CN113701824B - Device and method for testing local current density-temperature distribution of fuel cell - Google Patents
Device and method for testing local current density-temperature distribution of fuel cell Download PDFInfo
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- CN113701824B CN113701824B CN202111156019.1A CN202111156019A CN113701824B CN 113701824 B CN113701824 B CN 113701824B CN 202111156019 A CN202111156019 A CN 202111156019A CN 113701824 B CN113701824 B CN 113701824B
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Abstract
The invention provides a device and a method for testing local current density-temperature distribution of a fuel cell, belongs to the technical field of fuel cells, and can simultaneously realize real-time online measurement of local current density and temperature of the cell. The device comprises a PCB substrate and a plurality of measurement acquisition units. Each measurement and acquisition unit comprises a top layer current collection region, a PCB substrate insulation region, a bottom layer current lead, a metal current conduction through hole, a sampling Hall element and a temperature measurement through hole. Converting the measured current into an electric signal on a sampling Hall element circuit by utilizing a Hall effect, and acquiring, processing and analyzing the electric signal to obtain a local current density value of a corresponding area; and inserting a thermocouple wire into the temperature testing hole, and recording the temperature data in real time by using a data acquisition card. Compared with the prior art, the invention has the advantages of small influence on the battery, high reliability, high response speed and wide test range, and can simultaneously carry out real-time online measurement on the current density and the temperature distribution of any region in the battery.
Description
Technical Field
The invention relates to the technical field of fuel cells, in particular to a device and a method for testing local current density-temperature distribution of a fuel cell.
Background
The fuel cell is a highly efficient, clean and environmentally friendly power generation mode, and has been highly regarded by governments, enterprises and researchers of various countries, and is considered by most countries and enterprises to be the most promising next-generation automobile power source. With the further increase of energy-saving and emission-reducing force of the Chinese government and the successive departure of the targets of 'carbon neutralization', 'carbon peak reaching', and the like, the industrialization of the fuel cell is accelerated. However, the fuel cell also has the problems of cost, service life and the like, which hinders the popularization of large-scale commercialization of the fuel cell. In the practical application process, due to the difference of parameters such as the internal flow field structure of the fuel cell, the operation parameters of the cell, the internal water heat management and the like, the internal electrochemical reaction of the cell is not uniform, so that the uneven current density and temperature distribution of the internal reaction area of the cell are generated. The long-term operation of the fuel cell under such working conditions can lead to the increase of the attenuation rate of the membrane electrode, even the occurrence of local hot spots causes irreversible damage to the membrane electrode assembly, and the service life and the conversion efficiency of the fuel cell are greatly influenced. Therefore, the real-time online monitoring of the local current density-temperature distribution has important significance for prolonging the service life of the battery and reducing the operation cost of the battery.
In addition, by accurately measuring the local current density-temperature distribution in the fuel cell, the distribution conditions of water and reactants in the cell can be known, and a foundation is provided for designing a more reasonable flow channel structure, optimizing the gas supply rate and the operation mode of reaction gas, optimizing the load of a catalyst and better controlling the water distribution in the cell, so that the cell performance is enhanced and the service life of the cell is prolonged. Currently, a standard resistance method is generally adopted for monitoring local current density distribution inside a fuel cell, voltage drop generated on a standard resistor by current is measured, and then the current corresponding to a test area is calculated by using ohm's law. Southern science and technology university (application number: 201811125984.0) discloses a fuel cell internal partition detection bipolar plate, wherein resistors are arranged in through holes of two printed circuit boards, when current flows through two ends of the resistors, voltage difference is generated, and the current value of a corresponding area is calculated by using ohm's law. Electronic science and technology university (application number: 202011078944.2) also discloses a fuel cell internal current distribution online detection device, and local current density is measured by arranging a sampling resistor connected with a metalized through hole in the middle of a double-sided partition acquisition plate. Although the method can measure the current of the local area of the battery, the external resistance introduced into the test board causes the internal parameters of the battery to be greatly changed, especially the ohmic impedance of the battery, so that the measurement of the local current density is greatly different from the original battery parameters, and the measurement accuracy of the test resistance is still required to be further improved. Furthermore, for testing under locally high current conditions, the use of the resistance method has a severe heating phenomenon, with the possibility of creating the risk of the test board igniting, which is unacceptable for cells using hydrogen as fuel. For monitoring the temperature distribution inside the battery, usually, a thermistor is pre-embedded in a corresponding test area or a test board, a voltage-stabilized power supply is externally connected to two ends of the thermistor, and the temperature of the test area is obtained through the temperature variation characteristic of the thermistor. Linrui et al (application number: 201310123343.2) at the university of Tongji discloses a multifunctional on-line test printed circuit board for a fuel cell, which is formed by embedding a plurality of thermistors in a temperature test layer, sequentially connecting the thermistors in series at two ends of an external voltage-stabilized power supply to form an independent closed loop, and measuring the temperature through the temperature change characteristic of the thermistors. However, this method requires a complicated test circuit design and is difficult to maintain and replace. In addition, the base material used for the test board generally has poor heat conduction effect, and has certain hysteresis quality for measuring the change of the local temperature of the battery.
In a word, the prior disclosed technology and device greatly change the original parameters or structure of the fuel cell, and have certain limitations in the range and accuracy of local current measurement; for the test of the temperature distribution in the battery, the aspects of test circuit design, maintenance, operation and the like are complex, and certain hysteresis exists in the test. In the practical process, the on-line test with high development accuracy, high response speed and convenient operation is more significant for the development and application of the fuel cell.
Disclosure of Invention
The invention aims to make up for the technical defects and provides a fuel cell local current density-temperature distribution testing device and a method, which are used for improving the accuracy of local current density detection, reducing the influence of a testing process on inherent parameters of a cell and improving the reliability of detection. At the same time, the complexity and hysteresis of the local temperature testing process is reduced.
The specific technical scheme provided by the invention is as follows:
a fuel cell local current density-temperature distribution test apparatus, the apparatus comprising: the PCB comprises a PCB substrate and a plurality of measurement acquisition units distributed on the substrate; each measurement and acquisition unit comprises a sampling Hall element and a measurement and acquisition end; each measurement acquisition end is provided with a top layer current collection area, a middle PCB substrate insulation area, a metal current conduction through hole and a bottom layer current lead along the thickness direction of the PCB substrate; the top layer current collecting region is connected with a bottom layer current lead through a metal current conducting through hole penetrating through the PCB substrate, the other end of the bottom layer current lead is connected with a current inflow end of the sampling Hall element, current flows through the sampling Hall element and then is collected to a current common end by a current output end of the sampling Hall element, and the current common end is connected with an external load of the battery; the current is converted into other electric signals in the sampling Hall elements through the Hall effect, and the electric signal output end of each sampling Hall element is connected with the multi-channel data acquisition equipment;
a temperature measuring through hole is arranged below the top layer current collecting region, and a temperature measuring element is inserted into the temperature measuring through hole during temperature measurement and is used for carrying out real-time online monitoring on local temperature change in the fuel cell;
when the testing device is used, the testing device is hermetically fixed on the back side of the cathode flow field or the anode flow field of the fuel cell to be tested, and replaces a corresponding side current collecting plate.
Based on the scheme, preferably, the top layer current collecting region and the bottom layer current conducting wire are both formed by copper sheets; copper sheets are covered on the periphery of the metal current conducting through hole; the thickness of the copper sheet is 30-150 um, and a gold or silver coating is arranged on the surface of the copper sheet so as to reduce the contact resistance between the copper sheet and a battery flow field plate.
Based on the scheme, preferably, the copper-clad areas of the top current collecting areas of all the measurement and acquisition units are the same. The top layer current collecting regions of the measurement acquisition units are independent and insulated from each other.
Based on the scheme, preferably, the width of the bottom layer current lead is greater than or equal to 1mm, the length of the bottom layer current lead is basically consistent, large current can be allowed to pass through, and the resistance value in the lead is guaranteed to be consistent.
Based on the above scheme, preferably, the plurality of measurement acquisition ends are distributed in the middle lower part of the PCB substrate and are called as measurement areas, when the testing device is used, the measurement areas correspond to the positions of flow fields in the fuel cell, the plurality of sampling hall elements are fixed above the measurement areas on the PCB substrate in a welding manner, the sampling hall elements are high-precision hall effect current sensors, the resistance value is less than 1m Ω, and the hall elements used in each measurement acquisition unit are the same.
Based on the above scheme, preferably, the copper sheet covers the upper part of the PCB substrate sampling Hall element and serves as a common end for current input of each measurement and acquisition unit, so that the risk of board explosion of the testing device under high current is prevented. After the current of each measurement acquisition unit flows through the Hall element, the current flows into the common end, and the common end is connected with a load device outside the battery, so that the performance of the battery is further represented.
Based on the above scheme, preferably, the PCB substrate is provided with a power supply voltage circuit, and a capacitor element is arranged in a bypass of the power supply circuit to provide stable power supply voltage for the sampling hall element, so that the sampling hall element can work normally; the capacitance value of the capacitive element is determined by the supply voltage range.
Based on the above scheme, preferably, the electric signal output end circuit of the sampling hall element is connected with the fixed value resistor, and the capacitor element is arranged in the output end circuit bypass, so that the uniformity and accuracy of the output electric signal are ensured; the resistance value of the fixed value resistor and the capacitance value of the capacitor element are determined by specific specification parameters of the Hall element.
Based on the scheme, preferably, the temperature measuring through hole is positioned in the center of the top layer current collecting region and penetrates or does not penetrate through the top layer current collecting region; the temperature measuring element is a thermocouple wire.
The invention also provides a measuring method applied to the fuel cell local current density-temperature distribution testing device, which comprises the following steps: inserting a temperature measuring element into the temperature measuring through hole of the testing device and fixing the temperature measuring element; the testing device is hermetically fixed on the back side of the cathode flow field or the anode flow field of the fuel cell to be tested, and a corresponding side current collecting plate is replaced;
connecting a current common end on a PCB substrate with an external load line, testing the battery, wherein in the testing process, a top layer current collecting region of each measurement collecting unit collects currents at different positions of the fuel battery, the collected currents are input into a sampling Hall element through a metal current conducting through hole and a bottom layer current conducting wire, the sampling Hall element converts current signals into other electric signals through a Hall effect to be output, and the electric signals output by the sampling Hall element are synchronously collected through a multi-channel data collecting device; converting the corresponding electric signal into a current signal by utilizing the output characteristic corresponding to the Hall element to obtain the local current density distribution condition of the fuel cell;
the temperature of different positions in the fuel cell is measured through the temperature measuring element, and real-time recording is carried out by utilizing a data acquisition card, so that local temperature data of the fuel cell is obtained.
Compared with the prior art, the invention has the following advantages:
(1) the invention uses a high-performance Hall element for testing in local current density measurement, and uses Hall effect to measure, analyze and record the magnitude of the collected current. The Hall element has the advantages of small inherent resistance (the resistance value is less than 1m omega) and high thermal stability. Compared with the test by using a resistance element, the influence of the test assembly on the inherent parameters of the battery can be reduced by using the high-performance Hall element, and the reliability and the accuracy of the test are improved.
(2) According to the invention, the output end circuit of the sampling Hall element is connected with the constant value resistor, and the capacitor element is arranged in the bypass of the output end circuit, so that the uniformity and accuracy of the output electric signal are ensured; the fixed value resistance value and the capacitance value of the capacitor element are determined by specific specification parameters of the Hall element.
(3) The invention coats the large-area copper sheet on the surface of the PCB substrate as a common end for current to flow in, reduces the resistance value of the current lead, has the advantages of allowing the battery to be tested under high current, reducing the high-temperature phenomenon of a testing device under high current, preventing the danger of board explosion and having higher safety.
(4) The temperature measuring through hole is formed in the middle of each current collecting region, and the local temperature change of the battery can be monitored in real time on line by inserting the thermocouple wire. The temperature measuring circuit has the advantages that the circuit design in the local temperature measuring process can be greatly simplified, and the operation and the maintenance are convenient. The change process of the local temperature can be reflected in time, and the hysteresis quality of the local temperature measurement is reduced.
(5) The local current density-temperature distribution test board can be placed on any side of the cathode or anode of the battery, is not limited by the type of the cathode and anode flow fields, can simultaneously carry out real-time online monitoring on the local current density-temperature, and has the advantages of simple structure, easy manufacture and convenient operation.
Drawings
FIG. 1 is a schematic diagram of a local current density testing circuit of the local current density-temperature distribution testing board according to the present invention.
Fig. 2 is a perspective assembly view of a fuel cell employing a local current density-temperature distribution testing apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic structural diagram of a test board for local current density-temperature distribution according to an embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a measurement acquisition unit provided in an embodiment of the present invention along a thickness direction of a PCB substrate.
FIG. 5 shows a measurement fuel cell 200mA/cm provided by an embodiment of the invention 2 Time current density profile.
FIG. 6 shows a measurement of 500mA/cm for a fuel cell in accordance with an embodiment of the present invention 2 Time current density profile.
FIG. 7 shows a fuel cell with a measurement of 800mA/cm according to an embodiment of the present invention 2 Time current density profile.
FIG. 8 is a graph of a 500mA/cm measurement fuel cell provided by an embodiment of the present invention 2 Time local temperature versus time graph.
FIG. 9 is a 500mA/cm measurement of fuel cells provided by an embodiment of the present invention 2 Time-varying battery high frequency impedance versus time.
The notation in the figure is:
1. the device comprises a battery end plate, 2, a battery current collecting plate, 3, a battery flow field plate, 4, a membrane electrode, 5, a battery flow field plate, 6, a local current density-temperature distribution testing device, 7, a battery end plate, 8, a PCB (printed Circuit Board) substrate, 9, a measurement acquisition end, 10, a sampling Hall element, 11, a power supply voltage end, 12, a sampling Hall element electrical signal output end, 13, a top layer current collecting region, 14, a PCB substrate insulating region, 15, a bottom layer current lead, 16, a metal current conducting through hole, 17 and a temperature measuring through hole.
Detailed Description
Examples
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the following specific embodiments, but the present invention is not limited to these embodiments.
FIG. 1 is a schematic diagram of a local current density testing circuit of the local current density-temperature distribution testing board of the present invention, wherein Vcc represents an external power supply voltage, and is connected to the power supply terminal of each sampling Hall element through a power supply circuit. A capacitor element is arranged in a bypass of a power supply circuit of each Hall element, so that the power supply voltage of the sampled Hall element is stable, the sampled Hall element works normally, and the capacitance value of the capacitor element is determined by the range of the power supply voltage. The current flowing in through the bottom layer current lead enters the Hall element through the inflow end IP + of the Hall element, and the current is collected to the current common end from the IP-outflow end after flowing through the Hall element. The current is converted into other electric signals in the Hall element by utilizing the Hall effect, the electric signals are output at an output end OUT, and the electric signals are synchronously acquired through the multichannel high-speed data acquisition equipment ADC/MCU. The circuit of the electric signal output end of the sampling Hall element is connected with a fixed value resistor, a capacitor element is arranged in a bypass of the circuit of the output end, the resistance value of the fixed value resistor and the capacitance value of the capacitor element are determined by specific specification parameters of the Hall element, and the uniformity and the accuracy of the output electric signal are guaranteed.
An embodiment of the present invention provides a cell using a local current density-temperature distribution testing apparatus for a fuel cell, as shown in fig. 2, including: the device comprises a cell end plate 1, a cell collector plate 2, a cell flow field plate 3, a membrane electrode 4, a cell flow field plate 5, a local current density-temperature distribution testing device 6 and a cell end plate 7; the local current density-temperature distribution testing device is shown in fig. 3 and comprises a PCB substrate 8, a plurality of measurement acquisition ends 9 distributed on the substrate, a sampling Hall element 10, a power supply voltage end 11 and a sampling Hall element electric signal output end 12; the structure of the measurement and collection unit is shown in fig. 4, and comprises a top layer current collection area 13, a middle PCB substrate insulation area 14, a bottom layer current lead 15, a metal current conducting through hole 16, a sampling hall element 10 and a temperature measurement through hole 17 in the middle of the current collection area.
The battery end plate 1 and the battery end plate 7 can be made of organic glass, phenolic resin, epoxy resin, stainless steel and other materials, reaction gas inlet and outlet and cooling water inlet and outlet are processed on two sides of the battery end plate, and the battery end plate mainly plays a role in fixing a battery assembly.
The battery current collecting plate 2 adopts a copper plate as a substrate material, and gold or silver is plated on the surface of the copper plate to reduce the contact resistance between the copper plate and a battery current flow field plate.
The battery flow field plate 3 and the battery flow field plate 5 are machined by graphite materials, and the flow field type adopts a parallel groove flow field; the invention can be applied to different flow field types, such as a snake-shaped flow field, a point-shaped flow field, an S-shaped flow field, a three-dimensional flow field and the like, so that the invention does not limit the flow field types.
The membrane electrode 4 has an effective active area of 50cm 2 The proton exchange membrane is made up by using gas diffusion layer formed from carbon paper coated with microporous layer and platinum carbon as catalyst, and placing the perfluorosulfonic acid proton exchange membrane in the cut polyester frame and making hot-pressing treatment.
The PCB substrate 8 is made of an insulating material and has the thickness of 2.0mm, and a copper sheet is stuck to the top layer of the current collecting region 13 on the top layer of the substrate and has the thickness of 70 microns; and plating gold on the surface of the copper sheet to reduce the contact resistance with a battery flow field plate.
The top layer current collecting regions 13 of the measurement collecting end 9 are uniformly distributed on the surface of the PCB substrate 2 in a 4 multiplied by 8 array manner; the number of the measurement acquisition ends 9 can be set according to the actual measurement area size and the measurement precision, which is not limited in the embodiment of the present invention.
The copper-clad areas of the top layer current collecting regions 13 of each measurement collecting end 9 are the same. The top layer current collecting regions 13 are independent from each other and insulated from each other.
The current collected by each current collection area 13 is connected with the bottom layer current lead 15 through the metal current conduction through hole 16 on the PCB, and the metal current conduction through hole 16 and the bottom layer current lead 15 are formed by copper sheets with the thickness of 70 um.
The width of the bottom layer current lead 15 is 1.0mm, the length is basically kept consistent, large current can be allowed to pass through, and the resistance value in the lead is guaranteed to be consistent.
The current collected by each measurement collecting end 9 flows into a corresponding Hall element 10 above the measurement area through a bottom layer current lead, the Hall element 10 is fixed on a PCB above the measurement area in a welding mode, and the collected current is measured by utilizing the Hall effect.
The sampling Hall element 10 is a high-precision Hall effect current sensor, is packaged by SOP8, is provided with a differential common mode suppression circuit, can enable the output of the element not to be influenced by external interference magnetic signals, has the testing current range of 0-5A, the working temperature range of-40 ℃ to +125 ℃, the resistance value of 0.9m omega, and is the same as the Hall element 10 used by each measurement and acquisition unit.
The PCB substrate 8 surface is covered with large tracts of land copper sheet, and thickness is 70um, and as the electric current common port, one side is connected with every sampling Hall element 10 electric current outflow end, and the opposite side is connected with battery external load device, further reduces the resistance of electric current wire, can allow heavy current to flow through, reduces testing arrangement and appears exploding the danger of board under the heavy current.
The PCB substrate 8 is provided with a 3.3V-5.0V power supply voltage end 11, and a 0.1uF capacitor element is arranged in parallel in the voltage power supply bypass to provide stable power supply voltage for the sampling Hall element 10 so as to enable the sampling Hall element to work normally.
The circuit of the electric signal output end 12 of the sampling Hall element 10 is connected with a 100 omega constant value resistor in series, and a 0.1nF capacitor element is arranged in parallel in an output end circuit bypass, so that the uniformity and accuracy of an output electric signal are ensured.
The middle of the top layer current collection region 13 is provided with a temperature measurement through hole 17, local temperature change of the battery can be monitored on line in real time by inserting K-type, T-type, J-type and other thermocouple wires, and the embodiment of the invention does not limit the type of the thermocouple wires.
The embodiment of the invention also provides a cell measuring method applied to the fuel cell local current density-temperature distribution testing device, which comprises the following steps:
selecting key areas for measuring the temperature of part of the battery, such as a reaction gas inlet, a reaction gas outlet, a middle area, an edge area and the like, inserting thermocouple wires into the temperature measuring through holes 17 in the corresponding areas, and sealing and fixing the thermocouple wires by using vulcanized silicone rubber;
inserting a local current density-temperature distribution testing device 6 into the back side of any one of a flow field plate 3 or a flow field plate 5 of a fuel cell to be tested to replace a corresponding side cell current collecting plate 2, sealing different components by using a sealing silica gel material, clamping a cell end plate 1 and a cell end plate 7 by using a screw rod, and fixing each component of the cell with a cell assembling force of 3.0 N.m;
connecting a current common end on the PCB substrate 8 with an external electronic load to test the battery;
after the current of each measurement and acquisition end 9 flows through the corresponding sampling Hall element 10, the output end of the sampling Hall element 10 outputs an electric signal, the electric signal is synchronously acquired by a multichannel high-speed acquisition system data acquisition device, the corresponding electric signal is converted into a current signal by utilizing the corresponding output characteristic of the sampling Hall element 10, and data analysis and discussion are carried out;
the local temperature data is measured by a thermocouple wire and is recorded in real time by a data acquisition card.
Fig. 5-7 are two-dimensional local current density distribution diagrams of a cell using a local current density-temperature distribution test device according to an embodiment of the present invention, the anode of the fuel cell is in a hydrogen circulation mode, and the operating temperature of the cell is set to 60 ℃. From the three current density distribution diagrams, it was found that the local current density was not uniformly distributed in the battery, and the nonuniformity of the local current density distribution increased as the average current density increased. At an average current density of 500mA/cm or more 2 The local current density in the air inlet region of the cell is higher, because the reactant concentration in the inlet region is higher, the hydrothermal management is better; the local current density is lower near the cell air outlet region, primarily due to the depletion of reactants along the flow path, where the concentration of reactants is lower. In addition, the air outlet is easy to be flooded by water, and the air outlet can also be used for controlling the air outletThe local current density decreases in the area. In conclusion, the device of the invention can well measure the local current density in the fuel cell and well reflect the current density distribution condition.
FIG. 8 is a graph of a cell employing a local current density-temperature distribution test apparatus at 500mA/cm in an example of the present invention 2 A graph of local temperature versus time, wherein the middle zone 1 represents the middle zone near the air inlet and the middle zone 2 represents the middle zone near the air outlet. The anode of the fuel cell is in a hydrogen circulation mode, and the operating temperature of the cell is set to 60 ℃. From the local temperature change curves of different regions along with time, the internal temperature distribution of the battery is not uniform. The temperature was higher in the middle region at and near the air inlet, with average temperatures of 60.2 c and 60.8 c, respectively, above the set cell operating temperature. The reason is that the reactant concentrations in the two areas are high, so that the reaction with good hydrothermal management releases large heat; the temperature was lowest at the air outlet, with an average temperature of 59.5 c each, below the set cell operating temperature. This is because the reactant concentration in this region is small and the exothermic heat of reaction is small. In addition, the unreacted air discharged at the outlet also takes away a part of the heat, so that the temperature at the air outlet is low. Through the analysis, the local temperature distribution has great influence on the local performance of the battery, and the change in the battery can be more accurately analyzed through the combination of the local temperature distribution and the local current density distribution.
FIG. 9 shows a cell using a local current density-temperature distribution test apparatus at 500mA/cm in an example of the present invention 2 The high-frequency impedance of the fuel cell is changed along with the time curve chart, the anode of the fuel cell is in a hydrogen circulation mode, and the working temperature of the fuel cell is set to be 60 ℃. Curve 1 in the figure represents the fuel cell high frequency impedance over time without the use of a local current density-temperature distribution test apparatus; curve 2 represents the fuel cell high frequency impedance over time using the local current density-temperature distribution test apparatus. The test conditions of the two curves are consistent with the initial state of the battery, so that the high-frequency resistance of the battery is passedThe change may indirectly reflect a change in ohmic impedance within the cell. It can be derived from the graph that the average high frequency resistance value of 2.55mOhm of the battery using the local current density-temperature distribution test device is almost identical to the high frequency resistance value of the battery not using the present invention. The local current density-temperature distribution testing device is applied to accurately measure the local current density-temperature of the fuel cell, and meanwhile, the influence on the inherent parameters of the cell can be almost ignored, and the measurement reliability is ensured.
In the above description, the present invention is described with reference to the accompanying drawings, which are used to illustrate and describe embodiments of the invention, and not to limit the invention.
Claims (10)
1. A fuel cell local current density-temperature distribution testing apparatus, comprising: the PCB comprises a PCB substrate and a plurality of measurement acquisition units distributed on the substrate; each measurement and acquisition unit comprises a sampling Hall element and a measurement and acquisition end;
each measurement acquisition end is provided with a top layer current collection area, a middle PCB substrate insulation area, a metal current conduction through hole and a bottom layer current lead along the thickness direction of the PCB substrate; the top layer current collecting region is connected with a bottom layer current lead through a metal current conducting through hole penetrating through the PCB substrate, the other end of the bottom layer current lead is connected with a current inflow end of the sampling Hall element, current flows through the sampling Hall element and then is collected to a current common end by a current output end of the sampling Hall element, and the current common end is connected with an external load of the battery; the current is converted into other electric signals in the sampling Hall elements through the Hall effect, and the electric signal output end of each sampling Hall element is connected with the multi-channel data acquisition equipment;
a temperature measuring through hole is arranged below the top layer current collecting region, and a temperature measuring element is inserted into the temperature measuring through hole during temperature measurement and is used for carrying out real-time online monitoring on local temperature change inside the fuel cell;
when the testing device is used, the testing device is hermetically fixed on the back side of the cathode flow field or the anode flow field of the fuel cell to be tested, and replaces a corresponding side current collecting plate.
2. The local current density-temperature distribution test device of claim 1, wherein the top-layer current collection region and the bottom-layer current lead are each formed of a copper sheet; copper sheets are covered on the periphery of the metal current conducting through hole; the thickness of the copper sheet is 30-150 um, and a gold or silver coating is arranged on the surface of the copper sheet.
3. The local current density-temperature distribution testing device according to claim 1, wherein the copper-clad area of the top current collecting region of each measurement and collection unit is the same; the top layer current collecting regions of the measurement acquisition units are independent and insulated from each other.
4. The local current density-temperature distribution testing device according to claim 1, wherein the width of the bottom layer current lead is greater than or equal to 1mm, and the lengths of the bottom layer current leads of the measurement acquisition units are kept consistent, so that a large current is allowed to pass through.
5. The local current density-temperature distribution testing device according to claim 1, wherein a plurality of measurement collection terminals are arrayed and distributed below the middle part of the PCB substrate, called a measurement area, when the testing device is in use, the measurement area corresponds to the position of a flow field in a fuel cell, a plurality of sampling hall elements are fixed above the measurement area on the PCB substrate in a welding manner, the sampling hall elements are high-precision hall effect current sensors, the resistance value is less than 1m Ω, and the hall elements used in each measurement collection unit are the same.
6. The local current density-temperature distribution testing device according to claim 1, wherein a copper sheet is covered on the upper part of the sampling Hall element of the PCB substrate and is used as a common end for current input of each measurement acquisition unit.
7. The local current density-temperature distribution testing device according to claim 1, wherein a supply voltage circuit is provided on the PCB substrate, and a capacitive element is provided in a bypass of the supply voltage circuit to provide a stable supply voltage for the sampling hall element; the capacitance value of the capacitive element is determined by the supply voltage range.
8. The local current density-temperature distribution testing device according to claim 1, wherein a circuit of an electrical signal output end of the sampling hall element is connected with a constant value resistor, and a capacitor element is arranged in a bypass of the output end circuit to ensure uniformity and accuracy of an output electrical signal; the fixed value resistance value and the capacitance value of the capacitor element are determined by specific specification parameters of the Hall element.
9. The local current density-temperature distribution testing device as claimed in claim 1, wherein the temperature measuring through hole is located at the center of the top layer current collecting region, and penetrates or does not penetrate the top layer current collecting region; the temperature measuring element is a thermocouple wire.
10. A measurement method applied to the local current density-temperature distribution test device according to any one of claims 1 to 9, wherein the method comprises the following steps:
inserting a temperature measuring element into the temperature measuring through hole of the testing device and fixing the temperature measuring element; the testing device is hermetically fixed on the back side of a cathode flow field or an anode flow field of the fuel cell to be tested, and a corresponding side current collecting plate is replaced;
connecting a current common end on a PCB substrate with an external load line, testing the battery, wherein in the testing process, a top layer current collecting region of each measurement collecting unit collects currents at different positions of the fuel battery, the collected currents are input into a sampling Hall element through a metal current conducting through hole and a bottom layer current conducting wire, the sampling Hall element converts current signals into other electric signals through a Hall effect to be output, and the electric signals output by the sampling Hall element are synchronously collected through a multi-channel data collecting device; converting the corresponding electric signal into a current signal by utilizing the output characteristic corresponding to the Hall element to obtain the local current density distribution condition of the fuel cell;
the temperature of different positions in the fuel cell is measured through the temperature measuring element, and real-time recording is carried out by utilizing a data acquisition card, so that local temperature data of the fuel cell is obtained.
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| EP1691438A1 (en) * | 2005-02-15 | 2006-08-16 | Paul Scherer Institut | Fast locally resolved electrochemical impedance spectroscopy in polymer electrolyte fuel cells |
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