Silicon carbide device driving protection apparatus and method based on characteristic state current compensation

Abstract

This invention discloses a silicon carbide (SiC) device drive protection device and method based on characteristic state current compensation. The device includes a SiC device comprising a low-potential power electrode, a high-potential power electrode, and a gate. The circuit includes a drive protection circuit and a PWM drive module. The drive protection circuit includes a first terminal, a second terminal, a third terminal, and a fourth terminal. The drive protection circuit monitors the turn-on voltage change rate of the SiC device, generates an injection current positively correlated with the turn-on voltage change rate, and inputs the injection current to the gate. The first terminal is connected to the low-potential power electrode to provide a reference potential. The second terminal is connected to the high-potential power electrode to monitor the turn-on voltage change rate. The third terminal is connected to the gate via the PWM drive module to ensure that the drive protection circuit operates synchronously when the SiC device is turned on. The fourth terminal is connected to the gate to input the injection current to the gate after the turn-on voltage change rate is returned from the second terminal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a silicon carbide device driving protection device and method based on characteristic state current compensation. BACKGROUND

[0002] The development of high-voltage silicon carbide devices greatly promotes the simplification of power electronic topologies suitable for medium / high-voltage scenarios and improves the reliability of the system. The driving protection design of high-voltage silicon carbide devices is the key to ensuring high reliability of the devices.

[0003] The short-circuit current of silicon carbide devices is large, the short-circuit resistance is weak, and the failure risk is high. Only at the local driving level can the device be reliably turned off to achieve short-circuit protection. The following schemes exist in existing short-circuit protection technologies:

[0004] Scheme 1: Research the difference between the gate current characteristics of the short-circuit process and the normal switching process of silicon carbide devices. Aiming at the feature that negative gate current appears in both load short-circuit and hard switching short-circuit process, a short-circuit fault is detected by gate current detection to speed up the short-circuit protection action time. However, this scheme relies on the change of short-circuit process current rise rate, and there is a risk of short-circuit failure.

[0005] Scheme 2: Optimize the design of the desaturation detection circuit applied to high-voltage silicon carbide devices, which is low in cost and easy to integrate. However, the existence of blanking time increases the risk of hard switching short-circuit failure.

[0006] Scheme 3: On the basis of desaturation detection technology, aiming at the shortcoming of blanking time in hard switching short-circuit detection, an additional driving voltage monitoring circuit is added to speed up the short-circuit detection. However, the reference value design of the driving voltage monitoring circuit is not flexible, which increases the design difficulty.

[0007] Scheme 4: Some researchers have proposed a dv / dt detection short-circuit fault method, which can speed up the detection speed of hard switching short-circuit compared with desaturation detection. However, the misoperation caused by low bus voltage is not considered, and the application has limitations.

[0008] Scheme 5: Some researchers have proposed a two-step short-circuit protection scheme design based on Kelvin emitter inductance di / dt detection and desaturation detection, which effectively avoids the problem of short-circuit mis-detection. However, the overall short-circuit protection action time is still long, and more data support is needed for short-circuit failure risk assessment.

[0009] The above-mentioned existing short-circuit protection technology schemes all improve the short-circuit detection, but few improve the protection action end. Therefore, a new technical scheme is urgently needed to solve the technical problem of how to effectively and reliably drive the short-circuit protection of high-voltage silicon carbide devices. SUMMARY

[0010] This invention provides a silicon carbide device drive protection device and method based on characteristic state current compensation, which solves the technical problem of how to effectively and reliably protect high-voltage silicon carbide devices from drive short circuits.

[0011] To achieve the above objectives, the present invention provides a silicon carbide device drive protection device based on characteristic state current compensation. The silicon carbide device includes a low-potential power electrode, a high-potential power electrode, and a gate electrode. The device includes a drive protection circuit and a PWM drive module. The drive protection circuit includes a first terminal, a second terminal, a third terminal, and a fourth terminal.

[0012] The drive protection circuit monitors the turn-on voltage change rate of the silicon carbide device, generates an injection current positively correlated with the turn-on voltage change rate, and inputs the injection current to the gate. The first terminal is connected to the low-potential power electrode to provide a reference potential. The second terminal is connected to the high-potential power electrode to monitor the turn-on voltage change rate. The third terminal is connected to the gate through the PWM drive module to ensure that the drive protection circuit works synchronously when the silicon carbide device is turned on. The fourth terminal is connected to the gate to input the injection current to the gate after the turn-on voltage change rate is returned from the second terminal.

[0013] Preferably, the drive protection circuit includes a DC power supply. PNP transistor and P-channel MOSFET ,resistance , and ,capacitance and diodes .

[0014] DC power supply The negative terminal is connected to the first terminal; PNP transistor and The base of the PNP transistor is connected to the base. The emitter is connected to a resistor Connect to DC power supply The positive electrode, the collector is through the diode. Connected to the fourth terminal; PNP transistor The emitter is connected to a resistor Connect to DC power supply The positive electrode, the collector is connected to the capacitor. Connected to the second terminal; P-channel MOSFET The source is connected to a DC power supply. The positive terminal and the drain terminal are connected to the PNP transistor. The collector and base, and the gate are connected by a resistor. Connect to the third terminal.

[0015] Preferably, the PWM drive module includes a PWM generator and a drive resistor.

[0016] The third terminal is connected to the output of the PWM generator, which is connected to the gate via a drive resistor. The other end of the PWM generator is connected to the low-potential power electrode. The PWM generator is used to provide switching signals for silicon carbide devices.

[0017] Preferably, ensuring that the drive protection circuit operates synchronously when the silicon carbide device is turned on includes:

[0018] When the silicon carbide device is in the off state, the P-channel field-effect transistor... The source-gate potential difference is greater than the turn-on threshold voltage, resulting in a low-resistance state from source to drain. The turn-on voltage change rate passes through the capacitor. The resulting displacement current flows into the P-channel MOSFET. or P-channel MOSFET In an anti-parallel diode, when the rate of change of the turn-on voltage is positive, the displacement current flows into the P-channel MOSFET. When the rate of change of the turn-on voltage is negative, the displacement current flows into the P-channel MOSFET. The anti-parallel diodes; the drive protection circuit stops working.

[0019] Preferably, ensuring that the drive protection circuit operates synchronously when the silicon carbide device is turned on also includes:

[0020] When the silicon carbide device is in the ON state, the P-channel field-effect transistor... The source-gate potential difference is less than the turn-on threshold voltage, resulting in a high-resistance state from source to drain. The rate of change of the turn-on voltage is reduced by the capacitance. The resulting displacement current flows into the PNP transistor. and or P-channel MOSFET In an anti-parallel diode, when the rate of change of the turn-on voltage is positive, displacement current flows into the PNP transistor. and When the rate of change of the turn-on voltage is negative, the displacement current flows into the P-channel MOSFET. The anti-parallel diodes drive the protection circuit to start working.

[0021] Preferably, the injection current into the gate after the return of the turn-on voltage change rate at the second terminal includes:

[0022] When the second terminal returns the rate of change of the turn-on voltage, the DC power supply It generates current and is supplied by a DC power source. PNP transistor and and resistance and The output of the mirror current source is transmitted through a PNP transistor. The collector passes through the diode Inject current into the gate of a silicon carbide device.

[0023] This invention also provides a driving protection method for silicon carbide devices based on characteristic state current compensation. The driving protection device based on this invention includes the following methods:

[0024] By monitoring the turn-on voltage change rate of the silicon carbide device through a drive protection circuit, an injection current positively correlated with the turn-on voltage change rate is generated, and the injection current is input to the gate, including:

[0025] The first terminal is connected to the low-potential power electrode of the silicon carbide device to provide a reference potential.

[0026] The high-potential power electrode of the silicon carbide device is connected via a second terminal to monitor the rate of change of the turn-on voltage.

[0027] The third terminal is connected to the gate of the silicon carbide device via the PWM drive module to ensure that the drive protection circuit works synchronously when the silicon carbide device is turned on.

[0028] The gate of the silicon carbide device is connected via the fourth terminal to inject current into the gate after the turn-on voltage change rate returns at the second terminal.

[0029] The present invention has the following beneficial effects:

[0030] This invention relates to a silicon carbide (SiC) device drive protection device based on characteristic state current compensation. It adjusts the high-voltage SiC drive process by identifying the differences in characteristic quantities between normal switching and short-circuit processes. During normal switching, the SiC device is turned on normally due to the additional current injected into the gate. However, during a short circuit, no additional current is injected into the gate, slowing down the SiC device's turn-on process and extending its short-circuit withstand time. The entire implementation does not involve active control circuitry, thus ensuring a fast drive response. Furthermore, since only the drive's protective shutdown action is optimized, it can be combined with existing short-circuit detection schemes to form a faster and more effective short-circuit protection design. This invention, combining a drain-source parallel capacitor and a mirror current source in the drive protection circuit, ensures a small short-circuit current during hard switching short-circuit processes while accelerating the normal turn-on process.

[0031] The silicon carbide device driving protection method based on characteristic state current compensation of the present invention, and the device based on the present invention, have the same beneficial effects as the device of the present invention.

[0032] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is a schematic diagram of a drive protection device according to a preferred embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the drive protection circuit and drive protection device according to a preferred embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of a silicon carbide half-bridge used for analysis according to a preferred embodiment of the present invention.

[0037] Figure 4 This is a schematic diagram illustrating the turn-on process analysis of a voltage source type drive scheme according to a preferred embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram illustrating the hard-switching short-circuit protection analysis of a voltage source type drive scheme according to a preferred embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram illustrating the opening process of a preferred embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram illustrating the hard switch short-circuit protection analysis of a preferred embodiment of the present invention.

[0041] Figure 8 This is a waveform diagram of the switching transistor turn-on process at 22.4µs in a preferred embodiment of the present invention without the driving protection circuit of the present invention.

[0042] Figure 9 The waveform diagram of the switching transistor turn-on process at 22.4µs is shown in the preferred embodiment of the present invention when the drive protection circuit of the present invention is present. Detailed Implementation

[0043] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0044] See Figure 1In a preferred embodiment of the present invention, a silicon carbide device drive protection device based on characteristic state current compensation is provided. The silicon carbide device includes a low-potential power electrode, a high-potential power electrode, and a gate electrode. The device includes a drive protection circuit and a PWM drive module. The drive protection circuit includes a first terminal, a second terminal, a third terminal, and a fourth terminal.

[0045] The drive protection circuit monitors the turn-on voltage change rate of the silicon carbide (SiC) device, generates an injection current positively correlated with the turn-on voltage change rate, and inputs the injection current to the gate. The first terminal is connected to the low-potential power electrode to provide a reference potential. The second terminal is connected to the high-potential power electrode to monitor the turn-on voltage change rate and provide a feedback signal to the drive protection circuit. The third terminal is connected to the gate via a PWM drive module to detect the drive signal of the SiC device, ensuring that the drive protection circuit operates synchronously when the SiC device is turned on and synchronously pauses operation when the SiC device is turned off. The fourth terminal is connected to the gate to input the injection current to the gate after the turn-on voltage change rate is returned from the second terminal, accelerating the turn-on process of the SiC device. Figure 1 middle, , , and These correspond to the first terminal, the second terminal, the third terminal, and the fourth terminal, respectively.

[0046] In a preferred embodiment of the present invention, based on the third terminal, the drive signal controls the turn-on and turn-off of the silicon carbide device while simultaneously controlling the operation of the drive protection circuit. This ensures that the drive protection circuit only operates when the device is turned on, accelerating the turn-on process, without affecting the turn-off process of the silicon carbide device. Simultaneously, when a short circuit occurs in the silicon carbide device, the drive protection circuit tends to be inactive.

[0047] In a preferred embodiment of the present invention, the PWM driving module includes a PWM generator and a driving resistor.

[0048] The third terminal is connected to the output of the PWM generator, which is connected to the gate via a drive resistor. The other end of the PWM generator is connected to the low-potential power electrode. The PWM generator is used to provide switching signals for silicon carbide devices.

[0049] exist Figure 1 In this context, PWM stands for PWM generator; Indicates silicon carbide devices; This represents the voltage between the low-potential power electrode and the high-potential power electrode of a silicon carbide device. This indicates the driving resistance.

[0050] See one implementation circuit of the drive protection circuit. Figure 2 In a preferred embodiment of the present invention, the drive protection circuit includes a DC power supply. PNP transistor and P-channel MOSFET ,resistance , and ,capacitance and diodes ;

[0051] DC power supply The negative terminal is connected to the first terminal; PNP transistor and The base of the PNP transistor is connected to the base. The emitter is connected to a resistor Connect to DC power supply The positive electrode, the collector is through the diode. Connected to the fourth terminal; PNP transistor The emitter is connected to a resistor Connect to DC power supply The positive electrode, the collector is connected to the capacitor. Connected to the second terminal; P-channel MOSFET The source is connected to a DC power supply. The positive terminal and the drain terminal are connected to the PNP transistor. The collector and base, and the gate are connected by a resistor. Connect to the third terminal. Figure 2 middle, Indicates the injected current; This indicates the driving voltage of the silicon carbide device; This indicates the current flowing through the silicon carbide device.

[0052] In a preferred embodiment of the present invention, a diode Used to prevent reverse injection of current.

[0053] In a preferred embodiment of the present invention, ensuring that the drive protection circuit operates synchronously when the silicon carbide device is turned on includes:

[0054] When the silicon carbide device is in the off state, the P-channel field-effect transistor... The source-gate potential difference is greater than the turn-on threshold voltage, resulting in a low-resistance state from source to drain. The turn-on voltage change rate passes through the capacitor. The resulting displacement current flows into the P-channel MOSFET. or P-channel MOSFET In an anti-parallel diode, when the rate of change of the turn-on voltage is positive, the displacement current flows into the P-channel MOSFET. When the rate of change of the turn-on voltage is negative, the displacement current flows into the P-channel MOSFET. The anti-parallel diodes; the drive protection circuit stops working.

[0055] When the silicon carbide device is in the ON state, the P-channel field-effect transistor... The source-gate potential difference is less than the turn-on threshold voltage, resulting in a high-resistance state from source to drain. The rate of change of the turn-on voltage is reduced by the capacitance. The resulting displacement current flows into the PNP transistor. and or P-channel MOSFET In an anti-parallel diode, when the rate of change of the turn-on voltage is positive, displacement current flows into the PNP transistor. and When the rate of change of the turn-on voltage is negative, the displacement current flows into the P-channel MOSFET. The anti-parallel diodes drive the protection circuit to start working.

[0056] In a preferred embodiment of the present invention, the injection current into the gate after the return of the turn-on voltage change rate at the second terminal includes:

[0057] When the second terminal returns the rate of change of the turn-on voltage, the DC power supply It generates current and is supplied by a DC power source. PNP transistor and and resistance and The output of the mirror current source is transmitted through a PNP transistor. The collector passes through the diode Inject current into the gate of a silicon carbide device.

[0058] In a preferred embodiment of the present invention, the turn-on process of the device is accelerated by monitoring the rate of change of the turn-on voltage and inputting current to the gate in real time.

[0059] This invention relates to a silicon carbide (SiC) device drive protection device based on characteristic state current compensation. It adjusts the high-voltage SiC drive process by identifying the differences in characteristic quantities between normal switching and short-circuit processes. During normal switching, the SiC device is turned on normally due to the additional current injected into the gate. However, during a short circuit, no additional current is injected into the gate, slowing down the SiC device's turn-on process and extending its short-circuit withstand time. The entire implementation does not involve active control circuitry, thus ensuring a fast drive response. Furthermore, since only the drive's protective shutdown action is optimized, it can be combined with existing short-circuit detection schemes to form a faster and more effective short-circuit protection design. This invention, combining a drain-source parallel capacitor and a mirror current source in the drive protection circuit, ensures a small short-circuit current during hard switching short-circuit processes while accelerating the normal turn-on process.

[0060] In a preferred embodiment of the present invention, a driving protection method for silicon carbide devices based on characteristic state current compensation is also provided. The driving protection device based on the present invention includes the following methods:

[0061] By monitoring the turn-on voltage change rate of the silicon carbide device through a drive protection circuit, an injection current positively correlated with the turn-on voltage change rate is generated, and the injection current is input to the gate, including:

[0062] The first terminal is connected to the low-potential power electrode of the silicon carbide device to provide a reference potential.

[0063] The high-potential power electrode of the silicon carbide device is connected via a second terminal to monitor the rate of change of the turn-on voltage.

[0064] The third terminal is connected to the gate of the silicon carbide device via the PWM drive module to ensure that the drive protection circuit works synchronously when the silicon carbide device is turned on.

[0065] The gate of the silicon carbide device is connected via the fourth terminal to inject current into the gate after the turn-on voltage change rate returns at the second terminal.

[0066] The silicon carbide device driving protection method based on characteristic state current compensation of the present invention, and the device based on the present invention, have the same beneficial effects as the device of the present invention.

[0067] In a preferred embodiment of the present invention, a silicon carbide half-bridge is used as an example to analyze common voltage source driving schemes and the scheme of the present invention. See also Figure 3 In a preferred embodiment of the present invention, the silicon carbide half-bridge used for analysis includes a switching transistor. and Bus capacitor and DC power supply ,load Power circuit stray inductance driving resistor and and PWM generator and Assuming the switching transistor and All are SiC MOSFETs.

[0068] DC power supply With bus capacitor and Parallel connection; bus capacitor One end is under load With switching transistor The drain and switching transistor The source terminal is connected, and the other end is connected to the switching transistor. Source connection; bus capacitor One end passes through the stray inductance of the power circuit. With switching transistor The drain is connected, and the other end passes through the load. With switching transistor The drain and switching transistor Source connection; PWM generator One end passes through a driving resistor With switching transistor The gate is connected, and the other end is connected to the switch. Source connection; PWM generator One end passes through a driving resistor With switching transistor The gate is connected, and the other end is connected to the switch. The source is connected; the PWM generator is used to provide switching signals to the switching transistor.

[0069] In a preferred embodiment of the present invention, under normal circumstances, the upper and lower SiC MOSFETs conduct in a complementary manner. If, at a certain moment, the upper MOSFET suddenly turns on while the lower MOSFET turns on due to a signal fault, the current flows directly from the positive terminal of the capacitor through the upper MOSFET and then directly through the lower MOSFET to the negative terminal. At this time, the current rises abnormally rapidly, and the bus voltage is also applied to the MOSFET, causing a short circuit in the switching transistor, i.e., a hard switching short circuit fault occurs.

[0070] (1) In common voltage source type drive schemes:

[0071] Combination Figure 4 Perform a pass-through process analysis:

[0072] Phase 1 ( ): Switching transistor and All are in the off state, load current Flowing Anti-parallel diode, It can withstand the entire bus voltage.

[0073] Phase 2 ( ): time, The activation signal is given. driving voltage From negative pressure It begins to rise gradually, and its upward trend can be expressed as:

[0074] ;

[0075] in, It is driving positive pressure; It is the driving resistance of the device; It is the input capacitance of the device; Indicates time.

[0076] Phase 3 ( ): time, Reaching threshold voltage The load current gradually changes from anti-parallel diode commutation, flow current It gradually increases from zero. Due to stray inductance in the power circuit. The existence of Current change rate leads to drain-source voltage A decline can be specifically expressed as:

[0077] ;

[0078] in, This parameter is used to measure the relationship between the output current of a switching transistor and its drive voltage.

[0079] Phase 4 ( ): At that moment, the converter process was basically completed. At the same time as it begins to bear voltage The voltage across the terminals begins to drop rapidly, which can be specifically expressed as:

[0080] ;

[0081] in, It is the gate-drain capacitance of the device, also known as Miller capacitance.

[0082] Combination Figure 5 Analysis of hard switch short-circuit protection:

[0083] Phase 1 ( ): In a state of discontinuity All are in the through state. It can withstand the entire bus voltage.

[0084] Phase 2 ( ): At that moment, due to a signal failure The activation signal is given. From negative pressure It begins to rise gradually, and its upward trend can be expressed as:

[0085] ;

[0086] Phase 3 ( ): time, Reaching threshold voltage A hard switch short circuit fault occurred. The current flowing through... The current gradually increases from zero due to the stray inductance of the power circuit. The existence of Current change rate leads to The decrease, neglecting the effect of increased device junction temperature, can be specifically expressed as:

[0087] ;

[0088] Phase 4 ( ): time, The shutdown signal is given. Flowing through The current gradually decreases to zero, and the short-circuit current is interrupted. Overshoot can be specifically represented as:

[0089] ;

[0090] The above analysis shows that the driving resistance of the device It affects the normal turn-on speed of the device (switching loss) and the magnitude of the hard-switching short-circuit current. The smaller the value, the faster the turn-on speed and the lower the turn-on loss, but the larger the hard-switching short-circuit current. Common voltage source drives need to strike a trade-off between turn-on speed (turn-on loss) and hard-switching short-circuit current, which is difficult to optimize further.

[0091] (2) In the present invention:

[0092] First of all Figure 3 The drive circuit consisting of the drive resistor and PWM generator in the original circuit is replaced with the drive protection circuit of this invention.

[0093] Combination Figure 6 Perform a pass-through process analysis:

[0094] Phase 1 ( ): Switching transistor and All are in the off state, load current Flowing Anti-parallel diode, It can withstand the entire bus voltage.

[0095] Phase 2 ( ): time, The activation signal is given. driving voltage From negative pressure It begins to rise gradually, and its upward trend can be expressed as:

[0096] ;

[0097] in It is driving positive pressure; It is the driving resistance of the device; It is the input capacitance of the device; Indicates time.

[0098] Phase 3 ( ): time, Reaching threshold voltage The load current gradually changes from anti-parallel diode commutation, flow current It gradually increases from zero. Because... When in the ON state, the P-channel MOSFET When the source potential difference between the gate and the source is less than the turn-on threshold voltage, the source to drain state exhibits a high resistance state, which is controlled by a DC power supply. It generates current and is supplied by a DC power source. PNP transistor and and resistance and The injected current output by the mirror current source After diode The current flows into the gate of the switching transistor, thereby accelerating the switching process. The turn-on process. However, due to the rate of change of the turn-on voltage at this time... The effect is not obvious, so the generated current is small. Due to the turn-on voltage change rate feedback injection, the switching transistor in the turn-on state can be obtained. Compensated driving voltage and rate of change of current The expressions are as follows:

[0099] ;

[0100] in, Indicates the driving resistance; Indicates the input capacitance of the device; Indicates the drain-source voltage; This represents the parasitic inductance of the circuit; The proportional gain represents the current source mirror, specifically in the drive protection circuit. .

[0101] Phase 4 ( ): At that moment, the converter process was basically completed. At the same time as it begins to bear voltage The voltage across the terminals begins to drop rapidly, which can be specifically expressed as:

[0102] ;

[0103] in, It is the load current. It is the gate-drain capacitance of the device, also known as Miller capacitance.

[0104] Because at this time the switching transistor If it is still in the commissioning phase, then the P-channel MOSFET... When the source potential difference between the gate and the source is less than the turn-on threshold voltage, the source to drain state exhibits a high resistance state, which is controlled by a DC power supply. It generates current and is supplied by a DC power source. PNP transistor and and resistance and The injected current output by the mirror current source Still passing through diodes The current flows into the gate of the switching transistor to accelerate the turn-on process. At this time, due to the rate of change of the turn-on voltage... If the change is significant, then the generated current Larger.

[0105] Combination Figure 7 Analysis of hard switch short-circuit protection:

[0106] Phase 1 ( ): In a state of discontinuity All are in the through state. It can withstand the entire bus voltage.

[0107] Phase 2 ( ): At that moment, due to a signal failure The activation signal is given. From negative pressure It begins to rise gradually, and its upward trend can be expressed as:

[0108] ;

[0109] Phase 3 ( ): time, Reaching threshold voltage A hard switch short circuit fault occurred. The current flowing through... The current gradually increases from zero due to the stray inductance of the power circuit. The existence of Current change rate leads to A decrease occurs, at which point due to the switching transistor The P-channel MOSFET is in the ON state. The drain and source are turned off.

[0110] DC power supply PNP transistor and and resistance and The injected current output by the mirror current source Through diode Flow into the switching transistor The gate. At this time, the rate of change of the turn-on voltage. The change in turn-on voltage is small and not obvious, and the rate of change increases with the duration of the short circuit. It will decay, which will cause the injected current to be generated. It also decays accordingly. Ignoring the effect of increased junction temperature, this can be specifically expressed as:

[0111] ;

[0112] Phase 4 ( ): time, The shutdown signal is given. Flowing through The current gradually decreases to zero, and the short-circuit current is interrupted. Overshoot can be specifically represented as:

[0113] ;

[0114] Because the turn-on voltage change rate (dv / dt) feedback injection circuit increases the current change rate (di / dt) and the turn-on voltage change rate (dv / dt) during the normal turn-on process of the device, especially the turn-on voltage change rate (dv / dt), a larger turn-on resistor can be selected while ensuring consistent losses with conventional voltage source drive operation. However, the turn-on voltage change rate (dv / dt) feedback injection circuit has limited impact on the short-circuit current under hard-switching short-circuit conditions. Therefore, the present invention uses a larger turn-on resistor, which can reduce the short-circuit current by comparison.

[0115] In the extreme case, the leakage inductance of the main circuit is zero, so the current change rate di / dt is no longer affected by the feedback injection circuit of the turn-on voltage change rate dv / dt. If the turn-on voltage change rate of the device is guaranteed under conventional voltage source drive and the scheme of this invention...dv / dt The latter method uses a smaller on-resistance, and the rate of change of current di / dt during a short circuit is completely controlled by the on-resistance. Therefore, the short-circuit current under the latter's influence is smaller, and the device can withstand a longer short-circuit time. This also makes it applicable to all converters with hard-switching processes, such as DC / DC converters and DC / AC converters. The solution of this invention can reduce the hard-switching short-circuit current.

[0116] See Figure 8 and Figure 9 , Figure 8 The waveform at 22.4µs is shown when the switching transistor is turned on without the drive protection circuit of this invention. Figure 9 The waveform of the switching transistor turn-on process at 22.4µs is shown when the drive protection circuit of this invention is present. (Curve) For switching transistors S The drain-source voltage waveform of 1, curve For switching transistors S The drain-source voltage waveform of 2, curve For the flow through the switching transistor S The current waveform and curve of 1. For switching transistors S The gate-source voltage of 1 is the driving voltage waveform. (From...) Figure 8 and Figure 9 It can be seen that during the turn-on process of the switching transistor, the rate of change of the turn-on voltage dv / dt between the drain and source of the switching transistor is faster with the driving protection circuit of the present invention than without the driving protection circuit of the present invention. That is, the driving protection circuit of the present invention can accelerate the turn-on of the switching transistor.

[0117] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silicon carbide device drive protection device based on characteristic state current compensation, wherein the silicon carbide device includes a low-potential power electrode, a high-potential power electrode, and a gate electrode; characterized in that, The device includes a drive protection circuit and a PWM drive module; the drive protection circuit includes a first terminal, a second terminal, a third terminal, and a fourth terminal; The drive protection circuit is used to monitor the turn-on voltage change rate of the silicon carbide device, generate an injection current that is positively correlated with the turn-on voltage change rate, and input the injection current to the gate; the first terminal is connected to the low potential power electrode to provide a reference potential; The second terminal is connected to the high-potential power electrode to monitor the turn-on voltage change rate; the third terminal is connected to the gate through the PWM drive module to ensure that the drive protection circuit works synchronously when the silicon carbide device is turned on; the fourth terminal is connected to the gate to input the injection current to the gate after the second terminal returns the turn-on voltage change rate. The drive protection circuit includes a DC power supply. PNP transistor and P-channel MOSFET ,resistance , and ,capacitance and diodes ; DC power supply The negative terminal of the PNP transistor is connected to the first terminal; and The base of the PNP transistor is connected to the base. The emitter is connected to a resistor Connect to DC power supply The positive electrode, the collector is through the diode. Connected to the fourth terminal; PNP transistor The emitter is connected to a resistor Connect to DC power supply The positive electrode, the collector is connected to the capacitor. Connected to the second terminal; P-channel MOSFET The source is connected to a DC power supply. The positive terminal and the drain terminal are connected to the PNP transistor. The collector and base, and the gate are connected by a resistor. Connect to the third terminal.

2. The silicon carbide device drive protection device based on characteristic state current compensation according to claim 1, characterized in that, The PWM drive module includes a PWM generator and a drive resistor; The third terminal is connected to the output terminal of the PWM generator, the output terminal of the PWM generator is connected to the gate through the driving resistor, and the other end of the PWM generator is connected to the low-potential power electrode; the PWM generator is used to provide switching signals for the silicon carbide device.

3. The silicon carbide device drive protection device based on characteristic state current compensation according to claim 2, characterized in that, The step of ensuring that the drive protection circuit operates synchronously when the silicon carbide device is turned on includes: When the silicon carbide device is in the off state, the P-channel field-effect transistor... The source-gate potential difference is greater than the turn-on threshold voltage, resulting in a low-resistance state from source to drain. The turn-on voltage change rate passes through the capacitor. The resulting displacement current flows into the P-channel MOSFET. or P-channel MOSFET In an anti-parallel diode, when the rate of change of the turn-on voltage is positive, the displacement current flows into the P-channel MOSFET. When the rate of change of the turn-on voltage is negative, the displacement current flows into the P-channel MOSFET. The anti-parallel diode; the drive protection circuit stops working.

4. The silicon carbide device drive protection device based on characteristic state current compensation according to claim 3, characterized in that, The method of ensuring that the drive protection circuit operates synchronously when the silicon carbide device is turned on also includes: When the silicon carbide device is in the ON state, the P-channel field-effect transistor... The source-gate potential difference is less than the turn-on threshold voltage, resulting in a high-resistance state from source to drain. The rate of change of the turn-on voltage is reduced by the capacitance. The resulting displacement current flows into the PNP transistor. and or P-channel MOSFET In an anti-parallel diode, when the rate of change of the turn-on voltage is positive, displacement current flows into the PNP transistor. and When the rate of change of the turn-on voltage is negative, the displacement current flows into the P-channel MOSFET. The anti-parallel diodes; the drive protection circuit starts working.

5. The silicon carbide device drive protection device based on characteristic state current compensation according to claim 4, characterized in that, After the rate of change of the turn-on voltage returns at the second terminal, the injected current is input to the gate, including: When the second terminal returns the rate of change of the turn-on voltage, the DC power supply It generates current and is supplied by a DC power source. PNP transistor and and resistance and The output of the mirror current source is transmitted through a PNP transistor. The collector passes through the diode Inject current into the gate input of a silicon carbide device.

6. A method for driving and protecting silicon carbide devices based on characteristic state current compensation, wherein the driving and protection device according to any one of claims 1 to 5 is characterized in that, The method includes: The drive protection circuit monitors the turn-on voltage change rate of the silicon carbide device, generates an injection current positively correlated with the turn-on voltage change rate, and inputs the injection current to the gate, including: The first terminal is connected to the low-potential power electrode of the silicon carbide device to provide a reference potential; The high-potential power electrode of the silicon carbide device is connected via the second terminal to monitor the rate of change of the turn-on voltage; The third terminal is connected to the gate of the silicon carbide device via the PWM drive module to ensure that the drive protection circuit works synchronously when the silicon carbide device is turned on. The gate of the silicon carbide device is connected via the fourth terminal to input the injected current to the gate after the turn-on voltage change rate returns at the second terminal.

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