A method for predicting the temperature of the bumps on hydrogen fuel cell bipolar plates at a microscopic level when subjected to low voltage and high current

Abstract

The invention discloses a method for predicting the temperature of a convex point of a hydrogen fuel cell bipolar plate under a microscopic level when the bipolar plate is subjected to a low voltage and a large current. The method comprises the following steps: S1, preparing a plurality of stainless steel plates, stainless steel current needles and a plurality of weights of different weights, wherein the lower part of the stainless steel current needle is a hemisphere; S2, performing surface polishing treatment on the stainless steel current needle and the stainless steel plate; S3, installing the stainless steel plate and the stainless steel current needle on an experimental device, wherein the bottom of the stainless steel current needle can be pressed on the stainless steel plate, and zeroing the pressure sensor connected to the stainless steel current needle; S4, connecting a positive electric clamp to the stainless steel current needle, and connecting a negative electric clamp to the stainless steel plate; S5, connecting the positive electric clamp and the negative electric clamp to a power source, changing the normal load applied to the stainless steel current needle, and measuring the temperature of the convex point under different normal loads; changing the voltage, and measuring the temperature of the convex point under different voltages; the invention can predict the influence of the normal load and the contact voltage on the temperature of the convex point under a microscopic level, and can effectively prevent improper electrical contact relationships.

Description

Technical Field

[0001] The invention relates to the technical field of bipolar plates of hydrogen fuel cells, in particular to a method for predicting the temperature of convex points of bipolar plates of hydrogen fuel cells when subjected to low voltage and high current at a microscopic level. Background Art

[0002] Hydrogen fuel cells have the advantages of energy saving, environmental protection and zero carbon, and have huge application potential in the commercial vehicle field in the future.

[0003] Due to the assembly design of the fuel cell stack, the surface of the bipolar plate is uneven at the microscopic level. When in contact, the bumps on the bipolar plate generate instantaneous large current due to nonlinear force electrical contact, which generates high temperature and causes the bipolar plate to be corroded, resulting in battery failure. In the prior art, it is impossible to predict the temperature changes of the bumps on the bipolar plate when subjected to different normal loads or different contact voltages, and it is impossible to prevent improper electrical contact relationships. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above and / or existing problems of bipolar plates in existing hydrogen fuel cells, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is that the prior art cannot predict the impact of different normal loads or different contact voltages on the temperature of the bumps on the bipolar plates. The present invention can predict the impact of normal load and contact voltage on the temperature of the bumps at the microscopic level, and can make corresponding adjustments to the normal load and contact voltage, effectively preventing improper electrical contact relationships, and helping to improve the safety and reliability of the overall battery stack.

[0007] In order to solve the above technical problems, the present invention provides the following technical solution: a method for predicting the temperature of the convex point of a hydrogen fuel cell bipolar plate when it is subjected to low voltage and high current at a microscopic level, comprising the following steps:

[0008] S1 prepares a number of stainless steel plates of the same size, stainless steel current needles of the same number of stainless steel plates, and a number of weights of different weights, wherein the downward end of the stainless steel current needle is a hemisphere;

[0009] S2 polished the surface of the stainless steel current needle and stainless steel plate, and wiped the surface with alcohol before the experiment;

[0010] S3 installs the stainless steel plate and the stainless steel current needle on the experimental equipment. The bottom of the stainless steel current needle can be pressed on the stainless steel plate. The contact point between the bottom of the stainless steel current needle and the stainless steel plate is simulated as a convex point. The pressure sensor connected to the stainless steel current needle is zeroed.

[0011] S4 connects the stainless steel current needle to the positive clamp and the stainless steel plate to the negative clamp;

[0012] The S5 positive and negative clamps are connected to the positive and negative poles of the power supply respectively. The stainless steel current needle contacts the stainless steel plate to form a current loop. The normal load applied to the stainless steel current needle is changed, and the temperature at the bump under different normal loads is measured; the power supply voltage is changed, and the temperature at the contact point between the stainless steel current needle and the stainless steel plate under different voltages is measured.

[0013] As a preferred solution of the method for predicting the temperature of the convex point of the bipolar plate of a hydrogen fuel cell when it is subjected to low voltage and high current at the microscopic level in the present invention, the experimental equipment includes a bottom plate, a plurality of columns are arranged on the upper side of the bottom plate, a top plate is fixedly connected to the upper side of the columns, a test bench for installing a stainless steel plate is connected to the bottom plate between the columns, at least two vertical poles are fixedly connected between the bottom plate and the top plate, a voltage regulating plate for placing weights is slidably connected to the vertical poles, a suspension rod for convenient weight insertion is fixedly connected to the upper end of the voltage regulating plate, a lifting ear for connecting a suspension rope is fixedly fixed to the upper end of the suspension rod, the upper end of the experimental frame is rotatably connected to two pulleys arranged at intervals in the left and right directions, the left side of the leftmost pulley is outside the left side of the top plate, a pressure sensor is fixedly connected to the lower side of the voltage regulating plate, an insulating sleeve is fixedly connected to the lower end of the pressure sensor, a stainless steel current needle is fixedly connected to the lower part of the insulating sleeve, and the bottom of the stainless steel current needle is below the insulating sleeve.

[0014] As a preferred solution of the method for predicting the temperature of the protrusions of the bipolar plates of hydrogen fuel cells under the microscopic level when subjected to low voltage and high current in the present invention, the stainless steel current needle below the insulating sleeve is provided with a conductive block, a connecting hole is provided on the conductive block, a clamping groove is provided on the conductive block at the outer edge of the connecting hole, screw holes are provided on the conductive blocks on both sides of the clamping groove, a conductive bolt is screwed into one screw hole, passes through the clamping groove, and then screwed into another screw hole to tighten the clamping groove, the conductive block is clamped on the stainless steel current needle, and the positive clamp is clamped on the conductive bolt.

[0015] As a preferred solution of the method for predicting the temperature at the bump of a hydrogen fuel cell bipolar plate when subjected to low voltage and high current at a microscopic level in the present invention, wherein: when measuring the influence of different normal loads on the temperature at the bump, a fixed contact voltage is set, and different normal loads are simulated by placing different weights on the lifting plate, and a measurement time of one is set, and the temperature of the top of the stainless steel current needle during the experiment is detected in real time by a thermal imager, and after the set time is reached, temperature data one is exported; when measuring the influence of different contact voltages on the temperature at the bump, the normal load is controlled to 5N, and the output voltage is changed, and a measurement time of two is set, and the temperature change is detected in real time by a thermal imager, and after the set time is reached, temperature data two is exported.

[0016] As a preferred solution of the method for predicting the temperature at the bump of a hydrogen fuel cell bipolar plate under low voltage and high current at a microscopic level in the present invention, step S5 also includes the following steps, using COMSOL simulation software to mathematically model the stainless steel current needle and the stainless steel plate, setting the hemispherical surface and the upper surface of the lower electrode plate as a contact pair, and forming an assembly as a whole, simulating the influence of different normal loads and contact voltages on the temperature at the bump during electrical contact at a microscopic level, and predicting the temperature at the bump under different normal loads and the temperature at the bump under different contact voltages.

[0017] As a preferred solution of the method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate under low voltage and high current at the micro level in the present invention, the temperature of the convex point under different normal loads is predicted as shown in the following formula:

[0018] ;

[0019] in, y is the temperature at the convex point, y 0 is the initial temperature at the convex point, A 1 and A 2 are real constants; t1 and t2 are time constants, x 1 is time, and the values ​​of various constants are different under different normal loads.

[0020] As a preferred solution of the method for predicting the temperature of the bumps at the hydrogen fuel cell bipolar plate under low voltage and high current at the micro level in the present invention, the temperature of the bumps under different contact voltages is predicted as shown in the following formula:

[0021] ;

[0022] in, x 2 is time, t1 and t2 are both time constants, B1 and B 2 They are all real constants, and their values ​​are different under different contact voltages.

[0023] The beneficial effect of the present invention is that by accurately predicting the influence of normal load and contact voltage on the temperature at the bump at the microscopic level, corresponding adjustments can be made to the normal load and contact voltage, effectively preventing improper electrical contact relationships, and helping to improve the safety and reliability of the overall battery stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0025] Figure 1 It is a three-dimensional structural diagram of the experimental equipment in the present invention.

[0026] Figure 2 for Figure 1 A partial enlarged view of point A in the middle.

[0027] Figure 3 This is the temperature change curve under different normal loads when the initial temperature is 36°C under experimental conditions.

[0028] Figure 4 To simulate the temperature change curve under different normal loads when the initial temperature is 309.15K.

[0029] Figure 5 This is the temperature change curve under different contact voltages when the initial temperature is 36°C under experimental conditions.

[0030] Figure 6 To simulate the temperature change curve under different contact voltages when the initial temperature is 309.15K.

[0031] Figure 7 The temperature variation curve when the normal load is 5N is depicted for simulation.

[0032] Figure 8 The temperature curve when the contact voltage is 0.6V is depicted for simulation.

[0033] Fig. 9 To explore the comparison curve between simulation and experimental data of normal load.

[0034] Fig.10 To explore the comparison curve of simulation and experimental data of contact voltage.

[0035] Fig.11 To establish a simplified model of spherical-surface contact at the microscopic level and draw the meshed diagram, (a) is the model mesh diagram, (b) is the model diagram, (c) the left one is the mesh subdivision diagram on the upper surface of the stainless steel plate, the right one is the mesh subdivision diagram of the bipolar plate and the bump, and the enlarged diagram is the mesh subdivision diagram at the bump.

[0036] Among them, 1 bottom plate, 2 columns, 3 poles, 4 pulleys, 5 top plates, 6 suspension rods, 601 lifting ears, 7 lifting plates, 8 pressure sensors, 9 insulating sleeves, 10 conductive blocks, 1001 clamping grooves, 11 stainless steel current needles, 12 conductive bolts, and 13 stainless steel plates. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0040] Example 1

[0041] Reference Figure 1 and Figure 2, which is the first embodiment of the present invention, which provides a method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate when it is subjected to low voltage and high current at the microscopic level. The experimental equipment used in the prediction includes a bottom plate, a plurality of columns are arranged on the upper side of the bottom plate, a top plate is fixedly connected to the upper side of the columns, and a test bench for installing a stainless steel plate is connected to the bottom plate between the columns. When installing the stainless steel plate, two clamping plates are used to clamp the two ends of the stainless steel plate on the test bench respectively, and the clamping plate is fixed to the test bench with a clamping bolt so that the stainless steel plate is fixed relative to the test bench. When the stainless steel plate needs to be replaced, the clamping bolt is loosened, the stainless steel plate is removed, and a new stainless steel plate is replaced, and the clamping bolt is screwed in again to clamp the new stainless steel plate on the test bench; at least two poles are fixedly connected between the bottom plate and the top plate, and a pressure regulating plate for placing weights is slidably connected to the pole, and a convenient weight is fixedly connected to the upper end of the pressure regulating plate The plug-in suspension rod has a suspension ear fixed on the upper end of the suspension rod for connecting the suspension rope. The upper end of the experimental frame is rotatably connected to two pulleys arranged at intervals in the left and right directions. The left side of the leftmost pulley is outside the left side of the top plate. One end of the suspension rope is connected to the suspension ear, and the other end of the suspension rope vertically passes through the through hole set on the top plate and then passes through the two pulleys and is connected to the weight. A pressure sensor is fixedly connected to the lower side of the voltage regulating plate, and an insulating sleeve is fixedly connected to the lower end of the pressure sensor. A stainless steel current needle is fixedly connected to the lower part of the insulating sleeve, and the bottom of the stainless steel current needle is below the insulating sleeve. A conductive block capable of conducting electricity is mounted on the stainless steel current needle below the insulating sleeve, and a connecting hole is opened on the conductive block. A clamping groove is opened on the conductive block at the outer edge of the connecting hole, and screw holes are opened on the conductive blocks on both sides of the clamping groove. A conductive bolt is screwed into a screw hole, passes through the clamping groove, and then screwed into another screw hole to tighten the clamping groove, and the conductive block is clamped on the stainless steel current needle; the following steps are included:

[0042] S1 prepares a number of stainless steel plates of the same size, stainless steel current needles of the same number of stainless steel plates, and a number of weights of different weights, wherein the downward end of the stainless steel current needle is a hemisphere;

[0043] S2 polished the surface of the stainless steel current needle and stainless steel plate, and wiped the surface with alcohol before the experiment;

[0044] S3 installs the stainless steel plate and the stainless steel current needle on the experimental equipment. The bottom of the stainless steel current needle can be pressed on the stainless steel plate. The point where the bottom of the stainless steel current needle contacts the stainless steel plate is simulated as a convex point. The pressure sensor connected to the stainless steel current needle is zeroed. Specifically, the sensor is placed in a pressure-free state, and the pressure sensor is connected to a computer for collecting data. The computer receives the pressure signal transmitted by the pressure sensor in real time and displays it on the display interface of the computer. The output value of the pressure sensor is adjusted to zero, and the pressure error is adjusted to 0.1N. Adjust according to the instruction manual of the pressure sensor to ensure the accuracy and stability of the 0 output value. Then place a 100g weight to observe the output pressure of the pressure sensor. If the error exceeds the currently set error value, continue to calibrate. Repeat the operation to ensure the experimental effect.

[0045] S4: Clamp the positive clamp on the conductive bolt, and connect the stainless steel plate to the negative clamp;

[0046] The S5 positive clamp and negative clamp are connected to the positive and negative poles of the power supply respectively. The stainless steel current needle contacts the stainless steel plate to form a current loop. A fixed contact voltage is set. Different normal loads are simulated by placing different weights on the lifting plate. The measurement time is set to one. The temperature of the top of the stainless steel current needle is detected in real time by a thermal imager during the experiment. After the set time is reached, temperature data one is exported. When measuring the effect of different contact voltages on the temperature at the bump, the normal load is controlled to 5N. By changing the output voltage, the measurement time is set to two. The temperature change is detected in real time by a thermal imager. After the set time is reached, temperature data two is exported. The effects of different normal loads and different contact voltages on the temperature at the bump are analyzed from the exported temperature data one and temperature data two.

[0047] The two parts of the experiment in step S5 are both performed multiple times, and the experimental data are averaged under the same experimental conditions.

[0048] The thermal imager is placed on one side of the experimental table in the left and right directions, and is focused on the contact point between the stainless steel current needle and the stainless steel plate.

[0049] Stainless steel plates were used to simulate bipolar plates.

[0050] Through this experiment, the influence of different normal loads under a specific contact voltage or the influence of different contact voltages under a specific normal load on the temperature at the bump can be obtained.

[0051] Example 2

[0052] Reference Figure 3 to Figure 11 , which is the second embodiment of the present invention. This embodiment can further accurately predict the temperature at the bump under different normal loads at a specific contact voltage or under different contact voltages at a specific normal load.

[0053] The weights of the different weights are 100g, 200, and 500g respectively. The materials of the stainless steel plate and the stainless steel current needle are both 316L, with dimensions of 50mm×50mm×1mm. Different weights are used to simulate different normal loads.

[0054] In the experiment in step S5, different normal loads are 1N, 2N, and 5N respectively, the contact voltage is controlled to be 0.6V, the measurement time is 2 minutes, the initial temperature is 36°C, and the corresponding temperature change curve is as follows: Figure 3 As shown; different contact voltages are 0.6V, 0.7V, and 0.8V, the normal load is controlled to be 5N, the measurement time is 2 minutes, the initial temperature is 36°C, and the corresponding temperature change curve is as follows Figure 5 shown.

[0055] Step S5 also includes the following steps: using COMSOL simulation software to mathematically model the stainless steel current needle and the stainless steel plate, establish a simplified ball-surface contact model at the micro level and draw a grid, such as Figure 3 As shown, an extremely fine swept grid is used for the upper and lower plates, and an extremely fine free tetrahedral grid is used for the convex point (maximum growth rate 1.5, curvature factor 0.6). The hemisphere and the upper surface of the lower plate are set as a contact pair. The boundary conditions of the model are defined according to the actual situation and experimental requirements, the degrees of freedom of the lower plate in the x, y, and z directions are constrained, and the bottom current is set to ground. The normal load and potential are applied to the top of the upper plate along the z direction, and the x-axis movement direction of the upper plate is restricted; finally, the specified displacement is set along the y-axis to simulate the vibration. Simulate the influence of different normal loads and contact voltages on the temperature at the convex point during electrical contact at the microscopic level, and predict the temperature at the convex point under different normal loads and the temperature at the convex point under different contact voltages. Set the ambient temperature to 309.15K, the material to 316L stainless steel, and the parameters are shown in the table below;

[0056]

[0057] The model is simulated by multi-physics field using electromagnetic heat and thermal expansion modules in the simulation software. Using the electro-thermal coupling algorithm, a constant potential is applied to the top of the upper plate to extract the temperature and current density at the contact point between the bump and the lower plate; then force-electro-thermal coupling is performed, and different normal loads (1N, 2N, 5N) are applied on the basis of the previous one. Since excessive normal loads may cause the bump to deform, excessive loads are not selected. The friction coefficient is set to 0.6 and the rated voltage is 0.6V.

[0058] The simulation results are as follows: Figure 4 shown.

[0059] Through experiments and simulations, it can be found that under the same conditions, the contact resistance will change with the change of normal load. At the microscopic level, the increase in normal load will destroy the tiny bumps on the rough surface, which can be understood as an increase in the effective contact area. Properly increasing the contact load is equivalent to effectively increasing the fixed constraint, which can reduce the tendency of micromotion to a certain extent. However, various components, such as fuel cell bipolar plates, are always subject to nonlinear loads due to the design of the stack bolt assembly. Therefore, increasing the contact load can only delay the occurrence of micromotion corrosion. During this period, the function of temperature changing with time under different normal loads can be interpreted as a two-stage exponential correlation equation. At this time, x is the normal load, and y is the temperature that rises after power is turned on. When the contact voltage is predicted to be 0.6V, the temperature at the bump under different normal loads is shown in the following formula,

[0060] (1);

[0061] in, y is the temperature at the convex point, y 0 is the initial temperature at the convex point, A 1 and A 2 are real constants; t1 and t2 are time constants, x 1 is time, and the values ​​of the constants under different normal loads are different; the estimated curve corresponding to formula (1) is as follows Figure 7 ,The simulated temperature curve is basically consistent with the estimated curve, ,crossing the contact resistance, and directly predicting the effect of different ,pressures on temperature.

[0062] In order to study the effect of different voltages on the temperature rise and contact resistance at the bump, three different contact voltages (0.6V, 0.7V, 0.8V) were designed for both the experiment and the finite element simulation. The selected voltages were all within the rated voltage range of the monolithic fuel cell (0.6V~0.85V), and the normal load was set to 5N. The simulation results are shown in Figure 2. Figure 6 shown.

[0063] When the normal load is predicted to be 5N, the temperature at the bump under different contact voltages is as follows:

[0064] (2);

[0065] in, x 2 is time, t1 and t2 are both time constants, B 1 and B 2 are all real constants. The values ​​of the constants are different under different contact voltages. The estimated curve corresponding to formula (2) is as follows: Figure 8 ,The simulated temperature curve is basically consistent with the estimated curve, ,which bypasses the contact resistance and directly predicts the effect of the contact voltage on ,temperature.

[0066] Figure 3 and Figure 4 The following are the changes in the effects of different normal loads on temperature in the experiment and simulation, revealing the deep physical relationship between normal load and contact resistance at the micro level: as the load increases, the effective contact area increases at the micro level. At the same time, due to the compression of the load, more paths are available for current to pass through, which eventually leads to a decrease in contact resistance. Therefore, the temperature changes from a sharp increase to a gentle trend. Therefore, appropriate load has a positive effect on electrical contact. Figure 5 and Figure 6 The graphs below show the effect of different contact voltages on temperature in the experiment and simulation, respectively, which reveal the relationship between voltage and contact resistance at the microscopic level: a larger contact voltage represents a larger current density, so a higher contact voltage per unit volume will generate more Joule heat, but at the same time the heat will be generated, causing the oxide at and near the contact point to soften or melt, thereby affecting the electrical contact efficiency and causing the temperature rise trend to become less severe. Fig. 9 and Fig.10 The simulation data is compared with the experimental data: it is concluded that the temperature change trends of the two are the same, and the relationship between normal load, contact voltage, temperature and contact resistance is verified again.

[0067] The above illustrates the influence of different normal loads and contact voltages on the temperature at the bump at the micro level, and formula (1) and formula (2) well describe the relationship between the normal load and the contact voltage and the temperature at the bump in the experiment and simulation, indicating that the method of the present invention for predicting the temperature at the bump of a fuel cell bipolar plate under low voltage and high current at the micro level is highly accurate, thereby intuitively predicting the influence of the normal load and contact voltage on the temperature at the bump at the micro level, providing a reference for the estimation of improper electrical contact between fuel cell bipolar plates.

[0068] In actual working conditions, the bipolar plates of fuel cells are tightly fitted together, so the simulation also simulates the fitting of the two stainless steel plates and draws the bumps that exist at the microscopic level. In the experimental case, the electrical contact scenario can be simulated by simply using a stainless steel current needle to contact the stainless steel plate.

[0069] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the technical solutions of the present invention.

Claims

1. A method for predicting the temperature of the convex point of a hydrogen fuel cell bipolar plate under low voltage and high current at a microscopic level, characterized by: The following steps are included: S1 prepares a number of stainless steel plates of the same size, stainless steel current needles of the same number of stainless steel plates, and a number of weights of different weights, wherein the downward end of the stainless steel current needle is a hemisphere; S2 polished the surface of the stainless steel current needle and stainless steel plate, and wiped the surface with alcohol before the experiment; S3 installs the stainless steel plate and the stainless steel current needle on the experimental equipment. The bottom of the stainless steel current needle can be pressed on the stainless steel plate. The contact point between the bottom of the stainless steel current needle and the stainless steel plate is simulated as a convex point. The pressure sensor connected to the stainless steel current needle is zeroed. S4 connects the stainless steel current needle to the positive clamp and the stainless steel plate to the negative clamp; The positive and negative clamps of S5 are connected to the positive and negative electrodes of the power supply respectively. The stainless steel current needle contacts the stainless steel plate to form a current loop. The normal load applied to the stainless steel current needle is changed, and the temperature at the bump under different normal loads is measured. Change the power supply voltage and measure the temperature at the contact point between the stainless steel current needle and the stainless steel plate under different voltages; Normal load = weight of the weight * 10N / kg, the unit of the weight of the weight is kg, and the unit of the normal load is N.

2. The method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate when subjected to low voltage and high current at the micro level as claimed in claim 1, characterized in that: The experimental equipment includes a base plate, a plurality of columns are arranged on the upper side of the base plate, a top plate is fixedly connected to the upper side of the columns, a test bench for installing a stainless steel plate is connected to the base plate between the columns, at least two poles are fixedly connected between the base plate and the top plate, a pressure regulating plate for placing weights is slidably connected to the poles, a suspension rod for convenient weight insertion is fixedly connected to the upper end of the pressure regulating plate, a lifting ear for connecting a suspension rope is fixedly fixed to the upper end of the suspension rod, two pulleys arranged at intervals in the left and right directions are rotatably connected to the upper end of the experimental frame, the left side of the leftmost pulley is outside the left side of the top plate, a pressure sensor is fixedly connected to the lower side of the pressure regulating plate, an insulating sleeve is fixedly connected to the lower end of the pressure sensor, a stainless steel current needle is fixedly connected to the lower part of the insulating sleeve, and the bottom of the stainless steel current needle is below the insulating sleeve.

3. The method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate under low voltage and high current at the micro level as claimed in claim 2 is characterized by: A conductive block capable of conducting electricity is mounted on the stainless steel current needle below the insulating sleeve, a connecting hole is formed on the conductive block, a clamping groove is formed on the conductive block at the outer edge of the connecting hole, screw holes are formed on the conductive blocks on both sides of the clamping groove, a conductive bolt is screwed into one screw hole, passes through the clamping groove, and then screwed into another screw hole to tighten the clamping groove, the conductive block is clamped on the stainless steel current needle, and the positive current clamp is clamped on the conductive bolt.

4. The method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate when subjected to low voltage and high current at the micro level as claimed in claim 2, characterized in that: When measuring the influence of different normal loads on the temperature at the bump, a fixed contact voltage is set, different normal loads are simulated by placing different weights on the lifting plate, measurement time one is set, and the temperature of the top of the stainless steel current needle during the experiment is detected in real time by a thermal imager. After the set time is reached, temperature data one is exported; when measuring the influence of different contact voltages on the temperature at the bump, the normal load is controlled to 5N, the output voltage is changed, measurement time two is set, and the temperature change is detected in real time by a thermal imager. After the set time is reached, temperature data two is exported.

5. The method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate when subjected to low voltage and high current at the micro level as claimed in claim 4, characterized in that: Step S5 also includes the following steps: using COMSOL simulation software to mathematically model the stainless steel current needle and the stainless steel plate, setting the hemispherical surface and the upper surface of the lower electrode plate as a contact pair, and forming an assembly as a whole, simulating the influence of different normal loads and contact voltages on the temperature at the bump during electrical contact at the microscopic level, and predicting the temperature at the bump under different normal loads and the temperature at the bump under different contact voltages.

6. The method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate under low voltage and high current at the micro level as claimed in claim 5, characterized in that: The predicted temperature at the convex point under different normal loads is shown in the following formula: ； in, y is the temperature at the convex point, y 0 is the initial temperature at the convex point, A 1 and A 2 are real constants; t1 and t2 are time constants, x 1 is time, and the values ​​of various constants are different under different normal loads.

7. The method for predicting the temperature of the convex point of the hydrogen fuel cell bipolar plate under low voltage and high current at the micro level as claimed in claim 5, characterized in that: The predicted temperature at the bump under different contact voltages is shown in the following formula: ； in, x 2 is the time, t1 and t2 are time constants, B 1 and B 2 They are all real constants, and the values ​​of the constants are different under different contact voltages. y 0 is the initial temperature at the bump.

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