CN113937989B - Driving circuit and method for suppressing SiC MOSFET crosstalk and drain current overshoot - Google Patents

Abstract

The invention relates to the technical field of wide bandgap semiconductor device driving, and discloses a driving circuit for inhibiting SiCMOSFET crosstalk and drain current overshoot, wherein a supply voltage source V2-H is introduced into a basic driving circuit of an upper bridge arm, and a supply voltage source V2-L is introduced into a basic driving circuit of a lower bridge arm and a crosstalk and overshoot inhibiting circuit. The voltage of the capacitor C2 is stabilized through the driving circuit, and the voltage of the common-source parasitic inductance ls_L is clamped, so that the decoupling of the ls_L is realized. The invention does not introduce additional active devices and controllers, and has high reliability; the structure is simple without introducing excessive transistors; the driving circuit does not introduce extra capacitance and resistance, and the switching speed is not affected; the influence caused by parasitic inductance of the source end is restrained, negative-pressure turn-off is added, misleading possibly existing in the device is avoided, crosstalk voltage and drain current overshoot phenomena of the gate source are restrained, meanwhile, the time of switching in a loop through the switch control capacitor is controlled, and extra power loss is avoided as much as possible.

Description

Driving circuit and method for suppressing SiC MOSFET crosstalk and drain current overshoot

technical field

The invention relates to the technical field of driving wide bandgap semiconductor devices, in particular to a driving circuit and method for suppressing SiC MOSFET crosstalk and drain current overshoot.

Background technique

As a representative device of the third-generation wide bandgap semiconductor, SiC MOSFET has significant advantages such as fast switching speed, low turn-off loss, and high withstand voltage. It is an effective way to improve the performance of power converters such as efficiency and power density. However, due to the high switching speed of SiC MOSFET and the existence of parasitic capacitance, no matter the change of current or voltage will cause the change of gate potential. Especially the parasitic inductance at the source end, when crosstalk occurs, it will cause a great change in the potential of the source end, which will cause interference to the gate and source, thus affecting the working status of the MOS tube. In severe cases, it may cause false conduction of the device or even damage. At the same time, the drain current also has a current overshoot problem due to the influence of parasitic parameters, and excessive drain current may also cause damage to the device. Therefore, in the SiC MOSFET bridge circuit, it is necessary to pay attention to the problems of crosstalk and drain current overshoot.

CN113315354A discloses a low-impedance clamp drive circuit for suppressing SiC MOSFET crosstalk, including a SiC MOSFET upper bridge arm and a SiC MOSFET lower bridge arm, and each bridge arm includes a basic drive circuit and a crosstalk suppression circuit to ensure that the same bridge arm In , the SiC MOSFET will not be falsely turned on when positive crosstalk occurs, and reverse breakdown will not occur when negative crosstalk occurs. However, the crosstalk suppression structure of the CN113315354A technical solution is mainly located at both ends of the gate and source of the MOSFET, and additional resistance and capacitance are introduced into the driving circuit, which will affect the switching speed of the MOSFET.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a driving circuit and method for suppressing SiC MOSFET crosstalk and drain current overshoot.

In order to achieve the above objectives, the present invention relates to a driving circuit for suppressing SiC MOSFET crosstalk and drain current overshoot, and the specific scheme is as follows:

The drive circuit for suppressing SiC MOSFET crosstalk and drain current overshoot includes SiC MOSFET upper bridge arm and lower bridge arm. The upper bridge arm only has the basic drive circuit, and the lower bridge arm includes the basic drive circuit and crosstalk and overshoot suppression circuits. A power supply voltage source V2_H is introduced into the basic drive circuit of the upper bridge arm, the negative pole of the power supply voltage source V2_H is simultaneously connected to the source of the switch tube S2_H and one end of the auxiliary capacitor C3, and the positive pole of the power supply voltage source V2_H is simultaneously connected to the power supply The negative pole of the voltage source V1_H and one end of the common source parasitic inductance Ls_H; the power supply voltage source V2_L is introduced into the basic drive circuit of the lower bridge arm and the crosstalk and overshoot suppression circuit, and the negative pole of the power supply voltage source V2_L is connected to the switch tube at the same time The source of S2_L and one end of the auxiliary capacitor C2, and the anode of the supply voltage source V2_L are simultaneously connected to the cathode of the supply voltage source V1_L, one end of the common source parasitic inductance Ls_L, one end of the capacitor C1 and the cathode of the diode D2.

Further, the basic driving circuit of the upper bridge arm also includes a switch tube S1_H and a gate resistor R4, the anode of the power supply voltage source V1_H is connected to the drain of the switch tube S1_H, and the negative pole of the power supply voltage source V1_H is connected to the drain of the upper bridge arm One end of the common-source parasitic inductance Ls_H is connected, and the other end of the common-source parasitic inductance Ls_H is connected to one end of the auxiliary capacitor C3 and the source of the SiC MOSFET M1; the source of the switching tube S1_H is connected to one end of the gate resistor R4 and the switching tube The drain of S2_H is connected; the other end of the gate resistor R4 is connected to the gate of SiC MOSFET M1.

Further, the basic drive circuit of the lower bridge arm includes a switch tube S1_L and a gate resistor R1, the anode of the power supply voltage source V1_L is connected to the drain of the switch tube S1_L, the negative pole of the power supply voltage source V1_L is connected to the drain of the lower bridge arm One end of the common-source parasitic inductance Ls_L is connected, and the other end of the common-source parasitic inductance Ls_L is connected to the other end of the auxiliary capacitor C2 and the source of the SiC MOSFET M2; the source of the switching tube S1_L is connected to one end of the gate resistor R1 and the switching tube The drain of S2_L is connected; the other end of the gate resistor R1 is connected to the gate of SiC MOSFET M2.

Further, the crosstalk and overshoot suppression circuit of the lower bridge arm further includes a diode D1, a diode D2, a diode D3, a resistor R2, a resistor R3 and a transistor Q1, the cathode of the diode D1 is connected to the drain of the SiC MOSFET and the transistor Q1 The collector of the diode D1 is connected to one end of the resistor R3 and the base of the transistor Q1, the other end of the resistor R3 is connected to the emitter of the transistor Q1, one end of the resistor R2 is connected to the positive electrode of the diode D2, and the other end of the resistor R2 Connected to the other end of the capacitor C1; the cathode of the diode D2 is also connected to one end of the common source parasitic inductance Ls_L, one end of the diode D3 is connected to the drain of the SiC MOSFET M2; the other end of the diode D3 is connected to one end of the common source parasitic inductance Ls_L.

Preferably, the switching tube S1_H, the switching tube S2_H, the switching tube S1_L, the switching tube S2_L, and the transistor Q1 are all NPN transistors.

Preferably, the turn-on voltage in the basic driving circuit is 18V, and the turn-off voltage is -5V.

Another aspect of the present invention relates to a method for suppressing crosstalk and drain current overshoot of a SiC MOSFET.

The method for suppressing SiC MOSFET crosstalk and drain current overshoot, using the drive circuit for suppressing SiC MOSFET crosstalk and drain current overshoot of the present invention, when the drain current overshoot occurs in the lower bridge arm, the reverse current flowing through the diode D1 Increase, so that the transistor Q1 is turned on, the capacitor C1 absorbs the drain current, suppresses the overshoot of the drain current, and reduces the Miller capacitor current flowing through the SiC MOSFETM2, so that the gate crosstalk is reduced.

Further, voltage sources V2_H and V2_L are introduced to stabilize the voltage of the capacitor C2 and clamp the voltage of the common-source parasitic inductance Ls_L to realize the decoupling of Ls_L.

Further, the switching signals controlling the switch S1_H and the switch S2_H are complementary, and the switching signals controlling the switch S1_L and the switch S2_L are complementary.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention does not introduce additional active devices and controllers, and has high reliability; does not introduce too many transistors, and has a simple structure; does not introduce additional capacitors and resistors in the drive circuit, and the switching speed is not affected;

(2) The driving circuit of the present invention not only suppresses the influence caused by the parasitic inductance of the source terminal, but also increases the negative voltage shutdown, avoids the possible false conduction of the device, and suppresses the gate-source crosstalk voltage and the drain current overshoot. At the same time, the switch controls the time when the capacitor is connected to the loop to avoid additional power loss as much as possible.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is a driving circuit diagram shown in the present invention;

Figure 2 is the switching waveform of the traditional drive circuit ("gate voltage Vg-time t" characteristic curve);

Fig. 3 is a switching waveform ("gate voltage Vg-time t" characteristic curve) among the present invention;

Fig. 4 is the drain current waveform of the traditional driving circuit;

Fig. 5 is drain current waveform among the present invention;

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

As shown in Figure 1, a driving circuit for suppressing SiC MOSFET crosstalk and drain current overshoot includes SiC MOSFET upper bridge arm and lower bridge arm, the upper bridge arm only has the basic driving circuit, and the lower bridge arm includes the basic driving circuit and crosstalk , Overshoot suppression circuit.

The basic driving circuit of the upper bridge arm includes a power supply voltage source V1_H, a power supply voltage source V2_H, a switch tube S1_H, a switch tube S2_H, a gate resistor R4, and an auxiliary capacitor C3. The positive pole of the power supply voltage source V1_H is connected to the drain of the switch tube S1_H; the negative pole of the power supply voltage source V1_H is connected to one end of the common source parasitic inductance Ls_H of the upper bridge arm; the other end of the common source parasitic inductance Ls_H is connected to one end of the auxiliary capacitor C3 and The source of the SiC MOSFET M1 is connected; the source of the switch tube S1_H is connected to one end of the gate resistor R4 and the drain of the switch tube S2_H; the other end of the gate resistor R4 is connected to the gate of the SiC MOSFET M1; the switch tube S2_H The source is connected to the other end of the auxiliary capacitor C3 and the negative pole of the power supply voltage source V2_H; the positive pole of the power supply voltage source V2_H is connected to the negative pole of the power supply voltage source V1_H and one end of the common source parasitic inductance Ls_H.

The basic driving circuit of the lower bridge arm includes a power supply voltage source V1_L, a power supply voltage source V2_L, a switch tube S1_L, a switch tube S2_L, a gate resistor R1, and an auxiliary capacitor C2; the positive pole of the power supply voltage source V1_L is connected to the drain of the switch tube S1_L; The negative pole of the supply voltage source V1_H is connected to one end of the common-source parasitic inductance Ls_L of the lower bridge arm; the other end of the common-source parasitic inductance Ls_L is connected to one end of the auxiliary capacitor C2 and the source of the SiC MOSFET M2; the source of the switch tube S1_L is connected to One end of the gate resistor R1 is connected to the drain of the switch tube S2_L; the other end of the gate resistor R1 is connected to the gate of the SiC MOSFET M2; the source of the switch tube S2_L is connected to the other end of the auxiliary capacitor C2 and the power supply voltage source V2_L The negative poles are connected; the positive pole of the power supply voltage source V2_L is connected with the negative pole of the power supply voltage source V1_L and one end of the common source parasitic inductance Ls_L.

The crosstalk and overshoot suppression circuit of the lower bridge arm includes a diode D1, a diode D2, a diode D3, a resistor R2, a resistor R3, a transistor Q1, and a capacitor C1; the cathode of the diode D1 is connected to the drain of the SiC MOSFET and the collector of the transistor Q1; The anode of the diode D1 is connected to one end of the resistor R3 and the base of the transistor Q1; the other end of the resistor R3 is connected to the emitter of the transistor Q1, one end of the resistor R2, and the anode of the diode D2; the other end of the resistor R2 is connected to one end of the capacitor C1 connected; the other end of capacitor C1 is connected to one end of common source parasitic inductance Ls_L and the positive pole of supply voltage source V2_L; the cathode of diode D2 is connected to one end of common source parasitic inductance Ls_l and the positive pole of power supply voltage source V2_L; one end of diode D3 is connected to SiC MOSFET The drains of M2 are connected; the other end of the diode D3 is connected to one end of the common-source parasitic inductance Ls_L.

Wherein, the switching tube S1_H, the switching tube S2_H, the switching tube S1_L, the switching tube S2_L, and the transistor Q1 are all NPN transistors.

The turn-on voltage of the basic driving circuit in this embodiment is 18V, and the turn-off voltage is -5V.

The method for suppressing SiC MOSFET crosstalk and drain current overshoot, using the drive circuit for suppressing SiC MOSFET crosstalk and drain current overshoot of the present invention, when the drain current overshoot occurs in the lower bridge arm, the reverse current flowing through the diode D1 Increase, so that the transistor Q1 is turned on, the capacitor C1 absorbs the drain current, suppresses the overshoot of the drain current, and reduces the Miller capacitor current flowing through the SiC MOSFETM2, so that the gate crosstalk is reduced.

The present invention introduces the voltage sources V2_H and V2_L to stabilize the voltage of the capacitor C2 at -5V, and clamp the voltage of the common source parasitic inductance Ls_L to realize the decoupling of Ls_L and greatly reduce the parasitic at the source end of the power loop Inductance, to reduce the crosstalk caused by the induced voltage caused by the parasitic inductance of the source.

The switching signals for controlling the switch S1_H and the switch S2_H are complementary, and the switching signals for controlling the switch S1_L and the switch S2_L are complementary. When the switch S1_L is open, the switch S2_L is closed to provide a negative voltage to the MOSFET to speed up the turn-off speed. At the same time, turning off the negative voltage can prevent false conduction caused by crosstalk. Specifically, when the forward crosstalk occurs, the reverse current of the diode D1 suddenly increases, and the increased reverse current flows through the resistor R3, generating a voltage drop, which makes the transistor Q1 turn on, providing a low-impedance branch , the current at the drain terminal is absorbed by the capacitor C1, which can reduce the overshoot phenomenon of the drain current, and at the same time reduce the current flowing through the Miller capacitor to the gate, reduce the voltage drop generated on the gate resistor, and suppress the forward crosstalk.

When the reverse crosstalk comes, the switch S1_L is turned off and the switch S2_L is turned on. At this time, the -5V voltage source can directly clamp the gate and source of the MOSFET to suppress the reverse crosstalk.

Figure 2 shows the switching waveform of the traditional drive circuit, Figure 3 shows the switching waveform of the present invention, Figure 4 shows the drain current waveform of the traditional drive circuit, and Figure 5 shows the drain current waveform of the present invention. It can be seen that both positive and negative crosstalk voltage spikes are suppressed.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (6)

1. The driving circuit for inhibiting the crosstalk of the SiC MOSFET and the overshoot of the drain current is characterized by comprising an upper bridge arm and a lower bridge arm of the SiC MOSFET, wherein the upper bridge arm is only provided with a basic driving circuit, the lower bridge arm comprises a basic driving circuit and a crosstalk and overshoot inhibiting circuit, a power supply voltage source V2-H is introduced into the basic driving circuit of the upper bridge arm, the negative electrode of the power supply voltage source V2-H is simultaneously connected with the source of a switch tube S2-H and one end of an auxiliary capacitor C3, and the positive electrode of the power supply voltage source V2-H is simultaneously connected with the negative electrode of the power supply voltage source V1-H and one end of a common source parasitic inductance Ls-H; introducing a power supply voltage source V2-L into the basic driving circuit and the crosstalk and overshoot suppression circuit of the lower bridge arm, wherein the negative electrode of the power supply voltage source V2-L is simultaneously connected with the source electrode of the switching tube S2-L and one end of the auxiliary capacitor C2, and the positive electrode of the power supply voltage source V2-L is simultaneously connected with the negative electrode of the power supply voltage source V1-L, one end of the common source parasitic inductance Ls-L, one end of the capacitor C1 and the negative electrode of the diode D2;

the basic driving circuit of the upper bridge arm comprises a switching tube S1_H and a grid resistor R4, wherein the positive electrode of a power supply voltage source V1_H is connected with the drain electrode of the switching tube S1_H, the negative electrode of the power supply voltage source V1_H is connected with one end of a common source parasitic inductance ls_H of the upper bridge arm, and the other end of the common source parasitic inductance ls_H is connected with the other end of an auxiliary capacitor C3 and the source electrode of a SiC MOSFET M1; the source electrode of the switching tube S1_H is connected with one end of the grid resistor R4 and the drain electrode of the switching tube S2_H; the other end of the gate resistor R4 is connected with the gate of the SiC MOSFET M1;

the basic driving circuit of the lower bridge arm comprises a switching tube S1_L and a grid resistor R1, wherein the positive electrode of a power supply voltage source V1_L is connected with the drain electrode of the switching tube S1_L, the negative electrode of the power supply voltage source V1_L is connected with one end of a common source parasitic inductance ls_L of the lower bridge arm, and the other end of the common source parasitic inductance ls_L is connected with the other end of an auxiliary capacitor C2 and the source electrode of a SiC MOSFET M2; the source electrode of the switching tube S1_L is connected with one end of the grid resistor R1 and the drain electrode of the switching tube S2_L; the other end of the gate resistor R1 is connected with the gate of the SiC MOSFET M2;

the crosstalk and overshoot suppression circuit of the lower bridge arm further comprises a diode D1, a diode D2, a diode D3, a resistor R2, a resistor R3 and a triode Q1, wherein the cathode of the diode D1 is connected with the drain electrode of the SiC MOSFET and the collector electrode of the triode Q1, the anode of the diode D1 is connected with one end of the resistor R3 and the base electrode of the triode Q1, the other end of the resistor R3 is connected with the emitter electrode of the triode Q1, one end of the resistor R2 and the anode of the diode D2, and the other end of the resistor R2 is connected with the other end of the capacitor C1; the cathode of the diode D2 is also connected with one end of the common-source parasitic inductance ls_L, and one end of the diode D3 is connected with the drain electrode of the SiC MOSFET M2; the other end of the diode D3 is connected to one end of the common-source parasitic inductance ls_l.

2. The driving circuit for suppressing crosstalk and drain current overshoot of a SiC MOSFET according to claim 1, wherein said switching transistors s1_h, s2_h, s1_l, s2_l, Q1 are NPN transistors.

3. The drive circuit for suppressing SiC MOSFET crosstalk and drain current overshoot of claim 1, wherein the on voltage in said basic drive circuit is 18V and the off voltage is-5V.

4. A method for suppressing SiC MOSFET crosstalk and drain current overshoot, wherein the driving circuit for suppressing SiC MOSFET crosstalk and drain current overshoot according to claim 1 is used, and when the lower arm generates drain current overshoot, the reverse current flowing through diode D1 increases, so that transistor Q1 is turned on, capacitor C1 absorbs drain current, suppresses drain current overshoot, and reduces miller capacitance current flowing through SiC MOSFET M2, so that gate crosstalk is reduced.

5. A method for suppressing SiC MOSFET crosstalk and drain current overshoot, characterized by employing a driving circuit for suppressing SiC MOSFET crosstalk and drain current overshoot according to any one of claims 1-3, introducing voltage sources v2_h and v2_l, stabilizing the voltage of capacitor C2, and clamping the voltage of common source parasitic inductance ls_l, to achieve decoupling of ls_l.

6. The method of suppressing SiC MOSFET crosstalk and drain current overshoot of claim 5, wherein the switching signals controlling switch s1_h and switch s2_h are complementary and the switching signals controlling switch s1_l and switch s2_l are complementary.