Method for generating junction temperature calibration curve of SiCMOSFET device, junction temperature evaluation method and system

Abstract

The present invention discloses a method for generating a junction temperature calibration curve of a SiC MOSFET device, as well as a junction temperature evaluation method and system thereof. First, the square root of the transconductance of the SiC MOSFET device at different junction temperatures is obtained; then, the relationship between the square root of the transconductance and the temperature is linearly fitted to obtain a linear relationship between the square root of the transconductance and the temperature, and a junction temperature calibration curve is established from this relationship; finally, the junction temperature of the device is obtained by measuring the square root of the transconductance of the device to be evaluated and querying the calibration curve or calculating by the linear relationship. This method overcomes the disadvantages of the traditional junction temperature measurement method for power semiconductor devices, such as cumbersome process, low accuracy, and difficulty in online application. The square root of the transconductance of the SiC MOSFET device has a linear relationship with the junction temperature, and the accuracy is relatively high during junction temperature evaluation, and it can be applied online, enabling accurate evaluation of the device junction temperature; at the same time, this method can measure the device junction temperature fluctuation caused by a single switching cycle; through the accurate evaluation of the device junction temperature, the operation reliability of the device and the economy of research and development can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical fields of the reliability of power semiconductor devices and power electronic converters, and particularly to a method for generating a junction temperature calibration curve of a SiC MOSFET device, a method for evaluating the junction temperature, and a system therefor. Background Art

[0002] With the rapid development of power semiconductor devices, their reliability issues have attracted wide attention in the academic and industrial fields. As a typical representative of emerging wide-bandgap semiconductor material devices, SiC MOSFETs have advantages such as high temperature resistance, high voltage resistance, high switching frequency, and low on-resistance. However, due to the immaturity of manufacturing and packaging processes, their operating conditions far from reach the theoretical limit of SiC materials, and it is necessary to further study their failure mechanisms to improve the deficiencies in manufacturing processes and packaging designs, and give full play to the advantages of SiC materials as much as possible. The failure of power devices is closely related to their junction temperature. Therefore, the junction temperature of power devices can be used as a basis for technical fields such as device reliability evaluation, condition monitoring, and health management. Junction temperature measurement is an important basis and prerequisite for research and development in these fields. Therefore, it is very crucial to accurately and quickly obtain the junction temperature of the device.

[0003] Currently, the methods for obtaining the junction temperature of power devices mainly include four categories: physical contact method, optical method, thermal network model method, and temperature-sensitive electrical parameter method. The temperature-sensitive electrical parameter method (TSEP) is considered to be one of the most promising junction temperature measurement methods, which has advantages such as fast response speed, non-invasive, and can achieve online measurement. In existing research, the body diode voltage drop of SiC MOSFETs can be used for their junction temperature measurement, which has certain advantages in linearity and sensitivity. However, in most cases, the body diode is prohibited from conducting or the conduction time is very short, so its online application has great difficulties. In the research on the steady-state thermal resistance measurement of Darlington tubes based on the electrical method that has been proposed, it is also necessary to measure their junction temperature, and the temperature dependence of the forward voltage drop of its PN junction is used to achieve the purpose of junction temperature measurement. However, its measurement circuit is separated from the working circuit, resulting in the measured junction temperature not being the real-time junction temperature, so junction temperature error correction is required, which makes the measurement work complicated and cumbersome. When using the threshold voltage as the temperature-sensitive electrical parameter for junction temperature measurement, the requirement for the synchronization of voltage and current sampling is very high, and the high switching speed of SiC MOSFETs makes the sampling more difficult, so its application difficulty is very high. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for generating a junction temperature calibration curve of a SiC MOSFET device, a method for evaluating the junction temperature, and a system therefor. This method generates the junction temperature calibration curve of the device and uses the calibration curve to achieve real-time measurement of the device junction temperature and its changes.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The method for generating the junction temperature calibration curve of the SiC MOSFET device provided by the present invention includes the following steps:

[0007] Obtain the transconductance parameter values of the SiC MOSFET device at different junction temperatures;

[0008] Fit the transconductance parameter values and temperature to obtain the relationship curve between the transconductance parameter values and temperature.

[0009] Further, the transconductance parameter value refers to the arithmetic square root of the transconductance of the SiC MOSFET device;

[0010] Further, the transconductance is calculated according to the following formula:

[0011]

[0012] where, ΔI D represents the increment of the drain current I D ;

[0013] ΔV GS represents the increment of the gate drive voltage V GS that causes the increment of the drain current, and the value of ΔV GS is within a preset range;

[0014] Further, the relationship curve is the transconductance arithmetic square root -junction temperature T j calibration curve, and the relationship curve is specifically formed according to the following process:

[0015] Apply a gate drive voltage to the SiC MOSFET gate, denoted as the first drive voltage V CS1 , and obtain the drain current at this time, denoted as the first drain current I D1 ;

[0016] Change the drive voltage and denote it as the second drive voltage V GS2 , it is necessary to ensure that the difference from V GS to V GS is within a preset range, and at the same time record the drain current at this time, denoted as the second drain current I D2 ;

[0017] Calculate the transconductance value at this test temperature, and further solve to obtain the transconductance arithmetic square root

[0018] Repeatedly test the SiC MOSFET at different junction temperatures to obtain all the square root values of the transconductance at preset different test temperatures. Perform a linear fit on the relationship between the square root value of the transconductance and the temperature to obtain its fitting linear relationship formula. The square root of the transconductance obtained from the fitting linear relationship formula and the junction temperature T j of the linear relationship curve, that is, the calibration curve.

[0019] The junction temperature evaluation method based on the device junction temperature calibration curve provided by the present invention includes the following steps:

[0020] Obtain the junction temperature calibration curve of the device generated by using the method described in any one of claims 1-4 above;

[0021] Test the transconductance of the device to be evaluated and calculate the real-time square root value of the device transconductance;

[0022] Query the device transconductance square root junction temperature calibration curve according to the real-time square root value of the transconductance to obtain the device junction temperature.

[0023] Furthermore, the transconductance of the device to be evaluated is tested in the following manner:

[0024] Set the drive voltage of the SiC MOSFET device and measure the drain current value corresponding to the drive voltage;

[0025] Calculate the transconductance value and the square root of the transconductance;

[0026] Query the junction temperature corresponding to the device transconductance square root junction temperature calibration curve according to the square root of the transconductance.

[0027] Furthermore, the setting of the drive voltage of the SiC MOSFET device is carried out according to the preset drive voltage value in the device junction temperature calibration curve.

[0028] Furthermore, the drive voltage is the gate drive voltage during the device turn-on process, and the drain current value is the corresponding drain current during the turn-on process; or

[0029] The drive voltage is the gate drive voltage during the device turn-off process, and the drain current value is the corresponding drain current during the turn-off process.

[0030] The method for measuring the device junction temperature fluctuation of the SiC MOSFET under a single switching cycle provided by the present invention is measured according to the following steps:

[0031] Use the method described in claim 5 to measure and evaluate the junction temperature T at the start of conduction of the same switching cycle of the device jmin and the junction temperature T at the end of conduction jmax, calculate the difference between the start and end of conduction to obtain the junction temperature fluctuation during the conduction process in a single switching cycle; or

[0032] Use the method described in claim 5 to measure and evaluate the junction temperature T at the start of turn-off in the same switching cycle of the device jmax and the junction temperature T at the end of turn-off jmin , calculate the difference between the start and end of turn-off to obtain the junction temperature fluctuation during the turn-off process in a single switching cycle.

[0033] The SiC MOSFET junction temperature evaluation system based on device transconductance measurement provided by the present invention includes a main circuit module, a gate drive module, a temperature regulation module, a voltage acquisition module, a current acquisition module, a data processing module, and a junction temperature evaluation module;

[0034] The main circuit module is used to carry the circuit topology for the operation of the SiC MOSFET;

[0035] The gate drive module is used to provide corresponding gate drive signals for the SiC MOSFET;

[0036] The temperature regulation module is used to provide different test temperatures for the device;

[0037] The voltage acquisition module is used to acquire voltage-related data required for obtaining the calibration curve;

[0038] The current acquisition module is used to acquire current-related data required for obtaining the calibration curve;

[0039] The data processing module is used to calculate, linearly fit, and establish a calibration curve for the acquired data;

[0040] The junction temperature evaluation module is used to look up the calibration curve according to the square root of the transconductance and calculate by the linear relationship formula to obtain the junction temperature evaluation report of the device.

[0041] The beneficial effects of the present invention are as follows:

[0042] The method for generating the junction temperature calibration curve of the SiC MOSFET device provided by the present invention, its junction temperature evaluation method and system, measure the junction temperature of the SiC MOSFET based on the curve of the square root of the device transconductance and the junction temperature. By measuring the square root of the transconductance at different junction temperatures and fitting to obtain the linear relationship formula between the square root of the device transconductance and the junction temperature, establish a junction temperature calibration curve based on the linear relationship formula, and then query the calibration curve according to the square root of the transconductance of the device to be measured to obtain the temperature corresponding to this value, that is, the junction temperature evaluation value, thus completing the junction temperature evaluation, realizing the fast and accurate evaluation of the device junction temperature, and overcoming the disadvantages of the traditional method for measuring the junction temperature of power semiconductor devices, such as cumbersome process, low precision, and difficulty in on-line application.

[0043] By measuring the device transconductance at different test temperatures, further solve the transconductance to obtain its arithmetic square root; by linearly fitting the arithmetic square root of the transconductance of the SiC MOSFET at all test temperatures, obtain the linear relationship between the arithmetic square root of the transconductance and the temperature; when evaluating the junction temperature, by obtaining the value of the arithmetic square root of the device transconductance in real time, the junction temperature can be quickly determined according to the fitted linear relationship or the junction temperature calibration curve. The fitting curve obtained by this method has good linearity and high precision in junction temperature evaluation, can be applied online, and can accurately evaluate the device junction temperature; at the same time, this method can measure the device junction temperature fluctuation caused by a single switching cycle.

[0044] This method can effectively evaluate and measure the real-time junction temperature of the device. This method has obvious advantages in terms of comprehensive effects such as linearity, sensitivity, and ease of online application; at the same time, this method can measure the device junction temperature fluctuation caused by a single switching cycle; and in terms of measurement sensitivity, it can be adjusted within a certain range according to needs. By accurately evaluating the device junction temperature, the operation reliability of the device and the economy of research and development can be effectively improved.

[0045] The magnitude of the temperature-sensitive electrical parameter can be appropriately adjusted, so that its sensitivity can be adjusted within a certain range. The transconductance of the device can be represented by the slope of its transfer characteristic curve. It can be seen from the transfer characteristic curve that its slope (transconductance) is different at different operating points, that is, the arithmetic square root of the transconductance is also different at different operating points. Therefore, within a certain range, the magnitude of the temperature-sensitive electrical parameter can be changed by changing the operating point (gate drive voltage) for obtaining the calibration curve, and then the magnitude of its sensitivity can be adjusted.

[0046] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to make the objectives, technical solutions, and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0048] Figure 1 It is a flowchart for establishing a junction temperature calibration curve.

[0049] Figure 2 It is a schematic diagram of the junction temperature evaluation process for the device to be tested.

[0050] Figure 3 It is a junction temperature evaluation system.

[0051] Figure 4 Data acquisition principle for transconductance calculation.

[0052] Figure 5 Experimental measurement and fitting calibration curve. Specific implementation mode

[0053] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the specific embodiments cited do not limit the present invention.

[0054] Embodiment 1

[0055] As Figure 1 shown, Figure 1 The flowchart for establishing the junction temperature calibration curve. The method for generating the junction temperature calibration curve of the SiC MOSFET device provided in this embodiment includes the following steps:

[0056] Obtain the transconductance parameter values of the SiC MOSFET device at different junction temperatures;

[0057] Fit the transconductance parameter values and temperature to obtain the relationship curve between the transconductance parameter values and temperature;

[0058] The transconductance parameter value in this embodiment refers to the arithmetic square root of the transconductance of the SiC MOSFET device;

[0059] The transconductance of the SiC MOSFET in this embodiment characterizes the control ability of the gate drive voltage on the drain current, and is described from the microscopic physical structure of the device as:

[0060]

[0061] In the formula: Z is the channel width; μ ni is the inversion channel electron mobility; C OX is the characteristic capacitance of the oxide layer; L CH is the channel length; V GS is the gate drive voltage; V TH is the threshold voltage of the device.

[0062] The transconductance in this embodiment is calculated according to the following formula:

[0063]

[0064] Among them, ΔI D represents the increment of the drain current I D ;

[0065] ΔV GS represents the increment of the gate drive voltage V GS that causes the increment of the drain current, and ΔVGS The value is within a preset range, which is a tiny increment range and can be determined according to the actual situation during actual setting. In this embodiment, ΔV GS has a value range of (0.1V to 0.5V).

[0066] In this embodiment, from the transfer characteristic curve of the SiC MOSFET, the transconductance is the slope of its transfer characteristic curve, and its calculated value is the ratio of the tiny increment of the drain current I D to the corresponding tiny increment of the gate drive voltage V GS that causes the tiny increment of the drain current.

[0067] The relationship curve in this embodiment is the square root of the transconductance -junction temperature T j calibration curve;

[0068] The process of obtaining the relationship curve in this embodiment is as follows:

[0069] Apply a gate drive voltage slightly greater than its threshold voltage to the gate of the SiC MOSFET, denoted as the first drive voltage V GS , and obtain the drain current at this time, denoted as the first drain current I D1 ;

[0070] Change the drive voltage and denote it as the second drive voltage V GS , and it is necessary to ensure that the difference from V GS1 to V GS2 is very small. At the same time, record the drain current at this time, denoted as the second drain current I D2 ;

[0071] Calculate the transconductance value at this test temperature according to equation (2), and further solve to obtain the square root of the transconductance

[0072] Repeat the above steps for the SiC MOSFET at different test temperatures (junction temperatures), and the square root of the transconductance values at all test temperatures can be obtained. Perform a linear fit on the square root of the transconductance values and the temperature at all test temperatures, and a linear relationship between the square root of the transconductance and the junction temperature can be obtained. Based on this relationship, establish the square root of the transconductance and the linear relationship curve of the junction temperature T j , that is, the calibration curve, and the slope of the curve represents its temperature coefficient.

[0073] The fitting curve obtained by the method provided in this embodiment has good linearity, high accuracy in junction temperature evaluation, can be applied online, and can accurately evaluate the device junction temperature; at the same time, this method can measure the device junction temperature fluctuation caused by a single switching cycle.

[0074] The temperature-sensitive electrical parameter (square root of transconductance) provided in this embodiment can be used to extract the junction temperature of SiC MOSFETs. This method can effectively evaluate and measure the real-time junction temperature of the device. Compared with other existing research methods, this method has obvious advantages in terms of comprehensive effects such as linearity, sensitivity, and ease of on-line application. At the same time, this method can measure the device junction temperature fluctuation caused by a single switching cycle. And in terms of measurement sensitivity, it can be adjusted within a certain range as needed. By accurately evaluating the device junction temperature, the operation reliability of the device and the economy of research and development can be effectively improved.

[0075] The method provided in this embodiment is based on the fact that when the temperature is the only variable, there is an obvious corresponding relationship between the transconductance of the SiC MOSFET device and the device junction temperature. Set the temperature gradient, obtain the device transconductance values at different test temperatures (junction temperatures), and further perform data processing to solve the transconductance to obtain its square root value. Perform a linear fit on the square root of the transconductance values of the device at all test temperatures to obtain the fitting linear relationship between the square root of the transconductance and the temperature (junction temperature). The curve established by this linear relationship is the junction temperature calibration curve, and the curve slope is the temperature coefficient of the square root of the transconductance. Using this linear relationship, obtain the square root of the transconductance value of the SiC MOSFET device at any temperature within the test temperature range. According to this value and the fitting linear relationship or the junction temperature calibration curve, the junction temperature of the device can be quickly and real-time evaluated, so as to achieve the purpose of junction temperature measurement.

[0076] In this embodiment, when obtaining the square root of the transconductance - Junction temperature T j The calibration curve can be obtained through a double-pulse test experiment. The double-pulse test experiment is widely used in the research of the switching process and dynamic performance evaluation of power semiconductor devices. This circuit topology is simple, and the chip only undergoes two power cycles, which can effectively reduce the self-heating phenomenon of the chip during the test and make the junction temperature as consistent with the test temperature as possible, so that the established calibration curve is more accurate. Therefore, this circuit topology can be used when obtaining the calibration curve.

[0077] Embodiment 2

[0078] As Figure 2 shown, Figure 2 is a schematic diagram of the junction temperature evaluation process of the device to be tested. The process of generating the junction temperature calibration curve of the device is obtained according to the above method. The junction temperature evaluation method based on the junction temperature calibration curve of the device provided in this embodiment includes the following steps:

[0079] Obtain the junction temperature calibration curve of the device according to the above method;

[0080] Test the transconductance of the device to be evaluated and calculate the real-time square root value of the device transconductance;

[0081] The junction temperature of the device is obtained by querying the junction temperature calibration curve of the device according to the real-time transconductance arithmetic square root value.

[0082] In this embodiment, the transconductance of the device to be evaluated is tested in the following manner:

[0083] Set the driving voltage of the SiC MOSFET device and measure the drain current value corresponding to the driving voltage;

[0084] Calculate the transconductance value and the arithmetic square root of the transconductance;

[0085] Query the junction temperature corresponding to the transconductance arithmetic square root junction temperature calibration curve of the device according to the arithmetic square root of the transconductance.

[0086] In this embodiment, the driving voltage of the SiC MOSFET device is set according to the preset driving voltage value in the junction temperature calibration curve of the device.

[0087] In this embodiment, the curve slope of the transconductance arithmetic square root junction temperature calibration curve of the device represents the temperature coefficient.

[0088] In this embodiment, since the transconductance value of the SiC MOSFET device can be calculated by formula (2) at a certain junction temperature, and from the transfer characteristic curve of the device, it can be known that the transconductance value of the SiC MOSFET is the slope of the transfer characteristic curve, and its magnitude is not a fixed value but is directly related to the magnitude of the gate driving voltage. Therefore, in order to ensure that the calibration curve applied to the test device is consistent with the actual process to be measured, it is necessary to ensure that two different preset driving voltages are consistent with the two driving voltages in the obtained calibration curve, and then measure the drain current values corresponding to the two driving voltages respectively.

[0089] In this embodiment, after obtaining the transconductance arithmetic square root value of the device, the calibration curve is searched according to the magnitude of this value. According to the linear relationship of the calibration curve, the temperature corresponding to this value on the calibration curve is the current junction temperature of the device, so that the junction temperature evaluation value of the device can be obtained and the junction temperature measurement is completed.

[0090] The junction temperature calibration curve provided in this embodiment can measure the minimum junction temperature and the maximum junction temperature within one switching period through the junction temperature evaluation method based on transconductance measurement, so that the junction temperature fluctuation range within a single switching period can be obtained.

[0091] Embodiment 3

[0092] As Figure 3 shown, Figure 3It is a block diagram of the junction temperature evaluation system. The SiC MOSFET junction temperature evaluation system based on device transconductance measurement provided in this embodiment includes a main circuit module, a gate drive module, a temperature regulation module, a voltage acquisition module, a current acquisition module, a data processing module, and a junction temperature evaluation module;

[0093] The main circuit module is used to carry the circuit topology for the operation of the SiC MOSFET. This main circuit module is the circuit topology for different application scenarios of the SiC MOSFET, such as a Buck converter, etc.;

[0094] The gate drive module is used to provide corresponding gate drive signals for the SiC MOSFET. The generation of the gate drive voltage signal can be implemented by a DSP or RT-Lab, etc. This module also includes corresponding hardware circuits;

[0095] The temperature regulation module is used to provide different test temperatures for the device to ensure that the device can reach different preset test temperatures. The temperature regulation module includes a heating plate and a temperature regulator for controlling the temperature of the heating plate, such as the PXF5 temperature regulator of Fuji Electric;

[0096] The voltage acquisition module is used to acquire voltage-related data required for obtaining the calibration curve, which can be implemented by a high-precision oscilloscope;

[0097] The current acquisition module is used to acquire current-related data required for obtaining the calibration curve, which can be jointly implemented by a high-frequency current probe and a high-precision oscilloscope;

[0098] The data processing module is used to calculate, linearly fit, and establish a calibration curve for the acquired data;

[0099] The junction temperature evaluation module is used to look up the calibration curve according to the square root of the transconductance and calculate by a linear relationship to obtain the junction temperature evaluation report of the device.

[0100] In this embodiment, a SiC MOSFET chip from manufacturer Rohm is used for case verification. The selected chip model is SCT3060AL. The rated voltage of this chip is 650V, the rated current is 39A, and the on-state current is 60mΩ.

[0101] According to the steps described in this method, it is necessary to obtain the square root value of the transconductance of the SiC MOSFET at different test temperatures.

[0102] First, use formula (2) to calculate and obtain its transconductance value. The principle of obtaining the data required for transconductance calculation is as Figure 4 shown, Figure 4 It is the principle of obtaining data for transconductance calculation, where V GS1 and V GS2are the first driving voltage and the second driving voltage respectively, and the corresponding I D1 and I D2 are the first drain current and the second drain current respectively;

[0103] According to the obtained data, the transconductance value can be obtained from formula (2),

[0104] and further solve the transconductance to obtain the arithmetic square root of the transconductance.

[0105] As described in this method, the final calibration curve of the device turn-on process obtained in this case experiment is as Figure 5 shown, Figure 5 which are the experimental measurement results and the fitted calibration curve. The relationship between the arithmetic square root of the device transconductance and the junction temperature obtained under different test temperature experiments is shown by the experimental measurement points in the figure; further, the arithmetic square root of the transconductance and the temperature at all test temperatures are linearly fitted, and the fitted calibration curve is shown by the fitted curve in the figure. The linear relationship of the curve obtained in this case is:

[0106]

[0107] From the curve slope, it can be seen that the temperature coefficient of the arithmetic square root of the transconductance of the SiC MOSFET in this case application is 0.004696 S / °C = 4.696 mS / °C.

[0108] Therefore, the calibration curves between the arithmetic square root of the transconductance of the SiC MOSFET and the junction temperature can all be fitted into the following form:

[0109]

[0110] where a and b are the fitting coefficients under different working conditions.

[0111] Finally, obtain the arithmetic square root value of the transconductance of the SiC MOSFET whose junction temperature needs to be evaluated. According to the linear relationship of the calibration curve, the junction temperature evaluation value of the SiC MOSFET can be obtained from the arithmetic square root value, and thus the junction temperature T jmin .

[0112] Similarly, the principle of junction temperature evaluation in the turn-off process is the same as that in the turn-on process. As Figure 4 shown in, V GS3 and V GS4 are the gate driving voltages in the turn-off process, which are respectively denoted as the third driving voltage and the fourth driving voltage, and the corresponding I D3 and I D4They are the third drain current and the fourth drain current respectively. By substituting the data obtained according to the data in formula (2), the transconductance value during the turn-off process can be obtained. Further solving the transconductance gives the arithmetic square root of the transconductance during the turn-off process. Except for data substitution, other steps and methods are the same as the junction temperature evaluation process during the turn-on process and will not be repeated here. Thus, the junction temperature T at the end of the SiC MOSFET turn-on can be obtained. jmax 。

[0113] As Figure 4 shown, the junction temperature T at the start of the turn-on of the device in the same switching cycle is measured and evaluated respectively jmin and the junction temperature T at the end of the turn-on jmax . The difference between the two is the junction temperature fluctuation caused by a single switching cycle, so that the measurement of the device junction temperature fluctuation caused by a single switching cycle can be completed. Therefore, by establishing their respective calibration curves during the turn-on and turn-off stages of the device and using the respective calibration curves for junction temperature evaluation, the junction temperature evaluations during the turn-on and turn-off stages can be completed respectively. Further taking the difference between the two junction temperature evaluation values gives the junction temperature fluctuation under a single switching cycle.

[0114] When the junction temperature of the device reaches a steady state, in the same switching cycle, theoretically the junction temperature fluctuation during the turn-on process is the same as that during the turn-off process. Therefore, during actual measurement, one of the methods can be selected for measurement.

[0115] The temperature-sensitive electrical parameter method described in this method is compared with some of the temperature-sensitive electrical parameter methods that have been proposed for SiC MOSFET junction temperature measurement, and evaluated from three aspects: linearity, sensitivity, and ease of on-line application. The evaluation results are shown in Table 1.

[0116] Table 1 Performance evaluation of different temperature-sensitive electrical parameters

[0117]

[0118] From the comparison of the evaluation results in the table, the temperature dependence of the arithmetic square root of the transconductance proposed in this method has good linearity, high sensitivity, and is easy to apply on-line; while the linearity of the body diode voltage drop of the SiC MOSFET is not much different from that described in this method, and the sensitivity is slightly inferior, but its on-line application is more difficult; while the on-resistance is easy to apply on-line, but it has deficiencies in both linearity and sensitivity. From the comprehensive effect, this method has obvious advantages in the field of SiC MOSFET junction temperature measurement.

[0119] The above-described embodiments are merely preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art of this technology on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for generating a junction temperature calibration curve of a SiC MOSFET device, characterized in that: It includes the following steps: Obtain the transconductance parameter values of the SiC MOSFET device at different junction temperatures; Fit the transconductance parameter values and temperature to obtain the relationship curve between the transconductance parameter values and temperature; The transconductance parameter value refers to the arithmetic square root of the transconductance of the SiC MOSFET device; The junction temperature calibration curve is the square root of the transconductance arithmetic -junction temperature calibration curve.

2. The method for generating a junction temperature calibration curve according to claim 1, wherein: The transconductance is calculated according to the following formula: ； Among them, represents the increment of the drain current ; represents the increment of the gate drive voltage that causes the increment of the drain current and the value is within a preset range.

3. The method for generating a junction temperature calibration curve according to claim 1, wherein: The junction temperature calibration curve is specifically formed according to the following process: By applying a gate drive voltage to the SiC MOSFET, which is denoted as the first drive voltage and obtaining the drain current at this time, which is denoted as the first drain current ; Change the driving voltage and denote it as the second driving voltage , it is necessary to ensure that the difference from to is within a preset range, and at the same time record the drain current at this time and denote it as the second drain current ; Calculate the transconductance value at this test temperature, and further solve to obtain the arithmetic square root of the transconductance ; The SiC MOSFET is repeatedly tested at different junction temperatures to obtain all the square root values of the transconductance at preset different test temperatures. The relationship between the square root value of the transconductance and the temperature is linearly fitted to obtain its fitting linear relationship formula. The square root of the transconductance obtained from the fitting linear relationship formula and the junction temperature The linear relationship curve, that is, the calibration curve.

4. A junction temperature evaluation method implemented by using the method according to any one of claims 1-3, characterized in that: It includes the following steps: Obtain the junction temperature calibration curve of the device; Test the transconductance of the device to be evaluated and calculate the real-time arithmetic square root value of the device transconductance; Calculate according to the linear relationship between the arithmetic square root of the device transconductance and the junction temperature based on the real-time arithmetic square root value of the transconductance or directly query the calibration curve to obtain the junction temperature of the device.

5. The junction temperature evaluation method according to claim 4, characterized in that: The transconductance of the device to be evaluated is tested in the following manner: Set the drive voltage of the SiC MOSFET device and measure the drain current value corresponding to the drive voltage; Calculate the transconductance value and the arithmetic square root of the transconductance; Query the junction temperature corresponding to the device transconductance arithmetic square root junction temperature calibration curve according to the arithmetic square root of the transconductance.

6. The junction temperature evaluation method according to claim 5, characterized in that: The setting of the drive voltage of the SiC MOSFET device is carried out according to the preset drive voltage value in the junction temperature calibration curve of the device.

7. The junction temperature evaluation method according to claim 5, characterized in that: The drive voltage is the gate drive voltage during the device turn-on process, and the drain current value is the corresponding drain current during the turn-on process; or The drive voltage is the gate drive voltage during the device turn-off process, and the drain current value is the corresponding drain current during the turn-off process.

8. The method for measuring the junction temperature fluctuation of a SiC MOSFET device in a single switching cycle is implemented by using the method according to any one of claims 4-7, characterized in that: The measurement is carried out according to the following steps: Measure the junction temperature T at the beginning of the same switching cycle of the evaluation device. jmin The junction temperature T jmax , calculate the difference between the start and end of conduction to obtain the junction temperature fluctuation during the conduction process of a single switching cycle; or Measure and evaluate the junction temperature T at the start of turn-off within the same switching cycle of the device jmax and the junction temperature T at the end of turn-off jmin , calculate the difference between the start and the end of turn-off to obtain the junction temperature fluctuation during the turn-off process of a single switching cycle.

9. A SiC MOSFET junction temperature evaluation system based on device transconductance measurement, characterized in that: It includes a main circuit module, a gate drive module, a temperature regulation module, a voltage acquisition module, a current acquisition module, a data processing module, and a junction temperature evaluation module; The main circuit module is used to carry the circuit topology for the SiC MOSFET to work; The gate drive module is used to provide the corresponding gate drive signal for the SiC MOSFET; The temperature regulation module is used to provide different test temperatures for the SiC MOSFET; The voltage acquisition module is used to acquire the voltage-related data required for the calibration curve; The current acquisition module is used to acquire the current-related data required for the calibration curve; The data processing module is used to calculate, linearly fit, and establish the calibration curve for the acquired data; The junction temperature evaluation module is used to calculate according to the method for generating the junction temperature calibration curve of the SiC MOSFET device described in claim 1 above and obtain the junction temperature evaluation report of the device.

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