Diagnostic method for fuel cell system and fuel cell system
By introducing a shutdown process and a pre-determined power requirement curve in the fuel cell system, the state of the fuel cell system is diagnosed, and the problem of excessive difference in voltage and current change curves caused by the reduction of catalytic activity is solved, and the fuel cell system is realized Effective monitoring and early warning of the status extend the service life of the system.
Patent Information
- Application Number
- CN202380048599.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-22
- Filing Date
- 2023-06-22
- Publication Date
- 2025-02-07
AI Technical Summary
The catalytic activity of the fuel cell system decreases during aging, resulting in too large differences between the voltage change curve and the current change curve from the pre-given reference change curve, making it difficult to effectively diagnose the system status.
By introducing the shutdown process of the fuel cell system, the cathode shutdown valve is closed, and the power output is adjusted according to the preset power requirement curve, the voltage change curve and/or current change curve are obtained, and the preset reference change curve is performed with the preset reference change curve Comparison, output warning notification when the difference exceeds the diagnostic threshold.
It realizes effective diagnosis of the status of the fuel cell system, can identify aging conditions in advance, and extend the service life of the fuel cell through warning notifications and repair functions that reverse the aging effect.
Smart Images
Figure CN119404344A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a diagnosis method for a fuel cell system and a fuel cell system. Background Art
[0002] Fuel cell systems convert chemical energy into electrical energy or vice versa. For this purpose, fuel cells are used, which wear out or age during their use. In particular, the catalytic activity decreases as the age of the fuel cell increases. Summary of the invention
[0003] In the context of the proposed invention, a diagnostic method and a fuel cell system are proposed. Further features and details of the invention are derived from the respective dependent claims, the description and the drawings. Features and details described in the context of the diagnostic method according to the invention naturally also apply in the context of the fuel cell system according to the invention, and vice versa, so that with regard to the disclosure of the individual inventive aspects, reference is always made to one another or can be made to one another.
[0004] The proposed invention is used in particular for determining the state of a fuel cell system.
[0005] Therefore, according to a first aspect of the proposed invention, a diagnostic method for diagnosing the state of a fuel cell of a fuel cell system is proposed.
[0006] The diagnostic method includes introducing a shutdown process of the fuel cell system, by closing the cathode shut-off valve of the fuel cell system and adjusting a predetermined power requirement curve on the fuel cell system, and obtaining a voltage change curve and / or a current change curve of at least one fuel cell of the fuel cell system during power output according to the power requirement, comparing the obtained voltage change curve and / or the obtained current change curve with a predetermined reference change curve, and outputting a warning notification in the case where the obtained voltage change curve and / or the obtained current change curve differs from the reference change curve at least regionally by a value greater than a predetermined diagnostic threshold.
[0007] The proposed invention is based on the following principle: During the shutdown process of the fuel cell system, the residual oxygen in the fuel cell stack of the fuel cell system is consumed by so-called "bleeding", i.e., by operating the fuel cell system with a predetermined power requirement, in order to infer the state of the corresponding fuel cells of the fuel cell stack. For this purpose, the properties of the fuel cells during the shutdown process are determined using voltage sensors and / or current sensors. The measured values thus determined or the corresponding voltage profile and / or current profile are compared with a predetermined reference profile, so that a warning message can be output if the determined voltage profile and / or the determined current profile differs from the reference profile at least regionally by a value greater than a predetermined diagnostic threshold value. The warning message can be output to a user of the fuel cell system in order to inform the user of the critical state of the fuel cell system and / or can be transmitted to a server in order to plan maintenance and / or can be transmitted to a computing unit in order to activate predetermined countermeasures, for example, activation of a repair function of the fuel cell system to reverse reversible aging effects.
[0008] It can be provided that a warning message is output if the ascertained voltage profile has a region of increasing voltage after a continuously decreasing region.
[0009] The region of increasing voltage following the region of decreasing voltage is also referred to as a “rebound” and is characteristic of fuel cells with reduced catalytic activity, since these do not immediately convert the corresponding oxygen that is available, so that a surplus of oxygen accumulates and the voltage rises higher at the end of the power demand than was set according to the power demand.
[0010] Furthermore, it may be provided that the diagnostic threshold comprises a first value at a first time and a second value at a second time, wherein a warning message is output if the determined measured value of the voltage profile is less than the first value at the first time and greater than the second value at the second time.
[0011] The rebound can be reflected in a simple and computationally efficient manner via two thresholds, wherein a first threshold indicates an upper threshold and a second threshold indicates a lower threshold, so that a rebound can be considered to exist if it is below the first threshold and above the second threshold. Depending on the size of the first or second threshold, a minimum rebound can be tolerated without warning notification.
[0012] Furthermore, it can be provided that the diagnostic method further comprises an activation step in which a program for counteracting aging effects of the fuel cell system is activated if a warning message is output.
[0013] A program to counteract aging effects may be, for example, a maintenance program in which the fuel cell system is flushed with hydrogen only in order to expel oxygen deposits.
[0014] Furthermore, it can be provided that the warning message includes a characteristic value which quantifies the state of the fuel cell system, wherein the characteristic value is determined as a function of a deviation of the ascertained voltage profile and / or the ascertained current profile from a diagnostic threshold value.
[0015] Characteristic values which quantify the state of the fuel cell system can be used, for example, to observe changes in the fuel cell system over time, ie during different shutdown processes, so that, for example, times for maintenance can be extrapolated and accordingly predicted for the future.
[0016] Furthermore, it can be provided that the determined voltage profile comprises a slope of at least one region of the voltage profile and / or that the determined current profile comprises a slope of at least one region of the current profile.
[0017] The slope indicates a change in the voltage profile or in the current profile in a computationally efficient manner, so that a change in the slope can be used as an indicator for a change in the state of the respective fuel cell.
[0018] Furthermore, it can be provided that the characteristic value is increased if the slope of the ascertained voltage profile and / or the slope of the ascertained current profile decreases.
[0019] Since a decreasing slope indicates a less active or aged fuel cell, this condition may be reflected by an increase in the characteristic value.
[0020] Furthermore, it can be provided that the slope is determined by means of an area derivation of the voltage profile and / or by means of an area derivation of the current profile.
[0021] The voltage or current behavior of the fuel cell can be observed in a computationally efficient manner using the derivation over the entire predetermined range. Accordingly, any desired range can be selected and comprehensively evaluated.
[0022] Furthermore, it can be provided that the warning message is transmitted to the server via the wireless interface.
[0023] By means of a wireless interface, such as a WLAN interface or a mobile radio interface, the corresponding determined data or warning messages can be transmitted to a server, which can be, for example, a central database which automatically plans and manages the maintenance of the fuel cell system in response to the data transmitted by the fuel cell system.
[0024] According to a second aspect, the proposed invention relates to a fuel cell system comprising a computing unit which is configured to carry out a possible configuration of the proposed diagnostic method.
[0025] Further advantages, features and details of the invention emerge from the following description, in which various exemplary embodiments are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The accompanying drawings show:
[0027] Figure 1 A possible configuration of the proposed diagnostic method is shown,
[0028] Figure 2 A schematic diagram showing a possible configuration of the proposed fuel cell system,
[0029] Figure 3 Show according to Figure 2 Voltage variation curve of the fuel cell of the fuel cell system. DETAILED DESCRIPTION
[0030] exist Figure 1 A diagnostic method 100 for diagnosing a state of a fuel cell system is shown in FIG.
[0031] The diagnostic method 100 comprises an initiation step 101 in which a shutdown process of the fuel cell system is initiated by closing a cathode shutoff valve of the fuel cell system and setting a predefined power demand profile at the fuel cell system in accordance with a predefined power demand.
[0032] Furthermore, the diagnostic method 100 comprises a determination step 103 in which a voltage profile and / or a current profile of at least one fuel cell of the fuel cell system is determined during a power withdrawal in accordance with a power demand.
[0033] Furthermore, the diagnostic method 100 comprises a comparison step 105 in which the ascertained voltage profile and / or the ascertained current profile is compared with a predefined reference profile.
[0034] Furthermore, diagnostic method 100 comprises an output step 107 in which a warning message is output if the ascertained voltage profile and / or the ascertained current profile differs from the reference profile at least regionally by an amount greater than a predefined diagnostic threshold value.
[0035] exist Figure 2A fuel cell system 200 is shown in FIG. The fuel cell system 200 comprises a computing unit 201 which is configured to carry out the diagnostic method 100 .
[0036] exist Figure 3 Graph 300 is shown in . Graph 300 extends on its abscissa over time, for example in [s], and on its ordinate over voltage in [V] or current in [A].
[0037] Curve 301 shows the voltage profile of an aged fuel cell.
[0038] Curve 303 indicates a predefined reference curve.
[0039] Diagnostic threshold 305 is exemplarily 5 V. Since curve 301 rebounds at time t1 and differs from curve 303 by a value greater than diagnostic threshold 305 , the fuel cell can be identified as aged and a corresponding warning message can be output.
[0040] Curve 307 shows the current curve of the fuel cell. In the present case, this current curve has the value “0” at time t1.
Claims
1. A diagnostic method (100) for diagnosing a state of a fuel cell of a fuel cell system (200), in, The diagnostic method (100) comprises: - initiating (101) a shut-down process of the fuel cell system (200) by closing a cathode shut-off valve of the fuel cell system (200) and setting a predetermined power requirement curve on the fuel cell system (200) according to a predetermined power requirement, - determining (103) a voltage profile and / or a current profile of at least one fuel cell of the fuel cell system (200) during power delivery according to the power requirement, - comparing the determined voltage profile and / or the determined current profile with a predefined reference profile (105), - outputting (107) a warning message in the event that the determined voltage profile (301) and / or the determined current profile (307) differ from the reference profile (303) at least regionally by a value greater than a predefined diagnostic threshold value (305).
2. The diagnostic method (100) according to claim 1, It is characterized in that The warning message is output if the determined voltage profile (301) has an increasing voltage region after a continuously decreasing region.
3. The diagnostic method (100) according to claim 1 or 2, It is characterized in that The diagnostic threshold value (305) comprises a first value at a first time point and a second value at a second time point, wherein the warning message is output if the determined measured value of the voltage profile (301) is less than the first value at the first time point and greater than the second value at the second time point.
4. The diagnostic method (100) according to any one of the preceding claims, It is characterized in that The diagnostic method (100) further comprises an activation step in which, if the warning notification is output, a program of the fuel cell system (200) for counteracting aging effects is activated.
5. The diagnostic method (100) according to any one of the preceding claims, It is characterized in that The warning message comprises a characteristic value which quantifies the state of the fuel cell system (200), wherein the characteristic value is determined as a function of a deviation between an ascertained voltage profile (301) and / or an ascertained current profile (307) and the diagnostic threshold value (305).
6. The diagnostic method (100) according to any one of the preceding claims, It is characterized in that The determined voltage profile (301) includes a slope of at least one region of the voltage profile (301) and / or the determined current profile (307) includes a slope of at least one region of the current profile (307).
7. The diagnostic method (100) according to claims 5 and 6, It is characterized in that If the slope of the ascertained voltage profile (301) and / or the slope of the ascertained current profile (307) decreases, the characteristic value is increased.
8. The diagnostic method (100) according to claim 6, It is characterized in that The slope is determined by means of a regional derivation of the voltage profile (301) and / or by means of a regional derivation of the current profile (307).
9. The diagnostic method (100) according to any one of the preceding claims, It is characterized in that The warning notification is transmitted to a server via a wireless interface.
10. A fuel cell system (200) for converting energy, in, The fuel cell system (200) comprises a computing unit (201) configured to execute the diagnostic method (100) according to any one of claims 1 to 9.