Method and system for on-line measurement of junction temperature of IGBT device

Abstract

The application discloses an online measurement method and system for a junction temperature of an IGBT device, simplifies the on-state voltage drop of the IGBT device into a sum of a P-i-N junction voltage drop, a MOSFET channel resistance voltage drop and a connection material resistance voltage drop, estimates the on-state slope resistance of the IGBT device online by measuring collector-emitter voltages of the IGBT device under different collector currents, subtracts the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device, and approximately obtains the P-i-N junction voltage drop in the IGBT device, which is used as a new temperature-sensitive electrical parameter. Since the P-i-N junction voltage drop has a single negative temperature coefficient, the influence of temperature differences of internal connection materials of the IGBT device under different working conditions on the temperature-sensitive electrical parameter is avoided, the accuracy of the junction temperature measurement of the IGBT device is improved, there is no blind spot, and the junction temperature is more suitable for online estimation.

Description

Technical Field

[0001] This application relates to the field of semiconductor power device monitoring technology, and in particular to an online measurement method and system for the junction temperature of an IGBT device. Background Technology

[0002] Power semiconductor devices typically operate in harsh environments and are the components with the highest failure rate in power conversion systems. According to a power electronic system reliability survey report, approximately 55% of power electronic system failures are mainly caused by temperature factors. Therefore, accurate online extraction of the junction temperature of high-capacity power semiconductor devices is the foundation for device lifetime prediction and health management, and is of great significance for improving the reliability of power electronic systems.

[0003] Insulated-gate bipolar transistors (IGBTs) are commonly used power semiconductor devices. Because the IGBT chip is internally packaged and acts as a heat source, accurate online measurement of the IGBT junction temperature has always been a major challenge. Current methods for measuring IGBT junction temperature typically involve: first, pre-measuring the on-state voltage drop (collector-emitter voltage) versus current (collector current) of the offline IGBT at different temperatures to establish a three-dimensional calibration relationship between the on-state voltage drop, current, and temperature; then, measuring the on-state voltage drop versus current curve under real-time operating conditions and comparing it with the three-dimensional calibration relationship of the IGBT's on-state voltage, current, and temperature to obtain the IGBT junction temperature.

[0004] However, the junction temperature of IGBT devices measured using existing methods usually does not match their actual junction temperature, resulting in low measurement accuracy. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides an online measurement method and system for IGBT device junction temperature, thereby improving the accuracy of IGBT device junction temperature measurement.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0007] An online measurement method for the junction temperature of an IGBT device, wherein the on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to electrically connect the IGBT chip to an external source, and the IGBT chip in the on-state is equivalent to a PiN junction and a MOSFET device connected in series, the method comprising:

[0008] The collector-emitter voltage and collector current of the IGBT device are measured in real time under operating conditions to obtain the corresponding relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions.

[0009] Based on the correspondence between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated. The on-state slope resistance of the IGBT device is the rate of change of the collector-emitter voltage relative to the collector current after the inflection point of the IGBT device. It is equivalent to the sum of the resistance of the connection material and the channel resistance of the MOSFET device after the inflection point of the IGBT device. The inflection point is the temperature-independent operating point of the collector-emitter voltage and collector current of the IGBT device obtained in advance.

[0010] Subtracting the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions yields the voltage drop across the PiN junction and the real-time monitoring value of the collector current of the IGBT device under operating conditions.

[0011] Based on the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions, as well as the pre-obtained correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device, the junction temperature of the IGBT device is obtained.

[0012] Optionally, based on the relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated, including:

[0013] The ratio of the difference between the maximum collector-emitter voltage of the IGBT device during a measurement phase and the collector-emitter voltage of the IGBT device at the inflection point to the difference between the maximum collector current of the IGBT device during the same measurement phase and the collector current of the IGBT device at the inflection point is used as the on-state slope resistance of the IGBT device under operating conditions.

[0014] Optionally, based on the relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated, including:

[0015] A linear fit is performed on the relationship between the collector-emitter voltage and collector current of the IGBT device after the inflection point under operating conditions to obtain the slope of the fitted line, which is used as the on-state slope resistance of the IGBT device under operating conditions.

[0016] Optionally, the process of pre-obtaining the relationship between the voltage drop across the PiN junction in the IGBT device, the collector current of the IGBT device, and the temperature of the IGBT device includes:

[0017] The offline IGBT device was placed in temperature chambers at different temperatures, and the collector-emitter voltage and collector current of the offline IGBT device at different temperatures were measured to obtain the corresponding relationship between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures.

[0018] Based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated.

[0019] By subtracting the product of the corresponding collector current and the on-state slope resistance at the corresponding temperature from the collector-emitter voltage of the offline IGBT device at different temperatures, the corresponding relationship between the voltage drop across the PiN junction and the collector current of the IGBT device at different temperatures is obtained. This relationship serves as the correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device.

[0020] Optionally, the process of obtaining the inflection point in advance includes:

[0021] Based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the curves of the change of collector-emitter voltage with collector current of the offline IGBT device at different temperatures are obtained.

[0022] The intersection point of the collector-emitter voltage versus collector current curves of the offline IGBT device at different temperatures is taken as the inflection point.

[0023] Optionally, based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated, including:

[0024] The ratio of the difference between the maximum collector-emitter voltage of the offline IGBT device at different temperatures and the collector-emitter voltage of the IGBT device at the inflection point to the difference between the maximum collector current of the offline IGBT device at the corresponding temperature and the collector current of the IGBT device at the inflection point is used as the on-state slope resistance of the offline IGBT device at the corresponding temperature.

[0025] Optionally, based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated, including:

[0026] Linear fitting is performed on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device after the inflection point at different temperatures to obtain the slope of the fitted line, which is used as the on-state slope resistance of the offline IGBT device at the corresponding temperature.

[0027] An online measurement system for the junction temperature of an IGBT device, wherein the on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to electrically connect the IGBT chip to an external source, and the IGBT chip in the on-state is equivalent to a PiN junction and a MOSFET device connected in series, the measurement system comprising:

[0028] The measurement module is used to measure the collector-emitter voltage and collector current of the IGBT device in real time under operating conditions, and to obtain the corresponding relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions.

[0029] The calculation module is used to calculate the on-state slope resistance of the IGBT device under operating conditions based on the correspondence between the collector-emitter voltage and the collector current of the IGBT device under operating conditions. The on-state slope resistance of the IGBT device is the rate of change of the collector-emitter voltage relative to the collector current of the IGBT device after the inflection point, which is equivalent to the sum of the resistance of the connection material of the IGBT device and the channel resistance of the MOSFET device after the inflection point. The inflection point is the temperature-independent operating point of the collector-emitter voltage and collector current of the IGBT device obtained in advance.

[0030] The conversion module is used to subtract the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions, so as to obtain the voltage drop across the PiN junction and the real-time monitoring value of the collector current of the IGBT device under operating conditions.

[0031] The calibration module is used to obtain the junction temperature of the IGBT device based on the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions, as well as the pre-acquired correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device.

[0032] Optionally, the computing module includes:

[0033] The first calculation unit is used to calculate the ratio of the difference between the maximum collector-emitter voltage of the IGBT device in a measurement phase and the collector-emitter voltage of the IGBT device at the inflection point to the maximum collector current of the IGBT device in the same measurement phase and the collector current of the IGBT device at the inflection point, and use it as the on-state slope resistance of the IGBT device under operating conditions.

[0034] Optionally, the computing module includes:

[0035] The second calculation unit is used to perform linear fitting on the correspondence between the collector-emitter voltage and collector current of the IGBT device after the inflection point under the operating conditions, and obtain the slope of the fitted line as the on-state slope resistance of the IGBT device under the operating conditions.

[0036] Compared with existing technologies, the above technical solution has the following advantages:

[0037] The online measurement method for IGBT junction temperature provided in this application embodiment considers that the on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to connect the IGBT chip to the external electrical system. Furthermore, the IGBT chip in the on-state is equivalent to a PiN junction and a MOSFET device connected in series. Therefore, the on-state voltage drop of the IGBT device is simplified to the sum of the PiN junction voltage drop, the MOSFET channel resistance voltage drop, and the resistance voltage drop of the connecting material. By measuring the collector-emitter voltage of the IGBT device under different collector currents in real time, the on-state slope resistance of the IGBT device under operating conditions is estimated online. The collector-emitter voltage of the IGBT device under operating conditions is then subtracted from the product of the corresponding collector current and the on-state slope resistance, which represents the voltage drop across the on-state slope resistance in the collector-emitter voltage of the IGBT device under operating conditions. Subtracting the voltage drop across the IGBT's collector-emitter voltage, which is composed of the channel resistance of the MOSFET and the resistance of the interconnecting materials, yields the real-time monitored values ​​of the voltage drop across the IGBT's PiN junction and the collector current. This value is then compared with pre-obtained correlations between the PiN junction voltage drop, the collector current, and the IGBT's temperature to determine the junction temperature. This method uses the "PiN junction voltage drop" as a new temperature-sensitive parameter, and because the PiN junction voltage drop has a single negative temperature coefficient, it avoids the influence of temperature differences in the internal interconnecting materials of the IGBT on the temperature-sensitive parameter under different operating conditions. This improves the accuracy of IGBT junction temperature measurement and eliminates blind spots.

[0038] Furthermore, since the on-state slope resistance of the IGBT device under operating conditions is calculated in real time based on the collector-emitter voltage and collector current data of the IGBT device measured online, the accuracy of the real-time calculation results is not affected regardless of whether the junction temperature of the IGBT chip and the temperature of the connecting material are equal. Therefore, this method can also avoid the influence of the temperature difference of the internal connecting material of the IGBT device on the temperature-sensitive electrical parameters during the offline calibration process and actual operation, and is more suitable for online estimation of junction temperature. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A schematic diagram illustrating a three-dimensional calibration relationship between the on-state voltage drop, current, and temperature of an IGBT device;

[0041] Figure 2 This is a schematic diagram of the cross-sectional structure of an IGBT chip;

[0042] Figure 3 This is a schematic diagram of the equivalent circuit of an IGBT chip in the on-state.

[0043] Figure 4 This is a schematic diagram showing the change of collector-emitter voltage with collector current of an IGBT device at different temperatures.

[0044] Figure 5 This is a schematic diagram showing the voltage drop across the PiN junction of an IGBT device as a function of collector current at different temperatures.

[0045] Figure 6 A schematic flowchart illustrating an online measurement method for the junction temperature of an IGBT device provided in an embodiment of this application;

[0046] Figure 7 In an online measurement method for the junction temperature of an IGBT device provided in this application embodiment, the measured collector-emitter voltage of the IGBT device under operating conditions is a curve showing the change of its collector current.

[0047] Figure 8 This is a flowchart illustrating the process of obtaining the relationship between the voltage drop across the PiN junction of the IGBT device, the collector current of the IGBT device, and the temperature of the IGBT device in advance in an online measurement method for the junction temperature of an IGBT device provided in an embodiment of this application.

[0048] Figure 9 This is a schematic diagram of an online measurement system for the junction temperature of an IGBT device provided in an embodiment of this application. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0050] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0051] As described in the background section, since the IGBT device chip is packaged inside the device and the chip inside the IGBT device is a heat source, the accurate online measurement of the junction temperature of the IGBT device has always been a major challenge.

[0052] In converter systems, the temperature-sensitive electrical parameter method based on the on-state voltage drop (collector-emitter voltage) of IGBT devices is a non-invasive method for obtaining junction temperature by measuring electrical parameters. This method can be further subdivided into the temperature-sensitive electrical parameter method based on small current on-state voltage drop and the temperature-sensitive electrical parameter method based on large current on-state voltage drop. The small current on-state voltage drop method involves injecting a small current into the IGBT device when the converter is not in operation and measuring the change in its on-state voltage drop. This method has advantages such as good linearity, high detection accuracy, and is unaffected by chip self-heating effects. However, it requires interrupting the normal operation of the converter during testing, which has a significant impact on the converter system control. The large current on-state voltage drop method monitors the junction temperature online by detecting the change in the on-state voltage drop of the IGBT device under load current. It does not require changes to the existing control strategy or interruption of converter operation, and can monitor the health status of the IGBT device in real time, making it more valuable for industrial applications.

[0053] The main implementation steps of the existing temperature-sensitive electrical parameter method based on large current on-state voltage drop are as follows:

[0054] 1. Place offline IGBT devices in temperature chambers at different temperatures, and measure the variation curves of the on-state voltage drop (collector-emitter voltage) with the current (collector current) of the offline IGBT devices at different temperatures. Establish a three-dimensional calibration relationship between the on-state voltage drop (collector-emitter voltage), the current (collector current), and the temperature of the IGBT devices. Figure 1 The on-state voltage drop V of the IGBT device is shown. CE_on Current I C A schematic diagram illustrating a three-dimensional calibration relationship between temperature T and T;

[0055] 2. Real-time measurement of the on-state voltage drop of the IGBT under operating conditions as a function of current;

[0056] 3. Compare the curve of the on-state voltage drop of the IGBT under operating conditions measured in real time with the previously established three-dimensional calibration relationship of the on-state voltage, current and temperature of the IGBT device to obtain the junction temperature of the IGBT device.

[0057] The inventors discovered that the main problem with the above measurement method is that in the first step of offline calibration, the IGBT device under test is placed in a temperature chamber for a sufficiently long time so that the junction temperature of the IGBT device is similar to the ambient temperature in the temperature chamber, so that the ambient temperature in the temperature chamber can be used as the junction temperature of the IGBT device.

[0058] However, it is understandable that the IGBT chip is packaged inside the device, meaning that in addition to the IGBT chip, the IGBT device also includes connecting materials for electrically connecting the IGBT chip to the outside. Therefore, in the first step of offline calibration, the junction temperature of the chip inside the IGBT device and the temperature of the connecting materials are both controlled to the temperature set by the temperature chamber. That is, the junction temperature of the chip inside the IGBT device and the temperature of the connecting materials are exactly equal, which is inconsistent with the actual operating conditions of the IGBT device. In actual operating conditions, the chip inside the IGBT device is the main heat source, and the temperature of the bonding material is lower than the junction temperature of the chip. Correspondingly, since the resistance of the bonding material has a positive temperature coefficient, that is, the higher the temperature of the bonding material, the greater the voltage drop across the bonding material resistance. Therefore, when the junction temperature of the IGBT chip in actual operating conditions is equal to the temperature of the temperature chamber during offline calibration, the bonding material resistance in actual operating conditions is less than that in offline calibration. This leads to the on-state voltage drop of the IGBT device in actual operating conditions being lower than that in offline calibration at the same junction temperature, which in turn results in the measured junction temperature of the IGBT device being lower than the actual junction temperature.

[0059] Therefore, the junction temperature of IGBT devices measured using existing methods usually does not match their actual junction temperature, and the measurement accuracy is not high.

[0060] In view of this, embodiments of this application provide an online measurement method for the junction temperature of an IGBT device. Since the voltage drop across the connection material between the IGBT chip and the external electrical connection under high current is not negligible, the voltage drop across the connection material between the IGBT chip and the external electrical connection needs to be considered when measuring the junction temperature of the IGBT device.

[0061] Figure 2 A cross-sectional structural diagram of an IGBT chip is shown, as follows. Figure 2 As shown, the IGBT chip includes P164 ... + Zone 10, N-Drift Zone 20, P Zone 30, N + In section 40, this IGBT chip has three electrode terminals: an emitter (E), a gate (G), and a collector (C). The gate (G) has a SiO2 layer (50). It should be noted that... Figure 2 The connecting material that connects the IGBT chip to the external electrical system is not shown in the diagram.

[0062] The inventors discovered through research that, for example Figure 2 The schematic diagram of the cross-sectional structure of the IGBT chip shown is as follows: Figure 3 The diagram shows the equivalent circuit of an IGBT chip in the on-state. In the on-state, the IGBT chip can be equivalent to a PiN junction and a MOSFET device connected in series. Therefore, the total on-state voltage drop V of the IGBT device in the on-state is... CE_on (i.e., the on-state voltage drop) is equal to the voltage drop V across the PiN junction. CE_P-i-N (T j ), the channel resistance R of MOSFET devices MOS (T j The pressure drop R on the surface MOS (T j )I C and the resistance R of the connecting material con (T con The pressure drop R on the surface con (T con )I C The sum can be specifically expressed as:

[0063]

[0064] Among them, the on-state voltage drop V of the IGBT device CE_on This refers to the collector-emitter voltage of the IGBT device in the on-state, I. C T is the collector current of the IGBT device. j T represents the junction temperature of the IGBT chip inside the IGBT device. con This indicates the temperature of the internal interconnecting material of the IGBT device.

[0065] In summary, the problem with existing temperature-sensitive electrical parameter methods based on high current on-state voltage drop is that, during offline calibration, after placing the IGBT device under test in a temperature chamber for a sufficiently long time, all internal components of the IGBT device are controlled to the temperature set by the chamber, i.e., T. j =T con In actual operation, the IGBT chip is the main heat source, and at this time, T j >T con Accordingly, there must be R con (T j R con (T con Therefore, the collector-emitter voltage V of the IGBT device at different temperatures during offline calibration and actual operation corresponds to different conditions. CE_on With collector current I C The changing family of curves will inevitably have differences, which will lead to variations in the measured junction temperature T. j There is a discrepancy.

[0066] The inventors further discovered that, within a small current range, the on-state voltage drop V of the IGBT device... CE_on The voltage drop V across the PiN junction CE_P-i-N (T j The primary characteristic is the on-state voltage drop (V) of the IGBT device, while in the high current range, the on-state voltage drop (V) is... CE_on The channel resistance R of the MOSFET device MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistance is the main component, meaning the voltage drop across the resistor is the primary component.

[0067] Understandably, the voltage drop V across the PiN junction... CE_P-i-N (T j It has a negative temperature coefficient, meaning that at the same current, the higher the temperature, the greater the voltage drop V across the PiN junction. CE_P-i-N (T j The lower the value, the better. And for MOSFET devices, the channel resistance R... MOS (T j and the resistance R of the connecting material con (T con In terms of the overall resistance of the MOSFET device, since resistance has a positive temperature coefficient, the channel resistance R is... MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistance of the MOSFET also has a positive temperature coefficient; that is, at the same current, the higher the temperature, the greater the channel resistance R of the MOSFET device. MOS (T j and the resistance R of the connecting material con (T con The higher the voltage drop across the overall resistor composed of the components, the higher the voltage drop.

[0068] For ease of understanding, Figure 4 The collector-emitter voltage V of the IGBT device at different temperatures is shown. CE_on With its collector current I C A schematic diagram of the change curve, such as... Figure 4 As shown, in the low current range, the on-state voltage drop V of the IGBT device is... CE_on The voltage drop V across the PiN junction CE_P-i-N (T j The main characteristic is the negative temperature gradient, meaning that under the same current, the higher the temperature, the lower the on-state voltage drop V of the IGBT device. CE_on The lower, specifically, along Figure 4The four curves, pointing downwards along the dashed arrows, correspond to IGBT junction temperatures of 65℃, 85℃, 105℃, and 125℃, respectively.

[0069] like Figure 4 As shown, in the high current range, the on-state voltage drop V of the IGBT device is... CE_on The channel resistance R of the MOSFET device MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistance of the IGBT device is the primary characteristic, exhibiting a positive temperature coefficient. This means that at the same current, the higher the temperature, the greater the on-state voltage drop V of the IGBT device. CE_on The higher, specifically, along Figure 4 The four curves, pointing upwards with the dashed arrows, correspond to IGBT junction temperatures of 65℃, 85℃, 105℃, and 125℃, respectively.

[0070] like Figure 4 As shown, the collector-emitter voltage V of the IGBT device at different temperatures CE_on With its collector current I C The change curves have a convergence point C, called the inflection point. This inflection point C is the collector-emitter voltage V of the IGBT device. CE_on and collector current I C The temperature-independent operating point, that is, the collector-emitter voltage V of the IGBT device before this inflection point C. CE_on The voltage drop V across the PiN junction CE_P-i-N (T j The collector-emitter voltage (V) of the IGBT device is mainly based on the negative temperature coefficient, and after this inflection point C, the collector-emitter voltage (V) of the IGBT device... CE_on The channel resistance R of the MOSFET device MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistance is the dominant characteristic, meaning it is primarily a resistive voltage drop and has a positive temperature coefficient. At the inflection point C, the collector-emitter voltage V of the IGBT device... CE_on and collector current I C Temperature-independent, or in other words, at the inflection point C, the collector current I of the IGBT device varies with different temperatures. C The corresponding collector-emitter voltage V CE_on They are all equal, equivalent to the channel resistance R of a MOSFET device. MOS (T j and the resistance R of the connecting material con (T conThe positive temperature coefficient of the voltage drop across the overall resistor composed of the πN junction varies with the voltage drop V across the πN junction. CE_P-i-N (T j The operating point of the IGBT device when the negative temperature coefficient change is offset.

[0071] Because after the inflection point C, the collector-emitter voltage V of the IGBT device... CE_on The channel resistance R of the MOSFET device MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistance is the main component, meaning the voltage drop across the resistor is the primary component. Therefore, if... Figure 4 As shown, at a certain temperature, the collector-emitter voltage V of the IGBT device after the transition point... CE_on With its collector current I C The change is almost linear, therefore, the collector-emitter voltage V of the IGBT device after the inflection point can be used as a basis for analysis. CE_on With its collector current I C The change curve is used to obtain the collector-emitter voltage V of the IGBT device after the inflection point. CE_on Relative to collector current I C The rate of change of the resistance is called the on-state slope resistance R of the IGBT device. on .

[0072] It is understandable that the on-state slope resistance R of an IGBT device... on R can be approximated as the channel resistance of a MOSFET device. MOS (T j and the resistance R of the connecting material con (T con The overall resistance consisting of ) is:

[0073] R on ≈R MOS (T j )+R con (T con (2)

[0074] Based on formulas (1) and (2), the voltage drop V across a virtual PiN junction can be obtained. C ′ E_P-i-N for:

[0075] V′ CE_P-i-N =V CE_on -R on I C (3)

[0076] Therefore, it can be approximated that the voltage drop across the virtual PiN junction is equal to the voltage drop across the real PiN junction, that is:

[0077] V′ CE_P-i-N =V CE_P-i-N (4)

[0078] Therefore, based on Figure 4 The collector-emitter voltage V of the IGBT device shown at different temperatures CE_on With its collector current I C The on-state slope resistance R of the IGBT device at different temperatures can be calculated from the curve of the curve. on Therefore, based on formula (3), for Figure 4 The collector-emitter voltage V of the IGBT device shown at different temperatures CE_on With its collector current I C By transforming the curve of change, we can obtain Figure 5 The voltage drop V across the PiN junction of the IGBT device shown is different at different temperatures. CE_P-i-N With collector current I C A cluster of changing curves.

[0079] like Figure 5 As shown, the ordinate parameter is converted from the collector-emitter voltage V CE_on Replace with the voltage drop V across the PiN junction CE_P-i-N The obtained VI curves show a very good one-to-one correspondence with temperature; specifically, along... Figure 5 The four curves, pointing downwards along the dashed arrows, correspond to IGBT junction temperatures of 65℃, 85℃, 105℃, and 125℃, respectively. This means that the "PiN junction voltage drop" can be used as a new temperature-sensitive electrical parameter.

[0080] And, as Figure 4 As shown, the turning point C is actually the collector-emitter voltage V of the IGBT device. CE_on This is a blind spot when measuring junction temperature using temperature-sensitive electrical parameters, because at the inflection point C, the collector-emitter voltage V of the IGBT device... CE_on and collector current I C Neither of them changes with temperature, and there is no blind spot when using "PiN junction voltage drop" as a temperature-sensitive electrical parameter.

[0081] This is because, according to formula (3), the collector-emitter voltage V of the IGBT device is... CE_on The on-state slope resistance R of the IGBT device on The pressure drop R on on I CSubtracting, that is, reducing the collector-emitter voltage V of the IGBT device. CE_on The channel resistance R of a MOSFET device MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistor composed of the IGBT is reduced, thereby decreasing the collector-emitter voltage V of the IGBT device. CE_on The voltage drop of the remaining part (virtual PiN junction voltage drop, approximately equal to the real PiN junction voltage drop) has a negative temperature coefficient, thus having a very good one-to-one correspondence with temperature, and there are no blind spots.

[0082] Based on this, such as Figure 6 As shown in the embodiments of this application, the online measurement method for the junction temperature of an IGBT device includes:

[0083] S100: Real-time measurement of the collector-emitter voltage and collector current of the IGBT device under operating conditions, obtaining the corresponding relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions.

[0084] Optionally, in a converter system, when the converter is under actual operating conditions, a dedicated on-state voltage drop measurement circuit can be used to measure the collector-emitter voltage V of the IGBT device under operating conditions. CE_on Simultaneously, a Hall current sensor is used to measure the load current I flowing through the IGBT device under operating conditions. C This refers to the collector current I of the IGBT under operating conditions. C .

[0085] Optionally, the relationship between the collector-emitter voltage and collector current of an IGBT device under operating conditions can be expressed as the collector-emitter voltage V of the IGBT device under operating conditions. CE_on With its collector current I C The change curve, specifically as follows: Figure 7 As shown, the collector current I of the IGBT device under operating conditions is... C The horizontal axis represents the collector-emitter voltage V of the IGBT device under operating conditions. CE_on Using the vertical axis as the ordinate, we obtain the collector-emitter voltage V of the IGBT device under operating conditions. CE_on With its collector current I C The changing VI curve, Figure 7 Two VI curves are shown in the figure.

[0086] Optionally, the relationship between the collector-emitter voltage and collector current of an IGBT device under operating conditions can also be expressed in other forms, such as scatter plots, tables, etc., depending on the specific circumstances.

[0087] It should be noted that in a converter system, the load current I flowing through the IGBT device under operating conditions is... C For alternating current, such as a sinusoidal current, it changes in real time. Correspondingly, the collector-emitter voltage V of the IGBT device under operating conditions... CE_on It also changes in real time. However, the online measurement method for the junction temperature of IGBT devices provided in this application is not limited to IGBT devices in converter systems, as long as the collector-emitter voltage V of the IGBT device under operating conditions is within the range. CE_on With its collector current I C The changes can be addressed by utilizing the online measurement method for IGBT device junction temperature provided in the embodiments of this application.

[0088] It should also be noted that in step S100, the collector-emitter voltage V of the IGBT device under operating conditions is measured in real time. CE_on and collector current I C Therefore, the collector-emitter voltage V of the IGBT device under operating conditions can be obtained through real-time measurement. CE_on and collector current I C The junction temperature of the IGBT device is obtained, that is, the online measurement method of the junction temperature of the IGBT device provided in this application embodiment can monitor the current junction temperature of the IGBT device under operating conditions in real time.

[0089] S200: Based on the correspondence between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated. The on-state slope resistance of the IGBT device is the rate of change of the collector-emitter voltage relative to the collector current after the inflection point of the IGBT device. It is equivalent to the sum of the resistance of the connecting material of the IGBT device after the inflection point and the channel resistance of the MOSFET device. The inflection point is the operating point of the IGBT device where the collector-emitter voltage and collector current are independent of temperature.

[0090] As previously known, the inflection point C corresponds to the channel resistance R of the MOSFET device. MOS (T j and the resistance R of the connecting material con (T con The positive temperature coefficient of the voltage drop across the overall resistor composed of the πN junction varies with the voltage drop V across the πN junction. CE_P-i-N (T jThe negative temperature coefficient change of the IGBT device cancels out the operating point of the collector-emitter voltage V at the inflection point C. CE_on and collector current I C Temperature-independent, meaning that at the inflection point C, the collector current I of the IGBT device varies with different temperatures. C The corresponding collector-emitter voltage V CE_on They are all equal.

[0091] As previously known, after the inflection point C, the collector-emitter voltage V of the IGBT device... CE_on The channel resistance R of the MOSFET device MOS (T j and the resistance R of the connecting material con (T con The voltage drop across the overall resistor (composed of the components) is the primary characteristic, meaning the voltage drop across the resistor is the main component. Therefore, it can be understood that the reference voltage drop is the primary characteristic. Figure 7 As shown, when the IGBT device is operating at its current junction temperature, the collector-emitter voltage V of the IGBT device after the transition point... CE_on With its collector current I C The voltage changes almost linearly, thus, the collector-emitter voltage V of the IGBT device under operating conditions can be determined based on the measured voltage. CE_on and collector current I C The correspondence between them was used to calculate the collector-emitter voltage V of the IGBT device after the transition point. CE_on Relative to collector current I C The rate of change of resistance is the on-state slope R of the IGBT device under operating conditions. on Among them, the on-state slope resistance R of the IGBT device on Equivalent to the resistance R of the connecting material after the inflection point of the IGBT device. con (T con The channel resistance R of the MOSFET device MOS (T j ) and.

[0092] It should be noted that in step S100, due to the collector-emitter voltage V of the IGBT device under operating conditions... CE_on and collector current I C The measurement is real-time; therefore, the obtained collector-emitter voltage V of the IGBT device under operating conditions is accurate. CE_on and collector current I C The correspondence between them is also real-time, and in step S200, it is necessary to calculate the collector-emitter voltage V of the IGBT device after the inflection point. CE_on Relative to collector current IC The rate of change of the IGBT device's on-state slope resistance R under operating conditions is obtained by calculating the rate of change of the resistance. on Therefore, it is necessary to measure the collector-emitter voltage V of the IGBT device after the inflection point within a measurement phase. CE_on Relative to collector current I C The rate of change is calculated.

[0093] Furthermore, due to the on-state slope resistance R of an IGBT device at a certain junction temperature... on It is certain; therefore, the collector-emitter voltage V of the IGBT device after the inflection point, calculated within a measurement phase, can be used as the reference. CE_on Relative to collector current I C The rate of change of resistance, R, is used as the on-state slope resistance of the IGBT device under operating conditions over a relatively long measurement period. on Alternatively, the collector-emitter voltage V of the IGBT device after the inflection point, calculated in the previous measurement stage, can be used as the reference value. CE_on Relative to collector current I C The rate of change of is used as the on-state slope resistance R of the IGBT device under operating conditions in the next measurement phase. on Furthermore, within each measurement phase, the collector-emitter voltage V of the IGBT device after the transition point can be calculated. CE_on Relative to collector current I C The rate of change of is used as the on-state slope resistance R of the IGBT device under operating conditions during this measurement phase. on It depends on the specific circumstances.

[0094] Optionally, in one embodiment of this application, the on-state slope resistance of the IGBT device under operating conditions is calculated based on the correspondence between the collector-emitter voltage and collector current of the IGBT device under operating conditions, including:

[0095] S210: Calculate the ratio of the difference between the maximum collector-emitter voltage of the IGBT device during a measurement phase and the collector-emitter voltage of the IGBT device at the inflection point, and the difference between the maximum collector current of the IGBT device during the same measurement phase and the collector current of the IGBT device at the inflection point, as the on-state slope resistance of the IGBT device under operating conditions.

[0096] Specifically, such as Figure 7 As shown, Figure 7 That is, the collector-emitter voltage V of the IGBT device under operating conditions during a measurement phase. CE_on With its collector current I CThe curve shows the change in voltage, where the maximum collector-emitter voltage of the IGBT device during this measurement phase is V. CE_max The maximum collector current of the IGBT device during this measurement phase is I. C_max Furthermore, the collector-emitter voltage V at the inflection point C of the IGBT CE_inf and collector current I C_inf If this information can be obtained in advance, then the on-state slope resistance R of the IGBT device under operating conditions... on It can be represented as:

[0097]

[0098] Optionally, in another embodiment of this application, the on-state slope resistance of the IGBT device under operating conditions is calculated based on the correspondence between the collector-emitter voltage and collector current of the IGBT device under operating conditions, including:

[0099] S220: Linearly fit the relationship between collector-emitter voltage and collector current of the IGBT device after the inflection point under operating conditions, and obtain the slope of the fitted line as the on-state slope resistor of the IGBT device under operating conditions.

[0100] Because the collector-emitter voltage V of the IGBT device after the inflection point CE_on With its collector current I C The change is almost linear; therefore, in step S220, the collector-emitter voltage V of the IGBT device after the inflection point C under operating conditions can be measured. CE_on and collector current I C The corresponding relationship between them is linearly fitted to obtain the slope of the fitted line, which is used as the on-state slope resistance of the IGBT device under operating conditions.

[0101] Understandably, the method of calculating the on-state slope resistance of the IGBT device under operating conditions in step S210 is simpler, but the method of calculating the on-state slope resistance of the IGBT device under operating conditions in step S220 is more accurate. The specific method can be selected according to the actual situation.

[0102] It should be noted that this application is not limited to the two methods of calculating the on-state slope resistance of the IGBT device under operating conditions, namely steps S210 and S220. Optionally, in other embodiments of this application, such as... Figure 7 As shown, the IGBT device can also be calculated at an operating point (e.g., during a measurement phase) within a single measurement phase. Figure 7 The collector-emitter voltage at the mid-Y point and the IGBT device at another operating point (e.g., Figure 7The difference ΔV between the collector and emitter voltages at point X (midpoint X) CE_on With the IGBT device at this operating point (e.g. Figure 7 The collector current at the mid-Y point and the IGBT device at another operating point (e.g., Figure 7 The difference ΔI between the collector currents at point X) C The ratio of the two values ​​is used as the on-state slope resistance R of the IGBT device under operating conditions. on As long as this operating point is located after the inflection point, the on-state slope resistance R of the IGBT device under operating conditions is sufficient. on It can be represented as:

[0103]

[0104] S300: Subtract the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions to obtain the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions.

[0105] Specifically, referring to formula (3), the collector-emitter voltage V of the IGBT device under operating conditions is... CE_on Subtract the corresponding collector current I C With the on-state slope resistance R on The product R on I C This allows us to obtain the voltage drop V′ across the virtual PiN junction of the IGBT device under operating conditions. CE_P-i-N and the collector current I of the IGBT device C The real-time monitoring value, further, can be obtained by referring to formula (4), that is, the voltage drop V′ on the virtual PiN junction. CE_P-i-N Approximately equal to the voltage drop V across the actual PiN junction CE_P-i-N Thus, the voltage drop V across the PiN junction of the IGBT device under operating conditions can be obtained. CE_P-i-N and the collector current I of the IGBT device C Real-time monitoring values.

[0106] In the aforementioned steps, the collector-emitter voltage V of the IGBT device under operating conditions has been obtained. CE_on and collector current I C The correspondence between them is as follows: Figure 7 As shown in the VI curve, and based on the collector-emitter voltage V of the IGBT device under operating conditions. CE_on and collector current I C The correspondence between them was used to calculate the on-state resistance R of the IGBT device under operating conditions. onIn step S300, subtracting the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions means subtracting the product of the collector current and the on-state slope resistance from each collector-emitter voltage of the IGBT device under operating conditions.

[0107] S400: Based on the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions, as well as the pre-obtained correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device, the junction temperature of the IGBT device is obtained.

[0108] Specifically, the voltage drop V across the PiN junction in the pre-acquired IGBT device CE_P-i-N The collector current I of the IGBT device C The corresponding relationship between the temperature T of the IGBT device and the temperature T can be found in [reference]. Figure 5 As shown, the voltage drop V across the PiN junction in IGBT devices at different temperatures T is... CE_P-i-N With the collector current I of the IGBT device C The changing VI curve family, specifically, along Figure 5 The four curves, pointing downwards along the dashed arrows, correspond to IGBT junction temperatures of 65℃, 85℃, 105℃, and 125℃, respectively.

[0109] After obtaining the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions in the aforementioned steps, these values ​​can be compared with the pre-obtained correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device. This comparison yields the temperature of the IGBT device corresponding to the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current under operating conditions, which is then used as the junction temperature of the IGBT device.

[0110] Therefore, the online measurement method for IGBT junction temperature provided in this application embodiment considers that the on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to connect the IGBT chip to the external electrical system. Furthermore, the IGBT chip in the on-state is equivalent to a PiN junction and a MOSFET device connected in series. Thus, the on-state voltage drop of the IGBT device is simplified to the sum of the PiN junction voltage drop, the MOSFET channel resistance voltage drop, and the resistance voltage drop of the connecting material. By measuring the collector-emitter voltage and collector current of the IGBT device in real time under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is estimated. The on-state slope resistance is calculated by subtracting the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions. The voltage drop is subtracted from the overall resistance consisting of the channel resistance of the MOSFET device and the resistance of the connecting materials in the collector-emitter voltage of the IGBT device under operating conditions. This yields the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions. These values ​​are then compared with pre-obtained correlations between the PiN junction voltage drop, the collector current, and the temperature of the IGBT device to obtain the junction temperature of the IGBT device. In essence, this method uses the "PiN junction voltage drop" as a new temperature-sensitive electrical parameter. Since the PiN junction voltage drop has a single negative temperature coefficient, it avoids the influence of temperature differences in the internal connecting materials of the IGBT device under different operating conditions on the temperature-sensitive electrical parameter, thereby improving the accuracy of IGBT junction temperature measurement and eliminating blind spots.

[0111] Furthermore, since the on-state slope resistance of the IGBT device under operating conditions is calculated in real time based on the collector-emitter voltage and collector current data of the IGBT device measured online, the accuracy of the real-time calculation results is not affected regardless of whether the junction temperature of the IGBT chip and the temperature of the connecting material are equal. Therefore, this method can also avoid the influence of the temperature difference of the internal connecting material of the IGBT device on the temperature-sensitive electrical parameters during the offline calibration process and actual operation, and is more suitable for online estimation of junction temperature.

[0112] Based on any of the above embodiments, optionally, in one embodiment of this application, such as Figure 8 As shown, the process of obtaining the relationship between the voltage drop across the PiN junction in the IGBT device, the collector current of the IGBT device, and the temperature of the IGBT device includes:

[0113] S10: Place the offline IGBT device in temperature chambers at different temperatures, measure the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, and obtain the corresponding relationship between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures.

[0114] It should be noted that an offline IGBT device refers to an IGBT device that is not in actual operating condition. For example, in an AC system, when the converter is interrupted, the IGBT device is in an offline state.

[0115] Specifically, after step S10, such as Figure 4 As shown, the collector-emitter voltage V of the offline IGBT device at different temperatures is obtained. CE_on and collector current I C The correspondence between them can be expressed as the collector-emitter voltage V of an offline IGBT device at different temperatures. CE_on With collector current I C The curve showing the change.

[0116] S20: Based on the correspondence between collector-emitter voltage and collector current of offline IGBT devices at different temperatures, the on-state slope resistance of offline IGBT devices at different temperatures is obtained.

[0117] It is understandable that in step S20, the on-state slope resistance of the offline IGBT device at various temperatures can be obtained based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures.

[0118] Step S20 is similar to the aforementioned step S200. Optionally, in one embodiment of this application, based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated, including:

[0119] S21: Calculate the ratio of the difference between the maximum collector-emitter voltage of the offline IGBT device at different temperatures and the collector-emitter voltage of the IGBT device at the inflection point, to the difference between the maximum collector current of the offline IGBT device at the corresponding temperature and the collector current of the IGBT device at the inflection point, and use it as the on-state slope resistance of the offline IGBT device at the corresponding temperature.

[0120] Optionally, in another embodiment of this application, based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated, including:

[0121] S22: Perform linear fitting on the relationship between collector-emitter voltage and collector current of the offline IGBT device after the inflection point at different temperatures, and obtain the slope of the fitted line as the on-state slope resistance of the offline IGBT device at the corresponding temperature.

[0122] It should be noted that this application is not limited to the two methods of calculating the on-state slope resistance of the offline IGBT device at different temperatures, namely steps S21 and S22. Optionally, in other embodiments of this application, reference can be made to... Figure 7 As shown, the calculation of an IGBT device at an operating point (e.g.) can also be performed. Figure 7 The collector-emitter voltage at the mid-Y point and the IGBT device at another operating point (e.g., Figure 7 The difference ΔV between the collector and emitter voltages at point X (midpoint X) CE_on With the IGBT device at this operating point (e.g. Figure 7 The collector current at the mid-Y point and the IGBT device at another operating point (e.g., Figure 7 The difference ΔI between the collector currents at the mid-Y point C The ratio of the two values ​​is used as the on-state slope resistance R of the IGBT device under operating conditions. on The selected work point only needs to be a work point located after the inflection point.

[0123] S30: Subtract the product of the corresponding collector current and the on-state slope resistance at the corresponding temperature from the collector-emitter voltage of the offline IGBT device at different temperatures to obtain the corresponding relationship between the voltage drop across the PiN junction and the collector current of the IGBT device at different temperatures. This relationship is used as the correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device.

[0124] Specifically, referring to formula (3), the collector-emitter voltage V of the offline IGBT device at different temperatures is calculated. CE_on Subtract the corresponding collector current I C With the on-state slope resistance R on The product R on I C This allows us to obtain the voltage drop V′ across the virtual PiN junction of the offline IGBT device at different temperatures. CE_P-i-N and the collector current I of the IGBT deviceC Furthermore, referring to formula (4), it can be seen that the voltage drop V′ on the virtual PiN junction is... CE_P-i-N Approximately equal to the voltage drop V across the actual PiN junction CE_P-i-N This allows us to obtain the voltage drop V across the PiN junction of the offline IGBT device at different temperatures. CE_P-i-N and the collector current I of the IGBT device C The correspondence between them ultimately yields the following: Figure 5 The voltage drop V across the PiN junction in the IGBT device shown CE_P-i-N The collector current I of the IGBT device C And the corresponding relationship between the temperature T of the IGBT device and the voltage drop V across the PiN junction in the IGBT device can be seen. CE_P-i-N With the collector current I of the IGBT device C The change curve has a very good one-to-one correspondence with the temperature, and there are no blind spots.

[0125] Based on the above embodiments, optionally, in one embodiment of this application, the process of pre-obtaining the inflection point includes:

[0126] S11: Based on the relationship between collector-emitter voltage and collector current of offline IGBT devices at different temperatures, the curves showing the variation of collector-emitter voltage with collector current at different temperatures for offline IGBT devices are obtained, as detailed below. Figure 4 The VI curve shown;

[0127] S12: The intersection of the collector-emitter voltage curves of offline IGBT devices at different temperatures versus collector current is taken as the inflection point.

[0128] As previously known, the inflection point C is the collector-emitter voltage V of the IGBT device. CE_on and collector current I C The temperature-independent operating point, or in other words, the collector-emitter voltage V of the IGBT device at the inflection point C at different temperatures. CE_on All are equal, and the collector current I C Since they are all equal, the intersection point of the collector-emitter voltage variation curves of offline IGBT devices with collector current at different temperatures is the inflection point C.

[0129] This application also provides an online measurement system for the junction temperature of an IGBT device. The on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to electrically connect the IGBT chip to an external source. In the on-state, the IGBT chip is equivalent to a PiN junction and a MOSFET device connected in series. Figure 9 As shown, the measurement system includes:

[0130] Measurement module 100 is used to measure the collector-emitter voltage and collector current of IGBT device under operating conditions in real time, and obtain the corresponding relationship between the collector-emitter voltage and collector current of IGBT device under operating conditions.

[0131] The calculation module 200 is used to calculate the on-state slope resistance of the IGBT device under operating conditions based on the correspondence between the collector-emitter voltage and collector current of the IGBT device under operating conditions. The on-state slope resistance of the IGBT device is the rate of change of the collector-emitter voltage relative to the collector current of the IGBT device after the inflection point. It is equivalent to the sum of the resistance of the connecting material of the IGBT device after the inflection point and the channel resistance of the MOSFET device. The inflection point is the operating point of the IGBT device where the collector-emitter voltage and collector current are independent of temperature.

[0132] The conversion module 300 is used to subtract the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions, so as to obtain the voltage drop across the PiN junction and the real-time monitoring value of the collector current of the IGBT device under operating conditions.

[0133] The calibration module 400 is used to obtain the junction temperature of the IGBT device based on the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions, as well as the pre-acquired correspondence between the voltage drop across the PiN junction, the collector current of the IGBT device, and the temperature of the IGBT device.

[0134] Optionally, the computing module 200 includes:

[0135] The first calculation unit is used to calculate the ratio of the difference between the maximum collector-emitter voltage of the IGBT device in a measurement phase and the collector-emitter voltage of the IGBT device at the inflection point, and the difference between the maximum collector current of the IGBT device in the same measurement phase and the collector current of the IGBT device at the inflection point, as the on-state slope resistance of the IGBT device under operating conditions.

[0136] Alternatively, the computing module 200 includes:

[0137] The second calculation unit is used to perform linear fitting on the relationship between the collector-emitter voltage and collector current of the IGBT device after the inflection point under operating conditions, and obtain the slope of the fitted line, which is used as the on-state slope resistance of the IGBT device under operating conditions.

[0138] Since the above processes have been described in detail in the foregoing embodiments, they will not be repeated here.

[0139] The various parts of this manual are described in a combination of parallel and progressive methods. Each part focuses on the differences between the other parts, and the same or similar parts can be referred to each other.

[0140] The features described above regarding the disclosed embodiments can be substituted or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for online measurement of junction temperature of an IGBT device, characterized in that, The on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to electrically connect the IGBT chip to an external source. The IGBT chip, in the on-state, is equivalent to a PiN junction and a MOSFET device connected in series. The method includes: The collector-emitter voltage and collector current of the IGBT device are measured in real time under operating conditions to obtain the corresponding relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions. Based on the correspondence between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated. The on-state slope resistance of the IGBT device is the rate of change of the collector-emitter voltage relative to the collector current after the inflection point of the IGBT device. It is equivalent to the sum of the resistance of the connection material and the channel resistance of the MOSFET device after the inflection point of the IGBT device. The inflection point is the temperature-independent operating point in the pre-obtained curve of the collector-emitter voltage versus collector current of the IGBT device at different temperatures. Subtracting the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions yields the voltage drop across the PiN junction and the real-time monitoring value of the collector current of the IGBT device under operating conditions. Based on the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions, as well as the pre-obtained correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device, the junction temperature of the IGBT device is obtained.

2. The online measurement method for the junction temperature of an IGBT device according to claim 1, characterized in that, Based on the relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated, including: The ratio of the difference between the maximum collector-emitter voltage of the IGBT device during a measurement phase and the collector-emitter voltage of the IGBT device at the inflection point to the difference between the maximum collector current of the IGBT device during the same measurement phase and the collector current of the IGBT device at the inflection point is used as the on-state slope resistance of the IGBT device under operating conditions.

3. The online measurement method for the junction temperature of an IGBT device according to claim 1, characterized in that, Based on the relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions, the on-state slope resistance of the IGBT device under operating conditions is calculated, including: A linear fit is performed on the relationship between the collector-emitter voltage and collector current of the IGBT device after the inflection point under operating conditions to obtain the slope of the fitted line, which is used as the on-state slope resistance of the IGBT device under operating conditions.

4. The online measurement method for the junction temperature of an IGBT device according to any one of claims 1-3, characterized in that, The process of pre-observing the relationship between the voltage drop across the PiN junction in the IGBT device, the collector current of the IGBT device, and the temperature at which the IGBT device is located includes: The offline IGBT device was placed in temperature chambers at different temperatures, and the collector-emitter voltage and collector current of the offline IGBT device at different temperatures were measured to obtain the corresponding relationship between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures. Based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated. By subtracting the product of the corresponding collector current and the on-state slope resistance at the corresponding temperature from the collector-emitter voltage of the offline IGBT device at different temperatures, the corresponding relationship between the voltage drop across the PiN junction and the collector current of the IGBT device at different temperatures is obtained. This relationship serves as the correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device.

5. The online measurement method for the junction temperature of an IGBT device according to claim 4, characterized in that, The process of obtaining the inflection point in advance includes: Based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the curves of the change of collector-emitter voltage with collector current of the offline IGBT device at different temperatures are obtained. The intersection point of the collector-emitter voltage versus collector current curves of the offline IGBT device at different temperatures is taken as the inflection point.

6. The online measurement method for the junction temperature of an IGBT device according to claim 4, characterized in that, Based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated, including: The ratio of the difference between the maximum collector-emitter voltage of the offline IGBT device at different temperatures and the collector-emitter voltage of the IGBT device at the inflection point to the difference between the maximum collector current of the offline IGBT device at the corresponding temperature and the collector current of the IGBT device at the inflection point is used as the on-state slope resistance of the offline IGBT device at the corresponding temperature.

7. The online measurement method for the junction temperature of an IGBT device according to claim 4, characterized in that, Based on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device at different temperatures, the on-state slope resistance of the offline IGBT device at different temperatures is calculated, including: Linear fitting is performed on the correspondence between the collector-emitter voltage and collector current of the offline IGBT device after the inflection point at different temperatures to obtain the slope of the fitted line, which is used as the on-state slope resistance of the offline IGBT device at the corresponding temperature.

8. An online measurement system for the junction temperature of an IGBT device, characterized in that, The on-state voltage drop of the IGBT device includes the IGBT chip voltage drop and the resistance voltage drop of the connecting material used to electrically connect the IGBT chip to an external source. The IGBT chip, in the on-state, is equivalent to a PiN junction and a MOSFET device connected in series. The measurement system includes: The measurement module is used to measure the collector-emitter voltage and collector current of the IGBT device in real time under operating conditions, and to obtain the corresponding relationship between the collector-emitter voltage and collector current of the IGBT device under operating conditions. The calculation module is used to calculate the on-state slope resistance of the IGBT device under operating conditions based on the correspondence between the collector-emitter voltage and the collector current of the IGBT device under operating conditions. The on-state slope resistance of the IGBT device is the rate of change of the collector-emitter voltage relative to the collector current after the inflection point of the IGBT device. It is equivalent to the sum of the resistance of the connection material of the IGBT device and the channel resistance of the MOSFET device after the inflection point. The inflection point is the temperature-independent operating point in the pre-obtained curve of the collector-emitter voltage versus collector current of the IGBT device at different temperatures. The conversion module is used to subtract the product of the corresponding collector current and the on-state slope resistance from the collector-emitter voltage of the IGBT device under operating conditions, so as to obtain the voltage drop across the PiN junction and the real-time monitoring value of the collector current of the IGBT device under operating conditions. The calibration module is used to obtain the junction temperature of the IGBT device based on the real-time monitoring values ​​of the voltage drop across the PiN junction and the collector current of the IGBT device under operating conditions, as well as the pre-acquired correspondence between the voltage drop across the PiN junction, the collector current, and the temperature of the IGBT device.

9. The online measurement system for IGBT device junction temperature according to claim 8, characterized in that, The computing module includes: The first calculation unit is used to calculate the ratio of the difference between the maximum collector-emitter voltage of the IGBT device in a measurement phase and the collector-emitter voltage of the IGBT device at the inflection point to the maximum collector current of the IGBT device in the same measurement phase and the collector current of the IGBT device at the inflection point, and use it as the on-state slope resistance of the IGBT device under operating conditions.

10. The online measurement system for IGBT device junction temperature according to claim 8, characterized in that, The computing module includes: The second calculation unit is used to perform linear fitting on the correspondence between the collector-emitter voltage and collector current of the IGBT device after the inflection point under the operating conditions, and obtain the slope of the fitted line as the on-state slope resistance of the IGBT device under the operating conditions.

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