Test method for the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution

Abstract

This application provides a method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution, including: establishing a transient temperature model of the package material; performing lumped parameter equivalence and replacement on the temperature of the package material within the power semiconductor device to obtain the transient relationship between on-state voltage drop and junction temperature; fixing the device's operating time while changing the switching frequency or bus voltage, measuring multiple sets of on-state voltage drop data under different junction temperature conditions, and fitting a linear function to the fixed operating time. t The application employs a parameter-based approach to determine the relationship between on-state voltage drop and junction temperature. By varying the operating time, fixing the current operating time, and changing the switching frequency or bus voltage, a transient relationship between on-state voltage drop and junction temperature is generated. The on-state voltage drop and operating time of the device are measured online, and the junction temperature is measured online using this transient relationship. This application addresses the junction temperature measurement error caused by package temperature gradients under transient operating conditions by correcting the relationship between on-state voltage drop and junction temperature using transient parameters.

Description

Technical Field

[0001] This application relates to the field of power semiconductor device testing, and more specifically, to a method for testing the transient relationship between on-state voltage drop and junction temperature, taking into account the package temperature distribution. Background Technology

[0002] The method of measuring the junction temperature of power semiconductors using on-state voltage drop as a temperature-sensitive parameter has attracted widespread attention due to its non-invasiveness and high sensitivity. To ensure the accuracy of online junction temperature measurement, the relationship between the on-state voltage drop and the junction temperature of the device under test needs to be pre-tested.

[0003] Existing methods for testing the relationship between on-state voltage drop and junction temperature require placing the device under test (DUT) in a temperature chamber or constant temperature heating stage. The internal temperature of the DUT is made the same as the ambient temperature by heating it with the external environment. Then, a short current pulse is applied to measure the relationship between on-state voltage drop and junction temperature.

[0004] In the prior art, CN119104862A discloses an online monitoring method for the junction temperature and thermal impedance of power devices during power cycling and heating. The method includes: online tuning of the on-state voltage drop and junction temperature relationship of the device under test (DUT) during power cycling; online calculation of the junction temperature of the DUT during the heating process based on the on-state voltage drop and junction temperature relationship; online calculation of the transient thermal impedance of the DUT based on the junction temperature; and automatic judgment and retuning of the on-state voltage drop and junction temperature relationship during power cycling to ensure the accuracy of the junction temperature and transient thermal impedance. However, under actual operating conditions, the above technical solution suffers from significant temperature gradients within the device, and the temperatures of each layer of the packaging material (solder, bonding wires, etc.) change with the transient operation, causing significant changes in the on-state voltage drop and junction temperature relationship characteristics, leading to increased errors in junction temperature calculation.

[0005] Therefore, it is necessary to improve the method for testing the relationship between on-state voltage drop and junction temperature. On the one hand, it is necessary to modify the model of the relationship between on-state voltage drop and junction temperature so that it is applicable under different transient operating conditions. On the other hand, it is necessary to create internal temperature distribution conditions that are similar to the actual operating conditions during pre-testing, and to measure and characterize the key characteristic state parameters of the device under different temperature distribution conditions. Summary of the Invention

[0006] In view of one of the deficiencies in the prior art, the purpose of this application is to provide a test method for the transient relationship between on-state voltage drop and junction temperature that takes into account the package temperature distribution.

[0007] A first aspect of this application provides a method for testing the transient relationship between on-state voltage drop and junction temperature, taking into account the package temperature distribution, comprising:

[0008] A lumped transient temperature model is established, which equates the temperature distribution of the packaging material within the power semiconductor device to the node temperature on the junction-to-ambient thermal path. The lumped transient temperature model is then substituted into the linear relationship between on-state voltage drop and junction temperature for parameter replacement, yielding the transient relationship between on-state voltage drop and junction temperature.

[0009] ;

[0010] Among them, the on-state voltage drop of the device V ce ( t ) and junction temperature T j ( t The relationship is a linear function, with the slope parameter of the expression being... k 1( t and intercept parameters k 2( t (Changes over time)

[0011] The device was operated in DC switching mode. The operating time of the device was fixed, but the switching frequency or bus voltage was varied. Multiple sets of on-state voltage drop data were measured under different junction temperature conditions. A linear function was then used to fit the data at the fixed operating time. t Relational parameters at 0;

[0012] By changing the operating time, fixing the current operating time, and changing the switching frequency or bus voltage, the relationship parameters between the on-state voltage drop and junction temperature under multiple operating times are obtained, thereby generating expressions for the slope parameter and intercept parameter of the relationship.

[0013] By substituting the expressions for the slope parameter and the intercept parameter into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated. Using this transient relationship between the on-state voltage drop and the junction temperature, the on-state voltage drop and the operating time of the device are measured online, and the junction temperature is measured online.

[0014] Optionally, the step of establishing a lumped transient temperature model, which equates the temperature distribution of the packaging material within the power semiconductor device to the node temperature on the junction-to-ambient thermal path, includes:

[0015] To obtain a power semiconductor device, with the PN junction inside the device as the starting node and the external environment as the ending node, the temperature of the packaging material is equivalent to a node in the heat conduction path from the PN junction to the external environment.

[0016] The transient thermal impedance of the PN junction to the encapsulation material Z ji ( t The transient thermal resistance of the encapsulation material to the external environment Zia ( t The two are in series, and their sum equals the transient thermal resistance from the PN junction to the external environment. Z ja ( t );

[0017] The average power loss of the device is mentioned above. P loss junction temperature T j ( t ) and ambient temperature T a The formula between them is satisfied:

[0018] ;

[0019] The average power loss of the device P loss The temperature of the encapsulation material T i ( t ) and the ambient temperature T a The formula between them is satisfied:

[0020] ;

[0021] Based on the above formula, a lumped transient temperature model is established, which is expressed as:

[0022] ;

[0023] In the formula, T i ( t ( ) represents the temperature of the encapsulation material; T j ( t ( ) represents the junction temperature; Z ja ( t The transient thermal impedance from the junction to the environment; Z ia ( t ( ) represents the transient thermal resistance of the encapsulation material to the environment; T a The ambient temperature; Z ji ( t ) represents the transient thermal impedance of the junction to the encapsulation material.

[0024] Optionally, substituting the lumped transient temperature model into the linear relationship between on-state voltage drop and junction temperature for parameter substitution to obtain the transient relationship between on-state voltage drop and junction temperature includes:

[0025] The forward voltage drop is linearly related to the junction temperature and the temperature of the packaging material;

[0026] The linear relationship is as follows:

[0027]

[0028] in, V ce ( t ) represents the on-state voltage drop of the device. a , b , c These are the coefficients in the formula;

[0029] Obtain the lumped transient temperature model, substitute it into the linear relationship, and replace the packaging material temperature in the linear relationship with the lumped transient temperature model to obtain the simplified transient relationship between the on-state voltage drop and the junction temperature:

[0030] ;

[0031] in, k 1( t )and k 2( t ) are the slope parameter and intercept parameter of the simplified relation after merging.

[0032] Optionally, in the formula where the on-state voltage drop is linearly related to the junction temperature and the packaging material temperature, when the device used, the driving voltage, and the on-state current remain constant, the coefficients a, b, and c in the formula are constants.

[0033] In the transient relationship between the on-state voltage drop and the junction temperature, the slope parameter... k 1( t It is affected by the components used, the driving voltage, and the conduction current;

[0034] In the transient relationship between the on-state voltage drop and the junction temperature, the intercept parameter k 2( t The performance is affected by the components used, the driving voltage, the conduction current, and the ambient temperature.

[0035] Optionally, in the transient relationship between the on-state voltage drop and the junction temperature, the slope parameter of the transient relationship... k 1( t and the intercept parameter k 2( t With the transient thermal resistance of the junction to the encapsulation material Z ji ( t The transient thermal resistance of the encapsulation material to the environment. Zia ( t The transient thermal impedance of the junction to the environment Z ja ( t )change;

[0036] runtime t After a sufficiently long period of time, such that the device reaches a thermal steady state and the temperature distribution no longer changes, the slope parameter k1(t) and the intercept parameter k2(t) also reach steady-state values.

[0037] Optionally, the device is operated in a DC switching state, the operating time of the device is fixed, the switching frequency or bus voltage is changed, multiple sets of on-state voltage drop data under different junction temperature conditions are measured, and a linear function is used to fit the fixed operating time. t The relational parameters under 0 include:

[0038] The device under test is operated at high frequency, with a constant DC current flowing through it when it is turned on and a constant bus voltage when it is turned off.

[0039] The ambient temperature is kept constant. In the initial state, the internal temperature of the device is equal to the ambient temperature. During operation, the junction temperature of the device and the temperature of the packaging material increase with the increase of operating time.

[0040] The running time of the device is obtained. After the running time reaches a preset fixed running time, the on-state voltage drop and junction temperature of the device are measured to obtain the first on-state voltage drop data.

[0041] The device was then recooled to ambient temperature after measurement.

[0042] Optionally, after the device has been running for a preset fixed duration, the on-state voltage drop and junction temperature of the device are measured. The junction temperature measurement method includes: indirect measurement using the K-coefficient isothermal parameter, or direct measurement using a fiber optic sensor or an infrared thermometer.

[0043] Optionally, after the device has been recooled to ambient temperature following the measurement, the method further includes:

[0044] Fixed runtime t Under the conditions of 0 and fixed on-current, the switching loss power of the device is changed by altering the switching frequency or bus voltage to obtain on-voltage drop data at different junction temperatures.

[0045] Repeated experiments were conducted to obtain multiple sets of on-state voltage drop data. A linear function was then used to fit the relationship between the junction temperature and the on-state voltage drop to obtain the result during the fixed operating time. t The relational parameters under 0; the formula is:

[0046] ;

[0047] In the formula, V ce ( t 0) and T j ( t 0) represents the transient values ​​of the dependent and independent variables of a linear function at a time when the runtime is a specific value t0, and k1(t0) and k2(t0) represent the transient values ​​of the slope parameter k1(t) and the intercept parameter k2(t) at a time when the runtime is a specific value t0.

[0048] Optionally, the step of changing the operating time, fixing the current operating time, changing the switching frequency or bus voltage, and obtaining the on-state voltage drop versus junction temperature relationship parameters under multiple operating times, thereby generating expressions for the slope and intercept parameters of the relationship, includes:

[0049] The device's operating time is changed, and the experiment is repeated while keeping other conditions unchanged. The other conditions include: the device used, the driving voltage, the conduction current, and the ambient temperature.

[0050] Obtain the slope parameters of the transient relation under different runtimes. k 1( t and intercept parameters k 2( t The value of ) k 1( t 1), k 1( t 2)... k 1( t n )and k 2( t 1), k 2( t 2)... k 2( t n ), and obtain k 1( t )and k 2( t As running time t Formulas for the changing law of slope; expressions for the slope parameter and intercept parameter are generated;

[0051] in;

[0052] Wherein, the slope parameter k 1( t ) and the intercept parameter k 2( t As running timet The formula for the law of change is:

[0053] ;

[0054] ;

[0055] In the formula, The thermal time constant is the slope parameter; The thermal time constant of the intercept parameter, m 11 , m 12 , m 21 , m 22 , n 1. n 2 represents the coefficients obtained from the fitting.

[0056] Optionally, by substituting the expressions for the slope parameter and the intercept parameter into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated. Using this transient relationship, the on-state voltage drop and operating time of the device are measured online, and the junction temperature is measured online. This includes:

[0057] Obtain the slope parameter k 1( t ) and the intercept parameter k 2( t The expression for the slope parameter is given. k 1( t ) and the intercept parameter k 2( t Substituting the expression of ) into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated;

[0058] The transient relationship between the on-state voltage drop and junction temperature is as follows:

[0059] ;

[0060] In the formula, It is a natural constant; The thermal time constant is the slope parameter; is the thermal time constant of the intercept parameter.

[0061] This application provides a method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution. It employs a method that equates the temperature distribution of the package material within a power semiconductor device to the node temperature on the junction-to-environment thermal path to establish a lumped transient temperature model. By fitting the transient parameter relationship between on-state voltage drop and junction temperature under different operating durations through switching DC experiments, a transient relationship including an exponential decay term is finally constructed for online junction temperature measurement. This technique can more accurately reflect the dynamic changes in on-state voltage drop and junction temperature under actual operating conditions, providing strong support for the performance monitoring and reliable operation of power semiconductor devices, improving the accuracy of junction temperature measurement under transient conditions, and solving the problem of junction temperature measurement errors caused by package temperature gradients under transient conditions.

[0062] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0063] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0064] Figure 1 This is a flowchart illustrating a test method for the transient relationship between on-state voltage drop and junction temperature, taking into account package temperature distribution, according to an exemplary embodiment.

[0065] Figure 2 This is a schematic diagram illustrating a test method for the transient relationship between on-state voltage drop and junction temperature, taking into account package temperature distribution, according to an exemplary embodiment.

[0066] Figure 3 The waveforms of the on-state current and on-state voltage drop measured during 0.5s of DC operation of a 55A switch according to an exemplary embodiment are shown.

[0067] Figure 4 The graph shows the relationship between on-state voltage drop and junction temperature measured during a 0.5s runtime, according to an exemplary embodiment.

[0068] Figure 5 The above is a graph illustrating the relationship between on-state voltage drop and junction temperature under various operating lengths according to an exemplary embodiment.

[0069] Figure 6 This is a graph illustrating the relationship between the slope parameter and runtime according to an exemplary embodiment.

[0070] Figure 7 This is a graph illustrating the relationship between the intercept parameter and runtime according to an exemplary embodiment.

[0071] Figure 8 The diagram shows the measured on-state voltage drop curve and junction temperature measurement results according to an exemplary embodiment. Detailed Implementation

[0072] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0073] Existing methods for testing the relationship between on-state voltage drop and junction temperature require placing the device under test (DUT) in a temperature chamber or constant-temperature heating stage. The external environment heats the DUT to achieve the same internal temperature as the environment, and then a short current pulse is applied to measure the on-state voltage drop and junction temperature relationship. However, in actual operating conditions, a significant temperature gradient exists within the device, and the temperatures of each layer of the packaging material (solder, bonding wires, etc.) change during transient operation, causing significant changes in the on-state voltage drop and junction temperature relationship characteristics, leading to increased errors in junction temperature calculation. To address these issues, this application provides a method for testing the transient relationship between on-state voltage drop and junction temperature that considers the packaging temperature distribution, thereby resolving the aforementioned problems.

[0074] Reference Figure 1 As shown in one embodiment of this application, a method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution includes:

[0075] S1. Establish a lumped transient temperature model, equating the temperature distribution of the packaging material within the power semiconductor device to the node temperature on the junction-to-ambient thermal path. Substitute the lumped transient temperature model into the linear relationship between on-state voltage drop and junction temperature, and perform parameter substitution to obtain the transient relationship between on-state voltage drop and junction temperature:

[0076] ;

[0077] Among them, the on-state voltage drop of the device V ce ( t ) and junction temperature T j ( t The relationship is a linear function, with the slope parameter of the expression being... k 1( t and intercept parameters k 2( t (Changes over time)

[0078] S2. Operate the device under DC switching conditions, fix the device's operating time, change the switching frequency or bus voltage, and measure multiple sets of on-state voltage drop data under different junction temperature conditions. Use a linear function to fit the data for the fixed operating time. tRelational parameters at 0;

[0079] S3. Change the running time, fix the current running time, change the switching frequency or bus voltage, and obtain the on-state voltage drop and junction temperature relationship parameters under multiple running times, thereby generating expressions for the slope parameter and intercept parameter of the relationship.

[0080] S4. By substituting the expressions for the slope parameter and the intercept parameter into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated. Using this transient relationship, the on-state voltage drop and the running time of the device are measured online, and the junction temperature is measured online.

[0081] Specifically, firstly, the temperature distribution of the packaging material within the power semiconductor device is equivalent to the node temperature on the junction-to-environment thermal path, constructing a transient temperature model of the packaging material. Next, using the method of lumped parameter equivalence and substitution, the complex temperature distribution of the packaging material within the power semiconductor device is simplified, converting numerous dispersed parameters into a few lumped parameters, deriving the transient relationship between the on-state voltage drop and the junction temperature. Then, the power semiconductor device is operated under DC switching conditions. During the experiment, the device's operating time is kept constant, and multiple different junction temperature conditions are created by changing the switching frequency or bus voltage. Under each junction temperature condition, the corresponding on-state voltage drop data is measured. Then, a linear function is used to fit the on-state voltage drop and junction temperature data at a fixed operating time t0, determining the parameters of the relationship at that operating time. Finally, the device's operating time is gradually changed. For each new operating time, the duration is again kept constant, and different junction temperature conditions are obtained again by changing the switching frequency or bus voltage, and the corresponding on-state voltage drop data is measured. Following the method in S2, the parameters of the relationship between on-state voltage drop and junction temperature under this operating time are obtained by fitting a linear function. By changing the operating time multiple times and repeating the above operation, the relationship parameters under multiple operating times are finally obtained, thereby generating a transient relationship between on-state voltage drop and junction temperature. Finally, using the generated transient relationship between on-state voltage drop and junction temperature, online measurement of the power semiconductor device is performed. By measuring the current on-state voltage drop of the device and combining it with the device's operating time, the junction temperature of the device can be calculated in real time and accurately based on the transient relationship.

[0082] It should be noted that the node temperature on the thermal path from the junction to the environment is specifically the heat conduction path between the PN junction inside the device and the external environment, while the temperature of the packaging material is equivalent to the intermediate node temperature between the PN junction inside the device and the external environment.

[0083] The embodiments described above in this application establish a transient temperature model for the packaging material and perform lumped parameter equivalence and replacement, which effectively simplifies the complex packaging temperature distribution problem. It transforms the internal temperature relationship, which is difficult to measure directly, into a form that can be expressed through a mathematical model, obtaining a transient relationship between the on-state voltage drop and the junction temperature. By changing the switching frequency or bus voltage under a fixed operating time, multiple sets of on-state voltage drop data under junction temperature conditions are obtained. A linear function is used to fit the parameters to determine the relationship between the on-state voltage drop and the junction temperature under a specific operating time, obtaining parameters for the on-state voltage drop and junction temperature relationship under multiple operating times. Finally, a transient relationship is generated, enabling the generated transient relationship to more comprehensively and accurately reflect the performance changes of the device under different operating times and junction temperature conditions, enhancing the applicability and accuracy of the model. Based on the generated transient relationship, online measurement of the on-state voltage drop and junction temperature of power semiconductor devices can be achieved. By correcting the relationship between the on-state voltage drop and junction temperature using transient parameters, the junction temperature measurement error caused by the packaging temperature gradient under transient operating conditions is solved, improving the junction temperature measurement accuracy.

[0084] In some specific embodiments of this application, the establishment of a lumped transient temperature model, which equates the temperature distribution of the packaging material within the power semiconductor device to the node temperature on the junction-to-ambient thermal path, includes:

[0085] To obtain power semiconductor devices, the PN junction inside the device is taken as the starting node and the external environment is taken as the ending node. The temperature of the packaging material is equivalent to a node in the heat conduction path from the PN junction to the external environment.

[0086] Transient thermal resistance from PN junction to encapsulation material Z ji ( t ), and the transient thermal resistance of the encapsulation material to the external environment. Z ia ( t The two are in series, and their sum equals the transient thermal resistance from the PN junction to the external environment. Z ja ( t ).

[0087] Among them, the average power loss of the device P loss junction temperature T j ( t ) and ambient temperature T a The formula between them is satisfied:

[0088] ;

[0089] Average power loss of the device P loss Encapsulation material temperatureT i ( t ) and ambient temperature T a The formula between them is satisfied:

[0090] ;

[0091] Based on the above formulas, a lumped transient temperature model is established, and the temperature of the encapsulation material can be expressed as:

[0092] ;

[0093] In the formula, T i ( t ( ) represents the temperature of the encapsulation material; T j ( t ( ) represents the junction temperature; Z ja ( t The transient thermal impedance from the junction to the environment; Z ia ( t ( ) represents the transient thermal resistance of the encapsulation material to the environment; T a The ambient temperature; Z ji ( t ) represents the transient thermal impedance of the junction to the encapsulation material.

[0094] It should be noted that the lumped transient temperature model, i.e. the temperature of the encapsulation material, is used to characterize the overall equivalent temperature of the encapsulation material.

[0095] The embodiments described above in this application establish a lumped transient temperature model, starting with the internal PN junction of the power semiconductor device and ending with the external environment, and using the equivalent temperature of the packaging material. This model establishes the series relationship of transient thermal impedance from the junction to the packaging material and from the packaging material to the external environment, as well as its correlation with the transient thermal impedance from the junction to the environment. This allows for accurate analysis and prediction of transient temperature changes of power semiconductor devices under different operating conditions, providing a basis for solving problems in device thermal design, reliability assessment, and optimization.

[0096] In this approach, the temperature of the encapsulation material is equated to a node in the thermal path from the PN junction to the environment. Specifically, the starting node is the PN junction inside the device, and the ending node is the external environment. The temperature of the encapsulation material is considered an intermediate node in the thermal path from the PN junction to the environment. The complete heat conduction path is "starting from the PN junction, proceeding to the encapsulation material as the intermediate node, and finally ending at the external environment," with the encapsulation material serving only as an intermediate link in the thermal path.

[0097] In some specific embodiments of this application, the method of substituting the lumped transient temperature model into the linear relationship between on-state voltage drop and junction temperature to obtain the transient relationship between on-state voltage drop and junction temperature includes:

[0098] The forward voltage drop is linearly related to the junction temperature and the temperature of the packaging material;

[0099] The linear relationship is:

[0100] ;

[0101] in, V ce ( t ) represents the on-state voltage drop of the device. a , b , c These are the coefficients in the formula;

[0102] Obtain the lumped transient temperature model, substitute it into the linear relationship, and replace the packaging material temperature in the linear relationship with the lumped transient temperature model to obtain the simplified transient relationship between the on-state voltage drop and the junction temperature:

[0103] ;

[0104] in, k 1( t )and k 2( t ) represents the slope parameter and intercept parameter of the simplified relation after merging.

[0105] It should be noted that in the experiment, only the slope parameter after merging is needed. k 1( t and intercept parameters k 2( t Extraction is performed without needing to obtain [the necessary information]. a , b , c , Z ji ( t ), Z ia ( t ), Z ja ( t The specific values ​​of variables such as )

[0106] Specifically, refer to Figure 2As shown, the transient temperature model is first obtained to determine that the on-state voltage drop is linearly related to the junction temperature and the temperature of the encapsulation material, and the linear relationship is given. Then, the transient temperature model is substituted into the linear relationship, and the temperature of the encapsulation material is equivalently replaced by the lumped parameter transient temperature model to finally obtain the transient relationship between the on-state voltage drop and the junction temperature.

[0107] The embodiments described above in this application transform the complex linear relationship between on-state voltage drop and junction temperature and packaging material temperature into one that only requires extracting the combined parameters by equivalently replacing the packaging material temperature with lumped parameters. k 1( t )and k 2( t By establishing the transient relationship between conduction voltage drop and junction temperature, and accurately establishing the dynamic relationship between conduction voltage drop and junction temperature, only the combined parameters need to be extracted during the experiment. k 1( t )and k 2( t This eliminates the need to obtain specific values ​​for numerous other variables, simplifies the experimental process, avoids the tedious process of obtaining specific values ​​for multiple intermediate variables, and reduces experimental costs and operational difficulty.

[0108] In some specific embodiments of this application, in the linear relationship between on-state voltage drop and junction temperature and packaging material temperature, when the device used, drive voltage, and on-state current remain constant, the coefficients a, b, and c in the formula are constants; wherein, in the simplified transient relationship between on-state voltage drop and junction temperature, the slope parameter... k 1( t The voltage drop is affected by the components used, the driving voltage, and the on-current; in the simplified transient relationship between the on-state voltage drop and the junction temperature, the intercept parameter... k 2( t The performance is affected by the components used, the driving voltage, the conduction current, and the ambient temperature.

[0109] Specifically, when the components used, the driving voltage, and the on-current remain constant, the coefficient... a , b , c It is a constant; transient thermal impedance Z ji ( t ), Z ia ( t )and Z ja ( t It is only related to the material properties of the device itself and is not affected by changes in other parameters; the simplified relational parameters are combined. k 1( t )for a , b ,Z ia ( t ), Z ja ( t The operation combination is therefore affected by the devices used, the driving voltage, and the conduction current; the simplified relational parameters are combined. k 2( t )for b , c , Z ji ( t ), Z ja ( t ), T a The operation combination is therefore affected not only by the devices used, the driving voltage and the conduction current, but also by the ambient temperature.

[0110] The above embodiments of this application limit the scope of application of the formula proposed in this application, avoiding errors caused by using experimentally obtained formulas to calculate junction temperature under inappropriate conditions. By controlling key factors such as device model, electrical conditions (drive voltage, conduction current) and ambient temperature, the slope parameter is ensured. k 1( t and intercept parameters k 2( t The time-varying characteristics of the junction temperature prediction model are greatly simplified, improving the accuracy, repeatability and operability of transient junction temperature testing and prediction, and providing a basis for the thermal reliability assessment of devices.

[0111] For example, the conditions such as the devices used, drive voltage, on-current, and ambient temperature must remain consistent during parameter testing and subsequent actual junction temperature measurements. If the conditions of the device under test, drive voltage, on-current, and ambient temperature change in the actual application scenario, the relationship needs to be retested according to the changed actual conditions.

[0112] In some specific embodiments of this application, the transient relationship between on-state voltage drop and junction temperature is expressed as follows:

[0113] ;

[0114] transient relational slope parameter k 1( t and intercept parameters k 2( t The transient thermal resistance of the junction to the encapsulation material is... Z ji ( t Transient thermal resistance of encapsulation material to the environmentZ ia ( t Transient thermal impedance of junction to environment Z ja ( t Changes during runtime t After a sufficiently long period, allowing the device to reach thermal steady state and the temperature distribution to no longer change, the slope parameter... k 1 (t) and intercept parameter k 2 (t) It reaches a steady-state value.

[0115] The above embodiments of this application modify the slope parameter in the transient relationship between on-state voltage drop and junction temperature. k 1 (t) and intercept parameter k 2 (t) Set to vary with transient thermal resistance Z ji ( t ), Z ia ( t )and Z ja ( t The changes fully consider the influence of the package temperature distribution, and can accurately reflect the relationship between the on-state voltage drop and the junction temperature of the device under different thermal states; when the running time is long enough for the device to reach thermal steady state, the parameters reach steady state values, improving the accuracy of the evaluation of the relationship between the on-state voltage drop and the junction temperature of the device, and improving the accuracy of the test results.

[0116] In some specific embodiments of this application, for devices operating in DC switching mode, the switching frequency or bus voltage is varied while the device's operating time is fixed. Multiple sets of on-state voltage drop data are measured under different junction temperature conditions, and a linear function is used to fit the data during the fixed operating time. t The relational parameters with a length of 0 include:

[0117] The device under test is subjected to high-frequency switching operation, with a constant DC current flowing through it when turned on and a constant bus voltage when turned off. The ambient temperature is kept constant. Initially, the internal temperature of the device is equal to the ambient temperature. During operation, the junction temperature and the temperature of the packaging material increase with the increase of the operating time. The operating time of the device is acquired. After the operating time reaches the preset fixed operating time, the forward voltage drop and junction temperature of the device are measured to obtain the forward voltage drop data. The device is then cooled back to the ambient temperature after measurement.

[0118] Specifically, the device under test is placed in a high-frequency switching operation state. During the turn-on phase, a constant DC current flows through the device, and during the turn-off phase, the device is subjected to a constant bus voltage. The ambient temperature is kept stable. Initially, the internal temperature of the device is equal to the ambient temperature. As the operation time progresses, the junction temperature of the device and the temperature of the packaging material gradually increase. When the operation time reaches a preset fixed duration, the on-state voltage drop and junction temperature of the device are measured to obtain a set of on-state voltage drop data. Then, the measured device is cooled to the ambient temperature for subsequent measurements under different conditions.

[0119] The embodiments described above in this application, by placing the device under test in an environment with a high-frequency switch, a constant DC current, and a constant bus voltage, while maintaining a constant ambient temperature, can precisely control experimental conditions, causing the junction temperature and packaging material temperature of the device to change systematically with operating time. After a fixed operating time, the on-state voltage drop and junction temperature are measured to obtain accurate data under specific conditions, providing parameters for fitting the relational equation under a fixed operating time using a linear function. Finally, the measured device is cooled to ambient temperature, ensuring consistent starting conditions for each measurement, reducing experimental errors, and improving the accuracy and repeatability of experimental data.

[0120] In some specific embodiments of this application, after the device has been running for a preset fixed duration, the on-state voltage drop and junction temperature of the device are measured. The junction temperature measurement method includes: indirect measurement using isothermal parameters of the K coefficient, and direct measurement using a fiber optic sensor or an infrared thermometer.

[0121] It should be noted that the measurement methods are not limited to those mentioned above.

[0122] In some specific embodiments of this application, after the device has been recooled to ambient temperature following measurement, the following steps are also included:

[0123] Fixed runtime t Under the conditions of 0 and fixed on-current, the switching power loss of the device is changed by altering the switching frequency or bus voltage, and on-voltage drop data at different junction temperatures are obtained.

[0124] Repeated experiments were conducted to obtain multiple sets of on-state voltage drop data. The relationship between junction temperature and on-state voltage drop was fitted using a linear function to obtain the result under a fixed operating time. t The relational parameters under 0; the formula is:

[0125] ;

[0126] In the formula, V ce ( t 0) and T j ( t0) represents the transient values ​​of the dependent and independent variables of a linear function at a time when the runtime is a specific value t0, and k1(t0) and k2(t0) represent the transient values ​​of the slope parameter k1(t) and the intercept parameter k2(t) at a time when the runtime is a specific value t0.

[0127] In the embodiments described above, after measuring the device and cooling it to ambient temperature, the operating time and conduction current are fixed. The switching power loss is adjusted by changing the switching frequency or bus voltage to obtain conduction voltage drop data at different junction temperatures. After repeating the experiment to obtain multiple sets of data, a linear function is used for fitting. This can effectively control variables, eliminate interference from operating time and conduction current, and accurately explore the influence of changes in switching frequency or bus voltage on the device junction temperature and conduction voltage drop. Fitting multiple sets of data can improve the accuracy of the relational parameters and the accuracy of the experiment.

[0128] In some specific embodiments of this application, for changing the operating time, fixing the current operating time, changing the switching frequency or bus voltage, obtaining the on-state voltage drop and junction temperature relationship parameters under multiple operating times, thereby generating expressions for the slope parameter and intercept parameter of the relationship, including:

[0129] Change the device's operating time, and repeat the experiment while keeping other conditions constant. Other conditions include: the device used, the drive voltage, the on-state current, and the ambient temperature.

[0130] Obtain the slope parameters of the transient relational parameters under different runtimes. k 1( t and intercept parameters k 2( t The value of ) k 1( t 1), k 1( t 2)... k 1( t n )and k 2( t 1), k 2( t 2)... k 2( t n ), and obtain k 1( t )and k 2( t As running time t Formulas for the changing patterns; expressions for generating slope and intercept parameters.

[0131] Specifically, to obtain the transient relationship between on-state voltage drop and junction temperature, the device operating time is first changed. When the current operating time is fixed, other conditions such as the device used, drive voltage, on-state current, and ambient temperature are kept constant. Then, the values ​​of the slope parameter k1(t) and intercept parameter k2(t) in the transient relationship parameters under different operating times are obtained, and the formulas for the variation of k1(t) and k2(t) with operating time t are obtained. Based on these variation formulas, the transient relationship between on-state voltage drop and junction temperature is substituted into the transient relationship between on-state voltage drop and junction temperature, thereby obtaining the transient relationship between on-state voltage drop and junction temperature.

[0132] Among them, the slope parameter k 1( t ) and intercept parameter k 2( t As running time t The formula for the law of change is:

[0133] ;

[0134] ;

[0135] in, The thermal time constant is the slope parameter; The thermal time constant is the intercept parameter; m 11 , m 12 , m 21 , m 22 , n 1. n 2 represents the coefficients obtained from the fitting;

[0136] In some specific embodiments of this application, by substituting the expressions for the slope parameter and the intercept parameter into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated. Using this transient relationship, the on-state voltage drop and operating time of the device are measured online, and the junction temperature is measured online, including:

[0137] Obtain slope parameters k 1( t ) and intercept parameter k 2( t The expression for ) and the slope parameter k 1( t ) and intercept parameter k 2( t Substituting the expression of ) into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated;

[0138] The transient relationship between the on-state voltage drop and the junction temperature is as follows:

[0139] ;

[0140] In the formula, It is a natural constant; The thermal time constant is the slope parameter; is the thermal time constant of the intercept parameter.

[0141] The embodiments described above in this application determine the key parameters in the relationship between on-state voltage drop and junction temperature under different operating lengths, namely the slope parameter and intercept parameter, and generate a transient relationship between on-state voltage drop and junction temperature. This helps to more accurately grasp the change of on-state voltage drop with junction temperature under different operating lengths, effectively improve the performance evaluation and optimization design of the device, and enhance the reliability and stability of operation.

[0142] In this application, specific tests are required for different devices, drive voltages, conduction currents, and ambient temperature conditions, depending on the actual needs of the converter.

[0143] The preferred features in the above embodiments can be used individually in any embodiment, or in any combination thereof, provided they do not conflict with each other. Furthermore, parts not described in detail in the embodiments can be implemented using existing technologies.

[0144] The following examples and comparative examples will be used to further illustrate this application in order to better understand the above-mentioned technical solutions. It should be understood that the following are only some examples and are not intended to limit this application.

[0145] Application Example 1:

[0146] The device under test (DUT) was operated in a 55A switching DC mode for a given duration of 0.5s and a switching frequency of 2kHz. The on-state current and on-state voltage drop of the device during this process are as follows: Figure 3 As shown. At this time, the on-state voltage drop of the device is 1.507V. In addition, the junction temperature of the device under test is 53.8℃, which is measured by the K coefficient method. This is a set of on-state voltage drop and junction temperature data.

[0147] The experiment was repeated with the switching frequency changed to 2kHz, 5kHz, 8kHz, and 10kHz while maintaining a runtime of 0.5s. Multiple sets of on-state voltage drop and junction temperature data were obtained, and the on-state voltage drop-junction temperature relationship curves are plotted as follows. Figure 4 As shown, the curve with a running time of 0.5s obtained by fitting has a slope of 0.00099V / ℃ and an intercept of 1.45361V.

[0148] By setting multiple different runtime values ​​and repeating the above experiment, multiple on-state voltage drop-junction temperature relationship curves under different heating times were obtained. The obtained curves and their fitted slopes and intercepts are as follows: Figure 5 As shown.

[0149] Based on the above experimental results, plot the slope parameters. k 1( t A curve that changes over time, such as Figure 6 As shown;

[0150] Fitting the proposed relation, we obtain:

[0151] ;

[0152] Plotting intercept parameters k 2( t A curve that changes over time, such as Figure 7 As shown:

[0153] Fitting the proposed relation, we obtain:

[0154]

[0155] In summary, the relationship between on-state voltage drop and junction temperature is obtained as follows:

[0156]

[0157] Under actual operating conditions, using the above relationship to measure the junction temperature, the on-state voltage drop of the device under test and the predicted junction temperature change over time are as follows: Figure 8 As shown in the figure, the temperature measurement results show that during the 5-second transient operation, the junction temperature error measured using the existing steady-state relationship is nearly 20℃, while the maximum error of the junction temperature calculated using the proposed transient relationship is within 5℃. Figure 8 It is evident that, compared with traditional methods that do not consider the transient temperature distribution of the package, the relationship proposed in this application can more accurately predict the junction temperature of the device under test.

[0158] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A method for testing transient relationship between on-state voltage drop and junction temperature considering package temperature distribution, characterized in that, include: A lumped transient temperature model is established, which equates the temperature distribution of the packaging material within the power semiconductor device to the node temperature on the junction-to-ambient thermal path. The lumped transient temperature model is then substituted into the linear relationship between on-state voltage drop and junction temperature for parameter replacement, yielding the transient relationship between on-state voltage drop and junction temperature. ； Wherein, the on-voltage drop of the device V ce ( t ) is a linear function of the junction temperature T j ( t ), the slope parameter k 1( t ) and the intercept parameter k 2( t ) vary with time; In the switch DC state, the device is operated, the running time of the device is fixed, the switch frequency or bus voltage is changed, the conduction voltage drop data under multiple different junction temperature conditions are measured, and the relationship parameters under the fixed running time are fitted by using a first function t 0. By changing the operating time, fixing the current operating time, and changing the switching frequency or bus voltage, the relationship parameters between the on-state voltage drop and junction temperature under multiple operating times are obtained, thereby generating expressions for the slope parameter and intercept parameter of the relationship. By substituting the expressions for the slope parameter and the intercept parameter into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated. Using this transient relationship between the on-state voltage drop and the junction temperature, the on-state voltage drop and the operating time of the device are measured online, and the junction temperature is measured online.

2. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 1, characterized in that, The establishment of the lumped transient temperature model, which equates the temperature distribution of the packaging material within the power semiconductor device to the node temperature on the junction-to-ambient thermal path, includes: To obtain a power semiconductor device, with the PN junction inside the device as the starting node and the external environment as the ending node, the temperature of the packaging material is equivalent to a node in the heat conduction path from the PN junction to the external environment. The transient thermal impedance of the PN junction to the encapsulation material Z ji ( t ), and the transient thermal resistance of the encapsulation material to the external environment. Z ia ( t The two are in series, and their sum equals the transient thermal resistance from the PN junction to the external environment. Z ja ( t ); The average power loss of the device is mentioned above. P loss junction temperature T j ( t ) and ambient temperature T a The formula between them is satisfied: ； The average power loss of the device P loss The temperature of the encapsulation material T i ( t ) and the ambient temperature T a The formula between them is satisfied: ； Based on the above formula, a lumped transient temperature model is established, which is expressed as: ； In the formula, T i ( t ( ) represents the temperature of the encapsulation material; T j ( t ( ) represents the junction temperature; Z ja ( t The transient thermal impedance from the junction to the environment; Z ia ( t ( ) represents the transient thermal resistance of the encapsulation material to the environment; T a Ambient temperature; Z ji ( t ) represents the transient thermal resistance of the junction to the encapsulation material.

3. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 2, characterized in that, The step of substituting the lumped transient temperature model into the linear relationship between on-state voltage drop and junction temperature to obtain the transient relationship between on-state voltage drop and junction temperature includes: The forward voltage drop is linearly related to the junction temperature and the temperature of the packaging material, and the linear relationship is expressed as follows: ； in, V ce ( t ) represents the on-state voltage drop of the device. a , b , c These are the coefficients in the formula; Obtain the lumped transient temperature model, substitute it into the linear relationship, and replace the packaging material temperature in the linear relationship with the lumped transient temperature model to obtain the simplified transient relationship between the on-state voltage drop and the junction temperature: ； in, k 1( t )and k 2( t ) are the slope parameter and intercept parameter of the simplified relation after merging.

4. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 3, characterized in that, In the formula stating that the on-state voltage drop is linearly related to the junction temperature and the packaging material temperature, when the device used, the driving voltage, and the on-state current remain constant, the coefficients of the formula are... a , b , c It is a constant; In the transient relationship between the on-state voltage drop and the junction temperature, the slope parameter... k 1( t It is affected by the components used, the driving voltage, and the conduction current; In the transient relationship between the on-state voltage drop and the junction temperature, the intercept parameter k 2( t The performance is affected by the components used, the driving voltage, the conduction current, and the ambient temperature.

5. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 3, characterized in that, In the transient relationship between the on-state voltage drop and the junction temperature, the slope parameter of the transient relationship... k 1( t and the intercept parameter k 2( t With the transient thermal resistance of the junction to the encapsulation material Z ji ( t The transient thermal resistance of the encapsulation material to the environment. Z ia ( t The transient thermal impedance of the junction to the environment Z ja ( t Changes during runtime t The slope parameter is set long enough so that the device reaches thermal stability and the temperature distribution no longer changes. k 1 (t) and the intercept parameter k 2 (t) It reaches a steady-state value.

6. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 1, characterized in that, The device is operated in a DC switching state. The operating time of the device is fixed, but the switching frequency or bus voltage is varied. Multiple sets of on-state voltage drop data are measured under different junction temperature conditions. A linear function is used to fit the data at a fixed operating time. t The relational parameters under 0 include: The device under test is operated at high frequency, with a constant DC current flowing through it when it is turned on and a constant bus voltage when it is turned off. The ambient temperature is kept constant. In the initial state, the internal temperature of the device is equal to the ambient temperature. During operation, the junction temperature of the device and the temperature of the packaging material increase with the increase of the operating time. The running time of the device is obtained. After the running time reaches a preset fixed running time, the on-state voltage drop and junction temperature of the device are measured to obtain the first on-state voltage drop data. The device was then recooled to ambient temperature after measurement.

7. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 6, characterized in that, After the device has been running for a preset fixed duration, the on-state voltage drop and junction temperature of the device are measured. The junction temperature measurement methods include: indirect measurement using isothermal parameters with a K coefficient, and direct measurement using a fiber optic sensor or an infrared thermometer.

8. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 7, characterized in that, After the device is recooled to ambient temperature following the measurement, the method further includes: Fixed runtime t Under the conditions of 0 and fixed on-current, the switching loss power of the device is changed by altering the switching frequency or bus voltage to obtain on-voltage drop data at different junction temperatures. Repeated experiments were conducted to obtain multiple sets of on-state voltage drop data. A linear function was then used to fit the relationship between the junction temperature and the on-state voltage drop to obtain the result during the fixed operating time. t The relational parameters under 0; the formula is: ； In the formula, V ce ( t 0) and T j ( t 0) represents the transient values ​​of the dependent and independent variables of a linear function at a time when the runtime is a specific value t0, and k1(t0) and k2(t0) represent the transient values ​​of the slope parameter k1(t) and the intercept parameter k2(t) at a time when the runtime is a specific value t0.

9. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 1, characterized in that, The process involves changing the operating time, fixing the current operating time, changing the switching frequency or bus voltage, and obtaining the on-state voltage drop versus junction temperature relationship parameters under multiple operating times. This generates expressions for the slope and intercept parameters of the relationship, including: The device's operating time is changed, and the experiment is repeated while keeping other conditions constant. The other conditions include: the device used, the driving voltage, the on-state current, and the ambient temperature. Obtain the slope parameters of the transient relation under different runtimes. k 1( t and intercept parameters k 2( t The value of ) k 1( t 1), k 1( t 2)... k 1( t n )and k 2( t 1), k 2( t 2)... k 2( t n ), and obtain k 1( t )and k 2( t As running time t The formula for the change law is used to generate expressions for the slope parameter and intercept parameter; Wherein, the slope parameter k 1( t ) and the intercept parameter k 2( t As running time t The formula for the law of change is: ； ； In the formula, The thermal time constant is the slope parameter; The thermal time constant of the intercept parameter, m 11 , m 12 , m 21 , m 22 , n 1. n 2 represents the coefficients obtained from the fitting.

10. The method for testing the transient relationship between on-state voltage drop and junction temperature considering package temperature distribution according to claim 9, characterized in that, The process involves substituting the expressions for the slope and intercept parameters into the transient relationship between the on-state voltage drop and the junction temperature to generate a transient relationship between the on-state voltage drop and the junction temperature. Using this transient relationship, the on-state voltage drop and operating time of the device are measured online, and the junction temperature is measured online. This includes: Obtain the slope parameter k 1( t ) and the intercept parameter k 2( t The expression for the slope parameter is given. k 1( t ) and the intercept parameter k 2( t Substituting the expression of ) into the transient relationship between the on-state voltage drop and the junction temperature, a transient relationship between the on-state voltage drop and the junction temperature is generated; The transient relationship between the on-state voltage drop and junction temperature is as follows: ； In the formula, It is a natural constant; The thermal time constant is the slope parameter; is the thermal time constant of the intercept parameter.

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