A short circuit protection circuit for a SiC MOSFET

Abstract

The application discloses a SiC MOSFET short-circuit protection circuit, which comprises a logic control unit, a gate driver, a short-circuit fault detection circuit and a short-circuit protection action circuit; the logic control unit comprises starting unit 1 and starting unit 2; the short-circuit fault detection circuit comprises a drain-source voltage type fault detection unit, a gate voltage / charge type fault detection unit and a drain-source current type fault detection unit. The application has the advantages that the drain-source voltage type short-circuit protection action is more reliable, the gate voltage / charge type and the drain-source current type short-circuit protection based on a detection inductor have a faster response speed, the detection results of the gate voltage / charge type fault detection unit and the drain-source current type fault detection unit are used for triggering the starting unit 1 and the starting unit 2 respectively, any starting unit is triggered, then the acceleration unit acts, the response speed of the drain-source voltage type fault detection unit is accelerated, and if the starting unit 1 and the starting unit 2 are both triggered, the short-circuit protection action circuit soft turns off the SiC MOSFET.

Description

Technical Field

[0001] This invention relates to a short-circuit protection circuit for SiC MOSFETs, belonging to the field of SiC MOSFET short-circuit protection. Background Technology

[0002] With its superior characteristics such as high blocking voltage, high switching frequency, and high thermal conductivity, SiC MOSFETs have become an ideal device choice for simplifying topologies, improving efficiency, and increasing power density. Compared to traditional Si-based IGBTs, SiC MOSFETs have shorter short-circuit withstand times, placing higher demands on the speed and reliability of short-circuit protection.

[0003] Currently, several documents and patents have researched short-circuit protection circuits and methods for SiC MOSFETs, which can be mainly categorized into three types. The first type is drain-source voltage-based short-circuit protection, which detects the drain-source voltage v. ds To reflect the drain-source current i ds When a short circuit fault occurs, i ds Rapid rise, when i ds Reaching the delinearity point, v ds Raise to bus voltage V dc By detecting v ds It can reliably identify HSF hard-switching short-circuit faults and FUL load short-circuit faults, but in order to avoid normal transient v of SiC MOSFETs ds The voltage has not yet dropped to the set threshold voltage V. ds,th To prevent protection malfunctions, a transient blind zone time t must be set. blank This results in a slower response time for protection actions. The second type is gate voltage / charge type short-circuit protection. This method identifies HSF short-circuit faults based on the difference in gate charging characteristics between normal operating conditions and short-circuit fault conditions during the turn-on process. During normal turn-on, Miller capacitance C... gd With v ds The current decreases and increases, at which point most of the gate current is supplied to C. gd Charging, gate voltage v gs Enter the Miller platform; and when an HSF short-circuit fault occurs, v ds Rise to V dc C gd Smaller and essentially unchanged, the gate current gives almost no benefit to C. gd During charging, the Miller plateau disappears, therefore, when an HSF short-circuit fault occurs, the gate charge Q... g It is smaller than the normal operating conditions. For example, Figure 1 As shown, a reasonable gate voltage reference value V is set. gs,ref and gate charge reference value Q g,ref If v gs >V gs,refAnd Q g <Q g,ref This method can determine the occurrence of an HSF short-circuit fault. It requires no blind time setting and provides rapid protection action, but V gs,ref and Q g,ref The protection method is susceptible to malfunctions due to factors such as operating bus voltage, leakage current, and operating temperature. The third type is leakage current-based short-circuit protection based on inductor detection. This method integrates the voltage across the inductor using a resistor-capacitor circuit to linearly reconstruct i. ds It can identify short-circuit faults without setting a blind time, and the protection action is rapid, but the recovery time is short. ds The linearity and gain are affected by the size of the detected inductor and the rate of change of the drain-source current di. ds / dt has a significant impact, making protection mechanisms prone to malfunction. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a SiCMOSFET short-circuit protection circuit to address the issues of slow response speed of drain-source voltage-type short-circuit protection and the susceptibility to false tripping of gate voltage / charge-type and drain-source current-type short-circuit protection based on sensing inductance.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A SiC MOSFET short-circuit protection circuit includes a logic control unit, a gate driver, a short-circuit fault detection circuit, and a short-circuit protection action circuit; one end of the gate driver is connected to the logic control unit, and the other end is connected to a detection resistor R. g,shunt The circuit is connected to a SiC MOSFET; one end of the short-circuit protection circuit is connected to a logic control unit, and the other end is connected to a SiC MOSFET; the logic control unit includes a first startup unit and a second startup unit; the short-circuit fault detection circuit includes a drain-source voltage fault detection unit, a gate voltage / charge fault detection unit, and a drain-source current fault detection unit.

[0007] The drain-source voltage fault detection unit receives output commands from the logic control unit to enable or disable the SiCMOSFET drain-source voltage v. ds The detection function feeds back the detection signal to the logic control unit; the gate voltage / charge type fault detection unit receives output commands from the logic control unit to enable or disable the gate charge Q of the SiC MOSFET. g The detection function feeds back the detection signal to the logic control unit; the drain-source current type fault detection unit detects the drain-source current i. ds And feed back the detection signal to the logic control unit;

[0008] When the logic control unit receives the PWM enable signal, the logic control unit sets the first dead zone time t. blank The output command switches the threshold voltage of the drain-source voltage fault detection unit to the first set value V. th,max Enable drain-source voltage v ds and gate charge Q g The detection functions include a drain-source voltage fault detection unit, a gate voltage / charge fault detection unit, and a drain-source current fault detection unit, which detect the drain-source voltage in real time. ds Gate voltage v gs Gate charge Q g and drain-source current i ds ;

[0009] If the logic control unit determines that the gate voltage / charge type fault detection unit has detected a short circuit fault, the first startup unit is triggered; if the logic control unit determines that the drain-source current type fault detection unit has detected a short circuit fault, the second startup unit is triggered.

[0010] If the first or second activation unit is triggered, the acceleration unit will operate, reducing the first blind time t. blank Shorten the time to the second blind zone t blank,min The threshold voltage of the drain-source voltage type fault detection unit is from the first set value V. th,max Switch to the second setting V th,min This accelerates the response speed of the drain-source voltage fault detection unit.

[0011] If both the first and second start-up units are triggered, the logic control unit ultimately determines and identifies a short-circuit fault, and issues a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. Simultaneously, it issues a command to shield the drain-source voltage-type fault detection unit v. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function;

[0012] If the logic control unit determines that the drain-source voltage fault detection unit has detected a short-circuit fault, it will ultimately confirm the short-circuit fault and send a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. Simultaneously, it will send a command to disable the drain-source voltage fault detection unit. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function;

[0013] If the logic control unit determines that no short-circuit fault has been detected, when the logic control unit receives the PWM shutdown signal, it outputs a command to shield the drain-source voltage fault detection unit v. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function.

[0014] Furthermore, one end of the drain-source voltage fault detection unit is connected to the drain of the SiC MOSFET, and the other end is connected to the logic control unit.

[0015] Furthermore, one end of the gate voltage / charge type fault detection unit is connected to the gate of the SiC MOSFET, and the other end is connected to the logic control unit.

[0016] Furthermore, the gate voltage / charge type fault detection unit includes a gate voltage detection circuit and a gate charge detection circuit; the gate voltage detection circuit detects the gate voltage v of the SiC MOSFET in real time. gs The detection signal is fed back to the logic control unit; the gate charge detection circuit receives output commands from the logic control unit to enable or disable the gate charge Q of the SiC MOSFET. g It has a detection function and feeds back the detection signal to the logic control unit.

[0017] Furthermore, one end of the drain-source current type fault detection unit is connected to a detection inductor L. kp Connect one end to the source of the SiC MOSFET and the other end to the logic control unit.

[0018] Furthermore, the detection inductor L kp This is the parasitic inductance between the Kelvin source and the power source of the SiC MOSFET.

[0019] Furthermore, the short-circuit protection circuit is a high-resistance soft-shutdown circuit or a reduced-gate-voltage soft-shutdown circuit.

[0020] Furthermore, the drain-source voltage type fault detection unit includes a resistor-capacitor voltage divider circuit, a first comparator, a reset switch SW1, and a switching switch SW2; the resistor-capacitor voltage divider circuit consists of a first voltage-dividing capacitor C. p First voltage divider resistor R total Second voltage divider capacitor C a Second voltage divider resistor R div Composition, the first voltage divider capacitor C p First voltage divider resistor R total After being connected in parallel, one end is connected to the drain of the SiC MOSFET, and the other end is connected to the non-inverting input of the first comparator; reset switch SW1, second voltage divider capacitor C a Second voltage divider resistor R div After being connected in parallel, one end is connected to the non-inverting input of the first comparator, and the other end is connected to the power supply V. EE The inverting input of the first comparator is connected to the stationary input of the switching switch SW2, and the two moving inputs of the switching switch SW2 are respectively connected to the first set value V. th,max Second set value V th,minThe output of the first comparator is connected to the logic control unit.

[0021] Furthermore, the gate voltage / charge type fault detection unit includes a gate voltage detection circuit and a gate charge detection circuit; the gate voltage detection circuit is composed of a second comparator, the non-inverting terminal of the second comparator is connected to the gate of the SiC MOSFET, and the inverting terminal is connected to the gate reference voltage V. gs,ref The output terminal is connected to the logic control unit; the gate charge detection circuit consists of a differential amplifier circuit, an integrator circuit, an integrator reset circuit, and a third comparator; it detects the charge through resistor R. g,shunt The gate current signal of the SiC MOSFET is acquired, amplified by a differential amplifier circuit, and then detected by an integrator circuit to measure the gate charge Q. g Gate charge Q g Input to the inverting input of the third comparator, gate charge reference value Q g,ref The input is to the non-inverting input of the third comparator, and the output of the third comparator is connected to the logic control unit.

[0022] Furthermore, the leakage-source current fault detection unit consists of a first resistor R s First capacitor C s It is composed of a fourth comparator; the first resistor R s First capacitor C s After being connected in series, it is connected in parallel to the sensing inductor L. kp At both ends, the first resistor R s First capacitor C s The common terminal is connected to the non-inverting input of the fourth comparator, and the inverting input of the fourth comparator is connected to the threshold voltage V. o,th The output of the fourth comparator is connected to the logic control unit.

[0023] Furthermore, the short-circuit protection circuit consists of a large resistor R. soft Composed of soft-shutdown switch SW3; large resistor R soft One end of the circuit is connected in series with the soft-turn-off switch SW3 to the gate of the SiC MOSFET, and the other end is connected to the power supply V. EE .

[0024] Compared with the prior art, the present invention, employing the above technical solution, has the following beneficial effects:

[0025] This invention combines the advantages of more reliable drain-source voltage-based short-circuit protection with faster response times from gate voltage / charge-based and drain-source current-based short-circuit protection methods. The detection results from the gate voltage / charge-based fault detection unit and the drain-source current-based fault detection unit trigger startup unit 1 and startup unit 2, respectively. When either startup unit is triggered, the acceleration unit activates to speed up the response of the drain-source voltage-based fault detection unit. If both startup units 1 and 2 are triggered, the logic control unit directly outputs a command to the short-circuit protection action circuit to soft-shut down the SiC MOSFET. Based on the startup and acceleration protection methods, the SiC MOSFET short-circuit protection circuit provided by this invention combines fast operation with high reliability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the principle of existing gate voltage / charge short-circuit protection methods;

[0027] Figure 2 This is a block diagram of the SiC MOSFET short-circuit protection circuit of the present invention;

[0028] Figure 3 This is a schematic diagram of an embodiment of the drain-source voltage-based fault detection unit of the present invention;

[0029] Figure 4 This is a schematic diagram of an embodiment of the gate voltage / charge type fault detection unit of the present invention;

[0030] Figure 5 This is a schematic diagram of an embodiment of the drain-source current type fault detection unit of the present invention;

[0031] Figure 6 This is a schematic diagram of an embodiment of the short-circuit protection action circuit of the present invention;

[0032] Figure 7 This is a flowchart illustrating the working principle of an embodiment of the SiC MOSFET short-circuit protection circuit of the present invention.

[0033] Among them, 001 is a short-circuit fault detection circuit; 002 is a drain-source voltage type fault detection unit; 003 is a resistor-capacitor voltage divider circuit; 004 is a gate voltage detection circuit; 005 is a gate charge detection circuit; 006 is a drain-source current type fault detection unit; and 007 is a short-circuit protection action circuit. Detailed Implementation

[0034] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] In one embodiment, such as Figure 2As shown, a SiC MOSFET short-circuit protection circuit is provided. This SiC MOSFET short-circuit protection circuit includes a logic control unit, a gate driver, a short-circuit fault detection circuit, and a short-circuit protection action circuit. The short-circuit fault detection circuit consists of a drain-source voltage type fault detection unit and a detection resistor R. g,shunt Gate voltage / charge type fault detection unit, detection inductor L kp The system comprises a drain-source current fault detection unit. The logic control unit includes at least a startup unit and an acceleration unit, and accepts a PWM input signal. It is connected to a gate driver, a drain-source voltage fault detection unit, a gate voltage / charge fault detection unit, a drain-source current fault detection unit, and a short-circuit protection circuit. One end of the gate driver is connected to the logic control unit, and the other end is connected to a detection resistor R. g,shunt The drain-source voltage-type fault detection unit is connected at one end to the drain of a SiC MOSFET and at the other end to a logic control unit; the detection resistor R g,shunt One end is connected to the gate driver, and the other end is connected to the gate of the SiC MOSFET; the gate voltage / charge type fault detection unit is connected in parallel with R. g,shunt The other end is connected to the logic control unit; the two ends of the drain-source current type fault detection unit are connected in parallel to the detection inductor L. kp One end is connected to the logic control unit; the short-circuit protection circuit is connected to the logic control unit at one end and to the gate of the SiC MOSFET at the other end.

[0036] In one embodiment, such as Figure 7 As shown, the working process of the above short-circuit protection circuit is as follows:

[0037] When the logic control unit receives the PWM enable signal, it sets the dead time t. blank The output command switches the threshold voltage of the drain-source voltage fault detection unit to V. th,max Enable drain-source voltage fault detection unit v ds Detection function and gate voltage / charge type fault detection unit Q g The detection function includes a drain-source voltage fault detection unit, a gate voltage / charge fault detection unit, and a drain-source current fault detection unit to detect drain-source voltage, gate voltage / charge, and drain-source current in real time.

[0038] If the logic control unit determines that the gate voltage / charge type fault detection unit has detected a short circuit fault, then the startup unit 1 is triggered; if the logic control unit determines that the drain-source current type fault detection unit has detected a short circuit fault, then the startup unit 2 is triggered.

[0039] If either starter unit 1 or starter unit 2 is triggered, the acceleration unit's action is accelerated, reducing the blind time t. blank Shorten to tblank,min The threshold voltage of the drain-source voltage type fault detection unit is from V th,max Switch to V th,min This accelerates the response speed of the drain-source voltage fault detection unit.

[0040] If both start-up unit 1 and start-up unit 2 are triggered, the logic control unit ultimately determines and identifies a short-circuit fault, and issues a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. Simultaneously, it issues a command to shield the drain-source voltage-type fault detection unit v. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function;

[0041] If the logic control unit determines that the drain-source voltage fault detection unit has detected a short-circuit fault, it will ultimately confirm the short-circuit fault and send a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. Simultaneously, it will send a command to disable the drain-source voltage fault detection unit. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function;

[0042] If the logic control unit determines that no short-circuit fault has been detected, when the logic control unit receives the PWM shutdown signal, it outputs a command to shield the drain-source voltage fault detection unit v. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function.

[0043] In one embodiment, such as Figure 3 As shown, the drain-source voltage fault detection unit includes a resistor-capacitor voltage divider circuit, a first comparator, a reset switch SW1, and a switching switch SW2; the resistor-capacitor voltage divider circuit consists of C p R total C a and R div Composition, C p C a Connected to R respectively total and R div At both ends, the drain-source voltage of the SiC MOSFET is divided by a resistor-capacitor voltage divider circuit to obtain the detection voltage v. detect The first comparator's non-inverting input v detect The inverting input is connected to the switching switch SW2, and the output sends a feedback detection signal S1 to the logic control unit; the reset switch SW1 is connected in parallel to C. a Both ends receive output commands from the logic control unit; one end of the switch SW2 is connected to the inverting input of the first comparator, and the other end is connected to the threshold voltage V. th,max The other end is connected to the threshold voltage V. th,min V th,max Greater than Vth,min It also accepts output commands from the acceleration unit; when the logic control unit receives the PWM enable command, it sets the dead time t. blank And export command to connect SW2 to V th,max Simultaneously, the output command disconnects SW1, enabling the SiC MOSFET drain-source voltage detection function; during normal start-up, v ds The voltage drops to the on-state voltage drop, v detect Less than V th,max When a short circuit fault occurs, v ds Rise to bus voltage, v detect Greater than V th,max Blind spot time t blank After completion, the logic control unit can determine whether the drain-source voltage fault detection unit has detected a short-circuit fault by recognizing the detection signal S1. If the logic control unit determines that the drain-source voltage fault detection unit has detected a short-circuit fault, it will ultimately determine that a short-circuit fault has been detected and issue a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. If the acceleration unit operates, the dead time t... blank Shorten to t blank,min And output a command to SW2 to make the threshold voltage drop from V th,max Switch to V th,min This accelerates the response speed of the drain-source voltage fault detection unit; if the logic control unit receives a PWM shutdown command or output command to the short-circuit protection action circuit, the logic control unit output command will close SW1, thus disabling the SiC MOSFET drain-source voltage detection function.

[0044] In one embodiment, such as Figure 4 As shown, the gate voltage / charge type fault detection unit includes a gate voltage detection circuit and a gate charge detection circuit; the gate voltage detection circuit is composed of a second comparator, the non-inverting terminal of which is connected to the gate of the SiC MOSFET, and the inverting terminal is connected to the gate reference voltage V. gs,ref The output terminal feeds back the detection signal S2 to the logic control unit; the gate charge detection circuit consists of a differential amplifier circuit, an integrator circuit, an integrator reset circuit, and a third comparator; and the detection is achieved through the detection resistor R. g,shunt The gate current signal is acquired and amplified by a differential amplifier circuit. The amplified output signal is then integrated by an integrator circuit to detect the gate charge Q. g The third comparator's inverting input Q is... g The non-inverting input gate charge reference value Q g,ref The output terminal feeds back the detection signal S3 to the logic control unit; the logic control unit outputs a command to the integral reset circuit to enable or disable the gate charge detection function; during normal operation, when the gate voltage v gs Rise to gate voltage reference value V gs,ref Qg Greater than Q g,ref When a short circuit fault occurs, when v gs Reaching V gs,ref At that time, Q g Still less than Q g,ref The logic control unit can determine whether the gate voltage / charge fault detection unit has detected a short circuit fault by identifying detection signals S2 and S3. If the logic control unit determines that the gate voltage / charge fault detection unit has detected a short circuit fault, it triggers the start-up unit 1, and the acceleration unit shortens the dead zone time t. blank To t blank,min And output a command to SW2, causing the threshold voltage to change from V th,max Switch to V th,min This accelerates the response speed of the drain-source voltage fault detection unit; if the logic control unit receives a PWM shutdown command or outputs a command to the short-circuit protection action circuit, the logic control unit outputs a command to the integral reset circuit, thus disabling the SiC MOSFET gate charge detection function.

[0045] In one embodiment, such as Figure 5 As shown, the drain-source current fault detection unit consists of R s C s It is composed of a fourth comparator; R s C s After being connected in series, it is connected in parallel to the sensing inductor L. kp Both ends, R s C s Circuit for L kp The detection voltage v is obtained by integrating the voltage across the two terminals. o v o With drain-source current i ds The relationship is approximately linear; the input v at the non-inverting input of the fourth comparator o Inverting input threshold voltage v o,th The output detection signal S4 is fed back to the logic control unit; under normal operating conditions, the detection voltage v o Less than v o,th When a short circuit fault occurs, i ds Rapid rise, detect voltage v o Greater than v o,th The logic control unit can determine whether the drain-source current fault detection unit has detected a short circuit fault by recognizing the detection signal S4. If the logic control unit determines that the drain-source current fault detection unit has detected a short circuit fault, it triggers the start-up unit 2, and the acceleration unit shortens the dead zone time t. blank To t blank,min And output a command to SW2, causing the threshold voltage to change from V th,max Switch to V th,min This accelerates the response speed of the drain-source voltage fault detection unit.

[0046] In one embodiment, such as Figure 6 As shown, the short-circuit protection circuit consists of a large resistor R. soft Together with the soft-shutdown switch SW3, it forms a circuit. If both starting unit 1 and starting unit 2 are triggered, or the logic control unit determines that the drain-source voltage fault detection unit has detected a short-circuit fault, the logic control unit determines that a short-circuit fault has been detected and sends a command to the short-circuit protection action circuit, causing the soft-shutdown switch SW3 to close. The SiC MOSFET then passes through a large resistor R. soft Soft shutdown.

[0047] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A SiC MOSFET short-circuit protection circuit, characterized in that, It includes a logic control unit, a gate driver, a short-circuit fault detection circuit, and a short-circuit protection circuit; one end of the gate driver is connected to the logic control unit, and the other end is connected to a detection resistor R. g,shunt The circuit connects to a SiC MOSFET; one end of the short-circuit protection circuit is connected to a logic control unit, and the other end is connected to the SiC MOSFET; the short-circuit fault detection circuit includes a drain-source voltage fault detection unit, a gate voltage / charge fault detection unit, and a drain-source current fault detection unit; one end of the drain-source voltage fault detection unit is connected to the drain of the SiC MOSFET, and the other end is connected to the logic control unit; one end of the gate voltage / charge fault detection unit is connected to the gate of the SiC MOSFET, and the other end is connected to the logic control unit; one end of the drain-source current fault detection unit is connected to the source of the SiC MOSFET, and the other end is connected to the logic control unit. The drain-source voltage fault detection unit receives output commands from the logic control unit to enable or disable the SiCMOSFET drain-source voltage v. ds The detection function feeds back the detection signal to the logic control unit; the gate voltage / charge type fault detection unit receives output commands from the logic control unit to enable or disable the gate charge Q of the SiC MOSFET. g The detection function feeds back the detection signal to the logic control unit; the drain-source current type fault detection unit detects the drain-source current i. ds And feed back the detection signal to the logic control unit; The logic control unit includes a first startup unit, a second startup unit, and an acceleration unit; When the logic control unit receives the PWM enable signal, the logic control unit sets the first dead zone time t. blank The output command switches the threshold voltage of the drain-source voltage fault detection unit to the first set value V. th,max Enable drain-source voltage v gs and gate charge Q g The detection functions include a drain-source voltage fault detection unit, a gate voltage / charge fault detection unit, and a drain-source current fault detection unit, which detect the drain-source voltage in real time. ds Gate voltage v gs Gate charge Q g and drain-source current i ds ; If the logic control unit determines that the gate voltage / charge type fault detection unit has detected a short circuit fault, the first startup unit is triggered; if the logic control unit determines that the drain-source current type fault detection unit has detected a short circuit fault, the second startup unit is triggered. If the first or second activation unit is triggered, the acceleration unit will operate, reducing the first blind time t. blank Shorten the time to the second blind zone t blank,min The threshold voltage of the drain-source voltage type fault detection unit is from the first set value V. th,max Switch to the second setting V th,min This accelerates the response speed of the drain-source voltage fault detection unit. If both the first and second start-up units are triggered, the logic control unit ultimately determines and identifies a short-circuit fault, and issues a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. Simultaneously, it issues a command to shield the drain-source voltage-type fault detection unit v. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function; If the logic control unit determines that the drain-source voltage fault detection unit has detected a short-circuit fault, it will ultimately confirm the short-circuit fault and send a command to the short-circuit protection circuit to softly turn off the SiC MOSFET. Simultaneously, it will send a command to disable the drain-source voltage fault detection unit. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function; If the logic control unit determines that no short-circuit fault has been detected, when the logic control unit receives the PWM shutdown signal, it outputs a command to shield the drain-source voltage fault detection unit v. ds Detection function and gate voltage / charge type fault detection unit Q g Detection function.

2. The SiC MOSFET short-circuit protection circuit according to claim 1, characterized in that, The gate voltage / charge type fault detection unit includes a gate voltage detection circuit and a gate charge detection circuit; the gate voltage detection circuit detects the gate voltage v of the SiC MOSFET in real time. gs And feed back the detection signal to the logic control unit; The gate charge detection circuit receives output commands from the logic control unit to enable or disable the gate charge Q of the SiC MOSFET. g It has a detection function and feeds back the detection signal to the logic control unit.

3. The SiC MOSFET short-circuit protection circuit according to claim 1, characterized in that, One end of the drain current type fault detection unit is connected to the detection inductor L. kp Connect to the source of the SiC MOSFET.

4. The SiC MOSFET short-circuit protection circuit according to claim 3, characterized in that, The detection inductor L kp This is the parasitic inductance between the Kelvin source and the power source of the SiC MOSFET.

5. The SiC MOSFET short-circuit protection circuit according to claim 1, characterized in that, The short-circuit protection circuit is a high-resistance soft-shutdown circuit or a reduced-gate-voltage soft-shutdown circuit.

6. The SiC MOSFET short-circuit protection circuit according to claim 1, characterized in that, The drain-source voltage fault detection unit includes a resistor-capacitor voltage divider circuit, a first comparator, a reset switch SW1, and a changeover switch SW2; the resistor-capacitor voltage divider circuit consists of a first voltage-dividing capacitor C. p First voltage divider resistor R total Second voltage divider capacitor C a Second voltage divider resistor R div Composition, the first voltage divider capacitor C p First voltage divider resistor R total After being connected in parallel, one end is connected to the drain of the SiC MOSFET, and the other end is connected to the non-inverting input of the first comparator; reset switch SW1, second voltage divider capacitor C a Second voltage divider resistor R div After being connected in parallel, one end is connected to the non-inverting input of the first comparator, and the other end is connected to the power supply V. EE The inverting input of the first comparator is connected to the stationary input of the switching switch SW2, and the two moving inputs of the switching switch SW2 are respectively connected to the first set value V. th,max Second set value V th,min The output of the first comparator is connected to the logic control unit.

7. The SiC MOSFET short-circuit protection circuit according to claim 1, characterized in that, The gate voltage / charge type fault detection unit includes a gate voltage detection circuit and a gate charge detection circuit; the gate voltage detection circuit is composed of a second comparator, the non-inverting terminal of which is connected to the gate of the SiC MOSFET, and the inverting terminal is connected to the gate reference voltage V. gs,ref The output terminal is connected to the logic control unit; The gate charge detection circuit consists of a differential amplifier circuit, an integrator circuit, an integrator-reset circuit, and a third comparator; it detects the charge through resistor R. g,shunt The gate current signal of the SiC MOSFET is acquired, amplified by a differential amplifier circuit, and then detected by an integrator circuit to detect the gate charge Q. g Gate charge Q g Input to the inverting input of the third comparator, gate charge reference value Q g,ref The input is to the non-inverting input of the third comparator, and the output of the third comparator is connected to the logic control unit.

8. The SiC MOSFET short-circuit protection circuit according to claim 3, characterized in that, The leakage current type fault detection unit consists of a first resistor R s First capacitor C s It is composed of a fourth comparator; the first resistor R s First capacitor C s After being connected in series, it is connected in parallel to the sensing inductor L. kp At both ends, the first resistor R s First capacitor C s The common terminal is connected to the non-inverting input of the fourth comparator, and the inverting input of the fourth comparator is connected to the threshold voltage V. o,th The output of the fourth comparator is connected to the logic control unit.

9. The SiC MOSFET short-circuit protection circuit according to claim 1, characterized in that, The short-circuit protection circuit consists of a large resistor R. soft Composed of soft-shutdown switch SW3; large resistor R soft After being connected in series with the soft-turn-off switch SW3, one end is connected to the gate of the SiC MOSFET, and the other end is connected to the power supply V. EE .

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