A method of monitoring a fuel cell system

Abstract

This invention discloses a monitoring method for a fuel cell system, relating to the field of fuel cell technology. The method includes: simultaneously acquiring the current-voltage polarization curve and electrochemical impedance spectroscopy (EIS) of the fuel cell system at a preset current point; obtaining real-time impedance parameters based on the EIS, and obtaining real-time polarization slope parameters, real-time average single-cell voltage, and real-time minimum single-cell voltage based on the current-voltage polarization curve; determining calibration test parameters based on the EIS, preset EIS, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage; determining the real-time fuel cell stack lifetime based on the calibration test parameters, the current-voltage polarization curve, and the preset current-voltage polarization curve; and determining fault location information and early warning information based on the real-time fuel cell stack lifetime. This effectively improves the accuracy of fault diagnosis.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a monitoring method for a fuel cell system. Background Technology

[0002] With increasing emphasis on new energy sources and continuous advancements in fuel cell technology, higher demands are being placed on the durability and sustainability of fuel cells. Real-time fault diagnosis can effectively improve fuel cell lifespan. Fault diagnosis is typically based on model-based methods, but existing fault diagnosis technologies suffer from issues such as simplistic fault diagnosis and lagging recovery strategies, affecting the accuracy of fault diagnosis. Summary of the Invention

[0003] This invention provides a monitoring method for a fuel cell system to improve the accuracy of fault diagnosis.

[0004] This invention provides a monitoring method for a fuel cell system, comprising:

[0005] Simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point;

[0006] The real-time impedance parameters are obtained based on the electrochemical impedance spectrum, and the real-time polarization slope parameters, the real-time average single-cell voltage corresponding to the first preset current density, and the real-time minimum single-cell voltage corresponding to the first preset current density are obtained based on the current-voltage polarization curve.

[0007] Obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point;

[0008] The preset impedance parameters are obtained based on the preset electrochemical impedance spectrum, and the preset polarization slope parameters, the preset average single-cell voltage corresponding to the first preset current density, and the preset minimum single-cell voltage corresponding to the first preset current density are obtained based on the preset current-voltage polarization curve.

[0009] The calibration test parameters are determined based on the electrochemical impedance spectrum, the preset electrochemical impedance spectrum, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage.

[0010] The real-time fuel cell stack lifetime is determined based on the calibration test parameters, the current-voltage polarization curve, and the preset current-voltage polarization curve.

[0011] Fault location information and early warning information are determined based on the real-time fuel cell stack life.

[0012] Optionally, calibration test parameters are determined based on the electrochemical impedance spectroscopy, the preset electrochemical impedance spectroscopy, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, including:

[0013] The fuel cell stack fault type is determined based on the electrochemical impedance spectrum, the preset electrochemical impedance spectrum, the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage.

[0014] Determine fault recovery operation information based on the type of fuel cell stack fault;

[0015] The calibration test parameters are determined based on the fault recovery operation information.

[0016] Optionally, the fuel cell stack fault type is determined based on the electrochemical impedance spectroscopy, the preset electrochemical impedance spectroscopy, the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, including:

[0017] When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is less than or equal to the first preset value, it is determined that the fuel cell stack is fault-free at the preset current point.

[0018] When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point, and the fault type of the fuel cell stack is determined according to the real-time impedance parameter, the preset impedance parameter, the real-time average single cell voltage, the real-time minimum single cell voltage, the preset average single cell voltage, and the preset minimum single cell voltage.

[0019] Optionally, the real-time impedance parameters include real-time charge transfer impedance, real-time ohmic impedance, and real-time mass transfer impedance; the real-time polarization slope parameters include real-time activation polarization slope and real-time ohmic polarization slope; the preset impedance parameters include preset charge transfer impedance, preset ohmic impedance, and preset mass transfer impedance; the preset polarization slope parameters include preset activation polarization slope and preset ohmic polarization slope.

[0020] The fuel cell stack fault type is determined based on the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, including:

[0021] When the difference between the real-time ohmic impedance and the preset ohmic impedance is greater than or equal to a second preset value, and the real-time activation polarization slope is greater than the preset activation polarization slope, the fuel cell stack at the preset current point is determined to be a membrane dry fault.

[0022] When the difference between the real-time quality transmission impedance and the preset quality transmission impedance is greater than or equal to a third preset value, and the difference between the real-time average single-cell voltage and the preset average single-cell voltage is greater than or equal to a fourth preset value, the fuel cell stack at the preset current point is determined to be flooded.

[0023] When the difference between the real-time charge transfer impedance and the preset charge transfer impedance is greater than or equal to a fifth preset value, and the real-time ohmic polarization slope is greater than the preset ohmic polarization slope, the fuel cell stack at the preset current point is determined to have a catalyst poisoning fault.

[0024] When the difference between the real-time mass transmission impedance and the preset mass transmission impedance is greater than or equal to a sixth preset value, and the real-time minimum single-cell voltage is less than a preset multiple of the preset minimum single-cell voltage, the fuel cell stack at the preset current point is determined to have a hydrogen permeation fault.

[0025] Optionally, fault recovery operation information is determined based on the type of fault in the fuel cell stack, including:

[0026] When it is determined that the fuel cell stack has a membrane dry fault at the preset current point, the first fault recovery operation information is determined; the first fault recovery operation information includes increasing the humidifier power in the fuel cell system by a first preset step, decreasing the opening time of the hydrogen drain valve in the fuel cell system by a second preset step, or decreasing the cooling water inlet temperature in the fuel cell system by a third preset step.

[0027] When it is determined that the fuel cell stack is flooded at the preset current point, second fault recovery operation information is determined; the second fault recovery operation information includes increasing the anode outlet back pressure in the fuel cell system by a fourth preset step or increasing the air flow in the fuel cell system by a fifth preset step.

[0028] When it is determined that the fuel cell stack has a catalyst poisoning fault at the preset current point, the third fault recovery operation information is determined; the third fault recovery operation information includes adjusting the coolant inlet temperature in the fuel cell system by a sixth preset step size, or performing an anode protection operation.

[0029] When it is determined that the fuel cell stack has a hydrogen permeation fault at the preset current point, the fourth fault recovery operation information is determined; the fourth fault recovery operation information includes reducing the anode side pressure in the fuel cell system by a seventh preset step or reducing the cooling water inlet temperature in the fuel cell system by an eighth preset step.

[0030] Optionally, after determining the fault recovery operation information based on the fuel cell stack fault type, the method further includes:

[0031] Obtain the current number of monitoring cycles for the electrochemical impedance spectroscopy;

[0032] Based on the current number of monitoring cycles, the operation of synchronously acquiring the current-voltage polarization curve and the electrochemical impedance spectrum at the preset current point of the fuel cell system will be performed again.

[0033] When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than a first preset value, it is determined whether the current monitoring number is less than the preset monitoring number.

[0034] When the current number of monitoring is less than the preset number of monitoring, the operation of synchronously acquiring the current-voltage polarization curve of the fuel cell system and the electrochemical impedance spectrum at the preset current point is performed again, and the number of monitoring is updated.

[0035] When the current monitoring count is greater than or equal to the preset monitoring count, the monitoring at the preset current point is stopped, and the monitoring is switched to the next preset current point.

[0036] Optionally, before determining the fuel cell stack fault type based on the electrochemical impedance spectroscopy, the preset electrochemical impedance spectroscopy, the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, the method further includes:

[0037] Obtain the current number of monitoring cycles for the current-voltage polarization curve;

[0038] When the current number of monitoring times meets the preset number of monitoring times, the step of determining the fuel cell stack fault type based on the electrochemical impedance spectrum, the preset electrochemical impedance spectrum, the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage is executed.

[0039] Optionally, the real-time fuel cell stack lifetime is determined based on the calibration test parameters, the current-voltage polarization curve, and the preset current-voltage polarization curve, including:

[0040] The current number of monitoring cycles for the current-voltage polarization curve is obtained based on the calibration test parameters.

[0041] When the current number of monitoring does not meet the preset number of monitoring, it is determined whether the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value.

[0042] When the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value, the monitoring ends.

[0043] When the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is greater than the seventh preset value, the real-time fuel stack lifetime is determined.

[0044] Optionally, fault location information and early warning information are determined based on the real-time fuel cell stack lifetime, including:

[0045] The single lifespan decay is determined based on the real-time fuel cell stack lifespan.

[0046] Obtain the preset lifespan decay;

[0047] Monitoring ends when the single lifetime decay is less than the preset lifetime decay.

[0048] When the single life decay is greater than or equal to the preset life decay, fault location information and early warning information are determined.

[0049] Optionally, the real-time fuel cell stack lifetime is determined based on a first formula, which satisfies the following:

[0050] ;

[0051] Where L is the real-time fuel stack lifetime, and L0 is the baseline lifetime; k i N is the weighting factor for the fault type. i ε represents the number of failures; ε is the natural aging degradation coefficient. Accumulated damage due to faults; t represents natural aging loss; t represents cumulative operating time.

[0052] The technical solution of this invention provides a monitoring method for a fuel cell system, comprising: simultaneously acquiring the current-voltage polarization curve and the electrochemical impedance spectroscopy (EIS) at a preset current point of the fuel cell system; acquiring real-time impedance parameters based on the EIS, and acquiring real-time polarization slope parameters, the real-time average single-cell voltage corresponding to a first preset current density, and the real-time minimum single-cell voltage corresponding to a first preset current density based on the current-voltage polarization curve; acquiring a preset current-voltage polarization curve and a preset EIS at a preset current point; acquiring preset impedance parameters based on the preset EIS, and acquiring preset polarization slope parameters, the preset average single-cell voltage corresponding to a first preset current density, and the preset minimum single-cell voltage corresponding to a first preset current density based on the preset current-voltage polarization curve; determining calibration test parameters based on the EIS, the preset EIS, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage; determining the real-time fuel cell stack lifetime based on the calibration test parameters, the current-voltage polarization curve, and the preset current-voltage polarization curve; and determining fault location information and early warning information based on the real-time fuel cell stack lifetime. This will effectively improve the accuracy of fault diagnosis, enable fault recovery and adjustment, predict the remaining life of the fuel cell, determine the impact of fuel cell faults, and carry out timely repairs to ensure the safety of the fuel cell.

[0053] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A flowchart illustrating a monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0056] Figure 2 A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0057] Figure 3 A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0058] Figure 4A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0059] Figure 5 A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0060] Figure 6 A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0061] Figure 7 A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0062] Figure 8 A flowchart illustrating another monitoring method for a fuel cell system provided in an embodiment of the present invention;

[0063] Figure 9 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention. Detailed Implementation

[0064] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0065] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0066] Figure 1 This is a flowchart illustrating a monitoring method for a fuel cell system according to an embodiment of the present invention. This embodiment is applicable to the monitoring of fuel cell systems. The method can be executed by a monitoring device for the fuel cell system, which can be implemented in hardware and / or software. Figure 1As shown, the method includes:

[0067] S101, simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectra of the fuel cell system at preset current points.

[0068] After the fuel cell system is started, the current-voltage polarization curves and electrochemical impedance spectroscopy (EIS) at a preset current point are acquired simultaneously. The current-voltage polarization curves describe the relationship between the fuel cell output voltage and the output current density, corresponding to different voltage values ​​at different current points. The current-voltage polarization curves include activation polarization, ohmic polarization, and concentration polarization regions. The activation polarization region is less than or equal to 0.2 times the maximum current density and greater than or equal to 0.05 times the maximum current density; the ohmic polarization region is less than or equal to 0.8 times the maximum current density and greater than 0.05 times the maximum current density; and the concentration polarization region is less than or equal to the maximum current density and greater than or equal to 0.8 times the maximum current density. By applying a preset current to the fuel cell and measuring its response signal, the dynamic characteristics of various internal components (such as the membrane, catalyst layer, and gas diffusion layer) are analyzed, resulting in the EIS at the preset current point. The EIS includes ohmic impedance, charge transfer impedance, and mass transport impedance.

[0069] S102, obtain real-time impedance parameters based on electrochemical impedance spectroscopy, and obtain real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0070] Based on the electrochemical impedance spectroscopy, real-time impedance parameters can be extracted, including real-time charge transfer impedance, real-time ohmic impedance, and real-time mass transport impedance. Based on the current-voltage polarization curves, real-time polarization slope parameters, the real-time average single-cell voltage at a first preset current density, and the real-time minimum single-cell voltage at a first preset current density can be extracted. The first preset current density can be the maximum current density. The real-time polarization slope parameters include the real-time activation polarization slope and the real-time ohmic polarization slope.

[0071] S103, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0072] The preset current-voltage polarization curves are standard current-voltage polarization curves, plotted under test conditions strictly following industry standards to clearly show the three major polarization loss regions: activation, ohmic, and concentration. The preset electrochemical impedance spectroscopy (EIS) is a standard EIS, measured under test conditions, methods, and procedures strictly following industry standards to obtain the EIS of the fuel cell.

[0073] S104. Obtain preset impedance parameters based on preset electrochemical impedance spectra, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curves.

[0074] Specifically, preset impedance parameters are extracted based on preset electrochemical impedance spectra, including preset charge transfer impedance, preset ohmic impedance, and preset mass transport impedance. Preset polarization slope parameters, preset average single-cell voltage at a first preset current density, and preset minimum single-cell voltage at a first preset current density are obtained based on preset current-voltage polarization curves. The preset polarization slope parameters include preset activation polarization slope and preset ohmic polarization slope.

[0075] S105, determine the calibration test parameters based on the electrochemical impedance spectrum, preset electrochemical impedance spectrum, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage.

[0076] Specifically, the system compares the electrochemical impedance spectroscopy (EIS) with a preset EIS, the real-time impedance parameters with preset impedance parameters, the real-time average single-cell voltage with the real-time minimum single-cell voltage, and the preset average single-cell voltage with the preset minimum single-cell voltage to determine if a fault exists at the current preset current point. If a fault exists, corresponding fault recovery is required, and the calibration test parameters after the fault recovery operation are recorded. The calibration test parameters are those from the last calibration test during the same fault recovery operation.

[0077] S106. Determine the real-time fuel cell stack life based on the calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0078] After performing online fault recovery on the fuel cell, it is necessary to verify the effect of the calibration test parameters on the fuel cell recovery using current-voltage polarization curves and preset current-voltage polarization curves. The real-time fuel cell stack lifetime is determined by using the calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves to assess the impact of the fault on the fuel cell lifetime.

[0079] S107 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0080] When the real-time fuel cell stack lifespan shows abnormal decline, it is necessary to determine and output fault location information and early warning information. The fault location information can reflect the specific location of the fault, and the early warning information can remind staff to handle the fault in a timely manner, ensuring the safety of the fuel cell system and reducing maintenance costs.

[0081] This invention provides embodiments of the invention that simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectroscopy (EIS) of a fuel cell system at a preset current point; obtain real-time impedance parameters based on the EIS, and obtain real-time polarization slope parameters, the real-time average single-cell voltage at a first preset current density, and the real-time minimum single-cell voltage at the first preset current density based on the current-voltage polarization curves; obtain preset impedance parameters based on the preset EIS, and obtain preset polarization slope parameters, the preset average single-cell voltage at a first preset current density, and the preset minimum single-cell voltage at the first preset current density based on the preset current-voltage polarization curves; determine calibration test parameters based on the EIS, preset EIS, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage; determine the real-time fuel cell stack lifetime based on the calibration test parameters, the current-voltage polarization curves, and the preset current-voltage polarization curves; and determine fault location information and early warning information based on the real-time fuel cell stack lifetime. This will effectively improve the accuracy of fault diagnosis and predict the remaining life of the fuel cell, thereby determining the impact of fuel cell faults and enabling timely repairs to ensure the safety of the fuel cell.

[0082] Optional, Figure 2 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 2 As shown, the method includes:

[0083] S201, simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0084] S202, obtain real-time impedance parameters based on electrochemical impedance spectroscopy, and obtain real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0085] S203, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0086] S204. Obtain preset impedance parameters based on preset electrochemical impedance spectra, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curves.

[0087] S205, determine the fuel cell stack fault type based on electrochemical impedance spectroscopy, preset electrochemical impedance spectroscopy, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage.

[0088] Specifically, the current fuel cell stack fault type is determined by comparing the electrochemical impedance spectroscopy (EIS) with a preset EIS, comparing the real-time impedance parameters with preset impedance parameters, comparing the real-time average single-cell voltage with the real-time minimum single-cell voltage, and comparing the preset average single-cell voltage with the preset minimum single-cell voltage. Fuel cell stack fault types can include flooding faults, membrane dryness faults, catalyst poisoning faults, and hydrogen permeation faults.

[0089] S206, determine fault recovery operation information based on the type of fuel cell stack fault.

[0090] Specifically, corresponding fault recovery operation information is determined based on different types of fuel cell stack faults in order to restore the fuel cell stack faults.

[0091] S207, determine the calibration test parameters based on the fault recovery operation information.

[0092] Different fault recovery operation information corresponds to different calibration test parameters.

[0093] S208 determines the real-time fuel cell stack life based on calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0094] S209 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0095] This invention determines the fuel cell stack fault type based on electrochemical impedance spectroscopy (EIS), a preset EIS, real-time impedance parameters, a preset impedance parameter, real-time average single-cell voltage, real-time minimum single-cell voltage, a preset average single-cell voltage, and a preset minimum single-cell voltage. Fault recovery operation information is determined based on the fault type. Correction test parameters are then determined based on the fault recovery operation information. By using EIS, a preset EIS, current-voltage polarization curves, and a preset current-voltage polarization curve to determine the corresponding fuel cell stack fault type, and by determining fault recovery operation information based on the fault type, and by determining corresponding fault recovery operation information for different fuel cell stack fault types, this invention achieves fault recovery of the fuel cell stack, effectively improves fault diagnosis accuracy, and ensures timely fault recovery.

[0096] Optional, Figure 3 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 3 As shown, the method includes:

[0097] S301, simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0098] S302, obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0099] S303, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0100] S304, obtain preset impedance parameters based on preset electrochemical impedance spectrum, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0101] S305, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is less than or equal to the first preset value, it is determined that the fuel cell stack is fault-free at the preset current point.

[0102] The first preset value can be set according to different types of fuel cell stacks, and this embodiment of the invention does not impose specific limitations. When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is less than or equal to the first preset value, it is considered that the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum at the current preset current point is small, and the fuel cell stack at the preset current point is determined to be fault-free.

[0103] S306 When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point, and the fault type of the fuel cell stack is determined according to the real-time impedance parameters, preset impedance parameters, real-time average single cell voltage, real-time minimum single cell voltage, preset average single cell voltage, and preset minimum single cell voltage.

[0104] Specifically, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is considered that the difference between the electrochemical impedance spectrum at the current preset current point and the preset electrochemical impedance spectrum is large. Therefore, it is determined that there is a fault in the fuel cell stack at the preset current point, and it is necessary to continue to investigate the fault type of the fuel cell stack and then recover from the fault.

[0105] S307, determine fault recovery operation information based on the type of fuel cell stack fault.

[0106] S308, determine the calibration test parameters based on the fault recovery operation information.

[0107] S309 determines the real-time fuel cell stack life based on calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0108] S310 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0109] This invention determines that the fuel cell stack is fault-free at a preset current point when the absolute value of the difference between the electrochemical impedance spectroscopy (EIS) and a preset EIS is less than or equal to a first preset value. Conversely, it determines that a fault exists in the fuel cell stack at the preset current point when the absolute value of the difference is greater than the first preset value. The fault type is then determined based on real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage. By comparing the EIS, the preset EIS, and the first preset value, the existence of a fault at the preset current point is determined, ensuring the accuracy of fault diagnosis.

[0110] Optional, Figure 4 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 4 As shown, the real-time impedance parameters include real-time charge transfer impedance, real-time ohmic impedance, and real-time mass transfer impedance; the real-time polarization slope parameters include real-time activation polarization slope and real-time ohmic polarization slope; the preset impedance parameters include preset charge transfer impedance, preset ohmic impedance, and preset mass transfer impedance; the preset polarization slope parameters include preset activation polarization slope and preset ohmic polarization slope. The method includes:

[0111] S401, simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0112] S402, obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0113] S403, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0114] S404, obtain preset impedance parameters based on preset electrochemical impedance spectrum, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0115] S405, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is less than or equal to the first preset value, it is determined that the fuel cell stack is fault-free at the preset current point.

[0116] S406, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time ohmic impedance and the preset ohmic impedance is greater than or equal to the second preset value, and the real-time activation polarization slope is greater than the preset activation polarization slope, it is determined that the fuel cell stack at the preset current point is a membrane dry fault.

[0117] When a fault is determined in the fuel cell stack at a preset current point, further determination of the specific fault type is required. The second preset value can be set according to different types of fuel cell stacks, and this embodiment of the invention does not impose specific limitations. When the difference between the real-time ohmic impedance and the preset ohmic impedance is greater than or equal to the second preset value, and the real-time activation polarization slope is greater than the preset activation polarization slope, it is considered that the internal membrane of the fuel cell stack is dry at the current preset current point, and the fuel cell stack at the preset current point is determined to have a membrane dryness fault.

[0118] S407, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to the third preset value, and the difference between the real-time average single cell voltage and the preset average single cell voltage is greater than or equal to the fourth preset value, it is determined that the fuel cell stack at the preset current point is flooded.

[0119] The third and fourth preset values ​​can be set according to different types of fuel cell stacks, and this embodiment of the invention does not impose specific limitations. When the difference between the real-time mass transmission impedance and the preset mass transmission impedance is greater than or equal to the third preset value, and the difference between the real-time average single-cell voltage and the preset average single-cell voltage is greater than or equal to the fourth preset value, it is considered that the cathode inside the fuel cell stack has been flooded at the current preset current point, and the fuel cell stack at the preset current point is determined to be flooded.

[0120] S408, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time charge transfer impedance and the preset charge transfer impedance is greater than or equal to the fifth preset value, and the real-time ohmic polarization slope is greater than the preset ohmic polarization slope, it is determined that the fuel cell stack at the preset current point is a catalyst poisoning fault.

[0121] The fifth preset value can be set according to different types of fuel cell stacks, and this embodiment of the invention does not impose specific limitations. When the difference between the real-time charge transfer impedance and the preset charge transfer impedance is greater than or equal to the fifth preset value, and the real-time ohmic polarization slope is greater than the preset ohmic polarization slope, it is considered that the fuel cell stack membrane electrode has undergone catalyst poisoning at the current preset current point, and the fuel cell stack at the preset current point is determined to have a catalyst poisoning fault.

[0122] S409, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to the sixth preset value, and the real-time minimum single-cell voltage is less than the preset multiple of the preset minimum single-cell voltage, it is determined that the fuel cell stack at the preset current point is a hydrogen permeation fault.

[0123] The sixth preset value can be set according to different types of fuel cell stacks, and this embodiment of the invention does not impose specific limitations. The preset multiplier can be 0.2. When the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to the sixth preset value, and the real-time minimum single-cell voltage is less than the preset multiplier of the preset minimum single-cell voltage, or when the real-time mass transfer impedance cannot be resolved, it is considered that hydrogen permeation has occurred in the membrane electrode assembly of the fuel cell stack at the current preset current point, and the fuel cell stack at the preset current point is determined to have a hydrogen permeation fault.

[0124] S410 determines fault recovery operation information based on membrane dryness fault, water flooding fault, catalyst poisoning fault, and hydrogen permeation fault.

[0125] S411, determine the calibration test parameters based on the fault recovery operation information.

[0126] S412 determines the real-time fuel cell stack lifetime based on calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0127] S413 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0128] This invention determines a fault in the fuel cell stack at a preset current point when the absolute value of the difference between the electrochemical impedance spectrum and a preset electrochemical impedance spectrum is greater than a first preset value; when the difference between the real-time ohmic impedance and the preset ohmic impedance is greater than or equal to a second preset value, and the real-time activation polarization slope is greater than a preset activation polarization slope, the fuel cell stack at the preset current point is determined to have a membrane dryness fault; when the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to a third preset value, and the difference between the real-time average single-cell voltage and the preset average single-cell voltage is greater than or equal to a fourth preset value, the fuel cell stack at the preset current point is determined to have a flooding fault; when the difference between the real-time charge transfer impedance and the preset charge transfer impedance is greater than or equal to a fifth preset value, and the real-time ohmic polarization slope is greater than a preset ohmic polarization slope, the fuel cell stack at the preset current point is determined to have a catalyst poisoning fault; when the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to a sixth preset value, and the real-time minimum single-cell voltage is less than a preset multiple of the preset minimum single-cell voltage, the fuel cell stack at the preset current point is determined to have a hydrogen permeation fault. By accurately diagnosing the type of fault, the subsequent fault recovery effect can be effectively improved, thus ensuring the performance of the fuel cell stack.

[0129] Optional, Figure 5 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 5 As shown, the method includes:

[0130] S501, simultaneously acquires the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0131] S502, obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0132] S503, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0133] S504, obtain preset impedance parameters based on preset electrochemical impedance spectrum, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0134] S505, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is less than or equal to the first preset value, it is determined that the fuel cell stack is fault-free at the preset current point.

[0135] S506, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time ohmic impedance and the preset ohmic impedance is greater than or equal to the second preset value, and the real-time activation polarization slope is greater than the preset activation polarization slope, it is determined that the fuel cell stack at the preset current point is a membrane dry fault.

[0136] S507, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to the third preset value, and the difference between the real-time average single cell voltage and the preset average single cell voltage is greater than or equal to the fourth preset value, it is determined that the fuel cell stack at the preset current point is flooded.

[0137] S508, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time charge transfer impedance and the preset charge transfer impedance is greater than or equal to the fifth preset value, and the real-time ohmic polarization slope is greater than the preset ohmic polarization slope, it is determined that the fuel cell stack at the preset current point is a catalyst poisoning fault.

[0138] S509, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point. When the difference between the real-time mass transfer impedance and the preset mass transfer impedance is greater than or equal to the sixth preset value, and the real-time minimum single-cell voltage is less than the preset multiple of the preset minimum single-cell voltage, it is determined that the fuel cell stack at the preset current point is a hydrogen permeation fault.

[0139] S510, when it is determined that the fuel cell stack has a membrane dry fault at the preset current point, the first fault recovery operation information is determined; the first fault recovery operation information includes increasing the humidifier power in the fuel cell system by a first preset step, decreasing the opening time of the hydrogen drain valve in the fuel cell system by a second preset step, or decreasing the cooling water inlet temperature in the fuel cell system by a third preset step.

[0140] When the fuel cell stack is determined to have a membrane dryness fault at a preset current point, first fault recovery operation information can be determined based on the membrane dryness fault. The first fault recovery operation information includes increasing the humidifier power in the fuel cell system by a first preset step size to increase the water spray flow rate. The first preset step size can be set according to actual fault improvement needs to ensure the resolution of the membrane dryness fault; this embodiment of the invention does not impose specific limitations. The first fault recovery operation information may also include decreasing the opening time of the hydrogen path drain valve in the fuel cell system by a second preset step size to extend the drain interval and avoid excessive draining that exacerbates membrane dryness. The second preset step size can be set according to actual fault improvement needs; this embodiment of the invention does not impose specific limitations. The first fault recovery operation information may also include decreasing the cooling water inlet temperature in the fuel cell system by a third preset step size to reduce water evaporation. The third preset step size can be set according to actual fault improvement needs; this embodiment of the invention does not impose specific limitations.

[0141] S511, when it is determined that the fuel cell stack is flooded at the preset current point, the second fault recovery operation information is determined; the second fault recovery operation information includes increasing the anode outlet back pressure in the fuel cell system by a fourth preset step or increasing the air flow in the fuel cell system by a fifth preset step.

[0142] When the fuel cell stack is determined to have a flooding fault at a preset current point, second fault recovery operation information can be determined based on the flooding fault. The second fault recovery operation information includes increasing the anode outlet back pressure in the fuel cell system by a fourth preset step size to promote the discharge of liquid water. The fourth preset step size can be set according to actual fault improvement needs, and this embodiment of the invention does not impose specific limitations. The second fault recovery operation information may also include increasing the air flow rate in the fuel cell system by a fifth preset step size to promote the discharge of liquid water. The fifth preset step size can be set according to actual fault improvement needs, and this embodiment of the invention does not impose specific limitations.

[0143] S512, when it is determined that the fuel cell stack has a catalyst poisoning fault at the preset current point, the third fault recovery operation information is determined; the third fault recovery operation information includes adjusting the coolant inlet temperature in the fuel cell system by the sixth preset step size, or performing an anode protection operation.

[0144] When the fuel cell stack is determined to have a catalyst poisoning fault at a preset current point, a third fault recovery operation can be determined based on the catalyst poisoning fault. The third fault recovery operation includes adjusting the coolant inlet temperature in the fuel cell system by a sixth preset step size. This adjustment can include increasing or decreasing the coolant inlet temperature. Through physicochemical processes, poisons (typically carbon monoxide, sulfides, etc.) are desorbed from the platinum-based catalyst surface, and catalyst activity is restored, thus recovering the performance loss caused by catalyst poisoning. The sixth preset step size can be set according to actual fault improvement needs; this embodiment of the invention does not impose specific limitations. The third fault recovery operation may also include performing an anode protection operation. The anode protection operation is to prevent the formation of a hydrogen-air interface during the next startup of the fuel cell system, which would cause corrosion of the carbon support on the cathode side. This operation is typically performed when the system is shut down to prevent the formation of vacant states on both sides of the membrane electrode assembly inside the stack.

[0145] S513, when it is determined that the fuel cell stack is in a hydrogen permeation fault at the preset current point, the fourth fault recovery operation information is determined; the fourth fault recovery operation information includes reducing the anode side pressure in the fuel cell system by the seventh preset step size, or reducing the cooling water inlet temperature in the fuel cell system by the eighth preset step size.

[0146] When the fuel cell stack is determined to have a hydrogen permeation fault at a preset current point, a fourth fault recovery operation can be determined based on the hydrogen permeation fault. The fourth fault recovery operation includes reducing the anode-side pressure in the fuel cell system by a seventh preset step size. During the pressure reduction process, the anode-side pressure should always be kept higher than the cathode-side pressure to recover the performance loss caused by hydrogen permeation. The seventh preset step size can be set according to the actual fault improvement needs, and this embodiment of the invention does not impose specific limitations. The fourth fault recovery operation information may also include reducing the cooling water inlet temperature in the fuel cell system by an eighth preset step size. After stabilization, continuous operation for a period of time restores the membrane's compactness to recover the performance loss caused by hydrogen permeation. The eighth preset step size can be set according to the actual fault improvement needs, and this embodiment of the invention does not impose specific limitations.

[0147] S514, determine the calibration test parameters based on the first fault recovery operation information, the second fault recovery operation information, the third fault recovery operation information, or the fourth fault recovery operation information.

[0148] S515 determines the real-time fuel cell stack life based on calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0149] S516 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0150] In this embodiment of the invention, when a membrane dryness fault is determined in the fuel cell stack at a preset current point, first fault recovery operation information is determined. This first fault recovery operation information includes increasing the humidifier power in the fuel cell system by a first preset step, decreasing the opening time of the hydrogen drain valve in the fuel cell system by a second preset step, or decreasing the cooling water inlet temperature in the fuel cell system by a third preset step. When a flooding fault is determined in the fuel cell stack at the preset current point, second fault recovery operation information is determined. This second fault recovery operation information includes increasing the anode outlet back pressure in the fuel cell system by a fourth preset step or increasing the air flow rate in the fuel cell system by a fifth preset step. When a catalyst poisoning fault is determined in the fuel cell stack at the preset current point, third fault recovery operation information is determined. This third fault recovery operation information includes increasing or decreasing the coolant inlet temperature in the fuel cell system by a sixth preset step, or performing an anode protection operation. When a hydrogen permeation fault is determined in the fuel cell stack at the preset current point, fourth fault recovery operation information is determined. This fourth fault recovery operation information includes decreasing the anode side pressure in the fuel cell system by a seventh preset step, or decreasing the cooling water inlet temperature in the fuel cell system by an eighth preset step. The stack fault is restored according to the first fault recovery operation information, the second fault recovery operation information, the third fault recovery operation information, or the fourth fault recovery operation information to ensure the recovery effect.

[0151] Optional, Figure 6 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 6 As shown, the method includes:

[0152] S601, simultaneously acquires the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0153] S602, obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0154] S603, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0155] S604, obtain preset impedance parameters based on preset electrochemical impedance spectrum, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0156] S605 determines the fuel cell stack fault type based on the electrochemical impedance spectrum, preset electrochemical impedance spectrum, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage.

[0157] S606, determine fault recovery operation information based on the type of fuel cell stack fault.

[0158] S607, obtain the current number of monitoring times for electrochemical impedance spectroscopy.

[0159] After completing the fault recovery operation of the fuel cell stack, it is necessary to obtain the current number of monitoring times of the electrochemical impedance spectroscopy.

[0160] S608, based on the current number of monitoring cycles, perform the operation of synchronously acquiring the current-voltage polarization curve of the fuel cell system and the electrochemical impedance spectrum at the preset current point again.

[0161] The monitoring count is updated based on the current monitoring count. For example, if the current monitoring count is 1, the updated monitoring count is incremented by 1, resulting in 2 monitoring counts. After the monitoring count is updated, the operation of synchronously acquiring the current-voltage polarization curves and electrochemical impedance spectroscopy at a preset current point of the fuel cell system is performed again. That is, the operations of steps S601-S604 above are repeated.

[0162] S609, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined whether the current monitoring number is less than the preset monitoring number.

[0163] Specifically, when the absolute value of the difference between the electrochemical impedance spectroscopy (EIS) and the preset EIS is less than or equal to a first preset value, the fuel cell stack is determined to be fault-free at the preset current point. When the absolute value of the difference between the EIS and the preset EIS is greater than the first preset value, it is determined whether the current number of monitoring iterations is less than the preset number of monitoring iterations to determine the next step in the workflow.

[0164] S610, when the current number of monitoring is less than the preset number of monitoring, perform the operation of synchronously acquiring the current-voltage polarization curve of the fuel cell system and the electrochemical impedance spectrum at the preset current point again, and update the number of monitoring.

[0165] For example, when the current monitoring count is 2 and the preset monitoring count is 3, the operation of synchronously acquiring the current-voltage polarization curves and electrochemical impedance spectroscopy at the preset current point of the fuel cell system can be performed again, and the monitoring count can be updated. When the current monitoring count is greater than or equal to the preset monitoring count, for example, when the current monitoring count is 3 and the preset monitoring count is 2, the monitoring count can be reset to zero, and monitoring can proceed to the next preset current point. At the next current point, the calibration test parameters at each current point are detected or recorded, and then the current-voltage polarization curve test verifies the effect of parameter optimization on the performance recovery of the fuel cell stack.

[0166] S611, determine the calibration test parameters based on the fault recovery operation information.

[0167] S612 determines the real-time fuel cell stack life based on calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0168] S613 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0169] This invention employs a method to acquire the current number of monitoring iterations of an electrochemical impedance spectroscopy (EIS). Based on this current number of iterations, it re-executes the operation of simultaneously acquiring the current-voltage polarization curve of the fuel cell system and the EIS at a preset current point. When the absolute value of the difference between the EIS and the preset EIS is greater than a first preset value, it determines whether the current number of monitoring iterations is less than the preset number of monitoring iterations. If the current number of monitoring iterations is less than the preset number of monitoring iterations, it re-executes the operation of simultaneously acquiring the current-voltage polarization curve of the fuel cell system and the EIS at the preset current point, and updates the monitoring number. This effectively ensures the accuracy of fault diagnosis and the effectiveness of fault recovery.

[0170] Optional, Figure 7 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 7 As shown, the method includes:

[0171] S701, simultaneously acquires the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0172] S702 obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0173] S703, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0174] S704, obtain preset impedance parameters based on preset electrochemical impedance spectrum, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0175] S705, obtains the current number of monitoring cycles for the current and voltage polarization curves.

[0176] In the process of diagnosing fault types in fuel cell stacks, it is necessary to obtain the current monitoring count of the current-voltage polarization curve in order to combine the electrochemical impedance spectroscopy with the current-voltage polarization curve to achieve multi-scale characteristic capacitance for fault type determination.

[0177] S706 When the current number of monitoring times meets the preset number of monitoring times, the fault type of the fuel cell stack is determined based on the electrochemical impedance spectrum, preset electrochemical impedance spectrum, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage.

[0178] The preset number of monitoring times can be set according to actual design requirements, and this embodiment of the invention does not impose specific limitations. For example, the preset number of monitoring times can be 2. When the current-voltage polarization curve has a current monitoring time of 1, the monitoring time is incremented by 1 and updated to 2. At this time, it is necessary to combine the electrochemical impedance spectroscopy with the current-voltage polarization curve to perform multi-scale feature fusion to determine the fault type of the fuel cell stack, thereby improving the accuracy of the fault type determination.

[0179] S707 determines fault recovery operation information based on the type of fuel cell stack fault.

[0180] S708, obtains the current number of monitoring cycles for electrochemical impedance spectroscopy.

[0181] S709, based on the current number of monitoring cycles, perform the operation of synchronously acquiring the current-voltage polarization curve of the fuel cell system and the electrochemical impedance spectrum at the preset current point again.

[0182] S710, when the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined whether the current monitoring number is less than the preset monitoring number.

[0183] S711, when the current number of monitoring is less than the preset number of monitoring, perform the operation of synchronously acquiring the current-voltage polarization curve of the fuel cell system and the electrochemical impedance spectrum at the preset current point again, and update the number of monitoring.

[0184] S712, determine the calibration test parameters based on the fault recovery operation information.

[0185] S713 determines the real-time fuel cell stack life based on calibration test parameters, current-voltage polarization curves, and preset current-voltage polarization curves.

[0186] S714 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0187] This invention obtains the current number of monitoring cycles of the current-voltage polarization curve. When the current number of monitoring cycles meets a preset number of monitoring cycles, the fuel cell stack fault type is determined based on the electrochemical impedance spectroscopy, a preset electrochemical impedance spectroscopy, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage. This improves the accuracy of fuel cell stack fault type determination.

[0188] Optional, Figure 8 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 8 As shown, the method includes:

[0189] S801, simultaneously acquires the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0190] S802 obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0191] S803, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0192] S804, obtains preset impedance parameters based on preset electrochemical impedance spectrum, and obtains preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0193] S805 determines the calibration test parameters based on the electrochemical impedance spectrum, preset electrochemical impedance spectrum, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage.

[0194] S806, obtain the current monitoring count of the current-voltage polarization curve based on the calibration test parameters.

[0195] After obtaining the calibration test parameters, it is assumed that the parameters of the fuel cell system have changed, and the optimized parameters need to be verified using current-voltage polarization curves. Therefore, it is necessary to obtain the current number of monitoring cycles for the current-voltage polarization curves based on the calibration test parameters.

[0196] S807, when the current number of monitoring does not meet the preset number of monitoring, determine whether the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value.

[0197] In this scenario, if the current monitoring count does not meet the preset monitoring count, it can be set to exceed the preset monitoring count. In this case, the current-voltage polarization curve needs to be compared with the preset current-voltage polarization curve to determine whether the correction test parameters have a restorative effect on the stack fault. The seventh preset value can be limited according to actual design requirements; this embodiment of the invention does not impose specific limitations.

[0198] S808: When the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value, the monitoring ends.

[0199] Among them, when the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value, it is considered that the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is small, and it is determined that the correction test parameters play a role in the recovery of the stack performance, and the monitoring ends.

[0200] S809, when the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is greater than the seventh preset value, the real-time fuel stack lifetime is determined.

[0201] Specifically, when the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is greater than the seventh preset value, it is considered that the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is large. In this case, it is determined that the correction test parameters have failed to restore the stack performance, and stack lifetime prediction should be performed to determine the real-time fuel stack lifetime and assess the impact of the current fault on the stack lifetime. Lifetime prediction can be performed using a lifetime prediction model. For example, based on the first formula, the real-time fuel stack lifetime can be determined. The first formula satisfies: Where L is the real-time fuel stack lifetime, and L0 is the baseline lifetime; k i N is the weighting factor for the fault type. i ε represents the number of failures; ε is the natural aging degradation coefficient. Accumulated damage due to faults; t represents natural aging loss; t represents cumulative operating time. The degree of degradation or reversible recovery of the fuel cell stack caused by cathode flooding, membrane dryness, catalyst poisoning, and hydrogen permeation faults is recorded. The fault type weighting factors are: membrane dryness k1, cathode flooding k2, catalyst poisoning k3, and hydrogen permeation k4; the fault occurrence frequency is assigned as: membrane dryness N1, cathode flooding N2, catalyst poisoning N3, and hydrogen permeation N4; the natural aging degradation coefficient ε is provided by the fuel cell stack manufacturer.

[0202] S810 determines fault location information and early warning information based on the real-time fuel cell stack life.

[0203] This invention obtains the current monitoring count of the current-voltage polarization curve based on calibration test parameters. When the current monitoring count does not meet the preset monitoring count, it determines whether the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to a seventh preset value. If the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value, monitoring ends. If the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is greater than the seventh preset value, the real-time fuel cell stack lifetime is determined. By timely assessing the impact of current faults on stack lifetime, the safety of the fuel cell system is ensured.

[0204] Optional, Figure 9 A flowchart of another monitoring method for a fuel cell system provided in an embodiment of the present invention is shown below. Figure 9 As shown, the method includes:

[0205] S901, simultaneously acquires the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point.

[0206] S902 obtains real-time impedance parameters based on electrochemical impedance spectroscopy, and obtains real-time polarization slope parameters, real-time average single-cell voltage corresponding to the first preset current density, and real-time minimum single-cell voltage corresponding to the first preset current density based on current-voltage polarization curves.

[0207] S903, obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point.

[0208] S904, obtain preset impedance parameters based on preset electrochemical impedance spectrum, and obtain preset polarization slope parameters, preset average single-cell voltage corresponding to the first preset current density, and preset minimum single-cell voltage corresponding to the first preset current density based on preset current-voltage polarization curve.

[0209] S905 determines the calibration test parameters based on the electrochemical impedance spectrum, preset electrochemical impedance spectrum, real-time impedance parameters, preset impedance parameters, real-time average single-cell voltage, real-time minimum single-cell voltage, preset average single-cell voltage, and preset minimum single-cell voltage.

[0210] S906, obtain the current monitoring count of the current-voltage polarization curve based on the calibration test parameters.

[0211] S907, when the current number of monitoring does not meet the preset number of monitoring, determine whether the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value.

[0212] S908, when the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value, the monitoring ends.

[0213] S909, when the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is greater than the seventh preset value, the real-time fuel stack lifetime is determined.

[0214] S910 determines the single-cycle lifespan degradation based on the real-time fuel cell stack lifespan.

[0215] Specifically, the single-cycle lifespan decay can be obtained based on the real-time fuel cell stack lifespan. This single-cycle lifespan decay is then compared with a preset lifespan decay to determine the impact of the fault on the battery lifespan. The preset lifespan decay can be set according to actual design requirements, and this embodiment of the invention does not impose specific limitations.

[0216] S911: When the single lifetime decay is less than the preset lifetime decay, the monitoring ends.

[0217] Specifically, if the single life decay is less than the preset life decay, the current fuel cell stack decay is considered to be normal decay, and monitoring will then end.

[0218] S912: When the single life decay is greater than or equal to the preset life decay, the fault location information and early warning information are determined.

[0219] When a single life decay is greater than or equal to the preset life decay, the current fuel cell stack decay is considered abnormal, and fault location information and early warning information need to be output to remind staff to check and repair in a timely manner.

[0220] This invention determines single-cycle lifespan degradation based on the real-time fuel cell stack lifespan. Monitoring ends when the single-cycle lifespan degradation is less than a preset lifespan degradation. When the single-cycle lifespan degradation is greater than or equal to the preset lifespan degradation, fault location information and early warning information are determined and output. This alerts personnel to promptly inspect and repair the system, ensuring the safety of the fuel cell system.

[0221] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A monitoring method for a fuel cell system, characterized in that, include: Simultaneously acquire the current-voltage polarization curves and electrochemical impedance spectroscopy of the fuel cell system at a preset current point; The real-time impedance parameters are obtained based on the electrochemical impedance spectrum, and the real-time polarization slope parameters, the real-time average single-cell voltage corresponding to the first preset current density, and the real-time minimum single-cell voltage corresponding to the first preset current density are obtained based on the current-voltage polarization curve. Obtain the preset current-voltage polarization curve and the preset electrochemical impedance spectrum at the preset current point; The preset impedance parameters are obtained based on the preset electrochemical impedance spectrum, and the preset polarization slope parameters, the preset average single-cell voltage corresponding to the first preset current density, and the preset minimum single-cell voltage corresponding to the first preset current density are obtained based on the preset current-voltage polarization curve. The calibration test parameters are determined based on the electrochemical impedance spectrum, the preset electrochemical impedance spectrum, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage. The real-time fuel cell stack lifetime is determined based on the calibration test parameters, the current-voltage polarization curve, and the preset current-voltage polarization curve. Fault location information and early warning information are determined based on the real-time fuel cell stack life.

2. The monitoring method for a fuel cell system according to claim 1, characterized in that, The calibration test parameters are determined based on the electrochemical impedance spectroscopy, the preset electrochemical impedance spectroscopy, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, including: The fuel cell stack fault type is determined based on the electrochemical impedance spectrum, the preset electrochemical impedance spectrum, the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage. Determine fault recovery operation information based on the type of fuel cell stack fault; The calibration test parameters are determined based on the fault recovery operation information.

3. The monitoring method for a fuel cell system according to claim 2, characterized in that, The fuel cell stack fault type is determined based on the electrochemical impedance spectroscopy, the preset electrochemical impedance spectroscopy, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, including: When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is less than or equal to the first preset value, it is determined that the fuel cell stack is fault-free at the preset current point. When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than the first preset value, it is determined that there is a fault in the fuel cell stack at the preset current point, and the fault type of the fuel cell stack is determined according to the real-time impedance parameter, the preset impedance parameter, the real-time average single cell voltage, the real-time minimum single cell voltage, the preset average single cell voltage, and the preset minimum single cell voltage.

4. The monitoring method for a fuel cell system according to claim 3, characterized in that, The real-time impedance parameters include real-time charge transfer impedance, real-time ohmic impedance, and real-time mass transfer impedance; the real-time polarization slope parameters include real-time activation polarization slope and real-time ohmic polarization slope; the preset impedance parameters include preset charge transfer impedance, preset ohmic impedance, and preset mass transfer impedance; the preset polarization slope parameters include preset activation polarization slope and preset ohmic polarization slope. The fuel cell stack fault type is determined based on the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, including: When the difference between the real-time ohmic impedance and the preset ohmic impedance is greater than or equal to a second preset value, and the real-time activation polarization slope is greater than the preset activation polarization slope, the fuel cell stack at the preset current point is determined to be a membrane dry fault. When the difference between the real-time quality transmission impedance and the preset quality transmission impedance is greater than or equal to a third preset value, and the difference between the real-time average single-cell voltage and the preset average single-cell voltage is greater than or equal to a fourth preset value, the fuel cell stack at the preset current point is determined to be flooded. When the difference between the real-time charge transfer impedance and the preset charge transfer impedance is greater than or equal to a fifth preset value, and the real-time ohmic polarization slope is greater than the preset ohmic polarization slope, the fuel cell stack at the preset current point is determined to have a catalyst poisoning fault. When the difference between the real-time mass transmission impedance and the preset mass transmission impedance is greater than or equal to a sixth preset value, and the real-time minimum single-cell voltage is less than a preset multiple of the preset minimum single-cell voltage, the fuel cell stack at the preset current point is determined to have a hydrogen permeation fault.

5. The monitoring method for a fuel cell system according to claim 4, characterized in that, Based on the type of fuel cell stack fault, fault recovery operation information is determined, including: When it is determined that the fuel cell stack has a membrane dry fault at the preset current point, the first fault recovery operation information is determined; the first fault recovery operation information includes increasing the humidifier power in the fuel cell system by a first preset step, decreasing the opening time of the hydrogen drain valve in the fuel cell system by a second preset step, or decreasing the cooling water inlet temperature in the fuel cell system by a third preset step. When it is determined that the fuel cell stack is flooded at the preset current point, second fault recovery operation information is determined; the second fault recovery operation information includes increasing the anode outlet back pressure in the fuel cell system by a fourth preset step or increasing the air flow in the fuel cell system by a fifth preset step. When it is determined that the fuel cell stack has a catalyst poisoning fault at the preset current point, the third fault recovery operation information is determined; the third fault recovery operation information includes adjusting the coolant inlet temperature in the fuel cell system by a sixth preset step size, or performing an anode protection operation. When it is determined that the fuel cell stack has a hydrogen permeation fault at the preset current point, the fourth fault recovery operation information is determined; the fourth fault recovery operation information includes reducing the anode side pressure in the fuel cell system by a seventh preset step or reducing the cooling water inlet temperature in the fuel cell system by an eighth preset step.

6. The monitoring method for a fuel cell system according to claim 2, characterized in that, After determining the fault recovery operation information based on the fuel cell stack fault type, the following is also included: Obtain the current number of monitoring cycles for the electrochemical impedance spectroscopy; Based on the current number of monitoring cycles, the operation of synchronously acquiring the current-voltage polarization curve and the electrochemical impedance spectrum at the preset current point of the fuel cell system will be performed again. When the absolute value of the difference between the electrochemical impedance spectrum and the preset electrochemical impedance spectrum is greater than a first preset value, it is determined whether the current monitoring number is less than the preset monitoring number. When the current number of monitoring is less than the preset number of monitoring, the operation of synchronously acquiring the current-voltage polarization curve of the fuel cell system and the electrochemical impedance spectrum at the preset current point is performed again, and the number of monitoring is updated. When the current monitoring count is greater than or equal to the preset monitoring count, the monitoring at the preset current point is stopped, and the monitoring is switched to the next preset current point.

7. The monitoring method for a fuel cell system according to claim 2, characterized in that, Before determining the fuel cell stack fault type based on the electrochemical impedance spectroscopy, the preset electrochemical impedance spectroscopy, the real-time impedance parameters, the preset impedance parameters, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage, the following steps are included: Obtain the current number of monitoring cycles for the current-voltage polarization curve; When the current number of monitoring times meets the preset number of monitoring times, the step of determining the fuel cell stack fault type based on the electrochemical impedance spectrum, the preset electrochemical impedance spectrum, the real-time impedance parameter, the preset impedance parameter, the real-time average single-cell voltage, the real-time minimum single-cell voltage, the preset average single-cell voltage, and the preset minimum single-cell voltage is executed.

8. The monitoring method for a fuel cell system according to claim 1, characterized in that, Determining the real-time fuel cell stack lifetime based on the calibration test parameters, the current-voltage polarization curve, and the preset current-voltage polarization curve includes: The current number of monitoring cycles for the current-voltage polarization curve is obtained based on the calibration test parameters. When the current number of monitoring does not meet the preset number of monitoring, it is determined whether the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value. When the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is less than or equal to the seventh preset value, the monitoring ends. When the absolute value of the difference between the current-voltage polarization curve and the preset current-voltage polarization curve is greater than the seventh preset value, the real-time fuel stack lifetime is determined.

9. The monitoring method for a fuel cell system according to claim 1, characterized in that, Based on the real-time fuel cell stack lifetime, fault location information and early warning information are determined, including: The single lifespan decay is determined based on the real-time fuel cell stack lifespan. Obtain the preset lifespan decay; Monitoring ends when the single lifetime decay is less than the preset lifetime decay. When the single life decay is greater than or equal to the preset life decay, fault location information and early warning information are determined.

10. The monitoring method for a fuel cell system according to claim 8, characterized in that, Based on the first formula, the real-time fuel cell stack lifetime is determined. The first formula satisfies the following: ； Where L is the real-time fuel stack lifetime, and L0 is the baseline lifetime; k i N is the weighting factor for the fault type. i ε represents the number of failures; ε is the natural aging degradation coefficient. Accumulated damage due to faults; t represents natural aging loss; t represents cumulative operating time.

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