Vertical high-voltage transformer and switching power supply

Abstract

The invention discloses a vertical high-voltage transformer which comprises a framework, a plurality of windings and a magnetic core, the framework comprises a wrapping post and a through hole formed in the middle of the wrapping post, the windings are wound on the wrapping post of the framework, the magnetic core is assembled into the through hole of the framework, the transformer framework and the windings are wound on the framework, and the vertical high-voltage transformer is characterized by further comprising a shielding layer; the plurality of windings comprise a primary-side first winding and a primary-side second winding, the primary-side first winding and the primary-side second winding are simultaneously wound on the same layer side by side in a branching manner to form a winding structure in which the plurality of windings are wound on the same layer in a branching manner, and four wire ends are pulled out and are fixedly connected with four transformer pins respectively; the shielding layer is of a rectangular sheet structure and is wound on the first winding and the second winding of the primary side. Through a series of methods and structure optimization, the product design of the vertical high-voltage transformer is miniaturized, and the comprehensive performance of a power supply product can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to a transformer of a switching power supply, and in particular to a vertical high-voltage transformer and a switching power supply. Background Art

[0002] For switching power supplies with an ultra-wide input range, the most common solution currently used is to connect the input circuits in series to meet the high voltage withstand requirements. When multiple stages are connected in series, the turns ratio of the input winding and the output winding of the transformer in each stage of the input circuit is consistent, and the switching transistors in each stage of the input circuit are turned on simultaneously. Existing switching power supply products with a wide input voltage range and a high maximum input voltage are often implemented with a multi-transistor series flyback circuit topology. The circuit schematic is shown in the figure below. Figure 1 As shown, a multi-transistor flyback circuit in series primarily includes power transistors Q1, Q2, Q3, and Q4, and a high-voltage transformer T1. The high-voltage transformer T1 includes a primary winding (first winding P1), a second winding (P2), a third winding (P3), and a fourth winding (P4), as well as a secondary winding (S1). A traditional high-voltage transformer comprises a bobbin, multiple windings, and a magnetic core. The bobbin includes winding posts and through-holes in the middle of the posts. Multiple windings are wound around the bobbin's winding posts, and the magnetic core is inserted into the bobbin's through-holes.

[0003] The traditional high voltage transformer adopts sandwich winding method, that is, a primary winding is wound with a layer of insulating tape, and then a secondary winding is wound with a layer of insulating tape; and then this winding method is repeated to form the winding coil of the entire transformer. Figure 2 As shown, specifically, the first winding P1 of the primary side is wound into a layer to form the innermost winding N1, part of the winding of the secondary winding S1 is wound into a layer to form the inner second layer winding N2, the second winding P2 of the primary side is wound into a layer to form the inner third layer winding N3, part of the winding of the secondary winding S1 is wound into a layer to form the inner fourth layer winding N4, the third winding P3 is wound into a layer to form the inner fifth layer winding N5, part of the winding of the secondary winding S1 is wound into a layer to form the inner sixth layer winding N6, and the fourth winding P4 is wound into a layer to form the inner seventh layer winding N7. Because the secondary winding S1 is a winding structure, the inner second layer winding N2, the inner fourth layer winding N4, and the inner sixth layer winding N6 are finally connected in parallel to form one winding. In this transformer winding method, the insulation between the primary and secondary windings relies on the insulating material of the wire itself and the yellow insulating tape between the windings. Due to the limited design space, the small-sized high-voltage transformers commonly seen on the market currently use a simple combination of wire and insulating tape to provide insulation, which is far from meeting the electrical isolation safety performance requirements of the national standard GB3836.4 (Chinese standard name: Explosive atmospheres Part 4: Equipment protected by intrinsically safe type "i"). Summary of the Invention

[0004] The present invention miniaturizes the volume of the vertical transformer through structural optimization and can meet the requirements of the national standard GB3836.4. Therefore, the structure of the present invention can significantly improve the isolation performance of the power supply product, and the product design is more miniaturized.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: A vertical high-voltage transformer is suitable for transformer applications with multiple windings in a multi-tube series flyback circuit, comprising a skeleton, multiple windings and a magnetic core. The skeleton comprises a winding post and a through-hole opened in the middle of the winding post. Multiple windings are wound on the winding post of the skeleton, and the magnetic core is inserted into the through-hole of the skeleton. The transformer skeleton and the multiple windings wound on the skeleton are characterized in that: it also includes a shielding layer; the multiple windings include a first winding and a second winding on the primary side, and the first winding and the second winding on the primary side are wound side by side on the same layer in a split-line manner to form a winding structure with multiple windings wound on the same layer, and four wire ends are pulled out for fixed connection with four transformer pins respectively; the shielding layer is a rectangular thin sheet structure, wound on the first winding and the second winding on the primary side.

[0006] Preferably, the multiple windings also include a third winding and a fourth winding on the primary side. The third winding and the fourth winding on the primary side are wound side by side on the same layer in a split-line manner to form a winding structure with multiple windings wound on the same layer, and four wire ends are pulled out for fixed connection with the four transformer pins respectively.

[0007] Preferably, the multiple windings also include a first winding and a second winding on the secondary side. The first winding and the second winding on the secondary side are wound simultaneously on the same layer and then two wire ends are pulled out, which are used to be fixedly connected to two transformer pins respectively or directly pulled out as two external lead-out ends.

[0008] Preferably, the first winding, the second winding, the third winding and the fourth winding of the primary side are made of three-layer insulated wire material, and the first winding and the second winding of the secondary side are made of Litz wire material.

[0009] Preferably, insulating tape is added between the primary and secondary windings to improve the insulation performance between the primary and secondary windings.

[0010] Preferably, the shielding layer is arranged between the primary winding and the secondary winding, has no electrical connection between the head end and the tail end, and is provided with a lead wire for connecting to the ground through the lead wire.

[0011] Preferably, the thickness of the shielding layer is determined by the primary current.

[0012] Preferably, the shielding layer is made of copper foil.

[0013] Preferably, the skeleton is provided with a winding post, and the winding post adopts a heightened design to achieve a more reasonable transformer effective window area coefficient when the primary and secondary stacked winding structure is miniaturized.

[0014] Preferably, the frame is provided with a terminal seat, and metal pins extend from both sides of the terminal seat for fixed connection with the winding wire ends of the transformer.

[0015] Preferably, a retaining wall is provided at the gap beside the winding structure of the same layer to fill the winding area of ​​the same layer so that the shielding layer can be wound more smoothly outside.

[0016] Preferably, a sleeve is added to the wire of one winding, several windings or all windings among the multiple windings.

[0017] The present invention further provides a switching power supply, comprising the above-mentioned vertical high-voltage transformer. The vertical high-voltage transformer is assembled on a PCB circuit board and packaged into a switching power supply with a multi-transistor series flyback circuit topology within 350W. The primary and secondary side electrical isolation thereof can reach 5000VAC and can pass the certification requirements of the national standard GB3836.4.

[0018] Compared with traditional transformers, the vertical high-voltage transformer of the present invention has the following beneficial effects: 1. By optimizing the winding structure and designing a suitable transformer skeleton, the primary and secondary electrical isolation of this transformer with an added shielding layer can reach 5000VAC; 2. Based on the more miniaturized product design, the winding window area is increased, which reduces the difficulty of the winding process, and the related temperature control effect can be equivalent to or better than that of traditional transformers; 3. Applicable to multi-tube series flyback circuit topology switching power supply within 350W; 4. Since the spacing between the primary windings is closer, the leakage inductance of the transformer is smaller and the noise during withstand voltage is smaller, so the transformer as a whole can significantly improve the comprehensive performance of the power supply product, and meet the national standard GB3836.4 for coal mines for the certification requirements of power supply products. Compared with traditional transformers, it can better meet market demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the schematic diagram of the commonly used flyback circuit with multiple tubes in series; Figure 2 Schematic diagram of the winding structure of a traditional transformer; Figure 3 Schematic diagram of the winding structure of the vertical high-voltage transformer of the present invention; Figure 4This is a three-dimensional structural diagram of a vertical high-voltage transformer according to the present invention, wherein the outer insulating tape of the transformer winding is peeled off to expose the inner wire. The drawn wire end of the winding is for reference only, and the wire diameter is not shown. Figure 5 This is a three-dimensional structural diagram of the vertical high-voltage transformer of the present invention from another perspective, in which the outer layer of insulating tape of the transformer winding is peeled off to expose the inner layer of wire; the drawn wire end of the winding is for reference only, and the wire diameter is not shown; Figure 6 A three-dimensional structural diagram of the skeleton of the vertical high-voltage transformer of the present invention; Figure 7 A three-dimensional structural diagram of the skeleton of the vertical high-voltage transformer of the present invention from another perspective; Figure 8 Schematic diagram of the winding structure of the frame of the vertical high-voltage transformer of the present invention, on which the innermost winding and the first shielding layer are wound; Figure 9 This is the stress waveform test diagram of the main power MOS tube of a traditional high-voltage transformer; Figure 10 This is a stress waveform test diagram of the main power MOS tube of the vertical high-voltage transformer of the present invention.

[0020] The reference numerals in the above drawings are described as follows: 100. Skeleton, 101. Winding post, 102. Terminal block, 103. Metal pin, 104. Through hole 200. Winding, 201. Primary first winding P1 (N1), 202. Primary second winding P2 (N2), 203. Primary third winding P3 (N5), 204. Primary fourth winding P4 (N6), 210. Secondary winding S1 (secondary first winding N3, secondary second winding N4), where the numbers in brackets are the numbers in the winding structure diagram corresponding to each winding 300. Magnetic core 400. Shielding layer, 401. Lead wire, 411. First shielding layer, 412. Second shielding layer 500.Insulation tape 600. Retaining Wall 700.Casing DETAILED DESCRIPTION Description of the invention concept: The flyback circuit of multiple transistors in series is commonly used. The four primary windings and three secondary windings of the traditional transformer are sandwich-wound. One winding occupies one layer of winding area of ​​the bobbin winding column. The specific winding structure is: primary-secondary-primary-secondary-primary-secondary-primary-auxiliary winding (such as Figure 2 shown).

[0021] The four primary windings and three secondary windings of the vertical high-voltage transformer of the present invention are sandwich-wound. The first primary winding and the second primary winding are on the same layer, and the two windings jointly occupy one layer of the winding area of ​​the skeleton winding column, wherein each winding occupies half of the winding area of ​​the same layer; the three secondary windings are wound in parallel; the third primary winding and the fourth primary winding are on the same layer, and the two windings jointly occupy one layer of the winding area of ​​the skeleton winding column, wherein each winding occupies half of the winding area of ​​the same layer; and a shielding layer, such as copper foil, is provided between the primary winding and the secondary winding. The specific winding structure is: primary / primary-copper foil-secondary / secondary / secondary / -copper foil-primary / primary (such as Figure 3 shown).

[0022] The vertical high-voltage transformer of the present invention optimizes the winding structure and process and designs a suitable transformer skeleton, making the product design of the transformer with an added shielding layer more miniaturized. The leakage inductance and temperature control of the transformer can be comparable to those of traditional transformers, and the isolation performance of the power supply product can be significantly improved. It also meets the national standard GB3836.4 for coal mines and the certification requirements for product intrinsic safety insulation.

[0023] The present invention and its beneficial effects will be further described in detail below with reference to specific implementation methods and the accompanying drawings. However, the specific implementation methods of the present invention are not limited thereto.

[0024] See also Figures 3 to 8 , a vertical high-voltage transformer of the present invention is suitable for transformer applications with multiple windings in a multi-transistor series flyback circuit, comprising a bobbin 100, a plurality of windings 200, and a magnetic core 300. The bobbin includes a winding post 101 and a through-hole 104 provided in the middle of the winding post. The plurality of windings 200 are wound on the bobbin winding post 101. The magnetic core 300 is inserted into the through-hole 104 of the bobbin. The bobbin also includes a shielding layer 400. The plurality of windings include a first winding 201 and a second winding 202. The first winding 201 and the second winding 202 are wound side by side on the same layer in a split-line manner, forming a winding structure in which multiple windings are wound separately on the same layer. The shielding layer 400 is a rectangular thin sheet structure, wound around the first winding 201 and the second winding 202 .

[0025] Preferably, the multiple windings may also include a third winding 203 and a fourth winding 204 on the primary side. The third winding and the fourth winding on the primary side are wound side by side on the same layer in a split-line manner to form a winding structure with multiple windings wound on the same layer, and four wire ends are pulled out for fixed connection with the four transformer pins respectively. Thus, a winding structure with multiple windings wound in the same layer is formed, including the first winding 201, the second winding 202, the third winding 203 and the fourth winding 204 of the primary side and the secondary winding 210. The first winding 201 and the second winding 202 of the primary side are wound side by side in the same layer in a split line manner, and four wire ends are pulled out for respectively fixed connection with four transformer pins; the third winding 203 and the fourth winding 204 of the primary side are wound side by side in the same layer in a split line manner, and four wire ends are pulled out for respectively fixed connection with four transformer pins; the secondary winding 210 is wound in layers and two wire ends are pulled out for respectively fixed connection with two transformer pins.

[0026] The multiple windings may also include a first winding N3 and a second winding N4 on the secondary side. The first winding and the second winding on the secondary side are wound simultaneously on the same layer and then two wire ends are pulled out for fixed connection with two transformer pins respectively or directly pulled out as two external lead-out ends. Thus, a winding structure with multiple windings wound in the same layer is formed, and multiple windings include the first winding 201, the second winding 202, the third winding 203 and the fourth winding 204 on the primary side, and the first winding N3 and the second winding N4 on the secondary side. The first winding 201 and the second winding 202 on the primary side are wound side by side in a split-line manner on the same layer, and then four wire ends are pulled out for respectively fixed connection with four transformer pins; the third winding 203 and the fourth winding 204 on the primary side are wound side by side in a split-line manner on the same layer, and then four wire ends are pulled out for respectively fixed connection with four transformer pins; the first winding N3 and the second winding N4 on the secondary side are wound on the same layer at the same time, and then two wire ends are pulled out for respectively fixed connection with two transformer pins. In other embodiments, the first winding N3 and the second winding N4 on the secondary side can also be wound side by side in a split-line manner on the same layer, and then four wire ends are pulled out for respectively fixed connection with four transformer pins to meet the certification requirements of the same or similar transformers.

[0027] The first, second, third and fourth windings of the primary side are made of three-layer insulated wire, and the first and second windings of the secondary side are made of Litz wire. Insulating tape 500 is added between the primary and secondary windings to improve the insulation performance between the primary and secondary windings. Figure 3 and Figure 8 As shown, the shield layer of the vertical high-voltage transformer of the present invention is disposed between the primary and secondary windings. Its leading and trailing ends are not electrically connected. A lead wire 401 is provided for connection to ground. The thickness of the shield layer is determined by the primary current. The shield layer is made of copper foil.

[0028] The bobbin is provided with a winding post 101, which is designed to be elevated to achieve a more reasonable transformer effective window area coefficient when miniaturizing the primary and secondary stacked winding structure. In this embodiment, when miniaturizing the primary and secondary stacked winding structure, a more reasonable effective window area coefficient can be determined by the innermost dimension of the stacked winding structure. The innermost dimension of the winding structure is the height of the two windings wound side by side, with separate lines and separate sides.

[0029] The winding wire ends of the secondary side of the bobbin use Litz wire (a wire made of multiple independently insulated conductors twisted or braided together), which has a relatively thick wire diameter. In order to simplify the transformer structure design, the wire ends of the secondary winding can generally be directly pulled out as the external lead-out terminals of the transformer (i.e., the pins of the transformer, which are soldering pins used for electrical connection to the PCB circuit board). However, due to the differences in the secondary winding wire diameters of different models of power supply products, the corresponding transformer pin soldering positions on the PCB circuit board also need to be adjusted accordingly, which makes the design consistency of the PCB circuit board worse, which is not conducive to the back-end application of the transformer. Figure 6 and Figure 7 As shown, the vertical high-voltage transformer of the present invention preferably has a terminal base 102 on its frame, and metal pins 103 extend from both sides of the terminal base for fixed connection with the winding wire ends of the transformer.

[0030] A retaining wall 600 is provided in the gaps between winding structures on the same layer to fill the winding area on the same layer, allowing the shielding layer to be wound more smoothly outside. The wires of one, several, or all of the multiple windings can be provided with a sleeve 700 to further improve the insulation performance between the primary and secondary windings.

[0031] Under the same flyback circuit topology application environment, the working conditions of the main power MOS tube of the traditional transformer and the vertical high-voltage transformer of the present invention were tested respectively. The stress peak (maximum value) of the waveform obtained in the test is related to the input voltage and the leakage inductance of the transformer. Figure 9 and Figure 10 It can be seen that Figure 9 The leakage inductance of the traditional transformer is too large, and the stress peak is 536.06V; Figure 10 The vertical high-voltage transformer of the present invention has a relatively low leakage inductance, resulting in a stress peak of 470.4V. Compared to the platform voltage of 450V, this stress peak value is reduced from the traditional 85V peak voltage to a peak voltage of 20V, a reduction of more than 76%. This essentially eliminates the stress spike caused by the transformer leakage inductance, achieving a significant optimization effect.

[0032] The vertical high-voltage transformer of the present invention is suitable for multi-transistor series flyback topology switching power supplies within 350W. By optimizing the winding structure and designing a suitable transformer skeleton, the primary and secondary electrical isolation of the transformer with an added shielding layer can reach 5000VAC. On the basis of a more miniaturized product design, the increase in the transformer window area reduces the difficulty of the winding process, and the related temperature control can also be equivalent to or better than that of a traditional transformer. Moreover, since the spacing between the primary windings is closer, the leakage inductance of the transformer is smaller, and the noise during withstand voltage is smaller, so that the transformer as a whole can significantly improve the comprehensive performance of the power supply product, and meet the certification requirements of the national standard GB3836.4 for coal mines for power supply products. Compared with traditional transformers, it can better meet market demand.

[0033] The above embodiments are only used to help understand the methods and core ideas of the present invention. For ordinary technicians in this technical field, without departing from the principles of the present invention, other equivalent application schemes that can be naturally associated with the above description and examples, as well as several improvements and modifications to the present invention, all fall within the scope of protection of the claims of the present invention.

Claims

1. A vertical high-voltage transformer suitable for use in transformer applications involving multiple windings in a multi-transistor series flyback circuit, comprising a bobbin, multiple windings, and a magnetic core. The bobbin comprises winding posts and through-holes formed in the middle of the winding posts. The multiple windings are wound around the bobbin winding posts, and the magnetic core is inserted into the through-holes of the bobbin. The transformer is characterized by: Also includes shielding layer; The multiple windings include a first winding and a second winding on the primary side. The first winding and the second winding on the primary side are wound side by side on the same layer in a split-line manner to form a winding structure with multiple windings wound on the same layer, and four wire ends are pulled out for fixed connection with four transformer pins respectively. The shielding layer is a rectangular thin sheet structure and is wound around the first winding and the second winding of the primary side.

2. The vertical high-voltage transformer according to claim 1, characterized in that: The multiple windings also include a third winding and a fourth winding on the primary side. The third winding and the fourth winding on the primary side are wound side by side on the same layer in a split-line manner to form a winding structure with multiple windings wound on the same layer, and four wire ends are pulled out for fixed connection with the four transformer pins respectively.

3. The vertical high-voltage transformer according to claim 1, characterized in that: The multiple windings also include a first winding and a second winding on the secondary side. The first winding and the second winding on the secondary side are wound simultaneously on the same layer and then two wire ends are pulled out, which are used to be fixedly connected to two transformer pins respectively or directly pulled out as two external lead-out ends.

4. The vertical high-voltage transformer according to claim 3, characterized in that: The first winding, the second winding, the third winding and the fourth winding of the primary side are made of three-layer insulated wire material, and the first winding and the second winding of the secondary side are made of Litz wire material.

5. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: Insulating tape is added between the primary and secondary windings to improve the insulation performance between the primary and secondary windings.

6. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: The shielding layer is arranged between the primary winding and the secondary winding, has no electrical connection between the head end and the tail end, and is provided with a lead wire for connecting to the ground through the lead wire.

7. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: The shielding layer is made of copper foil; and / or the thickness of the shielding layer is determined by the primary current.

8. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: The bobbin is provided with winding posts, which are designed to be elevated to achieve a more reasonable transformer effective window area coefficient when miniaturizing the primary and secondary stacked winding structures. In this embodiment, when miniaturizing the primary and secondary stacked winding structures, a more reasonable effective window area coefficient can be determined based on the innermost dimensions of the stacked winding structure. The innermost dimensions of the winding structure are the height of the two windings wound side by side, with separate lines and separate sides.

9. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: The frame is provided with a terminal seat, and metal pins extend from both sides of the terminal seat for fixed connection with the winding wire end of the transformer.

10. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: A retaining wall is provided at the gap beside the winding structure of the same layer to fill the winding area of ​​the same layer so that the shielding layer can be wound more smoothly outside the structure.

11. The vertical high-voltage transformer according to claim 1 or 2, characterized in that: A sleeve is added to the wire of one winding, several windings or all windings among the multiple windings.

12. A switching power supply comprising the vertical high-voltage transformer according to any one of claims 1 to 13, characterized in that: The vertical high-voltage transformer is assembled on a PCB circuit board and is packaged into a switching power supply with a multi-tube series flyback circuit topology within 350W. The primary and secondary side electrical isolation can reach 5000VAC and can pass the certification requirements of the national standard GB3836.4.

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