CN112260522A

CN112260522A - E for MOSFET2Quasi-resonance drive circuit and modulation method thereof

Info

Publication number: CN112260522A
Application number: CN202010915551.6A
Authority: CN
Inventors: 孙向东; 陈泽驰; 王之轩; 任碧莹
Original assignee: Xian University of Technology
Current assignee: Xian University of Technology
Priority date: 2020-09-03
Filing date: 2020-09-03
Publication date: 2021-01-22
Anticipated expiration: 2040-09-03
Also published as: CN112260522B

Abstract

The invention discloses a method for improving the performance of a MOSFET₂Class resonance drive circuit, including DC supply voltage, DC supply voltage's positive pole is connected with the one end of direct current inductance, the other end of direct current inductance is connected with the drain electrode of first switch tube, the source electrode of first switch tube is connected to DC supply voltage's negative pole, still include the double-frenquency resonance inductance and the resonance capacitance of series connection, after double-frenquency resonance inductance and resonance capacitance series connection parallelly connected to the drain electrode and the source electrode of first switch tube ON and be connected with ON-OFF sub-circuit, DC supply voltage still parallel connection has the negative pressure to turn OFF sub-circuit, the output of ON-OFF sub-circuit and the output of negative pressure turn OFF sub-circuit parallel connection have by the drive initiative switch tube. The invention realizes ON-OFF driving of the high-frequency MOSFET, so that the switching device can work in a high-frequency resonance ON-OFF mode. The invention also discloses a device E for the MOSFET₂A modulation method of a quasi-resonance drive circuit.

Description

E for MOSFET2Quasi-resonance drive circuit and modulation method thereof

Technical Field

The invention belongs to the technical field of high-frequency switching power supplies, and relates to an E for a metal-oxide-semiconductor field effect transistor (MOSFET)₂The invention also relates to a modulation method of the resonance driving circuit.

Background

Metal-oxide semiconductor field effect transistors (MOSFETs) mainly include gallium nitride field effect transistors (GaN MOSFETs), silicon carbide field effect transistors (SiC MOSFETs), silicon field effect transistors (Si MOSFETs), and the like. With the development of power electronic technology, the operating frequency of power semiconductor devices is gradually increasing. In the fields of wireless power transmission, high-frequency switching power supplies and the like, the highest working frequency of the MOSFET can reach dozens of megahertz. Generally, the MOSFET device is a voltage-driven device, and the energy loss on the gate charge of the device during switching generates a large gate driving loss, and the higher the switching frequency is, the larger the driving loss is. In order to reduce the drive loss of the MOSFET in high frequency operation, reducing the energy loss of the gate charge of the driving switching semiconductor device has been the focus of research on high frequency power supply design and the like.

High frequency drive circuits often employ resonant circuits to reduce the energy loss of the drive gate charge. When the resonant driving circuit works, the grid charges participate in resonance, so that the energy loss of the grid charges is greatly reduced. The duty cycle and frequency of the resonant type driving circuit are not easy to change, so that the resonant type driving circuit is usually used together with an ON-OFF modulation method. The high-frequency resonant driving circuit proposed at present includes a voltage-raising self-driving circuit of ON-OFF modulation, a single-switch zero-voltage switching gate driving circuit, and the like. The boosting self-driving circuit is usually used for a synchronous rectifier, an auxiliary winding needs to be led out of a transformer of the rectifier, resonance is carried out on the auxiliary winding and a resonance device to drive a switching device, and the auxiliary switching device is used for controlling whether the resonance circuit is connected with a driving circuit or not. However, in a general application scenario, the transformer and the auxiliary winding thereof are not provided, so that the application scenario of the resonant driver is limited greatly. The single-switch zero-voltage switch gate driving circuit is an E-type resonant circuit, resonant voltage at two ends of a capacitor acts on a switching device in the E-type resonant circuit to drive, and the loss of the resonant circuit is zero theoretically, so that the single-switch zero-voltage switch gate driving circuit is suitable for driving the switching device with fixed high-frequency resonant frequency and fixed duty ratio. However, the scheme can not realize ON-OFF modulation and only can stably operate; the start-up process of the driving circuit is slow, the switch-on of the switch device may be mistakenly conducted in the start-up process to cause danger, and the negative pressure switch-off of the switch device cannot be realized.

Disclosure of Invention

Objects of the inventionIs to provide an E for MOSFET₂The quasi-resonance driving circuit realizes ON-OFF driving of the high-frequency MOSFET, so that the switching device can work in a high-frequency resonance ON-OFF mode.

It is another object of the present invention to provide an E for a MOSFET₂A modulation method of a quasi-resonance drive circuit.

The technical scheme adopted by the invention is that E is used for the MOSFET₂Quasi-resonant drive circuit including a DC supply voltage V_DCD.c. supply voltage V_DCIs connected with a direct current inductor L₁One end of (1), a direct current inductor L₁Is connected with a first MOSFET switch tube S₁Of the first MOSFET switching tube S₁Is connected to a dc supply voltage V_DCAlso comprises a double-frequency resonance inductor L connected in series₂And a resonance capacitor C₂Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Connected in series and then connected in parallel to the first MOSFET switching tube S₁On the drain and source of (1), a double frequency resonance inductor L₂And a resonance capacitor C₂An ON-OFF sub-circuit connected in parallel after series connection, a DC supply voltage V_DCAnd the output end of the ON-OFF sub-circuit and the output end of the negative pressure turn-OFF sub-circuit are connected with a driven active switching tube S in parallel.

The present invention is also characterized in that,

the ON-OFF sub-circuit comprises an auxiliary resonant capacitor C₁A second MOSFET switch tube S₂And a third MOSFET switch tube S₃Auxiliary resonant capacitor C₁And a second MOSFET switch tube S₂The drain electrode and the source electrode are connected in parallel; second MOSFET switch tube S₂And the first MOSFET switch tube S₁The drain electrodes of the two electrodes are connected; second MOSFET switch tube S₂Source and third MOSFET switch tube S₃The drain electrodes of the two-way transistor are connected, and the connection point is marked as a point A; third MOSFET switch tube S₃Source electrode of and first MOSFET switch tube S₁The source of the driving active switch tube S is connected with the point A, and the source of the driving active switch tube S is connected with the output end of the ON-OFF sub-circuit.

The negative voltage turn-off sub-circuit comprises a voltage stabilizing diode DZ₁Voltage stabilizing capacitor C₃Freewheeling resistor R₁Diode DZ for voltage regulation₁Anode and voltage-stabilizing capacitor C₃And a third MOSFET switching tube S₃The source electrodes of the two-way transistor are connected; voltage stabilizing diode DZ₁Cathode and voltage-stabilizing capacitor C₃The positive electrodes of the two electrodes are connected, and the connection point is marked as a point B; follow current resistor R₁Is connected to a dc supply voltage V_DCPositive electrode of (2), freewheel resistor R₁Is connected to a point B of the connection point, and a main resonant capacitor C is connected between the point A and the point B₄The grid electrode of the driven main switch tube S is connected with the point A, and the source electrode of the driven main switch tube S is connected with the point B.

The second technical scheme adopted by the invention is as follows: e for MOSFET₂Modulation method of quasi-resonance drive circuit, using the above E for MOSFET₂Quasi-resonant drive circuit for MOSFET₂The ON-OFF logic control subcircuit of the quasi-resonance driving circuit comprises: a high-frequency square-wave generator and an ON-OFF modulator, the high-frequency switching frequency of the driven main switch tube S is generated by the high-frequency square-wave generator, the high-frequency square-wave generator generates a frequency f₁Duty ratio du₁Of the high-frequency square-wave signal, the operating frequency of the ON-OFF modulator being f₂ON-OFF modulator with duty cycle du₂The enable signal of the ON-OFF modulator is EN, and the output signal of the high-frequency square-wave generator is marked as G₁The high-frequency square wave generator is connected with an AND gate chip IC ₂1 input terminal and AND gate chip IC ₃1 input terminal; the output signal of the ON-OFF modulator is connected with an AND gate chip IC ₂2 input terminal and not-gate chip IC₁An input terminal of (1); NOT gate chip IC₁Is connected to the AND gate chip IC ₃2 input terminal of (1); AND gate chip IC₂The output signal of the SR trigger is connected with an S-end input pin of the SR trigger; AND gate chip IC₃The output signal of the SR flip-flop is connected to an R end input pin of the SR flip-flop; the Q output signal of the pin of the SR flip-flop is marked as G₂(ii) a The Q output signal of the pin of the SR flip-flop is marked as G₃Wherein the signal G₁Is a first MOSFETT switch tube S₁Signal G₂For the second MOSFET switching tube S₂Signal G₃For a third MOSFET switching tube S₃Signal G₂And signal G₃Are complementary all the time; e for MOSFET₂The quasi-resonance driving circuit is divided into 3 working states according to an enable signal EN of the ON-OFF modulator, and specifically comprises the following steps: t is t₀～t₁The section is in an enable prohibition state, and the output of the driving circuit is always in a negative pressure turn-off state; t is t₁～t₂The section is in an ON state, and the output of the driving circuit is a high-frequency switch driving signal; t is t₂～t₃The section is in an OFF state, and the output of the drive circuit is always in a negative pressure turn-OFF state.

The second aspect of the present invention is also characterized in that,

the specific modulation method is as follows:

t₀～t₁enable inhibit state: the enable signal EN is a low-level invalid signal, and the high-frequency square-wave generator outputs a square-wave signal G₁First MOSFET switch tube S₁Working in high-frequency switch state all the time, the resonant circuit starts oscillation gradually, the output signal of ON-OFF modulator is low level, so that signal G₂Always at low level, the second MOSFET switch tube S₂Is always turned off, and the third MOSFET switching tube S₃Always on, the output voltage U of the driving circuit₁Is always a negative pressure signal, and during the time period, the direct current inductance L₁A first MOSFET switch tube S₁Auxiliary resonant capacitor C₁Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Together form E₂The quasi-resonance circuit enables the output of the driving circuit to be a constant negative pressure signal due to the existence of the negative pressure turn-off sub-circuit, and in the interval, the enabling time of the EN signal is delayed to enable the E₂The quasi-resonance circuit reaches a stable working state;

t₁～t₂an ON state: the output of the state driving circuit is a high-frequency switch driving signal, the enable signal EN is an effective signal at the moment, the ON-OFF modulator outputs a high-level signal t₀～t₁Length of time block of segmentAt duty cycle du₂At this time G₂The signal is high level, the second MOSFET switch tube S₂Always on, the third MOSFET switch tube S₃Always off, the output voltage U of the drive circuit₁For high-frequency switching of the drive signal, the switching frequency being derived from the signal G₁During this time period, the direct current inductance L₁A first switch tube S₁Main resonant capacitor C₄Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Together form E₂Quasi-resonant circuit, negative turn-off circuit making U_DS1The signal generates negative pressure deviation, so that the driving circuit has a negative pressure turn-off function;

t₂～t₃OFF state: the output of the state driving circuit is always in negative pressure turn-OFF, at the moment, the enable signal EN is an effective signal, the ON-OFF modulator outputs a low level signal t₁～t₂The length of the segment depends on du₂，G₂The signal being low, G₃The signal is high level, the second MOSFET switch tube S₂Is always turned off, and the third MOSFET switching tube S₃Always on, the output voltage U of the driving circuit₁Is always in a negative pressure state, and during the time period, the direct current inductance L₁A first switch tube S₁Auxiliary resonant capacitor C₁Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Together form E₂Like a resonant circuit, the resonant circuit portion is continuously operated.

The invention has the beneficial effects that: the invention solves the problem that the prior method can not realize ON-OFF modulation, realizes ON-OFF modulation of the driven MOSFET, solves the problem that the prior method can not realize negative pressure turn-OFF of a switching tube, realizes reliable negative pressure turn-OFF of the driven MOSFET, solves the problem that a driver in the prior method has a starting resonance process, and avoids the problems that the driven MOSFET has slow starting oscillation process and is easy to be switched ON by mistake.

Drawings

FIG. 1 is E for a MOSFET of the present invention₂A main circuit diagram of a quasi-resonant drive circuit;

FIG. 2 is a diagram of the present invention for a MOSE of FET₂An ON-OFF logic control sub-circuit implementation block diagram of the quasi-resonance drive circuit;

FIG. 3 is E for a MOSFET of the present invention₂The working state and the working waveform of the quasi-resonance driving circuit.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Invention E for MOSFET₂The quasi-resonance drive circuit has a structure shown in FIG. 1 and includes a DC supply voltage V_DCD.c. supply voltage V_DCIs connected with a direct current inductor L₁One end of (1), a direct current inductor L₁Is connected with a first MOSFET switch tube S₁Of the first MOSFET switching tube S₁Is connected to a dc supply voltage V_DCAlso comprises a double-frequency resonance inductor L connected in series₂And a resonance capacitor C₂Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Connected in series and then connected in parallel to the first MOSFET switching tube S₁On the drain and source of (1), a double frequency resonance inductor L₂And a resonance capacitor C₂An ON-OFF sub-circuit connected in parallel after series connection, a DC supply voltage V_DCThe output end of the ON-OFF sub-circuit and the output end of the negative pressure turn-OFF sub-circuit are connected with a driven active switching tube S in parallel;

the ON-OFF sub-circuit comprises an auxiliary resonant capacitor C₁A second MOSFET switch tube S₂And a third MOSFET switch tube S₃Auxiliary resonant capacitor C₁And a second MOSFET switch tube S₂The drain electrode and the source electrode are connected in parallel; second MOSFET switch tube S₂And the first MOSFET switch tube S₁The drain electrodes of the two electrodes are connected; second MOSFET switch tube S₂Source and third MOSFET switch tube S₃The drain electrodes of the two-way transistor are connected, and the connection point is marked as a point A; third MOSFET switch tube S₃Source electrode of and first MOSFET switch tube S₁The source electrode of the driving active switching tube S is connected with the point A, and the source electrode of the driving active switching tube S is connected with the output end of the ON-OFF sub-circuit;

the negative voltage turn-off sub-circuit comprises a voltage stabilizing diode DZ₁Voltage stabilizing capacitor C₃Freewheeling resistor R₁Diode DZ for voltage regulation₁Anode and voltage-stabilizing capacitor C₃And a third MOSFET switching tube S₃The source electrodes of the two-way transistor are connected; voltage stabilizing diode DZ₁Cathode and voltage-stabilizing capacitor C₃The positive electrodes of the two electrodes are connected, and the connection point is marked as a point B; follow current resistor R₁Is connected to a dc supply voltage V_DCPositive electrode of (2), freewheel resistor R₁Is connected to a point B of the connection point, and a main resonant capacitor C is connected between the point A and the point B₄The grid electrode of the driven main switch tube S is connected with the point A, and the source electrode of the driven main switch tube S is connected with the point B;

invention E for MOSFET₂Modulation method of quasi-resonance drive circuit, using the above E for MOSFET₂Quasi-resonant drive circuit for MOSFET₂The ON-OFF logic control sub-circuit of the quasi-resonance drive circuit, as shown in FIG. 2, comprises a high-frequency square-wave generator and an ON-OFF modulator, the high-frequency switching frequency of the driven main switch tube S is generated by the high-frequency square-wave generator, and the high-frequency square-wave generator generates the frequency f₁Duty ratio du₁Of the high-frequency square-wave signal, the operating frequency of the ON-OFF modulator being f₂ON-OFF modulator with duty cycle du₂The enable signal of the ON-OFF modulator is EN, and the output signal of the high-frequency square-wave generator is marked as G₁The high-frequency square wave generator is connected with an AND gate chip IC ₂1 input terminal and AND gate chip IC ₃1 input terminal; the output signal of the ON-OFF modulator is connected with an AND gate chip IC ₂2 input terminal and not-gate chip IC₁An input terminal of (1); NOT gate chip IC₁Is connected to the AND gate chip IC ₃2 input terminal of (1); AND gate chip IC₂The output signal of the SR trigger is connected with an S-end input pin of the SR trigger; AND gate chip IC₃The output signal of the SR flip-flop is connected to an R end input pin of the SR flip-flop; the Q output signal of the pin of the SR flip-flop is marked as G₂(ii) a The Q output signal of the pin of the SR flip-flop is marked as G₃Wherein the signal G₁For the first MOSFET switching tube S₁Signal G₂For the second MOSFET switching tube S₂Signal G₃For a third MOSFET switching tube S₃Signal G₂And signal G₃Are complementary all the time; e for MOSFET₂The quasi-resonance driving circuit is divided into 3 working states according to an enable signal EN of the ON-OFF modulator, and specifically comprises the following steps: t is t₀～t₁The section is in an enable prohibition state, and the output of the driving circuit is always in a negative pressure turn-off state; t is t₁～t₂The section is in an ON state, and the output of the driving circuit is a high-frequency switch driving signal; t is t₂～t₃The section is OFF state, the output of the drive circuit is always in negative pressure turn-OFF state, the invention switches on the tube S through the second MOSFET₂And a third MOSFET switch tube S₃Alternately switching when the output of the drive circuit is off so that the auxiliary resonant capacitor C₁And a main resonance capacitor C₄Alternating as E₂The resonant capacitor of the quasi-resonant circuit eliminates the starting and closing processes of the driving voltage of the controlled switching tube, and the specific modulation method is as follows:

as shown in FIG. 3, t₀～t₁Enable inhibit state: the enable signal EN is a low-level invalid signal, and the high-frequency square-wave generator outputs a square-wave signal G₁First MOSFET switch tube S₁Working in high-frequency switch state all the time, the resonant circuit starts oscillation gradually, the output signal of ON-OFF modulator is low level, so that signal G₂Always at low level, the second MOSFET switch tube S₂Is always turned off, and the third MOSFET switching tube S₃Always on, the output voltage U of the driving circuit₁Is always a negative pressure signal, and during the time period, the direct current inductance L₁A first MOSFET switch tube S₁Auxiliary resonant capacitor C₁Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Together form E₂The quasi-resonance circuit enables the output of the driving circuit to be a constant negative pressure signal due to the existence of the negative pressure turn-off sub-circuit, and in the interval, the enabling time of the EN signal is delayed to enable the E₂The quasi-resonance circuit reaches a stable working state, and the condition of false conduction caused by incomplete resonance can be avoided;

t₁～t₂an ON state: the output of the state driving circuit is a high-frequency switch driving signal, the enable signal EN is an effective signal at the moment, the ON-OFF modulator outputs a high-level signal t₀～t₁The length of the period depending on the duty cycle du₂At this time G₂The signal is high level, the second MOSFET switch tube S₂Always on, the third MOSFET switch tube S₃Always off, the output voltage U of the drive circuit₁For high-frequency switching of the drive signal, the switching frequency being derived from the signal G₁During this time period, the direct current inductance L₁A first switch tube S₁Main resonant capacitor C₄Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Together form E₂Quasi-resonant circuit, negative turn-off circuit making U_DS1The signal generates negative pressure deviation, so that the driving circuit has a negative pressure turn-off function;

The high frequency square wave generator of the present invention is typically designed using a voltage controlled oscillator, so the frequency f₁And duty cycle du₁Generally, the high-frequency switching frequency and the duty cycle of the driven main switching tube S are kept constant. ON-OFF modulator generating a frequency of f₂Low frequency ON-OFF square wave signal of du through₂The signal controls the duty cycle of the ON-OFF signal, via ENSignal control ON-OFF modulator enabling or disabling output, in practice f₂Typically remain unchanged.

Claims

1. E for MOSFET₂Quasi-resonant drive circuit, characterized in that it comprises a DC supply voltage V_DCD.c. supply voltage V_DCIs connected with a direct current inductor L₁One end of (1), a direct current inductor L₁Is connected with a first MOSFET switch tube S₁Of the first MOSFET switching tube S₁Is connected to a dc supply voltage V_DCAlso comprises a double-frequency resonance inductor L connected in series₂And a resonance capacitor C₂Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Connected in series and then connected in parallel to the first MOSFET switching tube S₁On the drain and source of (1), a double frequency resonance inductor L₂And a resonance capacitor C₂An ON-OFF sub-circuit connected in parallel after series connection, a DC supply voltage V_DCAnd the output end of the ON-OFF sub-circuit and the output end of the negative pressure turn-OFF sub-circuit are connected with a driven active switching tube S in parallel.

2. E for a MOSFET according to claim 1₂Quasi-resonant drive circuit, characterized in that the ON-OFF sub-circuit comprises an auxiliary resonant capacitor C₁A second MOSFET switch tube S₂And a third MOSFET switch tube S₃Auxiliary resonant capacitor C₁And a second MOSFET switch tube S₂The drain electrode and the source electrode are connected in parallel; second MOSFET switch tube S₂And the first MOSFET switch tube S₁The drain electrodes of the two electrodes are connected; second MOSFET switch tube S₂Source and third MOSFET switch tube S₃The drain electrodes of the two-way transistor are connected, and the connection point is marked as a point A; third MOSFET switch tube S₃Source electrode of and first MOSFET switch tube S₁The source of the driving active switch tube S is connected with the point A, and the source of the driving active switch tube S is connected with the output end of the ON-OFF sub-circuit.

3. Root of herbaceous plantE for a MOSFET according to claim 2₂Quasi-resonance drive circuit, characterized in that the negative voltage turn-off sub-circuit comprises a zener diode DZ₁Voltage stabilizing capacitor C₃Freewheeling resistor R₁Diode DZ for voltage regulation₁Anode and voltage-stabilizing capacitor C₃And a third MOSFET switching tube S₃The source electrodes of the two-way transistor are connected; voltage stabilizing diode DZ₁Cathode and voltage-stabilizing capacitor C₃The positive electrodes of the two electrodes are connected, and the connection point is marked as a point B; follow current resistor R₁Is connected to a dc supply voltage V_DCPositive electrode of (2), freewheel resistor R₁Is connected to a point B of the connection point, and a main resonant capacitor C is connected between the point A and the point B₄The grid electrode of the driven main switch tube S is connected with the point A, and the source electrode of the driven main switch tube S is connected with the point B.

4. E for MOSFET₂Modulation method for a quasi-resonant drive circuit, characterized in that an E for a MOSFET according to claim 3 is used₂Quasi-resonant drive circuit, said E for MOSFET₂The ON-OFF logic control subcircuit of the quasi-resonance driving circuit comprises: a high-frequency square-wave generator and an ON-OFF modulator, the high-frequency switching frequency of the driven main switch tube S is generated by the high-frequency square-wave generator, the high-frequency square-wave generator generates a frequency f₁Duty ratio du₁Of the high-frequency square-wave signal, the operating frequency of the ON-OFF modulator being f₂ON-OFF modulator with duty cycle du₂The enable signal of the ON-OFF modulator is EN, and the output signal of the high-frequency square-wave generator is marked as G₁The high-frequency square wave generator is connected with an AND gate chip IC₂1 input terminal and AND gate chip IC₃1 input terminal; the output signal of the ON-OFF modulator is connected with an AND gate chip IC₂2 input terminal and not-gate chip IC₁An input terminal of (1); NOT gate chip IC₁Is connected to the AND gate chip IC₃2 input terminal of (1); AND gate chip IC₂The output signal of the SR trigger is connected with an S-end input pin of the SR trigger; AND gate chip IC₃The output signal of the SR flip-flop is connected to an R end input pin of the SR flip-flop; the Q output signal at pin of the SR flip-flop is recorded asG₂(ii) a The Q output signal of the pin of the SR flip-flop is marked as G₃Wherein the signal G₁For the first MOSFET switching tube S₁Signal G₂For the second MOSFET switching tube S₂Signal G₃For a third MOSFET switching tube S₃Signal G₂And signal G₃Are complementary all the time; said E for MOSFET₂The quasi-resonance driving circuit is divided into 3 working states according to an enable signal EN of the ON-OFF modulator, and specifically comprises the following steps: t is t₀～t₁The section is in an enable prohibition state, and the output of the driving circuit is always in a negative pressure turn-off state; t is t₁～t₂The section is in an ON state, and the output of the driving circuit is a high-frequency switch driving signal; t is t₂～t₃The section is in an OFF state, and the output of the drive circuit is always in a negative pressure turn-OFF state.

5. E for a MOSFET according to claim 4₂The modulation method of the quasi-resonance driving circuit is characterized by comprising the following steps of:

t₁～t₂ON shapeState: the output of the state driving circuit is a high-frequency switch driving signal, the enable signal EN is an effective signal at the moment, the ON-OFF modulator outputs a high-level signal t₀～t₁The length of the period depending on the duty cycle du₂At this time G₂The signal is high level, the second MOSFET switch tube S₂Always on, the third MOSFET switch tube S₃Always off, the output voltage U of the drive circuit₁For high-frequency switching of the drive signal, the switching frequency being derived from the signal G₁During this time period, the direct current inductance L₁A first switch tube S₁Main resonant capacitor C₄Frequency-doubled resonant inductor L₂And a resonance capacitor C₂Together form E₂Quasi-resonant circuit, negative turn-off circuit making U_DS1The signal generates negative pressure deviation, so that the driving circuit has a negative pressure turn-off function;

The invention solves the problems that the scheme can not realize ON-OFF modulation and can only run in a stable state ON the basis of a single-switch zero-voltage switch gate driving circuit, the starting oscillation process of the driving circuit is slow, and the problem that the false conduction of a switching device is possibly dangerous in the starting oscillation process can be solved, and simultaneously the problem of negative pressure turn-OFF of the switching device can be solved; the added negative voltage turn-off sub-circuit comprises a voltage stabilizing diode, a current limiting resistor and a voltage stabilizing capacitor so as to realize the negative voltage turn-off function of the switching device; the logic control sub-circuit comprises a phase inverter, two AND gates and an SR trigger, and drives the auxiliary switch device through the logic control sub-circuit, so that the resonant capacitor is switched, and the problems of slow starting process and false conduction are avoided.