Power device junction temperature accurate detection method, system and product

Abstract

The invention relates to the field of semiconductor device testing, and discloses a power device junction temperature accurate detection method and system and a product, and the method comprises the steps: S1, obtaining a relation curve between the conduction voltage drop and the junction temperature of a tested power device; s2, the tested power device is started to operate, the power of the tested power device is obtained after steady-state operation, and then the tested power device stops operating; s3, performing a conduction voltage drop test on the tested power device to obtain a conduction voltage drop test value, and reversely deducing a junction temperature test value through the conduction voltage drop test value and the relation curve of the conduction voltage drop and the junction temperature; s4, obtaining an instantaneous temperature difference compensation value through the RC thermal resistance parameter, the test time interval and the power of the tested power device; and S5, adding the junction temperature test value and the instantaneous temperature difference compensation value, and calculating to obtain the accurate junction temperature of the tested power device during operation. According to the application, temperature compensation is carried out on the junction temperature test value measured by the thermo-electric parameter method, so that the problem that the real junction temperature cannot be accurately detected when the power device operates by the thermo-electric parameter method is solved.

Description

Technical Field

[0001] This application relates to the field of semiconductor device performance testing, specifically to a method, system, and product for accurately detecting the junction temperature of power devices. Background Technology

[0002] Junction temperature is a core parameter that determines the electrical performance, operational reliability, and lifespan of semiconductor power devices. Statistics show that for every 10°C increase in junction temperature, the effective lifespan of a power device may decrease by 30% to 50%. Therefore, accurate measurement of junction temperature is crucial for monitoring the health status of devices and thus improving their operational reliability.

[0003] Currently, junction temperature measurement methods for power devices can be mainly divided into four categories: direct contact methods, optical methods, thermal network model methods, and thermistor electrical parameter methods. Direct contact and optical methods require damaging the original packaging structure of the device, making them difficult to apply to mass-produced devices. Thermal network model methods require pre-training of the thermal resistance network model and extensive data iteration calculations, making them cumbersome and complex, significantly limiting the response speed of junction temperature testing. Different product models require retraining of the model and preparation of data. Thermistor electrical parameter methods, on the other hand, utilize the inherent correlation between the electrical parameters of power devices and junction temperature. By measuring the electrical parameters, the junction temperature can be inferred, without damaging the packaging, and with a fast measurement response speed. This is currently the most commonly used junction temperature detection method in mass production testing and practical applications.

[0004] Thermistor-based junction temperature measurement typically involves immediately switching the measurement to the device after stress is applied. The electrical parameters of the device under its current state are measured, and the corresponding junction temperature is deduced from this measurement. This measured junction temperature is then used as the junction temperature at the time of stress application. However, in practical applications, a time interval inevitably occurs between the stress application and the subsequent switching back to electrical parameter measurement. Furthermore, after the device loses power input, the junction temperature T... j A precipitous drop will occur within an extremely short time (on the μs level), such as... Figure 1 As shown. Therefore, the junction temperature measured by the thermistor method is not the actual junction temperature during device operation, but a relatively low value that deviates to the actual junction temperature, which greatly affects the accuracy of evaluating the output capability and operational reliability of power devices. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the prior art and provide a method, system and product for accurate detection of junction temperature of power devices. The transient temperature difference is calculated based on the power and RC thermal resistance parameters of the power device, thereby compensating for the junction temperature test value measured by the thermistor parameter method, so as to solve the problem that the thermistor parameter method cannot accurately detect the actual junction temperature of the power device during operation.

[0006] Firstly, this application provides a method for accurately detecting the junction temperature of a power device, the technical solution of which includes the following steps; S1, calibrate the relationship curve between the on-state voltage drop and junction temperature of the power device under test; S2, the power device under test starts running. After the power device under test is running in steady state, the power P of the power device under test is acquired. L Then the power device under test stops operating; S3, obtain the test time interval ∆t, and perform a forward voltage drop test on the power device under test to obtain the forward voltage drop test value V. cesat Through the conduction voltage drop test value V cesat The junction temperature test value T can be derived from the relationship curve between on-state voltage drop and junction temperature. j（Vcesat） ; S4, by obtaining the RC thermal resistance parameter of the power device under test, the test time interval ∆t, and the power P of the power device under test. L The instantaneous temperature difference compensation value T of the power device under test is calculated. ∆j ; S5. Add the junction temperature test value and the instantaneous temperature difference compensation value to calculate the accurate junction temperature T of the power device under test during operation. j There is T j =T j(Vcesat) +T ∆j .

[0007] By adopting the above technical solution, when the power device under test reaches its junction temperature in steady-state operation, the power of the power device under test is calculated. Then, the junction temperature of the power device under test is obtained by measuring the on-state voltage drop and the relationship curve between the on-state voltage drop and the junction temperature using the thermistor parameter method. The instantaneous temperature difference compensation value is then calculated using the RC thermal resistance parameter of the power device under test, the test time interval ∆t, and the measured power of the power device under test. The junction temperature test value is compensated by the instantaneous temperature difference compensation value. The accurate junction temperature data obtained is more consistent with the actual junction temperature reached by the power device under test in steady-state operation than the junction temperature test value obtained directly using the thermistor parameter method, which significantly improves the accuracy of the test.

[0008] Preferably, the specific steps of S1 include: S101, heat the power device under test to the target constant test temperature, which is the current junction temperature of the power device under test; S102, apply a small test current to test the on-state voltage drop of the power device under test at a constant test temperature; S103, change the target constant test temperature of the power device under test, repeat step S102, and obtain the corresponding curves of on-state voltage drop and junction temperature under different target constant test temperatures.

[0009] The above technical solution can obtain the correlation curve between the on-state voltage drop and the junction temperature of the target power device under test. This curve can be used to calculate the corresponding junction temperature based on the measured on-state voltage drop when measuring the junction temperature of the power device under test.

[0010] Preferably, in S102, the small test current is 1 / 1000 of the rated operating current value of the power device under test.

[0011] By adopting the above technical solution, it can be ensured that when the on-state voltage drop test is performed on the power device under test at a specific junction temperature, the current and the resulting heat effect are small enough not to affect the junction temperature of the power device under test.

[0012] Preferably, in step S2, the power P of the power device under test is obtained. L The method involves real-time detection of the operating current I of the power device under test. L and voltage V L After the power device under test has been operating in steady state, the power P of the power device under test is calculated using current and voltage. L There is P L =I L *V L .

[0013] By adopting the above technical solution, by detecting the operating current and operating voltage of the power device under test, it is possible to confirm whether the power device under test has entered steady-state operation and accurately calculate the power of the power device under test under steady-state operation. This helps to calculate the instantaneous temperature difference compensation value in the subsequent process, thereby making the results of accurate junction temperature detection more precise.

[0014] Preferably, the test time interval ∆t is obtained by recording the period from when the power device under test stops operating to when the on-state voltage drop V is applied to the power device under test. cesat The test time interval ∆t.

[0015] As a preferred method, the specific method for obtaining the RC thermal resistance parameter of the power device under test is as follows: Obtain the RC transient thermal resistance function Z of a power device of the same model as the power device under test. thjc (t), specifically, can be obtained from the power device's datasheet or by calculating the power device's fourth-order RC thermal resistance function; The specific formula for calculating the fourth-order RC thermal resistance function of power devices is as follows: , In the formula, n represents the order index of the power device thermal network model, used to describe different RC links; Rth is the sub-link thermal resistance, representing the thermal resistance of the structure corresponding to each RC link, describing the heat dissipation resistance of different structures; Cth is the sub-link heat capacity, representing the heat storage capacity of the structure corresponding to each RC link, describing the rate of temperature change of different structures; t is the transient process time variable, used to describe the thermal impedance parameters at different times. Substituting the test time interval ∆t, we have t=∆t. The RC thermal resistance parameter of the power device under test is calculated as the RC transient thermal resistance function Z with respect to the test time interval ∆t. thjc (∆t).

[0016] By adopting the above technical solution, the time-based transient thermal resistance function Z is used. thjc (∆t) and power P L It can accurately describe the dynamic change of internal temperature of the power device under test during the transient change from steady-state operation to shutdown, thereby enabling compensation for the temperature difference generated during the time interval from shutdown to conduction voltage drop test of the power device under test, making the calculation results of instantaneous temperature difference compensation value highly reliable.

[0017] Secondly, the power device junction temperature accurate detection system provided in this application adopts a technical solution including a calibration module for the relationship between on-state voltage drop and junction temperature, a junction temperature detection module, a power measurement module, a timing module, a temperature compensation module, and a data processing module. The on-state voltage drop versus temperature calibration module is used to calibrate the on-state voltage drop versus junction temperature curve of the power device under test. The junction temperature detection module includes a steady-state operation path and a test path. The steady-state operation path controls the steady-state operation or shutdown of the power device under test. After the power device under test stops operating, it switches to the test path to measure the on-state voltage drop V of the power device under test. cesat Perform testing and base the results on the conduction voltage drop test value V. cesat The junction temperature T was analyzed using the on-state voltage drop versus junction temperature curve. j（Vcesat） Perform reverse reasoning; The power measurement module measures the current I of the power device under test during steady-state operation. L and voltage V L To perform testing, the power P of the power device under test is measured at the moment before it ceases operation. L Calculation; The timing module records the test time interval ∆t from when the power device under test stops operating to when the on-state voltage drop test is performed; The temperature compensation module obtains the RC transient thermal resistance function Z of the power device under test based on the test time interval ∆t. thjc(∆t), and through the RC transient thermal resistance function Z thjc (∆t) and power P L Instantaneous temperature difference compensation value T ∆j Calculation; The data processing module will process the junction temperature test value T. j（Vcesat） With instantaneous temperature difference compensation value T ∆j The summation yields the accurate junction temperature T of the power device under test during operation. j .

[0018] Preferably, the power measurement module completes the current I of the power device under test. L and voltage V L After detection, a stop signal for the power device under test is sent to the junction temperature detection module. The steady-state operation path of the junction temperature detection module controls the power device under test to stop operating according to the stop signal and switches to the test path.

[0019] The above technical solution ensures that the current and voltage of the power device under test are recorded before it stops operating, which facilitates the calculation of the instantaneous temperature difference compensation value and provides a clear time and signal node for the power device under test to stop operating.

[0020] Preferably, the timing module starts timing based on the stop signal of the power device under test sent by the power measurement module, and measures the on-state voltage drop V of the power device under test based on the junction temperature detection module. cesat The detection signal stops the timing.

[0021] The above technical solution ensures that the test time interval ∆t measured by the timing module corresponds to the time interval from when the power device under test stops operating to when the on-state voltage drop test is performed, so that the calculation result of the instantaneous temperature difference compensation value can truly reflect the change process of the junction temperature of the power device under test within the time interval.

[0022] Thirdly, this application provides a computer program product, including a computer program or instructions, which enables the computer program or instructions to implement the steps in the above-mentioned method for accurately detecting the junction temperature of power devices.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. This application can describe the actual physical process of junction temperature measurement using the thermistor electrical parameter method, and calculate the compensation for the temperature difference caused by the test time interval during the process, thereby effectively improving the accuracy of junction temperature detection using the thermistor electrical parameter method.

[0024] 2. In the testing of the power device under test in this application, the junction temperature test value is inversely deduced by the on-state voltage drop of the device under test, and the instantaneous temperature difference compensation value is calculated by the power of the device under test and the test time interval. The parameters are obtained accurately and conveniently, which improves the accuracy and response speed of the junction temperature test.

[0025] 3. This application only requires prior acquisition of the relationship curve between the on-state voltage drop and junction temperature of the power device under test. It does not require the derivation or training of junction temperature parameter-related models, nor does it require the storage or iteration of a large amount of data, which reduces the complexity of test preparation and improves test efficiency.

[0026] 4. This application employs non-destructive junction temperature detection, ensuring the integrity of the power device under test and enabling online monitoring and control of the power device under test. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the temperature change curve of the power device; Figure 2 This is a flowchart illustrating a method for accurately detecting the junction temperature of a power device according to an embodiment of this application. Figure 3 This is a schematic diagram of the architecture of a power device junction temperature accurate detection system according to an embodiment of this application; Figure 4 This is a schematic diagram of an exemplary computer device structure in an embodiment of this application. Detailed Implementation

[0028] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of this application.

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that in the optional embodiments of this application, the object information and other related data involved require the permission or consent of the object when the embodiments of this application are applied to specific products or technologies, and the collection, use, and processing of related data must comply with the relevant laws, regulations, and standards of the relevant countries and regions. That is to say, if the embodiments of this application involve data related to the object, it needs to be obtained with the authorization and consent of the object, the authorization and consent of the relevant departments, and in compliance with the relevant laws, regulations, and standards of the country and region. If personal information is involved in the embodiments, the acquisition of all personal information requires the consent of the individual. If sensitive information is involved, the separate consent of the information subject is required, and the embodiments also need to be implemented with the authorization and consent of the object.

[0030] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0031] Please see Figure 2 The present application provides a method for accurately detecting the junction temperature of a power device, which specifically includes the following steps.

[0032] S1 is used to calibrate the relationship curve between the on-state voltage drop and junction temperature of the power device under test.

[0033] The on-state voltage drop versus junction temperature curve is used in subsequent tests to infer the junction temperature from the on-state voltage drop measured by the device under test. Therefore, the accuracy of this on-state voltage drop versus junction temperature curve has a significant impact on the accuracy of the junction temperature measurement. More specifically, the method for obtaining the on-state voltage drop versus junction temperature curve is as follows.

[0034] S101, Heat the power device under test to the target constant test temperature. This heating temperature needs to be maintained for a sufficient time so that the temperature of all parts of the power device, especially the chip temperature, reaches the set target constant test temperature, so that the target constant test temperature can represent the current junction temperature of the power device under test.

[0035] S102, Maintaining the current temperature conditions, apply a small test current to measure the on-state voltage drop of the power device under test at a constant test temperature. To avoid the current heating effect affecting the junction temperature of the device under test, the small test current needs to be sufficiently small. In the embodiments of this application, the small current is 1 / 1000 of the rated operating current value of the power device under test.

[0036] S103, change the target constant test temperature of the power device under test, and repeat step S102 to perform the on-state voltage drop test. The measured on-state voltage drops and the target constant test temperatures (current junction temperatures) form a one-to-one correspondence, thus obtaining the on-state voltage drop versus junction temperature curves at different target constant test temperatures.

[0037] It should be noted that for a specific type of power device, the relationship between its on-state voltage drop and junction temperature is determined by the physical properties of the semiconductor material itself. Therefore, an on-state voltage drop versus junction temperature curve that matches the type of power device can be experimentally calibrated and used as the standard curve for all power devices of the same type.

[0038] S2, the power device under test starts running. After the power device under test is running in steady state, the power P of the power device under test is acquired. L Then the power device under test stops operating.

[0039] Obtain the power P of the power device under test L The method involves real-time detection of the operating current I of the power device under test. L and voltage V L When the current I L and voltage V L If the rate of change is less than a certain threshold and remains within the minimum time requirement, it indicates that the power device under test has achieved steady-state operation, and the junction temperature of the power device under test at this time is the steady-state junction temperature. After confirming the steady-state operation of the power device under test, the power P of the power device under test is calculated by reading the current and voltage values. L There is P L =I L *V L .

[0040] The power P of the power device under test is measured. L Afterwards, the power device under test is stopped to perform a conduction voltage drop test. Stopping the power device under test before performing the conduction voltage drop test with a small current is to obtain a relatively clean measurement environment, eliminating signal interference and self-heating effects from large operating currents, and ensuring that the measured conduction voltage drop signal is true and accurate.

[0041] Meanwhile, after the power device under test stops operating, its junction temperature will drop rapidly within a short period of time. In order to compensate for the temperature difference during this process, it is necessary to calculate the instantaneous temperature difference compensation value of the test time interval ∆t from when the power device under test stops operating to when the on-state voltage drop test is performed. Therefore, the length of this test time interval ∆t needs to be recorded.

[0042] S3, Perform a forward voltage drop test on the power device under test to obtain the forward voltage drop test value V.cesat Through the conduction voltage drop test value V cesat The junction temperature test value T can be derived from the relationship curve between on-state voltage drop and junction temperature. j（Vcesat） .

[0043] It should be noted that the small current value used in the on-state voltage drop test in this step should be consistent with the small current used to obtain the relationship curve between on-state voltage drop and junction temperature in S102, to ensure that the on-state voltage drop test value V is passed. cesat Derive the junction temperature test value T j（Vcesat） The accuracy of the test is ensured. In the embodiments of this application, the small current for the on-state voltage drop test is 1 / 1000 of the rated operating current of the power device under test.

[0044] The junction temperature test value T j（Vcesat） The junction temperature is the temperature after the power device under test stops operating and experiences a temperature drop.

[0045] S4. Obtain the RC thermal resistance parameter of the power device under test, the test time interval ∆t, and the power P of the power device under test. L The instantaneous temperature difference compensation value T of the power device under test is calculated. ∆j The specific method is as follows.

[0046] S401, obtain the RC thermal resistance parameter of the power device under test. It should be noted that this RC thermal resistance parameter is a transient RC thermal resistance function Z with respect to the test time interval ∆t. thjc (∆t).

[0047] During the transient period when the device under test stops working, the cooling process inside the chip is not linear, but rather a dynamic decay process determined by the thermal resistance and thermal capacity of the packaging material. The RC transient thermal resistance function Z... thjc (∆t) is a time-varying function that incorporates the combined effects of thermal capacity (Cth) and thermal resistance (Rth).

[0048] The thermal capacity effect (Cth) specifically refers to the thermal capacity of the chip itself, the bonding material, the casing, and other layers, enabling them to store heat. At the moment of shutdown, the junction temperature does not immediately drop to the case temperature; instead, heat is first transferred from the junction region to adjacent packaging materials, causing their temperature to rise. This process effectively slows down the rate of temperature decrease at the junction. Simultaneously, the thermal resistance effect (Rth) refers to the process by which heat is conducted outwards through the packaging materials, overcoming the thermal resistance of each layer, and ultimately dissipated into the environment. This is illustrated by the RC transient thermal resistance function Z. thjc (∆t) can describe the physical process of temperature drop of the power device under test, thereby accurately calculating the temperature drop value within a short period of ∆t.

[0049] The RC transient thermal resistance function Z of the power device of the same model as the tested power device thjc (t) can be obtained by consulting the datasheet provided by the manufacturer of the power device under test, or by calculating the fourth-order RC thermal resistance function. The specific formula is as follows:

[0050] In the formula, n represents the order index of the thermal network model of the power device under test, used to describe different RC links; Rth is the sub-link thermal resistance, representing the thermal resistance of the structure corresponding to each RC link, describing the heat dissipation resistance of different structures; Cth is the sub-link heat capacity, representing the heat storage capacity of the structure corresponding to each RC link, describing the rate of temperature change of different structures; t is the transient process time variable, used to describe the thermal impedance parameters at different times. Substituting the test time interval ∆t, we have t=∆t. The RC thermal resistance parameter of the power device under test is calculated as the RC transient thermal resistance function Z with respect to the test time interval ∆t. thjc (∆t).

[0051] The use of a fourth-order RC thermal resistance function to calculate the junction temperature of power devices is essentially to achieve an optimal balance between computational complexity and transient thermal response accuracy. The process of chip junction temperature changing with power involves multiple "thermal inertia" stages, such as rapid heating of the chip core, slow heat conduction by the packaging material, and gradual heat accumulation by the heat sink. First-order or second-order RC models can only simulate a coarse change in a single time constant, easily leading to peak temperature prediction errors or slow steady-state temperature convergence. In contrast, the fourth-order RC model, through multiple RC stages, corresponds to the delay characteristics of different thermal paths, more realistically reproducing the entire process from rapid temperature rise to steady state, and can more accurately calculate short-term temperature peaks and long-term temperature trends. Theoretically, the higher the order of the RC model, the higher the model accuracy, but the computational load increases exponentially, which greatly limits practical industrial applications. The fourth-order RC model is the choice in the practical application of this application, satisfying the thermal response accuracy requirements of most consumer electronics and automotive electronics without placing an excessive computational burden on simulation tools or real-time monitoring algorithms.

[0052] S402, based on the power P of the power device under test in S2. L And the obtained test time interval ∆t, for the instantaneous temperature difference compensation value T ∆j Perform the calculation. As shown in the following formula:

[0053]

[0054]

[0055]

[0056]

[0057] S5. Add the junction temperature test value and the instantaneous temperature difference compensation value to calculate the accurate junction temperature T of the power device under test during operation. j There is T j =T j(Vcesat) +T ∆j .

[0058] More specifically, in one embodiment, a standard junction temperature threshold is set for a specific model of the power device under test. If the accurate junction temperature T... j If the calculated result deviates from the standard junction temperature threshold by more than the warning value, it proves that the actual junction temperature of the power device under test or the relationship curve between its on-state voltage drop and junction temperature has deviated from the normal state. It is necessary to check the reliability of the current state of the power device under test, such as whether there is damage or aging, or to verify and adjust the thermal interface of the system in which the power device is located.

[0059] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0060] Please see Figure 3 This application provides an embodiment of a power device junction temperature accurate detection system for testing the power device 7 under test. The system includes a calibration module 1 for the relationship between on-state voltage drop and junction temperature, a junction temperature detection module 2, a power measurement module 3, a timing module 4, a temperature compensation module 5, and a data processing module 6.

[0061] The on-state voltage drop versus temperature calibration module 1 is used to perform on-state voltage drop tests on the power device under test in advance, so as to calculate and record the on-state voltage drop versus junction temperature curve of the power device under test 7.

[0062] The junction temperature detection module 2 includes a steady-state operation path 21 and a test path 22. The steady-state operation path 21 controls the steady-state operation or shutdown of the power device under test 7. After the power device under test 7 stops operating, it switches to the test path to measure the on-state voltage drop V of the power device under test 7. cesat Perform testing and base the results on the conduction voltage drop test value V. cesat The junction temperature T was analyzed using the on-state voltage drop versus junction temperature curve. j（Vcesat） Perform a reverse calculation.

[0063] The power measurement module 3 measures the current I of the power device 7 under test during steady-state operation. L and voltage V L The test is performed to measure the power P of the power device under test 7 just before it stops operating. LThe calculation.

[0064] The timing module 4 is used to record the test time interval ∆t from when the power device under test 7 stops running to when the on-state voltage drop test is performed.

[0065] In one specific embodiment, the power measurement module 3 completes the current I of the power device under test 7. L and voltage V L After detection, a stop signal for the power device under test (7) is sent to the junction temperature detection module 2. The steady-state operation path 21 of the junction temperature detection module 2 controls the power device under test (7) to stop operating based on the stop signal and switches to the test path 22 to perform the on-state voltage drop test. The timing module 4 starts timing based on the stop signal for the power device under test (7) sent by the power measurement module 3, and calculates the on-state voltage drop V based on the test value of the power device under test (V) from the junction temperature detection module 2. cesat The detection signal stops the timing, thereby obtaining the test time interval ∆t.

[0066] In the above embodiment, the power measurement module 3 measures the current I of the power device under test 7. L and voltage V L The rate of change confirms that the power device under test 7 has reached steady-state operation, and the current I is applied after the power device meets the minimum time requirement for steady-state operation. L and voltage V L After the detection is completed, a stop signal is sent, causing the junction temperature detection module 2 to switch to test path 22 to perform subsequent on-state voltage drop testing. This implementation method is highly efficient, enables automated testing, and is suitable for high-speed testing of large batches of power devices 7 under test, applicable to scenarios such as product factory performance testing.

[0067] In another specific embodiment, the power measurement module 3 is connected to an external control signal source. When online performance testing of the power device under test 7 is required, the external control signal source outputs a redundancy switching signal, and the power measurement module 3 measures the current I of the power device under test 7 based on the redundancy switching signal. L and voltage V L The system performs online testing of the power device under test (7) and sends a stop signal after the test is completed. Simultaneously, an external control signal source performs redundancy switching of the backup power device based on the stop signal. The subsequent on-state voltage drop test procedure is the same as in the previous embodiment. This implementation method enables online testing of the power device under test (7) without affecting the overall normal operation of the system.

[0068] Temperature compensation module 5 obtains the RC transient thermal resistance function Z of the power device under test 7 based on the test time interval ∆t. thjc(∆t), and through the RC transient thermal resistance function Z thjc (∆t) and power P L Instantaneous temperature difference compensation value T ∆j The calculation.

[0069] Data processing module 6 will process the junction temperature test value T. j（Vcesat） With instantaneous temperature difference compensation value T ∆j The summation yields the accurate junction temperature T of the power device under test 7 during operation. j .

[0070] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the power device junction temperature accurate detection system described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0071] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0072] This application provides a computer program product, which includes a computer program or instructions that enable the computer program or instructions to implement the steps in the above-described method for accurately detecting the junction temperature of a power device.

[0073] As an exemplary computer device for implementing the aforementioned computer program product, its internal structure diagram can be as follows: Figure 4 As shown. The computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and the database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The computer program is executed by the processor to implement the steps in the aforementioned method for accurately detecting the junction temperature of a power device. The database of the computer device stores the on-state voltage drop versus junction temperature curve data and the RC transient thermal resistance function Z of the power device under test 7. thjc (∆t), test parameters, and test logs. The network interface of this computer device is used to communicate with external terminals via a network connection to input test data and output control signals and test results for the power device under test 7.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for accurately detecting the junction temperature of a power device, characterized in that, Includes the following steps; S1, calibrate the relationship curve between the on-state voltage drop and junction temperature of the power device under test; S2, the power device under test starts running. After the power device under test is running in steady state, the power P of the power device under test is acquired. L Then the power device under test stops operating; S3, obtain the test time interval ∆t, and perform a forward voltage drop test on the power device under test to obtain the forward voltage drop test value V. cesat Through the conduction voltage drop test value V cesat The junction temperature test value T can be derived from the relationship curve between on-state voltage drop and junction temperature. j（Vcesat） ; S4, by obtaining the RC thermal resistance parameter of the power device under test, the test time interval ∆t, and the power P of the power device under test. L The instantaneous temperature difference compensation value T of the power device under test is calculated. ∆j ; S5. Add the junction temperature test value and the instantaneous temperature difference compensation value to calculate the accurate junction temperature T of the power device under test during operation. j There is T j =T j(Vcesat) +T ∆j .

2. The method for accurately detecting the junction temperature of a power device according to claim 1, characterized in that, The specific steps of S1 include: S101, heat the power device under test to the target constant test temperature, which is the current junction temperature of the power device under test; S102, apply a small test current to test the on-state voltage drop of the power device under test at a constant test temperature; S103, change the target constant test temperature of the power device under test, repeat step S102, and obtain the corresponding curves of on-state voltage drop and junction temperature under different target constant test temperatures.

3. The method for accurately detecting the junction temperature of a power device according to claim 2, characterized in that, In S102, the small test current is 1 / 1000 of the rated operating current value of the power device under test.

4. The method for accurately detecting the junction temperature of a power device according to claim 1, characterized in that, In S2, the power P of the power device under test is obtained. L The method involves real-time detection of the operating current I of the power device under test. L and voltage V L After the power device under test has been operating in steady state, the power P of the power device under test is calculated using current and voltage. L There is P L =I L *V L .

5. The method for accurately detecting the junction temperature of a power device according to claim 1, characterized in that, Specifically, the test time interval ∆t is recorded from the time the power device under test stops operating until the on-state voltage drop V is applied to the power device under test. cesat The test time interval ∆t.

6. The method for accurately detecting the junction temperature of a power device according to claim 5, characterized in that, The specific method for obtaining the RC thermal resistance parameters of the power device under test is as follows: Obtain the RC transient thermal resistance function Z of a power device of the same model as the power device under test. thjc (t), specifically, can be obtained from the power device's datasheet or by calculating the power device's fourth-order RC thermal resistance function; The specific formula for calculating the fourth-order RC thermal resistance function of power devices is as follows: ， In the formula, n represents the order index of the power device thermal network model, used to describe different RC links; Rth is the sub-link thermal resistance, representing the thermal resistance of the structure corresponding to each RC link, describing the heat dissipation resistance of different structures; Cth is the sub-link heat capacity, representing the heat storage capacity of the structure corresponding to each RC link, describing the rate of temperature change of different structures; t is the transient process time variable, used to describe the thermal impedance parameters at different times. Substituting the test time interval ∆t, we have t=∆t. The RC thermal resistance parameter of the power device under test is calculated as the RC transient thermal resistance function Z with respect to the test time interval ∆t. thjc (∆t).

7. A system for accurately detecting the junction temperature of power devices, characterized in that, It includes a calibration module for the relationship between on-state voltage drop and junction temperature, a junction temperature detection module, a power measurement module, a timing module, a temperature compensation module, and a data processing module; The on-state voltage drop versus temperature calibration module is used to calculate the on-state voltage drop versus junction temperature curve of the power device under test. The junction temperature detection module includes a steady-state operation path and a test path. The steady-state operation path controls the steady-state operation or shutdown of the power device under test. After the power device under test stops operating, it switches to the test path to measure the on-state voltage drop V of the power device under test. cesat Perform testing and base the results on the conduction voltage drop test value V. cesat The junction temperature T was analyzed using the on-state voltage drop versus junction temperature curve. j（Vcesat） Perform reverse reasoning; The power measurement module measures the current I of the power device under test during steady-state operation. L and voltage V L To perform testing, the power P of the power device under test is measured at the moment before it ceases operation. L Calculation; The timing module records the test time interval ∆t from when the power device under test stops operating to when the on-state voltage drop test is performed; The temperature compensation module obtains the RC transient thermal resistance function Z of the power device under test based on the test time interval ∆t. thjc (∆t), and through the RC transient thermal resistance function Z thjc (∆t) and power P L Instantaneous temperature difference compensation value T ∆j Calculation; The data processing module will process the junction temperature test value T. j（Vcesat） With instantaneous temperature difference compensation value T ∆j The summation yields the accurate junction temperature T of the power device under test during operation. j .

8. The power device junction temperature accurate detection system according to claim 7, characterized in that, The power measurement module completes the current I of the power device under test. L and voltage V L After detection, a stop signal for the power device under test is sent to the junction temperature detection module. The steady-state operation path of the junction temperature detection module controls the power device under test to stop operating according to the stop signal and switches to the test path.

9. The power device junction temperature accurate detection system according to claim 8, characterized in that, The timing module starts timing based on the stop signal of the power device under test sent by the power measurement module, and measures the on-state voltage drop V of the power device under test based on the junction temperature detection module. cesat The detection signal stops the timing.

10. A computer program product, characterized in that, The computer program product includes a computer program or instructions that enable the computer program or instructions to perform the steps in the power device junction temperature accurate detection method according to any one of claims 1 to 6.

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