JP2012028185A - Cell abnormality detecting device for fuel battery, fuel battery device, and cell abnormality detecting method for fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect abnormality of a fuel battery cell even when polarity inversion states of fuel battery cells occur at the same time in plural cell groups.SOLUTION: A cell abnormality detecting device 50 for a fuel battery has: an alternating current applying unit 52 for applying alternating current to a cell group 18; a measuring unit 54 for measuring impedance of the cell group 18 when the alternating current is applied; a calculating unit 56 for calculating the upper limit value of cell impedance on the basis of cell group impedance measured by the measuring unit 54, an impedance increasing rate at a cell in which a cell abnormality occurs, cell impedance per cell under normal potential, a predetermined number of abnormality occurring cells and the number of cells constituting the cell group 18; and a determining unit 58 for comparing the upper limit value of the cell impedance and the average cell impedance obtained by dividing the cell group impedance by the cell number to determine occurrence or non-occurrence of abnormality of the fuel battery cell 24.

Description

  The present invention relates to a cell abnormality detecting device for a fuel cell, a fuel cell device, and a cell abnormality detecting method for a fuel cell, and in particular, a plurality of fuel cells each including an electrolyte membrane are stacked and connected in series. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell abnormality detection device for a fuel cell that detects a cell reversal state in a fuel cell stack, a fuel cell device including the same, and a cell abnormality detection method for a fuel cell.

  Conventionally, for example, Japanese Unexamined Patent Application Publication No. 2004-220823 (Patent Document 1) discloses a cell abnormality detection device for a fuel cell. This cell abnormality detection device comprises a fuel cell that separates a fuel gas channel and an oxidant gas channel by sandwiching both sides of an electrolyte thin film between a pair of gas separators, and a plurality of such cells are stacked in series. In a fuel cell that constitutes a fuel cell stack and obtains a predetermined output voltage by the fuel cell stack, a cell block in which a predetermined number of cells are stacked in series is provided, and a plurality of the cell blocks are stacked in series. The stack includes a voltage output terminal for taking out an output voltage provided in each cell block, an output voltage detector disposed between the voltage output terminals of each cell block, and voltages of the plurality of output voltage detectors. A voltage comparator for comparison, and safe operating means that operates when the voltage comparator detects a voltage difference between the output voltage detectors.

  Japanese Patent Laying-Open No. 2006-318669 (Patent Document 2) discloses a fuel cell device. The fuel cell device includes a fuel cell stack in which a plurality of cells each having an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode are stacked, a liquid fuel supply unit that supplies liquid fuel to the fuel electrode of the cell, An oxidant supply unit for supplying an oxidant to the oxidant electrode of the cell, between both electrodes in a plurality of cells of the fuel cell stack, and between both electrodes in at least one reference cell included in the plurality of cells Two impedance values are calculated based on an alternating voltage application unit for applying an alternating voltage to the two electrodes and two current signals that respond between the electrodes of the plurality of cells and between the electrodes of the reference cell. And a power generation control unit that detects the occurrence of defects in the cells included in the plurality of cells based on the values.

JP 2004-220823 A JP 2006-318669 A

  In the cell abnormality detection device described in Patent Document 1, when cell abnormality occurs simultaneously in two cell blocks to be compared, a difference in output voltage between the two is less likely to occur. May not be detected accurately.

  Further, even in the fuel cell device described in the above-mentioned Patent Document 2, in the case where defects occur simultaneously in the reference cell serving as a comparison reference and one or more cells among the plurality of other cells, both If the difference between the calculated impedance values does not increase, the cell defect may still not be detected accurately.

  An object of the present invention is to provide a cell abnormality detection device for a fuel cell that can accurately detect abnormality of a fuel cell even when cell abnormality occurs simultaneously in a plurality of cell groups, and a fuel cell using the same An object of the present invention is to provide a device and a cell abnormality detection method for a fuel cell. Here, the cell abnormality that can be detected by the present invention is an abnormality in which the impedance is greatly increased due to the occurrence of water electrolysis due to inversion or the like.

  An apparatus for detecting an abnormality in a cell of a fuel cell according to the present invention applies an alternating current to one or a plurality of cell groups in which a plurality of fuel cells each including an electrolyte membrane are stacked and connected in series. A measurement unit that measures the impedance of the cell group when the alternating current is applied, a cell group impedance measured by the measurement unit, an impedance increase rate in a cell in which a cell abnormality has occurred, and a normal potential A cell impedance per cell, a predetermined number of abnormal cells and a number of cells constituting the cell group, a calculation unit for calculating a cell impedance upper limit value, and the cell group impedance for the cell The cell impedance is determined by comparing the average cell impedance obtained by dividing by the number and the cell impedance upper limit value. It comprises a part, a.

  In the cell abnormality detection device for a fuel cell according to the present invention, the determination unit determines whether the average cell impedance exceeds a value obtained by subtracting a cell impedance fluctuation value generated during normal operation from the cell impedance upper limit value. It may be determined that a cell abnormality has occurred in the cell.

  In the cell abnormality detection device for a fuel cell according to the present invention, the number of abnormality occurrence cells used in the arithmetic unit may be defined in advance as one.

  A fuel cell device according to the present invention includes a cell abnormality detection device for a fuel cell having any one of the above configurations, a fuel cell stack having at least one cell group to which the cell abnormality detection device for the fuel cell is connected, A fuel gas supply / discharge unit that supplies fuel gas to the fuel cell stack and discharges waste fuel gas, and an oxidant gas supply that supplies oxidant gas and discharges waste oxidant gas to the fuel cell stack. A discharge unit.

  A method for detecting a cell abnormality in a fuel cell according to the present invention includes a step of applying an alternating current to a cell group in which a plurality of fuel cells each including an electrolyte membrane are stacked and connected in series, and the alternating current is applied A measurement step of measuring the impedance of the cell group when being performed, a cell group impedance measured by the measurement unit, an impedance increase rate in a cell in which a cell abnormality has occurred, a cell impedance per cell at a normal potential, A calculation step for calculating a cell impedance upper limit value based on a predetermined number of abnormally occurring cells and the number of cells constituting the cell group, and an average obtained by dividing the cell group impedance by the number of cells A determination step of comparing the cell impedance and the cell impedance upper limit value to determine whether or not a cell abnormality has occurred.

  In the cell abnormality detection method for a fuel cell according to the present invention, in the determination step, when the average cell impedance exceeds a value obtained by subtracting a cell impedance fluctuation value generated during normal operation from the cell impedance upper limit value, the fuel cell It may be determined that a cell abnormality has occurred in the cell.

  Moreover, in the cell abnormality detection method for a fuel cell according to the present invention, the number of abnormality occurrence cells used in the calculation step may be defined in advance as one.

  According to the fuel cell abnormality detection device, the fuel cell device, and the fuel cell abnormality detection method according to the present invention, when the electrolyte membrane contained in the fuel cell is dried for some reason and becomes in a reversal state, the impedance is increased. The upper limit value of the cell impedance is calculated in consideration of the rapidly increasing characteristics, and the occurrence of an abnormality in the fuel cell constituting the cell group is determined by comparison with this value. Even when the pole state occurs simultaneously, it is possible to accurately detect the abnormality of the fuel cell included in the cell group.

It is a figure which shows schematic structure of the fuel cell apparatus which is one embodiment of this invention. It is a block diagram which shows roughly the cell abnormality detection apparatus connected to one cell group which comprises the fuel cell stack of FIG. It is a partial expanded sectional view of one fuel battery cell which constitutes a fuel cell stack. It is a flowchart which shows the process sequence performed with a cell abnormality detection apparatus. It is a graph which shows the relationship between the cell number n which comprises a cell group, and the cell impedance upper limit Zlim by using the number m of reverse electric potential generation cells as a parameter. It is a graph which shows a mode that an average cell impedance increases when a reverse electric potential state arises with progress of time.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like.

  FIG. 1 is a diagram showing a schematic configuration of a fuel cell device 10 according to an embodiment of the present invention, and FIG. 2 is a detection of a cell abnormality connected to one cell group 18 constituting the fuel cell stack 12 of FIG. 2 is a block diagram schematically showing the device 50. FIG.

  The fuel cell device 10 includes a fuel cell stack 12, a fuel gas supply / discharge unit 14 connected to the fuel cell stack 12, an oxidant gas supply / discharge unit 16 connected to the fuel cell stack 12, and a fuel cell stack 12. An electrically connected fuel cell cell abnormality detection device (hereinafter simply referred to as a “cell abnormality detection device”) 50 is provided.

  The fuel cell stack 12 includes two cell groups 18 connected in series connected in the stacking direction indicated by the arrow A direction, and end plates 20 and 22 provided at both ends of the two cell groups 18 in the stacking direction. The fuel gas supply / discharge part 14 is connected to the end plate 20 at one end in the stacking direction, and the oxidant gas supply / discharge part 16 is connected to the end plate 22 at the other end in the stacking direction.

  As shown in FIG. 2, the cell group 18 is configured by connecting a large number of fuel cells 24 stacked in the direction of arrow A in series. The number of fuel cells 24 included in each cell group 18 may be the same or different. In addition, the fuel cell stack 12 may be configured by only one cell group 18 or may be configured by connecting three or more cell groups 18 in series.

  Referring also to FIG. 3, the fuel cell 24 includes an electrolyte membrane 26, two catalyst layers 28 provided with the electrolyte membrane 26 sandwiched from both sides in the stacking direction, and a sandwich structure of the electrolyte membrane 26 and the catalyst layer 28. Two gas diffusion layers 30 sandwiched from both sides in the stacking direction, and two separators 32 sandwiched between the electrolyte membrane 26, the catalyst layer 28, and the gas diffusion layer 30 from both sides in the stacking direction. It is configured.

  The electrolyte membrane 26 can be suitably formed by a membrane made of a polymer material that exhibits proton conductivity in a wet state. The catalyst layer 28 is formed as a layer having conductivity and air permeability, and platinum, a platinum alloy, or the like is preferably used as the catalyst. The gas diffusion layer 30 is formed as a layer having conductivity and air permeability, and diffuses the fuel gas and oxidant gas supplied to the fuel battery cell 24 in the cell surface direction (direction perpendicular to the paper surface of FIG. 2). It has the function to let it pass. The catalyst layer 28 and the gas diffusion layer 30 may be formed as a single layer or an integral layer.

  The separator 32 is made of, for example, a flat plate made of metal such as stainless steel, and a plurality of groove-like gas passages 34 and cooling water passages 35 are formed. The cooling water channel 35 is formed in cooperation with the separator 32 of the adjacent fuel cell 24, and the fuel cells 24 on both sides in the stacking direction are cooled by the cooling water flowing therethrough. In addition, the separator 32 is formed of a conductive metal plate, thereby functioning as a conductive plate or an electrode plate that electrically connects two adjacent fuel cells 24 to each other.

  In FIG. 3, the catalyst layer 28, the gas diffusion layer 30, and the separator 32 positioned on one side (for example, the upper side) of the electrolyte membrane 26 with respect to the stacking direction constitute the fuel electrode 37, and the other side (for example, the lower side) of the electrolyte membrane 26. The catalyst layer 28, the gas diffusion layer 30, and the separator 32, which are located at ()) constitute the oxidant electrode 39.

  Referring to FIG. 1 again, the fuel gas supply / discharge section 14 connected to the end plate 20 includes a fuel gas supply pipe 15a and a fuel gas discharge pipe 15b. For example, hydrogen is preferably used as the fuel gas. Although not shown, the fuel gas supply / discharge section 14 further stores a circulation flow path connecting the fuel gas supply pipe 15a and the fuel gas discharge pipe 15b, a fuel gas circulation pump provided in the circulation path, and fuel gas. Waste fuel gas discharged from the fuel cell stack 12 via the fuel gas tank, the pressure regulating valve and pressure gauge provided in the middle of the fuel gas supply pipe 15a connecting the fuel gas tank and the fuel cell stack 12, and the fuel gas discharge pipe 15b A purge valve that is opened when discharging to the outside may be included.

  The oxidant gas supply / discharge section 16 connected to the other end plate 22 includes an oxidant gas supply pipe 17a and an oxidant gas discharge pipe 17b. For example, oxygen contained in air is preferably used as the oxidant gas. Although not shown, the oxidant gas supply / discharge unit 16 is supplied to the fuel cell stack 12 via an air compressor for sending air taken from outside air to the oxidant gas supply pipe 17a and the oxidant gas supply pipe 17a. A humidifier that moderately humidifies the air to be supplied, an on-off valve and a pressure gauge provided in the pipe 17a, etc., a diluter connected to the oxidant gas discharge pipe 17b, and the like may be included.

  In the above description, the fuel gas supply / discharge part 14 is connected to the end plate 20 and the oxidant gas supply / discharge part 16 is connected to the end plate 22. You may comprise so that it may be connected to the end plate 20 or 22 of an edge part.

  On the side of the cell group 18 of the fuel cell stack 12, power output terminals 36 and 38 are provided for collectively outputting the power generated by each fuel cell 24. The output terminals 36 and 38 are electrically connected to the separator 32 of the fuel cell 24 closest to the end plates 20 and 22. The cell group 18 is provided with detection terminals 40, 42, 44 that are electrically connected to the cell abnormality detection device 50. The two detection terminals 40 and 44 are electrically connected to the separator 32 of the fuel cell 24 closest to the end plates 20 and 22, and the one detection terminal 42 in the middle of the stacking direction is at the boundary between the two cell groups 18. It is electrically connected to the corresponding separator 32.

  The power generation operation in the fuel cell stack 12 configured as described above will be described. Hydrogen, which is a fuel gas, is supplied to the fuel cell stack 12 from the fuel gas supply pipe 15a. Then, hydrogen is sent to the gas flow path 34 on the fuel electrode 37 side of each fuel cell 24 through a fuel gas manifold formed in each cell group 18 of the fuel cell stack 12.

  On the other hand, air containing oxygen, which is an oxidant gas, is appropriately humidified when passing through the humidifier and is supplied into the fuel cell stack 12 from the oxidant gas supply pipe 17a. Then, the air is sent to the gas flow path 34 on the oxidant electrode 39 side of each fuel cell 24 through the oxidant gas manifold formed in each cell group 18 of the fuel cell stack 12.

  Part of the hydrogen supplied to the fuel electrode 37 of the fuel battery cell 24 passes through the gas diffusion layer 30 while diffusing and reaches the catalyst layer 28, where it releases electrons by contacting with a catalyst such as platinum. As a result, protons are generated. The electrons emitted at this time become electromotive force in each fuel cell 24, current flows between the power output terminals 36 and 38 of the fuel cell stack 12, and as a result, power generation is performed in the fuel cell stack 12. Become.

  The protons are conducted from the fuel electrode 37 to the oxidant electrode 39 in the electrolyte membrane 26 which is in a wet state by the humidified air. And the said proton couple | bonds with the oxygen ion which ionized by receiving an electron in an oxidizing agent electrode, and water is produced | generated. This produced water is discharged together with the waste air from the fuel cell stack 12 to the oxidant gas discharge pipe 17b.

  Waste hydrogen after being used for power generation in each fuel cell 24 is discharged from the fuel cell stack 12 to the fuel gas discharge pipe 15b. However, since it still contains high-concentration hydrogen, the fuel gas supply pipe is provided by a circulation pump. The fuel cell stack 12 is circulated and supplied from 15a. Then, the purge valve is opened at a predetermined timing when the concentration of hydrogen in the waste hydrogen decreases and the amount of produced water as an impurity increases, so that it is discharged to the outside of the fuel cell device 10. At this time, the waste hydrogen is preferably discharged outside the apparatus after being diluted by the waste air sent from the fuel cell stack 12 through the oxidant gas discharge pipe in the diluter.

  During the power generation operation as described above, for example, due to a cause such as insufficient humidification of air, excessive temperature rise, or insufficient gas supply, the inversion state in which the potential relationship between the fuel electrode 37 and the oxidant electrode 39 in the fuel cell 24 is reversed. May be. When such a reversal state or a reverse potential state occurs, water contained in the electrolyte membrane 26 is electrolyzed and the electrolyte membrane 26 is dried, whereby the electric resistance is α times (for example, several times to 10 times). To a large extent). If the power generation operation of the fuel cell stack 12 is continued in this state, the electrolyte membrane 26 of the fuel cell 24 in the above-described inversion state may be damaged. Therefore, it is necessary to accurately detect that such an abnormal state of the fuel battery cell 24 has occurred and deal with it.

  On the other hand, if the output voltage or cell impedance of all the fuel cells 24 of the fuel cell stack 12 is detected and monitored, it is necessary to individually provide a voltage sensor and an impedance sensor for each fuel cell 24, The configuration of the fuel cell device becomes complicated.

  Therefore, in the fuel cell device 10 of the present embodiment, the cell abnormality detection device 50 is provided in order to accurately detect an abnormal state such as the inversion of the fuel cell 24 as described above with a simple configuration.

  Next, the cell abnormality detection device 50 in the present embodiment will be described with reference to FIG. Cell abnormality detection device 50 includes an alternating current application unit 52, a measurement unit 54, a calculation unit 56, and a determination unit 58. The cell abnormality detection device 50 is provided for each cell group 18. However, at least one of the portions that can be used in common for the plurality of cell groups 18, for example, at least one of the AC voltage application unit 52, the calculation unit 56, and the determination unit 58 is larger than the number of the cell groups 18 included in the fuel cell stack 12. It may be less. Thereby, the structure of the cell abnormality detection apparatus 50 in the fuel cell apparatus 10 can be simplified.

  The alternating current application unit 52 has a function of passing a weak alternating current of about several mA, for example, to the cell group 18 and is located at both ends of the cell group 18 in the stacking direction via the inspection terminals 40 and the like. The separator 32 is electrically connected. The alternating current application unit 52 may incorporate an alternating current power supply or may be connected to an external alternating current power supply.

  The measurement unit 54 has a function of measuring the impedance (hereinafter referred to as cell group impedance) Zgroup of the cell group 18 when an AC voltage is applied to the cell group 18 by the AC current application unit 52, and the inspection terminal 40 and the like. It is electrically connected to the separators 32 located at both ends in the stacking direction of the cell group 18 via (or a terminal different from the terminal to which the alternating current application unit 52 is connected). As the measurement unit 54, an AC milliohm sensor or the like that obtains impedance by measuring an alternating voltage when an alternating current is applied can be suitably used.

  The calculation unit 56 and the determination unit 58 are electrically connected to the measurement unit 54 through a signal line, and are configured to receive the cell group impedance Zgroup from the measurement unit 54. The calculation unit 56 includes a cell group impedance Zgroup of the cell group 18 measured by the measurement unit 54, an impedance increase rate α in the fuel cell 24 in which a cell abnormality has occurred, a cell impedance Za per cell at a normal potential, It has a function of calculating and obtaining a cell impedance upper limit value Zlim based on the defined number of abnormal cells m and the number of cells n constituting the cell group 18. Specifically, the calculation unit 56 calculates the cell impedance upper limit value Zlim by the following equation. In the following equation, the left term “αmZa” on the upper side is the impedance value of the fuel cell 24 in the inversion state, and the right term “(nm) Za” on the upper side is the value of the fuel cell 24 in the normal potential state. Total impedance value. Therefore, the upper side “αmZa + (n−m) Za” corresponds to the cell group impedance in the cell group 18 in which the inversion state is assumed to occur in the m fuel cells 24. By dividing this cell group impedance by the number of cells n, a cell impedance upper limit value Zlim per cell is obtained.

  The calculation unit 56 can be suitably configured by a microcomputer including a CPU (Central Processing Unit) and a memory, and the function may be executed by a part of software executed in the CPU. However, it is not limited to this, The calculating part 56 may be implement | achieved by the hardware element.

  The impedance increase rate α is stored in advance in the memory, and a constant obtained experimentally or empirically is used. For example, the impedance increase rate α may be “10” although it varies depending on the material constituting the electrolyte membrane 26.

  Values stored in advance in the memory are also used for the cell impedance Za per cell at the normal potential, the number m of abnormal cells, and the number n of cells constituting the cell group 18. The cell impedance Za per cell at the normal potential is a known value obtained experimentally or empirically. The number n of cells constituting the cell group 18 is a known value determined by the configuration of the fuel cell stack 12.

  Further, the number m of abnormality occurrence cells is defined in advance as “1”, for example. As is clear from FIG. 5, the cell impedance upper limit Zlim tends to increase as the number m of abnormal cells increases as 1, 2, 3, 4, 5,. This is because the abnormality occurrence state of the fuel cell 24 can be detected more accurately by setting the number n of abnormality occurrence cells having the minimum value Zlim to “1”. However, as described above, the number m of abnormal cells is not limited to “1”. For example, it is not less than “2” for the reason that it is not determined that a cell abnormality has occurred due to a measurement error by the measurement unit 54. It may be set to a value.

  The determination unit 58 can be configured by the same microcomputer as that constituting the calculation unit 56, but may be configured by another microcomputer or by a hardware element such as a comparator. May be.

  In the determination unit 58, the average cell impedance Z obtained by dividing the cell group impedance Zgroup transmitted from the measurement unit 54 by the number of cells n is compared with the cell impedance upper limit value Zlim, and an abnormality occurs in the fuel cell 24. A function of determining the presence or absence of In this embodiment, as will be described later, the average cell impedance Z and the cell impedance upper limit value Zlim are subtracted from the cell impedance fluctuation value Zb or compared or compared to determine whether or not a cell abnormal state has occurred. Instead, the average cell impedance Z and the cell impedance upper limit Zlim may be directly compared to determine whether or not a cell abnormality has occurred.

  In the above description, the average cell impedance Z is calculated by the determination unit 58. However, the average cell impedance Z is not limited to this, and is obtained by dividing the cell group impedance Zgroup by the number n of cells in the measurement unit 54. The average cell impedance Z may be transmitted from the measurement unit 54 to the determination unit.

  Next, the operation of the cell abnormality detection device 50 having the above configuration will be described with reference to FIGS. FIG. 4 is a flowchart showing a processing procedure executed by the cell abnormality detection device 50, and FIG. 6 shows how the average cell impedance increases with time when a inversion state (reverse potential state) occurs. It is a graph. This processing procedure is executed, for example, every predetermined time when the fuel cell stack 12 is operated continuously or intermittently.

  First, in step S10, the calculation unit 56 calculates the cell impedance upper limit value Zlim by the above formula. This cell impedance upper limit value Zlim is stored in the memory.

  Next, in step S <b> 12, the alternating current application unit 52 applies an alternating current to the cell group 18. Since this alternating current is a weak current, it does not affect the power generation operation of the fuel cells 24 included in the cell group 18.

  In subsequent step S <b> 14, the measurement unit 54 measures the cell group impedance Zgroup at both ends of the cell group 18 in the stacking direction. Then, the measurement unit 54 transmits the cell group impedance Zgroup to the determination unit 58.

  Subsequently, in step S <b> 16, the determination unit 58 divides the cell group impedance Zgroup received from the measurement unit 54 by the number n of cells in the cell group 18 to obtain an average cell impedance Z per cell.

  In step S18, the determination unit 58 compares the average cell impedance Z with a threshold value Zthr that is a value obtained by subtracting the cell impedance fluctuation value Zb from the cell impedance upper limit value Zlim. As a result, when the average cell impedance Z exceeds the threshold value Zthr, it is determined in step S20 that there is a fuel cell 24 in which a cell abnormality or a reverse potential state has occurred. Then, the cell abnormality determination process ends.

  Referring to FIG. 6, when a cell abnormality occurs in one or a plurality of fuel cells 24 and the electrolyte membrane 26 and the catalyst layer 28 are in a dry state, the average cell impedance Z which is the value of Za at the normal potential is the time t1. It shows how it suddenly grows. In this way, it is detected that a cell abnormality has occurred in the fuel cell stack 12 at the time t2 when the average cell impedance Z rapidly increases and exceeds the threshold value Zthr.

  On the other hand, when the average cell impedance Z does not exceed the threshold value Zthr in step S18, that is, when the average cell impedance Z is equal to or less than the threshold value Zthr, the process returns to step S12 and the processes of steps S12 to S18 are repeatedly executed.

  As described above, according to the cell abnormality detection device 50 of the present embodiment, when a cell abnormality such as inversion occurs, the electrolyte membrane 26 and the catalyst layer 28 included in the fuel battery cell 24 are dried and the impedance is rapidly increased. The cell impedance upper limit value Zlim is obtained in consideration of the characteristics, and the occurrence of cell abnormality in the fuel cell 24 constituting the cell group 18 is determined by comparison with this, so that the fuel cell 24 in the two cell groups 18 Even when the inversion state occurs at the same time, it is possible to accurately detect the occurrence of an abnormality in the fuel cell 24 included in the cell group 18.

  In the cell abnormality detection device 50 of the present embodiment, the average cell impedance Z is compared with the threshold value Zthr, which is a value obtained by subtracting the cell impedance fluctuation value Zb from the cell impedance upper limit value Zlim, and the abnormality of the fuel cell 24 is detected. The presence or absence of occurrence is determined. Thus, by considering the cell impedance fluctuation value Zb, it is possible to determine and detect the occurrence of abnormality of the fuel cell 24 earlier.

  When it is detected that a cell abnormality has occurred in the fuel cell 24 as described above, the fuel cell stack 10 increases, for example, the humidification of the air supplied to the fuel cell stack 12 in the fuel cell device 10. At least one protective measure such as increasing the cooling performance of a cooling means (not shown) for cooling 12, increasing the supply amount of fuel gas or the like, or stopping the power generation operation may be taken.

  DESCRIPTION OF SYMBOLS 10 Fuel cell apparatus, 12 Fuel cell stack, 14 Fuel gas supply discharge part, 15a Fuel gas supply pipe, 15b Fuel gas discharge pipe, 16 Oxidant gas supply discharge part, 17a Oxidant gas supply pipe, 17b Oxidant gas discharge pipe , 18 cell group, 20, 22 end plate, 24 fuel cell, 26 electrolyte membrane, 28 catalyst layer, 30 gas diffusion layer, 32 separator, 34 gas flow path, 35 cooling water flow path, 36, 38 power output terminal, 37 Fuel electrode, 39 Oxidant electrode, 40, 42, 44 detection terminal, 50 cell abnormality detection device, 52 AC current application unit, 54 measurement unit, 56 calculation unit, 58 determination unit, m number of abnormal cells, n cell group Cell number, Z average cell impedance, Za cell impedance, Zb cell impedance fluctuation value, Zgroup cell group impedance Dance, Zlim cell impedance limit, Zthr threshold, alpha impedance increase rate.

Claims (7)

An alternating current application unit for applying an alternating current to one or a plurality of cell groups each formed by stacking a plurality of fuel cells each including an electrolyte membrane and connected in series;
A measurement unit for measuring the impedance of the cell group when the alternating current is applied;
The cell group impedance measured by the measurement unit, the impedance increase rate in the cell where the cell abnormality has occurred, the cell impedance per cell at the normal potential, the number of abnormal cells defined in advance, and the cell group are configured A calculation unit that calculates a cell impedance upper limit value based on the number of cells, and
A determination unit that determines whether or not an abnormality has occurred in a fuel cell by comparing an average cell impedance obtained by dividing the cell group impedance by the number of cells and the cell impedance upper limit value;
A cell abnormality detection device for a fuel cell. The cell abnormality detection device for a fuel cell according to claim 1,
The determination unit determines that a cell abnormality has occurred in the fuel cell when the average cell impedance exceeds a value obtained by subtracting a cell impedance fluctuation value generated during normal operation from the cell impedance upper limit value. A cell abnormality detection device for a fuel cell. The cell abnormality detection device for a fuel cell according to claim 1 or 2,
A cell abnormality detection device for a fuel cell, wherein the number of abnormality occurrence cells used in the arithmetic unit is defined as 1 in advance. A cell abnormality detection device for a fuel cell according to any one of claims 1 to 3,
A fuel cell stack having at least one cell group to which the cell abnormality detection device of the fuel cell is connected;
A fuel gas supply / discharge section for supplying fuel gas to the fuel cell stack and discharging waste fuel gas;
An oxidant gas supply / discharge section for supplying oxidant gas to the fuel cell stack and discharging waste oxidant gas;
A fuel cell device comprising: A step of applying an alternating current to a cell group in which a plurality of fuel cells each including an electrolyte membrane are stacked and connected in series;
A measurement step of measuring the impedance of the cell group when the alternating current is applied;
The cell group impedance measured by the measurement unit, the impedance increase rate in the cell where the cell abnormality has occurred, the cell impedance per cell at the normal potential, the number of abnormal cells defined in advance, and the cell group are configured A calculation step for calculating a cell impedance upper limit value based on the number of cells,
A determination step of determining the presence or absence of occurrence of abnormality of the fuel cell by comparing the average cell impedance obtained by dividing the cell group impedance by the number of cells and the cell impedance upper limit value;
A cell abnormality detection method for a fuel cell, comprising: The cell abnormality detection method for a fuel cell according to claim 5,
In the determination step, it is determined that a cell abnormality has occurred in the fuel cell when the average cell impedance exceeds a value obtained by subtracting a cell impedance fluctuation value generated during normal operation from the cell impedance upper limit value. A method for detecting a cell abnormality in a fuel cell. The cell abnormality detection method for a fuel cell according to claim 5 or 6,
The cell abnormality detection method for a fuel cell, wherein the number of abnormality-occurring cells used in the calculation step is defined as 1 in advance.

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