Diagnostic method for diagnosing state of hydrogen gas sensor in fuel cell system
By opening the exhaust valve in the fuel cell system to fluidly communicate with the anode and the cathode system, and monitoring the rise of the measured value of the hydrogen sensor, the problem of difficulty in diagnosing the state of the hydrogen sensor in the prior art is solved, and timely detection of hydrogen sensor failures and normal operation of the system are achieved.
Patent Information
- Application Number
- CN202380054519.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-07-18
- Filing Date
- 2023-05-26
- Publication Date
- 2025-03-28
AI Technical Summary
The prior art is difficult to effectively diagnose the state of hydrogen sensors in fuel cell systems, resulting in the possibility of hydrogen sensor failure and failure to detect it in time.
By running the fuel cell system, opening the drain valve to fluidly communicate with the cathode subsystem, monitoring the rise of the measured value of the hydrogen sensor over a given time period, and outputting a fault message if the threshold is not exceeded.
Reliable diagnosis of the status of the hydrogen sensor is achieved, and the hydrogen sensor failure can be detected in a timely manner to ensure the normal operation of the system.
Smart Images
Figure CN119731814A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a diagnosis method for diagnosing the state of a hydrogen sensor in a fuel cell system and a fuel cell system. Background Art
[0002] Polymer Electrolyte Membrane (PEM) fuel cell systems convert hydrogen into electricity with the help of oxygen, while producing waste heat and water.
[0003] Here, the conversion of hydrogen means that the hydrogen molecules are consumed or removed on the anode side. A PEM fuel cell consists of an anode supplied with hydrogen, a cathode supplied with air and a polymer electrolyte membrane placed between them. In practical applications, a plurality of such individual fuel cells are stacked to form a fuel cell stack in order to increase the generated voltage. In this fuel cell stack, which is called a "stack", there are supply channels, which supply hydrogen and air to the individual fuel cells or carry away depleted humid air and depleted anode exhaust gas.
[0004] The nitrogen enters the anode chamber by diffusion processes. Nitrogen is an inert gas for the fuel cell and reduces the cell voltage and thus the stack voltage, which in turn means a loss of efficiency. Therefore, during the driving cycle, the gas is also repeatedly discharged from the anode chamber in order to reduce the nitrogen content. This discharge is achieved via a discharge valve, the so-called "purge valve".
[0005] According to the prior art, fresh nitrogen is supplied by means of a hydrogen metering valve, which can be designed as a proportional valve. The control strategy provides that the gas pressure in the anode path is measured by means of a pressure sensor at a defined position via such a valve and is adjusted to a defined set pressure depending on the system operating point.
[0006] Depending on the system, there is a hydrogen sensor in the exhaust path of the cathode air, ie in the cathode subsystem, downstream of the introduction point of the connecting line regulated by the corresponding exhaust valve. If anode gas enters the cathode subsystem, this is detected by the hydrogen sensor. Summary of the invention
[0007] Within the scope of the invention, a diagnostic method and a fuel cell system are proposed. Further features and details of the invention can be derived from the corresponding dependent claims, the description and the drawings. Features and details described in connection with the diagnostic method according to the invention also apply to the fuel cell system according to the invention and vice versa, so that the disclosure of the individual inventive aspects always refers to each other or can refer to each other.
[0008] In particular, the present invention provides a robust and reliable fuel cell system.
[0009] Therefore, according to a first aspect of the present invention, a diagnostic method for diagnosing the state of a hydrogen sensor in a fuel cell system is provided. The diagnostic method comprises: operating the fuel cell system; obtaining a measured value of the hydrogen concentration in the cathode subsystem of the fuel cell system by the hydrogen sensor; opening a discharge valve of the fuel cell system so that the anode subsystem and the cathode subsystem of the fuel cell system are fluidically connected; and outputting a fault message if the measured value obtained by the hydrogen sensor does not rise above a given threshold within a given time period after the discharge valve is opened.
[0010] In the context of the present invention, a discharge valve is understood in particular to be a so-called “purge valve” for discharging hydrogen or a gas mixture containing hydrogen from the anode subsystem into the cathode subsystem, in particular into the exhaust gas line of the cathode subsystem.
[0011] The present invention is based on the following principle: determine the state or function of a hydrogen sensor of a fuel cell system, which means checking whether the hydrogen sensor is still working or is damaged, or whether its function is no longer being performed or is no longer being performed sufficiently.
[0012] In order to check the hydrogen sensor, i.e. the hydrogen concentration sensor, it is provided that the anode subsystem, i.e. the anode path or the anode chamber, is connected to the cathode subsystem, i.e. the cathode path or the cathode chamber in a fluid communication manner, so that hydrogen or a gas containing hydrogen flows from the anode subsystem into the cathode subsystem. The signal response of the hydrogen concentration sensor is verified based on the change in the hydrogen concentration in the cathode subsystem caused by the connection of the anode subsystem and the cathode subsystem. Accordingly, it is determined whether the signal response shows an expected increase.
[0013] In order to connect the anode subsystem and the cathode subsystem, the exhaust valve of the fuel cell system is opened so that the change or increase of the hydrogen concentration in the cathode subsystem can be controlled by manipulating the exhaust valve. Accordingly, operating conditions can be created by manipulating the exhaust valve, and these operating conditions are controlled to create conditions under which, if the hydrogen sensor works correctly, it must provide the expected signal response, that is, the increased measured value. Therefore, it can be inferred that if the measured value obtained by the hydrogen sensor does not rise above a given threshold value within a given time period after the exhaust valve is opened, the hydrogen sensor is faulty, so that a corresponding fault message can be output. In order to determine whether the corresponding measured value exceeds a given threshold value, the measured value can be compared with a given threshold value. Therefore, it can be stipulated that before the fault message is output, the measured value must be greater than the threshold value within a given minimum time period.
[0014] In order to output the fault message, the fault message can be stored, for example, in a memory or displayed on an output unit, for example on a display, in particular by means of a fault warning lamp.
[0015] It can be provided that the diagnostic method further comprises: determining the pressure in the anode subsystem by means of a pressure sensor arranged in the anode subsystem before the drain valve; and verifying the fluid connection between the anode subsystem and the cathode subsystem achieved by opening the drain valve by means of the measured value determined by the pressure sensor.
[0016] In order to exclude false fault messages or false negative diagnosis results due to an insufficient hydrogen supply to the anode subsystem when diagnosing the functionality of the hydrogen sensor, the hydrogen supply to the anode subsystem may be checked.
[0017] It can be stipulated that, during verification, if, within a given time period after outputting a control command for opening the exhaust valve, the measured value acquired by the pressure sensor drops below a given threshold value, an opening verification signal is output, wherein the opening verification signal includes a message confirming the connection between the anode subsystem and the cathode subsystem.
[0018] In order to verify that hydrogen enters the cathode subsystem by opening the exhaust valve, a measured value or a signal response of a pressure sensor arranged upstream of the exhaust valve in the anode subsystem can be evaluated when the exhaust valve is opened, so that if the measured value determined by the pressure sensor drops below a given threshold value after the output of the control command for opening the exhaust valve, it can be concluded that hydrogen enters the cathode subsystem as expected. However, if the measured value determined by the pressure sensor does not drop below the given threshold value after the output of the control command for opening the exhaust valve, it can be concluded that hydrogen does not enter the cathode subsystem, for example because the exhaust valve is damaged and / or the connecting line for connecting the anode subsystem to the cathode subsystem is blocked.
[0019] It may be provided that the given time period after closing the discharge valve starts from a point in time when a given gas flow time has elapsed after closing the discharge valve.
[0020] In order to keep the measured signal to be observed as short as possible and correspondingly effective or sensitive to the controlled changes in the hydrogen concentration, it is possible to exclude the observation of measured values which are determined after the opening of the discharge valve but before the arrival of the hydrogen entering due to the opening. For this purpose, an observation window corrected with the gas flow time or a time period corrected with the gas flow time is particularly advantageously used.
[0021] According to a second aspect, the invention relates to a fuel cell system.
[0022] The proposed fuel cell system includes: an anode subsystem; a cathode subsystem; an exhaust valve, which opens a path in an open state, the path connecting the anode subsystem to the cathode subsystem in fluid communication, and closes the path in a closed state; a hydrogen sensor arranged in the anode subsystem before the exhaust valve in the flow direction of the operating medium flowing through the anode subsystem; and a control device.
[0023] The control device is configured to: operate the fuel cell system at a given operating point; obtain a measured value of the hydrogen concentration in the cathode subsystem of the fuel cell system with the help of a hydrogen sensor; open the exhaust valve so that the anode subsystem is fluidically connected to the cathode subsystem; and output a fault message if the measured value obtained by the hydrogen sensor does not rise above a given threshold value within a given time period after the exhaust valve is opened.
[0024] The proposed diagnostic method is used in particular for operating the proposed fuel cell system.
[0025] In the context of the present invention, a control device is understood to be a computing unit, such as a computer, a processor, a control device or any other programmable circuit.
[0026] It can also be provided that the fuel cell system also includes a pressure sensor arranged in the anode subsystem before the exhaust valve, and the control device is further configured to verify the fluid connection between the anode subsystem and the cathode subsystem achieved by opening the exhaust valve with the aid of a measured value determined by the pressure sensor.
[0027] It can also be provided that the control device is configured to output an opening verification signal if a measured value obtained by the pressure sensor drops below a given threshold value within a given time period after outputting a control command for opening the exhaust valve, wherein the opening verification signal includes a message confirming the connection between the anode subsystem and the cathode subsystem.
[0028] It may also be provided that the control device is configured to close the drain valve in order to separate the anode subsystem from the cathode subsystem and to output a fault message if the measured value ascertained by the hydrogen sensor does not fall below a given threshold value within a given time period after closing the drain valve.
[0029] It may also be provided that the given time period after closing the discharge valve starts from a point in time when a given gas flow time has elapsed after closing the discharge valve.
[0030] Further advantages, features and details of the invention can be derived from the following description, in which an embodiment of the invention is described in detail with reference to the accompanying drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The accompanying drawings show:
[0032] Figure 1 Schematic diagram of a possible configuration of the proposed diagnostic method,
[0033] Figure 2 A possible configuration of the proposed fuel cell system,
[0034] Figure 3 With the help of Figure 2 Performance of measured values under different states when the fuel cell system executes the proposed diagnostic method. DETAILED DESCRIPTION
[0035] exist Figure 1 1 shows a diagnostic method 100 for diagnosing the status of a hydrogen sensor in a fuel cell system.
[0036] The diagnostic method 100 comprises an operating step 101 , in which the fuel cell system is operated at a given operating point.
[0037] Furthermore, the diagnostic method 100 comprises a determination step 103 in which a measured value of the hydrogen concentration in the cathode subsystem of the fuel cell system is determined by a hydrogen sensor.
[0038] Furthermore, the diagnostic method 100 includes an opening step 105 in which a vent valve of the fuel cell system is opened to connect the anode subsystem and the cathode subsystem of the fuel cell system in fluid communication.
[0039] Furthermore, diagnostic method 100 comprises an output step 107 , in which a fault message is output if the measured value ascertained by the hydrogen sensor does not rise above a predefined threshold value within a predefined time period after the opening of the exhaust valve.
[0040] exist Figure 2 2. Fuel cell system 200 is shown in FIG. Fuel cell system 200 includes anode subsystem 201, cathode subsystem 203, and exhaust valve 205, which in an open state opens path 207 that connects anode subsystem 301 in fluid communication with cathode subsystem 203, and in a closed state closes path 207.
[0041] The fuel cell system 200 also comprises a hydrogen sensor 209 and a control unit 211 which are arranged in the anode subsystem 201 upstream of the discharge valve 205 in the flow direction of the operating medium flowing through the anode subsystem 201 .
[0042] The control device 211 is configured to: operate the fuel cell system 200 at a given operating point; obtain a measured value of the hydrogen concentration in the cathode subsystem 203 of the fuel cell system 200 with the help of the hydrogen sensor 209; open the exhaust valve 205 so that the anode subsystem 201 is fluidically connected to the cathode subsystem 203; and output a fault message if the measured value obtained by the hydrogen sensor 209 does not rise above a given threshold value within a given time period after the exhaust valve 205 is opened.
[0043] Optionally, the fuel cell system 200 comprises a pressure sensor 213 which is arranged in the anode line 201 in the flow direction upstream of the discharge valve 205 .
[0044] exist Figure 3 2 shows a diagram 300 which plots time on the abscissa and various sensor values or control states on the ordinate.
[0045] The curve 301 of the measured value of the hydrogen sensor 209 remains substantially constant from the time point T0 until the time point T2 , at which the curve 301 rises, and flattens out again at the time point T3 .
[0046] Compared with the curve 303 of the position of the discharge valve 205, it can be seen that at the time point T4, the discharge valve 205 is opened and the anode subsystem 201 and the cathode subsystem 203 are connected, so that as indicated by the line 309, after the gas flow time, the hydrogen flowing from the anode subsystem 201 reaches the hydrogen sensor 209. Accordingly, the curve 301 rises above a given threshold at the time point T1, so that the correct functionality of the hydrogen sensor 209 can be inferred.
[0047] In order to check the functionality of outlet valve 205 , curve 307 of the measured value of pressure sensor 213 may be evaluated in conjunction with curve 305 of the actuation signal of outlet valve 205 .
[0048] Since curve 303 changes at time T1, the pressure in anode subsystem 201 also changes in response to the swing of curve 305, ie the corresponding transmitted opening signal, so that it can be inferred that the discharge valve is correctly opened in response to the opening signal.
[0049] At time T5, an opening signal is again sent, but this leads neither to a change in curve 305 of the pressure nor in curve 303 of the position of the outlet valve nor in curve 301 of the measured value of hydrogen sensor 209. Accordingly, it can be concluded that outlet valve 205 is not opened.
Claims
1. A diagnostic method (100) for diagnosing a state of a hydrogen sensor (209) in a fuel cell system (200), wherein: The diagnostic method (100) comprises: - operating (101) the fuel cell system (200), - determining (103) a measured value of the hydrogen concentration in the cathode subsystem (203) of the fuel cell system (200) by the hydrogen sensor (209), - opening (105) the exhaust valve (205) of the fuel cell system (200) so as to connect the anode subsystem (201) of the fuel cell system (200) in fluid communication with the cathode subsystem (203), If the measured value ascertained by the hydrogen sensor (209) does not rise above a predetermined threshold value within a predetermined time period after the discharge valve has been opened, a fault message is output (107).
2. The diagnostic method (100) according to claim 1, characterized in that: The diagnostic method (100) further comprises: - determining the pressure in the anode subsystem (201) by means of a pressure sensor (213) arranged in the anode subsystem (201) upstream of the outlet valve; - verifying the fluid-connected connection of the anode subsystem (201) to the cathode subsystem (203) by opening the discharge valve (209) using the measured value ascertained by the pressure sensor (213).
3. The diagnostic method (100) according to claim 2, characterized in that: During verification, if the measured value obtained by the pressure sensor (213) drops below a given threshold value within a given time period after outputting a control command for opening the discharge valve (205), an opening verification signal is output, wherein the opening verification signal includes a message confirming the connection between the anode subsystem (201) and the cathode subsystem (203).
4. The diagnostic method (100) according to one of the preceding claims, characterized in that The diagnostic method (100) further comprises: - closing the exhaust valve (205) of the fuel cell system (200) in order to separate the anode subsystem (201) from the cathode subsystem (203), If the measured value ascertained by the hydrogen sensor (209) does not fall below a predefined threshold value within a predefined time period after closing the discharge valve (205), a fault message is output.
5. The diagnostic method (100) according to claim 4, characterized in that: The given time period after closing the discharge valve (205) starts from a time point when a given gas flow time has passed after closing the discharge valve (205).
6. A fuel cell system (200), wherein: The fuel cell system (200) comprises: - an anode subsystem (201), - cathode subsystem (203), - a discharge valve (205) which, in an open state, opens a path connecting the anode subsystem (201) to the cathode subsystem (203) in fluid communication, and which, in a closed state, closes the path, a hydrogen sensor (209) arranged in the anode subsystem (201) before the discharge valve (205) in the flow direction of the operating medium flowing through the anode subsystem (201), - a control device (211), Wherein, the control device (211) is configured as: - operating the fuel cell system (200) at a given operating point, - using the hydrogen sensor (209) to determine a measured value of the hydrogen concentration in the cathode subsystem (203) of the fuel cell system (200), - opening the discharge valve (205) so as to connect the anode subsystem (201) in fluid communication with the cathode subsystem (203), If the measured value ascertained by the hydrogen sensor (209) does not rise above a predefined threshold value within a predefined time period after the discharge valve (205) has been opened, a fault message is output.
7. The fuel cell system (200) according to claim 6, characterized in that: The fuel cell system (200) also includes a pressure sensor (213) arranged in the anode subsystem (201) before the discharge valve (205) in the flow direction, and the control device (211) is also configured to verify the fluid connection between the anode subsystem (201) and the cathode subsystem (203) achieved by opening the discharge valve (205) with the help of the measurement value obtained by the pressure sensor (213).
8. The fuel cell system (200) according to claim 7, characterized in that: The control device (211) is configured to output an opening verification signal if a measured value obtained by the pressure sensor (213) drops below a given threshold value within a given time period after outputting a control command for opening the exhaust valve (205), wherein the opening verification signal includes a message confirming the connection between the anode subsystem (201) and the cathode subsystem (203).
9. The fuel cell system (200) according to any one of claims 6 to 8, characterized in that: The control device (211) is also configured to close the discharge valve (205) to separate the anode subsystem (201) from the cathode subsystem (203), and to output a fault message if the measured value obtained by the hydrogen sensor (209) does not drop below a given threshold value within a given time period after closing the discharge valve (205).
10. The fuel cell system (200) according to claim 9, characterized in that: The given time period after closing the discharge valve (205) starts from a time point when a given gas flow time has passed after closing the discharge valve (205).