SiC mosfet junction temperature monitoring method, device, equipment and medium

Abstract

The application relates to the technical field of power electronic device state monitoring, in particular to a SiC MOSFET junction temperature monitoring method, device, equipment and medium, which comprises the following steps: obtaining a through-state current and a through-state voltage of a measured silicon carbide metal oxide semiconductor field effect transistor (SiC MOSFET); calculating a through-state resistance of the SiC MOSFET according to the through-state current and the through-state voltage; and calculating a junction temperature of the SiC MOSFET according to the measured through-state resistance based on a mapping relationship between the through-state resistance and the junction temperature established in advance. Thus, the problems in the prior art that the junction temperature monitoring method can only be applied to a relatively narrow switching frequency range and the precision is seriously affected by device aging are solved, the working frequency is improved, the cost is reduced, and the influence of device aging on the junction temperature monitoring is reduced by proposing a novel through-state voltage drop online measurement circuit and a SiC MOSFET junction temperature monitoring strategy considering aging.

Description

Technical Field

[0001] This application relates to the field of power electronic device condition monitoring technology, and in particular to a method, apparatus, equipment and medium for monitoring the junction temperature of a SiC (siliconcarbide) MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Background Technology

[0002] In recent years, the reliability of power electronic converters has gradually attracted attention. Converters have the highest failure rate in power electronic systems, causing significant economic losses and safety hazards. While wide-bandgap semiconductor devices, such as SiC MOSFETs, offer higher stability, the failure rate of converters has not decreased dramatically with the widespread adoption of SiC MOSFETs. On the contrary, the reduced size and higher switching frequency have presented new challenges to the high-reliability operation of converters. According to reports, excessively high junction temperatures and junction temperature fluctuations are the main factors leading to converter failures. Therefore, online monitoring of SiC MOSFET junction temperatures is fundamental to improving the reliability of converters constructed with these devices.

[0003] In related technologies, the junction temperature monitoring method is mainly the thermistor parameter method, which calculates the junction temperature by measuring electrical parameters that are consistent with the junction temperature online. This type of method has the advantages of low invasiveness, low monitoring cost, and fast response speed. Common thermistor parameters include leakage current, on-state voltage drop, on-state resistance, saturation current, switching time, and threshold voltage. These monitoring methods have achieved certain results on Si-based IGBT (Insulated Gate Bipolar Transistor) devices, but their effect on SiC MOSFETs is unsatisfactory. The main reasons are as follows: (1) The sensitivity of thermistor parameters in SiC MOSFETs is low; (2) High switching frequency and faster switching process make it very difficult to measure dynamic parameters such as threshold voltage and switching time of SiC MOSFETs, resulting in low accuracy; (3) SiC MOSFETs have strong blocking capability, so their leakage current is small and difficult to use as a monitoring indicator; (4) The saturation current method requires changing the control strategy of the device and needs to be measured in the switching transient state, which is not suitable for SiC MOSFETs with high switching frequency. In summary, the method for measuring the thermistor electrical parameters of SiC MOSFETs still needs further improvement. Some experts have suggested that on-state resistance is a suitable indicator for monitoring the junction temperature of SiC MOSFETs. On the one hand, as a steady-state parameter, on-state resistance has stronger anti-interference capabilities and lower requirements for the sampling rate of the measurement equipment; on the other hand, measuring on-state resistance does not affect the normal operation of the device. However, this method also has two major drawbacks: (1) it can only be applied to a narrow switching frequency range; (2) its accuracy is severely affected by device aging.

[0004] Based on the above analysis, there is an urgent need for an online non-invasive junction temperature monitoring method specifically for SiC MOSFETs to provide a basis for converter condition assessment and promote the safe, economical, and high-quality operation of the converter system. Summary of the Invention

[0005] This application provides a method, apparatus, device, and medium for monitoring the condition of power electronic devices, in order to solve the problems that junction temperature monitoring methods in related technologies can only be applied to a narrow switching frequency range and that their accuracy is easily affected by device aging.

[0006] The first aspect of this application provides a method for monitoring the junction temperature of a SiC MOSFET, comprising the following steps:

[0007] Obtain the on-state current and on-state voltage of the tested metal oxide field-effect transistor (SiC MOSFET);

[0008] Calculate the on-state resistance of the SiC MOSFET based on the on-state current and on-state voltage; and

[0009] Based on a pre-established mapping relationship between on-state resistance and junction temperature, the junction temperature of the SiC MOSFET is obtained according to the on-state resistance.

[0010] According to an embodiment of the present invention, the above-described SiC MOSFET junction temperature monitoring method further includes:

[0011] Monitor the case temperature of the SiC MOSFET;

[0012] Based on the pre-established shell temperature-junction temperature thermal model, the aging reference junction temperature is obtained according to the shell temperature;

[0013] If the difference between the junction temperature and the aging reference junction temperature is less than or equal to a preset threshold, then the optimal control strategy for the SiC MOSFET is determined based on the junction temperature, and the SiC MOSFET is controlled according to the optimal control strategy; otherwise, the process returns to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET.

[0014] According to one embodiment of the present invention, before monitoring the case temperature of the SiC MOSFET, the method further includes:

[0015] Determine whether the current monitoring duration has reached the preset monitoring duration;

[0016] If the current monitoring duration reaches the preset monitoring duration, the case temperature of the SiC MOSFET is monitored.

[0017] According to one embodiment of the present invention, the preset monitoring duration is 100 switching cycles.

[0018] According to an embodiment of the present invention, a pre-established shell-junction temperature thermal model is used.

[0019] T jr =T c +R j-c (E sw f sw +I DS 2 R ON );

[0020] Among them, T jr For aging reference junction temperature, T C For shell temperature, R j-c For the thermal resistance between the shell and the junction, E SW For the single-switching loss of SiC MOSFET, f sw For switching frequency, I DS For the on-state current, R ON This is the on-state resistance.

[0021] According to one embodiment of the present invention, before obtaining the junction temperature of the SiC MOSFET based on the on-state resistance according to the pre-established mapping relationship between the on-state resistance and the junction temperature, the method further includes:

[0022] The pre-established mapping relationship between on-state resistance and junction temperature is obtained based on the double-pulse test;

[0023] The pre-established mapping relationship between on-state resistance and junction temperature is stored in the DSP (Digital Signal Processor).

[0024] The SiC MOSFET junction temperature monitoring method according to embodiments of this application calculates the on-state resistance of the SiC MOSFET by acquiring its on-state current and on-state voltage, and obtains the junction temperature of the SiC MOSFET based on a pre-established mapping relationship between on-state resistance and junction temperature. This solves the problems of related technologies where junction temperature monitoring methods can only be applied to a narrow switching frequency range and whose accuracy is severely affected by device aging. By proposing a novel online on-state voltage drop measurement circuit and a SiC MOSFET junction temperature monitoring strategy that considers aging, the operating frequency is improved, costs are reduced, and the impact of device aging on junction temperature monitoring is minimized.

[0025] A second aspect of this application provides a SiC MOSFET junction temperature monitoring device, comprising:

[0026] The first acquisition module is used to acquire the on-state current and on-state voltage of the silicon carbide metal oxide field-effect transistor (SiC MOSFET) under test.

[0027] A calculation module is used to calculate the on-state resistance of the SiC MOSFET based on the on-state current and the on-state voltage; and

[0028] The first monitoring module is used to obtain the junction temperature of the SiC MOSFET based on the on-state resistance, according to a pre-established mapping relationship between the on-state resistance and the junction temperature.

[0029] According to an embodiment of the present invention, the above-described SiC MOSFET junction temperature monitoring device further includes:

[0030] The second monitoring module is used to monitor the case temperature of the SiC MOSFET;

[0031] The second acquisition module is used to obtain the aging reference junction temperature based on the shell temperature and the shell temperature, according to the preset shell temperature-junction temperature thermal model.

[0032] The judgment module is used to determine the optimal control strategy of the SiC MOSFET based on the junction temperature if the difference between the junction temperature and the aging reference junction temperature is less than or equal to a preset threshold, and to control the SiC MOSFET according to the optimal control strategy; otherwise, it returns to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET.

[0033] According to one embodiment of the present invention, before monitoring the case temperature of the SiC MOSFET, the second monitoring module is further configured to:

[0034] Determine whether the current monitoring duration has reached the preset monitoring duration;

[0035] If the current monitoring duration reaches the preset monitoring duration, the case temperature of the SiC MOSFET is monitored.

[0036] According to one embodiment of the present invention, the preset monitoring duration is 100 switching cycles.

[0037] According to an embodiment of the present invention, a pre-established shell-junction temperature thermal model is used.

[0038] T jr =T c +R j-c (E sw f sw +I DS 2 R ON );

[0039] Among them, T jr For aging reference junction temperature, T C For shell temperature, R j-c For the thermal resistance between the shell and the junction, E SW For the single-switching loss of SiC MOSFET, f sw For switching frequency, I DS For the on-state current, R ON This is the on-state resistance.

[0040] According to one embodiment of the present invention, before determining the junction temperature of the SiC MOSFET based on the on-state resistance according to the pre-established mapping relationship between the on-state resistance and the junction temperature, the first monitoring module is further configured to:

[0041] The pre-established mapping relationship between on-state resistance and junction temperature is obtained based on the double-pulse test;

[0042] The pre-established mapping relationship between on-state resistance and junction temperature is stored in the digital signal processor (DSP).

[0043] The SiC MOSFET junction temperature monitoring device according to embodiments of this application calculates the on-state resistance of the SiC MOSFET by acquiring its on-state current and on-state voltage, and obtains the junction temperature of the SiC MOSFET based on a pre-established mapping relationship between on-state resistance and junction temperature. This solves the problems of related technologies where junction temperature monitoring methods can only be applied to a narrow switching frequency range and whose accuracy is severely affected by device aging. By proposing a novel online on-state voltage drop measurement circuit and a SiC MOSFET junction temperature monitoring strategy that considers aging, the operating frequency is improved, the cost is reduced, and the impact of device aging on junction temperature monitoring is minimized.

[0044] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the SiC MOSFET junction temperature monitoring method as described in the above embodiments.

[0045] A fourth aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the SiC MOSFET junction temperature monitoring method as described in the above embodiments.

[0046] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0047] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0048] Figure 1 This refers to an online on-state voltage drop measurement circuit in related technologies.

[0049] Figure 2 Junction temperature monitoring strategies in related technologies;

[0050] Figure 3 This is a schematic diagram of a SiC MOSFET junction temperature monitoring method based on on-state resistance according to an embodiment of this application;

[0051] Figure 4 This is a flowchart illustrating a SiC MOSFET junction temperature monitoring method according to an embodiment of this application.

[0052] Figure 5 This is a schematic diagram of the on-state voltage drop and other related parameter waveforms after the converter is in operation, according to an embodiment of this application.

[0053] Figure 6 This is a schematic diagram of an on-state voltage drop measurement circuit and a dual-pulse test circuit according to an embodiment of this application;

[0054] Figure 7 This is a schematic diagram illustrating the relationship between on-state resistance and junction temperature according to an embodiment of this application;

[0055] Figure 8 This is a schematic diagram of a SiC MOSFET thermal model according to an embodiment of this application;

[0056] Figure 9 T is provided in various cases according to an embodiment of this application. correct Schematic diagram;

[0057] Figure 10 This is a schematic diagram of a double-pulse test waveform provided according to an embodiment of this application;

[0058] Figure 11 This is a schematic diagram of calibration results provided according to an embodiment of this application;

[0059] Figure 12 This is an example diagram of a SiC MOSFET junction temperature monitoring device according to an embodiment of this application;

[0060] Figure 13 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0061] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0062] The following description, with reference to the accompanying drawings, describes a SiC MOSFET junction temperature monitoring method, apparatus, device, and dielectric according to embodiments of this application. Addressing the issues mentioned in the background section regarding the limitations of existing junction temperature monitoring methods—which are limited to a narrow switching frequency range and whose accuracy is severely affected by device aging—this application provides a SiC MOSFET junction temperature monitoring method. In this method, the on-state resistance of the SiC MOSFET is calculated by acquiring its on-state current and on-state voltage. Based on a pre-established mapping relationship between on-state resistance and junction temperature, the junction temperature of the SiC MOSFET is obtained from the on-state resistance. This solves the problems of existing junction temperature monitoring methods being limited to a narrow switching frequency range and their accuracy being severely affected by device aging. By proposing a novel online on-state voltage drop measurement circuit and a SiC MOSFET junction temperature monitoring strategy that considers aging, the operating frequency is improved, costs are reduced, and the impact of device aging on junction temperature monitoring is minimized.

[0063] Before introducing the embodiments of this application, we will first introduce the related technology of SiC MOSFET junction temperature monitoring method based on on-state resistance.

[0064] Specifically, calculating the on-state resistance in related technologies requires simultaneous measurement of both the on-state voltage drop and the on-state current. Measuring the on-state current is relatively easy due to its large amplitude, while measuring the on-state voltage drop is more difficult and therefore requires specialized measurement circuitry. For example... Figure 1 As shown, this circuit illustrates a forward voltage drop measurement circuit in related technologies, consisting of passive components, operational amplifiers, and transistors. The function of this circuit is to shield the bus high-voltage protection measurement ADC (Analog-to-digital converter) when the SiC MOSFET under test is in a resistive state, thereby enabling online measurement of the forward voltage drop.

[0065] Furthermore, such as Figure 2 As shown, it illustrates a junction temperature monitoring strategy based on on-state resistance, which is based on... Figure 1 The circuit shown is based on the online measurement circuit for on-state voltage drop. Figure 2 China V ON (k) represents the on-state voltage drop measurement result at time k, i ds (k) represents the on-state current measurement result at time k, θ j-est (k) represents the estimated junction temperature at time k. The on-state resistance can be calculated using the on-state voltage drop and on-state current, and then the junction temperature can be calculated based on the relationship between the on-state resistance and junction temperature obtained from offline testing.

[0066] The above technical solutions also have some technical defects: (1) The on-state voltage drop measurement circuit can only operate at switching frequencies below 80kHz. The switching frequency of a typical SiC MOSFET is greater than 100kHz. Therefore, if this method is to be used to monitor the junction temperature, the converter must operate at a lower frequency. As a result, the excellent performance of the SiC MOSFET will not be reflected. (2) The on-state resistance is not only related to the junction temperature but also changes with the aging of the device. Therefore, the monitoring accuracy will decrease as the aging degree of the SiC MOSFET increases.

[0067] Therefore, regarding the aforementioned SiC MOSFET junction temperature monitoring method based on on-state resistance, this application embodiment will address the problems existing in related technical monitoring methods by employing a novel online SiC MOSFET junction temperature monitoring method using a novel high-frequency on-state voltage drop measurement circuit, such as... Figure 3 As shown, the following discussion will take the junction temperature monitoring of a three-phase two-level converter composed of six C2M0080120D SiC MOSFETs as an example.

[0068] Specifically, Figure 4 This is a schematic flowchart of a SiC MOSFET junction temperature monitoring method provided in an embodiment of this application.

[0069] like Figure 4 As shown, the SiC MOSFET junction temperature monitoring method includes the following steps:

[0070] In step S401, the on-state current and on-state voltage of the tested metal oxide field-effect transistor (SiC MOSFET) are acquired.

[0071] Specifically, after the monitored converter starts working, the current probe measures the on-state single current I of the tested SiC MOSFET. DS The voltage probe measures the on-state voltage V of the SiC MOSFET using the proposed measurement circuit. ON The SiC MOSFET under test is located in the lower arm of the C phase, so when measuring V... ON At the same time, the C-phase current I also needs to be measured. C The specific measurement results are as follows: Figure 5 As shown, V mea The on-state voltage of the measured circuit is the voltage of the on-state voltage. Subtracting the diode voltage gives the on-state voltage of the SiC MOSFET being measured.

[0072] In step S402, the on-state resistance of the SiC MOSFET is calculated based on the on-state current and on-state voltage.

[0073] Specifically, the on-state current and on-state voltage of the SiC MOSFET are measured using the aforementioned current and voltage probes, and the on-state resistance R of the SiC MOSFET is calculated based on the on-state current and on-state voltage. ON .

[0074] In step S403, based on the pre-established mapping relationship between on-state resistance and junction temperature, the junction temperature of the SiC MOSFET is obtained according to the on-state resistance.

[0075] Furthermore, in some embodiments, before obtaining the junction temperature of the SiC MOSFET based on the on-state resistance according to the pre-established mapping relationship between on-state resistance and junction temperature, the method further includes: obtaining the pre-established mapping relationship between on-state resistance and junction temperature according to a double-pulse test; and storing the pre-established mapping relationship between on-state resistance and junction temperature in a digital signal processor (DSP).

[0076] Specifically, in this embodiment, the pre-established on-state resistance R is first obtained through a double-pulse test. ON and junction temperature T j The mapping relationship between them is established and stored in the DSP, and combined with the dual-pulse test circuit topology of the on-state voltage measurement circuit. For example... Figure 6 As shown, the on-state voltage measurement circuit consists of two diodes, two resistors, a current source, an operational amplifier, and an auxiliary MOSFET M2. M1 is a SiC MOSFET that is being monitored. Its specific implementation is as follows:

[0077] First, a double-pulse signal is triggered during the double-pulse test. When the drive voltage is high, M1 is turned on, and the DC power supply charges the inductor L at a constant voltage, resulting in an on-state current I. DS The voltage increases linearly. At this point, the current source in the on-state voltage measurement circuit flows through R1, D1, and M1. Since this current is very small, the voltage at the measurement point is approximately the on-state voltage of M1 plus the diode's point voltage. When the drive voltage is low, M1 is turned off, and the current in inductor L freewheels through diode D3. At this time, due to the inverter, M2 is on-state, and the current source flows through D2, R2, and M2. Therefore, the voltage at the measurement point is equal to the on-state voltage of M2 plus the diode voltage of D2. The bus voltage is shielded by diode D1. Since the operating frequency of the on-state voltage measurement circuit depends on the switching frequency of M2, the upper frequency limit is greatly increased.

[0078] Secondly, by changing the junction temperature of M1 using a temperature control box and adjusting the DC power supply voltage, the on-state current and on-state voltage at each junction temperature are measured. Then, the on-state resistance at each junction temperature can be obtained, such as... Figure 7 As shown, the relationship between on-state resistance and junction temperature can be expressed as follows after linear regression:

[0079] R ON =0.6181T j +64.004; (1)

[0080] Furthermore, based on the on-state resistance R ON The mapping relationship between the calculation results and the junction temperature can be used to obtain the junction temperature T of the SiC MOSFET. j .

[0081] Furthermore, in some embodiments, the above-described SiC MOSFET junction temperature monitoring method further includes: monitoring the case temperature of the SiC MOSFET; obtaining an aging reference junction temperature based on a preset case temperature-junction temperature thermal model; if the difference between the junction temperature and the aging reference junction temperature is less than or equal to a preset threshold, determining the optimal control strategy for the SiC MOSFET based on the junction temperature, and controlling the SiC MOSFET according to the optimal control strategy; otherwise, returning to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET.

[0082] Furthermore, in some embodiments, before monitoring the case temperature of the SiC MOSFET, the method further includes: determining whether the monitoring duration has reached a preset monitoring duration; if the monitoring duration has reached the preset monitoring duration, then monitoring the case temperature of the SiC MOSFET.

[0083] The predicted monitoring duration can be a threshold set by the user or a threshold obtained through multiple computer simulations; no specific limitation is made here.

[0084] Specifically, in this embodiment of the application, the measured SiC MOSFET junction temperature T is established. j and shell temperature T c The thermal model between them is used for aging reference junction temperature T. jr The calculation. For example... Figure 8 The diagram shown illustrates a schematic of the thermal model of a SiC MOSFET. Where Z... j-c It represents the thermal resistance between the crust and the metal, and can also be written as R. j-c ;P loss Representing the total loss, its expression can be given as:

[0085] P loss =E sw f sw +I DS 2 R ON (2)

[0086] Among them, E SW f represents the single-cycle switching loss of a SiC MOSFET. swIndicates the switching frequency.

[0087] Furthermore, in this embodiment, the case temperature of the SiC MOSFET is measured based on a thermal model, and the aging reference junction temperature is estimated based on the thermal model and the calculated losses. Since aging does not require real-time monitoring, the junction temperature is calculated every 100 switching cycles, i.e., the preset monitoring duration is 100 switching cycles. Therefore, the relationship between the aging reference junction temperature and the case temperature can be expressed as:

[0088] T jr =T c +R j-c (E sw f sw +I DS 2 R ON (3)

[0089] Furthermore, according to the datasheet, the R of the SiC MOSFET in the embodiments of this application is... j-c It is 0.6 W / ℃.

[0090] E SW It can be represented as:

[0091] E sw =0.342I DS 2 +3.718I DS +40.61; (4)

[0092] Specifically, the temperature difference T between the junction temperature and the shell temperature can be obtained through the calculations of equations (1) to (4) above. correct Its expression is:

[0093] T correct =R j-c (E sw f sw +I DS 2 (0.6181T j +64.004)); (5)

[0094] A temperature difference graph between the junction temperature and the case temperature can be generated by analyzing the temperature difference between the junction temperature and the case temperature. Figure 9 As shown, when it is necessary to calculate T jr At this point, it is sufficient to find the corresponding on-state current and junction temperature.

[0095] Furthermore, the SiC MOSFET junction temperature monitoring method in this embodiment of the application also needs to calculate the difference between the junction temperature and the aging reference junction temperature, and determine whether the difference is less than or equal to a preset threshold. If the difference between the junction temperature and the aging reference junction temperature is less than or equal to the preset threshold, such as 5°C, then the optimal control strategy for the SiC MOSFET is determined based on the junction temperature, and the SiC MOSFET is controlled according to the optimal control strategy, as shown in Table 1.

[0096] Table 1

[0097]

[0098] Table 1 shows the junction temperature monitoring results of healthy SiC MOSFETs. It can be seen that the error between the monitored junction temperature and the aging reference junction temperature is approximately less than 2℃.

[0099] Furthermore, if the difference between the junction temperature and the aging reference junction temperature is greater than a preset threshold, the process returns to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET, as shown in Table 2.

[0100] Table 2

[0101]

[0102] Table 2 shows the junction temperature monitoring results of the SiC MOSFET under aging conditions. It can be seen that the error becomes very large, far exceeding the 5℃ error threshold, therefore recalibration is required. The recalibration results are shown in the following formula.

[0103] T j =1.351R ON -92.124; (6)

[0104] The monitoring results, as shown in Table 3, were obtained by recalculating the junction temperature. It can be seen that the monitoring error was reduced to the threshold range again.

[0105] Table 3

[0106]

[0107] Specifically, based on the analysis of the above methods, in the process of determining the mapping relationship between on-state resistance and junction temperature through double-pulse testing, it is also necessary to verify it. The specific verification method is as follows:

[0108] First, the on-state voltage online measurement circuit of the embodiments of this application is tested, such as... Figure 10 As shown, the waveform of the double-pulse test is displayed, and it can be seen from V mea The magnitude of the on-state voltage of the SiC MOSFET under test can be clearly read from the data.

[0109] Secondly, according to Figure 11 As shown, the relationship between the on-state resistance and junction temperature of SiCMOSFET can be obtained from the calibration results of the double-pulse test, as shown in formula (1).

[0110] In summary, the main inventive points of the embodiments of this application are:

[0111] (1) A novel on-state voltage drop online measurement circuit is proposed, which features low cost and high operating frequency, and can be matched with the high switching frequency of SiC MOSFETs. This circuit greatly improves the upper limit of the applicable frequency of the SiC MOSFET junction temperature monitoring method based on on-state resistance.

[0112] (2) Based on this, a SiC MOSFET junction temperature monitoring strategy considering aging is proposed. A reference junction temperature T is established. jr Monitoring junction temperature T j and T jr The difference can reflect the degree of aging of the device. When the interpolation difference exceeds a certain threshold, T needs to be recalibrated. j and on-state resistance R ON This relationship allows for the partial elimination of the impact of device aging on accuracy.

[0113] Therefore, the advantages of the embodiments of this application compared with related technologies are as follows:

[0114] (1) To address the limitation that on-state voltage drop measurement circuits can only operate at switching frequencies below 80kHz, a novel online on-state voltage drop measurement circuit is proposed. This circuit features low cost and high operating frequency, making it compatible with the high switching frequency requirements of SiC MOSFETs. This circuit significantly improves the upper limit of the applicable frequency for SiC MOSFET junction temperature monitoring methods based on on-state resistance.

[0115] (2) To address the issue that monitoring accuracy decreases with increasing SiC MOSFET aging, a SiC MOSFET junction temperature monitoring strategy that takes aging into account is proposed. Compared with related technologies, this monitoring strategy can reduce the impact of device aging on junction temperature monitoring and ensure that the error does not increase during long-term monitoring.

[0116] The SiC MOSFET junction temperature monitoring method according to embodiments of this application calculates the on-state resistance of the SiC MOSFET by acquiring its on-state current and on-state voltage, and obtains the junction temperature of the SiC MOSFET based on a pre-established mapping relationship between on-state resistance and junction temperature. This solves the problems of related technologies where junction temperature monitoring methods can only be applied to a narrow switching frequency range and whose accuracy is severely affected by device aging. By proposing a novel online on-state voltage drop measurement circuit and a SiC MOSFET junction temperature monitoring strategy that considers aging, the operating frequency is improved, costs are reduced, and the impact of device aging on junction temperature monitoring is minimized.

[0117] Next, referring to the accompanying drawings, a SiC MOSFET junction temperature monitoring device according to an embodiment of this application is described.

[0118] Figure 12 This is a block diagram of a SiC MOSFET junction temperature monitoring device according to an embodiment of this application.

[0119] like Figure 12 As shown, the SiC MOSFET junction temperature monitoring device 10 includes: a first acquisition module 100, a calculation module 200, and a first monitoring module 300.

[0120] The first acquisition module 100 is used to acquire the on-state current and on-state voltage of the silicon carbide metal oxide field-effect transistor (SiC MOSFET) under test.

[0121] Calculation module 200 is used to calculate the on-state resistance of the SiC MOSFET based on the on-state current and on-state voltage; and

[0122] The first monitoring module 300 is used to obtain the junction temperature of the SiC MOSFET based on the on-state resistance according to a pre-established mapping relationship between on-state resistance and junction temperature.

[0123] Furthermore, in some embodiments, the SiC MOSFET junction temperature monitoring device 10 described above further includes:

[0124] The second monitoring module is used to monitor the case temperature of the SiC MOSFET;

[0125] The second acquisition module is used to obtain the aging reference junction temperature based on the shell temperature and the preset shell temperature-junction temperature thermal model.

[0126] The judgment module is used to determine the optimal control strategy for the SiC MOSFET based on the junction temperature if the difference between the junction temperature and the aging reference junction temperature is less than or equal to a preset threshold, and to control the SiC MOSFET according to the optimal control strategy; otherwise, it returns to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET.

[0127] Furthermore, in some embodiments, before monitoring the case temperature of the SiC MOSFET, the second monitoring module is also used for:

[0128] Determine whether the current monitoring duration has reached the preset monitoring duration;

[0129] If the current monitoring duration reaches the preset monitoring duration, the case temperature of the SiC MOSFET will be monitored.

[0130] Furthermore, in some embodiments, the preset monitoring duration is 100 switching cycles.

[0131] Furthermore, in some embodiments, a pre-established shell-junction temperature thermal model is used.

[0132] T jr =T c +R j-c (E sw f sw +I DS 2 R ON );

[0133] Among them, T jr For aging reference junction temperature, T C For shell temperature, R j-c For the thermal resistance between the shell and the junction, E SW For the single-switching loss of SiC MOSFET, f sw For switching frequency, I DS For the on-state current, R ON This is the on-state resistance.

[0134] Furthermore, in some embodiments, before determining the junction temperature of the SiC MOSFET based on the on-state resistance according to a pre-established mapping relationship between on-state resistance and junction temperature, the first monitoring module 300 is also configured to:

[0135] The pre-established mapping relationship between on-state resistance and junction temperature is obtained based on the double-pulse test;

[0136] The pre-established mapping relationship between on-state resistance and junction temperature is stored in the digital signal processor (DSP).

[0137] The SiC MOSFET junction temperature monitoring device according to embodiments of this application calculates the on-state resistance of the SiC MOSFET by acquiring its on-state current and on-state voltage, and obtains the junction temperature of the SiC MOSFET based on a pre-established mapping relationship between on-state resistance and junction temperature. This solves the problems of related technologies where junction temperature monitoring methods can only be applied to a narrow switching frequency range and whose accuracy is severely affected by device aging. By proposing a novel online on-state voltage drop measurement circuit and a SiC MOSFET junction temperature monitoring strategy that considers aging, the operating frequency is improved, the cost is reduced, and the impact of device aging on junction temperature monitoring is minimized.

[0138] Figure 13 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0139] The memory 1301, the processor 1302, and the computer program stored on the memory 1301 and executable on the processor 1302.

[0140] When the processor 1302 executes the program, it implements the SiC MOSFET junction temperature monitoring method provided in the above embodiments.

[0141] Furthermore, electronic devices also include:

[0142] Communication interface 1303 is used for communication between memory 1301 and processor 1302.

[0143] The memory 1301 is used to store computer programs that can run on the processor 1302.

[0144] The memory 1301 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0145] If the memory 1301, processor 1302, and communication interface 1303 are implemented independently, then the communication interface 1303, memory 1301, and processor 1302 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be divided into address buses, data buses, control buses, etc. For ease of representation, Figure 13The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0146] Optionally, in a specific implementation, if the memory 1301, processor 1302, and communication interface 1303 are integrated on a single chip, then the memory 1301, processor 1302, and communication interface 1303 can communicate with each other through an internal interface.

[0147] The processor 1302 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0148] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the SiC MOSFET junction temperature monitoring method described above.

[0149] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0150] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0151] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0152] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0153] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0154] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware, and the program can be stored in a computer-readable storage medium. When executed, the program includes one or a combination of the steps of the method embodiments.

[0155] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0156] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for monitoring the junction temperature of a SiC MOSFET, characterized in that, Includes the following steps: Obtain the on-state current and on-state voltage of the silicon carbide metal oxide field-effect transistor (SiC MOSFET) under test; Calculate the on-state resistance of the SiC MOSFET based on the on-state current and the on-state voltage; Based on the pre-established mapping relationship between on-state resistance and junction temperature, the junction temperature of the SiC MOSFET is obtained according to the on-state resistance; Also includes: Monitor the case temperature of the SiC MOSFET; Based on the pre-established shell temperature-junction temperature thermal model, the aging reference junction temperature is obtained according to the shell temperature; If the difference between the junction temperature and the aging reference junction temperature is less than or equal to a preset threshold, then the optimal control strategy for the SiC MOSFET is determined based on the junction temperature, and the SiC MOSFET is controlled according to the optimal control strategy; otherwise, the process returns to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET. Before determining the junction temperature of the SiC MOSFET based on the pre-established mapping relationship between the on-state resistance and the junction temperature, the method further includes: The pre-established mapping relationship between on-state resistance and junction temperature is obtained based on the double-pulse test; The pre-established mapping relationship between on-state resistance and junction temperature is stored in the digital signal processor (DSP).

2. The method according to claim 1, characterized in that, Before monitoring the case temperature of the SiC MOSFET, the following is also included: Determine whether the monitoring duration has reached the preset monitoring duration; If the monitoring duration reaches the preset monitoring duration, the case temperature of the SiC MOSFET is monitored.

3. The method according to claim 2, characterized in that, The preset monitoring duration is 100 switching cycles.

4. The method according to claim 1, characterized in that, Pre-established shell-junction temperature thermal model ； in, T jr For aging reference junction temperature, T C For shell temperature, R j-c For the thermal resistance between the shells, E SW For the single switching loss of SiC MOSFET, f sw For switching frequency, I DS For on-state current, R ON This is the on-state resistance.

5. A SiC MOSFET junction temperature monitoring device, characterized in that, include: The first acquisition module is used to acquire the on-state current and on-state voltage of the SiC MOSFET under test; A calculation module is used to calculate the on-state resistance of the SiC MOSFET based on the on-state current and the on-state voltage; as well as The first monitoring module is used to obtain the junction temperature of the SiC MOSFET based on the pre-established mapping relationship between the on-state resistance and the junction temperature. Also includes: The second monitoring module is used to monitor the case temperature of the SiC MOSFET; The second acquisition module is used to obtain the aging reference junction temperature based on the shell temperature and the shell temperature, according to the preset shell temperature-junction temperature thermal model. If the difference between the junction temperature and the aging reference junction temperature is less than or equal to a preset threshold, the determination module determines the optimal control strategy for the SiC MOSFET based on the junction temperature and controls the SiC MOSFET according to the optimal control strategy; otherwise, it returns to the step of obtaining the on-state current and on-state voltage of the SiC MOSFET. Before determining the junction temperature of the SiC MOSFET based on the pre-established mapping relationship between on-state resistance and junction temperature, the first monitoring module is further configured to: The pre-established mapping relationship between on-state resistance and junction temperature is obtained based on the double-pulse test; The pre-established mapping relationship between on-state resistance and junction temperature is stored in the digital signal processor (DSP).

6. The apparatus according to claim 5, characterized in that, Before monitoring the case temperature of the SiC MOSFET, the second monitoring module is further configured to: Determine whether the current monitoring duration has reached the preset monitoring duration; If the current monitoring duration reaches the preset monitoring duration, the case temperature of the SiC MOSFET is monitored.

7. The apparatus according to claim 6, characterized in that, The preset monitoring duration is 100 switching cycles.

8. The apparatus according to claim 5, characterized in that, Pre-established shell-junction temperature thermal model ； in, T jr For aging reference junction temperature, T C For shell temperature, R j-c For the thermal resistance between the shells, E SW For the single switching loss of SiC MOSFET, f sw For switching frequency, I DS For on-state current, R ON This is the on-state resistance.

9. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the SiC MOSFET junction temperature monitoring method as described in any one of claims 1-4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the SiC MOSFET junction temperature monitoring method as described in any one of claims 1-4.

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