PCB WINDING TRANSFORMER
The present disclosure discloses a PCB winding transformer. The PCB winding transformer includes a magnetic core and a coil board with a multilayer structure. The coil board includes a primary coil and a secondary coil wound around a magnetic core column of the magnetic core. The secondary coil is located in a first layer and a last layer, and the primary coil is located in intermediate layers. The number of turns of the secondary coil is less than that of the primary coil. At least one via hole for connecting the first layer and the last layer of the secondary coil is disposed in the coil board between an inner side of the primary coil and the magnetic core column.
This application is a Continuation Application of U.S. patent application Ser. No. 15/846,140, filed on Dec. 18, 2017, and entitled “PCB Winding Transformer and Coil Board Thereof”, the entire contents of which are incorporated herein by reference.
This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 201621395261.9 filed in P.R. China on Dec. 19, 2016, the entire contents of which are hereby incorporated by reference.
Some references, if any, which may include patents, patent applications and various publications, may be cited and discussed in the description of this invention. The citation and/or discussion of such references, if any, is provided merely to clarify the description of the present invention and is not an admission that any such reference is “prior art” to the invention described herein. All references listed, cited and/or discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.
TECHNICAL FIELDThe present disclosure relates to a transformer, in particular to a PCB winding transformer.
BACKGROUND ARTTransformer design is always a key point for a switching mode power supply.
In recent years, with the increasing demand for higher power density, high frequency has become a development trend of the switching mode power supply, thus the design of the transformer becomes more important, since the leakage inductance of the transformer has more influence on the efficiency of the switching mode power supply with high frequency.
Compared with conventional winding type transformer, PCB winding transformer can usually achieve smaller size and less leakage inductance. The structure of the PCB winding transformer may still be further optimized to reduce leakage inductance, thus improve the efficiency of the switching mode power supply with high frequency.
SUMMARYIn order to overcome the problems in the prior art, the purpose of the present disclosure is to provide a PCB winding transformer. By optimizing the position of a via hole in a coil board of the PCB winding transformer, the size of the PCB winding transformer may be further reduced, and the size of a secondary loop or a primary loop may be reduced to make leakage inductance smaller.
In one aspect, the present disclosure provides a PCB winding transformer comprising a magnetic core and a coil board with a multilayer structure. The coil board comprises a primary coil and a secondary coil wound around a magnetic core column of the magnetic core. The secondary coil is located in a first layer and a last layer, and the primary coil is located in intermediate layers. The number of turns of the secondary coil is less than that of the primary coil. At least one via hole for connecting the first layer and the last layer of the secondary coil is disposed in the coil board. The at least one via hole is disposed between an inner side of the primary coil and the magnetic core column.
As compared with the prior art, the present disclosure may at least obtain the following beneficial technical effects. By positioning the via hole corresponding to the secondary coil between an inner side of the primary coil and the magnetic core column, the size of the loop formed by the secondary coil may be reduced physically, thereby reducing the leakage inductance correspondingly. Additionally, the area of the coil board may be reduced.
Details and technical specification of the present disclosure are further described in combination with a preferred example, but shall not be construed as limit thereto.
An isolated switching mode power supply typically comprises a transformer, a primary power switch, an input bus capacitor, a secondary synchronous rectifier and an output capacitor. As shown in
First, a summary description for a conventional PCB winding transformer will be provided below, with reference to
A PCB winding transformer according to one embodiment of the present disclosure will be described below with reference to
As shown in
Further, on the coil board, a secondary synchronous rectifier 12 is provided. The secondary synchronous rectifier 12 may be located closer to the secondary coil SEC. For example, as shown in
A structural diagram of the coils shown in
Although the via hole S in the above embodiment is designed for the secondary coil SEC, the present disclosure is not limited thereto. According to the characteristics that the loop impacts on the leakage inductance, the less turns of coil the primary or secondary loop has, the greater the primary or secondary loop impacts on the leakage inductance. Therefore, by moving the via hole corresponding to the coil with less turns to a position between the inner side of the other coil with more turns and the magnetic core column (or the through hole), the size of the loop which has less turns may be physically reduced, which in turn reduces the leakage inductance. Specifically, in the above embodiment, the size of the secondary loop may be physically reduced by moving the via hole S corresponding to the secondary coil SEC to a position between the inner side of the primary coil PRI and the magnetic core column (or the through hole), thereby reducing leakage inductance.
A PCB winding transformer according to another embodiment of the present disclosure will be described below with reference to
Different from the embodiment shown in
It should be noted that the example is only used to explain the present disclosure, but not used to limit the technical solutions of the present disclosure. In addition, although the present disclosure is described in detail in combination with the example, it should be understood by those of ordinary skill in the art that modification or equivalent replacement may be made to the present disclosure. Therefore, all technical solutions and improvement thereof without departing from the spirit and scope of the present disclosure shall be incorporated in the protection scope of the claims of the present disclosure.
Claims
1. A PCB winding transformer, comprising:
- a magnetic core and a coil board with a multilayer structure;
- wherein the coil board comprises a primary coil and a secondary coil wound around a magnetic core column of the magnetic core, the secondary coil is located in a first layer and a last layer, the primary coil is located in intermediate layers, the number of turns of the secondary coil is less than that of the primary coil; and
- wherein at least one via hole for connecting the first layer and the last layer of the secondary coil is disposed in the coil board between an inner side of the primary coil and the magnetic core column.
2. The PCB winding transformer according to claim 1, wherein the secondary coil comprises two turns with flat copper foil, one turn is disposed in the first layer, and the other turn is disposed in the last layer.
3. The PCB winding transformer according to claim 1, further comprising:
- a switching device disposed on the coil board and at least partly overlapped with the secondary coil.
4. The PCB winding transformer according to claim 3, wherein the switching device is a secondary synchronous rectifier disposed on the secondary coil.
5. The PCB winding transformer according to claim 3, wherein the switching device is a secondary rectifier diode disposed on the secondary coil.
6. The PCB winding transformer according to claim 1, wherein the PCB winding transformer is used in a flyback converter.
Type: Application
Filed: Mar 29, 2021
Publication Date: Jul 29, 2021
Inventors: Haibin SONG (Shanghai), Zengyi LU (Shanghai), Jinfa ZHANG (Shanghai), Shiwei LIU (Shanghai), Jian ZHOU (Shanghai), Daofei XU (Shanghai), Jianwei SONG (Shanghai)
Application Number: 17/216,590