CN218939408U - Planar transformer, power conversion circuit and adapter - Google Patents

Abstract

The application provides a planar transformer, a power conversion circuit and an adapter. The planar transformer includes a primary coil and a secondary coil disposed opposite the primary coil. At least one of the primary coil and the secondary coil comprises a winding coil, wherein the winding coil is formed by bending a metal sheet, and two oppositely arranged winding layers and a connecting bridge for connecting the two winding layers are formed after bending. At least two winding coils are stacked along a first direction, the first direction is perpendicular to the surface where the winding layers are located, and two winding layers of one winding coil are arranged between two winding layers of the other winding coil. Therefore, the welding connection of the coil can be reduced, the negative influence on the power conversion circuit caused by welding is reduced, accidents caused by poor welding are avoided, and the vertical installation of the planar transformer in the adapter is realized.

Description

Planar transformer, power conversion circuit and adapter

Technical Field

The application relates to the technical field of transformers, in particular to a planar transformer, a power conversion circuit and an adapter.

Background

Along with the rapid development of electronic technology, light weight, high efficiency and reliability are becoming the development direction of electronic equipment, and the improvement of a switching power supply adopted by an electronic system to the direction of small volume and high conversion rate is also promoted. The traditional transformer in the switching power supply has large occupied space and large power consumption, and is one of key factors for restricting the development of the switching power supply. In order to enable the switching power supply to meet the target requirements of light weight, high efficiency and high reliability, the design optimization of the transformer is very important. Compared with the traditional transformer, the planar transformer is flat, the size, particularly the height, is greatly reduced, and the planar transformer is widely applied to a switching power supply.

The winding in the planar transformer is in a planar structure, and is mostly formed by manufacturing a spiral coil by adopting a thin copper sheet or a flat copper wire etched on a printed circuit board and stacking the spiral coil. When the coils are connected in series, a welding process is needed to be applied to connect the coils, so that the resistance between the coils is increased, the manufacturing process difficulty of the planar transformer is increased, the risk of poor welding exists, the planar transformer is horizontally installed, and the application scene is limited.

Disclosure of Invention

The utility model provides a plane transformer, power conversion circuit and adapter not only can reduce the resistance value between the winding layer, but also can avoid causing plane transformer trouble because of welding defect, promotes the reliability to realize the vertical installation of plane transformer in the adapter.

According to a first aspect of embodiments of the present application, there is provided a planar transformer, comprising: a primary coil and a secondary coil disposed opposite to the primary coil;

at least one of the primary coil and the secondary coil comprises a winding coil, wherein the winding coil is formed by bending a metal sheet, and two oppositely arranged winding layers and a connecting bridge for connecting the two winding layers are formed after bending;

at least two winding coils are stacked along a first direction, the first direction is perpendicular to the surface where the winding layers are located, and two winding layers of one winding coil are arranged between two winding layers of the other winding coil.

The technical scheme provided by the embodiment of the application can comprise the following beneficial effects:

the two winding layers are directly connected through the connecting bridge, the material of the whole winding coil is kept unchanged all the time, and the resistance is small. In the related art, the winding layers are connected through welding, the resistance of the welded joint is large, and the current loss is high. And the welding process is liable to generate defects such as cold joint, solder accumulation and poor infiltration, and the connection strength between coils and normal operation of a circuit are affected. The two winding coils are distributed in such a way that the thickness of the planar transformer can be as small as possible, the space utilization rate is improved, and the vertical installation of the planar transformer can be realized.

The technical scheme of the application is further described below:

in one embodiment, the planar transformer further comprises a base made of an insulating material.

In one embodiment, the winding layer is provided with pins, the base is provided with mounting holes, and the pins can be placed in the mounting holes.

In one embodiment, the pins are spaced apart along a second direction, the second direction being perpendicular to the first direction.

In one embodiment, the pins extend a distance from one side of the base through the mounting holes to the other side.

In one embodiment, the secondary coil is at least two winding coils, and the primary coil is disposed between the inner two winding layers.

According to a second aspect of embodiments of the present application, there is provided a power conversion circuit including: a primary circuit, a secondary circuit, and a planar transformer as in any of the embodiments described above, the planar transformer being disposed between the primary circuit and the secondary circuit.

In one embodiment, the pin is connected to a potential quiescent point of the primary circuit or a potential quiescent point of the secondary circuit.

By applying the transformer in the power conversion circuit, the circuit loss can be reduced.

According to a third aspect of embodiments of the present application, there is provided an adapter comprising the power conversion circuit of any of the embodiments described above.

In one embodiment, the adapter comprises a PCB on which the planar transformer is disposed, the plane of the winding layer being perpendicular to the plane of the PCB.

Thus, the vertical installation of the planar transformer is realized, and compared with a common transformer, the planar transformer occupies smaller area of a PCB and has higher space utilization rate.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

FIG. 1 is a schematic perspective view of a planar transformer according to an embodiment;

FIG. 2 is an exploded perspective view of the planar transformer of FIG. 1;

FIG. 3 is a schematic view of a metal sheet in an embodiment;

FIG. 4 is a front view of the winding coil of FIG. 3 with the metal sheet bent;

FIG. 5 is a left side view of the winding coil shown in FIG. 4;

FIG. 6 is a bottom view of the planar transformer of FIG. 1 without a base;

FIG. 7 is a bottom view of the planar transformer belt base of FIG. 1;

FIG. 8 is a schematic diagram of a power conversion circuit according to an embodiment;

fig. 9 is a schematic structural diagram of an adapter application scenario in an embodiment.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present application. Rather, they are merely examples of apparatus consistent with some aspects of the present application as detailed in the accompanying claims.

The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The terms "first," "second," and the like in the description and in the claims, are not used for any order, quantity, or importance, but are used for distinguishing between different elements. Likewise, the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "plurality" means two or more. Unless otherwise indicated, the terms "front," "rear," "lower," and/or "upper" and the like are merely for convenience of description and are not limited to one location or one spatial orientation. The word "comprising" or "comprises", and the like, means that elements or items appearing before "comprising" or "comprising" are encompassed by the element or item recited after "comprising" or "comprising" and equivalents thereof, and that other elements or items are not excluded. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

The utility model provides a planar transformer, power conversion circuit and adapter both can reduce the resistance value between the winding layer, can reduce the welded connection between the winding layer again, reduces the negative effect that produces power conversion circuit because of the welding, avoids the accident that the welding is bad to realize the vertical installation of planar transformer in the adapter.

For ease of understanding, the technical terms involved in the embodiments of the present application are explained and described below.

Planar transformer (plannar transformer): unlike traditional transformer structure, the magnetic core and winding of planar transformer are planar structure. The magnetic core is generally of a small-size E-type and RM-type magnetic core structure, the winding is generally formed by superposing and winding a plurality of layers of printed circuit boards (printed circuit board, PCB), and the design has low direct-current resistance, small leakage inductance and distributed capacitance, small height and high working frequency.

Skin effect: also known as skin effect. When there is an alternating current or an alternating electromagnetic field in the conductor, the current distribution inside the conductor is uneven, the current is concentrated in the "skin" portion of the conductor, that is to say the current is concentrated in a thin layer on the surface of the conductor, the closer to the surface of the conductor, the higher the current density, and in fact the current inside the conductor is smaller. As a result, the resistance of the conductor increases, and the power loss increases.

Proximity effect: the phenomenon that alternating currents approach each other to adjacent conductors in two conductors of a two-wire transmission line.

Potential dead point: in a circuit network, the voltage potential amplitude at the network node remains relatively constant during circuit operation without high frequency jumps or oscillations.

Winding layer: in planar transformers, winding layers refer to single or multi-turn coils in the windings that lie in the same plane. The plane is perpendicular to the central axis of the magnetic core surrounded by the windings, and the multi-turn coils can be wound in parallel on the same plane from inside to outside. In one winding, there may be a plurality of winding layers, each of which is arranged in a plane parallel to each other and perpendicular to the core central axis. Correspondingly, two adjacent winding layers, i.e. two planes, are parallel, and there are no two winding layers of the other winding layer in between.

The planar transformer of the present application will be described in detail with reference to the accompanying drawings. The features of the examples and embodiments described below may be combined with each other without conflict.

Referring to fig. 1 to 5, the present application provides a planar transformer 10 including a primary coil 110 and a secondary coil 120 disposed opposite to the primary coil 110. At least one of the primary coil 110 and the secondary coil 120 includes a winding coil 130, the winding coil 130 is formed by bending a metal sheet 131, and two oppositely disposed winding layers 132 and a connecting bridge 133 connecting the two winding layers 132 are formed after bending. In this way, the two winding layers 132 are directly connected by the connecting bridge 133, and the material of the whole winding coil 130 is kept unchanged all the time, so that the resistance is small. In the related art, the winding layers are connected through welding, the resistance of the welded joint is large, and the current loss is high. And the welding process is liable to appear defects such as cold joint, solder accumulation, bad infiltration, influence the normal work of joint strength and circuit between the coil, this application is through buckling into two winding layers 132 of integral structure with foil 131, need not to carry out welded connection, avoids causing planar transformer 10 trouble because of welding defect, promotes the reliability.

The use of the metal sheet 131 has a small thickness, and can greatly reduce the skin effect.

Note that, the metal sheet 131 may employ a copper bus bar. The copper bus has higher mechanical property, good electrical conductivity and thermal conductivity, good corrosion resistance and good forming processability, and is suitable for the requirements of planar transformers. The metal sheet can also be made of other types of metal materials according to practical use requirements, which are not limited in this application.

The winding layers 132 may be designed in a circular shape, a square shape, or the like, and the two winding layers 132 may be the same or different, and the connecting bridge 133 may be elongated. The sheet metal base material can be processed by punching, wire cutting, or other processing techniques to form and size the winding layer 132 and the connecting bridge 133 designed according to actual requirements.

Further, in some embodiments, referring to fig. 3 and 4, bending grooves 134 are provided at the bending portions of the winding coil 130. In this way, tearing and distortion of the foil 131 when the winding layer 132 is bent relative to the connecting bridge 133 is avoided.

The bending groove 134 may have a rectangular shape, an arc shape, or the like. The bending slots 134 typically have a kerf width greater than the thickness of the foil and a kerf depth greater than 1.5 times the thickness of the foil. The shape and size of the bending groove 134 are not limited in this application.

In some embodiments, referring to fig. 5, two winding layers 132 are disposed in parallel, and the winding layers 132 and the connection bridge 133 are disposed vertically. In this manner, the two winding layers 132 are equidistant everywhere, facilitating placement of regularly shaped coils or other components. The distance between the two winding layers 132 can be changed by changing the length of the connection bridge 133 to meet the actual use requirement.

As shown in fig. 2, the planar transformer 10 further includes a magnetic core 140, which is configured as a split structure. The center leg of the core 140 passes through the openings of the primary coil 110 and the secondary coil 120, and sandwiches the primary coil 110 and the secondary coil 120. The winding layer 132 is located within the coverage of the magnetic core 140, and the connection bridge 133 is located outside the coverage of the magnetic core 140.

The shape and material of the magnetic core 140 are not limited in this application. For example, the magnetic core 140 may be of EC type, EE type, EI type, or RM type. The core 140 may be composed of a magnetic metal oxide of a mixture of iron oxides. For example, the magnetic core 140 may be made of manganese-zinc ferrite and nickel-zinc ferrite materials.

The cross-section of the core 140 may be circular, oval, rectangular, square, or irregularly shaped.

In the embodiment of the present application, as shown in fig. 2 and 6, the secondary coil 120 includes a winding coil 130, the primary coil 110 is disposed between two winding layers 132, or the primary coil 110 includes a winding coil 130, and the secondary coil 120 is disposed between two winding layers 132. The primary coil 110 is sandwiched by the two winding layers 132 of the secondary coil 120 to form a sandwich winding method of a secondary winding, so that the primary coil 110 is far away from the magnetic core 140, the secondary voltage is low, the induced high-frequency interference is small, and the primary coil 110 and the secondary coil 120 are coupled with each other, thereby reducing leakage inductance of the planar transformer 10 and reducing loss. The secondary coil 120 is sandwiched by the two winding layers 132 of the primary coil 110 to form a sandwich winding of the primary and secondary, which increases the effective coupling area of the primary and secondary and greatly reduces leakage inductance of the planar transformer 10.

The transformer transformation ratio k=primary winding number Np/secondary winding number Ns, K >0. The transformation ratio K is chosen to be different values according to the requirements of the input and output voltages when designing the transformer, i.e. the value K is determined by the design requirements when designing the transformer. Based on the K value, in selecting the number of turns of the coil, the selection of the number of turns Np of the primary coil and the number of turns Ns of the secondary coil is varied. For example: a transformer with Np/ns=2.5 is designed, and various combinations of Np and Ns are provided that the core is unsaturated, such as np=20, ns=8, np=10, ns=4, or np=5, ns=2. In order to reduce the loss of the transformer, a conventional transformer winding design will generally select smaller Np and Ns, for example, a transformer design of k=2.5, and on the premise of satisfying the unsaturation of the magnetic core, a winding scheme of np=5 and ns=2 will be selected. Therefore, in the embodiment of the present application, as shown in fig. 4, the number of turns of the winding layer 132 is 1, and the loss of the transformer 10 can be reduced.

The number of turns of the winding layer 132 can also be designed according to the application scene requirement and the processing condition, and the specific number of turns of the winding layer 132 is not limited in the application.

It should be noted that, the output end of the planar transformer 10 is generally low voltage and high current, so the secondary coil 120 includes the winding coil 130, and is suitably made of copper material, so that the temperature rise caused by copper loss can be effectively reduced.

In some embodiments, as shown in fig. 3-5, the winding coil 130 is also provided with pins 135. The device is convenient to connect with other circuits, has simple manufacturing process, reduces processing links and reduces cost. Meanwhile, the pins 135 and the winding layer 132 are made of the same metal material, and the resistance is low.

In some embodiments, pins 135 are provided at the beginning and end of winding layer 132. Thus, the processing and manufacturing are convenient. The pins 135 are directly processed by blanking, wire cutting and other processes, and the winding layer 132 can be completed in the same processing process, so that the efficiency is high, the processing path is short, and the economy is better.

In some embodiments, the winding coil 130 is surface coated with an insulating layer (not shown). In this way, the winding coil 130 can be protected from mechanical damage and chemical corrosion, and can be isolated from other electrical components, so that the normal and safe use of the planar transformer 10 is ensured.

The insulating layer may be a tape directly attached to both sides of the winding layer 132, and the insulating tape may be a polyamide material. The insulating layer may also cover the outer surface of the winding layer 132 to form a protective layer. The specific implementation of the insulating layer is not limited in this application.

The surface insulation of the winding coil 130 is ensured, and the primary coil 110 and the secondary coil 120 are alternately assembled by adopting the sandwich structure, so that the proximity effect of the planar transformer formed by the assembly position relationship is small, and the thermal effect is overcome, and the performance is excellent.

Referring to fig. 6, the present application further provides a planar transformer 10, at least two winding coils 130 are stacked along a first direction x, where the first direction x is perpendicular to a plane on which the winding layers 132 are located, and two winding layers 132 of one winding coil 130 are disposed between two winding layers 132 of the other winding coil 130. The two winding coils 130 are arranged such that the thickness of the planar transformer 10 can be as small as possible, the space utilization is improved, and the vertical installation of the planar transformer 10 can be achieved.

In some embodiments, the secondary coil 120 is at least two winding coils 130, and the primary coil 110 is disposed between the inner two winding layers 132. In this way, the winding coils 130 are all coupled to the primary coil 110, the ampere-turns generated by the secondary coil 120 are equal to the ampere-turns generated by the primary winding, and the winding current distribution is equal without affecting other elements in the circuit.

In some embodiments, as shown in fig. 1 and 7, planar transformer 10 further includes a base 150, which is made of an insulating material. The base 150 can support the primary winding 110, the secondary winding 120, and the magnetic core 140, and can also electrically isolate the primary winding from the magnetic core, thereby protecting the circuit. The insulating material may be a conventional epoxy resin.

The base 150 is sized to fully support the core 140.

Further, as shown in fig. 7, the base 150 is provided with a mounting hole 151, and the pin 135 may be placed in the mounting hole 151. This achieves a fixation of the pins 135 and also a rapid assembly between the winding coil 130 and the base 150. The mounting holes 151 may be designed according to the shape and size of the pins 135, and an interference or transition fit may be adopted between the two.

Further, as shown in fig. 1, the pins 135 extend from one side of the base 150 through the mounting holes 151 to the other side and a distance. In this manner, the pins 135 are facilitated to be connected to other circuitry. This distance is designed and manufactured according to the actual requirements.

In some embodiments, the pins 135 are spaced apart along a second direction y, which is perpendicular to the first direction x. In this way, the arrangement and identification of the pins 135 is facilitated.

The present application also provides a power conversion circuit 20, as shown with reference to fig. 8, comprising: the primary circuit 210, the secondary circuit 220, and the planar transformer 10 described above, the planar transformer 10 being disposed between the primary circuit 210 and the secondary circuit 220. By applying the above-described transformer 10 to the power conversion circuit 20, circuit loss can be reduced. One end of the primary winding 110 is used to connect to the potential dead point of the primary circuit 210, and the secondary winding 120 is used to connect to the potential dead point of the secondary circuit 220.

In some embodiments, pin 135 is connected to a potential quiescent point of primary circuit 210 or a potential quiescent point of secondary circuit 220. Thus, the transformer 10 is connected to the power conversion circuit 20.

The present application also provides an adapter 30 comprising the power conversion circuit 20 described above. In this way, the power density and reliability of the adapter 30 can be improved, and the user experience is enhanced.

When the power of the adapter is increased due to high transformer loss, the heat consumption density is increased, so that the adapter is required to meet the heat dissipation requirement, and the power density of the adapter is restricted from being improved. The adapter 30 in the embodiment of the present application can effectively solve the above-mentioned problems by applying the transformer 10 with low loss.

In particular, the adapter 30 may be applied to the scenario of charging or powering a device. For example, fig. 9 is a schematic structural diagram of one possible application scenario in the embodiment of the present application. Referring to fig. 9, the application scenario includes an external power source 40, an adapter 30, and a device to be charged 50. The device to be charged 50 may include a cellular phone, a notebook computer, a battery, etc., which is not limited in the embodiment of the present application. Typically, the adapter 30 is connectable to an external power source 40, and the adapter 30 includes a power conversion circuit for converting a higher voltage provided by the external power source 40 into a lower voltage that meets a charging or power supply standard of the device 50 to be charged, and for charging or powering the device 50 to be charged.

In some embodiments, the adapter 30 includes a PCB board (not shown) on which the planar transformer 10 is disposed, with the plane of the winding layer 132 being perpendicular to the plane of the PCB board. Thus, the vertical installation of the planar transformer 10 is realized, and compared with a common transformer, the planar transformer occupies smaller area of a PCB and has higher space utilization rate.

In some embodiments, sockets may be provided on the PCB board into which planar transformer 10 is inserted via pins 135, facilitating quick installation and removal of planar transformer 10. Planar transformer 10 may also be secured to the PCB by soldering pins 135.

The foregoing description of the preferred embodiment of the present utility model is not intended to limit the utility model to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the utility model.

Claims (10)

1. A planar transformer, comprising: a primary coil and a secondary coil disposed opposite to the primary coil;

at least one of the primary coil and the secondary coil comprises a winding coil, wherein the winding coil is formed by bending a metal sheet, and two oppositely arranged winding layers and a connecting bridge for connecting the two winding layers are formed after bending;

at least two winding coils are stacked along a first direction, the first direction is perpendicular to the surface where the winding layers are located, and two winding layers of one winding coil are arranged between two winding layers of the other winding coil.

2. The planar transformer of claim 1, further comprising a base made of an insulating material.

3. The planar transformer of claim 2, wherein the winding layer is provided with pins, the base is provided with mounting holes, and the pins are placed in the mounting holes.

4. The planar transformer of claim 3, wherein the pins are spaced apart along a second direction, the second direction being perpendicular to the first direction.

5. The planar transformer of claim 3, wherein the pins extend a distance from one side of the base through the mounting holes to the other side.

6. The planar transformer of claim 1, wherein the secondary winding is at least two winding coils and the primary winding is disposed between the inner two winding layers.

7. A power conversion circuit, comprising: a primary circuit, a secondary circuit and a planar transformer as claimed in any one of claims 1 to 6, the planar transformer being arranged between the primary circuit and the secondary circuit.

8. The power conversion circuit according to claim 7, wherein the winding layer is provided with a pin connected to a potential dead point of the primary circuit or a potential dead point of the secondary circuit.

9. An adapter comprising the power conversion circuit of claim 7 or 8.

10. The adapter of claim 9 wherein said adapter comprises a PCB board, said planar transformer being disposed on said PCB board, said winding layer being disposed on a plane perpendicular to said PCB board.

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