Isolated type dead-zone-free soft switching resonant conversion circuit

Abstract

The invention provides an isolated soft switching resonant conversion circuit without dead zone setting, belongs to the technical field of power electronic power conversion, and aims to solve the problem that a resonant conversion circuit in the prior art is difficult to meet high-frequency application due to the influence of dead zone setting. Compared with an existing soft switching resonant converter based on a half-bridge or full-bridge structure, the soft switching resonant converter provided by the invention does not need to set dead time for a switching tube, so that the soft switching resonant converter is more suitable for a high-frequency application scene; in addition, the source electrodes of the two switch tubes are connected with one end of the input power supply at the same time, so that the drive circuit of the switch tubes is simpler than a full-bridge or half-bridge circuit in design, and the circuit is simpler.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic power conversion, and more particularly to an isolated soft-switching resonant conversion circuit with no dead zone setting. Background Art

[0002] High-frequency design is an effective way to improve the power density of power electronic converters. To overcome the increased switching losses associated with high-frequency operation, soft-switching techniques are often employed simultaneously. Among various soft-switching techniques, resonant soft switching is the most common. However, existing resonant converter circuits are generally based on half-bridge or full-bridge structures, such as series resonant circuits, parallel resonant circuits, series-parallel resonant circuits, and LLC resonant circuits. To prevent simultaneous conduction of the upper and lower switches in a half-bridge or full-bridge resonant circuit, a dead-time is added to the control signals of the upper and lower switches. For applications with very high switching frequencies, a dead-time that is too long can severely impact converter performance, while a dead-time that is too short can create the risk of shoot-through. Overall, while existing soft-switching techniques help reduce switching losses in power electronic converters, the dead-time setting still restricts the development of higher-frequency converters. Summary of the Invention

[0003] In order to overcome the defect that the resonant conversion circuit in the above-mentioned prior art is affected by the dead zone setting and is difficult to meet high-frequency applications, the present invention provides an isolated soft-switching resonant conversion circuit without dead zone setting. The circuit structure is simple, and there is no need to set a dead zone time for the switch tube, which is more suitable for high-frequency application scenarios.

[0004] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0005] An isolated, dead-zone-free soft-switching resonant conversion circuit includes: a first switching tube S1, a second switching tube S2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a three-winding transformer, and a rectifier unit;

[0006] The source of the first switching transistor S1 and the source of the second switching transistor S2 are respectively connected to one end of the power supply, the drain of the first switching transistor S1 is connected to one end of the first inductor L1, and the drain of the second switching transistor S2 is connected to one end of the second inductor L2; the gate of the first switching transistor S1 and the gate of the second switching transistor S2 serve as input ends of a control signal, used to control the conduction and shutdown of the first switching transistor S1 and the second switching transistor S2; the other end of the first inductor L1 is connected to one end of the first winding of the three-winding transformer, and the other end of the second inductor L2 is connected to one end of the second winding of the three-winding transformer; the other end of the first winding and the other end of the second winding are respectively connected to the other end of the power supply;

[0007] The two ends of the first capacitor C1 are respectively connected to the source and drain of the first switch tube S1, and the two ends of the second capacitor C2 are respectively connected to the source and drain of the second switch tube S2;

[0008] The two ends of the third winding in the three-winding transformer are respectively connected to the two input ends of the rectifier unit, and the two output ends of the rectifier unit are respectively connected to the two ends of the load.

[0009] Preferably, the first switch transistor S1 and the second switch transistor S2 are both N-channel MOS transistors.

[0010] Preferably, the first switch S1 and the second switch S2 are alternately turned on with a duty cycle of 0.5, and no dead time is set between the control signals of the first switch S1 and the second switch S2.

[0011] Preferably, the voltage across the load is adjusted by changing the switching frequency of the first switch tube S1 and the second switch tube S2.

[0012] Preferably, the first winding and the second winding of the three-winding transformer have the same number of turns.

[0013] Preferably, the voltage across the load is adjusted by changing the turns ratio of the three-winding transformer.

[0014] Preferably, the rectifier unit is a full-bridge rectifier circuit, comprising: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a filter capacitor Co;

[0015] The anode of the first diode D1 is connected to the cathode of the second diode D2 and serves as the first input terminal of the rectifier unit; the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and serves as the second input terminal of the rectifier unit; the cathode of the first diode D1 is connected to the cathode of the third diode D3 and one end of the filter capacitor Co, respectively, and serves as the first output terminal of the rectifier unit; the anode of the second diode D2 is connected to the anode of the fourth diode D4 and the other end of the filter capacitor Co, respectively, and serves as the second output terminal of the rectifier unit;

[0016] The first input end and the second input end of the rectifier unit are respectively connected to the two ends of the third winding; the first output end and the second output end of the rectifier unit are respectively connected to the two ends of the load.

[0017] Preferably, the rectifier unit is a half-bridge rectifier circuit, comprising: a fifth diode D5, a sixth diode D6, a filter capacitor Co1 and a filter capacitor Co2;

[0018] The anode of the fifth diode D5 and the cathode of the sixth diode D6 are connected and serve as the first input terminal of the rectifier unit, one end of the filter capacitor Co1 and one end of the filter capacitor Co2 are connected and serve as the second input terminal of the rectifier unit; the cathode of the fifth diode D5 and the other end of the filter capacitor Co1 are connected and serve as the first output terminal of the rectifier unit; the anode of the sixth diode D6 and the other end of the filter capacitor Co2 are connected and serve as the second output terminal of the rectifier unit;

[0019] The first input end and the second input end of the rectifier unit are respectively connected to the two ends of the third winding; the first output end and the second output end of the rectifier unit are respectively connected to the two ends of the load.

[0020] Preferably, the circuit further comprises a resonant capacitor Cr;

[0021] Two ends of the resonant capacitor Cr are connected to the drain of the first switch tube S1 and the drain of the second switch tube S2 respectively.

[0022] Preferably, the power supply is a DC voltage source.

[0023] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0024] The present invention provides an isolated soft-switching resonant converter circuit with no dead-zone setting. Compared with existing soft-switching resonant converters based on half-bridge or full-bridge structures, the soft-switching resonant converter provided by the present invention does not require setting a dead-zone time for the switching tube, and is therefore more suitable for high-frequency application scenarios. In addition, the sources of the two switching tubes are simultaneously connected to one end of the input power supply, so the driving circuit of the switching tube is simpler and more concise than the full-bridge or half-bridge circuit design. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an isolated, dead-zone-free soft-switching resonant conversion circuit provided in Example 1.

[0026] Figure 2 This is a structural diagram of the full-bridge rectifier circuit provided in Example 1.

[0027] Figure 3 This is a structural diagram of the half-bridge rectifier circuit provided in Example 1.

[0028] Figure 4 This is a structural diagram of another isolated soft-switching resonant conversion circuit with no dead zone provided in Example 2.

[0029] Figure 5 This is a specific structural diagram of another isolated soft-switching resonant conversion circuit with no dead zone provided in Example 2.

[0030] Figure 6 This is a schematic diagram of the operating status of the isolated, dead-zone-free soft-switching resonant conversion circuit provided in Example 2. DETAILED DESCRIPTION

[0031] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present application;

[0032] In order to better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size;

[0033] It is understandable to those skilled in the art that some well-known structures and descriptions thereof may be omitted in the drawings.

[0034] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] like Figure 1 As shown, this embodiment provides an isolated soft-switching resonant conversion circuit with no dead zone setting, including: a first switch tube S1, a second switch tube S2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a three-winding transformer and a rectifier unit;

[0037] The source of the first switching transistor S1 and the source of the second switching transistor S2 are respectively connected to one end of the power supply, the drain of the first switching transistor S1 is connected to one end of the first inductor L1, and the drain of the second switching transistor S2 is connected to one end of the second inductor L2; the gate of the first switching transistor S1 and the gate of the second switching transistor S2 serve as input ends of a control signal, used to control the conduction and shutdown of the first switching transistor S1 and the second switching transistor S2; the other end of the first inductor L1 is connected to one end of the first winding of the three-winding transformer, and the other end of the second inductor L2 is connected to one end of the second winding of the three-winding transformer; the other end of the first winding and the other end of the second winding are respectively connected to the other end of the power supply;

[0038] The two ends of the first capacitor C1 are respectively connected to the source and drain of the first switch tube S1, and the two ends of the second capacitor C2 are respectively connected to the source and drain of the second switch tube S2;

[0039] The two ends of the third winding in the three-winding transformer are respectively connected to the two input ends of the rectifier unit, and the two output ends of the rectifier unit are respectively connected to the two ends of the load;

[0040] The first switch tube S1 and the second switch tube S2 are both N-channel MOS tubes;

[0041] The first winding and the second winding of the three-winding transformer have the same number of turns;

[0042] When the rectifier unit is a full-bridge rectifier circuit, it includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a filter capacitor Co;

[0043] The anode of the first diode D1 is connected to the cathode of the second diode D2 and serves as the first input terminal of the rectifier unit; the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and serves as the second input terminal of the rectifier unit; the cathode of the first diode D1 is connected to the cathode of the third diode D3 and one end of the filter capacitor Co, respectively, and serves as the first output terminal of the rectifier unit; the anode of the second diode D2 is connected to the anode of the fourth diode D4 and the other end of the filter capacitor Co, respectively, and serves as the second output terminal of the rectifier unit;

[0044] The first input terminal and the second input terminal of the rectifier unit are respectively connected to the two ends of the third winding; the first output terminal and the second output terminal of the rectifier unit are respectively connected to the two ends of the load;

[0045] When the rectifier unit is a half-bridge rectifier circuit, it includes: a fifth diode D5, a sixth diode D6, a filter capacitor Co1 and a filter capacitor Co2;

[0046] The anode of the fifth diode D5 and the cathode of the sixth diode D6 are connected and serve as the first input terminal of the rectifier unit, one end of the filter capacitor Co1 and one end of the filter capacitor Co2 are connected and serve as the second input terminal of the rectifier unit; the cathode of the fifth diode D5 and the other end of the filter capacitor Co1 are connected and serve as the first output terminal of the rectifier unit; the anode of the sixth diode D6 and the other end of the filter capacitor Co2 are connected and serve as the second output terminal of the rectifier unit;

[0047] The first input terminal and the second input terminal of the rectifier unit are respectively connected to the two ends of the third winding; the first output terminal and the second output terminal of the rectifier unit are respectively connected to the two ends of the load;

[0048] The power supply is specifically a DC voltage source.

[0049] In the specific implementation process, the isolated soft-switching resonant conversion circuit without dead zone setting proposed in this embodiment is as follows: Figure 1 As shown, the circuit consists of switch tubes S1 and S2, inductors L1 and L2, capacitors C1 and C2, a three-winding transformer and a rectifier unit, which is used to convert the DC power supply voltage V in Converted into DC output voltage V o And supply power to the load Ro;

[0050] Specifically, the source of the first switching transistor S1 and the source of the second switching transistor S2 are respectively connected to one end of the power supply, the drain of the first switching transistor S1 is connected to one end of the first inductor L1, and the drain of the second switching transistor S2 is connected to one end of the second inductor L2; the gate of the first switching transistor S1 and the gate of the second switching transistor S2 serve as input ends of a control signal, used to control the on and off of the first switching transistor S1 and the second switching transistor S2; the other end of the first inductor L1 is connected to one end of the first winding of the three-winding transformer, and the other end of the second inductor L2 is connected to one end of the second winding of the three-winding transformer; the other end of the first winding and the other end of the second winding are respectively connected to the other end of the power supply; in this embodiment, the first switching transistor S1 and the second switching transistor S2 are both N-channel MOS transistors;

[0051] The two ends of the first capacitor C1 are respectively connected to the source and drain of the first switch tube S1, and the two ends of the second capacitor C2 are respectively connected to the source and drain of the second switch tube S2;

[0052] The first winding (np1) and the second winding (np2) of the three-winding transformer have the same number of turns, two ends of the third winding (ns) of the three-winding transformer are respectively connected to two input ends of the rectifier unit, and two output ends of the rectifier unit are respectively connected to two ends of the load;

[0053] In this embodiment, the rectifier unit can have two specific circuits, wherein the first is a full-bridge rectifier circuit, including a rectifier composed of four diodes and an output filter capacitor; the second is a half-bridge rectifier circuit, including a half-bridge composed of two diodes and two series output filter capacitors;

[0054] like Figure 2 As shown, when the rectifier unit is a full-bridge rectifier circuit, it includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a filter capacitor Co; the anode of the first diode D1 is connected to the cathode of the second diode D2 and serves as the first input terminal of the rectifier unit; the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and serves as the second input terminal of the rectifier unit; the cathode of the first diode D1 is respectively connected to the cathode of the third diode D3 and one end of the filter capacitor Co, and serves as the first output terminal of the rectifier unit; the anode of the second diode D2 is respectively connected to the anode of the fourth diode D4 and the other end of the filter capacitor Co, and serves as the second output terminal of the rectifier unit;

[0055] like Figure 3As shown, when the rectifier unit is a half-bridge rectifier circuit, it includes: a fifth diode D5, a sixth diode D6, a filter capacitor Co1 and a filter capacitor Co2; the anode of the fifth diode D5 and the cathode of the sixth diode D6 are connected and serve as the first input terminal of the rectifier unit, one end of the filter capacitor Co1 and one end of the filter capacitor Co2 are connected and serve as the second input terminal of the rectifier unit; the cathode of the fifth diode D5 and the other end of the filter capacitor Co1 are connected and serve as the first output terminal of the rectifier unit; the anode of the sixth diode D6 and the other end of the filter capacitor Co2 are connected and serve as the second output terminal of the rectifier unit;

[0056] The first input terminal and the second input terminal of the rectifier unit are respectively connected to the two ends of the third winding; the first output terminal and the second output terminal of the rectifier unit are respectively connected to the two ends of the load;

[0057] Compared with the existing soft-switching resonant converter based on half-bridge or full-bridge structure, the soft-switching resonant converter proposed in this embodiment does not need to set a dead zone for the switching tube, so it is more suitable for high-frequency application scenarios; at the same time, the first ends of the two switching tubes (generally the source of the N-type MOSFET) are simultaneously connected to the negative electrode of the input power supply, so the driving circuit of the switching tube is simpler than the full-bridge or half-bridge circuit design.

[0058] Example 2

[0059] like Figure 4 As shown, this embodiment provides another isolated soft-switching resonant conversion circuit with no dead zone, including: a first switch tube S1, a second switch tube S2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a resonant capacitor Cr, a three-winding transformer and a rectifier unit;

[0060] The source of the first switching transistor S1 and the source of the second switching transistor S2 are respectively connected to one end of the power supply, the drain of the first switching transistor S1 is connected to one end of the first inductor L1, and the drain of the second switching transistor S2 is connected to one end of the second inductor L2; the gate of the first switching transistor S1 and the gate of the second switching transistor S2 serve as input ends of a control signal, used to control the conduction and shutdown of the first switching transistor S1 and the second switching transistor S2; the other end of the first inductor L1 is connected to one end of the first winding of the three-winding transformer, and the other end of the second inductor L2 is connected to one end of the second winding of the three-winding transformer; the other end of the first winding and the other end of the second winding are respectively connected to the other end of the power supply;

[0061] The two ends of the first capacitor C1 are respectively connected to the source and drain of the first switch tube S1, and the two ends of the second capacitor C2 are respectively connected to the source and drain of the second switch tube S2;

[0062] The two ends of the third winding in the three-winding transformer are respectively connected to the two input ends of the rectifier unit, and the two output ends of the rectifier unit are respectively connected to the two ends of the load;

[0063] The two ends of the resonant capacitor Cr are respectively connected to the drain of the first switch tube S1 and the drain of the second switch tube S2;

[0064] The first switch tube S1 and the second switch tube S2 are both N-channel MOS tubes;

[0065] The first switch S1 and the second switch S2 are alternately turned on at a duty cycle of 0.5, and no dead time is set between the control signals of the first switch S1 and the second switch S2; the voltage across the load is adjusted by changing the switching frequency of the first switch S1 and the second switch S2;

[0066] The first winding and the second winding of the three-winding transformer have the same number of turns; the voltage across the load is adjusted by changing the turns ratio of the coils of the three-winding transformer;

[0067] When the rectifier unit is a full-bridge rectifier circuit, it includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a filter capacitor Co;

[0068] The anode of the first diode D1 is connected to the cathode of the second diode D2 and serves as the first input terminal of the rectifier unit; the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and serves as the second input terminal of the rectifier unit; the cathode of the first diode D1 is connected to the cathode of the third diode D3 and one end of the filter capacitor Co, respectively, and serves as the first output terminal of the rectifier unit; the anode of the second diode D2 is connected to the anode of the fourth diode D4 and the other end of the filter capacitor Co, respectively, and serves as the second output terminal of the rectifier unit;

[0069] The first input terminal and the second input terminal of the rectifier unit are respectively connected to the two ends of the third winding; the first output terminal and the second output terminal of the rectifier unit are respectively connected to the two ends of the load;

[0070] When the rectifier unit is a half-bridge rectifier circuit, it includes: a fifth diode D5, a sixth diode D6, a filter capacitor Co1 and a filter capacitor Co2;

[0071] The anode of the fifth diode D5 and the cathode of the sixth diode D6 are connected and serve as the first input terminal of the rectifier unit, one end of the filter capacitor Co1 and one end of the filter capacitor Co2 are connected and serve as the second input terminal of the rectifier unit; the cathode of the fifth diode D5 and the other end of the filter capacitor Co1 are connected and serve as the first output terminal of the rectifier unit; the anode of the sixth diode D6 and the other end of the filter capacitor Co2 are connected and serve as the second output terminal of the rectifier unit;

[0072] The first input terminal and the second input terminal of the rectifier unit are respectively connected to the two ends of the third winding; the first output terminal and the second output terminal of the rectifier unit are respectively connected to the two ends of the load;

[0073] The power supply is specifically a DC voltage source.

[0074] In a specific implementation, the circuit structure of this embodiment is substantially the same as that of Embodiment 1, with the only difference being that the circuit of this embodiment further includes a resonant capacitor Cr connected in parallel between the drain of the first switching transistor S1 and the drain of the second switching transistor S2.

[0075] like Figure 5 The specific structure shown in FIG. 1 is a diagram showing a full-bridge rectifier circuit as a rectifier unit in this embodiment to specifically illustrate the principle of the circuit provided by this embodiment.

[0076] like Figure 6 As shown, when the circuit in this embodiment is working, the switch tubes S1 and S2 are alternately turned on at a duty cycle of 0.5, and no dead time is required between the control signals of the switch tubes S1 and S2. The operation state of the entire circuit is as follows: Figure 6 The sequence shown switches automatically;

[0077] When the switch tube S1 is turned on and S2 is turned off, the resonant capacitor Cr and the parallel capacitor of S2 are connected in parallel and charged by the current iL2 of the inductor L2, so that their voltage increases from 0, so S2 is turned off at zero voltage; the current iL2 of the inductor L2 gradually decreases; the current is of the third winding of the transformer supplies power to the output capacitor Co and the load through the diodes D2 and D3 of the full-bridge rectifier, and the current iL1 of the inductor L1 drops rapidly to 0 and increases in the reverse direction; when the current iL1 increases in the reverse direction to be greater than the current iL2 of the inductor L2, the transformer The third winding current is of the transformer reverses and supplies power to the output capacitor Co and the load through the diodes D1 and D4 of the full-bridge rectifier. The current iL2 of the inductor L2 gradually decreases to 0 and increases in the reverse direction. The parallel capacitance of the resonant capacitor Cr and S2 begins to discharge, causing their voltage to gradually decrease. When the parallel capacitance voltage of the resonant capacitor Cr and S2 drops to 0, the parallel diode of the switch tube S2 turns on to continue the current, so that the voltage between Cr and S2 remains at 0 until the switch tube S2 turns on and S1 turns off. Therefore, S2 is turned on at zero voltage.

[0078] When the switch tube S2 is turned on and S1 is turned off, the resonant capacitor Cr is connected in parallel with the parallel capacitor of S1 and is charged by the current iL1 of the inductor L1, so that their voltage increases from 0, so S1 is turned off at zero voltage; the current iL1 of the inductor L1 gradually decreases; the current is of the third winding of the transformer supplies power to the output capacitor Co and the load through the diodes D1 and D4 of the full-bridge rectifier, and the current iL2 of the inductor L2 drops rapidly to 0 and increases in the reverse direction; when the current iL2 increases in the reverse direction to be greater than the current iL1 of the inductor L1, the transformer The third winding current is of the transformer reverses and supplies power to the output capacitor Co and the load through the diodes D2 and D3 of the full-bridge rectifier. The current iL1 of the inductor L1 gradually decreases to 0 and increases in the reverse direction. The parallel capacitance of the resonant capacitor Cr and S1 begins to discharge, causing their voltage to gradually decrease. When the parallel capacitance voltage of the resonant capacitor Cr and S1 drops to 0, the parallel diode of the switch tube S1 turns on to continue the current, so that the voltage between Cr and S1 remains at 0 until the switch tube S1 turns on and S2 turns off. Therefore, S1 is turned on at zero voltage.

[0079] When switches S1 and S2 operate alternately at high frequency, inductors L1 and L2, resonant capacitor Cr, and the parallel capacitance of switches S1 and S2 together form a resonant network. This provides zero-voltage switching conditions for switches S1 and S2, and provides energy to output capacitor Co and the load through the three-winding transformer and rectifier circuit, resulting in stable DC power across the load.

[0080] Like traditional resonant converters (LLC, LCC, series resonant, etc.), the output voltage can be adjusted by changing the switching frequency of switches S1 and S2 in the proposed conversion circuit, thereby maintaining the output voltage stable when the load or input voltage changes. The turns ratio of the three-winding transformer can also be designed to meet the needs of step-up or step-down application scenarios.

[0081] The soft-switching resonant converter proposed in this embodiment does not require a dead zone for the switching tube, and is therefore more suitable for high-frequency application scenarios. At the same time, the first ends of the two switching tubes (generally the source of the N-type MOSFET) are simultaneously connected to the negative electrode of the input power supply, so the driving circuit of the switching tube is simpler than the full-bridge or half-bridge circuit design.

[0082] The same or similar reference numerals correspond to the same or similar components;

[0083] The terms used in the drawings to describe positional relationships are for illustrative purposes only and are not to be construed as limiting the present application.

[0084] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An isolated soft-switching resonant converter circuit with no dead zone, characterized in that: include: A first switching tube S1, a second switching tube S2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a three-winding transformer and a rectifier unit; The source of the first switching transistor S1 and the source of the second switching transistor S2 are respectively connected to one end of the power supply, the drain of the first switching transistor S1 is connected to one end of the first inductor L1, and the drain of the second switching transistor S2 is connected to one end of the second inductor L2; the gate of the first switching transistor S1 and the gate of the second switching transistor S2 serve as input ends of a control signal, used to control the conduction and shutdown of the first switching transistor S1 and the second switching transistor S2; the other end of the first inductor L1 is connected to one end of the first winding of the three-winding transformer, and the other end of the second inductor L2 is connected to one end of the second winding of the three-winding transformer; the other end of the first winding and the other end of the second winding are respectively connected to the other end of the power supply; The two ends of the first capacitor C1 are respectively connected to the source and drain of the first switch tube S1, and the two ends of the second capacitor C2 are respectively connected to the source and drain of the second switch tube S2; The two ends of the third winding in the three-winding transformer are respectively connected to the two input ends of the rectifier unit, and the two output ends of the rectifier unit are respectively connected to the two ends of the load.

2. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The first switch transistor S1 and the second switch transistor S2 are both N-channel MOS transistors.

3. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The first switch S1 and the second switch S2 are both turned on alternately with a duty cycle of 0.5, and no dead time is set between the control signals of the first switch S1 and the second switch S2.

4. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The voltage across the load is adjusted by changing the switching frequency of the first switch tube S1 and the second switch tube S2.

5. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The first winding and the second winding of the three-winding transformer have the same number of turns.

6. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The voltage across the load is adjusted by changing the turns ratio of the three-winding transformer.

7. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The rectifier unit is a full-bridge rectifier circuit, including: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a filter capacitor Co; The anode of the first diode D1 is connected to the cathode of the second diode D2 and serves as the first input terminal of the rectifier unit; the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and serves as the second input terminal of the rectifier unit; the cathode of the first diode D1 is connected to the cathode of the third diode D3 and one end of the filter capacitor Co, respectively, and serves as the first output terminal of the rectifier unit; the anode of the second diode D2 is connected to the anode of the fourth diode D4 and the other end of the filter capacitor Co, respectively, and serves as the second output terminal of the rectifier unit; The first input end and the second input end of the rectifier unit are respectively connected to the two ends of the third winding; the first output end and the second output end of the rectifier unit are respectively connected to the two ends of the load.

8. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The rectifier unit is a half-bridge rectifier circuit, including: a fifth diode D5, a sixth diode D6, a filter capacitor Co1 and a filter capacitor Co2; The anode of the fifth diode D5 and the cathode of the sixth diode D6 are connected and serve as the first input terminal of the rectifier unit, one end of the filter capacitor Co1 and one end of the filter capacitor Co2 are connected and serve as the second input terminal of the rectifier unit; the cathode of the fifth diode D5 and the other end of the filter capacitor Co1 are connected and serve as the first output terminal of the rectifier unit; the anode of the sixth diode D6 and the other end of the filter capacitor Co2 are connected and serve as the second output terminal of the rectifier unit; The first input end and the second input end of the rectifier unit are respectively connected to the two ends of the third winding; the first output end and the second output end of the rectifier unit are respectively connected to the two ends of the load.

9. The isolated soft-switching resonant converter circuit without dead zone setting according to claim 1, characterized in that: The circuit further includes a resonant capacitor Cr; Two ends of the resonant capacitor Cr are connected to the drain of the first switch tube S1 and the drain of the second switch tube S2 respectively.

10. The isolated soft-switching resonant converter circuit without dead zone setting according to any one of claims 1 to 9, characterized in that: The power supply is specifically a DC voltage source.

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