Silicon carbide drive circuit with miller clamp function

Abstract

The utility model discloses a silicon carbide drive circuit with miller clamping function relates to semiconductor drive circuit technical field, the utility model discloses a power module, drive module, control module and power module, power module is used for converting external 24V power supply into 5V voltage and isolated 15V voltage, and the power supply is powered for drive chip input end and output drive end, drive module is used for the differential signal processing amplification MCU sends to the drive voltage of SIC MOS, the utility model discloses circuit can when the current passes through miller capacitor voltage not through drive resistance directly connects ground, makes the current quick release to the voltage reduction below Vth prevents the false opening, in addition, this circuit can also detect the overcurrent condition of SIC MOS, when the current exceeds the set value, closes drive output, and simultaneously possesses chip and drive voltage detection function, when voltage is unstable, sends signal to MCU and closes drive output.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor driving circuit technology, and in particular relates to a silicon carbide driving circuit with Miller clamping function. Background Technology

[0002] With the continuous development of power electronics technology, silicon carbide (SiC) power devices have been increasingly widely used in various power conversion systems, such as new energy vehicles, photovoltaic inverters, and smart grids, due to their advantages such as high voltage, high temperature, high frequency, and low switching losses. However, SiC MOSFETs face many challenges in practical applications.

[0003] On the one hand, SiC MOSFETs have large gate and drain capacitances, as well as high gate threshold voltages, which to some extent limits their switching speed and leads to increased switching losses in high-frequency applications. On the other hand, due to the influence of parasitic inductance and capacitance in the circuit, SiC MOSFETs are susceptible to the Miller effect during switching. The Miller effect can cause abnormal fluctuations in the gate voltage, potentially leading to false turn-on and severely affecting the reliability and stability of the circuit.

[0004] Furthermore, some existing SiC driver circuits suffer from low switching performance and poor reliability, failing to meet the ever-increasing demands for high-performance power conversion. For example, some driver circuits cannot precisely control the gate current when driving SiC MOSFETs, leading to unstable device switching times and affecting the overall system efficiency. Simultaneously, some driver circuits lack effective overcurrent detection and protection functions, failing to take timely measures when overcurrent faults occur, easily causing device damage and reducing system reliability. Therefore, developing a SiC driver circuit with Miller clamping function that can effectively overcome the above problems is of significant practical importance. Utility Model Content

[0005] This invention provides a silicon carbide drive circuit with Miller clamping function to solve the problems of low switching performance, large influence of Miller effect and poor reliability of existing SiC drive circuits, thereby improving the working stability of SiC MOSFET and the overall performance of the system.

[0006] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution:

[0007] A silicon carbide drive circuit with Miller clamping function includes a power supply module, a drive module, a control module, and a power module.

[0008] The power module converts an external 24V power supply into a 5V voltage and an isolated 15V voltage to power the input and output drive terminals of the driver chip. Its features include: an external 24V voltage connected to pin 1 of a first power interface P1 and pin 2 of a first power conversion chip U2; a first capacitor C4 connected in parallel between pins 2 and 1 of the first power interface P1, and pin 2 connected to the first ground terminal GND1; a second capacitor C5 connected in parallel between pins 3 and 2, and pin 3 being the 5V output pin; a third capacitor C6 connected in parallel between pins 2 and 1 of the first power conversion chip U2, and pin 1 connected to the first ground terminal GND1; pin 3 of the first power conversion chip U2 being the 15V output pin, and pin 5 being the 0V output pin; a fourth capacitor C7 connected in parallel between pins 3 and 5, and pin 5 connected to the second ground terminal GND2; the 15V and the second ground terminal GND2 form an isolated drive power supply, and the 5V and the first ground terminal GND1 form a chip input power supply.

[0009] The driver chip is SiLM5992SHCG-DG. The DESAT pin 2 is connected to the drain of the second MOSFET Q2 through a 100Ω first resistor R1 and a Schottky diode to detect whether the current exceeds the preset value.

[0010] The driving module processes and amplifies the differential signal sent by the MCU to achieve the driving voltage of the SiC (silicon carbide) MOS. The signal sent by the MCU is a differential signal that is converted into a single-ended driving signal after entering the driving chip and the voltage is amplified to 15V. The driving section includes overcurrent detection of the MOS and dual power supply detection for input and output. Its features include: pin 15 of the driving chip U1 is the chip power supply pin, connected to a 5V power supply, and a fifth capacitor C1 is connected in parallel to the first ground terminal GND1. Pin 5 is the positive voltage isolation power supply pin for the drive, connected to a 15V isolation power supply, and a sixth capacitor C2 is connected in parallel to the second ground terminal GND2. Pin 8 of U1 is the negative voltage power supply pin for the drive, connected to the second ground terminal GND2. Pin 7 is the Miller clamp pin, directly connected to the gate of the SiC (silicon carbide) MOS to provide a discharge channel for the MOS transistor. Pin 2 is for short-circuit overcurrent detection of the SiC (Silicon Carbide) MOSFET. It is connected to the drain of the second MOSFET Q2 through the first resistor R1 and the first diode D1. Simultaneously, the seventh capacitor C3 and the second diode D2 are connected in parallel between pin 2 and the first ground terminal GND1. Pin 13 is the overcurrent fault reporting pin, pulled up to 5V output through the second resistor R2. Pin 9 is connected to the first ground terminal GND1, and pin 3 is connected to the second ground terminal GND2. Pin 14 is the reset pin, directly connected to the MCU control pin, clearing the alarm signal by sending a pulse signal. Pin 12 is the dual power supply detection status output pin, pulled up to 5V through the third resistor R3 and output to the MCU receive pin. Pin 6 is the shutdown drive signal output pin, connected to the gate of the second MOSFET Q2 through the third resistor R4. Pin 4 is the turn-on drive signal output pin, connected to the gate of the second MOSFET Q2 through the fourth resistor R5. Pins 1 and 16 are unconnected. Pin 11 is the negative drive input pin, connected to the output pin of the MCU sending the negative drive signal. Pin 10 is the positive drive input pin, which is connected to the output pin of the positive drive signal sent by the MCU.

[0011] The control module controls the power section to turn on and off, thereby controlling the chopper regulation, by sending drive signals and reset signals, and receiving dual power supply detection signals and overcurrent fault signals. Its key feature is that the MCU microcontroller is connected to the + drive signal, - drive signal, dual power supply detection signal, reset signal, and overcurrent fault signal.

[0012] The power module generates a pulse output by chopping the BUS+ bus voltage using a SiC (silicon carbide) MOSFET. Its key feature is that the BUS bus voltage is connected to the drain of a first MOSFET Q1, the source of the first MOSFET Q1 is connected to the drain of a second MOSFET Q2, and the source of the second MOSFET Q2 is grounded. The polarity of the output is controlled by turning the first MOSFET Q1 and the second MOSFET Q2 on and off.

[0013] This invention is used in SiC (silicon carbide) driver circuits, and its working process is as follows:

[0014] (1) The power supply module provides the power supply side voltage and the drive side isolation voltage to the driver chip;

[0015] (2) After the driver chip is powered on normally, pin 12 of the driver chip U1 will send a normal power supply signal to the MCU microcontroller;

[0016] (3) After receiving the normal power supply signal from both ends, the MCU microcontroller sends a differential drive signal to the driver chip;

[0017] (4) The driver chip receives the drive signal from the MCU microcontroller and amplifies it to the drive side power supply voltage. It sends the signal to the gate of the SiC (silicon carbide) MOS transistor through the drive resistor at pins 4 and 6 to control the turn-on and turn-off of the SiC (silicon carbide) MOS transistor.

[0018] (5) When the chip is turned off, the internal MOSFET will directly connect the voltage of the CLMPI pin to the isolation ground (or negative voltage; this circuit is designed with isolation ground). The diode inside will clamp the voltage to negative voltage to prevent false turn-on.

[0019] (6) When the current through the SiC (silicon carbide) MOS exceeds the set value, the driver chip sends an overcurrent fault signal to the MCU microcontroller at pin 13 and blocks the output drive signal at the same time, so as to achieve the SiC (silicon carbide) MOS turn-off effect.

[0020] (7) To restart the drive circuit, a pulse reset signal needs to be sent to pin 14 of the drive chip through the MCU microcontroller.

[0021] The present invention has the following advantages over the prior art:

[0022] The peripheral circuit design of this utility model is simple and can be implemented with a driver chip and a few peripheral components. It combines the advantages of the previous solutions. This driver circuit design can effectively eliminate the influence of the Miller platform by adjusting the negative voltage of the driver side power supply pin 8 VEE2 and adjusting the gate drive resistors R4 and R5.

[0023] Of course, any product implementing this utility model does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 Circuit diagram of the drive section and power section;

[0026] Figure 2 Circuit diagram for the power supply section;

[0027] Figure 3 This is a schematic diagram of the logic section. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings.

[0030] like Figure 2 As shown, the power supply section first converts the 24V voltage into an isolated voltage of 15V and a non-isolated voltage of 5V through the isolated power supply module VRB2415LD-20WR3 and the voltage regulator module LM7805, so as to provide power to the MCU and driver chip.

[0031] like Figure 1 , Figure 3 As shown, when the power supplies on both sides of the driver chip SiLM5992SHCG-DG reach normal values, pin 12 RDY will be pulled high to indicate that the power supply voltage is normal. The driver chip then waits to receive drive signals from the MCU microcontroller. When the differential drive signal is positive, pin 4 OUTH charges the gate through drive resistor R4 to turn it on (this resistor is the on-resistance and can be adjusted according to the required on-time; this resistor affects switching losses). When the differential drive signal is negative, pin 6 OUTL discharges current through resistor R5 to perform turn-off (this resistor is the turn-off resistor; the turn-off time can be adjusted to reduce its impact, but it may cause overshoot and other problems). During turn-off, the gate voltage is detected through the OUTH pin. When the voltage is lower than the clamping voltage (2V), the clamping circuit is activated, generating a low-clamping sink current. During on-time, the clamping circuit is disabled. Pin 2 (DESAT) of the chip is used to detect whether the current exceeds 9V (the chip's default voltage can be adjusted using external circuitry to set a specific current value). Typically, a 100Ω resistor and a Schottky diode are chosen to protect the DESAT pin. When the current on the MOSFET exceeds a preset value during operation, the FLT will send a low-level alarm to the MCU. After the alarm, the alarm state needs to be reset. The MCU sends a low-level pulse signal to pin 14 (RST) of the chip to restore the overcurrent alarm signal.

[0032] The preferred embodiments of this utility model disclosed above are merely illustrative of the present utility model. These preferred embodiments do not exhaustively describe all details, nor do they limit the utility model to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it. This utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A silicon carbide drive circuit with Miller clamping function, characterized in that, It includes a power supply module, a drive module, a control module, and a power module; The power module is used to convert an external 24V power supply into a 5V voltage and an isolated 15V voltage to power the input and output drive terminals of the driver chip. The external 24V voltage is connected to pin 1 of the first power interface (P1) and pin 2 of the first power conversion chip (U2). A first capacitor (C4) is connected in parallel between pin 2 and pin 1 of the first power interface (P1), and pin 2 is connected to the first ground terminal (GND1). A second capacitor (C5) is connected in parallel between pin 3 and pin 2 of the first power interface (P1), and pin 3 is the 5V output pin. A third capacitor (C6) is connected in parallel between pin 2 and pin 1 of the first power conversion chip (U2), and pin 1 is connected to the first ground terminal (GND1). Pin 3 of the first power conversion chip (U2) is the 15V output pin, and pin 5 is the 0V output pin. A fourth capacitor (C7) is connected in parallel between pin 3 and pin 5, and pin 5 is connected to the second ground terminal (GND2). The 15V and the second ground terminal (GND2) form an isolated drive power supply, and the 5V and the first ground terminal (GND1) form a chip input power supply. The driving module is used to process and amplify the differential signal sent by the MCU to the driving voltage of the SiC MOS, including MOS overcurrent detection and input / output dual power supply detection; pin 15 of the driving chip (U1) is connected to a 5V power supply, and a fifth capacitor (C1) is connected in parallel to the first ground terminal (GND1); pin 5 is connected to a 15V isolation power supply, and a sixth capacitor (C2) is connected in parallel to the second ground terminal (GND2); pin 8 is connected to the second ground terminal (GND2) as the driving negative voltage power supply pin; pin 7 is used as a Miller clamping pin and is directly connected to the SiC MOS. The gate of the MOSFET is connected to the drain of the second MOSFET (Q2) via a first resistor (R1) and a first diode (D1). A seventh capacitor (C3) and a second diode (D2) are connected in parallel between pin 2 and the first ground terminal (GND1). Pin 13 is pulled up to 5V via a second resistor (R2) as an overcurrent fault reporting pin. Pin 9 is connected to the first ground terminal (GND1), and pin 3 is connected to the second ground terminal (GND2). Pin 14 is connected to the MCU control pin as a reset pin. Pin 12 is pulled up to 5V via a third resistor (R3) and output to the MCU receive pin as a dual power supply detection status output pin. Pin 6 is connected to the gate of the second MOSFET (Q2) via a third resistor (R4) as a shutdown drive signal output pin. Pin 4 is connected to the gate of the second MOSFET (Q2) via a fourth resistor (R5) as an turn-on drive signal output pin. Pin 11 is connected to the negative drive signal output pin sent by the MCU as a negative drive input pin. Pin 10 is connected to the MCU... The output pin of the sent positive drive signal is used as the positive drive input pin, and pins 1 and 16 are unused pins; The control module controls the power module's shutdown and startup by sending drive signals and reset signals, and receiving dual power supply detection signals and overcurrent fault signals; the MCU microcontroller is connected to the positive drive signal, negative drive signal, dual power supply detection signal, reset signal, and overcurrent fault signal respectively. The power module generates a pulse output by chopping the BUS+ bus voltage through a SiC MOSFET. The BUS bus voltage is connected to the drain of the first MOSFET (Q1), the source of the first MOSFET (Q1) is connected to the drain of the second MOSFET (Q2), and the source of the second MOSFET (Q2) is grounded. The output polarity is adjusted by controlling the on and off states of the first MOSFET (Q1) and the second MOSFET (Q2).

2. The silicon carbide drive circuit with Miller clamping function according to claim 1, characterized in that, In the power module, the first power conversion chip (U2) adopts the isolated power module VRB2415LD-20WR3, and the third pin of the first power interface (P1) outputs a 5V voltage through the voltage regulator module LM7805.

3. A silicon carbide drive circuit with Miller clamping function according to claim 1, characterized in that, The driver chip is a SiLM5992SHCG-DG model. The DESAT terminal of pin 2 is connected to the drain of the second MOSFET (Q2) through a 100Ω first resistor (R1) and a Schottky diode, which is used to detect whether the current exceeds the preset value.

4. A silicon carbide drive circuit with Miller clamping function according to claim 1, characterized in that, The third resistor (R4) between pin 6, corresponding to the off drive signal output pin of the drive module, and the gate of the second MOS transistor (Q2), and the fourth resistor (R5) between pin 4, corresponding to the on drive signal output pin, and the gate of the second MOS transistor (Q2), are used to adjust the switching time and power consumption of the MOS transistor.

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