CN115508684A - Power device on-state resistance measurement circuit and junction temperature measurement method and system - Google Patents

Abstract

The invention discloses a power device on-state resistance measuring circuit and a junction temperature measuring method and system, which solve the contradiction between the wide range and the high precision of measuring equipment through an on-state resistance measuring module, ensure the high-speed response capability of measurement and realize the on-state resistance measurement with high precision and high response capability; the junction temperature model building module obtains data of on-state resistance, load current and other thermosensitive parameters through a single-pulse calibration link, and then builds a junction temperature online measurement model through a full-connection neural network prediction model; the junction temperature online measurement module collects the on-state resistance and the load current in real time, inputs the on-state resistance and the load current into the junction temperature online measurement model, displays the junction temperature fluctuation condition in real time through an upper computer interface, and realizes the high-precision junction temperature online real-time measurement. The system can truly and accurately reflect junction temperature fluctuation of the SiC-MOSFET power module, provides important basis for reliability evaluation, service life prediction and health management of the SiC-MOSFET power module, and is beneficial to ensuring the reliable operation of a power electronic system.

Description

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

technical field

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

Background technique

As a new generation of wide-bandgap semiconductor power devices, SiC-MOSFET power modules have the advantages of high voltage, high frequency, and high power density. They stand out among existing power devices and have broad application prospects. However, as SiC-MOSFET power modules are more and more widely used, their reliability in long-term operation has gradually become the focus of the industry. The reliability and life of SiC-MOSFET power modules are inseparable from the junction temperature of the internal chip. The thermal stress cycle caused by the continuous fluctuation of the internal junction temperature of the module has become the main cause of device aging and failure. The online real-time measurement of the junction temperature of SiC-MOSFET power modules is the basis for its reliability evaluation, cost performance improvement, active thermal control and status monitoring.

The existing junction temperature measurement methods mainly include optical non-contact measurement, physical contact measurement, thermal network prediction method, finite element method, and heat-sensitive electrical parameter method. Among them, the optical method needs to open the package of the module, which is highly intrusive and not suitable for field applications; the cost of physical contact measurement is low, but the response time is long and the accuracy is low; the difficulty in the application of the thermal network method is that the aging of the device causes heat The network parameters are biased, and the measurement results will produce errors; the heat-sensitive electrical parameter method uses external electrical parameters that are easy to measure to extract and monitor the junction temperature of the power module, without changing the module packaging structure, and has high-speed response capability and strong online capability. It is widely used because of its low cost, high response speed, and non-invasiveness.

A comprehensive comparison is made from the aspects of linearity, sensitivity, electrothermal coupling, on-line measurement capability, and measurement complexity. The dynamic thermal sensitive electrical parameters represented by parameters such as turn-off delay time and turn-on current change rate have more electrothermal coupling. Off-line calibration and online measurement are relatively complicated; there are significant individual chip differences in static heat-sensitive electrical parameters such as threshold voltage, and aging drift is serious, which brings difficulties to the calibration process; on-state resistance is characterized by its high linearity, high sensitivity and strong The advantage of online capability enables efficient junction temperature measurement and monitoring in power electronics systems. The key points of the application of the on-state resistance method are mainly to reduce the measurement error, improve the measurement resolution, establish a high-precision junction temperature measurement model, solve the contradiction between wide range and high precision, high-frequency switching and slow response, and avoid measurement The link is too complicated to achieve high measurement accuracy and high dynamic response measurement.

In the prior art, the on-state resistance is measured by measuring tools such as graph instruments and oscilloscopes. This measurement method has the problems of insufficient resolution and low response speed, and cannot guarantee the high precision and high response of the measurement.

The traditional junction temperature measurement method establishes the temperature-on-state resistance curve through the offline calibration link, but the curve function obtained by the traditional least square method and other fitting methods cannot meet the high precision requirements. The key point of the application of the on-state resistance method is to solve the contradiction between wide range and high precision, high frequency switching and slow response. Although the model curve can be optimized by using intelligent algorithms such as neural networks, the SiC-MOSFET power module High-voltage and high-frequency operating characteristics increase the difficulty of on-state resistance measurement, and there are problems such as low measurement accuracy and slow response speed, which will lead to large deviations in junction temperature measurement results, and will affect the online capability of junction temperature measurement. It makes up for the defects of low precision and poor online ability.

Contents of the invention

The technical problem to be solved by the present invention is to provide a power device on-state resistance measurement circuit and a junction temperature measurement method and system to improve the measurement accuracy and response speed of the on-state resistance.

In order to solve the above technical problems, the technical solution adopted in the present invention is: a power device on-state resistance measurement circuit, comprising:

The micro current source is used to provide the conduction current to the high voltage blocking module;

A high-voltage blocking module, the first input terminal is connected to the output terminal of the micro-current source, and the second input terminal is connected to the drain of the power device under test;

The 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 under test.

When the device under test is in the off state, the high-voltage blocking module blocks the hundred-volt level voltage, shortens the measurement range, and effectively improves the measurement accuracy; when the device under test is in the on state, the micro-current source provides a conduction current to the high-voltage blocking module, The on-state electrical parameters of the device under test are transmitted to the input terminal of the operational amplifier with high speed and high precision to ensure the accuracy of the measurement results; when the device under test is in a high-frequency switching state, the wide-band and high-voltage slew rate characteristics of the on-state resistance measurement circuit Meet the high-frequency requirements of the measurement and ensure 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 high precision and high dynamic response of on-state resistance measurement ability.

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 triode and the emitter of the third triode; the base of the first triode is connected to the emitter of the triode The base of the third triode is connected; the base of the first triode, the base of the third triode, and the collector of the first triode are all connected to the emitter of the second triode; the third The collector of the triode is connected to the emitter of the fourth triode; the base of the second triode is connected to the base of the fourth triode; the base of the second triode, the fourth triode Both the base of the tube and the collector of the second triode are 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 triode 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 (that is, 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, that is, the source of the device under test.

In the present invention, considering that the main function of the micro-current source is to provide the conduction current to the high-voltage blocking module, in order to reduce the loss in the measurement link, the conduction current is required to be in milliampere level. The micro current source adopts the topological structure of the mirror current source, which has good symmetry. The output current can be controlled by adjusting the voltage dividing resistor. The structure is simple, and it can ensure the stability of the output current of the micro current source, and has good temperature compensation. characteristic.

In the present invention, 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; the cathode of the first diode is connected to the drain of the power device under test and an operational amplifier . The hundreds of volts voltage when the device is turned off is blocked by the first diode with high withstand voltage, so as to shorten the measurement range and improve the accuracy.

In the present invention, considering the impact of the forward conduction voltage drop of the first diode on the measurement results, in order to eliminate this impact, a second diode is connected between the cathode of the first diode and the drain of the power device under test. A diode; the cathode of the second diode is connected to the drain of the power device under test; the anode of the second diode is connected to the cathode of the first diode and the operational amplifier.

In the present invention, since the device to be tested is in a high-frequency switching state, a voltage peak will appear in the turn-on and turn-off process, which will have an impact on the input of the operational amplifier (operational amplifier), damage the device, and reduce the operational reliability. Therefore, in order to prevent the operation The voltage at the input terminal of the amplifier exceeds the normal working range, and a clamping circuit is connected between the output terminal of the high voltage blocking module and the operational amplifier.

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 pole tube is grounded; the cathode of the fourth diode is connected to the second voltage source. The clamping circuit of the present invention uses diodes to limit the input voltage, so that the operational amplifier can work within the normal range, and has simple structure and high reliability.

The output terminal of the operational amplifier is connected to the AD sampling and conditioning module; the AD sampling and conditioning module outputs an on-state resistance measurement value R _on =(2V _a -V _b )/I _ds , wherein V _a is the aforementioned first diode cathode Voltage, V _b is the output terminal voltage of the aforementioned micro-current source, and I _ds is the load current.

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

S1. Using the above-mentioned on-state resistance measurement circuit to obtain sample data of the on-state resistance of the power device at a given temperature and a given load current;

S2. Perform normalization processing on the sample data;

S3. Using the normalized sample data to construct a training set;

S4. Taking the on-state resistance R _on and load current I _ds of the power device under test in the training set as the input variables, and the junction temperature T _j of the power device under test as the output variable, train the fully connected BP neural network to obtain the junction temperature Measurement model.

The 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.

The sample data acquisition process of the on-state resistance includes:

1) Put the power device under test into the constant temperature box, and let it stand for a set time, so that the power device under test reaches thermal equilibrium, and consider that the junction temperature T _j of the power device under test is consistent with the given temperature;

2) Make the power device to be tested operate at various current levels, and measure the on-state resistance R _on and the load current I _ds of the power device to be tested under each working condition through the on-state resistance measuring circuit;

3) Change the given temperature value in the constant temperature box, repeat step 1) and step 2), and obtain the on-state resistance of the power device at different given temperatures and different given load currents.

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 running normally, laying the foundation for the online and real-time extraction of junction temperature.

The present invention also provides an online real-time measurement system for the junction temperature of power devices, including a memory, a processor, and a computer program stored on the memory; the processor executes the computer program to realize the steps of the above measurement method of the present invention.

Compared with the prior art, the invention has the beneficial effects that: the invention can extract the on-state 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. Through the on-state resistance measurement module, the contradiction between the wide range and high precision of the measuring equipment is solved, and at the same time, the high-speed response capability of the measurement is ensured, and the on-state resistance measurement with high precision and high response capability is realized; the on-state resistance is obtained through the single pulse calibration link and load current and other thermal parameters, and then establish a junction temperature online measurement model through a fully connected neural network prediction model; collect on-state resistance and load current in real time, and input them into the junction temperature online measurement model, through the host computer interface Real-time display of junction temperature fluctuations, realizing high-precision online real-time measurement of junction temperature. The 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 evaluation, life prediction and health management of the power module, which is beneficial to ensure the reliable operation of the power electronic system. Versatile.

Description of drawings

Fig. 1 is the circuit diagram of the on-state resistance measurement module in the junction temperature online real-time measurement system in Embodiment 1 of the present invention;

2 is a schematic structural diagram of an online real-time measurement system for junction temperature in Embodiment 2 of the present invention;

Fig. 3 is a control module block diagram of the junction temperature online real-time measurement system in Embodiment 2 of the present invention;

Fig. 4 is the neural network training flow chart of the junction temperature model building module in the junction temperature online real-time measurement system in embodiment 3 of the present invention;

Fig. 5 is a visualization surface of a junction temperature model based on a fully connected neural network in Embodiment 3 of the present invention;

Fig. 6 is the interface for real-time monitoring of the junction temperature of the SiC-MOSFET power module in Example 3 of the present invention;

FIG. 7 is a comparison of the junction temperature measured by the junction temperature online real-time measurement system and the simulated junction temperature in Embodiment 3 of the present invention.

detailed description

In order to make the purpose, 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 It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In this document, the terms "first", "second" and other similar words are not intended to imply any order, quantity and importance, but are only used to distinguish different elements. In this document, the terms "a", "an" and other similar words are not intended to mean that there is only one of said things, but that the description is for only one of said things, which may have one or more indivual. In this document, the terms "comprising", "comprising" and other similar words are intended to indicate logical interrelationships, and cannot be regarded as denoting spatial structural relationships. For example, "A includes B" is intended to mean that B logically belongs to A, but not that B is spatially inside A. Additionally, the meanings of the terms "comprising", "comprising" and other similar words are to be regarded as open rather than closed. For example, "A includes B" means that B belongs to A, but B does not necessarily constitute the whole of A, and A may also include C, D, E and other elements.

Example 1

1 is a circuit diagram of the on-state resistance measurement module 50 of the junction temperature online real-time measurement system provided by Embodiment 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 clamp Bit part 503 (clamping circuit), operation part 504.

Specifically, the micro-current source part 501 provides conduction current to the high-voltage blocking diode through the mirror current source, which is mainly composed of the voltage source V _SS , the first to fourth transistors T ₁ , T ₂ , T ₃ , T ₄ and the voltage divider. Resistor R ₁ (first voltage dividing resistor) and R ₂ (second voltage dividing resistor) constitute. Among them, 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 and the clamping diode D _2B , forming a current loop with the voltage source V _DD of the clamping part; 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 into the reference ground. Wherein, the reference ground in the circuit of this embodiment is the source of the device under test. The high-voltage blocking part 502 blocks the hundred-volt level voltage when the device is turned off through the high withstand voltage diode D _1A , so as to shorten the measurement range and improve the accuracy. Considering the impact of the forward conduction voltage drop of diode D _1A on the measurement results, a diode D _1B is added, and diodes D _1A and D _1B take the same parameters. The measured value V _ds of the conduction voltage drop of the device under test is calculated as shown in formula (1):

The clamping part 503 includes a voltage source V _DD and clamping diodes D _2A (third diode) and D _2B (fourth diode). The main function of this part is to protect the voltage at the input terminal of the operational amplifier from exceeding the normal working range. Since the device under test is in a high-frequency switching state, there will be a voltage spike during the turn-on and turn-off process, which will have an impact on the input of the op amp, damage the device, and reduce operational reliability. Therefore, a clamp diode is used at the input end of the op amp to limit the input voltage, so that the op amp can work within the normal range. The operation part 504 is mainly composed of an operation amplification 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 the feedback resistance are 1kΩ, and the formula (2) can be obtained from the knowledge of the circuit principle, and the voltage at the output terminal of the op amp is the value of the conduction voltage drop. After AD sampling, the on-state voltage drop and the load current are calculated to obtain the on-state resistance measurement value R _on , so as to realize on-state resistance measurement with high precision and high response speed.

Example 2

As shown in FIG. 2 , an online real-time measurement system for SiC-MOSFET power module junction temperature based on on-state resistance change provided by Embodiment 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-state resistance measurement module 50 , a junction temperature model building module 60 , and an online junction temperature measurement module 70 .

Specifically, the main power circuit 10 is used to provide an electrical connection to the SiC-MOSFET power module, so that the device under test can work in a single-pulse calibration mode or a single-phase inverter mode; The device under test provides ambient temperature so that its junction temperature is a given temperature value; the control module 30 is used to control the opening and closing of the device under test, so as to realize the switching of multiple operating modes, as shown in Figure 3; the load module 40 , is electrically connected with 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; the on-state resistance measurement module 50 is used for high-precision, high-response speed measurement The on-state resistance and related electrical parameters of the SiC-MOSFET power module are used to realize online real-time high-precision junction temperature measurement; the junction temperature model building module 60 obtains the data of thermal parameters such as on-state resistance and load current through a single pulse calibration link , and then establish the junction temperature online measurement model through the neural network prediction model; the junction temperature online measurement module 70 collects the on-state resistance and load current in real time and inputs them into the junction temperature online measurement model, and displays the junction temperature in real time through the host computer interface Fluctuations, to achieve high-precision junction temperature online real-time measurement.

The junction temperature model building module 60 obtains data of thermal parameters such as on-state resistance and load current through a single pulse calibration link, and then establishes an online junction temperature measurement model through a neural network prediction model. Among them, the single-pulse calibration working mode is used to obtain the relationship curve between the on-state resistance R _on and the junction temperature T _j under each load current I _ds , because the power loss of the SiC-MOSFET power module will make it self-heating when the working current is applied , the longer the conduction time is, the more serious the heat will be. This phenomenon will cause errors in the measurement results of the junction temperature. Therefore, a single-pulse trigger circuit is used to reduce the influence of the self-heating effect and ensure that the influence of the self-heating effect of the device on the junction temperature can be ignored. The single-pulse calibration mode uses a single-pulse trigger circuit to reduce the self-heating effect, ensuring that the influence of the self-heating effect on the junction temperature can be ignored; given the temperature of the constant temperature heating module, heating the SiC-MOSFET power module to thermal equilibrium, which is regarded as SiC-MOSFET power The junction temperature of the module is 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 single pulse calibration working mode are as follows:

Step 1: Start the constant temperature heating module 20 and set the initial temperature to 20°C, put the device under test into the incubator, and let it stand for 15-20 minutes, so that the device under test reaches thermal equilibrium, which is regarded as the junction temperature T _j and the given temperature consistent;

Step 2: Set the load module 40 to make the device under test operate at various current levels, and the control module 30 sends the switch signal of the device under test to enable the device under test to be turned on at a certain current level, and record it through the on-state resistance measurement module 50 On-state resistance R _on and load current I _ds of the device under test under each working condition;

Step 3: After the on-state resistance R _on and the load current I _ds of the device under test in each working condition are recorded at the initial temperature, change the given temperature value of the constant temperature heating module 20, and repeat steps 1 and 2 to obtain different temperatures and different currents The on-state resistance R _on of the device under test at I _ds .

Example 3

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

Step 1: Data normalization. Since the activation function of the output layer of the neural network has a limited value range, it is necessary to map the target data of the network training to the value range of the activation function. Before inputting the sample data into the model, it needs to perform feature normalization processing. This system selects the bipolar S-type activation function for linear transformation, and maps the calculation results of the original data to [0,1];

Step 2: Load the processed data. Select the on-state resistance R _on and load current I _ds of the device under test as input variables, and the junction temperature T _j of the power module as the output variable. Based on the processed data, randomly select 70% of the sample data as the training set to train the model, and the remaining 30% is used as a test set to verify the accuracy of the model;

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;

Step 4: Train the network and predict the result. 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 verification set, and use the trained neural network to obtain the predicted value , the visualization surface of the junction temperature model based on the fully connected neural network is shown in Figure 5.

Step Five: Error Evaluation. The output result is denormalized, and then compared with the theoretical junction temperature value, the difference between the estimated result of the model output and the expected output result is calculated, and the maximum absolute error (MAE), mean square error (MSE) and Accuracy is used as an evaluation standard to verify the validity of the model and quantify the accuracy of the estimated model. The closer the maximum absolute error (MAE) and mean square error (MSE) obtained from the model running results are to 0, the higher the accuracy (Accuracy) is. Closer to 1, it means that the prediction accuracy of the model to the IGBT power module junction temperature is higher, and the model is more reliable. After evaluation, the maximum absolute error MAE of the junction temperature model of this system does not exceed 0.0086, the mean square error MSE does not exceed 0.21%, the accuracy rate Accuracy is between 99.78% and 100%, and the model reliability is high.

The junction temperature online measurement module 80 inputs thermal parameters such as on-state resistance and other thermal parameters collected in real time under the single-phase inverter operation mode into the junction temperature online measurement model, and displays them in real time through the host computer interface. Junction temperature fluctuations, to achieve high-precision junction temperature online real-time measurement.

The working principle of the single-phase inverter is as follows: the control module sends a modulation signal to control the high-frequency switching action of the power module under test, and the DC side voltage is stabilized and filtered and then input to the single-phase inverter composed of the power module under test. Transform the main circuit, 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 the junction temperature online measurement module The junction temperature is extracted.

Among them, the single-phase inverter working mode is used to realize the online real-time measurement of the SiC-MOSFET power module junction temperature under the actual inverter working condition. The mode works as follows:

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 stabilized and filtered and then input to the single-phase inverter main circuit composed of the SiC-MOSFET power module to be tested. After filtering, it is connected to the load module 40 to output an AC waveform.

Step 2: The on-state resistance measurement module 50 is directly connected to the drain of the device under test through the high-voltage blocking part 502 . The main function of this module is to solve the contradiction between the wide range and high precision of the measuring equipment, and at the same time ensure the high-speed response capability of the measurement. Through the on-state resistance measurement module 50, the on-state resistance of the device under test can be measured with high precision and high response speed, and at the same time, the switching peak can be clamped to avoid impact on the subsequent device, and the online real-time measurement system of the junction temperature can be guaranteed. reliable operation.

Step 3: The thermally sensitive parameters such as on-state resistance collected in real time 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 realize high-precision online real-time measurement of junction temperature. Figure 6 shows the real-time monitoring interface of the junction temperature of the SiC-MOSFET power module, which is used to monitor the junction temperature swing and the maximum junction temperature of the SiC-MOSFET power module in multiple fundamental frequency cycles.

Using the PLECS power electronics simulation software 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 7. The measured junction temperature fluctuation trend and amplitude are basically consistent with the theoretical simulation results, and the two fit well. 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 solution system of the present invention can truly and accurately reflect the junction temperature fluctuation of the SiC-MOSFET power module to be tested, and provide an important basis for the reliability evaluation, life prediction and health management of the SiC-MOSFET power module, which is beneficial to ensure the power electronics reliable operation of the system.

What is disclosed above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention.

Claims (10)

1. A power device on-resistance measurement circuit, comprising:

the micro-current source is used for providing conducting current for the high-voltage blocking module;

the first input end of the high-voltage blocking module is connected with the output end of the micro-current source, and the second input end of the high-voltage blocking module is connected with the drain electrode of the power device to be tested;

and the operational amplifier is connected with the output end of the high-voltage blocking module and is used for calculating the measured value of the conduction voltage drop of the power device to be measured.

2. The power device on-resistance measurement circuit of claim 1, wherein the micro-current source comprises a first voltage source; the first voltage source is connected with the emitting electrode of the first triode and the emitting electrode of the third triode; the base electrode of the first triode is connected with the base electrode of the third triode; the base electrode of the first triode, the base electrode of the third triode and the collector electrode of the first triode are all connected with the emitter electrode of the second triode; the collector of the third triode is connected with the emitter of the fourth triode; the base electrode of the second triode is connected with the base electrode of the fourth triode; the base electrode of the second triode, the base electrode of the fourth triode and the collector electrode of the second triode are all connected with one end of a first divider resistor, and the other end of the first divider resistor is grounded; the collector of the fourth triode is connected with one end of the second divider resistor; the other end of the second voltage-dividing resistor is connected with the first input end of the high-voltage blocking module.

3. The power device on-resistance measurement circuit of claim 1 or 2, wherein the high voltage blocking module comprises a first diode; the anode of the first diode is connected with the output end of the micro-current source; and the cathode of the first diode is connected with the drain of the power device to be tested and the operational amplifier.

4. The on-state resistance measuring circuit of the power device as claimed in claim 3, wherein a second diode is connected between the cathode of the first diode and the drain of the power device to be tested; the cathode of the second diode is connected with the drain electrode of the power device to be tested; and the anode of the second diode is connected with the cathode of the first diode and the operational amplifier.

5. The power device on-resistance measurement circuit according to claim 1 or 2, wherein 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 of claim 5, wherein the clamp circuit comprises a third diode and a fourth diode; the cathode of the third diode and the anode of the fourth diode are both connected with 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 with a second voltage source.

7. The power device on-resistance measurement circuit according to claim 2, wherein the output end of the operational amplifier is connected with an AD sampling conditioning module; the AD sampling conditioning module outputs an on-state resistance measured value R _on ：R _on ＝(2V _a -V _b )/I _ds In which V is _a Is the voltage of the cathode of the first diode, V _b For the output terminal voltage of the microcurrent source, I _ds Is the load current.

8. A power device junction temperature online real-time measurement method is characterized by comprising the following steps:

s1, acquiring sample data of the on-state resistance of a power device at a given temperature and a given load current by using the on-state resistance measuring circuit of one of claims 1 to 6;

s2, normalizing the sample data;

s3, constructing a training set by using the sample data after normalization processing;

s4, conducting on-state resistor R when the power device to be tested in the training set is conducted _on And the load current I _ds As input variable, the junction temperature T of the power device under test _j And as an output variable, training a fully-connected BP neural network to obtain a junction temperature measurement model.

9. The method for online real-time measurement of the junction temperature of the power device according to claim 8, wherein the sample data acquisition process of the on-state resistance comprises:

1) Putting the power device to be tested into a constant temperature box, standing for a set time to ensure that the power device to be tested reaches thermal balance, and considering the junction temperature T of the power device to be tested _j Consistent with a given temperature;

2) The power device to be measured is operated under each current level, and the on-state resistance R of the power device to be measured under each working condition is measured by the on-state resistance measuring circuit _on And a load current I _ds ；

3) Changing a given temperature value in the thermostat, and repeating the step 1) and the step 2) to obtain the on-state resistance of the power device at different given temperatures and different given load currents.

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

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