A fuel cell on-load purge method based on current distribution optimization

Abstract

A fuel cell load purging method based on current distribution optimization relates to the technical field of fuel cell start-stop strategy, with the purpose of more accurately determining the load purging time during the fuel cell shutdown process, and discharging the residual moisture in the fuel cell stack as much as possible in a shorter time, while alleviating battery attenuation. The technical key points are that the fuel cell stack is set to an idle state, a certain amount of reaction gas is supplied to the fuel cell stack, and the fuel cell stack is purged under load by controlling the purge conditions; wherein the purge conditions include at least one of the fuel cell operating temperature range, gas flow range, gas temperature range, gas humidity range, and intake pressure range. The present invention develops a fuel cell load purging strategy from the perspective of current distribution, which makes up for the current deficiency of relying solely on high-frequency resistance as the basis for judgment, and the current distribution information can provide assistance for a deeper understanding of the fuel cell load purging process, which helps to alleviate the attenuation of the fuel cell stack.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell start-stop strategies, and in particular to a fuel cell on-load purge method based on current distribution optimization. Background Art

[0002] A fuel cell is a power generation device that converts the chemical energy of a fuel and an oxidant directly into electrical energy through an electrochemical reaction. It boasts high energy conversion efficiency, zero pollution, and low noise. With the advancement of its commercialization, the market has placed higher demands on fuel cell output power, leading to the development of fuel cells with large active areas. However, fuel cells involve multiple physical fields, including water, gas, heat, electricity, and force. These fields work together to determine the cell's power generation performance. However, these fields are often difficult to distribute evenly, especially within a larger active area, making it more likely to cause uneven degradation in different regions within the stack. Furthermore, the start-up and shutdown processes of fuel cells are prone to phenomena such as hydrogen-air interfaces, high cathode potentials, and reactant gas starvation, which accelerate stack degradation. To address these issues, research on fuel cell start-up and shutdown strategies based on current distribution optimization has become an important technical approach to mitigate battery degradation.

[0003] During the shutdown process of the fuel cell stack, the moisture generated in the fuel cell stack needs to be discharged from the fuel cell stack to avoid corrosion, freezing and other phenomena of the bipolar plates and membrane electrodes due to residual water, which leads to fuel cell stack degradation. The usual practice is to use reaction gas or other inert gas to directly purge the residual moisture in the fuel cell stack. In order to reduce the cathode potential during the water purge process, the purge is usually performed at a lower current density or idle state. This can discharge the excess moisture in the fuel cell stack and avoid high potential, which helps to alleviate the degradation of the fuel cell stack. During the on-load purge process, the purge effect is usually judged based on the detection of high-frequency impedance. However, this method cannot reflect the distribution of current inside the fuel cell stack. An inappropriate on-load purge strategy will lead to a very uneven current distribution, which will have an adverse effect on the durability of the fuel cell stack. Summary of the Invention

[0004] In order to solve the above problems, the stack can maintain a suitable current distribution state during the loaded purge process, so as to achieve the purpose of alleviating the attenuation of the stack.

[0005] According to some embodiments of the present application, a fuel cell on-load purge method based on current distribution optimization is used for fuel cell shutdown, and the method includes:

[0006] The stack is set to idle state, a certain amount of reactant gas is supplied to the stack, and the stack is purged under load by controlling the purge conditions;

[0007] Stop gas supply based on the current distribution inside the fuel cell stack;

[0008] Reduce the output current of the battery stack to zero;

[0009] The purge conditions include at least one of the stack operating temperature range, gas flow rate range, gas temperature range, gas humidity range, and intake pressure range.

[0010] According to the fuel cell on-load purging method based on current distribution optimization in some embodiments of the present application, the operating temperature range of the fuel cell stack is 30°C~90°C.

[0011] According to the fuel cell load purge method based on current distribution optimization in some embodiments of the present application, the gas flow rate range is a current density of 200~2000 mA cm -2 The corresponding gas volume.

[0012] According to the fuel cell on-load purge method based on current distribution optimization in some embodiments of the present application, the gas temperature range is 30°C to 90°C.

[0013] According to the fuel cell on-load purge method based on current distribution optimization in some embodiments of the present application, the gas humidity range is 0~100%RH.

[0014] According to the fuel cell on-load purge method based on current distribution optimization in some embodiments of the present application, the intake pressure range is 0~150 kPa.

[0015] According to the fuel cell on-load purge method based on current distribution optimization in some embodiments of the present application, the purge condition includes a first purge condition and a second purge condition, the first purge condition is implemented in the first purge stage, and the second purge condition is implemented in the second purge stage;

[0016] The first purge condition includes a stack operating temperature of 55°C and a gas flow rate of 1000 mAcm -2 The corresponding gas volume, gas humidity is 30% RH, inlet pressure is 15 kPa, and the purge duration is 120 s;

[0017] The second purge condition includes a stack operating temperature of 55°C and a gas flow rate of 500 mA cm -2 The corresponding gas volume, gas humidity is dry gas, inlet pressure is 15kPa, and the loaded purge lasts for 30 s.

[0018] According to the fuel cell load purging method based on current distribution optimization in some embodiments of the present application, the steps of stopping the gas supply are determined according to the current distribution state, including stopping the load purging and gas supply when the relative standard deviation of the current distribution reaches a threshold, or the maximum value of the current distribution reaches a threshold.

[0019] According to the fuel cell load purging method based on current distribution optimization in some embodiments of the present application, the relative standard deviation of the current distribution reaches a threshold value, which is an increase of the relative standard deviation of the current distribution compared to the initial moment in the range of 10%~200%, and / or the increase of the maximum value of the current distribution compared to the initial moment in the range of 10%~200%.

[0020] According to the fuel cell loaded purging method based on current distribution optimization in some embodiments of the present application, it also includes connecting a discharge resistor between the positive and negative electrodes of the fuel cell stack to discharge the fuel cell stack to consume the residual reaction gas in the anode and cathode; when the voltage between the positive and negative electrodes of the fuel cell stack drops below the set value, the discharge resistor is disconnected to complete the shutdown.

[0021] Beneficial effects: From the perspective of current distribution, the present invention provides more detailed internal current distribution information for optimizing the fuel cell shutdown process, making up for the current deficiency of relying solely on high-frequency resistance as the basis for judgment. Moreover, the current distribution information can provide assistance for a deeper understanding of the fuel cell start-stop process and help alleviate the stack attenuation phenomenon.

[0022] The present invention optimizes and controls the purge conditions during the on-load purge process, mainly including parameters such as the stack operating temperature, purge gas flow rate, gas humidity, gas pressure, and gas temperature. The present invention also optimizes the purge time, which is reflected in the fact that the purge is achieved in two stages in the optimal embodiment of the present invention, wherein each stage corresponds to a different purge parameter, thereby achieving the optimized control of the present invention. The implementation results show that the above-mentioned optimization method of the present invention can achieve the stack maintaining a suitable current distribution state during the on-load purge process, alleviate the concentration of current distribution inside the stack during the purge process, and help alleviate the stack attenuation phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 This figure shows the effect of different purge gas volumes on current distribution during the loaded purge process according to an embodiment of the present invention.

[0025] Figure 2 This is a trend diagram of the maximum value of current distribution under different purge gas volumes during the loaded purge process of an embodiment of the present invention.

[0026] Figure 3 This figure shows the influence of different stack temperatures on current distribution during the on-load purge process in an embodiment of the present invention.

[0027] Figure 4 This is a graph showing the changing trend of the maximum current distribution at different stack temperatures during the on-load purge process according to an embodiment of the present invention.

[0028] Figure 5 This figure shows the effect of different gas humidification on current distribution during the loaded purge process according to an embodiment of the present invention.

[0029] Figure 6 This is a trend diagram of the maximum value of current distribution under different gas humidification conditions during the loaded purge process of an embodiment of the present invention.

[0030] Figure 7 This figure shows the influence of different intake pressures on current distribution during the loaded purge process according to an embodiment of the present invention.

[0031] Figure 8 This is a trend diagram of the maximum value of current distribution under different intake pressures during the loaded purge process of an embodiment of the present invention.

[0032] Figure 9 This is the current distribution when a two-step purge strategy is adopted in an embodiment of the present invention.

[0033] Figure 10 This is a trend diagram of the maximum value of current distribution when a two-step purge strategy is adopted in an embodiment of the present invention.

[0034] Figure 11 The relative standard deviation of the current distribution has an impact on the current distribution compared to the initial moment.

[0035] Figure 12 The effect of the relative standard deviation increase of different current distributions on durability.

[0036] Figure 13 This is a diagram showing the changing trend of current distribution during the on-load purge process according to an embodiment of the present invention.

[0037] Figure 14 This is a diagram showing the changing trend of the current distribution during the on-load purge process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0039] The applicant's prior application (application number 2024114604335) describes a fuel cell start-stop method based on current distribution optimization. This method aims to more accurately determine the purge time during the shutdown of the fuel cell stack, perform the purge in the shortest possible time, and dry the water in the fuel cell stack as much as possible while reducing the possibility of fuel cell stack degradation.

[0040] The method specifically discloses, in a first aspect, a fuel cell shutdown method based on current distribution optimization according to some embodiments of the present application, comprising setting the fuel cell stack to an idle state, supplying a certain amount of reactant gas to the fuel cell stack, and performing a load purge on the fuel cell stack;

[0041] The gas supply is stopped based on the current distribution state inside the stack; the output current of the stack is reduced to zero; a discharge resistor is connected between the positive and negative electrodes of the stack to discharge the stack to consume the residual reactant gas in the cathode and anode; when the voltage between the positive and negative electrodes of the stack drops below the set value, the discharge resistor is disconnected to complete the shutdown. The steps of this method include stopping the gas supply based on the current distribution state, including stopping the loaded purge and gas supply when the relative standard deviation of the current distribution is stable or reaches a threshold. Among them, the standard deviation threshold of the current distribution is preferably 60.0%.

[0042] In this method, the stack is set to an idle state, the stack temperature is reduced to a certain value, the resistance of the discharge resistor is 0.01 to 20 times the internal resistance of the stack, and the voltage is reduced to a set value of 0.8V.

[0043] This method optimizes the basis for determining the purge time by analyzing the current distribution within the active area of ​​the stack during the on-load purge process. This ensures that the current distribution is within a reasonable range while maximizing water discharge and minimizing the purge time, thereby reducing the likelihood of stack degradation. This method connects a discharge resistor between the positive and negative electrodes to rapidly consume residual gas in the anode and cathode, thereby shortening the duration of high potential caused by residual gas in the anode and cathode.

[0044] During the shutdown process, this method first reduces the current to the idle current, then increases the anode and cathode gas flow to 10 times the amount corresponding to the idle current, and at the same time turns off the humidification function, allowing dry gas to directly enter the stack for load purging. Figure 13 The figure shows the time-varying trend of the current distribution during the stack's loaded purge process. As the purge time increases, the current concentration gradually shifts from the left side (cathode inlet side) to the right side (cathode outlet side). This is because the large amount of dry gas overdries the cathode inlet side, increasing internal resistance and causing the current to flow toward the relatively more humid outlet side. This is how the inventors unexpectedly discovered that the current distribution reflects the distribution of water within the stack. Figure 14The following plot shows the relative standard deviation of the current distribution over time during this process. It can be seen that the current distribution consistency gradually deteriorates with increasing purge time, reaching stability after approximately 200 seconds. This indicates that the current distribution region stabilizes after approximately 200 seconds, indicating that the water generated by the reaction within the stack and the water removed by the reactant gas purge have reached a dynamic equilibrium. At this point, continuing to purge the stack with the current reactant gas flow rate will essentially stabilize the current distribution and maintain a dynamic equilibrium between the water generated by the reaction within the stack and the water removed by the reactant gas purge, resulting in a roughly stable water volume. Therefore, continuing to purge the stack with the current reactant gas flow rate will not further reduce the water volume within the stack. Furthermore, if the air flow rate is high, continued purge may overdry the stack inlet, causing mechanical damage to the membrane electrode and stack degradation. If the air flow rate is low, a longer purge time may be required to reach this equilibrium, and continuing purge will further reduce the product's usability.

[0045] Therefore, by Figure 13-14 It can be seen that the stability of the collected stack current distribution can be used as a basis for determining whether to stop the gas purge. The gas purge is stopped based on the current distribution. At this point, the amount of water produced inside the stack and the amount of water removed by the gas purge are balanced, reaching the critical point for reducing the amount of water in the stack. In other words, the purge has achieved optimal water removal. Stopping the purge at this point can avoid stack degradation caused by long-term purge with high air volume and avoid the reduced convenience caused by long-term purge with low air volume.

[0046] As described above, during the shutdown process, the stack is first de-loaded to idle and the stack temperature is lowered to a set value. Subsequently, the hydrogen and air flow rates are increased to set values, and an on-load purge is performed. Once the current distribution consistency stabilizes, the on-load purge is terminated, and the stack output current is rapidly reduced to zero. The reactant gas supply is then stopped, and a discharge resistor is connected to discharge the stack, rapidly consuming any residual reactant gas in the anode and cathode. Once the stack voltage drops to a certain range (e.g., below 0.8V or below 0.3V), the discharge resistor is disconnected. Furthermore, during the shutdown process, the anode and cathode purge gas flow rate is increased to 1.5 to 15.0 times the flow rate corresponding to the idle current. Furthermore, at the end of the on-load purge during the shutdown process, the current is reduced to zero. During the on-load purge process, the current distribution uniformity (measured by parameters such as the current distribution range, variance, standard deviation, and relative standard deviation) shows an increasing trend. This trend is then stabilized, which serves as the basis for determining the end of the on-load purge. Furthermore, during the shutdown process, a discharge resistor is connected to consume the residual reaction gas, and the resistance value of the connected discharge resistor is 0.01 to 20 times the internal resistance of the fuel cell stack.

[0047] This method provides more detailed internal current distribution information for optimizing the fuel cell startup and shutdown process from the perspective of current distribution, making up for the current deficiency of relying solely on high-frequency resistance as the basis for judgment. In addition, the current distribution information can provide a deeper understanding of the fuel cell startup and shutdown process, and help alleviate the stack attenuation phenomenon.

[0048] However, during the on-load purge process, the purge conditions affect the concentration of current distribution within the stack, thereby adversely affecting the stack's durability. Therefore, from the perspective of current distribution optimization, the present invention controls the purge conditions during the on-load purge process, primarily including parameters such as the stack operating temperature, purge gas flow rate, gas humidity, gas pressure, and gas temperature, to achieve a suitable current distribution state for the stack during the on-load purge process.

[0049] Therefore, based on the above, the present invention starts from the perspective of current distribution optimization, and controls the purging conditions during the loaded purging process, mainly including parameters such as the stack operating temperature, purging gas flow, gas humidity, gas pressure, and gas temperature. When the current distribution state reaches the threshold, the loaded purging is stopped, and then the stack output current is quickly reduced to 0 to complete the loaded purging process.

[0050] Furthermore, the purge conditions mainly include the following parameters: the stack operating temperature range is 30℃~90℃, the gas flow range is 200~2000 mA cm -2 Corresponding to the gas volume, the gas temperature range is 30℃~90℃, the gas humidity range is 0~100%RH, and the gas pressure range is 0~150 kPa.

[0051] Furthermore, during the on-load purge process, the purge conditions can be either constant or changed as the purge time progresses, that is, it can be performed in one step, two steps, or multiple steps.

[0052] Furthermore, the criterion for the end of the on-load purge is determined by the current distribution state. The relative standard deviation of the current distribution at the end increases by ≤200% compared with the initial moment, and the maximum value of the current distribution increases by ≤200% compared with the initial moment.

[0053] Example 1: This example takes a proton exchange membrane fuel cell as an example. Specifically, the active area of ​​the stack is 372 cm 2 , gas flow rates were 500, 800, 1000, and 1200 mA cm -2 The corresponding gas volume, operating temperature is 75℃, the gas is dry gas, the inlet pressure is 15 kPa, and the loaded purge lasts for 5 minutes. The final current distribution is as follows Figure 1 As shown, Figure 2Figure 2 shows the variation trend of the maximum current distribution during the on-load purge process. It can be seen that as the on-load purge time increases, the current distribution concentration within the stack becomes increasingly severe, and the current distribution maximum gradually increases. Furthermore, the larger the purge gas volume, the larger the current maximum. This indicates that appropriately reducing the purge gas volume can help alleviate the phenomenon of excessive current concentration, but too small a volume is not conducive to purging residual moisture from the stack in a short period of time.

[0054] Example 2: This example takes a proton exchange membrane fuel cell as an example. Specifically, the active area of ​​the stack is 372 cm 2 , gas flow rate is 1000 mA cm -2 The corresponding gas volume, working temperature are 55℃, 65℃, 75℃ respectively, the gas is dry gas, the inlet pressure is 15 kPa, the loaded purge lasts for 5 minutes, and the final current distribution is as follows Figure 3 As shown, Figure 4 Figure 2 shows the variation trend of the maximum current distribution value during the on-load purge process. It can be seen that as the on-load purge time increases, the maximum current distribution value within the stack gradually increases. Furthermore, the higher the stack operating temperature, the larger the current maximum value and the more severe the current distribution concentration. This indicates that appropriately lowering the stack operating temperature can help alleviate the phenomenon of excessive current distribution concentration.

[0055] Example 3: This example takes a proton exchange membrane fuel cell as an example. Specifically, the active area of ​​the stack is 372 cm 2 , operating temperature is 75℃, gas flow rate is 1000 mA cm -2 The corresponding gas volume, gas humidity is dry gas, 60% RH, inlet pressure is 15kPa, and the loaded purge lasts for 5 minutes. The final current distribution is as follows Figure 5 As shown, Figure 6 Figure 2 shows the variation trend of the maximum current distribution during the on-load purge process. It can be seen that as the on-load purge time increases, the maximum current distribution value within the stack gradually increases. Furthermore, the lower the gas humidity, the larger the current maximum value and the more severe the current distribution concentration. This indicates that appropriately increasing the gas humidity can help alleviate the phenomenon of excessive current concentration, but excessively high humidity is detrimental to the maximum removal of residual moisture from the stack.

[0056] Example 4: This example takes a proton exchange membrane fuel cell as an example. Specifically, the active area of ​​the stack is 372 cm 2 , operating temperature is 75℃, gas flow rate is 1000 mA cm -2 The corresponding gas volume, gas humidity is dry gas, inlet pressure is 15kPa, 30kPa, 50kPa, the loaded purge lasts for 5 minutes, and the final current distribution is as follows Figure 7 As shown, Figure 8 Figure 2 shows the variation trend of the maximum current distribution during the on-load purge process. It can be seen that as the on-load purge time increases, the maximum current distribution value within the stack gradually increases. Furthermore, the lower the intake pressure, the larger the current maximum value and the more severe the current distribution concentration. This indicates that appropriately increasing the intake pressure can help alleviate the phenomenon of excessive current distribution concentration.

[0057] Example 5: This example takes a proton exchange membrane fuel cell as an example. The loaded purge process adopts a two-step purge strategy. The specific steps are as follows: First step purge conditions: operating temperature is 55 ° C, gas flow rate is 1000 mA cm -2 The corresponding gas volume, gas humidity is 30% RH, inlet pressure is 15kPa, and the purge duration is 120 s; the second step purge conditions are: operating temperature is 55℃, gas flow rate is 500 mA cm -2 The corresponding gas volume, gas humidity is dry gas, the inlet pressure is 15kPa, and the load purge lasts for 30 seconds; the current distribution during the load purge is as follows Figure 9 As shown, Figure 10 Figure 2 shows the trend of the maximum current distribution during the on-load purge process. It can be seen that during the first on-load purge, due to the relatively low stack operating temperature and a certain amount of gas humidification, the stack distribution did not change significantly, even with a large purge gas volume. After 120 seconds of on-load purge, the maximum current increased from the initial 0.57A to 0.62A, an increase of 8.8%, and the relative standard deviation of the current distribution increased from the initial 29.7% to 36.8%, an increase of 7.1%. During the second on-load purge, dry gas was used to avoid moisture introduced by the humidifying gas itself and to remove as much moisture as possible from the bipolar plate and membrane electrode surfaces. Due to the significant impact of dry gas on current distribution, this process lasted only 30 seconds. The maximum current increased from the initial 0.62A to 0.73A, an increase of 17.7%, and the relative standard deviation of the current distribution increased from the initial 36.8% to 58.1%, an increase of 21.3%. The two-step purge strategy can not only ensure the relative uniformity of current distribution throughout the entire process, but also remove as much residual moisture as possible from the fuel cell stack, which is beneficial to improving the durability of the fuel cell stack.

[0058] Figure 11 It shows that the relative standard deviation of the current distribution has an impact on the current distribution when compared to the initial moment. When the increase is 10% and 200%, the current distribution is relatively uniform, but when the increase is 300%, the current distribution is uneven.

[0059] When the fuel cell adopts the conventional loaded purge strategy, that is, the current distribution is not optimized (the existing impedance is used as the criterion for the end of purge), the durability test results show that the performance degradation of the fuel cell stack reaches 45 mV.

[0060] Figure 12 It shows that when the relative standard deviation of the current distribution at the end of the fuel cell load purge increases by 5%, 10%, 21%, 200%, and 300% respectively compared to the initial moment, the durability test results of repeated tests show that when the relative standard deviation of the current distribution is 5%, the durability test results show that the stack performance attenuation reaches 37 mV; when the relative standard deviation of the current distribution is 10%, the durability test results show that the stack performance attenuation reaches 15 mV; when the relative standard deviation of the current distribution is 21%, the durability test results show that the stack performance attenuation reaches 13 mV; when the relative standard deviation of the current distribution is 200%, the durability test results show that the stack performance attenuation reaches 22 mV; when the relative standard deviation of the current distribution is 300%, the durability test results show that the stack attenuation reaches 46 mV. It can be seen that the strategy of optimizing the current distribution of the present invention can reduce the performance attenuation of the stack, and the load purge strategy based on current distribution optimization plays an important role in alleviating fuel cell attenuation.

[0061] The above durability test results also show that when the relative standard deviation of the current distribution increases within the range of 10%-200%, the stack performance degradation is relatively small, while when the relative standard deviation of the current distribution increases beyond this range, such as 5% and 300%, the stack performance degradation is relatively large. This shows that optimizing the current distribution during the on-load purge process plays an important role in improving the durability of the stack.

[0062] As mentioned above, the present invention is based on a fuel cell load purging method for current distribution optimization, which relates to the technical field of fuel cell start-stop strategy, with the purpose of more accurately determining the load purging time during the fuel cell shutdown process, and discharging the residual moisture in the stack as much as possible in a shorter time, while alleviating battery attenuation. The technical points are that when the stack is shut down, it first enters the idle state, and performs load purging on the stack by controlling the working temperature, purge gas flow, temperature, humidity and pressure of the stack; determines whether to stop the gas supply according to the current distribution state inside the stack; and quickly reduces the output current of the stack to zero to complete the load purging process. The present invention develops a fuel cell load purging strategy from the perspective of current distribution, which makes up for the current deficiency of relying solely on high-frequency resistance as the basis for judgment, and the current distribution information can provide assistance for a deeper understanding of the fuel cell load purging process, which helps to alleviate the attenuation of the stack.

[0063] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

Claims

1. A fuel cell on-load purge method based on current distribution optimization, characterized in that: For a fuel cell shutdown process, the method includes: The stack is set to idle state, a certain amount of reactant gas is supplied to the stack, and the stack is purged under load by controlling the purge conditions; Determining whether to stop gas supply based on the current distribution state inside the fuel cell stack, wherein determining whether to stop gas supply based on the current distribution state includes stopping on-load purge and gas supply when the relative standard deviation of the current distribution reaches a threshold value, or when the maximum value of the current distribution reaches a threshold value; Reduce the output current of the battery stack to zero; The purge conditions include at least one of the stack operating temperature range, gas flow rate range, gas temperature range, gas humidity range, and intake pressure range; The purge condition includes a first purge condition and a second purge condition, wherein the first purge condition is implemented in a first purge stage, and the second purge condition is implemented in a second purge stage; Wherein, the first purge condition includes gas humidity, and the gas humidity is moisture; The second purge condition includes gas humidity, and the gas humidity is dry gas.

2. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: in, The operating temperature range of the battery stack is 30℃~90℃.

3. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: in, The gas flow rate range is 200~2000 mA cm -2 The corresponding gas volume.

4. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: in, The gas temperature range is 30℃~90℃.

5. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: in, The gas humidity range is 0~100%RH.

6. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: in, The intake pressure range is 0~150 kPa.

7. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: The purge condition includes a first purge condition and a second purge condition, wherein the first purge condition is implemented in a first purge stage, and the second purge condition is implemented in a second purge stage; The first purge condition includes a stack operating temperature of 55°C and a gas flow rate of 1000 mA cm -2 The corresponding gas volume, gas humidity is 30% RH, inlet pressure is 15 kPa, and the purge duration is 120 s; The second purge condition includes a stack operating temperature of 55°C and a gas flow rate of 500 mA cm -2 The corresponding gas volume, gas humidity is dry gas, inlet pressure is 15kPa, and the loaded purge lasts for 30 s.

8. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: The relative standard deviation of the current distribution reaches a threshold value when the relative standard deviation of the current distribution increases by 10% to 200% compared to the initial moment, and / or the maximum value of the current distribution increases by 10% to 200% compared to the initial moment.

9. The fuel cell on-load purge method based on current distribution optimization according to claim 1, characterized in that: It also includes connecting a discharge resistor between the positive and negative poles of the battery stack to discharge the battery stack to consume the residual reaction gas in the anode and cathode; when the voltage between the positive and negative poles of the battery stack drops below the set value, the discharge resistor is disconnected to complete the shutdown.

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