JP2008071637A - Fuel cell system, fuel cell stack inspection apparatus, and fuel cell stack abnormality determination method - Google Patents

Abstract

Provided are a fuel cell system, a fuel cell stack abnormality inspection device, and a stack abnormality determination method that accurately detect an abnormal cell in which flooding occurs during normal operation of a fuel cell or during a stack abnormality inspection in a fuel cell stack manufacturing stage. To do.
When the temperature of the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and the voltage value of one or more cells that are the objects of voltage detection at that time is below a reference value The one or more cells are determined to be abnormal.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system including a fuel cell stack in which a plurality of cells are stacked, an inspection device for detecting an abnormality in the fuel cell stack, and a method for determining an abnormality in the fuel cell stack.

  In the fuel cell system, when the power generation amount of the fuel cell decreases or the temperature of the cooling medium of the fuel cell stack decreases and the temperature of the fuel cell stack decreases, the water generated in the fuel cell stack causes the cell electrode to flow. Blocking flooding (water clogging) is likely to occur. And in the cell in which the flooding has occurred, since the gas flow is hindered, the cell voltage is lowered and the battery performance is lowered.

  When the power generation amount of the fuel cell stack suddenly decreases or the temperature of the fuel cell stack cooling medium decreases due to a decrease in the outside air temperature, and the temperature of the fuel cell stack decreases, cooling is performed to counter the temperature decrease. A technique is known in which the cooling capacity of the apparatus is controlled to effectively prevent the occurrence of flooding due to the temperature drop of the fuel cell stack (see, for example, Patent Document 1).

JP 2004-158355 A

  Here, when detecting a cell in which flooding occurs during normal fuel cell system operation or in the stack manufacturing stage, the detection sensitivity is better when the cell voltage is detected in an environment where flooding is likely to occur. Therefore, for example, a method of reducing the temperature of the fuel cell stack by reducing the amount of gas supplied to the fuel cell stack and reducing the amount of heat generated by power generation, and detecting the cell voltage in an environment where flooding is likely to occur can be considered. .

  However, when the amount of gas supplied to the fuel cell stack is reduced, the amount of gas supplied decreases as the cell is arranged in the back along the gas supply direction, and the voltage value of the cell decreases as it goes back. Then, when detecting an abnormal cell by detecting the voltage value of the cell, the cell placed in the back along the gas supply direction is detected low even if it is not abnormal. There is a problem that it is difficult to judge abnormal cells.

  The present invention relates to a fuel cell system including a fuel cell stack in which a plurality of cells are stacked, and a cooling means for cooling the fuel cell stack and a voltage of one or a plurality of cells among the cells included in the fuel cell stack. If there is at least one voltage detection means and the inside of the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and the detected voltage value by the voltage detection means is below the reference value at that time, the voltage detection And determining means for determining that one or a plurality of cells which are detection targets of the means are abnormal.

  According to the present invention, the abnormal cell detection sensitivity is improved by making the inside of the fuel cell stack easy to cause flooding, and the measured voltage value of the cell is less affected by the position where the cell is arranged. Abnormal cell detection accuracy is also improved.

  In the present invention, the cooling means includes means for supplying a cooling medium such as water to the fuel cell stack by a circulation pump or the like for cooling the fuel cell stack, and the judging means judges abnormality of one or a plurality of cells. In this case, it is preferable to set the fuel cell stack inlet temperature of the cooling medium within a range of 40 degrees to 60 degrees.

  According to such a configuration, the inside of the fuel cell stack is likely to be flooded, the detection sensitivity for detecting the cells where the flooding is generated is improved, and even in an environment where the flooding is likely to occur, For cells other than the cell, it is possible to achieve compatibility with not causing a voltage drop due to flooding.

  In the present invention, it is preferable that the judging means stops the operation of the fuel cell system when the number of abnormal cells exceeds a predetermined number.

  The present invention provides an inspection apparatus for detecting an abnormality of a fuel cell stack in which a plurality of cells are stacked, a cooling means for cooling the fuel cell stack, and a voltage of one or a plurality of cells among the cells included in the fuel cell stack. If there is at least one voltage detection means to detect and the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and if the voltage detected by the voltage detection means is below the reference value at that time, the voltage detection And determining means for determining that one or a plurality of cells which are detection targets of the means are abnormal.

  In the present invention, the cooling means includes means for supplying a cooling medium such as water to the fuel cell stack by a circulation pump or the like for cooling the fuel cell stack, and the judging means judges abnormality of one or a plurality of cells. In this case, it is preferable to set the fuel cell stack inlet temperature of the cooling medium within a range of 40 degrees to 60 degrees.

  The present invention relates to a method for determining an abnormality in a fuel cell stack in which a plurality of cells are stacked, wherein the temperature of the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and at that time, it is a target for voltage detection. When the voltage value of the one or more cells is equal to or less than the reference value, the one or more cells are determined to be abnormal.

  In the present invention, when judging the abnormality of one or a plurality of cells, the fuel cell stack inlet temperature of a cooling medium such as water for cooling the fuel cell stack is set within a range of 40 to 60 degrees. It is preferable to do.

  In the present invention, when the number of abnormal cells exceeds a predetermined number, it is preferable to stop the operation of the fuel cell system.

  According to the present invention, it is possible to accurately detect an abnormal cell in which flooding has occurred during normal operation of the fuel cell or at the stage of manufacturing the fuel cell stack.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a fuel cell system of the present invention. The fuel cell system in the embodiment of the present invention includes a fuel cell stack 10, a humidifier 12, a control unit 30, and a cooling device 80.

  The fuel cell stack 10 is configured by stacking a plurality of single cells. Each single cell has a structure in which an electrolyte membrane (for example, a polymer membrane) is sandwiched between an anode electrode and a cathode electrode, and both sides thereof are sandwiched between separators. The structure of the unit cell is the same as the unit cell structure of a fuel cell that has been widely known.

  The fuel cell stack 10 generates power by receiving supply of hydrogen gas as a fuel and air as an oxidant. In this embodiment, the circulation path of the fuel gas and the oxidant gas is configured as indicated by the arrows in FIG. 1, but it is needless to say that the present invention is not limited to this and can be variously modified.

Hydrogen gas from a hydrogen tank (not shown) is supplied to the fuel electrode (anode) of each of a plurality of cells constituting the fuel cell stack 10. Further, the air pumped by a compressor (not shown) is humidified by the humidifier 12 and supplied to the air electrodes (cathodes) of a plurality of cells constituting the fuel cell stack 10. Then, water generated by the reaction in the air electrode _{^{(2H + + 1 / 2O 2}} → H 2 O) is discharged together with the exhaust gas from the air electrode, the exhaust gas is not shown is supplied to the humidifier 12 Humidify the supply air pumped from the compressor.

  The cooling device 80 circulates a cooling medium for cooling the fuel cell stack 10 between the fuel cell stack 10 and the radiator 20 to cool the fuel cell stack 10 and diffuses the exhaust heat to the outside air. The apparatus includes a cooling water circulation pump 22, a cooling water circulation channel 24, a radiator 20, a cooling water bypass channel 26, and a flow rate adjusting three-way valve 50. In the present embodiment, the cooling medium is water, but it is needless to say that the present invention is not limited to this, and various modifications can be made.

  The cooling water is supplied to the fuel cell stack 10, cools the inside of the stack, and then is supplied to the radiator 20 through the cooling water circulation channel 24 by the cooling water circulation pump 22. The cooling water exchanges heat with the outside air in the radiator 20, and the heat is released to the outside. The flow rate adjusting three-way valve 50 is connected to the control unit 30. The three-way valve 50 for flow rate adjustment adjusts the opening degree of the valve based on a signal from the control unit 30 to arbitrarily set the flow rate of cooling water passing through the radiator 20 and the amount of cooling water flowing through the cooling water bypass passage 26. It can be adjusted in proportion.

  The cooling device 80 includes a fuel cell stack outlet side temperature sensor 42, a bypass temperature sensor 44, a radiator outlet side temperature sensor 46, and a fuel cell stack inlet side temperature sensor 48. It is connected.

  The fuel cell stack 10 is provided with a voltmeter 60, and the voltmeter 60 is connected to the control unit 30. In this embodiment, as shown in FIG. 2A, a terminal 18 is provided in each of the plurality of single cells 16 constituting the fuel cell stack 10 and connected to a voltmeter 60, and the voltage of each single cell 16 is measured. is doing. Here, in the present embodiment, the voltage is measured for each single cell 16, but the voltage may be measured for each of a plurality of cells, for example. In addition, among the cells included in the fuel cell stack 10, one or more cells near the end in the stacking direction are arranged close to the outside air side, so that the temperature is easier to cool than other cells, and flooding is performed. Is likely to occur. Therefore, the configuration may be such that only the voltage of one or a plurality of cells near the end in the stacking direction is measured, and various modifications are possible.

  In addition to the present embodiment, for example, when inspecting a stack abnormality in a fuel cell stack manufacturing stage, as shown in FIG. 2B, a plurality of single cells 16 are stacked and current is collected at both ends. A plurality of substacks 70 may be configured with the substack 70 sandwiched between the plates 68 as one structural unit, and a stack abnormality may be inspected for each substack 70. In such a case, the hydrogen gas and air supply line is branched, hydrogen gas and air are supplied to each sub-stack 70 to generate electric power, a terminal is provided on the current collector plate 68, and the generated voltage is supplied to the voltmeter 62. It can also be set as the structure measured by ~ 66. Here, the voltmeter may be provided for each single cell 16 and, of course, various modifications are possible. In addition, the sub-stacks 70 may be inspected by being connected in series or in parallel to each other, and various changes can be made.

  Here, a case where an abnormal cell in which the cell voltage is reduced due to the occurrence of flooding during normal operation of the fuel cell system is detected based on the measured voltage value of the cell will be described with reference to FIG.

  First, the control unit 30 sets the control target value of the fuel cell stack inlet side temperature to a predetermined temperature. Then, the control unit 30 determines the opening degree of the flow rate adjusting three-way valve 50 based on detection signals from the fuel cell stack outlet side temperature sensor 42, the radiator outlet side temperature sensor 46, and the bypass temperature sensor 44. Further, control is performed so as to correct the opening degree of the flow rate adjusting three-way valve 50 while feeding back a detection signal from the fuel cell stack inlet side temperature sensor 48.

  Here, it is desirable to set the control target value of the stack inlet side temperature within a range of 40 degrees to 60 degrees. When detecting an abnormal cell in which flooding has occurred, it is better to detect the cell voltage in an environment where flooding is likely to occur.However, if the stack temperature is too low, cells other than the abnormal cell will be detected. It is not preferable because the cell voltage may be lowered due to flooding. Therefore, by setting the control target value of the stack inlet side temperature within the range of 40 degrees to 60 degrees, while improving the detection sensitivity when detecting abnormal cells, and making the environment prone to flooding, For cells other than abnormal cells, it is possible to achieve compatibility with not causing a voltage drop due to flooding.

As described above, the voltage measurement value of each single cell 16 is input to the control unit 30 in a state where the fuel cell stack 10 is cooled to a temperature lower than that during normal operation. And the control part 30 judges that this single cell 16 is abnormal, when there exists the single cell 16 whose voltage measured value is below a reference value.
FIG. 3 is a graph showing voltage measurements of each single cell 16. The horizontal axis in FIG. 3 indicates that each single cell 16 is numbered along the stacking direction of the single cells 16, and the vertical axis indicates a voltage measurement value of each single cell 16. The graph of FIG. 3 indicates that the voltage measurement value of the nth single cell 16 is equal to or less than the reference value V1, and the nth single cell 16 is determined to be abnormal.

  When the number of single cells 16 determined to be abnormal by the control unit 30 exceeds a predetermined number, the control unit 30 determines that it is difficult to continue the operation of the fuel cell system due to a decrease in battery performance, and performs the operation. Stop.

  Next, the abnormality determination control routine for the fuel cell stack 10 executed by the control unit 30 will be described. FIG. 4 is a flowchart illustrating an example of an abnormality determination control routine for the fuel cell stack 10 executed by the control unit 30. This routine is repeatedly executed at predetermined time intervals during normal operation of the fuel cell system.

  First, in step S101, the control target value of the cooling water fuel cell stack inlet side temperature is set to a predetermined temperature, and the process proceeds to the next step S102. As described above, it is desirable to set the target temperature within a range of 40 degrees to 60 degrees.

  When the target value of the cooling water fuel cell stack inlet side temperature is set to a predetermined temperature in step S101, as described above, the flow rate adjusting three-way valve is set so that the cooling water fuel cell stack inlet side temperature becomes the target value. An opening of 50 is controlled.

  In step S102, it is determined whether or not the fuel cell stack inlet side temperature of the cooling water has reached the target value. If it is determined that the fuel cell stack inlet side temperature of the cooling water has reached the target value, the next step S103 is performed. When it is determined that the temperature of the cooling water fuel cell stack inlet side does not reach the target value, the flow adjustment three-way valve 50 is opened until the temperature of the cooling water fuel cell stack inlet side reaches the target value. The degree is controlled. When it is determined that the temperature of the coolant water inlet side of the cooling water has reached the target value, the process proceeds to the next step S103.

  In step S103, it is determined whether or not there is a single cell 16 whose voltage measurement value is equal to or less than the reference value V1, and when there is no single cell 16 whose voltage measurement value is equal to or less than the reference value V1, execution of this routine is performed. Then, the operation of the fuel cell system is continued as it is. On the other hand, when it is determined that there is a single cell 16 whose voltage measurement value is equal to or less than the reference value V1, the process proceeds to step S104, and the single cell 16 is determined to be abnormal, and the process proceeds to step S105.

  In step S105, it is determined whether or not there are a predetermined number or more of the single cells 16 whose voltage measurement value is the reference value V1 or less, and the number of the single cells 16 whose voltage measurement value is the reference value V1 or less is greater than the predetermined number. When the number is small, the execution of this routine is terminated and the operation of the fuel cell system is continued as it is. On the other hand, when the number of single cells 16 whose voltage measurement value is equal to or less than the reference value V1 is equal to or greater than a predetermined number, it is determined that it is difficult to continue operation due to a decrease in battery performance, and the process proceeds to step S106 to Stop operation. Here, as a matter of course, the number of abnormal cells for determining whether or not to continue operation of the fuel cell system can take various values according to the battery performance and the like.

  In the present embodiment, an example of a fuel cell system performing a normal power generation operation has been mainly described. However, for example, a stack in the fuel cell stack manufacturing stage by combining the control unit 30, the voltmeter 60, and the cooling device 80. Of course, an inspection apparatus that detects this abnormality may be configured, and various modifications are possible.

  In the present embodiment, the description will focus on an example in which the stack inlet temperature of cooling water for cooling the fuel cell stack is set to a predetermined temperature range and the stack temperature is cooled to a temperature lower than the temperature during normal operation. However, for example, the configuration may be such that the inside of the fuel cell stack is easily flooded by increasing the humidity of air, which is an oxidant gas. In this case, the air flow path passing through the humidifier and the air flow path bypassing the humidifier join together to supply air to the fuel cell stack, and adjust the amount of air passing through the humidifier to adjust the humidity in the air. Of course, the configuration may be such that various changes are possible.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

1 is a schematic configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a figure which shows the structure of the voltmeter which concerns on embodiment of this invention. It is a figure which shows the voltage measurement value of each single cell which concerns on embodiment of this invention. It is a flowchart explaining the abnormality judgment control routine of the fuel cell stack performed by the control part which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell stack, 12 Humidifier, 16 Single cell, 18 terminal, 20 Radiator, 22 Cooling water circulation pump, 24 Cooling water circulation channel, 26 Cooling water bypass channel, 30 Control part, 42 Fuel cell stack exit side temperature sensor , 44 Bypass temperature sensor, 46 Radiator outlet side temperature sensor, 48 Fuel cell stack inlet side temperature sensor, 50 Three-way valve for flow rate adjustment, 60, 62, 64, 66 Voltmeter, 68 Current collector plate, 70 Sub stack, 80 Cooling system.

Claims (8)

In a fuel cell system including a fuel cell stack in which a plurality of cells are stacked,
Cooling means for cooling the fuel cell stack;
Voltage detecting means for detecting the voltage of one or more cells among the cells included in the fuel cell stack;
When the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and when the detected voltage value by the voltage detecting means is equal to or lower than a reference value, one or a plurality of detection targets of the voltage detecting means A fuel cell system comprising: a determination unit that determines that the cell is abnormal.   The cooling means includes means for supplying a cooling medium to the fuel cell stack in order to cool the fuel cell stack, and the determination means determines the abnormality of the one or more cells when determining the abnormality of the one or more cells. The fuel cell system according to claim 1, wherein the inlet temperature of the fuel cell stack is set within a range of 40 degrees to 60 degrees.   3. The fuel cell system according to claim 1, wherein the determination unit stops the operation of the fuel cell system when the number of abnormal cells exceeds a predetermined number. In an inspection apparatus for detecting an abnormality in a fuel cell stack in which a plurality of cells are stacked,
Cooling means for cooling the fuel cell stack;
Voltage detecting means for detecting the voltage of one or more cells among the cells included in the fuel cell stack;
When the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and when the detected voltage value by the voltage detecting means is equal to or lower than a reference value, one or a plurality of detection targets of the voltage detecting means An inspection apparatus comprising: a determination unit that determines that the cell is abnormal.   The cooling means includes means for supplying a cooling medium to the fuel cell stack in order to cool the fuel cell stack, and the determination means determines the abnormality of the one or more cells when determining the abnormality of the one or more cells. The inspection apparatus according to claim 4, wherein the fuel cell stack inlet temperature is set within a range of 40 degrees to 60 degrees. In a method for determining an abnormality in a fuel cell stack in which a plurality of cells are stacked,
When the temperature of the fuel cell stack is cooled to a temperature lower than the temperature during normal operation, and the voltage value of one or a plurality of cells that are the targets of voltage detection at that time is equal to or lower than a reference value, Alternatively, it is determined that a plurality of cells are abnormal.   The fuel cell stack inlet temperature of a cooling medium for cooling the fuel cell stack is set within a range of 40 degrees to 60 degrees when determining an abnormality of the one or more cells. Item 7. The method according to Item 6.   The method according to claim 6 or 7, wherein when the number of abnormal cells exceeds a predetermined number, the operation of the fuel cell system is stopped.

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