Device-level thermoelectric parameter testing device and method based on electrical parameter identification

Abstract

The invention provides a device-level thermoelectric parameter testing device and method based on electrical parameter identification, and belongs to the technical field of thermoelectric device testing. The hot ends of the same first thermoelectric sheet and second thermoelectric sheet are opposite, and a thermal resistance plate is clamped between the two thermoelectric sheets, so that a temperature difference exists between the hot ends of the two thermoelectric sheets; the first temperature controller is connected with the cold end of the first thermoelectric sheet, and the second temperature controller is connected with the cold end of the second thermoelectric sheet to control the temperature of the cold end of the thermoelectric sheet; the first thermoelectric sheet is electrified with current I1 as a heat source, and the second thermoelectric sheet uses a thermoelectric power generation principle as a heat flow meter; by controlling the cold end temperatures of the two thermoelectric pieces and the input current I1 of the first thermoelectric piece, the average temperatures of the two thermoelectric pieces to be measured are the same, namely, the two thermoelectric pieces to be measured are in an equivalent temperature condition and have the same thermoelectric parameters; and based on the equivalent relationship of the two thermoelectric sheets, determining the thermoelectric parameters of the thermoelectric sheet to be tested by using the cold and hot end temperatures and the electrical parameters of the two thermoelectric sheets. The performance of the thermoelectric device can be accurately evaluated by using the method.

Description

Technical Field

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

[0002] Thermoelectric devices are increasingly used in energy recovery, electronic cooling and temperature control. With the development of efficient thermoelectric materials and the advancement of manufacturing technology, the application potential of thermoelectric technology in new energy, aerospace and smart wearable devices is constantly 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 thermoelectric refrigeration systems, low thermal conductivity and high Seebeck coefficient can maximize the cooling effect, while the device internal resistance needs to find a balance between good electrical conductivity and low thermal conductivity to ensure efficient operation of the system. Accurately extracting these physical parameters can quantify the energy efficiency of thermoelectric power generation and refrigeration systems and promote the widespread application of thermoelectric technology in various fields.

[0004] In actual applications, although the physical parameters of thermoelectric materials can be measured when producing devices, due to differences in the inherent properties of the materials, structural design and manufacturing processes, there are significant differences between the physical parameters of the devices and the physical parameters of the materials.

[0005] Device-level thermoelectric parameters refer to the physical parameters that are simplified to the Seebeck coefficient of the entire device, ignoring the specific values ​​of the device interface contact thermal resistance and resistance. α Total internal resistance R and total thermal conductivity K , these parameters usually change with temperature. Device-level physical parameters reflect comprehensive performance and are affected by more external factors. Manufacturers' tests on device-level parameters are not standardized and unified. When applying thermoelectric devices, their parameters need to be accurately evaluated in order to make more accurate calculations.

[0006] There are many methods and devices for accurately testing the physical parameters of thermoelectric devices. The Seebeck coefficient and device internal resistance are usually easy to measure. However, since thermal conductivity needs to be calculated by measuring heat flow, traditional thermal resistance heat flow meters often have large errors, long test processes, and require a vacuum environment. Especially in the low temperature range below 150°C, the reduced heat flow makes the temperature difference less obvious, and the thermal conductivity measurement accuracy is lower.

[0007] In order 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 fast device-level physical property parameter testing method that can be applicable to thermoelectric devices of most sizes. Summary of the invention

[0008] In view of this, the present invention provides a device-level thermoelectric parameter testing method and apparatus based on electrical parameter identification, which can accurately calculate and reduce heat loss when the heat flux is small, thus avoiding the shortcomings of traditional thermoelectric testing devices that rely on precise processing of heat conductive blocks and vacuum environment.

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

[0010] A device-level thermoelectric parameter test device based on electrical parameter identification, comprising: 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 calculation 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; 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 end of the thermoelectric sheet; the 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 element is supplied with a current I provided by a current source. 1 As a heat source, the second thermoelectric sheet uses the principle of thermoelectric power generation as a heat flux meter; By controlling the cold end temperature of the two thermoelectric sheets and the current I 1 , so that the average temperature of the hot and cold ends of the two thermoelectric chips to be tested is T 0 The same, at this time in the equivalent temperature conditions, the two thermoelectric sheets at the current temperature conditions T 0 The same thermoelectric parameters are obtained under The measuring component is used to measure the electrical parameters of the second thermoelectric chip under the current temperature conditions when the two thermoelectric chips are under equivalent temperature conditions, including the open circuit voltage U, the device internal resistance R and the current I 2 ; The calculation module is used to determine the thermoelectric parameters of the thermoelectric sheet to be tested 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.

[0011] Preferably, the thermal resistance plate and the thermoelectric sheet have the same size, and the temperature difference between the hot ends of the two thermoelectric sheets is 5° C. to 8° C. by selecting the thermal conductivity of the thermal resistance plate.

[0012] Preferably, the first temperature controller and the second temperature controller adopt a combination of a third thermoelectric sheet and a water-cooled radiator; the third thermoelectric sheet provides a cold plate or a hot plate for the thermoelectric sheet to be tested through bidirectional current control, and the water-cooled radiator is used to maintain the cooling performance when the third thermoelectric sheet provides a cold plate.

[0013] Preferably, the measuring component 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 form a path after the electronic load is connected in series with the second thermoelectric sheet as a heat flow meter and the average temperature T of the two thermoelectric sheets is readjusted. 0 Unchanged, get the hot end temperature of the second thermoelectric sheet and cold junction temperature , and the hot end temperature of the first thermoelectric chip and cold junction temperature ; Obtain the current I at this time from the electronic load 2 ; 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 current temperature condition T can be obtained by solving the above formula (4). 0 The total thermal conductivity K of the device at the corresponding temperature.

[0014] Preferably, the temperature is adjusted by the first temperature controller and the second temperature controller, and the current I flowing into the first thermoelectric chip is adjusted by the current source. 1 , so that the temperature difference between the hot and cold ends of the first thermoelectric sheet and the second thermoelectric sheet is less than 20°C.

[0015] Preferably, the device further comprises: 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.

[0016] Preferably, 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.

[0017] The present invention also provides a device-level thermoelectric parameter testing method based on electrical parameter identification, using the above-mentioned device-level thermoelectric parameter testing device, the method comprises the following steps: 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, and adjust the temperature of the two temperature controllers and the current I of the first thermoelectric chip. 1 , so that the average temperature of the hot and cold ends of the two thermoelectric sheets rises to the measurement temperature condition T 0 ; 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 I of the second thermoelectric sheet 2 ; Step 5: Based on the device internal resistance R of the thermoelectric chip, the Seebeck coefficient α and the current I of the two thermoelectric chips 1 and I 2 , based on the equivalent relationship between the two thermoelectric sheets, determine the thermal conductivity K of the thermoelectric sheet to be tested.

[0018] Preferably, the Seebeck coefficient α calculated in step 3 is: 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 ; Maintain the average temperature T of the two thermoelectric chips 0 The current I at this time is obtained from the load resistance 2 ; 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 current temperature condition T can be obtained by solving the above formula (4). 0 The corresponding thermal conductivity K of the thermoelectric sheet is shown below.

[0019] Preferably, the method further comprises: 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 W at this time. 1 ; Measure the cold end temperature T of the first thermoelectric chip c1 and hot end temperature T h1 , and the input current I 1 ; 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 (W 1 / 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 I 3 , at this time there is Q c = Q h3 , the cooling capacity Q of the first thermoelectric chip can be calculated using the following formula (5): c ; (5) According to the electric power input value W displayed by the electronic load 2 Calculate the refrigeration efficiency, refrigeration efficiency COP = ( Q c / W 2 ) 100%.

[0020] Beneficial effects: (1) Traditional thermal resistance heat flux meters rely on the equivalent one-dimensional heat transfer of the heat conductive block and perform multi-point temperature measurement. When the heat flux is small, the difference between the temperatures of each point is small, and the calculation error is difficult to control. Other heat flux meters based on the Seebeck effect or thin film heat flux meters need to be calibrated and processed into suitable shapes according to actual needs. The heat flux calculation method adopted by the present invention can directly use the uncalibrated thermoelectric chip to be tested, and does not rely entirely on temperature measurement, but uses current parameters for calculation, which greatly improves the convenience and accuracy of measuring the physical parameters of thermoelectric devices.

[0021] The present invention can accurately and quickly test the open circuit voltage, internal resistance and heat flow of thermoelectric devices at different temperatures in a low temperature range below 150°C, thereby calculating parameters such as its Seebeck coefficient and thermal conductivity, avoiding the shortcomings of traditional thermoelectric testing devices that rely on precise processing of heat-conducting blocks and a vacuum environment.

[0022] (2) The present invention uses a thermal resistance plate for isolation when testing thermoelectric parameters. A temperature difference is generated between the hot ends of two thermoelectric devices by heat flow. The two devices are then placed under equivalent temperature conditions through cold end temperature control and different electrical parameters are identified, thereby reducing test errors.

[0023] (3) The present invention is based on the hot end temperature T of the thermoelectric device h , cold end temperature T c , current I 1 The relationship between the three regulates the average temperature T of the thermoelectric device. 0 By changing the temperature, the method can test the curve of the thermoelectric parameters changing with temperature.

[0024] (4) The present invention uses a device that couples thermoelectric cooling and a liquid cooling plate as a temperature controller, and the temperature value of 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 wide range of temperature changes can be provided.

[0025] (5) The test method adopted by the present invention is relatively simple and accurate. Since one of the thermoelectric sheets to be tested is used to calculate the heat flux, and the thermal resistance plate has insulation measures, the convection and radiation heat losses itself are very small. There is no need for insulation in a vacuum environment and no need to process a heat conductive block, which reduces the processing cost.

[0026] (6) The present invention provides a device-level thermoelectric parameter testing scheme that can be closer to the working state of the thermoelectric element. Compared with the scheme using a vacuum environment test, this scheme can better reflect the thermoelectric conversion efficiency or heat flow and other data under the actual working state of the thermoelectric device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The schematic diagram of the device-level thermoelectric parameter testing scheme based on electrical parameter identification of the present invention; Figure 2 It is the temperature gradient diagram of the test process of the present invention; Figure 3 It is a structural diagram of a device-level thermoelectric parameter testing device based on electrical parameter identification of the present invention; Figure 4 It is a flow chart of the device-level thermoelectric parameter testing method based on electrical parameter identification of the present invention; Figure 5 Schematic diagram for maximum thermoelectric conversion efficiency testing; Figure 6 Schematic diagram for testing cooling capacity and cooling efficiency; Among them, 1-the first thermoelectric chip (the thermoelectric chip to be tested); 2-the second thermoelectric chip (the thermoelectric chip 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 DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0029] The present invention provides a device-level thermoelectric parameter testing solution for electrical parameter identification, such as Figure 1 As shown, the basic idea of ​​this scheme is to fit two identical thermoelectric sheets to be tested face to face so as to connect the heat flow 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, and the second thermoelectric sheet 2 uses the thermoelectric power generation principle as a heat flow meter. The inside of the two thermoelectric sheets is the hot end, and the outside is the cold end. Temperature sensors are provided at the hot end and the cold end 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 shown in FIG. Figure 1 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 are shown. The first thermoelectric sheet 1 as a heat source is supplied with a current I 1 , the hot end generates heat 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, which acts as a power generation sheet to convert the heat flow into electrical energy. The open circuit voltage U, open circuit AC internal resistance R and current I of the thermoelectric sheet under the current temperature conditions can be measured by the measuring component. 2 Isoelectric parameters.

[0030] 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.

[0031] 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 I of the first thermoelectric plate 1 1 The size of the two thermoelectric chips can then be controlled to control the temperature of the cold and hot ends. Figure 2 As shown, the average temperature of the hot and cold ends of the two thermoelectric chips is T 0 (Where T 0 =(Th +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.

[0032] 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 lower thermal conductivity and the same size as the thermoelectric sheet between the two thermoelectric sheets to provide a thermal resistance, so as to ensure that the temperature of the hot end of the first thermoelectric sheet 1 through which current is passed is higher than the temperature of the hot end of the second thermoelectric sheet 2. Only by making 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 T 0 At the same time, the cold and hot end temperatures and current data of each thermoelectric chip are different, so that the combined heat flow equations can be solved.

[0033] 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℃.

[0034] 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 3 As shown, the device includes a support component, a first temperature controller 6, a second temperature controller 10, a first thermoelectric sheet to be tested 1, a second thermoelectric sheet to be tested 2, a thermal resistance plate 8, a temperature sensor, a measuring component, a current source and a calculation module. Among them, the temperature sensor, the measuring component, the current source and the calculation module are not shown in the figure.

[0035] The first thermoelectric sheet 1 to be tested and the second thermoelectric sheet 2 to be tested select two thermoelectric sheets of the same model, and place the hot end faces opposite to each other according to the hot and cold end markings given by the manufacturer, with a thermal resistance plate 8 of the same size sandwiched in between. The two thermoelectric sheets are coupled to transfer heat to form a heat flow series. Among them, the inner sides of the two thermoelectric sheets to be tested are the hot ends, and the outer sides are the cold ends. Temperature sensors are provided at both ends of the two thermoelectric sheets. The first temperature controller 6 is connected to the cold end of the first thermoelectric sheet, and the second temperature controller 10 is connected to the cold end of the second thermoelectric sheet to control the temperature of the cold end of the thermoelectric sheets. The first temperature controller 6 and the second temperature controller 10 can simultaneously serve as temperature sensors for the cold ends of the two thermoelectric sheets, without the need to set up cold end temperature sensors separately.

[0036] The thermal resistance plate 8 is arranged between the first thermoelectric plate and the second thermoelectric plate, so that there is a temperature difference between the hot ends of the two thermoelectric plates. The shape of the thermal resistance plate 8 needs to be consistent with the thermoelectric device, and a thermocouple temperature measuring 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 insulating material to reduce heat loss, and the surface in contact with the thermoelectric sheet is also coated with thermal conductive silicone grease to enhance heat transfer.

[0037] The support assembly includes a top plate 7, a bracket 9, a base 3, a hydraulic regulator 5, and preferably a pressure sensor 4 to keep the pressure between the thermoelectric sheets unchanged during the test to avoid the influence caused by stress changes. As shown in the figure, the base 3 and the top plate 7 are supported by a bracket; the pressure sensor 4 is fixed on the upper side of the base 3 to monitor the pressure during the test of the thermoelectric sheet in real time; a temperature controller is fixed on the upper end of the pressure sensor 4; the hydraulic regulator 5 is fixed on the lower side of the top plate 7 to provide downward pressure and cooperate with the pressure sensor 4 to control the pressure; another temperature controller is fixed on the lower end of the hydraulic regulator 5; two relatively fitted thermoelectric sheets, the first thermoelectric sheet on the top, or the second thermoelectric sheet on the top, are fixed between the base and the top plate. In this embodiment, the first thermoelectric sheet 1 is on the top, and the first temperature controller 6 is fixed on the lower side of the corresponding hydraulic regulator. Preferably, an alignment device can also be set at the installation position of the thermoelectric sheet so that the thermoelectric sheet and the thermal resistance plate can be aligned in position.

[0038] The first temperature controller 6 and the second temperature controller 10 are used to control the cold end temperature of the two thermoelectric sheets. The current source is used to control the current I 1 , so that the first thermoelectric sheet is used as a heat source; the second thermoelectric sheet uses the thermoelectric power generation principle as a heat flux meter. By controlling the cold end temperature of the two thermoelectric sheets and the current I 1 , so that the average temperature of the two thermoelectric chips to be tested is T 0 The same, at this time in the equivalent temperature conditions, the two thermoelectric sheets at the current temperature conditions T 0 have the same thermoelectric parameters.

[0039] The measuring component is used to measure the electrical parameters of the second thermoelectric sheet 2 under the current temperature conditions when the two thermoelectric sheets are under equivalent temperature conditions, including the open circuit voltage U, the device internal resistance R and the current I 2 The measuring components include an open circuit voltage measuring device, an internal resistance measuring device and an electronic load. The voltage measuring device may be a battery tester, which is used to measure the open circuit voltage U of the second thermoelectric sheet; the internal resistance measuring device may be an AC internal resistance meter, which is used to measure the device internal resistance R of the second thermoelectric sheet. The electronic load is used to connect to the second thermoelectric sheet to form a path, and the electronic load can display the current I flowing through the second thermoelectric sheet when the path is in place. 2 .

[0040] The calculation module is used to determine the thermoelectric parameters of the thermoelectric sheet to be tested 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.

[0041] In a preferred embodiment, in order to improve the accuracy, the temperature of the first temperature controller and the second temperature controller is adjusted, and the current I flowing into the first thermoelectric chip is adjusted by the current source. 1 , so that the temperature difference between the hot and cold ends of the first thermoelectric sheet and the second thermoelectric sheet is kept small, for example, within 20°C, which can reduce the impact of nonlinear changes in thermoelectric parameters as temperature increases.

[0042] In a preferred embodiment, when conducting a wide range of temperature tests, 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 use a combination of a third thermoelectric plate + a water-cooled radiator. When the required temperature is low, the third thermoelectric plate provides a cold plate or a hot plate for the thermoelectric plate to be tested through a bidirectional current control module, and the water-cooled radiator is used to maintain the cooling performance of the third thermoelectric plate when providing a cold plate. This implementation method can adjust the temperature faster than a simple liquid cooling plate, and can be adjusted within the range of -20°C to 150°C through a PID temperature control system to adapt to more working conditions.

[0043] When installing the device, adjust the hydraulic controller to lift the first temperature controller on the upper side, leaving enough space, and place the test unit formed by the attached thermoelectric sheet + resistor plate at the center of the surface of the second temperature controller on the lower side. The positions where the upper and lower temperature controllers contact the test unit are equipped with thermocouples for monitoring and adjusting the temperature. The cold end temperatures of the two thermoelectric sheets are T c1 and T c2 , adjust the base to keep it horizontal. Turn on the hydraulic controller and lower the first temperature controller on the upper side, so that its surface is pressed on the upper surface of the unit to be tested, ensuring that all contact surfaces have good thermal contact. Set a fixed pressure value such as 20kg, and automatically keep the pressure unchanged during the test according to the set pressure value.

[0044] Figure 4 The working process of the device-level thermoelectric parameter testing device based on electrical parameter identification of the present invention is shown, which includes the following steps: 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 flux meter; the current source passes an initial current I into the first thermoelectric chip and the second thermoelectric chip remains open circuit.

[0045] In this step, the water circulation of the first temperature controller is turned on first, but the refrigeration chip in the first temperature controller is not powered on first to maintain room temperature. The first thermoelectric chip as a heat source is fed with an initial current I, and the second thermoelectric chip as a heat flow meter is kept open.

[0046] Step 2: Turn on the first temperature controller and the second temperature controller, and adjust the temperature of the two temperature controllers and the current I of the first thermoelectric chip. 1 , so that the average temperature of the two thermoelectric chips rises to the measurement temperature condition T 0 .

[0047] In this step, see Figure 2 The temperature gradient diagram shown in the figure takes the thermoelectric parameters of the thermoelectric sheet at 50°C as an example. Two temperature controllers are turned on and the input current I of the first thermoelectric sheet is adjusted. 1 The temperature of the temperature controller raises the average temperature of the hot and cold ends of the first thermoelectric chip to 50°C. h1 With T h2 The difference ΔT is used to adjust the cold end temperature and current I of the temperature controller. 1 Meet T c2 =T c1 +ΔT, at this time, the average temperature of the second thermoelectric plate used as a heat flux meter is also 50°C, but the temperature difference is 2ΔT smaller than the former.

[0048] 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.

[0049] 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 a heat flow meter. Since the battery tester and the AC internal resistance meter do not generate direct current, it is not necessary to consider the influence of the Peltier effect when the thermoelectric sheet forms a path. Based on the test results and temperature data, the calculation module calculates the device-level physical property parameter Seebeck coefficient , the formula is: (1) 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 I of the second thermoelectric sheet 2 .

[0050] In this step, the electronic load is connected in series to form a path for the thermoelectric sheet of the heat flow meter. 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 to keep the average temperature of the two thermoelectric sheets at T. 0 =50℃, the current I 2 .

[0051] Step 5: Based on the device internal resistance R of the thermoelectric chip, the Seebeck coefficient α and the current I of the two thermoelectric chips 1 and I 2 , based on the equivalent relationship between the two thermoelectric sheets, determine the thermal conductivity K of the thermoelectric sheet to be tested.

[0052] In this step, according to the current temperature condition T calculated previously, 0 The Seebeck coefficient α and the device internal resistance R under the condition can be solved according to the steady-state equation when the thermoelectric sheet is in the power generation or cooling state to obtain the device thermal conductivity, and then calculate the thermal conductivity K of the particle. The calculation process is: For the heat flow at the hot end of the first thermoelectric element as a heat source: (2) For the heat flow at the hot end of the second thermoelectric chip as a heat flow meter: (3) By adjusting the temperature controller and the current I 1 Input, so that the average temperature of the two thermoelectric chips T 0 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, so that the steady-state equations of the heat transfer at the hot end of the two thermoelectric sheets can be combined, and then the known temperature and current parameters are substituted to solve the thermal conductivity K.

[0053] Therefore, neglecting heat losses, we have ,Right now (4) Since the other parameters in the equation are known, the total thermal conductivity K of the thermoelectric chip can be solved.

[0054] 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.

[0055] Preferably, the roles of the two thermoelectric sheets to be tested can be exchanged, or the thermoelectric sheets of the same model can be replaced and tested in the same way. Since the device adopts a vertically symmetrical structure, the position of the current sheet can be directly changed without reinstalling it. After the roles are exchanged, a series of parameters obtained 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.

[0056] Step 7: Test the maximum thermoelectric conversion efficiency of the thermoelectric chip under a certain working state: Testing the maximum conversion efficiency of thermoelectric power generation requires measuring the heat flow through the thermoelectric chip and the maximum power generation. The heat flow test is based on the previously measured device-level thermoelectric parameters, and uses electrical parameter identification to calculate the heat flow, thereby calculating the thermoelectric conversion efficiency.

[0057] Specifically: See Figure 5 , raise the temperature of the first temperature controller as a heat source, there are still two thermoelectric sheets in the middle, the first thermoelectric sheet on the upper side is used as a heat flux meter, and the second thermoelectric sheet on the lower side is used as a thermoelectric sheet to be tested for thermoelectric conversion efficiency. The hot end temperature T of the first thermoelectric sheet is adjusted by the first temperature controller h1 , use the second temperature controller to adjust the cold end temperature of the second thermoelectric sheet so that the temperature at both ends of the thermoelectric sheet to be tested can reach the required value of the hot and cold ends under the current test working state. For example, when measuring the heat source temperature of 150 degrees and the cold source temperature of 20 degrees, how much electricity the thermoelectric sheet can generate and the conversion efficiency, the temperature at both ends of the thermoelectric sheet to be tested needs to reach the corresponding temperature value.

[0058] If the required temperature is higher, the first temperature controller can be replaced by a conventional electric heating temperature controller, and the second temperature controller can be replaced by a pure liquid cooling temperature controller to maintain the temperature difference of the thermoelectric chip to be tested.

[0059] 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 W at this time. 1 . Measure the cold and hot end temperatures T of the first thermoelectric plate c1 and T h1 , and the input current I 1 .

[0060] Based on the previously measured device-level physical parameters, the physical parameters at the cold and hot end temperatures are interpolated, and the heat flux at the hot end of the thermoelectric element to be tested is calculated using formula (2): Q 1 , then the maximum thermoelectric conversion efficiency is (W 1 / Q h1 ) 100%.

[0061] Step 8: Test the cooling capacity and cooling efficiency of the thermoelectric cooling device under a certain working state.

[0062] See also Figure 6 The device arrangement is consistent with the way of testing thermoelectric power generation devices. At this time, the first thermoelectric plate is used as a cooling plate and a current consistent with the test working state is passed through it. The second thermoelectric plate is used as a heat flux meter and a certain current I is passed through it. 3 , that is, at this time, the second thermoelectric plate also acts as a heat flux meter and provides the heat load of the first thermoelectric plate Q h3, at this time there is cooling capacity Q c = Q h3 The first temperature controller and the second thermoelectric chip respectively maintain the temperature of the hot end and the cold end of the refrigeration chip to be consistent with the test working state. The test working state here refers to the cooling capacity and cooling efficiency of the refrigeration chip to be measured under a certain current input or working temperature.

[0063] Since the temperature of the hot end of the cooling plate is usually not high, the first temperature controller can still be a thermoelectric temperature controller, while the second temperature controller needs to provide heat dissipation for dissipating the hot end of the thermoelectric plate of the heat flux meter.

[0064] Measure the hot end temperature T of the second thermoelectric chip h3 , cold end temperature T c3 and input current I 3 , use the following formula (5) to calculate the cooling capacity of the piece to be tested Q c : (5) According to the electric power input value W 2 Calculate the refrigeration efficiency, refrigeration efficiency COP = ( Q c / W 2 ) 100%.

[0065] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in the description may be different and are not limited. Therefore, those skilled in the art in the field of the present invention may modify or replace the technical solutions recorded in the above embodiments; and these modifications and replacements do not deviate from the creative purpose and technical solutions of the present invention and should 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 chips 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; The calculation module is used to determine the thermoelectric parameters of the thermoelectric sheet to be tested 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.

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 components include 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. A device-level thermoelectric parameter testing method based on electrical parameter identification, characterized in that: Using the device-level thermoelectric parameter testing device based on electrical parameter identification as described in any one of claims 1 to 7, the method comprises the following steps: 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.

9. The device-level thermoelectric parameter testing method based on electrical parameter identification according to claim 8, characterized in that: The Seebeck coefficient α calculated in step 3 is: 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).

10. The device-level thermoelectric parameter testing method based on electrical parameter identification according to claim 8, characterized in that: The method further comprises: 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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