A matrix transformer based on leakage inductance control

Abstract

The invention discloses a matrix transformer based on leakage inductance control, comprising a magnetic core and a winding, wherein the magnetic core (5) further comprises a magnetic column composed of four middle columns (1) and four side columns (2), and a magnetic core cover arranged above and below the middle column and above and below the side columns, each middle column (1) is wound with a middle column primary winding (3) and a middle column secondary winding (4); in each middle column (1), the magnetic flux corresponding to the middle column secondary winding (4) is less than the magnetic flux corresponding to the middle column primary winding (3); there are air gaps (6) between the middle columns (1); the cross-sectional area of ​​the magnetic column is changed by controlling the winding of the middle column secondary winding, and the size of the leakage inductance is changed by controlling the distance between the middle column secondary winding and the middle column primary winding. Compared with the prior art, the invention solves the problem that the leakage inductance of the matrix transformer is uncontrollable.

Description

Technical Field

[0001] The invention relates to the field of DC-DC conversion and resonant converter, and in particular to a leakage inductance control method of a matrix transformer. Background Art

[0002] As switching power supplies develop towards miniaturization and lightness, the improvement of transformers, as one of the core components, is crucial to improving the overall efficiency of the converter, including the use of matrix transformers and PCB windings, which are the best solutions for transformer improvement. Compared with ordinary transformers, matrix transformers have smaller volume and magnetic density, which can effectively improve the power density of the converter and reduce core losses, so they are widely used in DC-DC conversion situations. However, for the resonant converter LLC, the leakage inductance provided by the matrix transformer is very small and uncontrollable, resulting in a very small inductance ratio, which cannot meet the resonant converter's demand for voltage regulation. Therefore, it is usually necessary to connect an additional inductor in series with the resonant cavity, which not only increases the number and volume of the core components, but also limits the resonant converter from exerting good magnetic integration characteristics.

[0003] Since copper foil printed on the PCB is used as the transformer winding, the spacing between the windings is very small, the coupling degree between the primary and secondary windings is very high, and the leakage inductance of the matrix transformer is usually very small. Therefore, in order to obtain a sufficient magnitude of leakage inductance, the coupling degree between the primary and secondary windings must first be reduced. Common methods include increasing the distance between the primary and secondary windings, and unequally dividing the windings with magnetic columns. Summary of the invention

[0004] In view of the problem that the leakage inductance of the matrix transformer is uncontrollable, the present invention proposes a matrix transformer, which controls the magnetic resistance by improving the cross-sectional area of ​​the magnetic column and utilizes the difference in the cross-sectional area of ​​the magnetic column of the primary and secondary windings to manufacture controllable leakage inductance, so as to meet the requirements of the inductance ratio when the LLC converter is regulating the voltage.

[0005] The present invention is achieved by the following technical solutions:

[0006] A matrix transformer based on leakage inductance control includes a magnetic core and windings, wherein the magnetic core 5 further includes four middle columns 1, four side columns 2, and a magnetic core cover disposed above and below the middle column and the side column, and each of the middle columns 1 is wound with a middle column primary winding 3 and a middle column secondary winding 4; wherein:

[0007] In each of the middle columns 1, the middle column primary windings 3 are arranged on both sides, the corresponding magnetic column cross-sectional areas remain unchanged, and the magnetic flux generated by the middle column primary windings 3 is fixed; the middle column secondary windings 4 have four layers in total and are placed in the middle of the middle column primary windings 3, the magnetic column cross-sectional area corresponding to the middle column secondary windings 4 lacks a portion of the width w1×height h1 of the magnetic column cross-sectional area corresponding to the middle column primary windings 3, and the magnetic flux generated by the middle column secondary windings 4 is less than the magnetic flux generated by the middle column primary windings 4;

[0008] There are air gaps 6 between the middle columns 1;

[0009] The cross-sectional area of ​​the magnetic column is changed by controlling the winding of the secondary winding of the center column, and the size of the leakage inductance is changed by controlling the distance between the secondary winding of the center column and the primary winding of the center column.

[0010] Compared with the prior art, the present invention can achieve the following beneficial technical effects:

[0011] The present invention improves the structure of the magnetic core on the basis of a four-column matrix transformer, solves the problem of uncontrollable leakage inductance of the matrix transformer; and solves the problem of increased volume and efficiency loss caused by the need for external discrete magnetic parts when an LLC resonant converter adopts a matrix transformer due to insufficient leakage inductance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the three-dimensional structure of a matrix transformer based on leakage inductance control of the present invention;

[0013] Figure 2 It is a schematic diagram of a top view of a matrix transformer structure based on leakage inductance control of the present invention;

[0014] Figure 3 It is a cross-sectional view along the A-A' direction of a matrix transformer structure based on leakage inductance control of the present invention;

[0015] Figure 4 is the equivalent magnetoresistance diagram;

[0016] Reference numerals:

[0017] 1. Middle column, 2. Side column, 3. Middle column primary winding, 4. Middle column secondary winding, 5. Magnetic core structure, 6. Air gap. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] like Figures 1 to 3As shown, a matrix transformer structure of the present invention is shown. A matrix transformer of the present invention includes a magnetic core and a winding. Wherein, the magnetic core structure includes a magnetic column; the winding includes a primary winding and a secondary winding. Wherein, the magnetic column has four middle columns 1 and four side columns 2, and includes a magnetic core cover arranged above the middle column and the side column and a magnetic core cover below. Primary windings and secondary windings are arranged around each middle column 1 and each side column 2 to form a transformer. In each of the middle columns 1, the middle column primary windings 3 are arranged on both sides, and the corresponding magnetic column cross-sectional areas remain unchanged, so the magnetic flux φ generated by the middle column primary winding 3 is also fixed. The secondary winding 4 of the middle column has four layers and is placed in the middle of the primary winding 3 of the middle column. Compared with the primary winding 3 of the middle column, the cross-sectional area of ​​the secondary winding 4 of the middle column lacks the concave area (the cross-sectional area is designed to be two obviously different parts). The magnetic flux generated by the secondary winding 4 of the middle column is also less than the magnetic flux generated by the primary winding 3 of the middle column. Therefore, by adjusting the value of this part of the area, Figure 1 The product of the width w1 and the height h1 is used to reduce the coupling degree between the primary and secondary windings. The difference in the magnetic flux generated by the primary and secondary windings is the leakage magnetic flux of the transformer, thereby realizing the design of expanding the leakage magnetic flux φσ. There is an air gap 6 in the middle column 1.

[0020] like Figure 4 The equivalent magnetic circuit diagram of the magnetic core structure is shown in the figure. Among them, NPIP and NsIs are the magnetic potentials generated by the primary winding and the secondary winding respectively, and F1, F2, R1, R2, R3, R4, R5, and Rg correspond to Figure 1 The magnetic column lengths l1, l2, l3, l4, l5 and the air gap length l g Position equivalent magnetic resistance, R a1 , R a2 is the air magnetic resistance of the leakage magnetic circuit. By analyzing and simplifying the magnetic circuit diagram, the expressions of the magnetic fluxes φ1, φ2, and φ3 of each branch can be derived, and φ2 is the value of the leakage magnetic flux. Therefore, the present invention can change the size of the leakage inductance by changing the distribution of the magnetic flux.

[0021] Taking LLC resonant converter as an example, the working process of a matrix transformer in leakage inductance control of the present invention is as follows:

[0022] Step 1: construct a matrix transformer based on a magnetic core structure and a corresponding winding arrangement to reduce the coupling between the primary winding and the secondary winding and create a leakage inductance of sufficient magnitude;

[0023] Step 2: By controlling the winding of the secondary winding to change the cross-sectional area of ​​the magnetic column, and by controlling the distance between the secondary winding and the primary winding to change the size of the leakage inductance, the problem of uncontrollable leakage inductance of the matrix transformer is solved;

[0024] Step 3: Decoupling control of leakage inductance and excitation inductance to achieve magnetic integration of series resonant inductance, parallel resonant inductance and transformer of LLC resonant converter.

[0025] The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be regarded as within the scope of patent protection of the present invention.

Claims

1. A matrix transformer based on leakage inductance control, comprising a magnetic core and a winding, characterized in that: The magnetic core (5) further comprises four middle columns (1), four side columns (2), and a magnetic core cover arranged above the middle columns and the side columns and a magnetic core cover arranged below the middle columns, each of the middle columns (1) being wound with a middle column primary winding (3) and a middle column secondary winding (4); wherein: In each of the middle columns (1), the middle column primary windings (3) are arranged on both sides, the corresponding magnetic column cross-sectional areas remain unchanged, and the magnetic flux generated by the middle column primary windings (3) is fixed; the middle column secondary windings (4) have four layers in total and are arranged in the middle of the middle column primary windings (3); the magnetic column cross-sectional area corresponding to the middle column secondary windings (4) lacks a portion of the width w1×height h1 of the magnetic column cross-sectional area corresponding to the middle column primary windings (3); and the magnetic flux generated by the middle column secondary windings (4) is less than the magnetic flux generated by the middle column primary windings (3); There are air gaps (6) between the middle columns (1); The cross-sectional area of ​​the magnetic column is changed by controlling the winding of the middle column secondary winding (4), and the size of the leakage inductance is changed by controlling the distance between the middle column secondary winding (4) and the middle column primary winding (3).

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