Silicon carbide MOSFET gate-oxide health state real-time monitoring circuit and method

Abstract

The invention relates to the technical field of health management of silicon carbide MOSFET devices, in particular to a silicon carbide MOSFET gate oxide health state real-time monitoring circuit and method. The silicon carbide MOSFET gate-oxide health state real-time monitoring circuit comprises a differentiating circuit, a signal processing unit and a monitoring output unit, and synchronously outputs a first specific monitoring signal when a first voltage spike signal in a silicon carbide MOSFET turn-on stage is continuous; when the second voltage spike signal in the turn-off stage of the silicon carbide MOSFET is continuous, a second specific monitoring signal is synchronously output, and the duration time of the first specific monitoring signal and the duration time of the second specific monitoring signal are used for reflecting the gate-oxide health state of the silicon carbide MOSFET. According to the gate-oxide health state monitoring circuit, the resolution ratio can be effectively improved, only the gate signals are collected, the original working states of devices such as a driving resistor do not need to be changed, real-time online signal collection and low invasion of the monitoring circuit are kept, and the gate-oxide health state monitoring circuit and a driving circuit are easily integrated.

Description

Technical Field

[0001] The present invention relates to the technical field of health management of silicon carbide MOSFET devices, and in particular to a circuit and method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET. Background Art

[0002] Reliability issues for SiC MOSFETs can be primarily categorized as chip reliability and package reliability. Chip reliability includes gate oxide degradation and body diode degradation. SiC MOSFETs can provide the high power, high frequency, and high temperature operation required for next-generation power electronics applications. However, long-term operation at high frequencies, temperatures, and electric field stress can lead to gate oxide degradation, affecting device characteristics and potentially causing short-circuit failures, posing a risk to converter systems. Therefore, real-time monitoring of the gate oxide health of SiC MOSFETs is essential.

[0003] Current gate oxygen health monitoring technology still has the following problems: First, it is not easy to integrate. Existing monitoring solutions often require the collection of multiple signals and signal processing modules, which requires the design of additional circuits. The introduction of these components directly leads to an increase in circuit design area.

[0004] Second, it is difficult to measure online. The existing technical solutions require a long time period for online monitoring. It may be necessary to significantly reduce the operating frequency of the power device or even interrupt the operation of the device before the measurement can be implemented. It is not applicable to some scenarios that require continuous operation of the power device.

[0005] Third, the system is highly invasive. When some existing technical solutions collect multiple signals, the monitoring module needs to be directly connected to the gate, source and drain of the silicon carbide MOSFET, which will change the original working state of the device and increase the device power consumption and failure risk.

[0006] In view of the above problems, the existing technology is in urgent need of improvement. Summary of the Invention

[0007] The purpose of the present invention is to provide a real-time monitoring circuit and method for the gate oxygen health status of a silicon carbide MOSFET, so as to improve the integration and maintain the real-time online signal acquisition and low intrusiveness of the monitoring circuit.

[0008] To solve the above technical problems, the present invention provides a circuit and method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET.

[0009] The silicon carbide MOSFET gate oxygen health status real-time monitoring circuit of the present invention comprises: a differentiator circuit connected to the gate of the silicon carbide MOSFET, configured to detect a gate voltage signal during a turn-on phase of the silicon carbide MOSFET and convert the gate voltage signal into two voltage spike signals, or detect a gate voltage signal during a turn-off phase of the silicon carbide MOSFET and convert the gate voltage signal into two voltage spike signals; a signal processing unit connected to the output end of the differentiating circuit, connected to a reference voltage for comparison with the voltage spike signal, and configured to output a comparison signal reflecting the duration of the two voltage spike signals according to a comparison result; a monitoring output unit connected to the signal processing unit to receive the comparison signal and synchronously output a first specific monitoring signal when the first voltage spike signal in the turn-on phase of the silicon carbide MOSFET persists, where the duration of the first specific monitoring signal is the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; or, synchronously output a second specific monitoring signal when the second voltage spike signal in the turn-off phase of the silicon carbide MOSFET persists, where the duration of the second specific monitoring signal is the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET; The time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET and / or the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET are used to reflect the gate oxide health status of the silicon carbide MOSFET.

[0010] Further, the signal processing unit includes a first voltage comparator and a second voltage comparator both connected to the output terminal of the differential circuit; The differential circuit converts the gate signal into two positive voltage spike signals when the silicon carbide MOSFET is turned on, and converts the gate signal into two negative voltage spike signals when the silicon carbide MOSFET is turned off; The first voltage comparator is used to output two first high-level comparison signals corresponding to the two positive voltage spike signals when the silicon carbide MOSFET is turned on; the second voltage comparator is used to output two second high-level comparison signals corresponding to the two negative voltage spike signals when the silicon carbide MOSFET is turned off; The monitoring output unit synchronously outputs a first specific monitoring signal while the first first high-level comparison signal continues, and the duration of the first specific monitoring signal is the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; the monitoring output unit synchronously outputs a second specific monitoring signal while the second second high-level comparison signal continues, and the duration of the second specific monitoring signal is the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET.

[0011] Furthermore, the monitoring output unit includes a signal adjustment unit and a signal judgment unit; The signal conditioning unit includes a first D flip-flop and a second D flip-flop, wherein the input terminal D of the first D flip-flop is disconnected from the output terminal Q, the input terminal D of the second D flip-flop is disconnected from the output terminal Q, the clock signal input terminal of the first D flip-flop is connected to the first voltage comparator, and the clock signal input terminal of the second D flip-flop is connected to the second voltage comparator; The signal judgment unit includes a first AND gate, a second AND gate and an OR gate; The first AND gate is connected to the output terminal Q of the first D flip-flop and is also connected to the first voltage comparator; The second AND gate is disconnected from the output terminal Q of the second D flip-flop and is also connected to the second voltage comparator; Output terminals of the first AND gate and the second AND gate are both connected to the OR gate.

[0012] Furthermore, the inverting input terminal of the first voltage comparator is connected to a first reference voltage, and the positive input terminal is connected to the differentiating circuit; The positive input terminal of the second voltage comparator is connected to the second reference voltage, and the negative input terminal is connected to the differentiating circuit; The voltage of the positive voltage spike signal is greater than the first reference voltage and the second reference voltage; the voltage of the negative voltage spike signal is less than the first reference voltage and the second reference voltage.

[0013] Furthermore, it also includes a microprocessor, which is used to receive the first specific monitoring signal and the second specific monitoring signal and record the duration of the first specific monitoring signal and the second specific monitoring signal.

[0014] Furthermore, it also includes a programmable low-voltage source, which is used to provide power to the signal processing unit and the monitoring output unit.

[0015] The present invention further provides a method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET, which is implemented by a real-time monitoring circuit for the gate oxygen health status of a silicon carbide MOSFET according to any one of the above technical solutions, comprising: Obtain the gate voltage of the silicon carbide MOSFET; Detecting a gate voltage signal during a turn-on phase and / or a turn-off phase of a silicon carbide MOSFET and converting the gate voltage signal into two voltage spike signals; The duration of the first voltage spike signal in the turn-on phase of the silicon carbide MOSFET is recorded as the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; and / or, the duration of the second voltage spike signal in the turn-off phase of the silicon carbide MOSFET is recorded as the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET; the time difference between the turn-on moment and the start moment of the Miller platform in the turn-off phase of the silicon carbide MOSFET and / or the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET are used to reflect the gate oxide health status of the silicon carbide MOSFET.

[0016] Furthermore, the recording of the duration of the first voltage spike signal during the turn-on phase of the silicon carbide MOSFET includes: Comparing the voltage spike signal with a reference voltage, and outputting a comparison signal reflecting the duration of the two voltage spike signals according to the comparison result; receiving the comparison signal; The first voltage spike signal is determined according to the comparison signal, and a first specific monitoring signal is synchronously output when the first voltage spike signal continues. The duration of the first specific monitoring signal is the duration of the first voltage spike signal.

[0017] Furthermore, the recording of the duration of the second voltage spike signal during the turn-off phase of the silicon carbide MOSFET includes: Comparing the voltage spike signal with a reference voltage, and outputting a comparison signal reflecting the duration of the two voltage spike signals according to the comparison result; receiving the comparison signal; The second voltage spike signal is determined according to the comparison signal, and a second specific monitoring signal is synchronously output when the second voltage spike signal continues. The duration of the second specific monitoring signal is the duration of the second voltage spike signal.

[0018] Furthermore, the gate signal is converted into two positive voltage spike signals during the turn-on phase of the silicon carbide MOSFET; Recording the duration of the first positive voltage spike signal as the time difference between the turn-on moment of the silicon carbide MOSFET and the start moment of the Miller platform; Converting the gate signal into two negative voltage spike signals during the turn-off phase of the silicon carbide MOSFET; Recording the duration of the second negative voltage spike signal as the time difference between the end of the Miller platform in the turn-off phase of the silicon carbide MOSFET and the complete turn-off moment; The sum of the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the SiC MOSFET and the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the SiC MOSFET is used to reflect the gate oxide health status of the SiC MOSFET.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: The gate voltage signal of the silicon carbide MOSFET is directly obtained through a differential circuit and converted into a voltage spike signal. Only a single-point connection is required to complete the signal acquisition, avoiding the problem of traditional solutions requiring the connection of multiple electrodes, and significantly reducing the system intrusion. The signal processing unit uses a comparator structure to detect the duration of the spike signal. The circuit structure is simple and easy to integrate. The monitoring output unit realizes real-time extraction of time parameters by synchronously outputting the monitoring signal, and online measurement can be completed without interrupting the operation of the device. The entire solution can effectively improve the resolution through the coordinated work of the three functional units. It only needs to collect a single-point signal of the gate to extract the key time parameters reflecting the health status of the gate oxide. There is no need to change the original working state of the device such as the driving resistor. While reducing the intrusion, it achieves high integration and online monitoring capabilities, maintains the real-time online signal acquisition and low intrusion of the monitoring circuit, and is easy to integrate the silicon carbide MOSFET gate oxide health status real-time monitoring circuit of the present application with the driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of an embodiment of a real-time monitoring circuit for the gate oxygen health status of a silicon carbide MOSFET according to the present invention; Figure 2 for Figure 1 Timing diagram of the real-time monitoring circuit for the gate oxygen health status of silicon carbide MOSFET; Figure 3 for Figure 1 The real-time monitoring circuit for the health status of silicon carbide MOSFET gate oxides sends signals from each module when the silicon carbide MOSFET is turned on; Figure 4 for Figure 1 The signal of each module of the real-time monitoring circuit of the gate oxygen health status of the silicon carbide MOSFET during the shutdown phase of the silicon carbide MOSFET; Figure 5 Schematic diagram of the relationship between the gate oxide health of silicon carbide MOSFET and monitoring parameters under accelerated gate oxide aging experiment. DETAILED DESCRIPTION

[0021] The following will describe the circuit and method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET of the present invention in conjunction with a schematic diagram, which shows a preferred embodiment of the present invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation of the present invention. Based on the inspiration of this specification, those skilled in the art can form new technical solutions by cross-combining different implementation methods without generating technical contradictions, and such variations should be deemed to fall within the scope of protection of this patent.

[0022] The serial numbers assigned to components herein, such as "first," "second," etc., are used solely to distinguish the objects being described and do not convey any sequential or technical meaning. References to "connection" and "coupling" herein, unless otherwise specified, include both direct and indirect connections (couplings). In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like, indicating positions or relationships, are based on those shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the device or element referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention.

[0023] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0024] In this application, unless otherwise specified or limited, the term "connection" should be understood broadly. For example, "connection" can refer to fixed connection, detachable connection, or integration; it can refer to direct connection or indirect connection through an intermediate medium. In addition, the term "electrical connection" can refer to direct electrical connection or indirect electrical connection through an intermediate medium.

[0025] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are greatly simplified and not to exact scale, and are provided solely for the purpose of assisting in the description of the embodiments of the present invention.

[0026] The inventors have found that the formation principle of the Miller platform is due to the voltage stagnation phenomenon caused by the Miller capacitance during the switching process of the MOSFET (metal-oxide semiconductor field-effect transistor). Specifically, in the turn-on phase, when the gate voltage V GS After rising to the Miller platform voltage, the drain-source voltage V DS Starts to decrease, the gate-drain parasitic capacitance C GD Absorbs driving current instantaneously, causing gate voltage V GS It remains almost unchanged for a period of time (Miller plateau period); in the off stage, the drain-source voltage V DS Gate-drain parasitic capacitance C during rising GD Discharge also produces a Miller platform.

[0027] The inventors further discovered that as the gate oxide layer of the SiC MOSFET ages, affected by the device's own parameters, the time difference between the turn-on moment and the start of the Miller plateau (recorded as T1) during the SiC MOSFET's turn-on phase, and the time difference between the end of the Miller plateau and the time of complete shutdown (recorded as T2) during the turn-off phase, both increase. To reduce system intrusion, the inventors proposed a new approach to monitoring the health of the SiC MOSFET's gate oxide layer: by monitoring the duration of the voltage change of the SiC MOSFET's gate signal at the turn-on or turn-off moments, the time difference between the turn-on moment and the start of the Miller plateau during the turn-off phase, or the time difference between the end of the Miller plateau and the time of complete shutdown during the turn-off phase, is recorded to reflect the gate oxide health of the SiC MOSFET.

[0028] Based on this idea, the present invention proposes a real-time monitoring circuit and method for the gate oxygen health status of a silicon carbide MOSFET.

[0029] The following is attached with the instruction manual Figure 1 To the attached Figure 5 , the real-time monitoring circuit and method of the gate oxygen health status of silicon carbide MOSFET of the present invention are introduced.

[0030] In some embodiments, the silicon carbide MOSFET gate oxygen health status real-time monitoring circuit includes a differential circuit, a signal processing unit and a monitoring output unit.

[0031] The differential circuit is connected to the gate of the SiC MOSFET and is configured to detect the gate voltage signal during the SiC MOSFET's turn-on phase and convert the gate voltage signal into two voltage spikes, or detect the gate voltage signal during the SiC MOSFET's turn-off phase and convert the gate voltage signal into two voltage spikes. The differential circuit can be implemented using an RC differential network, and the differential time constant must be selected to ensure accurate extraction of the gate voltage change rate.

[0032] The signal processing unit is connected to the output end of the differential circuit, is connected to a reference voltage for comparison with the voltage spike signal, and is used to output a comparison signal reflecting the duration of the two voltage spike signals according to a comparison result.

[0033] The monitoring output unit is connected to the signal processing unit to receive the comparison signal, and synchronously outputs a first specific monitoring signal when the first voltage spike signal in the turn-on phase of the silicon carbide MOSFET continues, and the duration of the first specific monitoring signal is the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; or, synchronously outputs a second specific monitoring signal when the second voltage spike signal in the turn-off phase of the silicon carbide MOSFET continues, and the duration of the second specific monitoring signal is the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET.

[0034] The time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET and / or the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET are used to reflect the gate oxide health status of the silicon carbide MOSFET.

[0035] The gate voltage signal of the silicon carbide MOSFET is directly obtained through a differential circuit and converted into a voltage spike signal. Only a single-point connection is required to complete the signal acquisition, avoiding the problem of traditional solutions requiring the connection of multiple electrodes, and significantly reducing the system intrusion. The signal processing unit uses a comparator structure to detect the duration of the spike signal. The circuit structure is simple and easy to integrate. The monitoring output unit realizes real-time extraction of time parameters by synchronously outputting the monitoring signal, and online measurement can be completed without interrupting the operation of the device. The entire solution can effectively improve the resolution through the coordinated work of the three functional units. It only needs to collect a single-point signal of the gate to extract the key time parameters reflecting the health status of the gate oxide. There is no need to change the original working state of the device such as the driving resistor. While reducing the intrusion, it achieves high integration and online monitoring capabilities, maintains the real-time online signal acquisition and low intrusion of the monitoring circuit, and is easy to integrate the silicon carbide MOSFET gate oxide health status real-time monitoring circuit of the present application with the driving circuit. In some embodiments, the present invention can reflect the gate oxygen health status of the silicon carbide MOSFET by the sum of the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET and the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET, that is, the sum of T1+T2. Compared with reflecting only through T1 or only through T2, the aging signal can be amplified and the sensitivity is greatly improved. In other embodiments, for the purpose of simplifying the circuit, the gate oxygen health status of the silicon carbide MOSFET can also be reflected only through T1 or only through T2.

[0036] Next, the real-time monitoring circuit for the gate oxygen health status of a silicon carbide MOSFET of the present invention is described by taking the sum of T1+T2 to reflect the gate oxygen health status of the silicon carbide MOSFET as an example.

[0037] In some embodiments, such as Figure 1As shown, the signal processing unit includes a first voltage comparator U1 and a second voltage comparator U2, both connected to the output terminal of the differential circuit. The differential circuit converts the gate signal into two positive voltage spike signals during the SiC MOSFET's turn-on phase and into two negative voltage spike signals during the SiC MOSFET's turn-off phase. The first voltage comparator U1 is configured to output two first high-level comparison signals corresponding to the two positive voltage spike signals during the SiC MOSFET's turn-on phase; the second voltage comparator U2 is configured to output two second high-level comparison signals corresponding to the two negative voltage spike signals during the SiC MOSFET's turn-off phase. The monitoring output unit synchronously outputs a first specific monitoring signal while the first first high-level comparison signal persists. The duration of the first specific monitoring signal is the time difference between the SiC MOSFET's turn-on phase and the start of the Miller plateau. The monitoring output unit synchronously outputs a second specific monitoring signal while the second second high-level comparison signal persists. The duration of the second specific monitoring signal is the time difference between the end of the Miller plateau and the complete turn-off phase of the SiC MOSFET.

[0038] Specifically, the first voltage comparator U1 and the second voltage comparator U2 can be implemented by operational amplifiers with different threshold voltage settings, wherein the positive input terminal of the first voltage comparator U1 is connected to the output of the differential circuit, and the negative input terminal is connected to the first reference voltage V REF1 The reverse input terminal of the second voltage comparator U2 is connected to the output of the differential circuit, and the positive input terminal is connected to the second reference voltage V REF2 The voltage of the positive voltage spike signal is greater than the first reference voltage V REF1 and the second reference voltage V REF2 ; The voltage of the negative voltage spike signal is less than the first reference voltage V REF1 and the second reference voltage V REF2 Among them, the first reference voltage V REF1 and the second reference voltage V REF2 This can be achieved using a programmable reference voltage source, whose output value can be adjusted to set different reference voltage thresholds. A differential circuit, such as an RC differential circuit or an operational amplifier, can be used to extract the rate of change of the gate voltage signal. This allows for accurate differentiation of signals of opposite polarity generated during the different operating phases of the SiC MOSFET.

[0039] As a preferred embodiment, the first reference voltage V REF1 Set slightly above zero potential to identify positive voltage spikes; the second reference voltage V REF2The voltage is set slightly below zero to identify negative voltage spikes. The differential circuit can be constructed using an RC differential network, with its time constant optimized based on the switching frequency of the SiC MOSFET. The monitoring output unit can achieve signal synchronization via a D-type flip-flop. The first D-type flip-flop, U3, is triggered by the first voltage comparison signal, while the second D-type flip-flop, U4, is triggered by the second voltage comparison signal. This ensures strict synchronization between the monitoring signal and the spike signal.

[0040] By providing independent first and second voltage comparators U1 and U2, respectively processing the positive voltage spike signal during the turn-on phase and the negative voltage spike signal during the turn-off phase, signal polarity confusion is effectively avoided. The monitoring output unit uses a synchronous output mechanism to precisely capture the duration of the first positive voltage spike signal and the second negative voltage spike signal, thereby accurately reflecting the gate oxide health status.

[0041] Furthermore, in some embodiments, the monitoring output unit includes a signal conditioning unit and a signal determination unit. The signal conditioning unit includes a first D flip-flop U3 and a second D flip-flop U4. The input terminal D of the first D flip-flop U3 is disconnected from the output terminal Q, and the input terminal D of the second D flip-flop U4 is disconnected from the output terminal Q. The clock signal input terminal CLK of the first D flip-flop U3 is connected to the first voltage comparator U1, and the clock signal input terminal CLK of the second D flip-flop U4 is connected to the second voltage comparator U2. The signal determination unit includes a first AND gate AND1, a second AND gate AND2, and an OR gate OR. The first AND gate AND1 is connected to the output terminal Q of the first D flip-flop U3 and is also connected to the first voltage comparator U1. The second AND gate AND2 is disconnected from the output terminal Q of the second D flip-flop U4 and is also connected to the second voltage comparator U2. The output terminals of the first and second AND gates AND1 and AND2 are both connected to the OR gate OR.

[0042] Specifically, the first D flip-flop U3 and the second D flip-flop U4 are both rising-edge-triggered D flip-flops, with their clock signal inputs receiving pulse signals from the first voltage comparator U1 and the second voltage comparator U2, respectively. One input of the first AND gate AND1 is connected to the Q output of the first D flip-flop U3, and the other input is directly connected to the output of the first voltage comparator U1. One input of the second AND gate AND2 is connected to the Q non-output of the second D flip-flop U4, and the other input is directly connected to the output of the second voltage comparator U2. The OR gate utilizes a two-input OR gate, with its inputs connected to the outputs of the first and second AND gates AND1 and AND2, respectively.

[0043] In this embodiment, signal synchronization processing is achieved through digital logic circuits to avoid timing errors caused by analog circuits. By disconnecting the input terminal D and the output terminal Q of the first D flip-flop U3 and the input terminal D and the output terminal Q of the second D flip-flop U4, the signal conditioning unit forms a frequency division circuit, which converts the pulse signal output by the voltage comparator into a square wave signal with a constant duty cycle, ensuring that the monitoring signal V OUT The time measurement benchmark is stable. The first D flip-flop U3 divides the high-level comparison signal in the on-phase by two, and the second D flip-flop U4 divides the high-level comparison signal in the off-phase by two. The signal judgment unit implements signal screening through a combination of logic gates: the first AND gate AND1 performs a logical AND operation on the divided on-signal and the original comparison signal to accurately capture the first positive voltage spike; the second AND gate AND2 performs a logical AND operation on the divided off-signal and the original comparison signal to accurately capture the second negative voltage spike. The OR gate combines the judgment results of the two working states and outputs a unified monitoring signal V OUT This eliminates jitter interference in the comparison signal, ensuring an accurate starting point for time measurement. AND gate logic accurately filters spike signals, retaining only the duration information of the first positive voltage spike and the second negative voltage spike. An OR gate implements a unified output interface for dual-mode signals. This embodiment performs signal synchronization and logic judgment at the hardware level, eliminating the need for software intervention and meeting the real-time requirements of high-frequency switching scenarios.

[0044] Furthermore, in some embodiments, the silicon carbide MOSFET gate oxygen health status real-time monitoring circuit further includes a microprocessor MCU, the microprocessor is used to receive the output monitoring signal and record the monitoring signal V OUT duration.

[0045] Specifically, the microcontroller (MCU) receives the digital signal from the monitoring output unit and uses an internal timer module to accurately record the duration of the signal's high level. The timer can be configured in input capture mode to measure pulse width by capturing the signal's edge-triggered timestamp.

[0046] The monitoring process is automated by the introduction of a microprocessor. The pulse signal generated by the monitoring output unit is acquired in real time by the microprocessor, which uses its high-precision timing function to record the pulse width, which directly corresponds to the critical timing parameters of the SiC MOSFET. Compared to manual oscilloscope measurements, this eliminates human reading errors and improves measurement accuracy to the nanosecond level. The microprocessor continuously records the time data of multiple switching cycles, improving measurement reliability through statistical analysis. The automatic data storage function avoids omissions or errors that may occur due to manual recording, providing complete data support for long-term aging trend analysis.

[0047] Furthermore, in some of the embodiments, the silicon carbide MOSFET gate oxygen health status real-time monitoring circuit also includes a programmable low-voltage source, and the programmable low-voltage source is used to provide power to the signal processing unit and the monitoring output unit.

[0048] Specifically, a programmable low-voltage power supply refers to a DC power supply module whose output voltage can be adjusted using digital or analog signals. Specific implementations include, but are not limited to, using a digital potentiometer combined with a reference voltage source, or using a PWM signal to control the output voltage of a switching power supply.

[0049] The programmable power supply design enables dynamic adjustment of the supply voltage, providing precise voltage values ​​based on the actual operating requirements of the signal processing unit and monitoring output unit. When the monitoring circuit is in different operating modes, such as when the silicon carbide MOSFET is switching at high frequencies, the supply voltage can be increased to ensure the responsiveness of the signal processing unit; in standby mode, the voltage can be reduced to minimize power consumption.

[0050] The following combination Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 , the working process of one embodiment of the real-time monitoring circuit for the gate oxygen health status of the silicon carbide MOSFET is described.

[0051] When the silicon carbide MOSFET device is in the off state, the output voltage V R The voltage at the positive input terminal of the first voltage comparator U1 and the voltage at the negative input terminal of the second voltage comparator U2 are also 0V.

[0052] Therefore, the voltage V at the positive input of the first voltage comparator U1 is R is less than the first reference voltage V REF1 , the output of the first voltage comparator U1 is low level, so the output of the first AND gate AND1 is low level. The second reference voltage V REF2 Less than the voltage V at the inverting input R , the second voltage comparator U2 outputs a low level, so the second AND gate AND2 outputs a low level, and finally the monitoring signal V output by the OR gate OR OUT is low level.

[0053] When the PWM conduction signal is input to the silicon carbide MOSFET device through the driving circuit, that is, when an 18V driving signal is applied to the gate, the gate voltage V GSIt starts to rise from 0V or negative voltage. Due to the characteristics of the Miller platform, the gate voltage remains almost unchanged during the Miller platform. The differential circuit is only sensitive to the part with fast voltage changes. At this time, the differential circuit outputs two positive voltage spike signals V R , the second reference voltage V REF2 will always be less than the positive voltage spike V at the inverting input R , so the output voltage V U2 is low level, the second AND gate AND2 will always maintain a low level.

[0054] The positive input voltage V R Greater than the first reference voltage V REF1 , the first voltage comparator U1 outputs a voltage V U1 Since the first D flip-flop U3 is rising edge triggered and its input terminal D is disconnected from its output terminal Q, the output terminal Q of the first D flip-flop U3 is low in the initial state and Q is not high, so the input terminal is also high.

[0055] The output of the first voltage comparator U1 is connected to the clock signal input terminal CLK of the first D flip-flop U3. When the first high-level comparison signal arrives, the first D flip-flop U3 is triggered by the rising edge of the first high-level comparison signal. At this time, the output terminal Q of the first D flip-flop U3 becomes high, and Q does not become low, so the input terminal D also becomes low. At this time, both input terminals of the first AND gate AND1 are high, and the first AND gate AND1 outputs a high level. Therefore, the monitoring signal V output by the OR gate OR OUT is high level, serving as the first specific monitoring signal.

[0056] When the first high-level comparison signal ends, one of the input terminals of the first AND gate AND1 becomes low level, so the output of the first AND gate AND1 is low level, and the monitoring signal output by the OR gate OR is also low level.

[0057] When the second first high level comparison signal arrives, the first D flip-flop U3 is triggered again by the rising edge of the voltage signal. At this time, the output terminal Q becomes low level, so the output terminal of the first AND gate AND1 remains at a low level.

[0058] At this time, the time during which the monitoring signal output by the OR gate remains at a high level is the time difference T1 between the turn-on moment of the silicon carbide MOSFET and the start of the Miller platform.

[0059] When a turn-off signal is applied to the SiC MOSFET device, that is, 0V or negative voltage is applied to the gate, the gate voltage V GSIt starts to decrease from 18V. Due to the characteristics of the Miller platform, the gate voltage remains almost unchanged during the Miller platform. The differential circuit is only sensitive to the part with fast voltage changes. At this time, the differential circuit outputs two negative voltage spike signals V R , the positive input voltage of the first voltage comparator U1 is V R is always less than the first reference voltage V at the inverting input terminal. REF1 , output voltage V U1 is low level, and the output of the first AND gate AND1 will remain low level.

[0060] The second reference voltage V REF2 Greater than the reverse input voltage V R , the second voltage comparator output voltage V U2 These are the two second high level comparison signals.

[0061] Since the second D flip-flop U4 is rising edge triggered and its input terminal D is disconnected from its output terminal Q, the output terminal Q of the D flip-flop is low in the initial state and Q is not high, so the input terminal is also high.

[0062] The output of the second voltage comparator U2 is connected to the clock signal input terminal CLK of the second D flip-flop U4. When the first second high-level comparison signal arrives, the second D flip-flop U4 is triggered by the rising edge of the second high-level comparison signal. At this time, the output terminal Q of the second D flip-flop U4 becomes high, and Q not becomes low, so the input terminal D also becomes low. The Q not of the second D flip-flop U4 is connected to one of the input terminals of the second AND gate AND2. At this time, one of the two input terminals of the second AND gate AND2 is high and the other is low, so the second AND gate AND2 remains at a low level. At this time, the monitoring signal V output by the OR gate OR OUT Also keep it low.

[0063] When the second high level comparison signal arrives, the second D flip-flop U4 is triggered by the rising edge of the second high level comparison signal again. At this time, the output terminal Q of the second D flip-flop U4 becomes low level, and Q does not become high level, so the input terminal D also becomes high level. At this time, both input terminals of the second AND gate AND2 are high level, so the second AND gate AND2 changes from low level to high level. At this time, the monitoring signal V output by the OR gate OR OUT It also changes from low level to high level, serving as the second specific monitoring signal.

[0064] When the second high-level comparison signal ends, that is, the output of the second voltage comparator U2 becomes low, the inputs of the second AND gate AND2 are one low and one high, and the output of the second AND gate AND2 changes from high to low. At this time, the monitoring signal output by the OR gate OR also changes from high to low.

[0065] At this time, the time during which the monitoring signal output by the OR gate remains at a high level is the time difference T2 between the end of the Miller platform in the turn-off phase of the silicon carbide MOSFET and the complete turn-off moment.

[0066] Both T1 and T2 increase with the degradation of the gate oxide of the SiC MOSFET. After T1 and T2 are processed by the MCU, the time parameter of the sum of T1+T2 can be obtained. Compared with reflecting only through T1 or only through T2, it can amplify the aging signal and greatly improve the sensitivity.

[0067] The present invention also provides a method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET.

[0068] In some embodiments, the method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET includes: Obtain the gate voltage of the silicon carbide MOSFET; Detecting a gate voltage signal during a turn-on phase and / or a turn-off phase of a silicon carbide MOSFET and converting the gate voltage signal into two voltage spike signals; The duration of the first voltage spike signal in the turn-on phase of the silicon carbide MOSFET is recorded as the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; and / or, the duration of the second voltage spike signal in the turn-off phase of the silicon carbide MOSFET is recorded as the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET; the time difference between the turn-on moment and the start moment of the Miller platform in the turn-off phase of the silicon carbide MOSFET and / or the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET are used to reflect the gate oxide health status of the silicon carbide MOSFET.

[0069] Specifically, the gate voltage can be obtained by directly connecting the gate pin. The voltage spike signal can be transformed by a differential circuit, where the time constant of the differential circuit needs to be optimized according to the switching frequency of the SiC MOSFET.

[0070] By acquiring a single-point gate signal and utilizing the inherent gate voltage variation characteristics during the switching process, time parameters directly related to gate oxide health are extracted. Two parameters, the time from the start of the Miller platform during the turn-on phase and the time from the end of the Miller platform to complete shutdown during the turn-off phase, are sensitive indicators of changes in the charge trapping state of the gate oxide layer. Compared to existing technologies, this method only requires the acquisition of a single-point gate signal, making the system less invasive. Real-time signal processing enables true online monitoring without interrupting device operation. The monitored parameters have a clear physical correlation with gate oxide health, enabling accurate assessment of gate oxide health.

[0071] In some embodiments, the method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET may be implemented by a real-time monitoring circuit for the gate oxygen health status of a silicon carbide MOSFET according to any one of the above technical solutions.

[0072] In some embodiments, in order to record the duration of the first voltage spike signal during the turn-on phase of the silicon carbide MOSFET, the method includes: Comparing the voltage spike signal with a reference voltage, and outputting a comparison signal reflecting the duration of the two voltage spike signals according to the comparison result; receiving the comparison signal; The first voltage spike signal is determined according to the comparison signal, and a first specific monitoring signal is synchronously output when the first voltage spike signal continues. The duration of the first specific monitoring signal is the duration of the first voltage spike signal.

[0073] The voltage comparison process can be implemented by a voltage comparator, and the voltage comparator is connected to a reference voltage.

[0074] In some embodiments, in order to record the duration of the second voltage spike signal during the turn-off phase of the silicon carbide MOSFET, the method includes: Comparing the voltage spike signal with a reference voltage, and outputting a comparison signal reflecting the duration of the two voltage spike signals according to the comparison result; receiving the comparison signal; The second voltage spike signal is determined according to the comparison signal, and a second specific monitoring signal is synchronously output when the second voltage spike signal continues. The duration of the second specific monitoring signal is the duration of the second voltage spike signal.

[0075] The voltage comparison process can be implemented by a voltage comparator, and the voltage comparator is connected to a reference voltage.

[0076] In some embodiments, the gate oxide health status of the SiC MOSFET is reflected by the sum of the time difference between the turn-on moment and the start moment of the Miller plateau during the turn-off phase of the SiC MOSFET and the time difference between the end moment of the Miller plateau and the complete turn-off moment during the turn-off phase of the SiC MOSFET, that is, the sum of T1+T2. Specifically: Converting the gate signal into two positive voltage spike signals during the turn-on phase of the silicon carbide MOSFET; Recording the duration of the first positive voltage spike signal as the time difference between the turn-on moment of the silicon carbide MOSFET and the start moment of the Miller platform; Converting the gate signal into two negative voltage spike signals during the turn-off phase of the silicon carbide MOSFET; Recording the duration of the second negative voltage spike signal as the time difference between the end of the Miller platform in the turn-off phase of the silicon carbide MOSFET and the complete turn-off moment; The sum of the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the SiC MOSFET and the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the SiC MOSFET is used to reflect the gate oxide health status of the SiC MOSFET.

[0077] Reflecting the gate oxide health status of the silicon carbide MOSFET through the sum of T1+T2 can amplify the aging signal and greatly improve the sensitivity compared to reflecting it only through T1 or only through T2.

[0078] Furthermore, in some embodiments, a differential circuit is used to detect a gate voltage signal during the turn-on and / or turn-off phases of a silicon carbide MOSFET and convert the gate voltage signal into two voltage spike signals. The differential circuit can be implemented using an RC differential network, and the differential time constant must be selected to ensure accurate extraction of the gate voltage change rate.

[0079] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A real-time monitoring circuit for the gate oxygen health status of a silicon carbide MOSFET, characterized in that: include: a differentiator circuit connected to the gate of the silicon carbide MOSFET, configured to detect a gate voltage signal during a turn-on phase of the silicon carbide MOSFET and convert the gate voltage signal into two voltage spike signals, or detect a gate voltage signal during a turn-off phase of the silicon carbide MOSFET and convert the gate voltage signal into two voltage spike signals; a signal processing unit connected to the output end of the differentiating circuit, connected to a reference voltage for comparison with the voltage spike signal, and configured to output a comparison signal reflecting the duration of the two voltage spike signals according to a comparison result; a monitoring output unit connected to the signal processing unit to receive the comparison signal and synchronously output a first specific monitoring signal when the first voltage spike signal in the turn-on phase of the silicon carbide MOSFET persists, where the duration of the first specific monitoring signal is the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; or, synchronously output a second specific monitoring signal when the second voltage spike signal in the turn-off phase of the silicon carbide MOSFET persists, where the duration of the second specific monitoring signal is the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET; The time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET and / or the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET are used to reflect the gate oxide health status of the silicon carbide MOSFET.

2. The silicon carbide MOSFET gate oxygen health status real-time monitoring circuit according to claim 1, characterized in that: The signal processing unit includes a first voltage comparator and a second voltage comparator both connected to the output terminal of the differentiating circuit; The differential circuit converts the gate signal into two positive voltage spike signals when the silicon carbide MOSFET is turned on, and converts the gate signal into two negative voltage spike signals when the silicon carbide MOSFET is turned off; The first voltage comparator is used to output two first high-level comparison signals corresponding to the two positive voltage spike signals when the silicon carbide MOSFET is turned on; the second voltage comparator is used to output two second high-level comparison signals corresponding to the two negative voltage spike signals when the silicon carbide MOSFET is turned off; The monitoring output unit synchronously outputs a first specific monitoring signal while the first first high-level comparison signal continues, and the duration of the first specific monitoring signal is the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; the monitoring output unit synchronously outputs a second specific monitoring signal while the second second high-level comparison signal continues, and the duration of the second specific monitoring signal is the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET.

3. The silicon carbide MOSFET gate oxygen health status real-time monitoring circuit according to claim 2, characterized in that: The monitoring output unit includes a signal adjustment unit and a signal judgment unit; The signal conditioning unit includes a first D flip-flop and a second D flip-flop, wherein the input terminal D of the first D flip-flop is disconnected from the output terminal Q, the input terminal D of the second D flip-flop is disconnected from the output terminal Q, the clock signal input terminal of the first D flip-flop is connected to the first voltage comparator, and the clock signal input terminal of the second D flip-flop is connected to the second voltage comparator; The signal judgment unit includes a first AND gate, a second AND gate and an OR gate; The first AND gate is connected to the output terminal Q of the first D flip-flop and is also connected to the first voltage comparator; The second AND gate is disconnected from the output terminal Q of the second D flip-flop and is also connected to the second voltage comparator; Output terminals of the first AND gate and the second AND gate are both connected to the OR gate.

4. The silicon carbide MOSFET gate oxygen health status real-time monitoring circuit according to claim 2, characterized in that: The inverting input terminal of the first voltage comparator is connected to the first reference voltage, and the positive input terminal is connected to the differentiating circuit; The positive input terminal of the second voltage comparator is connected to the second reference voltage, and the negative input terminal is connected to the differentiating circuit; The voltage of the positive voltage spike signal is greater than the first reference voltage and the second reference voltage; the voltage of the negative voltage spike signal is less than the first reference voltage and the second reference voltage.

5. The silicon carbide MOSFET gate oxygen health status real-time monitoring circuit according to claim 2, characterized in that: The system also includes a microprocessor configured to receive the first specific monitoring signal and the second specific monitoring signal and record the duration of the first specific monitoring signal and the second specific monitoring signal.

6. The silicon carbide MOSFET gate oxygen health status real-time monitoring circuit according to claim 1, characterized in that: It also includes a programmable low-voltage source, which is used to provide power to the signal processing unit and the monitoring output unit.

7. A method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET, characterized in that: The method is implemented by the silicon carbide MOSFET gate oxygen health status real-time monitoring circuit according to any one of claims 1 to 6, comprising: Obtain the gate voltage of the silicon carbide MOSFET; Detecting a gate voltage signal during a turn-on phase and / or a turn-off phase of a silicon carbide MOSFET and converting the gate voltage signal into two voltage spike signals; The duration of the first voltage spike signal in the turn-on phase of the silicon carbide MOSFET is recorded as the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the silicon carbide MOSFET; and / or, the duration of the second voltage spike signal in the turn-off phase of the silicon carbide MOSFET is recorded as the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET; the time difference between the turn-on moment and the start moment of the Miller platform in the turn-off phase of the silicon carbide MOSFET and / or the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the silicon carbide MOSFET are used to reflect the gate oxide health status of the silicon carbide MOSFET.

8. The method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET according to claim 7, characterized in that: The recording of the duration of the first voltage spike signal during the turn-on phase of the silicon carbide MOSFET includes: Comparing the voltage spike signal with a reference voltage, and outputting a comparison signal reflecting the duration of the two voltage spike signals according to the comparison result; receiving the comparison signal; The first voltage spike signal is determined according to the comparison signal, and a first specific monitoring signal is synchronously output when the first voltage spike signal continues. The duration of the first specific monitoring signal is the duration of the first voltage spike signal.

9. The method for real-time monitoring of gate oxygen health status of silicon carbide MOSFET according to claim 7, characterized in that: The duration of the second voltage spike signal recorded during the turn-off phase of the silicon carbide MOSFET includes: Comparing the voltage spike signal with a reference voltage, and outputting a comparison signal reflecting the duration of the two voltage spike signals according to the comparison result; receiving the comparison signal; The second voltage spike signal is determined according to the comparison signal, and a second specific monitoring signal is synchronously output when the second voltage spike signal continues. The duration of the second specific monitoring signal is the duration of the second voltage spike signal.

10. The method for real-time monitoring of the gate oxygen health status of a silicon carbide MOSFET according to claim 7, characterized in that: Converting the gate signal into two positive voltage spike signals during the turn-on phase of the silicon carbide MOSFET; Recording the duration of the first positive voltage spike signal as the time difference between the turn-on moment of the silicon carbide MOSFET and the start moment of the Miller platform; Converting the gate signal into two negative voltage spike signals during the turn-off phase of the silicon carbide MOSFET; Recording the duration of the second negative voltage spike signal as the time difference between the end of the Miller platform in the turn-off phase of the silicon carbide MOSFET and the complete turn-off moment; The sum of the time difference between the turn-on moment and the start moment of the Miller platform in the turn-on phase of the SiC MOSFET and the time difference between the end moment of the Miller platform and the complete turn-off moment in the turn-off phase of the SiC MOSFET is used to reflect the gate oxide health status of the SiC MOSFET.

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