A device for measuring the thermal impedance of a device

Abstract

The application relates to the technical field of measuring device coupling thermal impedance, and discloses a device coupling thermal impedance measuring device and method, which comprises a PCB board, a first device and a second device arranged on the PCB board, heating circuits connected to the two ends of the first device, a heating power supply and a first signal module arranged on the heating circuits, test circuits connected to the two ends of the second device, a test power supply, a collection system and a second signal module arranged on the test circuits, and a saturation pressure drop of the second device under the influence of the temperature of the first device under small current changing with time being collected by the collection system. The device can obtain the temperature rising curve and the temperature falling curve of the test device through one-time measurement, and can one-time measure the coupling thermal impedance of one device to multiple devices or the coupling thermal impedance of multiple devices to one device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of measuring device coupling thermal impedance, and particularly relates to a device coupling thermal impedance measuring device and method. BACKGROUND

[0002] With the development of power electronic technology, the power density of power modules is also increasing, and the junction temperature is also increasing, and temperature becomes an important factor affecting its reliability. Among them, the parallel application of devices is more and more widely used. In the parallel application of devices, the power loss of the device will not only affect its own temperature, but also the temperature of the adjacent devices will affect each other due to the thermal coupling effect. The junction temperature of the device is affected by the thermal coupling effect and increases, especially the devices located in the inner position are affected by the thermal coupling of the devices around them, and their temperature is higher than that of the devices on the outer edge. With the increase of device power and the increase of parallel number, the influence of thermal coupling effect on temperature is more and more great. The temperature rise problem caused by thermal coupling effect cannot be ignored. Studying the thermal coupling effect of one electronic device on another electronic device is crucial for module thermal management, life prediction and reliability evaluation. Through the measurement of coupling thermal impedance, not only the heat transfer effect between devices can be characterized, but also a more perfect RC thermal network model can be established to more accurately predict the junction temperature.

[0003] At present, the coupling thermal impedance between two devices is usually obtained by temperature sensor or other temperature measuring instrument to obtain the temperature rise or drop curve, and then the coupling thermal impedance of one device to another device is calculated; the junction temperature can also be obtained by building a circuit using temperature-sensitive electrical parameter method. In this process, the heating current needs to be quickly converted into test current for temperature-sensitive parameter measurement.

[0004] The former obtains the temperature change of the chip in the device through the temperature measuring instrument, and the error is large. Only the coupling thermal impedance of one device to another device can be measured. For the application scene of multiple devices, multiple tests need to be carried out, and the operation is complex and tedious. In the temperature-sensitive electrical parameter measurement, there is a process of switching the heating current to the test current. The time of converting the current will affect the collection of the highest temperature, and the length of time of this process will also affect the measurement result precision, so that the calculated coupling thermal impedance is small. SUMMARY

[0005] In order to solve the problems that the operation mode of obtaining the coupling thermal impedance between devices through the temperature measuring instrument in the prior art is complicated and inaccurate, and the time of converting the current in the process of obtaining the coupling thermal impedance between devices through the temperature-sensitive electrical parameter method affects the measurement of the junction temperature of the device and reduces the measurement precision, the present application provides a device coupling thermal impedance measuring device and method.

[0006] The technical scheme of the present application is as follows:

[0007] The application provides a device coupling thermal impedance measuring device, comprising:

[0008] The PCB board and the first device and the second device arranged on the PCB board, the heating circuit is connected to the two ends of the first device, the heating power supply and the first signal module are arranged on the heating circuit, the heating power supply and the first device are connected in series, the first signal module is connected in parallel between the gate and the negative electrode of the first device, the test circuit is connected to the two ends of the second device, the test power supply, the acquisition system and the second signal module are arranged on the test circuit, the test power supply and the second device are connected in series, the second signal module is connected in parallel between the gate and the negative electrode of the second device, the acquisition system is connected in parallel between the positive electrode and the negative electrode of the second device, and the second device is obtained through the acquisition system. The saturation voltage drop of the second device under the influence of the temperature of the first device under small current changes with time;

[0009] The second device provides a stable voltage through the second signal module to maintain the always-on state, the second device is arranged adjacent to the first device, and the second device is heated and cooled with the first device.

[0010] Further, the first signal module provides a first on-off signal, the on-off state of the first on-off signal controls the heating and cooling of the first device, and the first on-off signal is a step signal.

[0011] Further, the second signal module provides a second on-off signal, when the second device is heated or cooled with the first device, the second on-off signal remains in the on state, and the second on-off signal is an always-on signal.

[0012] Further, the first device includes at least one, when the first device is more than two, the heating circuit is connected to each of the first devices.

[0013] Further, the second device includes at least one, when the second device is more than two, the test circuit is connected to each of the second devices.

[0014] The application also provides a device coupling thermal impedance measuring method, which realizes the measurement of the device coupling thermal impedance through the measuring device described in any one of the above, comprising the following steps:

[0015] S1: arranging the first device and the second device on the PCB board, and connecting the heating circuit and the test circuit to the first device and the second device respectively;

[0016] S2: open the heating circuit to heat the first device, and open the test circuit and collect the saturation voltage drop of the second device under small current affected by the temperature of the first device over time;

[0017] S3: the saturation voltage drop of the second device under small current over time collected by the second device is converted into the temperature change curve of the second device through the characteristic curve of the second device;

[0018] S4: the coupling thermal impedance of the first device to the second device is calculated through the temperature change curve of the second device.

[0019] Further, the step S2 comprises:

[0020] The first device is heated to a first thermal equilibrium state after the first signal module is turned on, and the heating period is 0-t1; the first device is cooled to a second thermal equilibrium state after the first signal module is turned off, and the cooling period is t1-t2;

[0021] The second device is heated to a third thermal equilibrium state affected by the heating of the first device, and the heating period is 0-t1; the second device is cooled to a fourth thermal equilibrium state affected by the cooling of the first device, and the cooling period is t1-t2.

[0022] Further, the step S2 further comprises:

[0023] The time when the test circuit and the collection system are opened is the same as or earlier than the time when the heating circuit is opened.

[0024] Further, the step S3 comprises:

[0025] The expression of the characteristic curve of the second device is:

[0026] V(t)=k×T j (t)+b (1);

[0027] Wherein, V(t) is the saturation voltage drop of the second device under small current, T j (t) is the temperature change curve of the second device;

[0028] The temperature change curve of the second device includes a heating curve T1(t) and a cooling curve T2(t).

[0029] Further, the step S4 comprises:

[0030] The coupling thermal impedance of the first device to the second device is calculated through the heating curve T1(t) of the second device:

[0031]

[0032] Wherein, Z th(1-2) is the coupling thermal impedance of the first device to the second device in the heating process, T1(t) is the heating curve of the second device in the period of 0-t1, T2(t=0) is the initial temperature of the second device, and P1 is the power value of the load current in the heating process of the first device.

[0033] The first device calculates the coupling thermal impedance to the second device through the cooling curve T2(t) of the second device.

[0034]

[0035] Wherein, Z th(1-2) is the coupling thermal impedance of the first device to the second device in the cooling process, T2(t) is the cooling curve of the second device in the period of t1-t2, T2(t=t1) is the initial temperature in the cooling process of the second device, that is, the highest temperature of the second device, and P1 is the power value of the load current in the heating process of the first device.

[0036] Further, the step S4 further comprises:

[0037] The coupling thermal resistance and the coupling thermal capacity are calculated through the coupling thermal impedance of the first device to the second device, and are obtained through the following expression:

[0038]

[0039] Wherein, R th(1-2) is the coupling thermal resistance of the first device to the second device, C th(1-2) is the coupling thermal capacity of the first device to the second device, and t is the period of heating or cooling of the first device.

[0040] The beneficial effects of the present application at least include:

[0041] (1) Through the measurement method provided by the present application, the heating curve and the cooling curve of the test device can be obtained by measuring once, and the operation is simpler and more convenient.

[0042] (2) The value of the coupling thermal impedance is obtained through the way that the first device is connected to the heating circuit and the second device is connected to the test circuit, the temperature-sensitive electrical parameter is continuously collected through the establishment of the two circuits, the sampling frequency is changed to improve the accuracy of the measurement result, which is more accurate and reduces the error.

[0043] (3) Through the measurement device and method provided by the present application, the coupling thermal impedance of one device to multiple devices, or the coupling thermal impedance of multiple devices to one device can be measured at one time. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1A structural schematic diagram of a device coupling thermal impedance measurement device provided by the present application.

[0045] Figure 2 An implementation flowchart of a device coupling thermal impedance measurement method provided by the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0047] Embodiment 1

[0048] In combination with Figure 1 As shown in the figure, the present embodiment provides a device coupling thermal impedance measurement device provided by the present application, which comprises:

[0049] The PCB board and the first device and the second device arranged on the PCB board, the first device is connected with a heating circuit at both ends, the heating circuit is provided with a heating power supply and a first signal module, the heating power supply and the first device are connected in series, the first signal module is connected in parallel at both ends of the gate and the negative electrode of the first device, the second device is connected with a test circuit at both ends, the test circuit is provided with a test power supply, a collection system and a second signal module, the test power supply and the second device are connected in series, the second signal module is connected in parallel at both ends of the gate and the negative electrode of the second device, the collection system is connected in parallel at both ends of the positive electrode and the negative electrode of the second device, the second device acquires the saturation voltage drop of the second device under the influence of the first device temperature with the collection system, and the saturation voltage drop of the second device under the influence of the first device temperature with the collection system is obtained.

[0050] The second device provides a stable voltage through the second signal module to keep the always-on state, the second device is arranged adjacent to the first device, and the second device is heated and cooled with the heating and cooling of the first device.

[0051] The first device and the second device each comprise three electrodes of a positive electrode, a negative electrode and a gate electrode, the first device and the second device are arranged on the PCB board, the first device is connected with the heating power supply and the first signal module through the wires, the second device is connected with the test power supply, the collection system and the second signal module through the wires, and the measurement of the device coupling thermal impedance is realized.

[0052] Further, the first signal module provides a first on-off signal, and the on-off state of the first on-off signal controls the temperature rise and temperature drop of the first device, the first on-off signal is a step signal, when the first on-off signal is on, it is the temperature rise process of the first device, and the first device is heated to a first thermal equilibrium state during this period; when the first on-off signal is off, it is the temperature drop process of the first device, and the first device is cooled to a second thermal equilibrium state during this period.

[0053] Further, the second signal module provides a second on-off signal, and when the second device rises in temperature or drops in temperature with the first device, the second on-off signal remains on, and the second on-off signal is a normally-on signal. The second device remains on during the temperature rise and temperature drop of the first device, and the second device rises in temperature and drops in temperature with the temperature rise and temperature drop of the first device, and the current provided by the test circuit is as small as possible to avoid affecting the temperature of the second device.

[0054] The heating circuit and the test circuit work simultaneously, and the saturation voltage drop is a temperature-sensitive parameter used in the temperature-sensitive parameter method, which can be obtained by obtaining different temperature-sensitive parameters according to different applications of the device, and the test circuit obtains the saturation voltage drop-time curve of the second device under a small current affected by the temperature of the first device through the acquisition system.

[0055] The saturation voltage drop-time curve measured by the test circuit is converted into the temperature change curve of the second device through the characteristic curve, that is, the K curve. Through the measuring device provided in this embodiment, the test circuit can measure the saturation voltage drop curve of the second device under a small current in the temperature rise process and the temperature drop process of the second device in one test process, and then convert the saturation voltage drop curve into the temperature change curve of the second device in the temperature rise process and the temperature drop process through the characteristic curve, and further calculate the coupling thermal impedance of the first device to the second device according to the temperature change curve.

[0056] This embodiment realizes higher-precision measurement by increasing the sampling frequency of the saturation voltage drop, and avoids the need to convert the heating circuit into the test circuit in a very short time in the existing measurement method when implementing the temperature-sensitive electrical parameter method, thereby affecting the precision of the measurement result.

[0057] Further, the first device includes at least one, and when the number of the first devices is two or more, each of the first devices is connected with a heating circuit.

[0058] When the number of the first devices is greater than one, a heating circuit is arranged for each of the first devices, and the test circuit is connected to the second device to measure the saturation voltage drop of the second device under a small current, which is converted into the temperature change curve of the second device through the K curve, and then the sum of the coupling thermal impedances of the first devices to the second device is calculated.

[0059] Furthermore, the second device includes at least one, and when there are two or more second devices, each of the second devices is connected to a test circuit.

[0060] When the number of second devices is greater than 1, a test circuit is arranged for each of the multiple second devices, a heating circuit is connected to the first device, the saturation voltage drop of the multiple second devices under small current is measured, and the temperature change curve of the second device is converted through the K curve, and then the coupling thermal impedance of the first device to the multiple second devices is calculated.

[0061] The first and second devices are positioned on the PCB board according to the actual application scenario, and heat dissipation conditions are set. Then, the heating circuit and the test circuit are connected respectively. The first turn-on signal of the first device and the heating power supply are turned on. At this time, the time is 0. The heating current passes through the first device, the first device generates heat, which flows to the heat dissipation device and diffuses to the second device until the temperature of the first device reaches the second thermal equilibrium state. At this time, the time is t1. The first turn-on signal is turned off, the heating current is turned off, and the first device cools down to the second thermal equilibrium state. At this time, the time is t2. The second turn-on signal of the test circuit is turned on, and then the test power supply of the test circuit is turned on. The test power supply and the heating power supply are turned on simultaneously or in advance to ensure complete measurement of the influence of the first device on the second device. The second device heats up or cools down with the heating or cooling of the first device. The second device reaches the third thermal equilibrium state at t1 and the fourth thermal equilibrium state at t2. The acquisition system acquires the saturation voltage drop curve of the second device over time, and then converts it into a temperature curve based on the characteristic curve of the second device, and then calculates the coupling thermal impedance of the first device to the second device.

[0062] In this embodiment, the measuring device provided in this embodiment is used, and the test current is kept as small as possible to ensure that the heat generated has little impact on the second device.

[0063] Example 2

[0064] In conjunction with Example 1 and Figure 2 As shown, this embodiment provides a method for measuring the coupling thermal impedance of a device. The method utilizes the measuring device described in any one of Embodiments 1 to measure the coupling thermal impedance of the device, and includes the following steps:

[0065] S1: Arrange the first device and the second device on the PCB board, and connect the heating circuit and the test circuit to the first device and the second device respectively;

[0066] S2: Turn on the heating circuit to heat the first device, and at the same time turn on the test circuit to collect the curve of the saturation voltage drop of the second device under low current as a function of the temperature of the first device over time.

[0067] S3: the saturation voltage drop curve of the small current collected by the second device is converted into the temperature change curve of the second device through the characteristic curve of the second device;

[0068] S4: the coupling thermal impedance of the first device to the second device is calculated through the temperature change curve of the second device.

[0069] Further, the step S2 comprises:

[0070] The first device is heated to the first thermal equilibrium state after the first signal module is turned on, and the heating period is 0-t1. The first device is cooled to the second thermal equilibrium state after the first signal module is turned off, and the cooling period is t1-t2.

[0071] The second device is heated to the third thermal equilibrium state due to the heating of the first device, and the heating period is 0-t1. The second device is cooled to the fourth thermal equilibrium state due to the cooling of the first device, and the cooling period is t1-t2.

[0072] Further, the step S2 further comprises:

[0073] The time when the test circuit and the collection system are turned on is the same as or earlier than the time when the heating circuit is turned on.

[0074] Further, the step S3 comprises:

[0075] The expression of the characteristic curve of the second device is:

[0076]

[0077] Wherein, V(t) is the saturation voltage drop of the second device under small current, T j (t) is the temperature change curve of the second device;

[0078] The temperature change curve of the second device includes the heating curve T1(t) and the cooling curve T2(t).

[0079] Further, the step S4 comprises:

[0080] The coupling thermal impedance of the first device to the second device is calculated through the heating curve T1(t) of the second device:

[0081]

[0082] Wherein, Z th(1-2) is the coupling thermal impedance of the first device to the second device during the heating process, T1(t) is the heating curve of the second device within the period of 0-t1, T2(t=0) is the initial temperature of the second device, and P1 is the power value of the load current during the heating of the first device.

[0083] The first device calculates the coupling thermal impedance of the second device through the cooling curve T2(t) of the second device:

[0084]

[0085] Wherein, Z th(1-2) is the coupling thermal impedance of the first device to the second device during the cooling process, T2(t) is the cooling curve of the second device within the time period t1-t2, T2(t=t1) is the initial temperature of the second device during the cooling process, i.e. the highest temperature of the second device, P1 is the power value of the load current of the first device during the heating process.

[0086] Further, the step S4 further comprises:

[0087] The coupling thermal resistance and the coupling thermal capacity are calculated through the coupling thermal impedance of the first device to the second device, and are obtained through the following expression:

[0088]

[0089] Wherein, R th(1-2) is the coupling thermal resistance of the first device to the second device, C th(1-2) is the coupling thermal capacity of the first device to the second device, and t is the time period of the temperature rise or fall of the first device.

[0090] Use of the embodiment:

[0091] The first device is turned on through the first on-off signal of the heating circuit, and the heating power on the heating circuit is turned on at the same time. The temperature of the first device rises to the first thermal equilibrium state. At this time, the time is t1. The step time of the first on-off signal is set long enough to make the temperature of the first device rise to the stable state. After the first on-off signal is reset to zero, the first device is turned off, the heating current is cut off, and the first device starts to cool down to the second thermal equilibrium state. At this time, the time is t2.

[0092] At the same time when the first device is heated, the second device is turned on through the second on-off signal on the test circuit to keep it in the always-on state, and the test power on the test circuit is turned on at the same time. The test current for the test circuit is started. The temperature of the second device rises to the third thermal equilibrium state of the second device due to the influence of the temperature rise of the first device. At this time, the time is t1. After the first device is turned off, the temperature of the second device cools down to the fourth thermal equilibrium state due to the influence of the temperature fall of the first device. At this time, the time is t2. 0-t1-t2 is the time of the entire measurement process. During the entire measurement process, the test current of the second device remains always on. The saturation voltage drop of the second device under the small current within the time period 0-t1-t2 is obtained, and the saturation voltage drop-time curve is drawn according to the same.

[0093] In the embodiment, the opening time of the test circuit and the starting time of the acquisition system cannot represent the 0 time, the opening time of the heating circuit is the 0 time, and the test circuit and the acquisition system need to be opened simultaneously or in advance with the heating circuit.

[0094] Before the measurement starts, the characteristic curve of the second device is measured in advance, the saturation voltage drop of the second device under a small current obtained after the measurement is converted into a temperature curve of the second device, the temperature curve includes a temperature rising curve and a temperature falling curve, and then the coupling thermal impedance of the first device to the second device is calculated through formulas (2) and (3).

[0095] The coupling thermal impedance can be fitted by a curve fitting toolbox in MATLAB, and the coupling thermal impedance and the coupling thermal capacity are fitted through formula (4).

[0096] In the embodiment, the first temperature difference T1(t)-T2(t=0) between the temperature rising curve of the second device in the temperature rising process and the initial temperature of the second device before the temperature rising is calculated;

[0097] The ratio of the first temperature difference to the power P1 of the heating current applied to the first device is the coupling thermal impedance of the first device to the second device in the temperature rising process;

[0098] In the embodiment, the second initial time of the second device and the second temperature difference T2(t=t1)-T2(t) between the temperature falling curve of the second device in the temperature falling process are calculated;

[0099] The ratio of the second temperature difference to the power P1 of the heating circuit applied to the first device is the coupling thermal impedance of the first device to the second device in the temperature falling process.

[0100] The first device and the second device in the embodiment include but are not limited to various power semiconductor devices in single-tube and module types. The first device and the second device are connected to the heating circuit and the test circuit in the same way, and the devices are directly connected to the power supply through wires, but due to the characteristics of the power semiconductor device, the device is not turned on, so the circuit is not turned on after connection. A gate signal is connected in parallel between the gate and the negative electrode of the device, which is used to control the device to turn on and turn on the circuit to form a current loop.

[0101] In the embodiment, each step is implemented by manual operation control.

[0102] Embodiment 3

[0103] In combination with embodiments 1 and 2, the embodiment can also measure multiple coupling thermal impedances of one device to multiple devices by arranging the positions of the devices and the circuits.

[0104] In the single-tube SiC MOSFET parallel motor controller, 5 single-tube devices are connected in parallel to form a bridge arm, and the coupling thermal impedance of the first device to the other 4 second devices in parallel is measured as follows:

[0105] According to the single-tube parallel motor controller application scenario, the positions of all devices are arranged, the heat dissipation conditions are set, and the heat sink is provided for the controller to dissipate heat. A heating circuit is arranged for the first device, and a test circuit is arranged for each of the other four second devices.

[0106] The first device opens the first communication signal, and then the heating power of the heating circuit is turned on. At this time, the time is 0, the heating current passes through the first device, the first device generates heat, flows to the heat sink, and spreads laterally to the other second devices, until the temperature of the first device reaches the first thermal equilibrium state, at which time the time is t1, then the first communication signal is zeroed, and the heating power is turned off. The first device cools down to the second thermal equilibrium state, at which time the time is t2.

[0107] The second communication signal of the test circuit is turned on, and then the test power of the test circuit is turned on. The test power ensures that it is turned on at the same time as the heating power or earlier than the heating power, so as to ensure the complete test of the influence of the first device on the second device. The test current is as small as possible to ensure that the heat generated by the test current is not enough to affect the measurement of the second device.

[0108] The second device is affected by the temperature rise of the first device in the 0-t1 time period, and the temperature of the second device also rises until it reaches the third thermal equilibrium state of the second device. The second device is affected by the temperature drop of the first device in the t1-t2 time period, and the temperature of the second device also drops until it reaches the fourth thermal equilibrium state of the second device. The operations of the four second devices are performed simultaneously, and the saturation voltage drops of the four second devices under small current are collected through the multiple channels of the acquisition system.

[0109] The characteristic curves of the four second devices are measured in advance, and the saturation voltage drops of each second device under small current in the 0-t2 time period are collected through the above steps V DS-i (t), and converted into the temperature change curve T i (t) of the second device in the 0-t2 time period.

[0110] The characteristic curve of the second device is as follows:

[0111]

[0112] Where i=2,3,4,5, respectively, indicating the four second devices, k i , b iThe coefficients of the characteristic curve of the device i can be obtained by experiment or datasheet of the device;

[0113] T (t) = T0+ (t-t0) * k1 (1) i T (t) = T0+ (t-t0) * k1 (1) i T (t) = T0+ (t-t0) * k1 (1)

[0114] Then the coupling thermal impedance of the first device to the second device is calculated by formula (2) and formula (3), and the coupling thermal impedance of the first device to the four second devices is calculated by the above steps, and the coupling thermal impedance of the first device to the four second devices and the coupling thermal capacity of the first device to the four second devices can also be calculated by formula (4).

[0115] Example 4

[0116] In combination with examples 1 and 2, the coupling thermal impedance of multiple devices to one device can also be measured by arranging the positions of the devices and the circuit.

[0117] In a single-tube SiC MOSFET parallel motor controller, five single-tube devices are connected in parallel to form a bridge arm, and the coupling thermal impedance of the second device to the other four first devices connected in parallel is measured, and the arrangement is as follows:

[0118] According to the application scene of single-tube parallel motor controller, the positions of all devices are arranged, and the heat dissipation condition is set. In this embodiment, a heat sink is provided for the controller to dissipate heat, a test circuit is arranged for the second device, and a heating circuit is arranged for each of the other four first devices;

[0119] The first opening signal of the heating circuit is turned on, and then the heating power of the heating circuit is turned on. At this time, the time is 0, the first device flows through the heating current to generate heat, and the heat is dissipated to the heat sink and diffused to the second device horizontally until the temperature of the first device reaches the first thermal equilibrium state. At this time, the time is t1, then the first opening signal is zero, and the heating power is turned off. The first device cools down to the second thermal equilibrium state, and the time is t2;

[0120] The above steps are taken for the four first devices to obtain the heating and cooling times;

[0121] The second opening signal of the test circuit is turned on, and then the test power of the test circuit is turned on. The test power ensures that it is turned on at the same time as the heating power or earlier than the heating power, so as to ensure that the test of the influence of the first device on the second device is completed, the test current is as small as possible, and the heat generated by the test current is not enough to affect the measurement of the second device.

[0122] During the time period from 0 to t1, the temperature of the second device is affected by the temperature increase of the other four first devices, and the temperature of the second device also increases until it reaches the third thermal equilibrium state. During the time period from t1 to t2, the temperature of the second device is affected by the temperature decrease of the other four first devices, and the temperature of the second device also decreases until it reaches the fourth thermal equilibrium state. The saturation voltage drop of the second device under small current is collected by the acquisition system.

[0123] The characteristic curve of the second device was measured in advance, and the saturation voltage drop V of the second device under low current during the time period from 0 to t2 was collected through the above steps. DS-i (t), and converted into the temperature change curve T of the second device during the time period from 0 to t2. i (t);

[0124] The characteristic curve of the second device is as follows:

[0125] V DS-i (t)=k i ×T i (t)+b i (6);

[0126] Where i = 1, k i b i The coefficients of the characteristic curve of device i can be obtained through experiments or the device's datasheet;

[0127] Among them, T1(t) during the time period from 0 to t1 is the heating curve of the second device, and T1(t) during the time period from t1 to t2 is the cooling curve of the second device;

[0128] Next, the sum of the coupling thermal impedances Zth-1 of the four first devices to the second device is calculated using equations (2) and (3). Zth-1 represents the sum of the four coupling thermal impedances of the four first devices to the second device, as shown in the following equation:

[0129] Z th-1 =Z th(2-1) +Z th(3-1) +Z th(4-1) +Z th(5-1) (7);

[0130] Wherein, Zth-1 is the sum of the coupling thermal impedance of the four first devices to the second devices, and the power values ​​of the load are the same during the heating process of the four first devices;

[0131] The coupling thermal resistance of the four first devices to the second device and the coupling thermal capacity of the four first devices to the second device can also be calculated by equation (4).

[0132] Through the embodiments provided by the application, the temperature rising curve and the temperature falling curve of the measured device can be obtained at one time, the coupling thermal impedance of one device to multiple devices can be measured at the same time by increasing the number of test circuits, or the coupling thermal impedance of multiple devices to one device can be measured at the same time by increasing the number of heating circuits, the operation is simple, the test times are reduced, and the labor cost and the time cost are saved; and through the construction of the heating circuit and the test circuit, the continuous acquisition of the temperature-sensitive electrical parameters can be realized, and the precision of the measurement result can be improved by changing the sampling frequency.

[0133] The above is only an embodiment of the application, and does not limit the patent range of the application, and any equivalent structure or equivalent flow transformation made by using the content of the specification and the drawings, or direct or indirect application in other related technical fields, is also included in the patent protection range of the application.

Claims

1. A method for measuring the coupling thermal impedance of a device, characterized in that: The measurement of device coupling thermal impedance is realized based on a measuring device, the measuring device comprising: The PCB board and a first device and a second device mounted on the PCB board are provided. The first device is connected to a heating circuit at both ends. The heating circuit is equipped with a heating power supply and a first signal module. The heating power supply is connected in series with the first device. The first signal module is connected in parallel between the gate and the negative terminal of the first device. The second device is connected to a test circuit at both ends. The test circuit is equipped with a test power supply, a data acquisition system and a second signal module. The test power supply is connected in series with the second device. The second signal module is connected in parallel between the gate and the negative terminal of the second device. The data acquisition system is connected in parallel between the positive and negative terminals of the second device. The second device acquires the saturation voltage drop curve of the second device under low current affected by the temperature of the first device over time. The second device is provided with a stable voltage through the second signal module to maintain a normally open state. The second device is arranged adjacent to the first device, and the second device heats up and cools down along with the first device. The measurement method includes the following steps: S1: Arrange the first device and the second device on the PCB board, and connect the heating circuit and the test circuit to the first device and the second device respectively; S2: Turn on the heating circuit to heat the first device, and at the same time turn on the test circuit to collect the curve of the saturation voltage drop of the second device under low current as a function of the temperature of the first device over time. S3: The curve of saturation voltage drop under low current collected by the second device is converted into the temperature change curve of the second device through the characteristic curve of the second device; S4: Calculate the coupling thermal impedance of the first device to the second device using the temperature change curve of the second device; Step S2 includes: The first device heats up to a first thermal equilibrium state after the first signal module is turned on, and the heating period is 0- t 1. The first device cools down to a second thermal equilibrium state after the first signal module is turned off, and the cooling period is... t 1- t 2; The second device is heated to the third thermal equilibrium state by the heating effect of the first device, and the heating period is 0- t 1. The second device cools down to the fourth thermal equilibrium state due to the cooling effect of the first device, and the cooling period is... t 1- t 2; Step S2 further includes: The timing of turning on the test circuit and the acquisition system is the same as or earlier than the timing of turning on the heating circuit; Step S3 includes: The expression for the characteristic curve of the second device is: （1）； in, V ( t ) represents the saturation voltage drop of the second device under low current. T j ( t ( ) is the temperature change curve of the second device; The temperature change curve of the second device includes a heating curve. T 1 ( t ) and cooling curve T 2 ( t ).

2. The method for measuring the coupling thermal impedance of a device according to claim 1, characterized in that: The first signal module provides a first turn-on signal, and the turn-on and turn-off states of the first turn-on signal control the heating and cooling of the first device. The first turn-on signal is a step signal.

3. The method for measuring the coupling thermal impedance of a device according to claim 1, characterized in that: The second signal module provides a second turn-on signal. When the second device heats up or cools down along with the first device, the second turn-on signal remains on. The second turn-on signal is a normally open signal.

4. The method for measuring the coupling thermal impedance of a device according to claim 1, characterized in that: The first device includes at least one, and when there are two or more first devices, each of the first devices is connected to a heating circuit.

5. The method for measuring the coupling thermal impedance of a device according to claim 1, characterized in that: The second device includes at least one, and when there are two or more second devices, each of the second devices is connected to a test circuit.

6. The method for measuring the coupling thermal impedance of a device according to claim 1, characterized in that: Step S4 includes: The temperature rise curve of the first device through the second device T 1 ( t The coupling thermal impedance to the second device was calculated: （2）； Among them, Z th（1-2） The coupling thermal impedance of the first device to the second device during the heating process is given. T 1 ( t ) is the second device in 0- t Temperature rise curve over a period of time 1 T 2 ( t =0) is the initial temperature of the second device. P 1 represents the power value of the load current during the heating process of the first device; The cooling curve of the first device through the second device T 2 ( t The coupling thermal impedance to the second device was calculated: （3）； Among them, Z th（1-2） The coupling thermal impedance of the first device to the second device during the cooling process is given. T 2 ( t ) for the second device in t 1- t The temperature drop curves over two time periods T 2 ( t = t 1) The initial temperature during the cooling process of the second device is also the highest temperature of the second device. P 1 represents the power value of the load current during the heating process of the first device.

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