JP4647293B2 - Fuel cell monitoring apparatus and monitoring method - Google Patents

Description

  The present invention relates to a monitoring device and a monitoring method for a fuel cell in which a plurality of cells each having an anode and a cathode are connected in series.

  In recent years, fuel cells have attracted attention as a new power source for automobiles. The fuel cell has, for example, a stack structure in which a plurality of cells are stacked. Here, each of the cells includes a solid polymer electrolyte membrane, a membrane electrode structure (MEA) having an anode electrode (anode) and a cathode electrode (cathode) disposed on both sides of the electrolyte membrane, and the membrane. A pair of separators sandwiching the electrode structure.

  When gas fuel (for example, hydrogen gas) is supplied to the anode electrode of this fuel cell and oxidant gas (for example, air containing oxygen) is supplied to the cathode electrode, power is generated by an electrochemical reaction. Since only harmless water is generated at the time of power generation, fuel cells are attracting attention from the viewpoint of environmental impact and utilization efficiency.

  By the way, in the fuel cell described above, it is important to monitor the power generation status of each cell in order to obtain sufficient power to drive the automobile. Therefore, the following fuel cell performance monitoring method has been proposed (see Patent Document 1).

In this performance monitoring method, first, a plurality of fuel cells connected in series are divided into at least two groups, the voltages of each group are measured, and then the measured voltages are normalized. Next, these normalized values are compared with a predetermined reference value, or the normalized values are compared with each other. Thereby, a danger level can be judged for every cell group.
Japanese National Patent Publication No. 5-502973

  However, the performance monitoring method described above has a problem that it is difficult to accurately compare the measured voltages because a calculation error occurs when normalizing the voltages of the cell groups.

  Therefore, an object of the present invention is to provide a fuel cell monitoring device and a monitoring method capable of accurately comparing the voltages of cell groups.

A fuel cell monitoring apparatus according to claim 1 (for example, monitoring apparatus 30 in the embodiment) includes a cell having an anode (for example, an anode electrode in the embodiment) and a cathode (for example, a cathode electrode in the embodiment). A monitoring device for a fuel cell that monitors a plurality of fuel cells (for example, the fuel cell 1 in the embodiment) in which a plurality of cells (for example, the cells 2 in the embodiment) are connected in series, wherein two or more of the cells are One cell group (for example, cell groups 40a and 40b in the embodiment), voltage detection means (for example, voltage detection unit 31 in the embodiment) for detecting a voltage for each of these cell groups, and each of the cell groups by comparing the detected values with each other, wherein the specification means voltages of cell groups are identified as a specific cell group lower cell group (e.g., the comparison section 321 in the embodiment), before The detection value of the detection value and the specific cell group of the cell group, and normalization means for normalizing by dividing the number of cells constituting the cell group (e.g., the normalization unit 322 in the embodiment), the It is characterized by providing.

  According to the present invention, first, the voltage detection means detects the voltage for each cell group. Next, in the specifying means, the detected values of the detected cell groups are compared with each other, and a specific cell group with a specific voltage is specified. Subsequently, the detection value of the cell group and the detection value of the specific cell group are normalized by the normalizing means. Therefore, since the detection values are normalized after the detection values are compared, the voltages of the cell groups can be accurately compared.

The fuel cell monitoring device according to claim 2 is the fuel cell monitoring device according to claim 1, wherein after the specific cell group is specified and before the detected value is normalized, the specific cell group A danger level judgment means for judging the danger level of the fuel cell by comparing the detected value with a reference value set for the voltage of the cell group according to the danger level of the fuel cell (for example, an embodiment) And a fuel cell control unit 323).

  In the conventional performance monitoring method, since the voltage of the cell group is measured and then compared after normalization, the processing for determining the risk level of the cell group is burdened by the time required for the calculation of normalization. There is a problem. However, according to the present invention, the detection value of the specific cell group is compared with the reference value without normalization, and the risk level is determined. Therefore, the process for determining the risk level of the cell group can be reduced.

The method for monitoring a fuel cell according to claim 3 is a method for monitoring a fuel cell in which a plurality of cells each having an anode and a cathode are connected in series, wherein two or more of the cells are defined as one cell group. A procedure for detecting a voltage for each cell group, a procedure for comparing the detection values of these cell groups, and specifying a cell group having a lower voltage among the cell groups as a specific cell group, and detection of the cell group And a procedure of normalizing the value and the detected value of the singular cell group by dividing the value by the number of cells constituting the cell group . According to this invention, since the detected values are normalized after comparing the detected values, the voltages of the cell groups can be compared accurately.

The method for monitoring a fuel cell according to claim 4 is the method for monitoring a fuel cell according to claim 3, wherein the specific cell group is detected after the specific cell group is specified and the detected value is normalized. The method further comprises a step of comparing the value and a reference value set for the voltage of the cell group according to the danger level of the fuel cell to determine the danger level of the fuel cell. According to the present invention, since the risk level is determined by comparing the detection value of the specific cell group and the reference value without normalization, the process of determining the risk level of the cell group can be reduced.

  According to the first and third aspects of the invention, the voltages of the cell groups can be accurately compared. According to the inventions according to claims 2 and 4, it is possible to reduce the process of determining the risk level of the cell group.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a fuel cell monitoring system 10 to which a monitoring device 30 according to an embodiment of the present invention is applied. The fuel cell monitoring system 10 includes a fuel cell 1, a supply device 20 that supplies hydrogen and air to the fuel cell 1, and a monitoring device 30 that controls the supply device 20.

  FIG. 2 is a schematic sectional view of the fuel cell 1. As shown in FIG. 2, the fuel cell 1 has a stack structure in which n (for example, 220) cells 2 are stacked. Each cell 2 includes a membrane electrode structure (MEA) 3 and a pair of separators 4 and 5 that sandwich the membrane electrode structure 3.

  As shown in FIG. 2, the above-described cell 2 includes three types of a first cell 2 a, a second cell 2 b, and a third cell 2 c. Specifically, the first cell 2a (2) has a voltage measuring terminal 6 on the separator 4 on the anode electrode (not shown) side as an anode. The second cell 2b (2) has a voltage measurement terminal 7 on a separator 5 on the cathode electrode (not shown) side as a cathode. The third cell 2c (2) has no terminal in either of the separators 4 and 5.

  The first cell 2a and the third cell 2c are alternately stacked on the positive electrode side from the center of the fuel cell 1, and the second cell 2b and the third cell 2c are alternately stacked on the negative electrode side from the center. Is laminated. Here, two of the cells 2 are defined as one cell group. Specifically, the first cell 2a and the third cell 2c arranged on the positive electrode side from the center are defined as a cell group 40a, and the second cell 2b and the third cell arranged on the negative electrode side from the center Let 2c be the cell group 40b.

  At this time, the electrodes facing each other in the cells 2a and 2c and the cells 2b and 2c adjacent in the stacking direction have the same potential. Specifically, for example, the potential of the cathode electrode of the first cell 2a located at the end on the positive electrode side is the same as the potential of the anode electrode of the third cell 2c adjacent thereto.

  Returning to FIG. 1, the supply device 20 includes a compressor 21 that supplies air containing oxygen to the cathode electrode side of the cell 2, a hydrogen tank 22 that supplies hydrogen gas to the anode electrode side of the cell 2, and an ejector 23. Consists of.

  The compressor 21 is connected to an oxidant gas passage (not shown) formed in the separator 5 of the fuel cell 1 via an oxidant gas supply pipe 24. An oxidant gas discharge pipe 25 is connected to the oxidant gas passage of the fuel cell 1, and a back pressure valve 26 that adjusts the internal pressure on the cathode electrode side of the fuel cell 1 is connected to the tip of the oxidant gas discharge pipe 25. Is provided.

  The hydrogen tank 22 is connected to a fuel gas passage (not shown) formed in the separator 4 of the fuel cell 1 via a fuel gas supply pipe 27. Further, a fuel gas discharge pipe 28 is connected to the fuel gas passage of the fuel cell 1, and the fuel gas discharge pipe 28 is closed by a purge valve 29 provided at the tip. The ejector 23 is provided in the middle of the fuel gas supply pipe 27, and returns the hydrogen gas that has flowed to the fuel gas discharge pipe 28 to the fuel gas supply pipe 27.

  FIG. 3 is a block diagram of the monitoring device 30. The monitoring device 30 includes a voltage detection unit 31, a calculation unit 32, and a storage unit 33 as voltage detection means.

  The voltage detector 31 detects a voltage for each of the cell groups 40a and 40b. Specifically, the voltage detection unit 31 includes a plurality of connectors 8 and 9, and the connector 8 is connected to the terminal 6 of the first cell 2a, and the connector 9 is connected to the terminal 7 of the second cell 2b. Connected to. On the positive electrode side from the center of the fuel cell 1, the potential difference between the anode electrodes of the first cells 2a adjacent to each other is obtained to detect the voltage of the cell group 40a. The voltage of the cell group 40b is detected by obtaining the potential difference of the cathode electrode of the cell 2b.

  The calculation unit 32 compares the detection values of the cell groups 40a and 40b and compares the comparison unit 321 as a specifying unit for specifying a specific cell group having a specific detection value among the cell groups 40a and 40b, and the cell group 40a, The normalization unit 322 as normalizing means for normalizing the detection value of 40b and the detection value of the specific cell group, and the detection value of the specific cell group and the reference value are compared to determine the danger level of the fuel cell 1. A fuel cell control unit 323 is provided as a danger level determination means for controlling the fuel cell 1 in accordance with these danger levels.

  Each time the comparison unit 321 receives a detection value from the voltage detection unit 31, the comparison unit 321 compares the received detection value with VLOW, sets the lower value to VLOW, compares the detection value with VHIGH, Let the value be VHIGH. In addition, the comparison unit 321 sets a cell group in which VLOW is detected among the cell groups 40a and 40b as a specific cell group, further sets the final VLOW as WORST, and sets the final VHIGH as BEST.

  The normalization unit 322 normalizes all VLOWs and detection values in addition to WORST and BEST. That is, these values are divided by the number of cells 2 constituting the cell groups 40a and 40b.

  The fuel cell control unit 323 compares the VLOW with three types of reference values to determine the danger level, and controls the cell groups 40a and 40b in which the VLOW is detected according to the danger level. Specifically, the fuel cell control unit 323 controls the compressor 21, the back pressure valve 26, and the purge valve 29.

  Here, the three types of reference values for determining the danger level are values calculated by doubling the reference value of a single cell, and are a third reference value, a second reference value, and a first reference value. In order of the reference value. Further, when the voltage is less than the third reference value, the danger level 3 is set, and when the voltage is greater than or equal to the third reference value and less than the second reference value, the danger level 2 is set. When the voltage is greater than or equal to the second reference value and less than the first reference value, the danger level is 1, and when the voltage is greater than or equal to the first reference value, the danger level is 0. That is, the danger level is the lowest at level 0 and the highest at level 3. In the fuel cell control unit 323, the control contents for the cell groups 40a and 40b differ according to these danger levels 0 to 3.

  The operation of the fuel cell monitoring system 10 will be described. In the fuel cell 1, fuel gas (for example, hydrogen gas) is supplied to the anode electrode through the fuel gas passage, and oxidant gas (for example, air containing oxygen) is supplied to the cathode electrode through the oxidant gas passage. Then, hydrogen is ionized by the catalyst layer (not shown) of the anode electrode, and moves to the cathode electrode side through the solid polymer electrolyte membrane (not shown). Electrons generated during this time are taken out to an external circuit and used as direct current electric energy. At this time, hydrogen ions, electrons, and oxygen react to generate water.

  Next, the operation of the monitoring device 30 will be described with reference to FIG. First, the voltage detection unit 31 detects the voltages of the cell groups 40a and 40b in order from one end side. For example, here, detection is performed from the + pole side (ST1).

  Next, the comparison unit 321 of the calculation unit 32 receives the detection value from the voltage detection unit 31, compares the detection value with VLOW and VHIGH, and calculates VLOW and VHIGH (ST2). Since VLOW and VHIGH do not exist at the beginning, the two detection values are compared, and the lower value is VLOW and the higher value is VHIGH. Moreover, the cell group in which this VLOW is detected among the cell groups 40a and 40b is defined as a specific cell group.

  Subsequently, the fuel cell control unit 323 controls the fuel cell 1 based on VLOW (ST3). Hereinafter, a specific procedure in ST3 will be described with reference to FIG. First, it is determined whether or not VLOW is greater than or equal to a third reference value (ST31). If it is determined that VLOW is not greater than or equal to the third reference value, the specific cell group in which VLOW is detected is controlled as the risk level 3 (ST32). On the other hand, if it is determined that VLOW is greater than or equal to the third reference value, the process proceeds to ST33.

  In ST33, it is determined whether or not VLOW is greater than or equal to the second reference value. If it is determined that VLOW is not equal to or greater than the second reference value, the specific cell group in which VLOW is detected is controlled as the risk level 2 (ST34). On the other hand, if it is determined that VLOW is greater than or equal to the second reference value, the process proceeds to ST35. In ST35, it is determined whether or not VLOW is equal to or greater than a first reference value. If it is determined that VLOW is not greater than or equal to the first reference value, control is performed with the specific cell group in which VLOW is detected as the risk level 1 (ST36). On the other hand, when it is determined that VLOW is equal to or higher than the first reference value, the control is performed with the danger level 0.

  The above ST1 to ST3 are repeated. Thus, VLOW is calculated every time the voltage of the fuel cell 1 is detected, and the fuel cell 1 is controlled based on this VLOW. That is, from the one end side of the fuel cell 1 to the other end side, the voltage of all the cell groups 40a and 40b is sequentially detected, and at the same time, VLOW is calculated one after another to control the fuel cell 1.

  Next, the comparison unit 321 sets final VLOW to WORST and final VHIGH to BEST (ST4), and the normalization unit 322 normalizes WORST, BEST, all VLOWs, and detection values (ST5). ). Then, the value normalized in ST5 is stored in the storage unit 33 (ST6).

  According to this embodiment, there are the following effects. Since the monitoring device 30 includes the voltage detection unit 31, the calculation unit 32, and the storage unit 33, the monitoring device 10 operates as follows. First, the voltage detector 31 detects a voltage for each of the cell groups 40a and 40b. Next, the comparison unit 321 compares the detected values of the detected cell groups 40a and 40b to identify a specific cell group with a specific voltage. Subsequently, the normalization unit 322 normalizes the detection values of the cell groups 40a and 40b and the detection value of the specific cell group. Therefore, since the detected values are normalized after comparing the detected values, the voltages of the cell groups 40a and 40b can be accurately compared.

  Since the monitoring apparatus 10 is provided with the fuel cell control unit 323, the detection value of the specific cell group is not normalized and compared with the first to third reference values, and the risk level is determined. Therefore, the cell group 40a, It is possible to reduce the process of determining the risk level of 40b.

  Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope in which the object of the present invention can be achieved are included in the present invention. For example, in the present embodiment, two of the cells 2 are set as one cell group 40a, 40b. However, the present invention is not limited to this, and three or more cells 2 may be set as one cell group.

1 is a block diagram of a fuel cell monitoring system to which a monitoring device according to an embodiment of the present invention is applied. FIG. It is a schematic sectional drawing of the fuel cell which concerns on the said embodiment. It is a block diagram of the monitoring apparatus concerning the embodiment. It is a flowchart of the monitoring apparatus which concerns on the said embodiment. It is a flowchart of the danger level judgment means which comprises the monitoring apparatus which concerns on the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2, 2a, 2b, 2c ... Cell 40a, 40b ... Cell group 30 ... Monitoring apparatus 31 ... Voltage detection part (voltage detection means)
321... Comparison unit (specifying means)
322 ... Normalization unit (normalization means)
323 ... Fuel cell control unit (danger level judgment means)

Claims (4)

A fuel cell monitoring device for monitoring a fuel cell in which a plurality of cells each having an anode and a cathode are connected in series,
Two or more of the cells are defined as one cell group, and voltage detecting means for detecting a voltage for each of these cell groups;
A specifying unit which compares the detected values with each other of said groups each cell, identifying as a specific cell group the cell group of lower voltage of the cell group,
And a normalization unit that normalizes the detection value of the cell group and the detection value of the specific cell group by dividing the detection value of the cell group by the number of cells constituting the cell group. . After the specific cell group is specified and before normalizing the detection value, the reference value set for the voltage of the cell group according to the detection value of the specific cell group and the danger level of the fuel cell The fuel cell monitoring device according to claim 1, further comprising: a danger level determination unit that determines a danger level of the fuel cell by comparing with the above. A method of monitoring a fuel cell in which a plurality of cells having an anode and a cathode are connected in series,
A procedure for detecting two or more of the cells as one cell group and detecting a voltage for each of these cell groups;
A step of comparing the detected values with each other of these cell groups, to identify as a specific cell group the cell group of lower voltage of the cell group,
And a procedure of normalizing the detection value of the cell group and the detection value of the specific cell group by dividing the detection value of the cell group by the number of cells constituting the cell group . After specifying the specific cell group and before normalizing the detection value, the detection value of the specific cell group and a reference value set for the voltage of the cell group according to the danger level of the fuel cell, The method for monitoring a fuel cell according to claim 3, further comprising a step of determining a danger level of the fuel cell by comparing the two.

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