Fuel cell monolithic fault tolerance control method and system

Abstract

The invention discloses a fuel cell monolithic fault tolerance control method and system. The method comprises the following steps: acquiring the lowest monolithic voltage of a fuel cell stack in real time; comparing the lowest single-chip voltage with a plurality of different voltage thresholds, and executing corresponding output current control operation; when the lowest single-chip voltage is lower than a third voltage threshold value, entering a dynamic load reduction mode, and executing cyclic load reduction operation; after the dynamic load reduction mode is executed for a preset duration time, if the lowest single-chip voltage is detected to be higher than a fifth voltage threshold value, entering a recovery mode; and if the lowest monolithic voltage is lower than the second voltage threshold value during the recovery period, the recovery is stopped immediately. According to the invention, the system can output stable power to the greatest extent in a fault state, and power oscillation and further damage to a single chip caused by frequent load change are avoided.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a fault-tolerant control method and system for a single fuel cell wafer. Background Technology

[0002] The fuel cell stack is the core component of a fuel cell system, consisting of multiple individual fuel cells connected in series or parallel. Complex electrochemical reactions occur within each individual fuel cell, converting the chemical energy of hydrogen and oxygen into electrical energy. The performance and condition of each individual fuel cell directly affect the output power, efficiency, and stability of the entire fuel cell stack.

[0003] In actual operation, various complex environmental factors can trigger known or unknown abnormal faults, leading to a sharp decline in the performance of a single cell in the fuel cell stack. When used in vehicles, in situations where a clear fault has not been identified or a fault that is difficult to resolve in the short term is encountered, it is essential to ensure that the fuel cell remains in a state of maximum operational capability. Therefore, the challenge lies in how to ensure that the fuel cell system continues to operate even when the performance of a single cell is limited.

[0004] To address the aforementioned technical issues, related technologies typically employ a step-by-step restriction mechanism with different thresholds. For example, when the minimum single-cell performance is below threshold 1, the system's load ramping rate is limited; when it's below threshold 2, the system is prohibited from further loading and maintains its current state; and so on, until the minimum single-cell performance is below threshold 4, at which point the system actively drops the load. While this method can ensure system operation under constrained conditions when fuel cell single-cell performance is abnormal, avoiding system shutdown, the single-cell performance may briefly recover above the judgment threshold due to a decrease in the target current during load reduction or discharge. This causes the system to quickly recover from the constrained state to a normal state. However, since the single-cell problem is not completely resolved, the fault-tolerant strategy is triggered again after recovery. Ultimately, this leads to the system frequently being in a constrained-recovery cycle, resulting in high-frequency load changes, unstable system output power, and further damage to the single cells, creating a vicious cycle. Summary of the Invention

[0005] The purpose of this invention is to propose a fault-tolerant control method and system for a single fuel cell wafer to solve the problems in the prior art.

[0006] Therefore, the present invention provides a fault-tolerant control method for a single fuel cell wafer, comprising: S1, real-time acquisition of the lowest single-cell voltage of the fuel cell stack; S2, compare the lowest single-chip voltage with multiple different voltage thresholds, and perform corresponding output current control operations based on the comparison results; S3, when the lowest single-chip voltage is lower than the third voltage threshold, enter the dynamic load reduction mode and perform cyclic load reduction operation; S4, after the dynamic load reduction mode has been executed for a predetermined duration, if the lowest single-chip voltage is detected to be higher than the fifth voltage threshold, then the recovery mode is entered; wherein, the value of the fifth voltage threshold is between the second voltage threshold that triggers the stop loading and the third voltage threshold that triggers the dynamic load reduction mode; S5, in the recovery mode, if the current output current has reached the loadable current and the minimum single-chip voltage is higher than the second voltage threshold, the loadable current is restored at a controllable rate; if the minimum single-chip voltage is lower than the second voltage threshold during the recovery period, the recovery is stopped immediately; if it is lower than the third voltage threshold, step S3 is executed again until the power is turned off.

[0007] In some embodiments, in step S2, the plurality of different voltage thresholds include a first voltage threshold, a second voltage threshold, a third voltage threshold, and a fourth voltage threshold that decrease sequentially; and The fifth voltage threshold; The fifth voltage threshold is higher than the third voltage threshold but lower than the second voltage threshold.

[0008] In some embodiments, in step S2, if the lowest single-cell voltage is less than a first voltage threshold, the loading rate of the battery system is limited to a preset rate. If the lowest single-cell voltage is less than the second voltage threshold, the battery system stops loading; If the lowest single-cell voltage is less than the fourth voltage threshold, the battery system will be discharged.

[0009] In some embodiments, in step 2, if the lowest single-cell voltage is less than a first voltage threshold, the loading rate of the battery system is limited to a preset rate, the preset rate being 20A / s.

[0010] In some embodiments, the cyclic unloading operation in step S3 includes: Determine the relationship between the current current and the first current threshold. If it is greater than the threshold, the current is reduced by the first gradient value until the preset current threshold is reached. If it is less than, the current is reduced by the second gradient value until the preset current threshold is reached; Wherein, the first gradient value is greater than the second gradient value.

[0011] In some embodiments, the cyclic unloading operation is repeated at a preset period.

[0012] In some embodiments, the preset period is at least 1 second.

[0013] In some embodiments, in step S5, the controllable rate is 5 A / s to 10 A / s.

[0014] In some embodiments, the first voltage threshold, the second voltage threshold, the third voltage threshold, the fourth voltage threshold, the fifth voltage threshold, the first current threshold, and the preset current threshold are all calibrable parameters.

[0015] On the other hand, a fault-tolerant control system for a fuel cell single-cell reactor is also provided, employing the above-mentioned control method, including: The voltage monitoring module is used to obtain the lowest single-cell voltage of the fuel cell stack in real time. The control module is communicatively connected to the voltage monitoring module and is used to compare the lowest single-chip voltage with multiple different voltage thresholds and generate corresponding output current control commands based on the comparison results. The dynamic load reduction module is communicatively connected to the threshold comparison and control module. It is used to enter the dynamic load reduction mode and perform cyclic load reduction operation when the lowest single-cell voltage is lower than the third voltage threshold. The cyclic load reduction operation includes dynamically correcting the loadable current of the battery system based on the current output current. A recovery module, communicatively connected to the dynamic load reduction module and the control module, is used to enter recovery mode after the dynamic load reduction mode has been executed for a predetermined duration, if the lowest single-chip voltage is detected to be higher than a fifth voltage threshold; wherein the value of the fifth voltage threshold is between the second voltage threshold that triggers the load stop and the third voltage threshold that triggers the dynamic load reduction mode; and In the recovery mode, if the current output current has reached the loadable current and the minimum single-chip voltage is higher than the second voltage threshold, the loadable current is controlled to recover at a controllable rate; if the minimum single-chip voltage is detected to be lower than the second voltage threshold during the recovery period, the recovery is stopped immediately; if it is lower than the third voltage threshold, the dynamic load reduction module is triggered to re-execute the cyclic load reduction operation.

[0016] Beneficial effects: This invention introduces a cyclic load reduction operation based on the current output current to dynamically correct the loadable current, on the basis of existing multi-level voltage threshold judgment. After load reduction, a delay time and a higher recovery voltage threshold are set, so that the system can output stable power to the maximum extent under fault conditions, avoiding power oscillation and further damage to individual chips caused by frequent load changes. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0018] Figure 1 The flowchart illustrates the fault-tolerant control method for a single fuel cell wafer provided by this invention. Detailed Implementation

[0019] The invention will be more readily understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the definitions in this specification shall prevail.

[0020] In some embodiments of the present invention, such as Figure 1 As shown, a fault-tolerant control method for a single fuel cell cell includes: S1, real-time acquisition of the lowest single cell voltage of the fuel cell stack; specifically, the voltage of each individual cell is collected by a voltage sensor installed on the fuel cell stack, and the controller's calculation unit finds the cell with the lowest real-time voltage value from all the individual cell voltage values, which is recorded as the lowest single cell voltage.

[0021] S2 compares the lowest single-cell voltage with multiple different voltage thresholds and executes corresponding output current control operations based on the comparison results. Specifically, the multiple voltage thresholds are pre-set voltage values ​​stored in the controller, and they are ordered from high to low as the first voltage threshold, the second voltage threshold, the third voltage threshold, and the fourth voltage threshold. The corresponding output current control operation is as follows: when the lowest single-cell voltage is lower than the first threshold, the current loading rate of the entire fuel cell system is limited, for example, to 20 amperes / second. When the lowest single-cell voltage further decreases to below the second threshold, the system will completely stop the current loading process, i.e., maintain the current output current level. When the lowest single-cell voltage continues to decrease to below the fourth threshold, the system performs a load dump operation, i.e., instructs the output current to rapidly decrease to a very low safety level or zero.

[0022] S3, when the lowest single-chip voltage is lower than the third voltage threshold, enter the dynamic load reduction mode and perform cyclic load reduction operation; specifically, the value of the third voltage threshold is lower than the second threshold but higher than the fourth threshold.

[0023] After entering this mode, the controller periodically performs a load reduction judgment. For example, it first checks whether the current output current of the system is greater than a preset current threshold. If it is greater, the maximum current value that the system can be loaded is set to the current current minus a larger fixed value. If it is less, the loadable current is set to the current current minus a smaller fixed value. This process is repeated cyclically, causing the loadable current to be continuously and gradually reduced until the system shuts down or the recovery condition in step S4 is met.

[0024] This step solves the problem of frequent load changes in existing technologies. By continuously and periodically reducing the load, the system can automatically and gradually find and stabilize at a lower power level that matches the performance of the currently faulty chip. Different load reduction techniques are selected based on the current current magnitude, enabling the system to quickly reduce the load to ensure safety during high-load faults and to smoothly adjust to maintain stable output during low-load faults.

[0025] S4, after the dynamic load reduction mode has been executed for a predetermined duration, such as 30 seconds, if the lowest single-chip voltage is detected to be higher than the fifth voltage threshold, then the system enters the recovery mode. The fifth voltage threshold is between the second voltage threshold that triggers the stop loading and the third voltage threshold that triggers the dynamic load reduction mode. Specifically, the predetermined duration is, for example, 30 seconds. After entering the dynamic load reduction state in step S3, the system must continue operating in this state for at least 30 seconds before determining whether recovery is allowed. The voltage threshold for allowing recovery is the fifth voltage threshold, which is set lower than the second threshold (stop loading line) but higher than the third threshold (start load reduction line). This setting ensures that the single-chip voltage has a sufficient and stable recovery before considering restoring output capability.

[0026] S5. In recovery mode, if the current output current has reached the loadable current and the minimum single-chip voltage is higher than the second voltage threshold, the loadable current is restored at a controllable rate; if the minimum single-chip voltage is lower than the second voltage threshold during the recovery period, the recovery is stopped immediately; if it is lower than the third voltage threshold, step S3 is executed again until the power is turned off.

[0027] Specifically, once recovery is permitted, the recovery process is cautious and controlled. First, the system's current actual output current must have reached the loadable current limited by dynamic load derating, and the lowest single-chip voltage must be stable above the second threshold. At this point, the controller gradually increases the loadable current value at a slow, fixed rate (e.g., 5A / s to 10A / s). If the lowest single-chip voltage drops back below the second threshold during recovery, the recovery process is immediately paused; if it further drops below the third threshold, the controller determines that the fault condition has recurred, immediately exits the recovery mode, and jumps back to step S3 to begin the cyclic load derating operation. Through continuous and slow recovery, while continuously monitoring the lowest single-chip voltage during the recovery process, the recovery process can be immediately paused or reverted to the load derating state if the voltage performance is poor. This ensures that the improvement in system output capability is based on a true and stable improvement in single-chip performance, avoiding secondary faults that may occur during the recovery process.

[0028] In summary, based on the above technical solution, by continuously monitoring the lowest single-chip voltage and comparing it with a set of voltage thresholds set from high to low, a series of progressively escalating control actions are triggered. When the voltage drops to the third voltage threshold, instead of executing a simple one-time command, a periodic cycle is initiated, dynamically lowering the upper limit of the current allowed by the system. Simultaneously, a delay time and stricter voltage conditions are set for recovery from this load reduction state. In this way, after a single-chip failure, the system can automatically find a stable power point and firmly maintain that state until the fault is truly alleviated or the system is shut down. This ensures stable power output to the greatest extent possible while guaranteeing safety and completely avoiding frequent fluctuations in output power.

[0029] In one embodiment, in step S2, the plurality of different voltage thresholds include a first voltage threshold, a second voltage threshold, a third voltage threshold, and a fourth voltage threshold that decrease sequentially; and Fifth voltage threshold; Specifically, the first, second, third, and fourth voltage thresholds are four different levels of values ​​used to determine the severity of the fault and trigger different levels of control actions. Their numerical relationship is: the first voltage threshold is the highest, and the fourth voltage threshold is the lowest, i.e., first voltage threshold > second voltage threshold > third voltage threshold > fourth voltage threshold. The system progressively escalates the control strategy based on the lowest single-chip voltage falling below these thresholds in sequence. The fifth voltage threshold is a specific threshold used to determine whether recovery from the fault handling state is permitted.

[0030] The fifth voltage threshold is higher than the third voltage threshold but lower than the second voltage threshold. This means that the fifth voltage threshold is set within the voltage range between the stop loading line (the second threshold) and the start dynamic load reduction line (the third threshold). Its value is higher than the third threshold that triggers load reduction, but lower than the second threshold that triggers stop loading.

[0031] In one embodiment, in step S2, if the lowest cell voltage is less than a first voltage threshold, the loading rate of the battery system is limited to a preset rate. The loading rate refers to the rate at which the output current or power of the fuel cell system is allowed to increase. When the lowest cell voltage is detected to be below the highest first voltage threshold, it indicates that signs of poor performance are beginning to appear in the stack. At this time, the controller's response is not to immediately stop the power increase, but to allow continued loading, but limit its rate to a lower, gradual preset value, such as 20 A / s. This serves as a reminder to the system to exercise caution when attempting to increase power.

[0032] If the lowest single-cell voltage falls below the second voltage threshold, the battery system stops loading. Specifically, when the voltage drops further below the second threshold, it indicates a more pronounced fault, and attempting to increase power at the current output level may exacerbate the problem. At this point, the controller issues a command to prohibit any further increase in the system's output current or power, freezing it at the currently achieved value. The system output will remain unchanged unless a subsequent step (such as S3) triggers an operation to reduce the output.

[0033] If the lowest cell voltage falls below the fourth voltage threshold, the battery system will perform a load dump. Specifically, when the voltage drops to the lowest fourth threshold, it indicates that the cell performance has deteriorated to a dangerous level, potentially posing a risk of permanent damage (such as reverse polarity or thermal runaway). At this point, the controller executes the most urgent protective operation, load dumping, which instructs the system's output current or power to rapidly and actively decrease to a very low safe level, or even zero, to quickly remove the battery stack from the high-stress, dangerous operating condition.

[0034] In one embodiment, the cyclic unloading operation in step S3 includes: The controller determines the relationship between the current current and a first current threshold. The current current refers to the real-time output current value of the battery system, while the first current threshold is a pre-calibrated current value used to divide different operating ranges. At the beginning of each cycle, such as 1 second, the controller compares the current current value with the first current threshold.

[0035] If the current is greater than the preset current threshold, the current is reduced by the first gradient value until it reaches the preset current threshold. At this point, the system is operating under a relatively high load. The controller then selects a larger current reduction step size, i.e., the first gradient value; for example, reducing the maximum load current by 100 amperes per cycle, continuously performing the load reduction operation. This load reduction process continues until the allowable operating current calculated by the system according to the new rules reaches or falls below another safety lower limit, i.e., the preset current threshold.

[0036] If the current is less than the preset current threshold, the current is reduced by the second gradient value until it reaches the preset current threshold, indicating that the system load is not high. In this case, the controller selects a smaller current reduction step size, i.e., the second gradient value; for example, reducing the maximum load current by 50 amperes in each cycle for a smoother load reduction operation. Similarly, this process continues until the preset current threshold is reached.

[0037] The first gradient value is greater than the second gradient value.

[0038] The system intelligently determines the load reduction mode based on its real-time load status. This allows the system to adopt the most appropriate strategy when facing faults of varying severity and background, enabling rapid recovery in critical situations and a smooth transition in calmer ones. It fundamentally optimizes power control quality under fault conditions, strengthening protection while improving output stability and system availability.

[0039] On the other hand, a fault-tolerant control system for a fuel cell single-cell reactor is also provided, employing the above-mentioned control method, including: The voltage monitoring module is used to obtain the lowest single-cell voltage of the fuel cell stack in real time. The control module, which communicates with the voltage monitoring module, is used to compare the lowest single-chip voltage with multiple different voltage thresholds and generate corresponding output current control commands based on the comparison results. The dynamic load reduction module communicates with the threshold comparison and control module. It is used to enter the dynamic load reduction mode when the lowest single-cell voltage is lower than the third voltage threshold and perform cyclic load reduction operation. The cyclic load reduction operation includes dynamically correcting the loadable current of the battery system based on the current output current. The recovery module, communicatively connected to the dynamic load reduction module and the control module, is used to enter recovery mode after a predetermined duration of dynamic load reduction mode if the lowest single-chip voltage is detected to be higher than a fifth voltage threshold; wherein the value of the fifth voltage threshold is between the second voltage threshold that triggers the load stop and the third voltage threshold that triggers the dynamic load reduction mode; and In recovery mode, if the current output current has reached the loadable current and the minimum single-chip voltage is higher than the second voltage threshold, the loadable current is restored at a controllable rate. If the minimum single-chip voltage is detected to be lower than the second voltage threshold during the recovery period, the recovery is stopped immediately. If it is lower than the third voltage threshold, the dynamic de-load module is triggered to re-execute the cyclic de-load operation.

[0040] This system allows for the introduction of a cyclic load reduction operation based on the current output current, dynamically correcting the loadable current, on top of the existing multi-level voltage threshold judgment. After load reduction, a delay time and a higher recovery voltage threshold are set, enabling the system to output stable power to the maximum extent under fault conditions, thus avoiding power oscillations and further damage to individual chips caused by frequent load changes.

[0041] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fault-tolerant control method for a single fuel cell wafer, characterized in that, include: S1, real-time acquisition of the lowest single-cell voltage of the fuel cell stack; S2, compare the lowest single-chip voltage with multiple different voltage thresholds, and perform corresponding output current control operations based on the comparison results; S3, when the lowest single-chip voltage is lower than the third voltage threshold, enter the dynamic load reduction mode and perform cyclic load reduction operation; S4, after the dynamic load reduction mode has been executed for a predetermined duration, if the lowest single-chip voltage is detected to be higher than the fifth voltage threshold, then the recovery mode is entered; wherein, the value of the fifth voltage threshold is between the second voltage threshold that triggers the stop loading and the third voltage threshold that triggers the dynamic load reduction mode; S5, in the recovery mode, if the current output current has reached the loadable current and the minimum single-chip voltage is higher than the second voltage threshold, the loadable current is restored at a controllable rate; if the minimum single-chip voltage is lower than the second voltage threshold during the recovery period, the recovery is stopped immediately; if it is lower than the third voltage threshold, step S3 is executed again until the power is turned off.

2. The fuel cell single-cell fault-tolerant control method according to claim 1, characterized in that, In step S2, the plurality of different voltage thresholds include a first voltage threshold, a second voltage threshold, a third voltage threshold, and a fourth voltage threshold that decrease sequentially; and The fifth voltage threshold; The fifth voltage threshold is higher than the third voltage threshold but lower than the second voltage threshold.

3. The fuel cell single-cell fault-tolerant control method according to claim 2, characterized in that, In step S2, if the lowest single-cell voltage is less than the first voltage threshold, the loading rate of the battery system is limited to a preset rate. If the lowest single-cell voltage is less than the second voltage threshold, the battery system stops loading; If the lowest single-cell voltage is less than the fourth voltage threshold, the battery system will be discharged.

4. The fuel cell single-cell fault-tolerant control method according to claim 3, characterized in that, In step 2, if the lowest single-cell voltage is less than the first voltage threshold, the loading rate of the battery system is limited to a preset rate, which is 20A / s.

5. The fault-tolerant control method for a single fuel cell wafer according to claim 1, characterized in that, In step S3, the cyclic unloading operation includes: Determine the relationship between the current current and the first current threshold. If it is greater than the threshold, the current is reduced by the first gradient value until the preset current threshold is reached. If it is less than, the current is reduced by the second gradient value until the preset current threshold is reached; Wherein, the first gradient value is greater than the second gradient value.

6. The fuel cell single-cell fault-tolerant control method according to claim 5, characterized in that, The cyclic unloading operation is repeated at a preset period.

7. The fuel cell single-cell fault-tolerant control method according to claim 6, characterized in that, The preset period is at least 1 second.

8. The fuel cell single-cell fault-tolerant control method according to claim 1, characterized in that, In step S5, the controllable rate is from 5 A / s to 10 A / s.

9. The fuel cell single-cell fault-tolerant control method according to claim 5, characterized in that, The first voltage threshold, the second voltage threshold, the third voltage threshold, the fourth voltage threshold, the fifth voltage threshold, the first current threshold, and the preset current threshold are all calibrable parameters.

10. A fault-tolerant control system for a single fuel cell wafer, characterized in that, The control method according to any one of claims 1-9 includes: The voltage monitoring module is used to obtain the lowest single-cell voltage of the fuel cell stack in real time. The control module is communicatively connected to the voltage monitoring module and is used to compare the lowest single-chip voltage with multiple different voltage thresholds and generate corresponding output current control commands based on the comparison results. The dynamic load reduction module is communicatively connected to the threshold comparison and control module. It is used to enter the dynamic load reduction mode and perform cyclic load reduction operation when the lowest single-cell voltage is lower than the third voltage threshold. The cyclic load reduction operation includes dynamically correcting the loadable current of the battery system based on the current output current. A recovery module, communicatively connected to the dynamic load reduction module and the control module, is used to enter recovery mode after the dynamic load reduction mode has been executed for a predetermined duration, if the lowest single-chip voltage is detected to be higher than a fifth voltage threshold; wherein the value of the fifth voltage threshold is between the second voltage threshold that triggers the load stop and the third voltage threshold that triggers the dynamic load reduction mode; and In the recovery mode, if the current output current has reached the loadable current and the minimum single-chip voltage is higher than the second voltage threshold, the loadable current is controlled to recover at a controllable rate; if the minimum single-chip voltage is detected to be lower than the second voltage threshold during the recovery period, the recovery is stopped immediately; if it is lower than the third voltage threshold, the dynamic load reduction module is triggered to re-execute the cyclic load reduction operation.

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