Driving circuit and switching power supply

Abstract

The invention discloses a driving circuit and a switching power supply. The driving circuit comprises a first secondary winding and a first output circuit connected with the first secondary winding; the second output circuit is connected with the second secondary winding; one end of the first secondary winding and one end of the second secondary winding are mutually different-polarity ends; each of the first output circuit and the second output circuit comprises a first charge storage unit, a first diode, a first MOS tube, a voltage limiting circuit and a negative voltage module, one end of the negative voltage module and a drain electrode of the first MOS tube are simultaneously connected with one end of the corresponding secondary winding, and the other end of the negative voltage module is connected with a grid electrode of the driven switch tube; the first end of the voltage limiting circuit and the cathode of the first diode are simultaneously connected with the other end of the corresponding secondary winding, the second end of the voltage limiting circuit is simultaneously connected with one end of the first charge storage unit and the grid electrode of the first MOS tube, and the anode of the first diode, the other end of the first charge storage unit and the source electrode of the first MOS tube are connected together for connecting the source electrode of the driven switch tube. The invention provides a low-cost and stable SiC driving circuit scheme.

Description

Technical Field

[0001] The invention belongs to the field of power electronics, and in particular relates to a drive circuit and a switching power supply. Background Art

[0002] With the development of power electronics technology, SiC MOS tubes have been widely used in many fields such as car charging, photovoltaic power generation, rail transportation, and data centers due to their advantages such as high withstand voltage, fast switching speed, and low reverse recovery. However, the gate drive voltage threshold of SiCMOS tubes is low and easily interfered with, and a stable negative voltage shutdown is required during the application process. The isolated driver IC with integrated negative voltage is costly and has limited driving capability. In addition, for the half-bridge topology, additional power supply costs are required.

[0003] like Figure 1 As shown in the figure, it is a schematic diagram of a conventional transformer driving solution, which includes a transformer isolation drive and a negative pressure module, and forms a negative pressure loop through a transistor when the drive signal is turned off. The transformer isolation drive solution is a low-cost solution, but the negative pressure value will exceed the withstand voltage limit of the SiC MOS tube, and it is difficult to achieve negative pressure shutdown during the dead time, so the reliability is low.

[0004] Figure 2 This is an improvement scheme for the existing transformer drive, but it also has shortcomings, including the loss of duty cycle, large drive current and slow switching speed. Specifically: due to the tailing effect of the transistor, although the negative voltage drive signal can be maintained during the dead time, the transistor cannot be turned off in time when the drive voltage rises, which is manifested as the loss of the drive duty cycle; in addition, during the high-frequency drive process, when the transformer drive voltage changes from low to high, the tailing effect of the transistor will cause the winding S1-transistor Qa-diode Da1 of the transformer T1 to form a current loop to generate additional drive current. The tailing effect of the transistor leads to a large drive current, which is a great burden on the transformer front-stage drive circuit, thereby slowing down the switching speed.

[0005] Patent CN 116388534 A proposes an isolated SiC drive circuit, in which the secondary side of the driving transformer forms a loop through two resistors, which will also lead to a large drive current and increase the burden on the previous stage; and when the circuit is turned off, the gate voltage of the driving switch tube u1 is relied on to turn on the discharge switch tube Q1 to form a discharge loop. When the gate voltage of the driving switch tube u1 drops below the threshold (that is, after u1 is turned off), the discharge switch tube is also turned off. Therefore, it is impossible to provide negative voltage for the driving switch tube during the dead time, so there is a problem of insufficient ability to maintain negative voltage during the dead time, which will lead to large switching losses; in addition, the gate stress of the NPN MOS used in this scheme to maintain negative voltage is consistent with the gate stress of the SiC MOS (SiC can reach a maximum of 22V), which brings great pressure to the selection of the MOS tube.

[0006] Therefore, there is an urgent need to provide a low-cost, stable SiC drive circuit solution that can fully utilize the excellent performance of SiC while bringing higher economic benefits. Summary of the invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a method that at least solves one of the technical problems existing in the prior art to a certain extent.

[0008] As a first aspect of the present invention, the technical solution of the embodiment of the driving circuit provided is as follows:

[0009] A driving circuit, comprising: a transformer core; a primary winding wound on the transformer core, used for inputting a driving signal source; a first secondary winding wound on the transformer core and a first output circuit connected thereto; a second secondary winding wound on the transformer core and a second output circuit connected thereto; one end of the first secondary winding and one end of the second secondary winding are opposite ends;

[0010] The first output circuit and the second output circuit have the same structure, and both include:

[0011] A first charge storage unit, a first diode, a first MOS tube, a voltage limiting circuit and a negative voltage module, wherein one end of the negative voltage module and the drain of the first MOS tube are simultaneously connected to one end of the corresponding secondary winding, and the other end of the negative voltage module is used to connect the gate of the driven switch tube, the first end of the voltage limiting circuit and the cathode of the first diode are simultaneously connected to the other end of the corresponding secondary winding, the second end of the voltage limiting circuit is simultaneously connected to one end of the first charge storage unit and the gate of the first MOS tube, and the anode of the first diode, the other end of the first charge storage unit and the source of the first MOS tube are connected together to connect the source of the driven switch tube;

[0012] Each output circuit forms a discharge loop for the gate capacitance of the corresponding driven switch tube by turning on the corresponding first MOS tube, and forms a negative voltage driving signal for the corresponding driven switch tube during the non-conduction time;

[0013] The negative voltage module of each output circuit, and the corresponding secondary winding, voltage limiting circuit, and first charge storage unit form a first discharge loop for the gate capacitance of the corresponding driven switch tube when the driving signal source is turned off. At the same time, the voltage limiting circuit stabilizes the driving voltage of the corresponding first MOS tube and quickly charges the corresponding first charge storage unit. The charge stored in the corresponding first charge storage unit maintains the charge required for the corresponding first MOS tube to turn on within the driving dead time.

[0014] Preferably, the first charge storage unit is a capacitor.

[0015] Preferably, the voltage limiting circuit includes a voltage stabilizing diode and a resistor, the cathode of the voltage stabilizing diode is connected to the first end of the voltage limiting circuit, the anode of the voltage stabilizing diode is connected to one end of the resistor, and the other end of the resistor is connected to the second end of the voltage limiting circuit.

[0016] Preferably, the voltage limiting circuit includes two resistors, wherein a first end of one resistor is connected to the first end and the second end of the voltage limiting circuit, and a first end of another resistor is simultaneously connected to the second end of the voltage limiting circuit, and a second end of another resistor is connected to a connection point of the anode of the first diode, the other end of the first charge storage unit and the source of the first MOS tube.

[0017] Preferably, the negative pressure module comprises a capacitor and a resistor, one end of the capacitor is connected to one end of the negative pressure module, the other end of the capacitor is connected to one end of the resistor, and the other end of the resistor is connected to the other end of the negative pressure module.

[0018] Furthermore, the negative pressure module also includes a voltage regulator diode, a cathode of the voltage regulator diode is connected to one end of the negative pressure module, and an anode of the voltage regulator diode is connected to the other end of the capacitor.

[0019] Furthermore, the negative pressure module also includes a diode, a cathode of the diode is connected to one end of the negative pressure module, and an anode of the diode is connected to the other end of the resistor.

[0020] Furthermore, the driving circuit also includes a resistor, one end of which is connected to the other end of the negative pressure module and the other end is connected to the anode of the first diode, the other end of the first charge storage unit and the connection point of the source of the first MOS tube.

[0021] Furthermore, the driving circuit also includes two voltage-stabilizing diodes, wherein the cathode of one voltage-stabilizing diode is connected to the other end of the negative pressure module, and the anode is connected to the anode of another voltage-stabilizing diode, and the cathode of the other voltage-stabilizing diode is connected to the connection point of the anode of the first diode, the other end of the first charge storage unit and the source of the first MOS tube.

[0022] Furthermore, the selection of the first MOS transistor satisfies that the first MOS transistor operates in a variable resistance region during a dead time between switching of the input drive signal source between a high level and a low level.

[0023] As a second aspect of the present invention, the technical solution of the embodiment of the switching power supply provided is as follows:

[0024] A switching power supply adopts a half-bridge topology, characterized in that the switching power supply includes the driving circuit described in any one of the first aspects above.

[0025] The driving circuit of the embodiment of the present invention includes two complementary output circuits. The specific working principle will be analyzed in detail in conjunction with the specific embodiment. The beneficial effects of the embodiment of the present invention are as follows:

[0026] 1. When the input driving signal source of the driving circuit of the embodiment of the present invention is switched to a low level, the voltage across the first secondary winding is zero, the voltage across the corresponding first charge storage unit increases and the corresponding first MOS tube is stably turned on through the corresponding voltage limiting circuit, so that a stable and reliable negative voltage driving signal can be provided for the corresponding driven switch tube within the dead time, and the reliability is high;

[0027] 2. When the driving circuit input driving signal source of the driving circuit of the embodiment of the present invention is switched to a low level, the voltage across the first secondary winding is zero, and the negative voltage module provides a negative driving voltage for the corresponding driven switch tube through the stable conduction of the corresponding first MOS tube, so that the switching speed is fast, which is conducive to reducing the switching loss and can meet the high-frequency design requirements;

[0028] 3. The driving circuit of the embodiment of the present invention is provided with a first charge storage unit in the gate capacitance discharge loop of each driven switch tube, and the switching speed can be adjusted by adjusting the size of the charge storage power supply of the first charge storage unit or the impedance of the discharge loop;

[0029] 4. The driving circuit of the embodiment of the present invention does not add an additional current loop, can maintain a small driving loss, and has a strong driving capability;

[0030] 5. The driving circuit of the embodiment of the present invention adopts transformer isolation driving, does not require additional power supply, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the schematic diagram of the conventional transformer drive solution;

[0032] Figure 2 Provide improvement solutions for existing transformer drives;

[0033] Figure 3 A first specific implementation circuit diagram of the driving circuit of the present invention;

[0034] Figure 4 for Figure 3 Waveform diagram of the driving circuit;

[0035] Figure 5 This is a second specific implementation circuit diagram of the driving circuit of the present invention. DETAILED DESCRIPTION

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0037] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application are described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, method, system, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0039] It should be understood that, in the specification, claims and drawings, when a step is described as being connected to another step, the step may be directly connected to the other step, or be connected to the other step through a third step; when an element / unit is described as being "connected" to another element / unit, the element / unit may be "directly connected" to the other element / unit, or be "connected" to the other element / unit through a third element / unit.

[0040] In addition, the drawings of the present disclosure are only schematic diagrams of the present disclosure and are not necessarily drawn to scale. The same symbols in the drawings represent the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented using software, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontrollers.

[0041] The inventive concept of the present application is that two complementary output circuits are arranged in a driving circuit, each output circuit is connected to a transformer secondary winding, each output circuit includes a negative voltage module, a negative voltage clamping MOS tube (i.e., a first MOS tube), a negative voltage clamping diode (i.e., a first diode), a voltage limiting circuit and a charge storage unit (i.e., a first charge storage unit), each output circuit forms a fast discharge loop for the gate capacitance of the corresponding driven switch tube through the conduction of the corresponding negative voltage clamping MOS tube, and forms a negative voltage driving signal for the corresponding driven switch tube during the non-conduction time; the negative voltage module, the corresponding secondary winding, the voltage limiting circuit and the first charge storage unit of each output circuit form a first discharge loop for the gate capacitance of the corresponding driven switch tube at the moment when the driving signal source is turned off, the voltage limiting circuit stabilizes the driving voltage of the negative voltage clamping MOS tube, and quickly charges the first charge storage unit, and the charge stored in the first charge storage unit maintains the charge required for the negative voltage clamping MOS tube to conduct within the driving dead time.

[0042] Based on the above invention concept, the present invention provides a driving circuit, which includes: a transformer core; a primary winding for inputting a driving signal source; a first secondary winding and a first output circuit connected thereto; a second secondary winding and a second output circuit connected thereto; one end of the first secondary winding and one end of the second secondary winding are opposite ends;

[0043] The first output circuit has the same structure as the second output circuit, and both include:

[0044] A first charge storage unit, a first diode, a first MOS tube, a voltage limiting circuit and a negative voltage module, one end of the negative voltage module and the drain of the first MOS tube are simultaneously connected to one end of the corresponding secondary winding, the other end of the negative voltage module is used to connect the gate of the driven switch tube, the first end of the voltage limiting circuit and the cathode of the first diode are simultaneously connected to the other end of the corresponding secondary winding, the second end of the voltage limiting circuit is simultaneously connected to one end of the first charge storage unit and the gate of the first MOS tube, the anode of the first diode, the other end of the first charge storage unit and the source of the first MOS tube are connected together to connect the source of the driven switch tube;

[0045] Each output circuit forms a fast discharge loop for the gate capacitance of the corresponding driven switch tube by turning on the corresponding first MOS tube, and forms a negative voltage driving signal for the corresponding driven switch tube during the non-conduction time;

[0046] The negative voltage module of each output circuit, and the corresponding secondary winding, voltage limiting circuit, and first charge storage unit form a first discharge loop for the gate capacitance of the corresponding driven switch tube when the driving signal source is turned off. At the same time, the voltage limiting circuit stabilizes the driving voltage of the corresponding first MOS tube and quickly charges the corresponding first charge storage unit. The charge stored in the corresponding first charge storage unit maintains the charge required for the corresponding first MOS tube to turn on within the driving dead time.

[0047] In the drive circuit of the present invention, since one end of the first secondary winding and one end of the second secondary winding are opposite ends, the first drive voltage provided by the first output circuit and the second drive voltage provided by the second output circuit are symmetrical and complementary drive signals. Taking the first drive voltage provided by the first output circuit as an example, the specific description is as follows:

[0048] When the input drive signal source is at a high level, the first secondary winding, the corresponding negative voltage module, the corresponding gate capacitor of the driven switch tube and the corresponding first diode form a first drive loop to provide a first drive voltage;

[0049] When the input drive signal source is switched to a low level, the voltage across the first secondary winding is zero, and the gate capacitance of the corresponding driven switch tube, the corresponding negative voltage module, the first secondary winding, the corresponding voltage limiting circuit and the corresponding first charge storage unit form a first loop, and the gate capacitance of the corresponding driven switch tube is discharged, while the corresponding first charge storage unit is charged, so that the voltage across the first charge storage unit increases and the corresponding first MOS tube is stably turned on through the corresponding voltage limiting circuit, so that the corresponding negative voltage module provides a negative driving voltage for the corresponding driven switch tube.

[0050] It should be noted that, in practical applications, by controlling the oscillation time of the driving signal source input to the primary winding, a dead zone can be created between the two complementary driving signals, thereby preventing the two switching tubes in the half-bridge circuit from being turned on at the same time and causing burning.

[0051] Figure 3 This is a first specific implementation circuit diagram of the driving circuit of the present invention, wherein:

[0052] The primary winding is P1, the first secondary winding is S1, the second secondary winding is S2, the driven switch tube connected to the first output circuit is Sa1, and the driven switch tube connected to the second output circuit is Sa2;

[0053] The first charge storage unit in the first output circuit is a capacitor Ca0, the first diode is Da1, and the first MOS tube is Sa0; the voltage limiting circuit in the first output circuit includes voltage-stabilizing diodes Da0 and Ra0; the negative voltage module in the first output circuit includes a capacitor Ca1, a resistor Ra1, a voltage-stabilizing diode Da2, and a diode Da3;

[0054] The first charge storage unit in the second output circuit is capacitor Cb0, the first diode is Db1, and the first MOS tube is Sb0; the voltage limiting circuit in the second output circuit includes voltage-regulating diodes Db0 and Rb0; the negative voltage module in the second output circuit includes capacitor Cb1, resistor Rb1, voltage-regulating diode Db2 and diode Db3.

[0055] Figure 4 for Figure 3 Waveform diagram of the driving circuit, where PWMSa1 is the first driving voltage of 120kHz output by the first output circuit, and PWMSa0 is the driving voltage of the negative voltage clamping MOS tube Sa0 in the first output circuit.

[0056] The following combination Figure 4 Waveform pair Figure 3 The working principle of the circuit in one working cycle is analyzed in detail:

[0057] In the first stage, that is, when the two ends of the secondary winding S1 of the transformer are in a forward driving voltage, the secondary winding S1, the negative voltage module, the gate capacitor of the switch tube Sa1 and the negative voltage clamping diode Da1 form a first driving circuit, and output the first driving voltage V0 required by the switch tube Sa1. The first driving voltage V0 is the voltage across the secondary winding S1 minus the voltage across the negative voltage module. The advantage is that there is no resistance device in the driving circuit, the loss is small, and the primary driving capacity requirement of the transformer can be reduced;

[0058] It should be noted that the capacitor Ca1 will be charged in the first one or two cycles before the drive circuit starts working. In the following normal working process, the voltage across the capacitor Ca1 is considered to be a stable voltage, and the current in the charging and discharging process is relatively small. The driving process hardly consumes the charge in the capacitor Ca1, and there is no need to consider its discharge process.

[0059] The second stage, that is, when the forward driving voltage of the transformer secondary winding S1 turns to 0, this is the dead time, the voltage across the transformer secondary winding S1 is zero, the gate capacitance of the switch tube Sa1, the negative voltage module, the transformer secondary side S1, the voltage stabilizing diode Da0, the current limiting resistor Ra0, and the voltage stabilizing capacitor Ca0 form a first discharge loop for the gate capacitance of the switch tube Sa1 at the moment when the driving voltage of the switch tube Sa1 is turned off, and the voltage stabilizing capacitor Ca0 is quickly charged, and the charge stored in the voltage stabilizing capacitor Ca0 maintains the charge required for the negative voltage clamping MOS tube Sa0 to turn on within the driving dead time, and the voltage stabilizing diode Da0 and the current limiting resistor Ra0 stabilize the driving voltage of the negative voltage clamping MOS tube Sa0;

[0060] In the third stage, when the voltage of the voltage stabilizing capacitor Ca0 reaches the conduction threshold value Vth of the negative voltage clamping MOS tube Sa0, the first output circuit forms a fast discharge loop for the gate capacitance of the switch tube Sa1 through the conduction of the negative voltage clamping MOS tube Sa0, and due to the existence of capacitor Ca1 Figure 3 The voltage is positive on the left and negative on the right. Therefore, after the negative voltage clamping MOS tube Sa0 is turned on, it will form a negative voltage driving signal V1 for Sa1 during the dead time. The advantage of this negative voltage control scheme is that the charge stored in the voltage stabilizing capacitor Ca0 enables the negative voltage clamping MOS tube Sa0 to remain turned on during the dead time, providing reliable negative voltage and strong reliability.

[0061] Furthermore, the selection of the first MOS tube satisfies that the negative voltage clamping MOS tube Sa0 works in the variable resistance region during the dead time between the high level and the low level switching of the input driving signal source, in order to avoid the current spike in the discharge circuit;

[0062] In the fourth stage, when the secondary side winding S1 connected to the first output circuit is a negative conduction voltage, the secondary side winding S1 and the voltage stabilizing diode Da0, the current limiting resistor Ra0, and the voltage stabilizing capacitor Ca0 jointly provide driving charge for the negative voltage clamping MOS tube Sa0, and the negative voltage clamping MOS tube Sa0 is fully turned on and forms a second discharge loop with the negative voltage module for the gate capacitance of the switch tube Sa1, forming a stable negative voltage driving voltage V2.

[0063] Figure 3 The voltage-stabilizing diode Da0, the current-limiting resistor Ra0 and the voltage-stabilizing capacitor Ca0 constitute a driving circuit for the negative-voltage clamping MOS tube Sa0, which stabilizes the negative-voltage clamping MOS tube Sa0 and filters out false switching caused by high-frequency noise, and also provides space for adjustable driving withstand voltage for the selection of the negative-voltage clamping MOS tube.

[0064] In specific implementation, the driving voltage change rate can be adjusted by adjusting the voltage limiting value of the voltage stabilizing diode Da0 or the capacitance of the voltage stabilizing capacitor Ca0 or the resistance of the current limiting resistor Ra0 to increase the driving speed of the switch tube Sa1.

[0065] In addition, it should be noted that Figure 3 In the circuit, Da2 is a voltage-stabilizing diode, which is used to form a stable negative voltage driving signal V1; Da3 is a discharge diode, which provides a discharge circuit for the gate capacitance of the switch tube Sa1, thereby realizing rapid discharge of the gate capacitance of the switch tube Sa1; Ra2 is the anti-static resistor of the switch tube Sa1; a pair of voltage-stabilizing diodes connected in reverse series between the gate and source of the switch tube Sa1 are overshoot protection devices, which prevent the driving voltage from being too high or too low to damage the switch tube Sa1.

[0066] Figure 5 The second specific implementation circuit diagram of the driving circuit of the present invention is shown in FIG. Figure 3 The difference is that: the voltage limiting circuit includes a first voltage dividing resistor Ra01 / Rb01 and a second voltage dividing resistor Ra02 / Rb02 connected in series, wherein the first end of the first voltage dividing resistor is connected to the first end of the voltage limiting circuit, the second end, and the first end of the second voltage dividing resistor is simultaneously connected to the second end of the voltage limiting circuit, and the second end of the second voltage dividing resistor is connected to the connection point of the anode of the first diode in the corresponding output circuit, the other end of the first charge storage unit and the source of the first MOS tube; wherein the second voltage dividing resistor is used to provide a suitable driving voltage for the negative voltage clamping MOS tube Sa0, and the first voltage dividing resistor Ra01 is used for current limiting; the first voltage dividing resistor and the voltage stabilizing capacitor Ca0 also constitute an RC filtering circuit to filter out high-frequency noise interference and avoid the corresponding first MOS tube from being turned on by mistake; the second voltage dividing resistor Ra02 and the voltage stabilizing capacitor Ca0 also constitute a discharge circuit, and it is necessary to ensure that the voltage stabilizing capacitor Ca0 can provide sufficient charge within the dead time to keep the negative voltage clamping MOS tube Sa0 turned on.

[0067] An embodiment of the present invention further provides a switching power supply, which adopts a half-bridge topology and includes any one of the above-mentioned drive circuits.

[0068] The above are only preferred embodiments of the present invention, and it should be noted that the above preferred embodiments should not be regarded as limiting the present invention. For those skilled in the art, several equivalent substitutions, improvements and modifications can be made without departing from the spirit and scope of the present invention, and these equivalent substitutions, improvements and modifications should also be regarded as the protection scope of the present invention. The embodiments will not be repeated here, and the protection scope of the present invention shall be based on the scope defined by the claims.

Claims

1. A driving circuit, characterized in that: include: The primary winding of the transformer is used for inputting a driving signal source; A first secondary winding and a first output circuit connected thereto; a second secondary winding and a second output circuit connected thereto; One end of the first secondary winding and one end of the second secondary winding are opposite ends; The first output circuit and the second output circuit have the same structure, and both include: A first charge storage unit, a first diode, a first MOS tube, a voltage limiting circuit and a negative voltage module, wherein one end of the negative voltage module and the drain of the first MOS tube are simultaneously connected to one end of the corresponding secondary winding, and the other end of the negative voltage module is used to connect the gate of the driven switch tube, the first end of the voltage limiting circuit and the cathode of the first diode are simultaneously connected to the other end of the corresponding secondary winding, the second end of the voltage limiting circuit is simultaneously connected to one end of the first charge storage unit and the gate of the first MOS tube, and the anode of the first diode, the other end of the first charge storage unit and the source of the first MOS tube are connected together to connect the source of the driven switch tube; Each output circuit forms a discharge loop for the gate capacitance of the corresponding driven switch tube by turning on the corresponding first MOS tube, and forms a negative voltage driving signal for the corresponding driven switch tube during the non-conduction time; The negative voltage module of each output circuit, and the corresponding secondary winding, voltage limiting circuit, and first charge storage unit form a first discharge loop for the gate capacitance of the corresponding driven switch tube when the driving signal source is turned off. At the same time, the voltage limiting circuit stabilizes the driving voltage of the corresponding first MOS tube and quickly charges the corresponding first charge storage unit. The charge stored in the corresponding first charge storage unit maintains the charge required for the corresponding first MOS tube to turn on within the driving dead time.

2. The driving circuit according to claim 1, characterized in that: The first charge storage unit is a capacitor.

3. The driving circuit according to claim 1, characterized in that: The voltage limiting circuit includes a voltage stabilizing diode and a resistor, wherein the cathode of the voltage stabilizing diode is connected to the first end of the voltage limiting circuit, the anode of the voltage stabilizing diode is connected to one end of the resistor, and the other end of the resistor is connected to the second end of the voltage limiting circuit.

4. The driving circuit according to claim 1, characterized in that: The voltage limiting circuit includes two resistors, wherein a first end of one resistor is connected to a first end and a second end of the voltage limiting circuit, and a first end of another resistor is simultaneously connected to a second end of the voltage limiting circuit, and a second end of another resistor is connected to a connection point of an anode of the first diode, the other end of the first charge storage unit and a source of the first MOS tube.

5. The driving circuit according to claim 1, characterized in that: The negative pressure module includes a capacitor and a resistor, one end of the capacitor is connected to one end of the negative pressure module, the other end of the capacitor is connected to one end of the resistor, and the other end of the resistor is connected to the other end of the negative pressure module.

6. The driving circuit according to claim 5, characterized in that: The negative pressure module further includes a voltage stabilizing diode, wherein a cathode of the voltage stabilizing diode is connected to one end of the negative pressure module, and an anode of the voltage stabilizing diode is connected to the other end of the capacitor.

7. The driving circuit according to claim 5 or 6, characterized in that: The negative pressure module further includes a diode, a cathode of the diode is connected to one end of the negative pressure module, and an anode of the diode is connected to the other end of the resistor.

8. The driving circuit according to claim 1, characterized in that: The driving circuit also includes a resistor, one end of which is connected to the other end of the negative pressure module and the other end of which is connected to the anode of the first diode, the other end of the first charge storage unit and the connection point of the source of the first MOS tube.

9. The driving circuit according to claim 1 or 8, characterized in that: The driving circuit also includes two voltage-stabilizing diodes, wherein the cathode of one voltage-stabilizing diode is connected to the other end of the negative pressure module, and the anode is connected to the anode of another voltage-stabilizing diode, and the cathode of the other voltage-stabilizing diode is connected to the connection point of the anode of the first diode, the other end of the first charge storage unit and the source of the first MOS tube.

10. The driving circuit according to claim 1, characterized in that: The selection of the first MOS transistor satisfies the requirement that the first MOS transistor works in a variable resistance region during a dead time between switching of the input drive signal source between a high level and a low level.

11. A switching power supply, the switching power supply adopting a half-bridge topology, characterized in that: The switching power supply comprises the driving circuit according to any one of claims 1 to 10.

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