A resonant transformer and switching power supply circuit

Abstract

The present application provides a resonant transformer and a switching power supply circuit, which relates to the field of high-frequency transformer technology. The resonant transformer includes a support frame, a coil sheath, a first winding, a second winding, a first main magnetic core, a second main magnetic core, and a shunt magnetic core. An insulating cylinder is provided inside the support frame. The first winding is installed in the first winding area, the second winding is installed in the second winding area, the shunt magnetic core is installed in the magnetic shunt magnetic core accommodating area, the coil sheath is installed on the support frame and arranged outside the first winding, and the first main magnetic core and the second main magnetic core both include a center column; the first main magnetic core and the second main magnetic core are respectively arranged on both sides of the support frame, and the center columns of the first main magnetic core and the second main magnetic core are passed through the insulating cylinder and the shunt magnetic core and are connected. The center columns of the first main magnetic core and the second main magnetic core are both spaced apart from the shunt magnetic core to increase the leakage inductance of the resonant transformer. The present application has the advantages of simple structure, conducive to miniaturization, and at the same time increases the leakage inductance of the resonant transformer.

Description

Technical Field

[0001] The present application relates to the technical field of high-frequency transformers, and in particular to a resonant transformer and a switching power supply circuit. Background Art

[0002] In high-frequency switching power supply circuits, especially in resonant topology circuits, the LLC resonant network includes the transformer's magnetizing inductance Lm, leakage inductance Lk, and resonant capacitor Cr.

[0003] Currently, there are two common design approaches. One involves using a traditional transformer with a separate resonant inductor, but this consumes significant PCB space and increases power supply costs. The other involves winding the primary and secondary coils separately on a double-slot bobbin, adjusting the leakage inductance by adjusting the number of turns and the distance between the primary and secondary. However, this results in a larger transformer, increased magnetic leakage, and lower efficiency. Furthermore, under certain conditions, the range of leakage inductance that can be increased is very limited.

[0004] In summary, the existing technology has the problem that the resonant transformer is large in size and the range of increasing leakage inductance is limited. Summary of the Invention

[0005] The purpose of the present application is to provide a resonant transformer and a switching power supply circuit to solve the problems in the prior art of the resonant transformer being large in size and having a limited range for increasing leakage inductance.

[0006] In order to achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows:

[0007] On the one hand, an embodiment of the present application provides a resonant transformer, which includes a support frame, a coil sheath, a first winding, a second winding, a first main magnetic core, a second main magnetic core and a shunt magnetic core, the outer wall of the support frame is sequentially provided with a first winding area, a magnetic shunt magnetic core accommodating area, a fitting area and a second winding area, an insulating cylinder is provided inside the support frame, the first winding is installed in the first winding area, the second winding is installed in the second winding area, the shunt magnetic core is installed in the magnetic shunt magnetic core accommodating area, the coil sheath is installed on the support frame and is arranged outside the first winding, and the first main magnetic core and the second main magnetic core both include a center column; wherein,

[0008] The first main magnetic core and the second main magnetic core are respectively arranged on both sides of the supporting frame, and the middle columns of the first main magnetic core and the second main magnetic core are passed through the insulating tube and the shunt magnetic core and are connected. The middle columns of the first main magnetic core and the second main magnetic core are spaced apart from the shunt magnetic core to increase the leakage inductance of the resonant transformer.

[0009] Optionally, the shunt magnetic core is shaped like a U-shape, a through-hole is provided in the middle of the shunt magnetic core, and the shape of the middle column is the same as that of the through-hole, so that the middle column passes through the through-hole.

[0010] Optionally, the shape of the shunt magnetic core is set to be U-shaped or C-shaped, a through slot is set in the middle position of the shunt magnetic core, and the middle column passes through the through slot.

[0011] Optionally, the shunt core includes a first magnetic core bar and a second magnetic core bar, the first magnetic core bar and the second magnetic core bar are installed in parallel in the magnetic shunt core accommodating area, and the center column passes between the first magnetic core bar and the second magnetic core bar.

[0012] Optionally, a positioning hole is provided in the magnetic shunt core accommodating area, and the shunt core is installed in the positioning hole.

[0013] Optionally, the center column is spaced 0.1 to 0.3 mm from the inner wall of the insulating tube and the shunt magnetic core.

[0014] Optionally, the first main magnetic core and the second main magnetic core are both configured to be E-shaped, and the first main magnetic core and the second main magnetic core further include a first side column and a second side column, and the first side column and the second side column are both spaced apart from the outer side of the shunt magnetic core.

[0015] Optionally, the support frame includes a base and a lead terminal, a connection area is provided at both ends of the base, the connection area is provided with a plurality of protrusions, a lead groove is provided on the outer side of each protrusion, and the lead terminal is provided on the protrusion; wherein,

[0016] The leads of the first winding and the second winding are connected to the lead terminals after passing through the lead grooves and the protrusions.

[0017] Optionally, the coil sheath is configured to be U-shaped, and fixing portions are provided on both sides of the coil sheath, and the coil sheath is connected to the supporting frame via the fixing portions.

[0018] On the other hand, an embodiment of the present application further provides a switching power supply circuit, which includes the above-mentioned resonant transformer.

[0019] Compared with the prior art, this application has the following beneficial effects:

[0020] The present application provides a resonant transformer and a switching power supply circuit, the resonant transformer including a supporting frame, a coil sheath, a first winding, a second winding, a first main magnetic core, a second main magnetic core and a shunt magnetic core, the outer wall of the supporting frame is sequentially provided with a first winding area, a magnetic shunt magnetic core accommodating area, a fitting area and a second winding area, an insulating cylinder is provided inside the supporting frame, the first winding is installed in the first winding area, the second winding is installed in the second winding area, the shunt magnetic core is installed in the magnetic shunt magnetic core accommodating area, the coil sheath is installed on the supporting frame and is arranged outside the first winding, the first main magnetic core and the second main magnetic core both include a middle column; wherein the first main magnetic core and the second main magnetic core are respectively arranged on both sides of the supporting frame, the middle columns of the first main magnetic core and the second main magnetic core are passed through the insulating cylinder and the shunt magnetic core and are connected, and the middle columns of the first main magnetic core and the second main magnetic core are both spaced apart from the shunt magnetic core to increase the leakage inductance of the resonant transformer. The resonant transformer provided in the present application has a simple structure, and various components are connected by a supporting frame, which is conducive to miniaturization and at the same time increases the leakage inductance of the resonant transformer.

[0021] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the resonant transformer provided in an embodiment of the present application.

[0024] Figure 2 This is a schematic diagram of the first structural decomposition of the resonant transformer provided in an embodiment of the present application.

[0025] Figure 3 This is a schematic diagram of the second structural decomposition of the resonant transformer provided in an embodiment of the present application.

[0026] Figure 4 It is a structural schematic diagram of the support skeleton provided in an embodiment of the present application.

[0027] Figure 5 This is a schematic diagram of the third structural decomposition of the resonant transformer provided in an embodiment of the present application.

[0028] Figure 6 This is a fourth structural decomposition diagram of the resonant transformer provided in an embodiment of the present application.

[0029] Figure 7 It is a schematic diagram of the bottom structure of the support frame provided in an embodiment of the present application.

[0030] Figure 8 It is a schematic structural diagram of the coil sheath provided in an embodiment of the present application.

[0031] In the figure: 100-resonant transformer; 110-support frame; 120-coil sheath; 130-first main magnetic core; 140-second main magnetic core; 150-shunt magnetic core; 151-first magnetic core bar; 152-second magnetic core bar; 111-first winding area; 112-magnetic shunt core accommodating area; 113-embedded area; 114-second winding area; 115-base; 116-lead terminal. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0034] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0035] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0036] In the description of this application, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0037] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed" and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, or electrical connections; direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0038] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0039] As described in the background art, the current design of the resonant transformer has the problems of large size and limited range for increasing leakage inductance.

[0040] In view of this, in order to solve the above problems, the present application provides a resonant transformer, which achieves the effect of reducing the volume and increasing the leakage inductance by adjusting the supporting skeleton structure and adding a shunt core.

[0041] The following is an exemplary description of the resonant transformer provided in this application:

[0042] As an optional implementation, see Figure 1-Figure 4The resonant transformer 100 includes a support frame 110, a coil sheath 120, a first winding, a second winding, a first main magnetic core 130, a second main magnetic core 140, and a shunt magnetic core 150. The outer wall of the support frame 110 is sequentially provided with a first winding area 111, a magnetic shunt core accommodating area 112, a fitting area 113, and a second winding area 114. An insulating cylinder is provided inside the support frame 110. The first winding is installed in the first winding area 111, the second winding is installed in the second winding area 114, the shunt magnetic core 150 is installed in the magnetic shunt core accommodating area 112, the coil sheath 120 is installed on the support frame 110 and is arranged outside the first winding. The first main magnetic core 130 and the second main magnetic core 140 both include a center column. The first main magnetic core 130 and the second main magnetic core 140 are respectively arranged on both sides of the support frame 110. The middle columns of the first main magnetic core 130 and the second main magnetic core 140 are passed through the insulating tube and the shunt magnetic core 150 and are connected. The middle columns of the first main magnetic core 130 and the second main magnetic core 140 are spaced apart from the shunt magnetic core 150 to increase the leakage inductance of the resonant transformer.

[0043] By adjusting the support frame 110 and adding the shunt core 150 , the magnetic flux generated by the first winding of the transformer is shunted, reducing the magnetic flux entering the second winding, thereby increasing the leakage inductance of the first winding of the transformer.

[0044] Furthermore, when making a resonant power supply, there is no need to set up an additional independent inductor, which can reduce the material cost and production cost of the power supply. The magnetic shunt core accommodating area 112 in the support frame 110 provided in this application can solve the problem of insufficient safety distance after the transformer is miniaturized through the clever structural design, and also greatly simplify the transformer production process. The leakage magnetic component can be adjusted by adjusting the size of the magnetic shunt core 150 (i.e., adjusting the size of the air gap between the magnetic shunt core 150 and the main magnetic circuit core), thereby adjusting the leakage inductance.

[0045] In addition, the structure provided in the present application can also be used as a differential common-mode integrated inductor when the number of turns and wire diameter of the first winding and the second winding are the same.

[0046] It should be noted that the support frame 110 provided in the present application is made of insulating material, such as thermosetting phenolic resin, and is injection-molded by a mold.

[0047] Optionally, the partitions on both sides of the magnetic shunt core accommodating area 112 provided in the present application are connected by a plurality of 0.5 to 1 mm thick insulating plates to form a accommodating portion for the magnetic shunt core 150, and the supporting skeleton 110 such as the winding area of ​​the first winding and the second winding is connected as a whole, and an opening is left at a specific position for the shunt core 150 to be inserted. At the same time, by providing the insulating plates, it can play a certain isolation role on the first winding, the second winding and the shunt core 150 after the shunt core 150 is inserted into the opening. Of course, in actual applications, the number of insulating plates may be more. For example, a plurality of insulating plates are provided on the outer wall of the insulating cylinder, and the first winding area 111, the magnetic shunt core accommodating area 112, the interlocking area 113 and the second winding area 114 are divided by a plurality of insulating partitions.

[0048] Among them, this application does not limit the shape and material of the magnetic core. For example, for the material of the first main magnetic core 130, the second main magnetic core 140 and the shunt magnetic core 150, soft magnetic ferrite material can be selected. Optionally, the resonant transformer can choose power ferrite material, and when it is necessary to make a differential common mode integrated inductor, high permeability ferrite material can be selected.

[0049] Regarding the shape of the shunt core 150, as a first optional implementation method, the shape of the shunt core 150 is set to be a U-shape, and a through hole is set in the middle position of the shunt core 150. The shape of the middle column is the same as the shape of the through hole, so that the middle column passes through the through hole.

[0050] It should be noted that the "U" shape described in this application refers to a pattern with a perforation in the middle, including a standard U-shape and its corresponding modified structures. For example, the standard U-shape is a shunt core 150 with a quadrilateral outer frame and a quadrilateral perforation, such as both being square. Its modified structure includes variations in the outer frame and perforation shape, for example, the outer frame is a quadrilateral and the perforation is circular or polygonal, or the outer frame is a circular or polygonal and the perforation is a quadrilateral.

[0051] In addition, generally speaking, the shape of the center column is the same as the shape of the through hole, so that the distance between the center column and the shunt core 150 is guaranteed to be consistent at different positions. For example, when the shape of the through hole is set to be circular, the shape of the center column is also set to be circular; when the shape of the through hole is set to be a quadrilateral, the shape of the center column is also set to be a quadrilateral.

[0052] As a second implementation, see Figure 5 The shunt core 150 is shaped like a U or C, with a slot provided in the middle of the shunt core 150, through which the center column passes. In other words, if one of the sides of the shunt core 150 is missing, the shunt core 150 may be shaped like a U or C, or the shunt core 150 may be shaped like an arcuate U or C.

[0053] As a third implementation, see Figure 6 The shunt core 150 includes a first core bar 151 and a second core bar 152. The first core bar 151 and the second core bar 152 are installed parallel to each other in the magnetic shunt core accommodating area 112. The center column passes between the first core bar 151 and the second core bar 152. On this basis, the center column can optionally be in the shape of a quadrilateral.

[0054] Furthermore, it should be noted that, optionally, the insulating tube has a wall thickness of 0.5-1 mm, and the inner hole of the tube matches the shape and size of the main magnetic core's center column, with a gap of 0.1-0.3 mm left on each side. In other words, in this application, the shapes of the insulating tube, the via hole of the shunt magnetic core 150, and the center column all correspond; for example, the cross-sections of all three are circular.

[0055] As an implementation, the first main magnetic core 130 and the second main magnetic core 140 are both configured in an E-shape. The first main magnetic core 130 and the second main magnetic core 140 further include first and second side pillars, each of which is spaced apart from the outer side of the shunt magnetic core 150. The support frame 110 is provided with first and second side pillar receiving grooves. After the first main magnetic core 130 and the second main magnetic core 140 are inserted into the insulating cylinder, the first side pillar is placed in the first side pillar receiving groove, and the second side pillar is placed in the second side pillar receiving groove.

[0056] Therefore, when installing the resonant transformer provided in the present application, the shunt core 150 is first installed in the magnetic shunt core accommodating area 112, wherein the magnetic shunt core accommodating area 112 can be set to a square shape, so that the shunt core 150 can be directly placed in the magnetic shunt core accommodating area 112. Then the first main core 130 and the second main core 140 are respectively inserted into the insulating tube along the left and right ends of the support frame 110, and the middle columns of the first main core 130 and the second main core 140 are in contact inside the insulating tube to achieve connection. In addition, since the shunt core 150 is arranged between the first winding and the second winding, when the middle column passes through the insulating tube, it will also pass through the shunt core 150.

[0057] In one implementation, one of the first main magnetic core 130 and the second main magnetic core 140 passes through the shunt magnetic core 150, while the center leg of the other core does not reach the shunt magnetic core 150, so that the center legs of the two are connected within the insulating tube. In another implementation, the center legs of the first main magnetic core 130 and the second main magnetic core 140 are connected within the shunt magnetic core 150.

[0058] It should also be noted that the interior of the magnetic shunt core accommodating area 112 is provided with devices such as magnetic shunt core 150 positioning holes. First, a single U-shaped magnetic shunt core 150 is inserted into the magnetic shunt core 150 accommodating portion, and the middle column of the main magnetic core passes through the middle square hole of the U-shaped core and engages with it, leaving an air gap between the two; the two outer sides of the U-shaped core are adjacent to the first side column and the second side column of the main magnetic core, and an air gap is also left; the size of the air gap between the magnetic shunt core 150 and the main magnetic core can be adjusted by controlling the size of the square hole inside the U-shaped core, thereby adjusting the leakage inductance; the leakage magnetic flux can also be adjusted by adjusting the thickness of the U-shaped core.

[0059] When the shape of the shunt magnetic core 150 is set to U-shape or C-shape, its inner concave part is embedded in the middle column of the main magnetic core, and an air gap is left; the outer sides of its two legs are adjacent to the two side columns of the main magnetic core, and an air gap is also left; the size of the air gap between the shunt magnetic core 150 and the main magnetic core can be adjusted by controlling the length, width and other dimensions of the two legs of the U-shaped or C-shaped shunt magnetic core 150, thereby adjusting the leakage inductance.

[0060] When the shunt core 150 includes a first core bar 151 and a second core bar 152, two core bars can also be installed in the fixed position of the magnetic shunt core accommodating area 112. The two core bars are inserted into the positioning holes of the magnetic shunt core accommodating area 112 between the middle column and the side legs of the main magnetic core. An air gap is provided between the core bars and the main magnetic circuit core. The size of the air gap between the shunt core 150 and the main magnetic core can be adjusted by controlling the size of the core bars, thereby adjusting the leakage inductance.

[0061] And, as an optional implementation, see Figure 7 The support frame 110 includes a base 115 and a lead terminal 116. Connection areas are provided at both ends of the base 115. The connection areas are provided with multiple protrusions. A lead groove is provided on the outside of each protrusion, and the lead terminal 116 is provided on the protrusion; wherein, the leads of the first winding and the second winding are connected to the lead terminal 116 after passing through the lead groove and the protrusion.

[0062] Furthermore, a groove is provided in the middle of the bottom curved portion of the magnetic shunt core accommodation area 112 for routing wires across the first and second windings or for reducing adhesive, etc. Two rectangular bases are provided outside the partitions outside the two winding areas, each equipped with a plurality of lead terminals 116, which are located at the lower ends of the bases.

[0063] By passing the winding lead through the lead groove and winding it around the protrusion before connecting it to the terminal, the creepage distance can be increased and the probability of coil short circuit can be reduced.

[0064] In addition, as an implementation, see Figure 8The coil sheath 120 is U-shaped, with fixing portions provided on both sides thereof. The coil sheath 120 is connected to the interlocking area 113 of the support frame 110 via the fixing portions. The sheath is inserted into the corresponding position of the wound support frame 110, and the interlocking of the fixing portions and the support frame 110 ensures a safe distance between the coil of this winding and the magnetic core and the coil of the other winding.

[0065] The opening direction of the U-shaped coil sheath 120 is opposite to the opening direction of the magnetic shunt core accommodating area 112 , so as to increase the creepage distance and electrical clearance.

[0066] Based on the above implementation, an embodiment of the present application further provides a switching power supply circuit, which includes the above-mentioned resonant transformer.

[0067] In summary, the present application provides a resonant transformer and a switching power supply circuit, the resonant transformer includes a supporting frame, a coil sheath, a first winding, a second winding, a first main magnetic core, a second main magnetic core and a shunt magnetic core, the outer wall of the supporting frame is sequentially provided with a first winding area, a magnetic shunt magnetic core accommodating area, a fitting area and a second winding area, an insulating cylinder is provided inside the supporting frame, the first winding is installed in the first winding area, the second winding is installed in the second winding area, the shunt magnetic core is installed in the magnetic shunt magnetic core accommodating area, the coil sheath is installed on the supporting frame and is arranged outside the first winding, the first main magnetic core and the second main magnetic core both include a middle column; wherein, the first main magnetic core and the second main magnetic core are respectively arranged on both sides of the supporting frame, the middle columns of the first main magnetic core and the second main magnetic core are passed through the insulating cylinder and the shunt magnetic core and are connected, and the middle columns of the first main magnetic core and the second main magnetic core are spaced apart from the shunt magnetic core to increase the leakage inductance of the resonant transformer. The resonant transformer provided herein has a simple structure, and various components are connected by a supporting frame, which is conducive to miniaturization and at the same time increases the leakage inductance of the resonant transformer.

[0068] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0069] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present application is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A resonant transformer, characterized in that: The resonant transformer includes a support frame, a coil sheath, a first winding, a second winding, a first main magnetic core, a second main magnetic core and a shunt magnetic core. The outer wall of the support frame is sequentially provided with a first winding area, a magnetic shunt magnetic core accommodating area, a fitting area and a second winding area. An insulating cylinder is provided inside the support frame. The first winding is installed in the first winding area, the second winding is installed in the second winding area, the shunt magnetic core is installed in the magnetic shunt magnetic core accommodating area, the coil sheath is installed on the support frame and is arranged outside the first winding. The first main magnetic core and the second main magnetic core both include a center column; wherein, The first main magnetic core and the second main magnetic core are respectively arranged on both sides of the support frame, and the middle columns of the first main magnetic core and the second main magnetic core are passed through the insulating tube and the shunt magnetic core and are connected. The middle columns of the first main magnetic core and the second main magnetic core are spaced apart from the shunt magnetic core to increase the leakage inductance of the resonant transformer; The shunt magnetic core includes a first magnetic core bar and a second magnetic core bar, the first magnetic core bar and the second magnetic core bar are installed in parallel in the magnetic shunt core accommodating area, and the center column passes between the first magnetic core bar and the second magnetic core bar, wherein an air gap is provided between the first magnetic core bar and / or the second magnetic core bar and the corresponding main magnetic circuit magnetic core, so that the leakage inductance can be changed by adjusting the size of the air gap; A positioning hole is provided in the magnetic shunt core accommodating area, and the shunt core is installed in the positioning hole, wherein the first magnetic core bar and the second magnetic core bar are inserted into the positioning hole in the magnetic shunt core accommodating area between the middle column and the side leg of the main magnetic core, and the size of the air gap between the shunt core and the main magnetic core is adjusted by controlling the size of the first magnetic core bar and / or the first magnetic core bar to adjust the leakage inductance.

2. The resonant transformer according to claim 1, wherein: The shunt magnetic core is shaped like a U-shape, a through hole is provided in the middle of the shunt magnetic core, and the shape of the center column is the same as that of the through hole, so that the center column passes through the through hole.

3. The resonant transformer according to claim 1, wherein: The shape of the shunt magnetic core is set to be U-shaped or C-shaped, and a through slot is set in the middle position of the shunt magnetic core, and the middle column passes through the through slot.

4. The resonant transformer according to claim 1, wherein The distance between the center column and the inner wall of the insulating tube and the shunt magnetic core is 0.1-0.3 mm.

5. The resonant transformer according to claim 1, wherein: The first main magnetic core and the second main magnetic core are both configured to be E-shaped. The first main magnetic core and the second main magnetic core further include a first side column and a second side column. The first side column and the second side column are both spaced apart from the outer side of the shunt magnetic core.

6. The resonant transformer according to claim 1, wherein: The support frame includes a base and a lead terminal. The two ends of the base are provided with a connection area. The connection area is provided with a plurality of protrusions. The outer side of each protrusion is provided with a lead groove. The lead terminal is provided on the protrusion; wherein, The leads of the first winding and the second winding are connected to the lead terminals after passing through the lead grooves and the protrusions.

7. The resonant transformer according to claim 1, wherein: The coil sheath is configured to be U-shaped, and fixing portions are provided on both sides of the coil sheath, through which the coil sheath is connected to the support frame.

8. A switching power supply circuit, characterized in that: The switching power supply circuit includes the resonant transformer according to any one of claims 1 to 7.

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