Pretreatment method and diagnostic method for fuel cell system

Abstract

The proposed invention relates to a pretreatment method (100) for pretreating a fuel cell system (300), which comprises a connection path (307) for conducting fluid connection of a cathode subsystem (303) and an anode subsystem (305) of the fuel cell system (300), the pretreatment method (100) comprises:-inerting (101) an atmosphere in the cathode subsystem (303) of the fuel cell system (300) and an atmosphere in the anode subsystem (305) of the fuel cell system (300),-closing (103) a cathode shut-off valve of the cathode subsystem (303),-closing (105) the connection path (307) between the cathode subsystem (303) and the anode subsystem (305), wherein the pre-treatment method (100) is executed in order to prepare for a diagnostic method (200) for diagnosing a state of a fuel cell system (300) in a vehicle (400).

Description

Technical Field

[0001] The present invention relates to a preprocessing method, a diagnostic method, a vehicle, and a computer program product for diagnosing the condition of a fuel cell system in a vehicle, according to the appended claims. Background Technology

[0002] To diagnose the condition of a fuel cell system, voltage-manipulated diagnostic methods, such as cyclic voltammetry, are typically used. In this method, each individual fuel cell in the fuel cell stack is repeatedly subjected to a voltage triangular wave to determine characteristic values, particularly the active platinum area, i.e., the electrochemically active area of ​​each fuel cell. Summary of the Invention

[0003] Within the framework of the proposed invention, a preprocessing method, a diagnostic method, a vehicle, and a computer program product are provided. Further features and details of the invention are derived from the corresponding dependent claims, the specification, and the drawings. Herein, the features and details described in connection with the diagnostic method according to the invention also apply to the diagnostic system according to the invention, the vehicle according to the invention, or the computer program product according to the invention, and vice versa, so that the disclosures of each aspect of the invention are always mutually referenced or may be mutually referenced.

[0004] The proposed invention is particularly useful for providing a possibility for determining the state of a fuel cell system in a vehicle.

[0005] Therefore, according to the first aspect of the invention, a pretreatment method for pretreating a fuel cell system is proposed, the fuel cell system including a connection path for conductively connecting the cathode subsystem and the anode subsystem of the fuel cell system.

[0006] The proposed pretreatment method includes inertizing the atmosphere in the cathode subsystem and the anode subsystem of the fuel cell system, closing the cathode shut-off valve of the cathode subsystem, and closing the connection path between the cathode subsystem and the anode subsystem. The pretreatment method is performed to prepare for a diagnostic method for diagnosing the condition of the fuel cell system in a vehicle.

[0007] The proposed preprocessing method induces a state in which the fuel cell system is favorable for measurement by the proposed diagnostic method, enabling the acquisition of accurate and stable diagnostics or reliable or dependable characteristic values. Accordingly, the fuel cell system can be optimized or tuned with particular precision according to its corresponding state, for example, to minimize the aging of the fuel cell stack.

[0008] To address this, the proposed pretreatment method is based on a system topology having a connecting path for conductive fluid between the cathode and anode subsystems, allowing inert gas to flow, for example, from the cathode subsystem into the anode subsystem. Accordingly, this connecting path is opened for inertization and then closed after inertization.

[0009] The connection path for conducting fluid can be, for example, part of an inertization system used to improve the start-up characteristics of a fuel cell system, or part of a cleaning or drainage system used for so-called “venting” or “flushing” processes, especially for the anode subsystem.

[0010] By inertizing not only the cathode subsystem but also the anode subsystem, it is ensured that the cathode subsystem is reliably or completely inert, even in system topologies with connection paths between the cathode and anode subsystems. Correspondingly, the presence of residual oxygen in the cathode subsystem is prevented when it is shut down.

[0011] It can be configured that the preprocessing method is executed in response to instructions to execute the diagnostic method.

[0012] Because the preprocessing method according to the invention is used to optimize the diagnostic method according to the invention, the preprocessing method can be automatically activated when the diagnostic method should be executed. Therefore, the preprocessing method can be coupled to instructions for executing the diagnostic method or executed as part of the diagnostic method.

[0013] The preprocessing method may also include at least one of the following steps: - Drain the cathode path before inertization. - Fuel-filled anode subsystem - Drain the anode subsystem before or during fuel filling. - Close the anode shut-off valve of the anode subsystem. - To recirculate the atmosphere confined within the anode subsystem. - Open the cleaning valve of the fuel cell system and introduce a mass flow of air into the cathode subsystem to drain and / or dry the cathode subsystem during cathode subsystem inertization. - Open the cleaning valve of the fuel cell system and introduce fuel flow into the anode subsystem to drain and / or dry the anode subsystem before or during inertization.

[0014] For example, the HGI / hydrogen metering valve can be opened or partially opened or adjusted to feed fuel from the tank into the anode subsystem; the flush / vent valve can be opened or partially opened or adjusted to vent residual hydrogen and partially vent inert gases and liquid water. Venting liquid water supports the creation of a defined state in the anode subsystem. Optionally, an HRB (Hydrogen recirculation blower bzw. Brennstoffrezirkulationsgebläse, hydrogen recirculation blower or fuel recirculation blower) can be operated to support recirculation, wherein an injection pump is used as a base.

[0015] At the end of the pretreatment process, there exists an inert cathode subsystem and an anode subsystem filled with fuel, particularly hydrogen. This pretreatment process provides a sufficiently defined framework for diagnostic methods within the fuel cell system, allowing subsequent diagnostic procedures to be performed.

[0016] It can also be configured to introduce inert gas from the cathode subsystem into the anode subsystem in order to inertize the anode subsystem, or to generate inert gas using an additional fuel cell stack and introduce it into the anode subsystem.

[0017] Additional or second fuel cell stacks in a fuel cell system can be used as an inert gas source. Alternatively, a tank containing inert gas can also be used as an inert gas source.

[0018] By using an inert gas source independent of the respective fuel cell stack to be pretreated, sufficient inert gas is available to purge, for example, the cathode and / or anode subsystems of the fuel cell stack to be pretreated, thereby causing, for example, drying. Furthermore, the anode subsystem can also be supplied with inert gas after the connection path has been closed.

[0019] According to the second aspect, the proposed invention relates to a diagnostic method for diagnosing the condition of a fuel cell system in a vehicle.

[0020] The proposed diagnostic method includes loading the fuel cell stack of the fuel cell system with current from a current source, measuring the voltage on each fuel cell of the fuel cell stack, obtaining characteristic values ​​of the state of the fuel cell system based on the measured voltage, and outputting the characteristic values ​​on the output unit, wherein the voltage on each fuel cell of the fuel cell stack is measured simultaneously.

[0021] Optionally, the proposed diagnostic method includes performing the proposed pretreatment method.

[0022] In the context of the proposed invention, the characteristic value is understood as a value on a scale or a numerical value.

[0023] The proposed diagnostic method is based on current manipulation. This means that a pre-given current is applied as an independent variable to the fuel cell stack or its individual fuel cells, and the change in voltage applied to each fuel cell in response to the applied current is used as a dependent variable to obtain or analyze its characteristic value. Accordingly, characteristic values ​​quantifying the state of the fuel cell or fuel cell system are obtained based on the voltage change curves during the applied current and subsequent self-discharge.

[0024] The obtained characteristic values ​​are output, provided, or stored on an output unit, such as a display and / or a memory.

[0025] To measure the voltage on each fuel cell in a fuel cell system, a so-called "cell voltage monitoring system" or an external voltage measuring device can be used.

[0026] Based on the voltages obtained separately, the corresponding characteristic values ​​can be derived using equation (1). The method is as follows: equation (1) is applied at, for example, 400mV (= U). lb ) and 500mV (= U ub The values ​​are fitted to the measurement data within a certain range. Electrochemical reactions will not occur on the catalyst only within this range.

[0027] Here, U(t) represents the voltage measured at time point t, and I Q R represents the applied current. SC Represents short-circuit resistance, t lb Indicates that U is reached during the charging process. lb Time, C dl Represents double-layer capacitance and I H2 This represents the discharge current, which is independent of voltage.

[0028] During the self-discharge, no current flows through the short-circuit resistor, causing the double-layer capacitance to discharge from U. ub to U lb The area is only composed of I H2 Discharge: .

[0029] With the help of double-layer capacitance in U ub and U lb The discharge rate (2) between these points can eliminate the double-layer capacitance from equation (1): .

[0030] Therefore, it is still necessary to use quantity I only during charging. H2 and R sc Fit the equation to voltage U lb and U ub On the measurement points between.

[0031] In order to generate an atmosphere suitable for performing the proposed diagnostic method around the working electrode of the corresponding fuel cell system, a so-called self-inertization is provided according to the invention, in which an atmosphere is generated by an inert gas, especially pure nitrogen.

[0032] It can be configured such that the cathode of the fuel cell system is used as the working electrode and a pure nitrogen atmosphere surrounding the working electrode is generated through the self-inertization process.

[0033] The cathode of a fuel cell system is particularly suitable as the working electrode because the air system of a fuel cell system in a vehicle can be controlled or configured to create inert conditions or accumulate inert gases from the air.

[0034] It is possible to configure the anode of the fuel cell system to be used as the counter electrode and to operate in a hydrogen atmosphere or a hydrogen-nitrogen atmosphere.

[0035] It can also be configured such that, during self-inertia, the inlet and outlet on the air side of the fuel cell system are closed, and the fuel cell system is shut off via a resistor, so that the residual oxygen on the air side is converted.

[0036] Through a resistor-based shutdown process, known as "bleed-down," a voltage is generated during the shutdown process of the corresponding fuel cell system, thereby consuming the remaining reactants in the fuel cell system, particularly the oxygen in the air on the cathode side. The input of fresh air and the oxygen contained therein is blocked by closing the inlet and outlet on the air side of the fuel cell system. Accordingly, an inert atmosphere is created through this shutdown process, resulting in a nitrogen-based atmosphere at the cathode.

[0037] Alternatively, the system can be configured to interrupt the input of fresh air to the air side of the fuel cell system during self-inertia, and to shut off the fuel cell system via a resistor during active exhaust gas recirculation, so that the oxygen remaining on the air side is converted.

[0038] By actively drawing back the exhaust gas, the atmosphere formed around the cathode is circulated, allowing the nitrogen atmosphere to continuously flow along the cathode.

[0039] It can also be set that at least one of the following characteristic numbers from the list of characteristic numbers is used as the characteristic value: electrochemical active area, hydrogen film leakage, double layer capacitance, catalyst capacitance, roughness factor, and film short-circuit resistance.

[0040] Eigenvalues ​​can be output as numerical values ​​or assigned to scale values ​​using assignment charts (Zuordnungsschemas), such as to color charts and / or to values ​​on ordinal scales, and then output. Of course, eigenvalues ​​can include multiple sub-eigenvalues, which include corresponding eigenvalue numbers or are based on corresponding eigenvalue numbers.

[0041] In addition, the fuel cell system can be configured to discharge via self-discharge after the applied current is applied.

[0042] In order to be able to test the electrochemical characteristics of individual fuel cells, self-discharge has proven to be particularly suitable because the voltage drops slowly, i.e., over several seconds, during this type of discharge, which should be attributed solely to the physical characteristics of the fuel cell (Equation (2)).

[0043] Additionally, it can be configured to apply current to the fuel cell stack within a single charging cycle.

[0044] In contrast to voltage-guided methods, the proposed diagnostic method can be performed through a single charging cycle. This means that the fuel cell is charged to a predetermined maximum voltage value at a predetermined current value in a single charge cycle and then self-discharges. Each fuel cell should reach a minimum of 500mV (U) at the current-off point. ub This allows for the execution of analysis and evaluation.

[0045] It can also be set that, when calculating the characteristic value, the short-circuit resistance of each fuel cell in the fuel cell stack is obtained from the rising region of the voltage change curve when the current is applied to the fuel cell stack (Equation (3)).

[0046] The short-circuit resistance of each fuel cell can be quickly and easily obtained using a so-called "fitting function".

[0047] It is also possible to configure the voltage-independent discharge current (If) of each fuel cell in the fuel cell stack when calculating the eigenvalues. H2 The current is obtained from the rising region of the voltage change curve when a current is applied to the fuel cell stack, which corresponds to the transfer of molecular state H2 across the fuel cell membrane as depicted by the CV / LSC method.

[0048] The voltage-independent discharge current of each fuel cell can also be quickly and easily obtained using a "fitting function". In the self-discharge region, the voltage-independent discharge current at U can be determined by measurements. ub and U lb The discharge rate between them and therefore the double-layer capacitance C is also determined by means of equation (2). dl .

[0049] Due to the simple interrelationship in equation (2), the double-layer capacitance C in equation (1) is... dl It can be replaced by a known quantity, which leads to equation (3). Therefore, the fitting algorithm only needs to determine the two unknown I values ​​simultaneously. H2 and R sc .

[0050] To calculate the roughness factor of the desorption process, we examine the values ​​below U using the quantities determined above. lb The charging range. The hydrogen desorption process can be considered as one of the capacitors connected in parallel with the electric double layer, whose charge does not increase linearly with voltage or remain constant.

[0051] According to a third aspect, the proposed invention relates to a vehicle. The proposed vehicle includes a computing unit configured in a possible configuration for implementing the proposed preprocessing method and / or diagnostic method.

[0052] In the context of the proposed invention, the computing unit is understood to be a computer, processor, control device, or any other programmable circuit. In particular, the computing unit can be a control device for a corresponding fuel cell system.

[0053] According to the fourth aspect, the proposed invention relates to a computer program product having program code that, when implemented on a computer, configures the computer to perform possible implementations of the proposed preprocessing method and / or diagnostic method.

[0054] The proposed computer program product may be, for example, a file or data carrier on a server for download, such as a CD-ROM or USB flash drive.

[0055] The advantages of the pretreatment method for pretreatment of a fuel cell system described in detail in the first aspect of the invention are also applicable to the diagnostic method for diagnosing the condition of a fuel cell system in a vehicle according to the second aspect of the invention, as well as to vehicles according to the third aspect of the invention and computer program products according to the fourth aspect of the invention.

[0056] Other advantages, features, and details of the invention will become apparent from the following description, in which embodiments of the invention are described in detail with reference to the accompanying drawings. Herein, the features mentioned in the claims and the description are substantially important to the invention, individually or in any combination. Attached Figure Description

[0057] The attached diagram shows: Figure 1 One possible configuration of the proposed preprocessing method. Figure 2One possible configuration of the proposed diagnostic method. Figure 3 Used for implementation according to Figure 1 The system topology of the preprocessing method, and Figure 4 : One possible configuration of the proposed vehicle. Detailed Implementation

[0058] exist Figure 1 The diagram illustrates a pretreatment method 100 for pretreating a fuel cell system, the fuel cell system including a connection path for conductively connecting the cathode subsystem and the anode subsystem of the fuel cell system.

[0059] The pretreatment method 100 includes an inertization step 101, in which the atmosphere in the cathode subsystem and the anode subsystem of the fuel cell system are inertized; a first shut-off step 103, in which the cathode shut-off valve of the cathode subsystem is closed; and a second shut-off step 105, in which the connection path between the cathode subsystem and the anode subsystem is closed.

[0060] Preprocessing method 100 is performed to prepare for diagnostic methods used to diagnose the condition of a fuel cell system in a vehicle.

[0061] exist Figure 2 Diagnostic method 200 is shown. This diagnostic method 200 includes an optional preprocessing step 201, in which the diagnostic method 200 is performed according to... Figure 1 The preprocessing method 100 includes a current-passing step 203, in which a current from a current source is passed through the fuel cell stack of the fuel cell system; a measurement step 205, in which the voltage on each fuel cell of the fuel cell stack is measured; a calculation step 207, in which characteristic values ​​for quantifying the state of the fuel cell system are determined based on the measured voltages; and an output step 209, in which the characteristic values ​​are output on an output unit, wherein the voltage on the corresponding fuel cell of the fuel cell stack is measured simultaneously.

[0062] exist Figure 3 The image shows a fuel cell system 300. The fuel cell system 300 includes a first fuel cell stack 301 having a cathode subsystem 303, an anode subsystem 305, a cooling circuit 313, and a connection path 307 between the cathode subsystem 303 and the anode subsystem 305.

[0063] The connection path 307 can be switched via one or two shut-off valves 315 to be interrupted, i.e., not conducting fluid, or to be released, i.e. conducting fluid.

[0064] In addition, the fuel cell system 300 includes a second fuel cell stack 309 constructed similarly to the first fuel cell stack 301, which is connected to the first fuel cell stack 301 via a fluid conduit such that inert gas discharged from the second fuel cell stack can flow into the cathode subsystem 303 and / or anode subsystem 305 of the first fuel cell stack 301.

[0065] The fuel cell system 300 also includes a flushing / draining valve 315, through which the anode subsystem 303 and / or cathode subsystem 301 of the first fuel cell stack 301 can be cleaned.

[0066] The first fuel cell stack 301 and the second fuel cell stack 309 are supplied with air via a common air supply system 317 and their exhaust gases are discharged into the surrounding environment via a common exhaust system 319.

[0067] The waste gas can be metered into the air supply system 317 via the optional waste gas backflow valve 321, thereby causing or supporting the inertization of the cathode subsystem 303 and / or the anode subsystem 305, for example.

[0068] The first fuel cell stack 301 is supplied with fuel via the first fuel supply system 323.

[0069] The second fuel supply stack 309 is fueled via the second fuel supply system 325.

[0070] exist Figure 4 The image shows a vehicle 400. The vehicle 400 includes a computing unit 401 in the form of a control device and a [database / system / etc.]. Figure 3 The fuel cell system 300, wherein the control device is configured to perform according to Figure 1 Preprocessing method 100 and / or according to Figure 2 Diagnostic methods 200.

[0071] The computing unit 401 may optionally be communicatively coupled to the battery voltage detection system 403 of the vehicle 400.

Claims

1. A pretreatment method (100) for pretreating a fuel cell system (300), the fuel cell system including a connection path (307) for conductively connecting a cathode subsystem (303) and an anode subsystem (305) of the fuel cell system (300), wherein, The preprocessing method (100) includes: - Inertize the atmosphere in the cathode subsystem (303) and the atmosphere in the anode subsystem (305) of the fuel cell system (300) (101). - Close the cathode shut-off valve of the cathode subsystem (303) described in (103), - Close (105) the connection path (307) between the cathode subsystem (303) and the anode subsystem (305). The preprocessing method (100) is performed to prepare for a diagnostic method (200) for diagnosing the condition of the fuel cell system (300) in the vehicle (400).

2. The preprocessing method (100) according to claim 1. Its features are, The preprocessing method (100) is executed in response to an instruction for performing the diagnostic method (200).

3. The pretreatment method (100) according to claim 1 or 2. Its features are, The preprocessing method (100) further includes at least one of the following steps: - Drain the cathode path (303) before inertization (101), - Fill the anode subsystem (305) with fuel. - Before or after this, drain the anode subsystem (305). - Close the anode shut-off valve of the anode subsystem (305). - To recirculate the atmosphere enclosed in the anode subsystem (305), - Open at least one cleaning valve (315) of the fuel cell system (300) and introduce a mass flow of air into the cathode subsystem (303) to drain and / or dry the cathode subsystem (303) during the inertization (101) of the cathode subsystem (303). - Open the cleaning valve (315) of the fuel cell system (300) and introduce fuel flow into the anode subsystem (305) so that the anode subsystem (305) is drained and / or dried before or during the inertization (101) of the anode subsystem (305).

4. The pretreatment method (100) according to any one of the preceding claims. Its features are, To inertize the anode subsystem (305) (101), an inert gas is introduced from the cathode subsystem (303) into the anode subsystem (305), or an inert gas is generated by an additional fuel cell stack (309) and introduced into the anode subsystem (305).

5. The pretreatment method (100) according to any one of the preceding claims. Its features are, The connection path (307) is a direct pipeline between the cathode subsystem (303) and the anode subsystem (305), or includes a cleaning pipeline for cleaning the anode subsystem (305) or a drainage pipeline for draining the anode subsystem (305).

6. A diagnostic method (200) for diagnosing the condition of a fuel cell system (300) in a vehicle (400), wherein, The diagnostic method (200) includes: - The fuel cell stack (301) of the fuel cell system (300) is loaded with current from a current source. -Measure (205) the voltage on each fuel cell of the fuel cell stack (301), -Based on the measured voltage, (207) characteristic values ​​quantifying the state of the fuel cell system (300) are obtained. - Output the characteristic value described in (209) on the output unit. Meanwhile, the voltage measurement (205) on each fuel cell of the fuel cell stack (301) is performed simultaneously.

7. The diagnostic method (200) according to claim 6. Its features are, The diagnostic method (200) includes: performing a pretreatment method (100) according to any one of claims 1 to 5.

8. The diagnostic method (200) according to claim 6 or 7. Its features are, The characteristic value is obtained by continuously changing the input parameters of the physical model of the fuel cell system (300) until the difference between the first change curve of the measured voltage and the second change curve output by the model meets a pre-given standard.

9. The diagnostic method (200) according to any one of claims 6 to 8. Its features are, The voltage values ​​measured during the measurement (205) are transmitted to the server and the server is configured to: perform the calculation (207), and determine, during the calculation (207) based on the measured voltage values, a potential future operational failure of the fuel cell system (300), and report the operational failure during the output (209), and activate countermeasures stored in the allocation chart in the fuel cell system (300).

10. Vehicles (400) in, The vehicle (400) includes a fuel cell system (300) and a computing unit (401), wherein the computing unit (401) is configured to perform a preprocessing method (100) according to any one of claims 1 to 5 and / or a diagnostic method (200) according to any one of claims 6 to 9.

11. A computer program product having program code that, when implemented on a computer, configures the computer to perform a preprocessing method (100) according to any one of claims 1 to 5 and / or a diagnostic method (200) according to any one of claims 6 to 9.

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