An on-line measurement system for SiC MOSFET aging parameters

Abstract

The present invention relates to the technical field of semiconductor device monitoring, and provides an on-line measurement system for aging parameters of SiC MOSFETs. The aging parameters include threshold voltage and on-resistance. The on-line measurement system includes a body effect monitoring module, a gate drive monitoring module, and a mutual verification module. Through the technical solution provided by the present application, on the one hand, it realizes on-line real-time measurement of aging characteristic parameters without affecting the normal operation of power devices, solves the problem that device on-line operation and aging monitoring cannot be carried out simultaneously, can detect potential aging problems of SiC MOSFETs in advance, take preventive measures, and avoid system failures; on the other hand, the present invention improves the accuracy of monitoring and early warning by integrating two sets of on-line real-time monitoring methods of body effect and gate drive to carry out monitoring respectively and conduct comparative analysis and cross-analysis of monitoring data and their trend data, and solves the problem of false alarms caused by monitoring errors of only using one set of monitoring methods, and timely mutual verification improves the accuracy of the monitoring scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device monitoring, and particularly to an on-line measurement system for aging parameters of SiC MOSFETs. Background Art

[0002] SiC MOSFETs (Silicon Carbide Metal Oxide Semiconductor Field Effect Transistors) have advantages such as high switching frequency, high efficiency and low loss, excellent thermal performance, and high reliability, making them widely used in fields such as electric vehicles, solar inverters, fast charging stations, data centers, and industrial motor drives. As the core component of power electronic devices, SiC MOSFETs are prone to various fatigue aging phenomena during long-term operation, such as gate oxide degradation, bias temperature instability (BTI), etc. These aging phenomena will lead to a decline in device performance and even failure, thus affecting the reliable operation of the entire system. Through aging monitoring, potential problems can be discovered in advance, and preventive measures can be taken to avoid system failures.

[0003] The aging problems of SiC MOSFETs mainly involve the degradation of their gate oxides, bias temperature instability (BTI), package failure, and short-circuit tolerance. Current aging monitoring methods include off-line and on-line methods. Off-line monitoring usually needs to be carried out after the device is shut down or disassembled, and the aging state of the device is evaluated through laboratory equipment or accelerated aging experiments, which is not suitable for monitoring devices that are in operation. On-line monitoring refers to obtaining the aging state of the device in real time through specific monitoring circuits and methods when the SiC MOSFET is in normal operation or off state, without the need to shut down or disassemble the device. However, on-line monitoring methods are prone to interfering with the normal operation of the device. Due to the complexity of on-line monitoring of aging parameters such as threshold voltage and on-resistance, the accuracy of on-line monitoring is often inferior to that of off-line monitoring.

[0004] In order not to affect the normal operation of power devices and be able to on-line monitor the aging of SiC MOSFETs to discover potential problems in advance and take preventive measures, it is necessary to develop a system that can not only on-line monitor aging parameters in real time, but also does not interfere with the normal operation of SiC MOSFETs, and has high accuracy in monitoring aging parameters. Summary of the Invention

[0005] Based on the above situation, the main purpose of the present invention is to provide an on-line measurement system for aging parameters of SiC MOSFETs, which can realize on-line real-time measurement of aging characteristic parameters, and can perform comparative analysis and cross-analysis on monitoring data and its trend data to improve the accuracy of monitoring and early warning.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0007] The present invention provides an on-line measurement system for aging parameters of SiC MOSFETs. The aging parameters include threshold voltage and on-resistance. The on-line measurement system includes a body effect monitoring module, a gate drive monitoring module, and a mutual verification module. The body effect monitoring module is used to collect the relationship curve between the source-drain voltage and the gate voltage by applying a constant measurement current during the gate switching process of the SiC MOSFET to extract the threshold voltage under the body effect. It is also used to calculate the on-resistance under the body effect by applying a constant measurement current to the source-drain of the SiC MOSFET and monitoring its conduction voltage. The gate drive monitoring module is used to apply a pre-bias voltage and a scan voltage to the gate at intervals using an electric quantity measurement unit and monitor the gate voltage when the drain current reaches a specified value, which is the threshold voltage under the gate drive. It is also used to evaluate the on-resistance under the gate drive by monitoring the change in gate charge during the switching process of the SiC MOSFET. The mutual verification module is used to separately track and record and plot the change trends of the threshold voltage under the body effect monitoring and the gate drive, and separately track and record and plot the change trends of the on-resistance under the body effect monitoring and the gate drive monitoring. If the two change trends are respectively consistent and the data is within the normal range, continuous normal monitoring is carried out. If the two change trends are respectively consistent but the data is abnormal, an aging warning for the SiC MOSFET is issued. If more than one of the two change trends is inconsistent, the two monitoring modules are calibrated and then re-monitored.

[0008] Further, the body effect monitoring module includes: a control circuit, an oscilloscope, a voltage source, a constant current source, and a host computer. The control circuit is used to switch different measurement modes through a relay to achieve gate biasing and electrical parameter measurement. The oscilloscope is used to collect the source-drain voltage-gate-source voltage waveform data and record the voltage changes during the switching process. The voltage source and the constant current source are used to provide the gate bias voltage and the measurement current to measure the threshold voltage and the on-resistance. The host computer is used for data processing and analysis, processes the collected waveform data, calculates, and tracks and records the threshold voltage and the on-resistance.

[0009] Further, the specific measurement steps for the threshold voltage under the body effect include: pre-bias processing: applying a pre-bias voltage to the gate according to the pre-bias setting time; interval time: after the pre-bias is completed, according to a predetermined time interval; applying the measurement current: after the pre-bias is completed and a certain interval time is set, when the SiC MOSFET is operating in the third quadrant, applying a constant source-drain current through the constant current source; collecting and plotting the source-drain voltage-gate-source voltage curve: during the gate voltage switching process, collecting and plotting the relationship curve between the source-drain voltage and the gate voltage; extracting the threshold voltage: when the source voltage no longer changes with the gate voltage, the corresponding gate voltage is the threshold voltage under the body effect.

[0010] Further, the specific measurement steps of the on-resistance under the body effect include: calculating the on-resistance: extracting the source-drain voltage and the source-drain current, and calculating the ratio of the source-drain voltage to the source-drain current, which is the on-resistance under the body effect.

[0011] Further, the gate drive monitoring module is a dual-channel drive chip integrated in the gate driver of the SiC MOSFET, and the dual-channel drive chip provides a drive current output that supports real-time variable drive strength.

[0012] Further, the specific measurement steps of the threshold voltage under the gate drive include: gate pre-biasing: using a gate pre-biasing circuit to pre-bias the device under test, and applying a specified gate pre-biasing voltage and gate pre-biasing time by a DC power supply with an ammeter; after the pre-biasing is completed, cut off the gate pre-biasing voltage and pass through a specified interval time; gate voltage scanning: after the interval time ends, apply a gate scanning voltage by a variable DC voltage source with an ammeter according to the specified threshold voltage scanning direction, scanning range, and test time; at the same time, synchronously monitor the drain current; reading the threshold voltage: when the drain current monitored by the variable DC voltage source with an ammeter reaches the specified value, read the corresponding gate-source voltage, which is the threshold voltage under the gate drive.

[0013] Further, the specific measurement steps of the on-resistance under the gate drive include: measuring the drain-source voltage: while monitoring the drain current, measure the drain-source voltage; calculating the on-resistance: extracting the drain-source voltage and the drain current, and calculating the ratio of the drain-source voltage to the drain current, which is the on-resistance under the gate drive.

[0014] Further, the mutual verification module can be integrated in the upper computer, and trend comparison analysis and cross-comparison analysis are performed by extracting the threshold voltage and on-resistance data of the body effect monitoring module and the gate drive monitoring module.

[0015] Further, the trend comparison analysis refers to separately analyzing the threshold voltage change trend and the on-resistance change trend to judge the aging condition of the SiC MOSFET.

[0016] Further, the cross-comparison analysis refers to performing a cross-analysis on the threshold voltage change trend and the on-resistance change trend. If the change trends of the two are consistent and show a positive correlation, it is not necessary to calibrate the two monitoring modules; if the change trends of the two are inconsistent or show a negative correlation, it is necessary to calibrate the two monitoring modules and then re-monitor.

[0017] The beneficial effects of the present invention include:

[0018] In a first aspect, the present invention provides an on-line measurement system for aging characteristic parameters that does not affect the normal operation of power devices, solves the problem that device on-line operation and aging detection cannot be carried out simultaneously, can detect potential aging problems of SiC MOSFETs in advance, take preventive measures, and avoid system failures. In a second aspect, the present invention integrates two on-line real-time monitoring methods of body effect monitoring and gate drive, respectively conducts monitoring, and performs comparative analysis and cross-analysis of monitoring data and its trend data, improves the accuracy of monitoring and early warning, and solves the problem of false alarms caused by the monitoring error of only using one set of monitoring devices, and timely corrects and improves the accuracy of the monitoring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a schematic structural diagram of an on-line measurement system for SiC MOSFET aging parameters provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0021] Please refer to Figure 1 , in order to simultaneously achieve the normal operation of Sic MOSFET and on-line measurement of parameters and improve the monitoring accuracy of aging parameters, the present application provides an on-line measurement system for SiC MOSFET aging parameters. The aging parameters include threshold voltage and on-resistance. The on-line measurement system includes a body effect monitoring module, a gate drive monitoring module, and a mutual verification module. The body effect monitoring module is used to collect the relationship curve between the source-drain voltage and the gate voltage by applying a constant measurement current during the gate switching process of the SiC MOSFET, and extract the threshold voltage under the body effect. It is also used to calculate the on-resistance under the body effect by applying a constant measurement current to the source-drain of the SiC MOSFET and monitoring its on-voltage. The gate drive monitoring module is used to apply a pre-bias voltage and a scan voltage to the gate at intervals using a power measurement unit, and monitor the gate voltage when the drain current reaches a specified value, which is the threshold voltage under the gate drive. It is also used to evaluate the on-resistance under the gate drive by monitoring the change of gate charge during the switching process of the SiC MOSFET. The mutual verification module is used to respectively track, record, and plot the change trends of the threshold voltage under body effect monitoring and gate drive, and respectively track, record, and plot the change trends of the on-resistance under body effect monitoring and gate drive monitoring. If the two change trends are respectively consistent and the data is within the normal range, continuous normal monitoring is carried out. If the two change trends are respectively consistent but the data is abnormal, an aging warning of the SiC MOSFET is issued. If more than one of the two change trends is inconsistent, the two monitoring modules are calibrated and then re-monitored.

[0022] Specifically, in the practical application of SiC MOSFET devices, the reliability of the gate oxide layer is one of the key factors affecting the device lifetime. Due to the low barrier height of SiC material and the high trap density at the SiC / SiO 2 interface, SiC MOSFETs are more vulnerable to gate oxide layer aging. Therefore, in actual operation, it is of great significance to conduct on-line monitoring of the gate aging state of SiC MOSFETs, including: Timely fault diagnosis: Through on-line monitoring, signs of gate aging can be detected in real time, and measures can be taken in advance to avoid device failure; Improving system reliability: On-line monitoring can ensure the stable operation of power electronic systems and reduce sudden failures caused by device aging; Reducing maintenance costs: Avoiding economic losses caused by shutdown monitoring and reducing damage caused by device disassembly. And on-line monitoring of the aging parameters of SiC MOSFETs can provide the following values: Multi-parameter monitoring: By monitoring parameters such as threshold voltage (VTH), on-resistance (RDS(on)), gate leakage current (IGSS), etc., the health state of the device can be comprehensively evaluated; Temperature decoupling: Some monitoring methods (such as monitoring based on the bulk effect) are insensitive to temperature changes and can achieve accurate monitoring in a non-constant temperature environment; Fast response: On-line monitoring can be quickly completed when the device is in the off state without affecting the normal operation of the device; The technical implementation of on-line monitoring of aging parameters includes: a gate aging monitoring circuit, a conventional drive circuit, a monitoring drive circuit, a sampling circuit, and a logic operation circuit, which can perform aging monitoring when the device is off without affecting normal operation. Aging characteristic quantity: By monitoring characteristic quantities such as gate charging time, the aging state of the gate can be accurately evaluated. This method is insensitive to the change of junction temperature and is not affected by the working current and package aging. An integrated intelligent gate driver can monitor the gate voltage slope in real time, adjust the gate drive curve and bus voltage to compensate for changes caused by aging. On-line monitoring technology can be widely applied to various devices including SiC MOSFET devices, such as electric vehicles, converters, etc., which helps to reduce operation and maintenance costs, improve the reliability and service life of the devices. By on-line monitoring the aging parameters of SiC MOSFETs, real-time evaluation of the device health state can be achieved, potential faults can be predicted in advance, thus significantly improving the reliability and economy of power electronic systems.

[0023] To monitor the aging parameters in real-time online, body effect monitoring is a relatively good method. The body effect monitoring module includes: a control circuit, an oscilloscope, a voltage source, a constant current source, and a host computer; the control circuit is used to switch different measurement modes through a relay to achieve gate biasing and electrical parameter measurement; the oscilloscope is used to collect source-drain voltage-gate-source voltage waveform data and record the voltage changes during the switching process; the voltage source and the constant current source are used to provide the gate biasing voltage and the measurement current to measure the threshold voltage and the on-resistance; the host computer is used for data processing and analysis, processes the collected waveform data, and calculates and tracks the threshold voltage and the on-resistance.

[0024] Specifically, the structural model of the real-time online monitoring module for the gate aging of SiC MOSFET based on the body effect mainly includes the following key parts to achieve fast, accurate, and temperature-interference-free aging monitoring: Composition of the module structure: Control circuit: Switches different measurement modes through a relay to achieve gate biasing and electrical parameter measurement; Oscilloscope: Used to collect VSD-VGS waveform data and record the voltage changes during the switching process; Voltage source and constant current source: Provide the gate biasing voltage and the measurement current, and are used to measure VTH(body) and VTH; Host computer: Used for data processing and analysis, processes the collected waveform data, and calculates the change of VTH(body). Working modes of the measurement circuit: Gate biasing mode: The relay connects the voltage source to apply a biasing voltage to the gate, and at the same time the constant current source is short-circuited, and the device is in the accelerated aging stage; VTH(body) measurement mode: The relay connects the voltage source and the current source, the current source applies the measurement current ISD, the voltage source provides the gate switching pulse, and the oscilloscope collects the VSD-VGS waveform. VTH measurement mode: The relay connects the drain, and the current source applies the measurement current IDS to measure the traditional threshold voltage VTH. Measurement principle: Body effect principle: When the SiC MOSFET operates in the third quadrant, a positive voltage is applied to the source-drain, and the threshold voltage decreases (body effect). By monitoring the VSD-VGS curve during the switching process, VTH(body) can be obtained, thereby realizing gate aging monitoring. Features of the module: Fast measurement: The measurement is realized during the gate switching process, without changing the gate circuit topology, and the measurement time is short. Sensitive to aging: VTH(body) has a good correlation with both positive bias temperature instability (PBTI) and negative bias temperature instability (NBTI). The real-time online monitoring module for the gate aging of SiC MOSFET based on the body effect realizes fast, accurate, and temperature-interference-free aging monitoring by measuring VTH(body), providing a new technical means for the reliability research and health management of SiC MOSFET devices.

[0025] The specific measurement steps of the threshold voltage under the body effect include: Pre - bias processing: Apply a pre - bias voltage to the gate according to the pre - bias set time; Interval time: After the pre - bias is completed, according to a predetermined time interval; Apply measurement current: After the pre - bias is completed and a certain interval time is set, when the SiC MOSFET operates in the third quadrant, apply a constant source - drain current through a constant current source; Collect and plot the source - drain voltage - gate - source voltage curve: During the gate voltage switching process, collect and plot the relationship curve between the source - drain voltage and the gate voltage; Extract the threshold voltage: When the source voltage no longer changes with the gate voltage, the corresponding gate voltage is the threshold voltage under the body effect.

[0026] Specifically, the monitoring of the threshold voltage (VTH(body)) of SiC MOSFET based on the body effect is an emerging gate aging monitoring technology, which can quickly and accurately evaluate the aging state of the device in a non - constant temperature environment. The following are the specific monitoring methods and operation steps: Principle of body effect monitoring: The body effect refers to the phenomenon that when the SiC MOSFET operates in the third quadrant and a positive voltage is applied between the source and the drain, the threshold voltage decreases. In this state, the threshold voltage under the body effect (VTH(body)) has good sensitivity to gate aging (such as positive - bias temperature instability PBTI and negative - bias temperature instability NBTI). (1) The module includes a control circuit: used to switch different measurement modes. An oscilloscope and a voltage source: used to collect the VSD - VGS curve. A constant current source: used to apply the measurement current. (2) Measurement process: Pre - bias processing: Apply a pre - bias voltage (Vcon) to the gate, and the duration (tcon) is usually 1 - 100 ms. Interval time: After the pre - bias is completed, after a specified interval time (tfloat, usually less than 10 ms). Apply measurement current: When operating in the third quadrant, apply a constant source - drain current (such as 50 mA) through a constant current source. Collect the VSD - VGS curve: During the gate voltage switching process, collect the relationship curve between the source - drain voltage (VSD) and the gate voltage (VGS). Extract VTH(body): When VSD no longer changes with VGS, the corresponding VGS is VTH(body). Advantages of the monitoring method: Fast measurement: The measurement is completed during the gate switching process without changing the gate circuit topology. Sensitive to aging: VTH(body) has a good correlation with both PBTI and NBTI.

[0027] The specific measurement steps of the on - resistance under the body effect include: Calculate the on - resistance: Extract the source - drain voltage and the source - drain current, and calculate the ratio of the source - drain voltage to the source - drain current, which is the on - resistance under the body effect.

[0028] To improve the measurement accuracy of aging parameters, this solution also includes another set of measurement modules to measure together with the body effect module to improve the measurement accuracy. The gate drive monitoring module is a dual-channel drive chip integrated in the gate driver of the SiC MOSFET, and the dual-channel drive chip provides a drive current output that supports real-time variable drive strength.

[0029] The specific measurement steps for the threshold voltage under gate drive include: Gate pre-biasing: Use a gate pre-biasing circuit to pre-bias the device under test, and apply a specified gate pre-biasing voltage and gate pre-biasing time by a DC power supply with an ammeter; After the pre-biasing is completed, cut off the gate pre-biasing voltage and pass through a specified interval time; Gate voltage scanning: After the interval time ends, apply a gate scanning voltage by a variable DC voltage source with an ammeter according to the specified threshold voltage scanning direction, scanning range, and test time; At the same time, synchronously monitor the drain current; Read the threshold voltage: When the drain current monitored by the variable DC voltage source with an ammeter reaches the specified value, read the corresponding gate-source voltage, which is the threshold voltage under gate drive. The specific measurement steps for the on-resistance under gate drive include: Measure the drain-source voltage: While monitoring the drain current, measure the drain-source voltage; Calculate the on-resistance: Extract the drain-source voltage and the drain current, and calculate the ratio of the drain-source voltage to the drain current, which is the on-resistance under gate drive.

[0030] Specifically, the specific measurement steps for the threshold voltage (VTH) under gate drive (single voltage source scanning method)

[0031] According to the latest measurement standards and practices, the following are the specific steps for measuring the threshold voltage (VTH) of SiC MOSFET based on the single voltage source sweep method: Preparation of the measurement circuit Gate pre - bias circuit: Use the gate pre - bias circuit. SMU1 is a DC voltage source with an ammeter. Test circuit: Use a test circuit such as the single voltage source sweep method. SMU2 is a variable DC voltage source with an ammeter. Measurement steps include: Gate pre - bias: Use the gate pre - bias circuit to pre - bias the device under test. Apply a specified gate pre - bias voltage (Vcon) and gate pre - bias time (tcon) by SMU1. Usually, tcon can be taken as 1 - 100 ms. After the pre - bias is completed, cut off the gate pre - bias voltage, and after a specified interval time (tfloat), usually tfloat < 10 ms. Switch to the test circuit: After the interval time ends, switch the circuit to the single voltage source sweep method test circuit. Gate voltage sweep: Apply a gate sweep voltage by SMU2 according to the specified threshold voltage sweep direction, sweep range, and test time. At the same time, synchronously monitor the drain current (IDS). Read the threshold voltage: When the drain current monitored by SMU2 reaches the specified value, read the corresponding gate - source voltage (VGS), which is the threshold voltage (VTH). It should be noted that: Gate pre - bias voltage (Vcon) and time (tcon): Vcon can be selected as the maximum rated value of the gate - source voltage or slightly higher than the expected threshold voltage (such as 0.5 V higher). Interval time (tfloat): Usually less than 10 ms. Sweep step and time: The threshold voltage test time (tVT) should be as short as possible to meet the accuracy requirements. For example, when the sweep step is 0.1 V, tVT should be less than (10 ms × number of sweep points).

[0032] Through the above steps, the threshold voltage of SiC MOSFET can be accurately measured, which is applicable to scenarios such as aging monitoring, quality control, and reliability assessment. These methods comply with the latest test standards, ensuring the accuracy and repeatability of the measurement.

[0033] To solve the measurement errors or mistakes that occur in the monitoring system and improve the accuracy of aging parameter measurement, this solution also includes an interactive calibration module: The mutual calibration module can be integrated in the host computer. By extracting the threshold voltage and on - resistance data of the body effect monitoring module and the gate drive monitoring module, trend comparison analysis and cross - comparison analysis are carried out. Trend comparison analysis means separately analyzing the change trends of the threshold voltage and the on - resistance to judge the aging condition of the SiC MOSFET. Cross - comparison analysis means cross - analyzing the change trends of the threshold voltage and the on - resistance. If the change trends of the two are consistent and show a positive correlation, there is no need to calibrate the two monitoring modules; if the change trends of the two are inconsistent or show a negative correlation, the two monitoring modules need to be calibrated and then monitored again.

[0034] Specifically, in the aging monitoring of SiC MOSFETs, gate drive monitoring and body effect-based monitoring methods can be mutually verified to improve the accuracy and reliability of monitoring. The following is the combination of the two methods and their verification methods: Gate drive monitoring: Gate drive monitoring usually evaluates the aging state of SiC MOSFETs by measuring parameters such as threshold voltage (VTH), on-resistance (RDS,ON), Miller plateau voltage (VGP), etc. These parameters are highly sensitive to gate aging. Body effect-based monitoring: The body effect refers to the phenomenon that when the SiC MOSFET operates in the third quadrant and a positive voltage is applied between the source and drain, the threshold voltage decreases. The body effect-based monitoring method evaluates gate aging by measuring the threshold voltage under the body effect (VTH(body)). VTH(body) has good sensitivity to both positive bias temperature instability (PBTI) and negative bias temperature instability (NBTI), and has low temperature sensitivity (2.97 mV / ℃), making it suitable for non-constant temperature environments. Advantages of mutual verification Fast measurement: The body effect-based monitoring method can be quickly measured during the gate switching process without changing the gate circuit topology, and the measurement results are more stable. Multi-parameter fusion: By simultaneously measuring VTH(body) and VTH, the results of the two methods can be compared to further verify the aging state. In summary, the gate drive monitoring and the body effect-based monitoring methods can be mutually verified to improve the accuracy and reliability of SiC MOSFET aging monitoring. As a new monitoring parameter, VTH(body) has the characteristics of low temperature sensitivity, fast measurement, and good sensitivity to PBTI / NBTI, and can effectively complement the deficiencies of traditional monitoring methods.

[0035] For those skilled in the art, according to the technical solutions and concepts described above, various corresponding changes and deformations can be made, and all such changes and deformations should fall within the protection scope of the claims of the present invention.

[0036] It should be noted that: The above-described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The singular forms of "a", "the", and "its" used in the embodiments and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

Claims

1. A SiC MOSFET aging parameter online measurement system, characterized in that: The aging parameters include threshold voltage and on-resistance, and the online measurement system includes a body effect monitoring module, a gate drive monitoring module, and a mutual verification module; The body effect monitoring module is used to extract the threshold voltage under the body effect by applying a constant measurement current and collecting the relationship curve between the source-drain voltage and the gate voltage during the gate switching process of the SiC MOSFET; it is also used to calculate the on-resistance under the body effect by applying a constant measurement current to the source and drain of the SiC MOSFET and monitoring its on-voltage; The gate drive monitoring module is used to apply a pre-bias voltage and a scan voltage to the gate interval using a power measurement unit and to extract the gate voltage when the drain current reaches a specified value, which is the threshold voltage under gate drive; and is also used to evaluate the on-resistance under gate drive by monitoring the gate charge change of SiC MOSFET during the switching process; The mutual verification module is used to respectively track, record and draw the threshold voltage change trend under body effect monitoring and gate drive, and to respectively track, record and draw the on-resistance change trend under body effect monitoring and gate drive monitoring; If the two change trends are consistent and the data are within the normal range, continue normal monitoring; If the two change trends are consistent but the data is abnormal, an SiC MOSFET aging warning is issued; If at least one of the two changing trends is inconsistent, the two monitoring modules should be calibrated and then monitored again.

2. The SiC MOSFET aging parameter online measurement system according to claim 1, characterized in that: The body effect monitoring module includes: a control circuit, an oscilloscope, a voltage source and a constant current source, and a host computer; The control circuit is used to switch different measurement modes through relays to achieve gate bias and electrical parameter measurement; The oscilloscope is used to collect source-drain voltage-gate-source voltage waveform data and record voltage changes during the switching process; The voltage source and the constant current source are used to provide a gate bias voltage and a measurement current, and to measure a threshold voltage and an on-resistance; The host computer is used for data processing and analysis, processes the collected waveform data, and calculates and tracks and records the threshold voltage and on-resistance.

3. The SiC MOSFET aging parameter online measurement system according to claim 2, characterized in that: The specific steps of measuring the threshold voltage under the body effect include: Pre-bias processing: applying a pre-bias voltage to the gate according to the pre-bias setting time; Interval time: After pre-biasing is completed, according to the predetermined time interval; Applying the measurement current: After a certain interval of time after the pre-bias is completed, a constant source-drain current is applied through a constant current source when the SiC MOSFET operates in the third quadrant; Collect and draw the source-drain voltage-gate-source voltage curve: During the gate voltage switching process, collect and draw the relationship curve between the source-drain voltage and the gate voltage; Extracting threshold voltage: When the source voltage no longer changes with the gate voltage, the corresponding gate voltage is the threshold voltage under the body effect.

4. The SiC MOSFET aging parameter online measurement system according to claim 3, characterized in that: The specific measurement steps of on-resistance under body effect include: Calculate the on-resistance: extract the source-drain voltage and source-drain current, and calculate the ratio of the source-drain voltage and source-drain current to obtain the on-resistance under the body effect.

5. The SiC MOSFET aging parameter online measurement system according to claim 1, characterized in that: The gate drive monitoring module is a dual-channel drive chip integrated in the gate driver of the SiC MOSFET, and the dual-channel drive chip provides a drive current output supporting real-time variable drive strength.

6. The SiC MOSFET aging parameter online measurement system according to claim 5, characterized in that: The specific steps for measuring the threshold voltage under gate drive include: Gate pre-bias: The device under test is pre-biased using a gate pre-bias circuit, and a DC power supply with an ammeter applies a specified gate pre-bias voltage and gate pre-bias time; after the pre-bias is completed, the gate pre-bias voltage is cut off and a specified interval time passes; Gate voltage scan: After the interval time is over, a variable DC voltage source with an ammeter applies a gate scan voltage according to the specified threshold voltage scan direction, scan range and test time; and the drain current is monitored synchronously at the same time; Reading the threshold voltage: When the drain current monitored by the variable DC voltage source with an ammeter reaches the specified value, the corresponding gate-source voltage is read out, which is the threshold voltage under gate drive.

7. The SiC MOSFET aging parameter online measurement system according to claim 6, characterized in that: The specific steps for measuring the on-resistance under gate drive include: Measure drain-source voltage: Measure the drain-source voltage while monitoring the drain current; Calculate the on-resistance: extract the drain-source voltage and drain current, and calculate the ratio of the drain-source voltage and drain current to get the on-resistance under gate drive.

8. The SiC MOSFET aging parameter online measurement system according to claim 1, characterized in that: The mutual verification module can be integrated in a host computer, and perform trend comparison analysis and cross comparison analysis by extracting threshold voltage and on-resistance data of the body effect monitoring module and the gate drive monitoring module.

9. The SiC MOSFET aging parameter online measurement system according to claim 8, characterized in that: The trend comparison analysis refers to separately analyzing the threshold voltage change trend and the on-resistance change trend to determine the aging condition of the SiC MOSFET.

10. The SiC MOSFET aging parameter online measurement system according to claim 8, characterized in that: The cross-comparison analysis refers to a cross-analysis of the threshold voltage change trend and the on-resistance change trend. If the change trends of the two are consistent and positively correlated, it is not necessary to calibrate the two monitoring modules. If the changing trends of the two are inconsistent or negatively correlated, the two monitoring modules need to be calibrated and re-monitored.

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