Bridge arm crosstalk suppression circuit for reducing reverse conduction loss of GaN device

Abstract

The invention discloses a bridge arm crosstalk suppression circuit for reducing reverse conduction loss of a GaN device, and belongs to the technical field of power electronics and electricians. According to the circuit, a negative voltage circuit capable of inhibiting forward crosstalk is connected in series in a driving circuit, an auxiliary MOS tube is connected in series in a reverse direction on the driving positive voltage circuit, and the negative voltage circuit is isolated from the driving circuit by controlling the auxiliary MOS tube to be switched on in dead time, so that the reverse conduction loss is reduced. When forward crosstalk is generated, the auxiliary MOS tube is controlled to be switched off, the negative voltage circuit is connected to the driving circuit, negative voltage is provided for a gate source capacitor of the GaN device, meanwhile, a low-impedance loop is provided for forward crosstalk current, and forward bridge arm crosstalk is restrained. When negative crosstalk is generated, a low-impedance loop is provided for negative crosstalk current, and negative bridge arm crosstalk is suppressed. The reverse conduction loss of the GaN device can be reduced while positive and negative crosstalk is suppressed, and the method is suitable for all bridge arm type circuit topologies.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics and electrical engineering, and particularly relates to a bridge arm crosstalk suppression circuit for reducing reverse conduction loss of a GaN device. TECHNICAL BACKGROUND

[0002] Compared with traditional Si devices, eGaN HEMT has lower on-resistance, smaller junction capacitance, faster switching speed and better high-temperature working ability, supports high-frequency and high-efficiency operation, significantly improves the maximum working frequency and efficiency of the converter, reduces the volume and weight, and has a broad market prospect in high-power density and high-frequency converters.

[0003] But higher switching frequency means greater dv / dt, and the gate-source threshold voltage of eGaN HEMT is lower, which is more sensitive to the parasitic parameters of the circuit, and is prone to false conduction. Moreover, the negative voltage that eGaN HEMT can withstand is smaller than that of Si devices, which may exceed the maximum gate-source negative voltage range, resulting in device damage or accelerated performance degradation.

[0004] At present, the related researches on bridge arm crosstalk suppression methods at home and abroad mainly fall into two categories:

[0005] Firstly, control the gate drive impedance; by connecting an external capacitor in parallel between the gate and source of the switch tube to provide a low-impedance branch for the Miller current. Although this method reduces the crosstalk voltage, it increases the equivalent capacitance between the gate and source, reduces the switching speed of the power device, and increases the switching loss.

[0006] Secondly, use negative voltage to turn off; by applying a negative voltage between the gate and source to prevent false turn-on of the device. However, for eGaN HEMT, this method increases the reverse conduction loss of the dead time, and makes the negative crosstalk voltage amplitude increase, and the negative crosstalk occurs to a certain extent.

[0007] Therefore, in order to fully exert the application advantages of eGaN HEMT in high-power density and high-frequency converters, it is necessary to continue to study a more optimized crosstalk suppression method.

[0008] For the control gate drive impedance crosstalk suppression method, in addition to the theoretical analysis of the gate-source series capacitor caused by the slow switching speed, and further caused the problem of increased switching loss, due to the low threshold voltage of eGaN HEMT, this suppression measure has inhibitory effect on the positive crosstalk during the on period, but there is still the risk of exceeding the threshold voltage due to oscillation, leading to the mis-conduction of the switch tube. Therefore, in actual application, generally, on the basis of adopting this crosstalk suppression measure, negative voltage off is adopted, so as to reduce the harm caused by positive crosstalk, and make the whole system work more safely and reliably, but due to the unique reverse conduction characteristic of GaN device, the negative gate-source voltage will increase the reverse conduction loss of the dead time, and the deeper the negative voltage, the greater the source-drain voltage, and the greater the reverse conduction loss.

[0009] The present patent proposes a bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of GaN device, aiming at the problems of crosstalk deterioration and increased reverse conduction loss caused by the crosstalk suppression method of eGaN HEMT bridge arm negative voltage off. SUMMARY

[0010] In view of the deficiencies of the prior art, the purpose of the present application is to provide a bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of GaN device, which can reduce the reverse conduction loss of GaN device without an additional isolated negative voltage source, and suppress positive and negative crosstalk. The present application adopts the following technical solutions to achieve the above purpose:

[0011] The bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of GaN device comprises an upper bridge arm circuit, which comprises an upper drive negative voltage circuit considering parasitic parameters, an upper drive positive voltage circuit, an upper drive negative voltage isolation circuit and an upper power circuit. 1H The upper drive negative voltage circuit comprises an auxiliary capacitor C 1H , a resistor R 3H and a diode D 4H , wherein the auxiliary capacitor C 1H and the resistor R 1H are connected in parallel to provide a drive negative voltage for the gate, and at the same time provide a low impedance loop for the negative crosstalk current, and the diode D 4H isolates the resistor R 3H from the auxiliary capacitor C 3H , so that the resistor R 1H does not affect the charging process of the auxiliary capacitor C 2H ; the upper drive positive voltage circuit comprises an auxiliary capacitor C 2H , a resistor R 1H and a diode D 2H , wherein the auxiliary capacitor C 2H and the resistor R 1H are connected in parallel to provide a drive positive voltage for the gate, and at the same time provide a low impedance loop for the positive crosstalk current, and the diode D 2HThe energy stored above is only through resistor R 2H Consumption; the upper drive negative voltage isolation circuit includes an auxiliary MOSFET S 1H diode D 2H diode D 3H Auxiliary MOSFET S 1H The auxiliary MOSFET S is connected in reverse series in the positive driving circuit to control the positive driving voltage circuit. 1H Turning on isolates the drive negative voltage circuit from the drive circuit, controlling the auxiliary MOSFET S. 1H The negative voltage circuit is switched off and connected to the drive circuit; the upper power circuit includes a power transistor M. H Gate resistance R gH Gate-source capacitance C gsH Gate-drain capacitance C gdH Drain-source capacitance C dsH Among them, power transistor M H Gate-source capacitance C gsH Gate-drain capacitance C gdH Drain-source capacitance C dsH Together they form the GaN device of the upper bridge arm;

[0012] The lower bridge arm circuit is the same as the upper bridge arm. The lower bridge arm circuit of the bridge arm crosstalk suppression circuit includes a lower drive negative voltage circuit considering parasitic parameters, a lower drive positive voltage circuit, a lower drive negative voltage isolation circuit, and a lower power circuit; the lower drive negative voltage circuit includes an auxiliary capacitor C. 1L Resistance R 1L Resistance R 3L diode D 4L The auxiliary capacitor C 1L and resistance R 1L The parallel connection provides a driving negative voltage to the gate and a low-impedance loop for the negative crosstalk current. Diode D 4L Isolation resistor R 3L Make the resistor R 3L It does not affect the auxiliary capacitor C 1L The charging process; the lower driving positive voltage circuit includes an auxiliary capacitor C 2L Resistance R 2L Diode D 1L The auxiliary capacitor C 2L and resistance R 2L The parallel connection provides a positive drive voltage to the gate and a low-impedance loop for the forward crosstalk current. Diode D 1L This makes the auxiliary capacitor C 2L The energy stored is obtained only through resistor R 2L Consumption; the lower drive negative voltage isolation circuit includes an auxiliary MOSFET S 1L Diode D 2L diode D 3L Auxiliary MOSFET S1L The auxiliary MOS tube S 1L is turned on to isolate the driving negative voltage circuit from the driving circuit, and the auxiliary MOS tube S 1L is turned off to connect the driving negative voltage circuit to the driving circuit. L The power tube M gL , the gate-source capacitor C gsL , the gate-drain capacitor C gdL , and the drain-source capacitor C dsL together constitute a GaN device of the lower bridge arm. L The power tube M gsL , the gate-source capacitor C gdL , and the drain-source capacitor C dsL together constitute a GaN device of the upper bridge arm.

[0013] The control method of the bridge arm crosstalk suppression circuit comprises the following steps: providing a driving positive voltage for the gate-source of the power tube by using the driving positive voltage circuit; providing a driving negative voltage for the gate-source of the power tube by using the driving negative voltage circuit, without an additional isolated negative voltage source; turning on the auxiliary MOS tube in the dead time to isolate the driving negative voltage circuit from the driving circuit, so that the gate-source voltage of the GaN device is 0V in the dead time, thereby reducing the reverse conduction loss of the GaN device; when positive crosstalk occurs, turning off the auxiliary MOS tube to connect the driving negative voltage circuit to the driving circuit, thereby providing a negative voltage for the gate-source capacitor of the GaN device and providing a low-impedance loop for the positive crosstalk current, thereby suppressing the positive bridge arm crosstalk; when negative crosstalk occurs, providing a low-impedance loop for the negative crosstalk current, thereby suppressing the negative bridge arm crosstalk.

[0014] Further, the auxiliary MOS tube S 1H and S 1L are required to be selected as follows: the on-resistance R DS(on) is less than or equal to 50 mΩ, and the switching time is less than or equal to 50 ns.

[0015] Further, during the turning-on process of the upper bridge arm circuit, the voltage source V sH charges the auxiliary capacitors C 1H and C 2H , wherein the resistors R 1H and R 2H provide preset negative voltages for the auxiliary capacitors C 1H and C 2H , and the stable voltage division values of the auxiliary capacitors C 1H and C 2H are as follows:

[0016]

[0017] wherein the diodes D 1H and D 3H are connected in parallel., D 4H are in forward conducting state, diode D 4H is shorted. 3H

[0018] Further, the upper bridge arm power tube M H is turned off at the same time, the auxiliary MOS tube S 1H is turned on, the negative voltage circuit is isolated from the driving circuit, the gate-source voltage V H of the power tube M gsH is clamped to 0V, reducing the reverse conducting loss of the GaN device; the auxiliary capacitor C 1H consumes energy through the resistor R 1H , the resistor R 3H parallel branch and the auxiliary MOS tube S 3H continues to flow, the diode D 1H is reverse blocked, and the energy consumed on the auxiliary capacitor C 2H is on the resistor R 2H , compared with the negative voltage V gsH in the dead time, the reduced reverse conducting loss is:

[0019] P reverse_loss_saved =2ΔV gsH I dH T dead f

[0020] Where ΔV gsH is the gate-source voltage change, I dH is the drain current, T dead is the dead time, and f is the switching frequency.

[0021] Further, the lower bridge arm power tube M L is turned on at the same time, the auxiliary MOS tube S 1H is turned off, the negative voltage circuit is connected to the driving circuit, and the negative voltage is provided for the gate-source capacitor C H of the power tube M gsH ; the lower bridge arm power tube M L is turned on at the moment, the induced current direction generated on the gate-drain capacitor C gdH in the upper bridge arm circuit is from the drain to the gate, and part of the current flows to the gate-source capacitor C gsH to generate crosstalk voltage, and part of the current flows through the auxiliary capacitor C 2H branch to reduce the induced current flowing through the gate-source capacitor C gsH , that is, to reduce the forward crosstalk voltage on the gate-source capacitor C gsH at this time.

[0022] Further, after the lower bridge arm power tube M L is turned on, the auxiliary MOS tube S 1H ​Turn on, the upper bridge arm power tube M H Gate-source voltage V gsH Clamped to 0V; the lower bridge arm power tube M L Turn off, auxiliary MOS tube S 1H Turn off, at this time, the auxiliary capacitor C 1H The energy stored on the resistor R 1H , the resistor R 3H The drain-source voltage V dgL Rises, the drain current I dH Of the upper bridge arm circuit falls, the output capacitor C ossH Of the upper bridge arm circuit is charged, and its gate-drain capacitor C gdH Induces a displacement current I gdH In the opposite direction of the turn-on period, through the gate two branch shunt, part of the current generates a positive-negative crosstalk voltage at the gate-source capacitor C gsH , part of the current flows through the auxiliary capacitor C1 branch, reduces the negative crosstalk voltage on the gate-source capacitor C gsH .

[0023] The technical scheme adopted by the present application has the following technical effects compared with the prior art:

[0024] (1) The bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of the GaN device provided by the present application, by using an RC voltage dividing circuit, can provide negative voltage for the gate-source capacitor of the main power tube under the condition that only positive voltage is provided by the external driving chip, compared with the traditional negative voltage off circuit, an additional negative voltage source is not needed;

[0025] (2) The bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of the GaN device provided by the present application, in view of the problem of increased reverse conduction loss of the GaN device in the dead time in the traditional bridge arm crosstalk negative voltage off suppression method, by using an auxiliary MOS tube to isolate the negative voltage loop in the dead time, the gate-source voltage of the main power tube is clamped to 0V, thereby reducing the reverse conduction loss of the GaN device in the dead time;

[0026] (3) The bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of the GaN device provided by the present application, in view of the problem that the negative crosstalk voltage starts to drop from the negative voltage in the traditional bridge arm crosstalk negative voltage off suppression method, by using an auxiliary MOS tube to isolate the negative voltage loop, after the energy stored on the negative voltage loop is consumed, the negative crosstalk current flows through the low-impedance path, thereby reducing the negative crosstalk voltage. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The schematic diagram of the bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of the GaN device in the present application;

[0028] Figure 2 The upper and lower tube driving voltage and upper tube gate-source voltage waveform when the lower tube of the bridge arm circuit in the application is turned on and turned off are shown in the schematic diagram;

[0029] Figure 3 The driving signal and auxiliary MOS tube switching timing diagram of the bridge arm circuit in the application are shown in the schematic diagram;

[0030] Figure 4 The current loop schematic diagram for charging the voltage dividing capacitor in the upper tube driving circuit before the lower tube is turned on in the application is shown in the schematic diagram;

[0031] Figure 5 The current loop schematic diagram for isolating the driving negative voltage circuit and clamping the gate-source voltage to 0V during the dead time in the application is shown in the schematic diagram;

[0032] Figure 6 The upper bridge arm driving negative voltage circuit and the positive forward crosstalk induced current flow direction when the lower tube is turned on in the application are shown in the schematic diagram;

[0033] Figure 7 The negative forward crosstalk induced current flow direction when the lower tube is turned off in the application is shown in the schematic diagram. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0035] The bridge arm crosstalk suppression circuit for reducing the reverse conduction loss of a GaN device, and a control method thereof, provide driving positive voltage for the gate-source of the power tube by using a driving positive voltage circuit; provide driving negative voltage for the gate-source of the power tube by using a driving negative voltage circuit, without an additional isolated negative voltage source, isolate the driving negative voltage circuit from the driving circuit by controlling the auxiliary MOS tube to be turned on during the dead time, so that the gate-source voltage of the GaN device is 0V during the dead time, and the reverse conduction loss of the GaN device is reduced; when positive forward crosstalk occurs, control the auxiliary MOS tube to be turned off, connect the driving negative voltage circuit to the driving circuit, provide negative voltage for the gate-source capacitor of the GaN device, and at the same time provide a low-impedance loop for the positive forward crosstalk current, to suppress the positive forward bridge arm crosstalk; when negative forward crosstalk occurs, provide a low-impedance loop for the negative forward crosstalk current, to suppress the negative forward bridge arm crosstalk.

[0036] The driving circuit used in the method is shown in FIG. 1, which includes an upper driving negative voltage circuit, an upper driving positive voltage circuit, an upper driving negative voltage isolation circuit, and an upper power circuit, taking into account the parasitic parameters. Figure 1 The upper driving negative voltage circuit includes an auxiliary capacitor C1H , resistor R 1H , resistor R 3H , diode D 4H , wherein the auxiliary capacitor C 1H and the resistor R 1H are connected in parallel to provide a driving negative voltage for the gate and a low impedance loop for the negative crosstalk current, the diode D 4H is connected in series to isolate the resistor R 3H from the auxiliary capacitor C 3H , so that the resistor R 1H does not affect the charging process of the auxiliary capacitor C 2H ; the upper driving positive voltage circuit comprises an auxiliary capacitor C 2H , a resistor R 1H , and a diode D 2H , wherein the auxiliary capacitor C 2H and the resistor R 1H are connected in parallel to provide a driving positive voltage for the gate and a low impedance loop for the positive crosstalk current, the diode D 2H is connected in series to make the energy stored on the auxiliary capacitor C 2H only consumed by the resistor R 1H ; the upper driving negative voltage isolation circuit comprises an auxiliary MOS tube S 2H , a diode D 3H , and an auxiliary MOS tube S 1H connected in reverse series on the driving positive voltage circuit, which is isolated from the driving circuit by turning on the auxiliary MOS tube S 1H , and is connected to the driving circuit by turning off the auxiliary MOS tube S 1H ; the upper power circuit comprises a power tube M H , a gate resistor R gH , a gate-source capacitor C gsH , a gate-drain capacitor C gdH , and a drain-source capacitor C dsH , wherein the power tube M H , the gate-source capacitor C gsH , the gate-drain capacitor C gdH , and the drain-source capacitor C dsH together constitute a GaN device of the upper bridge arm.

[0037] The lower bridge arm circuit is the same as the upper bridge arm, and the lower bridge arm circuit of the bridge arm crosstalk suppression circuit comprises a lower driving negative voltage circuit, a lower driving positive voltage circuit, a lower driving negative voltage isolation circuit, and a lower power circuit considering parasitic parameters; the lower driving negative voltage circuit comprises an auxiliary capacitor C 1L , a resistor R 1L , a resistor R 3L , and a diode D 4L , wherein the auxiliary capacitor C 1L and the resistor R 1LThe parallel connection provides a driving negative voltage to the gate and a low-impedance loop for the negative crosstalk current. Diode D 4L Isolation resistor R 3L Make the resistor R 3L It does not affect the auxiliary capacitor C 1L The charging process; the lower driving positive voltage circuit includes an auxiliary capacitor C 2L Resistance R 2L Diode D 1L The auxiliary capacitor C 2L and resistance R 2L The parallel connection provides a positive drive voltage to the gate and a low-impedance loop for the forward crosstalk current. Diode D 1L This makes the auxiliary capacitor C 2L The energy stored is obtained only through resistor R 2L Consumption; the lower drive negative voltage isolation circuit includes an auxiliary MOSFET S 1L Diode D 2L diode D 3L Auxiliary MOSFET S 1L In reverse series connection under the positive voltage driving circuit, the auxiliary MOSFET S is controlled. 1L Turning on isolates the drive negative voltage circuit from the drive circuit, controlling the auxiliary MOSFET S. 1L The negative voltage circuit is switched off and connected to the drive circuit; the lower power circuit includes a power transistor M. L Gate resistance R gL Gate-source capacitance C gsL Gate-drain capacitance C gdL Drain-source capacitance C dsL Among them, power transistor M L Gate-source capacitance C gsL Gate-drain capacitance C gdL Drain-source capacitance C dsL Together, they form the GaN device in the lower bridge arm. The auxiliary MOSFET S... 1H S 1L The specific selection requirements are as follows: on-resistance R DS(on) ≤50mΩ, switching time ≤50ns.

[0038] like Figure 2 The diagram shows the waveforms of the driving voltages of the upper and lower transistors and the gate-source voltage of the upper transistor when the lower transistor in the bridge arm circuit of this invention is turned on and off. A detailed analysis is then provided regarding the steady-state conduction and turn-off of the upper transistor and the turn-on and turn-off of the lower transistor:

[0039] The [t0-t1] phase refers to the period before the lower pipe is opened, and the upper pipe M... H It is in a steady-state conduction state. Auxiliary power transistor S 1H When in the off state, the upper bridge arm voltage source V sH For auxiliary capacitor C 1H C2H Pre-charge, using R 1H and R 2H Two resistors to divide voltage for C 1H to provide a preset negative voltage value, so that it provides enough negative voltage when the positive crosstalk caused by the lower tube open. Auxiliary capacitor C 1H and C 2H The stable voltage is:

[0040]

[0041] Wherein, diode D 1H , D 3H , D 4H are in the forward conducting state, diode D 4H short R 3H . As Figure 4 The current loop schematic diagram of the application before the lower tube open, the auxiliary circuit of the upper tube capacitor is pre-charged.

[0042] [t1-t2] stage for the pre-dead time, the upper tube M H off, auxiliary MOS S 1H open, will drive negative voltage circuit, do not provide negative voltage C gsH , V gsH clamped to 0V; diode D 1H is in the reverse blocking state, the energy on C 2H through R 2H consumption. Because of the reverse conducting characteristics of eGaN HEMT, the load current at this time reverse through M H , because V gsH clamped to 0V, greatly reduces the reverse conduction loss in the pre-dead time. As Figure 5 The current loop schematic diagram of the application in the dead time isolation drive negative voltage circuit, the gate-source voltage clamped to 0V, compared with the dead time V gsH for negative pressure, the reduced reverse conduction loss is:

[0043] P reverse_loss_saved = 2ΔV gsH I dH T dead f

[0044] Where ΔV gsH is the gate-source voltage variation, I dH is the upper tube drain current, T dead is the dead time, f is the switching frequency.

[0045] [t2-t3] stage for the lower tube M LStart to turn on until steady state conduction, at time t2, the lower tube M L Gate-source voltage V gsL To drive positive pressure, the lower tube M L Turn on, at this time, the auxiliary power tube S 1H Turn off, C 1H To C gsH Provide a preset negative pressure. The lower tube opens at the moment, M L The drain-source voltage V dsL Drop, the upper tube M H The drain-source voltage V dsH Rise, high dv / dt and M H The gate-drain capacitance C gdH Coupling generates positive cross-talk current I gdH , the output capacitance C ossH Of the upper tube is charged, and the current is shunted to flow through the drive circuit and the gate-source capacitance C gsH Of the upper tube, C gsH The positive cross-talk voltage is generated between the two ends, which rises from the preset negative pressure, and in this stage, the diode D 1H Forward conduction, providing a low impedance loop for the cross-talk induced current, which alleviates the bridge arm shoot-through problem caused by the forward cross-talk in the transient period. As Figure 6 The lower tube opens, the upper bridge arm drive negative voltage circuit and the forward cross-talk induced current flow diagram.

[0046] [t3-t4] stage is the lower tube M L Fully on state, forward cross-talk ends, auxiliary power tube S 3H Turn on, the gate-source voltage V gsH Of the upper tube is clamped to 0V, the auxiliary capacitor C 1H Parallel resistance R 1H And R 3H , diode D 4H Reverse stop, D 2H Forward conduction, C 1H The energy storage on R 1H And R 3H Consumed.

[0047] [t4-t5] stage is the post-dead time, at time t4, the lower tube M L Turn off, auxiliary MOS tube S 1H Turn off, at this time, the auxiliary capacitor C 1H The energy stored on R 1H , resistance R 3H Has been completely consumed, the drain-source voltage V L Of M gdL Rise, the upper tube M H The drain-source voltage V gdHfalling, high dv / dt and M H gate leakage capacitor C gdH a negative crosstalk current I gdH is coupled out in the direction opposite to the on period, which charges the output capacitor C ossH of the upper transistor, and also flows through the drive circuit of the upper transistor, is divided in two branches through the gate, and part of it generates a crosstalk voltage of upper negative and lower positive across the gate-source capacitor C gsH , and part of the current flows through the auxiliary capacitor C 1H branch, reducing the negative crosstalk voltage across the gate-source capacitor C gsH at this time. As shown in Figure 7 is a schematic diagram of the negative crosstalk induced current flow of the upper bridge arm when the lower transistor is turned off according to the present application.

[0048] As shown in Figure 3 is a timing diagram of the PWM and auxiliary MOS transistor of the bridge arm circuit in the present application, which is analyzed by taking the upper transistor steady-state on and off and the lower transistor on and off as examples, i.e. [t0-t5] stage. At t0, the upper bridge arm voltage source V sH provides operating voltage for the upper transistor, and pre-charges the auxiliary capacitors C 1H , C 2H , and the auxiliary power transistor S 1H is turned off. At t1, the upper transistor M H is turned off, S 1H is turned on, the negative voltage loop and the drive circuit are isolated, V gsH is clamped to 0V, reducing the reverse conduction loss during the dead time of the upper transistor. At t2, S 1H is turned off, the negative voltage loop is connected to the drive circuit, providing a preset negative voltage for C gsH , so that the positive crosstalk starts to rise from the preset negative voltage value, suppressing the positive crosstalk voltage. At t3, S 1H is turned on, and the energy stored in C 1H is consumed through R 1H and R 3H . At t4, S 1H is turned off, part of the negative crosstalk current flows through the auxiliary capacitor C 1H branch, reducing the negative crosstalk voltage across the gate-source capacitor C gsH at this time.

[0049] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions described in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A bridge leg crosstalk suppression circuit to reduce reverse conduction losses of a GaN device, characterized in that, The upper bridge arm circuit of the bridge arm crosstalk suppression circuit includes an upper driving negative voltage circuit considering parasitic parameters, an upper driving positive voltage circuit, an upper driving negative voltage isolation circuit, and an upper power circuit; the upper driving negative voltage circuit includes an auxiliary capacitor C. 1H Resistance R 1H Resistance R 3H diode D 4H The auxiliary capacitor C 1H and resistance R 1H The parallel connection provides a driving negative voltage to the gate and a low-impedance loop for the negative crosstalk current. Diode D 4H Isolation resistor R 3H Make the resistor R 3H It does not affect the auxiliary capacitor C 1H The charging process; the upper driving positive voltage circuit includes an auxiliary capacitor C 2H Resistance R 2H diode D 1H The auxiliary capacitor C 2H and resistance R 2H The parallel connection provides a positive drive voltage to the gate and a low-impedance loop for the forward crosstalk current. Diode D 1H This makes the auxiliary capacitor C 2H The energy stored above is only through resistor R 2H Consumption; the upper drive negative voltage isolation circuit includes an auxiliary MOSFET S 1H diode D 2H diode D 3H Auxiliary MOSFET S 1H The auxiliary MOSFET S is connected in reverse series in the positive driving circuit to control the positive driving voltage circuit. 1H Turning on isolates the drive negative voltage circuit from the drive circuit, controlling the auxiliary MOSFET S. 1H The negative voltage circuit is switched off and connected to the drive circuit; the upper power circuit includes a power transistor M. H Gate resistance R gH Gate-source capacitance C gsH Gate-drain capacitance C gdH Drain-source capacitance C dsH Among them, power transistor M H Gate-source capacitance C gsH Gate-drain capacitance C gdH Drain-source capacitance C dsH Together they form the GaN device of the upper bridge arm; The lower bridge arm circuit is the same as the upper bridge arm. The lower bridge arm circuit of the bridge arm crosstalk suppression circuit includes a lower drive negative voltage circuit considering parasitic parameters, a lower drive positive voltage circuit, a lower drive negative voltage isolation circuit, and a lower power circuit; the lower drive negative voltage circuit includes an auxiliary capacitor C. 1L Resistance R 1L Resistance R 3L diode D 4L The auxiliary capacitor C 1L and resistance R 1L The parallel connection provides a driving negative voltage to the gate and a low-impedance loop for the negative crosstalk current. Diode D 4L Isolation resistor R 3L Make the resistor R 3L It does not affect the auxiliary capacitor C 1L The charging process; the lower driving positive voltage circuit includes an auxiliary capacitor C 2L Resistance R 2L diode D 1L The auxiliary capacitor C 2L and resistance R 2L The parallel connection provides a positive drive voltage to the gate and a low-impedance loop for the forward crosstalk current. Diode D 1L This makes the auxiliary capacitor C 2L The energy stored is obtained only through resistor R 2L Consumption; the lower drive negative voltage isolation circuit includes an auxiliary MOSFET S 1L diode D 2L diode D 3L Auxiliary MOSFET S 1L In reverse series connection under the positive voltage driving circuit, the auxiliary MOSFET S is controlled. 1L Turning on isolates the drive negative voltage circuit from the drive circuit, controlling the auxiliary MOSFET S. 1L The negative voltage circuit is switched off and connected to the drive circuit; the lower power circuit includes a power transistor M. L Gate resistance R gL Gate-source capacitance C gsL Gate-drain capacitance C gdL Drain-source capacitance C dsL Among them, power transistor M L Gate-source capacitance C gsL Gate-drain capacitance C gdL Drain-source capacitance C dsL Together they form the GaN device of the lower bridge arm; The control method of the bridge arm crosstalk suppression circuit provides a driving positive voltage for the gate-source of the power tube by using a driving positive voltage circuit; provides a driving negative voltage for the gate-source of the power tube by using a driving negative voltage circuit, without an additional isolated negative voltage source, and by controlling the auxiliary MOS tube to be turned on in the dead time, the driving negative voltage circuit is isolated from the driving circuit, so that the gate-source voltage of the GaN device is 0V in the dead time, and the reverse conduction loss of the GaN device is reduced; when positive crosstalk occurs, the auxiliary MOS tube is turned off, the driving negative voltage circuit is connected to the driving circuit, a negative voltage is provided for the gate-source capacitor of the GaN device, and a low-impedance loop is provided for the positive crosstalk current, thereby suppressing the positive bridge arm crosstalk; when negative crosstalk occurs, a low-impedance loop is provided for the negative crosstalk current, thereby suppressing the negative bridge arm crosstalk.

2. The bridge leg cross-talk mitigation circuit for reducing reverse conduction loss of a GaN device of claim 1, wherein, The auxiliary MOS transistor S 1H , S 1L is required to be selected as follows: the on-resistance R DS(on) ≤ 50 mΩ, and the switching time ≤ 50 ns.

3. The bridge leg cross-talk mitigation circuit for reducing reverse conduction loss of GaN devices of claim 1, wherein, In the on process of the upper bridge arm circuit, the voltage source V sH is charged through the resistor R 1H and the resistor R 2H , wherein the resistor R 1H and the resistor R 2H provide a preset negative voltage for the auxiliary capacitor C 1H and the auxiliary capacitor C 2H , and the stable voltage division values of the auxiliary capacitor C 1H and the auxiliary capacitor C 2H are respectively Wherein, diode D 1H , D 3H , D 4H are all in forward conducting state, diode D 4H shorts resistance R 3H .

4. The bridge leg cross-talk mitigation circuit for reducing reverse conduction loss of GaN devices of claim 1, wherein, The upper bridge arm power tube M H At the same time of turning off, the auxiliary MOS tube S 1H is turned on, the negative voltage circuit is isolated from the driving circuit, and the gate-source voltage V H of the power tube M gsH is clamped to 0V, thereby reducing the reverse conduction loss of the GaN device; the auxiliary capacitor C 1H consumes the energy of the auxiliary MOS tube S 1H through the resistance R 3H , the parallel branch and the auxiliary MOS tube S 3H continues to flow, the diode D 1H is reverse blocked, and the energy consumption of the auxiliary capacitor C 2H is on the resistance R 2H , compared with the reduced reverse conduction loss of V gsH being negative during the dead time. P reverse_loss_saved = 2ΔV gsH I dH T dead f where ΔV gsH is the gate-source voltage variation, I dH is the drain current, T dead is the dead time, and f is the switching frequency.

5. The bridge leg cross-talk mitigation circuit for reducing reverse conduction loss of GaN devices of claim 1, wherein, The lower bridge arm power transistor M L At the same time, the auxiliary MOS transistor S 1H is turned on, the negative voltage circuit is connected to the driving circuit, and the gate-source capacitor C H of the power transistor M gsH provides negative voltage; the lower bridge arm power transistor M L is turned on, the gate-drain capacitor C gdH in the upper bridge arm circuit generates induced current from the drain to the gate, which is shunted through the gate, and part of the current flows to the gate-source capacitor C gsH , generating crosstalk voltage, and part of the current flows through the auxiliary capacitor C 2H , reducing the induced current flowing through the gate-source capacitor C gsH , that is, reducing the positive crosstalk voltage on the gate-source capacitor C gsH .

6. The bridge leg cross-talk mitigation circuit for reducing reverse conduction loss of GaN devices of claim 1, wherein, The lower bridge arm power transistor M L After being turned on, the auxiliary MOS transistor S 1H is turned on, the upper bridge arm power transistor M H is turned on, the gate-source voltage V gsH is clamped to 0V; the lower bridge arm power transistor M L is turned off, the auxiliary MOS transistor S 1H is turned off, at this time, the energy stored in the auxiliary capacitor C 1H has been completely consumed on the resistor R 1H , the resistor R 3H , and the drain-source voltage V dgL rises, the drain current I dH of the upper bridge arm circuit falls, the output capacitor C ossH of the upper bridge arm circuit is charged, and a gate-drain capacitor C gdH is induced to produce a displacement current I gdH in the opposite direction to the period when it is turned on, which is divided into two branches at the gate, part of the current produces a positive voltage on the gate-source capacitor C gsH , and part of the current flows through the auxiliary capacitor C1 branch, reducing the negative cross-talk voltage on the gate-source capacitor C gsH .

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