A driving circuit for SiC power MOSFET

Abstract

The present invention discloses a driving circuit for a SiC power MOSFET, comprising a power management IC, a driving isolation IC, an isolation transformer W, a voltage regulator tube ZD2, a MOS tube Q3, a MOS tube Q4 and a MOS tube Q5. The power management IC is connected to a winding Np of the isolation transformer W, one end of a winding Ns of the transformer W is connected to a positive electrode of a diode D7 and a negative electrode of a diode D8, and the other end of the winding Ns of the transformer W is connected to a positive electrode of a diode D9 and a negative electrode of a diode D10. The present invention can realize the driving of an N-channel SiC power MOSFET and has gate active clamping and overvoltage clamping, thereby meeting the driving requirements of the SiC power MOSFET.

Description

Technical Field

[0001] The present invention relates to the technical field of driving power supplies, and in particular to a driving circuit of a SiC power MOSFET. Background Art

[0002] The application of power devices enables the industry to achieve automated equipment control. With decades of development of power electronics technology, the application of IGBT has become increasingly mature. The emergence of the third-generation wide bandgap semiconductors has taken the development of power electronics technology to a higher level. As the third-generation and a half SiC process matures and costs gradually decrease, the application of SIC will involve various fields of power electronic power supplies, but its characteristics are slightly different from the well-known IGBT, so the driving technology of SIC requires in-depth research and quality improvement. Summary of the invention

[0003] In order to make up for the deficiencies of the prior art, the embodiments of the present application propose a driving circuit for a SiC power MOSFET to solve the problems existing in the prior art.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A driving circuit for a SiC power MOSFET comprises a power management IC, a driving isolation IC, an isolation transformer W, a voltage regulator tube ZD2, a MOS tube Q3, a MOS tube Q4 and a MOS tube Q5, wherein the power management IC is connected to a winding Np of the isolation transformer W, one end of a winding Ns of the transformer W is connected to a positive electrode of a diode D7 and a negative electrode of a diode D8, the other end of a winding Ns of the transformer W is connected to a positive electrode of a diode D9 and a negative electrode of a diode D10, the negative electrode of the diode D7 is connected to a negative electrode of the diode D9, a capacitor EC3, a resistor R4, a capacitor C5, a drain of the MOS tube Q3, a drain of the MOS tube Q5 and a negative electrode of the diode D2, the positive electrode of the diode D8 is connected to a positive electrode of the diode D10, a positive electrode of the diode ZD2, a drain of the MOS tube Q4, a capacitor EC4 and capacitor C6, the other end of capacitor EC3 is connected to the other end of resistor R4, the cathode of diode ZD2, the other end of capacitor C5, the other end of capacitor EC4 and the other end of capacitor C6, the source of MOS tube Q3 is connected to resistor Rgon2, the source of MOS tube Q4 is connected to resistor Rgoff2, the gate of MOS tube Q3 is connected to drive isolation IC, the gate of MOS tube Q4 is connected to drive isolation IC, the drive isolation IC is also connected to control signal DRV, the other end of resistor Rgon2 is connected to the other end of resistor Rgoff2, resistor R2, capacitor C2, the anode of diode D2, the gate of MOS tube Q5 and the drain of transistor Q6, the source of MOS tube Q5 is connected to the gate of transistor Q6, the source of transistor Q6 is connected to the other end of resistor R2 and the other end of capacitor C2.

[0006] As a further technical solution of the present invention: the diode ZD2 is a voltage-stabilizing diode.

[0007] As a further technical solution of the present invention: the MOS tube Q3 is an N-channel MOSFET.

[0008] As a further technical solution of the present invention: the MOS tube Q4 is a P-channel MOSFET.

[0009] As a further technical solution of the present invention: the MOS tube Q5 is an N-channel MOSFET.

[0010] As a further technical solution of the present invention: the transistor Q6 is a JFET.

[0011] As a further technical solution of the present invention: the diode D7, the diode D8, the diode D9 and the diode D10 form a full-bridge rectifier circuit.

[0012] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0013] The present invention can realize the driving of N-channel SiC power MOSFET and has gate active clamping and overvoltage clamping, thereby meeting the driving requirements of SiC power MOSFET. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a driving power circuit diagram of Embodiment 1;

[0015] Figure 2 This is an isolation driving circuit diagram of Embodiment 1;

[0016] Figure 3 This is a driving power circuit diagram of Embodiment 2;

[0017] Figure 4 This is the isolation driving circuit diagram of embodiment 2. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Embodiment 1, as Figure 1-2As shown, a driving circuit of a SiC power MOSFET uses a power isolation transformer, a power IC, a driving isolation IC, a resistor, a capacitor, a voltage regulator, a diode, a MOS tube, and a JFET field effect tube as main components. The control signal is converted through this circuit and the driving function of the SiC power MOS is realized.

[0020] The output side of the isolation transformer is connected in series through a bridge rectifier structure composed of diodes D7, D8, D9, and D10. Electrolytic capacitors EC3 and EC4 are connected in series, with the positive electrode connected to the positive electrode of the rectifier diode and the negative electrode connected to the negative electrode of the rectifier diode. The middle is connected as the common end of the power output, which is the driving power ground S. Resistor R4 and voltage regulator ZD2 are also connected in series, and capacitors C5 and C6 are also connected in series, with the middle connection points connected to the driving power ground S. The anode of the voltage regulator is connected to the anode of the rectifier diode, which serves as the output end VEE-4.5V of the negative power supply. The other end of the resistor R4 is connected to the cathode of the rectifier diode, which serves as the output end VCC+18V of the positive power supply.

[0021] The output high side HO of the isolation IC is connected to the gate terminal of the N-channel MOSFET Q3, the drain of Q3 is connected to the output terminal VCC+18V of the positive power supply, and the source is connected to the turn-on drive resistor Rgon2. The turn-on drive resistor Rgon2 is connected in series with the turn-off drive resistor Rgoff2. The middle point is the SIC power device drive output terminal G-MOS, which is connected to the gate of the driven SICMOS power device. The output low side LO of the isolation IC is connected to the gate terminal of the P-channel MOSFET Q4. The drain of Q4 is connected to the output terminal VEE-4.5V of the negative power supply, and the source is connected to the other end of the turn-off drive resistor Rgoff2. The middle point of the series connection of Rgoff2 and Rgon2 is the SIC power device drive output terminal. One end of the gate protection resistor R2 is connected to the output terminal G-MOS, and the other end is connected to the drive power ground S. At the same time, an absorption capacitor C2 and a discharge P-channel JFET Q6 are connected in parallel. The source of JFET Q6 is connected to the output terminal G-MOS, the drain is connected to the drive power ground S, and the gate is connected to the source of the N-channel MOSFET Q5. The gate of MOSFET Q5 is connected to the output terminal G-MOS, and the drain is connected to the output terminal VCC+18V of the positive power supply. The anode of diode D2 is connected to the output terminal G-MOS, and the cathode is connected to the output terminal VCC+18V of the positive power supply.

[0022] Here’s how it works:

[0023] The power conversion circuit of the SIC power device driving circuit is composed of power management IC, isolation transformer, diodes D7, D8, D9, D10, resistor R4, voltage regulator ZD2, filter capacitors EC3, EC4, C5, C6. 24V is used as the power input of the conversion circuit, and the power is converted into +18V and -4.5V positive and negative driving power to meet the SIC drive. The control signal conversion and the drive of the SIC power device are composed of the drive isolation IC, MOSFET Q3, Q4, Q5, JFET Q6, resistors Rgon2, Rgoff2, resistor R2, capacitor C2, and diode D2. The DRV drive signal is used as the input, which is converted into isolated high and low side drive signals through the isolation drive IC. After amplification by the MOSFET, the G-MOS drive signal is output to drive the SIC power device.

[0024] The power management chip makes the input power +24V generate the corresponding electromotive force on the secondary side through the isolation transformer, and generates a 22.5V power supply through the bridge rectifier composed of diodes D7, D8, D9, and D10. Then, the voltage is divided by resistor R4 and voltage regulator ZD2 to form two stable +18V and -4.5V separate power supplies. Finally, the filter capacitors EC3 and EC4 are used for filtering and storage, and the filter capacitors C5 and C6 are used to process the burrs of the two separate +18V and -4.5V power supplies, which become the positive and negative power supplies used by the SIC drive circuit.

[0025] The control signal generates two outputs, high-side HO and low-side LO, through the driver isolation IC. HO is valid at high level and LO is valid at low level. To control the N-channel SIC power device to turn on, the control signal DRV is high level, and after passing through the driver isolation IC, HO is output at high level, so that the Q3 N-channel MOSFET is turned on. The positive drive power supply +18V passes through Q3 and flows through the turn-on drive resistor Rgon2 to charge the gate of the N-channel SIC power device, turning on the N-channel SIC power device. When the voltage of the gate of the N-channel SIC power device exceeds the positive drive power supply +18V, the current flows from the gate of the SIC power device through the D2 diode to the positive drive power supply +18V, thereby clamping the gate voltage of the SIC power device. To control the N-channel SIC power device to turn off, the control signal DRV is low level, and after passing through the driver isolation IC, LO is output at low level, and HO is invalid level, so that the Q4 P-channel MOSFET is turned on and the Q3 N-channel MOSFET is turned off. At this time, the voltage of the gate of the SIC power device is connected to the output terminal VEE-4.5V of the negative power supply through the turn-off drive resistor Rgoff2 and Q4 MOSFET, and the gate charge of the SIC power device flows to the output terminal VEE-4.5V of the negative power supply, so that the gate of the SIC power device is at a negative voltage, and the SIC power device is turned off.

[0026] When the SIC power device is connected in series as a half-bridge, the upper and lower tubes are in a complementary state. When the upper tube is turned on, the lower tube is turned off, and when the lower tube is turned on, the upper tube is turned off, otherwise a direct short circuit will be formed. When the two tubes are switched, dead time is usually reserved to ensure that the tube that was originally turned on is turned off first, and then the tube that was originally turned off is turned on. Even if the dead time has been reserved, due to the fast switching speed of the SIC power device, when the turn-off dV / dt is large, the parasitic capacitance Cgd between the gate and drain of the MOS often causes the charge of the drain to flow to the gate through Cgd. At this time, although the gate of the SIC power device is connected to the output terminal VEE-4.5V of the negative power supply, there is a turn-off drive resistor Rgoff2 and the on-resistance of the Q4 MOSFET. At the same time, the gate capacitance Cgs collects charge, causing the gate of the SIC power device to slowly rise, causing the turned-off SIC power device to turn on again, forming a short circuit with the other SIC power device that has been turned on, causing the power circuit to be damaged. To avoid this kind of fault from damaging the circuit, the gate of the SIC power device is usually actively clamped. In this circuit, the active clamping of the gate of the SIC power device is achieved by Q6 JFET. When the SIC power device is turned off, Q4 MOSFET is turned on, so that Q4 MOSFET is low level, Q5 N-channel MOSFET is turned off, the gate and source voltage of Q6 JFET is low level, the JFET channel resistance is low resistance, JFET is in the on state, the gate of the SIC power device is connected to the source, so that the charge of the gate flows directly to the source, ensuring that the gate of the SIC power device is low level, and the SIC power device in the off state is reliably turned off. When the SIC power device is turned on, the gate of the SIC power device is high level, slightly lower than +18V, Q5MOSFET is turned on, so that Q6 JFET produces a large channel resistance, blocking communication, and JFET is turned off, ensuring that the voltage of the gate of the SIC power device does not leak, and the SIC power device is reliably turned on. Since the switching speed of SIC power devices is fast, the di / dt and dV / dt during switching are large, which will generate glitch harmonics. A 1nF filter capacitor is added closest to the gate of the SIC power device to filter out the glitch.

[0027] Embodiment 2, as Figure 2-4 As shown, this patent is a driving circuit for an N-channel SiC power MOSFET, and the driving circuit for a P-channel SiC power MOSFET can still be easily implemented by slightly adjusting the device. For those skilled in the art, they can still modify the technical solution of the present invention.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0029] In addition, it should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment have also been appropriately combined to form other implementation modes that are easy for those skilled in the art to understand.

Claims

1. A driving circuit of a SiC power MOSFET, comprising a power management IC, a driving isolation IC, an isolation transformer W, a voltage regulator tube ZD2, a MOS tube Q3, a MOS tube Q4 and a MOS tube Q5, characterized in that: The power management IC is connected to the winding Np of the isolation transformer W, one end of the winding Ns of the transformer W is connected to the positive electrode of the diode D7 and the negative electrode of the diode D8, the other end of the winding Ns of the transformer W is connected to the positive electrode of the diode D9 and the negative electrode of the diode D10, the negative electrode of the diode D7 is connected to the negative electrode of the diode D9, the capacitor EC3, the resistor R4, the capacitor C5, the drain of the MOS tube Q3, the drain of the MOS tube Q5 and the negative electrode of the diode D2, the positive electrode of the diode D8 is connected to the positive electrode of the diode D10, the positive electrode of the diode ZD2, the drain of the MOS tube Q4, the capacitor EC4 and the capacitor C6, and the other end of the capacitor EC3 is connected to the other end of the resistor R4 and the negative electrode of the diode ZD2. , the other end of capacitor C5, the other end of capacitor EC4 and the other end of capacitor C6, the source of MOS tube Q3 is connected to resistor Rgon2, the source of MOS tube Q4 is connected to resistor Rgoff2, the gate of MOS tube Q3 is connected to the drive isolation IC, the gate of MOS tube Q4 is connected to the drive isolation IC, the drive isolation IC is also connected to the control signal DRV, the other end of resistor Rgon2 is connected to the other end of resistor Rgoff2, resistor R2, capacitor C2, the positive electrode of diode D2, the gate of MOS tube Q5 and the drain of transistor Q6, the source of MOS tube Q5 is connected to the gate of transistor Q6, and the source of transistor Q6 is connected to the other end of resistor R2 and the other end of capacitor C2.

2. A SiC power MOSFET driving circuit according to claim 1, characterized in that: The diode ZD2 is a voltage stabilizing diode.

3. A SiC power MOSFET driving circuit according to claim 1, characterized in that: The MOS tube Q3 is an N-channel MOSFET.

4. A SiC power MOSFET driving circuit according to claim 1, characterized in that: The MOS tube Q4 is a P-channel MOSFET.

5. A SiC power MOSFET driving circuit according to claim 4, characterized in that: The MOS tube Q5 is an N-channel MOSFET.

6. A SiC power MOSFET driving circuit according to claim 1, characterized in that: The transistor Q6 is a JFET.

7. The driving circuit of a SiC power MOSFET according to claim 1, characterized in that: The diode D7, the diode D8, the diode D9 and the diode D10 form a full-bridge rectifier circuit.

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