A detection system for a fuel cell

Abstract

The present invention discloses a detection system for a fuel cell. The detection system includes: an insulation detection device for detecting the insulation state of the fuel cell; a stack airtightness detection device for detecting the airtightness of the fuel cell; and a voltage anomaly detection and failure diagnosis device for detecting and analyzing the short circuit of the fuel cell and the voltage anomaly of each cell of the fuel cell. Furthermore, the detection system for a fuel cell provided by the present invention can efficiently, non-destructively and with low risk complete the detection of the insulation, airtightness and voltage anomaly problems of the fuel cell before the ex-factory activation test, before the performance test and during the maintenance diagnosis, providing reliable, sufficient and effective data support for problem diagnosis and maintenance.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and more specifically, to a detection system for a fuel cell. Background Art

[0002] The state detection of a fuel cell is one of the important links for verifying the product quality and qualification rate of a fuel cell, and is also an important prerequisite for ensuring the smooth progress of factory activation testing and performance testing, and can also provide basic state data for the maintenance and repair of the fuel cell.

[0003] Currently, in the engineering research and development of fuel cells, for the state detection of a fuel cell stack, it is mainly limited to aspects such as insulation detection and airtightness detection, and is mainly implemented in stages such as after the stack assembly, before the performance test, or during the maintenance and repair of the stack. For insulation detection, manual methods are mostly used, and an insulation meter is used to detect the insulation resistance of the fuel cell under different states. For airtightness detection, currently, engineers also use airtightness detection equipment to detect the external leakage of the three cavities, the internal leakage of hydrogen and air, and the internal leakage of gas and water of the fuel cell stack.

[0004] In engineering research and development, after the fuel cell is assembled and passes the insulation and overall airtightness detection during factory production, there are still potential state problems, such as typical voltage abnormality problems. However, due to the lack of targeted detection, in actual engineering development work, when the fuel cell is subjected to bench testing, various problems still frequently occur, such as single-cell zero voltage, low voltage, high voltage (or negative voltage), abnormal voltage inspection information, etc., making it difficult to smoothly carry out the activation and performance testing of the stack. In addition, in the stack maintenance and repair link, due to the lack of a systematic detection method and detection device, problems such as low analysis efficiency of engineers and difficulty in clarifying the cause of the failure occur. Summary of the Invention

[0005] In view of this, the present invention provides a detection system for a fuel cell, which effectively solves the technical problems existing in the prior art, and can efficiently, non-destructively, and with low risk complete the detection of fuel cell insulation, airtightness, and voltage abnormality problems, etc. before the factory activation test, before the performance test, and during the maintenance diagnosis, and provides reliable, sufficient, and effective data support for problem diagnosis and maintenance.

[0006] To achieve the above object, the technical solution provided by the present invention is as follows:

[0007] A detection system for a fuel cell, the detection system includes a fuel cell stack to be detected, and a hydrogen gas path, an air path, and a nitrogen gas path connected to the fuel cell stack;

[0008] The hydrogen gas path includes a first flow regulating valve connected to a hydrogen gas source, a first flow meter with its input end connected to the output end of the first flow regulating valve, a second pressure sensor connected to the output end of the first flow meter, and a tenth flow regulating valve connected to the hydrogen gas outlet of the fuel cell stack. The output end of the first flow meter is connected to the anode side of the fuel cell stack;

[0009] The air path includes a second flow regulating valve connected to an air source, an eighth flow regulating valve, a third pressure sensor, and a second flow meter connected to the output end of the second flow regulating valve, and an eleventh flow regulating valve connected to the air outlet of the fuel cell stack. The output end of the second flow meter is connected to the cathode side of the fuel cell stack;

[0010] The nitrogen gas path includes a first pressure regulating valve connected to a nitrogen gas source, a third flow regulating valve connected to the output end of the first pressure regulating valve, a first pressure sensor, a fourth flow regulating valve, a fifth flow regulating valve, a sixth flow regulating valve, and a ninth flow regulating valve connected to the output end of the third flow regulating valve, a fourth flow meter connected to the output end of the fourth flow regulating valve, the output end of the fourth flow meter being connected to the output end of the first flow meter, the output end of the fifth flow regulating valve being connected to the output end of the second flow regulating valve, a fourth pressure sensor, a seventh flow regulating valve, and a third flow meter connected to the output end of the sixth flow regulating valve, and a twelfth flow regulating valve connected to the nitrogen gas outlet of the fuel cell stack. The output end of the third flow meter is connected to the cooling path of the fuel cell stack;

[0011] An insulation detection device for detecting the insulation state of the fuel cell;

[0012] A whole-stack airtightness detection device for detecting the airtightness of the fuel cell;

[0013] And a voltage anomaly detection and failure diagnosis device for detecting and analyzing the short circuit of the fuel cell and the voltage anomaly of each cell of the fuel cell.

[0014] Optionally, the voltage anomaly of each cell of the fuel cell includes:

[0015] In an open circuit state, the voltage of continuously multiple cells regularly shows high voltage, zero voltage, or negative voltage, and / or the voltage of any single cell shows high voltage, low voltage, zero voltage, or negative voltage, where the high voltage is not less than the average voltage of the normal number of cells plus a preset voltage, and the low voltage is not greater than the average voltage of the normal number of cells minus a preset voltage.

[0016] Optionally, the voltage anomaly detection and failure diagnosis device detects and analyzes the short circuit of the fuel cell and the voltage anomaly of each cell of the fuel cell, including:

[0017] S1. Introduce nitrogen into the anode side of the fuel cell stack, and at the same time introduce air into the cathode side of the fuel cell stack. After a preset time, introduce hydrogen into the anode side of the fuel cell stack until the open circuit voltage of the fuel cell remains stable;

[0018] S2. Collect the inspection signals of the voltages of each cell of the fuel cell, and determine whether the voltages of each cell of the fuel cell are abnormal according to the inspection signals and perform corresponding fault analysis.

[0019] Optionally, step S2 includes:

[0020] Collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that the voltage patterns of multiple consecutive cells show high voltages or negative voltages, and it is judged that the absolute values of the high voltages and the negative voltages are both M times the average voltage of the normal number of cells, it is determined as a fault of the inspection wire harness, where M = A ± 0.2 and A is a positive integer;

[0021] Collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that any single cell of the fuel cell has a zero voltage, purge the fuel cell with nitrogen and complete the discharge, and then measure the first resistance at the ends of the two inspection lines of the cell with zero voltage. If a short circuit alarm occurs during the detection, it is determined as a short circuit fault, or if the first resistance reaches the upper limit of the range, it is determined as an open circuit fault; measure the second resistance between the two electrodes of the cell with zero voltage. If the second resistance is less than the first resistance, it is determined as an open circuit fault of the inspection wire harness, or if the difference between the second resistance and the first resistance is within the preset range, it is determined as an open circuit fault inside the cell with zero voltage;

[0022] When it is determined that there is no zero voltage problem in any single cell of the fuel cell, introduce air into the cathode side of the fuel cell stack and introduce hydrogen into the anode side of the fuel cell stack. After the open circuit voltage of the fuel cell remains stable, collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that any single cell has a low voltage, it is determined that the cell with low voltage has a hydrogen-oxygen mutual penetration and internal leakage fault, or a hydrogen-oxygen external leakage and hydrogen-oxygen water stringing fault, or an unqualified membrane electrode or bipolar plate fault.

[0023] Optionally, step S1 includes:

[0024] Open the second flow regulating valve, the third flow regulating valve, the fourth flow regulating valve, the tenth flow regulating valve and the eleventh flow regulating valve. After a preset time, open the first flow regulating valve until the open circuit voltage of the fuel cell remains stable.

[0025] Optionally, the insulation detection device detects the insulation state of the fuel cell, including:

[0026] When the fuel cell is open - circuited, without gas supply, or in a zero / low - voltage state, measure the insulation resistance of the anode side and the cathode side of the fuel cell stack. When it is determined that the insulation resistance is within the designed or specified insulation resistance threshold range, determine that the fuel cell stack is in an insulation - safe state.

[0027] Optionally, the overall airtightness detection device detects the airtightness of the fuel cell, including:

[0028] The overall airtightness detection device detects the overall external leakage of the three cavities, the internal leakage of hydrogen - oxygen inter - penetration, and the internal leakage of hydrogen - oxygen water - penetration of the fuel cell stack.

[0029] Optionally, detecting the overall external leakage of the fuel cell stack includes: opening the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve, and the sixth flow regulating valve, adjusting the first pressure regulating valve to a first set pressure, such that the first pressure sensor, the second pressure sensor, the third pressure sensor, and the fourth pressure sensor are all at the first set pressure. After a first preset time, detect the readings of the first flowmeter, the second flowmeter, and the third flowmeter.

[0030] Optionally, detecting the internal leakage of hydrogen - oxygen inter - penetration of the fuel cell stack includes: opening the third flow regulating valve, the fourth flow regulating valve, and the eighth flow regulating valve, adjusting the first pressure regulating valve to a second set pressure, such that the first pressure sensor and the second pressure sensor are both at the second set pressure. After a second preset time, detect the reading of the second flowmeter.

[0031] Optionally, detecting the internal leakage of hydrogen - oxygen water - penetration of the fuel cell stack includes: opening the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve, and the seventh flow regulating valve, adjusting the first pressure regulating valve to a third set pressure, such that the first pressure sensor, the second pressure sensor, and the third pressure sensor are all at the third set pressure. After a third preset time, detect the reading of the third flowmeter.

[0032] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0033] The present invention provides a detection system for a fuel cell. The detection system includes: an insulation detection device for detecting the insulation state of the fuel cell; a stack airtightness detection device for detecting the airtightness of the fuel cell; and a voltage anomaly detection and failure diagnosis device for detecting and analyzing short circuits of the fuel cell and voltage anomalies of each cell of the fuel cell. Furthermore, the detection system for a fuel cell provided by the present invention can efficiently, nondestructively, and with low risk complete the detection of fuel cell insulation, airtightness, and voltage anomalies before factory activation testing, before performance testing, and during maintenance diagnosis, providing reliable, sufficient, and effective data support for problem diagnosis and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0035] Figure 1 It is a schematic structural diagram of a detection system for a fuel cell provided by an embodiment of the present invention;

[0036] Figure 2 It is a flowchart of a detection process for a fuel cell provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] As described in the background art, in engineering research and development, after the fuel cell is assembled and factory-produced and passes the insulation and overall airtightness tests, there are still potential state problems, such as typical voltage anomaly problems. However, due to the lack of targeted detection, in actual engineering development work, when the fuel cell is subjected to bench testing, there are still frequent failures, such as various problems such as single-cell zero voltage, low voltage, high voltage (or negative voltage), and abnormal voltage inspection information, making it difficult to smoothly carry out the activation and performance testing of the stack. In addition, in the stack maintenance link, due to the lack of systematic detection methods and detection devices, problems such as low analysis efficiency of engineers and difficulty in clarifying the cause of the failure occur.

[0039] Based on this, the embodiments of the present invention provide a detection system for a fuel cell, effectively solving the technical problems existing in the prior art. Before the factory activation test, before the performance test, and during the maintenance diagnosis, it can efficiently, non-destructively, and with low risk complete the detection of the fuel cell insulation, airtightness, and voltage abnormality problems, etc., providing reliable, sufficient, and effective data support for problem diagnosis and maintenance.

[0040] To achieve the above object, the technical solutions provided by the embodiments of the present invention are as follows, specifically combined with Figure 1 and Figure 2 to describe in detail the technical solutions provided by the embodiments of the present invention.

[0041] Referring to Figure 1 as shown, it is a schematic structural diagram of a detection system for a fuel cell provided by an embodiment of the present invention. Among them, the detection system includes a fuel cell stack 100 to be detected, and a hydrogen path, an air path, and a nitrogen path connected to the fuel cell stack 100;

[0042] The hydrogen path includes a first flow regulating valve K1 connected to a hydrogen source H2, a first flowmeter F1 with an input end connected to the output end of the first flow regulating valve K1, a second pressure sensor P2 connected to the output end of the first flowmeter F1, and a tenth flow regulating valve K10 connected to the hydrogen outlet of the fuel cell stack 100. The output end of the first flowmeter F1 is connected to the anode side of the fuel cell stack 100;

[0043] The air path includes a second flow regulating valve K2 connected to an air source air / O2, an eighth flow regulating valve K8, a third pressure sensor P3, and a second flowmeter F2 connected to the output end of the second flow regulating valve K2, and an eleventh flow regulating valve K11 connected to the air outlet of the fuel cell stack 100. The output end of the second flowmeter F2 is connected to the cathode side of the fuel cell stack 100;

[0044] The nitrogen gas path includes a first pressure regulating valve S1 connected to a nitrogen gas source N2, a third flow regulating valve K3 connected to the output end of the first pressure regulating valve S1, a first pressure sensor P1, a fourth flow regulating valve K4, a fifth flow regulating valve K5, a sixth flow regulating valve K6, and a ninth flow regulating valve K9 connected to the output end of the third flow regulating valve K3, a fourth flow meter F4 connected to the output end of the fourth flow regulating valve K4, the output end of the fourth flow meter F4 being connected to the output end of the first flow meter F1, the output end of the fifth flow regulating valve K5 being connected to the output end of the second flow regulating valve K2, a fourth pressure sensor P4, a seventh flow regulating valve K7, and a third flow meter F3 connected to the output end of the sixth flow regulating valve K2, and a twelfth flow regulating valve K12 connected to the nitrogen gas outlet of the fuel cell stack 100, the output end of the third flow meter F3 being connected to the cooling path of the fuel cell stack 100;

[0045] An insulation detection device 200 for detecting the insulation state of the fuel cell;

[0046] A whole-stack airtightness detection device 300 for detecting the airtightness of the fuel cell;

[0047] And a voltage abnormality detection and failure diagnosis device 400 for detecting and analyzing the short circuit of the fuel cell and the voltage abnormality of each cell of the fuel cell.

[0048] As can be seen from the above, the detection system of the fuel cell provided by the embodiment of the present invention can efficiently, non-destructively, and with low risk complete the detection of the insulation, airtightness, and voltage abnormality problems of the fuel cell before the factory activation test, before the performance test, and during the maintenance diagnosis, providing reliable, sufficient, and effective data support for problem diagnosis and maintenance.

[0049] As Figure 2 shown, it is a flowchart of a detection process of a fuel cell provided by an embodiment of the present invention. Combining with Figure 1 the detection system shown, the detection process provided by the embodiment of the present invention includes:

[0050] Using the insulation detection device to detect the insulation state of the fuel cell;

[0051] Then using the whole-stack airtightness detection device to detect the airtightness of the fuel cell;

[0052] After the insulation state and airtightness of the fuel cell are detected to be qualified, using the voltage abnormality detection and failure diagnosis device to detect and analyze the short circuit of the fuel cell and the voltage abnormality of each cell of the fuel cell.

[0053] In an embodiment of the present invention, the abnormal voltage of each cell of the fuel cell provided by the present invention includes: in an open circuit state, the voltages of continuously multiple cells regularly show high voltage, zero voltage or negative voltage, and / or, the voltage of any single cell shows high voltage, low voltage, zero voltage or negative voltage, where the high voltage is not less than the average voltage of the cells with normal number plus a preset voltage, and the low voltage is not greater than the average voltage of the cells with normal number minus a preset voltage.

[0054] The following describes the specific detection process of the fuel cell provided by the embodiment of the present invention.

[0055] First, an insulation detection device is used to detect the insulation state of the fuel cell. Among them, the insulation detection device detecting the insulation state of the fuel cell includes:

[0056] In the case of the fuel cell being open circuit, without gas supply, in a zero / low voltage state, use insulation resistance detection related devices (such as multimeter or insulation meter, etc.) to measure the insulation resistance of the anode side and the cathode side of the fuel cell stack, and when it is determined that the insulation resistance is within the designed or specified insulation resistance threshold (such as this specified insulation resistance threshold is a national standard, etc.), it is determined that the fuel cell stack is in an insulation safe state.

[0057] Then, a whole-stack airtightness detection device is used to detect the airtightness of the fuel cell. Among them, the whole-stack airtightness detection device detecting the airtightness of the fuel cell includes: the whole-stack airtightness detection device detecting the overall three-chamber external leakage, hydrogen-oxygen mutual leakage inside and hydrogen-oxygen water leakage inside of the fuel cell stack.

[0058] Specifically, the detection of the overall three-chamber external leakage of the fuel cell stack provided by the embodiment of the present invention includes: opening the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve and the sixth flow regulating valve, while other flow regulating valves are closed. Adjust the first pressure regulating valve to a first set pressure (the set pressure can be set according to the design pressure range of the fuel cell stack), the first pressure sensor, the second pressure sensor, the third pressure sensor and the fourth pressure sensor are all at the first set pressure. After a first preset time (such as the first preset time can be 1 min, and no specific limitation is made on this), detect the readings of the first flowmeter, the second flowmeter and the third flowmeter, and determine the situation of the overall three-chamber external leakage of the fuel cell stack according to the readings (after completion, close the first pressure regulating valve and the third flow regulating valve, slowly open the ninth flow regulating valve, and after the pressure relief is completed, close the fourth flow regulating valve, the fifth flow regulating valve, the sixth flow regulating valve and the ninth flow regulating valve).

[0059] Moreover, the detection of hydrogen-oxygen cross leakage in the fuel cell stack provided by the embodiments of the present invention includes: opening the third flow regulating valve, the fourth flow regulating valve, and the eighth flow regulating valve, while closing other flow regulating valves. Adjust the first pressure regulating valve to a second set pressure (the set pressure can be set according to the design pressure range of the fuel cell stack). When the first pressure sensor and the second pressure sensor both reach the second set pressure, after a second preset time (for example, the second preset time can be 1 minute, and there is no specific limitation on this), detect the reading of the second flow meter, and determine the hydrogen-oxygen cross leakage situation of the fuel cell stack according to the reading (after completion, close the first pressure regulating valve and the third flow regulating valve, slowly open the tenth flow regulating valve, and after the pressure relief is completed, close the fourth flow regulating valve, the eighth flow regulating valve, and the tenth flow regulating valve).

[0060] Moreover, the detection of hydrogen-oxygen water cross leakage in the fuel cell stack provided by the embodiments of the present invention includes: opening the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve, and the seventh flow regulating valve, while closing other flow regulating valves. Adjust the first pressure regulating valve to a third set pressure (the set pressure can be set according to the design pressure range of the fuel cell stack). When the first pressure sensor, the second pressure sensor, and the third pressure sensor all reach the third set pressure, after a third preset time (for example, the third preset time can be 1 minute, and there is no specific limitation on this), detect the reading of the third flow meter and determine the hydrogen-oxygen water cross leakage situation of the fuel cell stack according to the reading (after completion, close the first pressure regulating valve and the third flow regulating valve, slowly open the ninth flow regulating valve, and after the pressure relief is completed, close the fourth flow regulating valve, the fifth flow regulating valve, the seventh flow regulating valve, and the ninth flow regulating valve).

[0061] Finally, a voltage anomaly detection and failure diagnosis device is used to detect and analyze the short circuit of the fuel cell and the voltage anomaly of each cell of the fuel cell. Among them, the voltage anomaly detection and failure diagnosis device provided by the embodiments of the present invention for detecting and analyzing the short circuit of the fuel cell and the voltage anomaly of each cell of the fuel cell includes:

[0062] S1. Introduce nitrogen (the flow rate can be Q1) into the anode side of the fuel cell stack, and at the same time introduce air (the flow rate can be Q2) into the cathode side of the fuel cell stack. And after a preset time, introduce hydrogen (the flow rate can be Q3, Q3 < Q2 * a, a can be 0.04, and the value of a can be formulated according to the hydrogen safety threshold allowable at the detection site) into the anode side of the fuel cell stack until the open circuit voltage of the fuel cell remains stable (where the open circuit voltage can be 0.95 - 1.2 V (per cell), and actually can be set according to factors such as different types of fuel cell stacks, different fuel cell life states, and hydrogen permeation current values).

[0063] S2. Collect the inspection signals of the voltages of each cell of the fuel cell, and determine whether the voltages of each cell of the fuel cell are abnormal according to the inspection signals, and perform corresponding fault analysis.

[0064] In an embodiment of the present invention, after the fuel cell provided by the present invention leaves the factory, the basic state of the stack is unknown. In order to avoid problems such as burning caused by short-circuit faults, a pre-inspection step for short-circuit problems is first performed, that is, step S1. Among them, step S1 provided by the embodiment of the present invention includes: opening the second flow regulating valve, the third flow regulating valve, the fourth flow regulating valve, the tenth flow regulating valve and the eleventh flow regulating valve, while other flow regulating valves are closed. After a preset time, open the first flow regulating valve until the open-circuit voltage of the fuel cell remains stable.

[0065] On the basis of the air supply in step S1, after determining that there is no short circuit in the fuel cell, the abnormal detection and analysis of the voltage of each cell are carried out. The specific step S2 includes:

[0066] S21. Collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that the voltage patterns of multiple consecutive cells show high voltage or negative voltage, and it is determined that the absolute values of the high voltage and the negative voltage are both M times the average voltage of the cells with the normal number of cells, it is determined as an inspection harness fault, where M = A ± 0.2 and A is a positive integer.

[0067] It can be understood that the inspection voltage signals of each cell are collected to identify high-voltage and negative-voltage problems. Then, compare the numerical values of the high voltage, the negative voltage and the average voltage of the cells with the normal number of cells, as well as the positions of the cells with high voltage and negative voltage for identification. When it is determined that the absolute values of the high voltage and the negative voltage are both M times the average voltage of the cells with the normal number of cells and the voltage patterns of multiple consecutive cells show high voltage or negative voltage, it is confirmed as an inspection harness fault (such as incorrect harness order), and the inspection harness needs to be inspected and repaired.

[0068] S22. Collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that the voltage of any single cell appears as zero voltage, perform nitrogen purging on the fuel cell and complete the discharge. Then measure the first resistance at the ends of the two inspection lines of the cell with zero voltage. If a short-circuit alarm occurs during the detection, it is determined as a short-circuit fault, or if the first resistance reaches the upper limit of the range, it is determined as an open-circuit fault; measure the second resistance between the two electrodes of the cell with zero voltage. If the second resistance is less than the first resistance, it is determined as an inspection harness open-circuit fault, or if the difference between the second resistance and the first resistance is within a preset range, it is determined as an open-circuit fault inside the cell with zero voltage.

[0069] It is understandable that the inspection voltage signals of each battery cell are collected to identify the problem of zero voltage in a single battery cell. The characteristic is that the voltage of a single battery cell is zero, and the position of the cell is random. In this regard, troubleshooting will be carried out from two aspects: short circuit and open circuit. The open circuit troubleshooting includes but is not limited to aspects such as misinstallation of single plates, blockage of the hydrogen chamber or air chamber, and open circuit of the inspection wire harness. First, detect the open circuit problem of the wire harness. After closing all valves, open the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve, the tenth flow regulating valve, and the eleventh flow regulating valve, and use nitrogen to purge the anode side and the cathode side. After discharging (in principle, it should be discharged to a safe voltage below 36V), close all valves. After the nitrogen purge is completed and the discharge is finished, use an ohmic impedance measuring device (such as a multimeter, etc.) to measure the first resistance at the ends of the two inspection lines of the battery cell with the problem. If a short circuit alarm occurs during the detection, a short circuit fault is determined; if the detected first resistance R1 is close to or reaches the upper limit of the range (taking the range of a common insulation resistance meter as an example: 2000MΩ), an open circuit fault is determined. Then measure the second resistance R2 between the two plates of the battery cell with the problem. If the resistance R2 is much smaller than R1 (in this embodiment, R2 should be a normal value, and its reference value is 0.2 - 4mΩ), an open circuit fault of the inspection wire harness is determined; if R2 is approximately equal to R1 (that is, when the difference between R2 and R1 is within the preset range, and the preset range is specified by a ratio as: R2 / R1 = 0.9 - 1.1), or both R1 and R2 are close to or reach the upper limit of the range (taking the range of a common insulation resistance meter as an example: 2000MΩ), an open circuit fault inside the battery cell with zero voltage is determined. If it is necessary to further lock the cause, troubleshooting can be carried out from aspects such as misinstallation of single plates, blockage of the hydrogen chamber or air chamber, etc.

[0070] Thus, the analysis of the cause of zero voltage is completed, distinguishing between problems with the inspection wire harness and problems with the quality of a single battery cell itself. If it is determined that the problem is with the inspection wire harness, the wire harness can be replaced to complete the repair. If it is a problem with the quality of a single battery cell itself, the stack needs to be disassembled and replaced to complete the repair.

[0071] S23. When it is determined that there is no zero voltage problem in the voltage of any single battery cell of the fuel cell, air is introduced into the cathode side of the fuel cell stack, and hydrogen is introduced into the anode side of the fuel cell stack. After the open circuit voltage of the fuel cell remains stable, collect the inspection signals of the voltages of each battery cell of the fuel cell. When it is determined that the voltage of any single battery cell shows a low voltage, determine that the battery cell with low voltage has a hydrogen-oxygen cross-leakage internal leakage fault, or a hydrogen-oxygen external leakage and hydrogen-oxygen water cross-leakage fault, or an unqualified membrane electrode or bipolar plate fault.

[0072] It is understandable that after it is determined that there is no problem of zero voltage in a single cell, the first flow regulating valve, the second flow regulating valve, the tenth flow regulating valve and the eleventh flow regulating valve are opened to introduce air into the cathode side of the fuel cell stack and hydrogen into the anode side of the fuel cell stack (for example, for every 1 L / min reduction in air flow, the hydrogen flow is reduced by 1.5 L / min. In actual applications, the flow rate needs to be determined according to the fuel cell specifications). After the open circuit voltage of the fuel cell remains stable, the inspection signals of the voltages of each cell of the fuel cell are collected. If the open circuit voltage is lower than the average voltage of the cells in the normal number of cells (such as <0.85 V), it is a low voltage fault (also known as a single low fault). The troubleshooting will be carried out from the following aspects:

[0073] a) Hydrogen-oxygen cross-leakage and internal leakage fault in a single cell: Open the first flow regulating valve, the second flow regulating valve, the tenth flow regulating valve and the eleventh flow regulating valve. After the open circuit voltage is established and stable, close the second flow regulating valve and the tenth flow regulating valve to cut off the air supply. Record the voltage drop process of each cell. The severely leaking cells can be screened and captured from the voltage change states of each cell in the fuel cell stack. According to the relevant physical property parameters of the membrane electrode used in the fuel cell stack, the hydrogen-oxygen cross-leakage amount is calculated theoretically.

[0074] b) Hydrogen-oxygen external leakage and hydrogen-oxygen water cross-leakage fault in a single cell: In the qualified inspection of component materials, the leakage amount detection of single samples or short stack samples is usually carried out. Therefore, when the material inspection is qualified and the airtightness of the whole stack is qualified, the possibility of open circuit low voltage caused by external leakage and hydrogen-oxygen water cross-leakage of a single cell is relatively low.

[0075] c) Fault of unqualified membrane electrode or bipolar plate: If the preparation state of the membrane electrode or bipolar plate deviates significantly from the design target, it will also lead to abnormal open circuit voltage phenomenon.

[0076] In an embodiment of the present invention, the above voltage abnormality problems may occur in combination and superimposition. Based on the above process, the identification of voltage abnormality problems is completed. If there is no problem, it will be delivered for factory production, maintenance, etc.; if there is a problem, the above steps will be followed to detect the problem and analyze the cause, providing a basis for repairing the stack.

[0077] An embodiment of the present invention provides a detection system for a fuel cell. The detection system includes: an insulation detection device for detecting the insulation state of the fuel cell; a stack airtightness detection device for detecting the airtightness of the fuel cell; and a voltage anomaly detection and failure diagnosis device for detecting and analyzing short circuits of the fuel cell and voltage anomalies of each cell of the fuel cell. Furthermore, the detection system for a fuel cell provided by the embodiment of the present invention can efficiently, non-destructively, and with low risk complete the detection of the insulation, airtightness, and voltage anomalies of the fuel cell before factory activation testing, before performance testing, and during maintenance diagnosis, providing reliable, sufficient, and effective data support for problem diagnosis and maintenance.

[0078] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention will not be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A detection system for a fuel cell, characterized in that, the detection system includes a fuel cell stack to be detected, and a hydrogen path, an air path and a nitrogen path connected to the fuel cell stack; the hydrogen path includes a first flow regulating valve connected to a hydrogen source, a first flow meter with an input end connected to an output end of the first flow regulating valve, a second pressure sensor connected to an output end of the first flow meter, and a tenth flow regulating valve connected to a hydrogen outlet of the fuel cell stack, and the output end of the first flow meter is connected to an anode side of the fuel cell stack; the air path includes a second flow regulating valve connected to an air source, an eighth flow regulating valve, a third pressure sensor and a second flow meter connected to an output end of the second flow regulating valve, and an eleventh flow regulating valve connected to an air outlet of the fuel cell stack, and the output end of the second flow meter is connected to a cathode side of the fuel cell stack; the nitrogen path includes a first pressure regulating valve connected to a nitrogen source, a third flow regulating valve connected to an output end of the first pressure regulating valve, a first pressure sensor, a fourth flow regulating valve, a fifth flow regulating valve, a sixth flow regulating valve and a ninth flow regulating valve connected to an output end of the third flow regulating valve, a fourth flow meter connected to an output end of the fourth flow regulating valve, the output end of the fourth flow meter is connected to the output end of the first flow meter, the output end of the fifth flow regulating valve is connected to the output end of the second flow regulating valve, a fourth pressure sensor, a seventh flow regulating valve and a third flow meter connected to an output end of the sixth flow regulating valve, and a twelfth flow regulating valve connected to a nitrogen outlet of the fuel cell stack, and the output end of the third flow meter is connected to a cooling path of the fuel cell stack; an insulation detection device for detecting an insulation state of the fuel cell; a whole-stack airtightness detection device for detecting an airtightness of the fuel cell; and a voltage anomaly detection and failure diagnosis device for detecting and analyzing a short circuit of the fuel cell and voltage anomalies of each cell of the fuel cell; wherein, the voltage anomalies of each cell of the fuel cell include: in an open-circuit state, the voltage of continuously multiple cells regularly shows a high voltage, a zero voltage or a negative voltage, and / or, the voltage of any single cell shows a high voltage, a low voltage, a zero voltage or a negative voltage, wherein, the high voltage is not less than an average voltage of normal cells plus a preset voltage, and the low voltage is not greater than an average voltage of normal cells minus a preset voltage; the voltage anomaly detection and failure diagnosis device detecting and analyzing the short circuit of the fuel cell and the voltage anomalies of each cell of the fuel cell includes: S1. Introduce nitrogen into the anode side of the fuel cell stack, and at the same time introduce air into the cathode side of the fuel cell stack, and after a preset time, introduce hydrogen into the anode side of the fuel cell stack until the open-circuit voltage of the fuel cell remains stable; S2. Collect the inspection signals of the voltages of each cell of the fuel cell, and determine whether the voltages of each cell of the fuel cell are abnormal according to the inspection signals and perform corresponding fault analysis, including: Collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that the voltage patterns of multiple consecutive cells show high voltages or negative voltages, and it is judged that the absolute values of the high voltages and the negative voltages are both M times the average voltage of the cells with normal number of cells, it is determined as an inspection harness fault, where M = A ± 0.2 and A is a positive integer; Collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that the voltage of any single cell is zero voltage, perform nitrogen purging on the fuel cell and complete the discharge, and then measure the first resistance at the ends of the two inspection lines of the cell with zero voltage. If a short - circuit alarm occurs during the detection, it is determined as a short - circuit fault; or if the first resistance reaches the upper limit of the range, it is determined as an open - circuit fault; Measure the second resistance between the two plates of the cell with zero voltage. If the second resistance is less than the first resistance, it is determined as an open - circuit fault of the inspection harness; or if the difference between the second resistance and the first resistance is within a preset range, it is determined as an open - circuit fault inside the cell with zero voltage; When it is determined that there is no zero - voltage problem with the voltage of any single cell of the fuel cell, introduce air to the cathode side of the fuel cell stack and introduce hydrogen to the anode side of the fuel cell stack. After the open - circuit voltage of the fuel cell remains stable, collect the inspection signals of the voltages of each cell of the fuel cell. When it is determined that the voltage of any single cell is a low voltage, it is determined that the cell with low voltage has a hydrogen - oxygen mutual leakage and internal leakage fault, or a hydrogen - oxygen external leakage and hydrogen - oxygen water - stringing fault, or an unqualified membrane electrode or bipolar plate fault.

2. The detection system for a fuel cell according to claim 1, wherein, Step S1 includes: Open the second flow regulating valve, the third flow regulating valve, the fourth flow regulating valve, the tenth flow regulating valve and the eleventh flow regulating valve. After a preset time, open the first flow regulating valve until the open - circuit voltage of the fuel cell remains stable.

3. The detection system for a fuel cell according to claim 1, wherein, The insulation detection device detects the insulation state of the fuel cell, including: In the case of the fuel cell being open - circuited, without gas supply, in a zero / low - voltage state, measure the insulation resistance of the anode side and the cathode side of the fuel cell stack. When it is judged that the insulation resistance is within the designed or specified insulation resistance threshold range, it is determined that the fuel cell stack is in an insulation - safe state.

4. The detection system for a fuel cell according to claim 1, wherein, The overall airtightness detection device detects the airtightness of the fuel cell, including: The overall airtightness detection device detects the overall external leakage of the three cavities, hydrogen - oxygen mutual leakage and internal leakage of hydrogen - oxygen water - stringing of the fuel cell stack.

5. The detection system for a fuel cell according to claim 4, wherein, Detecting the overall external leakage of the fuel cell stack includes: opening the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve and the sixth flow regulating valve, adjusting the first pressure regulating valve to a first set pressure, and making the first pressure sensor, the second pressure sensor, the third pressure sensor and the fourth pressure sensor all at the first set pressure. After a first preset time, detect the readings of the first flowmeter, the second flowmeter and the third flowmeter.

6. The fuel cell detection system according to claim 4, wherein, detecting the internal leakage of hydrogen-oxygen cross-leakage of the fuel cell stack includes: opening the third flow regulating valve, the fourth flow regulating valve and the eighth flow regulating valve, adjusting the first pressure regulating valve to a second set pressure, and making the first pressure sensor and the second pressure sensor both at the second set pressure. After a second preset time, detect the reading of the second flowmeter.

7. The fuel cell detection system according to claim 4, wherein, detecting the internal leakage of hydrogen-oxygen water cross-leakage of the fuel cell stack includes: opening the third flow regulating valve, the fourth flow regulating valve, the fifth flow regulating valve and the seventh flow regulating valve, adjusting the first pressure regulating valve to a third set pressure, and making the first pressure sensor, the second pressure sensor and the third pressure sensor all at the third set pressure. After a third preset time, detect the reading of the third flowmeter.

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