SiC MOSFET aging parameter on-line measurement system

Abstract

The invention relates to the technical field of semiconductor device monitoring, and provides a SiC MOSFET aging parameter on-line measurement system, aging parameters comprise threshold voltage and on resistance, and the on-line measurement system comprises a bulk effect monitoring module, a gate drive monitoring module and a mutual verification module. According to the technical scheme provided by the invention, on the one hand, online real-time measurement of aging characteristic parameters which do not affect normal work of the power device is realized, the problem that online work and aging monitoring of the device cannot be carried out at the same time is solved, the potential aging problem of the SiC MOSFET can be found in advance, preventive measures can be taken, and system faults can be avoided; on the second aspect, two sets of on-line real-time monitoring methods of bulk effect and gate drive are integrated to carry out monitoring respectively, and comparative analysis and cross analysis of monitoring data and trend data thereof are carried out, so that the accuracy of monitoring and early warning is improved, and the problem of false alarm caused by monitoring errors of only one set of monitoring method is solved; and the accuracy of the monitoring scheme is improved through timely mutual verification.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device monitoring, and in particular to an online measurement system for SiC MOSFET aging parameters. Background Art

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

[0003] The aging problems of SiC MOSFET mainly involve the degradation of its gate oxide layer, bias temperature instability (BTI), package failure, and short-circuit tolerance. Current aging monitoring methods include offline and online methods. Offline monitoring usually needs to be performed after the device is shut down or disassembled, and the aging status of the device is evaluated through laboratory equipment or accelerated aging experiments. It is not suitable for monitoring devices in operation. Online monitoring refers to the use of specific monitoring circuits and methods to obtain the aging status of the device in real time when the SiC MOSFET is in normal operation or shutdown state, without shutting down or disassembling the device. However, the online monitoring method is easy to interfere with the normal operation of the device. However, due to the complexity of online monitoring of aging parameters such as threshold voltage and on-resistance, the accuracy of online monitoring is often not as good as offline monitoring.

[0004] In order to not affect the normal operation of power devices and to be able to monitor the aging of SiC MOSFET online so as to detect potential problems in advance and take preventive measures, it is necessary to develop a system that can monitor aging parameters in real time online without interfering with the normal operation of SiC MOSFET and has high accuracy in aging parameter monitoring. Summary of the invention

[0005] Based on the above situation, the main purpose of the present invention is to provide a measurement system based on an online measurement system for SiC MOSFET aging parameters, which can realize online real-time measurement of aging characteristic parameters, and can perform comparative analysis and cross-analysis of 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 the technical problem is as follows: The present invention provides an online measurement system for SiC MOSFET aging parameters, wherein 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 apply a constant measurement current during the gate switching process of SiC MOSFET, collect a relationship curve between source-drain voltage and gate voltage, and extract the threshold voltage under the body effect; it is also used to apply a constant measurement current to the source-drain of SiC MOSFET, and monitor its on-voltage to calculate the on-resistance under the body effect; the gate drive monitoring module is used to use a power measurement unit to apply a pre-bias voltage and a scanning voltage to the gate interval, and monitor that when the drain current reaches a specified value, the gate voltage is extracted as the threshold voltage under the gate drive; it is also used to monitor the SiC The on-resistance under gate drive is evaluated by the gate charge change of MOSFET during the switching process; the mutual verification module is used to track, record and plot the threshold voltage change trend under body effect monitoring and gate drive, and to track, record and plot 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, normal monitoring will continue; if the two change trends are consistent but the data are abnormal, an SiC MOSFET aging warning will be issued; if more than one of the two change trends is inconsistent, the two monitoring modules will be calibrated and re-monitored.

[0007] Furthermore, 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 drain-source voltage-gate-source voltage waveform data and record voltage changes during the switching process; the voltage source and constant current source are used to provide gate bias voltage and measurement current, measure threshold voltage and on-resistance; the host computer is used for data processing and analysis, processes the collected waveform data, calculates and tracks and records threshold voltage and on-resistance.

[0008] Furthermore, the specific measurement steps of 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 a measuring current: after the pre-bias is completed and a certain interval time is set, when the SiC MOSFET works in the third quadrant, a constant drain current is applied through a constant current source; collecting and drawing a drain-source voltage-gate-source voltage curve: during the gate voltage switching process, collecting and drawing a curve of the relationship 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.

[0009] Furthermore, the specific measurement steps of the on-resistance under the body effect include: calculating the on-resistance: extracting the drain-source voltage and the drain voltage, and calculating the ratio of the drain-source voltage to the drain voltage as the on-resistance under the body effect.

[0010] Furthermore, 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.

[0011] Furthermore, the specific measurement steps of the threshold voltage under gate drive include: gate pre-bias: using a gate pre-bias circuit to pre-bias the device under test, and applying a specified gate pre-bias voltage and gate pre-bias time by a DC power supply with an ammeter; after the pre-bias is completed, the gate pre-bias voltage is cut off and a specified interval time passes; gate voltage scanning: after the interval time ends, a variable DC voltage source with an ammeter applies a gate scanning voltage according to a specified threshold voltage scanning direction, scanning range and test time; and simultaneously monitors the drain current; reading the threshold voltage: when the drain current monitored by the variable DC voltage source with an ammeter reaches a specified value, the corresponding gate-source voltage is read out, which is the threshold voltage under gate drive.

[0012] Furthermore, the specific steps of measuring the on-resistance under gate drive include: measuring the drain-source voltage: measuring the drain-source voltage while monitoring the drain current; calculating the on-resistance: extracting the drain-source voltage and the drain voltage, and calculating the ratio of the drain-source voltage to the drain voltage, which is the on-resistance under gate drive.

[0013] Furthermore, the mutual verification module can be integrated in the host computer to perform trend comparison analysis and cross comparison analysis by extracting the threshold voltage and on-resistance data of the body effect monitoring module and the gate drive monitoring module.

[0014] Furthermore, 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.

[0015] Furthermore, cross-comparison analysis refers to 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 change trends of the two are inconsistent or negatively correlated, it is necessary to calibrate the two monitoring modules and then re-monitor.

[0016] The beneficial effects of the present invention include: In the first aspect, the present invention provides an online measurement system for aging characteristic parameters that does not affect the normal operation of power devices, which solves the problem that the online operation of devices and aging detection cannot be performed at the same time, and can detect potential aging problems of SiC MOSFET in advance, take preventive measures, and avoid system failures. In the second aspect, the present invention improves the accuracy of monitoring and early warning by integrating two sets of online real-time monitoring methods, body effect monitoring and gate drive, and performs comparative analysis and cross-analysis of monitoring data and their trend data, and solves the problem of false alarms caused by monitoring errors using only one set of monitoring devices, and timely correction improves the accuracy of the monitoring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of an online measurement system for SiC MOSFET aging parameters provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0019] Please refer to Figure 1 In order to simultaneously realize the normal operation and online measurement of parameters of Sic MOSFET and improve the monitoring accuracy of aging parameters, the present application provides an online measurement system for SiC MOSFET aging parameters, wherein 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 use a power measurement unit to apply a pre-bias voltage and a scanning voltage to the gate interval and monitor the drain current to reach a specified value, and extract the gate voltage as the threshold voltage under the gate drive; it is also used to monitor the SiC The on-resistance under gate drive is evaluated by the gate charge change of MOSFET during the switching process; the mutual verification module is used to track, record and plot the threshold voltage change trend under body effect monitoring and gate drive, and to track, record and plot 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, normal monitoring will continue; if the two change trends are consistent but the data are abnormal, an SiC MOSFET aging warning will be issued; if more than one of the two change trends is inconsistent, the two monitoring modules will be calibrated and re-monitored.

[0020] Specifically, in practical applications, the reliability of the gate oxide layer of SiC MOSFET devices is one of the key factors affecting the life of the device. Due to the low barrier height of SiC materials and the high trap density of the SiC / SiO2 interface, SiC MOSFET is more susceptible to gate oxide aging. Therefore, in actual operation, online monitoring of the gate aging status of SiC MOSFET is of great significance, including: timely fault diagnosis: through online monitoring, signs of gate aging can be found in real time, and measures can be taken in advance to avoid device failure; improve system reliability: online monitoring can ensure the stable operation of power electronic systems and reduce sudden failures caused by device aging; reduce maintenance costs: avoid economic losses caused by downtime monitoring, and reduce damage caused by disassembly of devices. Online monitoring of SiC MOSFET aging parameters can provide the following value: Multi-parameter monitoring: By monitoring parameters such as threshold voltage (VTH), on-resistance (RDS(on)), gate leakage current (IGSS), etc., the health status of the device can be comprehensively evaluated; Temperature decoupling: Some monitoring methods (such as monitoring based on body effect) are insensitive to temperature changes and can achieve accurate monitoring in non-constant temperature environments; Fast response: Online monitoring can be completed quickly when the device is turned off without affecting the normal operation of the device; The technical implementation of online monitoring of aging parameters includes: gate aging monitoring circuit conventional drive circuit, monitoring drive circuit, sampling circuit and logic operation circuit, which can perform aging monitoring when the device is turned 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 junction temperature changes and is not affected by operating current and package aging. The 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. Online monitoring technology can be widely used in various devices including SiC MOSFET devices, such as electric vehicles, converters, etc., which helps to reduce operating and maintenance costs and improve the reliability and service life of equipment. By online monitoring of SiC MOSFET aging parameters, real-time evaluation of device health status can be achieved, and potential failures can be warned in advance, thus significantly improving the reliability and economy of power electronic systems.

[0021] In order to monitor the aging parameters online in real time, body effect monitoring is a relatively effective method. 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 drain-source voltage-gate-source voltage waveform data and record voltage changes during the switching process; the voltage source and constant current source are used to provide gate bias voltage and measurement current, and measure threshold voltage and on-resistance; the host computer is used for data processing and analysis, processes the collected waveform data, calculates and tracks and records threshold voltage and on-resistance.

[0022] Specifically, the structural model of the real-time online monitoring module for SiC MOSFET gate aging based on body effect mainly includes the following key parts, which are used to realize fast, accurate and temperature-independent aging monitoring: Module structure composition: Control circuit: Switch different measurement modes through relays to realize gate bias and electrical parameter measurement; Oscilloscope: Used to collect VSD-VGS waveform data and record voltage changes during switching; Voltage source and constant current source: Provide gate bias voltage and measurement current for measuring VTH(body) and VTH; Host computer: Used for data processing and analysis, process the collected waveform data, and calculate the change of VTH(body). Measurement circuit working mode: Gate bias mode: The relay is connected to the voltage source to apply bias voltage to the gate, and the constant current source is short-circuited at the same time, and the device is in the accelerated aging stage; VTH(body) measurement mode: The relay is connected to 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 is connected to the drain, and the current source applies the measurement current IDS, which is used to measure the traditional threshold voltage VTH. Measurement principle: Body effect principle: When SiC MOSFET works in the third quadrant, positive voltage is applied to the source and drain, and the threshold voltage is reduced (body effect). By monitoring the VSD-VGS curve during the switching process, VTH(body) can be obtained, thereby realizing gate aging monitoring. Module features: 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 SiC MOSFET gate aging based on body effect realizes fast, accurate and temperature-independent aging monitoring by measuring VTH(body), providing a new technical means for reliability research and health management of SiC MOSFET devices.

[0023] The specific measurement steps of 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 the predetermined time interval; applying a measuring current: after the pre-bias is completed and a certain interval time is set, when the SiC MOSFET works in the third quadrant, a constant drain current is applied through a constant current source; collecting and drawing the drain-source voltage-gate-source voltage curve: during the gate voltage switching process, the relationship curve between the source-drain voltage and the gate voltage is collected and drawn; 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.

[0024] Specifically, the threshold voltage (VTH(body)) monitoring of SiC MOSFET based on body effect is an emerging gate aging monitoring technology that can quickly and accurately evaluate the aging status of the device in a non-constant temperature environment. The following are the specific monitoring methods and operation steps: Principle of body effect monitoring: Body effect refers to the phenomenon that when SiC MOSFET works in the third quadrant, a positive voltage is applied to the source and drain, resulting in a decrease in the threshold voltage. In this state, the threshold voltage (VTH(body)) under the body effect 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. Oscilloscope and voltage source: used to collect VSD-VGS curves. Constant current source: used to apply 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, a specified interval time (tfloat, usually less than 10 ms) passes. Apply measurement current: When operating in the third quadrant, a constant drain current (e.g. 50 mA) is applied through a constant current source. Collect VSD-VGS curve: During the gate voltage switching process, the relationship curve between the source drain voltage (VSD) and the gate voltage (VGS) is collected. 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.

[0025] The specific measurement steps of the on-resistance under the body effect include: calculating the on-resistance: extracting the drain-source voltage and the drain voltage, and calculating the ratio of the drain-source voltage to the drain voltage, which is the on-resistance under the body effect.

[0026] In order 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. The dual-channel drive chip provides a drive current output that supports real-time variable drive strength.

[0027] The specific measurement steps of the threshold voltage under gate drive include: gate pre-bias: the device under test is pre-biased by 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 scanning: after the interval time ends, a variable DC voltage source with an ammeter applies a gate scanning voltage according to the specified threshold voltage scanning direction, scanning 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 a specified value, the corresponding gate-source voltage is read out, which is the threshold voltage under gate drive. The specific measurement steps of the on-resistance under gate drive include: measuring the drain-source voltage: while monitoring the drain current, measuring the drain-source voltage; calculating the on-resistance: extracting the drain-source voltage and the drain voltage, and calculating the ratio of the drain-source voltage to the drain voltage is the on-resistance under gate drive.

[0028] Specifically, the specific measurement steps of the threshold voltage (VTH) under gate drive (single voltage source scanning method) 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: Measurement circuit preparation Gate pre-bias circuit: Use the gate pre-bias circuit, SMU1 is a DC voltage source with an ammeter. Test circuit: Use the single voltage source sweep method test circuit, SMU2 is a variable DC voltage source with an ammeter. The measurement steps include: Gate pre-bias: Use the gate pre-bias circuit to pre-bias the device under test. SMU1 applies the specified gate pre-bias voltage (Vcon) and gate pre-bias time (tcon). Usually, tcon can be 1-100ms. After the pre-bias is completed, the gate pre-bias voltage is cut off, and after the specified interval time (tfloat), usually tfloat < 10ms. Switch to the test circuit: After the interval time is over, switch the circuit to the single voltage source sweep method test circuit. Gate voltage sweep: SMU2 applies the gate sweep voltage according to the specified threshold voltage sweep direction, sweep range and test time. Simultaneously monitor the drain current (IDS). Reading 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). Note: 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. Scan step and time: The threshold voltage test time (tVT) should be as short as possible to meet the accuracy requirements. For example, when the scan step is 0.1 V, tVT should be less than (10 ms × number of scan points).

[0029] Through the above steps, the threshold voltage of SiC MOSFET can be accurately measured, which is suitable for scenarios such as aging monitoring, quality control and reliability assessment. These methods comply with the latest test standards and ensure the accuracy and repeatability of the measurement.

[0030] In order to solve the measurement errors or mistakes in the monitoring system and improve the accuracy of aging parameter measurement, this solution also includes an interactive verification module: the mutual verification module can be integrated in the host computer, and the threshold voltage and on-resistance data of the body effect monitoring module and the gate drive monitoring module are extracted for trend comparison analysis and cross comparison analysis. Trend comparison analysis refers to the separate analysis of the threshold voltage change trend and the on-resistance change trend to determine the aging of the SiC MOSFET. Cross comparison analysis refers to the 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 change trends of the two are inconsistent or negatively correlated, it is necessary to calibrate the two monitoring modules and re-monitor.

[0031] Specifically, in the aging monitoring of SiC MOSFET, gate drive monitoring and body effect-based monitoring methods can be mutually verified to improve the accuracy and reliability of monitoring. The following is a combination of the two methods and their verification methods: Gate drive monitoring: Gate drive monitoring usually evaluates the aging state of SiC MOSFET by measuring parameters such as threshold voltage (VTH), on-resistance (RDS,ON), and Miller platform voltage (VGP). These parameters are highly sensitive to gate aging. Monitoring based on body effect: Body effect refers to the phenomenon that when SiC MOSFET works in the third quadrant, a positive voltage is applied to the source and drain, resulting in a decrease in the threshold voltage. The monitoring method based on body effect evaluates gate aging by measuring the threshold voltage (VTH(body)) under body effect. 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 / ℃), which is suitable for non-constant temperature environments. Advantages of mutual verification Fast measurement: The monitoring method based on body effect can quickly measure during the gate switching process without changing the gate circuit topology, and the measurement results are more stable. Multi-parameter fusion: By measuring VTH(body) and VTH simultaneously, the results of the two methods can be compared to further verify the aging status. In summary, gate drive monitoring and body-effect-based monitoring methods can be cross-checked 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, which can effectively supplement the deficiencies of traditional monitoring methods.

[0032] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

[0033] It should be noted that the above-described embodiments are only some embodiments of the present invention, rather than all embodiments. The singular forms "a", "the" and "it" used in the embodiments and the appended claims are also intended to include 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 drain-source 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 drain current is applied through a constant current source when the SiC MOSFET operates in the third quadrant; Collect and draw the drain-source 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 drain-source voltage and the drain voltage, and calculate the ratio of the drain-source voltage to the drain voltage, which is 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, 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 the drain voltage, and calculate the ratio of the drain-source voltage to the drain voltage, which is 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 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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