Method and system for detecting state of air back pressure valve of fuel cell system

Abstract

A fuel cell system air back pressure valve state detection method and system belong to the fuel cell system field, and comprise: controlling an air back pressure valve opening according to a calibration top dead center, determining whether an actual opening is less than the calibration top dead center, if yes, updating the value of the calibration top dead center to the actual opening, and if not, updating the value of the calibration top dead center to the actual opening; after the value of the calibrated top dead center is updated to be the sum of the actual upper opening and the preset value, a first opening instruction is generated again; the opening degree of the air back pressure valve is controlled according to the calibrated bottom dead center, whether the actual lower opening degree is larger than the calibrated bottom dead center or not is judged, if yes, the value of the calibrated bottom dead center is updated to be the actual lower opening degree, and if not, after the value of the calibrated bottom dead center is updated to be the difference between the actual lower opening degree and preset data, a second opening degree instruction is generated again; and according to the updated calibrated bottom dead center, performing sealing judgment on the air back pressure valve to obtain a sealing result. Accurate upper and lower dead centers of the air back pressure valve can be obtained, so that the opening degree adjusting precision and the sealing performance are improved.

Description

Technical Field

[0001] The present application relates to the field of fuel cell systems, and in particular to a method and system for detecting the status of an air back-pressure valve in a fuel cell system. Background Art

[0002] The fuel cell system includes a stack, an air system, a hydrogen system, a water / heat management system and a corresponding control system, wherein Figure 1 The air system is mainly composed of an air filter, an air flow meter, an air compressor, an intercooler, and an air back pressure valve. The main function of the air system is to provide clean air with appropriate flow, temperature, and pressure for the fuel cell stack, making the fuel cell system run more stably.

[0003] The target air back-pressure valve opening required for each operating point of different fuel cell systems can be determined through testing and calibration, and then preset in the control software (e.g., stored in EEPROM). This is the pre-control portion, and its content cannot be changed after the system product is finalized. Specifically, the maximum target opening of the air back-pressure valve under each operating condition cannot exceed the calibrated top dead center, and the minimum cannot exceed the calibrated bottom dead center. Therefore, the accuracy of the calibrated top dead center and calibrated bottom dead center values ​​directly affects the formulation of the air back-pressure valve opening control strategy under each operating condition.

[0004] In the prior art, the calibrated top dead center and calibrated bottom dead center are set before the target opening for each operating condition and are also preset in the aforementioned control software. Once the system product is finalized, they cannot be changed. However, after the air backpressure valve has been in operation for a long time, the actual achievable top dead center and bottom dead center positions may change. The pre-set calibrated top dead center and calibrated bottom dead center may no longer reflect the air backpressure valve's true maximum and minimum opening positions. For example, if the air backpressure valve has been in operation for a long time and the actual achievable maximum opening decreases, meaning the actual dead center is less than the calibrated setting, if the air backpressure valve is still issued an opening command based on the calibrated top dead center, the feedback opening will be less than the commanded opening, causing the fault analysis software to mistakenly determine that the air backpressure valve is stuck, generating a false alarm. For another example, if the actual achievable minimum opening decreases after the air backpressure valve has been in operation for a long time, the fault analysis software may use the calibrated bottom dead center to determine the air backpressure valve's sealing performance, which may affect the accuracy of the judgment result. Summary of the Invention

[0005] The present application provides a method and system for detecting the state of an air back-pressure valve in a fuel cell system, which can solve various technical problems in the prior art caused by the uncertainty of the maximum and minimum openings of the air back-pressure valve.

[0006] In a first aspect, an embodiment of the present application provides a method for detecting the state of an air back-pressure valve of a fuel cell system, characterized in that the method for detecting the state of an air back-pressure valve of a fuel cell system comprises:

[0007] generating a first opening instruction based on the calibrated top dead center, controlling the opening of the air back pressure valve according to the first opening instruction, obtaining an actual opening of the air back pressure valve, and determining whether the actual opening is less than the calibrated top dead center. If so, updating the value of the calibrated top dead center to the actual opening; if not, updating the value of the calibrated top dead center to the sum of the actual opening and a preset value, and then generating the first opening instruction again;

[0008] generating a second opening instruction based on the calibrated bottom dead center, controlling the opening of the air back pressure valve according to the second opening instruction, obtaining the actual lower opening of the air back pressure valve, and determining whether the actual lower opening is greater than the calibrated bottom dead center. If so, updating the value of the calibrated bottom dead center to the actual lower opening; if not, updating the value of the calibrated bottom dead center to the difference between the actual lower opening and the preset data, and then generating the second opening instruction again;

[0009] The air back pressure valve is subjected to a sealing judgment based on the updated calibration bottom dead center to obtain a sealing result.

[0010] In combination with the first aspect, in one embodiment, the method further includes:

[0011] During the startup process of the fuel cell system, a back pressure valve top dead point self-check is set, and the first opening instruction is generated based on the calibrated top dead point to complete the back pressure valve top dead point judgment, and the obtained value is saved in the controller as the new calibrated top dead point. The back pressure valve top dead point self-check judgment action is repeated during each startup process.

[0012] In combination with the first aspect, in one embodiment, the method further includes:

[0013] During the shutdown process of the fuel cell system, a back pressure valve bottom dead point self-check is set, and the second opening instruction is generated based on the calibrated bottom dead point to complete the back pressure valve bottom dead point judgment, and the obtained value is saved in the controller as the new bottom dead point. The back pressure valve bottom dead point self-check judgment action is repeated during each shutdown process.

[0014] In combination with the first aspect, in one embodiment, the preset value adopts a minimum control precision value of the valve; the minimum control precision value of the valve is a positive number less than 1;

[0015] The minimum control accuracy value of the valve is calculated based on the control accuracy of the controller and the response accuracy of the components.

[0016] In combination with the first aspect, in one embodiment, judging the sealing performance of the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing performance result specifically includes the following steps:

[0017] After the hydrogen pressure of the fuel cell stack is increased to the first pressure value, the air shut-off valve is closed;

[0018] generating a third opening instruction according to the updated calibrated bottom dead center to adjust the opening of the air back pressure valve to the minimum;

[0019] After the hydrogen pressure of the fuel cell stack is increased to the second pressure value, the timing is started until the hydrogen pressure of the fuel cell stack is increased to the third pressure value, and a time value is obtained to determine whether the time value is less than the preset time threshold. If so, it is determined that the air back pressure valve is sealed normally. If not, it is determined that the air back pressure valve is sealed abnormally.

[0020] In a second aspect, an embodiment of the present application provides a fuel cell system air back pressure valve state detection system, the fuel cell system air back pressure valve state detection system comprising:

[0021] a top dead center calibration module, configured to generate a first opening instruction based on the calibrated top dead center, control the opening of the air back pressure valve according to the first opening instruction, obtain the actual opening of the air back pressure valve, determine whether the actual opening is less than the calibrated top dead center, and if so, update the value of the calibrated top dead center to the actual opening; if not, update the value of the calibrated top dead center to the sum of the actual opening and a preset value, and then generate the first opening instruction again;

[0022] a bottom dead point calibration module, which is used to generate a second opening instruction based on the calibrated bottom dead point, control the opening of the air back pressure valve according to the second opening instruction, and obtain the actual lower opening of the air back pressure valve, determine whether the actual lower opening is greater than the calibrated bottom dead point, and if so, update the value of the calibrated bottom dead point to the actual lower opening; if not, update the value of the calibrated bottom dead point to the difference between the actual lower opening and the preset data, and then generate the second opening instruction again;

[0023] The sealing detection module is used to judge the sealing of the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing result.

[0024] In combination with the second aspect, in one embodiment, the top dead point calibration module sets a back pressure valve top dead point self-check during the startup of the fuel cell system, generates the first opening instruction based on the calibrated top dead point to complete the back pressure valve top dead point judgment, and saves the obtained value as the new calibrated top dead point in the controller, and repeats the back pressure valve top dead point self-check judgment action during each startup process.

[0025] In combination with the second aspect, in one embodiment, the bottom dead point calibration module sets a back pressure valve bottom dead point self-check during the shutdown process of the fuel cell system, generates the second opening instruction based on the calibrated bottom dead point to complete the back pressure valve bottom dead point judgment, and saves the obtained value as the new bottom dead point in the controller, and repeats the back pressure valve bottom dead point self-check judgment action during each shutdown process.

[0026] In conjunction with the second aspect, in one embodiment, the preset value adopts a minimum control precision value of the valve; the minimum control precision value of the valve is a positive number less than 1;

[0027] The minimum control accuracy value of the valve is calculated based on the control accuracy of the controller and the response accuracy of the components.

[0028] In conjunction with the second aspect, in one embodiment, when the sealing detection module performs a sealing judgment on the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing result, the stack hydrogen pressure is increased to a first pressure value and then the air shut-off valve is closed;

[0029] generating a third opening instruction according to the updated calibrated bottom dead center to adjust the opening of the air back pressure valve to the minimum;

[0030] After the hydrogen pressure of the fuel cell stack is increased to the second pressure value, the timing is started until the hydrogen pressure of the fuel cell stack is increased to the third pressure value, and a time value is obtained to determine whether the time value is less than the preset time threshold. If so, it is determined that the air back pressure valve is sealed normally. If not, it is determined that the air back pressure valve is sealed abnormally.

[0031] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0032] The calibration top dead center is updated by obtaining the actual maximum opening of the air back pressure valve, and the calibration bottom dead center is updated by obtaining the actual minimum opening of the air back pressure valve. The updated calibration top dead center and calibration bottom dead center can more accurately reflect the opening limit of the air back pressure valve. Based on the more accurate calibration top dead center and calibration bottom dead center, a more reasonable air back pressure valve opening adjustment strategy can be specified, and the sealing of the air back pressure valve can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the architecture of a fuel cell system in the prior art;

[0034] Figure 2 This is a flow chart of an embodiment of a method for detecting the state of an air back pressure valve of a fuel cell system of the present application;

[0035] Figure 3 This is a flow chart of an embodiment of a method for detecting the state of an air back pressure valve of a fuel cell system of the present application;

[0036] Figure 4 This is a functional module diagram of an embodiment of the fuel cell system air back pressure valve status detection system of the present application. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] First, some technical terms in this application are explained to facilitate those skilled in the art to understand this application.

[0039] Air Shut-off Valve: Used to quickly shut off or restart the air supply (such as cathode air intake), isolating the air path to ensure safety during system startup, shutdown, or malfunction. For example, during shutdown, this valve prevents air from entering the fuel cell stack and causing an unintended reaction with residual hydrogen. It also provides an emergency air shut-off in the event of a malfunction. It is typically installed upstream of the air intake duct (such as at the compressor outlet or after the intercooler).

[0040] Air back-pressure valve: This valve controls the cathode exhaust pressure by adjusting the valve opening to maintain the optimal operating pressure inside the stack (e.g., 0.2-0.3 MPa). Installed at the end of the air exhaust duct (cathode outlet of the stack).

[0041] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0042] In a first aspect, an embodiment of the present application provides a method for detecting the state of an air back-pressure valve of a fuel cell system.

[0043] In one embodiment, referring to Figure 2 , Figure 2 This is a flow chart of an embodiment of a method for detecting the state of an air back pressure valve in a fuel cell system of the present application. Figure 2 As shown, the fuel cell system air back pressure valve status detection method includes:

[0044] Step S1: Generate a first opening instruction based on the calibrated top dead center, control the opening of the air back pressure valve according to the first opening instruction, obtain the actual opening of the air back pressure valve, and determine whether the actual opening is less than the calibrated top dead center. If so, update the value of the calibrated top dead center to the actual opening. If not, update the value of the calibrated top dead center to the sum of the actual opening and the preset value, and then generate the first opening instruction again.

[0045] Step S2: Generate a second opening instruction based on the calibrated lower dead point, control the opening of the air back pressure valve according to the second opening instruction, obtain the actual lower opening of the air back pressure valve, and determine whether the actual lower opening is greater than the calibrated lower dead point. If so, update the value of the calibrated lower dead point to the actual lower opening. If not, update the value of the calibrated lower dead point to the difference between the actual lower opening and the preset data, and then generate the second opening instruction again.

[0046] Step S3: judging the sealing performance of the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing performance result.

[0047] Step S2 may also be performed before step S1.

[0048] In this embodiment, the calibration top dead point is updated by obtaining the actual maximum opening of the air back pressure valve, and the calibration bottom dead point is updated by obtaining the actual minimum opening of the air back pressure valve. The updated calibration top dead point and calibration bottom dead point can more accurately reflect the opening limit of the air back pressure valve. Based on the more accurate calibration top dead point and calibration bottom dead point, a more reasonable air back pressure valve opening adjustment strategy can be specified, and the sealing of the air back pressure valve can be guaranteed.

[0049] In step S1 , the preset data may be gradually reduced or kept unchanged according to the number of times the first opening instruction is generated in a cycle.

[0050] In step S2, the preset data may be gradually reduced or kept unchanged according to the number of times the second opening instruction is generated in a cycle.

[0051] Furthermore, in one embodiment, during the startup of the fuel cell system, a back pressure valve top dead point self-check is set, the first opening instruction is generated based on the calibrated top dead point to complete the back pressure valve top dead point judgment, and the obtained value is saved in the controller as the new calibrated top dead point, and the above-mentioned back pressure valve top dead point self-check judgment action is repeated during each startup process.

[0052] In this embodiment, during normal operation of the fuel cell system, if the target opening value of the air back pressure valve reaches the calibrated top dead center, the air back pressure valve top dead center judgment logic is triggered, and the top dead center position is determined by the air back pressure valve feedback angle.

[0053] Furthermore, in one embodiment, during the shutdown process of the fuel cell system, a back pressure valve bottom dead point self-check is set, and the second opening instruction is generated based on the calibrated bottom dead point to complete the back pressure valve bottom dead point judgment, and the obtained value is saved as the new bottom dead point in the controller, and the above-mentioned back pressure valve bottom dead point self-check judgment action is repeated during each shutdown process.

[0054] In this embodiment, when the fuel cell system is shut down, the fuel cell system sends a minimum opening command to the air back pressure valve, which triggers the air back pressure valve bottom dead center judgment logic and determines the bottom dead center position through the air back pressure valve feedback angle.

[0055] Furthermore, in one embodiment, the preset value is a minimum control accuracy value of the valve, which is a positive number less than 1.

[0056] The above minimum control accuracy value of the valve is calculated based on the controller control accuracy and component response accuracy.

[0057] In this embodiment, the selection of the preset value should be conducive to approaching the actual maximum opening and the actual minimum opening. If the value is too large, it is easy to cause inaccurate values ​​and redundant operations.

[0058] In one specific implementation, referring to Figure 3 , Figure 3 This is a flow chart illustrating an embodiment of a method for detecting the status of an air backpressure valve in a fuel cell system according to the present application. In this embodiment, the preset value is 0.1. During fuel cell system startup, the controller reads the air backpressure valve calibration top dead center value y stored in the EEPROM, outputs the air backpressure valve target opening as top dead center y, and generates a first opening instruction. The controller then reads the air backpressure valve feedback opening a and determines the difference between the target opening setting value y and the feedback opening a. If a is less than y, indicating that the current maximum air backpressure valve opening is a, the upper calibration dead center value y = a in the EEPROM register is updated. If a is greater than y, indicating that the current EEPROM backpressure valve opening exceeds the calibration top dead center, the upper calibration dead center value y = a + 0.1 is updated, and the new top dead center value y is output as the new calibration backpressure valve opening setting value, generating a new first opening instruction. This cycle repeats until the air backpressure valve feedback value a is less than y.

[0059] After the fuel cell is shut down, the controller reads the calibrated bottom dead center value x stored in the EEPROM and outputs x as the target opening setting value of the air back pressure valve, thereby generating a second opening instruction. At this time, the feedback opening is b. The target opening setting value x is compared with the feedback opening value b. If b is greater than x, it means that the current minimum opening value of the air back pressure valve is b, and the bottom dead center value x in the EEPROM register is updated to b. If b is less than x, it means that the current minimum opening value of the air back pressure valve is lower than the calibrated bottom dead center. The calibrated bottom dead center value x is updated to x = b-0.1, and the new calibrated bottom dead center value x is output as the new opening setting value of the air back pressure valve, thereby generating a second opening instruction again. This cycle repeats until the air back pressure valve feedback value b is greater than x.

[0060] In this embodiment, the maximum and minimum openings that the air back pressure valve can actually reach are accurately found through at least one instruction cycle, and the maximum and minimum openings that can actually be reached are used as the updated calibration top dead point and calibration bottom dead point, thereby ensuring the accuracy of the calibration top dead point and the calibration bottom dead point, and then ensuring the accuracy of various control operations based on the calibration top dead point and the calibration bottom dead point in the later stage.

[0061] For example, in subsequent operations, the fuel cell system controller collects feedback signals from the air flow meter, air inlet pressure, and back-pressure valve angle, and controls the normal operation of the fuel cell air system by sending air compressor speed commands and back-pressure valve angle commands. The target air compressor speed and air back-pressure valve opening required at each operating point of the fuel cell system can be obtained through test calibration. During the operation of the fuel cell system, feedforward and PI controllers are used to perform closed-loop adjustment of the air compressor speed and air back-pressure valve deviation, and the upper and lower saturation limits of the air compressor speed and air back-pressure valve opening are set to not exceed the calibrated upper and lower dead points to avoid calculation distortion or loss of control of the control system, which may cause the pressure of the air entering the stack to deviate too much from the target value or fluctuate significantly, seriously affecting the performance of the fuel cell system.

[0062] Furthermore, in one embodiment, the above-mentioned sealing determination of the air back pressure valve according to the updated calibrated bottom dead center to obtain the sealing result specifically includes the following steps:

[0063] After the hydrogen pressure of the fuel cell stack is increased to the first pressure value, close the air shut-off valve.

[0064] A third opening instruction is generated according to the updated calibrated bottom dead center to adjust the opening of the air back pressure valve to the minimum.

[0065] After the hydrogen pressure of the fuel cell stack is increased to the second pressure value, the timing is started until the hydrogen pressure of the fuel cell stack is increased to the third pressure value, and a time value is obtained to determine whether the time value is less than the preset time threshold. If so, it is determined that the air back pressure valve is sealed normally. If not, it is determined that the air back pressure valve is sealed abnormally.

[0066] In this embodiment, after the fuel system is shut down and the bottom dead center is updated, the sealing performance of the back pressure valve at the new bottom dead center is determined: the stack hydrogen pressure is increased to a value of X1, the air shut-off valve is closed, and the air back pressure valve reaches the bottom dead center for sealing. The anode hydrogen and cathode oxygen in the fuel cell system are slowly consumed through electrochemistry and diffusion, and the anode pressure reaches an inflection point X3. At this point, the controller begins timing. As the cathode sealing valve slowly leaks air into the cathode side and diffuses through the fuel cell proton exchange membrane to the anode side, the hydrogen pressure value slowly increases. When the hydrogen pressure reaches X2, the time is recorded as T1. The sealing time lower limit Tm is determined based on the fuel cell system offline calibration. When T1 is greater than the calibrated sealing time lower limit Tm, the air back pressure valve is considered to be sealing properly; otherwise, the output air back pressure valve seal is faulty.

[0067] In summary, the present invention determines the upper and lower dead point positions through self-learning of the air back pressure valve, and evaluates the sealing effect of the lower dead point through the change in hydrogen pressure after shutdown, thereby predicting the failure of the air back pressure valve seal in advance.

[0068] The system monitors the actuators, namely the air compressor and air back-pressure valve, without blind spots. Detection and diagnosis are possible as long as the system is operating. Fault diagnosis is simple, with no blind spots and high robustness, unaffected by intake and exhaust piping or fuel cell stack performance. Back-pressure valve fault detection is comprehensive.

[0069] In a second aspect, an embodiment of the present application also provides a fuel cell system air back pressure valve status detection system.

[0070] In one embodiment, referring to Figure 4 , Figure 4 This is a functional module diagram of an embodiment of the fuel cell system air back pressure valve status detection system of this application. Figure 4 As shown, the fuel cell system air back pressure valve status detection system includes:

[0071] The top dead center calibration module 1 is used to generate a first opening instruction based on the calibrated top dead center, control the opening of the air back pressure valve according to the first opening instruction, and obtain the actual opening of the air back pressure valve, and judge whether the actual opening is less than the calibrated top dead center. If so, the value of the calibrated top dead center is updated to the actual opening; if not, the value of the calibrated top dead center is updated to the sum of the actual opening and a preset value, and then the first opening instruction is generated again.

[0072] The bottom dead point calibration module 2 is used to generate a second opening instruction based on the calibrated bottom dead point, control the opening of the air back pressure valve according to the second opening instruction, and obtain the actual lower opening of the air back pressure valve, and judge whether the actual lower opening is greater than the calibrated bottom dead point. If so, the value of the calibrated bottom dead point is updated to the actual lower opening; if not, the value of the calibrated bottom dead point is updated to the difference between the actual lower opening and the preset data, and then the second opening instruction is generated again.

[0073] The sealing detection module 3 is used to judge the sealing of the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing result.

[0074] In this embodiment, the calibration top dead point is updated by obtaining the actual maximum opening of the air back pressure valve, and the calibration bottom dead point is updated by obtaining the actual minimum opening of the air back pressure valve. The updated calibration top dead point and calibration bottom dead point can more accurately reflect the opening limit of the air back pressure valve. Based on the more accurate calibration top dead point and calibration bottom dead point, a more reasonable air back pressure valve opening adjustment strategy can be specified, and the sealing of the air back pressure valve can be guaranteed.

[0075] The preset data set by the top dead center calibration module 1 can be gradually reduced or kept unchanged according to the number of times the first opening instruction is generated in a cycle.

[0076] The preset data set by the bottom dead center calibration module 2 can be gradually reduced or kept unchanged according to the number of times the second opening instruction is generated in a cycle.

[0077] Furthermore, in one embodiment, during the startup of the fuel cell system, a back pressure valve top dead point self-check is set, the first opening instruction is generated based on the calibrated top dead point to complete the back pressure valve top dead point judgment, and the obtained value is saved in the controller as the new calibrated top dead point, and the above-mentioned back pressure valve top dead point self-check judgment action is repeated during each startup process.

[0078] In this embodiment, during normal operation of the fuel cell system, if the target opening value of the air back pressure valve reaches the calibrated top dead center, the air back pressure valve top dead center judgment logic is triggered, and the top dead center position is determined by the air back pressure valve feedback angle.

[0079] Furthermore, in one embodiment, during the shutdown process of the fuel cell system, a back pressure valve bottom dead point self-check is set, and the second opening instruction is generated based on the calibrated bottom dead point to complete the back pressure valve bottom dead point judgment, and the obtained value is saved as the new bottom dead point in the controller, and the above-mentioned back pressure valve bottom dead point self-check judgment action is repeated during each shutdown process.

[0080] In this embodiment, when the fuel cell system is shut down, the fuel cell system sends a minimum opening command to the air back pressure valve, which triggers the air back pressure valve bottom dead center judgment logic and determines the bottom dead center position through the air back pressure valve feedback angle.

[0081] Furthermore, in one embodiment, the preset value is a minimum control accuracy value of the valve, which is a positive number less than 1.

[0082] The above minimum control accuracy value of the valve is calculated based on the controller control accuracy and component response accuracy.

[0083] In this embodiment, the selection of the preset value should be conducive to approaching the actual maximum opening and the actual minimum opening. If the value is too large, it is easy to cause inaccurate values ​​and redundant operations.

[0084] In one specific implementation, referring to Figure 3 , Figure 3 This is a flow chart illustrating an embodiment of a method for detecting the status of an air backpressure valve in a fuel cell system according to the present application. In this embodiment, the preset value is 0.1. During fuel cell system startup, the controller reads the air backpressure valve calibration top dead center value y stored in the EEPROM, outputs the air backpressure valve target opening as top dead center y, and generates a first opening instruction. The controller then reads the air backpressure valve feedback opening a and determines the difference between the target opening setting value y and the feedback opening a. If a is less than y, indicating that the current maximum air backpressure valve opening is a, the upper calibration dead center value y = a in the EEPROM register is updated. If a is greater than y, indicating that the current EEPROM backpressure valve opening exceeds the calibration top dead center, the upper calibration dead center value y = a + 0.1 is updated, and the new top dead center value y is output as the new calibration backpressure valve opening setting value, generating a new first opening instruction. This cycle repeats until the air backpressure valve feedback value a is less than y.

[0085] After the fuel cell is shut down, the controller reads the calibrated bottom dead center value x stored in the EEPROM and outputs x as the target opening setting value of the air back pressure valve, thereby generating a second opening instruction. At this time, the feedback opening is b. The target opening setting value x is compared with the feedback opening value b. If b is greater than x, it means that the current minimum opening value of the air back pressure valve is b, and the bottom dead center value x in the EEPROM register is updated to b. If b is less than x, it means that the current minimum opening value of the air back pressure valve is lower than the calibrated bottom dead center. The calibrated bottom dead center value x is updated to x = b-0.1, and the new calibrated bottom dead center value x is output as the new opening setting value of the air back pressure valve, thereby generating a second opening instruction again. This cycle repeats until the air back pressure valve feedback value b is greater than x.

[0086] In this embodiment, the maximum and minimum openings that the air back pressure valve can actually reach are accurately found through at least one instruction cycle, and the maximum and minimum openings that can actually be reached are used as the updated calibration top dead point and calibration bottom dead point, thereby ensuring the accuracy of the calibration top dead point and the calibration bottom dead point, and then ensuring the accuracy of various control operations based on the calibration top dead point and the calibration bottom dead point in the later stage.

[0087] Furthermore, in one embodiment, when the sealing detection module 3 judges the sealing of the air back pressure valve according to the updated calibrated lower dead point to obtain the sealing result, the stack hydrogen pressure is increased to the first pressure value and then the air shut-off valve is closed.

[0088] A third opening instruction is generated according to the updated calibrated bottom dead center to adjust the opening of the air back pressure valve to the minimum.

[0089] After the hydrogen pressure of the fuel cell stack is increased to the second pressure value, the timing is started until the hydrogen pressure of the fuel cell stack is increased to the third pressure value, and a time value is obtained to determine whether the time value is less than the preset time threshold. If so, it is determined that the air back pressure valve is sealed normally. If not, it is determined that the air back pressure valve is sealed abnormally.

[0090] In this embodiment, after the fuel system is shut down and the bottom dead center is updated, the sealing performance of the back pressure valve at the new bottom dead center is determined: the stack hydrogen pressure is increased to a value of X1, the air shut-off valve is closed, and the air back pressure valve reaches the bottom dead center for sealing. The anode hydrogen and cathode oxygen in the fuel cell system are slowly consumed through electrochemistry and diffusion, and the anode pressure reaches an inflection point X3. At this point, the controller begins timing. As the cathode sealing valve slowly leaks air into the cathode side and diffuses through the fuel cell proton exchange membrane to the anode side, the hydrogen pressure value slowly increases. When the hydrogen pressure reaches X2, the time is recorded as T1. The sealing time lower limit Tm is determined based on the fuel cell system offline calibration. When T1 is greater than the calibrated sealing time lower limit Tm, the air back pressure valve is considered to be sealing properly; otherwise, the output air back pressure valve seal is faulty.

[0091] Among them, the functional implementation of each module in the above-mentioned fuel cell system air back pressure valve status detection system corresponds to the various steps in the above-mentioned fuel cell system air back pressure valve status detection method embodiment, and their functions and implementation processes will not be repeated here one by one.

[0092] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0093] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0094] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0095] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0096] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0097] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of the present application.

[0098] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting the state of an air back pressure valve of a fuel cell system, characterized in that: The fuel cell system air back pressure valve state detection method includes: generating a first opening instruction based on the calibrated top dead center, controlling the opening of the air back pressure valve according to the first opening instruction, obtaining an actual opening of the air back pressure valve, and determining whether the actual opening is less than the calibrated top dead center. If so, updating the value of the calibrated top dead center to the actual opening; if not, updating the value of the calibrated top dead center to the sum of the actual opening and a preset value, and then generating the first opening instruction again; generating a second opening instruction based on the calibrated bottom dead center, controlling the opening of the air back pressure valve according to the second opening instruction, obtaining the actual lower opening of the air back pressure valve, and determining whether the actual lower opening is greater than the calibrated bottom dead center. If so, updating the value of the calibrated bottom dead center to the actual lower opening; if not, updating the value of the calibrated bottom dead center to the difference between the actual lower opening and the preset data, and then generating the second opening instruction again; The air back pressure valve is subjected to a sealing judgment based on the updated calibration bottom dead center to obtain a sealing result.

2. The method for detecting the state of the air back pressure valve of the fuel cell system according to claim 1, wherein: The method further comprises: During the startup process of the fuel cell system, a back pressure valve top dead point self-check is set, and the first opening instruction is generated based on the calibrated top dead point to complete the back pressure valve top dead point judgment, and the obtained value is saved in the controller as the new calibrated top dead point. The back pressure valve top dead point self-check judgment action is repeated during each startup process.

3. The method for detecting the state of the air back pressure valve of the fuel cell system according to claim 1, wherein: The method further comprises: During the shutdown process of the fuel cell system, a back pressure valve bottom dead point self-check is set, and the second opening instruction is generated based on the calibrated bottom dead point to complete the back pressure valve bottom dead point judgment, and the obtained value is saved in the controller as the new bottom dead point. The back pressure valve bottom dead point self-check judgment action is repeated during each shutdown process.

4. The method for detecting the state of the air back pressure valve of the fuel cell system according to claim 1, wherein: The preset value adopts the minimum control precision value of the valve; the minimum control precision value of the valve is a positive number less than 1; The minimum control accuracy value of the valve is calculated based on the control accuracy of the controller and the response accuracy of the components.

5. The method for detecting the state of the air back pressure valve of the fuel cell system according to claim 1, wherein: The step of judging the sealing performance of the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing performance result specifically includes the following steps: After the hydrogen pressure of the fuel cell stack is increased to the first pressure value, the air shut-off valve is closed; generating a third opening instruction according to the updated calibrated bottom dead center to adjust the opening of the air back pressure valve to the minimum; After the hydrogen pressure of the fuel cell stack is increased to the second pressure value, the timing is started until the hydrogen pressure of the fuel cell stack is increased to the third pressure value, and a time value is obtained to determine whether the time value is less than the preset time threshold. If so, it is determined that the air back pressure valve is sealed normally. If not, it is determined that the air back pressure valve is sealed abnormally.

6. A fuel cell system air back pressure valve status detection system, characterized in that: The fuel cell system air back pressure valve state detection system includes: a top dead center calibration module, configured to generate a first opening instruction based on the calibrated top dead center, control the opening of the air back pressure valve according to the first opening instruction, obtain the actual opening of the air back pressure valve, determine whether the actual opening is less than the calibrated top dead center, and if so, update the value of the calibrated top dead center to the actual opening; if not, update the value of the calibrated top dead center to the sum of the actual opening and a preset value, and then generate the first opening instruction again; a bottom dead point calibration module, which is used to generate a second opening instruction based on the calibrated bottom dead point, control the opening of the air back pressure valve according to the second opening instruction, and obtain the actual lower opening of the air back pressure valve, determine whether the actual lower opening is greater than the calibrated bottom dead point, and if so, update the value of the calibrated bottom dead point to the actual lower opening; if not, update the value of the calibrated bottom dead point to the difference between the actual lower opening and the preset data, and then generate the second opening instruction again; The sealing detection module is used to judge the sealing of the air back pressure valve according to the updated calibrated bottom dead center to obtain a sealing result.

7. The fuel cell system air back pressure valve state detection system according to claim 6, characterized in that: During the startup of the fuel cell system, the top dead point calibration module sets a back pressure valve top dead point self-check, generates the first opening instruction based on the calibrated top dead point to complete the back pressure valve top dead point judgment, and saves the obtained value as the new calibrated top dead point in the controller, and repeats the back pressure valve top dead point self-check judgment action during each startup process.

8. The fuel cell system air back pressure valve state detection system according to claim 6, characterized in that: During the shutdown process of the fuel cell system, the bottom dead point calibration module sets a back pressure valve bottom dead point self-check, generates the second opening instruction based on the calibrated bottom dead point to complete the back pressure valve bottom dead point judgment, and saves the obtained value as the new bottom dead point in the controller, and repeats the back pressure valve bottom dead point self-check judgment action during each shutdown process.

9. The fuel cell system air back pressure valve state detection system according to claim 6, characterized in that: The preset value adopts the minimum control precision value of the valve; the minimum control precision value of the valve is a positive number less than 1; The minimum control accuracy value of the valve is calculated based on the control accuracy of the controller and the response accuracy of the components.

10. The fuel cell system air back pressure valve state detection system according to claim 6, characterized in that: The sealing detection module judges the sealing of the air back pressure valve according to the updated calibration bottom dead center to obtain a sealing result, and then closes the air stop valve after increasing the hydrogen pressure of the fuel cell stack to a first pressure value; generating a third opening instruction according to the updated calibrated bottom dead center to adjust the opening of the air back pressure valve to the minimum; After the hydrogen pressure of the fuel cell stack is increased to the second pressure value, the timing is started until the hydrogen pressure of the fuel cell stack is increased to the third pressure value, and a time value is obtained to determine whether the time value is less than the preset time threshold. If so, it is determined that the air back pressure valve is sealed normally. If not, it is determined that the air back pressure valve is sealed abnormally.

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