Fuel cell on-load purging method based on current distribution optimization

Abstract

The invention discloses a fuel cell on-load purging method based on current distribution optimization, relates to the technical field of fuel cell start-stop strategies, and aims to more accurately determine on-load purging time in the shutdown process of a fuel cell, discharge residual moisture in a galvanic pile as much as possible in a relatively short time and relieve cell attenuation at the same time. The technical key points are as follows: the galvanic pile is set to be in an idling state, a certain amount of reaction gas is supplied to the galvanic pile, and on-load purging is performed on the galvanic pile by controlling purging conditions; wherein the purging condition comprises at least one of a galvanic pile working temperature range, a gas flow range, a gas temperature range, a gas humidity range and a gas inlet pressure range, a fuel cell on-load purging strategy is developed from the angle of current distribution, the defect that only a high-frequency resistor is used as a judgment basis at present is overcome, and the reliability of the fuel cell is improved. And the current distribution information can provide help for deeper understanding of the on-load purging process of the fuel cell, and the attenuation of the electric pile can be relieved.

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 load purging method based on current distribution optimization. Background Art

[0002] A fuel cell is a power generation device that directly converts the chemical energy in fuel and oxidant into electrical energy through electrochemical reactions. It has the advantages of high energy conversion rate, no pollution and low noise. With the promotion of its commercialization process, the market has put forward higher requirements for the output power of fuel cells, so fuel cells with large active areas have become a development trend. However, fuel cells involve multiple physical fields such as water, gas, heat, electricity, and force. The combined action of these physical fields determines the power generation performance of the battery. However, these physical fields are usually difficult to distribute evenly, especially in a larger active area, so it is more likely to cause uneven attenuation in different areas of the stack. In addition, the start-stop process of the fuel cell is prone to hydrogen-air interface, high cathode potential, and reaction gas starvation, which accelerates the attenuation of the stack. In response to the above problems, the study of fuel cell start-stop strategies based on current distribution optimization has become an important technical means to alleviate battery attenuation.

[0003] During the shutdown process of the battery stack, the water generated in the battery stack needs to be discharged from the battery stack to avoid corrosion and icing of the bipolar plates and membrane electrodes due to residual water, which leads to battery stack attenuation. The usual practice is to use reaction gas or other inert gas to directly purge the residual water in the battery stack. In order to reduce the cathode potential during the water purge process, it is usually carried out at a lower current density or idle state. This can discharge excess water in the battery stack and avoid high potential, which helps to alleviate the attenuation of the battery 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 battery stack. Inappropriate on-load purge strategies will lead to very uneven current distribution, which will have an adverse effect on the durability of the battery stack. Summary of the invention

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

[0005] According to a fuel cell load purge method based on current distribution optimization in some embodiments of the present application, for fuel cell shutdown, the method includes: The stack is set to an 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; Stop gas supply based on the current distribution state inside the fuel cell stack; Reduce the output current of the battery stack to zero; The purge conditions include at least one of a stack operating temperature range, a gas flow rate range, a gas temperature range, a gas humidity range, and an intake pressure range.

[0006] According to the fuel cell 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.

[0007] 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 200~2000mAcm -2 The corresponding gas volume.

[0008] According to the fuel cell load purging method based on current distribution optimization in some embodiments of the present application, the gas temperature ranges from 30°C to 90°C.

[0009] According to the fuel cell load purging method based on current distribution optimization in some embodiments of the present application, the gas humidity range is 0~100%RH.

[0010] According to the fuel cell load purging method based on current distribution optimization in some embodiments of the present application, the intake pressure range is 0~150kPa.

[0011] According to the fuel cell load purging method based on current distribution optimization in some embodiments of the present application, the purging condition includes a first purging condition and a second purging condition, the first purging condition is implemented in the first purging stage, and the second purging condition is implemented in the second purging stage; The first purge condition includes a stack operating temperature of 55°C, a gas flow rate of 1000 mA cm -2 The corresponding gas volume, gas humidity is 30%RH, inlet pressure is 15kPa, and the purge duration is 120s; The first purge conditions include 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, the inlet pressure is 15kPa, and the loaded purge lasts for 30s.

[0012] 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.

[0013] 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 that the relative standard deviation of the current distribution increases by 10%~200% compared with the initial moment, and / or the maximum value of the current distribution increases by 10%~200% compared with the initial moment.

[0014] According to the fuel cell load 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 a set value, the discharge resistor is disconnected to complete the shutdown.

[0015] Beneficial effects: From the perspective of current distribution, the present invention provides more detailed internal current distribution information for optimizing the shutdown process of the fuel cell, 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 start-stop process of the fuel cell and help alleviate the attenuation phenomenon of the fuel cell stack.

[0016] The present invention optimizes and controls the purge conditions during the on-load purge process, mainly including: the operating temperature of the battery stack, the purge gas flow rate, the gas humidity, the gas pressure, the gas temperature and other parameters. Among them, the present invention also optimizes the purge time, which is reflected in the optimal embodiment of the present invention, that is, the purge is achieved in two stages, wherein each stage corresponds to different purge parameters mentioned above, to achieve the optimization control of the present invention. The implementation results show that the above-mentioned optimization method of the present invention can achieve the battery stack to maintain a suitable current distribution state during the on-load purge process, alleviate the concentration of the current distribution inside the battery stack during the purge process, and help alleviate the attenuation phenomenon of the battery stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0018] Figure 1 FIG. 4 is an illustration of the effect of different purge gas volumes on current distribution during the on-load purge process of an embodiment of the present invention.

[0019] Figure 2 This is a trend diagram of the maximum value of current distribution under different purge gas volumes during the on-load purge process of an embodiment of the present invention.

[0020] Figure 3 The figure shows the influence of different stack temperatures on current distribution during the on-load purge process in an embodiment of the present invention.

[0021] Figure 4 This is a graph showing the changing trend of the maximum value of the current distribution at different stack temperatures during the on-load purge process of an embodiment of the present invention.

[0022] Figure 5 FIG. 4 is an illustration of the effect of different gas humidification on current distribution during the on-load purge process according to an embodiment of the present invention.

[0023] Figure 6 This is a trend diagram of the maximum value of current distribution under different gas humidification conditions during the on-load purge process of an embodiment of the present invention.

[0024] Figure 7 FIG. 4 is an illustration of the effect of different intake pressures on current distribution during the on-load purge process according to an embodiment of the present invention.

[0025] Figure 8 This is a graph showing the changing trend of the maximum value of the current distribution under different intake pressures during the on-load purge process of an embodiment of the present invention.

[0026] Fig. 9 The current distribution in the embodiment of the present invention using a two-step purge strategy.

[0027] Fig.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.

[0028] Fig.11 The relative standard deviation of the current distribution has an impact on the current distribution compared to the initial moment.

[0029] Fig.12 This is the effect of the relative standard deviation increase of different current distributions on durability.

[0030] Fig.13 This is a diagram showing the changing trend of current distribution during the on-load purge process of an embodiment of the present invention.

[0031] Fig.14 This is a diagram showing the changing trend of the current distribution state during the on-load purge process of an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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 described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] The applicant's prior application (application number 2024114604335) records a fuel cell start-stop method based on current distribution optimization. The 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 attenuation.

[0034] The method specifically discloses, in a first aspect, a fuel cell shutdown method based on current distribution optimization in some embodiments of the present application, including setting the stack to an idle state, supplying a certain amount of reactant gas to the stack, and performing load purge on the stack; The gas supply is stopped according to 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 anode and cathode; 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 are to stop the gas supply according to the current distribution state, including stopping the load 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 preferred current distribution is 60.0%.

[0035] In this method, the stack is set to an idle state, and the stack temperature is reduced to a certain value. In this method, the resistance value of the discharge resistor is 0.01 to 20 times the internal resistance of the stack; the voltage is reduced to a set value of 0.8V.

[0036] This method optimizes the basis for determining the purge time by observing the law of current distribution in the active area of ​​the battery stack during the on-load purge process, so as to achieve current distribution within a reasonable range, discharge as much water as possible, and shorten the purge time as much as possible to reduce the possibility of battery stack attenuation. This method connects a discharge resistor between the positive and negative electrodes to achieve rapid consumption of residual gas in the anode and cathode, thereby shortening the duration of high potential caused by residual gas in the anode and cathode.

[0037] 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 gas volume 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. Fig.13 As shown in the figure, the current distribution changes over time during the purge process of the stack. It can be seen that as the purge time increases, the current concentration area gradually moves from the left side (cathode inlet side) to the right side (cathode outlet side). The reason is that a large amount of dry gas blows the cathode inlet side too dry, the internal resistance increases, and the current tends to the relatively more humid outlet side. It is also from this that the inventor accidentally discovered that the distribution of current reflects the distribution of water in the stack. Fig.14The figure is a trend diagram of the relative standard deviation of the current distribution over time in the process. It can be seen that with the extension of the purge time, the consistency of the current distribution gradually deteriorates and tends to be stable after about 200s. It can be seen that after about 200s, the current distribution area is stable, indicating that the water generated by the reaction in the stack and the water removed by the reaction gas purge reach a dynamic balance. That is, at this time, the current distribution of the stack is basically stable and unchanged, and the water generated by the reaction in the stack and the water removed by the reaction gas purge reach a dynamic balance, so that the amount of water in the stack is basically stable. Therefore, continuing to purge the stack with the current amount of reaction gas will not further reduce the amount of water inside the stack. On this basis, if the air volume is relatively large, continuing to purge will easily purge the entrance of the stack too dry, resulting in mechanical damage to the membrane electrode and causing the stack to decay. If the air volume is small, it takes a long purge time to reach this balance, and continuing to purge will further reduce the convenience of the product.

[0038] Therefore, by Figure 13-14 It can be seen that the stability of the current distribution of the collected stack can be used as a basis for judging whether to stop the current gas supply purge. The gas supply purge is stopped based on the current distribution. At this time, the water produced inside the stack and the water removed by the gas supply purge are balanced, which is the critical point for reducing the water volume in the stack. That is, the purge has achieved the best water removal effect. Stopping the purge at this time can avoid the attenuation of the stack caused by the long-term purge with large air volume and the reduction of convenience caused by the long-term purge with small air volume.

[0039] As mentioned above, during the shutdown process, the stack is first reduced to the idle state, and the stack temperature is reduced to the set value, and then the flow rate of hydrogen and air is increased to the set value, and the on-load purge is performed. After the current distribution consistency tends to be stable, the on-load purge is terminated, and the stack output current is quickly reduced to 0, and then the supply of the reactant gas is stopped, and the discharge resistor is connected at the same time to discharge the stack, and the residual reactant gas in the anode and cathode is quickly consumed. After the stack voltage drops to a certain range (such as below 0.8V, or below 0.3V), the discharge resistor is disconnected. Furthermore, the anode and cathode purge gas volume is increased during the shutdown process, and the gas flow rate is 1.5 to 15.0 times the gas volume corresponding to the idle current. Furthermore, the current is reduced to 0 at the end of the on-load purge during the shutdown process. During the on-load purge process, the current distribution uniformity (measured by parameters such as the current distribution range, variance, standard deviation, relative standard deviation, etc.) shows an increasing trend, and it is used as a basis for judging the end of the on-load purge when it tends to be stable. 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.

[0040] 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.

[0041] However, during the on-load purge process, the purge conditions affect the concentration of the current distribution inside the stack, thereby adversely affecting the durability of the stack. Therefore, from the perspective of current distribution optimization, the present invention controls the purge conditions during the on-load purge process, mainly including: stack operating temperature, purge gas flow, gas humidity, gas pressure, gas temperature and other parameters, so as to achieve the stack maintaining a suitable current distribution state during the on-load purge process.

[0042] Therefore, based on the above, the present invention starts from the perspective of current distribution optimization, by controlling the purge conditions during the load purge process, mainly including parameters such as the stack operating temperature, purge gas flow rate, gas humidity, gas pressure, and gas temperature. When the current distribution state reaches the threshold, the load purge is stopped, and then the stack output current is quickly reduced to 0 to complete the load purge process.

[0043] Furthermore, the purge conditions mainly include the following parameters: the stack operating temperature range is 30℃~90℃, the gas flow rate 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.

[0044] 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.

[0045] 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.

[0046] 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, working temperature is 75℃, the gas is dry gas, the inlet pressure is 15 kPa, and the purge lasts for 5 minutes. The final current distribution is as follows Figure 1 As shown, Figure 2is the changing trend of the maximum current distribution during the on-load purge process. It can be seen that with the extension of the on-load purge time, the concentration of the current distribution inside the stack becomes more serious, the maximum current distribution value gradually increases, and the larger the purge gas volume, the larger the current maximum value. It can be seen that appropriately reducing the purge gas volume can help alleviate the phenomenon of excessive current concentration, but if the gas volume is too small, it is not conducive to purging the residual moisture in the stack in a short time.

[0047] 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, the operating temperature is 55℃, 65℃, 75℃ respectively, the gas is dry gas, the inlet pressure is 15 kPa, the purge lasts for 5 minutes, and the final current distribution is as follows Figure 3 As shown, Figure 4 is the changing trend of the maximum current distribution value during the on-load purge process. It can be seen that with the extension of the on-load purge time, the maximum current distribution value inside the stack gradually increases, and the higher the stack operating temperature, the larger the current maximum value, and the more serious the current distribution concentration. It can be seen that appropriately lowering the stack operating temperature can help alleviate the phenomenon of over-concentration of current distribution.

[0048] 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 °C, 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 purge lasts for 5 minutes. The final current distribution is as follows: Figure 5 As shown, Figure 6 This is the changing 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 inside the stack gradually increases, and the lower the gas humidity, the larger the current maximum value, and the more serious the current distribution concentration. It can be seen that appropriately increasing the gas humidity can help alleviate the phenomenon of over-concentration of current distribution, but if the humidity is too high, it is not conducive to exhausting the residual moisture inside the stack as much as possible.

[0049] Example 4: This example takes a proton exchange membrane fuel cell as an example. Specifically, the active area of ​​the fuel cell stack is 372 cm 2 , operating temperature is 75 °C, gas flow rate is 1000 mA cm -2 The corresponding gas volume, gas humidity is dry gas, inlet pressure is 15kPa, 30kPa, 50kPa, and the purge lasts for 5 minutes. The final current distribution is as follows: Figure 7 As shown, Figure 8 is the changing trend of the maximum current distribution during the on-load purge process. It can be seen that with the extension of the on-load purge time, the maximum current distribution value inside the stack gradually increases, and the smaller the intake pressure, the larger the current maximum value, and the more serious the current distribution concentration. It can be seen that appropriately increasing the intake pressure can help alleviate the phenomenon of excessive current distribution concentration.

[0050] Example 5: This example takes a proton exchange membrane fuel cell as an example. The on-load 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, the inlet pressure is 15kPa, and the purge lasts for 120 s; the second step purge conditions: working 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 s; the current distribution during the load purge is as follows Fig. 9 As shown, Fig.10 The maximum value of the current distribution changes during the on-load purge process. It can be seen that in the first step of the on-load purge process, due to the lower operating temperature of the battery stack and a certain amount of gas humidification, the distribution of the battery stack did not change significantly even under a large amount of purge gas. After 120 seconds of on-load purge, the current maximum value 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%. In the second step of the on-load purge process, dry gas was used to avoid the moisture brought into the humidification gas itself and to drain the moisture on the surface of the bipolar plate and membrane electrode as much as possible. Since the dry gas has a greater impact on the current distribution, the process only lasts for 30 seconds. The current maximum value 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 process, but also expel as much residual moisture as possible from the fuel cell stack, which is beneficial to improving the durability of the fuel cell stack.

[0051] Fig.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.

[0052] When the fuel cell adopts the conventional on-load purge strategy, that is, the current distribution is not optimized (the existing impedance is used as the criterion for the end of purge), the endurance test results show that the performance attenuation of the fuel cell stack reaches 45 mV.

[0053] Fig.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 with 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 performance attenuation of the stack reaches 37 mV; when the relative standard deviation of the current distribution is 10%, the durability test results show that the performance reduction of the stack reaches 15 mV; when the relative standard deviation of the current distribution is 21%, the durability test results show that the performance of the stack reaches 13 mV; when the relative standard deviation of the current distribution is 200%, the durability test results show that the performance attenuation of the stack reaches 22 mV; when the relative standard deviation of the current distribution is 300%, the durability test results show that the attenuation of the stack reaches 46 mV. It can be seen that the strategy of optimizing the current distribution in the present invention can reduce the performance attenuation of the stack, and the load purge strategy based on the optimization of the current distribution plays an important role in alleviating the attenuation of the fuel cell.

[0054] The above durability test results also show that when the relative standard deviation of current distribution increases within the range of 10%-200%, the performance degradation of the battery stack is relatively small, while when the relative standard deviation of current distribution increases beyond this range, such as 5% and 300%, the performance degradation of the battery stack 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 battery stack.

[0055] As mentioned above, the fuel cell load purging method based on current distribution optimization of the present invention relates to the technical field of fuel cell start-stop strategy, so as to achieve more accurate determination of the load purging time during the fuel cell shutdown process, and to discharge the residual moisture in the stack as much as possible in a shorter time, while alleviating battery attenuation for the purpose. The technical point is 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. It should be noted that the terms "first", "second", etc. in the specification 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 data 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 that are 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 load purging method based on current distribution optimization, characterized in that: For a fuel cell shutdown process, the method comprises: The stack is set to an 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; Stop gas supply based on the current distribution state inside the fuel cell stack; Reduce the output current of the battery stack to zero; The purge conditions include at least one of a stack operating temperature range, a gas flow rate range, a gas temperature range, a gas humidity range, and an intake pressure range.

2. The fuel cell load purging 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 load purging 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 load purging method based on current distribution optimization according to claim 1, characterized in that: 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 the 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 15kPa, and the purge under load lasts for 120 s; The first purge conditions include 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, the 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: In the step, it is determined to stop the gas supply according to the current distribution state, including stopping the on-load purge and gas supply when the relative standard deviation of the current distribution reaches a threshold value, or the maximum value of the current distribution reaches a threshold value.

9. The fuel cell on-load purge method based on current distribution optimization according to claim 8, 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 with the initial moment, and / or the maximum value of the current distribution increases by 10% to 200% compared with the initial moment.

10. 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 electrodes 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 electrodes of the battery stack drops below a set value, the discharge resistor is disconnected to complete the shutdown.

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