Flat magnetic integrated transformer suitable for zero-ripple CUK converter

Abstract

The invention provides a flat magnetic integrated transformer suitable for a zero-ripple CUK converter. The transformer comprises a magnetic core of the transformer and a printed board winding. The printed board windings are four in number and comprise two transformer windings and two inductance windings, the two inductance windings are completely the same and are arranged on the magnetic core columns on the two sides, and the transformer windings are arranged on the middle column. According to the invention, one transformer and two coupling inductors are integrated at the same time, the utilization rate of magnetic parts can be improved, the volume and weight of the magnetic parts are greatly reduced, and the power density of the converter is improved.

Description

Technical Field

[0001] The present application relates to the technical field of CUK converters, and in particular to a flat magnetic integrated transformer suitable for a zero-ripple CUK converter. Background Art

[0002] With the continuous development of low ripple technology, the requirements for output ripple are becoming more and more stringent. The use of coupled inductor technology can truly achieve zero ripple in theory. Compared with other topologies, the Cuk converter is the optimal topology to achieve zero ripple circuits.

[0003] Commonly used zero-ripple CUK converter topology, see Figure 1 In order to reduce the number of magnetic components and improve the utilization rate of magnetic components, transformers and inductors are usually integrated together. The converter in the article "A new zero-ripple switching dc-to-dc converter and integrated magnetics" published in IEEE Transactions on Magnetics integrates three magnetic components in the topology (i.e., two coupled inductors and one transformer), which helps to reduce the number of magnetic components and the volume of the system. However, this method uses non-standard magnetic cores, and the air gap is strictly controlled during the manufacturing process. The manufacturing of magnetic integrated transformers is very difficult, which is not conducive to the promotion of magnetic integrated transformers in this way. The article "Inductor and Transformer-Coupled Magnetic Structure for Zero-Rippledc-dcCUK Converter" published at the IEEE Applied Power Electronics Conference and Exposition (APEC) uses discrete transformers and coupled inductors. The transformers and coupled inductors are simple to manufacture, but the volume of discrete devices is large, which is not conducive to the miniaturization of the converter. At the same time, both of the above two transformers are wound in a winding manner, and the height of the magnetic parts is very high. Summary of the invention

[0004] The present application provides a flat magnetic integrated transformer suitable for a zero-ripple CUK converter, which can be used to solve the technical problems in the magnetic integration method of non-standard magnetic core structure or low magnetic core volume utilization, high height, complex design, and limitations in promotion and application.

[0005] A flat magnetic integrated transformer suitable for a zero-ripple CUK converter comprises a transformer magnetic core and a printed circuit board winding, wherein the coil winding is placed on a magnetic core column and the coil winding is fixed on the magnetic core by glue.

[0006] The magnetic core adopts EE type magnetic core; the middle column of EE magnetic core is slotted, and the magnetic core columns on both sides are not slotted;

[0007] The printed circuit board winding has four windings, including two transformer windings and two inductor windings. The two inductor windings are exactly the same and are placed on the magnetic core columns on both sides, and the transformer winding is placed on the middle column;

[0008] The turns ratio of the transformer winding is 1:1, the turns ratio of the inductor is 1:1, and the turns ratio of the transformer and the inductor is 1:2;

[0009] The first inductor winding and the second inductor winding are each made of a six-layer printed circuit board; the first transformer winding and the second transformer winding are made of a six-layer printed circuit board, and the transformer winding is placed at the top in the vertical direction; the first inductor winding is placed in the middle, and the second inductor winding is placed at the bottom;

[0010] The transformer and inductor windings should be as far away from the core center column air gap as possible;

[0011] The transformer windings are arranged in a primary-secondary-primary-secondary manner to arrange the first transformer winding and the second transformer winding.

[0012] The present invention has the following beneficial effects:

[0013] At the same time, a transformer and two coupled inductors are integrated, which can improve the utilization rate of magnetic components, greatly reduce the volume and weight of magnetic components, and improve the power density of the converter;

[0014] The transformer windings are arranged in a staggered manner, which is beneficial to reducing the leakage inductance of the transformer and can be used to reduce the drain-source voltage spike when the MOS tube is turned off. The reasonable setting of the inductive coupling degree can also reduce the input current ripple.

[0015] The magnetic core structure is common, which greatly improves the promotion of this kind of magnetic integrated transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A zero-ripple CUK converter applicable to the flat magnetic integrated transformer of the present invention, wherein: Vin is the DC input source of the converter, C1 and C2 are capacitors of the CUK converter, Q1 is a MOS tube, D1 is a diode, Lp1, Lp2, Ls1, and Ls2 together constitute a magnetic integrated converter, C0 is a filter capacitor, R is a load, Lp1 is an inductor winding 1, Ls1 is an inductor winding 2, Lp2 is a transformer winding 1, and Ls1 is a transformer winding 2;

[0017] Figure 2 This is the actual placement diagram of the magnetic integrated transformer winding;

[0018] Figure 3 The left side shows the bottom view of the inductor winding, and the right side shows the PCB diagram;

[0019] Figure 4 The left side is a top view of transformer winding 1, and the right side is a PCB diagram;

[0020] Figure 5 The left side is the bottom view of transformer winding 2, and the right side is the PCB diagram. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0022] The following first introduces the embodiments of the present application in conjunction with the accompanying drawings.

[0023] like Figures 1 to 5 As shown, a magnetic integrated transformer and a zero-ripple CUK converter principle diagram applicable thereto of the present invention; Figure 1 It is the principle diagram of the zero-ripple CUK converter, and the magnetic integrated transformer includes Lp1, Lp2, Ls1, and Ls2, wherein Lp1 is the first inductor winding, Ls1 is the second inductor winding, Lp2 is the first transformer winding, and Ls1 is the second transformer winding.

[0024] Figure 2 The actual placement diagram of the magnetic integrated transformer windings, 1-magnetic core, 3-first transformer winding and second transformer winding printed boards, 2-first inductor winding printed boards, 4-second inductor winding printed boards, where the transformer is located at the top of the vertical position, 1.5mm below is the first inductor winding, 1.5mm below the inductor winding, the winding printed boards are separated by 1.5mm insulating rubber pads, the magnetic integrated transformer windings are bonded to the magnetic core with 702 glue, the first inductor winding printed board 2 and the second inductor winding printed board 4 are wired from the bottom, and the first transformer winding and the second transformer winding printed board 3 have wires on the top and bottom;

[0025] Figure 3 The top view and PCB diagram of the inductor winding in the magnetic integrated transformer. The PCB is a six-layer board. The first inductor winding is exactly the same as the second inductor winding 2. Each has 6 turns of winding. Each turn of winding occupies one layer of PCB, corresponding to Figure 2 The first inductor winding printed board 2 and the second inductor winding printed board 4 in the figure; the numbers in the figure are the layers where the windings are located. There are two pads on the bottom layer of the PCB. The pad on the left is connected to the 6th layer winding, corresponding to Figure 1 The middle black dot end; the right pad is connected to the first layer winding, corresponding to Figure 1 The other end of

[0026] Figure 4 and Figure 5 The top view and bottom view of the same PCB, corresponding to Figure 2The first transformer winding and the second transformer winding printed circuit board 3, the PCB is a six-layer board, used for the first transformer winding and the second transformer winding, the first transformer winding and the second transformer winding each have 3 turns;

[0027] Figure 4 In the figure, the meaning of each serial number is as follows: B1-the first turn of the first transformer winding, located on the first layer of the PCB, B2-the second turn of the first transformer winding, located on the second layer of the PCB, B3-the third turn of the first transformer winding, located on the third layer of the PCB, B4 and B7 are two pads on the first layer, B5 and B6 are two pads on the sixth layer, B8-the connection hole between the first and second layers, and B9-the connection hole between the second and third layers; the first transformer winding is Figure 1 Lp2 in corresponds to Figure 4 B1, B2, B3; B8 and B9 are connected by blind holes; B4 corresponds to Figure 1 The middle black dot end is connected to the first turn of the first winding; B7 corresponds to Figure 1 The non-black dot end in the middle is connected to the third turn of the first winding;

[0028] Figure 5 In the figure, the meaning of each serial number is as follows: C1-the first turn of the second transformer winding, located on the fourth layer of PCB, C9-the second turn of the second transformer winding, located on the fifth layer of PCB, C8-the third turn of the second transformer winding, located on the sixth layer of PCB, C2, C7-two pads on the first layer, C3, C6-pads on the sixth layer, C4-connecting hole between the fourth and fifth layers, C5-connecting hole between the fifth and sixth layers; the second transformer winding is Figure 1 Ls2 in corresponds to Figure 5 C1, C8, C9, C4 and C5 are connected by blind holes. There are two pads in the 6th layer. C3 is connected to the 4th layer winding, corresponding to Figure 1 At the black dot end, C6 is connected to the sixth layer of winding, corresponding to Figure 1 Black dot end of Central Africa.

[0029] The present application adopts a multi-inductor electromagnetic decoupling design, adopts a special winding stacking design to reduce the transformer leakage inductance, adopts a staggered arrangement of winding connection points to reduce the end lateral connection area, and considers the influence of air gap on leakage inductance and coupling degree; multi-inductor electromagnetic decoupling design: each inductor is placed in a high magnetic resistance loop, and a low magnetic resistance loop is shared for electromagnetic decoupling, so as to eliminate the electromagnetic coupling of each inductor and achieve the purpose of electromagnetic decoupling of multiple variable inductors; special winding stacking design: a winding stacking design of the primary side, the secondary side, the primary side and the secondary side is adopted to reduce the leakage inductance of the transformer, and the influence of different stacking methods on the leakage inductance is discussed by means of simulation modeling, and it is proved that this stacking method has the smallest leakage inductance; staggered arrangement of winding connection points: the connection points in the same column of the end are reused to reduce the end lateral connection area; leakage inductance and coupling degree design: a leakage inductance air gap model and a coupling degree air gap model are established to find out the relative position of the winding air gap when the leakage inductance is minimum and the relative position of the winding air gap when the coupling degree is 1.

[0030] In the magnetic integrated structure, the middle column of the magnetic core has no air gap, while the two side columns have air gaps. The two inductor windings are wound on the side columns respectively, and the middle column is wound around the winding of the transformer. The magnetic flux lines of the two inductor windings pass through their own side columns respectively, and use the low magnetic resistance middle column to form their own loops.

[0031] The integrated magnetic parts adopt EE type magnetic core, the middle magnetic core column has slots of the same length, and the magnetic core columns on both sides have no slots

[0032] The winding adopts printed circuit board.

[0033] The transformer winding stacking method adopts the PPSSPPSS staggered arrangement method, which can greatly reduce the leakage inductance of the transformer.

[0034] The above-described embodiments of the present application do not constitute a limitation on the protection scope of the present application.

[0035] In the process of determining the structure of the present application, the ideas of multi-inductor electromagnetic decoupling, special winding lamination, simplified winding connection points, minimum leakage inductance and maximum coupling are adopted; among them, multi-inductor electromagnetic decoupling design: each inductor is placed in a high magnetic resistance circuit, and a low magnetic resistance circuit is shared for electromagnetic decoupling, so as to eliminate the electromagnetic coupling of each inductor and achieve the purpose of electromagnetic decoupling of multiple variable inductors; special winding lamination design: the winding lamination design of the primary side, the secondary side, the primary side and the secondary side is adopted to reduce the leakage inductance of the transformer, and the influence of different lamination methods on the leakage inductance is discussed by means of simulation modeling, and it is proved that the leakage inductance of this lamination method is minimized; winding connection point simplified design: the winding connection points are staggered, and the connection points in the same column of the end are reused to reduce the lateral connection area of ​​the end; minimum leakage inductance design and maximum coupling design: a leakage inductance air gap model and a coupling air gap model are established to find out the relative position of the winding air gap when the leakage inductance is minimum and the relative position of the winding air gap when the coupling degree is maximum.

Claims

1. A flat magnetic integrated transformer suitable for zero-ripple CUK converter, characterized in that: The transformer comprises a magnetic core and a printed circuit board winding of the transformer; The printed circuit board winding has four windings, including two transformer windings and two inductor windings. The two inductor windings are exactly the same and are placed on the magnetic core columns on both sides, and the transformer winding is placed on the middle column.

2. The transformer according to claim 1, characterized in that: The magnetic core adopts EE type magnetic core; the middle column of EE magnetic core is slotted, and the magnetic core columns on both sides are not slotted.

3. The transformer according to claim 1, characterized in that: The turns ratio of the transformer winding is 1:1, the turns ratio of the inductor is 1:1, and the turns ratio of the transformer to the inductor is 1:

2.

4. The transformer according to claim 3, characterized in that: The first inductor winding and the second inductor winding are each made of a six-layer printed circuit board; the first transformer winding and the second transformer winding are made of a six-layer printed circuit board, and the transformer winding is placed at the top in the vertical direction; the first inductor winding is placed in the middle, and the second inductor winding is placed at the bottom.

5. The transformer according to claim 1, characterized in that: The transformer and inductor windings are far away from the air gap in the core column.

6. The transformer according to claim 1, characterized in that: The transformer windings are arranged in a primary-secondary-primary-secondary manner to arrange the first transformer winding and the second transformer winding.

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