A hydrogen-air fuel cell system with high hydrogen utilization rate and its purging method

Abstract

The present invention belongs to the technical field of fuel cells, and discloses a hydrogen-air fuel cell system with high hydrogen utilization rate and a purging method thereof, comprising an air supply device, a fuel cell stack and a hydrogen supply system, wherein: the fuel cell stack is a place where hydrogen and oxygen fuel undergo chemical reactions to generate electrical energy, and the air supply device is used to provide the fuel cell stack with air required for the chemical reaction; the hydrogen supply system comprises a hydrogen supply device and a hydrogen buffer device, the hydrogen supply device comprises a hydrogen storage unit, the hydrogen storage unit is connected to the anode gas inlet of the fuel cell stack, a hydrogen pressure reducing valve is further arranged between the two, and a hydrogen intake solenoid valve is further arranged between the hydrogen pressure reducing valve and the hydrogen-air fuel cell stack; the hydrogen buffer device comprises a buffer unit connected to the cathode of the fuel cell stack, a first pulse valve is arranged between the buffer unit and the fuel cell stack, and a second pulse valve is arranged at the exhaust end of the buffer unit.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and more specifically, relates to a hydrogen-air fuel cell system with high hydrogen utilization rate and a purge method thereof. Background Art

[0002] The main advantages of using hydrogen-air fuel cells in mobile power stations are: (1) There are no moving parts inside the fuel cell, and there is no combustion like in a heat engine, so the vibration and noise are low, which is beneficial to improving the stealth of unmanned underwater vehicles; (2) There is no exhaust emission. The fuel cell using pure hydrogen and pure oxygen only produces water, and there is no exhaust trail during use, which is beneficial to improving stealth; (3) It is not affected by underwater exhaust back pressure and can adapt to large depths.

[0003] During the operation of the hydrogen-air fuel cell, a large amount of air is introduced into the cathode side, and the main component of the air, nitrogen, will diffuse to the anode side through the proton exchange membrane. If the nitrogen diffused on the anode side is not discharged in time, it will continue to accumulate in the battery, causing the battery performance to decline, seriously restricting the output performance of the battery. The method of using excess gas to purge the impurity gas out of the battery is called pulse purging. However, frequent pulse purging will cause a large amount of hydrogen to be wasted, greatly reducing the fuel utilization rate and operating time. The existing method is to discharge the impurity gas by adding a single pulse exhaust valve at the anode outlet, but the problem is that it will cause fuel waste; or after the fuel cell is shut down, an inert gas is introduced for purging to remove the liquid water in the stack, which will cause the fuel cell to be shut down before purging, resulting in the problem of work suspension and delay. Therefore, it is necessary to design a fuel cell system with high hydrogen utilization to overcome the above problems. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a hydrogen-air fuel cell system with high hydrogen utilization rate and a purge method thereof, mainly to solve the problem of fuel waste caused by the emission of impurity gases from the battery.

[0005] To achieve the above object, the present invention provides a hydrogen-air fuel cell system with high hydrogen utilization rate, comprising an air supply device, a fuel cell stack and a hydrogen supply system, wherein:

[0006] The fuel cell stack is used as a place where hydrogen and oxygen fuel undergo chemical reactions to generate electrical energy, and the air supply device is used to provide the fuel cell stack with air required for the chemical reaction;

[0007] The hydrogen supply system comprises a hydrogen supply device and a hydrogen buffer device, wherein the hydrogen supply device comprises a hydrogen storage unit, the hydrogen storage unit is connected to the anode gas inlet of the fuel cell stack, a hydrogen pressure reducing valve is arranged between the two, and a hydrogen intake solenoid valve is arranged between the hydrogen pressure reducing valve and the fuel cell stack; the hydrogen buffer device comprises a buffer unit connected to the cathode of the fuel cell stack, a first pulse valve is arranged between the buffer unit and the fuel cell stack, and a second pulse valve is arranged at the exhaust end of the buffer unit;

[0008] During operation, the hydrogen pressure reducing valve and the hydrogen intake solenoid valve are controlled to open and close to supply hydrogen to the fuel cell stack, and the first pulse valve and the second pulse valve are controlled to open and close to purge the impurity gas of the fuel cell stack into the buffer unit and discharge it to the outside.

[0009] Furthermore, the hydrogen intake solenoid valve is a normally open solenoid valve, and the first pulse valve and the second pulse valve are normally closed solenoid valves.

[0010] Furthermore, the hydrogen supply device also includes a purge assembly, and the purge assembly is used to introduce inert gas into the fuel cell stack.

[0011] Furthermore, the purge assembly includes an inert gas supply unit, which is connected to the anode gas inlet of the fuel cell stack, and an inert gas pressure reducing valve is arranged between the two; an inert gas intake solenoid valve is also arranged between the inert gas pressure reducing valve and the fuel cell stack; preferably, the inert gas intake solenoid valve is a normally closed solenoid valve.

[0012] Furthermore, the hydrogen buffer device is also provided with an emergency exhaust valve.

[0013] Furthermore, the air supply device is a speed-adjustable fan; preferably, the buffer unit is a buffer tank, and its volume is 1L-2L.

[0014] According to another aspect of the present invention, a purging method for a hydrogen-air fuel cell system with high hydrogen utilization rate is also disclosed. The purging method can be implemented on any of the above-mentioned hydrogen-air fuel cell systems, comprising the following steps:

[0015] S1. Start the battery system and preset the safety voltage V m ;

[0016] S2, initialization purge on time and purge pulse interval t of the battery system x,i , where i is the number of pulses and x is seconds;

[0017] S3, close the first pulse valve and the second pulse valve, and determine whether the voltage V of any single cell in the fuel cell stack is greater than the safety voltage V m :

[0018] If so, it is repeated to determine whether the single chip voltage V is greater than the safety voltage V m ;

[0019] If not, opening the first pulse valve to allow the impurity gas accumulated in the battery system to enter the buffer unit;

[0020] S4. Determine whether the opening time of the first pulse valve is greater than a preset pulse time:

[0021] If yes, close the first pulse valve and repeat steps S2-S4;

[0022] If not, continue purging until the opening time of the first pulse valve is greater than the preset pulse time;

[0023] After executing a pulse purge operation, the pulse number i = i + 1;

[0024] S5. Determine whether the i-th pulse duration or pulse number i satisfies the preset conditions:

[0025] If yes, the first pulse valve and the second pulse valve are opened at the same time for purging, and both are closed at the same time after the preset time, and then a new round of purging is started;

[0026] If not, continue to judge, if not, continue to judge until the i-th pulse duration or pulse number i meets the preset conditions, then open the first pulse valve and the second pulse valve at the same time for buffering, and close both at the same time after the preset time to start a new round of purge.

[0027] Furthermore, in step S1, the total operating time of the battery system is also preset. After step S5 is completed, if the actual operating time t of the battery system is greater than the preset operating time, the battery system is shut down.

[0028] Further, in step S5, the preset condition corresponding to the i-th pulse duration is determined as: whether the i-th pulse duration is less than 0.2 times the i-1-th pulse duration; preferably, the preset condition corresponding to the pulse number i is determined as: whether the pulse number i is not less than 3.

[0029] Furthermore, the preset pulse time is 0.5s-1.5s; preferably, the preset pulse time is 1s.

[0030] The above technical solution conceived by the present invention has the following advantages compared with the prior art:

[0031] The present invention provides a high hydrogen utilization rate system for a hydrogen-air fuel cell, wherein the system uses a static buffer unit to provide back pressure for the hydrogen-air fuel cell system, thereby improving the output performance of the hydrogen-air fuel cell system, and discharges the impurity gas accumulated in the fuel cell stack to the buffer unit through a first pulse valve connected to the buffer unit, and discharges the impurity gas in the buffer unit through a second pulse valve connected to the exhaust end of the buffer unit, thereby effectively improving the ability of the fuel cell stack to operate stably for a long time, increasing the external pulse interval, and improving the hydrogen utilization rate.

[0032] When a large amount of air is introduced into the cathode side of the fuel cell stack in the present invention, the impurity gas, which is the main component of the air, will diffuse to the anode side through the proton exchange membrane. The impurity gas diffused on the anode side will continuously accumulate in the battery, causing the performance of the fuel cell stack to decline, seriously restricting the output performance of the fuel cell stack. In the present invention, a purge assembly is provided, which includes an inert gas supply unit, which is connected to the anode gas inlet of the fuel cell stack, and an inert gas pressure reducing valve and an inert gas intake solenoid valve are also provided between the two. The inert gas intake solenoid valve is a normally closed solenoid valve. When the fuel cell stack needs to be purged, the inert gas intake solenoid valve is opened to pass the inert gas into the fuel cell, and the impurity gas is purged out of the battery stack by the excess inert gas.

[0033] The present invention provides a purging method for a hydrogen-air fuel cell system with high hydrogen utilization rate. When the fuel cell system is running, a preset safety voltage V m and hydrogen supply time t s , and reset the pulse purge on-time and pulse purge interval t x,i , close the first pulse valve and the second pulse valve, and determine whether the voltage V of any single cell in the fuel cell stack is equal to the safety voltage V m The size of the first pulse valve is used to control the opening and closing of the first pulse valve to implement the purge buffering action; by judging the purge conduction time, the first pulse valve and the second pulse valve are controlled to open simultaneously to discharge the impurity gas to the outside; by judging the number of pulses, whether to start a new round of impurity gas purge is controlled. In general, the purge method of the present invention realizes efficient purge of the fuel cell stack system during operation by setting a buffer device downstream of the fuel cell stack, and limits frequent pulse purge by setting the number of pulses, thereby extending the pulse interval, thereby reducing hydrogen waste and improving hydrogen utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the battery stack system of the present invention;

[0035] Figure 2 is a schematic flow chart of a purging method for a hydrogen-air fuel cell stack system in an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the hydrogen utilization effect of a hydrogen-air fuel cell stack system consisting of two series-connected stacks in an embodiment of the present invention.

[0037] In the figure: 1-hydrogen storage unit, 2-hydrogen pressure reducing valve, 3-hydrogen intake solenoid valve, 4-inert gas supply unit, 5-inert gas pressure reducing valve, 6-inert gas intake solenoid valve, 7-air supply device, 8-fuel cell stack, 9-first pulse valve, 10-buffer unit, 11-second pulse valve. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] Example 1

[0040] This embodiment provides a hydrogen-air fuel cell system with high hydrogen utilization rate, such as Figure 1 As shown, the system includes an air supply device 7, a fuel cell stack 8 and a hydrogen supply system, wherein:

[0041] The fuel cell stack 8 is a place where hydrogen and oxygen fuel undergo chemical reactions to generate electrical energy. The fuel cell stack 8 may be one or a fuel cell stack group formed by connecting multiple fuel cell stacks. The fuel cell stack 8 in this embodiment includes multiple parallel bipolar plates, and the bipolar plates are arranged vertically. In a preferred embodiment, the bipolar plates are parallel flow channel graphite plates.

[0042] The air supply device is a speed-adjustable fan, which is used to provide the fuel cell stack 8 with air required for chemical reactions;

[0043] The hydrogen supply system includes a hydrogen supply device and a hydrogen buffer device. The hydrogen supply device includes a hydrogen storage unit 1, which is a hydrogen tank. The hydrogen storage unit 1 is connected to the anode gas inlet of the fuel cell stack 8, and a hydrogen pressure reducing valve 2 is provided between the two to reduce the pressure of the hydrogen supplied in the hydrogen tank; a hydrogen intake solenoid valve 3 is provided between the hydrogen pressure reducing valve 2 and the fuel cell stack 8, and the solenoid valve is a normally open solenoid valve, which is controlled to open and close to supply hydrogen to the fuel cell stack 8; the hydrogen buffer device includes a buffer unit 10 connected to the cathode of the fuel cell stack 8, and the buffer unit 10 is a storage tank. A first pulse valve 9 is provided between the buffer unit 10 and the fuel cell stack 8, and the first pulse valve 9 can receive an electrical signal to open and close, so that the fuel cell stack 8 and the storage tank are connected or closed; a second pulse valve 11 is also provided at the exhaust end of the buffer unit 10, and the pulse valve is used to achieve connection or disconnection between the storage tank and the outside world;

[0044] During operation, the hydrogen pressure reducing valve 2 and the hydrogen intake solenoid valve 3 are controlled to open and close to supply hydrogen to the fuel cell stack 8, and the first pulse valve 9 and the second pulse valve 11 are controlled to blow the impurity gas in the fuel cell stack 8 into the buffer unit 10 under the action of the pressure difference between the fuel cell stack 8 and the buffer unit, and discharge it to the outside from the buffer unit 10.

[0045] In a preferred embodiment, the hydrogen intake solenoid valve 3 is normally open, and the first pulse valve 9 and the second pulse valve 11 are normally closed.

[0046] In a preferred embodiment, the hydrogen supply device further includes a purge assembly, which is used to introduce inert gas into the fuel cell stack 8 .

[0047] In a preferred embodiment, the purge assembly includes an inert gas supply unit 4, which is connected to the anode gas inlet of the fuel cell stack 8, and an inert gas pressure reducing valve 5 is also arranged between the two; an inert gas intake solenoid valve 6 is also arranged between the inert gas pressure reducing valve 5 and the fuel cell stack 8; preferably, the inert gas intake solenoid valve 6 is a normally closed solenoid valve.

[0048] In a preferred embodiment, the hydrogen buffer device is also provided with an emergency exhaust valve.

[0049] In a preferred embodiment, the air supply device is an adjustable speed fan; preferably, the buffer unit 10 is a buffer tank, and its volume is 1L-2L, which can buffer the impurity gas regularly accumulated in the fuel cell stack to the greatest extent.

[0050] Example 2

[0051] like Figure 2 As shown, it is a schematic flow chart of a purge method for a hydrogen-air fuel cell system with high hydrogen utilization rate provided in this embodiment. The purge method can be implemented on any hydrogen-air fuel cell system provided in Example 1, and the method includes the following steps:

[0052] S1. Start the battery system under monitoring and input the preset pulse time and safety voltage V m ;

[0053] S2, initialize the purge on-time to 0, and initialize the purge pulse interval t of the battery system x,i , where i is the number of pulses and x is seconds;

[0054] S3, then close the first pulse valve 9 and the second pulse valve 11, and determine whether the voltage V of any single cell in the fuel cell stack 8 is greater than the safety voltage V m :

[0055] When the single chip voltage V is greater than the safety voltage V m, then continue to determine whether the real-time single-chip voltage V is greater than the safety voltage V m , until the single chip voltage V is no greater than the safety voltage V m ;

[0056] If the single-chip voltage V is not greater than the safety voltage V m , the first pulse valve 9 is opened to allow the impurity gas accumulated in the battery system to be purged into the buffer unit 10. During the purging, the buffer unit 10 is empty, while a large amount of impurity gas is accumulated in the fuel cell stack. At this time, there is a pressure difference between the two. Under the action of the pressure difference, once the first pulse valve 9 is opened, the impurity gas can smoothly enter the buffer unit 10;

[0057] S4, judging whether the opening time of the first pulse valve 9 is greater than the preset time:

[0058] If yes, close the first pulse valve 9 to stop the purge buffer, and repeat steps S2-S4 to start a new round of purge;

[0059] If not, buffering continues until the opening time of the first pulse valve 9 is greater than the preset pulse time, and the purge buffering is completed, so that the pressure difference between the fuel cell stack and the buffer unit is reduced; after completing one pulse purge, the pulse number i=i+1;

[0060] S5. Determine whether the duration of the i-th pulse or the total number of pulses i meets the preset conditions:

[0061] If yes, the first pulse valve 9 and the second pulse valve 11 are opened simultaneously for buffering, and both are closed simultaneously after a preset time, and steps S2-S5 are repeated to start a new round of purging;

[0062] If not, continue to judge until the i-th pulse duration or pulse number i meets the preset conditions, then open the first pulse valve 9 and the second pulse valve 11 at the same time for buffering, and close them at the same time after the preset pulse time, and start a new round of purging.

[0063] In a preferred embodiment, in the aforementioned step S1, the total operating time of the battery system is also preset. After step 5, if the actual operating time t of the battery system is greater than the preset operating time, the battery system automatically shuts down.

[0064] In a preferred embodiment, in step S5, the preset condition corresponding to the i-th pulse duration is determined as: whether the i-th pulse duration is less than 0.2 times the i-1-th pulse duration; preferably, the preset condition corresponding to the pulse number i is determined as: whether the pulse number i is not less than 3.

[0065] In a preferred embodiment, the aforementioned preset pulse time is 0.5s-1.5s; in this embodiment, the preset pulse time is preferably 1s.

[0066] Example 3

[0067] This embodiment provides a purging method for a hydrogen-air fuel cell system with high hydrogen utilization rate. The purging method can be implemented on a hydrogen-air fuel cell system as follows. The fuel cell system includes an adjustable speed fan, a fuel cell stack and a hydrogen supply system as in the previous embodiment, wherein:

[0068] The fuel cell stack is a fuel cell stack group formed by connecting two identical fuel cell stacks in series, each fuel cell stack includes a plurality of parallel flow channel graphite plates arranged in parallel and arranged vertically;

[0069] The adjustable speed fan provides the fuel cell stack with the air required for the chemical reaction;

[0070] The hydrogen supply system is also the same as that in the aforementioned embodiment, including a hydrogen supply device and a hydrogen buffer device. The hydrogen supply device includes a hydrogen tank, and the hydrogen tank is connected to the anode gas inlet of the previous fuel cell stack in the fuel cell stack through a pipeline, and a hydrogen pressure reducing valve is also arranged between the two, which is used to reduce the pressure of the hydrogen flowing out of the hydrogen tank; a hydrogen intake solenoid valve is also arranged on the pipeline between the hydrogen pressure reducing valve and the fuel cell stack, and the solenoid valve is a normally open solenoid valve, which is controlled to open and close for supplying hydrogen to the fuel cell stack; the hydrogen buffer device includes a buffer tank connected to the cathode of the latter fuel cell stack in the fuel cell stack through a pipeline, the volume of the buffer tank is 1.5L, and a first pulse valve is arranged between the buffer tank and the cathode of the latter fuel cell stack, the first pulse valve can receive an electrical signal to open and close, so that the fuel cell stack and the buffer tank are connected or closed; a second pulse valve is also arranged at the exhaust end of the buffer tank, and the pulse valve is used to realize the connection or disconnection between the buffer tank and the outside world;

[0071] During operation, the hydrogen pressure reducing valve and the hydrogen intake solenoid valve are controlled to open and close to supply hydrogen to the fuel cell stack, and the first pulse valve and the second pulse valve are controlled to blow the impurity gas in the fuel cell stack into the buffer tank through the connecting pipe under the action of the pressure difference between the fuel cell stack and the buffer tank, and then discharge it to the outside.

[0072] In this embodiment, the hydrogen gas inlet solenoid valve is normally open, and the first pulse valve and the second pulse valve are normally closed. The hydrogen gas supply device also includes the same purge assembly as in the previous embodiment, which is used to introduce inert gas into the fuel cell stack and purge before starting or after stopping the fuel cell stack; the purge assembly includes an inert gas storage tank, which is connected to the anode gas inlet of the previous fuel cell stack in the fuel cell stack through a pipeline, and an inert gas pressure reducing valve is also provided between the two; an inert gas gas inlet solenoid valve is also provided between the inert gas pressure reducing valve and the previous fuel cell stack, and the inert gas gas inlet solenoid valve is a normally closed solenoid valve.

[0073] After a certain amount of impurity gas accumulates in the fuel cell stack in the above-mentioned fuel cell system, the impurity gas is discharged by the following method, which includes the following steps:

[0074] S1. Start the battery system under monitoring and input the safe voltage V m and the total running time t s ;

[0075] S2, initialize the purge on-time to 0, and set the purge pulse interval of the battery stack system to t x,i initialization;

[0076] S3, then close the first pulse valve and the second pulse valve, and determine whether the voltage V of any single cell in the fuel cell stack is greater than the safety voltage V m :

[0077] When the single chip voltage V is greater than the safety voltage V m , then continue to determine whether the real-time single-chip voltage V is greater than the safety voltage V m , until the single chip voltage V is no greater than the safety voltage V m Proceed to the next step;

[0078] If the single-chip voltage V is not greater than the safety voltage V m , then the first pulse valve is opened so that the impurity gas accumulated in the battery system is purged into the buffer tank under the action of the pressure difference;

[0079] S4, in this embodiment, i is 0, that is, purge has not been performed, and it is determined whether the opening time of the first pulse valve is greater than the preset time 1s, 1s is the time required for a complete buffer purge:

[0080] If yes, close the first pulse valve to stop the purge buffer, and repeat steps S2-S4 to start a new round of purge;

[0081] If not, continue buffering until the opening time of the first pulse valve is greater than 1 second, complete the purge buffering, reduce the pressure difference between the fuel cell stack and the buffer unit, and proceed to the next step;

[0082] S5. After one purge is performed, the pulse number i=i+1;

[0083] S6, then determine whether the duration of the i-th pulse is less than 0.2 times the duration of the previous pulse:

[0084] If yes, it proves that the purging degree is not enough, then the first pulse valve and the second pulse valve are opened at the same time to continue purging, and after 1 second, the first pulse valve and the second pulse valve are closed at the same time to complete the purging, and steps S2-S5 are repeated to start a new round of purging;

[0085] If not, the determination is continued until the duration of the ith pulse is greater than 0.2 times the duration of the previous pulse.

[0086] In another preferred embodiment, in step S5, whether it is necessary to continue purging the buffer can be determined by judging whether the total number of pulses i meets 3 times. If it is less than 3 times, the purge needs to be continued. If it is not less than 3 times, the purge is completed and the first pulse valve and the second pulse valve are closed.

[0087] like Figure 3 As shown in the figure, it is the hydrogen utilization rate observation diagram of the fuel cell system after purging in this embodiment, 200mA / cm 2 Compared with the parallel air intake battery system and the series air intake battery system without the buffer device, the fuel cell system with the buffer device added under the current density in this embodiment can extend the pulse interval of the purge from 125s to 800s without parasitic power, and its fuel utilization rate of hydrogen fuel is improved to 99.21%.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A purging method for a hydrogen-air fuel cell system with high hydrogen utilization rate, characterized in that: The battery system comprises a hydrogen buffer device, the hydrogen buffer device comprises a buffer unit (10) connected to the cathode of a fuel cell stack (8), a first pulse valve (9) is arranged between the buffer unit (10) and the fuel cell stack (8), and a second pulse valve (11) is arranged at the exhaust end of the buffer unit (10). The purging method comprises the following steps: S1. Start the battery system and preset a safe voltage V m ; S2, initialization purge on time and purge pulse interval of the battery system t x,i ,in, i is the number of pulses, x is seconds; S3, closing the first pulse valve (9) and the second pulse valve (11), and determining the voltage of any single cell in the fuel cell stack (8). V Is it greater than the safety voltage? V m : If so, repeat the determination of the single chip voltage V Is it greater than the safety voltage V m ; If not, opening the first pulse valve (9) to allow the impurity gas accumulated in the battery system to enter the buffer unit (10); S4. Determine whether the opening time of the first pulse valve (9) is greater than a preset pulse time: If so, close the first pulse valve (9), and repeat steps S2-S4; If not, buffering continues until the opening time of the first pulse valve (9) is greater than the preset pulse time; After a pulse purge operation is performed, the pulse times i=i+ 1; S5. Determine the i Pulse duration or number of pulses i Whether the preset conditions are met: If so, the first pulse valve (9) and the second pulse valve (11) are opened simultaneously for buffering, and after the preset pulse time has passed, both are closed simultaneously, and a new round of purging is started; If not, continue to judge until the i Pulse duration or number of pulses i After the preset conditions are met, the first pulse valve (9) and the second pulse valve (11) are opened simultaneously for buffering, and after the preset pulse time has passed, the two are closed simultaneously to start a new round of purging.

2. The purging method of a hydrogen-air fuel cell system with high hydrogen utilization rate according to claim 1, characterized in that: In step S1, the total operating time of the battery system is also preset. When step S5 is completed, if the actual operating time of the battery system is t If the total operating time is greater than a preset time, the battery system shuts down.

3. The purging method of a hydrogen-air fuel cell system with high hydrogen utilization rate according to claim 1, characterized in that: In step S5, determine i The preset condition corresponding to the pulse duration is: i Is the duration of the second pulse less than 0.2 times the i- The duration of one pulse.

4. The purging method of a hydrogen-air fuel cell system with high hydrogen utilization rate according to claim 1, characterized in that: Determine the number of pulses i The corresponding preset conditions are: Pulse times i Is it not less than 3? 5. A purging method for a hydrogen-air fuel cell system with high hydrogen utilization rate as claimed in any one of claims 1 to 4, characterized in that: The preset pulse time is 0.5s-1.5s.

6. A purging method for a hydrogen-air fuel cell system with high hydrogen utilization rate as claimed in claim 5, characterized in that: The preset pulse time is 1s.

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