CN104506028A - SiC MOSFET (Metal Oxide Semiconductor Field Effect Transistor) half-bridge circuit driver and half-bridge circuit drive method - Google Patents

Abstract

The invention discloses a SiC MOSFET half-bridge circuit driver and a half-bridge circuit driving method, comprising: a negative voltage generation circuit and a crosstalk elimination circuit; the negative voltage generation circuit and the crosstalk elimination circuit are connected in series, and the crosstalk elimination circuit includes a MOSFET A switch tube and a second RC parallel circuit connected in series with the MOSFET switch tube, the second RC parallel circuit includes a resistor R2 and a capacitor C2 connected in parallel. Beneficial effects of the present invention: the drive circuit of the present invention generates negative pressure through passive devices, which reduces the use of negative voltage power supplies and saves costs; at the same time, it effectively solves the negative pressure spikes caused by the half-bridge unit crosstalk on the drive signal, reducing the The risk of SiC device damage due to gate-source negative pressure exceeding the limit value.

Description

A kind of SiC MOSFET half-bridge circuit driver and half-bridge circuit driving method

technical field

The invention relates to a SiC MOSFET half-bridge circuit driver and a half-bridge circuit driving method with negative pressure shutdown.

Background technique

As a wide bandgap semiconductor material, SiC material has good physical and chemical properties such as large band gap, high breakdown voltage, and high thermal conductivity. In recent years, with the increasing maturity of SiC materials, the application of SiC devices in the field of power electronics has attracted widespread attention. Among them, SiC MOSFET is favored by researchers for its high withstand voltage and high switching frequency. Due to the inherent characteristics of SiC MOSFET, the design of its driving circuit is different from that of Si material MOSFET. On the one hand, in order to increase the switching frequency of the device and reduce the turn-off time, negative voltage needs to be considered in the design of the driver. On the other hand, the negative voltage that the gate-source of SiC MOSFET can withstand is small, so the negative voltage cannot exceed its maximum Negative pressure value. In addition, since conventional two-level inverters are based on half-bridge circuit units, the mutual influence of the parasitic parameters of the two switching tubes of the half-bridge circuit under high dv/dt conditions, that is, crosstalk, cannot be ignored.

At present, the design of most drivers is to add a negative voltage power supply on the basis of the original Si MOSFET driver, which increases the design cost, and does not consider the influence of the half-bridge circuit crosstalk on the driving signal, resulting in gate-source negative voltage spikes It exceeds the maximum range that SiC MOSFET can withstand.

Contents of the invention

The purpose of the present invention is exactly in order to solve above-mentioned problem, has proposed a kind of SiC MOSFET half-bridge circuit driver and half-bridge circuit driving method with negative pressure shut-off, this structure produces negative pressure through the use of passive device, has reduced cost; Simultaneously Under the premise of not affecting the switching speed of the switching tube of the main circuit, the negative voltage spike brought by the crosstalk of the half-bridge circuit to the driving signal is eliminated.

In order to achieve the above object, the present invention adopts the following technical solutions:

A SiC MOSFET half-bridge circuit driver, comprising: a negative voltage generation circuit and a crosstalk elimination circuit; the negative voltage generation circuit and the crosstalk elimination circuit are connected in series, and the crosstalk elimination circuit includes a MOSFET switch tube and a MOSFET switch tube connected in series A second RC parallel circuit is connected, and the second RC parallel circuit includes a resistor R2 and a capacitor C2 connected in parallel.

The negative pressure generating circuit comprises: a power supply, a triode Su, a triode Sd and an RC parallel circuit one; the triode Su and the triode Sd are push-pull connected and connected in series at both ends of the power supply, and one end of the RC parallel circuit one is connected Between the triode Su and the triode Sd, the other end is connected to the crosstalk elimination circuit; the RC parallel circuit one includes a resistor R1 and a capacitor C1 connected in parallel.

When the triode Su is turned on, the triode Sd is turned off; when the triode Su is turned off, the triode Sd is turned on.

A SiC MOSFET half-bridge circuit applying the driver, comprising: an upper bridge arm driver and an upper bridge arm of a SiC MOSFET half-bridge circuit connected thereto, a lower bridge arm driver and a lower bridge arm of a SiC MOSFET half-bridge circuit connected thereto; The upper and lower bridge arms of the MOSFET half-bridge circuit are connected in series;

The driver of the upper bridge arm includes: the triode SHu and the triode SHd are push-pull connected, and connected in series at both ends of the power supply VH, one end of the parallel circuit composed of the resistor R1_H and the capacitor C1_H is connected between the triode SHu and the triode SHd, and the other end is divided into Two circuits, one of which is connected to the upper bridge arm of the SiC MOSFET half-bridge circuit, and the other is connected in series with the parallel circuit composed of the MOSFET switch tube and the resistor R2_H and the capacitor C2_H;

The driver of the lower bridge arm includes: the triode SLu and the triode SLd are push-pull connected, and connected in series at both ends of the power supply VL, one end of the parallel circuit composed of the resistor R1_L and the capacitor C1_L is connected between the triode SLu and the triode SLd, and the other end is divided into Two circuits, one of which is connected to the lower bridge arm of the SiC MOSFET half-bridge circuit, and the other is a parallel circuit composed of a MOSFET switch tube, a resistor R2_L and a capacitor C2_L in series.

A method for driving a SiC MOSFET half-bridge circuit, comprising:

During the period from t0 to t1, the switch SHu and the switch SLu are turned on, the switch SHd, the switch SHa, the switch SLd, and the switch SLa are turned off, and the capacitors C1_H, C2_H, C1_L, and C2_L are pre-charged. To provide negative pressure, the voltage is adjusted by setting the values of R1_H, R2_H, R1_L, and R2_L;

During the period from t1 to t2, the switches SHu and SLu are turned off, the switches SHd and SLd are turned on, and the capacitors C1_H and C1_L provide negative pressure for the upper and lower arms of the SiC MOSFET half-bridge circuit;

At time t2, the switching tube SHu is turned on, and SHd is turned off, so that the upper bridge arm of the SiC MOSFET half-bridge circuit starts to conduct, and the switching tubes SHa and SLa are always in the off state. Since the parasitic capacitance of the switching tube SHa is small, it will not affect The conduction speed of the switch tube of the upper bridge arm;

During the period from t3 to t4, the switching tube SHu is turned on, SHd is turned off, the upper bridge arm is turned on, and the lower bridge arm is turned off, and the capacitor C1_L continues to provide negative pressure for the lower tube;

During the period from t4 to t5, the switching tubes SHd, SLd, and SLa are turned on, the other switching tubes are turned off, and the upper bridge arm starts to turn off. At t5, the upper bridge arm is completely turned off, and the switching tube SLa is turned off;

During the time period from t5 to t6, the switch tubes SHd and SLd are turned on, the other switch tubes are turned off, and both the upper bridge arm and the lower bridge arm are in the off state, waiting for the arrival of the next switching cycle.

The beneficial effects of the present invention are:

The driving circuit of the present invention generates negative pressure through passive devices, reduces the use of negative voltage power supply, and saves costs; at the same time, it effectively solves the negative pressure peak caused by the half-bridge unit crosstalk on the driving signal, and reduces the negative voltage caused by the gate-source negative voltage. If the voltage exceeds the limit value, there is a risk of damage to the SiC device.

Description of drawings

Fig. 1 is the schematic diagram of circuit structure of the present invention;

Fig. 2 is the functional detection circuit of the present invention;

Fig. 3 is a logic diagram of the drive signal of the present invention;

Figure 4(a)-(f) are the equivalent diagrams of circuit work in each period respectively.

Detailed ways:

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

The topological structure of the SiC MOSFET half-bridge circuit driver of the present invention is shown in Figure 1, including: a negative voltage generation circuit and a crosstalk elimination circuit; the negative voltage generation circuit and the crosstalk elimination circuit are connected in series, and the crosstalk elimination circuit includes a MOSFET switch tube And a second RC parallel circuit connected in series with the MOSFET switching tube, the second RC parallel circuit includes a resistor R2 and a capacitor C2 connected in parallel.

The negative pressure generating circuit includes: a power supply, a triode Su, a triode Sd, and an RC parallel circuit one; the triode Su and the triode Sd are push-pull connected and connected in series at both ends of the power supply, and one end of the RC parallel circuit one is connected to the triode Between Su and the transistor Sd, the other end is connected to the crosstalk elimination circuit; the RC parallel circuit one includes a resistor R1 and a capacitor C1 connected in parallel.

The two triodes Su and Sd are push-pull connections, resistors R1 and R2 act as voltage dividers, C1 is used to generate negative voltage, Sa and C2 are used to eliminate the influence of half-bridge circuit crosstalk on the driving signal.

FIG. 2 is a schematic diagram of the application of the present invention to a half-bridge circuit. Including: the upper bridge arm driver and the upper bridge arm of the SiC MOSFET half-bridge circuit connected to it, the lower bridge arm driver and the lower bridge arm of the SiC MOSFET half-bridge circuit connected to it; the upper bridge arm and the lower bridge arm of the SiC MOSFET half-bridge circuit are connected in series ;

The driver of the upper bridge arm includes: the triode SHu and the triode SHd are push-pull connected, and connected in series at both ends of the power supply VH, one end of the parallel circuit composed of the resistor R1_H and the capacitor C1_H is connected between the triode SHu and the triode SHd, and the other end is divided into two circuits , one of which is connected to the upper bridge arm of the SiC MOSFET half-bridge circuit, and the other is connected in series with the parallel circuit composed of MOSFET switch tube, resistor R2_H and capacitor C2_H;

The driver of the lower bridge arm includes: the transistor SLu and the transistor SLd are push-pull connected, and connected in series at both ends of the power supply VL, one end of the parallel circuit composed of the resistor R1_L and the capacitor C1_L is connected between the transistor SLu and the transistor SLd, and the other end is divided into two circuits , one of which is connected to the lower bridge arm of the SiC MOSFET half-bridge circuit, and the other is connected in series with a parallel circuit composed of a MOSFET switch tube, a resistor R2_L and a capacitor C2_L.

The advantages of this drive circuit over conventional MOSFET drives will be described in detail below in conjunction with the drive signal logic in FIG. 3 .

During the period from t0 to t1, as shown in Figure 4(a), the switches SHu and SLu are turned on, the switches SHd, SHa, SLd, and SLa are turned off, and the capacitors C1_H, C2_H, and C1_L , C2_L for pre-charging, C1_H, C1_L for providing negative voltage, the voltage can be adjusted by setting the value of R1_H, R2_H, R1_L, R2_L.

The period from t1 to t2 is the initialization stage, as shown in Figure 4(b), the switches SHu and SLu are turned off, the switches SHd and SLd are turned on, and the capacitors C1_H and C1_L are the gate-source of the upper and lower arm SiC MOSFETs of the main circuit The negative voltage is provided to the two poles, so that the two switching tubes are in the off state and the main circuit is powered on.

During the period from t2 to t3, as shown in Figure 4(c), the switch SHu is turned on at t2, and SHd is turned off, so that the upper bridge arm of the SiC MOSFET half-bridge circuit starts to conduct, and the auxiliary switches SHa and SLa are always off. In the off state, since the parasitic capacitance of the switching tube SHa is small, it will not affect the conduction speed of the switching tube of the upper bridge arm. For ordinary drivers, due to crosstalk, the lower bridge arm will produce a positive peak on Cgs_L, causing the wrong conduction of the lower bridge arm of the half-bridge circuit. The present invention avoids this situation from two aspects. On the one hand, through SLa and C2_L branch to reduce the positive peak, on the other hand, C1_L provides negative pressure can also reduce the probability of false conduction of the lower bridge arm, and the upper bridge arm is completely turned on at time t3.

During the period from t3 to t4, as shown in Figure 4(d), during this period the switch SHu is turned on, SHd is turned off, the upper bridge arm is turned on and the lower bridge arm is turned off, and the capacitor C1_L continues to provide negative pressure for the lower transistor until t4 At this moment, the upper bridge arm starts to turn off.

During the period from t4 to t5, as shown in Figure 4(e), due to the freewheeling effect of the inductor at time t4, the drive signal of the lower half of the bridge arm will produce a negative peak, which is superimposed with the negative pressure signal of the drive itself, which is very easy to cause The negative pressure exceeds the limit value, causing damage to the SiC MOSFET. In the present invention, by closing the switch tube SLa, since the capacitance of C2_L is greater than that of Cgs_L, a low impedance loop can be provided, thereby eliminating the influence of the negative voltage peak on the MOSFET. During this period, the switching tubes SHd, SLd, and SLa are turned on, and the other switching tubes are turned off.

During the time period from t5 to t6, as shown in FIG. 4(f), the switching tubes SHd and SLd are turned on, and the other switching tubes are turned off. Both the upper bridge arm and the lower bridge arm are in the off state, waiting for the arrival of the next switching cycle.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (5)

1. A SiC MOSFET half-bridge circuit driver, characterized in that it comprises: a negative voltage generation circuit and a crosstalk elimination circuit; the negative voltage generation circuit and a crosstalk elimination circuit are connected in series, and the crosstalk elimination circuit includes a MOSFET switch tube and a The second RC parallel circuit is connected in series with the MOSFET switch tubes, and the second RC parallel circuit includes a resistor R2 and a capacitor C2 connected in parallel. 2. A kind of SiC MOSFET half-bridge circuit driver as claimed in claim 1, it is characterized in that, described negative pressure generating circuit comprises: power supply, triode Su, triode Sd and RC parallel circuit one; Described triode Su and triode Sd Push-pull connection, and connected in series at both ends of the power supply, one end of the RC parallel circuit one is connected between the triode Su and the triode Sd, and the other end is connected with the crosstalk elimination circuit; the RC parallel circuit one includes resistors connected in parallel R1 and capacitor C1. 3. A SiC MOSFET half-bridge circuit driver as claimed in claim 2, characterized in that, when the triode Su is turned on, the triode Sd is turned off; when the triode Su is turned off, the triode Sd is turned on. 4. A SiC MOSFET half-bridge circuit applying the driver according to claim 1, characterized in that it comprises: an upper bridge arm driver and an upper bridge arm of the SiC MOSFET half bridge circuit connected thereto, a lower bridge arm driver and a SiC MOSFET connected thereto The lower bridge arm of the half-bridge circuit; the upper and lower bridge arms of the SiC MOSFET half-bridge circuit are connected in series; The driver of the upper bridge arm includes: the triode SHu and the triode SHd are push-pull connected, and connected in series at both ends of the power supply VH, one end of the parallel circuit composed of the resistor R1_H and the capacitor C1_H is connected between the triode SHu and the triode SHd, and the other end is divided into Two circuits, one of which is connected to the upper bridge arm of the SiC MOSFET half-bridge circuit, and the other is connected in series with the parallel circuit composed of the MOSFET switch tube and the resistor R2_H and the capacitor C2_H; The driver of the lower bridge arm includes: the triode SLu and the triode SLd are push-pull connected, and connected in series at both ends of the power supply VL, one end of the parallel circuit composed of the resistor R1_L and the capacitor C1_L is connected between the triode SLu and the triode SLd, and the other end is divided into Two circuits, one of which is connected to the lower bridge arm of the SiC MOSFET half-bridge circuit, and the other is a parallel circuit composed of a MOSFET switch tube, a resistor R2_L and a capacitor C2_L in series. 5. A method for driving a SiC MOSFET half-bridge circuit as claimed in claim 4, characterized in that it comprises: During the period from t0 to t1, the switch SHu and the switch SLu are turned on, the switch SHd, the switch SHa, the switch SLd, and the switch SLa are turned off, and the capacitors C1_H, C2_H, C1_L, and C2_L are pre-charged. To provide negative pressure, the voltage is adjusted by setting the values of R1_H, R2_H, R1_L, and R2_L; During the period from t1 to t2, the switches SHu and SLu are turned off, the switches SHd and SLd are turned on, and the capacitors C1_H and C1_L provide negative pressure for the upper and lower arms of the SiC MOSFET half-bridge circuit; At time t2, the switching tube SHu is turned on, and SHd is turned off, so that the upper bridge arm of the SiC MOSFET half-bridge circuit starts to conduct, and the switching tubes SHa and SLa are always in the off state. Since the parasitic capacitance of the switching tube SHa is small, it will not affect The conduction speed of the switch tube of the upper bridge arm; During the period from t3 to t4, the switching tube SHu is turned on, SHd is turned off, the upper bridge arm is turned on, and the lower bridge arm is turned off, and the capacitor C1_L continues to provide negative pressure for the lower tube; During the period from t4 to t5, the switching tubes SHd, SLd, and SLa are turned on, the other switching tubes are turned off, and the upper bridge arm starts to turn off. At t5, the upper bridge arm is completely turned off, and the switching tube SLa is turned off; During the time period from t5 to t6, the switch tubes SHd and SLd are turned on, the other switch tubes are turned off, and both the upper bridge arm and the lower bridge arm are in the off state, waiting for the arrival of the next switching cycle.