An on-line purging method and system for fuel cells during rated operation

Abstract

The application discloses an online purging method and system during rated operation of a fuel cell, and the method comprises the following steps: obtaining drainage capacity data and electrochemical performance parameters of a water separator in a stack exhaust path; comprehensively judging the change amount of the drainage capacity relative to a preset reference and the fluctuation of the electrochemical parameters; when both of them exceed a threshold value, judging water flooding and triggering purging, otherwise, judging environmental interference; executing an intelligent online purging program to remove accumulated water; judging whether the purging is successful according to the voltage recovery and the drainage capacity regression after the purging, and executing power reduction protection when the purging is not successful. The application takes the drainage capacity as a direct indicator of water content, combines the electrochemical parameters to realize accurate judgment, effectively distinguishes water flooding from environmental interference, adopts on-demand purging and self-adaptive termination strategies to avoid membrane dryness and energy waste, has an online learning correction function and an effect verification mechanism to ensure long-term stable operation of the system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell control technology, and in particular to a method and system for preventing flooding by performing online purging based on drainage monitoring under the rated power operating conditions of a fuel cell. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs), as efficient and clean electrochemical energy conversion devices, are highly dependent on hydrothermal management for performance. During fuel cell operation, especially under rated power or high load conditions, the electrochemical reaction rate is rapid, significantly increasing the rate of water generation. If the water generated inside the stack cannot be drained in time, it can clog the pores of the gas diffusion layer (GDL) and catalyst layer (CL), resulting in a "flooding" phenomenon. Flooding not only hinders the transport of reactant gases (hydrogen and oxygen) to the catalytic active sites, increasing concentration polarization losses and causing voltage drops and power fluctuations, but in severe cases, it can even lead to physical damage to the membrane electrode assembly and bipolar plates, significantly impacting the dynamic response and lifespan of the fuel cell system.

[0003] Existing fuel cell water management strategies mostly focus on shutdown purging or low-load drainage. Shutdown purging is primarily used to prevent icing damage during cold starts at low temperatures, but it cannot address the dynamic flooding problem during operation. Traditional in-operation drainage often relies on fixed purging cycles or simple threshold judgments (such as based solely on voltage drop), lacking accurate perception of the actual water content inside the stack. Especially during continuous operation at rated power, due to the large and frequent fluctuations in water production, fixed drainage strategies are often either lagging or excessive: untimely drainage can lead to severe flooding, affecting output efficiency; while indiscriminate and frequent purging consumes parasitic power, reduces the system's net output efficiency, and may remove too much bound water from the membrane, leading to membrane drying.

[0004] Existing monitoring methods are insufficient to directly quantify the degree of liquid water accumulation inside the fuel cell stack. While voltage fluctuations can be monitored indirectly, these fluctuations are affected by various factors, resulting in a high false alarm rate. Accurately identifying flooding trends under rated operating conditions and implementing intelligent and efficient online purging without interrupting the fuel cell's normal power supply is a pressing technical challenge in the engineering application of current fuel cell systems. Summary of the Invention

[0005] This invention addresses the performance degradation and unplanned downtime issues caused by large water production and inaccurate flood monitoring in existing fuel cells during rated power operation. It provides an online purging method and system for fuel cells during rated operation, enabling intelligent sensing and active removal of liquid water inside the fuel cell stack without shutting down the system.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide an online purging method for a fuel cell during rated operation, comprising the following steps:

[0007] S1: Obtain the water discharge data of the gas-water separator set in the exhaust path of the fuel cell stack per unit time, as well as the electrochemical performance parameters of the stack.

[0008] S2: Based on the pre-established current operating condition drainage benchmark and electrochemical parameter benchmark, comprehensively determine whether liquid water accumulation occurs inside the fuel cell stack;

[0009] Specifically, when the change in the discharge volume data relative to the discharge volume benchmark exceeds a first threshold, and the fluctuation of the electrochemical performance parameters relative to the electrochemical parameter benchmark exceeds a second threshold, liquid water accumulation is determined to have occurred, and a purging request is triggered; when the change in the discharge volume data exceeds the first threshold but the electrochemical performance parameters do not exceed the second threshold, it is determined to be due to environmental interference, and a purging request is not triggered.

[0010] S3: In response to the purging request, execute the intelligent online purging procedure to remove the accumulated liquid water;

[0011] S4: After purging is completed, restore the power request of the fuel cell stack, and determine whether the purging was successful based on the voltage and drainage volume of the fuel cell stack.

[0012] If the voltage of the fuel cell stack recovers to the expected range and the drainage volume returns to the reference range, the purging is considered successful and the system returns to normal operation.

[0013] If the voltage of the fuel cell stack does not recover to the expected range or the drainage volume remains abnormal, the purging is deemed a failure, and a power reduction protection strategy is executed.

[0014] In a preferred embodiment of the present invention, the electrochemical performance parameters in S2 include at least one of the following: total stack voltage V_stack, individual cell voltage V_cell, output current I, and calculated power P. These parameters can sensitively reflect the non-uniformity of electrochemical reactions caused by flooding, complementing the drainage data and improving the reliability of the judgment.

[0015] In a preferred embodiment of the present invention, the first threshold and the second threshold in S2 are dynamically adjusted according to the displacement reference and / or the electrochemical parameter reference; the displacement reference and the electrochemical parameter reference are established in the following manner:

[0016] In the initial stage of commissioning of the new fuel cell stack, under different ambient temperature and humidity conditions, the discharge volume data and electrochemical performance parameters were recorded during stable operation under different load conditions, forming a MAP diagram of the "current-voltage-power-discharge volume" correspondence under different current densities. The discharge volume benchmark and electrochemical parameter benchmark provide accurate reference standards for subsequent judgments, and can adaptively adjust the threshold according to the operating conditions to avoid misjudgments caused by fixed thresholds.

[0017] In a preferred embodiment of the present invention, the comprehensive judgment in S2 further includes a multi-parameter fusion judgment step:

[0018] If the change in the discharge volume data exceeds a first threshold, and if an abnormal increase in the temperature of the discharge from the fuel cell stack outlet is detected, the priority of purging triggering is further increased. Similarly, if an abnormal discharge volume is detected along with an abnormal increase in the exhaust temperature at the fuel cell stack outlet, the priority of purging triggering is further increased. This temperature-assisted criterion can effectively distinguish between "normal high-load water production" and "abnormal flooding," and is particularly suitable for high-power-density scenarios.

[0019] In a preferred embodiment of the present invention, the intelligent online purging program in S3 includes:

[0020] Cathode pulse purging: By adjusting the cathode air supply parameters, the inlet air flow rate and / or pressure are increased in a pulsed or short-duration high-flow manner, discharging liquid water in the flow channel and gas diffusion layer through the air-water separator. Typical parameters are an air flow rate increased to 1.5 to 2 times the rated flow rate, lasting 5 to 60 seconds. This method ensures effective drainage while avoiding the risk of membrane drying caused by prolonged high flow rates.

[0021] Anode-coordinated purging: The anode circulation pump or hydrogen injector is activated simultaneously to assist in the drainage of water accumulated on the anode side. This method solves the problem that water flooding on the anode side is difficult to remove through cathode purging, achieving joint drainage of both anode and cathode.

[0022] In a preferred embodiment of the present invention, to avoid over- or under-purging, an adaptive termination method based on cumulative drainage volume is adopted: the instantaneous drainage flow rate of the steam-water separator is integrated to calculate the total drainage volume during the purging process; when the cumulative drainage volume reaches a target drainage volume threshold associated with the voltage deficit value before purging, purging is automatically terminated and normal gas supply is restored. This method achieves "on-demand purging," extending the purging process when there is excessive water accumulation and ending it earlier when there is insufficient water accumulation, minimizing the impact on fuel cell stack humidity and energy consumption.

[0023] In a preferred embodiment of the present invention, the power reduction protection strategy in S4 includes: limiting the maximum output power of the fuel cell stack to a preset percentage of the rated power and sending a maintenance alarm to the user terminal. If purging fails, the power reduction protection strategy is executed: limiting the maximum output power of the fuel cell stack to a preset percentage of the rated power (e.g., 80%) and sending a maintenance alarm to the user terminal. This strategy prevents irreversible damage caused by flooding, while ensuring that the system can continue to operate at limited power, avoiding safety risks caused by sudden shutdown.

[0024] In a preferred embodiment of the present invention, the displacement benchmark and / or electrochemical parameter benchmark have an online learning and correction function, specifically including:

[0025] The controller fine-tunes the baseline curve based on long-term operating data. For example, if it finds that the drainage volume is consistently low at the same current but the voltage is normal, it automatically lowers the drainage volume threshold at that current point to adapt to the drift in water production characteristics caused by fuel cell aging. This function ensures the accuracy of the model's judgment throughout its entire life cycle and avoids misjudgments caused by model fixation.

[0026] Another technical solution adopted by the present invention is: providing a fuel cell system, comprising:

[0027] A fuel cell stack is used to generate electrical energy through electrochemical reactions.

[0028] A vapor-water separator is connected in series in the cathode or anode exhaust pipe of the fuel cell stack to separate and collect liquid water in the exhaust. The vapor-water separator is equipped with a liquid level sensor or a weight sensor to measure the amount of water discharged in real time.

[0029] The data acquisition unit includes a voltage acquisition module, a current acquisition module, and a discharge volume sensor, which are used to acquire the electrochemical performance parameters and discharge volume data of the fuel cell stack in real time.

[0030] The controller is communicatively connected to both the data acquisition unit and the air compressor. The controller stores an intelligent online purging program module, which is configured to execute any of the online purging methods described above. This system integrates drainage volume sensing, electrochemical monitoring, and control decision-making, achieving closed-loop automated management from state perception to intelligent response.

[0031] The beneficial effects of this invention are: this invention breaks through the limitations of traditional shutdown purging, and can remove accumulated liquid in real time during rated power operation, avoiding unplanned shutdowns caused by flooding, and is particularly suitable for scenarios with high requirements for continuous power supply;

[0032] This invention introduces drainage volume as a direct criterion and combines it with electrochemical signals for dual verification, effectively solving the problem of misjudgment caused by load disturbances in single voltage monitoring.

[0033] This invention reduces prolonged immersion of the catalyst layer in liquid water by timely online purging, thus mitigating carbon support corrosion and catalyst loss; at the same time, it avoids the risk of membrane drying caused by excessive purging and maintains optimal hydrothermal balance.

[0034] This invention has a post-purging effect verification mechanism that can identify serious faults and issue timely alarms, preventing the faults from escalating and improving the system's operation and maintenance efficiency.

[0035] The baseline model of this invention has an online learning and correction function, which can adapt to the characteristic drift caused by the aging of the fuel cell stack and ensure the accuracy of long-term operation judgment. Attached Figure Description

[0036] 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 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, wherein:

[0037] Figure 1 This is a schematic diagram of the fuel cell system in an embodiment of the present invention;

[0038] Figure 2 This is a schematic flowchart of the online purging method for fuel cells during rated operation in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0042] In the description of this invention, it should be noted that the terms "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] Example 1: As Figure 1 As shown, a fuel cell system is provided, including a fuel cell stack 1, an air system, a hydrogen system, a vapor-water separator 3, a data acquisition unit 4, and a controller 5. The air system provides filtered, pressurized, and humidified oxidant to the stack cathode; the hydrogen system provides regulated reductant to the stack anode; the vapor-water separator 3 separates and measures liquid water in the exhaust gas; the data acquisition unit 4 collects electrochemical performance parameters and wastewater volume data; and the controller 5 coordinates the various components and executes an intelligent online purging program.

[0046] Fuel cell stack 1: Used for electrochemical reactions to generate electricity. The stack consists of multiple individual cells connected in series, each individual cell including a membrane electrode assembly (MEA) and bipolar plates. The cathode inlet of the stack is connected to the outlet of the air system, the anode inlet is connected to the outlet of the hydrogen system, and the cathode exhaust port is connected to the inlet of the gas-water separator 3. The power output terminal of the fuel cell stack 1 is connected to a DC / DC converter, a battery, and a load 2.

[0047] The DC / DC converter is used to achieve voltage conversion and power matching. The battery is used for auxiliary power supply during system start-up and shutdown and power buffering under dynamic operating conditions. The load 2 is used to consume the electrical energy output by the fuel cell stack and provide a current discharge channel required for the reaction. During the purging procedure, the controller 5 adjusts the power of the load 2 and the DC / DC output to coordinate the control of the fuel cell stack's output current, assisting in the power distribution during the purging process.

[0048] Air System: Outside air is filtered by an air filter and then compressed and pressurized by air compressor 6. The pressurized air enters humidifier 8 for humidification. The humidified air then enters the cathode inlet of fuel cell stack 1 to participate in the electrochemical reaction. The cathode exhaust gas produced after the electrochemical reaction is discharged from the cathode outlet and enters steam-water separator 3. Back pressure valve 7 is installed in the cathode exhaust pipe (located upstream or downstream of steam-water separator 3). By adjusting the opening of back pressure valve 7 in coordination with the speed of air compressor 6, the cathode intake air flow and pressure are jointly regulated. Both air compressor 6 and back pressure valve 7 are communicatively connected to controller 5. In purging mode, controller 5 increases the cathode intake air flow and / or pressure instantaneously by increasing the speed of air compressor 6 and / or adjusting the opening of back pressure valve 7. The humidifier is located between air compressor 6 and the cathode inlet of fuel cell stack 1 to humidify the intake air to maintain the water and heat balance inside the fuel cell stack. Its humidification amount is uniformly adjusted by controller 5 according to operating conditions.

[0049] Hydrogen System: Hydrogen gas from the hydrogen source is depressurized by pressure reducing valve 11 and then metered by hydrogen injector 10 before entering the anode inlet of fuel cell stack 1 to participate in the electrochemical reaction. Unreacted hydrogen gas and gases such as nitrogen permeating from the cathode side are discharged from the anode outlet. In systems equipped with a hydrogen circulation loop, the exhaust gas from the anode outlet is driven by anode circulation pump 9 and mixed with fresh hydrogen before circulating back to the anode inlet to improve hydrogen utilization. Both anode circulation pump 9 and hydrogen injector 10 are communicatively connected to controller 5. In anode co-purging mode, controller 5 can briefly activate anode circulation pump 9 or hydrogen injector 10 to assist in draining water accumulated on the anode side.

[0050] Steam-water separator 3: Connected in series in the cathode exhaust port pipeline of fuel cell stack 1. In systems with an anode circulation loop, the steam-water separator can also be connected in series in the anode exhaust port pipeline. The steam-water separator 3 employs a centrifugal or impact separation structure to efficiently separate and collect liquid water from the exhaust gas into the bottom water storage chamber. The separated gas is discharged from the top. The bottom water storage chamber is equipped with a level sensor or a weight sensor, which is electrically connected to the data acquisition unit 4 for real-time measurement and output of the discharged water volume.

[0051] It should be noted that when flooding occurs, the drainage volume on the cathode side increases and the drainage volume on the anode side decreases, and the two trends are opposite. Therefore, when the steam-water separator 3 is installed in the cathode or anode exhaust pipe, its drainage characteristics and control strategies are different. The following explanation will take the installation in the cathode exhaust pipe as an example.

[0052] Data acquisition unit 4 includes a voltage acquisition module, a current acquisition module, and a discharge volume sensor. The voltage acquisition module is electrically connected to each cell of the fuel cell stack 1 to acquire the total stack voltage V_stack and the voltage of each cell V_cell. The current acquisition module is electrically connected to the output terminal of the fuel cell stack 1 to acquire the output current I. The discharge volume sensor is electrically connected to a level sensor or a weight sensor to acquire the change in discharge volume ΔW of the steam-water separator 3 within a unit time Δt. Data acquisition unit 4 is communicatively connected to the controller 5, transmitting the acquired parameters to the controller in real time. The acquisition frequency is set to 10Hz-100Hz to capture rapid water management dynamics.

[0053] Controller 5: Communicates with data acquisition unit 4, air compressor 6, back pressure valve 7, anode circulation pump 9, and hydrogen injector 10 respectively, and is used to coordinate and control the various actuators. Controller 5 has built-in storage of drainage volume reference and electrochemical parameter reference, which are pre-stored in the form of a MAP diagram showing the correspondence between "current-voltage-power-drainage volume", and also stores an intelligent online purging program.

[0054] Example 2: Provides an online purging method for a fuel cell during rated operation, configured with the intelligent online purging program module described in Example 1. Its core is to use a gas-water separator installed at the stack outlet (cathode or anode, preferably cathode) as a "water content sensor" to infer the accumulation of liquid water inside the stack by monitoring the dynamic changes in the amount of water discharged.

[0055] like Figure 2 As shown, the specific control steps are as follows:

[0056] S1: When the fuel cell is operating at rated power or high load, such as load rate >80%, the controller collects the following parameters in real time:

[0057] (a) Total stack voltage V_stack and single cell voltage V_cell;

[0058] (b) Output current I and calculated power P;

[0059] (c) The change in drainage volume of the steam-water separator within a unit time Δt, ΔW.

[0060] S2: The controller compares the real-time collected data with the pre-stored parameter benchmarks. The parameter benchmarks include the current operating condition's drainage volume benchmark and electrochemical parameter benchmark, which are stored in a pre-set "current-voltage-power-drainage volume" mapping diagram within the controller. This mapping diagram is established by recording drainage volume data and electrochemical performance parameters during stable operation under different ambient temperatures, humidity, and load conditions, and describes the drainage volume range and corresponding electrochemical parameter range that should exist under normal hydrothermal equilibrium at the current current density.

[0061] The judgment logic is as follows:

[0062] Discharge abrupt change detection: If the change in discharge ΔW per unit time relative to the discharge benchmark exceeds the first threshold (e.g., 20% of the discharge benchmark value), and is accompanied by high-frequency fluctuations in the stack voltage V_stack or a deterioration in the consistency of single cell voltage (increased voltage difference, i.e., the fluctuation of electrochemical performance parameters relative to the electrochemical parameter benchmark exceeds the second threshold, e.g., the difference between the highest and lowest voltage of a single cell exceeds 50mV), then it is determined that liquid water has accumulated inside the stack (a precursor to flooding).

[0063] Excluding interference: If the change in the discharge volume data relative to the discharge volume benchmark exceeds the first threshold, but the fluctuation of the electrochemical performance parameters relative to the electrochemical parameter benchmark does not exceed the second threshold, it is determined to be an environmental factor interference (such as changes in ambient humidity) and purging is not triggered; only when "abnormal discharge volume" and "electrochemical performance fluctuation" occur simultaneously is it confirmed as a flooding state that requires intervention.

[0064] Specifically, when the change in discharge volume data relative to the discharge volume baseline exceeds a first threshold (e.g., 20% of the baseline value), and the fluctuation of electrochemical performance parameters relative to the electrochemical parameter baseline exceeds a second threshold (e.g., the difference between the highest and lowest voltage of a single cell exceeds 50mV), liquid water accumulation is determined to have occurred, triggering a purging request. When the change in discharge volume data exceeds the first threshold but the electrochemical performance parameters do not exceed the second threshold, it is determined to be due to environmental interference (e.g., changes in ambient humidity), and a purging request is not triggered.

[0065] S3: Once a flooded state is detected, the controller immediately initiates an intelligent online purging program. The purging strategy may include:

[0066] Pulse purging: By adjusting the air compressor speed or the back pressure valve opening, the cathode inlet air flow and / or pressure are instantly increased to purge the fuel cell stack in a pulse manner. During purging, the air flow is increased to 1.5 to 2 times the rated flow, and the purging duration is 5 to 60 seconds.

[0067] Variable load purging: While maintaining the total output power, the current command is finely adjusted to use the pressure pulsation generated by the current fluctuation to assist in drainage.

[0068] Anode-assisted purging: If the system configuration allows, the anode circulation pump or hydrogen injector can be activated briefly to assist in the discharge of water accumulated on the anode side.

[0069] S4: After purging, the controller resumes the rated power request and monitors the stack voltage and drainage response.

[0070] If recovery is successful: This indicates that the flooding has been relieved, the system continues to operate normally, and the process ends. The specific criteria for judgment are: the voltage of the fuel cell stack returns to the expected range and the drainage volume returns to the baseline range.

[0071] If recovery fails, it indicates that there may be irreversible water blockage, membrane electrode damage, or other faults inside the fuel cell stack. In this case, the controller forces the fuel cell stack into a power reduction protection mode (e.g., limiting the maximum power output to 80% of the rated value) and sends a "maintenance alarm" to the user terminal, prompting them to check the health status of the fuel cell stack or replace components.

[0072] Example 3: To improve the accuracy of the judgment, this example adds an online learning and correction function for the displacement benchmark and / or electrochemical parameter benchmark based on Example 2.

[0073] Initial calibration: In the early stages of commissioning the new fuel cell stack, an initial "current-discharge" mapping curve was established through long-term operation under different operating conditions. Specifically, variable humidity experiments were conducted under different ambient temperatures, humidity, and load conditions. The discharge benchmark during stable operation under different back pressures and humidification conditions was recorded, forming a "current-voltage-power-discharge" mapping diagram under different current densities, which was then stored in the controller.

[0074] Aging Compensation: As the fuel cell stack operates for longer periods, the aging of the membrane electrode assembly (MEA) can alter the water production characteristics. The controller periodically (e.g., every 500 hours of operation or after accumulating a certain mileage) fine-tunes the baseline curve based on actual operating data. For example, if the discharge rate is consistently low at the same current while the voltage is normal, the discharge rate threshold for that current point is automatically lowered to avoid misjudgments caused by model lag.

[0075] Example 4: In addition to drainage volume and voltage, this example also introduces temperature parameters as an auxiliary basis for judgment.

[0076] In S2, if an increase in drainage is detected and the stack outlet temperature rises abnormally (indicating that internal heat dissipation is blocked, possibly due to flooding causing a reduction in reaction area and local overheating), the priority of purging triggering is further increased.

[0077] This multi-parameter fusion mechanism can effectively distinguish between "normal high-load water production" and "abnormal flooding," further reducing the false alarm rate.

[0078] Example 5: Based on Example 2, this example further optimizes the termination conditions for purging. Traditional purging often has a fixed duration, which can easily lead to insufficient purging or membrane drying. This method uses the cumulative drainage volume of the steam-water separator as the criterion for the purging endpoint.

[0079] Process description: When S2 triggers the purging process, the controller starts to integrate the instantaneous drainage flow rate of the steam-water separator and calculates the total drainage volume W_total during the purging process.

[0080] Dynamic termination: Set a target discharge threshold W_target (this threshold is proportional to the voltage deficit before purging, for example...) Where k is an adjustable coefficient, and ΔV is the decrease in stack voltage relative to the reference voltage before triggering purge. When the real-time integration yields... If this occurs, immediately stop high-flow purging and restore normal gas supply.

[0081] This method achieves "on-demand purging." If there is a lot of water inside the fuel cell stack, the purging time is automatically extended; if there is little water, the purging ends quickly. This ensures effective drainage while minimizing the power consumption of the air compressor and the negative impact on the humidity of the proton exchange membrane.

[0082] The online purging method of this invention uses the physically separated drainage volume as a direct indicator, combined with electrochemical parameters, to more accurately reflect the water content state inside the fuel cell stack than relying solely on voltage monitoring, thus reducing misjudgments.

[0083] The online purging method of this invention has an online maintenance function, realizing "non-stop" drainage under rated power, avoiding forced shutdown or power limitation caused by flooding, and ensuring the power continuity of vehicles or equipment.

[0084] The online purging method during the rated operation of the fuel cell using the present invention promptly removes accumulated water, reducing the risk of immersion corrosion of the catalyst layer by liquid water. It also avoids membrane drying problems caused by blind purging, which helps to extend the service life of the fuel cell stack.

[0085] The online purging method of this invention has an online learning and correction function, strong adaptability, and can adapt to the characteristic drift caused by fuel cell aging, ensuring the accuracy of judgment in long-term operation.

[0086] The online purging method of this invention has a post-purging effect verification mechanism, which can identify serious faults and issue timely alarms to prevent the faults from escalating. Intelligent maintenance improves the system's operation and maintenance efficiency.

[0087] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An online purging method for a fuel cell during rated operation, characterized in that, Includes the following steps: S1: Obtain the water discharge data of the gas-water separator set in the exhaust path of the fuel cell stack per unit time, as well as the electrochemical performance parameters of the stack. S2: Based on the pre-established current operating condition drainage benchmark and electrochemical parameter benchmark, comprehensively determine whether liquid water accumulation occurs inside the fuel cell stack; Specifically, when the change in the discharge volume data relative to the preset discharge volume benchmark exceeds a first threshold, and the fluctuation of the electrochemical performance parameters relative to the electrochemical parameter benchmark exceeds a second threshold, liquid water accumulation is determined to have occurred, and a purging request is triggered; when the change in the discharge volume data exceeds the first threshold but the electrochemical performance parameters do not exceed the second threshold, it is determined to be due to environmental interference, and a purging request is not triggered. S3: In response to the purging request, execute the intelligent online purging procedure to remove the accumulated liquid water; S4: After purging is completed, restore the power request of the fuel cell stack, and determine whether the purging was successful based on the voltage and drainage volume of the fuel cell stack. If the voltage of the fuel cell stack recovers to the expected range and the drainage volume returns to the reference range, the purging is considered successful and the system returns to normal operation. If the voltage of the fuel cell stack does not recover to the expected range or the drainage volume remains abnormal, the purging is deemed a failure, and a power reduction protection strategy is executed.

2. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, The electrochemical performance parameters described in S2 include at least one of the following: total stack voltage V_stack, individual cell voltage V_cell, output current I, and calculated power P.

3. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, In S2, the first threshold and the second threshold are dynamically adjusted based on the displacement reference and / or the electrochemical parameter reference; the displacement reference and the electrochemical parameter reference are established in the following manner: In the initial stage of commissioning of the new fuel cell stack, under different ambient temperature and humidity conditions, the water discharge data and electrochemical performance parameters were recorded during stable operation under different load conditions, forming a MAP diagram of the "current-voltage-power-water discharge" relationship under different current densities.

4. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, The comprehensive judgment described in S2 also includes a multi-parameter fusion judgment step: If the change in the discharge volume data exceeds the first threshold, and if an abnormal increase in the temperature of the discharge from the fuel cell stack outlet is detected, the priority of purging triggering is further increased.

5. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, The intelligent online purging procedure described in S3 includes: increasing the intake air flow and / or pressure on the cathode side by adjusting the cathode gas supply parameters in a pulsed or short-duration high-flow manner to purge the fuel cell stack, and discharging the liquid water accumulated in the flow channel and gas diffusion layer through a gas-water separator; during purging, the air flow is increased to 1.5 to 2 times the rated flow, and the purging duration is 5 to 60 seconds.

6. The online purging method for fuel cells during rated operation according to claim 5, characterized in that, The intelligent online purging procedure described in S3 also includes: simultaneously activating the anode circulation pump or hydrogen injector to assist in draining the water accumulated on the anode side.

7. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, The intelligent online purging program described in S3 adopts an adaptive termination method based on cumulative drainage volume, which includes: integrating the instantaneous drainage flow rate of the gas-water separator to calculate the cumulative drainage volume during the purging process; when the cumulative drainage volume reaches the target drainage volume threshold associated with the voltage loss value of the fuel cell stack before purging, purging is terminated and normal gas supply is restored.

8. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, The power reduction protection strategy described in S4 includes: limiting the maximum output power of the fuel cell stack to a preset percentage of the rated power and sending a maintenance alarm to the user terminal.

9. The online purging method for fuel cells during rated operation according to claim 1, characterized in that, The aforementioned discharge capacity benchmark and / or electrochemical parameter benchmark have online learning and correction functions, specifically including: During long-term system operation, the controller fine-tunes the baseline curve based on actual operating data; If the discharge rate is consistently low under the same current but the voltage is normal, the discharge rate threshold at that current point will be automatically lowered to adapt to the drift in water production characteristics caused by fuel cell aging.

10. A fuel cell system, characterized in that, include: A fuel cell stack is used to generate electrical energy through electrochemical reactions. A vapor-water separator is connected in series in the cathode or anode exhaust pipe of the fuel cell stack to separate and collect liquid water in the exhaust. The vapor-water separator is equipped with a liquid level sensor or a weight sensor to measure the amount of water discharged in real time. The data acquisition unit includes a voltage acquisition module, a current acquisition module, and a discharge volume sensor, which are used to acquire the electrochemical performance parameters and discharge volume data of the fuel cell stack in real time. The controller is communicatively connected to the data acquisition unit and the air compressor, respectively. The controller stores an intelligent online purging program module, which is configured to execute the online purging method as described in any one of claims 1 to 9.

Images