Isolation pulse coupling full-bridge silicon carbide drive circuit with low EMI

Abstract

The utility model provides a low-EMI isolation pulse coupling full-bridge silicon carbide drive circuit, which can reduce electromagnetic interference and ensure normal operation of the full-bridge drive circuit. Comprising two same half-bridge circuits, and each half-bridge circuit comprises a driving isolation module used for receiving a driving signal and amplifying and isolating the driving signal; the quick turn-off protection module is connected with the driving isolation module and is used for realizing quick turn-off according to the amplified and isolated driving signal and realizing clamping protection of positive and negative voltages of the driving signal; the rapid turn-off protection module comprises a silicon carbide MOS tube Q1 and a silicon carbide MOS tube Q2. And the EMI noise reduction module is connected with the quick turn-off protection module and is used for reducing EMI noise of the silicon carbide MOS tube Q1 and the silicon carbide MOS tube Q2.

Description

Technical Field

[0001] This utility model relates to the field of silicon carbide driving technology, specifically to a low-EMI isolated pulse-coupled full-bridge silicon carbide driving circuit. Background Technology

[0002] In fields such as new energy vehicles, industrial control, and power electronics, full-bridge circuits composed of power semiconductors are required for power conversion and control. Among them, SiC (silicon carbide) power devices are power semiconductor devices made of silicon carbide materials. They are one of the important applications of the third generation of semiconductor materials after silicon (Si) and gallium nitride (GaN). With its excellent physical and chemical properties, such as high insulation breakdown field strength, wide bandgap, and high thermal conductivity, SiC has shown great potential and broad application prospects in the field of power electronics. However, correspondingly, its disadvantages are also obvious. It has poor anti-interference ability and is easily affected by electromagnetic interference from temperature or external environment, which can affect the normal operation of the full-bridge drive circuit. Utility Model Content

[0003] To address the aforementioned issues, this invention provides a low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit, which reduces electromagnetic interference and ensures the normal operation of the full-bridge drive circuit.

[0004] This utility model adopts the following technical solution: a low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit, comprising two identical half-bridge circuits, each of which includes:

[0005] The drive isolation module is used to receive drive signals and amplify and isolate them.

[0006] A fast shutdown protection module, connected to the drive isolation module, is used to achieve fast shutdown based on the amplified and isolated drive signal, and to clamp the positive and negative voltages of the drive signal; the fast shutdown protection module includes silicon carbide MOSFET Q1 and silicon carbide MOSFET Q2;

[0007] An EMI noise reduction module, connected to the fast shutdown protection module, is used to reduce the EMI noise of the silicon carbide MOSFETs Q1 and Q2.

[0008] Further, the drive isolation module includes resistors R1-R7, capacitors C1-C5, diodes D1-D4, transformer T1, and power driver U1. The power driver U1 uses a power driver chip of model TMP27524. One end of resistor R1 is connected to drive signal PWM1B, and one end of resistor R3 is connected to drive signal PWM2B. Pin 2 of the power driver U1 is connected to the other end of resistor R1, one end of resistor R2, and one end of capacitor C1. The other ends of resistor R2 and capacitor C1 are connected and then grounded. Pin 4 of the power driver U1 is connected to the other end of resistor R3, one end of resistor R4, and one end of capacitor C2. The other ends of resistor R4 and capacitor C2 are connected and then grounded. Pins 1 and 8 of the power driver U1 are connected. Pin 3 of the power driver U1 is connected to one end of capacitor C3 and then grounded. Pin 6 of the power driver U1 is connected to the other end of capacitor C3... One end of resistor R5 is connected to pin 8 of power driver U1, and the other end of resistor R5 is connected to a 12V power supply. Pin 5 of power driver U1 is connected to pin 6 of transformer T1, the anode of diode D1, and the cathode of diode D3. Pin 7 of power driver U1 is connected to one end of capacitor C4 and capacitor C5, the anode of diode D2, and the cathode of diode D4. The anodes of diodes D3 and D4 are connected to ground. The cathodes of diodes D1 and D2 are connected to a 12V power supply. The other ends of capacitors C4 and C5 are connected to pin 5 of transformer T1. Pin 1 of transformer T1 is connected to one end of resistor R6. Pin 3 of transformer T1 is connected to the other end of resistor R6. Pin 4 of transformer T1 is connected to one end of resistor R7. Pin 2 of transformer T1 is connected to the other end of resistor R7.

[0009] Furthermore, the fast shutdown protection module also includes resistors R8-R23, capacitors C6-C9, diodes D5-D12, ferrite bead inductors F1 and F2, field-effect transistors Q3 and Q4, and Zener diodes ZD1-ZD6. Pin 1 of the transformer T1 is connected to one end of resistor R8 and the anode of diode D5. The other end of resistor R8 is connected to the gate of field-effect transistor Q3. The cathode of diode D5 is connected to one end of resistor R9, the cathode of Zener diode ZD2, the cathode of diode D8, one end of resistor R11 and R12, and the source of field-effect transistor Q3. The other end of resistor R9 is connected to the anodes of diodes D6 and D7. Pin 3 of the transformer T1 is connected to the anode of Zener diode ZD1, one end of capacitor C6, and the drain of field-effect transistor Q3. The negative terminal of Zener diode ZD1 is connected to the other end of capacitor C6, the negative terminals of diode D6 and D7, one end of resistor R10, one end of resistor R14, and one end of capacitor C7. The positive terminal of Zener diode ZD2 is connected to the positive terminal of Zener diode ZD3. The negative terminal of Zener diode ZD3 is connected to the other end of resistor R10. One end of resistor R13 is connected to the other end of capacitor C7. The other end of resistor R13 is connected to the other ends of resistors R11 and R12, the positive terminal of diode D8, and one end of ferrite bead inductor F1. The other end of ferrite bead inductor F1 is connected to one end of resistor R15 and the gate of silicon carbide MOSFET Q1. The other end of resistor R14 is connected to the other end of resistor R15 and the driver source pin of silicon carbide MOSFET Q1.Pin 4 of transformer T1 is connected to one end of resistor R16 and the anode of diode D9. The other end of resistor R16 is connected to the gate of MOSFET Q4. The cathode of diode D9 is connected to one end of resistor R17, the cathode of Zener diode ZD5, the cathode of diode D12, one end of resistor R19 and resistor R20, and the source of MOSFET Q4. The other end of resistor R17 is connected to the anodes of diodes D10 and D11. Pin 2 of transformer T1 is connected to the anode of Zener diode ZD4, one end of capacitor C8, and the drain of MOSFET Q4. The cathode of Zener diode ZD4 is connected to the other end of capacitor C8, the cathode of diode D10, and the gate of MOSFET Q4. The negative terminal of D11, one end of resistor R18, one end of resistor R22, and one end of capacitor C9 are all connected together. The positive terminal of Zener diode ZD5 is connected to the positive terminal of Zener diode ZD6. The negative terminal of Zener diode ZD6 is connected to the other end of resistor R18. One end of resistor R21 is connected to the other end of capacitor C9. The other end of resistor R21 is connected to the other ends of resistor R19 and resistor R20, the positive terminal of diode D12, and one end of ferrite bead inductor F2. The other end of ferrite bead inductor F2 is connected to one end of resistor R23 and the gate of silicon carbide MOSFET Q2. The other end of resistor R22 is connected to the other end of resistor R23 and the driver source pin of silicon carbide MOSFET Q2.

[0010] Furthermore, the EMI noise reduction module includes capacitors C10-C14, a ferrite bead inductor F3, and a ferrite bead inductor F4; the drain of the silicon carbide MOSFET Q1 is connected to one end of the ferrite bead inductor F3, the source of the silicon carbide MOSFET Q1 is connected to one end of the ferrite bead inductor F4, and one end of capacitors C11 and C12, the other end of capacitor C11 is connected to one end of capacitor C10, the drain of the silicon carbide MOSFET Q2 is connected to the other end of the ferrite bead inductor F4, the source of the silicon carbide MOSFET Q2 is connected to one end of capacitors C13 and C14, the other end of capacitor C13 is connected to the other end of capacitor C12, and the other end of the ferrite bead inductor F3 is connected to the other ends of capacitors C10 and C14.

[0011] The beneficial effects of this utility model are that by setting two identical half-bridge circuits, full-bridge drive control can be realized. Each half-bridge circuit, through the sequentially connected drive isolation module, fast turn-off protection module, and EMI noise reduction module, can amplify and isolate the drive signal after receiving it, and realize negative voltage fast turn-off of silicon carbide, thereby achieving clamping protection of positive and negative voltages of the drive signal. It can also reduce gate crosstalk and oscillation when silicon carbide is turned on, further reducing electromagnetic interference, thus ensuring the normal operation of the full-bridge drive circuit and having good economic value. Attached Figure Description

[0012] Figure 1 This is a structural block diagram of the present invention;

[0013] Figure 2 This is the circuit diagram of the half-bridge circuit in this utility model. Detailed Implementation

[0014] like Figure 1 , Figure 2 As shown, this utility model discloses a low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit, comprising two identical half-bridge circuits, each half-bridge circuit including:

[0015] The drive isolation module is used to receive drive signals and amplify and isolate them.

[0016] The fast shutdown protection module, connected to the drive isolation module, is used to achieve fast shutdown based on the amplified and isolated drive signal, and to clamp the positive and negative voltages of the drive signal; the fast shutdown protection module includes silicon carbide MOSFET Q1 and silicon carbide MOSFET Q2;

[0017] The EMI noise reduction module, connected to the fast shutdown protection module, is used to reduce the EMI noise of silicon carbide MOSFETs Q1 and Q2.

[0018] The drive isolation module includes resistors R1-R7, capacitors C1-C5, diodes D1-D4, transformer T1, and power driver U1. Transformer T1 is a toroidal drive pulse transformer, whose main technical parameters are high isolation voltage, low coupling distortion, high common-mode rejection ratio, and small coupling capacitance. Power driver U1 uses a TMP27524 power driver chip. Capacitors C4 and C5 serve as coupling capacitors. Diodes D1-D4 form port protection, and drive signals with a 180-degree phase difference are coupled through pins 1 and 4 of transformer T1. One end of resistor R1 is connected to drive signal PWM1B, and one end of resistor R3 is connected to drive signal PWM2B. Pin 2 of power driver U1 is connected to the other end of resistor R1, one end of resistor R2, and one end of capacitor C1. The other ends of resistor R2 and capacitor C1 are connected and then grounded. Pin 4 of power driver U1 is connected to the other end of resistor R3, one end of resistor R4, and one end of capacitor C2. The other ends of resistor R4 and capacitor C2 are connected and then grounded. Pins 1 and 8 of the power driver U1 are connected. Pin 3 of the power driver U1 is connected to one end of capacitor C3 and then grounded. Pin 6 of the power driver U1 is connected to the other end of capacitor C3 and one end of resistor R5, and then connected to pin 8 of the power driver U1. The other end of resistor R5 is connected to the 12V power supply. Pin 5 of the power driver U1 is connected to pin 6 of transformer T1, the positive terminal of diode D1, and the negative terminal of diode D3. Pin 7 of the power driver U1 is connected to one end of capacitor C4 and capacitor C5, and the positive terminal of diode D2. The negative terminals of diodes D4 are all connected together. The positive terminals of diodes D3 and D4 are connected together and then grounded. The negative terminals of diodes D1 and D2 are connected together and then connected to a 12V power supply. The other ends of capacitors C4 and C5 are connected together and then connected to pin 5 of transformer T1. Pin 1 of transformer T1 is connected to one end of resistor R6. Pin 3 of transformer T1 is connected to the other end of resistor R6. Pin 4 of transformer T1 is connected to one end of resistor R7. Pin 2 of transformer T1 is connected to the other end of resistor R7.

[0019] The fast shutdown protection module also includes resistors R8-R23, capacitors C6-C9, diodes D5-D12, ferrite bead inductors F1 and F2, field-effect transistors Q3 and Q4, and Zener diodes ZD1-ZD6. Pin 1 of transformer T1 is connected to one end of resistor R8 and the anode of diode D5. The other end of resistor R8 is connected to the gate of field-effect transistor Q3. The cathode of diode D5 is connected to one end of resistor R9, the cathode of Zener diode ZD2, the cathode of diode D8, one end of resistors R11 and R12, and the source of field-effect transistor Q3. The other end of resistor R9 is connected to the anodes of diodes D6 and D7. Pin 3 of transformer T1 is connected to the anode of Zener diode ZD1 and capacitor C6. One end of the resistor R13 is connected to the drain of the MOSFET Q3. The cathode of the Zener diode ZD1 is connected to the other end of capacitor C6, the cathode of diode D6, the cathode of diode D7, one end of resistor R10, one end of resistor R14, and one end of capacitor C7. The anode of Zener diode ZD2 is connected to the anode of Zener diode ZD3. The cathode of Zener diode ZD3 is connected to the other end of resistor R10. One end of resistor R13 is connected to the other end of capacitor C7. The other end of resistor R13 is connected to the other ends of resistors R11 and R12, the anode of diode D8, and one end of ferrite bead inductor F1. The other end of ferrite bead inductor F1 is connected to one end of resistor R15 and the gate of silicon carbide MOSFET Q1. The other end of resistor R14 is connected to the gate of the MOSFET Q1. The other end of resistor R15 is connected to the source pin of the driver of silicon carbide MOSFET Q1; pin 4 of transformer T1 is connected to one end of resistor R16 and the anode of diode D9; the other end of resistor R16 is connected to the gate of MOSFET Q4; the cathode of diode D9 is connected to one end of resistor R17, the cathode of Zener diode ZD5, the cathode of diode D12, one end of resistor R19 and resistor R20, and the source of MOSFET Q4; the other end of resistor R17 is connected to the anodes of diodes D10 and D11; pin 2 of transformer T1 is connected to the anode of Zener diode ZD4, one end of capacitor C8, and the drain of MOSFET Q4; the cathode of Zener diode ZD4 is connected to the other end of capacitor C8. One end of resistor R11 is connected to the cathode of diode D10, the cathode of diode D11, one end of resistor R18, one end of resistor R22, and one end of capacitor C9. The anode of Zener diode ZD5 is connected to the anode of Zener diode ZD6. The cathode of Zener diode ZD6 is connected to the other end of resistor R18. One end of resistor R21 is connected to the other end of capacitor C9. The other end of resistor R21 is connected to resistor R19, the other end of resistor R20, the anode of diode D12, and one end of ferrite bead inductor F2. The other end of ferrite bead inductor F2 is connected to one end of resistor R23 and the gate of silicon carbide MOSFET Q2. The other end of resistor R22 is connected to the other end of resistor R23 and the driver source pin of silicon carbide MOSFET Q2.

[0020] The EMI noise reduction module includes capacitors C10-C14, ferrite bead inductor F3, and ferrite bead inductor F4. The drain of silicon carbide MOSFET Q1 is connected to one end of ferrite bead inductor F3. The source of silicon carbide MOSFET Q1 is connected to one end of ferrite bead inductor F4, one end of capacitors C11 and C12, and the other end of capacitor C11 is connected to one end of capacitor C10. The drain of silicon carbide MOSFET Q2 is connected to the other end of ferrite bead inductor F4. The source of silicon carbide MOSFET Q2 is connected to one end of capacitors C13 and C14, and the other end of capacitor C13 is connected to the other end of capacitor C12. The other end of ferrite bead inductor F3 is connected to the other ends of capacitors C10 and C14. Through capacitors C10-C14, the switching noise of silicon carbide MOSFETs Q1 and Q2 can be absorbed.

[0021] Since the two half-bridge circuits are identical and their operating principles are the same, this utility model only uses... Figure 2 Taking a half-bridge circuit as an example, the working principle is explained as follows: Two sets of drive signals from a microcontroller or DSP controller are input to the drive isolation module. The drive isolation module amplifies and isolates one set of drive signals, PWM1B and PWM2B (i.e., symmetrical drive waveforms with dead time). The other set of drive signals is driven and noise-reduced by another half-bridge circuit. The amplified and isolated drive signal is input to the fast shutdown protection module. When pin 1 of transformer T1 is a positive pulse, the field-effect transistor Q3 is turned off. The drive signal is sent to the gate of silicon carbide MOSFET Q1 through diode D5, resistor R11, and ferrite bead inductor F1. When pin 1 of transformer T1 is a negative pulse, the field-effect transistor Q3 is quickly turned on, realizing the negative voltage fast shutdown of silicon carbide MOSFET Q1. At the same time, the positive voltage of the drive pulse is realized through Zener diodes ZD2 and ZD3 and resistor R10. Voltage clamping protection is achieved through Zener diodes ZD5 and ZD6, and resistor R18 to clamp the negative voltage of the drive pulse; and through Zener diode ZD1, capacitor C6, resistor R9, diode D6, and diode D7 to meet the negative voltage requirements of silicon carbide drive. After the drive signal is sent to the EMI noise reduction module, the EMI noise of the gate of silicon carbide MOSFET Q1 is reduced to the maximum extent through the ferrite bead inductor F1, the oscillation of the drain of silicon carbide MOSFET Q1 is further reduced through the ferrite bead inductor F3, and the resistor R13 and capacitor C7 connected in parallel to the gate of silicon carbide MOSFET Q1 can reduce gate crosstalk and oscillation when silicon carbide MOSFET Q1 is turned on, further reducing electromagnetic interference. Then, the noise-reduced drive signal is output through the output terminal OUT, realizing low EMI isolated pulse coupling full-bridge silicon carbide drive.

[0022] Figure 2 In this circuit, PLINK and NLINK serve as the positive and negative power supply terminals of the DC bus, respectively; OUT serves as the half-bridge output of the half-bridge circuit; and LCAG serves as the common ground terminal.

[0023] In summary, this invention firstly leverages the low-loss characteristics of silicon carbide devices to help reduce system energy consumption and improve energy efficiency. Furthermore, the high voltage and high temperature resistance of silicon carbide devices allows for a more compact system with reduced size. Next, by sequentially connecting a drive isolation module, a fast shutdown protection module, and an EMI noise reduction module, it effectively reduces EMI interference (electromagnetic interference) during the switching of silicon carbide devices, ensuring the stability and reliability of the full-bridge drive circuit. This makes it widely applicable in various fields, such as fast-charging systems for new energy vehicles and high-precision power supplies in industrial control, demonstrating broad application prospects.

[0024] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0025] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit, comprising two identical half-bridge circuits, characterized in that: Each of the aforementioned half-bridge circuits includes: The drive isolation module is used to receive drive signals and amplify and isolate them. A fast shutdown protection module, connected to the drive isolation module, is used to achieve fast shutdown based on the amplified and isolated drive signal, and to clamp the positive and negative voltages of the drive signal; the fast shutdown protection module includes silicon carbide MOSFET Q1 and silicon carbide MOSFET Q2; An EMI noise reduction module, connected to the fast shutdown protection module, is used to reduce the EMI noise of the silicon carbide MOSFETs Q1 and Q2.

2. The low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit according to claim 1, characterized in that: The drive isolation module includes resistors R1-R7, capacitors C1-C5, diodes D1-D4, transformer T1, and power driver U1. Power driver U1 uses a TMP27524 power driver chip. One end of resistor R1 is connected to drive signal PWM1B, and one end of resistor R3 is connected to drive signal PWM2B. Pin 2 of power driver U1 is connected to the other end of resistor R1, one end of resistor R2, and one end of capacitor C1. The other ends of resistor R2 and capacitor C1 are connected and then grounded. Pin 4 of power driver U1 is connected to the other end of resistor R3, one end of resistor R4, and one end of capacitor C2. The other ends of resistor R4 and capacitor C2 are connected and then grounded. Pins 1 and 8 of power driver U1 are connected. Pin 3 of power driver U1 is connected to one end of capacitor C3 and then grounded. Pin 6 of power driver U1 is connected to the other end of capacitor C3, resistor R7, and capacitor C5. One end of resistor R5 is connected to pin 8 of the power driver U1. The other end of resistor R5 is connected to a 12V power supply. Pin 5 of the power driver U1 is connected to pin 6 of the transformer T1, the anode of diode D1, and the cathode of diode D3. Pin 7 of the power driver U1 is connected to one end of capacitors C4 and C5, the anode of diode D2, and the cathode of diode D4. The anodes of diodes D3 and D4 are connected to ground. The cathodes of diodes D1 and D2 are connected to a 12V power supply. The other ends of capacitors C4 and C5 are connected to pin 5 of the transformer T1. Pin 1 of the transformer T1 is connected to one end of resistor R6. Pin 3 of the transformer T1 is connected to the other end of resistor R6. Pin 4 of the transformer T1 is connected to one end of resistor R7. Pin 2 of the transformer T1 is connected to the other end of resistor R7.

3. The low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit according to claim 2, characterized in that: The fast shutdown protection module also includes resistors R8-R23, capacitors C6-C9, diodes D5-D12, ferrite bead inductors F1 and F2, field-effect transistors Q3 and Q4, and Zener diodes ZD1-ZD6. Pin 1 of the transformer T1 is connected to one end of resistor R8 and the anode of diode D5. The other end of resistor R8 is connected to the gate of field-effect transistor Q3. The cathode of diode D5 is connected to one end of resistor R9, the cathode of Zener diode ZD2, the cathode of diode D8, one end of resistor R11 and R12, and the source of field-effect transistor Q3. The other end of resistor R9 is connected to the anodes of diodes D6 and D7. Pin 3 of the transformer T1 is connected to the anode of Zener diode ZD1, one end of capacitor C6, and the drain of field-effect transistor Q3. The negative terminal of Zener diode ZD1 is connected to the other end of capacitor C6, the negative terminals of diode D6 and D7, one end of resistor R10, one end of resistor R14, and one end of capacitor C7. The positive terminal of Zener diode ZD2 is connected to the positive terminal of Zener diode ZD3. The negative terminal of Zener diode ZD3 is connected to the other end of resistor R10. One end of resistor R13 is connected to the other end of capacitor C7. The other end of resistor R13 is connected to the other ends of resistors R11 and R12, the positive terminal of diode D8, and one end of ferrite bead inductor F1. The other end of ferrite bead inductor F1 is connected to one end of resistor R15 and the gate of silicon carbide MOSFET Q1. The other end of resistor R14 is connected to the other end of resistor R15 and the driver source pin of silicon carbide MOSFET Q1.Pin 4 of transformer T1 is connected to one end of resistor R16 and the anode of diode D9. The other end of resistor R16 is connected to the gate of MOSFET Q4. The cathode of diode D9 is connected to one end of resistor R17, the cathode of Zener diode ZD5, the cathode of diode D12, one end of resistor R19 and resistor R20, and the source of MOSFET Q4. The other end of resistor R17 is connected to the anodes of diodes D10 and D11. Pin 2 of transformer T1 is connected to the anode of Zener diode ZD4, one end of capacitor C8, and the drain of MOSFET Q4. The cathode of Zener diode ZD4 is connected to the other end of capacitor C8, the cathode of diode D10, and the gate of MOSFET Q4. The negative terminal of diode D11, one end of resistor R18, one end of resistor R22, and one end of capacitor C9 are all connected together. The positive terminal of Zener diode ZD5 is connected to the positive terminal of Zener diode ZD6, and the negative terminal of Zener diode ZD6 is connected to the other end of resistor R18. One end of resistor R21 is connected to the other end of capacitor C9. The other end of resistor R21 is connected to the other ends of resistors R19 and R20, the positive terminal of diode D12, and one end of ferrite bead inductor F2. The other end of ferrite bead inductor F2 is connected to one end of resistor R23 and the gate of silicon carbide MOSFET Q2. The other end of resistor R22 is connected to the other end of resistor R23 and the driver source pin of silicon carbide MOSFET Q2.

4. The low-EMI isolated pulse-coupled full-bridge silicon carbide drive circuit according to claim 3, characterized in that: The EMI noise reduction module includes capacitors C10-C14, a ferrite bead inductor F3, and a ferrite bead inductor F4. The drain of the silicon carbide MOSFET Q1 is connected to one end of the ferrite bead inductor F3. The source of the silicon carbide MOSFET Q1 is connected to one end of the ferrite bead inductor F4, one end of capacitors C11 and C12, and the other end of capacitor C11 is connected to one end of capacitor C10. The drain of the silicon carbide MOSFET Q2 is connected to the other end of the ferrite bead inductor F4. The source of the silicon carbide MOSFET Q2 is connected to one end of capacitors C13 and C14. The other end of capacitor C13 is connected to the other end of capacitor C12. The other end of the ferrite bead inductor F3 is connected to the other ends of capacitors C10 and C14.

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