SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler

Abstract

The invention discloses a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler, and the circuit obtains an output signal of a switch control module according to a drive module, generates a control signal PWM signal of an electrical isolation module, generates a drive signal of a rapid discharge module through the electrical isolation module, adjusts the connection and disconnection of the rapid discharge module based on the control signal, and improves the crosstalk suppression efficiency. Circuit voltage is adjusted, and safety and stability of high-voltage and low-voltage parts are protected; and the Miller current is discharged through the rapid discharge module, so that the oscillation phenomenon in the switching process is reduced. Through cooperative work of the modules, the whole process from power supply to signal transmission and control is ensured to be optimized, grid crosstalk oscillation is suppressed, and the performance and reliability of the system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optical coupler. Background Art

[0002] SiC-MOSFET (Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor) is gradually replacing traditional IGBT in the miniaturization and high-frequency design of power conversion equipment due to its excellent high-frequency and high-temperature performance. However, the high-speed switching capability of SiC-MOSFET is prone to cause crosstalk oscillation in the gate-source voltage of the device, resulting in undue fluctuations in the gate-source voltage, which may cause the device to be turned on or off incorrectly, thereby increasing the risk of system failure. In order to avoid the negative impact of crosstalk oscillation, designers may have to sacrifice part of the high-speed switching performance of SiC-MOSFET, reduce its switching frequency or increase the buffer time during the switching process.

[0003] Existing crosstalk oscillation suppression methods reduce the possibility of crosstalk oscillation triggering device mis-conduction by reducing parasitic inductance, reducing device turn-on speed, and adding a fast discharge path for Miller current (charging current of Miller capacitor of device). Reducing inductance requires repeated optimization of PCB layout to minimize parasitic inductance, which is time-consuming; reducing device turn-on speed will increase device power loss, and adding a fast discharge path for Miller current is only applicable to devices with 0V turn-off condition. For devices with negative turn-off condition, this method does not work. Summary of the invention

[0004] The present invention provides a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optical coupler, so as to suppress the gate crosstalk oscillation phenomenon of a power device without affecting the switching speed of the device and applying a negative voltage to turn off the device.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler, including: a power module, a drive module, an electrical isolation module, a fast discharge module and a switch control module;

[0006] The power module is electrically connected to the driving module, the electrical isolation module and the fast discharge module;

[0007] The driving module is electrically connected to the electrical isolation module and the switch control module;

[0008] The electrical isolation module is electrically connected to the fast discharge module;

[0009] The fast discharge module is electrically connected to the switch control module.

[0010] The present invention obtains the output signal of the switch control module according to the driving module to generate the control signal PWM signal of the electrical isolation module, so as to generate the driving signal of the fast discharge module through the electrical isolation module, adjust the on and off of the fast discharge module based on the control signal, adjust the circuit voltage, and protect the safety and stability of the high-voltage and low-voltage parts; and discharge the Miller current through the fast discharge module to reduce the oscillation phenomenon during the switching process. Through the coordinated work between the various modules, the whole process from power supply to signal transmission and control is optimized, the gate crosstalk oscillation is suppressed, and the performance and reliability of the system are improved.

[0011] Further, the power module includes a first power interface, a second power interface, a third power interface, a fourth power interface and a fifth power interface;

[0012] The driving module is electrically connected to the first power interface, the second power interface, the third power interface and the fourth power interface respectively;

[0013] The electrical isolation module is electrically connected to the second power interface, the third power interface, the fourth power interface and the fifth power interface respectively.

[0014] Furthermore, the electrical isolation module includes a high-speed optical coupler, a first voltage divider module and a second voltage divider module;

[0015] The input end of the high-speed optical coupler is electrically connected to the driving module, and the output end of the high-speed optical coupler is electrically connected to the fast discharge module;

[0016] The first end of the first voltage dividing module is electrically connected to the second power interface and the fifth power interface, and the second end of the first voltage dividing module is electrically connected to the fast discharge module;

[0017] The first end of the second voltage dividing module is electrically connected to the second power interface and the fourth power interface, and the second end of the second voltage dividing module is electrically connected to the fast discharge module.

[0018] Further, the fast discharge module includes: a first triode, a second triode and a first switch control element;

[0019] The emitter of the first transistor is electrically connected to the emitter of the second transistor and the first end of the first switch control element;

[0020] The collector of the first transistor is electrically connected to the collector of the second transistor and the first end of the second voltage divider module;

[0021] The base of the first transistor is electrically connected to the second end of the first voltage dividing module;

[0022] The base of the second transistor is electrically connected to the second end of the second voltage dividing module;

[0023] The second end of the first switch control element is electrically connected to the output end of the high-speed optical coupler; the third end of the first switch control element is electrically connected to the switch control module and the driving module.

[0024] Further, the first transistor is a PNP transistor, and the second transistor is an NPN transistor;

[0025] The emitter of the PNP transistor is electrically connected to the emitter of the NPN transistor and the first end of the first switch control element;

[0026] The collector of the PNP transistor is electrically connected to the collector of the NPN transistor and the first end of the second voltage divider module;

[0027] The base of the PNP transistor is electrically connected to the second end of the first voltage dividing module;

[0028] The base of the NPN transistor is electrically connected to the second end of the second voltage dividing module.

[0029] Furthermore, the first switch control element is an NMOS tube;

[0030] The source of the NMOS transistor is electrically connected to the emitter of the PNP transistor and the collector of the NPN transistor;

[0031] The gate of the NMOS tube is electrically connected to the output end of the high-speed optical coupler;

[0032] The drain of the NMOS tube is electrically connected to the switch control module.

[0033] Further, the switch control module includes a second switch control element;

[0034] The first end of the second switch control element is connected to the driving module; the second end of the second switch control element is electrically connected to the third end of the first switch control element and the driving module.

[0035] Further, the second switch control element includes a SiC-MOSFET;

[0036] The source and driving module of the SiC-MOSFET;

[0037] The gate of the SiC-MOSFET is electrically connected to the third end of the first switch control element and the driving module.

[0038] Furthermore, the first voltage dividing module includes a first resistor and a second resistor; the second voltage dividing module includes a third resistor and a fourth resistor;

[0039] The first end of the first resistor is electrically connected to the second power interface; the first end of the second resistor is electrically connected to the fifth power interface; the second end of the first resistor is electrically connected to the second end of the second resistor and the fast discharge module;

[0040] The first end of the third resistor is electrically connected to the second power interface; the first end of the fourth resistor is electrically connected to the fourth power interface; the second end of the third resistor is electrically connected to the second end of the fourth resistor and the fast discharge module.

[0041] Furthermore, the high-speed optical coupler includes a light emitting diode and a phototransistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of a module of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the structure of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided by the present invention;

[0044] Figure 3 An operation mode structure diagram provided for an embodiment of the present invention;

[0045] Figure 4 Another operation mode structure diagram provided for an embodiment of the present invention;

[0046] Figure 5 A schematic diagram of the topological structure of some modules of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided in an embodiment of the present invention;

[0047] Figure 6 An oscillation suppression effect diagram of an original driving circuit provided by an embodiment of the present invention;

[0048] Figure 7 A diagram showing the oscillation suppression effect of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided in an embodiment of the present invention;

[0049] Figure 8 A schematic diagram of a switching waveform of an original driving circuit provided by an embodiment of the present invention;

[0050] Fig. 9 A schematic diagram of switching waveforms of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0052] The terms "first" and "second" and the like in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0053] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0054] Example 1

[0055] See also Figure 1 , Figure 1 The module schematic diagram of the SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler provided in the embodiment of the present invention. The embodiment of the present invention provides a SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler, including: a power module, a drive module, an electrical isolation module, a fast discharge module and a switch control module;

[0056] The power supply module is electrically connected to the driving module and the electrical isolation module;

[0057] The driving module is electrically connected to the electrical isolation module and the switch control module;

[0058] The electrical isolation module is electrically connected to the fast discharge module;

[0059] The fast discharge module is electrically connected to the switch control module.

[0060] In this embodiment, the power module is electrically connected to the driving module, the electrical isolation module and the fast discharge module to provide the necessary voltage and current to provide a stable working power supply for each module in the circuit and ensure the reliable operation of the overall circuit; the driving module is electrically connected to the electrical isolation module and the switch control module, which is used to generate a PWM control signal, and drive and control the conduction and disconnection of the remaining modules based on the PWM control signal; the electrical isolation module is electrically connected to the fast discharge module, and electrical isolation is achieved through the high-speed optical coupler in the electrical isolation module to ensure that the PWM signal is accurately transmitted to the gate of the switch control element. At the same time, noise and interference are suppressed to protect the safety and stability of the high-voltage and low-voltage parts; the fast discharge module is electrically connected to the switch control module, which is a fast discharge path of the Miller current, mainly composed of NMOSFET (S1), PNP transistor (S2) and NPN transistor (S3), to ensure that excess charge can be quickly released during the switching process, thereby reducing oscillation; the switch control module is used to control the switching operation of the SiC-MOSFET, integrate the signals of each module, accurately control the switching state of the SiC-MOSFET, and ensure that it works stably under high frequency and high efficiency conditions.

[0061] In this embodiment, the control signal PWM signal of the electrical isolation module is generated according to the output signal of the switch control module obtained by the driving module, so as to generate the driving signal of the fast discharge module through the electrical isolation module, and adjust the on and off of the fast discharge module based on the control signal, adjust the circuit voltage, and protect the safety and stability of the high-voltage and low-voltage parts; and discharge the Miller current through the fast discharge module to reduce the oscillation phenomenon during the switching process. Through the coordinated work between the various modules, the whole process from power supply to signal transmission and control is optimized, the gate crosstalk oscillation is suppressed, and the performance and reliability of the system are improved.

[0062] In this embodiment, the power module includes a first power interface, a second power interface, a third power interface, a fourth power interface and a fifth power interface;

[0063] The driving module is electrically connected to the first power interface, the second power interface, the third power interface and the fourth power interface respectively;

[0064] The electrical isolation module is electrically connected to the second power interface, the third power interface, the fourth power interface and the fifth power interface respectively.

[0065] In this embodiment, the power module includes five power interfaces, each of which outputs a different voltage. Specifically, the first power interface outputs a voltage of +15V, the second power interface outputs a voltage of 0V, the third power interface outputs a voltage of -4V, the fourth power interface outputs a voltage of -4V, and the fifth power interface outputs a voltage of -5V.

[0066] In this embodiment, different voltage values ​​are output through different power supply interfaces to provide stable working power for each module, thereby ensuring reliable operation of the overall circuit.

[0067] In this embodiment, the driving module is electrically connected to the electrical isolation module and the switch control module, and the driving module is used to output the PWM control signal of the switch control module to the electrical isolation module, so that the electrical isolation module generates a first driving signal according to the PWM control signal, wherein the first driving signal is a control signal of the fast discharge module.

[0068] In this embodiment, the driving module includes one or more driving chips, wherein the input end of the driving chip is electrically connected to the output end of the power module and the switch control module, and the output end of the driving module is electrically connected to the input end of the fast discharge module and the input end of the switch control module.

[0069] In this embodiment, the electrical isolation module includes a high-speed optical coupler, a first voltage divider module and a second voltage divider module;

[0070] The input end of the high-speed optical coupler is electrically connected to the driving module, and the output end of the high-speed optical coupler is electrically connected to the fast discharge module;

[0071] The first end of the first voltage dividing module is electrically connected to the second power interface and the fifth power interface, and the second end of the first voltage dividing module is electrically connected to the fast discharge module;

[0072] The first end of the second voltage dividing module is electrically connected to the second power interface and the fourth power interface, and the second end of the second voltage dividing module is electrically connected to the fast discharge module.

[0073] In this embodiment, a high-speed optocoupler (Optocoupler or Optical Isolator) is a device used for electrical isolation, which transmits information through optical signals and is usually used to transmit a control signal of a circuit from one part to another without directly connecting them, thereby achieving electrical isolation.

[0074] In this embodiment, the high-speed optical coupler includes a light emitting diode and a phototransistor.

[0075] In this embodiment, the input end of the high-speed optical coupler is connected to the driving module, the PWM control signal generated by the driving module is obtained, and the first driving signal con1 is generated based on the PWM control signal, and the first driving signal con1 is input into the fast discharge module.

[0076] In this embodiment, the first voltage dividing module and the second voltage dividing module are electrically connected to the power supply module to output different voltage values, and input the voltage values ​​into the fast discharge module as driving signals.

[0077] In this embodiment, the first voltage dividing module includes a first resistor and a second resistor; the second voltage dividing module includes a third resistor and a fourth resistor;

[0078] The first end of the first resistor is electrically connected to the second power interface; the first end of the second resistor is electrically connected to the fifth power interface; the second end of the first resistor is electrically connected to the second end of the second resistor and the fast discharge module;

[0079] The first end of the third resistor is electrically connected to the second power interface; the first end of the fourth resistor is electrically connected to the fourth power interface; the second end of the third resistor is electrically connected to the second end of the fourth resistor and the fast discharge module.

[0080] In this embodiment, the first voltage dividing module is used to output the second driving signal con2, and the second voltage dividing module is used to output the third driving signal con3.

[0081] In this embodiment, in the first voltage divider module, the first resistor is electrically connected to the second power interface, and its input voltage is 0V; the second resistor is electrically connected to the fifth power interface, and its input voltage is -5V. After voltage division by the first resistor and the second resistor, the second drive signal con2 is obtained.

[0082] In this embodiment, in the second voltage divider module, the third resistor is electrically connected to the second power supply interface, and its input voltage is 0V; the fourth resistor is electrically connected to the fast discharge module, and the input voltage is obtained based on the fast discharge module; based on the voltage division of the third resistor and the fourth resistor, the third drive signal con3 is obtained.

[0083] In this embodiment, the first resistor and the second resistor are set based on a preset first resistance ratio; the third resistor and the fourth resistor are set based on a preset second resistance ratio.

[0084] In an optional embodiment, the resistance ratio of the first resistor to the second resistor is 49: 1. According to the resistor voltage division principle, the second driving signal con2 is -4.9V.

[0085] In this embodiment, the electrical isolation module is used to generate a driving signal for the fast discharge module, including a first driving signal con1, a second driving signal con2 and a third driving signal con3, and adjust the conduction and disconnection of the components in the fast discharge module according to the first driving signal con1, the second driving signal con2 and the third driving signal con3.

[0086] In an optional embodiment, the ratio of the third resistor to the fourth resistor is 31:9.

[0087] In this embodiment, the fast discharge module includes: a first triode, a second triode and a first switch control element;

[0088] The emitter of the first transistor is electrically connected to the emitter of the second transistor and the first end of the first switch control element;

[0089] The collector of the first transistor is electrically connected to the collector of the second transistor and the first end of the second voltage divider module;

[0090] The base of the first transistor is electrically connected to the second end of the first voltage dividing module;

[0091] The base of the second transistor is electrically connected to the second end of the second voltage dividing module;

[0092] The second end of the first switch control element is electrically connected to the output end of the high-speed optical coupler; the third end of the first switch control element is electrically connected to the switch control module and the driving module.

[0093] In this embodiment, the first transistor is a PNP transistor, and the second transistor is an NPN transistor;

[0094] The emitter of the PNP transistor is electrically connected to the emitter of the NPN transistor and the first end of the first switch control element;

[0095] The collector of the PNP transistor is electrically connected to the collector of the NPN transistor and the first end of the second voltage divider module;

[0096] The base of the PNP transistor is electrically connected to the second end of the first voltage dividing module;

[0097] The base of the NPN transistor is electrically connected to the second end of the second voltage dividing module.

[0098] In this embodiment, the first switch control element is an NMOS tube;

[0099] The source of the NMOS transistor is electrically connected to the emitter of the PNP transistor and the collector of the NPN transistor;

[0100] The gate of the NMOS tube is electrically connected to the output end of the high-speed optical coupler;

[0101] The drain of the NMOS tube is electrically connected to the switch control module.

[0102] In this embodiment, a fast discharge path provided by the Miller current is formed by two three-level transistors and a switch control element.

[0103] In this embodiment, the output end of the first voltage divider module is connected to the base of the PNP transistor, and the second drive signal con2 is used as the base signal of the PNP transistor; the output end of the second voltage divider module is connected to the base of the NPN transistor, and the third drive signal con3 is used as the base signal of the NPN transistor; the output end of the high-speed optocoupler is connected to the gate of the NMOS tube, and the first drive signal con1 is used as the gate signal of the NMOS tube.

[0104] In this embodiment, in the fast discharge module, the combination of the NMOSFET, the PNP transistor and the NPN transistor provides a fast discharge path for discharging the Miller current and reducing the oscillation phenomenon during the switching process.

[0105] In this embodiment, the switch control module includes a second switch control element;

[0106] The first end of the second switch control element is connected to the driving module; the second end of the second switch control element is electrically connected to the third end of the first switch control element and the driving module.

[0107] In this embodiment, the second switch control element includes a SiC-MOSFET;

[0108] The source and driving module of the SiC-MOSFET;

[0109] The gate of the SiC-MOSFET is electrically connected to the third end of the first switch control element and the driving module.

[0110] In this embodiment, the opening and closing of the Miller current discharge channel in the fast discharge module of the drive signal is generated by the state of the SiC-MOSFET, and based on the output of the SiC-MOSFET, the first drive signal con1, the second drive signal con2 and the third drive signal con3 are generated via the drive module and the electrical isolation module, and the conduction and disconnection of the elements in the fast discharge module are adjusted according to the first drive signal con1, the second drive signal con2 and the third drive signal con3 to realize the opening and closing of the Miller current discharge channel.

[0111] The embodiment of the present invention further provides a control method for a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler, which is applied to the SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler, and includes:

[0112] A first voltage is obtained based on the second terminal of the switch control module, and the on and off of the fast discharge module is adjusted based on the first voltage. Specifically:

[0113] When the first voltage is greater than a preset voltage threshold, obtaining a first base signal based on the first voltage divider module, and turning on the PNP transistor based on the first base signal to reduce the first voltage;

[0114] When the first voltage is less than a preset voltage threshold, a second base signal is acquired based on the second voltage divider module, and the NPN transistor is turned on based on the second base signal to increase the first voltage.

[0115] In this embodiment, the first voltage is the voltage at the gate of the NOMS tube in the switch control module.

[0116] Please refer to Figure 2 , Figure 2 A schematic structural diagram of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided by the present invention.

[0117] In this embodiment, the power supply module includes a first power supply interface, a second power supply interface, a third power supply interface, a fourth power supply interface and a fifth power supply interface. The output voltage of the first power supply interface is +15V, the output voltage of the second power supply interface is 0V, the output voltage of the third power supply interface is -4V, the output voltage of the fourth power supply interface is -4V, and the output voltage of the fifth power supply interface is -5V.

[0118] In this embodiment, the driving module includes a driving chip, which is electrically connected to the power module and the switch control module, generates a PWM control signal by acquiring an output signal of the switch control module, and inputs the PWM control signal into the electrical isolation module.

[0119] In this embodiment, the input voltage of the driving module includes +15V, 0V and -4V, and the output thereof is a PWM control signal.

[0120] In this embodiment, the electrical isolation module includes a high-speed optical coupler, a first voltage divider module and a second voltage divider module, wherein the high-speed optical coupler includes a light emitting diode and a photodetector. The light emitting diode receives a PWM signal generated by a driving signal, and generates a light signal of corresponding intensity based on the signal, so that the photodetector receives the light signal and converts the light signal into an electrical signal.

[0121] In an alternative embodiment, the photodetector is a phototransistor.

[0122] In this embodiment, in the first voltage divider module, the first resistor is electrically connected to the second power interface, and its input voltage is 0V; the second resistor is electrically connected to the fifth power interface, and its input voltage is -5V. After voltage division by the first resistor and the second resistor, the second drive signal con2 is obtained.

[0123] In this embodiment, in the second voltage divider module, the third resistor is electrically connected to the second power supply interface, and its input voltage is 0V; the fourth resistor is electrically connected to the fast discharge module, and the input voltage is obtained based on the fast discharge module; based on the voltage division of the third resistor and the fourth resistor, the third drive signal con3 is obtained.

[0124] In this embodiment, the fast discharge module includes a PNP transistor, an NPN transistor and an NMOS transistor, wherein the output end of the first voltage divider module is connected to the base of the PNP transistor, and the second drive signal con2 is used as the base signal of the PNP transistor; the output end of the second voltage divider module is connected to the base of the NPN transistor, and the third drive signal con3 is used as the base signal of the NPN transistor; the output end of the high-speed optical coupler is connected to the gate of the NMOS tube, and the first drive signal con1 is used as the gate signal of the NMOS tube. The collectors of the PNP transistor and the NPN transistor are connected to the output end of the NMOS tube.

[0125] In this embodiment, the switch control module includes a SiC-MOSFET; the source of the SiC-MOSFET is connected to a driving module; the gate of the SiC-MOSFET is electrically connected to the input end of the SiC-MOSFET in the fast discharge module and the driving module.

[0126] In this embodiment, the NMOS tube S1 in the fast discharge module is regarded as a switch. When the SiC-MOSFET (Q2) in the switch control module is turned off, S1 is turned on, and the discharge path of the Miller current is opened. On the contrary, when Q2 is turned on, the path is closed. The turn-on and turn-off process of S1 is as follows:

[0127] When the initial state of S1 is off, the potential at point b is -4V. When the control signal (PWM) of Q2 changes from 0V to 5V, the output first drive signal con1 of the high-speed optical coupler S4 at point a changes to -4V. The threshold voltage of S1 is usually between 1V and 2V, at which point S1 is off. On the contrary, when the control signal (PWM) of Q2 changes from 5V to 0V, the output first drive signal con1 of the high-speed optical coupler S4 at point a changes to 0V, at which point S1 is on.

[0128] In this embodiment, the crosstalk oscillation is superimposed on -4V, resulting in the first voltage u gs During oscillation, the voltage is either above or below -4 V. In both cases, the circuit operates in two modes.

[0129] Please refer to Figure 3 , Figure 3 An operation mode structure diagram provided for an embodiment of the present invention.

[0130] In this embodiment, the first voltage, that is, the voltage at the gate of the SiC-MOSFET, is denoted as the gate-source voltage u gs When the gate-source voltage u gs Oscillation is higher than -4V: When the first voltage exceeds -4V, the Miller current discharge path is as follows Figure 3 . Among them, the resistance ratio of the first resistor and the second resistor in the first voltage divider module is 49:1. According to the resistor voltage division principle, the second drive signal con2 is -4.9V, and the potential of point c (con2) will be -4.9V. Since the threshold voltage of S2 is 1V, when the potential of point b exceeds -3.9V, transistor S2 is turned on. At this time, the current gain effect of the transistor can quickly discharge the Miller current.

[0131] Please refer to Figure 4 , Figure 4 Another operating mode structure diagram provided for an embodiment of the present invention.

[0132] In this embodiment, the first voltage, that is, the voltage at the gate of the SiC-MOSFET, is denoted as the gate-source voltage u gs When the gate-source voltage u gs The oscillation is lower than -4V. When the first voltage is lower than -4V, the Miller current discharge path is as follows: Figure 4 As shown. The value ratio of the third resistor to the fourth resistor is 31:9. According to the voltage division principle, the potential at point d (con3) will be -3.1V. Since the threshold voltage of S3 is 1V, it will be turned on when the potential at point b is lower than -4.1V. At this time, the voltage gap will be quickly filled.

[0133] In this embodiment, the crosstalk oscillation range can be suppressed within 0.2V through two operation modes.

[0134] Please refer to Figure 5 , Figure 5 A schematic diagram of the topological structure of some modules of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided in an embodiment of the present invention.

[0135] In this embodiment, the switch control module includes a first SiC-MOSFET ( Q1 ) and a second SiC-MOSFET ( Q2 ).

[0136] In this embodiment, in order to verify the oscillation suppression effect of the proposed SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler, a double-pulse simulation of the proposed SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler is performed in LTspice.

[0137] In this embodiment, based on the circuit, the first SiC-MOSFET (Q1) in the switch control module is turned on twice in succession, and the turn-on time is set to 15μs each time. Q2 remains in the off state during the whole process. Operating conditions: DC voltage (Udc=700V), inductor current (I=15A) after the first pulse. In addition, the oscillation waveform of the original drive circuit and the SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler is recorded to verify the suppression effect of the proposed circuit on the crosstalk oscillation range. The gate-source voltage waveform of the turn-on and turn-off actions of the original drive circuit and the SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler is recorded. Verify whether the proposed circuit will affect the switching speed of the device.

[0138] Please refer to Figure 6 and Figure 7 , Figure 6 This is a diagram showing the oscillation suppression effect of an original driving circuit provided by an embodiment of the present invention. Figure 7 This is a diagram showing the oscillation suppression effect of the SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler provided in an embodiment of the present invention.

[0139] In this embodiment, the operating conditions are: DC voltage (Udc=700V), inductor current after the first pulse (I=15A). It can be seen that when the SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler is not used, the oscillation range can reach 4.94V. However, after using the proposed SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler, the oscillation range is suppressed to about 0.2V. These data show that the circuit can effectively suppress crosstalk oscillation.

[0140] Please refer to Figure 8 and Fig. 9 , Figure 8 A schematic diagram of a switching waveform of an original driving circuit provided in an embodiment of the present invention, Fig. 9 A schematic diagram of switching waveforms of a SiC-MOSFET active crosstalk suppression circuit based on a high-speed optocoupler provided in an embodiment of the present invention.

[0141] In this embodiment, after adding the oscillation suppression circuit, the gate-source voltage u gs The waveform is almost the same as the original waveform. This shows that the switching speed of the device is almost not affected.

[0142] In this embodiment, the control signal PWM signal of the electrical isolation module is generated according to the state and output signal of the switch control module acquired by the driving module, so as to generate the driving signal of the fast discharge module through the electrical isolation module, and adjust the on and off of the fast discharge module based on the control signal, adjust the circuit voltage, and protect the safety and stability of the high-voltage and low-voltage parts; and discharge the Miller current through the fast discharge module to reduce the oscillation phenomenon during the switching process. Through the coordinated work between the various modules, the whole process from power supply to signal transmission and control is optimized, the gate crosstalk oscillation is suppressed, and the performance and reliability of the system are improved.

[0143] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler, characterized in that: include: Power module, drive module, electrical isolation module, fast discharge module and switch control module; The power supply module is electrically connected to the driving module and the electrical isolation module; The driving module is electrically connected to the electrical isolation module and the switch control module; The electrical isolation module is electrically connected to the fast discharge module; The fast discharge module is electrically connected to the switch control module.

2. The Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 1, characterized in that: The power module includes a first power interface, a second power interface, a third power interface, a fourth power interface and a fifth power interface; The driving module is electrically connected to the first power interface, the second power interface, the third power interface and the fourth power interface respectively; The electrical isolation module is electrically connected to the second power interface, the third power interface, the fourth power interface and the fifth power interface respectively.

3. The Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 2, characterized in that: The electrical isolation module includes a high-speed optical coupler, a first voltage divider module and a second voltage divider module; The input end of the high-speed optical coupler is electrically connected to the driving module, and the output end of the high-speed optical coupler is electrically connected to the fast discharge module; The first end of the first voltage dividing module is electrically connected to the second power interface and the fifth power interface, and the second end of the first voltage dividing module is electrically connected to the fast discharge module; The first end of the second voltage dividing module is electrically connected to the second power interface and the fourth power interface, and the second end of the second voltage dividing module is electrically connected to the fast discharge module.

4. The SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 3, characterized in that: The fast discharge module includes: a first triode, a second triode and a first switch control element; The emitter of the first transistor is electrically connected to the emitter of the second transistor and the first end of the first switch control element; The collector of the first transistor is electrically connected to the collector of the second transistor and the first end of the second voltage divider module; The base of the first transistor is electrically connected to the second end of the first voltage dividing module; The base of the second transistor is electrically connected to the second end of the second voltage dividing module; The second end of the first switch control element is electrically connected to the output end of the high-speed optical coupler; the third end of the first switch control element is electrically connected to the switch control module and the driving module.

5. The SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 4, characterized in that: The first transistor is a PNP transistor, and the second transistor is an NPN transistor; The emitter of the PNP transistor is electrically connected to the emitter of the NPN transistor and the first end of the first switch control element; The collector of the PNP transistor is electrically connected to the collector of the NPN transistor and the first end of the second voltage divider module; The base of the PNP transistor is electrically connected to the second end of the first voltage dividing module; The base of the NPN transistor is electrically connected to the second end of the second voltage dividing module.

6. The SiC-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 5, characterized in that: The first switch control element is an NMOS tube; The source of the NMOS transistor is electrically connected to the emitter of the PNP transistor and the collector of the NPN transistor; The gate of the NMOS tube is electrically connected to the output end of the high-speed optical coupler; The drain of the NMOS tube is electrically connected to the switch control module.

7. The Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 5, characterized in that: The switch control module includes a second switch control element; The first end of the second switch control element is connected to the driving module; the second end of the second switch control element is electrically connected to the third end of the first switch control element and the driving module.

8. The Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 7, characterized in that: The second switch control element comprises a Si C-MOSFET; The source and driving module of the Si C-MOSFET; The gate of the Si C-MOSFET is electrically connected to the third terminal of the first switch control element and the driving module.

9. The Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 3, characterized in that: The first voltage dividing module includes a first resistor and a second resistor; the second voltage dividing module includes a third resistor and a fourth resistor; The first end of the first resistor is electrically connected to the second power interface; the first end of the second resistor is electrically connected to the fifth power interface; the second end of the first resistor is electrically connected to the second end of the second resistor and the fast discharge module; The first end of the third resistor is electrically connected to the second power interface; the first end of the fourth resistor is electrically connected to the fourth power interface; the second end of the third resistor is electrically connected to the second end of the fourth resistor and the fast discharge module.

10. The Si C-MOSFET active crosstalk suppression circuit based on high-speed optocoupler according to claim 3, characterized in that: The high-speed optical coupler includes a light emitting diode and a phototransistor.

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