A method and device for shutting down and purging a hydrogen-oxygen fuel cell stack

Abstract

The present invention relates to a method and device for parking and purging a hydrogen-oxygen fuel cell stack. The device includes a hydrogen pipeline and an oxygen pipeline respectively connected to the hydrogen and oxygen chambers of the cell stack, and is also connected to a purge gas pipeline. Each pipeline is provided with an air inlet or exhaust solenoid valve, and the hydrogen and oxygen pipelines respectively contain a gas-water separator and a gas circulation pump. After parking is completed, the purge gas is sealed inside the cell stack for purging through the control of the solenoid valve, and the cell stack is discharged through the discharge resistor to consume the adsorbed hydrogen on the anode side of the electrode, thereby reducing the attenuation of the cell stack. During the entire purge and discharge process and after the purge is completed, the purge gas is completely sealed in the hydrogen and oxygen chambers of the cell stack. By circulating the purge gas in a closed environment, the residual liquid water in the cell stack is discharged, thereby increasing the service life of the cell stack.

Description

Technical Field

[0001] The present application belongs to the field of fuel cells, and specifically relates to a method and device for shutdown purging of a hydrogen-oxygen fuel cell stack. Background Art

[0002] A proton exchange membrane fuel cell (PEMFC) is a power generation device that efficiently converts the chemical energy of a fuel and an oxidant directly into electricity. Due to its significant advantages, including high energy conversion efficiency, environmental friendliness, fast startup, and minimal environmental pollution, PEMFC has become a leading power source for electric vehicles, stationary power plants, and various mobile power sources. The key materials and components of a PEMFC are primarily electrochemical catalysts, membrane electrodes, and bipolar plates, which are crucial for its performance and service life.

[0003] During the PEMFC power generation process, there are three ways for water to be transferred within the proton exchange membrane: 1. Concentration back diffusion: water molecules generated on the cathode side of the PEMFC penetrate from the cathode side to the anode side through the concentration gradient. 2. Electromigration: water molecules and H + Combined with H3O + 3. The form of pressure difference migration: In order to prevent the reverse polarity phenomenon, the pressure on the anode side is generally 5 to 10 kPa higher than that on the cathode side. Due to the pressure difference, the water molecules on the anode side will migrate to the cathode side. After the fuel cell completes normal operation, a large amount of liquid water and gaseous water will remain on the cathode and anode sides of the battery. Usually, gas is introduced into the hydrogen and oxygen chambers of the battery stack for purging, and the liquid water in the battery stack is discharged out of the battery stack along with the purge gas to avoid the accumulation of liquid water in the hydrogen and oxygen chambers of the battery stack, which causes the battery performance to deteriorate. This method usually consumes and emits a large amount of purge gas while discharging the liquid water inside the battery stack. During the purge process, a large amount of active hydrogen is still attached to the surface of the electrode anode, which is difficult to be purged and discharged. As a result, the single cell of the battery stack is still in a high voltage state for a long time after the purge is completed, causing corrosion of the carbon carrier in the catalyst layer of the electrode, affecting the performance of the battery stack. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings and deficiencies of the prior art and provides a method and device for shutting down and purging a hydrogen-oxygen fuel cell stack. This device uses a solenoid valve to seal purge gas within the hydrogen and oxygen chambers of the fuel cell stack. A gas circulation pump circulates the purge gas within these chambers to remove liquid water from the stack, significantly reducing purge gas usage. During the purge gas circulation process, a relay is opened and closed to control a discharge resistor, consuming active hydrogen adsorbed on the anode diffusion layer of the electrode while preventing localized polarity reversal.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A device for shutting down and purging a fuel cell stack, the device is provided with an oxygen pipeline and a hydrogen pipeline on the cathode and anode sides of the stack, respectively. An air intake solenoid valve is provided on each of the hydrogen and oxygen pipelines. At the same time, the purge gas pipeline is divided into two and connected to the hydrogen and oxygen inlets of the stack, respectively. A purge gas inlet solenoid valve is provided on each of the purge gas pipelines. A pressure sensor is provided at the hydrogen side outlet of the stack to measure the pressure on the hydrogen side of the stack. Two pipelines are connected to the outlet of the stack, one pipeline discharges the tail gas in the stack, and the other pipeline is connected to the hydrogen side inlet. A hydrogen side exhaust solenoid valve is provided on the pipeline discharging the tail gas, and a gas-water separator and a gas circulation pump are provided on the pipeline connected to the hydrogen side inlet. The structure of the oxygen side of the stack is the same as that of the hydrogen side. The device specifically includes:

[0007] A fuel cell stack, wherein the fuel cell stack is composed of n (n≥2 positive integer) fuel cell cells connected in series, and the end plates of the fuel cell stack are provided with a hydrogen side air inlet and a hydrogen side air outlet, and an oxygen side air inlet and an oxygen side air outlet;

[0008] A hydrogen pipeline is provided at the hydrogen side air inlet, and an oxygen pipeline is provided at the oxygen side air inlet. The hydrogen pipeline and the oxygen pipeline are connected to the hydrogen and oxygen chambers of the battery stack respectively. At the same time, a purge gas pipeline is provided at the hydrogen side air inlet and the oxygen side air inlet respectively, that is, the pipeline provided at the hydrogen side air inlet is the hydrogen side purge gas pipeline, and the pipeline provided at the oxygen side air inlet is the oxygen side purge gas pipeline;

[0009] At the hydrogen side outlet of the fuel cell stack, there are two pipelines: one is connected to the outside of the fuel cell stack through the gas pipeline, and the other is connected to the hydrogen inlet;

[0010] At the oxygen side outlet of the fuel cell stack, it is divided into two pipelines: one is connected to the outside of the fuel cell stack through the gas pipeline, and the other is connected to the oxygen inlet;

[0011] A hydrogen pressure sensor is provided at the hydrogen side outlet, and an oxygen pressure sensor is provided at the oxygen side outlet. The hydrogen pressure sensor and the oxygen pressure sensor are used to measure the hydrogen and oxygen chamber pressures in the fuel cell stack;

[0012] A discharge resistor and a relay are connected between the positive and negative electrodes of the fuel cell stack through wires, and the discharge of the fuel cell stack is achieved by turning the relay on and off.

[0013] Furthermore, the hydrogen pipeline is provided with a hydrogen-side hydrogen intake solenoid valve, and the oxygen pipeline is provided with an oxygen-side oxygen intake solenoid valve.

[0014] Furthermore, the purge gas pipeline is provided with an air intake solenoid valve, that is, the hydrogen side purge gas pipeline is provided with a hydrogen side purge gas intake solenoid valve, and the oxygen side purge gas pipeline is provided with an oxygen side purge gas intake solenoid valve.

[0015] Furthermore, the purge gas used for the purge pipeline can be a dry inert gas that does not chemically react with the electrode and does not chemically react with the fuel cell reaction gas; the inert gas is nitrogen.

[0016] Furthermore, the hydrogen side outlet end is connected to the pipeline outside the fuel cell stack, and the pipeline connected to the hydrogen side air inlet is connected to the hydrogen side outlet through a three-way joint; the hydrogen side outlet end is connected to the pipeline outside the fuel cell stack, and a hydrogen side exhaust solenoid valve is arranged between the hydrogen side pressure sensor; the pipeline between the hydrogen side outlet and the hydrogen side air inlet is provided with a hydrogen side gas-water separator and a hydrogen side gas circulation pump.

[0017] Furthermore, the oxygen side outlet end is connected to the pipeline outside the fuel cell stack, and the pipeline connected to the oxygen side gas inlet is connected to the oxygen side outlet through a three-way joint; an oxygen side exhaust solenoid valve is provided between the pipeline connected to the oxygen side outlet end outside the battery stack and the oxygen side pressure sensor; the pipeline between the oxygen side outlet and the oxygen side inlet is provided with an oxygen side gas-water separator and an oxygen side gas circulation pump.

[0018] A method for purging a fuel cell stack during shutdown uses the above-mentioned device. After the battery stack is shut down, purge gas is introduced into the battery stack. The gas and gas volume entering the hydrogen and oxygen chambers of the battery stack are controlled by two air inlet valves on the purge gas pipeline and the air inlet valve on the oxygen pipeline. The pressure sensors at the outlets of the hydrogen and oxygen chambers of the battery stack read the pressure on the hydrogen and oxygen sides of the battery stack. When the pressure reaches the required value, the gas circulation pumps on both sides of the hydrogen and oxygen are started, and the battery stack begins to discharge through relay control. When the lowest cell voltage of the battery stack is lower than 0.2V, the discharge stops, and the gas circulation pump continues to run. When the lowest voltage value is higher than 0.2V again, the discharge continues. This process ends after 20 minutes, but the pressure inside the battery is still maintained unchanged during the purge through the control of the hydrogen and oxygen side gas exhaust valves. Specifically, the following steps are included:

[0019] (1) Open the hydrogen side purge gas inlet solenoid valve, introduce purge gas into the hydrogen side, detect the hydrogen chamber pressure by the hydrogen side pressure sensor to be 0.25-0.30 bar, and close the hydrogen side purge gas inlet solenoid valve;

[0020] (2) Open the oxygen solenoid valve on the oxygen side and the purge gas inlet solenoid valve on the oxygen side, introduce purge gas and oxygen into the oxygen side, detect the oxygen chamber pressure of 0.3-0.40 bar through the oxygen side pressure sensor, and close the oxygen solenoid valve on the oxygen side and the purge gas inlet solenoid valve on the oxygen side;

[0021] (3) Open the hydrogen side purge gas inlet solenoid valve, introduce purge gas into the hydrogen side, detect the hydrogen chamber pressure through the hydrogen side pressure sensor, make the hydrogen chamber pressure 0.10-0.15 bar higher than the oxygen chamber pressure, and close the hydrogen side purge gas inlet solenoid valve;

[0022] (4) Turn on the hydrogen side gas circulation pump and the oxygen side gas circulation pump, and at the same time turn on the relay, and discharge the discharge resistor. When the minimum voltage of the battery stack is completely lower than 0.2V, stop discharging, turn off the relay, turn off the hydrogen side gas circulation pump and the oxygen side gas circulation pump, and the purge is completed.

[0023] Furthermore, the hydrogen side purge gas intake solenoid valve 2 intakes air in a pulsed manner, with each valve opening time being 100 to 200 ms and closed for 2 to 3 s; the oxygen side oxygen solenoid valve 3 and the oxygen side purge gas intake solenoid valve 4 start to intake air in a pulsed alternating manner, with the oxygen side oxygen intake solenoid valve 3 and the oxygen side purge gas intake solenoid valve 4 opening times ratio being 1:3 to 1:4, with each valve opening time being 100 to 200 ms and closed for 2 to 3 s.

[0024] Furthermore, in step (1), when the gas is introduced in a pulsed manner, if the hydrogen chamber pressure is higher than 0.30 bar, the hydrogen side purge gas inlet solenoid valve is closed, and the hydrogen side exhaust solenoid valve is opened in a pulsed manner, with each valve opening time being 100 to 200 ms, and is closed for 2 to 3 seconds until the hydrogen chamber pressure is 0.25-0.3 bar; in step (2), when the gas is introduced in a pulsed manner, if the oxygen chamber pressure is higher than 0.40 bar, the oxygen side oxygen solenoid valve and the oxygen side purge gas inlet solenoid valve are closed, and the oxygen side exhaust solenoid valve is opened in a pulsed manner, with each valve opening time being 100 to 200 ms, and is closed for 2 to 3 seconds until the oxygen chamber pressure is 0.30 to 0.40 bar.

[0025] Furthermore, in step (4), the voltage is completely lower than 0.2V means that: when the discharge voltage is lower than 0.2V for the first time, the discharge voltage will rebound after the relay 14 is turned off. The rebound value is lower than 0.2V, which means that the voltage is completely lower than 0.2V. The time from the start of discharge to the voltage being completely lower than 0.2V is the total discharge time; the opening time of the hydrogen side gas circulation pump 11 and the oxygen side gas circulation pump 12 is longer than the total discharge time.

[0026] After parking is completed, the device and method of the present invention controls the solenoid valve to seal the purge gas inside the battery stack for purging. At the same time, during the purge process, the battery stack is discharged through the discharge resistor to effectively consume the adsorbed hydrogen on the surface of the electrode anode, avoiding the single cell being in a high voltage state for a long time, which causes corrosion of the carbon support in the electrode catalyst layer, thereby reducing the attenuation of the battery stack. During the entire purge discharge process and after the purge is completed, the purge gas is completely sealed in the hydrogen and oxygen chambers of the battery stack, so that the purge gas circulates in the closed space to discharge the liquid water remaining in the battery stack. The purge gas is completely in a closed state during the purge process, and the purge gas is not discharged even after the purge is completed. This not only increases the service life of the fuel cell stack, but also minimizes the use of the purge gas. At the same time, after the purge is completed, the purge gas sealed inside the battery stack occupies the space of the hydrogen and oxygen chambers, preventing the liquid water that has not been discharged from contacting and soaking the diffusion layer on the hydrogen and oxygen sides of the electrode, affecting the performance of the battery stack.

[0027] Beneficial effects

[0028] While this purge device discharges the liquid water remaining inside the battery stack out of the battery stack, due to the intake ratio of oxygen to nitrogen in the purge gas on the oxygen side of the battery stack of 1:3 to 1:4, the active hydrogen attached to the anode side of the electrode can be effectively consumed by the oxygen in the purge gas, so that the batteries of the battery stack are prevented from being in a high voltage state after shutdown, which causes corrosion of the carbon carrier of the catalyst layer. At the same time, the high concentration of nitrogen in the purge gas also ensures that the cathode side of the electrode of the battery stack will not be in an oxygen-rich environment after the purge is completed, causing corrosion on the cathode side of the electrode and affecting the performance of the battery stack. In addition, this purge method reduces the amount of purge gas used in the purge process of the battery stack to a minimum. Finally, after the purge is completed, the purge gas sealed inside the battery stack can occupy the space of the hydrogen and oxygen cavities, preventing the liquid water that has not been discharged from contacting and soaking the diffusion layer on the hydrogen and oxygen sides of the electrode, affecting the performance of the battery stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the purge device;

[0030] In the figure: 1. Hydrogen side hydrogen inlet solenoid valve, 2. Hydrogen side purge gas inlet solenoid valve, 3. Oxygen side oxygen inlet solenoid valve, 4. Oxygen side purge gas inlet solenoid valve, 5. Hydrogen side exhaust solenoid valve, 6. Oxygen side exhaust solenoid valve, 7. Hydrogen side pressure sensor, 8. Oxygen side pressure sensor, 9. Hydrogen side gas-water separator, 10. Oxygen side gas-water separator, 11. Hydrogen side gas circulation pump, 12. Oxygen side gas circulation pump, 13. Discharge resistor, 14. Relay, 15. Hydrogen side air inlet, 16. Oxygen side air inlet, 17. Hydrogen side air outlet, 18. Oxygen side air outlet. DETAILED DESCRIPTION

[0031] In order to make those skilled in the art understand the purpose, features and effects of the present invention, the present invention is described in detail by the following specific embodiments in conjunction with the accompanying drawings.

[0032] Example

[0033] A fuel cell stack shutdown purge device, a fuel cell stack, wherein the fuel cell stack is composed of n (n≥2 positive integer) fuel cell cells connected in series, a hydrogen side air inlet 15 and a hydrogen side air outlet 17, an oxygen side air inlet 16 and an oxygen side air outlet 18 are provided on the end plate of the fuel cell stack; a hydrogen pipeline is provided at the hydrogen side air inlet 15, an oxygen pipeline is provided at the oxygen side air inlet 16, and a purge gas pipeline is provided at the hydrogen side air inlet 15 and the oxygen side air inlet 16, that is, the pipeline provided at the hydrogen side air inlet 15 is a hydrogen side purge gas pipeline, and the pipeline provided at the oxygen side air inlet 16 is an oxygen side purge gas pipeline; the hydrogen side air outlet 17 of the fuel cell stack is divided into two pipelines: one is through the gas pipeline One line is connected to the outside of the fuel cell stack as the hydrogen-side exhaust pipe, and the other is connected to the hydrogen inlet 15. At the oxygen-side outlet 18 of the fuel cell stack, two lines are split: one is connected to the outside of the fuel cell stack via a gas line as the oxygen-side exhaust pipe, and the other is connected to the oxygen inlet 16. A hydrogen pressure sensor 7 is installed at the hydrogen-side outlet 17, and an oxygen pressure sensor 8 is installed at the oxygen-side outlet 18. The hydrogen pressure sensor 7 and the oxygen pressure sensor 8 are used to measure the hydrogen and oxygen chamber pressures in the fuel cell stack. A discharge resistor 13 and a relay 14 are connected between the positive and negative current collectors of the fuel cell stack via wires. The discharge of the fuel cell stack is controlled by turning the relay 14 on and off. A hydrogen-side hydrogen inlet solenoid valve 1 is installed in the hydrogen line, and an oxygen-side oxygen inlet solenoid valve is installed in the oxygen line. The purge gas pipelines are equipped with inlet solenoid valves, namely, a hydrogen-side purge gas inlet solenoid valve 2 is provided in the hydrogen-side purge gas pipeline, and an oxygen-side purge gas inlet solenoid valve 3 is provided in the oxygen-side purge gas pipeline. The purge gas used in the purge pipelines is nitrogen. The hydrogen-side outlet 17 is connected to a pipeline external to the fuel cell stack, and the pipeline connected to the hydrogen-side inlet 15 is connected to the hydrogen-side outlet 17 via a tee joint. The hydrogen-side outlet 18 is connected to a pipeline external to the fuel cell stack, and a hydrogen-side exhaust solenoid valve 5 is provided between the hydrogen-side pressure sensor 7. The pipeline between the hydrogen-side outlet 17 and the hydrogen-side inlet 15 is equipped with a hydrogen-side gas-water separator 9 and a hydrogen-side gas circulation pump 11, with the hydrogen-side gas-water separator 9 located near the hydrogen-side outlet 17 and the hydrogen-side gas circulation pump 11 located near the hydrogen-side inlet 15. An oxygen-side exhaust solenoid valve 6 is provided between the pipeline connected to the oxygen-side outlet 18 and the oxygen-side pressure sensor 8. The pipeline connecting the oxygen side gas outlet 18 to the oxygen side gas inlet 16 is provided with an oxygen side gas-water separator 10 and an oxygen side gas circulation pump 12. The oxygen side gas-water separator 10 is close to the oxygen side gas outlet 18, and the oxygen side gas circulation pump 12 is close to the oxygen side gas inlet 16.

[0034] The fuel cell stack that has completed normal discharge work is purged and discharged, and the hydrogen side hydrogen inlet solenoid valve 1, the oxygen side oxygen solenoid valve 3, the hydrogen side exhaust solenoid valve 5, and the oxygen side exhaust solenoid valve 6 are kept closed.

[0035] Open the hydrogen side purge gas inlet solenoid valve 2 on the purge gas pipeline, and continuously introduce dry nitrogen into the purge gas pipeline. The hydrogen side purge gas inlet solenoid valve 2 is opened in a pulsed manner. The hydrogen side purge gas inlet solenoid valve 2 opens for 200ms each time and closes for 2s. The hydrogen chamber pressure value of the battery stack is measured by the hydrogen side pressure sensor 7. When the hydrogen chamber pressure reaches 0.25-0.3bar, the hydrogen side purge gas inlet solenoid valve 2 is closed. When the hydrogen chamber pressure is higher than 0.30bar, the hydrogen side exhaust solenoid valve 5 is opened in a pulsed manner. The valve opening time is 150ms each time and closed for 2s until the hydrogen chamber pressure is 0.25-0.30bar, and then the hydrogen side exhaust solenoid valve 5 is closed.

[0036] Open the oxygen side oxygen solenoid valve 3 and the oxygen side purge gas intake solenoid valve 4 on the purge gas pipeline, and introduce oxygen into the oxygen pipeline. Dry nitrogen is continuously introduced into the purge gas pipeline. The oxygen side oxygen intake solenoid valve 3 and the oxygen side purge gas intake solenoid valve 4 start to intake air in a pulse alternating manner. The valve opening ratio of the oxygen side oxygen intake solenoid valve 3 and the oxygen side purge gas intake solenoid valve 4 is 1:3. Each valve opening time is 200ms and closed for 2s. The oxygen chamber pressure value of the battery stack is measured by the oxygen side pressure sensor 8. If the pressure is 0.30-0.40 bar, the oxygen side oxygen intake solenoid valve 3 and the oxygen side purge gas intake solenoid valve 4 are closed. If the oxygen chamber pressure is higher than 0.40 bar, the oxygen side exhaust solenoid valve 6 is opened in a pulsed manner, with each valve opening time of 150ms and closed for 2s, until the oxygen chamber pressure reaches 0.30-0.40 bar, and then the solenoid 6 is closed.

[0037] Open the hydrogen side purge gas inlet solenoid valve 2 on the purge gas pipeline, and continuously introduce dry nitrogen into the purge gas pipeline. The hydrogen side purge gas inlet solenoid valve 2 is opened in a pulsed manner. The hydrogen side nitrogen inlet solenoid valve 2 is opened for 200ms each time and closed for 2s. The hydrogen chamber pressure value of the battery stack is measured by the hydrogen side pressure sensor 7 to ensure that the hydrogen side pressure is 0.10 to 0.15 bar higher than the oxygen side pressure.

[0038] When the hydrogen and oxygen chamber pressures reach the required level, the hydrogen side gas circulation pump 11 and the oxygen side gas circulation pump 12 are turned on, with the circulation pump speeds of both being 3000 r / min. Simultaneously, the relay 14 is turned on, causing the battery stack to begin discharging through the discharge resistor 13. When the lowest cell voltage of the battery stack falls below 0.2V, the relay 14 is turned off, stopping the discharge. After stopping the discharge, the battery stack voltage will recover. When it recovers to above 0.2V, the relay 14 is turned on to continue discharging the battery stack. This cycle repeats until the voltage is completely below 0.2V, at which point the relay 14 is turned off, stopping the discharge. After 20 minutes, the purge discharge process is complete, the hydrogen side gas circulation pump 11 and the oxygen side gas circulation pump 12 are simultaneously turned off, the hydrogen side hydrogen inlet solenoid valve 1 and the oxygen side oxygen inlet solenoid valve 3, the hydrogen side purge gas inlet valve 2 and the oxygen side oxygen inlet solenoid valve 4, the hydrogen side exhaust solenoid valve 5, and the oxygen side exhaust solenoid valve 6 are all closed. The relay 14 is also closed, and the discharge resistor 13 stops discharging the battery stack.

[0039] In this application, the hydrogen-side gas circulation pump 11 and the oxygen-side gas circulation pump 12 are not shut down immediately after the discharge is completed, but continue to purge and remove the liquid water inside the stack. The duration of the discharge process can be adjusted by adjusting the size of the discharge resistor. The selection standard of the discharge resistor in this application is to ensure that the discharge process lasts less than 20 minutes. The hydrogen-side gas circulation pump 11 and the oxygen-side gas circulation pump 12 are turned on for 20 minutes. The opening time of the gas circulation pump can be determined based on the number of stack sections to be purged and the maximum discharge power value of the stack.

Claims

1. A method for purging a fuel cell stack during shutdown, characterized in that: A shutdown purge device for a hydrogen-oxygen fuel cell stack is used, the device comprising: A fuel cell stack, wherein the fuel cell stack is composed of multiple fuel cell cells connected in series, and an end plate of the fuel cell stack is provided with a hydrogen side air inlet (15) and a hydrogen side air outlet (17), an oxygen side air inlet (16) and an oxygen side air outlet (18); A hydrogen pipeline is provided at the hydrogen side air inlet (15), an oxygen pipeline is provided at the oxygen side air inlet (16), and a purge gas pipeline is provided at each of the hydrogen side air inlet (15) and the oxygen side air inlet (16); The hydrogen side gas outlet (17) of the fuel cell stack is divided into two pipelines: one is connected to the outside of the fuel cell stack through a gas pipeline, and the other is connected to the hydrogen gas inlet (15); The oxygen side gas outlet (18) of the fuel cell stack is divided into two pipelines: one is connected to the outside of the fuel cell stack through a gas pipeline, and the other is connected to the oxygen gas inlet (16); A hydrogen pressure sensor (7) is provided at the hydrogen side outlet (17), and an oxygen pressure sensor (8) is provided at the oxygen side outlet (18) for measuring the hydrogen and oxygen chamber pressures in the fuel cell stack; A discharge resistor (13) and a relay (14) are connected between the positive and negative electrodes of the fuel cell stack via a wire, and the discharge of the fuel cell stack is realized by turning on and off the relay (14); The method comprises the following steps: (1) Open the hydrogen side purge gas inlet solenoid valve (2), introduce purge gas into the hydrogen side, detect the hydrogen chamber pressure at 0.25 to 0.30 bar through the hydrogen side pressure sensor (7), and close the hydrogen side purge gas inlet solenoid valve (2); (2) Open the oxygen side oxygen solenoid valve (3) and the oxygen side purge gas inlet solenoid valve (4), introduce purge gas and oxygen into the oxygen side, detect the oxygen chamber pressure as 0.3-0.40 bar through the oxygen side pressure sensor (8), and close the oxygen side oxygen solenoid valve (3) and the oxygen side purge gas inlet solenoid valve 4); (3) Open the hydrogen side purge gas inlet solenoid valve (2), introduce purge gas into the hydrogen side, detect the hydrogen chamber pressure through the hydrogen side pressure sensor (7), make the hydrogen chamber pressure 0.10 to 0.15 bar higher than the oxygen chamber pressure, and close the hydrogen side purge gas inlet solenoid valve (2); (4) Turn on the hydrogen side gas circulation pump (11) and the oxygen side gas circulation pump (12), and at the same time turn on the relay (14), and the discharge resistor (13) discharges. When the lowest cell voltage of the battery stack is completely lower than 0.2V, the discharge is stopped, the relay (14) is turned off, and the hydrogen side gas circulation pump (11) and the oxygen side gas circulation pump (12) are turned off, and the purge is completed.

2. The purging method according to claim 1, wherein: The hydrogen pipeline is provided with a hydrogen-side hydrogen inlet electromagnetic valve (1), and the oxygen pipeline is provided with an oxygen-side oxygen inlet electromagnetic valve (3).

3. The purging method according to claim 1, wherein: An air intake solenoid valve is provided in the purge air pipeline.

4. The method according to claim 1, wherein: The purge gas used in the purge pipeline is a dry inert gas that does not chemically react with the electrode and does not chemically react with the fuel cell reaction gas; the inert gas is nitrogen.

5. The method according to claim 1, wherein: The hydrogen side gas outlet (17) is connected to a pipeline outside the fuel cell stack, and the pipeline connected to the hydrogen side gas inlet (15) and the hydrogen side gas outlet (17) are connected via a three-way joint; The hydrogen side gas outlet (17) is connected to a pipeline outside the fuel cell stack, and a hydrogen side exhaust solenoid valve (5) is provided between the hydrogen side gas outlet (17) and the hydrogen side pressure sensor (7); The pipeline between the hydrogen side gas outlet (17) and the hydrogen side gas inlet (15) is provided with a hydrogen side gas-water separator (9) and a hydrogen side gas circulation pump (11).

6. The method according to claim 1, wherein: The oxygen side gas outlet (18) is connected to a pipeline outside the fuel cell stack, and the pipeline connected to the oxygen side gas inlet (16) and the oxygen side gas outlet (18) are connected via a three-way joint; An oxygen-side exhaust solenoid valve (6) is provided between the oxygen-side gas outlet (18) end connected to a pipeline outside the battery stack and the oxygen-side pressure sensor (8); The pipeline between the oxygen side gas outlet (18) and the oxygen side gas inlet (16) is provided with an oxygen side gas-water separator (10) and an oxygen side gas circulation pump (12).

7. The method according to claim 1, characterized in that The hydrogen side purge gas intake solenoid valve (2) intakes gas in a pulsed manner, with each valve opening time being 100 to 200 ms and closed for 2 to 3 s; the oxygen side oxygen solenoid valve (3) and the oxygen side purge gas intake solenoid valve (4) start intake in a pulsed alternating manner, with the ratio of the number of valve openings of the oxygen side oxygen intake solenoid valve (3) and the oxygen side purge gas intake solenoid valve 4 being 1:3 to 1:4, with each valve opening time being 100 to 200 ms and closed for 2 to 3 s.

8. The purging method according to claim 1 or 7, characterized in that: In step (1), when the pulsed air intake is performed, if the hydrogen chamber pressure is higher than 0.30 bar, the hydrogen side purge gas intake solenoid valve (2) is closed, and the hydrogen side exhaust solenoid valve (5) is opened in a pulsed manner, with each valve opening time being 100 to 200 ms, and is closed for 2 to 3 seconds until the hydrogen chamber pressure is 0.25 to 0.3 bar; in step (2), when the pulsed air intake is performed, if the oxygen chamber pressure is higher than 0.40 bar, the oxygen side oxygen solenoid valve 3 and the oxygen side purge gas intake solenoid valve (4) are closed, and the oxygen side exhaust solenoid valve (6) is opened in a pulsed manner, with each valve opening time being 100 to 200 ms, and is closed for 2 to 3 seconds until the oxygen chamber pressure is 0.30 to 0.40 bar.

9. The method according to claim 1, characterized in that In step (4), the voltage is completely lower than 0.2V means that: when the discharge voltage is lower than 0.2V for the first time, the discharge voltage will rebound after the relay (14) is turned off, and the rebound value is lower than 0.2V, which means that the voltage is completely lower than 0.2V, and the time from the start of discharge to the voltage being completely lower than 0.2V is the total discharge time; the opening time of the hydrogen side gas circulation pump (11) and the oxygen side gas circulation pump (12) is longer than the total discharge time.

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