CN116072936A - An on-line detection device and method for proton exchange membrane fuel cell stack leakage - Google Patents

Abstract

The invention relates to the technical field of fuel cells, in particular to an on-line detection device and method for proton exchange membrane fuel cell stack leakage. Including: determining the detection type, the detection type includes: reactant transfer leak detection, oxidizer-coolant transfer leak detection and fuel-coolant transfer leak detection; The oxidant inlet supplies the corresponding gas source, which is an inert gas or fuel; a potential difference is applied to the fuel cell of the stack, and the transfer current between the anode and the cathode of the fuel cell is measured; according to the reference current and the measured transfer current , to determine whether there is a leak corresponding to the detection type in the fuel cell. The detection device and method of the present invention can detect the single-cell batteries in the electric stack one by one, can effectively detect the leakage of each cell in the electric stack, is less affected by external interference, and is not affected by the number of cells and the active area of the electric stack. Versatile.

Description

An on-line detection device and method for proton exchange membrane fuel cell stack leakage

technical field

The invention relates to the technical field of fuel cells, in particular to an on-line detection device and method for proton exchange membrane fuel cell stack leakage.

Background technique

A proton exchange membrane fuel cell (PEMFC) is a high-efficiency device that is not limited by the Carnot cycle of an internal combustion engine, and directly converts the chemical energy in fuel hydrogen (pure hydrogen or reformed gas) and oxidant (pure oxygen or air) It is converted into electric energy, and its product is only water, which is very friendly to the environment. Therefore, PEMFC is considered to be one of the most promising clean energy sources and has been widely promoted in the field of vehicle energy. Carbon-friendly goals.

There are several routine methods for detecting leaks in PEMFC stacks. First, the presence of hydrogen can be detected by monitoring the oxidant off-gas. When hydrogen gas is detected in the oxidant exhaust stream, this may indicate a leak. One problem with this approach, however, is that hydrogen may be present in the oxidant exhaust stream for reasons other than fuel leaks. For example, if the cathode is starved of oxygen, protons arriving at the cathode from the anode may recombine with electrons to form hydrogen gas. There are many reasons for the above-mentioned hypoxia, for example, hypoxia may be due to sudden increase in power output demand, compressor failure, and liquid water accumulation causing blockage of oxidant flow field channels, etc. Another problem with using hydrogen as a leak indicator is that hydrogen may react in the fuel cell, especially when there is a catalyst at the three-phase interface between the electrolyte and the electrode, hydrogen is very prone to catalytic reactions. Therefore, there is a high probability that the hydrogen will be partially or fully catalyzed before being exposed to the detector located in the oxidant exhaust manifold, so the detected hydrogen concentration may not accurately reflect the actual leak.

Another way to detect leaks in a PEMFC stack is by monitoring the fuel exhaust to detect the presence of oxygen. The disadvantage of this approach is that there are other potential sources of oxygen at the anode. For example, oxygen is sometimes introduced into the feed stream of fuel reformate (where carbon monoxide is present) to attenuate the effects of catalyst poisoning. Another important source of anode oxygen is water. When fuel is in short supply, water can be converted into oxygen, electrons and protons by catalytic reaction at the anode. Therefore, the detected oxygen concentration may not accurately reflect the actual leakage.

PEMFC stacks are also typically checked for leaks prior to operation for power generation, such as after assembly or during routine maintenance. Generally, the pressure difference method is adopted, such as checking for leakage from the fuel chamber to the oxidant chamber, closing the coolant inlet and outlet manifolds, the fuel outlet manifold and the oxidizer inlet manifold with on-off valves, and the oxidizer outlet manifold being connected to the inlet port of the flowmeter, and the flow rate The outlet end of the meter is connected to the atmosphere, and compressed air or inert gas is fed into the fuel inlet manifold, and a certain pressure (10-100kPa) is maintained, and the reading of the flow meter when it reaches stability is recorded, which is the flow rate leaked from the fuel chamber to the oxidant chamber.

The above conventional methods have a common problem. The detected leakage is the result of the entire PEMFC stack. It is not clear which cell or cells are leaking. It is usually necessary to disassemble the stack and retest the leak in groups. Until each leaky unit is found, the above iterative process is complicated, undesirable, time-consuming, and easily causes irreversible damage to the stack.

Therefore, it is necessary to develop a simple and reliable method to detect the leakage of PEMFC stacks and accurately identify the specific leaking unit.

Contents of the invention

The invention provides an on-line detection device and method for proton exchange membrane fuel cell stack leakage, which solves at least one technical problem in the prior art.

A technical solution of the present invention is as follows: an online detection method for proton exchange membrane fuel cell stack leakage, comprising:

S10: Determine the detection type, the detection type includes: reactant transfer leak detection, oxidizer-coolant transfer leak detection, and fuel-coolant transfer leak detection;

S20: According to the detection type, supply corresponding gas sources to the fuel inlet, coolant inlet and oxidant inlet of the stack respectively, and the gas sources are inert gas or fuel;

S30: applying a potential difference on the fuel cell of the stack, and measuring the transfer current between the anode and the cathode of the fuel cell;

S40: According to the reference current and the measured transfer current, it is judged whether there is leakage corresponding to the detection type in the fuel cell.

Further, the step S20 includes:

When the detection type is reactant transfer leak detection, supply fuel to the fuel inlet at a first pressure, and supply inert gas to the oxidizer inlet at a second pressure;

When the detection type is oxidizer-coolant transfer leak detection, supply fuel to the fuel inlet at a third pressure, supply fuel to the coolant inlet at a fourth pressure, and supply inert gas to the oxidizer inlet at a fifth pressure;

When the detection type is fuel-coolant transfer leak detection, the fuel inlet is supplied with fuel at a sixth pressure, the coolant inlet is supplied with fuel at a seventh pressure, and the oxidizer inlet is supplied with fuel at an eighth pressure.

Further, the first pressure is greater than the second pressure, the fourth pressure is greater than the third pressure and the fifth pressure, the fifth pressure is greater than or equal to the third pressure, and the seventh pressure is greater than the sixth pressure and the fifth pressure. Eight pressures, the eighth pressure being greater than or equal to the sixth pressure.

Further, the step S30 includes:

When the detection type is reactant transfer leakage detection, the cathode voltage of the fuel cell is greater than the anode voltage;

When the detection type is oxidant-coolant transfer leakage detection, the cathode voltage of the fuel cell is greater than the anode voltage;

When the detection type is fuel-coolant transfer leak detection, the anode voltage of the fuel cell is greater than the cathode voltage.

Further, the step S30 includes:

When there are multiple fuel cells in the stack, apply a potential difference to at least one fuel cell in the stack, and measure the transfer current between the anode and cathode of one or more fuel cells;

Apply a potential difference to all the fuel cells in the stack in turn, and measure the transfer current of one or more fuel cells;

The step S40: according to the measured transfer current and the reference current of the fuel cell, it is judged whether there is a corresponding type of leakage in one or more fuel cells.

Further, when a potential difference is applied to multiple fuel cells, the transfer current between the anode of the first fuel cell and the cathode of the last fuel cell is measured.

Further, the step S40 includes: when the measured transfer current is greater than the reference current, the fuel cell has a leak of a corresponding detection type.

Another technical solution of the present invention provides: an online proton exchange membrane fuel cell stack leakage detection device for implementing any of the above-mentioned proton exchange membrane fuel cell stack leakage online detection methods, including:

Fuel gas source: used to deliver fuel to the corresponding inlet according to the detection type;

Inert gas source: used to deliver inert gas to the corresponding inlet according to the detection type;

Constant voltage power supply: connect the anode and cathode of the fuel cell of the electric stack, and apply a potential difference to the fuel cell of the electric stack;

Current meter: connected in series with the constant voltage power supply, used to measure the transfer current between the anode and cathode of the fuel cell.

Further, it also includes:

Path selector; respectively connected to the constant voltage power supply and each fuel cell of the electric stack, used to select one or more fuel cells in the electric stack to be connected to the constant voltage power supply;

Recorder: connected with the current meter, used to obtain the data of the current meter;

Controller: respectively connected to the constant voltage power supply and the path selector, used to control the path selector to sequentially select the anode and cathode of a single battery or multiple batteries to connect with the constant voltage power supply and control the output voltage of the constant voltage power supply.

Further, both the fuel gas source and the fuel gas source are connected to the inlet of the electric stack through a pressure valve, and the pressure valve is used to deliver the pressure.

Beneficial effects of the present invention: the device of the present invention can be integrated into a fuel cell system, and when the PEMFC stack is in a power station or vehicle-mounted operation site, it can directly perform leak detection when the corresponding gas supply conditions are met, and can be used as an on-site maintenance method. The detection device and method of the present invention adopt an electrochemical method for testing, and its detection accuracy depends on the current meter which can realize high-precision measurement, and the testing accuracy is much higher than that of the prior art. The detection device and method of the present invention can detect the single-cell batteries in the electric stack one by one, can effectively detect the leakage of each cell in the electric stack, is less affected by external interference, and is not affected by the number of cells and the active area of the electric stack. Versatile. The invented detection device and method can detect the single battery in the electric stack one by one, which can effectively detect which battery leaks, and more specifically, can clearly determine whether it is fuel-oxidant transfer leakage, oxidant-coolant transfer leakage, or oxidant-oxidant transfer leakage. Coolant leaks. The automatic detection recorder of the present invention realizes automatic detection without manual intervention, saves labor costs, has more stable data, can directly participate in product diagnosis, and is especially applicable to reliability selection and evaluation of PEMFC core components.

Description of drawings

Fig. 1 is a flowchart of the detection method of the present invention.

Fig. 2 is a structural schematic diagram of the implementation of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only the embodiments of the present invention Some examples, but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

In an embodiment of the present invention, FIG. 1 is a structural schematic diagram provided according to specific steps of an online detection method for proton exchange membrane fuel cell stack leakage according to the present invention. As shown in Figure 1, the method of the present invention specifically comprises the following four steps:

S10: Determine a detection type, the detection type including: reactant transfer leak detection, oxidant-coolant transfer leak detection, and fuel-coolant transfer leak detection.

S20: According to the detection type, supply corresponding gas sources to the fuel inlet, the coolant inlet, and the oxidant inlet of the cell stack respectively, and the gas sources are inert gas or fuel.

S30: applying a potential difference on the fuel cell of the stack, and measuring the transfer current between the anode and the cathode of the fuel cell.

S40: According to the reference current and the measured transfer current, it is judged whether there is leakage corresponding to the detection type in the fuel cell.

Wherein, when there are multiple fuel cells in the stack, a potential difference is applied to at least one fuel cell in the stack, and the transfer current between the anode and cathode of one or more fuel cells is measured. Apply a potential difference to all the fuel cells in the stack in turn, and measure the transfer current of one or more fuel cells. According to the measured transfer current and reference current of the fuel cell, it is judged whether there is a corresponding type of leakage in each one or more fuel cells. When a potential difference is applied across multiple fuel cells, the transfer current is measured between the anode of the first fuel cell and the cathode of the last fuel cell.

The aforementioned "transfer leak" refers to a situation where reactants may mix with each other or with the coolant within the fuel cell due to sealing defects in the MEA, the flow field plate and/or between the two. More specifically, "reactant transfer leak" refers to a transfer leak where fuel and oxidant may mix. Typical sources of "reactant transfer leaks" include small pinholes in the MEA membrane or cracked fuel-oxidizer bipolar plates. A "fuel-to-coolant transfer leak" refers to a transfer leak in which fuel and coolant may mix. "Oxidant to coolant transfer leak" refers to a transfer leak where oxidizer and coolant may mix. Typical sources of fuel-coolant and oxidant-coolant transfer leaks are cracked fuel-coolant flow field plates and cracked oxidant-coolant flow field plates, respectively. "Reactant-coolant transfer leak" generally refers to fuel-coolant and oxidant-coolant transfer leaks.

The "fuel" in the above step S20 refers to a pure hydrogen gas stream or a hydrogen-containing reformed gas stream; "oxidant" refers to a pure oxygen gas stream or a gas stream containing oxygen, such as air. "Inert gas" refers to a gas that is substantially non-reactive in a fuel cell stack, such as nitrogen, argon, helium, or carbon dioxide.

The "transferred current" in the above step S30 refers to the current flowing through the fuel cell due to hydrogen oxidation on one electrode of the fuel cell.

Another technical solution of the present invention provides an on-line detection device capable of implementing any of the above-mentioned on-line detection methods for proton exchange membrane fuel cell stack leakage.

Refer to Figure 2 for the structure of the proton exchange membrane fuel cell stack. Specifically, it consists of an upper end plate 94, a lower end plate 96 and batteries 108a-108d. The battery stack 90 shows 4 batteries for illustrative purposes only. A typical fuel cell stack contains tens to hundreds of batteries, and the actual number of batteries in the battery stack 90 depends on specific application scenarios. Batteries 108a-108d are mainly composed of oxidizer plates with coolant flow field, fuel plates and MEA (115a-115d), gas source 100 is detachably connected to fuel inlet manifold 102 through pipeline 104, and is the cell stack 90 To provide gas flow, pressure valve 106 regulates the pressure of the gas flow supplied to stack 90 . A gas source 120 is detachably connected to an oxidizer inlet manifold 122 through a pipe 124 to provide gas flow to the stack 90 , and a pressure valve 126 regulates the pressure of the gas flow supplied to the stack 90 . A gas source 110, detachably connected to a coolant inlet manifold 112 via a line 114 for supplying fuel to the stack 90, provides gas flow to the stack 90, wherein a pressure valve 116 regulates the pressure of the fuel supplied to the stack 90 . Gas supplied to the stack 90 is exhausted through a corresponding exhaust manifold. Wherein, the fuel inlet manifold 102 is the fuel inlet of the stack, the oxidant inlet manifold 122 is the oxidizer inlet of the stack, and the coolant inlet manifold 112 is the coolant inlet of the stack.

The proton exchange membrane fuel cell stack leakage on-line detection device of the present invention specifically includes: a fuel gas source, an inert gas source, a constant voltage power supply, a current meter, a path selector, a recorder and a controller as shown in Fig. 1 and Fig. 2 .

The fuel gas source is used to deliver fuel to the corresponding inlet according to the detection type. The inert gas source is used to deliver inert gas to the corresponding inlet according to the detection type. The above-mentioned gas source 100, gas source 110, and gas source 120 will be selected from fuel gas source and inert gas source according to the detection type. Both the fuel gas source and the fuel gas source are connected to the inlet of the electric stack through a pressure valve, and the pressure valve is used to deliver the pressure. The specific pressure valves are pressure valve 106 , pressure valve 116 and pressure valve 126 .

The constant voltage power supply is connected to the anode and cathode of the fuel cells of the electric stack, and is used to apply a potential difference to the fuel cells of the electric stack. A particular constant voltage power supply 150 is connected to the stack 90 to apply a selected potential difference across at least one cell in the stack, preferably the constant voltage power supply 150 applies a selected potential difference to each cell in the stack.

The current meter 160 can be connected to any cell of the electric stack to which a potential difference is applied, for measuring the transfer current passing through the cell, specifically, the current meter and the cell The constant voltage power supply is connected in series for measuring the transfer current between the anode and the cathode of the fuel cell.

The path selector is respectively connected with the constant voltage power supply and each fuel cell of the electric stack, and is used to select one or more fuel cells in the electric stack to be connected with the constant voltage power supply. 2 shown connections.

The recorder is connected with the current meter and is used to acquire the data of the current meter. The controller is respectively connected with the constant voltage power supply and the path selector, and is used to control the path selector to sequentially select the anode and cathode of a single battery or multiple batteries to connect with the constant voltage power supply and control the output voltage of the constant voltage power supply. The controller can also control the current meter to read the current value in the detection loop and record it through the recorder.

The following are specific embodiments of the present invention:

Example 1

The detection type of this embodiment is reactant transfer leakage detection, the gas source 100 is a fuel gas source and supplies fuel gas to the fuel manifold at a first pressure, the gas source 120 is an inert gas source, and supplies the fuel gas to the oxidant inlet manifold at a second pressure Inert gas is supplied to maintain a fixed pressure difference between the first pressure and the second pressure, ensuring that the first pressure is greater than the second pressure. The pressure difference between the first pressure and the second pressure can be between 0kPa and 70kPa, preferably between 10kPa and 40kPa. Then apply a potential difference on at least one battery (preferably one) in the stack to form a closed loop, so that the cathode of the fuel cell is more positive than the anode (the anode is the reference electrode), specifically referring to the voltage of the cathode is greater than the voltage of the anode , wherein the potential difference can be between 0.2V and 0.9V, preferably about 0.5V. Measure the transfer current. When the transfer current is greater than the reference current, it indicates that there is reactant transfer leakage in this battery. The reference current is obtained by the user's pre-test, especially in the battery damage test without leakage. Apply a potential difference to all the cells of the battery stack one by one until the leak detection of all single cells in the stack is completed.

For example, gas source 100 provides fuel, gas source 120 provides inert gas, and gas source 110 may provide coolant or may not provide any gas or liquid. Gas pressure valves 106 and 126 are adjusted to ensure that fuel is supplied to stack 90 at a higher pressure than the inert gas. Furthermore, in the apparatus of FIG. 2 , regulating the gas pressure valve 116 prevents the gas in the gas source 110 from being supplied to the stack 90 . The constant voltage power supply 150 implements a potential difference on one battery in the electric stack 90 , wherein one battery of the electric stack is sequentially selected by the path selector to be connected to the constant voltage power supply. The ammeter 160 is connected in series with the cross-current power supply, and is used to measure the transfer current through the battery, for example, to implement a potential difference on the 108b battery, and the ammeter is connected as shown in the figure. In the absence of reactant transfer leakage, a very small amount (the membrane itself has a certain gas permeability) of hydrogen diffuses on the membrane, resulting in a small constant transfer current. Reactant transfer leakage can lead to an increase in the rate of hydrogen transfer to the cathode side of the fuel cell, with a corresponding increase in the rate of hydrogen oxidation at the cathode, which in turn leads to an increase in the transfer current, which can be detected by an amperometric meter. The detected transfer current of a single cell is compared with the reference transfer current, and if the detected transfer current is higher than the reference transfer current, it indicates that there is reactant transfer leakage in this cell.

Example 2

The detection type of this embodiment is oxidant-coolant transfer leakage detection, the gas source 100 is the fuel gas source and supplies fuel gas to the fuel manifold at the third pressure, and the gas source 110 is the fuel gas source to the coolant inlet at the fourth pressure The manifold supplies fuel, the gas source 120 is an inert gas source and supplies inert gas to the oxidant inlet at a fifth pressure, and a pressure difference is maintained between the fourth pressure and the third pressure and the fifth pressure, preferably the fourth pressure is greater than The pressure difference between the third pressure and the fifth pressure may be between 0kPa and 70kPa, preferably between 10kPa and 40kPa. Then apply a potential difference on at least one cell (preferably one cell) in the stack, so that the cathode of the fuel cell is more positive than the anode (the anode is the reference electrode), specifically refers to the cathode voltage of the fuel cell is greater than the anode voltage, where the potential The magnitude of the difference may be between 0.2V and 0.9V, preferably about 0.5V. Measure the transfer current. When the transfer current is greater than the reference current, it indicates that there is an oxidant-coolant transfer leakage in the battery.

For example, both the gas source 100 and the gas source 110 provide fuel gas, the gas source 120 provides inert gas, and the gas pressure valves 106 , 116 and 126 are adjusted to ensure that the fuel of 110 is supplied to the stack 90 at a higher pressure. The constant voltage power supply 150 implements a potential difference on at least one battery (preferably one battery) in the electric stack 90, wherein any battery of the electric stack is selected to be connected to the constant voltage power supply through a path selector. The ammeter 160 is connected in series with the cross-current power supply, and is used to measure the transfer current through the battery, for example, to implement a potential difference on the 108b battery, and the ammeter is connected as shown in the figure. If there is no oxidizer-to-coolant transfer leak, a very small amount (the membrane itself is somewhat gas permeable) of hydrogen diffuses across the membrane, producing a small constant transfer current. Oxidant-to-coolant transfer leaks can lead to an increase in the oxidation rate of hydrogen at the cathode due to fuel transfer from the coolant pathway to the cathode chamber of the cell, which in turn causes an increase in the transfer current, which can be detected by the flow meter. The detected transfer current of a single cell is compared with a reference transfer current, and if the detected transfer current is higher than the reference transfer current, an oxidant-coolant leak is indicated.

Example 3

The detection type of this embodiment is fuel-coolant transfer leakage detection, which is basically the same as that of Embodiment 2.

The difference is that the gas source 100 is an inert gas source and supplies inert gas to the fuel manifold at the sixth pressure, the gas source 110 is a fuel gas source and supplies fuel to the coolant inlet manifold at the seventh pressure, and the gas source 120 is a fuel gas source and supplies fuel to the coolant inlet manifold at the seventh pressure. Fuel is supplied to the oxidant inlet at an eighth pressure, wherein the seventh pressure is greater than the sixth pressure and an eighth pressure, the eighth pressure being greater than or equal to the sixth pressure.

A potential difference is applied across the cell such that the anode is more positive than the cathode (in this example the cathode is the reference electrode), ie the anode voltage of the fuel cell is greater than the cathode voltage. Thus, referring again to FIG. 2, gas source 110 and gas source 120 contain fuel gas, and gas source 100 contains an inert gas. If there is no fuel-to-coolant transfer leak, a very small amount (the membrane itself is somewhat gas permeable) of hydrogen diffuses across the membrane, producing a small constant transfer current. As fuel is diverted from the coolant pathway to the anode chamber of the cell, fuel-to-coolant transfer leaks can lead to an increase in the oxidation rate of hydrogen at the anode, which in turn causes an increase in the transfer current, which can be detected by the flow meter. The sensed transfer current of a single cell is compared with a reference transfer current, and if the sensed transfer current is higher than the reference transfer current, a fuel-coolant leak is indicated.

Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A proton exchange membrane fuel cell stack leakage online detection method, characterized in that, comprising: S10: Determine the detection type, the detection type includes: reactant transfer leak detection, oxidizer-coolant transfer leak detection, and fuel-coolant transfer leak detection; S20: According to the detection type, supply corresponding gas sources to the fuel inlet, coolant inlet and oxidant inlet of the stack respectively, and the gas sources are inert gas or fuel; S30: applying a potential difference on the fuel cell of the stack, and measuring the transfer current between the anode and the cathode of the fuel cell; S40: According to the reference current and the measured transfer current, it is judged whether there is leakage corresponding to the detection type in the fuel cell. 2. the on-line detection method of proton exchange membrane fuel cell stack leakage as claimed in claim 1, is characterized in that, described step S20 comprises: When the detection type is reactant transfer leak detection, supply fuel to the fuel inlet at a first pressure, and supply inert gas to the oxidant inlet at a second pressure; When the detection type is oxidizer-coolant transfer leak detection, supply fuel to the fuel inlet at a third pressure, supply fuel to the coolant inlet at a fourth pressure, and supply inert gas to the oxidizer inlet at a fifth pressure; When the detection type is fuel-coolant transfer leak detection, the fuel inlet is supplied with fuel at a sixth pressure, the coolant inlet is supplied with fuel at a seventh pressure, and the oxidizer inlet is supplied with fuel at an eighth pressure. 3. the proton exchange membrane fuel cell stack leakage on-line detection method as claimed in claim 2, is characterized in that, The first pressure is greater than the second pressure, the fourth pressure is greater than the third pressure and the fifth pressure, the fifth pressure is greater than or equal to the third pressure, the seventh pressure is greater than the sixth pressure and the eighth pressure, The eighth pressure is greater than or equal to the sixth pressure. 4. The on-line detection method for proton exchange membrane fuel cell stack leakage as claimed in claim 1, wherein said step S30 comprises: When the detection type is reactant transfer leakage detection, the cathode voltage of the fuel cell is greater than the anode voltage; When the detection type is oxidant-coolant transfer leakage detection, the cathode voltage of the fuel cell is greater than the anode voltage; When the detection type is fuel-coolant transfer leak detection, the anode voltage of the fuel cell is greater than the cathode voltage. 5. The on-line detection method for proton exchange membrane fuel cell stack leakage as claimed in claim 1, wherein said step S30 comprises: When there are multiple fuel cells in the stack, apply a potential difference to at least one fuel cell in the stack, and measure the transfer current between the anode and cathode of one or more fuel cells; Apply a potential difference to all the fuel cells in the stack in turn, and measure the transfer current of one or more fuel cells; The step S40: according to the measured transfer current and the reference current of the fuel cell, it is judged whether there is a corresponding type of leakage in one or more fuel cells. 6. the proton exchange membrane fuel cell stack leakage on-line detection method as claimed in claim 5, is characterized in that, when applying potential difference on multiple fuel cells, measure the anode of the first fuel cell and the last fuel cell Transfer current between cathodes. 7. The on-line detection method for proton exchange membrane fuel cell stack leakage according to claim 1, characterized in that, said step S40 comprises: when the measured transfer current is greater than the reference current, the fuel cell has a corresponding Detect type of leak. 8. A proton exchange membrane fuel cell stack leakage on-line detection device for realizing the on-line detection method for proton exchange membrane fuel cell stack leakage according to any one of claims 1-7, characterized in that it comprises: Fuel gas source: used to deliver fuel to the corresponding inlet according to the detection type; Inert gas source: used to deliver inert gas to the corresponding inlet according to the detection type; Constant voltage power supply: connect the anode and cathode of the fuel cell of the electric stack, and apply a potential difference to the fuel cell of the electric stack; Current meter: connected in series with the constant voltage power supply, used to measure the transfer current between the anode and cathode of the fuel cell. 9. The proton exchange membrane fuel cell stack leakage on-line detection device as claimed in claim 8, is characterized in that, also comprises: Path selector; respectively connected to the constant voltage power supply and each fuel cell of the electric stack, used to select one or more fuel cells in the electric stack to be connected to the constant voltage power supply; Recorder: connected with the current meter, used to obtain the data of the current meter; Controller: respectively connected to the constant voltage power supply and the path selector, used to control the path selector to sequentially select the anode and cathode of a single battery or multiple batteries to connect with the constant voltage power supply and control the output voltage of the constant voltage power supply. 10. The proton exchange membrane fuel cell stack leakage on-line detection device as claimed in claim 8, characterized in that, the fuel gas source and the fuel gas source are all connected to the inlet of the stack through a pressure valve, and the pressure The pressure the valve is used to deliver.

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