Identification method for identifying state of fuel cell system
By running the flush valve when the main discharge valve is opened in the fuel cell system in a rhythmic manner, changing the system operating parameters and using the sensor signal response to empty state recognition, the problem of difficulty in identifying the empty state of multiple water separators in the prior art is solved, and the efficient operation of the fuel cell system is achieved.
Patent Information
- Application Number
- CN202380065793.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-14
- Filing Date
- 2023-09-13
- Publication Date
- 2025-04-22
AI Technical Summary
The prior art is difficult to accurately identify the empty state in multiple water separators in fuel cell systems, resulting in fuel waste and reduced system efficiency.
By running the flush valve when the main discharge valve is opened in a rhythmic manner, the operating parameters of the fuel cell system are changed, and the empty state recognition is performed using the corresponding sensor signal response, ensuring that the empty state of the second water separator is reliably identified.
Accurate identification of the empty state of the second water separator in the fuel cell system is achieved, reducing fuel waste and improving the system's use efficiency.
Smart Images
Figure CN119866556A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a recognition method for recognizing the state of a fuel cell system and a fuel cell system according to the appended claims. Background Art
[0002] Fuel cells convert hydrogen and oxygen into water, producing electricity which can be supplied to consumers such as electric motors in order to drive them.
[0003] In order to separate the liquid water from the gaseous part of the anode exhaust gas, a special water separator is used. In addition to the separation function, the water separator also has the task of storing the separated water. If the storage is full, the water is discharged by opening the so-called "drain valve" or drain valve.
[0004] According to the prior art, the fuel cell system is supplied with fresh hydrogen by means of a hydrogen metering valve which can be implemented as a proportional valve. A control strategy is provided, with which the gas pressure inside the anode path is regulated to a defined set pressure by means of a pressure sensor at a defined position depending on the system operating point. The reasons for the additional supply of fresh hydrogen may be: a) consumption of H due to electrochemical conversion; 2 b) additional losses of gas molecules from the anode space due to, for example, opening the discharge valve too long (if the gas is discharged after the water has been completely emptied) and due to opening the so-called "purge valve" or flushing valve. Unnecessary activation of the flushing valve causes a loss of fuel and may lead to an additional energy requirement for providing dilution air.
[0005] If the fuel cell system has two water reservoirs (for example the main water separator and the gas delivery unit), both function as drain valves and one additionally assumes the task of a flushing valve.
[0006] Depending on the system, the hydrogen concentration sensor is located in the exhaust gas path of the cathode air downstream of the introduction point of the discharge valve and the purge valve. If anode gas reaches the exhaust gas path of the cathode air, this is detected by the hydrogen concentration sensor. From the prior art, methods for detecting the full state of the water reservoir are known. This method detects a quasi-overflow of the water separator, but does not identify which of the two water reservoirs is involved.
[0007] Typically, the water reservoir of the gas delivery unit is smaller than the water reservoir of the main water separator, since the gas delivery unit separates much less water than the main water separator and the flushing valve is integrated into the gas delivery unit. Furthermore, typically due to the frequent activation of the flushing valve, the water reservoir of the gas delivery unit is empty more often than the water reservoir of the main water separator and correspondingly overflows less frequently or is full less frequently. Summary of the invention
[0008] Within the scope of the present invention, a recognition method for recognizing the state of a fuel cell system and a fuel cell system are described. Further features and details of the invention are derived from the corresponding dependent claims, the description and the drawings. Here, of course, the features and details described in connection with the recognition method according to the invention also apply in connection with the fuel cell system according to the invention and vice versa, so that in the disclosure of the individual inventive aspects, reference is always made to one another or can be made to one another.
[0009] The invention presented serves to operate a fuel cell system in a fuel-efficient manner. In particular, the invention presented serves to detect an empty state of a water separator in a fuel cell system having a plurality of water separators.
[0010] Therefore, according to the first aspect of the invention described, a method for identifying the state of a fuel cell system is described, wherein the fuel cell system includes a first water separator and a second water separator, the first water separator being the main water separator of the fuel cell system and including a main discharge valve for draining water from the second water separator, the second water separator being integrated into a gas delivery unit of the fuel cell system and including a flushing valve for flushing the fuel cell system, wherein the first water separator has a larger storage volume than the second water separator.
[0011] The identification method includes: opening a main discharge valve; operating the flushing valve in a clocked operation mode when the main discharge valve is open; performing empty state identification; and, if an empty state is repeatedly identified during the clocked operation with the aid of the empty state identification, outputting the following message: according to the message, the water reservoir of the second water separator is empty.
[0012] In the context of the invention presented, “empty state detection” is to be understood as a process in which it is determined whether the water separator is empty, ie whether there is no water in the water reservoir of the water separator.
[0013] In the context of the invention described, the clocked operation of a valve can be understood as the following operation of a valve: in the operation, the valve is opened and closed many times in a short time. Here, the valve is opened and closed again at a frequency, which can be between 1 Hz and 25 Hz.
[0014] The detection method presented is based on the clocked operation of the flushing valve of the fuel cell system when the main discharge valve of the fuel cell system is open. The clocked operation repeatedly changes operating parameters of the fuel cell system that can be evaluated by the empty state detection, such as the pressure acting in the cathode subsystem, the hydrogen concentration in the exhaust gas path of the cathode air acting downstream of the introduction point of the discharge valve and the flushing valve, or the current consumption caused by the gas supply unit of the fuel cell system in the case of an empty water reservoir of the gas supply unit, so that the corresponding signal response of the corresponding sensor for detecting the pressure, the hydrogen concentration or the consumed current changes according to the clocked operation and the "empty" state can be reliably assigned to the second water separator.
[0015] Since according to the invention only the flushing valve of the second water separator is operated in clocked mode, a corresponding clocked signal response can be assigned to the second water separator so that the state of the second water separator can be detected independently of the state of the first water separator.
[0016] It can be provided that if an empty state is repeatedly detected by means of the empty state detection during the clocked operation, the flushing valve is closed and the main outlet valve remains open until a further empty state is detected.
[0017] By closing the flushing valve while the main discharge valve remains open, the discharge of hydrogen from the flushing valve can be interrupted and fuel can be saved accordingly.
[0018] By opening the main drain valve until a further empty state is detected (ie the empty state is detected after the flush valve has been closed), the first water separator can be emptied further, since it is usually fuller than the second water separator or more water must be discharged.
[0019] Furthermore, it can be provided that the message includes that if an empty state is detected after closing the flush valve, in particular directly after closing the flush valve, the water reservoir of the first water separator is also empty and the main drain valve is closed.
[0020] By means of the empty state detection which is carried out after the flushing valve has been closed and the main drain valve is still open, the state of the first water separator or the main water separator can be reliably detected and the main drain valve can be adjusted accordingly.
[0021] If the empty state is detected directly after the flush valve has been closed, it can be assumed that the first water separator and the second water separator are emptied simultaneously.
[0022] Furthermore, it can be provided that the detection method comprises outputting a message according to which the water reservoir of the first water separator is empty if an empty state is detected continuously during the clocked operation by means of the empty state detection.
[0023] If the empty state is detected continuously during the clocked operation, the cause of the corresponding signal change leading to the detection of the "empty" state is not the second water separator, because the signal change does not occur clockedly, but its cause must be the state of the first water separator. Accordingly, it can be assumed that the first water separator is empty and the second water separator still contains water.
[0024] Furthermore, it can be provided that if an empty state is detected continuously during the clocked operation by means of the empty state detection, the main outlet valve is closed and the flushing valve is permanently opened until a further empty state is detected.
[0025] Because, if the empty state is continuously detected during the clocked operation by means of the empty state detection, it can be assumed that the first water separator is empty and the main drain valve can be closed. Since it can also be assumed that the second water separator is still filled with water, the flushing valve must remain open.
[0026] Furthermore, it can be provided that the empty state recognition comprises: determining the pressure acting in the anode subsystem of the fuel cell system by means of a pressure sensor; and reporting the identified empty state if the measured value determined by the pressure sensor drops below a predetermined pressure threshold within a predetermined period of time after the flushing valve and / or the main drain valve is opened.
[0027] Since the opening of the purge valve or the main exhaust valve leads to a pressure change in the anode subsystem of the respective fuel cell system, the evaluation of the pressure curve has proven to be a reliable measure for empty state detection.
[0028] Furthermore, it may be provided that the empty state recognition includes: determining the hydrogen concentration in the fuel cell system by means of a hydrogen concentration sensor; and, if the determined hydrogen concentration is above a predetermined hydrogen concentration threshold value within a predetermined time period after opening the purge valve and / or the main drain valve, reporting the identified empty state.
[0029] Since the opening of the purge valve or main discharge valve leads to an increase in the hydrogen concentration in the exhaust gas path of the cathode air downstream of the introduction point of the discharge valve and purge valve of the respective fuel cell system, evaluation of the hydrogen concentration profile has proven to be a reliable measure for empty state detection.
[0030] Furthermore, it can be provided that the empty state recognition includes: determining the current consumed by the hydrogen metering valve of the fuel cell system; and reporting the recognized empty state if the determined current is above a predetermined current threshold value within a predetermined time period after opening the purge valve and / or the main drain valve.
[0031] Since the opening of the purge valve or the main discharge valve leads to a compensation supply of hydrogen via the hydrogen metering valve of the corresponding fuel cell system, the evaluation of the current consumed by the hydrogen metering valve as a measure for the activity of the hydrogen metering valve has proven to be a reliable measure for empty state detection.
[0032] According to a second aspect, the invention relates to a fuel cell system. The described fuel cell system comprises a first water separator, a second water separator and a computing unit, wherein the first water separator is a main water separator of the fuel cell system and comprises a main discharge valve for conducting water out of the fuel cell system, wherein the second water separator is integrated into a gas delivery unit of the fuel cell system and comprises a flushing valve for flushing the fuel cell system, wherein the first water separator has a larger storage volume than the second water separator. The computing unit is configured to carry out a possible configuration of the described identification method.
[0033] In the context of the invention described, a computing unit may be understood as a computer, a processor, a controller or any other programmable switching circuit.
[0034] It can be set that the computing unit is configured to: output an opening instruction for opening the main discharge valve; output an activation instruction for activating the operation of the flushing valve in the clocked mode when the main discharge valve is open; output an activation instruction for activating the empty state recognition when the clocked mode is activated; and, if the empty state is identified by means of the empty state recognition and through the empty state recognition when the clocked mode is activated, output the following message, according to which the water reservoir of the second water separator is empty. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Further advantages, features and details of the invention are apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the accompanying drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.
[0036] It shows:
[0037] Figure 1 A possible configuration of the described identification method is
[0038] Figure 2 A possible embodiment of the described fuel cell system. DETAILED DESCRIPTION
[0039] exist Figure 11 shows an identification method 100. The identification method 100 is used to identify the state of a fuel cell system, wherein the fuel cell system comprises a first water separator and a second water separator, the first water separator being a main water separator of the fuel cell system and comprising a main discharge valve for conducting water out of the second water separator, the second water separator being integrated into a gas delivery unit of the fuel cell system and comprising a flushing valve for flushing the fuel cell system, wherein the first water separator has a larger storage volume than the second water separator.
[0040] The identification method 100 comprises an opening step 101 , in which the main drain valve is opened, and an operating step 103 , in which the flushing valve is operated in a clocked operation while the main drain valve is open.
[0041] In addition, the identification method 100 includes an implementation step 105 and an output step 107, in which an empty state recognition is implemented and in which, when an empty state is repeatedly recognized during clocked operation with the help of empty state recognition, the following message is output: according to the message, the water tank of the second water separator is empty.
[0042] exist Figure 2 2 shows a fuel cell system 200 . The fuel cell system 200 includes a first water separator 201 , a second water separator 203 and a computing unit 205 .
[0043] The first water separator 201 is a main water separator of the fuel cell system 200 and comprises a main drain valve 207 for draining water out of the first water separator 201 .
[0044] The second water separator 203 is integrated into a gas delivery unit 209 of the fuel cell system 200 and comprises a flushing valve 211 for flushing the fuel cell system 200 .
[0045] The first water separator 201 comprises a larger storage volume than the second water separator 203 .
[0046] The computing unit 205 is configured to carry out the identification method 100 .
Claims
1. A method (100) for identifying a state of a fuel cell system (200), the fuel cell system comprising a first water separator (201) and a second water separator (203), in, The first water separator (201) is a main water separator of the fuel cell system (200) and comprises a main discharge valve (207) for discharging water from the first water separator (201), wherein the second water separator (205) is integrated into a gas delivery unit (209) of the fuel cell system (200) and comprises a flushing valve (211) for flushing the fuel cell system (200), and wherein the first water separator (201) has a larger storage capacity than the second water separator (203), The identification method (100) comprises: - opening (101) the main discharge valve (207), - operating (103) the flushing valve (211) in a clocked operation mode while the main discharge valve (207) is open, - implement (105) empty state recognition, If an empty state is repeatedly detected during the clocked operation by means of the empty state detection, a message is output (107) according to which the water reservoir of the second water separator (203) is empty.
2. The identification method (100) according to claim 1, It is characterized in that If an empty state is repeatedly detected during the clocked operation using the empty state detection, the flushing valve (211) is closed and the main drain valve (207) remains open until a further empty state is detected.
3. The identification method (100) according to claim 2, It is characterized in that The message includes that if an empty state is identified after closing the flush valve (211), the water reservoir of the first water separator (201) is also empty and the main drain valve (207) is closed.
4. The identification method (100) according to any one of the preceding claims, It is characterized in that The identification method (100) further includes: If an empty state is detected continuously during the clocked operation by means of the empty state detection, a message is outputted: according to the message, the water reservoir of the first water separator (201) is empty.
5. The identification process (100) according to claim 4, It is characterized in that If an empty state is detected continuously during the clocked operation by means of the empty state detection, the main outlet valve (207) is closed and the flushing valve (211) is permanently opened until a further empty state is detected.
6. The identification method (100) according to any one of the preceding claims, It is characterized in that The empty state identification includes: - determining the pressure acting in the anode subsystem of the fuel cell system (200) by means of a pressure sensor, If, within a predefined period of time after the flushing valve and / or the main drain valve (207) has been opened, the measured value ascertained by the pressure sensor falls below a predefined pressure threshold value, a detected empty state is reported.
7. The identification method (100) according to any one of claims 1 to 5, It is characterized in that The empty state identification includes: - determining the hydrogen concentration in the fuel cell system (200) by means of a hydrogen concentration sensor, If the ascertained hydrogen concentration within a predefined period of time after opening the flushing valve (211) and / or the main drain valve (207) is above a predefined hydrogen concentration threshold value, a detected empty state is reported.
8. The identification method (100) according to any one of claims 1 to 5, It is characterized in that The empty state identification includes: - determining the current consumed by the hydrogen metering valve of the fuel cell system (200), If the current ascertained within a predefined period of time after the opening of the flushing valve (211) and / or the main drain valve (207) lies above a predefined current threshold value, a detected empty state is reported.
9. A fuel cell system (200), in, The fuel cell system (200) comprises: - a first water separator (201), - a second water separator (203), - a calculation unit (205), The first water separator (201) is a main water separator of the fuel cell system (200) and comprises a main discharge valve for discharging water from the fuel cell system (200). wherein the second water separator is integrated into a gas delivery unit (209) of the fuel cell system (200) and comprises a flushing valve (211) for flushing the fuel cell system (200), and, wherein the first water separator (201) has a larger storage capacity than the second water separator (203), The computing unit (205) is configured to execute the identification method (100) according to any one of claims 1 to 8.
10. The fuel cell system (200) according to claim 9, It is characterized in that The computing unit (205) is configured to: - outputting an opening command for opening the main discharge valve (207), - outputting an activation command, which activates the operation of the flushing valve (211) in a clocked mode and simultaneously opens the main drain valve (207), - outputting an activation command when the clocked mode is activated in order to activate the empty state detection, If an empty state is detected by means of the empty state detection when the clocked mode is activated, a message is outputted according to which the water reservoir of the second water separator (203) is empty.