Power device on-state resistance measurement circuit and junction temperature measurement method and system

Abstract

The present invention discloses a power device on-resistance measurement circuit and a junction temperature measurement method and system. The on-resistance measurement module solves the contradiction between the wide range and high precision of the measuring equipment, while ensuring the high-speed response capability of the measurement, and realizing high-precision and high-response on-resistance measurement; the junction temperature model building module obtains data of thermal parameters such as on-resistance and load current through a single pulse calibration link, and then establishes a junction temperature online measurement model through a fully connected neural network prediction model; the junction temperature online measurement module collects on-resistance and load current in real time, and inputs them into the junction temperature online measurement model, and displays the junction temperature fluctuation in real time through the host computer interface, realizing high-precision junction temperature online real-time measurement. The system can truly and accurately reflect the junction temperature fluctuation of SiC MOSFET power modules, provide an important basis for reliability assessment, life prediction and health management of SiC MOSFET power modules, and is conducive to ensuring the reliable operation of power electronic systems.

Description

Technical Field

[0001] The present invention relates to the field of reliability of core power devices in power electronic systems, and in particular to a power device on-resistance measurement circuit and a junction temperature measurement method and system. Background Art

[0002] As a new generation of wide-bandgap semiconductor power devices, SiC-MOSFET power modules offer advantages such as high voltage, high frequency, and high power density, making them stand out among existing power devices and possessing broad application prospects. However, as the application of SiC-MOSFET power modules becomes increasingly widespread, their long-term reliability has gradually become a key concern in the industry. The reliability and lifespan of SiC-MOSFET power modules are inextricably linked to the junction temperature of their internal chips. The thermal stress cycles caused by the constant fluctuations in the module's internal junction temperature are the primary cause of device aging and failure. Online, real-time measurement of the junction temperature of SiC-MOSFET power modules is fundamental to reliability assessment, cost-effectiveness improvement, active thermal control, and condition monitoring.

[0003] Existing junction temperature measurement methods primarily include optical non-contact measurement, physical contact measurement, thermal network prediction, finite element method, and thermosensitive electrical parameter method. The optical method requires opening the module package, is highly invasive, and is not suitable for field applications. Physical contact measurement offers lower costs but longer response times and lower accuracy. The thermal network method faces the challenge of device aging leading to thermal network parameter bias, which can result in measurement errors. The thermosensitive electrical parameter method utilizes easily measurable external electrical parameters to extract and monitor the junction temperature of power modules. This method eliminates the need to modify the module package structure and offers high-speed response and strong online capabilities. Due to its low cost, high response speed, and non-invasive nature, it is widely used.

[0004] A comprehensive comparison of linearity, sensitivity, electrothermal coupling, online measurement capability, and measurement complexity reveals that dynamic thermally sensitive electrical parameters, such as turn-off delay time and turn-on current change rate, exhibit significant electrothermal coupling, making offline calibration and online measurement more complex. Static thermally sensitive electrical parameters, such as threshold voltage, exhibit significant individual chip variations and exhibit severe aging drift, creating difficulties in calibration. On-state resistance, with its high linearity, high sensitivity, and strong online capability, enables efficient junction temperature measurement and monitoring in power electronics systems. The key to the application of the on-state resistance method lies in reducing measurement error, improving measurement resolution, establishing a high-precision junction temperature measurement model, resolving the contradictions between wide measurement range and high precision, high-frequency switching and slow response, and avoiding overly complex measurement steps to achieve high measurement accuracy and high dynamic response.

[0005] In the prior art, on-resistance is measured using measurement tools such as tracers and oscilloscopes. This measurement method has problems such as insufficient resolution and low response speed, and cannot guarantee high-precision and high-response measurement.

[0006] Traditional junction temperature measurement methods establish a temperature-on-resistance curve through an offline calibration process. However, the curve function obtained using traditional least squares fitting methods cannot meet high-precision requirements. The key to the application of the on-resistance method lies in resolving the contradiction between a wide measurement range and high precision, and between high-frequency switching and slow response. Although intelligent algorithms such as neural networks can optimize the model curve, the high-voltage and high-frequency operating characteristics of SiC-MOSFET power modules increase the difficulty of on-resistance measurement, resulting in low measurement accuracy and slow response speed. This can lead to large deviations in junction temperature measurement results and affect the online capability of junction temperature measurement, failing to fundamentally address these deficiencies. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a power device on-resistance measurement circuit and a junction temperature measurement method and system to improve the on-resistance measurement accuracy and response speed in view of the shortcomings of the existing technology.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: a power device on-resistance measurement circuit, comprising:

[0009] A micro-current source, used to provide conduction current to the high-voltage blocking module;

[0010] A high-voltage blocking module, wherein a first input terminal is connected to the output terminal of the micro-current source, and a second input terminal is connected to the drain of the power device to be tested;

[0011] An operational amplifier is connected to the output end of the high-voltage blocking module and is used to calculate the measured value of the conduction voltage drop of the power device to be measured.

[0012] When the device under test is in the off state, the high-voltage blocking module blocks the hundred-volt voltage, shortening the measurement range and effectively improving the measurement accuracy; when the device under test is in the on state, the micro-current source provides the on-current to the high-voltage blocking module, and the on-state electrical parameters of the device under test are transmitted to the input of the operational amplifier at high speed and high precision, ensuring the accuracy of the measurement results; when the device under test is in the high-frequency switching state, the wide bandwidth and high voltage slew rate characteristics of the on-state resistance measurement circuit meet the high-frequency requirements of the measurement, ensuring the high-speed response of the measurement. Therefore, the on-state resistance measurement circuit of the present invention can effectively solve the contradiction between wide range and high precision in the prior art, avoid the contradiction between high-frequency switching and slow response, and ensure the high-precision and high dynamic response capability of the on-state resistance measurement.

[0013] In the present invention, the micro-current source includes a first voltage source; the first voltage source is connected to the emitter of the first transistor and the emitter of the third transistor; the base of the first transistor is connected to the base of the third transistor; the base of the first transistor, the base of the third transistor, and the collector of the first transistor are all connected to the emitter of the second transistor; the collector of the third transistor is connected to the emitter of the fourth transistor; the base of the second transistor is connected to the base of the fourth transistor; the base of the second transistor, the base of the fourth transistor, and the collector of the second transistor are all connected to one end of the first voltage-dividing resistor, and the other end of the first voltage-dividing resistor is grounded; the collector of the fourth transistor is connected to one end of the second voltage-dividing resistor; the other end of the second voltage-dividing resistor is connected to the first input end of the high-voltage blocking module. When the device under test (i.e., the power device under test) is in the on state, the output current of the micro-current source flows through the high-voltage diode and the device under test into the reference ground, i.e., the source of the device under test.

[0014] In this invention, the microcurrent source's primary function is to provide on-current to the high-voltage blocking module. To reduce losses in the measurement link, a milliampere-level on-current is required. The microcurrent source employs a mirror current source topology, which offers good symmetry. The output current can be controlled by adjusting the voltage divider resistor. This simple structure ensures stable output current and offers excellent temperature compensation.

[0015] In the present invention, the high-voltage blocking module includes a first diode; the anode of the first diode is connected to the output of the micro-current source; the cathode of the first diode is connected to the drain of the power device to be measured and the operational amplifier. The high-voltage first diode blocks the hundred-volt voltage when the device is turned off, thereby shortening the measurement range and improving accuracy.

[0016] In the present invention, taking into account the influence of the forward conduction voltage drop of the first diode on the measurement result, in order to eliminate this influence, a second diode is connected between the cathode of the first diode and the drain of the power device to be measured; the cathode of the second diode is connected to the drain of the power device to be measured; and the anode of the second diode is connected to the cathode of the first diode and the operational amplifier.

[0017] In the present invention, since the device under test is in a high-frequency switching state, voltage spikes will appear during the conduction and shutdown processes, which will impact the input of the operational amplifier (operational amplifier), damage the device, and reduce operational reliability. Therefore, in order to prevent the voltage at the input of the operational amplifier from exceeding the normal operating range, a clamping circuit is connected between the output end of the high-voltage blocking module and the operational amplifier.

[0018] The clamping circuit includes a third diode and a fourth diode; the cathode of the third diode and the anode of the fourth diode are both connected to the output terminal of the high-voltage blocking module; the anode of the third diode is grounded; and the cathode of the fourth diode is connected to a second voltage source. The clamping circuit of the present invention uses diodes to limit the input voltage, allowing the operational amplifier to operate within a normal range. It has a simple structure and high reliability.

[0019] The output end of the operational amplifier is connected to the AD sampling and conditioning module; the AD sampling and conditioning module outputs the on-state resistance measurement value R on =(2V a -V b ) / I ds , where V a is the cathode voltage of the first diode, V b is the output voltage of the aforementioned micro-current source, I ds is the load current.

[0020] The present invention also provides a method for online real-time measurement of junction temperature of a power device, comprising the following steps:

[0021] S1. Obtain sample data of the on-state resistance of the power device at a given temperature and a given load current using the on-state resistance measurement circuit described above;

[0022] S2. performing normalization processing on the sample data;

[0023] S3. Use the normalized sample data to construct a training set;

[0024] S4, the on-state resistance R of the power device to be tested when it is turned on is set in the training set. on With the load current I ds As an input variable, the junction temperature T j As the output variable, the fully connected BP neural network is trained to obtain the junction temperature measurement model.

[0025] The present invention can measure the on-state resistance in real time, can measure the junction temperature of the power module (power device) online in real time during the operation of the power electronic system, and can truly and accurately reflect the junction temperature fluctuation of the power module.

[0026] The process of acquiring sample data of on-state resistance includes:

[0027] 1) Place the power device to be tested in a constant temperature box and let it stand for a set time to allow the power device to reach thermal equilibrium, which is considered as the junction temperature T j consistent with the given temperature;

[0028] 2) The power device to be tested is operated at various current levels, and the on-state resistance R of the power device to be tested under various working conditions is measured by the on-state resistance measurement circuit.on and load current I ds ;

[0029] 3) Changing the given temperature value in the constant temperature box, repeating steps 1) and 2) to obtain the on-state resistance of the power device under different given temperatures and different given load currents.

[0030] The acquisition of the above sample data is a non-invasive process that does not affect the actual engineering application of the device under test. The sample data can be obtained while the power electronic system is operating normally, laying the foundation for the online and real-time extraction of junction temperature.

[0031] The present invention also provides an online real-time measurement system for junction temperature of a power device, comprising a memory, a processor and a computer program stored in the memory; the processor executes the computer program to implement the steps of the above-mentioned measurement method of the present invention.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention can extract the on-resistance of the power module in real time, and can measure the junction temperature of the power module online in real time during the operation of the power electronic system. The contradiction between the wide range and high precision of the measuring equipment is solved by the on-resistance measurement module, while ensuring the high-speed response capability of the measurement, thereby realizing on-resistance measurement with high precision and high response capability; the data of thermal parameters such as on-resistance and load current are obtained through the single pulse calibration link, and then the junction temperature online measurement model is established through the fully connected neural network prediction model; the on-resistance and load current are collected in real time and input into the junction temperature online measurement model, and the junction temperature fluctuation is displayed in real time through the host computer interface, thereby realizing high-precision junction temperature online real-time measurement. The present invention can truly and accurately reflect the junction temperature fluctuation of the power module, especially the SiC-MOSFET power module, and provide an important basis for the reliability assessment, life prediction and health management of the power module, which is conducive to ensuring the reliable operation of the power electronic system and has strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 1 is a circuit diagram of an on-resistance measurement module in the online real-time junction temperature measurement system in Example 1 of the present invention;

[0034] Figure 2 2 is a schematic structural diagram of a junction temperature online real-time measurement system in Example 2 of the present invention;

[0035] Figure 3 This is a block diagram of a control module of a system for online real-time measurement of junction temperature in Example 2 of the present invention;

[0036] Figure 4 This is a neural network training flow chart of a junction temperature model building module in the online real-time junction temperature measurement system in Example 3 of the present invention;

[0037] Figure 5 It is a visualization surface of the junction temperature model based on the fully connected neural network in Example 3 of the present invention;

[0038] Figure 6 This is the real-time monitoring interface for the junction temperature of the SiC-MOSFET power module in Example 3 of the present invention;

[0039] Figure 7 This is a comparison between the actual junction temperature measured by the online real-time junction temperature measurement system in Example 3 of the present invention and the simulated junction temperature. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0041] In this article, the terms "first", "second" and other similar words are not intended to imply any order, quantity and importance, but are merely used to distinguish different elements. In this article, the terms "one", "an" and other similar words are not intended to indicate that there is only one of the things described, but rather to indicate that the relevant description is only for one of the two things described, and the things described may have one or more. In this article, the terms "comprise", "include" and other similar words are intended to indicate logical relationships, and cannot be regarded as indicating relationships in spatial structure. For example, "A includes B" is intended to indicate that B logically belongs to A, and does not mean that B is spatially located inside A. In addition, the meanings of the terms "comprise", "include" and other similar words should be regarded as open, rather than closed. For example, "A includes B" is intended to indicate that B belongs to A, but B does not necessarily constitute the whole of A, and A may also include other elements such as C, D, and E.

[0042] Example 1

[0043] Figure 1 This is a circuit diagram of the on-resistance measurement module 50 of the junction temperature online real-time measurement system provided in Example 1 of the present invention, including: a micro-current source part 501 (micro-current source), a high-voltage blocking part 502 (high-voltage blocking module), a clamping part 503 (clamping circuit), and an operation part 504.

[0044] Specifically, the micro current source part 501 provides a conduction current to the high voltage blocking diode through a mirror current source, which is mainly provided by the voltage source V SS, the first to fourth transistors T1, T2, T3, T4 and the voltage divider resistors R1 (first voltage divider resistor) and R2 (second voltage divider resistor). When the device under test is in the off state, the output current of the micro current source flows through the high voltage diode D 1B , clamping diode D 2B , and the voltage source V of the clamping section DD Form a current loop; when the device under test is in the on state, the output current of the micro-current source flows through the high-voltage diode D 1A (first diode), D 1B (Second diode) and the device under test flow into the reference ground. Wherein, in the circuit of this embodiment, the reference ground is the source of the device under test. The high voltage blocking part 502 is connected to the reference ground by a high withstand voltage diode D 1A The blocking device is turned off at the hundred-volt level to shorten the measurement range and improve accuracy. 1A The influence of forward conduction voltage drop on the measurement results, adding diode D 1B , diode D 1A 、D 1B Take the same parameters. The measured value of the on-state voltage drop of the device under test is V ds The calculation is shown in formula (1):

[0045]

[0046] The clamping part 503 includes a voltage source V DD With clamping diode D 2A (third diode), D 2B (The fourth diode), the main function of this part is to protect the voltage at the input of the operational amplifier from exceeding the normal operating range. Since the device under test is in a high-frequency switching state, voltage spikes will appear during the on-off process, which will impact the input of the operational amplifier, damage the device, and reduce operational reliability. Therefore, a clamping diode is used at the input of the operational amplifier to limit the input voltage so that the operational amplifier works within the normal range. The operation part 504 is mainly composed of an operational amplifier link with a gain of 1. The main purpose of this link is to offset the influence of the forward conduction voltage of the high-voltage diode on the measurement result through operation, and realize the operation of formula (1). Among them, the input resistance and feedback resistance are 1kΩ. According to the knowledge of circuit principles, formula (2) can be obtained. The voltage at the output of the operational amplifier is the value of the conduction voltage drop. After AD sampling, the conduction voltage drop and the load current are operated to obtain the on-state resistance measurement value R on , in order to achieve high-precision and high-response speed on-state resistance measurement.

[0047]

[0048] Example 2

[0049] like Figure 2As shown, an online real-time measurement system for the junction temperature of a SiC-MOSFET power module based on on-resistance change provided by Example 2 of the present invention includes: a main power circuit 10, a constant temperature heating module 20, a control module 30, a load module 40, an on-resistance measurement module 50, a junction temperature model building module 60, and a junction temperature online measurement module 70.

[0050] Specifically, the main power circuit 10 is used to provide electrical connection to the SiC-MOSFET power module so that the device under test can operate in a single-pulse calibration mode or a single-phase inverter mode; the constant temperature heating module 20 is used to provide an ambient temperature to the device under test so that its junction temperature is a given temperature value; the control module 30 is used to control the on and off of the device under test to achieve switching between multiple operating modes, such as Figure 3 As shown; a load module 40 is electrically connected to the main power circuit 10 and is used to change the operating conditions of the device under test so that the device under test can operate at various current levels; an on-resistance measurement module 50 is used to measure the on-resistance and related electrical parameters of the SiC-MOSFET power module with high precision and high response speed, so as to realize online real-time and high-precision junction temperature measurement; a junction temperature model building module 60 obtains data of thermal-sensitive parameters such as on-resistance and load current through a single-pulse calibration link, and then establishes a junction temperature online measurement model through a neural network prediction model; a junction temperature online measurement module 70 collects on-resistance and load current in real time and inputs them into the junction temperature online measurement model, and displays the junction temperature fluctuation in real time through the host computer interface, so as to realize high-precision online real-time measurement of the junction temperature.

[0051] The junction temperature model building module 60 obtains the data of thermal parameters such as on-resistance and load current through the single pulse calibration link, and then establishes the junction temperature online measurement model through the neural network prediction model. Among them, the single pulse calibration working mode is used to obtain the load current I ds Lower on-state resistance R on and junction temperature T jThe relationship curve between the two is shown. Since the power loss when the working current is applied to the SiC-MOSFET power module will cause it to self-heat, the longer the conduction time, the more serious the heat. This phenomenon will cause errors in the junction temperature measurement results. Therefore, a single-pulse trigger circuit is used to reduce the impact of the self-heating effect, ensuring that the effect of the device's self-heating effect on the junction temperature can be ignored. The single-pulse calibration working mode uses a single-pulse trigger circuit to reduce the self-heating effect, ensuring that the effect of the self-heating effect on the junction temperature can be ignored; given the temperature of the constant temperature heating module, the SiC-MOSFET power module is heated to thermal equilibrium, and the junction temperature of the SiC-MOSFET power module is considered to be consistent with the given temperature; at the same time, the load module is adjusted so that the SiC-MOSFET power module operates at different current levels, and a series of temperature, load current and on-state resistance data are recorded. The specific implementation steps of the single-pulse calibration working mode are as follows:

[0052] Step 1: Start the constant temperature heating module 20 and set the initial temperature to 20°C. Place the device under test in the constant temperature box and let it stand for 15-20 minutes to allow the device under test to reach thermal equilibrium, which is considered as the junction temperature T j consistent with the given temperature;

[0053] Step 2: Set the load module 40 to make the device under test run at various current levels. The control module 30 sends a switch signal to the device under test to turn on the device under test at a certain current level. The on-resistance measurement module 50 records the on-resistance R of the device under test under various working conditions. on and load current I ds ;

[0054] Step 3: On-state resistance R of the device under test under various working conditions at the initial temperature on and load current I ds After recording is completed, change the given temperature value of the constant temperature heating module 20, repeat steps 1 and 2, and obtain different temperatures and different currents I ds The on-state resistance R of the device under test on .

[0055] Example 3

[0056] In this embodiment, sample data of on-state resistance under given temperature and given load current are obtained according to the single pulse calibration working mode. A junction temperature measurement model based on a fully connected neural network is built using the Tensorflow framework in the PyCharm compilation environment. Figure 4 The following is a flowchart of neural network training. The specific implementation steps are as follows:

[0057] Step 1: Data normalization. Since the activation function of the output layer of the neural network has a limited range, the target data of the network training needs to be mapped to the range of the activation function. Before inputting the sample data into the model, it needs to be normalized. This system uses the bipolar sigmoid activation function for linear transformation, mapping the calculation results of the original data to the range [0,1].

[0058] Step 2: Load the processed data. Select the on-state resistance R of the device under test when it is turned on. on With the load current I ds As an input variable, the junction temperature of the power module T j As the output variable, based on the processed data, 70% of the sample data is randomly selected as the training set to train the model, and the remaining 30% is used as the test set to verify the accuracy of the model;

[0059] Step 3: Network initialization settings. The selected input layer is 1 layer, containing 2 neurons; the hidden layer is 3 layers, containing 64, 32, and 16 neurons respectively; the output layer is 1 layer, and the learning rate is set to 0.001;

[0060] Step 4: Train the network and predict the results. Load the processed sample data, randomly select 70% of the sample data as the training set, and input it into the network to train the fully connected BP neural network; use the remaining 30% of the sample data as the validation set, and use the trained neural network to obtain the predicted value. The junction temperature model based on the fully connected neural network is visualized as follows: Figure 5 shown.

[0061] Step 5: Error Evaluation. The output results are denormalized and then compared with the theoretical junction temperature value. The difference between the estimated model output and the expected output is calculated. Maximum absolute error (MAE), mean square error (MSE), and accuracy are used as evaluation criteria to verify the model's effectiveness and quantify its accuracy. The closer the maximum absolute error (MAE) and mean square error (MSE) are to 0, and the closer the accuracy is to 1, the higher the model's prediction accuracy for the IGBT power module junction temperature and the more reliable the model. Evaluation shows that the maximum absolute error (MAE) of the junction temperature model in this system does not exceed 0.0086, the mean square error (MSE) does not exceed 0.21%, and the accuracy is between 99.78% and 100%, indicating a high level of model reliability.

[0062] The junction temperature online measurement module 80 inputs the thermal parameters such as the on-state resistance collected in real time in the single-phase inverter working mode into the junction temperature online measurement model, and displays the junction temperature fluctuation in real time through the host computer interface, thereby realizing high-precision online real-time measurement of the junction temperature.

[0063] The working principle of the single-phase inverter operating mode is as follows: the control module sends a modulation signal to control the high-frequency switching action of the power module under test. The DC side voltage is input into the single-phase inverter main circuit composed of the power module under test after voltage stabilization and filtering. After low-pass filtering, it is connected to the load module to output the AC waveform. At the same time, the on-state resistance measurement module is directly connected to the drain of the device under test to achieve high-precision extraction of the on-state resistance, which is used for junction temperature extraction by the online junction temperature measurement module.

[0064] The single-phase inverter operating mode is used to achieve online real-time measurement of the junction temperature of the SiC-MOSFET power module under actual inverter operating conditions. The working principle of this mode is as follows:

[0065] Step 1: The control module 30 sends a modulation signal to control the high-frequency switching action of the device under test. The DC side voltage is input into the single-phase inverter main circuit composed of the SiC-MOSFET power module under test after voltage stabilization and filtering. After low-pass filtering, it is connected to the load module 40 to output the AC waveform.

[0066] Step 2: The on-resistance measurement module 50 is directly connected to the drain of the device under test via the high-voltage blocking portion 502. This module's primary function is to resolve the conflict between wide measurement range and high precision in measurement equipment, while ensuring high-speed measurement response. The on-resistance measurement module 50 enables high-precision and high-response measurement of the device's on-resistance. It also clamps switching spikes to prevent impact on downstream devices, ensuring reliable operation of the online, real-time junction temperature measurement system.

[0067] Step 3: The real-time collected thermal parameters such as on-resistance are input into the junction temperature online measurement model, and the junction temperature fluctuation is displayed in real time through the host computer interface to achieve high-precision online real-time measurement of junction temperature. Figure 6 The figure shows the real-time junction temperature monitoring interface of the SiC-MOSFET power module, which is used to monitor the junction temperature swing and maximum junction temperature of the SiC-MOSFET power module within multiple fundamental frequency cycles.

[0068] The PLECS power electronics simulation software is used to establish an electrothermal simulation model. The theoretical value of the junction temperature under a given task condition is obtained through simulation. The comparison between the measured junction temperature and the simulated junction temperature of the system within a fundamental frequency cycle is shown in Figure 2. Figure 7 As shown in the figure, the measured junction temperature fluctuation trend and amplitude are basically consistent with the theoretical simulation results, and the two have a good fit. The absolute error between the measured junction temperature and the simulated junction temperature does not exceed 0.3°C, and the relative error does not exceed 1.5%. Therefore, the proposed system can truly and accurately reflect the junction temperature fluctuation of the SiC-MOSFET power module under test, providing an important basis for the reliability assessment, life prediction and health management of SiC-MOSFET power modules, and is conducive to ensuring the reliable operation of power electronic systems.

[0069] The above disclosure is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, and they should all be covered by the scope of protection of the present invention.

Claims

1. A power device on-resistance measurement circuit, characterized in that: include: A micro-current source, used to provide conduction current to the high-voltage blocking module; A high-voltage blocking module, wherein a first input terminal is connected to the output terminal of the micro-current source, and a second input terminal is connected to the drain of the power device to be tested; an operational amplifier connected to the output terminal of the high-voltage blocking module and used to calculate the measured value of the conduction voltage drop of the power device to be measured; S1. Obtain sample data of the on-state resistance of the power device at a given temperature and a given load current; S2. performing normalization processing on the sample data; S3. Use the normalized sample data to construct a training set; S4, the on-state resistance R of the power device to be tested when it is turned on is set in the training set. on With the load current I ds As an input variable, the junction temperature T j As the output variable, the fully connected BP neural network is trained to obtain the junction temperature measurement model; The process of acquiring sample data of on-state resistance includes: 1) Place the power device to be tested in a constant temperature box and let it stand for a set time to allow the power device to reach thermal equilibrium, which is considered to be the junction temperature T j consistent with the given temperature; 2) The power device to be tested is operated at various current levels, and the on-state resistance R of the power device to be tested under various working conditions is measured by the on-state resistance measurement circuit. on and load current I ds ; 3) Changing the given temperature value in the constant temperature box, repeating steps 1) and 2) to obtain the on-state resistance of the power device under different given temperatures and different given load currents.

2. The power device on-resistance measurement circuit according to claim 1, characterized in that: The micro-current source includes a first voltage source; the first voltage source is connected to the emitter of the first transistor and the emitter of the third transistor; the base of the first transistor is connected to the base of the third transistor; the base of the first transistor, the base of the third transistor, and the collector of the first transistor are all connected to the emitter of the second transistor; the collector of the third transistor is connected to the emitter of the fourth transistor; the base of the second transistor is connected to the base of the fourth transistor; the base of the second transistor, the base of the fourth transistor, and the collector of the second transistor are all connected to one end of the first voltage-dividing resistor, and the other end of the first voltage-dividing resistor is grounded; the collector of the fourth transistor is connected to one end of the second voltage-dividing resistor; the other end of the second voltage-dividing resistor is connected to the first input end of the high-voltage blocking module.

3. The power device on-resistance measurement circuit according to claim 1 or 2, characterized in that: The high-voltage blocking module includes a first diode; the anode of the first diode is connected to the output end of the micro-current source; and the cathode of the first diode is connected to the drain of the power device to be measured and the operational amplifier.

4. The power device on-resistance measurement circuit according to claim 3, characterized in that: A second diode is connected between the cathode of the first diode and the drain of the power device to be measured; the cathode of the second diode is connected to the drain of the power device to be measured; and the anode of the second diode is connected to the cathode of the first diode and the operational amplifier.

5. The power device on-resistance measurement circuit according to claim 1 or 2, characterized in that: A clamping circuit is connected between the output end of the high-voltage blocking module and the operational amplifier.

6. The power device on-resistance measurement circuit according to claim 5, characterized in that: The clamping circuit includes a third diode and a fourth diode; the cathode of the third diode and the anode of the fourth diode are both connected to the output end of the high-voltage blocking module; the anode of the third diode is grounded; and the cathode of the fourth diode is connected to the second voltage source.

7. The power device on-resistance measurement circuit according to claim 2, characterized in that: The output end of the operational amplifier is connected to the AD sampling and conditioning module; the AD sampling and conditioning module outputs the on-state resistance measurement value R on :R on =(2V a -V b ) / I ds , where V a is the cathode voltage of the first diode, V b is the output voltage of the micro-current source, I ds is the load current.

8. A method for online real-time measurement of junction temperature of a power device, characterized in that: The following steps are involved: S1. Obtain sample data of the on-state resistance of a power device at a given temperature and a given load current using the on-state resistance measurement circuit according to any one of claims 1 to 6; S2. performing normalization processing on the sample data; S3. Use the normalized sample data to construct a training set; S4, the on-state resistance R of the power device to be tested when it is turned on is set in the training set. on With the load current I ds As an input variable, the junction temperature T j As the output variable, the fully connected BP neural network is trained to obtain the junction temperature measurement model; The process of acquiring sample data of on-state resistance includes: 1) Place the power device to be tested in a constant temperature box and let it stand for a set time to allow the power device to reach thermal equilibrium, which is considered to be the junction temperature T j consistent with the given temperature; 2) The power device to be tested is operated at various current levels, and the on-state resistance R of the power device to be tested under various working conditions is measured by the on-state resistance measurement circuit. on and load current I ds ; 3) Changing the given temperature value in the constant temperature box, repeating steps 1) and 2) to obtain the on-state resistance of the power device under different given temperatures and different given load currents.

9. A power device junction temperature online real-time measurement system, comprising a memory, a processor, and a computer program stored in the memory; characterized in that: The processor executes the computer program to implement the steps of the method according to claim 8.

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