A method for measuring junction temperature of power module press-fit power device

Abstract

The present invention provides a method for measuring the junction temperature of a power module press-fit power device, including: 1: determining the position of a water-cooled radiator temperature measuring point; 2: establishing an accurate three-dimensional model of the water-cooled radiator; 3: using finite element simulation software to perform steady-state thermal simulation on the established water-cooled radiator model to obtain the thermal resistance value between the radiator temperature measuring point and the radiator table; 4: extracting the actual power module temperature measuring point data, and indirectly deriving and calculating the power device loss according to the relationship between the radiator temperature measuring point temperature and thermal resistance and loss; 5: calculating the power device junction temperature. The power module press-fit power device and its radiator are taken as the research objects, and the actual temperature is measured by setting a temperature measuring point on the radiator in contact with the power device, and the loss of the power device transmitting the radiator table is obtained by combining the finite element simulation calculation of the radiator thermal resistance result and the temperature measuring point temperature measurement result, so as to obtain the junction temperature of the power device.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic equipment, and in particular to a method for measuring the junction temperature of a power module press-fit type power device. Background Art

[0002] The power module is a key component of the flexible direct current converter, which can realize the effective conversion, control and transmission of electric energy. It is widely used in the field of high-voltage direct current transmission. The crimped IGBT (insulated gate bipolar transistor) is a key component of the power module. It has the advantages of fast switching speed, failure short circuit, double-sided heat dissipation, etc. It can realize fast switching action in high-power occasions and realize effective control of the circuit. When working, the IGBT is subjected to the combined effects of electrical, thermal and mechanical stresses, and the failure mechanism is complex. Heat accumulation is the main cause of IGBT failure, which is mainly manifested in excessively high or rapid fluctuations in junction temperature. Common failure modes include aging failure, micro-motion wear, gate oxide layer damage, gate spring pin failure, boundary warping, etc.

[0003] Traditional methods for obtaining IGBT junction temperature mainly include direct measurement method, thermal network method, electrical temperature measurement method, and finite element simulation analysis method.

[0004] Direct measurement methods include optical measurement and physical contact measurement. The former uses optical fiber or infrared imager to measure the temperature of IGBT, while the latter pastes or welds thermistor or thermocouple to the chip under test. The measurement method requires opening the package of the device under test, which is a destructive method for obtaining junction temperature.

[0005] The thermal network method iteratively calculates the junction temperature of the device by establishing an equivalent thermal impedance model between the IGBT junction and the case. Although this method ensures the integrity of the device, it is no longer applicable to power module IGBTs with multiple heat source coupling effects.

[0006] The electrical temperature measurement method uses the relationship between electrical parameters and temperature to obtain junction temperature data. It is simple to operate and has high accuracy. It does not need to destroy the package structure of the device under test. However, the addition of measuring equipment will change the parasitic parameters in the circuit, and the auxiliary detection circuit is often very complex, making it difficult to achieve online measurement.

[0007] The finite element simulation analysis method establishes a corresponding finite element simulation model and uses simulation software to calculate the junction temperature of the device, but the premise is that the model and material properties are accurate enough. At the same time, this method cannot realize the real-time calculation of the IGBT junction temperature and is only suitable for the analysis of the thermal aging characteristics of IGBT devices under experimental conditions. Summary of the invention

[0008] In order to solve the technical problems raised by the background technology and overcome the shortcomings of the traditional method for obtaining the junction temperature of power module press-fit devices, the present invention provides a method for measuring the junction temperature of a power module press-fit power device, which obtains the thermal resistance of the heat sink and the actual temperature of the temperature measuring point by means of finite element simulation and setting temperature measuring points, and then obtains the loss transmitted from the power device to the heat sink table, and calculates the junction temperature of the power device based on the relationship between thermal resistance, loss and temperature. The method is a reasonable and effective junction temperature measurement method that does not change the original heat dissipation conditions of the power module press-fit device and is used to evaluate the thermal aging of the power device.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for measuring the junction temperature of a power module press-fit power device, wherein the method takes the press-fit power device and its water-cooled heat sink in the power module as research objects, and comprises the following steps:

[0011] Step 1: Determine the location of the temperature measurement point of the water cooling radiator;

[0012] Step 2: Create an accurate 3D model of the water-cooled radiator, and keep the location and size of the internal water channels and temperature measurement points consistent with the actual ones;

[0013] Step 3: Use finite element simulation software to perform steady-state thermal simulation on the established water-cooled radiator model to obtain the thermal resistance value between the radiator temperature measurement point and the radiator surface;

[0014] Step 4: Extract the actual power module temperature measurement point data, and indirectly deduce and calculate the power device loss based on the relationship between the heat sink temperature measurement point temperature and thermal resistance and loss;

[0015] Step 5: Write down the relationship expression between the junction temperature of the power device and the thermal resistance, loss, and the actual temperature measured at the temperature measurement point, and calculate the junction temperature of the power device.

[0016] Furthermore, in step 1, the method for determining the position of the temperature measuring point of the water-cooled radiator is as follows: the temperature measuring point is set according to the layout of the radiator water channel and the size of the heat-generating device shell. The principle is that it does not affect the installation of the temperature measuring device and the heat dissipation of the radiator, and ensures that the temperature measuring point is as close to the edge of the heat-generating device shell as possible; a multi-point measurement method is adopted to set temperature measuring points at different positions on the upper and lower surfaces of the radiator, so that the vertical distance between the temperature measuring point and the device shell is the same, a temperature measuring point is set at the center of the side of the radiator, and the total number of temperature measuring points on the same radiator is not less than 3.

[0017] Furthermore, in step 2, the specific method for constructing the physical model of the water-cooled radiator is: measuring the external dimensions and internal water channel dimensions of the water-cooled radiator, establishing a three-dimensional model of the water-cooled radiator at a 1:1 ratio, and setting the temperature measurement point positions according to step 1.

[0018] Furthermore, in step 3, the method for obtaining the thermal resistance value between each temperature measuring point of the water-cooled radiator and the radiator table is: divide the water-cooled radiator and its internal cooling medium into corresponding grids, apply a constant loss P on the water-cooled radiator table, set a constant water inlet temperature T in , the radiator temperature field distribution and the corresponding temperature target value are obtained, and the thermal resistance formula is used for calculation. The formula is as follows:

[0019]

[0020] In formula 1, R th测i-台面 is the thermal resistance between the temperature measurement point of the radiator and the table surface, T 台面 is the simulated value of the heat sink surface temperature, T 测仿i is the temperature simulation value of the heat sink temperature measurement point, the number i is consistent with the actual number of temperature measurement points, and P is the constant loss value applied to the heat sink surface.

[0021] Furthermore, in step 4, the method for calculating the power device loss, i.e., the power device loss transmitted to the radiator table is as follows: a temperature measuring device is arranged at the radiator temperature measuring point, the temperature data of each radiator temperature measuring point is extracted, and the power device loss is indirectly deduced and calculated based on the relationship between thermal resistance, temperature and loss:

[0022] T 测i =R th测i-台面 ×P j +T in (i is consistent with the actual number of temperature measurement points; j = 1, 2) (2)

[0023] P j R is the loss from the power devices on both sides of the heat sink to the heat sink surface. th测i-台面 is the thermal resistance between the radiator temperature measurement point and the radiator surface where it is located, T in is the radiator cooling medium inlet water temperature, T 测i It is the actual measured value of the temperature at the radiator measuring point.

[0024] Furthermore, in step 5, the relationship between the power device junction temperature and the loss, thermal resistance, and the measured temperature at the temperature measurement point is calculated as follows:

[0025] T j结 =P j ×R th结—测 +T 测i (3)

[0026] In formula 3, T j结 (j=1, 2) is the junction temperature of the power devices on both sides of the heat sink, P j (j=1, 2) is the loss of the power devices on both sides of the heat sink transmitted to the heat sink table, R th结-测is the thermal resistance between the power device chip and the temperature measurement point of the heat sink, R th结—测 =R th结—壳 +R th测i—台面 , R th结—壳 is the single-sided junction-to-case thermal resistance from the power device to the heat sink, which can be obtained by referring to the device specification. th测i-台面 is the thermal resistance between the temperature measuring point of the radiator and the table top, and i is consistent with the actual number of temperature measuring points.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) The method of the present invention can take power module crimped power devices and their heat sinks as research objects, by adding temperature measuring points on the heat sink in contact with the power device to measure the temperature, and combining the heat sink thermal resistance results obtained by finite element simulation calculation and the temperature measurement results of the temperature measuring points to obtain the loss of the power device transmitting to the heat sink table, thereby obtaining the junction temperature of the power device.

[0029] 2) The present invention takes the crimped power device and its heat sink in the power module as the research object, without destroying the integrity of the power device, and overcomes the shortcomings of the thermal network method that cannot fully consider the coupling of multiple heat sources in the power module and the simple finite element simulation method and the electrical temperature measurement method. The temperature measurement method is simple, effective and feasible.

[0030] 3) The method of the present invention is applicable to power modules of different topological structures. Not only can the junction temperature of a press-fit IGBT device be obtained, but the junction temperature of a diode can also be obtained by using the method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the topology of a half-bridge power module of the present invention;

[0032] Figure 2 It is a specific implementation flow chart of the present invention;

[0033] Figure 3 A top view showing a schematic diagram of the locations of the temperature measurement points of the radiator of the present invention;

[0034] Figure 4 This is a front view of a schematic diagram of the location of the temperature measurement points of the radiator of the present invention;

[0035] Figure 5 Schematic diagram of thermal resistance from each temperature measuring point to the radiator surface of the present invention;

[0036] Figure 6 It is a schematic diagram of the thermal resistance from the IGBT chip to the temperature measurement point of the present invention.

[0037] In the figure: 1-temperature measuring point 1 2-temperature measuring point 2 3-temperature measuring point 3 4-table 5-water inlet. DETAILED DESCRIPTION

[0038] The specific implementation modes provided by the present invention are described in detail below with reference to the accompanying drawings.

[0039] like Figure 1 As shown, the power module press-fit power devices include press-fit IGBTs and diodes. Different topological structures only differ in the type and quantity of press-fit devices, and the press-fitting methods are the same, all of which are implemented by an external pressure mechanism. For a half-bridge power module, two press-fit IGBTs, two diodes and five water-cooled heat sinks are used to achieve electrical and thermal contact through pressure. Therefore, both press-fit IGBTs and diodes can obtain junction temperature through the junction temperature measurement method of the present invention.

[0040] like Figure 2-4 As shown, a method for measuring the junction temperature of a power module press-fit type power device of the present invention takes the press-fit type power device and its water-cooled heat sink in the power module as research objects, and comprises the following steps:

[0041] Step 1: Determine the location of the temperature measurement point of the water cooling radiator;

[0042] Step 2: Create an accurate 3D model of the water-cooled radiator, and keep the location and size of the internal water channels and temperature measurement points consistent with the actual ones;

[0043] Step 3: Use finite element simulation software to perform steady-state thermal simulation on the established water-cooled radiator model to obtain the thermal resistance value between the radiator temperature measurement point and the radiator table (4);

[0044] Step 4: Extract the actual power module temperature measurement point data, and indirectly deduce and calculate the power device loss based on the relationship between the heat sink temperature measurement point temperature and thermal resistance and loss;

[0045] Step 5: Write down the relationship expression between the junction temperature of the power device and the thermal resistance, loss, and the actual temperature measured at the temperature measurement point, and calculate the junction temperature of the power device.

[0046] In the step 1, the method for determining the position of the temperature measuring point of the water-cooled radiator is as follows: the temperature measuring point is set according to the arrangement of the radiator water channel and the size of the heat-generating device tube shell, in principle, it does not affect the installation of the temperature measuring device and the heat dissipation of the radiator, and ensures that the temperature measuring point is as close to the edge of the heat-generating device tube shell as possible; a multi-point measurement method is adopted, the temperature measuring points are set at different positions of the upper and lower surfaces (4) of the radiator, the vertical distance between the temperature measuring points and the device tube shell is the same, a temperature measuring point is set at the center position of the side of the radiator, and the total number of temperature measuring points on the same radiator is not less than 3.

[0047] The table surface (4) of the heat sink refers to the contact surface between the power device and the heat sink.

[0048] In step 2, the specific method for constructing the physical model of the water-cooled radiator is: measuring the external dimensions and internal water channel dimensions of the water-cooled radiator, establishing a three-dimensional model of the water-cooled radiator at a 1:1 ratio, and setting the temperature measurement point positions according to step 1.

[0049] In step 3, the method for obtaining the thermal resistance value between each temperature measuring point of the water-cooled radiator and the radiator table (4) is as follows: the water-cooled radiator and its internal cooling medium are divided into corresponding grids, a constant loss P is applied to the water-cooled radiator table (4), and a constant water inlet temperature T is set. in , the radiator temperature field distribution and the corresponding temperature target value are obtained, and the thermal resistance formula is used for calculation. The formula is as follows:

[0050]

[0051] In formula 1, R th测i-台面 is the thermal resistance between the temperature measurement point of the radiator and the table surface, T 台面 is the simulated temperature value of the radiator surface (4), T 测仿i is the temperature simulation value of the heat sink temperature measurement point, the number i is consistent with the actual number of temperature measurement points, and P is the constant loss value applied to the heat sink table (4).

[0052] The temperature measurement point of the heat sink and the temperature simulation value of the table (4) in step 3 are based on the highest temperature.

[0053] The method of dividing the corresponding grids in step 3 is: dividing the radiator into solid grids, and dividing the cooling medium inside the radiator into fluid grids.

[0054] In step 4, the method for calculating the power device loss, i.e., the power device loss transmitted to the heat sink table (4) is as follows: a temperature measuring device is arranged at the heat sink temperature measuring point, the temperature data of each heat sink temperature measuring point is extracted, and the power device loss is indirectly deduced and calculated based on the relationship between thermal resistance, temperature and loss:

[0055] T 测i =R th测i-台面 ×P j +T in (i is consistent with the actual number of temperature measurement points; j = 1, 2) (2)

[0056] P j is the loss of the power devices on both sides of the heat sink transmitted to the heat sink surface (4), R th测i-台面 is the thermal resistance between the radiator temperature measurement point and the radiator surface (4) where it is located, T in is the radiator cooling medium inlet water temperature, T 测i It is the actual measured value of the temperature at the radiator measuring point.

[0057] The loss of power devices transferred to the radiator surface is calculated by combining the measured temperature of each radiator temperature measurement point and the thermal resistance simulation value between the temperature measurement point and the radiator surface. Since the water channels inside the radiator are symmetrically distributed, the thermal resistance value between the temperature measurement point and the radiator surface is only related to the selected position. The actual number of thermal resistance parameters from each temperature measurement point to the radiator surface is less than the number of temperature measurement points. Combined with formula (2), the loss of power devices transferred to the radiator surface can be calculated by substituting the thermal resistance simulation data and the measured temperature of the temperature measurement point into formula (2).

[0058] The temperature measuring device in step 4 should be selected based on the principles of high temperature measurement accuracy, simple operation and easy installation. Preferably, a thermocouple or NTC (negative temperature coefficient) sensor is used.

[0059] In step 5, the relationship between the power device junction temperature and the loss, thermal resistance, and the measured temperature at the temperature measurement point is calculated as follows:

[0060] T j结 =P j ×R th结—测 +T 测i (3)

[0061] In formula 3, T j结 (j=1, 2) is the junction temperature of the power devices on both sides of the heat sink, P j (j=1, 2) is the loss of the power devices on both sides of the heat sink transmitted to the heat sink table, R th结-测 is the thermal resistance between the power device chip and the temperature measurement point of the heat sink, R th结—测 =R th结—壳 +R th测i—台面 , R th结—壳 is the single-sided junction-to-case thermal resistance from the power device to the heat sink, which can be obtained by referring to the device specification. th测i-台面 is the thermal resistance between the temperature measuring point of the radiator and the table (4), and i is consistent with the actual number of temperature measuring points. [Specific embodiment]

[0063] like Figure 3-4 As shown, in this embodiment, a total of 3 temperature measuring points are selected, wherein the specific locations of temperature measuring point 1 (1) and temperature measuring point 2 (2) are located at the heat sink table (4) 2 mm outside the diameter of the heat generating IGBT device shell table, respectively located on the central axis of the upper and lower tables (4) of the heat sink, and are arranged non-symmetrically from top to bottom; temperature measuring point 3 (3) is located on the side of the heat sink, specifically located at the center of the side away from the water inlet (5). Thermocouples or NTC temperature sensors are installed at the 3 temperature measuring points to monitor temperature changes in real time.

[0064] In this embodiment, Solidworks software is used to establish an accurate three-dimensional model of the water-cooled radiator. The water-cooled radiator is simplified as follows during modeling: 1. Ignore the mounting threaded holes on the side of the radiator; 2. Ignore the detailed features of the connection between the water inlet and outlet and the water pipe; 3. Use the inner diameter of the water pipe as the inner diameter size of the water inlet and outlet of the radiator. The CFDFluent module of ANSYS software is used to simulate the temperature field and fluid field of the finite element simulation model of the water-cooled radiator. The specific settings are as follows: 1. The radiator is divided into a solid grid, and the cooling medium inside the radiator is divided into a fluid grid; 2. The loss transmitted from the IGBT to the radiator table is set to P, and a reasonable value can be given during simulation; 3. Combined with the flow rate of the power module water cooling system, the radiator cooling medium inlet is set as a velocity boundary condition, and the outlet is set as a static pressure boundary condition; 4. The simulation ignores the effect of thermal radiation, and only considers heat conduction and convection heat transfer between the radiator and the air, and the convection heat transfer coefficient is set to 5W / (m 2 ·K). The temperature field distribution of the radiator and the fluid field distribution of the internal cooling medium are obtained by simulation, and the highest temperature results of the three temperature measurement points and the radiator table (4) are extracted as known data for subsequent thermal resistance calculation.

[0065] like Figure 5 As shown in the figure, the relationship between the measured temperature at the temperature measurement point and the thermal resistance, loss, and radiator water inlet temperature is as follows:

[0066]

[0067] In formula 3, T 测i (i=1, 2, 3) is the measured temperature of the three temperature measuring points, in units of °C; R1 and R3 are the thermal resistances between the heat sink temperature measuring points 1 (1) and 2 (2) and the heat sink surface where they are located, in units of K / kW; R2 and R4 are the thermal resistances between the heat sink temperature measuring points 1 and 2 and the heat sink surface (4) not located there, in units of K / kW; R5 and R6 are the thermal resistances between the heat sink temperature measuring point 3 (3) and the upper and lower surfaces (4) of the heat sink, respectively, in units of K / kW; P1 and P2 are the losses transmitted from the IGBT1 and IGBT2 on both sides of the heat sink to the heat sink surface (4), in units of kW; T in is the water inlet temperature of the radiator, in °C, which is a known value.

[0068] like Figure 5 As shown, since the water channels inside the radiator are symmetrically distributed, the thermal resistance between the temperature measurement point and the radiator surface (4) is only related to the selected position, so:

[0069]

[0070] Substituting equation 5 into equation 4, we get:

[0071]

[0072] In formula 6, T 测i , T in is a known value, R1, R2, and R5 are the thermal resistance values ​​obtained by finite element simulation. The losses P1 and P2 actually transmitted from IGBT1 and IGBT2 on both sides of the heat sink to the heat sink table (4) can be expressed by the following equations 7 and 8:

[0073]

[0074] like Figure 6 As shown, the relationship between the IGBT junction temperature and loss, thermal resistance, and the measured temperature at the temperature measurement point is expressed as follows:

[0075] T 1结 =P j ×R th结—测 +T 测i =P1×(R th1结-壳 +R1)+T 测1 (9)

[0076] T 2结 =P j ×R th结—测 +T 测i =P2×(R th2结—壳 +R3)+T 测2 (10)

[0077] In formula 9 and 10, R th1结—壳 , R th2结—壳 is the single-sided junction-to-case thermal resistance from IGBT1 and IGBT2 to the heat sink, which can be obtained by referring to the device specification. The junction temperature of IGBT1 and IGBT2 can be calculated by substituting the measured temperature at the temperature measurement point and the calculated loss and thermal resistance values.

[0078] The above embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A method for measuring junction temperature of a power module press-fit power device, characterized in that: The method takes the press-fit power device and the water-cooled heat sink in the power module as the research object, and comprises the following steps: Step 1: Determine the location of the temperature measurement point of the water cooling radiator; Step 2: Create an accurate 3D model of the water-cooled radiator, and keep the location and size of the internal water channels and temperature measurement points consistent with the actual ones; Step 3: Use finite element simulation software to perform steady-state thermal simulation on the established water-cooling radiator model to obtain the thermal resistance value between the radiator temperature measurement point and the radiator surface; Step 4: Extract the actual power module temperature measurement point data, and indirectly deduce and calculate the power device loss based on the relationship between the heat sink temperature measurement point temperature and thermal resistance and loss; Step 5: Write down the relationship expression between the junction temperature of the power device and the thermal resistance, loss, and the measured temperature of the temperature measurement point, and calculate the junction temperature of the power device; In step 3, the method for obtaining the thermal resistance value between each temperature measuring point of the water-cooled radiator and the radiator table is: divide the water-cooled radiator and its internal cooling medium into corresponding grids, apply a constant loss P on the water-cooled radiator table, set a constant water inlet temperature T in , the radiator temperature field distribution and the corresponding temperature target value are obtained, and the thermal resistance formula is used for calculation. The formula is as follows: In formula 1, R th测i-台面 is the thermal resistance between the temperature measurement point of the radiator and the table surface, T 台面 is the simulated value of the heat sink surface temperature, T 测仿i is the simulated value of the temperature at the heat sink temperature measurement point, the number of i is consistent with the actual number of temperature measurement points, and P is the constant loss value applied to the heat sink surface; The temperature simulation value of the heat sink temperature measurement point and the table temperature simulation value in step 3 are based on the highest temperature; In step 4, the method for calculating the power device loss, i.e., the power device loss transmitted to the radiator table, is as follows: a temperature measuring device is arranged at the radiator temperature measuring point, the temperature data of each radiator temperature measuring point is extracted, and the power device loss is indirectly deduced and calculated based on the relationship between thermal resistance, temperature and loss: T 测i =R th测i-台面 ×P j +T in (i is consistent with the actual number of temperature measurement points; j = 1, 2) (2)P j R is the loss from the power devices on both sides of the heat sink to the heat sink surface. th测i-台面 is the thermal resistance between the radiator temperature measurement point and the radiator surface where it is located, T in is the radiator cooling medium inlet water temperature, T 测i It is the actual measured value of the temperature at the radiator temperature measuring point; In step 5, the relationship between the power device junction temperature and the loss, thermal resistance, and the measured temperature at the temperature measurement point is calculated as follows: T j结 =P j ×R th结—测 +T 测i (3) In formula 3, T j结 (j=1, 2) is the junction temperature of the power devices on both sides of the heat sink, P j (j=1, 2) is the loss of the power devices on both sides of the heat sink transmitted to the heat sink table, R th结-测 is the thermal resistance between the power device chip and the temperature measurement point of the heat sink, R th结—测 =R th结—壳 +R th测i—台面 , R th结—壳 is the single-sided junction-to-case thermal resistance from the power device to the heat sink, which can be obtained by referring to the device specification. th测i-台面 is the thermal resistance between the temperature measuring point of the radiator and the table top, and i is consistent with the actual number of temperature measuring points.

2. A method for measuring junction temperature of a power module press-fit type power device according to claim 1, characterized in that: In the step 1, the method for determining the position of the temperature measuring point of the water-cooled radiator is as follows: the temperature measuring point is set according to the arrangement of the radiator water channel and the size of the heat-generating device shell. The principle is that it does not affect the installation of the temperature measuring device and the heat dissipation of the radiator, and ensures that the temperature measuring point is as close to the edge of the heat-generating device shell as possible; a multi-point measurement method is adopted to set temperature measuring points at different positions on the upper and lower surfaces of the radiator, so that the vertical distance between the temperature measuring point and the device shell is the same, a temperature measuring point is set at the center of the side of the radiator, and the total number of temperature measuring points on the same radiator is not less than 3.

3. A method for measuring junction temperature of a power module press-fit type power device according to claim 1, characterized in that: In step 2, the specific method for constructing the physical model of the water-cooled radiator is: measuring the external dimensions and internal water channel dimensions of the water-cooled radiator, establishing a three-dimensional model of the water-cooled radiator at a 1:1 ratio, and setting the temperature measurement point positions according to step 1.

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