A device-level thermoelectric parameter testing device based on electrical parameter identification

Abstract

The present disclosure provides a device-level thermoelectric parameter testing device based on electrical parameter identification, belonging to the technical field of thermoelectric device testing. The same first thermoelectric sheet and second thermoelectric sheet have their hot ends facing each other, and a thermal resistance plate is sandwiched between them, so that there is a temperature difference between the hot ends of the two thermoelectric sheets; the first temperature controller is connected to the cold end of the first thermoelectric sheet, and the second temperature controller is connected to the cold end of the second thermoelectric sheet to control the temperature of the cold ends of the thermoelectric sheets; a current I1 is passed through the first thermoelectric sheet as a heat source, and the second thermoelectric sheet uses the thermoelectric power generation principle as a heat flow meter; by controlling the temperatures of the cold ends of the two thermoelectric sheets and the current I1 passed through the first thermoelectric sheet, the average temperatures of the two thermoelectric sheets to be tested are made the same, that is, in the equivalent temperature condition and having the same thermoelectric parameters; based on the equivalent relationship between the two thermoelectric sheets, the thermoelectric parameters of the thermoelectric sheets to be tested are determined by using the temperatures of the hot and cold ends and the electrical parameters of the two thermoelectric sheets. Using the present invention can accurately evaluate the performance of thermoelectric devices.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric device testing, in particular to the testing of physical properties and performance of device-level thermoelectric devices, and specifically to a device-level thermoelectric parameter testing device based on electrical parameter identification. Background Art

[0002] Thermoelectric devices are increasingly widely used in fields such as energy recovery, electronic cooling, and temperature control. With the research and development of high-efficiency thermoelectric materials and the progress of manufacturing technology, the application potential of thermoelectric technology in fields such as new energy, aerospace, and intelligent wearable devices is continuously increasing, and it has gradually become an important part of green energy technology.

[0003] The performance parameters of thermoelectric materials directly affect the efficiency and performance of thermoelectric devices. In a thermoelectric refrigeration system, low thermal conductivity and high Seebeck coefficient can maximize the refrigeration effect, while the internal resistance of the device needs to find a balance between good electrical conductivity and low thermal conductivity to ensure the efficient operation of the system. Accurately extracting these physical properties parameters can quantify the energy efficiency of thermoelectric power generation and refrigeration systems and promote the wide application of thermoelectric technology in various fields.

[0004] In actual applications, although the physical parameters of thermoelectric materials can be measured during device production, due to differences in the inherent properties, structural design, and manufacturing processes of the materials, there are significant differences between the physical property parameters of the device and those of the material.

[0005] Device-level thermoelectric parameters refer to simplifying the physical property parameters into the Seebeck coefficient α 、total internal resistance R and total thermal conductivity K of the whole device by ignoring the specific values of the interfacial contact thermal resistance and resistance of the device. These parameters usually vary with temperature. Device-level physical property parameters are an embodiment of comprehensive performance and are affected by more external factors. The tests carried out by manufacturers on device-level parameters are not standardized and unified enough. When applying thermoelectric devices, it is necessary to accurately evaluate their parameters in order to perform more precise calculations.

[0006] Currently, there are many methods and devices for accurately testing the physical property parameters of thermoelectric devices. The measurement of the Seebeck coefficient and the internal resistance of the device are usually relatively easy to obtain. However, since the thermal conductivity needs to be calculated by measuring the heat flux, traditional thermal resistance type heat flux meters often have large errors, long testing processes, and require a vacuum environment. Especially in the low temperature range below 150 °C, the decrease in heat flow makes the temperature difference change not obvious, and the measurement accuracy of thermal conductivity is even lower.

[0007] To accurately evaluate the performance of thermoelectric devices under actual working conditions in the low temperature range, it is necessary to develop an accurate and rapid method for testing device-level physical property parameters that can be applied to most size types of thermoelectric devices. Summary of the Invention

[0008] In view of this, the present invention provides a device-level thermoelectric parameter testing device based on electrical parameter identification, which has accurate calculation and small heat flow and heat loss when the heat flow is small, avoiding the disadvantages of traditional thermoelectric testing devices that rely on precise machining of heat conduction blocks and vacuum environments.

[0009] To solve the above technical problems, the present invention is implemented as follows.

[0010] A device-level thermoelectric parameter testing device based on electrical parameter identification includes: a first temperature controller, a second temperature controller, two identical thermoelectric chips to be tested, a thermal resistance plate, a temperature sensor, a measurement component, a current source, and a calculation module;

[0011] The two identical thermoelectric chips to be tested include a first thermoelectric chip and a second thermoelectric chip, which are face-to-face and relatively attached so that the heat flow is in series; the inner sides of the two thermoelectric chips to be tested are hot ends, and the outer sides are cold ends; temperature sensors are provided at the hot ends of the two thermoelectric chips; the first temperature controller is connected to the cold end of the first thermoelectric chip, and the second temperature controller is connected to the cold end of the second thermoelectric chip to control the cold end temperature of the thermoelectric chip; the thermal resistance plate is arranged between the first thermoelectric chip and the second thermoelectric chip so that there is a temperature difference between the hot ends of the two thermoelectric chips;

[0012] A current I1 provided by the current source is passed through the first thermoelectric chip as a heat source, and the second thermoelectric chip uses the thermoelectric power generation principle as a heat flow meter;

[0013] By controlling the cold end temperatures of the two thermoelectric chips and the current I1 passed through the first thermoelectric chip, the average temperatures T0 of the hot and cold ends of the two thermoelectric chips to be tested are made the same. At this time, under the equivalent temperature condition, the two thermoelectric chips have the same thermoelectric parameters under the current temperature condition T0;

[0014] The measurement component is used to measure the electrical parameters of the second thermoelectric chip under the current temperature condition when the two thermoelectric chips are under the equivalent temperature condition, including the open circuit voltage U, the device internal resistance R, and the current I2;

[0015] The calculation module is used to determine the thermoelectric parameters of the thermoelectric chip to be tested based on the equivalent relationship between the two thermoelectric chips and by using the hot and cold end temperatures and electrical parameters of the two thermoelectric chips.

[0016] Preferably, the thermal resistance plate has the same size as the thermoelectric chip. By selecting the thermal conductivity of the thermal resistance plate, the temperature difference between the hot ends of the two thermoelectric chips is made to be between 5°C and 8°C.

[0017] Preferably, the first temperature controller and the second temperature controller adopt a combination of a third thermoelectric chip and a water-cooled radiator; the third thermoelectric chip provides a cold plate or a hot plate for the thermoelectric chip to be tested through bidirectional current control, and the water-cooled radiator is used to maintain the refrigeration performance when the third thermoelectric chip provides a cold plate.

[0018] Preferably, the measurement component includes an open-circuit voltage measurement device, an internal resistance measurement device, and an electronic load;

[0019] The calculation module includes a Seebeck coefficient α calculation module, an internal resistance R determination module, and a thermal conductivity K calculation module;

[0020] The Seebeck coefficient α calculation module is used to obtain the hot-end temperature and the cold-end temperature of the second thermoelectric sheet, and in combination with the open-circuit voltage U of the second thermoelectric sheet measured by the open-circuit voltage measurement device, the Seebeck coefficient α is calculated using Equation (1):

[0021] (1)

[0022] The internal resistance R determination module is used to obtain the device internal resistance R of the second thermoelectric sheet from the internal resistance measurement device;

[0023] The thermal conductivity K calculation module is used to, after the electronic load is connected in series with the second thermoelectric sheet acting as a heat flow meter to form a path, and after readjusting the average temperature T0 of the two thermoelectric sheets to remain unchanged, obtain the hot-end temperature and the cold-end temperature of the second thermoelectric sheet, as well as the hot-end temperature and the cold-end temperature of the first thermoelectric sheet; obtain the current I2 at this time from the electronic load;

[0024] For the heat flux Q h1 at the hot end of the first thermoelectric sheet serving as a heat source

[0025] (2)

[0026] For the heat flux Q h2 at the hot end of the second thermoelectric sheet serving as a heat flow meter

[0027] (3)

[0028] Neglecting heat loss, there is Q h1 = Q h2 That is,

[0029] (4)

[0030] From the above Equation (4), the total thermal conductivity K of the corresponding temperature device under the current temperature condition T0 is solved.

[0031] Preferably, through the temperature regulation of the first temperature controller and the second temperature controller, and by adjusting the current I1 applied to the first thermoelectric sheet through the current source, the temperature difference between the hot and cold ends of the first thermoelectric sheet and the second thermoelectric sheet is made less than 20 °C.

[0032] Preferably, the device further comprises: a base, a bracket, a pressure sensor, a hydraulic regulator, and a top plate;

[0033] The base is supported by the bracket between the base and the top plate; a pressure sensor is fixed on the upper side of the base for real-time monitoring of the pressure when measuring the thermoelectric sheet to be measured; a temperature controller is fixed at the upper end of the pressure sensor; the hydraulic regulator is fixed on the lower side of the top plate for providing a downward pressure and cooperating with the pressure sensor for pressure control; another temperature controller is fixed at the lower end of the hydraulic regulator; two relatively fitted thermoelectric sheets, the first thermoelectric sheet is on the upper side, or the second thermoelectric sheet is on the upper side, are fixed between the base and the top plate.

[0034] Preferably, the shape of the thermal resistance plate is the same as that of the thermoelectric sheet, and temperature sensors are installed on two surfaces of the thermal resistance plate to respectively measure the hot-end temperature T h1 of the first thermoelectric sheet connected to the upper surface and the hot-end temperature T h2 of the second thermoelectric sheet; the side surface of the thermal resistance plate is coated with heat-insulating material, and the bonding surface with the thermoelectric sheet is coated with thermal conductive silicone grease.

[0035] The present invention also provides a device-level thermoelectric parameter testing method based on electrical parameter identification, adopting the above device-level thermoelectric parameter testing device. The method comprises the following steps:

[0036] Step 1: Turn on the first temperature controller and maintain room temperature; use the first thermoelectric sheet as a heat source and the second thermoelectric sheet as a heat flow meter; the current source passes an initial current into the first thermoelectric sheet, and the second thermoelectric sheet remains open.

[0037] Step 2: Turn on the first temperature controller and the second temperature controller, and adjust the temperatures of the two temperature controllers and the current I1 passed into the first thermoelectric sheet so that the average temperatures of the hot and cold ends of the two thermoelectric sheets are both raised to the measurement temperature condition T0.

[0038] Step 3: Use the measurement component to measure the electrical parameters of the second thermoelectric sheet under the current temperature condition, obtain the device internal resistance R and calculate the Seebeck coefficient α.

[0039] Step 4: Connect the electronic load to make the second thermoelectric sheet conductive, readjust the temperature to be the same as in Step 2, and measure the current I2 of the second thermoelectric sheet.

[0040] Step 5: Based on the device internal resistance R, the Seebeck coefficient α of the thermoelectric sheet, and the currents I1 and I2 of the two thermoelectric sheets, and based on the equivalent relationship between the two thermoelectric sheets, determine the thermal conductivity K of the thermoelectric sheet to be measured.

[0041] Preferably, the calculation of the Seebeck coefficient α in step 3 is as follows:

[0042] Obtain the hot-end temperature of the second thermoelectric sheet from the sensor and the cold-end temperature , and combine with the open-circuit voltage U of the second thermoelectric sheet measured by the open-circuit voltage measuring device, and calculate the Seebeck coefficient α using Equation (1):

[0043] (1)

[0044] The determination of the thermal conductivity K of the thermoelectric sheet to be measured in step 5 is as follows:

[0045] Obtain the hot-end temperature of the second thermoelectric sheet and the cold-end temperature , as well as the hot-end temperature of the first thermoelectric sheet and the cold-end temperature ; keep the average temperature T0 of the two thermoelectric sheets unchanged, and obtain the current I2 at this time from the load resistor;

[0046] For the heat flux of the first thermoelectric sheet as the heat source Q h1 :

[0047] (2)

[0048] For the heat flux of the second thermoelectric sheet as the heat flow meter Q h2 :

[0049] (3)

[0050] Ignoring heat loss, there is , that is

[0051] (4)

[0052] Solve the thermal conductivity K of the thermoelectric sheet corresponding to the current temperature condition T0 from the above formula (4).

[0053] Preferably, the method further includes:

[0054] Step 6: Adjust the average temperature to different measurement points, and obtain the Seebeck coefficient, device internal resistance, and total thermal conductivity of the thermoelectric sheet under different temperature conditions; use the least squares method to respectively fit the curves of the three thermoelectric parameters changing with temperature;

[0055] Step 7: Test the maximum conversion efficiency of the thermoelectric chip under a working condition: Remove the heat resistance plate, use the first temperature controller as the heat source, the first thermoelectric chip as the heat flow meter, and the second thermoelectric chip as the thermoelectric chip to be tested for thermoelectric conversion efficiency; Adjust the hot-end temperature \(T\) of the first thermoelectric chip through the first temperature controller h1 , and use the second temperature controller to adjust the cold-end temperature of the second thermoelectric chip so that the temperature at both ends of the second thermoelectric chip can reach the required temperature values at the hot and cold ends under the current test working condition;

[0056] Keep the cold and hot-end temperatures of the second thermoelectric chip unchanged, connect the second thermoelectric chip to the electronic load, adjust the resistance of the electronic load to make the output efficiency reach the maximum value, and read out the electric power \(W1\) at this time; Measure the cold-end temperature \(T\) of the first thermoelectric chip c1 and the hot-end temperature \(T\) h1 , as well as the input current \(I1\);

[0057] According to the curve of the device-level thermoelectric parameters changing with temperature measured in Step 6, interpolate to obtain the thermoelectric parameters at the cold and hot-end temperatures at this time, and use formula (2) to calculate the heat flow input to the hot end of the second thermoelectric chip Q h1 , then the maximum thermoelectric conversion efficiency is (\(W1 / Q h1 \)) 100%;

[0058] Step 8: Test the cooling capacity and cooling efficiency of the thermoelectric chip under a working condition:

[0059] Pass current through both the first thermoelectric chip and the second thermoelectric chip. Among them, the first thermoelectric chip is used as the thermoelectric chip to be tested for refrigeration, and the second thermoelectric chip is used as the heat flow meter and provides the heat load for the first thermoelectric chip Q h3 , and at this time there is a cooling capacity Q c = Q h3 ; Keep the hot-end and cold-end temperatures of the first thermoelectric chip consistent with the temperatures under the test working condition by the first temperature controller and the second thermoelectric chip respectively; Measure the hot-end temperature \(T\) of the second thermoelectric chip h3 , the cold-end temperature \(T\) c3 and the input current \(I3\). At this time, there is Q c = Q h3 , and the cooling capacity \(Q\) of the first thermoelectric chip can be calculated using the following formula (5) c ;

[0060] (5)

[0061] Calculate the cooling efficiency according to the electric power input value \(W2\) displayed by the electronic load. The cooling efficiency \(COP = (\Q c / W2) 100%.

[0062] Beneficial effects:

[0063] (1) Traditional thermal resistance type heat flux meters rely on a heat conducting block to equivalent one-dimensional heat transfer and perform multi-point temperature measurements. When the heat flux is small, the temperature difference between each point is not significant, and it is difficult to control the calculation error. Other heat flux meters based on the Seebeck effect or thin film type heat flux meters, etc., all require calibration and need to be processed into a suitable shape according to actual requirements. However, the heat flux calculation method adopted by the present invention can directly use the uncalibrated thermoelectric sheet to be measured, and does not completely rely on temperature measurement, but uses current parameters for calculation, greatly improving the convenience and accuracy of measuring the physical properties of thermoelectric devices.

[0064] The present invention can accurately and quickly measure the open circuit voltage, internal resistance and heat flux of thermoelectric devices at different temperatures in the low temperature range below 150 °C, so as to calculate parameters such as the Seebeck coefficient and thermal conductivity of the thermoelectric devices, avoiding the disadvantages of traditional thermoelectric testing devices relying on precise processing of heat conducting blocks and vacuum environment.

[0065] (2) When testing thermoelectric parameters, the present invention uses a heat resistance plate for isolation, generates a temperature difference between the hot ends of two thermoelectric devices relying on heat flux, and then makes the two devices in an equivalent temperature condition through cold end temperature control and identifies different electrical parameters, reducing the test error.

[0066] (3) According to the relationship among the hot end temperature T h of the thermoelectric device, the cold end temperature T c , and the current I1, the average temperature T0 of the thermoelectric device is adjusted to change, so that the present method can measure the curve of the thermoelectric parameters changing with temperature.

[0067] (4) The present invention uses a device coupling thermoelectric refrigeration and a liquid cooling plate as a temperature controller, and the temperature value on one side of the temperature controller is adjusted by a PID control system. Compared with a single water cooling temperature control method, the response is faster, and a large range of temperature change can be provided.

[0068] (5) The test method adopted by the present invention is relatively simple and accurate. Since one of the thermoelectric sheets to be measured is used to calculate the heat flux, and the heat resistance plate has heat insulation measures, the convective and radiative heat losses are very small. There is no need for heat insulation in a vacuum environment and no need to process a heat conducting block, reducing the processing cost.

[0069] (6) The present invention provides a device-level thermoelectric parameter test scheme that can be closer to the working state of the thermoelectric sheet. Compared with the test scheme using a vacuum environment, this scheme can better reflect data such as the thermoelectric conversion efficiency or heat flux of the thermoelectric device under the actual working state. Description of the Drawings

[0070] Figure 1 This is the schematic diagram of the device-level thermoelectric parameter test scheme based on electrical parameter identification of the present invention;

[0071] Figure 2 This is the temperature gradient diagram during the test process of the present invention;

[0072] Figure 3 This is the structural diagram of the device-level thermoelectric parameter test device based on electrical parameter identification of the present invention;

[0073] Figure 4 This is the flowchart of the device-level thermoelectric parameter test method based on electrical parameter identification of the present invention;

[0074] Figure 5 This is the schematic diagram for testing the maximum thermoelectric conversion efficiency;

[0075] Figure 6 This is the schematic diagram for testing the cooling capacity and cooling efficiency;

[0076] Among them, 1 - the first thermoelectric sheet (thermoelectric sheet to be tested); 2 - the second thermoelectric sheet (thermoelectric sheet to be tested); 3 - the base; 4 - the pressure sensor; 5 - the hydraulic regulator; 6 - the first temperature controller; 7 - the top plate; 8 - the thermal resistance plate; 9 - the bracket; 10 - the second temperature controller. Detailed Embodiment

[0077] The following combines the drawings and gives embodiments to describe the present invention in detail.

[0078] The present invention provides a device-level thermoelectric parameter test scheme based on electrical parameter identification. As Figure 1 shown, the basic idea of this scheme is: two same thermoelectric sheets to be tested are attached face to face so that the heat flow is in series. One of the thermoelectric sheets to be tested is denoted as the first thermoelectric sheet 1, and current is passed through it as a heat source; the other thermoelectric sheet to be tested is denoted as the second thermoelectric sheet 2. The second thermoelectric sheet 2 uses the thermoelectric power generation principle as a heat flow meter. The inner sides of the two thermoelectric sheets are the hot ends, and the outer sides are the cold ends. Temperature sensors are provided at both the hot and cold ends of the thermoelectric sheets, and temperature controllers are also provided at the cold ends of the two thermoelectric sheets to collect and control the cold end temperature. As Figure 1 shown, the first temperature controller 6 connected to the cold end of the first thermoelectric sheet 1 and the second temperature controller 10 connected to the cold end of the second thermoelectric sheet 2. Pass current I1 through the first thermoelectric sheet 1 as a heat source, and heat is generated at the hot end as a heat source to generate heat flow q , ignoring the small amount of heat loss on the side of the thermoelectric sheet, it can be assumed that all of it is transferred to the second thermoelectric sheet 2. The second thermoelectric sheet 2 acts as a power generation sheet to convert the heat flow into electrical energy. Through the measurement components, electrical parameters such as the open-circuit voltage U, open-circuit AC internal resistance R, and current I2 of the thermoelectric sheet under the current temperature conditions can be measured.

[0079] Based on the equivalent relationship between the two thermoelectric sheets, the Seebeck coefficient of the thermoelectric sheet to be tested can be determined by using the hot and cold end temperatures and electrical parameters of the two thermoelectric sheets. α 、Device internal resistance R and thermal conductivity K Especially the thermal conductivity, it is necessary to combine the heat flow expressions of the two thermoelectric sheets to determine the thermal conductivity K.

[0080] In order to achieve an equivalent state, the temperature T of the cold end of the first thermoelectric sheet 1 needs to be adjusted by the temperature controller of the cold end of the two thermoelectric sheets. c1 and the cold end temperature T of the second thermoelectric plate 2 c2 , and adjust the current I1 of the first thermoelectric sheet 1, thereby controlling the cold and hot end temperatures of the two thermoelectric sheets, such as Figure 2 As shown, the average temperature of the hot and cold ends of the two thermoelectric chips is T0 (where T0=(T h +T c ) / 2) are the same, that is, they are under equivalent temperature conditions. At this time, it can be considered that the two thermoelectric sheets have the same thermoelectric parameters at this temperature.

[0081] At the same time, due to the irreversibility of the thermoelectric conversion process, the two thermoelectric sheets cannot reach the same average temperature. It is also necessary to sandwich a thermal resistance plate 8 with a lower thermal conductivity and the same size as the thermoelectric sheet between the two thermoelectric sheets to provide a thermal resistance, thereby ensuring that the hot end temperature of the first thermoelectric sheet 1 through which current is passed is higher than the hot end temperature of the second thermoelectric sheet 2. Only by creating a temperature difference between the hot ends of the two thermoelectric sheets to be tested can the two thermoelectric sheets maintain the same average temperature T0 while the cold and hot end temperatures and current data of each thermoelectric sheet are different, thereby ensuring that the combined heat flow equations have solutions.

[0082] If the thermal resistance of the thermal resistance plate 8 is too large, after stabilization, the temperature difference of the thermoelectric sheet used for the heat flow meter will be too small and the current will become small, and the measurement and calculation errors will become larger; if the thermal resistance of the thermal resistance plate 8 is too small, after stabilization, the current values ​​of the two thermoelectric sheets will be close, which will also cause the calculation error to become larger. Therefore, preferably, the thermal conductivity of the thermal resistance plate is about 1-2W / (m*K), the thickness is about 1-2mm, and polytetrafluoroethylene or glass can be used to maintain T h1 and T h2 The temperature difference between them should be about 5-8℃.

[0083] Figure 3 FIG. 1 shows a structural diagram of a device-level thermoelectric parameter testing device based on electrical parameter identification in a preferred embodiment of the present invention. Figure 3As shown, the device includes a support assembly, a first temperature controller 6, a second temperature controller 10, a first thermoelectric element to be measured 1, a second thermoelectric element to be measured 2, a thermal resistance plate 8, a temperature sensor, a measurement assembly, a current source, and a calculation module. Among them, the temperature sensor, the measurement assembly, the current source, and the calculation module are not shown in the figure.

[0084] The first thermoelectric element to be measured 1 and the second thermoelectric element to be measured 2 select two thermoelectric elements of the same model. According to the hot and cold end markings given by the manufacturer, the hot end faces are opposite to each other, and a thermal resistance plate 8 of the same size is sandwiched in the middle. The two thermoelectric elements are coupled for heat transfer to form a series connection of heat flow. Among them, the inner sides of the two thermoelectric elements to be measured are the hot ends, and the outer sides are the cold ends. Temperature sensors are provided at both ends of the two thermoelectric elements. The first temperature controller 6 is connected to the cold end of the first thermoelectric element, and the second temperature controller 10 is connected to the cold end of the second thermoelectric element to control the temperature of the cold ends of the thermoelectric elements. The first temperature controller 6 and the second temperature controller 10 can simultaneously serve as the temperature sensors for the cold ends of the two thermoelectric elements, without the need to separately set cold end temperature sensors.

[0085] The thermal resistance plate 8 is arranged between the first thermoelectric element and the second thermoelectric element, so that there is a temperature difference between the hot ends of the two thermoelectric elements. The shape of the thermal resistance plate 8 needs to be consistent with the thermoelectric device, and a thermocouple temperature measurement point is integrated on its two bonding surfaces to measure the upper and lower surface temperatures T h1 and T h2 . Preferably, the side of the thermal resistance plate is coated with a heat insulation material to reduce heat loss, and the bonding surface with the thermoelectric element is also coated with thermal conductive silicone grease to enhance heat transfer.

[0086] The support assembly includes a top plate 7, a bracket 9, a base 3, and a hydraulic regulator 5. Preferably, it can also include a pressure sensor 4 to keep the pressure between the thermoelectric elements constant during the test and avoid the influence caused by stress changes. As shown in the figure, the base 3 and the top plate 7 are supported by brackets; the pressure sensor 4 is fixed on the upper side of the base 3 for real-time monitoring of the pressure during the test of the thermoelectric element; a temperature controller is fixed at the upper end of the pressure sensor 4; the hydraulic regulator 5 is fixed on the lower side of the top plate 7 for providing a downward pressure and cooperating with the pressure sensor 4 for pressure control; another temperature controller is fixed at the lower end of the hydraulic regulator 5; for the two relatively fitted thermoelectric elements, the first thermoelectric element is on the upper side, or the second thermoelectric element is on the upper side, and they are fixed between the base and the top plate. In this embodiment, the first thermoelectric element 1 is on the upper side, and the first temperature controller 6 is fixed on the lower side of the corresponding hydraulic regulator. Preferably, an alignment device can also be provided at the installation position of the thermoelectric element so that the thermoelectric element and the thermal resistance plate can be aligned in position.

[0087] The first temperature controller 6 and the second temperature controller 10 are used to control the cold-end temperatures of the two thermoelectric chips. The current source is used to control the current I1 passing through the first thermoelectric chip, making the first thermoelectric chip act as a heat source; the second thermoelectric chip acts as a heat flow meter using the thermoelectric power generation principle. By controlling the cold-end temperatures of the two thermoelectric chips and the current I1 passing through the first thermoelectric chip, the average temperature T0 of the two thermoelectric chips to be measured is made the same. At this time, under the equivalent temperature condition, the two thermoelectric chips have the same thermoelectric parameters under the current temperature condition T0.

[0088] The measurement component is used to measure the electrical parameters of the second thermoelectric chip 2 under the current temperature condition when the two thermoelectric chips are under the equivalent temperature condition, including the open-circuit voltage U, the device internal resistance R, and the current I2. The measurement component includes an open-circuit voltage measurement device, an internal resistance measurement device, and an electronic load. The voltage measurement device can use a battery tester to measure the open-circuit voltage U of the second thermoelectric chip; the internal resistance measurement device can use an AC internal resistance meter to measure the device internal resistance R of the second thermoelectric chip. The electronic load is used to connect to the second thermoelectric chip to form a circuit, and the electronic load can display the current I2 flowing through the second thermoelectric chip when the circuit is formed.

[0089] The calculation module is used to determine the thermoelectric parameters of the thermoelectric chips to be measured based on the equivalent relationship between the two thermoelectric chips, using the hot and cold-end temperatures and electrical parameters of the two thermoelectric chips.

[0090] In a preferred embodiment, to improve the accuracy, through the temperature adjustment of the first temperature controller and the second temperature controller, and through the current source to adjust the current I1 passing through the first thermoelectric chip, the temperature differences between the hot and cold ends of the first thermoelectric chip and the second thermoelectric chip are both kept at a small value, such as within 20 °C, so as to reduce the influence brought by the non-linear change of the thermoelectric parameters with the increase of temperature.

[0091] In a preferred embodiment, when performing a large-range temperature test, the heating / cooling units of the first temperature controller and the second temperature controller use a thermoelectric refrigeration temperature controller with water-cooled heat dissipation, which can specifically adopt the combination of a third thermoelectric chip + a water-cooled radiator. When the required temperature is low, the third thermoelectric chip provides a cold plate or a hot plate for the thermoelectric chips to be measured through a bidirectional current control module, and the water-cooled radiator is used to maintain the refrigeration performance when the third thermoelectric chip provides a cold plate. This implementation method can adjust the temperature faster compared with a simple liquid cooling plate, and can be adjusted in the range of -20 °C to 150 °C through a PID temperature control system, adapting to more working conditions.

[0092] When installing this device, adjust the hydraulic controller to lift the first temperature controller on the upper side, leave enough space, and place the test unit formed by the attached thermoelectric chip + resistor plate at the center position on the surface of the second temperature controller on the lower side. There are thermocouples at the positions where the upper and lower temperature controllers contact the test unit to monitor and adjust the temperature. The cold-end temperatures of the two thermoelectric chips are T respectivelyc1 and T c2 Adjust the base to keep it horizontal. Open the hydraulic controller and lower the first temperature controller on the upper side so that its surface presses on the upper surface of the unit under test, ensuring good thermal contact for all contact surfaces. Set a fixed pressure value such as 20 kg, and automatically maintain the pressure constant during the test according to the set pressure value.

[0093] Figure 4 The working process of the device-level thermoelectric parameter test device based on electrical parameter identification of the present invention is shown, and it includes the following steps:

[0094] Step 1: Turn on the first temperature controller and keep the room temperature; use the first thermoelectric sheet as the heat source and the second thermoelectric sheet as the heat flow meter; the current source passes an initial current I into the first thermoelectric sheet, and the second thermoelectric sheet remains open.

[0095] In this step, first turn on the water circulation of the first temperature controller, but the refrigeration sheet in the first temperature controller is not energized first to keep the room temperature. An initial current I is passed into the first thermoelectric sheet as the heat source, and the second thermoelectric sheet as the heat flow meter remains open.

[0096] Step 2: Turn on the first temperature controller and the second temperature controller, and adjust the temperatures of the two temperature controllers and the current I1 passed into the first thermoelectric sheet so that the average temperature of the two thermoelectric sheets rises to the measurement temperature condition T0.

[0097] In this step, referring to Figure 2 the temperature gradient diagram shown, taking the example of testing the thermoelectric parameters of the thermoelectric sheet at 50 °C, turn on the two temperature controllers, adjust the input current I1 of the first thermoelectric sheet and the temperature of the temperature controller to raise the average temperature of the hot and cold ends of the first thermoelectric sheet to 50 °C. According to the difference ΔT between T h1 and T h2 , adjust the cold-end temperature of the temperature controller and the current I1 to satisfy T c2 = T c1 + ΔT. At this time, the average temperature of the second thermoelectric sheet as the heat flow meter is also 50 °C, but the temperature difference is 2ΔT smaller than the former.

[0098] Step 3: Use the measurement component to measure the electrical parameters of the second thermoelectric sheet under the current temperature condition, obtain the device internal resistance R and calculate the Seebeck coefficient α.

[0099] In this step, a battery tester and an AC internal resistance meter are used to measure the open-circuit voltage U and the device internal resistance R of the first thermoelectric sheet in the short-circuit state as the heat flow meter. Since the battery tester and the AC internal resistance meter do not generate direct current, the influence brought by the Peltier effect when the thermoelectric sheet forms a circuit does not need to be considered. According to the test results and temperature data, the calculation module calculates the device-level physical property parameter Seebeck coefficient , and the formula is:

[0100] (1)

[0101] Step 4: Connect the electronic load to pass the second thermoelectric chip, readjust the temperature to be consistent with step 2, and measure the current I2 of the second thermoelectric chip.

[0102] In this step, the electronic load is connected in series with the thermoelectric chip of the heat flux meter to form a path. The load resistance should not be too large to prevent the current value from being too small and amplifying the error. At the same time, the temperature controller is adjusted so that the two thermoelectric chips continue to maintain an average temperature of T0=50℃, and the current I2 at this time is measured.

[0103] Step 5: According to the device internal resistance R of the thermoelectric chip, the Seebeck coefficient α, and the currents I1 and I2 of the two thermoelectric chips, based on the equivalent relationship between the two thermoelectric chips, determine the thermal conductivity K of the thermoelectric chip to be tested.

[0104] In this step, according to the previously calculated Seebeck coefficient α and device internal resistance R under the current temperature condition T0, the device thermal conductivity can be solved according to the steady-state equation when the thermoelectric sheet is in the power generation or cooling state, and then the thermal conductivity K of the particle can be calculated. The calculation process is:

[0105] For the heat flow at the hot end of the first thermoelectric element as a heat source:

[0106] (2)

[0107] For the heat flow at the hot end of the second thermoelectric chip as a heat flow meter:

[0108] (3)

[0109] By adjusting the temperature controller and the current I1 input, the average temperature T0 of the two thermoelectric sheets is equal. When the nonlinear change of temperature with the height direction of the thermoelectric arm is ignored, they are equivalent to having the same physical parameters such as α, R and K. Therefore, the steady-state equation of the heat transfer at the hot end of the two thermoelectric sheets can be jointly established, and then the known temperature and current parameters are substituted to solve the thermal conductivity K.

[0110] Therefore, neglecting heat losses, we have ,Right now

[0111] (4)

[0112] Since the other parameters in the equation are known, the total thermal conductivity K of the thermoelectric chip can be solved.

[0113] Step 6: Adjust the average temperature to different measurement points, repeat steps 1 to 5, and obtain the Seebeck coefficient, device internal resistance, and total thermal conductivity of the thermoelectric chip under different temperature conditions; use the least squares method to fit the curves of the three thermoelectric parameters changing with temperature.

[0114] Preferably, the roles of the two thermoelectric chips to be measured can be exchanged, or the thermoelectric chips of the same model can be replaced, and the same method can be used for testing. Since the device adopts an up-and-down symmetrical structure, directly changing the position of the current-carrying sheet is sufficient without reinstallation. After the roles are exchanged, a series of obtained parameters can be substituted into the least squares method to fit the change curve, so as to finally obtain the device-level physical property parameters that can be used for accurate calculation.

[0115] Step 7: Test the maximum thermoelectric conversion efficiency of the thermoelectric chip under a certain working condition:

[0116] Testing the maximum thermoelectric conversion efficiency requires measuring the heat flux passing through the thermoelectric chip and the maximum power generation. The heat flux test is based on the previously measured device-level thermoelectric parameters, and the heat flux is calculated by identifying the electrical parameters, so as to calculate the thermoelectric conversion efficiency.

[0117] Specifically: Refer to Figure 5 , raise the temperature of the first temperature controller as the heat source. There are still two thermoelectric chips in the middle. The upper first thermoelectric chip is used as a heat flux meter, and the lower second thermoelectric chip is used as the thermoelectric chip for measuring the thermoelectric conversion efficiency to be measured. Adjust the hot-end temperature T h1 of the first thermoelectric chip through the first temperature controller. Use the second temperature controller to adjust the cold-end temperature of the second thermoelectric chip so that the temperatures at both ends of the thermoelectric chip to be measured can reach the required values at the hot and cold ends under the current test working condition. For example, when measuring how much electricity the thermoelectric chip can generate and the conversion efficiency at a heat source temperature of 150 degrees and a cold source temperature of 20 degrees, the temperatures at both ends of the thermoelectric chip to be measured need to reach the corresponding temperature values.

[0118] If a higher temperature is required, the first temperature controller can be replaced with a conventional electric heating temperature controller, and the second temperature controller can be replaced with a pure liquid cooling temperature controller to maintain the temperature difference of the thermoelectric chip to be measured.

[0119] Keep the cold and hot-end temperatures of the second thermoelectric chip unchanged. Connect the second thermoelectric chip to an electronic load, adjust the resistance of the electronic load so that the output efficiency is at the maximum value, and read out the electric power W1 at this time. Measure the cold and hot-end temperatures T c1 and T h1 , and the input current I1.

[0120] According to the previously measured device-level physical property parameters, interpolate to obtain the physical property parameters at the cold and hot-end temperatures at this time, and use formula (2) to calculate the heat flux Qh 1 at the hot end input to the thermoelectric chip to be measured. Then the maximum thermoelectric conversion efficiency is (W1 / Q h1 ) 100%.

[0121] Step 8: Test the cooling capacity and cooling efficiency of the thermoelectric refrigeration device under a certain working condition.

[0122] Refer to Figure 6 , the device is arranged in the same way as the thermoelectric power generator device for testing. At this time, the first thermoelectric sheet is used as a cooling sheet and a current consistent with the test working condition is passed through it, and the second thermoelectric sheet is used as a heat flow meter and a certain current I3 is passed through it. That is, at this time, the second thermoelectric sheet serves as a heat flow meter and provides the heat load of the first thermoelectric sheet Q h3 , at this time, there is a cooling capacity Q c = Q h3 . The hot end and cold end temperatures of the cooling sheet are maintained by the first temperature controller and the second thermoelectric sheet respectively, so that they are consistent with the test working condition. The test working condition here refers to the cooling capacity and cooling efficiency of the cooling sheet to be measured under a certain current input or working temperature.

[0123] Since usually the hot end temperature of the cooling sheet is not high, the first temperature controller can still use a thermoelectric temperature controller, while the second temperature controller needs to provide heat dissipation for dissipating the heat of the hot end of the thermoelectric sheet of the heat flow meter.

[0124] Measure the hot end temperature T h3 of the second thermoelectric sheet, the cold end temperature T c3 and the input current I3, and use the following formula (5) to calculate the cooling capacity of the device to be tested Q c :

[0125] (5)

[0126] Calculate the cooling efficiency according to the electric power input value W2. The cooling efficiency COP = ( Q c / W2) × 100%.

[0127] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in this description can be different and are not limited. Therefore, those skilled in the art of the present invention can modify or equivalently replace the technical solutions recorded in the foregoing embodiments; and these modifications and replacements do not depart from the gist and technical solutions of the present invention, and shall all fall within the protection scope of the present invention.

Claims

1. A device-level thermoelectric parameter testing device based on electrical parameter identification, characterized in that: include: A first temperature controller, a second temperature controller, two identical thermoelectric sheets to be tested, a thermal resistance plate, a temperature sensor, a measuring component, a current source and a computing module; Two identical thermoelectric sheets to be tested include a first thermoelectric sheet and a second thermoelectric sheet, which are face-to-face and relatively attached so as to be connected in series with heat flow; the inner sides of the two thermoelectric sheets to be tested are hot ends, and the outer sides are cold ends; the hot ends of the two thermoelectric sheets are provided with temperature sensors, wherein a first temperature controller is connected to the cold end of the first thermoelectric sheet, and a second temperature controller is connected to the cold end of the second thermoelectric sheet to control the temperature of the cold ends of the thermoelectric sheets; a thermal resistance plate is arranged between the first thermoelectric sheet and the second thermoelectric sheet, so that there is a temperature difference between the hot ends of the two thermoelectric sheets; The first thermoelectric sheet is supplied with a current I1 provided by a current source as a heat source, and the second thermoelectric sheet is used as a heat flow meter using the thermoelectric power generation principle; By controlling the cold end temperature of the two thermoelectric sheets and the current I1 of the first thermoelectric sheet, the average temperature T0 of the hot and cold ends of the two thermoelectric sheets to be tested is made the same. At this time, they are in an equivalent temperature condition, and the two thermoelectric sheets have the same thermoelectric parameters under the current temperature condition T0. A measuring component, used for measuring the electrical parameters of the second thermoelectric sheet under the current temperature condition when the two thermoelectric sheets are under the equivalent temperature condition, including the open circuit voltage U, the device internal resistance R and the current I2; A calculation module is used to determine the thermoelectric parameters of the thermoelectric sheet to be tested, including the Seebeck coefficient α, the device internal resistance R and the thermal conductivity K, based on the equivalent relationship between the two thermoelectric sheets and using the cold and hot end temperatures and electrical parameters of the two thermoelectric sheets; The testing process using the device-level thermoelectric parameter testing device includes: Step 1: Turn on the first temperature controller and maintain room temperature; use the first thermoelectric chip as a heat source and the second thermoelectric chip as a heat flow meter; the current source passes an initial current to the first thermoelectric chip and the second thermoelectric chip remains open circuit; Step 2: Turn on the first temperature controller and the second temperature controller, adjust the temperatures of the two temperature controllers and the current I1 of the first thermoelectric sheet, so that the average temperatures of the hot and cold ends of the two thermoelectric sheets are both raised to the measurement temperature condition T0; Step 3: Use the measuring component to measure the electrical parameters of the second thermoelectric chip under the current temperature conditions, obtain the device internal resistance R and calculate the Seebeck coefficient α; Step 4: Connect the electronic load to make the second thermoelectric sheet pass, readjust the temperature to be consistent with step 2, and measure the current I2 of the second thermoelectric sheet; Step 5: According to the device internal resistance R of the thermoelectric chip, the Seebeck coefficient α, and the currents I1 and I2 of the two thermoelectric chips, based on the equivalent relationship between the two thermoelectric chips, determine the thermal conductivity K of the thermoelectric chip to be tested.

2. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: The thermal resistance plate has the same size as the thermoelectric sheet. By selecting the thermal conductivity of the thermal resistance plate, the temperature difference between the hot ends of the two thermoelectric sheets is 5° C. to 8° C.

3. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: The first temperature controller and the second temperature controller adopt a combination of a third thermoelectric plate and a water-cooled radiator; the third thermoelectric plate provides a cold plate or a hot plate for the thermoelectric plate to be tested through bidirectional current control, and the water-cooled radiator is used to maintain the cooling performance when the third thermoelectric plate provides a cold plate.

4. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: The measuring assembly includes an open circuit voltage measuring device, an internal resistance measuring device, and an electronic load; The calculation module includes a Seebeck coefficient α calculation module, an internal resistance R determination module, and a thermal conductivity K calculation module; The Seebeck coefficient α calculation module is used to obtain the hot end temperature of the second thermoelectric sheet. and cold junction temperature , combined with the open circuit voltage U of the second thermoelectric element measured by the open circuit voltage measuring device, the Seebeck coefficient α is calculated using formula (1): （1） The internal resistance R determination module is used to obtain the device internal resistance R of the second thermoelectric chip from the internal resistance measurement device; The thermal conductivity K calculation module is used to obtain the hot end temperature of the second thermoelectric sheet after the electronic load is connected in series with the second thermoelectric sheet as a heat flow meter to form a path and the average temperature T0 of the two thermoelectric sheets is readjusted to remain unchanged. and cold junction temperature , and the hot end temperature of the first thermoelectric chip and cold junction temperature ; Obtain the current I2 at this time from the electronic load; The heat flux at the hot end of the first thermoelectric chip as a heat source Q h1 : （2） The heat flow at the hot end of the second thermoelectric chip as a heat flow meter Q h2 : （3） Ignoring heat loss, we have Q h1 = Q h2 ,Right now （4） The total thermal conductivity K of the device corresponding to the current temperature condition T0 can be obtained by solving the above formula (4).

5. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: By adjusting the temperature of the first temperature controller and the second temperature controller and adjusting the current I1 flowing into the first thermoelectric sheet by the current source, the temperature difference between the cold and hot ends of the first thermoelectric sheet and the second thermoelectric sheet is less than 20°C.

6. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: The device further includes: a base, a bracket, a pressure sensor, a hydraulic regulator, and a top plate; The base and the top plate are supported by a bracket; a pressure sensor is fixed on the upper side of the base to monitor the pressure of the thermoelectric sheet to be tested in real time; a temperature controller is fixed on the upper end of the pressure sensor; a hydraulic regulator is fixed on the lower side of the top plate to provide downward pressure and cooperate with the pressure sensor to control the pressure; another temperature controller is fixed on the lower end of the hydraulic regulator; two relatively fitted thermoelectric sheets, with the first thermoelectric sheet on top, or the second thermoelectric sheet on top, are fixed between the base and the top plate.

7. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: The shape of the thermal resistance plate is consistent with that of the thermoelectric sheet, and temperature sensors are installed on both sides of the thermal resistance plate to measure the hot end temperature T of the first thermoelectric sheet connected to the upper surface. h1 and the hot end temperature of the second thermoelectric chip T h2 ; The side of the thermal resistance plate is coated with insulation material, and the bonding surface with the thermoelectric sheet is coated with thermal conductive silicone grease.

8. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: In the test process, the Seebeck coefficient α is calculated in step 3 as: Get the hot end temperature of the second thermoelectric chip from the sensor and cold junction temperature , combined with the open circuit voltage U of the second thermoelectric element measured by the open circuit voltage measuring device, the Seebeck coefficient α is calculated using formula (1): （1） In step 5, the thermal conductivity K of the thermoelectric sheet to be tested is determined as: Get the hot end temperature of the second thermoelectric chip and cold junction temperature , and the hot end temperature of the first thermoelectric chip and cold junction temperature ; Keep the average temperature T0 of the two thermoelectric chips unchanged, and obtain the current I2 at this time from the load resistor; Heat flow of the first thermoelectric sheet as a heat source Q h1 : （2） The heat flow of the second thermoelectric sheet as a heat flow meter Q h2 : （3） Ignoring heat loss, we have ,Right now （4） The thermal conductivity K of the thermoelectric sheet corresponding to the current temperature condition T0 is solved by the above formula (4).

9. The device-level thermoelectric parameter testing device based on electrical parameter identification according to claim 1, characterized in that: The testing process further includes: Step 6: Adjust the average temperature to different measurement points to obtain the Seebeck coefficient, device internal resistance, and total thermal conductivity of the thermoelectric chip under different temperature conditions; use the least squares method to fit the curves of the three thermoelectric parameters changing with temperature; Step 7: Test the maximum conversion efficiency of the thermoelectric sheet under a working state: remove the thermal resistance plate, use the first temperature controller as the heat source, the first thermoelectric sheet as the heat flux meter, and the second thermoelectric sheet as the thermoelectric sheet to be tested for thermoelectric conversion efficiency; adjust the hot end temperature T of the first thermoelectric sheet by the first temperature controller h1 , using the second temperature controller to adjust the cold end temperature of the second thermoelectric sheet so that the temperatures at both ends of the second thermoelectric sheet can reach the required temperature values ​​of the hot and cold ends under the current test working state; Keep the cold and hot end temperatures of the second thermoelectric sheet unchanged, connect the second thermoelectric sheet to the electronic load, adjust the resistance of the electronic load to make the output efficiency at the maximum value, and read the electric power W1 at this time; measure the cold end temperature T of the first thermoelectric sheet c1 and hot end temperature T h1 , and input current I1; According to the device-level thermoelectric parameter versus temperature curve measured in step 6, the thermoelectric parameters at the cold and hot end temperatures are interpolated, and the heat flux input to the hot end of the second thermoelectric element is calculated using formula (2). Q h1 , then the maximum thermoelectric conversion efficiency is (W1 / Q h1 ) 100%; Step 8: Test the cooling capacity and cooling efficiency of the thermoelectric element in a working state: Current is passed through the first thermoelectric sheet and the second thermoelectric sheet, wherein the first thermoelectric sheet serves as the cooling sheet to be tested, and the second thermoelectric sheet serves as a heat flux meter and provides heat load for the first thermoelectric sheet. Q h3 , at this time there is cooling capacity Q c = Q h3 The first temperature controller and the second thermoelectric sheet respectively keep the hot end and cold end temperatures of the first thermoelectric sheet consistent with the temperature under the test working state; measure the hot end temperature T of the second thermoelectric sheet h3 , cold end temperature T c3 and input current I3, then we have Q c = Q h3 , use the following formula (5) to calculate the cooling capacity of the first thermoelectric chip Q c ; （5） The cooling efficiency is calculated based on the electric power input value W2 displayed by the electronic load. The cooling efficiency COP = ( Q c / W2) 100%.

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