A system for driving a SiC MOSFET using negative pressure generated by an auxiliary winding

Abstract

The present invention discloses a system for driving a SIC MOSFET using a negative voltage generated by an auxiliary winding, including an auxiliary winding, a first diode, a first resistor, a first capacitor and a driving chip. One end of the auxiliary winding is grounded, the other end of the auxiliary winding is connected to the negative electrode of the first diode, the positive electrode of the first diode is connected to one end of the first resistor, the other end of the first resistor is connected to the VDD- pin of the driving chip and the negative electrode of the first capacitor, the positive electrode of the first capacitor is grounded, and the GATE pin of the driving chip is connected to the gate of the SIC MOSFET tube. In this system, the driving chip can provide a stable and reliable negative voltage.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor integrated circuits, and relates to a system for driving a SIC MOSFET using a negative voltage generated by an auxiliary winding. Background Art

[0002] Since the 1990s, the rapid development of silicon carbide (SiC) MOSFET technology has attracted extensive attention to this new generation of power devices. Compared with Si materials, the higher thermal conductivity of silicon carbide materials determines their high current density characteristics, and the higher bandgap width determines the high breakdown field strength and high operating temperature of SiC devices. Especially in the development and application of SiC MOSFETs, compared with Si MOSFETs of the same power level, the on-resistance and switching losses of SiC MOSFETs are significantly reduced, suitable for higher operating frequencies. In addition, due to their high-temperature operating characteristics, the high-temperature stability is greatly improved.

[0003] In the fields of ACDC chargers and adapters, in order to be able to adapt to a wider input voltage range, more reliable high-temperature stability, and higher operating frequencies to achieve a smaller volume, SIC MOSFET power devices have become the optimal choice in some ACDC fields.

[0004] Although SIC MOSFET has many above advantages, compared with SI MOSFET, the gate turn-on voltage of SIC MOSFET is the same as that of SI MOSFET, and the gate turn-off voltage of SIC MOSFET needs to reach about -5V, while SI MOSFET only needs to reach 0V to turn off. This poses a challenge to the design of ACDC systems and driver chips.

[0005] Figure 1 For a typical application of an ACDC system driving SI MOS with a traditional structure, since the gate drive turn-off voltage of SI MOS is 0V, the driver chip only needs to have a pin GND connected to the ground of the system. The internal drive circuit will generate a GATE signal. The high level of the GATE signal is generally greater than 10V, for example, 15V, and the low level is 0V. Thus, GATE can well control the turn-on and turn-off of SI MOS. As Figure 2 is the signal schematic diagram of GATE, VAUX, and VDD+. When GATE is at a high level, VAUX = Vout * Na / Ns, where Vout is the system output voltage, Na is the number of turns of the auxiliary winding, and Ns is the number of turns of the output winding; when GATE is at a low level, VAUX = -Vline * Na / Np, where Vline is the input voltage after the rectifier bridge of the system, and Np is the number of turns of the main winding.

[0006] However, the gate turn-off voltage of SIC MOS needs to reach about -5V. In a traditional ACDC system, the driving chip cannot obtain a stable and reliable negative voltage. Summary of the Invention

[0007] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art, and provide a system for driving SIC MOSFET with a negative voltage generated by an auxiliary winding. In this system, the driving chip can provide a stable and reliable negative voltage.

[0008] To achieve the above purpose, the system for driving SIC MOSFET with a negative voltage generated by an auxiliary winding according to the present invention includes an auxiliary winding, a first diode, a first resistor, a first capacitor, and a driving chip. One end of the auxiliary winding is grounded, the other end of the auxiliary winding is connected to the negative electrode of the first diode, the positive electrode of the first diode is connected to one end of the first resistor, the other end of the first resistor is connected to the VDD- pin of the driving chip and the negative electrode of the first capacitor, the positive electrode of the first capacitor is grounded, and the GATE pin of the driving chip is connected to the gate of the SIC MOSFET.

[0009] It also includes an AC power supply, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, a second resistor, the negative electrode of the second capacitor is grounded, the positive electrodes of the second diode, the fourth diode, the second capacitor, the third capacitor, the fourth capacitor, and a transformer;

[0010] One end of the AC power supply is connected to the positive electrode of the second diode and the negative electrode of the third diode, the other end of the AC power supply is connected to the positive electrode of the fourth diode and the negative electrode of the fifth diode, the positive electrodes of the third diode, the fifth diode, and the negative electrode of the second capacitor are grounded, the positive electrodes of the second diode, the fourth diode, the positive electrode of the second capacitor, one end of the second resistor, and one end of the primary winding of the transformer are connected, the VDD+ pin of the driving chip is connected to the positive electrode of the third capacitor, the negative electrode of the sixth diode, and the other end of the second resistor, the positive electrode of the sixth diode is connected to the negative electrode of the first diode, the other end of the primary winding of the transformer is connected to the drain of the SIC MOSFET, the source of the SIC MOSFET and the GND pin of the driving chip are both grounded, one end of the secondary winding of the transformer is connected to the other end of the secondary winding of the transformer through the seventh diode and the fourth capacitor, and the negative electrode of the third capacitor is grounded.

[0011] During operation, by adjusting the resistance value of the first resistor, the voltage at VDD- in the driving chip is made -5V.

[0012] The first capacitor is used for energy storage and filtering.

[0013] The present invention has the following beneficial effects:

[0014] When the system for driving SIC MOSFET with negative voltage generated by using an auxiliary winding according to the present invention is in specific operation, a first diode, a first resistor and a first capacitor are added at one end VAUX of the auxiliary winding. Among them, the negative voltage at VAUX is sampled through the first diode, and the first resistor plays a role in current limiting. Thus, the negative voltage at the VDD- pin in the driving chip can be adjusted according to the size of the first resistor. The first capacitor plays a role in energy storage and filtering, so that the voltage at the VDD- pin in the driving chip can be stabilized. The operation is convenient and simple, and the practicability is extremely strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the traditional technology;

[0016] Figure 2 is the main ACDC signal diagram in the traditional technology;

[0017] Figure 3 is a schematic structural diagram of the present invention;

[0018] Figure 4 is the main ACDC signal diagram in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings:

[0020] Refer to Figure 3 , the system for driving SIC MOSFET with negative voltage generated by using an auxiliary winding according to the present invention includes an auxiliary winding, a first diode D1, a first resistor R1, a first capacitor C1 and a driving chip. Among them, one end of the auxiliary winding is grounded, the other end of the auxiliary winding is connected to the negative electrode of the first diode D1, the positive electrode of the first diode D1 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the VDD- pin of the driving chip and the negative electrode of the first capacitor C1, the positive electrode of the first capacitor C1 is grounded, and the GATE pin of the driving chip is connected to the gate of the SIC MOSFET tube.

[0021] The present invention further includes an AC power supply, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, a second resistor R2, the negative electrode of a second capacitor C2 is grounded, the positive electrode of the second diode D2, the positive electrode of the fourth diode D4, the second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a transformer; one end of the AC power supply is connected to the positive electrode of the second diode D2 and the negative electrode of the third diode D3, the other end of the AC power supply is connected to the positive electrode of the fourth diode D4 and the negative electrode of the fifth diode D5, the positive electrodes of the third diode D3, the fifth diode D5 and the negative electrode of the second capacitor C2 are grounded, the positive electrode of the second diode D2, the positive electrode of the fourth diode D4, the positive electrode of the second capacitor C2, one end of the second resistor R2 and one end of the primary winding in the transformer are connected, the VDD+ pin of the driving chip is connected to the positive electrode of the third capacitor C3, the negative electrode of the sixth diode D6 and the other end of the second resistor R2, the positive electrode of the sixth diode D6 is connected to the negative electrode of the first diode D1, the other end of the primary winding in the transformer is connected to the drain of the SIC MOSFET, the source of the SIC MOSFET and the GND pin of the driving chip are both grounded, one end of the secondary winding in the transformer is connected to the other end of the secondary winding in the transformer through the seventh diode D7 and the fourth capacitor C4, and the negative electrode of the third capacitor C3 is grounded.

[0022] It should be noted that the present invention innovatively adds a first diode D1, a first resistor R1 and a first capacitor C1 at one end VAUX of the auxiliary winding. Among them, the function of the first diode D1 is to sample the negative voltage at VAUX, and the first resistor R1 plays a role in current limiting, so that the negative voltage at the VDD- pin in the driving chip can be adjusted according to the size of the first resistor R1. The first capacitor C1 plays a role in energy storage and filtering, so that the voltage at the VDD- pin in the driving chip can be stabilized. Refer to Figure 4 , by adjusting the first resistor R1, the negative voltage at the VDD- pin in the driving chip is equal to -5V.

Claims

1. A system for driving a SIC MOSFET using a negative voltage generated by an auxiliary winding, characterized in that, It includes an auxiliary winding, a first diode (D1), a first resistor (R1), a first capacitor (C1), and a driving chip. One end of the auxiliary winding is grounded, and the other end of the auxiliary winding is connected to the negative electrode of the first diode (D1). The positive electrode of the first diode (D1) is connected to one end of the first resistor (R1). The other end of the first resistor (R1) is connected to the VDD- pin of the driving chip and the negative electrode of the first capacitor (C1). The positive electrode of the first capacitor (C1) is grounded. The GATE pin of the driving chip is connected to the gate of the SIC MOSFET tube. It further includes an AC power supply, a second diode (D2), a third diode (D3), a fourth diode (D4), a fifth diode (D5), a sixth diode (D6), a seventh diode (D7), a second resistor (R2), the negative electrode of the second capacitor (C2) is grounded, the positive electrodes of the second diode (D2), the fourth diode (D4), the second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4), and a transformer. One end of the AC power supply is connected to the positive electrode of the second diode (D2) and the negative electrode of the third diode (D3). The other end of the AC power supply is connected to the positive electrode of the fourth diode (D4) and the negative electrode of the fifth diode (D5). The positive electrodes of the third diode (D3), the fifth diode (D5), and the negative electrode of the second capacitor (C2) are grounded. The positive electrodes of the second diode (D2), the fourth diode (D4), the positive electrode of the second capacitor (C2), one end of the second resistor (R2), and one end of the primary winding in the transformer are connected. The VDD+ pin of the driving chip is connected to the positive electrode of the third capacitor (C3), the negative electrode of the sixth diode (D6), and the other end of the second resistor (R2). The positive electrode of the sixth diode (D6) is connected to the negative electrode of the first diode (D1). The other end of the primary winding in the transformer is connected to the drain of the SIC MOSFET tube. The source of the SIC MOSFET tube and the GND pin of the driving chip are both grounded. One end of the secondary winding in the transformer is connected to the other end of the secondary winding in the transformer through the seventh diode (D7) and the fourth capacitor (C4). The negative electrode of the third capacitor (C3) is grounded.

2. The system for driving a SIC MOSFET with negative pressure generated by using an auxiliary winding according to claim 1, wherein During operation, by adjusting the resistance value of the first resistor (R1), the voltage at VDD- in the driving chip is made -5V.

3. The system for driving SIC MOSFET with negative pressure generated by using an auxiliary winding according to claim 1, wherein The first capacitor (C1) is used for energy storage and filtering.

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