CN115508684A - Power device on-state resistance measuring circuit and junction temperature measuring method and system - Google Patents
Power device on-state resistance measuring circuit and junction temperature measuring method and system Download PDFInfo
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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
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 measuring circuit and junction temperature measuring method and system.
Background
As a new generation of wide bandgap semiconductor power device, the SiC-MOSFET power module has the advantages of high voltage, high frequency, high power density and the like, is distinguished from the existing power device, and has wide application prospect. However, as SiC-MOSFET power modules become more widely used, reliability issues during long-term operation become a focus of industry concern. The reliability and the service life of the SiC-MOSFET power module are in a close and inseparable relation with the junction temperature of a chip in the SiC-MOSFET power module, and thermal stress circulation caused by continuous fluctuation of the junction temperature in the module becomes a main cause of aging and failure of the device. The online real-time measurement of the junction temperature of the SiC-MOSFET power module is the basis of reliability evaluation, cost performance improvement, active heat control and state monitoring.
The existing junction temperature measuring methods mainly comprise optical non-contact measurement, physical contact measurement, thermal network prediction methods, finite element methods and thermosensitive electrical parameter sensing methods. The optical method requires opening the package of the module, is highly invasive and is not suitable for field application; the physical contact type measurement has lower cost, longer response time and low accuracy; the difficulty in the application of the heat network method is that the aging of devices causes the parameter offset of the heat network, and the measurement result generates errors; the thermosensitive inductance parameter method is to utilize external electrical parameters convenient for measurement to extract and monitor the junction temperature of the power module, does not need to change a module packaging structure, has high-speed response capability and strong on-line capability, and is widely applied due to the advantages of low cost, high response speed, non-invasiveness and the like.
Comprehensive comparison is carried out from the aspects of linearity, sensitivity, electrothermal coupling quantity, online measurement capacity, measurement complexity and the like, more electrothermal coupling quantity exists in dynamic thermosensitive inductive parameters represented by parameters such as turn-off delay time, turn-on current change rate and the like, and the links of offline calibration and online measurement are more complicated; the problem that the individual difference of chips is obvious exists in static thermosensitive inductance parameters such as threshold voltage and the like, and the aging drift phenomenon is serious, so that the difficulty is brought to a calibration link; the on-state resistor has the advantages of high linearity, high sensitivity and strong on-line capability, and can be used for efficiently measuring and monitoring junction temperature in a power electronic system. The key points of the difficult application of the on-state resistance method mainly lie in reducing the measurement error, improving the measurement resolution, establishing a high-precision junction temperature measurement model, solving the contradiction between wide range and high precision, between high-frequency switch and slow response, and avoiding the measurement link from being too complex so as to realize high measurement precision and high dynamic response measurement.
In the prior art, the on-state resistance is measured by measuring tools such as a graphic instrument, an oscilloscope and the like, the measuring method has the problems of insufficient resolution and low response speed, and the high precision and high response of measurement cannot be ensured.
In the traditional junction temperature measurement method, a temperature-on-state resistance curve is established through an off-line correction link, but a curve function formula obtained by adopting a fitting mode such as a traditional least square method cannot meet the requirement of high precision. The application key point of the on-state resistance method is mainly to solve the contradiction between wide range and high precision, high-frequency switching and slow response, although a model curve can be optimized by adopting intelligent algorithms such as a neural network and the like, the high-voltage and high-frequency working characteristics of the SiC-MOSFET power module increase the difficulty of on-state resistance measurement, and the problems of low measurement precision, low response speed and the like exist, so that the junction temperature measurement result has larger deviation, the on-line capability of junction temperature measurement can be influenced, and the defects of low precision, poor on-line capability and the like can not be fundamentally overcome.
Disclosure of Invention
The invention aims to solve the technical problem that aiming at the defects of the prior art, the invention provides the on-state resistance measuring circuit of the power device, and the junction temperature measuring method and system, so that the on-state resistance measuring precision and the response speed are improved.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a power device on-resistance measurement circuit, comprising:
the micro-current source is used for providing conduction 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.
When the device to be measured is in a turn-off state, the high-voltage blocking module blocks a hundred-volt level voltage, so that the measurement range is shortened, and the measurement precision is effectively improved; when the device to be measured is in a conducting state, the micro-current source provides conducting current for the high-voltage blocking module, and conducting state electric parameters of the device to be measured are transmitted to the input end of the operational amplifier at high speed and high precision, so that the accuracy of a measuring result is guaranteed; when the device to be measured is in a high-frequency switching state, the broadband and high-voltage slew rate characteristics of the on-state resistance measuring circuit meet the high-frequency requirement of measurement, and the high-speed response of the measurement is guaranteed. Therefore, the on-state resistance measuring circuit can effectively solve the contradiction between wide range and high precision in the prior art, avoid the contradiction between a high-frequency switch and slow response, and ensure the high precision and high dynamic response capability of on-state resistance measurement.
In the present invention, 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. When the device to be tested (namely the power device to be tested) is in an on state, the output current of the micro current source flows through the high-voltage diode and the device to be tested to flow into a reference ground, namely a source electrode of the device to be tested.
In the invention, the micro-current source is considered to be mainly used for providing conduction current for the high-voltage blocking module, and the conduction current is required to be milliampere in order to reduce the loss of a measuring link. The micro-current source adopts a topological structure of a mirror current source, has good symmetry, can control the output current by adjusting the divider resistor, has a simple structure, can ensure the stability of the output current of the micro-current source, and has good temperature compensation characteristics.
In the invention, 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. The measurement range is shortened and the precision is improved by blocking the hundred-volt voltage when the device is turned off by the first diode with high voltage resistance.
In the invention, in consideration of the influence of the forward conduction voltage drop of the first diode on the measurement result, in order to eliminate the influence, a second diode is connected between the cathode of the first diode and the drain electrode of the power device to be measured; 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.
In the invention, because the device to be tested is in a high-frequency switching state, voltage spikes can occur in the process of switching on and off, impact is generated on the input end of an operational amplifier (operational amplifier), the device is damaged, and the operation reliability is reduced, therefore, in order to prevent the voltage of the input end of the operational amplifier from exceeding the normal working range, a clamping circuit is connected between the output end of the high-voltage blocking module and the operational amplifier.
The clamping 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. The clamping circuit of the invention adopts the diode to limit the input voltage, so that the operational amplifier works in a normal range, and the clamping circuit has simple structure and high reliability.
The output end of the operational amplifier is connected with the AD sampling conditioning module; the AD sampling conditioning module outputs an on-state resistance measured value 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 voltage of the micro-current source, I ds Is the load current.
The invention also provides an online real-time measurement method for the junction temperature of the power device, which comprises 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;
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.
The invention can measure the on-state resistance in real time, can measure the junction temperature of the power module (power device) in real time on line in the running process of a 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 resistor comprises the following steps:
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 In accordance 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.
The acquisition of the sample data belongs to a non-invasive process, does not influence the practical engineering application of a device to be measured, can acquire the sample data while the power electronic system is in normal operation, and lays a foundation for linearity and instantaneity of junction temperature extraction.
The invention also provides an online real-time measurement system for the junction temperature of the power device, which comprises a memory, a processor and a computer program stored on the memory; the processor executes the computer program to implement the steps of the above-described measuring method of the present invention.
Compared with the prior art, the invention has the following beneficial effects: 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 in real time on line in the operation process of a power electronic system. The contradiction between the wide range and the high precision of the measuring equipment is solved through the on-state resistance measuring module, 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; obtaining data of thermosensitive parameters such as on-state resistance, load current and the like through a single pulse calibration link, and further establishing a junction temperature online measurement model through a full-connection neural network prediction model; the on-state resistance and the load current are collected in real time and input into the junction temperature online measurement model, and the junction temperature fluctuation condition is displayed in real time through an upper computer interface, so that the high-precision junction temperature online real-time measurement is realized. The invention can truly and accurately reflect the junction temperature fluctuation of the power module, particularly the SiC-MOSFET power module, provides important basis for reliability evaluation, service life prediction and health management of the power module, is favorable for ensuring the reliable operation of a power electronic system, and has strong universality.
Drawings
Fig. 1 is a circuit diagram of an on-state resistance measuring module in the on-line real-time temperature measuring system in embodiment 1 of the present invention;
FIG. 2 is a schematic structural diagram of an on-line real-time temperature measurement system in embodiment 2 of the present invention;
FIG. 3 is a block diagram of a control module of the on-line real-time temperature measurement system in embodiment 2 of the present invention;
FIG. 4 is a neural network training flowchart of a junction temperature model building module in the on-line real-time measurement system of junction temperature in embodiment 3 of the present invention;
fig. 5 is a junction temperature model visualization curved surface based on a fully-connected neural network in embodiment 3 of the present invention;
FIG. 6 is a junction temperature real-time monitoring interface of the SiC-MOSFET power module in embodiment 3 of the present invention;
fig. 7 is a comparison between the measured junction temperature and the simulated junction temperature of the on-line real-time junction temperature measurement system in embodiment 3 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As used herein, the terms "first," "second," and the like, are not intended to imply any order, quantity, or importance, but rather are used to distinguish one element from another. As used herein, the terms "a," "an," and other similar terms are not intended to mean that there is only one of the referenced item, but rather that the pertinent description is directed to only one of the referenced items 2, which may have one or more of those items. As used herein, the terms "comprise," "include," and other similar words are intended to refer to logical interrelationships and are not to be construed as representing spatial structural relationships. For example, "a includes B" is intended to mean that logically B belongs to a, and not that spatially B is located inside a. Furthermore, the terms "comprising," "including," and other similar words are to be construed as open-ended, rather than closed-ended. For example, "a includes B" is intended to mean that B belongs to a, but B does not necessarily constitute all of a, and a may also include other elements such as C, D, E, and the like.
Example 1
Fig. 1 is a circuit diagram of an on-state resistance measurement module 50 of a junction temperature online real-time measurement system provided in 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 clamping part 503 (clamping circuit), and an operation part 504.
Specifically, the micro current source portion 501 supplies the on current to the high-voltage blocking diode through the mirror current source, mainly by the voltage source V SS A first to a fourth triode T 1 、T 2 、T 3 、T 4 And a voltage dividing resistor R 1 (first voltage-dividing resistor), R 2 (second voltage-dividing resistor). When the device to be tested is in an off state, the micro current source outputs current to flow through the high-voltage diode D 1B A clamping diode D 2B And a voltage source V of the clamping section DD Forming a current loop; when the device to be tested is in an 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 dut flow into the reference ground. The reference ground in the circuit of the embodiment is the source of the device under test. The high voltage blocking portion 502 is passed through a high voltage resistant diode D 1A And blocking the hundred-volt voltage when the device is turned off so as to shorten the measuring range and improve the precision. Considering the diode D 1A The influence of forward conduction voltage drop on the measurement result is added with a diode D 1B Diode D 1A 、D 1B The same parameters are taken. Measured value V of conduction voltage drop of device to be tested ds Calculating as shown in formula (1):
the clamping section 503 includes a voltage source V DD And a clamping diode D 2A (third diode), D 2B (fourth diode), this part of main function is to protect the input end voltage of the operational amplifier to not exceed the normal operating range. Because the device to be tested is in a high-frequency switching state, voltage spikes can occur in the switching-on and switching-off processes, so that the impact on the operational amplifier input is generated, the device is damaged, and the operation reliability is reduced. Therefore, the input end of the operational amplifier adopts a clamping diode to limit the input voltage, so that the operational amplifier works in a normal range. The operation part 504 is mainly composed of an operational amplification link with a gain of 1, and the operational amplification link is mainly used for counteracting the influence of the forward conduction voltage of the high-voltage diode on the measurement result through operation, so that the operation of the formula (1) is realized. The input resistor and the feedback resistor are 1k omega, the formula (2) can be obtained by knowledge of the circuit principle, and the voltage of the output end of the operational amplifier is the value of the conduction voltage drop. After AD sampling, the conduction voltage drop and the load current are calculated to obtain an on-state resistance measurement value R on So as to realize the 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 junction temperature of a SiC-MOSFET power module based on-state resistance change provided in embodiment 2 of the present invention includes: the system comprises a main power circuit 10, a constant-temperature heating module 20, a control module 30, a load module 40, an on-state resistance measuring module 50, a junction temperature model building module 60 and a junction temperature on-line measuring module 70.
Specifically, the main power circuit 10 is configured to provide electrical connection for the SiC-MOSFET power module, so that the device under test can operate in a single-pulse calibration operating mode or a single-phase inverter operating mode; the constant temperature heating module 20 is used for providing an ambient temperature for the device to be tested so that the junction temperature of the device to be tested is a given temperature value; a control module 30, configured to control turning on and off of the device to be tested, so as to implement switching among multiple operating modes, as shown in fig. 3; the load module 40 is electrically connected with the main power circuit 10 and used for changing the operation condition of the device to be tested, so that the device to be tested can operate at different current levels; the on-state resistance measuring module 50 is used for measuring the on-state resistance and related electrical parameters of the SiC-MOSFET power module at high precision and high response speed so as to realize online real-time high-precision junction temperature measurement; the junction temperature model building module 60 obtains data of thermosensitive parameters such as on-state resistance, load current and the like through a single pulse calibration link, and further builds a junction temperature online measurement model through a neural network prediction model; the junction temperature online measurement module 70 collects the on-state resistance and the load current in real time and inputs the on-state resistance and the load current into the junction temperature online measurement model, and displays the junction temperature fluctuation condition in real time through an upper computer interface, so that the high-precision junction temperature online real-time measurement is realized.
The junction temperature model building module 60 obtains data of thermosensitive parameters such as on-state resistance, load current and the like through a single pulse calibration link, and then builds a junction temperature online measurement model through a neural network prediction model. Wherein the single-pulse calibration mode is used for obtaining each load current I ds Lower on-state resistance R on And junction temperature T j According to the relation curve between the SiC-MOSFET power module and the MOSFET power module, the SiC-MOSFET power module can generate self-heating due to power loss when working current is introduced, the heating is more serious when the conduction time is longer, and the junction temperature measurement result generates errors due to the phenomenon, so that the influence caused by the self-heating effect is reduced by adopting the single-pulse trigger circuit, and the influence of the self-heating effect of the device on the junction temperature can be ignored. The single-pulse calibration working mode adopts a single-pulse trigger circuit to reduce the spontaneous heating effect and ensure that the influence of the spontaneous heating effect on the junction temperature can be ignored; the temperature of the constant-temperature heating module is given, the SiC-MOSFET power module is heated to be in thermal balance, and the junction temperature of the SiC-MOSFET power module is considered to be consistent with the given temperature; and simultaneously adjusting the load module to enable the SiC-MOSFET power module to operate at different current levels, and recording a series of temperature, load current and on-state resistance data. The specific implementation steps of the single-pulse calibration working mode are as follows:
the method comprises the following steps: starting the constant-temperature heating module 20, setting the initial temperature to be 20 ℃, placing the device to be tested into a constant-temperature box, standing for 15-20 minutes to ensure that the device to be tested reaches thermal balance, and considering the temperature T as junction temperature j Consistent with a given temperature;
step two: the load module 40 is arranged to enable the device to be tested to operate at each current level, the control module 30 issues a switching signal of the device to be tested to enable the device to be tested to be switched on at a certain current level, and the on-state resistance R of the device to be tested under each working condition is recorded through the on-state resistance measuring module 50 on And a load current I ds ；
Step three: on-state resistance R of device to be tested under various working conditions at initial temperature on And a load current I ds After the recording is finished, changing the given temperature value of the constant temperature heating module 20, and repeating the first step and the second step to obtain different temperatures and different currents I ds On-resistance R of lower device under test on 。
Example 3
In this embodiment, sample data of an on-state resistance at a given temperature and a given load current is obtained according to a single-pulse calibration working mode, a junction temperature measurement model based on a fully-connected neural network is built through a tenserflow framework in a pynorm compiling environment, as shown in fig. 4, a neural network training flow chart is shown, and specific implementation steps are as follows:
the method comprises the following steps: and (6) normalizing the data. Since the activation function of the neural network output layer has value range limitation, target data of network training needs to be mapped to the value range of the activation function, and before sample data is input into the model, feature normalization processing needs to be performed on the sample data. The system selects a bipolar S-shaped activation function to carry out linear transformation, and maps the calculation result of the original data between [0,1 ];
step two: and loading the processed data. Selecting the on-state resistance R of the device to be tested when the device is switched on on And the load current I ds As input variable, the junction temperature T of the power module j As an output variable, based on the processed data, randomly selecting 70% of sample data as a training set to train the model, and using the remaining 30% of sample data as a test set to verify the accuracy of the model;
step three: and (5) network initialization setting. The selected input layer is 1 layer and comprises 2 neurons; the hidden layer is 3 layers and respectively comprises 64 neurons, 32 neurons and 16 neurons; the output layer is 1 layer, and the learning rate is set to be 0.001;
step four: training the network and predicting the result. Loading processed sample data, randomly selecting 70% of the sample data as a training set, and inputting the sample data into a network to train a full-connection BP neural network; taking the remaining 30% of sample data as a verification set, obtaining a predicted value by using the trained neural network, and using a junction temperature model visualization curve based on the fully-connected neural network as shown in fig. 5.
Step five: and (4) error evaluation. And performing anti-normalization processing on the output result, comparing the output result with a theoretical junction temperature value, calculating a difference value between an estimation result output by the model and an expected output result, and selecting a Maximum Absolute Error (MAE), a Mean Square Error (MSE) and an Accuracy (Accuracy) as evaluation criteria to verify the effectiveness of the model and quantify the Accuracy of the estimation model, wherein the more the Maximum Absolute Error (MAE) and the Mean Square Error (MSE) obtained from the operation result of the model are close to 0, the more the Accuracy (Accuracy) is close to 1, the higher the prediction Accuracy of the model on the junction temperature of the IGBT power module is, and the more reliable the model is. Through evaluation, the maximum absolute error MAE of the junction temperature model of the system is not more than 0.0086, the mean square error MSE is not more than 0.21%, the Accuracy rate Accuracy is between 99.78% and 100%, and the reliability of the model is high.
The junction temperature online measurement module 80 inputs the on-state resistance and other heat-sensitive parameters acquired in real time in the single-phase inverter working mode into the junction temperature online measurement model in the single-phase inverter working mode, and displays the junction temperature fluctuation condition in real time through an upper computer interface, so that the high-precision junction temperature online real-time measurement is realized.
The working principle of the working mode of the single-phase inverter is as follows: the control module issues a modulation signal to control the high-frequency switching action of the power module to be tested, the direct-current side voltage is input to a single-phase inversion main circuit formed by the power module to be tested after voltage stabilization and filtering, and is connected with the load module to output an alternating-current waveform after low-pass filtering; meanwhile, the on-state resistance measuring module is directly connected with the drain electrode of the device to be measured, so that high-precision extraction of the on-state resistance is realized, and the on-state resistance measuring module is used for junction temperature extraction of the junction temperature on-line measuring module.
The single-phase inverter working mode is used for realizing online real-time measurement of junction temperature of the SiC-MOSFET power module under the actual inverter working condition. The working principle of the mode is as follows:
the method comprises the following steps: the control module 30 issues a modulation signal to control the high-frequency switching action of the device to be tested, the voltage on the direct current side is input to a single-phase inverter main circuit formed by the SiC-MOSFET power module to be tested after voltage stabilization and filtering, and the single-phase inverter main circuit is connected with the load module 40 after low-pass filtering to output an alternating current waveform.
Step two: the on-resistance measurement module 50 is directly connected to the drain of the dut via the high voltage blocking portion 502. The module has the main functions of solving the contradiction between the wide range and the high precision of the measuring equipment and ensuring the high-speed response capability of the measurement. The on-state resistance of the device to be measured can be measured with high precision and high response speed by the on-state resistance measuring module 50, and meanwhile, the switching peak is clamped, so that the impact on a later-stage device is avoided, and the reliable operation of the junction temperature on-line real-time measuring system is ensured.
Step three: and inputting the acquired on-state resistance and other heat-sensitive parameters into the junction temperature online measurement model in real time, and displaying the junction temperature fluctuation condition in real time through an upper computer interface to realize high-precision junction temperature online real-time measurement. Fig. 6 shows a junction temperature real-time monitoring interface of the SiC-MOSFET power module, which is used for monitoring junction temperature swings and the highest junction temperature of the SiC-MOSFET power module in a plurality of fundamental frequency periods.
An electric-heating simulation model is established by using PLECS power electronic simulation software, a theoretical value of junction temperature under a given task working condition is obtained through simulation, and comparison of actually-measured junction temperature and simulated junction temperature of the system in a fundamental frequency period is shown in FIG. 7. The fluctuation trend and amplitude of the actually measured junction temperature are basically consistent with those of a theoretical simulation result, the bonding effect of the actually measured junction temperature and the theoretical simulation result is good, the absolute error between the actually measured junction temperature and the simulated junction temperature is not more than 0.3 ℃, and the relative error is not more than 1.5%. Therefore, the system of the scheme of the invention can truly and accurately reflect junction temperature fluctuation of the SiC-MOSFET power module to be tested, provides important basis for reliability evaluation, service life prediction and health management of the SiC-MOSFET power module, and is beneficial to ensuring reliable operation of a power electronic system.
The above disclosure is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or modifications within the technical scope of the present invention, and shall be covered by the 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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