A driving circuit for parallel use of silicon carbide MOS tubes

Abstract

The utility model provides a driving circuit for parallel use of silicon carbide MOS tubes, which at least includes: a control signal circuit, a signal amplification circuit, an overcurrent protection circuit, and multiple groups of MOS tube driving protection circuits, and the MOS tube driving protection circuit is composed of a gate driving circuit, a silicon carbide MOS tube, a suppression circuit, and an overvoltage protection circuit. This solution uses the overcurrent protection circuit, the suppression circuit, and the overvoltage protection circuit to control the voltage and current of the silicon carbide MOS tube during operation, so as to avoid the inconsistency of voltage and current borne by different devices when the silicon carbide MOS tubes are used in parallel, thereby improving the service life and reliability of the device.

Description

Technical Field

[0001] The utility model relates to the technical field of power conversion circuits, in particular to a driving circuit for parallel use of silicon carbide MOS tubes. Background Art

[0002] Currently, silicon carbide field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) are commonly used as core devices for power conversion to achieve conversion from DC to AC.

[0003] The existing application environment of silicon carbide MOS tubes is single-tube use, specifically, the output capacity of the system is increased by using silicon carbide MOS tubes in parallel; however, since the electrical parameters of each silicon carbide MOS tube are inconsistent, when silicon carbide MOS tubes are used in parallel, the voltage and current borne by different devices will be inconsistent, thereby shortening the service life of the device and reducing the reliability of the device. Utility Model Content

[0004] In view of this, an embodiment of the utility model provides a driving circuit for parallel use of silicon carbide MOS tubes to solve the problem that when silicon carbide MOS tubes are used in parallel, the voltage and current borne by different devices are inconsistent.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The embodiment of the utility model provides a driving circuit for parallel use of silicon carbide MOS tubes, and the driving circuit for parallel use of silicon carbide MOS tubes at least includes: a control signal circuit, a signal amplification circuit, an overcurrent protection circuit, and multiple groups of MOS tube driving protection circuits;

[0007] The output end of the control signal circuit is connected to the input pin of the signal amplification circuit;

[0008] The output pins of the signal amplifying circuit are respectively connected to the input ends of the multiple groups of MOS tube driving protection circuits, and the output pins of the signal amplifying circuit are connected to the output end of the overcurrent protection circuit;

[0009] The overcurrent protection circuit is connected in parallel with multiple groups of MOS tube driving protection circuits;

[0010] The MOS tube driving protection circuit is composed of a gate driving circuit, a silicon carbide MOS tube, a suppression circuit and an overvoltage protection circuit.

[0011] Preferably, for each group of the gate drive circuit, silicon carbide MOS tube, suppression circuit and overvoltage protection circuit in the MOS tube drive protection circuit, the output pin of the signal amplification circuit is connected to the input end of the gate drive circuit;

[0012] The output end of the gate drive circuit, the suppression circuit, and the overvoltage protection circuit are respectively connected to the silicon carbide MOS tube;

[0013] The overcurrent protection circuit is connected in parallel with the silicon carbide MOS tube and the gate drive circuit.

[0014] Preferably, the suppression circuit is a Miller clamp circuit.

[0015] Preferably, it also includes: a driving power supply circuit;

[0016] The driving power supply circuit is connected to the power supply pin of the signal amplifying circuit.

[0017] Preferably, the signal amplifying circuit is a driver chip signal amplifying circuit.

[0018] Preferably, the control signal circuit is a pulse width modulation (PWM) control signal circuit.

[0019] Preferably, the output positive voltage of the driving power circuit is a first voltage, the output negative voltage of the driving power circuit is a second voltage, and the absolute values ​​of the first voltage and the second voltage are different.

[0020] Preferably, the first voltage is 18V, and the second voltage is -4.5V.

[0021] Preferably, the driving power circuit is composed of a driving power module, a plurality of capacitors and an inductor.

[0022] Preferably, the driving chip signal amplifying circuit is composed of a driving chip, multiple resistors, multiple capacitors, magnetic beads, multiple diodes, and a voltage regulator tube.

[0023] Based on the above-mentioned embodiment of the utility model, a driving circuit for parallel use of silicon carbide MOS tubes is provided, and the driving circuit for parallel use of silicon carbide MOS tubes at least includes: a control signal circuit, a signal amplification circuit, an overcurrent protection circuit, and multiple groups of MOS tube driving protection circuits; the output end of the control signal circuit is connected to the input pin of the signal amplification circuit; the output pins of the signal amplification circuit are respectively connected to the input ends of multiple groups of MOS tube driving protection circuits, and the output pins of the signal amplification circuit are connected to the output end of the overcurrent protection circuit; the overcurrent protection circuit is connected in parallel with multiple groups of MOS tube driving protection circuits; wherein the MOS tube driving protection circuit is composed of a gate driving circuit, a silicon carbide MOS tube, a suppression circuit, and an overvoltage protection circuit. This solution uses an overcurrent protection circuit, a suppression circuit, and an overvoltage protection circuit to control the voltage and current of the silicon carbide MOS tube during operation, so as to avoid the voltage and current inconsistency of different devices when the silicon carbide MOS tubes are used in parallel, thereby improving the service life and reliability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 A structural diagram of a driving circuit for parallel use of silicon carbide MOS tubes provided in an embodiment of the utility model;

[0026] Figure 2 Another structural diagram of a driving circuit for parallel use of silicon carbide MOS tubes provided by an embodiment of the utility model;

[0027] Figure 3 Another structural diagram of a driving circuit for parallel use of silicon carbide MOS tubes provided by an embodiment of the utility model;

[0028] Figure 4 A principle block diagram of a driving circuit for parallel use of silicon carbide MOS tubes provided in an embodiment of the utility model;

[0029] Figure 5 A schematic diagram of a driver chip signal amplification circuit provided by an embodiment of the utility model;

[0030] Figure 6 The schematic diagram of the silicon carbide double-tube parallel circuit provided by the embodiment of the utility model;

[0031] Figure 7 A schematic diagram of a driving power supply circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0034] The following examples are described with reference to the accompanying drawings. In addition, the examples shown below do not limit the contents of the utility model described in the claims. In addition, all the contents shown in the following examples are not limited to the solutions required as the utility model described in the claims.

[0035] In the field of power electronic converters, metal-oxide-semiconductor field-effect transistors (MOSFET) and insulated-gate bipolar transistors (IGBT) are currently widely used as core devices for power conversion to achieve DC to AC conversion. According to their voltage levels, IGBTs can be divided into three categories: low voltage, medium voltage and high voltage. IGBTs are widely used in rail transportation, smart grids, aerospace, electric vehicles, new energy equipment and other fields.

[0036] However, with the development of electronic power technology, there are now more stringent requirements for the high frequency and miniaturization of power devices. Silicon carbide MOSFET (abbreviated as silicon carbide MOS tube) has also emerged as a new type of power device. Due to the characteristics of high voltage resistance, high operating temperature, short body diode reverse recovery time, and small parasitic capacitance, silicon carbide MOS tubes have been widely used in the field of high frequency and high voltage.

[0037] It should be noted that due to the differences in materials, structures, and manufacturing processes, the electrical parameters of silicon carbide MOS tubes and silicon products are quite different, so new requirements are also put forward for the application environment of silicon carbide MOS tubes. The negative pressure tolerance of silicon carbide MOS tubes is low, and it is necessary to add a negative voltage clamping circuit to avoid fatigue damage caused by long-term negative voltage overshoot. The short-circuit tolerance time of silicon carbide MOS tubes is short, and in practical applications, it is necessary to select a suitable short-circuit detection method to reduce the short-circuit time. The switching speed of silicon carbide MOS tubes is fast, and a higher voltage change rate (dv / dt) and current change rate (di / dt) will be generated during switching, so it is necessary to improve the anti-interference ability of the application circuit. It can be seen from the above research content that the application environment of silicon carbide MOS tubes is more complex.

[0038] The inventors found in their research that the existing silicon carbide MOS tubes are basically used in single-tube applications. When the power and current are higher, IGBT power modules or silicon carbide power modules are selected to ensure the consistency and symmetry of the layout and routing between chips. However, the IGBT switching speed is slow, which limits the application of IGBT in high-frequency situations. At the same time, there is a tailing phenomenon when the IGBT is turned off, which leads to large overall power consumption and severe heat generation. Silicon carbide power modules have the problem of high cost.

[0039] Relatively speaking, the use of silicon carbide MOS tubes in parallel to increase the output capacity of the system can not only solve the problem of high power of IGBT modules and high cost of silicon carbide power modules, but also make full use of the PCB board size for free layout, and the weight and cost of the system are controlled.

[0040] However, the electrical parameters of each silicon carbide MOS tube are inconsistent. When silicon carbide MOS tubes are used in parallel, the voltage and current borne by different devices will be inconsistent, thereby shortening the service life of the device and reducing the reliability of the device. Therefore, the following key requirements exist for the parallel use of silicon carbide MOS tubes:

[0041] 1. The gate turn-on voltage of silicon carbide MOS tube is low, which makes it more susceptible to interference and mis-conduction under high-voltage and high-frequency switching conditions. It is necessary to improve the anti-interference ability of the driving circuit;

[0042] 2. The gate withstand voltage upper limit of silicon carbide MOS tube is low. The gate voltage spike during operation is more likely to cause the gate of the device to break down and be damaged. It is necessary to add a clamping circuit in the driving circuit;

[0043] 3. The switching speed of silicon carbide MOS tubes is fast, and there are differences in the gate parameters between different single tubes. Using them in parallel makes it easier for the gate voltages to affect each other, thus forming gate resonance, which in turn causes abnormal damage to the gate. Therefore, it is necessary to suppress the parallel gate resonance of silicon carbide MOS tubes.

[0044] To solve the above problems, the embodiment of the utility model proposes a driving circuit for parallel use of silicon carbide MOS tubes, which uses an overcurrent protection circuit, a suppression circuit and an overvoltage protection circuit to control the voltage and current of the silicon carbide MOS tubes during operation, so as to avoid the inconsistency of voltage and current borne by different devices when the silicon carbide MOS tubes are used in parallel, thereby improving the service life and reliability of the devices. The embodiments of the utility model are described in detail below through various embodiments.

[0045] See also Figure 1 , shows a structural diagram of a parallel driving circuit for silicon carbide MOS tubes provided by an embodiment of the utility model, and the parallel driving circuit for silicon carbide MOS tubes at least includes: a control signal circuit 100, a signal amplification circuit 200, an overcurrent protection circuit 300, and multiple groups of MOS tube driving protection circuits 400 (for example, having two groups of MOS tube driving protection circuits 400).

[0046] Specifically, the output end of the control signal circuit 100 is connected to the input pin of the signal amplification circuit 200;

[0047] The output pins of the signal amplifying circuit 200 are respectively connected to the input ends of the multiple groups of MOS tube driving protection circuits 400, and the output pins of the signal amplifying circuit 200 are connected to the output end of the overcurrent protection circuit 300;

[0048] The overcurrent protection circuit 300 is connected in parallel with multiple groups of MOS tube driving protection circuits 400;

[0049] Each group of MOS tube driving protection circuits 400 is composed of a gate driving circuit, a silicon carbide MOS tube, a suppression circuit and an overvoltage protection circuit; the gate driving circuit is used to control the on and off of the silicon carbide MOS tube.

[0050] In some specific embodiments, the suppression circuit in each group of MOS tube driving protection circuits 400 is a Miller clamp circuit, and the Miller clamp circuit is used to suppress the crosstalk of the gate voltage of the silicon carbide MOS tube.

[0051] In some specific embodiments, the control signal circuit 100 is a pulse width modulation (PWM) control signal circuit; the PWM control signal circuit inputs the PWM control signal into the signal amplifier circuit 200 to control the switch of the silicon carbide MOS tube, performs shaping and filtering at the front end, and ensures that the control signal input to the back end is stable and reliable.

[0052] In some specific embodiments, the signal amplifier circuit 200 is a driver chip signal amplifier circuit, which is composed of a driver chip, multiple resistors, multiple capacitors, magnetic beads, multiple diodes, and a voltage regulator. The driver chip signal amplifier circuit converts the input small current control signal into a large current silicon carbide MOS tube switch drive signal to meet the fast on-off requirements of the silicon carbide MOS tube.

[0053] exist Figure 1 Based on some embodiments, such as Figure 2 From another structural diagram of a driving circuit for a silicon carbide MOS tube in parallel, it can be seen that for each group of gate driving circuits, silicon carbide MOS tubes, suppression circuits and overvoltage protection circuits in a MOS tube driving protection circuit 400, the output pin of the signal amplification circuit 200 is connected to the input end of the gate driving circuit; the output end of the gate driving circuit, the suppression circuit and the overvoltage protection circuit are respectively connected to the silicon carbide MOS tube; and the overcurrent protection circuit 300 is connected in parallel with the silicon carbide MOS tube and the gate driving circuit.

[0054] That is to say, for each group of MOS tube drive protection circuits 400, the output pin of the signal amplification circuit 200 is connected to the input end of the gate drive circuit in the group of MOS tube drive protection circuits 400; the output end of the gate drive circuit in the group of MOS tube drive protection circuits 400, the suppression circuit, and the overvoltage protection circuit are respectively connected to the silicon carbide MOS tube in the group of MOS tube drive protection circuits 400, and the overcurrent protection circuit 300 is connected in parallel with the silicon carbide MOS tube and the gate drive circuit in the group of MOS tube drive protection circuits 400.

[0055] Among them, the gate drive circuit is connected to the output pin of the driving chip in the signal amplification circuit 200 (driving chip signal amplification circuit), and the other half of the gate drive circuit is connected to the gate and source of the silicon carbide MOS tube; the suppression circuit (such as the Miller clamping circuit) is connected to the gate of the silicon carbide MOS tube and the Miller pin of the driving chip; the overvoltage protection circuit is connected between the gate and the source of the silicon carbide MOS tube.

[0056] The overcurrent protection circuit 300, overvoltage protection circuit, and suppression circuit mentioned above constitute a gate protection circuit; the gate protection circuit is used to perform overvoltage protection, overcurrent protection, and crosstalk suppression on the gate voltage of silicon carbide, thereby reducing the possibility of device failure.

[0057] exist Figure 2 Based on some embodiments, such as Figure 3 As shown in another structural diagram of a driving circuit for parallel use of silicon carbide MOS tubes, the driving circuit for parallel use of silicon carbide MOS tubes further includes: a driving power circuit 500;

[0058] Specifically, the driving power supply circuit 500 is connected to a power supply pin (input / output power supply pin) of the signal amplifier circuit 200 .

[0059] In some specific embodiments, the driving power circuit 500 is composed of a driving power module, a plurality of capacitors, and an inductor. The output positive voltage of the driving power circuit 500 is a first voltage, and the output negative voltage of the driving power circuit 500 is a second voltage. The absolute values ​​of the first voltage and the second voltage are different; wherein one preferred example of the first voltage is 18V, and one preferred example of the second voltage is -4.5V.

[0060] In practical applications, the driving power circuit 500 supplies power to the driving chip and outputs positive and negative voltages to drive the silicon carbide MOS tube. The output negative voltage ensures the shutdown stability and the output positive voltage ensures that the silicon carbide MOS tube can be fully turned on to reduce the conduction power.

[0061] The above is a description of the driving circuit for parallel use of silicon carbide MOS tubes provided in the embodiment of the utility model; in order to better understand the specific structure of the driving circuit for parallel use of silicon carbide MOS tubes, Figure 4 Give an example.

[0062] like Figure 4 It can be seen that the driving circuit for parallel use of silicon carbide MOS tubes includes: a PWM control signal circuit (control signal circuit 100), a driving chip signal amplification circuit (signal amplification circuit 200), an overcurrent protection circuit 300, a driving power supply circuit 500, a gate driving circuit (2), silicon carbide MOS tubes (2, silicon carbide MOS tube 1 and silicon carbide MOS tube 2), Miller clamp circuits (2), and overvoltage protection circuits (2);

[0063] The PWM control signal circuit inputs the PWM control signal into the driver chip signal amplifier circuit to control the switch of the silicon carbide MOS tube, and performs shaping and filtering at the front end to ensure that the control signal input to the back end is stable and reliable.

[0064] The driver chip signal amplification circuit converts the input small current control signal into a large current silicon carbide MOS tube switch drive signal to meet the fast on and off requirements of the silicon carbide MOS tube.

[0065] The driving power circuit 500 supplies power to the driving chip and outputs positive and negative voltages to drive the silicon carbide MOS tube. The output negative voltage ensures the shutdown stability and the output positive voltage ensures that the silicon carbide MOS tube can be fully turned on to reduce the conduction power.

[0066] The overcurrent protection circuit 300, the overvoltage protection circuit, and the Miller clamp circuit constitute a gate protection circuit; the gate protection circuit is used to perform overvoltage protection, overcurrent protection, and crosstalk suppression on the gate voltage of silicon carbide, thereby reducing the possibility of device failure.

[0067] Through the above content, the silicon carbide MOS tube is connected to the main circuit to control the on and off of the main circuit, thereby achieving the ultimate control effect.

[0068] For the above-mentioned driver chip signal amplifying circuit (signal amplifying circuit 200), as Figure 5 As can be seen from the schematic diagram of the driving chip signal amplifying circuit, the driving chip signal amplifying circuit is composed of a driving chip U11, resistors R7-R15, capacitors C11-C18, a magnetic bead B1, diodes D3-D5, and a voltage regulator DZ1.

[0069] Among them, the voltage regulator DZ1, the resistor R8, the diode D4 and the Desat pin of the driver chip U11 constitute a desaturation protection circuit. The DS voltage drop of the silicon carbide MOS tube is positively correlated with the current flowing through it. The detection threshold is set by calculating the voltage drop corresponding to the protection current; when the detection threshold is greater than the protection threshold of the driver chip, a shutdown signal is output to disconnect the main current loop to trigger the protection.

[0070] The 7th pin of the driver chip is the Miller clamp pin, which is connected to the negative voltage through the MOS tube inside the driver chip. When the input signal is OV (i.e., the off state), the MOS tube is turned on, and the Miller clamp pin can be pulled to the negative voltage for clamping, thereby ensuring the stability of the gate signal of the silicon carbide MOS tube during the off moment, thereby avoiding false turn-on action; the driver chip is divided into a primary side of low-voltage power supply and a secondary side of power amplification, thereby realizing the function of switching control of the silicon carbide MOS tube through a small current signal.

[0071] It should be noted that Figure 5 VCC5, VON_UH, DESAT_UH, COM_UH, PWM_UHO, CLAMP_UH, G_UHL, and G_UHH are respectively the power supply, the positive voltage supply of the driver chip, the overcurrent detection signal, the MOS tube drive voltage ground, the PWM control signal, the Miller clamp detection signal, the MOS tube shutdown voltage signal, and the MOS tube turn-on voltage signal.

[0072] Figure 5 U5, U10, and U13 in the figure represent vias, indicating that signals are input from U5, U10, and U13; U10 and U13 are connected to PWM control signals; VCC5, VON_UH, and VOFF_UH are connected to the driving power circuit 500; and G_UHL, G_UHH, and COM_UH are connected to the gate driving circuit.

[0073] For the MOS tube drive protection circuit 400 mentioned above, the gate drive circuit, silicon carbide MOS tube and overvoltage protection circuit in each group of MOS tube drive protection circuit 400 constitute a silicon carbide double tube parallel circuit; Figure 6It can be seen from the schematic diagram of the silicon carbide dual-tube parallel circuit that the silicon carbide dual-tube parallel circuit is composed of silicon carbide MOS tubes Q1-Q2, diodes D1-D2, transient voltage suppression tubes (TVS tubes) U6-U9, resistors R1-R6, and capacitors C9-C10, wherein the two groups of silicon carbide MOS tube circuits are completely independent and controlled separately.

[0074] Figure 6 In the circuit, resistors R1 and R4 are used as separate turn-on and turn-off resistors, which facilitates the separate adjustment of the turn-on and turn-off speeds, and the comprehensive adjustment of the power consumption, oscillation, and overshoot during the turn-on and turn-off processes, thereby obtaining a more balanced performance.

[0075] R1, R4 and R2, R3 are the gate drive resistors of different silicon carbide MOS tubes. The gates of the parallel dual tubes are isolated, and the gate voltages of different silicon carbide MOS tubes can be formed into independent individuals, thereby increasing the damping between the two gates and effectively suppressing the gate resonance between the parallel single tubes.

[0076] Diodes D1 and D2 are arranged near the gate pin of the silicon carbide MOS tube, connecting the gate of the silicon carbide MOS tube and the Miller clamp circuit. Diodes D1 and D2 can provide a low impedance path for the crosstalk current, limit the gate voltage of the silicon carbide MOS tube within the range of the Miller clamp circuit voltage + the diode voltage drop, control the gate voltage rise problem caused by the crosstalk current, and reduce the possibility of false opening; the use of diodes can isolate the gates of the parallel double tubes, thereby preventing the gate current from generating backflow oscillation through this loop.

[0077] It should be noted that the Miller clamp circuit is mainly set in Figure 5 Inside the driver chip U11, the outside of the Miller clamp circuit is diodes D1 and D2.

[0078] TVS tubes U6 and U9 are connected between the gate and source of the silicon carbide MOS tube. The two TVS tubes are placed opposite to each other, which can limit the positive and negative voltage overshoot of the gate. The same is true for U7 and U8, which will not be repeated here. When the positive and negative voltage peaks of the gate voltage exceed the set value of the selected TVS tube, one of the TVS tubes is reversely broken down to instantly form a conduction loop, which leads out the large current at both ends and clamps the voltage at both ends to a predetermined value, ensuring that the gate and source of the silicon carbide MOS tube will not be damaged due to transient high-energy impact, thereby achieving the purpose of protecting the silicon carbide MOS tube.

[0079] It should be noted that in practical applications, Figure 6R1 and R4 in the circuit are used as turn-on and turn-off resistors and should be placed as close to the gate pin of the silicon carbide MOS tube as possible to suppress LC oscillation during normal switching. The specific resistance values ​​of R1 and R4 need to be determined through debugging. The turn-off resistor is generally smaller than the turn-on resistor, which can shorten the turn-off time and reduce the turn-off power consumption.

[0080] Figure 6 R5 in the circuit has the function of pulling down the gate voltage to ensure the gate is stable when no power is supplied. Relative to the gate resistance, the resistance of R5 should be more than 100 times of the gate resistance. This can avoid the problem of low voltage due to resistance division and incomplete opening of the silicon carbide MOS tube, which increases power consumption.

[0081] Figure 6 The capacitor C9 is connected in parallel with the internal input capacitor of the silicon carbide MOS tube. By adjusting C9, the switching rate can be adjusted to control dv / dt and di / dt, thereby affecting the drain-source voltage oscillation and overshoot. On the other hand, increasing C9 can absorb more crosstalk displacement current, reduce the gate voltage rise amplitude, and avoid shoot-through.

[0082] Figure 6 When selecting TVS tubes U6 and U9, the threshold voltage should be determined first. The threshold voltage should exceed the normal operating voltage and be as close to the normal operating voltage as possible. At the same time, the threshold voltage should be less than the gate safety voltage of the silicon carbide MOS tube, so that transient overvoltage can be effectively clamped; in addition, the junction capacitance of the selected TVS tube should be as small as possible, and the selected TVS tube should not affect the circuit function.

[0083] Figure 6 When selecting the diodes D1 and D2, the magnitude of the crosstalk current needs to be considered. The forward transient operating current should be greater than the crosstalk current. At the same time, the forward voltage drop and reverse recovery current should be as small as possible, and the reverse recovery time should be as short as possible to control the gate voltage near the Miller clamping voltage.

[0084] By selecting reasonable functional devices and adopting symmetrical layout and routing, Figure 6 The design of the silicon carbide dual-tube parallel circuit shown can effectively suppress the oscillation of the gate voltage, thereby solving the problem of parallel use of silicon carbide MOS tubes.

[0085] In addition to selecting appropriate models for each component, the layout and routing of the driving circuits of each silicon carbide MOS tube should be as symmetrical as possible, which can also reduce the impact of differences in stray inductance of the routing.

[0086] For the above-mentioned driving power circuit 500, as Figure 7As can be seen from the schematic diagram of the driving power supply circuit, the driving power supply circuit is composed of a driving power supply module U2, capacitors C1-C8, and an inductor L1. The driving power supply module U2 directly outputs a positive voltage of 18V and a negative voltage of -4.5V, turning on the silicon carbide MOS tube with positive voltage and turning off with negative voltage.

[0087] It should be noted that Figure 7 VON_UH, VOFF_UH, and COM_UH are signal names, which are connected to the signal amplification circuit of the driver chip. U1 and U4 mean vias, and DC28P refers to the 28V input power supply.

[0088] Figure 7 C3, C5, L1, C4, and C6 together form a π-type filtering network to suppress high-frequency interference of the power input, and also prevent the interference of the driving power module U2 from being introduced into the outside world; by selecting a combination of filter capacitors with different capacitance values, it can suppress interference in each frequency band.

[0089] Figure 7 The network composed of C1, C2, C7 and C8 is used to suppress power supply output interference. At the same time, since the current required by the silicon carbide MOS tube at the moment of turning on is large, the output voltage stabilizing capacitor also plays the role of providing short-term large current to enhance the output capacity.

[0090] By calculating the amount of charge required by the silicon carbide MOS tube at the switching moment and reproducing the fluctuation range of the power supply output, the appropriate output capacitance value can be obtained. In practical applications, the output capacitance can also be appropriately increased to reduce the power supply ripple.

[0091] Through the above Figure 5-Figure 7 It can be seen from the content that this scheme adds a Miller clamp circuit (that is, the suppression circuit mentioned above) and a filter capacitor to the gate-source loop of the silicon carbide MOS tube, provides a low-impedance loop for the gate crosstalk current during the shutdown period of the device, reduces the rise of the gate voltage, and thus solves the problem of false turn-on of the silicon carbide MOS tube; adds positive and negative voltage clamp circuits near the gate-source pins of the silicon carbide MOS tube, provides a discharge path for the positive and negative voltage overshoots that may be generated at the switching moment, suppresses the short-term spike of the gate voltage, and solves the overvoltage breakdown problem of the silicon carbide MOS tube; arranges a separate gate resistor near the gate of each silicon carbide MOS tube, isolates and decouples the gates between the parallel tubes, weakens the mutual influence of the gate voltages of the parallel tubes, improves the parallel resonance phenomenon of the silicon carbide MOS tube, and increases the reliability of the drive circuit.

[0092] In summary, this solution has the following beneficial effects:

[0093] Add a Miller clamp circuit to suppress the gate voltage crosstalk of the silicon carbide MOS tube when turning off the device, and reduce the risk of direct conduction between the upper and lower tubes; add positive and negative voltage clamp circuits to control the gate voltage range of the silicon carbide MOS tube during operation, avoid the reduction of electrical life caused by long-term gate voltage tolerance, and increase system reliability; use a separate gate drive resistor to suppress the gate resonance between parallel single tubes, and solve the problem of silicon carbide MOS tube failure and damage caused by excessive parallel tube resonance.

[0094] In summary, the embodiments of the utility model provide a driving circuit for parallel use of silicon carbide MOS tubes, which utilizes an overcurrent protection circuit, a suppression circuit, and an overvoltage protection circuit to control the voltage and current of the silicon carbide MOS tubes during operation, thereby avoiding the situation in which different devices are borne inconsistent voltages and currents when the silicon carbide MOS tubes are used in parallel, thereby improving the service life and reliability of the devices.

[0095] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0096] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present utility model.

[0097] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A driving circuit for parallel use of silicon carbide MOS tubes, characterized in that: The driving circuit for parallel use of silicon carbide MOS tubes at least includes: a control signal circuit, a signal amplification circuit, an overcurrent protection circuit, and multiple groups of MOS tube driving protection circuits; The output end of the control signal circuit is connected to the input pin of the signal amplification circuit; The output pins of the signal amplifying circuit are respectively connected to the input ends of the multiple groups of MOS tube driving protection circuits, and the output pins of the signal amplifying circuit are connected to the output end of the overcurrent protection circuit; The overcurrent protection circuit is connected in parallel with multiple groups of MOS tube driving protection circuits; The MOS tube driving protection circuit is composed of a gate driving circuit, a silicon carbide MOS tube, a suppression circuit and an overvoltage protection circuit.

2. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 1, characterized in that: For each group of the gate drive circuit, silicon carbide MOS tube, suppression circuit and overvoltage protection circuit in the MOS tube drive protection circuit, the output pin of the signal amplification circuit is connected to the input end of the gate drive circuit; The output end of the gate drive circuit, the suppression circuit, and the overvoltage protection circuit are respectively connected to the silicon carbide MOS tube; The overcurrent protection circuit is connected in parallel with the silicon carbide MOS tube and the gate drive circuit.

3. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 1 or 2, characterized in that: The suppression circuit is a Miller clamp circuit.

4. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 1 or 2, characterized in that: Also includes: Driving power supply circuit; The driving power supply circuit is connected to the power supply pin of the signal amplifying circuit.

5. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 1, characterized in that: The signal amplifying circuit is a driving chip signal amplifying circuit.

6. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 1, characterized in that: The control signal circuit is a pulse width modulation (PWM) control signal circuit.

7. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 4, characterized in that: The output positive voltage of the driving power circuit is a first voltage, the output negative voltage of the driving power circuit is a second voltage, and the absolute values ​​of the first voltage and the second voltage are different.

8. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 7, characterized in that: The first voltage is 18V, and the second voltage is -4.5V.

9. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 4, characterized in that: The driving power circuit is composed of a driving power module, a plurality of capacitors and an inductor.

10. The driving circuit for parallel use of silicon carbide MOS tubes according to claim 5, characterized in that: The driving chip signal amplifying circuit is composed of a driving chip, a plurality of resistors, a plurality of capacitors, a magnetic bead, a plurality of diodes and a voltage regulator tube.

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