A fuel cell hydrogen internal leakage fault online diagnosis method and system

Abstract

The application relates to a fuel cell hydrogen internal leakage fault online diagnosis method and system, wherein the method comprises the following steps: hydrogen and air with constant flow are respectively introduced into an anode and a cathode of a fuel cell; the hydrogen pressure on the anode side of the fuel cell is increased to a predetermined value and kept stable, while the air pressure on the cathode side is kept as the ambient atmospheric pressure; the fuel cell is kept open circuit, the air supply on the cathode side is instantaneously interrupted after the cell voltage is stabilized; the time experienced by the cell open circuit voltage drop to a specific voltage threshold value is recorded as the voltage drop time; during the aging process of the fuel cell, the above steps are repeated, the voltage drop time is re-determined, and if the reduction amplitude of the voltage drop time exceeds a certain threshold value, it is judged that a gas internal leakage fault occurs in the fuel cell. Compared with the prior art, the application can realize online diagnosis of the hydrogen fuel cell internal leakage fault, and has the advantages of simple operation, easy implementation, good repeatability, high reliability and the like.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane fuel cell technology, and in particular to an online diagnostic method and system for hydrogen internal leakage faults in fuel cells. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are characterized by high power density, short start-up time, and low operating temperature, and have become the mainstream technology for fuel cell vehicles. The PEM is the core component of a fuel cell, responsible for conducting protons, insulating electrons, and separating reactant gases at the electrodes. However, due to the porosity of the PEM, a small amount of hydrogen inevitably leaks from the anode to the cathode during normal fuel cell operation. As the PEM ages, the amount of hydrogen leakage inside the fuel cell gradually increases. Under real-world vehicle conditions, frequent fluctuations in operating parameters such as pressure, temperature, and humidity can cause mechanical damage to the fuel cell stack. Some severely degraded fuel cells may experience membrane perforation, at which point the small amount of hydrogen leakage can escalate into an abnormal internal hydrogen leak. A large amount of hydrogen directly mixing with air can significantly reduce the fuel cell's output performance and may even pose an explosion risk, severely impacting the normal operation of the fuel cell system. Current technologies for detecting internal hydrogen leaks in fuel cells mostly require introducing an inert gas into the cathode, while fault diagnosis of on-board fuel cells can only be performed under hydrogen-air conditions. Therefore, it is necessary to develop an online diagnostic method for hydrogen internal leakage faults in fuel cells that is simple to operate and easy to implement, in order to overcome the limitations of existing technologies. Summary of the Invention

[0003] The purpose of this invention is to provide an online diagnostic method and system for hydrogen internal leakage faults in fuel cells, which eliminates the need for introducing inert gas and enables simple and highly reliable online diagnostics of hydrogen internal leakage faults in fuel cells.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] An online diagnostic method for hydrogen internal leakage faults in fuel cells includes the following steps:

[0006] S1. Hydrogen and air are introduced into the anode and cathode of the fuel cell at constant flow rates, respectively.

[0007] S2. Increase the hydrogen pressure on the anode side of the fuel cell to a predetermined value and keep it stable, while keeping the air pressure on the cathode side at ambient atmospheric pressure;

[0008] S3. Keep the fuel cell open and interrupt the air supply to the cathode side instantly after the battery voltage stabilizes.

[0009] S4. Record the time it takes for the battery open-circuit voltage to drop to a specific voltage threshold, and denot it as the voltage drop time.

[0010] S5. During the aging process of the fuel cell, repeat steps S1-S4 and re-measure the voltage drop time. If the reduction in voltage drop time exceeds a certain threshold, it is determined that an internal gas leak has occurred inside the fuel cell.

[0011] The fuel cell is a proton exchange membrane fuel cell unit or a stack.

[0012] In step S2, the predetermined value of the hydrogen pressure is greater than the ambient atmospheric pressure.

[0013] The method for interrupting the air supply to the cathode side is as follows: set the air flow rate to zero while keeping the anode side air intake parameter settings unchanged.

[0014] The specific voltage threshold is less than or equal to 0.5V.

[0015] An online diagnostic system for hydrogen internal leakage faults in fuel cells includes:

[0016] The ventilation control module is used to perform the following steps: introduce hydrogen and air at constant flow rates into the anode and cathode of the fuel cell, respectively; increase the hydrogen pressure on the anode side of the fuel cell to a predetermined value and keep it stable, while keeping the air pressure on the cathode side at ambient atmospheric pressure; keep the fuel cell open, and interrupt the air supply to the cathode side momentarily after the battery voltage stabilizes.

[0017] The voltage drop time recording module is used to record the time it takes for the battery open-circuit voltage to drop to a specific voltage threshold, which is denoted as the voltage drop time.

[0018] The hydrogen internal leakage fault diagnosis module is used to repeatedly call the ventilation control module and the voltage drop time recording module during the aging process of the fuel cell to re-measure the voltage drop time. If the reduction in voltage drop time exceeds a certain threshold, it is determined that a gas internal leakage fault has occurred inside the fuel cell.

[0019] The fuel cell is a proton exchange membrane fuel cell unit or a stack.

[0020] In the ventilation control module, the predetermined value of hydrogen pressure is greater than the ambient atmospheric pressure.

[0021] The method for interrupting the air supply to the cathode side is as follows: set the air flow rate to zero while keeping the anode side air intake parameter settings unchanged.

[0022] The specific voltage threshold is less than or equal to 0.5V.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention can qualitatively detect changes in hydrogen internal leakage in fuel cells under hydrogen-air conditions, determine whether an internal leakage fault has occurred, and has a simple and easy-to-implement operation process with good repeatability and high reliability. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method of the present invention;

[0026] Figure 2 This is a schematic diagram comparing the open-circuit voltage drop curves before and after a fault is introduced into the fuel cell in an embodiment of the present invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] This embodiment provides an online diagnostic method for hydrogen internal leakage faults in proton exchange membrane fuel cell cells or stacks, such as... Figure 1 As shown, it includes the following steps:

[0030] S1. Introduce hydrogen and air at constant flow rates into the anode and cathode of the fuel cell, respectively; wherein the flow rate should be greater than zero.

[0031] S2. Increase the hydrogen pressure on the anode side of the fuel cell to a predetermined value and keep it stable, while keeping the air pressure on the cathode side at ambient atmospheric pressure;

[0032] In a preferred embodiment, the predetermined value of the hydrogen pressure is greater than the ambient atmospheric pressure.

[0033] S3. Keep the fuel cell open and interrupt the air supply to the cathode side instantly after the battery voltage stabilizes. Specifically, interrupting the air supply to the cathode side is achieved by setting the air flow rate to zero while keeping the anode side air intake parameter settings unchanged.

[0034] S4. Record the time it takes for the battery open-circuit voltage to drop to a specific voltage threshold, and denot it as the voltage drop time.

[0035] In a preferred embodiment, a specific voltage threshold is less than or equal to 0.5V.

[0036] S5. During the aging process of the fuel cell, repeat steps S1-S4 and re-measure the voltage drop time. If the reduction in voltage drop time exceeds a certain threshold, it is determined that an internal gas leak has occurred inside the fuel cell.

[0037] Voltage fall time is a qualitative indicator of the amount of hydrogen leakage inside a fuel cell; a shorter voltage fall time indicates a greater internal hydrogen leakage rate. Therefore, changes in voltage fall time can be used to determine whether an internal gas leakage fault has occurred.

[0038] The test object in this embodiment is a proton exchange membrane fuel cell unit, but it is not limited to this in practical applications.

[0039] With a reaction area of ​​25 cm² 2 Taking a fuel cell unit as an example, the fuel cell uses a defect-free membrane electrode assembly. High-purity hydrogen is introduced into the anode at a flow rate of 300 mL / min, and air is introduced into the cathode at a flow rate of 300 mL / min. The back pressures of the anode and cathode are set to 25 kPa and 0 kPa, respectively.

[0040] Keep the fuel cell open-circuited. Once the cell voltage stabilizes, adjust the cathode airflow to zero. Due to the stagnant gas flow at the cathode, hydrogen leaking to the cathode accumulates on its catalyst surface, causing the fuel cell open-circuit voltage to gradually decrease. Record the curve of the fuel cell open-circuit voltage decreasing over time. Figure 2 As shown by the dashed line, the voltage drop time is extracted with a voltage threshold of 0.1V.

[0041] Micropore defects were introduced into the proton exchange membrane of the aforementioned fuel cell cell, and the open-circuit voltage drop curve was obtained through the same steps, as shown below. Figure 2 As shown by the solid line, the voltage drop time of the fuel cell decreased by more than an order of magnitude after membrane perforation, indicating that the fuel cell has an internal hydrogen leak fault.

[0042] Example 2

[0043] This embodiment provides an online diagnostic system for hydrogen internal leakage faults in fuel cells, including:

[0044] The ventilation control module is used to perform the following steps: introduce hydrogen and air at constant flow rates into the anode and cathode of the fuel cell, respectively; increase the hydrogen pressure on the anode side of the fuel cell to a predetermined value and keep it stable, while keeping the air pressure on the cathode side at ambient atmospheric pressure; keep the fuel cell open, and interrupt the air supply to the cathode side momentarily after the battery voltage stabilizes.

[0045] The voltage drop time recording module is used to record the time it takes for the battery open-circuit voltage to drop to a specific voltage threshold, which is denoted as the voltage drop time.

[0046] The hydrogen internal leakage fault diagnosis module is used to repeatedly call the ventilation control module and the voltage drop time recording module during the aging process of the fuel cell to re-measure the voltage drop time. If the reduction in voltage drop time exceeds a certain threshold, it is determined that a gas internal leakage fault has occurred inside the fuel cell.

[0047] The specific implementation of this system can be referred to in Embodiment 1, which will not be repeated here.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An online diagnostic method for hydrogen internal leakage faults in fuel cells, characterized in that, Includes the following steps: S1. Hydrogen and air are introduced into the anode and cathode of the fuel cell at constant flow rates, respectively. S2. Increase the hydrogen pressure on the anode side of the fuel cell to a predetermined value and keep it stable, while keeping the air pressure on the cathode side at the ambient atmospheric pressure, wherein the predetermined value of the hydrogen pressure is greater than the ambient atmospheric pressure. S3. Keep the fuel cell open and interrupt the air supply to the cathode side instantly after the battery voltage stabilizes. The method of interrupting the air supply to the cathode side is as follows: set the air flow rate to zero, while keeping the anode side air intake parameter settings unchanged. S4. Record the time it takes for the battery open-circuit voltage to drop to a specific voltage threshold, and denot it as the voltage drop time. The specific voltage threshold is less than or equal to 0.5V. S5. During the aging process of the fuel cell, repeat steps S1-S4 and re-measure the voltage drop time. If the reduction in voltage drop time exceeds a certain threshold, it is determined that an internal gas leak has occurred inside the fuel cell.

2. The method for online diagnosis of hydrogen internal leakage fault in a fuel cell according to claim 1, characterized in that, The fuel cell is a proton exchange membrane fuel cell unit or a stack.

3. An online diagnostic system for hydrogen internal leakage faults in fuel cells, characterized in that, include: The ventilation control module is used to perform the following steps: introduce hydrogen and air at constant flow rates into the anode and cathode of the fuel cell, respectively; increase the hydrogen pressure on the anode side of the fuel cell to a predetermined value and keep it stable, while keeping the air pressure on the cathode side at ambient atmospheric pressure; keep the fuel cell open, and interrupt the air supply to the cathode side momentarily after the battery voltage stabilizes. In the ventilation control module, the predetermined value of hydrogen pressure is greater than the ambient atmospheric pressure. The method of interrupting the air supply to the cathode side is specifically to set the air flow rate to zero while keeping the anode side air intake parameter settings unchanged. A voltage drop time recording module is used to record the time it takes for the battery open-circuit voltage to drop to a specific voltage threshold, denoted as the voltage drop time, wherein the specific voltage threshold is less than or equal to 0.5V; The hydrogen internal leakage fault diagnosis module is used to repeatedly call the ventilation control module and the voltage drop time recording module during the aging process of the fuel cell to re-measure the voltage drop time. If the reduction in voltage drop time exceeds a certain threshold, it is determined that a gas internal leakage fault has occurred inside the fuel cell.

4. The online diagnostic system for hydrogen internal leakage faults in a fuel cell according to claim 3, characterized in that, The fuel cell is a proton exchange membrane fuel cell unit or a stack.

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