Cathode closed type air cooling fuel cell system and humidity adjusting method thereof

Abstract

The invention provides a cathode closed type air cooling fuel cell system and a humidity adjusting method thereof, and belongs to the technical field of fuel cells. The system comprises an electric pile, an air compressor, an air filter, a hot air recycling box, a first electromagnetic valve, a second electromagnetic valve and a third electromagnetic valve, a cathode inlet of the electric pile is connected with an air compressor through a pipeline, the air compressor is connected with an air filter through a pipeline, the air filter is connected with a first electromagnetic valve through a pipeline, and a first three-way valve is arranged on the pipeline; the hot air recycling box is provided with an exhaust port and a recycling port arranged towards a heat dissipation area of the electric pile, the exhaust port is connected with a second electromagnetic valve through a pipeline, the second electromagnetic valve is connected with a first three-way valve through a pipeline, and a second three-way valve is arranged on the pipeline; a cathode outlet of the electric pile is connected with a third electromagnetic valve through a pipeline; the third electromagnetic valve is connected with the second three-way valve through a pipeline. According to the invention, a hot air recovery branch formed by the hot air recovery box and the three electromagnetic valves can be adopted to control the humidity of the galvanic pile.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a cathode closed air-cooled fuel cell system and a humidity regulation method thereof. Background Art

[0002] The humidity of the fuel cell stack is one of the important factors affecting the performance of fuel cells. The current mainstream control strategy is to add a membrane humidifier to the fuel cell system for external humidification. However, the membrane humidifier needs to rely on complex flow channel design when in use, resulting in large flow losses. The membrane material is easily affected by pressure and temperature, which makes the humidity regulation effect of the membrane humidifier on the fuel cell stack poor. Summary of the invention

[0003] The main purpose of this application is to propose a cathode closed air-cooled fuel cell system and a humidity regulation method thereof to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0004] To achieve the above-mentioned purpose, one aspect of the present application provides a cathode closed air-cooled fuel cell system, the system comprising a fuel cell stack, an air compressor, an air filter, a hot air recovery box, a first solenoid valve, a second solenoid valve and a third solenoid valve; The cathode inlet of the stack is connected to the air compressor through a pipeline, the air compressor is connected to the air filter through a pipeline, the air filter is connected to the first solenoid valve through a pipeline, and a first three-way valve is provided on the pipeline connecting the air filter and the first solenoid valve; The hot air recovery box is provided with a recovery port and an exhaust port, the recovery port is arranged toward the heat dissipation area of ​​the fuel cell stack, the exhaust port is connected to the second solenoid valve through a pipeline, the second solenoid valve is connected to the first three-way valve through a pipeline, and a second three-way valve is provided on the pipeline connecting the second solenoid valve and the first three-way valve; The cathode outlet of the fuel cell stack is connected to the third solenoid valve through a pipeline, and the third solenoid valve is connected to the second three-way valve through a pipeline.

[0005] Furthermore, the system also includes an exhaust gas solenoid valve, which is in an intermittently open state, and the anode outlet of the fuel cell stack is connected to the exhaust gas solenoid valve through a pipeline.

[0006] Furthermore, the system also includes a high-pressure hydrogen storage tank and a pressure reducing valve, the anode inlet of the fuel cell stack is connected to the pressure reducing valve through a pipeline, and the pressure reducing valve is connected to the high-pressure hydrogen storage tank through a pipeline.

[0007] Furthermore, the system also includes a back pressure valve, a third three-way valve is arranged on a pipeline connecting the cathode outlet of the fuel cell stack and the third solenoid valve, and the back pressure valve is connected to the third three-way valve through a pipeline.

[0008] Furthermore, the system also includes a heat dissipation device, which is used to dissipate heat from the battery stack in a working state.

[0009] To achieve the above object, another aspect of the present application provides a humidity adjustment method, which is applied to the above cathode closed air-cooled fuel cell system, and the method comprises: Obtain the anode voltage drop of the battery stack; When the anode voltage drop of the battery stack is less than or equal to a preset voltage drop threshold, obtaining the ambient temperature of the battery stack, and adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the battery stack; Obtaining the cathode inlet humidity of the fuel cell stack; Determine whether the cathode inlet humidity of the fuel cell stack is equal to a preset humidity threshold; if so, control the state of the third solenoid valve to remain unchanged; if not, adjust the opening of the third solenoid valve, and then return to the step of obtaining the cathode inlet humidity of the fuel cell stack.

[0010] Further, adjusting the opening of the third solenoid valve includes: When the humidity at the cathode inlet of the fuel cell stack is less than the preset humidity threshold, increasing the opening of the third solenoid valve; When the humidity at the cathode inlet of the fuel cell stack is greater than the preset humidity threshold, the opening degree of the third solenoid valve is reduced.

[0011] Further, adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the fuel cell stack includes: When the ambient temperature of the battery stack is lower than a first preset temperature threshold, the first solenoid valve is controlled to be in a fully closed state, and the second solenoid valve is controlled to be in a fully open state; When the ambient temperature of the fuel cell stack is greater than or equal to the first preset temperature threshold, the first solenoid valve is controlled to be in a fully open state, and the second solenoid valve is controlled to be in a fully closed state.

[0012] Furthermore, the method further comprises: When the anode voltage drop of the stack is greater than the preset voltage drop threshold, extending the opening time of the exhaust gas solenoid valve each time; The temperature of the fuel cell stack is obtained, and the states of the first solenoid valve, the second solenoid valve, and the third solenoid valve are adjusted according to the temperature of the fuel cell stack.

[0013] Further, adjusting the states of the first solenoid valve, the second solenoid valve, and the third solenoid valve according to the temperature of the fuel cell stack includes: When the temperature of the battery stack is lower than a second preset temperature threshold, the first solenoid valve is controlled to be in a fully closed state, the second solenoid valve is controlled to be in a fully open state, and the state of the third solenoid valve is controlled to remain unchanged; When the temperature of the battery stack is greater than or equal to the second preset temperature threshold, the first solenoid valve is controlled to be in a fully open state, the second solenoid valve is controlled to be in a fully closed state, and the third solenoid valve is controlled to be in a fully closed state.

[0014] The present application includes at least the following beneficial effects: by setting a first solenoid valve on the cathode inlet side of the stack to control the external air from entering the stack, setting a hot air recovery box and a second solenoid valve around the stack to control the recovery of the exhaust gas discharged from the stack as a whole when the stack is working, and setting a third solenoid valve on the cathode outlet side of the stack to control the recovery of the wet air recirculated by the cathode when the stack is working, the hot air recovery branch formed by the hot air recovery box and the three solenoid valves can assist in the control of the humidity of the stack, and the overall structure is simple and compact, without the need for complex flow channel design. In the case where it is determined that there is no flooding inside the stack according to the anode voltage drop of the stack, the humidity of the stack can be effectively controlled by adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the stack, and then appropriately adjusting the opening of the third solenoid valve according to the humidity of the cathode inlet of the stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of a cathode closed air-cooled fuel cell system provided in an embodiment of the present application; Figure 2 It is a flow chart of a humidity adjustment method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of systems and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0017] It is understood that the terms "first", "second", etc. used in this application can be used in this article to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another concept. For example, without departing from the scope of the embodiments of the present application, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0019] The humidity of the fuel cell stack is one of the important factors affecting the performance of the fuel cell. If the humidity of the fuel cell stack is insufficient, the internal resistance of proton conduction will increase, resulting in cracking and degradation of the fuel cell stack membrane. If the humidity of the fuel cell stack is too high, the fuel cell stack electrodes will be flooded, affecting the electrochemical reaction inside the fuel cell stack. The current mainstream control strategy is to add a membrane humidifier to the fuel cell system for external humidification. The membrane humidifier recovers the moisture and heat in the fuel cell exhaust gas and exchanges this moisture and heat to the reaction gas entering the fuel cell, that is, the water vapor generated by the fuel cell during operation is converted into liquid water through the heat and mass transfer process of the membrane, and then transferred to the reaction gas through the membrane, thereby achieving the purpose of humidification. However, when using the membrane humidifier, it needs to rely on a complex flow channel design, resulting in large flow losses. The membrane material is easily affected by pressure and temperature, which makes the membrane humidifier poor in regulating the humidity of the fuel cell stack. In addition, in the entire process of controlling the humidity of the fuel cell stack, it does not take into account the need to take certain countermeasures when the fuel cell stack is flooded.

[0020] In view of this, the embodiment of the present application provides a cathode closed air-cooled fuel cell system and a humidity control method thereof, which is provided by setting a first solenoid valve on the cathode inlet side of the stack to control the external air to enter the stack, setting a hot air recovery box and a second solenoid valve around the stack to control the recovery of the exhaust gas discharged as a whole when the stack is working, and setting a third solenoid valve on the cathode outlet side of the stack to control the recovery of the humid air recirculated by the cathode when the stack is working. The hot air recovery branch formed by the hot air recovery box and the three solenoid valves can assist in achieving the control of the humidity of the stack, and the overall structure is simple and compact, without the need for complex flow channel design. In the case of determining that there is no flooding inside the stack according to the anode voltage drop of the stack, the humidity of the stack can be effectively controlled by adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the stack, and then appropriately adjusting the opening of the third solenoid valve according to the humidity of the cathode inlet of the stack.

[0021] Figure 1It is a structural schematic diagram of a cathode closed air-cooled fuel cell system provided in an embodiment of the present application, which includes a fuel cell stack 101, an air compressor 102, an air filter 103, a hot air recovery box 104, a high-pressure hydrogen storage tank 105, a heat dissipation device 106, a back pressure valve 107, a pressure reducing valve 108, an exhaust gas solenoid valve 109, a first solenoid valve 110, a second solenoid valve 111 and a third solenoid valve 112.

[0022] The cathode inlet of the fuel cell stack 101 is connected to the air compressor 102 through a pipeline, the air compressor 102 is connected to the air filter 103 through a pipeline, the air filter 103 is connected to the first solenoid valve 110 through a pipeline, and the first solenoid valve 110 is connected to the atmospheric environment; the air in the atmospheric environment enters the air filter 103 through the first solenoid valve 110, and the air filter 103 is used to filter out impurities such as solid particles in the air, and then the filtered air is compressed by the air compressor 102 and transported to the fuel cell stack 101 for electrochemical reaction.

[0023] The hot air recovery box 104 is provided with a recovery port and an exhaust port. The recovery port is mainly arranged toward the heat dissipation area of ​​the fuel cell stack 101. The exhaust port is connected to the second solenoid valve 111 through a pipeline. A first three-way valve 113 is arranged on the pipeline connecting the air filter 103 and the first solenoid valve 110. The second solenoid valve 111 is connected to the first three-way valve 113 through a pipeline. The hot air recovery box 104 is used to recover the exhaust gas discharged when the fuel cell stack 101 is working, and then the exhaust gas is transported to the gas ready to enter the air filter 103 through the second solenoid valve 111 for full mixing, so as to achieve energy recovery.

[0024] The cathode outlet of the fuel cell stack 101 is connected to the third solenoid valve 112 through a pipeline, and a second three-way valve 114 is arranged on the pipeline connecting the second solenoid valve 111 and the first three-way valve 113, and the third solenoid valve 112 is connected to the second three-way valve 114 through a pipeline, and a third three-way valve 115 is arranged on the pipeline connecting the cathode outlet of the fuel cell stack 101 and the third solenoid valve 112, and the back pressure valve 107 is connected to the third three-way valve 115 through a pipeline, and the back pressure valve 107 is connected to the atmospheric environment; for the humid air recirculated in the cathode of the fuel cell stack 101 when it is working, the humid air can be transported to the gas ready to enter the air filter 103 through the third solenoid valve 112 for full mixing, so as to realize energy recovery, or the humid air can be directly discharged to the atmospheric environment through the back pressure valve 107, and the back pressure valve 107 can control the pressure inside the fuel cell stack 101 to protect the fuel cell stack 101 in a working state.

[0025] The anode inlet of the fuel cell stack 101 is connected to the pressure reducing valve 108 through a pipeline, the pressure reducing valve 108 is connected to the high-pressure hydrogen storage tank 105 through a pipeline, the anode outlet of the fuel cell stack 101 is connected to the tail gas solenoid valve 109 through a pipeline, and the tail gas solenoid valve 109 is connected to the atmosphere; the hydrogen provided by the high-pressure hydrogen storage tank 105 is transported to the fuel cell stack 101 via the pressure reducing valve 108 for electrochemical reaction, and the moisture and nitrogen discharged from the anode outlet of the fuel cell stack 101 when it is working will be discharged to the atmosphere via the tail gas solenoid valve 109, and the setting of the tail gas solenoid valve 109 can also effectively prevent the hydrogen in the fuel cell stack 101 from escaping into the atmosphere, thereby improving the utilization rate of the hydrogen.

[0026] The heat dissipation device 106 can select at least one of a cooling fan, a radiator, a heat exchanger, etc. to dissipate heat for the battery stack 101 in a working state, which can assist in achieving temperature control of the battery stack 101, and is beneficial to extending the service life of the battery stack 101; in the present application, a cooling fan is preferably used, which can be arranged above or on the side of the battery stack 101 to ensure that air can flow smoothly over the surface of the battery stack 101, and the cooling fan and the hot air recovery box 104 are preferably arranged on the upper and lower sides of the battery stack 101, so that the cooling fan will not affect the hot air recovery box 104 from recovering the exhaust gas generated by the battery stack 101 when working.

[0027] It should be noted that before the humidity of the above-mentioned cathode closed air-cooled fuel cell system is adjusted, the exhaust gas solenoid valve 109 is set in an intermittently open state, which can be understood as limiting the exhaust gas solenoid valve 109 to operate alternately between opening and closing according to a certain time period. The time period is set artificially, and the first solenoid valve 110 is set in a normally open state, the second solenoid valve 111 is set in a normally closed state, and the third solenoid valve 112 is set in a normally closed state. In addition, it is necessary to set up a variety of sensors for data collection, specifically: by setting a humidity sensor at the cathode inlet of the fuel cell stack 101 to collect the humidity of the cathode inlet of the fuel cell stack 101; by setting a first pressure sensor at the anode inlet of the fuel cell stack 101 to collect the anode inlet pressure of the fuel cell stack 101; by setting a second pressure sensor at the anode outlet of the fuel cell stack 101 to collect the anode outlet pressure of the fuel cell stack 101; by embedding a first temperature sensor on the bipolar plate of the fuel cell stack 101 to collect the temperature of the fuel cell stack 101; by setting a second temperature sensor in the indoor space environment where the fuel cell stack 101 is located, and the second temperature sensor should be set as close to the fuel cell stack 101 as possible to collect the ambient temperature of the fuel cell stack 101.

[0028] The cathode closed air-cooled fuel cell system proposed in the embodiment of the present application is equipped with a first solenoid valve on the cathode inlet side of the fuel cell stack to control the entry of external air into the fuel cell stack, a hot air recovery box and a second solenoid valve are arranged around the fuel cell stack to control the recovery of exhaust gas discharged as a whole when the fuel cell stack is working, and a third solenoid valve is arranged on the cathode outlet side of the fuel cell stack to control the recovery of wet air recirculated at the cathode when the fuel cell stack is working. The hot air recovery branch formed by the hot air recovery box and the three solenoid valves can assist in achieving the control of the humidity of the fuel cell stack, and the overall structure is simple and compact, and no complicated flow channel design is required.

[0029] Figure 2 is an optional flow chart of a humidity adjustment method provided in an embodiment of the present application, which is mainly applied to the above-mentioned cathode closed air-cooled fuel cell system. Figure 2 The method may include but is not limited to steps S201 to S209: Step S201, obtaining the anode voltage drop of the battery stack; Step S202, determining whether the anode voltage drop of the battery stack is greater than a preset voltage drop threshold; if so, it indicates that water flooding occurs inside the battery stack, and step S208 is executed at this time; if not, it indicates that water flooding does not occur inside the battery stack, and step S203 is executed at this time; Step S203, obtaining the ambient temperature of the fuel cell stack, and adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the fuel cell stack; Step S204, obtaining the cathode inlet humidity of the fuel cell stack; Step S205, determining whether the humidity at the cathode inlet of the stack is equal to a preset humidity threshold; if so, it means that the humidity of the stack meets the standard, and step S207 is executed at this time; if not, it means that the humidity of the stack is too high or too low, and step S206 is executed at this time; Step S206, adjusting the opening of the third solenoid valve, and then returning to execute the above step S204; Step S207, controlling the state of the third solenoid valve to remain unchanged; Step S208, extending the opening time of the exhaust gas solenoid valve each time; Step S209: Acquire the temperature of the fuel cell stack, and adjust the states of the first solenoid valve, the second solenoid valve, and the third solenoid valve according to the temperature of the fuel cell stack.

[0030] In the present application, a controller can be configured for the above-mentioned cathode closed air-cooled fuel cell system, and the controller can cyclically execute the above-mentioned humidity adjustment method when it is in the power-on operation state, that is, after executing the above-mentioned step S207 or the above-mentioned step S209, it will return to re-execute the above-mentioned step S201; and when the controller switches from the power-on operation state to the power-off state, the above-mentioned humidity adjustment method will no longer be used to control the above-mentioned cathode closed air-cooled fuel cell system, that is, no matter which of the above-mentioned steps is executed, the entire control process will be directly terminated.

[0031] In some embodiments, the implementation of the above step S201 includes: obtaining the anode inlet pressure and the anode outlet pressure of the fuel cell stack, and then subtracting the anode inlet pressure and the anode outlet pressure of the fuel cell stack to obtain the anode pressure drop of the fuel cell stack.

[0032] In the above-mentioned step S202 of some embodiments, the method for determining the preset voltage drop threshold includes: obtaining the working current of the battery stack, and then obtaining the preset voltage drop threshold corresponding to the working current of the battery stack by looking up a table, the queried table records multiple continuous different working current ranges of the battery stack and the preset voltage drop threshold corresponding to each working current range, and these data are prepared through preliminary experiments.

[0033] In the above step S203 of some embodiments, the states of the first solenoid valve and the second solenoid valve are adjusted according to the ambient temperature of the fuel cell stack, and the corresponding implementation includes: Determine whether the ambient temperature of the fuel cell stack is less than a first preset temperature threshold value, which can be selected within the range of [5°C, 15°C] and is preferably set to 10°C; if so, control the first solenoid valve to be in a fully closed state, and control the second solenoid valve to be in a fully open state, so that the hot air recovery box can transmit the air heated by the fuel cell stack to the air supply branch through the second solenoid valve after recovering part of the air, and the air supply branch is formed by the cathode inlet of the fuel cell stack, the air compressor and the air filter, so as to increase the air temperature at the cathode inlet of the fuel cell stack; if not, control the first solenoid valve to be in a fully open state, and control the second solenoid valve to be in a fully closed state, so that the air in the atmospheric environment can be transmitted to the air supply branch through the first solenoid valve, to ensure the normal electrochemical reaction inside the fuel cell stack.

[0034] In the above step S205 of some embodiments, the following explanation is made for possible situations when judging whether the cathode inlet humidity of the fuel cell stack is equal to the preset humidity threshold: if the absolute deviation between the detected cathode inlet humidity of the fuel cell stack and the preset humidity threshold is within the range of [0%RH, 0.5%RH], it is assumed that the cathode inlet humidity of the fuel cell stack is equal to the preset humidity threshold.

[0035] In the above step S206 of some embodiments, the opening of the third solenoid valve can be adjusted according to the relationship between the cathode inlet humidity of the battery stack and the preset humidity threshold. The preset humidity threshold can be selected within the range of [20%RH, 40%RH], and is preferably set to 30%RH. The corresponding implementation methods include: When the humidity at the cathode inlet of the fuel cell stack is less than the preset humidity threshold, the opening of the third solenoid valve is increased, and the opening of the third solenoid valve is limited to a preset opening threshold at most, and the preset opening threshold is preferably set to 20%, so as to increase the humid air generated by the cathode recycling of the fuel cell stack transmitted to the air supply branch, and increase the water content of the air at the cathode inlet of the fuel cell stack; and when the humidity at the cathode inlet of the fuel cell stack is greater than the preset humidity threshold, the opening of the third solenoid valve is reduced, so as to reduce the humid air generated by the cathode recycling of the fuel cell stack transmitted to the air supply branch, and reduce the water content of the air at the cathode inlet of the fuel cell stack.

[0036] In the above step S209 of some embodiments, the states of the first solenoid valve, the second solenoid valve and the third solenoid valve are adjusted according to the temperature of the battery stack, and the corresponding implementation includes: Determine whether the temperature of the fuel cell stack is less than a second preset temperature threshold value, which can be selected within the range of [50°C, 70°C] and is preferably set to 60°C; if so, control the first solenoid valve to be in a fully closed state, control the second solenoid valve to be in a fully open state, and control the state of the third solenoid valve to remain unchanged, so that the air heated by the fuel cell stack recovered by the hot air recovery box can be transmitted to the air supply branch through the second solenoid valve to increase the air temperature at the cathode inlet of the fuel cell stack, thereby reducing the air humidity at the cathode inlet of the fuel cell stack; if not, control the first solenoid valve to be in a fully open state, control the second solenoid valve to be in a fully closed state, and control the third solenoid valve to be in a fully closed state, so that the air in the atmospheric environment can be transmitted to the air supply branch through the first solenoid valve to ensure normal electrochemical reaction inside the fuel cell stack.

[0037] The humidity control method for a cathode closed air-cooled fuel cell system proposed in the embodiment of the present application can effectively control the humidity of the fuel cell stack by adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the fuel cell stack, and then appropriately adjusting the opening of the third solenoid valve according to the humidity of the cathode inlet of the fuel cell stack, which is beneficial to alleviating the membrane drying phenomenon in the fuel cell stack; by extending the opening time of the exhaust gas solenoid valve each time, and then controlling the first solenoid valve to be in a fully closed state and the second solenoid valve to be in a fully open state, the flooding phenomenon in the fuel cell stack can be accelerated and alleviated, the service life of the fuel cell stack can be increased, and at the same time, the fuel cell stack can be restored to a normal state as soon as possible, the exhaust loss of the exhaust gas solenoid valve can be reduced, and the hydrogen utilization rate of the fuel cell stack can be improved.

[0038] Although the description of the present application has been quite detailed and specifically describes several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the attached claims, taking into account the prior art, so as to effectively cover the intended scope of the present application. In addition, the above description of the present application is based on the embodiments foreseeable by the inventor, and its purpose is to provide a useful description, and those non-substantial changes to the present application that have not yet been foreseen may still represent equivalent changes to the present application.

Claims

1. A cathode closed air-cooled fuel cell system, characterized in that: The system includes a fuel cell stack, an air compressor, an air filter, a hot air recovery box, a first solenoid valve, a second solenoid valve and a third solenoid valve; The cathode inlet of the stack is connected to the air compressor through a pipeline, the air compressor is connected to the air filter through a pipeline, the air filter is connected to the first solenoid valve through a pipeline, and a first three-way valve is provided on the pipeline connecting the air filter and the first solenoid valve; The hot air recovery box is provided with a recovery port and an exhaust port, the recovery port is arranged toward the heat dissipation area of ​​the fuel cell stack, the exhaust port is connected to the second solenoid valve through a pipeline, the second solenoid valve is connected to the first three-way valve through a pipeline, and a second three-way valve is provided on the pipeline connecting the second solenoid valve and the first three-way valve; The cathode outlet of the fuel cell stack is connected to the third solenoid valve through a pipeline, and the third solenoid valve is connected to the second three-way valve through a pipeline.

2. The cathode closed air-cooled fuel cell system according to claim 1, characterized in that: The system further comprises an exhaust gas solenoid valve, which is in an intermittently open state, and the anode outlet of the fuel cell stack is connected to the exhaust gas solenoid valve via a pipeline.

3. The cathode closed air-cooled fuel cell system according to claim 2, characterized in that: The system also includes a high-pressure hydrogen storage tank and a pressure reducing valve. The anode inlet of the fuel cell stack is connected to the pressure reducing valve through a pipeline, and the pressure reducing valve is connected to the high-pressure hydrogen storage tank through a pipeline.

4. The cathode closed air-cooled fuel cell system according to claim 2, characterized in that: The system further comprises a back pressure valve. A third three-way valve is arranged on a pipeline connecting the cathode outlet of the stack and the third solenoid valve. The back pressure valve is connected to the third three-way valve through a pipeline.

5. The cathode closed air-cooled fuel cell system according to claim 2, characterized in that: The system further comprises a heat dissipation device, which is used to dissipate heat from the battery stack in a working state.

6. A humidity adjustment method, characterized in that: The method is applied to the cathode closed air-cooled fuel cell system according to any one of claims 2 to 5, and the method comprises: Obtain the anode voltage drop of the battery stack; When the anode voltage drop of the battery stack is less than or equal to a preset voltage drop threshold, obtaining the ambient temperature of the battery stack, and adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the battery stack; Obtaining the cathode inlet humidity of the fuel cell stack; Determine whether the cathode inlet humidity of the fuel cell stack is equal to a preset humidity threshold; if so, control the state of the third solenoid valve to remain unchanged; if not, adjust the opening of the third solenoid valve, and then return to the step of obtaining the cathode inlet humidity of the fuel cell stack.

7. The humidity adjustment method according to claim 6, characterized in that: The adjusting the opening of the third solenoid valve comprises: When the humidity at the cathode inlet of the fuel cell stack is less than the preset humidity threshold, increasing the opening of the third solenoid valve; When the humidity at the cathode inlet of the fuel cell stack is greater than the preset humidity threshold, the opening degree of the third solenoid valve is reduced.

8. The humidity adjustment method according to claim 6, characterized in that: The adjusting the states of the first solenoid valve and the second solenoid valve according to the ambient temperature of the fuel cell stack includes: When the ambient temperature of the battery stack is lower than a first preset temperature threshold, the first solenoid valve is controlled to be in a fully closed state, and the second solenoid valve is controlled to be in a fully open state; When the ambient temperature of the fuel cell stack is greater than or equal to the first preset temperature threshold, the first solenoid valve is controlled to be in a fully open state, and the second solenoid valve is controlled to be in a fully closed state.

9. The humidity adjustment method according to claim 6, characterized in that: The method further comprises: When the anode voltage drop of the stack is greater than the preset voltage drop threshold, extending the opening time of the exhaust solenoid valve each time; The temperature of the fuel cell stack is obtained, and the states of the first solenoid valve, the second solenoid valve, and the third solenoid valve are adjusted according to the temperature of the fuel cell stack.

10. The humidity adjustment method according to claim 9, characterized in that: The adjusting the states of the first solenoid valve, the second solenoid valve, and the third solenoid valve according to the temperature of the fuel cell stack includes: When the temperature of the battery stack is lower than a second preset temperature threshold, the first solenoid valve is controlled to be in a fully closed state, the second solenoid valve is controlled to be in a fully open state, and the state of the third solenoid valve is controlled to remain unchanged; When the temperature of the battery stack is greater than or equal to the second preset temperature threshold, the first solenoid valve is controlled to be in a fully open state, the second solenoid valve is controlled to be in a fully closed state, and the third solenoid valve is controlled to be in a fully closed state.

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