Patent ID: 12231034

DESCRIPTION OF EMBODIMENTS

The following describes embodiments of this application with reference to accompanying drawings.

FIG.3is a schematic diagram of an application scenario of a drive circuit with an energy recovery function according to an embodiment of this application. As shown inFIG.3, the application scenario includes a switch mode power supply30and an electrical appliance31. The switch mode power supply30is connected to the electrical appliance31.

The switch mode power supply30includes a power supply301and a drive circuit302. A first port302aof the drive circuit302is connected to the power supply301, and a second port302bof the drive circuit302is connected to the electrical appliance31.

The drive circuit302controls switching-on and switching-off of a loop between the power supply301and the electrical appliance31, to implement a function of the switch mode power supply.

Herein, it should be noted that the drive circuit with an energy recovery function disclosed in this application may alternatively be applied to another circuit, for example, an inverter.

FIG.4is a schematic diagram of an architecture of a drive circuit with an energy recovery function according to an embodiment of this application. As shown inFIG.4, the drive circuit302includes a control circuit303, an energy recovery drive circuit304, a switch circuit305, and a direct current power supply306. A control terminal303aof the control circuit303is connected to a first port304aof the energy recovery drive circuit304. An output terminal306aof the direct current power supply306is connected to a third port304cof the energy recovery drive circuit304. A second port304bof the energy recovery drive circuit304is connected to a first port305aof the switch circuit305.

The control circuit303is configured to control the energy recovery drive circuit304to enable an energy storage capacitor in the energy recovery drive circuit304to charge a junction capacitor of the switch circuit305at a first moment, and enable the direct current power supply306to charge the junction capacitor of the switch circuit305through the energy recovery drive circuit304at a second moment, so that the switch circuit305is switched on, where the first moment is earlier than the second moment.

The control circuit303is further configured to control the energy recovery drive circuit304to enable the junction capacitor of the switch circuit305to charge the energy storage capacitor in the energy recovery drive circuit304at a third moment, and enable the junction capacitor of the switch circuit305to discharge to a ground through the energy recovery drive circuit304at a fourth moment, so that the switch circuit305is switched off, where the third moment is earlier than the fourth moment.

That the switch circuit305is switched on and switched off specifically means that a second port and a third port of the switch circuit305are connected and disconnected.

The second port305band the third port305cof the switch circuit305are respectively connected to the electrical appliance31and the power supply301, and the control circuit303controls connection and disconnection between the second port305band the third port305cof the switch circuit305, to switch on and switch off the loop between the power supply301and the electrical appliance31.

Further, the energy recovery drive circuit304includes a push-pull drive circuit307and an energy recovery circuit308, the first port304aof the energy recovery drive circuit304includes a first port307aof the push-pull drive circuit307and a first port308aof the energy recovery circuit308, and the second port304bof the energy recovery drive circuit304includes a second port307bof the push-pull drive circuit307and a second port308bof the energy recovery circuit308.

That a control terminal303aof the control circuit303is connected to a first port304aof the energy recovery drive circuit304specifically includes: The control terminal303aof the control circuit303is connected to both the first port307aof the push-pull drive circuit307and the first port308aof the energy recovery circuit308. That a second port304bof the energy recovery drive circuit304is connected to a first port305aof the switch circuit305specifically includes: Both the second port307bof the push-pull drive circuit307and the second port308bof the energy recovery circuit308are connected to the first port305aof the switch circuit305. That an output terminal306aof the direct current power supply306is connected to a third port304cof the energy recovery drive circuit304specifically means that the output terminal306aof the direct current power supply306is connected to a third port307cof the push-pull drive circuit307.

Specifically, that the control circuit303is configured to control the energy recovery drive circuit304to enable an energy storage capacitor in the energy recovery drive circuit304to charge a junction capacitor of the switch circuit305at a first moment, and enable the direct current power supply306to charge the junction capacitor of the switch circuit305through the energy recovery drive circuit304at a second moment specifically includes:the control circuit303controls the energy recovery circuit308to enable the energy storage capacitor in the energy recovery circuit308to charge the junction capacitor of the switch circuit305at the first moment, and controls the push-pull drive circuit307to enable the direct current power supply306to charge the junction capacitor of the switch circuit305through the push-pull drive circuit307at the second moment; andthat the control circuit303is configured to control the energy recovery drive circuit304to enable the junction capacitor of the switch circuit305to charge the energy storage capacitor in the energy recovery drive circuit304at a third moment, and enable the junction capacitor of the switch circuit305to discharge to a ground through the energy recovery drive circuit304at a fourth moment specifically includes:the control circuit303controls the energy recovery circuit308to enable the junction capacitor of the switch circuit to charge the energy storage capacitor in the energy recovery circuit308at the third moment, and controls the push-pull drive circuit307to enable the junction capacitor of the switch circuit305to discharge to the ground through the push-pull drive circuit307at the fourth moment.

Optionally, as shown inFIG.5aorFIG.6a, the switch circuit includes a resistor R4, a MOS transistor M0, a capacitor Cdg, and a capacitor Cgs. A first terminal of the resistor R4is connected to a gate of the MOS transistor M0, two terminals of the capacitor Cdg are respectively connected to a drain and the gate of the MOS transistor M0, two terminals of the capacitor Cgs are respectively connected to the gate and a source of the MOS transistor, and the source of the MOS transistor M0is connected to a second terminal of the resistor R4.

The second port305band the third port305cof the switch circuit305respectively include the drain and the source of the MOS transistor M0. That a second port and a third port of the switch circuit305are connected and disconnected means that the drain and the source of the MOS transistor M0are connected and disconnected.

In this application, the junction capacitor of the switch circuit305includes the capacitor Cdg and the capacitor Cgs.

Optionally, the switch circuit305further includes a capacitor Cds, and two terminals of the capacitor Cds are respectively connected to the drain and the source of the MOS transistor M0.

Optionally, the MOS transistor M0is an NPN MOS transistor.

The MOS transistor may be, but is not limited to, a common silicon-based metal-oxide-semiconductor field-effect transistor (Si MOSFET), a silicon carbide high electron mobility transistor (SiC HEMT), a gallium nitride high electron mobility transistor (GaN HEMT), and the like.

Optionally, as shown inFIG.5aorFIG.6a, the push-pull drive circuit307includes an NPN triode Q1, a PNP triode Q4, a capacitor C3, and a resistor R2.

An emitter of the triode Q4is connected to an emitter of the triode Q1, a base of the triode Q4is connected to a base of the triode Q1, a second terminal of the resistor R2is connected to the base of the triode Q4, a first terminal of the resistor R2is connected between the emitter of the triode Q4and the emitter of the triode Q1through a resistor R5, a first terminal of the capacitor C3is connected between the emitter of the triode Q4and the emitter of the triode Q1, a second terminal of the capacitor C3is connected between the base of the triode Q4and the base of the triode Q1, and a collector of the triode Q1is grounded.

Optionally, as shown inFIG.5aorFIG.6a, the energy recovery circuit308includes an NPN triode Q2, a PNP triode Q3, a clamping diode D2, a clamping diode D3, a capacitor C2, and a resistor R1, and the capacitor C2is the energy storage capacitor in the energy recovery drive circuit304.

An emitter of the triode Q2is connected to an emitter of the triode Q3, both a base of the triode Q2and a base of the triode Q3are connected to a second terminal of the resistor R1, a collector of the triode Q2is connected to a negative electrode of the diode D2, a collector of the triode Q3is connected to a positive electrode of the diode D3, both a negative electrode of the diode D3and a positive electrode of the diode D2are connected to a first terminal of the capacitor C2, and a second terminal of the capacitor C2is grounded.

Optionally, as shown inFIG.7orFIG.8, the push-pull drive circuit includes an NPN triode Q1, a PNP triode Q4, a capacitor C3, and a capacitor C4.

An emitter of the triode Q4is connected to an emitter of the triode Q1, a base of the triode Q4is connected to a base of the triode Q1, a second terminal of the capacitor C4is connected to the base of the triode Q4, a first terminal of the capacitor C4is connected between the emitter of the triode Q4and the emitter of the triode Q1through a resistor R5, a first terminal of the capacitor C3is connected between the emitter of the triode Q4and the emitter of the triode Q1, a second terminal of the capacitor C3is connected between the base of the triode Q4and the base of the triode Q1, and a collector of the triode Q1is grounded.

Optionally, as shown inFIG.7orFIG.8, the energy recovery circuit includes an NPN triode Q2, a PNP triode Q3, a clamping diode D2, a clamping diode D3, a capacitor C2, a capacitor C5, and a resistor R1, and the capacitor C2is the energy storage capacitor in the energy recovery drive circuit304.

An emitter of the triode Q2is connected to an emitter of the triode Q3, both a base of the triode Q2and a base of the triode Q3are connected to a second terminal of the resistor R1and a second terminal of the capacitor C5, a first terminal of the resistor R1is connected to a first terminal of the capacitor C5, a collector of the triode Q2is connected to a negative electrode of the diode D2, a collector of the triode Q3is connected to a positive electrode of the diode D3, both a negative electrode of the diode D3and a positive electrode of the diode D2are connected to a first terminal of the capacitor C2, and a second terminal of the capacitor C2is grounded.

Optionally, a parameter of the clamping diode D2is the same as that of the clamping diode D3.

Optionally, a parameter of the triode Q1is the same as that of the triode Q3, and a parameter of the triode Q2is the same as that of the triode Q4.

As shown inFIG.5aorFIG.6a, that both the second port307bof the push-pull drive circuit307and the second port308bof the energy recovery circuit308are connected to the first port305aof the switch circuit305specifically includes:the gate of the MOS transistor is connected between the emitter of the triode Q4and the emitter of the triode Q1, and the source of the MOS transistor is connected to the collector of the triode Q1; andthe gate of the MOS transistor is connected between the emitter of the triode Q2and the emitter of the triode Q3, and the source of the MOS transistor is connected to the second terminal of the capacitor C2; andthat the direct current power supply306is connected to the push-pull drive circuit specifically includes: a positive electrode of the direct current power supply306is connected to a collector of the triode Q4, and a negative electrode of the direct current power supply306is grounded.

The control circuit303includes a first drive signal generator V1, and that the control terminal303aof the control circuit303is connected to both the first port307aof the push-pull drive circuit307and the first port308aof the energy recovery circuit308specifically includes:as shown inFIG.5a, a positive electrode of the first drive signal generator V1is connected to the first terminal of the resistor R2in the push-pull drive circuit307and the first terminal of the resistor R1in the energy recovery circuit308through a resistor R3, and a negative electrode of the first drive signal generator V1is grounded; oras shown inFIG.7, a positive electrode of the first drive signal generator V1is connected to the first terminal of the capacitor C4in the push-pull drive circuit307, the first terminal of the resistor R1in the energy recovery circuit308, and the first terminal of the capacitor C5through a resistor R3.

Specifically, as shown inFIG.5a, the first drive signal generator V1outputs a drive signal. When a rising edge of the drive signal is output, a voltage of the first drive signal generator V1output by the first drive signal generator gradually increases. In addition, when the voltage V1output by the first drive signal generator V1is greater than a breakover voltage Vbe2, for example, 0.7 V, of the triode Q2in the energy recovery circuit308at the first moment, the collector and the emitter of the triode Q2are connected, and the capacitor C2of the energy recovery circuit308charges the capacitor Cdg and the capacitor Cgs of the switch circuit305through the diode D2and the triode Q2until a voltage on the capacitor C2is less than that on the capacitor Cdg and the capacitor Cgs of the switch circuit305. In this case, a voltage on the junction capacitor of the switch circuit305reaches an intermediate level. When the first drive signal generator V1outputs the rising edge of the drive signal, the capacitor C3is charged. When a voltage on the capacitor C3is greater than a breakover voltage Vbe4, for example, 0.7 V, of the triode Q4at the second moment, the collector and the emitter of the triode Q4are connected, and the direct current power supply VCC charges the capacitor Cdg and the capacitor Cgs of the switch circuit305through the triode Q4in the push-pull drive circuit307until the voltage on the capacitor Cdg and the capacitor Cgs is equal to a difference between a voltage of the direct current power supply VCC and a voltage drop Vce of the triode Q4. In this case, the voltage on the junction capacitor of the switch circuit305reaches a high level, and the switch circuit305is switched on. A loop for charging the capacitor Cdg and the capacitor Cgs of the switch circuit305is shown inFIG.5b.

When a falling edge of the drive signal is output, the voltage V1output by the first drive signal generator V1gradually decreases. When the difference between the voltage of the drive signal output by the first drive signal generator V1and the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305is greater than a breakover voltage Vbe3of the triode Q3, the triode Q3is switched on. The capacitor Cdg and the capacitor Cgs of the switch circuit305charge the capacitor C2of the energy recovery circuit308through the diode D3and the triode Q3until the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305is less than the voltage on the capacitor C2. In this case, the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305drops from the high level to the intermediate level. As the voltage output by the first drive signal generator decreases, the voltage on the capacitor C3gradually decreases. When the voltage on the capacitor C3is less than a breakover voltage Vbe1, for example, −0.7 V of the triode Q1at the fourth moment, the capacitor Cdg and the capacitor Cgs of the switch circuit305discharge to the ground through the triode Q1in the push-pull drive circuit307, so that the capacitor Cdg and the capacitor Cgs of the switch circuit305drop from the intermediate level to a low level, and the switch circuit305is switched off. A discharging loop for the capacitor Cdg and the capacitor Cgs of the switch circuit305is shown inFIG.5c.

FIG.5dis a schematic diagram of a voltage change on each device during operation of the drive circuit shown inFIG.5a. VC1inFIG.5dindicates the voltage on the capacitor Cdg and the capacitor Cgs. As shown inFIG.5d, the first drive signal generator V1outputs a square wave signal. As a rising edge of the square wave signal is output, a voltage Vbe2between the base and the emitter of the triode Q2gradually increases. When Vbe2of the triode Q2is greater than 0.7 V, the triode Q2is switched on, the energy storage capacitor C2charges the capacitor Cdg and the capacitor Cgs of the switch circuit305through the diode D2and the triode Q2, a voltage on the energy storage capacitor C2decreases, and a voltage on the capacitor Cdg and the capacitor Cgs increases until the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305is greater than the voltage on the energy storage capacitor C2. A voltage on the capacitor C3gradually increases with a voltage of the signal output by the first drive signal generator V1. When the voltage on the capacitor C3is greater than a voltage between the base and the emitter of the triode Q4, the triode Q4is switched on, and the power supply VCC charges the capacitor Cdg and the capacitor Cgs of the switch circuit305through the triode Q4, so that the drain and the source of the MOS transistor M0of the switch circuit305are connected.

As the first drive signal generator V1outputs a falling edge of the square wave signal, a voltage Vbe3between the base and the emitter of the triode Q3gradually decreases. When Vbe3of the triode Q3is less than (−0.7) V, the triode Q3is switched on, the capacitor Cdg and the capacitor Cgs of the switch circuit305charge the energy storage capacitor C2through the triode Q3and the diode D3, the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305decreases, and the voltage on the energy storage capacitor C2increases until the voltage on the energy storage capacitor C2is greater than the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305. The voltage on the capacitor C3gradually decreases along with the voltage of the signal output by the first drive signal generator V1. When the voltage on the capacitor C3is less than the voltage Vbe1between the base and the emitter of the triode Q1, the triode Q1is switched on, and the capacitor Cdg and the capacitor Cgs of the switch circuit305discharge to the ground through the triode Q1until the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305is 0, so that the drain and the source of the MOS transistor M0of the switch circuit305are disconnected.

Herein, it should be noted that, for a specific operating principle of the circuit shown inFIG.7, refer to related descriptions of the operating principle ofFIG.5a.

Herein, it should be noted that, in the circuits shown inFIG.5a,FIG.5b,FIG.5c, andFIG.7, the first moment and the second moment are moments in a process of outputting the rising edge of the drive signal by the first drive signal generator V1, and the first moment is earlier than the second moment; and the third moment and the fourth moment are moments in a process of outputting the falling edge of the drive signal by the first drive signal generator V1, and the third moment is earlier than the fourth moment. Optionally, the first moment may be earlier than the third moment, or the first moment is later than the fourth moment.

The control circuit303includes a first drive signal generator V1and a second drive signal generator V2, and that the control circuit303is connected to both the push-pull drive circuit307and the energy recovery circuit308specifically includes:as shown inFIG.6a, a positive electrode of the first drive signal generator V1is connected to the first terminal of the resistor R1through a resistor R3, a negative electrode of the first drive signal generator V1is grounded, a positive electrode of the second drive signal generator V2is connected to the first terminal of the resistor R2through a resistor R6, and a negative electrode of the second drive signal generator V2is grounded; or as shown inFIG.8, a positive electrode of the first drive signal generator V1is connected to the first terminal of the resistor R1through a resistor R3, a negative electrode of the first drive signal generator V1is grounded, a positive electrode of the second drive signal generator V2is connected to the first terminal of the capacitor C4through a resistor R6, and a negative electrode of the second drive signal generator V2is grounded.

Specifically, the first drive signal generator V1outputs a drive signal. When a rising edge of the drive signal is output, a voltage V1output by the first drive signal generator V1gradually increases. In addition, when the voltage V1output by the first drive signal generator is greater than a breakover voltage Vbe2, for example, 0.7 V, of the triode Q2in the energy recovery circuit308at the first moment, the collector and the emitter of the triode Q2are connected, and the capacitor C2of the energy recovery circuit308charges the capacitor Cdg and the capacitor Cgs of the switch circuit305through the diode D2and the triode Q2until a voltage on the capacitor C2is less than that on the capacitor Cdg and the capacitor Cgs of the switch circuit305. In this case, a voltage on the junction capacitor of the switch circuit305reaches an intermediate level. When the second drive signal generator V2outputs a rising edge of a drive signal, the capacitor C3is charged. When a voltage on the capacitor C3is greater than a breakover voltage Vbe4, for example, 0.7 V, of the triode Q4at the second moment, the collector and the emitter of the triode Q4are connected, and the power supply VCC charges the capacitor Cdg and the capacitor Cgs of the switch circuit305through the triode Q4in the push-pull drive circuit307until the voltage on the capacitor Cdg and the capacitor Cgs is equal to a difference between a voltage of the power supply VCC and a voltage drop Vce of the triode Q4. In this case, the voltage on the junction capacitor of the switch circuit305reaches a high level, and the switch circuit305is switched on. A loop for charging the capacitor Cdg and the capacitor Cgs of the switch circuit305is shown inFIG.6b.

When the first drive signal generator V1outputs a falling edge of the drive signal, the voltage V1output by the first drive signal generator V1gradually decreases. When the difference between the voltage of the drive signal output by the first drive signal generator V1and the voltage on the capacitor Cdg and the capacitor Cgs is greater than a breakover voltage Vbe3of the triode Q3, the collector and the emitter of the triode Q3are connected. The capacitor Cdg and the capacitor Cgs of the switch circuit305charge the capacitor C2of the energy recovery circuit308through the triode D3and the triode Q3until the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305is less than the voltage on the capacitor C2. In this case, the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305drops from the high level to the intermediate level. When the second drive signal generator V2outputs a falling edge of the drive signal, the voltage of the drive signal output by the second drive signal generator V2gradually decreases. As the voltage of the drive signal output by the second drive signal generator V2decreases, the voltage on the capacitor C3gradually decreases. When the voltage on the capacitor C3is less than a breakover voltage Vbe1, for example, −0.7 V, of the triode Q1at the fourth moment, the capacitor Cdg and the capacitor Cgs of the switch circuit305discharge to the ground through the triode Q1in the push-pull drive circuit307, so that the capacitor Cdg and the capacitor Cgs of the switch circuit305drop from the intermediate level to a low level, and the switch circuit305is switched off. A discharging loop for the capacitor Cdg and the capacitor Cgs of the switch circuit305is shown inFIG.6c.

Delays of the first drive signal generator and the second drive signal generator are adjusted to achieve the objective that the first moment is earlier than the second moment and the third moment is earlier than the fourth moment. In a process of driving a rising edge, a drive signal of the energy recovery circuit308precedes a drive signal of the push-pull drive circuit307. In a process of driving a falling edge, a drive signal of the energy recovery circuit308still precedes a drive signal of the push-pull drive circuit307. In this way, the energy recovery circuit308provides an intermediate level, to provide a part of drive energy during switching-on, and recover a part of drive energy stored on the capacitor Cdg and capacitor Cgs of the switch circuit305during switching-off.

After a drive voltage rises to the voltage on the capacitor C2of the energy recovery circuit308, the drive circuit is properly driven to provide a voltage required for fully switching on or off the switch circuit305, that is, a high level or a low level. During switching-on, energy required by the capacitor Cdg and the capacitor Cgs of the switch circuit305to rise from an intermediate level to a specified voltage corresponding to driving to full switching-on is supplemented. During switching-off, energy that remains on the junction capacitor of the switch circuit305after recovery is extracted to reach a specified voltage corresponding to driving to a switched-off state. Therefore, it can be considered that the drive circuit is a three-level drive circuit, that is, a high level, an intermediate level, and a low level.

Optionally, the first drive signal generator V1or the second drive signal generator V2may be a drive chip, and the drive chip may be constituted by a resistor and a diode that includes a push-pull circuit and a corresponding drive amplifier circuit, where the push-pull circuit includes a MOS transistor. A front-end input signal of the drive chip is used to adjust operating statuses of a push-pull drive circuit and an energy recovery drive circuit. A drive signal of the drive chip may be implemented by a control chip or a logic gate.

Herein, it should be noted that, for a specific operating principle of the circuit shown inFIG.8, refer to related descriptions of the operating principle ofFIG.6a.

Herein, it should be noted that, in the circuits shown inFIG.6a,FIG.6b,FIG.6c, andFIG.8, the first moment and the second moment are moments in a process of outputting the rising edge of the drive signal by the first drive signal generator V1, and the first moment is earlier than the second moment; and the third moment and the fourth moment are moments in a process of outputting the falling edge of the drive signal by the second drive signal generator V2, and the third moment is earlier than the fourth moment. Optionally, the first moment may be earlier than the third moment, or the first moment is later than the fourth moment.

By controlling timings of outputting signals by the first drive signal generator V1and the second drive signal generator V2, the signal output by the first drive signal generator V1inFIG.5amay be output based on the first drive signal generator V1and the second drive signal generator V2.

The resistor R1is configured to provide a pulse control signal for the energy recovery circuit308, so that the corresponding triodes Q2and Q3operate in a saturated state. In addition, the resistor R1is also a drive current-limiting resistor, and a base current Ib of the triodes Q2and Q3may be adjusted to adjust a size of a current at which the energy recovery circuit308charges and discharges the capacitor Cdg and the capacitor Cgs of the switch circuit.

The diode D2is configured to: serve as a part of a charge/discharge conduction loop of the triode Q2; and with a reverse cut-off characteristic of the diode D2, prevent a CE junction of the triode Q2from being damaged due to a reverse voltage after the drive voltage of the capacitor Cdg and the capacitor Cgs of the switch circuit305is greater than the voltage on the capacitor C2of the energy recovery circuit308. Similarly, the diode D3is configured to: serve as a part of a charge/discharge conduction loop of the triode Q3; and prevent a CE junction of the triode Q3from being damaged due to a reverse voltage after the drive voltage of the capacitor Cdg and the capacitor Cgs of the switch circuit305is less than the voltage on the capacitor C2of the energy recovery circuit308.

R2and C3are configured to provide a pulse control signal for the push-pull drive circuit307. In addition, values of R2and C3may be adjusted, that is, time constants of R2and C3may be adjusted, to adjust an operating time difference between the triodes Q2and Q3in the energy recovery circuit308and the triodes Q1and Q4in the push-pull drive circuit307. The time difference may also be considered as a difference between a time at which the energy recovery circuit308starts to operate and a time at which the push-pull drive circuit307starts to operate. After the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305reaches the intermediate level generated by the energy recovery circuit308, the push-pull drive circuit307needs to quickly perform a switchover, and the direct current power supply306in place of the energy recovery circuit308continues to charge the capacitor Cdg and the capacitor Cgs of the switch circuit305. In addition, R2is also a drive current-limiting resistor, and a value of the resistor R2may be adjusted to adjust a base current Ib of the triodes Q1and Q4, so as to adjust a size of a current at which the push-pull drive circuit307charges and discharges the capacitor Cdg and the capacitor Cgs of the switch circuit.

Optionally, a rising edge speed and a falling edge speed of the drive signal output by the first drive signal generator may be adjusted.

The capacitor C2is configured to: in a process of charging the capacitor Cdg and the capacitor Cgs of the switch circuit305, provide energy required for the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305to reach an intermediate-level voltage; and in a process in which the capacitor Cdg and the capacitor Cgs of the switch circuit305discharge, recover energy released for the voltage on the capacitor Cdg and the capacitor Cgs of the switch circuit305to reach the intermediate-level voltage. After a system including the switch mode power supply30and the switch circuit305reaches a steady state, the voltage on C2is stabilized at half of the voltage of the direct current power supply VCC. In addition, a capacity of C2needs to be greater than 100 times a capacity of the junction capacitor of the switch circuit, to avoid an excessive voltage fluctuation on the capacitor C2.

R5is configured to provide a discharge circuit for the capacitor Cdg and the capacitor Cgs of the switch circuit305after a voltage output by the control circuit303becomes less than a breakover voltage Vbe corresponding to the triode Q4or Q1, to ensure reliable switching-off of the switch circuit305.

Herein, it should be noted that the capacitor C4inFIG.7andFIG.8has a same function as that of the resistor R2inFIG.5aandFIG.6a, and the capacitor C5and the resistor R1inFIG.7andFIG.8have a same function as that of the resistor R1inFIG.5aandFIG.6a. When the first drive signal generator V1outputs a steady-state level, the resistor R1is configured to clamp a voltage on the capacitor C5.

In a specific example, parameters of the devices inFIG.5a,FIG.5b,FIG.5c,FIG.6a,FIG.6b,FIG.6c,FIG.7, andFIG.8are as follows: A capacitance of the capacitor C2is 100 nF, a capacitance of the capacitor C3is 4.8 nF, a capacitance of the capacitor C4is 2 nF, a capacitance of the capacitor C5is 1 nF, a resistance of the resistor R1is 22Ω, a resistance of the resistor R2is 47Ω, a resistance of the resistor R3is 3Ω, a resistance of the resistor R4is 10 kΩ, a resistance of the resistor R5is 220Ω, models of the diode D2and the diode D3are MBRS130L, models of the triode Q1and the triode Q3are 2N2907, and models of the triode Q2and the triode Q4are 2N2219A.

Optionally, the triodes in the push-pull drive circuit may be replaced with MOS transistors.

It can be learned that, in the solutions of this application, in a process of charging the junction capacitor of the switch circuit, the energy recovery circuit is controlled to operate first so that the energy storage capacitor C2in the energy recovery circuit charges the junction capacitor of the switch circuit, and then the push-pull drive circuit is controlled to operate so that the power supply VCC charges the junction capacitor of the switch circuit; and when the junction capacitor of the switch circuit discharges, the energy recovery circuit is controlled to operate first so that the junction capacitor of the switch circuit charges the energy storage capacitor C2in the energy recovery circuit, and then the push-pull drive circuit is controlled to operate so that the junction capacitor of the switch circuit discharges to the ground.

By controlling an operating sequence of the energy recovery circuit and the push-pull drive circuit, a part of drive energy stored on the junction capacitor of the switch circuit is transferred to the energy storage capacitor in the energy recovery drive circuit, to recover and reuse the drive energy and prevent all drive energy from being consumed on a drive resistor and the push-pull drive circuit. This greatly reduces driving loss, so that overall system efficiency is higher.

Embodiments of this application are described in detail above. The principle and implementation of this application are described herein through specific examples. The descriptions about embodiments are merely provided to help understand the method and core ideas of this application. In addition, a person of ordinary skill in the art can make variations and modifications to this application in terms of the specific implementations and application scopes according to the ideas of this application. Therefore, the content of this specification shall not be construed as a limit to this application.