Current density measuring device and measuring system for fuel cell stack

Abstract

The embodiment of the invention provides a current density measuring device and measuring system for a fuel cell stack, and relates to the technical field of cell testing, the current density measuring device comprises a substrate and a plurality of grid units, the substrate is used for being arranged between two polar plates in a to-be-tested stack and electrically connected with the two polar plates, and the grid units are arranged on the substrate. The grid units are distributed on the substrate in a matrix mode, each grid unit comprises a magnetic material area and a coil assembly, excitation current is externally connected to the coil assembly of each grid unit, and the current density of the grid unit is obtained according to the output voltage of the coil assembly. According to the invention, the current density distribution between the internal polar plates of the fuel cell stack is directly measured through the plurality of grid units distributed in the matrix, and the working state of the fuel cell stack is accurately reflected.

Description

Technical Field

[0001] The present invention relates to the technical field of battery testing, and in particular to a current density measuring device and a measuring system for a fuel cell stack. Background Art

[0002] As a clean and efficient energy conversion device, fuel cells have broad application prospects in electric vehicles, fixed power sources, and distributed energy systems. However, the performance of fuel cell stacks is affected by many factors during use, such as temperature, pressure, humidity, and reactant concentration, and the current density distribution of fuel cell stacks is one of the important indicators for evaluating their performance.

[0003] Traditional current density measurement usually uses external ammeters or voltmeters, but can only obtain the overall current value of the fuel cell stack. It is difficult to directly measure the current density distribution inside the fuel cell stack, and therefore cannot accurately reflect the working status of the fuel cell stack. Summary of the invention

[0004] The embodiments of the present invention provide a current density measuring device and a measuring system for a fuel cell stack, so as to solve the technical problem that it is difficult to measure the current density inside a fuel cell stack in the related art.

[0005] In a first aspect, the present invention provides a current density measuring device for a fuel cell stack, comprising:

[0006] A substrate, the substrate is used to be arranged between two electrode plates inside the battery stack to be tested and is electrically connected to the two electrode plates;

[0007] A plurality of grid units, wherein the plurality of grid units are distributed on the substrate in a matrix, and each of the grid units comprises a magnetic material area and a coil group;

[0008] An external excitation current is connected to the coil group of each grid unit, and the current density of the grid unit is obtained according to the output voltage of the coil group.

[0009] In some embodiments,

[0010] The substrate comprises: a first PCB board, a second PCB board and a third PCB board which are stacked;

[0011] The first PCB board and the third PCB board are used to be electrically connected to the two internal plates of the battery stack to be tested respectively. The second PCB board is arranged between the first PCB board and the third PCB board. The second PCB board is provided with mounting holes corresponding to each of the grid units one by one, and each of the mounting holes is used to accommodate the corresponding magnetic material area.

[0012] In some embodiments,

[0013] A plurality of electroplating areas distributed in a matrix are provided on one side of the first PCB board and the third PCB board away from the second PCB board, and each of the electroplating areas is provided corresponding to each of the grid units.

[0014] In some embodiments, each of the grid units further comprises:

[0015] Thermistor, wherein the thermistor is arranged on one side of the corresponding magnetic material area.

[0016] In some embodiments, each of the coil assemblies comprises:

[0017] A first coil, the first coil being arranged at one side of the corresponding magnetic material area;

[0018] a second coil, the second coil being arranged below the first coil, and one end of the second coil serving as an input end of the excitation current;

[0019] The third coil is symmetrically arranged with the second coil with the magnetic material area as the axis, and the voltage across both ends of the third coil is the output voltage of the corresponding coil group.

[0020] In some embodiments, each of the second coils in the same row is connected in series.

[0021] In some embodiments, each of the third coils in the same column is connected in series.

[0022] In some embodiments, it also includes:

[0023] A signal processing circuit is connected to the coil group of each of the grid units, and is used for filtering, amplifying, converting and calculating the output voltage of each of the grid units to obtain the current density of the grid unit.

[0024] In some embodiments, it also includes:

[0025] A host computer is connected to the signal processing circuit, and is used to obtain the current density of each grid unit and generate a current density stress distribution table.

[0026] In a second aspect, the present invention provides a current density measurement system for a fuel cell stack, comprising the aforementioned current density measurement device for a fuel cell stack.

[0027] The beneficial effects brought about by the technical solution provided by the present invention include:

[0028] The embodiment of the present invention provides a current density measuring device and a measuring system for a fuel cell stack, wherein the current density measuring device comprises a substrate and a plurality of grid units, wherein the substrate is used to be arranged between two internal plates of the stack to be measured and is electrically connected to the two plates, and the plurality of grid units are distributed on the substrate in a matrix, and each of the grid units comprises a magnetic material area and a coil group, and an external excitation current is connected to the coil group of each grid unit, and the current density of the grid unit is obtained according to the output voltage of the coil group. The present invention directly measures the current density distribution between the internal plates of the fuel cell stack by distributing a plurality of grid units in a matrix, and accurately reflects the working state of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram of a current density measuring device for a fuel cell stack provided by an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of a current density measuring device for a fuel cell stack provided by an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a current density measuring device for a fuel cell stack provided by an embodiment of the present invention;

[0033] Figure 4 A current density stress distribution table at a certain temperature provided by an embodiment of the present invention;

[0034] Reference numerals:

[0035] 1. substrate; 11. first PCB board; 111. electroplating area; 12. second PCB board; 13. third PCB board;

[0036] 2. Grid unit; 21. Magnetic material area; 22. Coil group; 221. First coil; 222. Second coil; 223. Third coil; 23. Thermistor. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The embodiments of the present invention provide a current density measuring device and a measuring system for a fuel cell stack, which can solve the technical problem that the related art is difficult to measure the current density inside the fuel cell stack.

[0039] See also Figure 1 As shown, an embodiment of the present invention provides a current density measuring device for a fuel cell stack, comprising a substrate 1 and a plurality of grid units 2, wherein the substrate 1 is used to be arranged between two internal plates of the stack to be measured and electrically connected to the two plates, and the plurality of grid units 2 are distributed on the substrate 1 in a matrix, and each of the grid units 2 is provided with a magnetic material area 21 and a coil group 22, and the current density I to be measured of the corresponding grid unit 2 is calculated according to the output voltage U(t) of the coil group 22. m The substrate 1 and the plurality of grid units 2 of the present invention are arranged in a matrix, and the current density distribution inside the fuel cell stack is directly measured to accurately reflect the working state of the fuel cell stack.

[0040] The present invention provides a current density measuring device for a fuel cell stack, comprising a substrate and a plurality of grid units, wherein the plurality of grid units are arranged in a grid-like manner on the substrate. During measurement, the measuring device is installed in the fuel cell stack to be measured, and after the temperature of the fuel cell stack to be measured is adjusted, the temperature of each grid unit is obtained, and an excitation current i(t) is connected to generate an output voltage U(t). The current density I of the fuel cell stack to be measured is calculated according to the output voltage U(t). m In order to promptly detect abnormal conditions in the fuel cell stack, such as uneven current density distribution or local overheating, quickly locate the source of the fault and take appropriate measures to repair it, so as to avoid further expansion of the fault or damage to the fuel cell stack. At the same time, through long-term monitoring of the current density distribution of the fuel cell stack, the occurrence trend of potential faults can be predicted, providing data support for preventive maintenance.

[0041] As an optional implementation, in an embodiment of the invention, see Figure 1As shown, the substrate 1 is provided with a first PCB board 11, a second PCB board 12 and a third PCB board 13 which are stacked, the first PCB board 11 and the third PCB board 13 are used to be electrically connected to the two internal plates of the battery stack to be tested respectively, the second PCB board 12 is arranged between the first PCB board 11 and the third PCB board 13, the second PCB board 12 is provided with a plurality of mounting holes corresponding to each of the grid units 2, each of the mounting holes is used to accommodate the corresponding magnetic material area 21. The design of three-layer PCB boards is adopted, and the first PCB board 11, the second PCB board 12 and the third PCB board 13 are stacked to improve space utilization, while improving heat dissipation performance, and ensuring reliable operation of the measuring device.

[0042] As an optional implementation, in an embodiment of the invention, see Figure 1 As shown, a plurality of electroplating areas 111 distributed in a matrix are provided on one side of the first PCB board 11 and the third PCB board 13 away from the second PCB board 12, and each of the electroplating areas 111 is provided corresponding to each of the grid units 2. In the embodiment of the present invention, the first PCB board 11 and the third PCB board 13 are subjected to grid-like gold plating. While the gold-plated areas are conductive, their low internal resistance characteristics reduce measurement errors caused by heat.

[0043] As an optional implementation, in an embodiment of the invention, see Figure 1 , Figure 2 and Figure 3 As shown, each of the grid units 2 is also provided with a thermistor 23, and the thermistor 23 is provided on one side of the corresponding magnetic material area 21. In the embodiment of the present invention, the thermistor 23 is an NTC. Since the magnetization intensity and magnetic field intensity of the magnetic material area 21 are greatly affected by temperature changes, a thermistor 23 is provided on one side of each magnetic material area 21 to measure the temperature of the corresponding grid unit 2. At the same time, before the measurement, each of the grid units 2 is calibrated at different temperatures and at different current densities I to be measured. m The corresponding output voltage U(t) is obtained to obtain the current density-voltage calibration table at different temperatures. In the process of current density measurement, the temperature and voltage value of the corresponding grid unit measured by the thermistor are looked up in the table to obtain the measured current density I of the grid unit. m .

[0044] Specifically, in the process of current density measurement, first, the temperature of the grid unit 2 is obtained through the thermistor 23 corresponding to the grid unit 2 to be measured, and when the second coil 222 of the grid unit 2 is passed through a constant AC excitation current i(t), the output voltage U(t) across the third coil 223 of the grid unit 2 is collected, and the current density I to be measured of the grid unit 2 is determined according to the current density-voltage calibration table corresponding to the temperature of the grid unit 2, that is, Table 1 below. m For example, when the output voltage U(t) is 0.15V, according to the following Table 1, the measured current density I m At 0.2A / cm 2 -0.3A / cm 2 The current density I to be measured is obtained by linear interpolation. m Further estimation: 0.2+(0.1 / 0.04)*0.01=0.225A / cm 2 , so as to obtain the measured current density I of all grid cells m distributed.

[0045] Table 1 Current density-voltage calibration table at a certain temperature

[0046]

[0047] Specifically, Figure 3 for Figure 2 The grid expansion scheme is used to realize the function of scanning measurement one by one. When i1(t) is excited, U1(t)-U n (t), and combined with the temperature of each corresponding grid unit, the current density-voltage calibration table at that temperature can be checked to obtain the measured current density I of each grid unit in the first row. m ,i n (t) when exciting, measure U1(t)-U one by one n (t), and combined with the temperature of each corresponding grid unit, the current density-voltage calibration table at that temperature can be checked to obtain the current density I of each grid unit in the nth row. m The scanning measurement design adopted by the present invention realizes the number of acquisition channels from n 2 Reducing n can significantly reduce the difficulty of routing design and manufacturing costs.

[0048] As an optional implementation, in an embodiment of the invention, see Figure 2 and Figure 3As shown, each coil group 22 is provided with a first coil 221, a second coil 222 and a third coil 223. The first coil 221 is provided at one side of the corresponding magnetic material area 21. The first coil 221 is electrically connected to the corresponding electroplating area 111. One end of the first coil 221 serves as the input end of the current to be measured. The second coil 222 is provided below the first coil 221. One end of the second coil 222 serves as the input end of the constant AC excitation current i(t). The third coil 223 and the second coil 222 are symmetrically arranged with the magnetic material area 21 as the axis. The voltage across the third coil 223 is the output voltage U(t) of the corresponding coil group 22. The first coil 221 is the current coil to be measured, and the current density to be measured is I m , used for magnetic conduction, the second coil 222 is an excitation current coil, the excitation current is i(t), the third coil 223 is a measuring coil, the third coil 223 measures the current density I m The signal is amplified into an output voltage U(t) for easy collection.

[0049] As an optional implementation, in an embodiment of the invention, see Figure 3 As shown, each of the second coils 222 in the same row is connected in series. In the embodiment of the present invention, row-by-row excitation and row-by-row acquisition are adopted. Each time a plurality of the grid units 2 in a row are excited, the output voltage U(t) of each of the grid units 2 in the row is acquired, including U1(t), U2(t) ... to U n (t), the grid units 2 in the remaining rows that are not excited will not interfere with each of the grid units 2 in the row. Compared with the existing single-channel excitation and acquisition, the embodiment of the present invention reduces the number of excitation and acquisition channels. The number of channels is n 2 Down to n.

[0050] As an optional implementation, in an embodiment of the invention, see Figure 3 As shown, each of the third coils 223 in the same column is connected in series, and the two ends of the series connection are the voltage output ends of each of the coil groups 22 in the column. n (t) is continuously fed into the matrix to activate the first row to the nth row. In each column, the third coil 223 of each grid unit 2 is connected in series, and the two ends of the series connection serve as the voltage output ends of the coil group 22. At the same time, the grid units 2 of the remaining rows that are not activated by the AC excitation current i(t) will not transmit any additional signals, thereby ensuring the anti-interference of the measurement environment.

[0051] As an optional implementation, in one embodiment of the invention, a signal processing circuit is further provided, the signal processing circuit is connected to the coil group 22 of each of the grid units 2, and the signal processing circuit is used to filter, amplify, convert and calculate the output voltage U(t) of each of the grid units 2 to obtain the current density I of the grid unit 2. m The embodiment of the present invention adds a signal processing circuit to realize the functions of amplification and filtering, and adopts a 24-bit high-precision ADC for acquisition to improve the accuracy of the measuring device.

[0052] As an optional implementation, in one embodiment of the invention, a host computer is further provided, which obtains and displays the measured current density I output by the signal processing circuit. m After filtering and amplifying the obtained output voltage U(t), a 24-bit high-precision ADC is used for acquisition to improve the accuracy of the measuring device. After table lookup and analysis, the current density I to be measured is obtained. m , and the grid display is performed on the host computer, that is, the current density stress distribution table is generated as follows Figure 4 As shown, it is used to display the current density of each grid unit.

[0053] The embodiment of the present invention further provides a current density measurement system for a fuel cell stack, including the aforementioned current density measurement device for a fuel cell stack, including a substrate 1 and a plurality of grid units 2, wherein the substrate 1 is used to be arranged between two internal plates of the stack to be measured and electrically connected to the two plates, and the plurality of grid units 2 are distributed on the substrate 1 in a matrix, and each of the grid units 2 is provided with a magnetic material area 21 and a coil group 22, and the current density I to be measured of the corresponding grid unit 2 is calculated according to the output voltage U(t) of the coil group 22. m The substrate 1 and the plurality of grid units 2 of the present invention are arranged in a matrix, and the current density distribution inside the fuel cell stack is directly measured to accurately reflect the working state of the fuel cell stack.

[0054] As an optional implementation, in an embodiment of the invention, see Figure 1As shown, the substrate 1 is provided with a first PCB board 11, a second PCB board 12 and a third PCB board 13 which are stacked, the first PCB board 11 and the third PCB board 13 are used to be electrically connected to the two internal plates of the battery stack to be tested respectively, the second PCB board 12 is arranged between the first PCB board 11 and the third PCB board 13, the second PCB board 12 is provided with a plurality of mounting holes corresponding to each of the grid units 2, each of the mounting holes is used to accommodate the corresponding magnetic material area 21. The design of three-layer PCB boards is adopted, and the first PCB board 11, the second PCB board 12 and the third PCB board 13 are stacked to improve space utilization, while improving heat dissipation performance, and ensuring reliable operation of the measurement system.

[0055] As an optional implementation, in an embodiment of the invention, see Figure 1 As shown, a plurality of electroplating areas 111 distributed in a matrix are provided on one side of the first PCB board 11 and the third PCB board 13 away from the second PCB board 12, and each of the electroplating areas 111 is provided corresponding to each of the grid units 2. In the embodiment of the present invention, the first PCB board 11 and the third PCB board 13 are subjected to grid-like gold plating. While the gold-plated areas are conductive, their low internal resistance characteristics reduce measurement errors caused by heat.

[0056] As an optional implementation, in an embodiment of the invention, see Figure 1 , Figure 2 and Figure 3 As shown, each of the grid units 2 is also provided with a thermistor 23, and the thermistor 23 is provided on one side of the corresponding magnetic material area 21. In the embodiment of the present invention, the thermistor 23 is an NTC. Since the magnetization intensity and magnetic field intensity of the magnetic material area 21 are greatly affected by temperature changes, a thermistor 23 is provided on one side of each magnetic material area 21 to measure the temperature of the corresponding grid unit 2. At the same time, before the measurement, each of the grid units 2 is calibrated at different temperatures and at different current densities I to be measured. m The corresponding output voltage U(t) is obtained to obtain the current density-voltage calibration table at different temperatures. In the process of current density measurement, the temperature and voltage value of the corresponding grid unit measured by the thermistor are looked up in the table to obtain the measured current density I of the grid unit. m .

[0057] Specifically, in the process of current density measurement, first, the temperature of the grid unit 2 is obtained through the thermistor 23 corresponding to the grid unit 2 to be measured, and when the second coil 222 of the grid unit 2 is passed through a constant AC excitation current i(t), the output voltage U(t) across the third coil 223 of the grid unit 2 is collected, and the current density I to be measured of the grid unit 2 is determined according to the current density-voltage calibration table corresponding to the temperature of the grid unit 2, that is, Table 1. m For example, when the output voltage U(t) is 0.15V, according to Table 1, the current density I to be measured is m At 0.2A / cm 2 -0.3A / cm 2 The current density I to be measured is obtained by linear interpolation. m Further estimation: 0.2+(0.1 / 0.04)*0.01=0.225A / cm 2 , so as to obtain the measured current density I of all grid cells m distributed.

[0058] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0059] It should be noted that, in the present invention, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0060] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features of the present invention.

Claims

1. A current density measuring device for a fuel cell stack, characterized in that: include: A substrate (1), the substrate (1) being arranged between two electrode plates inside a battery stack to be tested and being electrically connected to the two electrode plates; A plurality of grid units (2), wherein the plurality of grid units (2) are distributed on the substrate (1) in a matrix, and each of the grid units (2) comprises a magnetic material region (21) and a coil group (22); An external excitation current is connected to the coil group (22) of each grid unit (2), and the current density of the grid unit (2) is obtained according to the output voltage of the coil group (22).

2. A current density measuring device for a fuel cell stack according to claim 1, characterized in that: The substrate (1) comprises: a first PCB board (11), a second PCB board (12) and a third PCB board (13) which are stacked; The first PCB board (11) and the third PCB board (13) are used to be electrically connected to the two internal plates of the battery stack to be tested respectively; the second PCB board (12) is arranged between the first PCB board (11) and the third PCB board (13); the second PCB board (12) is provided with mounting holes corresponding to each of the grid units (2) one by one; each of the mounting holes is used to accommodate the corresponding magnetic material area (21).

3. A current density measuring device for a fuel cell stack according to claim 2, characterized in that: A plurality of electroplating areas (111) distributed in a matrix are provided on one side of the first PCB board (11) and the third PCB board (13) away from the second PCB board (12), and each of the electroplating areas (111) is arranged corresponding to each of the grid units (2).

4. A current density measuring device for a fuel cell stack according to claim 1, characterized in that: Each of the grid units (2) further comprises: A thermistor (23), wherein the thermistor (23) is arranged on one side of the corresponding magnetic material area (21).

5. The current density measuring device for a fuel cell stack according to claim 1, characterized in that: Each of the coil assemblies (22) comprises: A first coil (221), the first coil (221) being arranged on one side of the corresponding magnetic material area (21); A second coil (222), wherein the second coil (222) is arranged below the first coil (221), and one end of the second coil (222) serves as an input end of the excitation current; A third coil (223), wherein the third coil (223) and the second coil (222) are symmetrically arranged with the magnetic material area (21) as an axis, and the voltage across both ends of the third coil (223) is the output voltage of the corresponding coil group (22).

6. A current density measuring device for a fuel cell stack according to claim 5, characterized in that: Each of the second coils (222) in the same row is connected in series.

7. A current density measuring device for a fuel cell stack according to claim 5, characterized in that: Each of the third coils (223) in the same column is connected in series.

8. The current density measuring device for a fuel cell stack according to claim 1, characterized in that: Also includes: A signal processing circuit is connected to the coil group (22) of each grid unit (2), and is used to filter, amplify, convert and calculate the output voltage of each grid unit (2) to obtain the current density of the grid unit (2).

9. A current density measuring device for a fuel cell stack according to claim 8, characterized in that: Also includes: A host computer is connected to the signal processing circuit, and is used to obtain the current density of each grid unit (2) and generate a current density stress distribution table.

10. A current density measurement system for a fuel cell stack, characterized in that: It includes a current density measuring device for a fuel cell stack as described in claim 1.

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