Power supply topological structure with switching tubes located between primary windings and planar transformer

Abstract

The invention relates to the technical field of power supplies, and discloses a power supply topological structure with switching tubes located between primary windings and a planar transformer. The power supply topological structure only comprises a primary winding and a secondary winding, the first winding and the second winding jointly form the primary winding, and the switching tube is located between the first winding and the second winding and connected with the first winding and the second winding in series. When the number of turns, the perimeter and the line width of the windings meet the relation conditions given by the invention, the total charge on a stray capacitor between the primary winding and the secondary winding of the planar transformer based on the power supply topological structure is approximate to zero, and good conduction performance can be obtained. Compared with a traditional transformer needing a plurality of windings such as primary windings, secondary windings, power supply windings and shielding windings, the structure is greatly simplified; the low-cost planar transformer can be realized by using four layers of plates, and compared with a traditional multi-layer plate planar transformer, the structure, the process and the materials are simplified, and the planar transformer has obvious cost advantages in a medium-power section and can replace a winding transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a power supply topology structure in which a switch tube is located between primary windings and a planar transformer. Background Art

[0002] In traditional power supply topology, the switch tube is usually located between the primary and ground wire of the transformer. In order to meet the regulatory requirements for conduction and radiation, as well as the power supply needs of the controller, the transformer needs power supply windings and shielding windings in addition to the primary and secondary windings, and the transformer structure is relatively complex.

[0003] For wound transformers, it is not difficult to realize such a transformer. However, since wound transformers need to be wound individually, it is not possible to guarantee that each transformer has completely consistent performance. Usually, a relatively large margin needs to be left in the design, which increases the difficulty of design and production. At the same time, it is also because wound transformers need to be wound individually, the process is complicated and the production capacity is limited.

[0004] With the development of GaN technology (wide bandgap semiconductor material gallium nitride technology) and multi-layer PCB technology, the use of multi-layer PCB boards to make transformers, that is, the application of planar transformers, is becoming more and more widespread. Planar transformers have the characteristics of good consistency, easy mass production, and unlimited production capacity. However, due to the complex structure, more than 4 windings are required, which means that more than 6 layers of PCB boards must be used, which is costly and cannot replace wound transformers.

[0005] Therefore, according to the traditional power supply topology, whether it is the manufacture of a winding transformer or a planar transformer, there are problems such as complex structure, complex process, limited production capacity and high cost. Summary of the invention

[0006] The purpose of the present invention is to address the defects of the prior art and provide a power supply topology structure in which the switch tube is located between the primary windings, and a planar transformer manufactured using the power supply topology structure, so as to simplify the transformer structure, greatly simplify the production process and materials, and solve the problems raised in the background technology.

[0007] In order to achieve the above object, the present invention proposes the following technical solutions: A power supply topology structure in which a switch tube is located between primary windings, characterized in that: it includes and has only two windings, a primary winding and a secondary winding, wherein the first winding and the second winding together constitute the primary winding, and includes a switch tube, wherein the switch tube is located between the first winding and the second winding, and forms a series relationship with the first winding and the second winding, wherein the second end of the switch tube is connected to the second end of the first winding, and the third end of the switch tube is connected to the first end of the second winding; it includes a high-voltage input filter circuit, a rectifier output circuit and a control circuit, wherein one end of the high-voltage input filter circuit is connected to the first end of the first winding, and the other end is connected to the second end of the second winding, and one end of the rectifier output circuit is connected to the first end of the secondary winding, and the other end is connected to the second end of the secondary winding; the first end of the switch tube is connected to the control end of the control circuit, and the third end of the switch tube and the controller ground wire are connected to the first end of the second winding to form a floating ground; and the number of turns, circumference and line width of the primary and secondary windings are adjusted so that the total charge on the parasitic capacitance between the primary and secondary windings is approximately 0.

[0008] Furthermore, based on the above power supply topology, a specific circuit is provided: the winding three is a secondary winding, the rectifier output circuit includes an output capacitor two and a rectifier diode two, the first end of the winding three is connected to the positive electrode of the output capacitor two, the second end of the winding three is connected to the cathode of the rectifier diode two, and the anode of the rectifier diode two is connected to the negative electrode of the output capacitor two; the negative electrode of the output capacitor two is grounded, and the positive electrode supplies power to the load; the capacitance between the winding one and the winding three is recorded as C1, and the capacitance between the winding two and the winding three is recorded as C2; according to the input The voltage, output voltage and the number of turns of the winding one, winding two and winding three are used to calculate the average voltage of the winding one, winding two and winding three, which are recorded as V1, V2 and V3 respectively; the charges on C1 and C2 are respectively: the charge Q1 of the winding one to the winding three is Q1=C1V1; the charge Q2 of the winding two to the winding three is Q2=-C2V2; the charge Q3 of the winding three to the winding one is Q3=C1V3; the charge Q4 of the winding three to the winding two is Q4=C2V3; the number of turns, circumference and line width of the winding one, winding two and winding three are adjusted so that ∑Q i Approximately 0, that is, C1V-C2V2+C1V3+C2V3 is approximately 0. Based on the transformer of the power topology structure in which the switch tube is located between the primary windings, when the above conditions are met, the total charge on the parasitic capacitance between the primary and secondary windings is approximately 0, and good conduction performance can be obtained.

[0009] Based on the power topology structure in which the switch tube is located between the primary windings, a planar transformer is provided, characterized in that: the primary and secondary windings are made of PCB boards, including four layers of PCB boards stacked, the first layer of PCB boards from top to bottom prints the winding one, the winding three is divided into the front section of the winding three and the rear section of the winding three, and the second and third layers of PCB boards print the front section of the winding three and the rear section of the winding three respectively, the front section of the winding three and the rear section of the winding three are connected in series, and the fourth layer of PCB board prints the winding two. The PCB board is provided with a through hole, an opening is provided in the middle to accommodate the iron core, and is made of a glass fiber substrate, a paper substrate, a ceramic substrate or a flexible plate.

[0010] According to the characteristics of the transformer conduction performance under the power supply topology structure of the present invention, it can be deduced that when the above-mentioned planar transformer has the following parameter relationship, good conduction performance can be obtained: the number of turns of the winding 1, winding 2, the front section of winding 3, and the rear section of winding 3 are n1, n2, and n3 respectively. 31 、n 32 The average perimeters of the windings 1 and 2 are l1 and l2 respectively, and the line widths of the windings 1 and 2 are w1 and w2 respectively. By designing the planar transformer, l1= l2, and n1 2 w1+ n 31 n1w1 +(n 31 +n 32 ) n2w2 = n2 2 w2, at this time the planar transformer can obtain good conduction performance.

[0011] Furthermore, based on the above parameter relationship, n1w1=n2w2, n1 + 2n 31 +n 32 = n2, the planar transformer can obtain good conduction performance.

[0012] Furthermore, based on the above parameter relationship, the number of turns of the secondary winding is designed to be 2, and n 31 =n 32 =1, then we only need to maintain the number of turns of the two primary windings of the transformer n2= n1 + 3 so that the planar transformer can obtain good conduction performance.

[0013] It should be noted that, in the power topology structure in which the switch tube is located between the primary windings, the rectifier output circuit may also adopt the following structure, that is, the first end of the winding three is connected to the anode of the rectifier diode two, the cathode of the rectifier diode two is connected to the positive electrode of the output capacitor two, and the second end of the winding three is connected to the negative electrode of the output capacitor two. The structure and manufacturing method of the corresponding planar transformer can be adjusted and changed based on the above changes, and the effect achieved remains unchanged.

[0014] In the power supply topology structure in which the switch tube of the present invention is located between the primary windings, the secondary winding can also adopt the following structure, the secondary winding is divided into two windings, namely, secondary winding one and secondary winding two, like the primary winding, the rectifier diode two is located between the secondary winding one and the secondary winding two, forming a series relationship, the cathode of the rectifier diode two is connected to the second end of the secondary winding one, and the anode is connected to the first end of the secondary winding two; the first end of the secondary winding one is connected to the positive electrode of the output capacitor two, and the second end of the secondary winding two is connected to the negative electrode of the output capacitor two.

[0015] Based on the above-mentioned second power topology structure in which the switch tube is located between the primary windings, another planar transformer is provided, characterized in that: the primary winding and the secondary winding are made of PCB boards, including four layers of stacked PCB boards, on which the winding one, secondary winding one, secondary winding two, and winding two are printed in sequence from top to bottom; the PCB board is provided with a through hole, and an opening is provided in the middle to accommodate the iron core, and is made of a glass fiber substrate, a paper substrate, a ceramic substrate or a flexible board.

[0016] According to the characteristics of the transformer conduction performance under the power supply topology structure of the present invention, it can be deduced that when the planar transformer has the following parameter relationship, good conduction performance can be obtained: the number of turns of the winding 1, winding 2, sub-winding 1, and sub-winding 2 are n1, n2, n3, and n4 respectively, the average circumference of the winding 1 and winding 2 are l1 and l2 respectively, the line width of the winding 1 and winding 2 are w1 and w2 respectively, and the design of the planar transformer makes n1 2 l1w1+ n4 n2l2w2 = n2 2 l2w2 +n3n1l1w1, at this time the planar transformer can obtain good conduction performance.

[0017] Furthermore, based on the above parameter relationship, l1=l2, and n1w1=n2w2, n1+n4=n2+n3 are achieved, and the planar transformer can obtain good conduction performance.

[0018] Furthermore, based on the above parameter relationship, the number of turns of the secondary winding 1 and the secondary winding 2 is designed to be the same, that is, n3 = n4. Then, it is only necessary to maintain the number of turns of the two primary windings of the transformer n1 = n2 to enable the planar transformer to obtain good conduction performance.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The power supply topology structure of the present invention is applied to the transformer. Since there are only two windings, primary and secondary, the structure is greatly simplified compared with the traditional transformer with multiple windings such as primary, secondary, power supply, and shielding. 2. When the number of turns, circumference and line width of the winding meet the relationship conditions given in the present invention, the planar transformer can obtain good conduction performance; 3. When the terminal circuit area of ​​the switch tube and the number of turns of the winding meet the relationship conditions given in the present invention, the planar transformer can obtain good radiation performance; 4. A four-layer board can be used to realize a low-cost planar transformer. Compared with the traditional multi-layer board planar transformer, the structure, process, and materials are greatly simplified, which can reduce the cost by about 30%. Compared with the traditional winding transformer in the medium power range, it has obvious cost advantages and can replace the winding transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The power supply topology structure in which the switch tube is located between the primary windings of the present invention; Figure 2 A transformer circuit based on the power supply topology structure of the present invention; Figure 3 for Figure 2 Schematic diagram of the capacitance between the windings of the circuit; Figure 4 Based on Figure 2 Schematic diagram of the planar transformer of the circuit structure; Figure 5 for Figure 4 Schematic diagram of inter-winding capacitance of planar transformer; Figure 6 Another transformer circuit based on the power supply topology of the present invention; Figure 7 Based on Figure 6 Schematic diagram of a planar transformer for power topology; Figure 8 for Figure 7 Schematic diagram of inter-winding capacitance of planar transformer; Fig. 9 for Figure 2 Another variation of the circuit structure; Fig.10 It is a power supply topology structure in the prior art. DETAILED DESCRIPTION

[0021] The present invention is further described below through the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0022] Traditional power supply topologies such as Fig.10 As shown, the switch tube Q1 is located between the primary and ground wires of the transformer. In order to meet the requirements of the regulations on conduction and radiation, as well as the power supply needs of the controller, the transformer needs a power supply winding and a shielding winding in addition to the primary and secondary windings, and the transformer structure is relatively complex.

[0023] The power supply topology structure provided by the present invention in which the switch tube is located between the primary windings is as follows: Figure 1 As shown, it is characterized in that: it includes and has only two windings, primary and secondary, and winding one N1 and winding two N2 together constitute the primary winding, including a switch tube Q1, which is located in winding one N1 and winding two N2, and forms a series relationship with N1 and N2, and the second end of the switch tube Q1 is connected to the second end of N1, and the third end of the switch tube Q1 is connected to the first end of N2; it includes a high-voltage input filter circuit, a rectifier output circuit and a control circuit, one end of the high-voltage input filter circuit is connected to the first end of the winding one N1, and the other end is connected to the second end of the winding two N2, one end of the rectifier output circuit is connected to the first end of the secondary winding N3, and the other end is connected to the second end of the secondary winding N3; the first end of the switch tube Q1 is connected to the control end of the control circuit, and the third end of the switch tube Q1 and the controller ground wire are connected to the first end of the winding two N2 to form a floating ground. The value of the power supply topology structure of the present invention lies in: adjusting the number of turns, circumference and line width of the primary and secondary windings so that the total charge on the parasitic capacitance between the primary and secondary windings is approximately 0, thereby obtaining good conduction performance, thereby greatly simplifying the transformer structure.

[0024] See also Figure 2 Based on the above power supply topology, a specific transformer circuit is provided: the winding three N3 is a secondary winding, the rectifier output circuit includes an output capacitor two EC2 and a rectifier diode two D2, the first end of the winding three N3 is connected to the positive electrode of the capacitor two EC2, the second end of the winding three N3 is connected to the cathode of the rectifier diode two D2, and the anode of the rectifier diode two D2 is connected to the negative electrode of the output capacitor two EC2; the negative electrode of the output capacitor two EC2 is grounded, and the positive electrode supplies power to the load.

[0025] See also Figure 3 , is a schematic diagram of the inter-winding capacitance of the above power topology. Based on the above power topology in which the switch tube is located between the primary windings, good conduction performance can be obtained when the following conditions are met: The capacitance between winding 1 N1 and winding 3 N3 is recorded as C1, and the capacitance between winding 2 N2 and winding 3 N3 is recorded as C2; According to the input voltage, output voltage, and the number of turns of windings N1, N2, and N3, the average voltages V1, V2, and V3 of the N1, N2, and N3 windings can be calculated, and the positive and negative polarities can be marked according to the phase relationship; according to Figure 3 As shown in the polarity, if V1 is positive, then V3 is positive and V2 is negative.

[0026] Calculate the charges on C1 and C2 respectively: N1 to N3, Q1=C1V1 N2 to N3, Q2=-C2V2 N3 to N1, Q3=C1V3 N3 to N2, Q4=C2V3 Find the algebraic sum of Q1, Q2, Q3, and Q4, and adjust the wire diameter, circumference, and number of turns of N1, N2, and N3 accordingly so that ∑Q i =C1V1-C2V2+C1V3+C2V3=0, that is, the total charge on the parasitic capacitance between the primary and secondary windings is approximately zero, that is, the displacement current is approximately zero, so the transformer can obtain good conduction performance.

[0027] The above-mentioned characteristics of obtaining good conduction performance are applicable to any transformer based on the power supply topology structure of the present invention, including a wound transformer or a planar transformer. However, since the wire diameter, circumference and number of turns of the wound transformer winding are difficult to adjust, the present invention is more valuable when applied to a planar transformer.

[0028] Embodiment 1: Based on the power supply topology structure in which the switch tube is located between the primary windings provided by the present invention, the present invention provides a planar transformer, see Figure 4 and Figure 5 The primary and secondary windings are made of PCB boards, including four layers of PCB boards stacked together. From top to bottom, the first layer of PCB board is printed with winding one N1, and the winding is divided into three parts: winding three front section N 31 And winding three rear section N 32 , and the second and third PCB boards are printed with N 31 and N3, N 31 、N 32 They are connected in series inside the PCB board to form the secondary winding N3 in the power topology structure, and the second winding N2 is printed on the fourth layer PCB board.

[0029] See also Figure 4 The winding part of the above-mentioned planar transformer is a four-layer PCB board, with one winding on each layer. The thin wire is the frame of the PCB board, the gray part constitutes the conductor of the transformer winding, that is, the copper foil on the PCB board, and the blank part is the substrate of the PCB board, which is an insulating material. The PCB board is provided with through holes and an opening in the middle to accommodate the iron core, and is made of a glass fiber substrate, a paper substrate, a ceramic substrate or a flexible board.

[0030] According to the characteristics of the transformer conduction performance under the power supply topology structure of the present invention, it can be deduced that when the above-mentioned planar transformer has the following parameter relationship, good conduction performance can be obtained: the number of turns of the winding 1, winding 2, the front section of winding 3, and the rear section of winding 3 are n1, n2, and n3 respectively. 31 、n 32 The average perimeters of the windings 1 and 2 are l1 and l2 respectively, the line widths of the windings 1 and 2 are w1 and w2 respectively, and the design of the planar transformer makes l1= l2, n1w1=n2w2, n1 + 2n 31 +n32 =n2, at this time the planar transformer can obtain good conduction performance. The derivation process is as follows: Due to N 31 There is N between N2 32 Conductor of winding, N 32 There is N between N1 31 The conductor of the winding, therefore N 31 Between N2 and N 32 The capacitance between N1 and N2 is very small and can be ignored. 31 The capacitance C1, N2, N 32 Intermediate capacitor C2.

[0031] N1 and N 31 , N2 and N 32 They form two planar capacitors respectively. According to the planar capacitance calculation formula C=εε0S / d, where ε is the relative dielectric constant and ε0 is the vacuum dielectric constant 8.86×10 -12 F / m, S is the plate area, d is the plate spacing; ε and d can be obtained from the PCB manufacturer, and S can be obtained by calculating the expanded area of ​​N1 and N2 windings. Therefore, C1 and C2 can be calculated.

[0032] Then according to the turns ratio, calculate N1, N2, N 31 、N 32 The voltages on the windings are V1, V2, V 31 、V 32 .

[0033] Similarly, according to the polarity of each winding of the transformer, calculate the charge on C1 and C2, adjust the line width and number of turns of N1 and N2, so that ∑Q i =0, that is, the displacement current is zero, and good conduction performance can be obtained.

[0034] The specific calculation process is as follows: First calculate C1, C2 Assume: N1, N2, N 31 、N 32 The number of turns of the windings are n1, n2, n 31 、n 32 The average circumferences of N1 and N2 windings are l1 and l2 respectively. The line widths of N1 and N2 windings are w1 and w2 respectively. Then: C1=εε0n1l1w1 / d C2=εε0n2l2w2 / d Assume that the voltage of each coil in the transformer is v. According to the coupling relationship of the transformer, we know that: V1=n1v V2=n2v V 31 =n 31 v V 32 =(n 31 +n 32 )v Similarly, V1 is defined as positive. According to the polarity relationship in the figure above, we can know that V 31 、V 32 is positive and V2 is negative.

[0035] calculate Q1=C1V1= n1vεε0n1l1w1 / d Q2=-C2V2= -n2vεε0n2l2w2 / d Q 31 =C1V 31 = n 31 vεε0n1l1w1 / d Q 32 =C2V 32 = (n 31 +n 32 )vεε0n2l2w2 / d ∑Q i =n1vεε0n1l1w1 / d-n2vεε0n2l2w2 / d+n 31 vεε0n1l1w1 / d+(n 31 +n 32 )vεε0n2l2w2 / d=0 After simplification, we get: n1 2 l1w1-n2 2 l2w2+n 31 n1l1w1+(n 31 +n 32 ) n2l2w2=0 n1 2 l1w1+n 31 n1l1w1+(n 31 +n 32 ) n2l2w2=n2 2 1v2 That is, as long as the planar transformer is designed and manufactured to satisfy the above equation, good conduction performance can be obtained.

[0036] The above formula n1 2 l1w1+n 31 n1l1w1+(n 31 +n 32 ) n2l2w2=n22 The calculation of l2w2 is relatively complicated, and it is also troublesome to adjust and take into account l1, l2, w1, w2, n1, n2 at the same time. The following is a simplified design method that is relatively feasible in engineering.

[0037] In design, l1= l2 can be achieved, so the above formula can be simplified to n1 2 w1+ n 31 n1w1 +(n 31 +n 32 ) n2w2 = n2 2 w2 Similarly, in design, n1w1=n2w2 can be achieved, so the above formula can be further simplified to n1 + 2n 31 +n 32 = n2 From this we can conclude that: When l1= l2, n1w1=n2w2, the number of turns of the transformer winding only needs to maintain the following relationship, n1 + 2n 31 +n 32 = n2 Good conductivity performance can be obtained.

[0038] Furthermore, in the design, n 31 =n 32 =1, that is, the secondary is 2 turns, then it is only necessary to maintain the number of turns of the two primary windings of the transformer n2= n1 + 3 to obtain good conduction performance.

[0039] The following describes a power topology structure based on the present invention in which the switch tube is located between the primary windings, and another transformer circuit can be derived. The secondary winding can also be used as follows Figure 6 In the structure shown, the secondary winding is divided into two windings like the primary winding, namely, the secondary winding 1 N3 and the secondary winding 2 N4. The rectifier diode 2 D2 is located between the secondary winding 1 N3 and the secondary winding 2 N4, forming a series relationship. The cathode of the rectifier diode 2 D2 is connected to the second end of the secondary winding 1 N3, and the anode is connected to the first end of the secondary winding 2 N4; the first end of the secondary winding 1 N3 is connected to the positive electrode of the output capacitor 2 EC2, and the second end of the secondary winding 2 N4 is connected to the negative electrode of the output capacitor 2 EC2.

[0040] Embodiment 2: Based on the above transformer circuit, the present invention provides another planar transformer, see Figure 7 and Figure 8The primary winding and the secondary winding are made of PCB boards, including four layers of stacked PCB boards, on which the winding 1 N1, the secondary winding 1 N3, the secondary winding 2 N4, and the winding 2 N2 are printed in sequence from top to bottom.

[0041] See also Figure 7 The winding part of the above-mentioned planar transformer is a four-layer PCB board, with one winding on each layer. The thin wire is the frame of the PCB board, the gray part constitutes the conductor of the transformer winding, that is, the copper foil on the PCB board, and the blank part is the substrate of the PCB board, which is an insulating material. The PCB board is provided with through holes and an opening in the middle to accommodate the iron core, and is made of a glass fiber substrate, a paper substrate, a ceramic substrate or a flexible board.

[0042] According to the characteristics of the transformer conduction performance under the power supply topology structure of the present invention, it can be deduced that when the above-mentioned planar transformer has the following parameter relationship, good conduction performance can be obtained: the number of turns of winding one N1, winding two N2, sub-winding one N3, and sub-winding two N4 are n1, n2, n3, and n4 respectively, the average circumference of winding one N1 and winding two N2 are l1 and l2 respectively, the line width of winding one N1 and winding two N2 are w1 and w2 respectively, and through the design of the planar transformer, l1=l2, n1+n4=n2+n3, and the planar transformer can obtain good conduction performance.

[0043] The derivation process is given below: Since there is a conductor of the N4 winding between N3 and N2, and a conductor of the N3 winding between N4 and N1, the capacitance between N3 and N2, and between N4 and N1 is very small and can be ignored. Here, we only need to examine the capacitance C1 between N1 and N3, and the capacitance C2 between N2 and N4.

[0044] N1 and N3, N2 and N4 form two planar capacitors respectively. According to the planar capacitance calculation formula C=εε0S / d, where ε is the relative dielectric constant, ε0 is the vacuum dielectric constant, 8.86×10 -12 F / m, area S is the plate area, d is the plate spacing; ε, d can be obtained from the PCB manufacturer, S can be obtained by calculating the expansion area of ​​N1, N2 windings. Therefore, C1 and C2 can be calculated.

[0045] Then, according to the turns ratio, the voltages V1, V2, V3, and V4 on the N1, N2, N3, and N4 windings are calculated. Similarly, according to the polarity of each winding of the transformer, the charge on C1 and C2 when the switch tube is switched is calculated, and the line width and number of turns of N1 and N2 are adjusted so that ∑Q i =0, that is, the displacement current is zero, and good conduction can be obtained.

[0046] The specific calculation process is as follows: Assume that the number of turns of N1, N2, N3, and N4 windings are n1, n2, n3, and n4 respectively. The average circumferences of N1 and N2 windings are l1 and l2 respectively. The line widths of N1 and N2 windings are w1 and w2 respectively but: C1=εε0n1l1w1 / d C2=εε0n2l2w2 / d Assume that the voltage of each coil in the transformer is v. According to the coupling relationship of the transformer, we know that V1=n1v V2=n2v V3=n3v V4=n4v Similarly, V1 is defined as positive. According to the polarity relationship in the above figure, V4 is positive, and V2 and V3 are negative.

[0047] calculate Q1=C1V1= n1vεε0n1l1w1 / d Q2=-C2V2= -n2vεε0n2l2w2 / d Q3=-C1V3=- n3vεε0n1l1w1 / d Q4=C2V4= n4vεε0n2l2w2 / d To make: ∑Q i = n1vεε0n1l1w1 / d- n2vεε0n2l2w2 / d- n3vεε0n1l1w1 / d+n4vεε0n2l2w2 / d=0 After simplification, we get: n1 2 l1w1-n2 2 l2w2 - n3 n1l1w1 +n4 n2l2w2 =0 n1 2 l1w1+ n4 n2l2w2 = n2 2 l2w2 +n3 n1l1w1 That is, as long as the planar transformer satisfies the above formula in design and manufacturing, good conduction performance can be obtained.

[0048] The following is a simplified design method that is relatively feasible in engineering. In design, l1= l2 can be achieved, so the above formula can be simplified to n1 2 w1+n4n2w2 = n2 2 w2 +n3 n1w1 In terms of design, we can also achieve n1w1=n2w2, so the above formula can be simplified to n1 + n4 = n2 + n3 From this we can conclude that: When l1= l2, n1w1=n2w2, the number of turns of the transformer winding only needs to maintain the following relationship, n1 + n4 = n2 + n3 Good conductivity performance can be obtained.

[0049] Furthermore, based on the above parameter relationship, the number of turns of the secondary winding 1 and the secondary winding 2 is designed to be the same, that is, n3 = n4. Then, it is only necessary to maintain the number of turns of the two primary windings of the transformer n1 = n2 so that the planar transformer can obtain good conduction performance.

[0050] It should be noted that Figure 2 The transformer circuit shown in the figure can also be replaced by a secondary winding. Fig. 9 The structure shown is that the first end of the winding three N3 is connected to the anode of the rectifier diode two D2, the cathode of the rectifier diode two D2 is connected to the positive electrode of the output capacitor two EC2, and the second end of the winding three N3 is connected to the negative electrode of the output capacitor two EC2. The structure and manufacturing method of the corresponding planar transformer can be adjusted and changed based on the above changes, and the effect achieved remains unchanged.

[0051] The above description is only a preferred example of the present invention and is not any formal or substantial limitation to the present invention. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. The symbols of various components in the circuit diagram are only for illustrating the circuit structure. Any equivalent changes and modifications made to the above examples based on the essential technology of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A power topology structure in which the switch tube is located between the primary windings, characterized in that: The invention comprises and has only two windings, namely, a primary winding and a secondary winding, wherein the first winding and the second winding together constitute the primary winding, and comprises a switch tube, wherein the switch tube is located between the first winding and the second winding, and forms a series relationship with the first winding and the second winding, wherein the second end of the switch tube is connected to the second end of the first winding, and the third end of the switch tube is connected to the first end of the second winding; the invention comprises a high-voltage input filter circuit, a rectifier output circuit and a control circuit, wherein one end of the high-voltage input filter circuit is connected to the first end of the first winding, and the other end is connected to the second end of the second winding, and one end of the rectifier output circuit is connected to the first end of the secondary winding, and the other end is connected to the second end of the secondary winding; the first end of the switch tube is connected to the control end of the control circuit, and the third end of the switch tube and the ground wire of the controller are connected to the first end of the second winding to form a floating ground; and the number of turns, circumference and line width of the primary and secondary windings are adjusted so that the total charge on the parasitic capacitance between the primary and secondary windings is approximately 0.

2. According to claim 1, the power supply topology structure in which the switch tube is located between the primary windings is characterized in that: Winding three is a secondary winding, and the rectifier output circuit includes output capacitor two and rectifier diode two. The first end of winding three is connected to the positive electrode of output capacitor two, the second end of winding three is connected to the cathode of rectifier diode two, and the anode of rectifier diode two is connected to the negative electrode of output capacitor two; the negative electrode of output capacitor two is grounded, and the positive electrode supplies power to the load; the capacitance between winding one and winding three is recorded as C1, and the capacitance between winding two and winding three is recorded as C2; according to the input voltage, output voltage and winding one , the number of turns of winding 1, winding 2, and winding 3 are used to calculate the average voltages of winding 1, winding 2, and winding 3, which are recorded as V1, V2, and V3 respectively; the charges on C1 and C2 are respectively: the charge Q1 of winding 1 to winding 3 is Q1=C1V1; the charge Q2 of winding 2 to winding 3 is Q2=-C2V2; the charge Q3 of winding 3 to winding 1 is Q3=C1V3; the charge Q4 of winding 3 to winding 2 is Q4=C2V3; the number of turns, circumference, and line width of winding 1, winding 2, and winding 3 are adjusted so that ∑Q i It is approximately equal to 0, that is, C1V-C2V2+C1V3+C2V3 is approximately equal to 0.

3. A planar transformer of a power topology structure in which the switch tube is located between primary windings according to claim 2, characterized in that: The primary and secondary windings are made of PCB boards, including four layers of PCB boards stacked together. The first layer of PCB boards from top to bottom is used to print the winding one. The winding three is divided into a front section of winding three and a rear section of winding three. The second and third layers of PCB boards are used to print the front section of winding three and the rear section of winding three respectively. The front section of winding three and the rear section of winding three are connected in series. The fourth layer of PCB boards is used to print winding two.

4. The planar transformer according to claim 3, characterized in that: The number of turns of the winding 1, winding 2, the front section of winding 3, and the rear section of winding 3 are n1, n2, and n 31 、n 32 The average perimeters of the windings 1 and 2 are l1 and l2 respectively, and the line widths of the windings 1 and 2 are w1 and w2 respectively, satisfying the following relationship: l1= l2, n1 2 w1+ n 31 n1w1 +(n 31 +n 32 ) n2w2= n2 2 w2.

5. The planar transformer according to claim 4, characterized in that: The following relationship is also satisfied: n1w1=n2w2, n1 +2n 31 +n 32 = n2.

6. The planar transformer according to claim 5, characterized in that: The following relationship is also satisfied: the number of turns of the secondary winding is 2, that is, n 31 =n 32 =1, the number of turns of the two primary windings satisfies n2= n1 + 3.

7. The power topology structure with the switch tube located between the primary windings according to claim 2, characterized in that: The secondary winding is divided into two windings, namely, secondary winding one and secondary winding two. The rectifier diode two is located between the secondary winding one and the secondary winding two to form a series relationship. The cathode of the rectifier diode two is connected to the second end of the secondary winding one, and the anode is connected to the first end of the secondary winding two. The first end of the secondary winding one is connected to the positive electrode of the output capacitor two, and the second end of the secondary winding two is connected to the negative electrode of the output capacitor two.

8. A planar transformer of a power topology structure in which the switch tube is located between primary windings according to claim 7, characterized in that: The primary winding and the secondary winding are made of PCB boards, including four layers of stacked PCB boards, on which the winding 1, the secondary winding 1, the secondary winding 2, and the winding 2 are printed in sequence from top to bottom.

9. The planar transformer according to claim 8, characterized in that: The number of turns of the winding 1, winding 2, sub-winding 1, and sub-winding 2 are n1, n2, n3, and n4 respectively, the average circumferences of the winding 1 and winding 2 are l1 and l2 respectively, and the line widths of the winding 1 and winding 2 are w1 and w2 respectively, satisfying the following relationship: n1 2 l1w1+ n4 n2l2w2 = n2 2 l2w2 +n3 n1l1w1.

10. The planar transformer according to claim 9, characterized in that: The following relations are also satisfied: l1=l2, n1w1=n2w2, n1+n4=n2+n3.

11. The planar transformer according to claim 10, characterized in that: The following relationship is also satisfied: the number of turns of the first winding and the second winding is the same, and the number of turns of the first sub-winding and the second sub-winding is the same, that is, n1=n2, n3=n4.

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