Purging method and system of fuel cell and electronic equipment

Abstract

The invention discloses a purging method and system of a fuel cell and electronic equipment. The purging method of the fuel cell comprises high-temperature purging, cooling purging and low-speed purging which are carried out in sequence, wherein the high-temperature purging comprises the steps of controlling the temperature of the galvanic pile to be a high-temperature purging temperature, controlling air to purge the galvanic pile, and controlling hydrogen to cyclically purge the galvanic pile; the step of cooling and purging is that the temperature of the electric pile is controlled to be reduced from a high-temperature purging temperature to a low-temperature purging temperature, and in the cooling process, purging of the electric pile by air is stopped, and circulating purging of the electric pile by hydrogen is kept; the low-speed purging is characterized in that the temperature of the electric pile is controlled to be a low-temperature purging temperature, and the gas flow of hydrogen circulating purging is reduced so as to perform low-speed purging on the electric pile. According to the fuel cell purging method and system and the electronic equipment provided by the invention, the liquid in the fuel cell system can be effectively discharged, and the cold start capability of the fuel cell system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell purging method, system and electronic equipment. Background Art

[0002] Fuel cell technology is a power generation technology that generates electricity through electrochemical reactions of reaction materials, among which proton exchange membrane fuel cell technology (PEMFC) is the most common automotive fuel cell technology. The core components of proton exchange membrane fuel cells mainly include proton exchange membrane, cathode and anode catalyst layers, gas diffusion layers and bipolar plates. The function of the proton exchange membrane is to conduct protons, isolate electrons and cathode and anode reactants, the function of the cathode and anode catalyst layers is to provide a place for electrochemical reactions, the function of the gas diffusion layer is to facilitate the transmission of reaction gases and the discharge of liquid water, and the function of the bipolar plates is to isolate reactants and coolants.

[0003] An important challenge currently faced by proton exchange membrane fuel cells or other types of fuel cells is the cold start problem. The water generated by the fuel cell during operation will freeze in the stack, other components and pipelines below 0°C or under shutdown freezing conditions. The presence of ice may cause blockage of the gas transmission channels and pipelines inside the stack, or the components may be frozen and unable to operate normally. These situations will cause the fuel cell system to fail to start, that is, the fuel cell cold start failure. At present, the main means used by the industry to solve the cold start failure is cold start purge, that is, purge when the fuel cell system is shut down to discharge the liquid in the system. However, the cold start purge scheme in the prior art still has many shortcomings. For example, the gaseous water in the anode pipeline cannot be taken out of the system during the shutdown purge process. In the subsequent freezing process, as the temperature drops, the gaseous water will liquefy and freeze and freeze, causing the components, valve bodies and pipelines to freeze and fail to work normally, resulting in an increase in the cold start time or even failure.

[0004] Based on this, it is necessary to propose a technical solution to overcome the shortcomings of the existing technology. Summary of the invention

[0005] In order to overcome the defects of the prior art, the present invention proposes a fuel cell purging method, system and electronic equipment, which can effectively discharge the liquid in the fuel cell system and improve the cold start capability of the fuel cell system.

[0006] The present invention is implemented by the following technical solution: a fuel cell purging method, the purging method comprising high-temperature purging, cooling purging and low-speed purging performed in sequence; wherein: The high temperature purge is to control the temperature of the fuel cell stack to be a high temperature purge temperature, control air to purge the fuel cell stack, and control hydrogen to circulate and purge the fuel cell stack; The cooling and purging is to control the temperature of the stack to cool down from a high-temperature purging temperature to a low-temperature purging temperature, and in the cooling process, stop the air purging of the stack and keep the hydrogen purging of the stack in a cycle; The low-speed purge is to control the temperature of the fuel cell stack to a low-temperature purge temperature, and reduce the gas flow rate of the hydrogen circulation purge to purge the fuel cell stack at a low speed.

[0007] As a further improved technical solution, the purging method includes: detecting the high-frequency impedance value of the fuel cell stack during the high-temperature purging process, and entering a temperature reduction purging process when the high-frequency impedance value reaches a preset impedance threshold.

[0008] As a further improved technical solution, the purging method includes: detecting the temperature of the battery stack during the temperature reduction purging process, and entering a low-speed purging process when the temperature of the battery stack drops to the low-temperature purging temperature.

[0009] As a further improved technical solution, during the cooling purging and low-speed purging processes, the air is controlled to purge the emission path, and the air purging flow rate in this process is smaller than the purging flow rate when the air purges the fuel cell stack during the high-temperature purging process.

[0010] As a further improved technical solution, the purging method also includes drain valve purging, and the drain valve purging is: stopping the purging of hydrogen to the fuel cell stack and controlling the air to purge the drain valve.

[0011] As a further improved technical solution, during the high-temperature purge, cooling purge, low-speed purge and drain valve purge processes, the drain valve is intermittently opened and closed; wherein: When the low-speed purge process lasts for a preset time, or the drain valve is opened and closed a preset number of times during the low-speed purge process, the drain valve purge process is entered; and / or, When the duration of the drain valve purging process reaches a preset time, or the drain valve is opened and closed a preset number of times during the drain valve purging process, the purging is terminated.

[0012] As a further improved technical solution, during the high-temperature purge process, the air compressor operates at a first speed, and during the cooling purge, low-speed purge and drain valve purge processes, the air compressor operates at a second speed; wherein the second speed is less than the first speed; and / or, During the high-temperature purge and the cooling purge, the hydrogen circulation pump operates at a third speed, and during the low-speed purge, the hydrogen circulation pump operates at a fourth speed; wherein the fourth speed is lower than the third speed.

[0013] The present invention is also implemented through the following technical scheme: a purge system for a fuel cell, the purge system comprising a fuel cell stack, an air purge path, a hydrogen circulation purge path, a hydrothermal management path and a purge discharge path, wherein the air purge path can selectively control air to flow through or not through the fuel cell stack, the hydrogen circulation purge path controls hydrogen to circulate through the fuel cell stack after gas-liquid separation, the hydrothermal management path controls the temperature of the fuel cell stack, and the purge system operates to implement the purge method as described above.

[0014] As a further improved technical solution, the air purge circuit includes an air compressor, an air intake valve, an air pressure valve and a bypass valve. The air provided by the air compressor enters the fuel cell stack through the air intake valve and is discharged from the fuel cell stack through the air pressure valve. The bypass valve is connected between the inlet of the air intake valve and the outlet of the air pressure valve.

[0015] The present invention is also implemented through the following technical solution: an electronic device includes a memory and a processor, the memory stores a computer program that can be run on the processor, and the processor implements the fuel cell purging method as described above when executing the computer program.

[0016] The fuel cell purging method provided by the present invention can condense the gaseous water in the anode circuit into liquid water in advance by optimizing the cold start shutdown purging strategy and combining water temperature control and purging flow control, and discharge it through a drain valve, thereby facilitating the sedimentation and separation of the condensed liquid water mist, thereby effectively preventing liquid from remaining and freezing in the fuel cell system, and preventing the gaseous water remaining in the system from continuously condensing into ice and freezing components and pipelines during shutdown and freezing, thereby avoiding cold start failure or long waiting time and improving the cold start capability of the fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a schematic diagram of a system of an embodiment of a purge system for a fuel cell according to the present invention.

[0018] Figure 2 It is a control waveform diagram of various components of an embodiment of a fuel cell purging method of the present invention.

[0019] Figure 3 It is a curve graph showing the relationship between saturated water vapor pressure and temperature.

[0020] Explanation of the accompanying figures: 1-air compressor; 2-bypass valve; 3-air intake valve; 4-air pressure valve; 5-hydrogen circulation pump; 6-water distributor; 7-drain valve; 8-cell stack; 9-water pump; 10-three-way valve; 11-external radiator. DETAILED DESCRIPTION

[0021] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0022] The technical solutions in the embodiments of the present invention are 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, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] The present invention provides a fuel cell purging method, system and electronic device. The fuel cell purging method adopts segmented purging, combined with water temperature control and purging flow control, which can condense gaseous water in the anode loop into liquid water in advance, and facilitate the precipitation and separation of condensed liquid water mist, which can effectively avoid liquid residue and freezing in the fuel cell system, and improve the cold start capability of the fuel cell system.

[0024] See also Figure 1 As shown, it is a system architecture diagram of an embodiment of a fuel cell purge system to which the fuel cell purge method provided by the present application can be applied. In this embodiment, the purge system includes a fuel cell stack 8, an air purge path, a hydrogen circulation purge path, a water heat management path, and a purge discharge path.

[0025] The air purge path includes an air compressor 1, a bypass valve 2, an air intake valve 3 and an air pressure valve 4. The air provided by the air compressor 1 enters the battery stack 8 through the air intake valve 3 and is discharged from the battery stack 8 through the air pressure valve 4. The bypass valve 2 is connected between the inlet of the air intake valve 3 and the outlet of the air pressure valve 4. The air purge path can selectively control the air to flow through or not through the battery stack 8. Specifically, when the bypass valve 2 is disconnected and the air intake valve 3 and the air pressure valve 4 are connected, the air output by the air compressor 1 flows through the battery stack 8 and blows to the purge discharge path after passing through the battery stack 8; when the bypass valve 2 is connected and the air intake valve 3 and the air pressure valve 4 are disconnected, the air output by the air compressor 1 is directly blown to the purge discharge path through the bypass valve 2 without flowing through the battery stack 8.

[0026] The hydrogen circulation purge path includes a hydrogen circulation pump 5 and a water separator 6. The hydrogen circulation purge path controls the hydrogen to flow through the fuel cell stack 8 after gas-liquid separation through the water separator 6, thereby circulating and purging the fuel cell stack 8 and separating the liquid circulation. The water separator 6 is connected to the drain valve 7 of the purge discharge path.

[0027] The water heat management circuit includes a water pump 9, a three-way valve 10 and an external radiator 11. The on-off control of the three-way valve 10 can realize the water in the water heat management circuit to circulate through or not flow through the external radiator 11, so as to control the water temperature and further control the temperature of the battery stack 8.

[0028] Please also read Figure 2 As shown, the fuel cell purging method provided by the present invention includes high-temperature purging, cooling purging and low-speed purging performed in sequence; wherein: The high temperature purge is to control the temperature of the fuel cell stack 8 to be a high temperature purge temperature, control air to purge the fuel cell stack 8, and control hydrogen to circulate and purge the fuel cell stack 8; The cooling and purging is to control the temperature of the stack 8 to cool down from a high-temperature purging temperature to a low-temperature purging temperature, and in the cooling process, stop the air from purging the stack 8 and keep the hydrogen from purging the stack 8 in a cycle; The low-speed purge is to control the temperature of the fuel cell stack 8 to a low-temperature purge temperature, and reduce the gas flow rate of the hydrogen circulation purge to purge the fuel cell stack 8 at a low speed.

[0029] The purging method of the fuel cell provided by the present invention adopts segmented purging. The high-temperature purging process can quickly remove the liquid water in the stack 8, reduce the water content of the stack 8, and improve the purging efficiency; the cooling purging process is combined with water temperature control, which can gradually condense the gaseous water in the anode loop into liquid water, effectively avoiding the cold start failure caused by condensation and freezing of gaseous water after shutdown; the low-speed purging process is combined with purging flow control, so that the condensed liquid water mist can be fully settled and separated, improve the water separation efficiency, reduce the cycle purging time, and improve the purging efficiency. Therefore, the purging method of the fuel cell provided by the present invention can effectively avoid liquid residue and freezing in the fuel cell system, and improve the cold start capability of the fuel cell system.

[0030] See also Figure 3 As shown in Figure 2, under certain conditions, the saturated water vapor partial pressure increases with increasing temperature. Figure 3 Under a common environmental condition inside the battery stack 8 shown, when the temperature of the battery stack 8 is 60°C, the water vapor partial pressure is about 20MPa, and when the temperature of the battery stack 8 is 40°C, the water vapor partial pressure is about 7MPa, that is, when the temperature drops from 60°C to 40°C, the amount of gaseous water can be reduced by about 65%, thereby significantly reducing the amount of ice generated during the subsequent shutdown and freezing process. The present invention realizes condensing the gaseous water in the anode circuit into liquid water in advance through the cooling and purging process, thereby significantly reducing the amount of ice generated during the subsequent shutdown and freezing of the fuel cell system. Figure 3It can be seen that when the temperature of the battery stack 8 is cooled from 70°C to 30°C, the change in water vapor partial pressure is large, that is, the liquefaction and precipitation of gaseous water is more significant. When the temperature of the battery stack 8 continues to drop from 30°C, the change in water vapor partial pressure is not large, that is, the liquefaction and precipitation of gaseous water is limited. Therefore, in some embodiments, the high-temperature purge temperature is 55°C to 70°C, and the low-temperature purge temperature is 30°C to 50°C.

[0031] In one embodiment of the present application, when the water content of the battery stack 8 is reduced to a target value by high-temperature purge, the cooling purge process is entered. Specifically, the high-frequency impedance value of the battery stack 8 is detected during the high-temperature purge process, and when the high-frequency impedance value reaches a preset impedance threshold, the cooling purge process is entered. The high-frequency impedance value of the battery stack 8 can reflect the degree of dryness and wetness of the battery stack 8. When the high-frequency impedance value of the battery stack 8 reaches a preset impedance threshold, the air is stopped from purging the battery stack 8, that is, the cathode of the battery stack 8 is no longer purged to prevent the battery stack 8 from being too dry. In some embodiments, the impedance threshold is set to 80-100mΩ.

[0032] During the cooling and purging process, the change in temperature is a process that requires a certain period of time, and the temperature change is not immediate. In the embodiment of the present application, during the cooling and purging process, the air no longer purges the stack 8, and only the anode purging is retained. Further, the temperature can be gradually changed by controlling the cooling rate, and the amount of liquefied gaseous water can be controlled to match the ability of hydrogen circulation purging and liquid separation, so that the liquefied liquid can be discharged immediately and smoothly. During the cooling and purging process, the temperature of the stack is detected, and when the temperature of the stack drops to the low-temperature purging temperature, the low-speed purging process is entered.

[0033] In this embodiment, the gas flow rate of hydrogen circulation purge during low-speed purge is less than the gas flow rate of hydrogen circulation purge during high-temperature purge and cooling purge; and the gas flow rate of hydrogen circulation purge during high-temperature purge and cooling purge remains the same. In other embodiments, the gas flow rate of hydrogen circulation purge during high-temperature purge and cooling purge may also be different. That is, in the present application scheme, it is sufficient to ensure that the gas flow rate of hydrogen circulation purge during low-speed purge is less than the gas flow rate of hydrogen circulation purge during high-temperature purge and cooling purge, and there is no restriction on whether the gas flow rate of hydrogen circulation purge during high-temperature purge and cooling purge is the same.

[0034] Please continue reading Figure 2 As shown, in this embodiment, during the cooling purge and low-speed purge process, the air does not purge the stack 8, and the air purges the exhaust path to dilute the tail exhaust hydrogen. The purge flow rate of the air in this process does not need to be too large, and it is smaller than the purge flow rate when the air purges the stack 8 during the high-temperature purge process, so as to reduce the air consumption.

[0035] Furthermore, the purging method also includes: when the low-speed purging meets the preset conditions, the low-speed purging process is ended and the drain valve purging process is entered. The drain valve purging is: stopping the hydrogen purging of the fuel cell stack 8 and controlling the air to purge the drain valve 7. In this embodiment, the preset condition is that the duration of the low-speed purging process reaches a preset time. In one embodiment, the duration of the low-speed purging process is 20s to 60s. In other embodiments, the preset condition may also be when the drain valve 7 is opened and closed for a preset number of times during the low-speed purging process.

[0036] Please continue reading Figure 2 As shown, in this embodiment, during the high-temperature purge, cooling purge, low-speed purge and drain valve purge processes, the drain valve 7 is intermittently opened and closed. During the high-temperature purge process, the opening and closing frequency of the drain valve 7 is high, and the duration of the drain valve 7 being turned on accounts for a large proportion, so as to meet the demand for large drainage during high-temperature purge; during the cooling purge, low-speed purge and drain valve purge processes, the opening and closing frequency of the drain valve 7 is relatively reduced, and the duration of the drain valve 7 being turned on accounts for a relatively small proportion, so as to reduce the consumption of hydrogen while meeting the drainage demand.

[0037] When the duration of the drain valve purging process reaches a preset time, or the drain valve 7 is opened and closed a preset number of times during the drain valve purging process, the drain valve purging is terminated and the entire purging process is completed.

[0038] It can be understood that during the purging process, the air flow rate is adjusted by the air compressor speed and the opening of the relevant valves, and the hydrogen flow rate is adjusted by the hydrogen circulation pump and the opening of the relevant valves. In this embodiment, during the high-temperature purging process, the air compressor 1 operates at a first speed, and during the cooling purging, low-speed purging and drain valve purging processes, the air compressor 1 operates at a second speed; wherein the second speed is less than the first speed to achieve the above-mentioned air purging gas flow control. During the high-temperature purging and cooling purging processes, the hydrogen circulation pump 5 operates at a third speed, and during the low-speed purging process, the hydrogen circulation pump 5 operates at a fourth speed; wherein the fourth speed is less than the third speed to achieve the above-mentioned hydrogen purging gas flow control.

[0039] It should be noted that the "high temperature", "low temperature" and "low speed" in the above-mentioned high temperature purge, low temperature purge and low speed purge are all relative, and do not represent certain specific temperature ranges and flow rates or wind speed ranges. It can be understood that high temperature refers to a temperature higher than low temperature compared to low temperature; low temperature refers to a temperature lower than high temperature compared to high temperature; the high temperature purge temperature can be obtained by cooling down the low temperature purge temperature. Similarly, low speed refers to a purge speed that is smaller than the initial purge speed, which is obtained by reducing the initial purge speed. As for the value ranges of high temperature purge temperature, low temperature purge temperature and air flow rate or speed of low speed purge, those skilled in the art can reasonably choose according to the actual application scenario. The present application also exemplarily gives the value ranges of high temperature purge temperature and low temperature purge temperature in some of the above embodiments.

[0040] Combine the following Figure 2 The pair shown Figure 1 The specific control waveform diagrams of each component illustrate the fuel cell purging method of the present invention by taking a specific embodiment as an example.

[0041] After receiving the shutdown command at time t1, when it is determined that purging is required, the air compressor 1 and the hydrogen circulation pump 5 are respectively operated to the set speeds N1 and N3, the bypass valve 2 is disconnected (i.e., the bypass valve 2 opening is 0), and the air intake valve 3 and the air pressure valve 4 are opened to the maximum value, so that the air flow at the outlet of the air compressor 1 completely enters the stack 8. At the same time, the temperature of the stack 8 is adjusted by the three-way valve 10 and the external radiator 11, so that the stack 8 is purged at a higher temperature T1, achieving the goal of reducing the water content in the membrane of the stack 8, until the high-frequency impedance value rises to the threshold R at time t2, and the first stage of the high-temperature purging process is ended.

[0042] At time t2, the speed of the air compressor 1 is reduced to N2, the bypass valve 2 is fully opened (i.e., the opening is adjusted to the maximum), the air intake valve 3 and the air pressure valve 4 are disconnected (i.e., the opening of the air intake valve 3 and the air pressure valve 4 is 0), so that the air flow at the outlet of the air compressor 1 does not enter the fuel cell 8, and the fuel cell 8 is not purged to prevent the fuel cell 8 from being too dry. At this time, the air purge only serves to dilute the tail exhaust hydrogen. At this time, the external radiator 11 and the three-way valve 10 continue to work, controlling the water temperature to decrease from T1 to T2, so that the gaseous water in the fuel cell 8 and the pipeline is condensed into liquid water particles in large quantities, and the hydrogen circulation pump 5 maintains the speed N3, and takes out part of the liquid water condensed in the fuel cell 8 flow channel and the circulation pipeline to the water separator 6. Until the water temperature drops to the temperature T2 at time t3, the second stage of the cooling and purging process ends.

[0043] At time t3, the air path purge remains unchanged from the cooling purge process in the second stage, the external radiator 11 and the three-way valve 10 control the water temperature to maintain at T2, and the hydrogen circulation pump 5 reduces the speed to N4 to reduce the flow rate of the anode loop gas, so that the mist droplets condensed in the anode can be better separated by the water separator 6 at a low speed and discharged from the drain valve 7. After the preset duration reaches time t4, the low-speed purge process of the third stage ends.

[0044] At time t4, the air path purge remains unchanged with the cooling purge and low-speed purge processes of the second and third stages, the temperature remains unchanged, the hydrogen circulation pump 5 is turned off, the drain valve 7 is opened, and the body of the drain valve 7 is purged. The purge at this stage can reduce the residual liquid water in the water separator 6 while purging the body of the drain valve 7, and can prevent the residual liquid water in the water separator 6 and the drain valve 7 from freezing and being unable to open normally. During the purge process, the drain valve 7 is opened and closed intermittently. When the drain valve 7 is opened and closed for a preset number of times, it reaches time t5 and the purge is ended. In this embodiment, the drain valve 7 is opened and closed for a preset number of times, for example, 10 times; of course, in other embodiments, the number of times is not limited to this, and those skilled in the art can set the number of times or duration according to the actual purge situation.

[0045] Please refer again Figure 1 As shown, the purge system of the fuel cell provided in the present application includes a fuel cell stack 8, an air purge path, a hydrogen circulation purge path, a hydrothermal management path and a purge discharge path, wherein the air purge path can selectively control air to flow through or not flow through the fuel cell stack 8, the hydrogen circulation purge path controls the hydrogen to circulate through the fuel cell stack 8 after gas-liquid separation, and the hydrothermal management path controls the temperature of the fuel cell stack 8, and the operation of the purge system can realize the purge method as described above.

[0046] The present invention also provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor implements the above-mentioned fuel cell purging method when executing the computer program. The present invention also provides a storage medium, which stores the above-mentioned fuel cell purging method.

[0047] From the above description of the specific embodiments, it can be known that the fuel cell purging method provided by the present invention can condense the gaseous water in the anode circuit into liquid water in advance by optimizing the cold start shutdown purging strategy, combining water temperature control and purging flow control, and discharge it through the drain valve 7, and facilitate the sedimentation and separation of the condensed liquid water mist, which can effectively avoid the liquid from remaining and freezing in the fuel cell system, and avoid the gaseous water remaining in the system during shutdown to continue to condense into ice and freeze components and pipelines during shutdown and freezing, thereby avoiding cold start failure or long waiting time, and improving the cold start capability of the fuel cell system.

[0048] The present invention is described by several specific embodiments, and it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or specific circumstances without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods falling within the scope of the claims of the present invention.

Claims

1. A fuel cell purging method, characterized in that: The purging method includes high-temperature purging, cooling purging and low-speed purging performed in sequence; wherein: The high temperature purge is to control the temperature of the fuel cell stack to be a high temperature purge temperature, control air to purge the fuel cell stack, and control hydrogen to circulate and purge the fuel cell stack; The cooling and purging is to control the temperature of the stack to cool down from a high-temperature purging temperature to a low-temperature purging temperature, and in the cooling process, stop the air purging of the stack and keep the hydrogen purging of the stack in a cycle; The low-speed purge is to control the temperature of the fuel cell stack to a low-temperature purge temperature, and reduce the gas flow rate of the hydrogen circulation purge to purge the fuel cell stack at a low speed.

2. The fuel cell purging method according to claim 1, characterized in that: The purging method includes: detecting the high-frequency impedance value of the battery stack during a high-temperature purging process, and entering a temperature-lowering purging process when the high-frequency impedance value reaches a preset impedance threshold.

3. The fuel cell purging method according to claim 1, characterized in that: The purging method comprises: detecting the temperature of the battery stack during a temperature-lowering purging process, and entering a low-speed purging process when the temperature of the battery stack drops to the low-temperature purging temperature.

4. The fuel cell purging method according to claim 1, characterized in that: During the cooling purge and low-speed purge process, the air is controlled to purge the exhaust path, and the purge flow rate of the air in this process is smaller than the purge flow rate when the air purges the fuel cell stack during the high-temperature purge process.

5. The fuel cell purging method according to any one of claims 1 to 4, characterized in that: The purging method also includes drain valve purging, and the drain valve purging includes: stopping the purging of hydrogen to the fuel cell stack and controlling the air to purge the drain valve.

6. The fuel cell purging method according to claim 5, characterized in that: During high-temperature purge, cooling purge, low-speed purge and drain valve purge, the drain valve is intermittently opened and closed; wherein: When the low-speed purge process lasts for a preset time, or the drain valve is opened and closed a preset number of times during the low-speed purge process, the drain valve purge process is entered; and / or, When the duration of the drain valve purging process reaches a preset time, or the drain valve is opened and closed a preset number of times during the drain valve purging process, the purging is terminated.

7. The fuel cell purging method according to claim 5, characterized in that: During high-temperature purging, the air compressor operates at a first speed, and during cooling purging, low-speed purging and drain valve purging, the air compressor operates at a second speed; wherein the second speed is less than the first speed; and / or, During the high-temperature purge and the cooling purge, the hydrogen circulation pump operates at a third speed, and during the low-speed purge, the hydrogen circulation pump operates at a fourth speed; wherein the fourth speed is lower than the third speed.

8. A fuel cell purge system, characterized in that: The purge system includes a fuel cell stack, an air purge path, a hydrogen circulation purge path, a hydrothermal management path and a purge discharge path, wherein the air purge path can selectively control air to flow through or not flow through the fuel cell stack, the hydrogen circulation purge path controls hydrogen to circulate through the fuel cell stack after gas-liquid separation, and the hydrothermal management path controls the temperature of the fuel cell stack, and the purge system operates to implement the purge method as described in any one of claims 1 to 7.

9. The fuel cell purge system according to claim 8, characterized in that: The air purge path includes an air compressor, an air intake valve, an air pressure valve and a bypass valve. The air provided by the air compressor enters the fuel cell stack through the air intake valve and is discharged from the fuel cell stack through the air pressure valve. The bypass valve is connected between the inlet of the air intake valve and the outlet of the air pressure valve.

10. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor implements the fuel cell purging method as claimed in any one of claims 1 to 8 when executing the computer program.

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