A soft-switching synchronous BUCK circuit, device, and operating method with resonant drive.

Abstract

This invention provides a soft-switching synchronous BUCK circuit and device with resonant drive, including a main circuit and a resonant drive circuit, which are coupled to each other via a coupling inductor. The main circuit consists of a DC power supply, a voltage divider assembly, an auxiliary assembly, a first coupling inductor, a main bridge arm, and a load circuit. The resonant drive circuit drives the upper bridge arm main switch and consists of a coupling storage assembly (comprising a drive power supply, a second coupling inductor, and an energy storage capacitor), a control assembly, and a bootstrap assembly. The control terminals of the lower bridge arm synchronous switch, the auxiliary assembly, and the control assembly are connected to a controller. Based on this circuit, a working method and control timing are provided to enable soft switching of the main switch in the synchronous BUCK main circuit. The resonant energy generated during the soft switching process of the main circuit is transferred to the drive circuit side via the coupling inductor for resonant drive of the main switch and energy recovery. The soft switching of the synchronous BUCK main circuit and the resonant energy of the drive circuit are coupled and transferred in a single loop, which reduces switching losses and eliminates the need for additional drive current to achieve resonant drive, thereby reducing the overall losses of the high-frequency synchronous BUCK converter.

Description

Technical Field

[0001] This invention relates to the field of soft-switching and drive circuit design of field-effect transistors, and specifically to a soft-switching synchronous BUCK circuit, device, and operating method with resonant drive. Background Technology

[0002] As power converters are developing towards higher frequencies and higher power densities, the switching process of the power MOSFETs in existing synchronous BUCK converters and the losses caused by their driving are becoming increasingly prominent. With the increase of switching frequency, the switching losses and driving losses of the power MOSFETs increase proportionally.

[0003] Currently, the switching speed of power MOSFETs is a significant factor affecting switching losses. The switching loss problem of power MOSFETs under high-frequency operating conditions can be solved using soft-switching technology. Ideally, soft-switching technology involves reducing the current or voltage of the switching transistor to zero during the switching process, and then allowing the voltage or current to rise slowly, so that the switching loss is approximately zero. Soft-switching enables high-frequency operation of power conversion devices and reduces harmonic interference. Currently, the main soft-switching technologies on the market are non-isolated DC / DC converters, with BUCK and BOOST converters being typical examples. These are widely used in new energy power generation, communication base station power supplies, data center power supplies, and electric vehicle charging stations. In recent years, various soft-switching topologies have been developed for these converters to achieve high power density, high performance, and high efficiency. The main technical approach is to add inductors, capacitors, and auxiliary switching transistors to the original converter structure to form a resonant network, reducing or eliminating the voltage and current overlap region during the switching process, thus completing the soft-switching process.

[0004] On the other hand, drive losses mainly stem from the energy dissipation of gate-source charge in the device. To reduce the conduction losses of power MOSFETs, they require low on-resistance. Under current semiconductor manufacturing processes, this means an increase in the input capacitance of the power MOSFET, resulting in more gate-source charge for the same drive voltage. Therefore, to reduce the losses of power MOSFETs, their drive circuits should possess high current driving capability to accelerate switching speed and reduce gate charge energy dissipation to lower drive losses. Resonant drive is a very effective method. Resonant drive utilizes the resonance of an inductor and capacitor to charge and discharge the gate-source capacitance of the power MOSFET, and controls the gate-source voltage of the power MOSFET through the control switch of the drive circuit, achieving energy recovery and utilization. It has advantages such as fast drive speed and low drive loss. Resonant drive circuits can be divided into two categories: continuous inductor current and discontinuous inductor current. Continuous inductor current drive circuits are simpler, require fewer components, have simpler control logic, and faster drive speed, but suffer from higher losses. Discontinuous inductor current drive circuits are more complex in structure, require more components, but have lower drive losses.

[0005] In contrast, existing non-isolated DC / DC converters require separate circuit structures to achieve both soft switching and resonant drive. The resonant process of these circuit structures is also completed independently, resulting in less efficient utilization of resonant energy. Furthermore, they require two or more independent inductors, leading to larger size, higher cost, and greater energy loss.

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] The purpose of this invention is to provide a soft-switching synchronous BUCK circuit and device with resonant drive. By utilizing a coupled inductor and through a corresponding working method and timing, the soft switching and resonant drive of the switching transistor can be realized simultaneously, thereby reducing the switching loss and drive loss of the high-frequency synchronous BUCK converter. This invention discloses a soft-switching synchronous BUCK circuit with resonant drive, including: a voltage divider component, an auxiliary component, a main bridge arm, a first coupled inductor, a load circuit, and a resonant drive circuit.

[0008] Wherein, the voltage divider assembly is connected in parallel across both ends of the DC power supply, the main bridge arm is connected in parallel across both ends of the voltage divider assembly, the input terminal of the auxiliary assembly is electrically connected to the center of the voltage divider assembly, the output terminal of the auxiliary assembly is electrically connected to the same-name terminal of the first coupling inductor, the center of the main bridge arm is electrically connected to the opposite-name terminal of the first coupling inductor and the first terminal of the load circuit, the second terminal of the load circuit is electrically connected to the negative terminal of the DC power supply, and the control terminal of the auxiliary assembly and the synchronous switch control terminal of the main bridge arm are electrically connected to the output terminal of the controller;

[0009] The main switch control terminal of the main bridge arm is electrically connected to the output terminal of the resonant drive circuit, the center of the main bridge arm is electrically connected to the negative terminal of the drive power supply of the resonant drive circuit, and the control terminal of the resonant drive circuit is used to be electrically connected to the output terminal of the controller.

[0010] The resonant drive circuit is configured to resonate and drive the main switch so that the main switch can achieve zero-voltage switching using resonant energy.

[0011] Preferably, the voltage divider assembly includes a first clamping capacitor and a second clamping capacitor. One end of the first clamping capacitor is electrically connected to the positive terminal of the DC power supply, and the other end of the first clamping capacitor is electrically connected to one end of the second clamping capacitor and one end of the auxiliary assembly. The other end of the second clamping capacitor is electrically connected to the negative terminal of the DC power supply.

[0012] Preferably, the auxiliary component includes a first auxiliary MOSFET and a second auxiliary MOSFET, wherein the source of the first auxiliary MOSFET is electrically connected to the other end of the first clamping capacitor, the drain of the first auxiliary MOSFET is electrically connected to the drain of the second auxiliary MOSFET, and the source of the second auxiliary MOSFET is electrically connected to the same-name terminal of the first coupling inductor.

[0013] Preferably, the main bridge arm includes a main switching MOSFET and a synchronous switching MOSFET. The drain of the main switching MOSFET is electrically connected to the positive terminal of the DC power supply. The source of the main switching MOSFET is electrically connected to the drain of the synchronous switching MOSFET, the opposite terminal of the first coupling inductor, the first terminal of the load circuit, and the negative terminal of the driving power supply of the resonant driving circuit. The source of the synchronous switching MOSFET is electrically connected to the negative terminal of the DC power supply. The gate of the main switching MOSFET is electrically connected to the output terminal of the resonant driving circuit. The gate of the synchronous switching MOSFET is electrically connected to the output terminal of the controller.

[0014] Preferably, the load circuit includes a main inductor, an output capacitor, and a load. One end of the main inductor is electrically connected to the source of the main switching MOSFET, and the other end of the main inductor is electrically connected to one end of the output capacitor and one end of the load. The other end of the output capacitor and the other end of the load are used to be electrically connected to the negative terminal of the DC power supply.

[0015] Preferably, the resonant driving circuit includes a driving power supply, a coupled storage component, a control component, and a bootstrap component;

[0016] The drive power supply is connected in parallel with the bootstrap assembly. The negative terminal of the drive power supply is electrically connected to the first terminal of the coupled storage assembly, the second terminal of the control assembly, and the source of the main switch MOSFET. The second terminal of the coupled storage assembly is electrically connected to the third terminal of the control assembly. The positive terminal of the drive power supply, the first terminal of the bootstrap assembly, and the first terminal of the control assembly are electrically connected. The second terminal of the bootstrap assembly is electrically connected to the second terminal of the control assembly. The output terminal of the control assembly is electrically connected to the gate of the main switch MOSFET.

[0017] Preferably, the coupled storage component includes an energy storage capacitor and a second coupled inductor. The negative terminal of the driving power supply is electrically connected to one end of the energy storage capacitor, the other end of the energy storage capacitor is electrically connected to the same-name terminal of the second coupled inductor, and the opposite-name terminal of the second coupled inductor is electrically connected to the third terminal of the control component.

[0018] Preferably, the control component includes a first control MOSFET, a second control MOSFET, a third control MOSFET, and a fourth control MOSFET. The drain of the first control MOSFET is electrically connected to the positive terminal of the drive power supply and the first terminal of the bootstrap assembly. The source of the first control MOSFET is electrically connected to the drain of the second control MOSFET, the source of the fourth control MOSFET, and the source of the main switch MOSFET. The source of the second control MOSFET is electrically connected to the negative terminal of the drive power supply and the second terminal of the bootstrap assembly. The drain of the fourth control MOSFET is electrically connected to the drain of the third control MOSFET. The source of the third control MOSFET is electrically connected to the opposite terminal of the second coupling inductor.

[0019] Preferably, the bootstrap assembly includes a bootstrap diode and a bootstrap capacitor. The positive terminal of the drive power supply is electrically connected to the anode of the bootstrap diode, the cathode of the bootstrap diode is electrically connected to one end of the bootstrap capacitor, and the other end of the bootstrap capacitor is electrically connected to the negative terminal of the drive power supply.

[0020] The present invention also provides a soft-switching synchronous BUCK device with resonant drive, including a controller and a soft-switching synchronous BUCK circuit with resonant drive as described in any of the above claims, wherein the control terminal of the auxiliary component, the control terminal of the main bridge arm, and the control terminal of the resonant drive circuit are electrically connected to the output terminal of the controller.

[0021] In summary, the present invention provides a soft-switching synchronous BUCK circuit and device with resonant drive. Utilizing a coupled resonant inductor and auxiliary switching devices, and through the provided operating method and timing, it achieves zero-voltage turn-on of the main switching MOSFET and zero-current turn-off of the synchronous MOSFET, as well as resonant drive of the main switching MOSFET, thereby reducing switching losses and drive losses of the switching transistors; thus reducing the overall loss of the high-frequency synchronous BUCK converter. Attached Figure Description

[0022] Figure 1 This is a circuit diagram of a soft-switching synchronous BUCK circuit and device with resonant drive provided in an embodiment of the present invention.

[0023] Figure 2 This is a timing waveform diagram of a soft-switching synchronous BUCK circuit and device with resonant drive provided in an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Please see Figure 1 The first embodiment of the present invention provides a soft-switching synchronous BUCK circuit with resonant drive, including: a voltage divider component 1, an auxiliary component 2, a main bridge arm 3, and a first coupling inductor L. r1 4. Load circuit and 5. Resonant drive circuit;

[0027] The voltage divider assembly 1 is connected in parallel across the two ends of the DC power supply U1, the main bridge arm 3 is connected in parallel across the two ends of the voltage divider assembly 1, the input end of the auxiliary assembly 2 is electrically connected to the center of the voltage divider assembly 1, and the output end of the auxiliary assembly 2 is connected to the first coupling inductor L. r1 Electrically connected to the same end of the main bridge arm 3, with the center of the main bridge arm 3 connected to the first coupling inductor L.r1 The opposite-name terminal of the load circuit 4 is electrically connected to the first terminal of the load circuit 4, the second terminal of the load circuit 4 is electrically connected to the negative terminal of the DC power supply U1, and the control terminal of the auxiliary component 2 and the synchronous switch control terminal of the main bridge arm 3 are electrically connected to the output terminal of the controller.

[0028] The main switch control terminal of the main bridge arm 3 is electrically connected to the output terminal of the resonant drive circuit 5, the center of the main bridge arm 3 is electrically connected to the negative terminal of the drive power supply of the resonant drive circuit 5, and the control terminal of the resonant drive circuit 5 is used to be electrically connected to the output terminal of the controller.

[0029] The resonant drive circuit 5 is configured to resonate and drive the main switch so that the main switch can achieve zero-voltage switching using resonant energy.

[0030] Specifically, in this embodiment, the soft-switching synchronous BUCK circuit with resonant drive comprises two parts: a soft-switching synchronous BUCK circuit and a resonant drive circuit for the main switching MOSFET of the synchronous BUCK circuit. The soft-switching synchronous BUCK circuit addresses the switching losses of the MOSFET, while the resonant drive circuit addresses the driving losses of the MOSFET.

[0031] In this embodiment, the soft-switching synchronous BUCK circuit with resonant drive achieves zero-voltage turn-on and resonant drive of the main switch MOS transistor of the main bridge arm 3 by using a coupled resonant inductor and the resonant drive circuit.

[0032] In one possible embodiment of the present invention, the voltage divider assembly 1 includes a first clamping capacitor C. L1 and the second clamping capacitor C L2 The first clamping capacitor C L1 One end is used for electrical connection to the positive terminal of DC power supply U1, and the first clamping capacitor C L1 The other end is connected to the second clamping capacitor C L2 One end of the auxiliary component 2 is electrically connected to the second clamping capacitor C. L2 The other end is used for electrical connection to the negative terminal of DC power supply U1.

[0033] Specifically, in this embodiment, the first clamping capacitor C L1 and the second clamping capacitor C L2 It is an essential component of the main bridge arm 3 half-bridge structure, mainly providing energy to the main bridge arm 3 and distributing voltage to the main bridge arm 3.

[0034] In one possible embodiment of the present invention, the auxiliary component 2 includes a first auxiliary MOS transistor M1 and a second auxiliary MOS transistor M2, wherein the source of the first auxiliary MOS transistor M1 is connected to the first clamping capacitor C. L1 The other end is electrically connected, the drain of the first auxiliary MOSFET M1 is electrically connected to the drain of the second auxiliary MOSFET M2, and the source of the second auxiliary MOSFET M2 is electrically connected to the first coupling inductor L. r1 Electrical connection of the same name terminal.

[0035] Specifically, in this embodiment, the first auxiliary MOSFET M1 and the second auxiliary MOSFET M2 can be NMOS transistors. The first auxiliary MOSFET M1 and the second auxiliary MOSFET M2 achieve zero-capacitance turn-on of the main switch of the main bridge arm 3. Due to the presence of the drain parasitic capacitance of the first auxiliary MOSFET M1 and the second auxiliary MOSFET M2, zero-voltage turn-off of the main switch of the main bridge arm 3 is achieved when the MOSFETs are turned off. It should be noted that in other embodiments, other types of auxiliary components can also be used; no specific limitation is made here, but these solutions are all within the protection scope of this invention.

[0036] In one possible embodiment of the present invention, the main bridge arm 3 includes a main switch MOSFET Q1 and a synchronous switch MOSFET Q2. The drain of the main switch MOSFET Q1 is electrically connected to the positive terminal of the DC power supply U1. The source of the main switch MOSFET Q1 is connected to the drain of the synchronous switch MOSFET Q2 and the first coupling inductor L. r1 The opposite terminal of the load circuit 4, the first terminal of the load circuit 4, and the negative terminal of the driving power supply of the resonant driving circuit 5 are electrically connected. The source of the synchronous switch MOSFET Q2 is electrically connected to the negative terminal of the DC power supply U1. The gate of the main switch MOSFET Q1 is electrically connected to the output terminal of the resonant driving circuit 5. The gate of the synchronous switch MOSFET Q2 is electrically connected to the output terminal of the controller.

[0037] Specifically, in this embodiment, the main switch MOSFET Q1 and the synchronous switch MOSFET Q2 can be NMOS transistors. The soft-switching synchronous BUCK circuit with resonant drive utilizes a coupled resonant inductor and auxiliary switching devices to achieve zero-voltage turn-on of the main switch MOSFET Q1. Due to the existence of the drain-source parasitic capacitance of the main switch MOSFET Q1, its drain-source voltage cannot change abruptly when the main switch MOSFET Q1 is turned off, thus achieving zero-voltage turn-off. The synchronous switch MOSFET Q2 also achieves zero-voltage turn-on, and its operation shows that its turn-off achieves zero-current turn-off. It should be noted that in other embodiments, other types of main bridge arms can also be used, which are not specifically limited here, but these solutions are all within the protection scope of this invention.

[0038] In one possible embodiment of the present invention, the load circuit 4 includes a main inductor L1, an output capacitor C1, and a load R1. One end of the main inductor L1 is electrically connected to the source of the main switch MOSFET Q1, and the other end of the main inductor L1 is electrically connected to one end of the output capacitor C1 and one end of the load R1. The other end of the output capacitor C1 and the other end of the load R1 are used to be electrically connected to the negative terminal of the DC power supply U1.

[0039] Specifically, in this embodiment, it can be seen from the load circuit 4 that the main inductor L1 and the output capacitor C1 form a low-pass filter. The principle of this filter design is to allow the DC component of the DC power supply U1 to pass through, while suppressing the harmonic components of the DC power supply to pass through. The output voltage on the capacitor is the DC component of the DC power supply U1 plus a small ripple. Finally, the current passing through the low-pass filter will be provided to the load R1.

[0040] In one possible embodiment of the present invention, the resonant driving circuit 5 includes a driving power supply U. C1 Coupled storage component 51, control component 52, and bootstrap component 53;

[0041] Among them, the drive power supply U C1 The drive power supply U is connected in parallel with the bootstrap assembly 53. C1 The negative terminal is electrically connected to the first terminal of the coupled storage component 51, the second terminal of the control component 52, and the source of the main switch MOS transistor Q1. The second terminal of the coupled storage component 51 is electrically connected to the third terminal of the control component 52. The drive power supply U C1 The positive terminal of the bootstrap assembly 53 is electrically connected to the first terminal of the control assembly, the second terminal of the bootstrap assembly 53 is electrically connected to the second terminal of the control assembly 52, and the output terminal of the control assembly 52 is electrically connected to the gate of the main switch MOS transistor Q1.

[0042] Specifically, in this embodiment, the coupled storage component 51 includes an energy storage capacitor C. O and the second coupled inductor L r2 The drive power supply U C1 The negative terminal of the energy storage capacitor C O One end is electrically connected, the energy storage capacitor C O The other end is coupled to the second inductor L r2 Electrical connection of the same name terminal, the second coupled inductor L r2The opposite terminal is electrically connected to the third terminal of the control component 52. The control component 52 includes a first control MOSFET S1, a second control MOSFET S2, a third control MOSFET S3, and a fourth control MOSFET S4. The drain of the first control MOSFET S1 is connected to the drive power supply U. C1 The positive terminal of the first control MOSFET S1 is electrically connected to the first terminal of the bootstrap assembly 53. The source of the first control MOSFET S1 is electrically connected to the drain of the second control MOSFET S2, the source of the fourth control MOSFET S4, and the source of the main switch MOSFET Q1. The source of the second control MOSFET S2 is electrically connected to the drive power supply U. C1 The negative terminal of the bootstrap assembly 53 is electrically connected to the second terminal of the bootstrap assembly 53. The drain of the fourth control MOS transistor S4 is electrically connected to the drain of the third control MOS transistor S3. The source of the third control MOS transistor S3 is connected to the second coupling inductor L. r2 The opposite-named terminals are electrically connected. The bootstrap assembly 53 includes a bootstrap diode D1 and a bootstrap capacitor C. b The drive power supply U C1 The positive terminal of the capacitor is electrically connected to the anode of the bootstrap diode D1, and the cathode of the bootstrap diode D1 is connected to the bootstrap capacitor C. b One end of the bootstrap capacitor C is electrically connected. b The other end is connected to the drive power supply U C1 The negative electrical connection.

[0043] Specifically, in this embodiment, the first control MOSFET S1, the second control MOSFET S2, the third control MOSFET S3, and the fourth control MOSFET S4 can be NMOS transistors. The resonant drive circuit 5 realizes the resonant drive of the main switch MOSFET Q1, which has a fast drive speed and can recover the gate-source capacitance energy of the main switch MOSFET Q1. The first control MOSFET S1, the second control MOSFET S2, the third control MOSFET S3, and the fourth control MOSFET S4 realize the zero-voltage turn-on of the MOSFETs in the main bridge arm. It should be noted that in other embodiments, other types of control components can also be used; no specific limitation is made here, but these solutions are all within the protection scope of this invention.

[0044] Please see Figure 2Specifically, in this embodiment, the soft-switching synchronous BUCK circuit with resonant drive is further explained through the following control timing. Let a complete control cycle be from t0 to t9. Assume the soft-switching synchronous BUCK circuit outputs a constant voltage. When the load remains unchanged, ripple is ignored, and the steady-state current on the main inductor L1 is IL1. The control timing of the synchronous switch MOSFET Q2, the first auxiliary MOSFET M1, the second auxiliary MOSFET M2, the first control MOSFET S1, the second control MOSFET S2, the third control MOSFET S3, and the fourth control MOSFET S4 is as follows:

[0045] The synchronous switch MOSFET Q2 is turned on from time t2 to time t5, and turned off at the rest of the time.

[0046] The first auxiliary MOSFET M1 is turned on during t0-t1 and t4-t6, and turned off at other times;

[0047] The second auxiliary MOSFET M2 is turned on during t0-t1 and t4-t6, and turned off at other times;

[0048] The first control MOSFET S1 is turned on from t7 to t0 and turned off at the rest of the time;

[0049] The second control MOSFET S2 is turned on from t2 to t6 and turned off at the rest of the time;

[0050] The third control MOS transistor S3 is turned on during t1-t3 and t6-t8, and turned off at other times.

[0051] The fourth control MOS transistor S4 is turned on during t1-t3 and t6-t8, and turned off at other times.

[0052] Under this control timing, the operation of the soft-switching synchronous BUCK circuit with resonant drive is as follows: Before time t0, the first control MOSFET S1 is in the on state, and the first auxiliary MOSFET M1, the second auxiliary MOSFET M2, the second control MOSFET S2, the third control MOSFET S3, and the fourth control MOSFET S4 are in the off state. The main switch MOSFET Q1 is in the on state, and the gate-source voltage ugs_Q1 of the main switch MOSFET Q1 drives the power supply U. C1 With the voltage at which the synchronous switch MOSFET Q2 is off, the DC power supply U1 supplies power to the main inductor L1, the output capacitor C1, and the load R1 through the main switch MOSFET Q1. The first clamping capacitor C... L1 The voltage across the terminals and the second clamping capacitor C L2 The sum of the voltages at both ends is equal to the DC power supply U1, and the current iQ1 on the main switch MOS transistor Q1 is equal to IL1.

[0053] During the t0~t1 stage: At time t0, the first auxiliary MOSFET M1 and the second auxiliary MOSFET M2 are turned on, and the first clamping capacitor C... L1 The voltage applied to the first coupled inductor L r1 The first coupled inductor L charges it. r1 Current iL on r1 As the current increases linearly, the current i1 in the branch of the main switch MOS transistor Q1 also increases accordingly.

[0054] During the t1~t2 phase: At time t1, the first auxiliary MOSFET M1, the second auxiliary MOSFET M2, and the first control MOSFET S1 are turned off, while the third control MOSFET S3 and the fourth control MOSFET S4 are turned on, and the first coupling inductor L... r1 Current iL on r1 Transferred to the second coupled inductor L r2 Above, the second coupled inductor L r2 current iL r2 The gate-source capacitance of the main switch MOSFET Q1 resonates with the gate-source capacitance of the main switch MOSFET Q1, discharging the gate-source capacitance of the main switch MOSFET Q1 until ugs_Q1 drops to 0 at time t2. The anti-parallel diode of the second control MOSFET S2 turns on, the main switch MOSFET Q1 turns off, its drain-source voltage uds_Q1 rises to the voltage of the DC power supply U1, the current i1 in the branch of the main switch MOSFET Q1 drops to 0, the drain-source voltage uds_Q2 of the synchronous switch MOSFET Q2 drops to 0, and the anti-parallel diode of the synchronous switch MOSFET Q2 turns on.

[0055] During the t2~t3 phase: At time t2, the second control MOSFET S2 turns on with zero voltage after its anti-parallel diode is turned on, and the synchronous switch MOSFET Q2 turns on with zero voltage after its anti-parallel diode is turned on. The second coupling inductor L... r2 The current iLr2 flows into the energy storage capacitor C O until time t3, when iLr2 drops to 0.

[0056] During the t3~t4 stage: At time t3, the third control MOSFET S3 and the fourth control MOSFET S4 are turned off, the switching states of the remaining MOSFETs remain unchanged, the main inductor L1 freewheels through the synchronous switch MOSFET Q2, and the output capacitor C1 supplies power to the load R1.

[0057] During the t4~t5 phase: At time t4, the first auxiliary MOSFET M1 and the second auxiliary MOSFET M2 are turned on, and the second clamping capacitor C... L2 The voltage applied to the first coupled inductor L r1 The first coupled inductor L charges it.r1 The current iLr1 on the circuit increases linearly (opposite to the direction of the t0~t1 stage). At this time, the direction of the current iLr1 is opposite to the direction of the current i2 in the branch of the synchronous switch MOS transistor Q2, and the current i2 decreases.

[0058] t5~t6 stage: At time t5, the first coupled inductor L r1 The current iLr1 is greater than the steady-state current IL1 on the main inductor L1. The current on the main inductor L1 is provided by iLr1. The current i2 in the branch of the synchronous switch MOSFET Q2 drops to 0, the synchronous switch MOSFET Q2 is turned off, and the portion of the iLr1 current greater than IL1 flows into the branch of the main switch MOSFET Q1, discharging the drain-source capacitance of the main switch MOSFET Q1 and charging the drain-source capacitance of the synchronous switch MOSFET Q2. That is, the three resonate. The drain-source voltage uds_Q1 of the main switch MOSFET Q1 drops to 0, and the drain-source voltage uds_Q2 of the synchronous switch MOSFET Q2 rises to the DC power supply voltage U1.

[0059] During the t6~t7 stage: At time t6, the first auxiliary MOSFET M1, the second auxiliary MOSFET M2, and the second control MOSFET S2 are turned off, while the third control MOSFET S3 and the fourth control MOSFET S4 are turned on, and the first coupling inductor L... r1 The current iLr1 on the current is transferred to the second coupled inductor L r2 Above, the second coupled inductor L r2 The current iLr2 resonates with the gate-source capacitance of the main switch MOSFET Q1, charging the gate-source capacitance of the main switch MOSFET Q1 until time t7, when ugs_Q1 equals the drive power supply U. C1 After the anti-parallel diode of the first control MOSFET S1 is turned on, the first control MOSFET S1 is turned on. During this stage, the gate-source voltage ugs_Q1 of the main switch MOSFET Q1 gradually increases, that is, the main switch MOSFET Q1 is gradually turned on. The current i1 in the branch of the main switch MOSFET Q1 changes from negative to positive and rises until it is equal to the steady-state current IL1 of the main inductor L1. During the turn-on process, the drain-source voltage uds_Q1 of the main switch MOSFET Q1 has dropped to 0, achieving zero-voltage turn-on.

[0060] During the t7~t8 phase: At time t7, the first control MOSFET S1 turns on with zero voltage after its anti-parallel diode is turned on, and the second coupling inductor L... r2 The current iLr2 flows into the drive power supply voltage U C1 until time t8 when iLr2 drops to 0.

[0061] During the t8~t9 phase: At time t8, the third control MOSFET S3 and the fourth control MOSFET S4 are turned off, while the switching states of the remaining MOSFETs remain unchanged. The DC power supply U1 supplies power to the main inductor L1, the output capacitor C1, and the load R1 through the main switch MOSFET Q1. This circuit state continues until time t9, which is the next cycle time t0, and then a new cycle begins.

[0062] In summary, the soft-switching synchronous BUCK circuit with resonant drive achieves soft switching of the main switch MOSFET Q1 and the synchronous MOSFET Q2 through a coupled resonant inductor and auxiliary switching devices. The coupled resonant inductor can also transfer the resonant energy of the main circuit's soft switching to the driving circuit of the main switch MOSFET Q1, realizing the resonant drive of the main switch MOSFET Q1. To a certain extent, it reduces the switching loss and driving loss of the MOSFET, and the overall circuit efficiency is high. It is especially suitable for synchronous BUCK converters with high switching frequencies and has good application value.

[0063] The second embodiment of the present invention provides a soft-switching synchronous BUCK device with resonant drive, including a controller and a soft-switching synchronous BUCK circuit with resonant drive as described in any of the above. The control terminal of the auxiliary component 2, the control terminal of the main bridge arm 3, and the control terminal of the resonant drive circuit 5 are electrically connected to the output terminal of the controller.

[0064] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A soft-switching synchronous BUCK circuit with resonant drive, comprising a main circuit and a resonant drive circuit, the two being coupled by a coupling inductor; the main circuit consists of a DC power supply, a voltage divider component, an auxiliary component, a first coupling inductor, a main bridge arm, and a load circuit; the resonant drive circuit drives the main switch transistor of the upper bridge arm, and consists of a coupling storage component composed of a drive power supply, a second coupling inductor, and an energy storage capacitor, a control component, and a bootstrap component; in, The voltage divider assembly includes a first clamping capacitor and a second clamping capacitor, which together form a bridge arm; the load circuit includes a main inductor, an output capacitor, and a load, with the output capacitor connected in parallel with the load and then connected in series with the main inductor; the main bridge arm includes a main switching MOSFET and a synchronous switching MOSFET; the auxiliary assembly includes a first auxiliary MOSFET and a second auxiliary MOSFET, which are connected in series; the control assembly includes a first control MOSFET, a second control MOSFET, a third control MOSFET, and a fourth control MOSFET, with the first and second control MOSFETs connected to form a bridge arm, and the third and fourth control MOSFETs connected in series and electrically connected to the center of the bridge arm formed by the first and second control MOSFETs; Wherein, the same-name terminal of the first coupling inductor is electrically connected to the output terminal of the auxiliary component, and the opposite-name terminal of the first coupling inductor is electrically connected to the center of the main bridge arm; the same-name terminal of the second coupling inductor is electrically connected to one end of the energy storage capacitor, and the opposite-name terminal of the second coupling inductor is electrically connected to one end of the control component. Wherein, the first coupling inductor and the second coupling inductor are mutually coupled, characterized in that, on the one hand, the first coupling inductor is used to resonate with the drain-source capacitance of the main switch transistor of the upper bridge arm of the main circuit to realize soft switching, and on the other hand, it works together with the second coupling inductor to couple the electrical energy of the main circuit to the drive circuit; the second coupling inductor is used to work together with the first coupling inductor to couple the electrical energy of the main circuit to the drive circuit, and on the other hand, it is used to resonate with the gate-source capacitance of the main switch transistor of the upper bridge arm of the main circuit to drive the main switch transistor of the upper bridge arm of the main circuit.

2. The soft-switching synchronous BUCK circuit with resonant drive according to claim 1, characterized in that, Let a complete control cycle be from t0 to t9. The synchronous switching MOSFET, the first auxiliary MOSFET, the second auxiliary MOSFET, the first control MOSFET, the second control MOSFET, the third control MOSFET, and the fourth control MOSFET adopt the following control timing: the synchronous switching MOSFET is turned on after time t2 until time t5, and is turned off at the rest of the time; the first auxiliary MOSFET is turned on during time t0-t1 and time t4-t6, and is turned off at the rest of the time. The second auxiliary MOSFET is turned on during t0-t1 and t4-t6, and turned off at other times; The first control MOSFET is turned on during t7-t0 and turned off at other times; The second control MOSFET is turned on during t2-t6 and turned off at other times; The third control MOSFET is turned on during t1-t3 and t6-t8, and turned off at other times. The fourth control MOSFET is turned on during t1-t3 and t6-t8, and turned off at other times.

3. The soft-switching synchronous BUCK circuit with resonant drive according to claim 2, characterized in that, Under the adopted control timing, the working method for the first half of the cycle is as follows: During the t0~t1 phase: At time t0, the first auxiliary MOSFET and the second auxiliary MOSFET are turned on, and the voltage on the first clamping capacitor is applied to the first coupling inductor to charge it. The current iL in the first coupling inductor... r1 As the current increases linearly, the current i1 in the main switch MOS transistor branch also increases accordingly. During the t1~t2 phase: At time t1, the first auxiliary MOSFET, the second auxiliary MOSFET, and the first control MOSFET are turned off, while the third control MOSFET and the fourth control MOSFET are turned on. The current iL on the first coupling inductor... r1 The current iL in the second coupled inductor is transferred to the second coupled inductor. r2 The gate-source capacitance of the main switch MOSFET resonates with the gate-source capacitance of the main switch MOSFET, discharging the gate-source capacitance of the main switch MOSFET until ugs_Q1 drops to 0 at time t2. The anti-parallel diode of the second control MOSFET turns on, the main switch MOSFET turns off, its drain-source voltage uds_Q1 rises to the voltage of the DC power supply, the current i1 in the branch of the main switch MOSFET drops to 0, the drain-source voltage uds_Q2 of the synchronous switch MOSFET drops to 0, and the anti-parallel diode of the synchronous switch MOSFET turns on. t2~t3 stage: At time t2, the second control MOSFET turns on with zero voltage after its anti-parallel diode is turned on, and the synchronous switch MOSFET turns on with zero voltage after its anti-parallel diode is turned on. The current iLr2 on the second coupling inductor flows into the energy storage capacitor until iLr2 drops to 0 at time t3. During the t3~t4 stage: at time t3, the third control MOSFET and the fourth control MOSFET are turned off, the switching states of the remaining MOSFETs remain unchanged, the main inductor freewheels through the synchronous switching MOSFET, and the output capacitor supplies power to the load.

4. The soft-switching synchronous BUCK circuit with resonant drive according to claim 2, characterized in that, Under the adopted control timing, the working method for the second half of the cycle is as follows: During the t4~t5 stage: At time t4, the first auxiliary MOS transistor and the second auxiliary MOS transistor are turned on, and the voltage on the second clamping capacitor is applied to the first coupling inductor to charge it. The current iLr1 on the first coupling inductor rises linearly (in the opposite direction to the t0~t1 stage). At this time, the direction of the current iLr1 is opposite to the direction of the current i2 in the synchronous switch MOS transistor branch, and the current i2 decreases. During the t5~t6 phase: At time t5, the current iLr1 of the first coupled inductor is greater than the steady-state current IL1 of the main inductor. The current in the main inductor is provided by iLr1. The current i2 of the synchronous switch MOSFET branch drops to 0, the synchronous switch MOSFET is turned off, and the portion of the iLr1 current greater than IL1 flows into the main switch MOSFET branch, discharging the drain-source capacitance of the main switch MOSFET and charging the drain-source capacitance of the synchronous switch MOSFET. That is, the three resonate. The drain-source voltage uds_Q1 of the main switch MOSFET drops to 0, and the drain-source voltage uds_Q2 of the synchronous switch MOSFET rises to the DC power supply voltage. During the t6~t7 phase: At time t6, the first auxiliary MOSFET, the second auxiliary MOSFET, and the second control MOSFET are turned off, while the third and fourth control MOSFETs are turned on. The current iLr1 on the first coupling inductor is transferred to the second coupling inductor. The current iLr2 in the second coupling inductor resonates with the gate-source capacitance of the main switching MOSFET, charging the gate-source capacitance of the main switching MOSFET until time t7, when ugs_Q1 equals the driving power supply voltage U. C1 After the anti-parallel diode of the first control MOSFET is turned on, the first control MOSFET is turned on. During this stage, the gate-source voltage ugs_Q1 of the main switch MOSFET gradually increases, that is, the main switch MOSFET is gradually turned on. The current i1 of the main switch MOSFET branch changes from negative to positive and rises until it is equal to the steady-state current IL1 of the main inductor. During the turn-on process, the drain-source voltage uds_Q1 of the main switch MOSFET has dropped to 0, realizing zero-voltage turn-on. During the t7~t8 phase: At time t7, the first control MOSFET turns on with zero voltage after its anti-parallel diode is turned on, and the current iLr2 on the second coupling inductor flows into the drive power supply voltage U. C1 until time t8, iLr2 drops to 0; t8~t9 stage: At time t8, the third control MOSFET and the fourth control MOSFET are turned off, while the switching states of the remaining MOSFETs remain unchanged. The DC power supply supplies power to the main inductor, the output capacitor and the load through the main switch MOSFET. This circuit state continues until time t9, which is the next cycle time t0, and then a new cycle begins.

5. A soft-switching synchronous BUCK device with resonant drive, characterized in that, It includes a controller and a soft-switching synchronous BUCK circuit with resonant drive as described in any one of claims 1-4, wherein the control terminal of the auxiliary component, the control terminal of the main bridge arm, and the control terminal of the resonant drive circuit are electrically connected to the output terminal of the controller.

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