Method and system for ignition detection in a fuel cell

Abstract

Method for monitoring a fuel cell system (1), in particular for ignition detection in the fuel cell system (1), comprising: - detecting (S10) at least one temperature profile (5, 6) in a fuel cell system (1); - detecting (S20) an ignition event in the fuel cell system (1) based on the detected temperature profile (5, 6), wherein the detection (S20) of the ignition event comprises determining a similarity with which a temperature increase profile and a temperature decrease profile of the detected temperature profile (5, 6) following the temperature increase profile correspond to a predetermined temperature increase profile and a predetermined temperature decrease profile of an ignition event.

Description

[0001] The present invention relates to a method and a system for monitoring a fuel cell system, in particular for ignition detection in the fuel cell system.

[0002] Using hydrogen and oxygen, fuel cells typically convert chemical energy into electrical energy. The energy generated in this way can be used as propulsion energy, for example, to power a vehicle. The hydrogen required for this purpose is usually carried on board the vehicle in a dedicated tank. The required oxygen is typically taken from the ambient air. During operation, hydrogen is typically supplied to the anode of the fuel cell, and air is supplied to the cathode.

[0003] In fuel cells operated with hydrogen and air, in particular systems in which fuel cells are used, leaks can occur in individual cases due to operation and / or a fault, in particular as a result of a rear-end collision when the fuel cell system is used in a vehicle, as a result of which an ignitable mixture of hydrogen and air, in particular oxygen, can form. A leak in a fuel cell can lead to fuel or oxidant escaping from the fuel cell, in particular in an uncontrolled manner, which can lead to an unexpected ignition event. If fuel and oxidant come into contact in a sufficiently high concentration, usually with at least 5% fuel or hydrogen, an uncontrolled and dangerous reaction can occur which can cause a, particularly high, development of heat and / or explosion(s).

[0004] It is a particular object of the invention to further improve the safety of a fuel cell, in particular during operation, and in particular to improve leak detection.

[0005] This object is achieved according to the teaching of the independent claims. Various embodiments and further developments of the invention are the subject of the dependent claims.

[0006] According to one aspect of the invention, a method for monitoring a fuel cell system, in particular for ignition detection in the fuel cell system, is provided. The method comprises recording at least one temperature profile in the fuel cell system, in particular in or on the at least one fuel cell of the fuel cell system. The method further comprises detecting an ignition event in the fuel cell system, in particular in or on the at least one fuel cell of the fuel cell system. The method comprises detecting an ignition event in the fuel cell system, in particular the at least one fuel cell of the fuel cell system, based on the recorded temperature profile.

[0007] Detecting the ignition event comprises determining a similarity with which a temperature rise curve and a temperature drop curve following the temperature rise curve correspond to a predetermined temperature rise curve and a predetermined temperature drop curve of an ignition event. In one embodiment, the similarity of at least a portion of the detected temperature rise and the detected temperature drop to a predetermined temperature curve, in particular (at least a portion) of a predetermined temperature rise and / or in particular (at least a portion) of a predetermined temperature drop, in particular based on an at least substantially identical time period, is representative of a detected ignition event.

[0008] This makes it possible for an ignition event to be detected or verified, in particular confirmed, based on a large number of features, in particular the temperature increase and the temperature decrease.

[0009] In other words, generally speaking, detecting the ignition event in the fuel cell system, in particular in or on the at least one fuel cell of the fuel cell system, in one embodiment comprises determining a similarity with which the at least part of the detected temperature profile corresponds, at least substantially, to a predetermined temperature profile of an ignition event, in particular in the fuel cell system, further in particular in the at least one fuel cell of the fuel cell system. In one embodiment, the similarity is a measure that an ignition event has occurred if the temperature profile, in particular at least part of the detected temperature profile, has at least a predetermined similarity to a predetermined temperature profile, in particular a measure of the similarity corresponds to at least a predetermined measure.

[0010] In one embodiment, this advantageously allows an ignition event in the fuel cell system to be detected more precisely, in particular, it can be determined whether an ignition event has occurred in at least one of the fuel cells of the fuel cell system. Advantageously, in one embodiment, this allows an earlier, in particular automated, determination of whether an ignition event has occurred.

[0011] In one embodiment, it can thereby be determined whether at least a part of the detected temperature profile correlates with a predetermined temperature profile of an ignition event in the fuel cell system, which in one embodiment was determined by measurements, in particular as a function of further detectable parameters, further in particular in or on the at least one fuel cell of the fuel cell system, or whether it is likely that an ignition event has occurred, in particular based on a comparison of (at least a part of) the detected temperature profile with the predetermined temperature profile.

[0012] In one embodiment, the detection of the ignition event is based on a predetermined time period and a predetermined temperature difference, more particularly a predetermined temperature difference that is represented or occurs within the time period by the detected temperature profile.

[0013] In one embodiment, detecting an ignition event corresponds to or comprises determining an ignition event probability in the fuel cell system, in particular of the at least one fuel cell in the fuel cell system. In one embodiment, the ignition event probability describes a probability with which an ignition event has occurred in the fuel cell system. In one embodiment, the method further comprises operating the fuel cell system based on detecting the ignition event; in particular, if an ignition event was detected, shutting down, in particular the at least one part of the fuel cell system, or, if no ignition event was detected, (continuing) operating the fuel cell system.

[0014] If, for example, an undesired ignition occurs, in particular of a hydrogen-air mixture, in the fuel cell system, heat is released by the ignition, which can be detected in particular in a temperature increase in the area of ​​the ignition, in particular with suitable means, in particular a suitable sensor, further in particular with a temperature sensor.

[0015] Advantageously, in one embodiment, it can be made possible that an ignition or an ignition event can be detected more reliably, in particular the detection of an ignition event can be detected more easily, in particular with the aid of technology available on the market, so that the method can be implemented more easily and cost-effectively. Advantageously, in one embodiment, an ignition event can be detected more precisely, in particular compared to a pressure sensor that is configured to detect a pressure wave of an ignition event. Pressure changes during ignition events are usually of very short duration compared to temperature changes, so that monitoring a fuel cell system by means of a pressure sensor is more frequent and, in particular, more energy-intensive.Furthermore, it was found that monitoring the fuel cell system for ignition events using a pressure sensor is more error-prone than monitoring the temperature; particularly because a pressure sensor must be designed for large pressure differences, especially for pressure differences of several orders of magnitude and pressure peaks in the millisecond regime. Advantageously, a lower sampling rate can be used in one embodiment, especially compared to pressure sensors.

[0016] In one embodiment, the method comprises determining a forecast of the temperature profile based on the detected temperature profile. In one embodiment, the detection of an ignition event is additionally or alternatively based on the forecast of the temperature profile.

[0017] This allows a countermeasure to be implemented more quickly in one embodiment, in particular preventing a (further) ignition event.

[0018] In one embodiment, the method comprises initiating countermeasures, in particular for securing the fuel cell system, in particular based on the detected ignition event. In one embodiment, a countermeasure is in particular interrupting the hydrogen supply to the fuel cell, switching off the fuel cell, and / or discharging the fuel cell system which has the at least one fuel cell, provided that a residual electrical charge is present. In one embodiment, the initiation of countermeasures relates, in particular only, to the fuel cell stack which has the fuel cell for which an ignition event is or has been detected, indicated or confirmed. In one embodiment, in the event of a detected ordetermined ignition, at least one of the following measures is initiated: an interruption of the hydrogen supply to the fuel cell system, in particular to the fuel cell, a switching off of the fuel cell system, in particular the fuel cell and / or a discharging of the fuel cell system, in particular if a residual electrical charge is present.

[0019] In one embodiment, this advantageously prevents a further ignition event, in particular reduces the risk of an ignition event cascade, and in particular, (better) protects people who, in one embodiment, are (usually) located near the fuel cell system. In one embodiment, this advantageously makes it possible to prevent or enable a second ignition, in particular to reduce, in particular to avoid, a particularly immediate, hazard, particularly due to the leakage of operating fluids or the risk of fire.

[0020] In one embodiment, the initiation of a countermeasure is limited to the part of the fuel cell system in which an ignition event was detected or determined. This allows residual system power to be maintained in one embodiment, particularly in an emergency, to continue to provide (residual) energy, particularly without the risk or with a lower risk of another ignition event.

[0021] In one embodiment, the temperature profile, in particular the temperature rise profile, has a temperature rise of at least 10 Kelvin, in particular at least 15 Kelvin, more particularly at least 20 Kelvin, in particular at operating parameters or operating temperatures typical for the fuel cell system, in particular depending on a proportion of hydrogen in the leakage mixture. In one embodiment, the temperature profile, in particular the temperature rise, relates to a time period of at most 10 seconds, or at most 8 seconds, or at most 6 seconds and / or at least one second, or at least two seconds; or the recorded temperature profile has a corresponding temperature rise within a time period specified herein.In one embodiment, the temperature profile comprises a temperature drop following the temperature rise, which in particular has a gradient typical of an ignition event, in particular a predetermined (in particular negative) gradient, at least substantially. In one embodiment, the temperature profile is limited to a time period of at most 25 seconds, or at most 20 seconds. In particular, experiments have shown that an ignition event, in particular typically, causes a temperature rise and a temperature drop, in particular as described herein, in a time period of at most 25 seconds, or at most 20 seconds.

[0022] As a result, in one embodiment, an ignition event can advantageously be distinguished, in particular better, from an operational temperature increase, in particular a countermeasure as described herein can only be used if an ignition event has occurred.

[0023] In one embodiment, the at least one temperature profile is recorded in a housing of the fuel cell system, in particular at one or more locations in the housing, at an inlet or an outlet of the housing, in particular using a temperature sensor. In one embodiment, the temperature sensor is arranged in the housing.

[0024] In one embodiment, the method comprises additionally detecting an ambient temperature of the fuel cell system, detecting a humidity in the fuel cell system, detecting a humidity outside the fuel cell system, detecting a pressure in the fuel cell system, and / or detecting an ambient pressure of the fuel cell system. In one embodiment, the detection of the ignition event, the determination of a similarity, and / or the determination of a measure of similarity are additionally based on one of the aforementioned additional detected values ​​or parameters. In particular, in one embodiment, a predetermined temperature profile is additionally based on at least one of the aforementioned additional values ​​or parameters.

[0025] In one embodiment, this advantageously allows an ignition event to be detected more precisely, in particular more reliably.

[0026] It is within the scope of the invention that method steps described herein are combined in one embodiment and / or that one method step is integrated into another method step.

[0027] According to one embodiment of the invention, a fuel cell system is provided. In one embodiment, the fuel cell system is configured to carry out a method described herein. In one embodiment, the fuel cell system has at least one fuel cell. In one embodiment, the at least one fuel cell is configured to generate electricity, in particular using fuel gas, more particularly hydrogen, and oxidizing agent, in particular air and / or oxygen. In one embodiment, the fuel cell system has at least one housing, in particular for accommodating the at least one fuel cell. In one embodiment, the fuel cell system has at least one means for detecting a temperature, in particular a temperature sensor. In one embodiment, the fuel cell system has means for detecting a temperature profile in the fuel cell system.In one embodiment, the fuel cell system has means for detecting an ignition event, in particular based on the recorded temperature profile. In one embodiment, the means for detecting an ignition event is an ECU, in particular an ECU of a vehicle having a fuel cell system described herein.

[0028] Advantageously, this makes it possible for the fuel cell system to be protected in a simpler manner against one, in particular further, ignition event, in particular to be compliant with, in particular applicable, standards and / or guidelines, such as SAE J2578, in particular a vehicle which in one embodiment has a fuel cell system described herein complies or can comply with these standards and / or guidelines.

[0029] In one embodiment, the temperature sensor, in particular a temperature measuring tip, has a response time of at most 6 seconds. In one embodiment, the temperature sensor is designed for temperatures of at least 250°C and / or at most 450°C. In one embodiment, the temperature sensor has a tau 90 value (τ 90 ) of a maximum of 6 seconds, so that a temperature input value with this time constant is reached to 90%.

[0030] This advantageously allows an ignition event in or on the fuel cell and / or the fuel cell system to be detected more reliably.

[0031] In one embodiment, the fuel cell system comprises means configured to verify the plausibility of the detected ignition event, in particular by checking a determined similarity, in particular for its plausibility, and furthermore, in particular, by checking a temperature value detected by the at least one temperature sensor, in particular a detected temperature profile, for its accuracy. In one embodiment, the plausibility check comprises a check of the function of the temperature sensor, in particular during the detection of the at least one temperature profile.

[0032] In this way, the accuracy of the recording and / or detection or determination can be checked or is checked by the plausibility clarification.

[0033] In one embodiment, the enclosure has a predetermined breaking point and / or an overpressure relief device.

[0034] In one embodiment, this advantageously protects the enclosure from overpressure, which can occur particularly in the event of an ignition event. This can further increase the safety of the system.

[0035] The term "probability," as used herein, is to be understood in particular as the possibility or chance that an event will occur or has occurred. A probability is usually expressed as a number between 0 and 1, where 0 means that the event will not occur or has occurred, and 1 means that the event will occur or has occurred with certainty. The probability can also be expressed as a percentage or as a ratio. For example, a probability of 0.5 corresponds to a probability of 50% or a ratio of 1:1. The probability depends in an embodiment on various factors, in particular the accuracy of the available information.In one embodiment, the probability can be calculated by statistical methods and models based on predetermined data, in particular a predetermined temperature profile and, in one embodiment, in particular probability theory.

[0036] The term "plausibility clarification", as used herein, is to be understood in particular as the process of checking or assessing the plausibility or credibility of information, data or statements, here in one embodiment of checking or assessing the plausibility or credibility of the detection of the ignition event. The goal of plausibility clarification in one embodiment is to ensure that the available information is correct and / or logical and, in particular, corresponds to expectations. In one embodiment, different methods can be used to check plausibility, such as in particular by comparing data, in particular the data recorded by the temperature sensor, with previous results, checking internal consistency or applying statistical methods.In one embodiment, a successful plausibility check can advantageously help identify and correct errors or incorrect information and create a trustworthy basis for detecting an ignition event. In one embodiment, this can advantageously detect whether a temperature sensor is damaged or needs to be replaced and / or whether it is providing or detecting incorrect temperature values.

[0037] The terms "comprises," "includes," "includes," "has," "has," "with," or any other variation thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a method or apparatus that includes or has a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or that are inherent in such a method or apparatus.

[0038] Furthermore, unless expressly stated to the contrary, "or" refers to an inclusive "or" and not an exclusive "or". For example, a condition A or B is satisfied by one of the following conditions: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0039] The terms "a" or "an" as used herein are defined as "one or more." The terms "another" and "another," and any other variations thereof, are defined as "at least one other."

[0040] The term “plurality” as used herein shall mean “two or more”.

[0041] The term “designed” or “configured” to perform a specific function (and respective variations thereof), as used here where appropriate, is to be understood that a relevant device or component thereof is already in a configuration or setting in which it can perform the function or is at least adjustable – i.e. configurable – so that it can perform the function after being set accordingly. The configuration can be carried out, for example, by appropriately setting parameters of a process sequence or of switches or the like for activating or deactivating functionalities or settings. In particular, the device can have a plurality of predetermined configurations or operating modes, so that the configuration can be carried out by selecting one of these configurations or operating modes.

[0042] A system and / or means within the meaning of the present invention can be designed in hardware and / or software, in particular at least one, in particular digital, processing unit, in particular a microprocessor unit (CPU), graphics card (GPU) or the like, preferably connected to a memory and / or bus system for data or signals, and / or one or more programs or program modules. The processing unit can be designed to execute instructions implemented as a program stored in a memory system, to detect input signals from a data bus, and / or to output signals to a data bus. A memory system can have one or more, in particular different, storage media, in particular optical, magnetic, solid-state, and / or other non-volatile media. The program can be designed in such a way that it embodies the methods described here oris capable of carrying out such a method, so that the processing unit can carry out the steps of such methods and thus in particular operate or monitor the fuel cell system.

[0043] In one embodiment, a computer program or computer program product is provided, wherein the computer program or computer program product, in one embodiment stored on a computer-readable and / or non-volatile storage medium, contains instructions which, when executed by one or more computers or a fuel cell system described herein, cause the computer(s) or the fuel cell system to perform a method described herein.

[0044] In one embodiment, a computer program product can comprise, in particular be, a storage medium, in particular a computer-readable and / or non-volatile one, for storing a program or instructions or with a program or instructions stored thereon. In one embodiment, execution of this program or these instructions by a system or a controller, in particular a computer or an arrangement of multiple computers, causes the system or the controller, in particular the computer(s), to carry out a method described here or one or more of its steps, or the program or the instructions are configured to do so.

[0045] In one embodiment, one or more, in particular all, steps of the method are carried out completely or partially automatically, in particular by the controller or its means.

[0046] In one embodiment, the computer program can be stored on a non-volatile data carrier. This is preferably a data carrier in the form of an optical data carrier or a flash memory module. This can be advantageous if the computer program as such is to be handled independently of a processor platform on which the one or more programs are to be executed. In another implementation, the computer program can be present as a file on a data processing unit, in particular on a server, and can be downloaded via a data connection, for example the Internet or a dedicated data connection, such as a proprietary or local network. In addition, the computer program can have a plurality of interacting individual program modules. The modules can in particular be configured or at least be usable in such a way that they can be used in the sense of distributed computing (DC).“Distributed computing” is carried out on different devices (computers or processor units) that are geographically separated from each other and connected via a data network.

[0047] The fuel cell system can accordingly have a program memory in which the computer program is stored. Alternatively, the fuel cell system can also be configured to access an external computer program, for example, available on one or more servers or other data processing units, via a communication connection, in particular to exchange data with it that is used during the execution of the method or computer program or that represents outputs of the computer program.

[0048] Further advantages, features and possible applications of the present invention will become apparent from the following detailed description in conjunction with the figures. Fig. 1: schematic of a fuel cell system; Fig. 2: schematically shows a recorded temperature profile; and Fig. 3: a flow chart illustrating a preferred embodiment of the method according to the invention.

[0049] Elements depicted in the figures are not necessarily drawn to scale. Rather, the various elements depicted in the figures are depicted in such a way that their function and general purpose are understandable to those skilled in the art. Connections and couplings between functional units and elements depicted in the figures may, unless expressly stated otherwise, also be implemented as indirect connections or couplings. Functional units may, in particular, be implemented as hardware, software, or a combination of hardware and software.

[0050] Fig. 1 schematically shows a fuel cell system 1 with means 12 for detecting a temperature profile, which in one embodiment is at least one temperature sensor arranged in the fuel cell system 1, in particular in or on a fuel cell 11 of the fuel cell system 1. Furthermore, Fig. 1 schematically shows means 13 for detecting an ignition event in the fuel cell system 1, in particular in or on the fuel cell 11. If an ignition event occurs in the fuel cell system 1, in particular in or on the fuel cell 11, the temperature in the fuel cell system 1, in particular in the fuel cell 11, rises, in particular within a certain period of time. This temperature rise can be detected using the means 12 for detecting the temperature profile, in particular using the temperature sensor. If the temperature profile corresponds, at least substantially, to a predetermined temperature profile for an ignition event, the means 13 for detecting an ignition event determines that an ignition event has occurred, in particular a probability that is representative that an ignition event has occurred.According to an embodiment described herein, countermeasures can be taken to prevent a (further) ignition event.

[0051] Fig. 2 schematically shows a first temperature profile 5 and a second temperature profile 6, each of which was recorded using a temperature sensor 12 in the fuel cell system 1. Time is schematically plotted on the horizontal axis, and a recorded temperature is schematically plotted on the vertical axis. Dashed lines schematically show a time period Δt and a temperature difference ΔT of 25 Kelvin. The temperature profiles 5, 6 have a temperature profile in the time segment that has a temperature difference that is greater than a predetermined ΔT. Therefore, in the example shown, an ignition event is detected for both temperature profile 5 and temperature profile 6, in particular that an ignition event has occurred in or on the fuel cell 11 or the fuel cell system 1 and, in one embodiment, countermeasures are (must be) taken.In one embodiment, the temperature profiles can be or have been recorded at various locations in the fuel cell system 1 and / or in or on the fuel cell. For a temperature profile that is below the temperature difference, which is predetermined in one embodiment and further determined in particular from at least one measurement of an (artificially) generated ignition event, in particular on a test bench, in one embodiment, no ignition event is detected (automatically), in particular a similarity and / or probability is determined that is representative of the fuel cell system, in particular operated without an ignition event.

[0052] Fig.3 schematically shows a flow diagram to illustrate a method described herein. S10 represents the recording of at least one temperature profile in a fuel cell. The detection S20 of an ignition event in the fuel cell based on the recorded temperature profile is shown as a subsequent step of the method. Furthermore, operation of the fuel cell system based on the detection of the ignition event is shown schematically with dashed lines. If no ignition event is detected, in particular if a similarity of the temperature profile or a probability is determined that does not suggest the occurrence of an ignition event, the fuel cell system is (continued to) be operated S30. However, if an ignition event is detected, in particular if a similarity and / or a probability is determined that, in one embodiment, is equal to or greater than a predetermined similarity and / or probability, which means oris representative of the fact that an ignition event has occurred, the fuel cell system, in particular the part of the fuel cell system 1 in which the fuel cell 11 is located for which an ignition event was detected, is no longer operated S30, in particular countermeasures are taken to prevent a further ignition event.

[0053] While at least one exemplary embodiment has been described above, it should be appreciated that a wide variety of variations exist. It should also be understood that the described exemplary embodiments are merely non-limiting examples and are not intended to limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing description will provide one skilled in the art with guidance for implementing at least one exemplary embodiment, it being understood that various changes in the operation and arrangement of the elements described in an exemplary embodiment may be made without departing from the subject matter as defined in the appended claims, as well as their legal equivalents.

Claims

[1] Method for monitoring a fuel cell system (1), in particular for ignition detection in the fuel cell system (1), comprising: - Recording (S10) at least one temperature profile (5, 6) in a fuel cell system (1); - Detecting (S20) an ignition event in the fuel cell system (1) based on the detected temperature profile (5, 6), wherein the detection (S20) of the ignition event includes determining a similarity such that a temperature rise profile and a temperature fall profile following the temperature rise profile of the detected temperature profile (5, 6) correspond to a predetermined temperature rise profile and a predetermined temperature fall profile of an ignition event. [2] Method according to claim 1, characterized by, that the method includes initiating countermeasures, in particular to safeguard the fuel cell system (1), based on the detection (S20) of the ignition event, in particular interrupting the hydrogen supply to the fuel cell system (1), switching off the fuel cell system (1), and / or discharging the fuel cell system (1) which includes the fuel cell (11), if there is a residual electrical charge. [3] Method according to the preceding claim, characterized by , that the initiation of the countermeasure is limited to the part of the fuel cell system (1) in which an ignition event has been detected. [4] Method according to any one of the preceding claims, characterized by , that the temperature profile (5, 6) shows at least a temperature increase of 10 Kelvin, in particular in a time period of at most 25 seconds. [5] Fuel cell system (1), comprising: at least one fuel cell (11) for generating electricity using fuel gas and oxidizing gas and a housing for receiving the at least one fuel cell (11); at least one temperature sensor (12); wherein the fuel cell system (1) is configured to carry out a method according to one of the preceding claims and comprises: means for detecting (S10) a temperature profile in the fuel cell system (1); and means (13) for detecting (S20) an ignition event, based on the detected temperature profile. [6] Fuel cell system (1) according to the preceding claim, characterized by, that the means for recording (S10) the temperature profile (5, 6) in the fuel cell system (1) is a temperature sensor (12), in particular a measuring tip, which has a response time of at most 6 seconds, in particular a temperature sensor (12) which is designed for temperatures of at least 250°C and / or at most 450°C. [7] Fuel cell system (1) according to one of the preceding claims 5 or 6, characterized by , that the fuel cell system (1) has means which are provided for a plausibility check of the detected ignition event. [8] Computer program or computer program product, wherein the computer program or computer program product contains instructions, in particular stored on a computer-readable and / or non-volatile storage medium, which, when executed by one or more computers or a fuel cell system (1) according to any one of claims 5 to 7, cause the computer(s) or the fuel cell system (1) to carry out a method according to any one of claims 1 to 4.

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