included. It is characterized in that the auxiliary machine failure display means operates based on the determination of the deterioration failure due to the above.

Further, in the fuel cell system according to claim 4 of the present invention, the auxiliary equipment is the oxidant blower and / or the fuel gas pump, and when the auxiliary equipment deterioration determining means determines that deterioration progresses, the fuel cell system The oxidant blower and / or the fuel gas pump is operated and reversely rotated when the operation is stopped.

According to the fuel cell system according to claim 1 of the present invention, the controller for controlling the auxiliary equipment includes an auxiliary equipment deterioration diagnostic means for performing deterioration diagnosis of at least one of the auxiliary equipment, and the auxiliary equipment deterioration thereof. The diagnostic means are a power detecting means for detecting the drive power of an auxiliary device for performing deterioration diagnosis, a moving average value calculating means for calculating a moving average value of the detected power, an auxiliary equipment deterioration gradient value calculating means, and an auxiliary equipment predicted deterioration value. The auxiliary machine deterioration gradient value calculation means, including the calculation means and the auxiliary machine deterioration determination means, calculates the deterioration progress state of the auxiliary equipment for deterioration diagnosis at each deterioration diagnosis period interval, and the auxiliary machine prediction deterioration value calculation means is used. Based on the calculated auxiliary equipment deterioration gradient value, the auxiliary equipment deterioration prediction deterioration value in the reference life period (for example, 10 years) is calculated, and the auxiliary equipment deterioration determination means progresses deterioration based on the calculated auxiliary equipment deterioration prediction deterioration value. Since it is determined whether or not the auxiliary device to be diagnosed is operating continuously without deterioration until the reference life period, it is possible to predict whether or not the auxiliary device to be diagnosed continues to operate until the reference life period elapses. Then, for the auxiliary equipment that is judged to have a high risk of deterioration failure by the standard life period, the fuel cell system is deteriorated and failed during the standard life period by replacing it with a new one in advance before the deterioration failure. It can be operated without any trouble, and deterioration diagnosis of such auxiliary equipment can be performed during the operating operation of the fuel cell system.
Further, since the moving average value by the moving average value calculation means is updated over the deterioration diagnosis period, it is possible to detect the change in the drive power of the auxiliary device during this deterioration diagnosis period. In auxiliary equipment (for example, fuel gas pumps, water pumps, oxidant blowers, etc.), the drive efficiency decreases as the deterioration progresses, so when trying to maintain the initial capacity of the installation, the drive power increases, and this deterioration The deterioration state of the auxiliary equipment can be diagnosed from the fluctuation of the drive power during the diagnosis period. Further, the moving average value calculating means calculates the moving average value for each measurement time of the detected power of the power detecting means, and the auxiliary machine deterioration gradient value calculating means calculates the auxiliary machine deterioration gradient value using this moving average value. Therefore, by using this auxiliary equipment deterioration gradient value, it is possible to accurately predict and know the deterioration progress of the auxiliary equipment at the stage before the reference life period.
Regarding the drive control of this auxiliary device, when the drive voltage is controlled by changing the drive voltage while keeping the drive current constant, a power detection means that detects the drive voltage is used as the power detection means, and the power detection means assists. When the drive voltage supplied to the device is detected and the drive current (the dudy ratio) is controlled by changing the drive current (the dudy ratio) while keeping the drive voltage constant, the drive current (the dudy ratio) is used as a power detection means. ) Is used, and the drive current supplied to the auxiliary device is detected by this current detecting means.

Further, according to the fuel cell system according to claim 2 of the present invention, the auxiliary equipment deterioration determination means includes the auxiliary equipment deterioration determination reference value in the reference life period and the auxiliary equipment prediction deterioration value by the auxiliary equipment prediction deterioration value calculation means. Since it is determined that the deterioration progresses by comparing the above, it is possible to predict and know the deterioration progress of the auxiliary equipment before the lapse of the reference life period.

Further, according to the fuel cell system according to claim 3 of the present invention, the controller includes an auxiliary machine failure determining means and an auxiliary machine failure display means, and the auxiliary machine deterioration gradient by the auxiliary machine deterioration gradient value calculation means is lowered. If there is a tendency, for example, the filter built in the auxiliary equipment is likely to be damaged, and in this case, the auxiliary equipment failure display means is activated, thereby knowing that the auxiliary equipment is out of order. be able to.

Further, according to the fuel cell system according to claim 4 of the present invention , the auxiliary equipment is an oxidant blower and / or a fuel gas pump, and when the auxiliary equipment deterioration determining means determines that the deterioration progresses, the fuel cell system operates. Since the oxidant blower and / or the fuel gas pump operates in the reverse rotation in the stopped state, the clogging of the filter attached to the oxidant blower and / or the fuel gas pump is cleared, and the deterioration progress due to this clogging is eliminated. Can be recovered.

The simplified figure which shows one embodiment of the fuel cell system according to this invention simply. The block diagram which shows the control system of the fuel cell system of FIG. The figure which shows the relationship between the power generation output of a cell stack in the fuel cell system of FIG. 1 and the drive voltage (duty ratio of a drive current) of a fuel gas pump. The figure which shows the relationship between the driving voltage (due diligence ratio of the driving current) of a fuel gas pump, and the rotation speed. The figure for demonstrating the determination of the deterioration progress in a fuel gas pump. A flowchart showing the flow of deterioration diagnosis of a fuel gas pump. The figure for demonstrating the failure determination in an air blower. The flowchart which shows the flow of the deterioration diagnosis of the air blower in the fuel cell system of FIG.

Hereinafter, an embodiment of the fuel cell system according to the present invention will be described with reference to the accompanying drawings. In this embodiment, the present invention will be described by applying the present invention to a solid oxide fuel cell system as an example of a fuel cell system, but other forms of fuel cell system, for example, a solid polymer fuel cell system. It can be applied to such as as well.

In FIG. 1, the illustrated fuel cell system 2 includes a reformer 4 and a cell stack 6. As the reformer 4, for example, a catalyst in which alumina is supported on alumina is used as a reforming catalyst, and the fuel gas is steam reformed by the reforming catalyst as described later. As the fuel gas, natural gas (for example, city gas) or the like is used.

The cell stack 6 is configured by stacking a plurality of solid oxide fuel cell cells (not shown) for generating electricity by an electrochemical reaction via a current collecting member. This fuel cell includes a solid electrolyte that conducts oxygen ions, a fuel electrode provided on one side of the solid electrolyte, and an oxygen electrode provided on the other side of the solid electrolyte, and is doped with, for example, itria as the solid electrolyte. Zirconia is used.

The fuel electrode side of the cell stack 6 is connected to the reformer 4 via the reformed fuel gas supply line 8, and the oxygen electrode side thereof is connected to the air blower 12 (as an oxidant blower) via the air supply line 10. It works) is connected. The air blower 12 supplies air as an oxidant to the air electrode side of the cell stack 6 through the air supply line 10, and as described later, controls the rotation speed of the air blower 12 to supply air to the cell stack 6. The amount of supply is controlled.

The reformer 4 is connected to the desulfurization apparatus 16 via the fuel gas supply line 14, and the desulfurization apparatus 16 is connected to a fuel gas supply source (not shown) via the fuel gas supply line 18 (for example, an embedded pipe). , Fuel gas tank, etc.), and a fuel gas pump 20 is arranged in the fuel gas supply line 18. The fuel gas pump 20 supplies fuel gas to the desulfurization apparatus 16 through the fuel gas supply line 18, the desulfurizer 16 removes the sulfur component contained in the fuel gas, and the fuel gas from which the sulfur component has been removed sends the fuel gas. It is supplied to the reformer 4 through the supply line 14. As will be described later, the fuel gas pump 20 controls the supply amount of the fuel gas supplied to the reformer 4 by controlling the rotation speed thereof.

In this embodiment, one end side of the steam supply line 22 is connected to the fuel gas supply line 14, and the other end side is connected to the vaporizer 24, and the vaporizer 24 supplies reformed water via the water supply line 26. It is connected to a source (not shown) (eg, water tank, water pipe, etc.). A water pump 28 is arranged in the water supply line 26. The water pump 28 supplies reformed water to the vaporizer 24 through the water supply line 26. By controlling the rotation speed of the water pump 28, the amount of reformed water supplied to the vaporizer 24 is controlled. The vaporizer 24 vaporizes the reformed water to generate steam, and the generated steam is sent to the fuel gas feeding line 14 through the steam feeding line 22, and together with the fuel gas through the fuel gas feeding line 14. It is sent to the reformer 4.

The reformer 4 steam reforms the fuel gas with steam from the vaporizer 24, and the steam reformed reformed fuel gas is supplied to the fuel electrode side of the cell stack 6 through the reformed fuel gas supply line 8. Will be done. The steam supply line 22 may be connected to the reformer 4 to directly supply the steam from the vaporizer 24 to the reformer 4, or the vaporizer 24 and the reformer 4 may be used. May be integrally configured, and the fuel gas from the desulfurization device 16 may be supplied to the reformer 4 through the vaporizer 24.

The reformed fuel gas from the reformer 4 is supplied to the fuel electrode side 12 of the cell stack 6 through the reformed fuel gas supply line 8, and the air ( oxidizer ) from the air blower 20 is supplied through the air supply line 10. It is supplied to the air electrode side of the cell stack 6, and power is generated by oxidizing the reformed fuel gas in the cell stack 6 and reducing the oxidizing agent. The power generation output of the cell stack 6 is connected to the inverter 32 via the power generation output line 30, the DC generated power is converted into AC power by the inverter 32, and the AC power thus converted to AC is transmitted via the AC output line 34. It is supplied to and consumed by a power load (not shown) (for example, various electric appliances in the home).

Combustion regions (not shown) are provided on each discharge side of the fuel pole side and the oxygen pole side of the cell stack 6, and the surplus fuel gas discharged from the fuel pole side of the cell stack 6 (that is, the cell stack 6). The fuel gas that was not used for power generation) and the air (including oxygen) discharged from the oxygen electrode side are discharged to this combustion region and burned. A gas discharge line 36 is connected to the combustion region, and the exhaust gas from the combustion chamber is discharged to the atmosphere through the gas discharge line 36.

In the fuel cell system 2, the cell stack 6, the reformer 4, and the vaporizer 24 are housed in the battery housing 38. The battery housing 38 defines a high temperature space 40 covered with a heat insulating member (not shown), and the cell stack 6, the reformer 4, and the vaporizer 24 are housed in the high temperature space 40 and kept in a high temperature state. ..

When such a fuel cell system 2 is applied to a cogeneration system, although not shown, a hot water storage device is provided in connection with the fuel cell system 2, and a heat exchanger is arranged in the gas discharge line 36. Will be done. The hot water storage device includes a hot water storage tank for storing hot water and a circulation line for circulating water in the hot water storage tank through a heat exchanger, and a circulation pump is arranged in this circulation line. In such a cogeneration system, heat exchange between the exhaust gas discharged through the gas discharge line 36 and the water circulated through the circulation line is performed by the heat exchanger, and the hot water heated by the heat exchange is stored in the hot water storage tank. In this way, the heat in the exhaust gas is recovered as hot water.

The fuel cell system 2 is configured as follows so as to perform deterioration diagnosis of the auxiliary equipment of the fuel cell system 2. The auxiliary equipment in this embodiment is a fuel gas pump 20, a water pump 28, and an air blower 12, and is applied to a deterioration diagnosis of the fuel gas pump 20, a water pump 28, and an air blower 12 as a target of deterioration diagnosis of the auxiliary equipment. ..

With reference to FIG. 1 and FIG. 2, the fuel gas pump 20, the water pump 28, and the air blower 12 have a form in which the drive current is constant and the rotation speed is controlled by the fluctuation of the drive voltage, and the drive voltage thereof is the same. The higher the number, the higher the number of rotations. In connection with this, as a first power detecting means for detecting the driving power of the fuel gas pump 20, a first voltage detecting means 42 for detecting the driving voltage is provided, and a first voltage detecting means for detecting the driving power of the water pump 28 is detected. The second voltage detecting means 44 for detecting the driving voltage is provided as the second power detecting means, and the third voltage for detecting the driving voltage as the third power detecting means for detecting the driving power of the air blower 12. The detection means 46 is provided. The first to third voltage detecting means 42 to 46 are composed of, for example, a voltage detecting sensor.

As the fuel gas pump 20, the water pump 28, and the air blower 12, the fuel gas pump 20, the water pump 28, and the air blower 12 may be of a form in which the drive voltage is constant and the rotation speed is controlled by the fluctuation of the drive current (variation of the duedy ratio). As their drive current increases (ie, the dudy ratio increases), their rotation speed increases. In such a case, a first current detecting means (functioning as a first power detecting means) for detecting the driving current of the fuel gas pump 20 is used, and a second driving current for detecting the driving current of the water pump 28 is used. A current detecting means (functioning as a second power detecting means) is used, and a third current detecting means (functioning as a third power detecting means) for detecting the drive current of the air blower 12 is used. The third current detecting means is composed of, for example, a current detecting sensor.

The fuel cell system 2 includes a controller 52 for controlling the entire system, and detection signals from the first to third voltage detecting means 42 to 46 are sent to the controller 52. The controller 52 is composed of, for example, a microprocessor or the like, and has a control means 54, an auxiliary equipment deterioration diagnosis means 56, a timer means 60, and a memory means 62. The control means 54 controls the fuel gas pump 20, the water pump 28, the air blower 12, the inverter 32 and the like as described later, and the auxiliary equipment deterioration diagnosis means 56 is an auxiliary device (fuel gas pump 20, water pump 28 and air blower 12). Deterioration diagnosis is performed as described later.

Further, the timer means 60 measures the time, and in this embodiment, the measurement time for calculating the moving average value (for example, set to about 30 to 120 seconds) and the output stability determination time (for example, about 20 to 60 minutes). (Set), deterioration diagnosis period (for example, set to about 300 to 1000 hours), reference life period (for example, set to about 10 years), etc. are timed, and deterioration diagnosis is performed on the memory means 62. The moving average value of the period, the deterioration determination reference value in the reference life period (deterioration determination reference value of the fuel gas pump 20, the water pump 28, and the air blower 12) and the like are stored. The fuel cell system 2 is provided with auxiliary equipment deterioration display means 64 (for example, composed of a deterioration display lamp or the like) for displaying the deterioration progress of the auxiliary equipment in connection with the controller 52. At the same time, an auxiliary machine failure display means 66 (for example, composed of a failure display lamp or the like) for displaying a failure of the auxiliary device is provided.

The auxiliary equipment deterioration diagnosis means 56 of the controller 52 has the following configurations for performing deterioration diagnosis of auxiliary equipment (fuel gas pump 20, water pump 28, and air blower 12). That is, the auxiliary equipment deterioration diagnosis means 56 includes a rated operation determination means 72, an output stability determination means 74, a moving average value calculation means 76, an auxiliary equipment deterioration gradient value calculation means 78, an auxiliary equipment prediction deterioration value calculation means 80, and an auxiliary machine. It includes a deterioration determining means 82 and an auxiliary machine failure determining means 84.

The rated operation determining means 72 determines whether or not the fuel cell system 2 (cell stack 6) is rated operation, and the output stability determining means 74 determines that the output of the fuel cell system 2 (cell stack 6) is stable. (For example, when the output fluctuates within a range of, for example, 10%, it can be treated as no output fluctuation). For example, when the rated output of the cell stack 6 is, for example, 700 W (including the case where it fluctuates within a range of 10%, for example) and the generated output becomes 700 W, the rated operation determining means 74 determines that the rated operation is performed. Further, when this rated operating state continues for the output stability determination time (for example, set to 30 minutes), the output stability determination means 74 determines that the output is stable.

Further, the moving average value calculating means 76 calculates the moving average value of the auxiliary equipment (fuel gas pump 20, water pump 28, and air blower 12). In this embodiment, the fuel gas pump 20, the water pump 28, and the air blower 12 are not specifically shown, but are rotationally driven by a DC drive motor and are configured to be controlled substantially in the same manner.

For example, the fuel gas pump 20 (water pump 28, air blower 12) will be described. As the power generation output of the cell stack 6 increases, more fuel gas (reforming water, air) is required, and therefore, the fuel gas (modified). It is necessary to increase the supply flow rate of quality water and air). With reference to FIGS. 3 and 4, when a DC motor is used as the drive motor and the drive current (or drive voltage) is controlled to be constant, the drive voltage of the fuel gas pump 20 (water pump 28, air blower 12) is controlled. (Or the duedy ratio of the drive current) and its rotation speed are as shown in FIG. 4, and as the drive voltage (or the duedy ratio of the drive current) increases, the rotation speed also increases, and the fuel gas (or the fuel gas (or the duedy ratio of the drive current)). The supply flow rate of reforming water (water for reforming, air) increases (see FIG. 4). Therefore, by keeping the power generation output of the cell stack 6 and the drive voltage (dudy ratio of the drive current) of the fuel gas pump 20 (water pump 28, air blower 12) in the relationship shown in FIG. 3, for example, the power generation output of the cell stack 6 The fuel gas (water for reforming, air) required for the above can be supplied by the fuel gas pump 20 (water pump 28, air blower 12).

In this way, the drive voltage (or the duedy ratio of the drive current) of the fuel gas pump 20 (water pump 28, air blower 12) fluctuates due to the power output of the cell stack 6, and therefore, in this embodiment, the cell stack 6 is rated. Utilizing the fluctuation of the drive voltage (or the duedy ratio of the drive current) of the fuel gas pump 20 (water pump 28, air blower 12) at the time of output (for example, 700 W), the fuel gas pump 20 (water pump 28, air blower 12) Deterioration diagnosis is performed as described later.

For example, in a fuel gas pump 20 (water pump 28, air blower 12) using a DC drive motor, in general, the friction load and the like increase as the deterioration progresses, and the drive voltage (or the duedy ratio of the drive current) increases. Therefore, it is possible to diagnose the deterioration progress state by knowing the upward tendency of the drive voltage (or the duedy ratio of the drive current).

Therefore, in this embodiment, the drive voltage (or the duedy ratio of the drive current) of the fuel gas pump 20 (water pump 28, air blower 12) tends to increase every time the deterioration diagnosis period (for example, 500 hours), in other words. Then, the deterioration gradient value is calculated and the predicted deterioration value of the fuel gas pump 20 (water pump 28, air blower 12) in the reference life period (for example, 10 years) is calculated to determine the deterioration progress.

In this embodiment, the first voltage detecting means 42 (second voltage detecting means 44, third voltage detecting means 46) detects the drive voltage of the fuel gas pump 20 (water pump 28, air blower 12), for example, every second. Then, the moving average value calculation means 76 calculates, for example, the average value of the drive voltage of the immediately preceding measurement period (for example, 60 seconds), that is, the moving average value every second, and the calculation of the moving average value is, for example, 1. It is performed every second, and the calculated moving average value is updated and registered in the memory means 62.

Further, the auxiliary equipment deterioration gradient value calculation means 78 is a moving average value of the fuel gas pump 20 (water pump 28, air blower 12) before and after the deterioration diagnosis period (for example, 500 hours), that is, the moving average after the deterioration diagnosis period has elapsed. The deterioration progress state of the fuel gas pump 20 (water pump 28, air blower 12) based on the value (that is, the current moving average value) and the moving average value (that is, the previous moving average value) in the previous deterioration diagnosis period, that is, The deterioration gradient value is calculated, and this deterioration gradient value increases as the deterioration progresses.

Further, the auxiliary machine prediction deterioration value calculation means 80 is based on the deterioration gradient value of the fuel gas pump 20 (water pump 28, air blower 12) calculated by the auxiliary machine deterioration gradient value calculation means 78, and the state of this deterioration gradient is used as a reference. The predicted deterioration state when it continues to the life period (for example, 10 years), that is, the predicted deterioration value is calculated, and the auxiliary machine deterioration determining means 82 is the fuel gas pump 20 (water pump 28, air blower 12) in the reference life period. Deterioration determination is performed based on the deterioration determination reference value and the predicted deterioration value of the fuel gas pump 20 (water pump 28, air blower 12) calculated by the auxiliary machine predicted deterioration value calculation means 80.

Explaining the deterioration determination by the auxiliary machine deterioration determining means 82 with reference to FIG. 5, the deterioration gradient value of the fuel gas pump 20 (water pump 28, air blower 12) by the auxiliary machine deterioration gradient value calculating means 78 is, for example, FIG. As shown by the one-point chain line P1, the predicted deterioration value of the fuel gas pump 20 (water pump 28, air blower 12) is determined to be deteriorated even if this deterioration gradient state continues until the reference life period (for example, 10 years). The standard value is not exceeded, and in such a case, the fuel gas pump 20 (water pump 28, air blower 12) hardly deteriorates and fails even if the fuel gas pump 20 (water pump 28, air blower 12) is operated for the standard life period. The auxiliary machine deterioration determining means 82 determines that the fuel gas pump 20 (water pump 28, air blower 12) has not progressed in deterioration.

Further, if the deterioration gradient value of the fuel gas pump 20 (water pump 28, air blower 12) is as shown by the broken line Q1 in FIG. 5, for example, if this deterioration gradient state continues until the reference life period, the fuel gas pump 20 (water pump) 28, the predicted deterioration value of the air blower 12) exceeds the deterioration judgment reference value. In such a case, the fuel gas pump 20 (water pump 28, air blower 12) is driven when the fuel gas pump 20 (water pump 28, air blower 12) is operated during the reference life period. There is a high possibility that the voltage will rise beyond the deterioration determination reference value and cause deterioration failure. In such a case, the auxiliary equipment deterioration determination means 82 determines that the fuel gas pump 20 (water pump 28, air blower 12) has deteriorated. By doing so, it is possible to predict whether or not there is a risk of deterioration failure by predicting the stage before the lapse of the standard life period.

Deterioration diagnosis of the fuel gas pump 20 as an auxiliary device in the fuel cell system 2 is performed according to the flowchart shown in FIG. 7. Although the deterioration diagnosis of the fuel gas pump 20 will be described in FIG. 7, as can be easily understood from the above description, the deterioration diagnosis of the water pump 28 and the air blower 12 is the deterioration diagnosis of the fuel gas pump 20. The same applies, and therefore, the description of the deterioration diagnosis of the water pump 28 and the air blower 12 will be omitted.

Deterioration diagnosis of the fuel gas pump 20 will be described mainly with reference to FIGS. 1, 2 and 6. In this embodiment, at the time of deterioration diagnosis, it is determined whether or not the power generation output of the cell stack 6 is the rated output (for example, 700 W) (step S1). That is, the rated operation determination means 72 of the auxiliary equipment deterioration diagnosis means 56 determines that the cell stack 6 power generation output reaches the rated output, and the power generation state of the cell stack 6 is stable in such an operation state. Deterioration diagnosis of the fuel gas pump 20 is performed.

First, it is determined whether the rated output state of the cell stack 6 continues for the output stability determination time (for example, 30 minutes), and steps S1 and S2 are repeatedly executed until the output stability determination time elapses. .. Then, when this rated output state continues for the output stabilization time, the process proceeds from step S2 to step S3, and the drive voltage of the fuel gas pump 20 is detected. The first voltage detecting means 42 detects the driving voltage of the fuel gas pump 20 every second, and the detected driving voltage is stored in the memory means 62 (step S4).

When the rated output state of the cell stack 6 continues for a further measurement time (for example, 60 seconds), the process proceeds from step S5 to step S6 to step S7, and the moving average value of the drive voltage of the fuel gas pump 20 is calculated. The moving average value calculating means 76 calculates the average value (moving average value) of the detected voltage of the first voltage detecting means 42 in the immediately preceding measurement time, and the calculated moving average value of the fuel gas pump 20 overwrites the memory means 62. And memorized (step S8). The detection of the drive voltage of the fuel gas pump 20 and the calculation of the moving average value thereof are performed during the deterioration diagnosis period (for example, 500 hours), and after the deterioration diagnosis period elapses, the process proceeds to step S10 via step S9.

In step S10, the state of deterioration progress of the fuel gas pump 20, and in this embodiment, the deterioration gradient value of the drive voltage is calculated, and further, the predicted deterioration value of the fuel gas pump 20 is calculated based on the deterioration gradient value. We (step S11), and the deterioration state of the fuel gas pump 20 is determined based on the calculated predicted deterioration value (step S12).

The auxiliary equipment deterioration gradient value calculation means 78 is one before the moving average value of the drive voltage of the fuel gas pump 20 before and after the deterioration diagnosis period, that is, the moving average value overwritten and registered in the memory means 62 when the deterioration diagnosis period elapses. The deterioration gradient value is calculated based on the moving average value finally overwritten and registered in the memory means 62 in the deterioration diagnosis period, and the auxiliary machine prediction deterioration value calculation means 82 uses this deterioration gradient value for a reference life period (for example, for example). The predicted deterioration state, that is, the predicted deterioration value when the operation is performed up to (10 years from the start of operation) is calculated.

Then, the auxiliary equipment deterioration determination means 82 compares the calculated predicted deterioration value with the deterioration determination reference value of the fuel gas pump 20 in the reference life period, and the calculated predicted deterioration value exceeds the deterioration determination reference value and deteriorates. Then, it is determined that the deterioration progresses because there is a high possibility of deterioration failure at the stage before the operation until the reference life period (step S13), and the auxiliary equipment deterioration display means 64 operates based on the determination of the deterioration progress to fuel. The deterioration progress of the gas pump 20 is displayed (step S14), and then the process returns to step S1.

Further, if the calculated predicted deterioration value is smaller than the deterioration determination reference value, the auxiliary equipment deterioration determination means 82 considers that there is a low possibility of deterioration failure even if the fuel gas pump 20 is operated and operated until the reference life period, and no deterioration progresses. (Step S15), and then the process returns to step S1, and the deterioration diagnosis of the fuel gas pump 20 is performed in this way.

As described above, in the fuel cell system 2, it is possible to diagnose the deterioration progress state of the auxiliary equipment (fuel gas pump 20, water pump 28, air blower 12) without stopping the operating state of the system.

The fuel cell system 2 has, in addition to the above-mentioned deterioration diagnosis function of the auxiliary equipment (fuel gas pump 20, water pump 28, air blower 12), a failure diagnosis function of the auxiliary equipment, and an eye for eliminating clogging in which deterioration has progressed. It also has a clogging clearing function. In the following description, the air blower 12 as an auxiliary device will be described, but as can be understood from the above description of the deterioration diagnosis function, the fuel gas pump 20 and the water pump 28 as auxiliary devices will also be similarly described. Although it is applied, the description of these application examples is omitted because it is the same as the application example of the air blower 12.

Mainly referring to FIGS. 2, 7 and 8, in the deterioration diagnosis of the air blower 12 as an auxiliary device, the deterioration progress state of the air blower 12, that is, the deterioration gradient value is the same as the deterioration diagnosis of the fuel gas pump 20. The calculation is performed, and the execution content from step S21 to step S30 in the flowchart shown in FIG. 8 is substantially the same as the execution content from step S1 to step S10 in the flowchart shown in FIG.

When the deterioration gradient value of the drive voltage is calculated in the deterioration diagnosis of the air blower 12, the process proceeds from step S30 to step S31, and it is determined whether or not the calculated deterioration gradient tends to increase. As described above, in the air blower 20 (fuel gas pump, water pump 28) using a DC drive motor, the friction load and the like generally increase as the deterioration progresses, and the drive voltage (or the duedy ratio of the drive current). Is tending to increase, and when the deterioration progress is small, the deterioration gradient is shown by the alternate long and short dash line P2, and when the deterioration tendency is large, it is shown by the broken line Q2. The current duty ratio) may tend to decrease as shown by the solid line R. This due diligence of deterioration occurs when the filter member attached to the air blower 20 is damaged, or when the air flow path is damaged, and the due diligence of deterioration occurs when some kind of damage occurs. Therefore, the occurrence of the damaged state can be known by knowing the downward tendency of the driving voltage (or the due diligence ratio of the driving current).

Therefore, in step S30, the state of progress of deterioration of the air blower 12, and in this embodiment, the deterioration gradient value of the drive voltage is calculated, and when this deterioration gradient value tends to increase, step S31. To step S32, the predicted deterioration value of the air blower 12 is calculated based on the deterioration gradient value, and the deterioration state of the air blower 12 is determined based on the calculated predicted deterioration value (step S33). ).

The auxiliary machine deterioration gradient value calculation means 78 is one before the moving average value of the drive voltage of the air blower 12 before and after the deterioration diagnosis period, that is, the moving average value overwritten and registered in the memory means 62 when the deterioration diagnosis period elapses. The deterioration gradient value is calculated based on the moving average value finally overwritten and registered in the memory means 62 in the deterioration diagnosis period, and the auxiliary machine prediction deterioration value calculation means 82 uses this deterioration gradient value for a reference life period (for example, for example). The predicted deterioration state, that is, the predicted deterioration value when the operation is performed up to (10 years from the start of operation) is calculated.

Then, the auxiliary equipment deterioration determination means 82 compares the calculated predicted deterioration value with the deterioration determination reference value of the air pump 12 in the reference life period, and the calculated predicted deterioration value exceeds the deterioration determination reference value and deteriorates. Then, it is determined that the deterioration progresses because there is a high possibility of deterioration failure before the operation is performed until the reference life period (step S34), and it is supplemented that the calculated predicted deterioration value is smaller than the deterioration determination reference value. The machine deterioration determining means 82 determines that there is no progress in deterioration because the possibility of deterioration failure is low even if the air blower 12 is operated and operated until the reference life period (step S35), and then returns to step S21 to return to the above-mentioned air. The deterioration diagnosis of the blower 12 is repeatedly performed.

In this embodiment, when the auxiliary equipment deterioration determining means 82 determines the deterioration progress, the control means 54 generates a clogging signal (step S36), and the fuel cell system 2 is temporarily operated based on the clogging signal. Stop (step S37). After that, the deteriorated air blower 12 is operated by reverse rotation (step S38), and by rotating in reverse for a predetermined time (for example, about 1 to 3 minutes) in this way, impurities adhering to the filter of the air blower 12 (Dust, dust, etc.) is sucked and removed and discharged to the outside.

After the reverse rotation of the air blower 12, the fuel cell system 2 is restarted (step S39), and when the clogging in the air blower 12 is cleared, it is assumed that the air blower 12 has not deteriorated, and steps S40 to S21 Return to. If the clogging is not cleared by the reverse rotation of the air blower 12, the process proceeds to step S41, the auxiliary equipment deterioration display means 64 is operated, the deterioration progress of the air blower 12 is displayed, and then the process returns to step S21. ..

On the other hand, if the deterioration gradient value by the auxiliary equipment deterioration gradient value calculation means 78 tends to decrease, there is a high possibility that the filter (not shown) of the air blower 12 is damaged. In this case, steps S31 to S42 The auxiliary machine failure determination means 84 determines the deterioration failure based on this downward tendency, and the auxiliary machine failure display means 66 operates based on the determination of the deterioration failure, and the deterioration failure is caused in relation to the air blower 12. Notifying that it has occurred (step S43), the fuel cell system 2 is then shut down (step S44).

In the above-described embodiment, the deterioration diagnosis of the fuel gas pump 20, the water pump 28, and the air blower 12 as auxiliary equipment is performed, but it is not necessary to perform the deterioration diagnosis for all of them, and any one of them is used. Alternatively, deterioration diagnosis may be performed for any two. In addition, the failure diagnosis function does not have to be applied to all auxiliary equipment (fuel gas pump 20, water pump 28, air blower 12) to which the deterioration diagnosis function is applied, and it is not necessary to apply it to some of those to which the deterioration diagnosis function is applied. It may be applied.

Although the embodiment of the fuel cell system according to the present invention has been described above, the present invention is not limited to such an embodiment, and various modifications can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, deterioration diagnosis of auxiliary equipment (fuel gas pump 20, water pump 28, air blower 12) is performed when the output of the cell stack 6 is stable in the rated output operating state, but the cell stack 6 is used. This deterioration diagnosis may be performed when the output is stable in the partial load operating state of the cell stack 6, and in such a case, various moving average values (in other words, in other words, depending on the magnitude of the partial load in the partial load operating state of the cell stack 6). , The detection voltage of the first to third voltage detecting means 42 to 46) may be corrected to a value corresponding to, for example, the rated output operating state, and the arithmetic processing may be performed. Also, the deterioration diagnosis of the auxiliary device can be performed as desired.

2 Fuel cell system 4 Reformer 6 Cell stack 12 Air blower ( oxidizer blower )
20 Fuel gas pump 28 Water pump 52 Controller 54 Control means 56 Auxiliary equipment deterioration diagnostic means 76 Moving average value calculation means 78 Auxiliary equipment deterioration gradient value calculation means 80 Auxiliary equipment prediction deterioration value calculation means 82 Auxiliary equipment deterioration judgment means

Claims (4)

A cell stack equipped with a reformer for reforming a fuel gas and a plurality of fuel cell cells for generating power by oxidizing and reducing the reformed fuel gas and the oxidizing agent reformed by the reformer. The auxiliary device includes an auxiliary device for assisting the power generation of the cell stack and a controller for controlling the auxiliary device, and the auxiliary device includes a fuel gas pump for supplying fuel gas to the reformer. A fuel cell system comprising an oxidant blower for supplying the oxidant to the cell stack and a water pump for supplying the reforming water to the reformer.
The controller includes auxiliary equipment deterioration diagnostic means for performing deterioration diagnosis of at least one of the auxiliary equipment, and the auxiliary equipment deterioration diagnosis means is a power detection for detecting the drive power of the auxiliary equipment for performing deterioration diagnosis. The means, the moving average value calculating means for calculating the moving average value for each measurement time of the detected power of the power detecting means, and the deterioration progress state of the auxiliary device for performing deterioration diagnosis are calculated for each interval of the deterioration diagnosis period. Auxiliary equipment deterioration gradient value calculation means for calculating auxiliary equipment deterioration gradient value calculation means and auxiliary equipment prediction deterioration value calculation means for calculating auxiliary equipment prediction deterioration value in the reference life period based on the auxiliary equipment deterioration gradient value by the auxiliary equipment deterioration gradient value calculation means. And an auxiliary machine deterioration determining means for determining whether or not the deterioration of the auxiliary equipment is progressing.
The moving average value by the moving average value calculation means is updated during the deterioration diagnosis period, and the auxiliary equipment deterioration gradient value calculation means is one before the current moving average value at the lapse of the deterioration diagnosis period. The auxiliary equipment deterioration gradient value of the auxiliary equipment is calculated based on the moving average value of the deterioration diagnosis period, and the auxiliary equipment prediction deterioration value calculation means is the auxiliary machine calculated by the auxiliary equipment deterioration gradient value calculation means. The auxiliary machine prediction deterioration value in the reference life period is calculated based on the deterioration gradient value, and the auxiliary machine deterioration determination means is deteriorated based on the auxiliary machine prediction deterioration value by the auxiliary machine prediction deterioration value calculation means. A fuel cell system characterized by determining whether or not it is used. The auxiliary equipment deterioration determination means compares the auxiliary equipment deterioration determination reference value in the reference life period with the auxiliary equipment prediction deterioration value calculated by the auxiliary equipment prediction deterioration value calculation means, and the auxiliary equipment prediction deterioration value is the auxiliary equipment. The fuel cell system according to claim 1, wherein if the fuel cell deteriorates beyond the deterioration determination reference value, it is determined that the deterioration progresses. The controller further includes an auxiliary equipment failure determining means for diagnosing at least one deterioration failure of the auxiliary equipment and an auxiliary equipment failure display means for displaying the failure of the auxiliary equipment, and the auxiliary equipment deterioration. If the auxiliary equipment deterioration gradient by the gradient value calculation means tends to decrease, the auxiliary equipment failure determination means determines that the auxiliary equipment failure is a deterioration failure, and the auxiliary equipment failure display means operates based on the determination of the deterioration failure by the auxiliary equipment failure determination means. The fuel cell system according to claim 1, wherein the fuel cell system is characterized by the above. The auxiliary equipment is the oxidant blower and / or the fuel gas pump, and when the auxiliary equipment deterioration determining means determines that deterioration has progressed, the oxidant blower and / or the fuel is in a state where the operation of the fuel cell system is stopped. The fuel cell system according to claim 1 or 2 , wherein the gas pump is operated and rotated in the reverse direction.

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