CN114914492B - Local voltage detection device of fuel cell system and detection analysis method thereof - Google Patents

Abstract

The invention discloses a local voltage detection device of a fuel cell system and a detection and analysis method thereof. The fuel cell system includes a controller and a fuel cell stack divided into several reaction areas. The local voltage detection device includes a device for detecting several reaction areas. Several voltage sensing probes for local voltage information and a voltage acquisition module for converting the local voltage information and transmitting it to the controller; the method includes: step 1. Obtaining several groups of first partial signals generated by the fuel cell stack operating under different currents. Instantaneous voltage to determine whether the fuel cell stack reacts unevenly; if so, perform step 2; if not, perform step 1; step 2, obtain several sets of second partial instantaneous results generated by the operation of the fuel cell stack when several variable parameters change one by one. voltage, from which a group of second partial instantaneous voltages with relatively large overall values are screened, and their corresponding variable parameters are obtained. The present invention can provide a reference basis for technicians to adjust the stack control strategy.

Description

A local voltage detection device for a fuel cell system and its detection and analysis method

Technical field

The invention relates to the technical field of fuel cell applications, and in particular to a local voltage detection device of a fuel cell system and a detection and analysis method thereof.

Background technique

The internal environment of the fuel cell stack is very complex when it is working. Affected by factors such as gas distribution uniformity and temperature, adjacent areas of the fuel cell stack form voltage differences, generate local currents, affect the performance of the stack, and even lead to proton exchange in severe cases. The membrane is perforated and the stack is damaged. However, the current fuel cell system does not propose local current detection of the fuel cell stack in different regions, and thus fails to analyze the factors causing local voltage differences and cannot take corresponding control measures to ensure uniform reactions within the fuel cell stack.

Contents of the invention

The present invention provides a local voltage detection device of a fuel cell system and a detection and analysis method thereof to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or creation condition.

Embodiments of the present invention provide a local voltage detection device of a fuel cell system. The fuel cell system includes a fuel cell stack and a controller. The local voltage detection device includes a plurality of voltage sensing probes and voltage acquisition modules. The plurality of The voltage sensing probe is connected to the voltage acquisition module, and the voltage acquisition module is connected to the controller;

Several reaction areas are evenly divided on the fuel cell stack, and the plurality of voltage sensing probes are correspondingly arranged in the several reaction areas, and any one of the voltage sensing probes is used to detect local voltage information in the reaction area where it is located, The voltage acquisition module is used to convert the local voltage information into a local voltage signal identifiable by the controller and transmit it to the controller.

Further, the fuel cell system also includes a hydrogen supply module, an air supply module and a thermal energy management module;

The hydrogen supply module is connected to the fuel cell stack, and the hydrogen supply module is controlled by the controller for delivering the actual required hydrogen to the fuel cell stack;

The air supply module is connected to the fuel cell stack, and the air supply module is controlled by the controller for delivering actual required air to the fuel cell stack;

The thermal energy management module is connected to the fuel cell stack, and is controlled by the controller for regulating heat dissipation at the entrance and exit of the fuel cell stack.

In addition, embodiments of the present invention also provide a detection and analysis method for a local voltage detection device of a fuel cell system, using any of the above-mentioned local voltage detection devices of the fuel cell system. The detection and analysis method includes:

Step S100: Obtain several variable parameters that affect the operation of the fuel cell stack;

Step S200: Obtain several sets of first local instantaneous voltages generated by the fuel cell stack operating under different currents, and then adjust the operating current of the fuel cell stack to the initial state;

Step S300: Use the plurality of sets of first local instantaneous voltages to determine whether uneven reaction occurs in the fuel cell stack; if yes, continue to step S400; if not, return to step S200;

Step S400: Obtain several sets of second local instantaneous voltages generated by the operation of the fuel cell stack when the several variable parameters change individually, and the sets of second local instantaneous voltages are collected at the same specified current. owned;

Step S500: Select a group of second local instantaneous voltages with a relatively large overall value from the plurality of groups of second local instantaneous voltages, and then specify the variable parameters corresponding to the group of second local instantaneous voltages as the values for the fuel. The variable parameter that has the greatest impact on the current operating status of the battery stack.

Further, the implementation process of step S200 includes:

Step S210: When the operating current of the fuel cell stack remains I ₀ , control the fuel cell stack to operate stably for a period of time, where I ₀ represents the initial state of the current;

Step S220: When the operating current of the fuel cell stack increases to I ₀ +k×ΔI, obtain the kth group of first local instantaneous voltages generated by the operation of the fuel cell stack, where ΔI is the set current increment;

Step S230, determine whether k≥N ₁ is established, where N ₁ is the set total number of collections, N ₁ is a positive integer and N ₁ ≥ 2; if it is established, continue to execute step S240; if it is not established, control the fuel After the battery stack has been running stably for a period of time, k+1 is assigned to k and returns to step S220;

Step S240: Output N ₁ sets of first local instantaneous voltages, and then adjust the operating current of the fuel cell stack to the initial state;

Among them, the above-mentioned step S220 and the above-mentioned step S230 form a loop operation, and the loop operation is executed starting from k=1.

Further, the implementation process of step S300 is:

Screen out M groups of first local instantaneous voltages whose overall values are not exactly the same from the N ₁ groups of first local instantaneous voltages, and determine whether M is less than the established threshold; if so, determine that the internal reaction of the fuel cell stack is uniform; if not , then it is judged that the internal reaction of the fuel cell stack is uneven.

Further, the several variable parameters include air flow and hydrogen flow, the air flow is associated with the excess air coefficient, and the hydrogen flow is associated with the hydrogen excess coefficient.

Further, the implementation process of step S400 includes:

Step S410: When the operating current of the fuel cell stack remains at I ₀ , control the fuel cell stack to operate stably for a period of time, where I ₀ represents the initial state of the current;

Step S420: Increase the excess air coefficient from the initial value λ ₁ to λ ₁ +Δλ ₁ , and after controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to I ₀ +ΔI, Obtain the first set of second local instantaneous voltages generated by the operation of the fuel cell stack, where Δλ ₁ is the set first coefficient increment, and ΔI is the set current increment;

Step S430: When the operating current of the fuel cell stack recovers from I ₀ +ΔI to I ₀ and the excess air coefficient recovers from λ ₁ +Δλ ₁ to λ ₁ , control the fuel cell stack to operate stably for a period of time;

Step S440: Increase the hydrogen excess coefficient from the initial value λ ₂ to λ ₂ +Δλ ₂ , and after controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to I ₀ +ΔI, Obtain a second set of second local instantaneous voltages generated by the operation of the fuel cell stack, where Δλ ₂ is the set second coefficient increment;

Step S450: Restoring the operating current of the fuel cell stack from I ₀ +ΔI to I ₀ , and restoring the excess air coefficient from λ ₁ +Δλ ₁ to λ ₁ .

Further, the implementation process of step S500 includes:

When the overall value of the first group of second local instantaneous voltages is greater than the overall value of the second group of second local instantaneous voltages, the air flow corresponding to the first group of second local instantaneous voltages is designated as the air flow rate corresponding to the first group of second local instantaneous voltages. The variable parameter that has the greatest influence on the current operating status of the fuel cell stack is described below;

Alternatively, when the overall value of the second group of second local instantaneous voltages is greater than the overall value of the first group of second local instantaneous voltages, the hydrogen flow rate corresponding to the second group of second local instantaneous voltages is designated as A variable parameter that has the greatest influence on the current operating state of the fuel cell stack.

The present invention at least has the following beneficial effects: by evenly dividing the fuel cell stack into several reaction areas and using several voltage sensing probes to measure them, it can ensure that the instantaneous voltage of each reaction area collected is at the same time. This ensures data reliability when performing subsequent voltage analysis tasks. By collecting and analyzing the instantaneous voltages generated by several reaction areas of the fuel cell stack operating at different currents, the internal reaction conditions of the fuel cell stack can be obtained more accurately. By collecting the instantaneous voltages generated by the operation of several reaction areas of the fuel cell stack when different variable parameters change and conducting comparative analysis on them, the variable parameters that have the greatest impact on the fuel cell stack can be more accurately obtained to facilitate technicians Timely adjust the operation control strategy of the fuel cell stack to further improve the operating efficiency of the fuel cell system.

Description of the drawings

The accompanying drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the description. Together with the embodiments of the present invention, they are used to explain the technical solutions of the present invention, and do not constitute a limitation of the technical solutions of the present invention.

Figure 1 is a schematic structural diagram of a local voltage detection device of a fuel cell system in an embodiment of the present invention;

Figure 2 is a schematic diagram of the installation distribution of several voltage sensing probes arranged on the fuel cell stack in the embodiment of the present invention;

Figure 3 is a schematic flowchart of a detection and analysis method of a local voltage detection device of a fuel cell system in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

It should be noted that although the functional modules are divided in the system schematic diagram and the logical sequence is shown in the flow chart, in some cases, the modules can be divided into different modules in the system or the order in the flow chart can be executed. The steps shown or described. The terms "first", "second", etc. in the description, claims, and above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific sequence or sequence.

Please refer to Figures 1 to 2. An embodiment of the present invention provides a local voltage detection device for a fuel cell system, wherein the fuel cell system includes a fuel cell stack, a controller, a hydrogen supply module, an air supply module and a thermal energy management module. The local voltage detection device includes several voltage sensing probes and voltage acquisition modules, and several reaction areas (represented as area 1 to area 2N in Figure 2) are evenly divided on the fuel cell stack. The sensing probes (represented as voltage sensing probe 1 to voltage sensing probe 2N in Figure 2) are correspondingly arranged in the several reaction areas, that is, ensuring that each reaction area is equipped with a voltage sensing probe for detection.

In an embodiment of the present invention, the hydrogen supply module is connected to the fuel cell stack, and the hydrogen supply module is controlled by the controller for delivering the actual required hydrogen to the fuel cell stack; The air supply module is connected to the fuel cell stack, and the air supply module is controlled by the controller to deliver actual required air to the fuel cell stack; the thermal energy management module is connected to the fuel cell stack. The battery stack is connected, and the thermal energy management module is controlled by the controller, which is used to regulate heat dissipation at the entrance and exit of the fuel cell stack and discharge excess heat generated by the fuel cell stack in a timely manner; the plurality of voltages The induction probe is connected to the voltage acquisition module, and the voltage acquisition module is connected to the controller. Any one of the voltage induction probes is used to detect the local voltage information in the reaction area where it is located, and the voltage acquisition module is used to collect all the voltage information. The local voltage information is converted into a local voltage signal identifiable by the controller and transmitted to the controller to perform subsequent instantaneous voltage analysis tasks.

Specifically, the controller can be used to regulate the flow rate, temperature and humidity of hydrogen delivered by the hydrogen supply module to the fuel cell stack, and can also be used to regulate the flow of hydrogen delivered by the air supply module to the fuel cell stack. The flow rate, temperature and humidity of the delivered air, and the degree of heat dissipation used to regulate the inlet temperature and outlet temperature of the fuel cell stack by the thermal energy management module.

Wherein, the hydrogen supply module includes a hydrogen supply device, a first inlet valve, a first exhaust valve and a hydrogen circulation pump; the air supply module includes an air supply device, a second inlet valve and a second exhaust valve; The thermal energy management module includes a radiator and a coolant circulation pump. The above three modules are all common equipment in existing fuel cell systems and do not belong to the content to be protected by the present invention, so they will not be described again here.

Based on the above-mentioned local voltage detection device of the fuel cell system, an embodiment of the present invention also provides a detection and analysis method of the local voltage detection device of the fuel cell system. Refer to the schematic flow chart shown in Figure 3. The detection method Analysis methods include the following:

Step S100: Obtain several variable parameters that affect the operation of the fuel cell stack;

Step S200: Obtain several sets of first local instantaneous voltages generated by the fuel cell stack operating under different currents, and then adjust the operating current of the fuel cell stack to the initial state;

Step S300: Use the plurality of sets of first local instantaneous voltages to determine whether uneven reaction occurs in the fuel cell stack; if yes, continue to step S400; if not, return to step S200;

Step S400: Obtain several sets of second local instantaneous voltages generated by the operation of the fuel cell stack when the several variable parameters change individually, and the sets of second local instantaneous voltages are collected at the same specified current. owned;

Step S500: Select a group of second local instantaneous voltages with a relatively large overall value from the plurality of groups of second local instantaneous voltages, and then specify the variable parameters corresponding to the group of second local instantaneous voltages as the values for the fuel. The variable parameter that has the greatest impact on the current operating status of the battery stack.

In the above step S200, any group of first local instantaneous voltages is detected by the plurality of voltage sensing probes, that is to say, the number of first instantaneous voltages included in any group of first local instantaneous voltages The same number as the number of voltage sensing probes.

In the above step S400, any set of second local instantaneous voltages is detected by the plurality of voltage sensing probes; the number of sets of second local instantaneous voltages is the same as the number of the plurality of variable parameters. , when the number of the several variable parameters is K, any set of second local instantaneous voltages is collected under the condition that K-1 variable parameters remain unchanged and only one variable parameter changes, and each The variable parameters for which the second local instantaneous voltages of the group change are different from each other.

In the embodiment of the present invention, the implementation process of step S200 includes the following:

Step S210: When the operating current of the fuel cell stack remains I ₀ , control the fuel cell stack to operate stably for a period of time, where I ₀ represents the initial state of the current;

Step S220: When the operating current of the fuel cell stack increases to I ₀ +k×ΔI, obtain the kth group of first local instantaneous voltages generated by the operation of the fuel cell stack, where ΔI is the set current increment;

Step S230, determine whether k≥N ₁ is established, where N ₁ is the set total number of collections, N ₁ is a positive integer and N ₁ ≥ 2; if it is established, continue to execute step S240; if it is not established, control the fuel After the battery stack has been running stably for a period of time, k+1 is assigned to k and returns to step S220;

Step 240: Output the first local instantaneous voltage of the N ₁ group, and then adjust the operating current of the fuel cell stack to the initial state, that is, the operating current of the fuel cell stack is maintained at I ₀ ;

The above-mentioned step S220 and the above-mentioned step S230 form a loop operation, and the loop operation is executed starting from k=1, thereby ensuring that the loop operation can be executed N ₁ times to obtain N ₁ sets of first local instantaneous voltages.

In the embodiment of the present invention, the implementation process of step S300 is: filter out M groups of first local instantaneous voltages whose overall values are not exactly the same from the N ₁ groups of first local instantaneous voltages, and determine whether M is less than a predetermined threshold. ; If yes, it is determined that the internal reaction of the fuel cell stack is uniform; if not, then it is determined that the internal reaction of the fuel cell stack is uneven.

The predetermined threshold depends on the value of N ₁ to ensure that among the N ₁ groups of first local instantaneous voltages, most groups of first local instantaneous voltages are in a state with exactly the same overall value. That is to say, all All the first local instantaneous voltages contained in any group of first local instantaneous voltages among the majority of the first partial instantaneous voltages have the same value. At this time, it can be judged that when collecting the first partial instantaneous voltages of the group, the The internal reactions of the fuel cell stack are uniform.

It should be noted that in the above step S200, when the cyclic operation is performed to increase the operating current of the fuel cell stack to I ₀ +N ₁ ×ΔI, the operating current I ₀ +N ₁ ×ΔI should not exceed The allowable operating current range of the fuel cell stack is to avoid unnecessary damage to the fuel cell stack; in addition, the above-mentioned step S300 proposes to use the first local instantaneous voltage of the N ₁ group to determine the reaction unevenness , which can avoid misjudgments caused by accidental events.

In the embodiment of the present invention, the several variable parameters include but are not limited to air flow and hydrogen flow; wherein, the air flow is associated with the excess air coefficient, the hydrogen flow is associated with the hydrogen excess coefficient, and between them The correlation belongs to the existing technology and will not be described again here.

In this embodiment of the present invention, the implementation process of step S400 includes:

Step S410: When the operating current of the fuel cell stack remains at I ₀ , control the fuel cell stack to operate stably for a period of time, where I ₀ represents the initial state of the current;

Step S420: Increase the excess air coefficient from the initial value λ ₁ to λ ₁ +Δλ ₁ , and after controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to I ₀ +ΔI, Obtain the first set of second local instantaneous voltages generated by the operation of the fuel cell stack, where Δλ ₁ is the set first coefficient increment, and ΔI is the set current increment;

Step S430: When the operating current of the fuel cell stack recovers from I ₀ +ΔI to I ₀ and the excess air coefficient recovers from λ ₁ +Δλ ₁ to λ ₁ , control the fuel cell stack to operate stably for a period of time;

Step S440: Increase the hydrogen excess coefficient from the initial value λ ₂ to λ ₂ +Δλ ₂ , and after controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to I ₀ +ΔI, Obtain a second set of second local instantaneous voltages generated by the operation of the fuel cell stack, where Δλ ₂ is the set second coefficient increment;

Step S450: Restoring the operating current of the fuel cell stack from I ₀ +ΔI to I ₀ , and restoring the excess air coefficient from λ ₁ +Δλ ₁ to λ ₁ .

In the embodiment of the present invention, the implementation process of step S500 includes: when the overall value of the first group of second local instantaneous voltages is greater than the overall value of the second group of second local instantaneous voltages, The air flow corresponding to a set of second local instantaneous voltages is designated as a variable parameter that has the greatest influence on the current operating state of the fuel cell stack; or, when the overall value of the second set of second local instantaneous voltages is greater than the first When the overall value of a set of second local instantaneous voltages is determined, the hydrogen flow rate corresponding to the second set of second local instantaneous voltages is designated as a variable parameter that has the greatest influence on the current operating state of the fuel cell stack.

Under normal circumstances, the overall value of the first group of second local instantaneous voltages and the overall value of the second group of second local instantaneous voltages will not be exactly the same. If there are exceptions, the air flow rate will be changed at the same time. and hydrogen flow rate are designated as two variable parameters that have a greater impact on the current operating status of the fuel cell stack.

It should be noted that the implementation effect of controlling the fuel cell stack to operate stably for a period of time as mentioned in the above steps S200 and S400 is as follows: several voltage data detected by the several voltage sensing probes can be maintained in a stable state.

It should be noted that the analysis process of the above steps S300 and step S500 is executed in the controller, and the working current adjustment involved in the above step S200 and the variable parameters and working current involved in the above step S400 are The adjustment is controlled and adjusted by the controller.

In the embodiment of the present invention, a fuel cell stack with an output power of 5kW is measured. Taking the local voltage detection device including 6 voltage sensing probes as an example, the implementation process of the above steps S400 and S500 is detailed and exemplified. Description, specifically including the following:

Step A1: When the operating current of the fuel cell stack is maintained at 1A, control the fuel cell stack to operate stably for a period of time;

Step A2: Increase the excess air coefficient from the initial value of 1.1 to 1.5. After controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to 1.5A to obtain the first group of energy generated by the operation of the fuel cell stack. The second local instantaneous voltage is: U _{5, air} = 706mV, U _{6, air} = 704mV, U _{1, air} = U _{2, air} = U _{3, air} = U _{4, air} = 707mV;

Step A3: When the operating current of the fuel cell stack returns from 1.5A to 1A and the excess air coefficient returns from 1.5 to 1.1, control the fuel cell stack to operate stably for a period of time;

Step A4: Increase the hydrogen excess coefficient from the initial value of 1.1 to 1.5. After controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to 1.5A to obtain the second group of energy generated by the operation of the fuel cell stack. The second local instantaneous voltage is: U _5,H2 =705mV, U _6,H2 =702mV, U _1,H2 =U _2,H2 =U _3,H2 =U _4,H2 =707mV;

Step A5, restore the operating current of the fuel cell stack from 1.5A to 1A, and restore the excess air coefficient from 1.5 to 1.1;

Step A6: By comparing the first set of second local instantaneous voltages obtained in the above step A2 and the second set of second local instantaneous voltages obtained in the above step A4, it can be seen that the overall value of the first set of second local instantaneous voltages is The value is greater than the overall value of the second group of second local instantaneous voltages, then the air flow is designated as the variable parameter that has the greatest impact on the current operating state of the fuel cell stack, thereby informing the technician that the current air flow can be adjusted to improve the The operating condition of the fuel cell stack.

In the embodiment of the present invention, a fuel cell stack with an output power of 10kW is measured. Taking the local voltage detection device including 8 voltage sensing probes as an example, the implementation process of the above steps S400 and S500 is detailed and exemplified. Description, specifically including the following:

Step B1: When the operating current of the fuel cell stack is maintained at 2A, control the fuel cell stack to operate stably for a period of time;

Step B2: Increase the excess air coefficient from the initial value of 1.1 to 1.2. After controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to 3A to obtain the first group of the fuel cell stack generated by the operation. The two local instantaneous voltages are: U _{1, air} = U _{2, air} = 708mV, U _{3, air} = U _{4, air} = U 5 _{, air = U 6 , air} = 710mV, U _{7, air} = 707mV, U _{8, air} =709mV;

Step B3: When the operating current of the fuel cell stack returns from 3A to 2A and the excess air coefficient returns from 1.2 to 1.1, control the fuel cell stack to operate stably for a period of time;

Step B4: Increase the hydrogen excess coefficient from the initial value 1.1 to 1.2. After controlling the fuel cell stack to operate stably for a period of time, increase the operating current of the fuel cell stack to 3A to obtain the second group of the fuel cell stack generated by the operation. The two local instantaneous voltages are: U _1,H2 ＝704mV, U _2,H2 ＝705mV, U _3,H2 ＝U _4,H2 ＝U _5,H2 ＝U _6,H2 ＝711mV, U _7,H2 ＝705mV, U _8,H2 =706mV;

Step B5, restore the operating current of the fuel cell stack from 3A to 2A, and restore the excess air coefficient from 1.2 to 1.1;

Step B6: By comparing the first group of second local instantaneous voltages obtained in the above step B2 and the second group of second local instantaneous voltages obtained in the above step B4, it can be seen that the overall second group of the first group of second local instantaneous voltages is The value is greater than the overall value of the second group of second local instantaneous voltages, then the air flow is designated as the variable parameter that has the greatest impact on the current operating state of the fuel cell stack, thereby informing the technician that the current air flow can be adjusted to improve the The operating condition of the fuel cell stack.

Although the description of the present application has been quite thorough and has particularly described several of the described embodiments, it is not intended to be limited to any such details or embodiments or to any particular embodiment, but rather is to be considered by reference. The appended claims, taking into account the prior art, provide a broad possible interpretation of these claims to effectively cover the intended scope of the application. In addition, the above description of the present application is based on embodiments foreseeable by the inventor, with the purpose of providing a useful description, and those non-substantive changes to the present application that are not yet foreseeable can still represent equivalent changes to the present application.

Claims (7)

1. The detection and analysis method of the local voltage detection device of the fuel cell system is characterized by applying the local voltage detection device of the fuel cell system, wherein the fuel cell system comprises a fuel cell stack and a controller, the local voltage detection device comprises a plurality of voltage induction probes and a voltage acquisition module, the voltage induction probes are connected with the voltage acquisition module, and the voltage acquisition module is connected with the controller;

the fuel cell stack is uniformly divided into a plurality of reaction areas, the plurality of voltage sensing probes are correspondingly arranged in the plurality of reaction areas, any one of the voltage sensing probes is used for detecting local voltage information in the reaction area, and the voltage acquisition module is used for converting the local voltage information into a local voltage signal which can be identified by the controller and transmitting the local voltage signal to the controller;

the detection and analysis method comprises the following steps:

step S100, acquiring a plurality of variable parameters affecting the operation of the fuel cell stack;

step 200, obtaining a plurality of groups of first local instantaneous voltages generated by the operation of the fuel cell stack under different currents, and then regulating the working current of the fuel cell stack to an initial state;

step S300, judging whether the fuel cell stack has a phenomenon of uneven reaction or not by utilizing the plurality of groups of first local instantaneous voltages; if yes, go on to step S400; if not, returning to execute the step S200;

step S400, acquiring a plurality of groups of second local instantaneous voltages generated by the operation of the fuel cell stack when the variable parameters are changed independently one by one, wherein the groups of second local instantaneous voltages are acquired under the same appointed current;

and S500, screening a group of second local instantaneous voltages with relatively large overall values from the groups of second local instantaneous voltages, and designating the variable parameter corresponding to the group of second local instantaneous voltages as the variable parameter with the greatest influence on the current running state of the fuel cell stack.

2. The method for detecting and analyzing the local voltage detecting device for a fuel cell system according to claim 1, wherein the step S200 is performed by:

step S210, when the operating current of the fuel cell stack is kept at I ₀ Controlling the fuel cell stack to stably operate for a period of time, wherein I ₀ Represented as a current initial state;

step S220, when the operating current of the fuel cell stack is increased to I ₀ Obtaining a k-th group first local instantaneous voltage generated by the operation of the fuel cell stack when +kxDeltaI is obtained, wherein DeltaI is a set current increment;

step S230, judging that k is more than or equal to N ₁ Whether or not to do so, where N ₁ For the set total collection times N ₁ Is a positive integer and N ₁ 2 or more; if so, proceed to step 240; if not, controlling the fuel cell stack to stably operate for a period of time, and then adding k +Assigning 1 to k, and returning to execute step 220;

step S240, output N ₁ A first local instantaneous voltage is set, and then the working current of the fuel cell stack is regulated to an initial state;

wherein the above-described step S220 and the above-described step S230 form a loop operation, and the loop operation is performed starting from k=1.

3. The method for detecting and analyzing the local voltage detecting device for a fuel cell system according to claim 2, wherein the step S300 is performed as follows:

from the N ₁ Screening M groups of first local instantaneous voltages with the whole numerical values not being identical from the groups of first local instantaneous voltages, and judging whether M is smaller than a preset threshold value or not; if yes, judging that the internal reaction of the fuel cell stack is uniform; if not, judging that the internal reaction of the fuel cell stack is not uniform.

4. The method according to claim 1, wherein the plurality of variable parameters include an air flow rate associated with an excess air ratio and a hydrogen flow rate associated with a hydrogen excess ratio.

5. The method for detecting and analyzing the local voltage detecting device for a fuel cell system according to claim 4, wherein the step S400 is performed by:

step S410, when the operating current of the fuel cell stack is maintained at I ₀ Controlling the fuel cell stack to stably operate for a period of time, wherein I ₀ Represented as a current initial state;

step S420, the excess air ratio is changed from the initial value lambda ₁ To lambda rise to ₁ +Δλ ₁ After the fuel cell stack is controlled to stably operate for a period of time, the operating current of the fuel cell stack is increased to I ₀ +ΔI, obtaining a first set of second local areas generated by operation of the fuel cell stackInstantaneous voltage, Δλ ₁ For the set first coefficient increment, Δi is the set current increment;

step S430, when the operating current of the fuel cell stack is equal to the operating current of the fuel cell stack ₀ Restoration of +ΔI to I ₀ And the excess air ratio is from lambda ₁ +Δλ ₁ Restoring to lambda ₁ Controlling the fuel cell stack to stably operate for a period of time;

step S440, the hydrogen excess coefficient is changed from the initial value lambda ₂ To lambda rise to ₂ +Δλ ₂ After the fuel cell stack is controlled to stably operate for a period of time, the operating current of the fuel cell stack is increased to I ₀ +ΔI, obtaining a second set of second local instantaneous voltages generated by operation of the fuel cell stack, wherein Δλ ₂ Adding value for the set second coefficient;

step S450, the working current of the fuel cell stack is controlled from I ₀ Restoration of +ΔI to I ₀ And the excess air ratio is determined from lambda ₁ +Δλ ₁ Restoring to lambda ₁ 。

6. The method for detecting and analyzing the local voltage detecting device for a fuel cell system according to claim 5, wherein the step S500 is performed by:

when the integral value of the first group of second local instantaneous voltages is larger than that of the second group of second local instantaneous voltages, designating the air flow corresponding to the first group of second local instantaneous voltages as a variable parameter with the greatest influence on the current running state of the fuel cell stack;

and when the integral value of the second group of second local instantaneous voltages is larger than that of the first group of second local instantaneous voltages, designating the hydrogen flow corresponding to the second group of second local instantaneous voltages as a variable parameter with the greatest influence on the current running state of the fuel cell stack.

7. The method for detecting and analyzing a local voltage detection device of a fuel cell system according to claim 1, wherein the fuel cell system further comprises a hydrogen supply module, an air supply module, and a thermal management module;

the hydrogen supply module is connected with the fuel cell stack and is controlled by the controller and used for conveying the actually required hydrogen to the fuel cell stack;

the air supply module is connected with the fuel cell stack and is controlled by the controller and used for conveying the air actually required to the fuel cell stack;

the thermal energy management module is connected with the fuel cell stack, is controlled by the controller and is used for carrying out heat dissipation regulation and control on the inlet and outlet of the fuel cell stack.