An intrinsically safe planar transformer for isolated safety barriers

Abstract

The invention discloses an intrinsically safe planar transformer for an isolated safety barrier, comprising a PCB board, wherein the PCB board comprises an upper top plate, at least one middle plate and a lower bottom plate stacked in sequence from top to bottom; a plurality of metallized hole pads are provided on each PCB board, and the metallized hole pads on adjacent PCB boards are electrically connected one by one; a winding groove is provided on one side of the upper top plate and the lower bottom plate, and a winding groove is provided on both sides of the middle plate, and wiring is provided in the winding groove to form a winding; the PCB board is provided with metallized vias penetrating the PCB board, and the wiring of the upper top plate is electrically connected to the wiring in the lower bottom plate through the metallized vias of the upper top plate and the lower bottom plate in sequence, and the wiring on the upper and lower sides of the middle plate is electrically connected to each other through the corresponding metallized vias. The invention easily meets the solid insulation requirements, three-terminal isolation requirements and consistency requirements of intrinsic safety explosion-proof through the stacking design of the multi-layer PCB board. The material cost is low, the assembly is simple, and the welding is convenient.

Description

Technical Field

[0001] The invention belongs to the field of power transformers, and in particular relates to an intrinsically safe planar transformer for an isolated safety barrier. Background Art

[0002] Planar transformer is a transformer with high frequency, low profile, small height and high operating frequency. Planar transformer is usually based on multi-layer printed circuit board and assembled with wiring, and the PCB wiring replaces the traditional enameled wire winding transformer form.

[0003] The isolated safety barrier is a circuit structure that electrically isolates the intrinsically safe side, non-intrinsically safe side and power supply side from each other, and meets the requirements of intrinsically safe limited energy. It is an explosion-proof associated equipment and forms a joint explosion-proof system with the intrinsically safe explosion-proof instruments on site.

[0004] Intrinsically safe explosion-proof instruments use low operating voltage and small operating current, and limit the size of the resistance, capacitance and inductance parameters used in the instrument to ensure that the spark energy generated in normal and fault conditions is insufficient to ignite the explosive mixture. They are suitable for all hazardous locations.

[0005] Therefore, the transformer with isolated safety barrier is a key component of the intrinsically safe explosion-proof circuit. It needs to electrically isolate the intrinsically safe side, non-intrinsically safe side and power supply side from each other. Under the condition of the maximum voltage Um of 250Va.c. / dc, the national standard GB3836.4-2010 and product standards require a solid insulation gap of 1mm.

[0006] However, traditional transformers with a skeleton + winding design need to meet intrinsic safety and explosion-proof requirements, and a shell needs to be designed outside the skeleton and a potting process needs to be performed. The production process is complex, costly, and has a long cycle. Wire-wound transformers also have problems such as poor consistency, long production cycle, and poor solder joint quality. Specifically, the complexity of the process requirements is mainly reflected in A. The coil pins need to be well welded, and there must be no cold joints and excess solder; B. The paint should be evenly dipped, fully covered, and there should be no obvious water drop residue; C. There should be no obvious damage on the appearance of the product; D. Solderability: Observe the welding parts (pins) of the transformer, and more than 95% of the welding area should be covered with a new smooth solder coating; E. Solder resistance: The pins should not be loose, fall off, or break; F. Marking, the font should be clear and accurate; G. The potting silicone needs to be fully cured, and the bottom surface must be kept flat and must not protrude from the shell; H. For surface-mount wire-wound transformers, there is also a requirement for the coplanarity of the surface-mount pins, which is generally not more than 0.2mm, otherwise it may cause cold soldering problems; I. In the potting mode, the side line and other area lines must ensure an electrical clearance of 2.0mm. Summary of the invention

[0007] The technical purpose of the present invention is to provide an intrinsically safe planar transformer for an isolated safety barrier to solve the problems of complex process, high cost and long cycle of traditional intrinsically safe transformers.

[0008] To solve the above problems, the technical solution of the present invention is:

[0009] An intrinsically safe planar transformer for an isolated safety barrier includes a PCB board, wherein the PCB board includes an upper top plate, at least one middle plate and a lower bottom plate stacked in sequence from top to bottom; a plurality of metallized hole pads are provided on each PCB board, and the metallized hole pads on adjacent PCB boards are electrically connected one by one; winding grooves are provided on one side of the upper top plate and the lower bottom plate, and winding grooves are provided on both sides of the middle plate, and wiring is provided in the winding grooves to form a winding. The PCB board is provided with metallized vias penetrating the PCB board, and the wiring of the upper top plate is electrically connected to the wiring in the lower bottom plate through the metallized vias of the upper top plate and the lower bottom plate in sequence, and the wiring on the upper and lower sides of the middle plate is electrically connected to each other through the corresponding metallized vias.

[0010] Further preferably, a spacing insulating plate is provided between each PCB board, and the spacing insulating plates are sequentially inserted in adjacent PCB boards.

[0011] Specifically, the plurality of metallized hole pads include a first pin, a second pin, a third pin, a fourth pin, a fifth pin, a sixth pin, a seventh pin and an eighth pin, and the above pins of each PCB board are electrically connected one by one.

[0012] Specifically, the winding includes a power supply side winding, a non-intrinsically safe side winding and an intrinsically safe side winding; the power supply side winding is obtained by the wiring in the upper top plate and the lower bottom plate and the first pin and the second pin connected thereto; the non-intrinsically safe side winding is obtained by the wiring in the middle plate and the third pin, the fourth pin and the fifth pin connected thereto; the intrinsically safe side winding is obtained by the wiring in the middle plate and the sixth pin, the seventh pin and the eighth pin connected thereto.

[0013] Specifically, the middle board includes a first middle board, a second middle board, a third middle board and a fourth middle board arranged from top to bottom; the third pin, the wiring of the first middle board, the fourth pin, the wiring of the second middle board and the fifth pin electrically connected in sequence constitute the non-intrinsically safe side winding; the sixth pin, the wiring of the third middle board, the seventh pin, the wiring of the fourth middle board and the eighth pin electrically connected in sequence constitute the intrinsically safe side winding.

[0014] Specifically, the second pin, the wiring of the upper top plate, the wiring of the lower bottom plate and the first pin, which are electrically connected in sequence, constitute a power supply side winding.

[0015] Specifically, in the non-intrinsically safe side winding, the fifth pin is the starting pin, and the routing in the second middle board is connected to the fourth pin after 10 turns counterclockwise from the fifth pin through the corresponding metallized via; the routing in the first middle board is connected to the third pin after 10 turns counterclockwise from the fourth pin through the corresponding metallized via; wherein, the routing in the first middle board and the second middle board is 9 mil line width PCB routing.

[0016] Specifically, in the intrinsically safe side winding, the eighth pin is the starting pin, and the routing in the fourth middle board is connected to the seventh pin after 10 turns counterclockwise from the eighth pin through the corresponding metallized via; the routing in the third middle board is connected to the sixth pin after 10 turns counterclockwise from the seventh pin through the corresponding metallized via; wherein, the routing in the third middle board and the fourth middle board is 9 mil line width PCB routing.

[0017] Specifically, in the power side winding, the second pin is the starting pin, and the routing in the upper top plate goes from the second pin through the corresponding metallized via in a counterclockwise direction for 10 turns and then connects to the first pin in the lower bottom plate; wherein, the routing in the upper top plate and the lower bottom plate is 18mil line width PCB routing.

[0018] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: a multi-layer PCB printed board is adopted, the wiring of the printed board is used as a coil, and a transformer that meets the requirements of intrinsically safe explosion-proof solid insulation and three-terminal isolation is provided.

[0019] 1) Through the stacking design of multi-layer PCB boards, it is easy to meet the solid insulation requirements, three-terminal isolation requirements, and consistency requirements of intrinsic safety and explosion-proof.

[0020] 2) The material cost is low, only printed circuit boards and routing are required. The routing is already included in the printed circuit board, and the only other auxiliary materials are some sealing glue.

[0021] 3) The assembly is simple. Use fast-curing anaerobic adhesive to stick the upper and lower traces together, and use epoxy resin to fix the traces and printed circuit boards.

[0022] 4) Easy to weld, the half-hole design has no extra cost, and the sideband design provided by the manufacturer can easily meet the SMT process requirements of the SMT machine. In summary, it has obvious advantages in terms of material cost, production cost, process cost, product consistency, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0024] Figure 1The schematic diagram of the intrinsically safe planar transformer for an isolated safety barrier of the present invention is shown in FIG.

[0025] Figure 2 It is the wiring distribution diagram of the upper top surface and the lower bottom surface of the present invention;

[0026] Figure 3 is a wiring distribution diagram of the second intermediate board of the present invention;

[0027] Figure 4 A wiring distribution diagram of the first intermediate board of the present invention;

[0028] Figure 5 is a wiring distribution diagram of a fourth intermediate board of the present invention;

[0029] Figure 6 is a wiring distribution diagram of the third intermediate board of the present invention;

[0030] Figure 7 It is a structural schematic diagram of an intrinsically safe planar transformer for an isolated safety barrier of the present invention;

[0031] Figure 8 It is a schematic diagram of the magnetic core assembly and finished product of the present invention. DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0033] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0034] The following is a further detailed description of an intrinsically safe planar transformer for an isolated safety barrier proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0035] Example

[0036] See also Figures 1 to 8The present embodiment provides an intrinsically safe planar transformer for an isolated safety barrier, which mainly includes a PCB board, and a plurality of PCB boards are aligned and stacked in sequence. From top to bottom, they can be named as an upper top board, a middle board, and a lower bottom board. In the present embodiment, there are four middle boards, namely, a first middle board, a second middle board, a third middle board, and a fourth middle board. Preferably, an insulating spacer is interspersed between the adjacent PCB boards. Specifically, see Figure 7 The top layer of this embodiment is the top plate, below which is a spacer insulating plate with a thickness of 0.4mm, followed by a first middle plate with a thickness of 0.2mm, and then below it is a spacer insulating plate with a thickness of 0.1mm, and below that is a second middle plate with a thickness of 0.2mm, the lower surface of the second middle plate is connected to the spacer insulating plate with a thickness of 1mm, and below that is a third middle plate with a thickness of 0.2mm, and a fourth middle plate with a thickness of 0.2mm is arranged below the third middle plate, and the third middle plate and the fourth middle plate are provided with a spacer insulating plate with a thickness of 0.1mm, and the bottom layer of this embodiment is the lower bottom plate, and a spacer insulating plate with a thickness of 1mm is arranged between the lower bottom plate and the fourth middle plate.

[0037] See also Figures 2 to 6 , a number of metallized hole pads are provided at the same position on each PCB board, specifically, including a first pin, a second pin, a third pin, a fourth pin, a fifth pin, a sixth pin, a seventh pin and an eighth pin. The first pin and the second pin are a group, arranged on one side of the PCB board, the third pin, the fourth pin and the fifth pin are a group, arranged on the same side of the first pin, the sixth pin, the seventh pin and the eighth pin are a group, arranged on the opposite side of the first pin, and the above is just an example of the arrangement of each pin but is not limited to this. The above pins of each PCB board are electrically connected one by one, that is, it can be understood that the first pin of each PCB board is connected, and the same applies to the remaining pins.

[0038] See also Figures 2 to 7 , the upper top plate and the lower bottom plate are provided with winding grooves on the outer side, and the middle plate is provided with winding grooves on both sides. Routes are arranged in the winding grooves to form windings. The routing is made of enameled wire or tape material. The distance between the outer routing and the first to fifth pins is not less than 4.2mm, and the distance between the inner routing and the inner board edge is not less than 1mm. Each PCB board is also provided with metallized vias that penetrate the PCB board. Two metallized vias are arranged on the inner side of the winding grooves and are symmetrically arranged on the PCB board. The routing of the upper top plate is electrically connected to the routing in the lower bottom plate through the metallized vias of the upper top plate and the metallized vias of the lower bottom plate in turn, and the routing on the upper and lower sides of the middle plate is electrically connected to each other through its own metallized vias.

[0039] See also Figure 1Specifically, the windings can also be divided into three groups, namely, the power supply side winding, the non-intrinsically safe side winding and the intrinsically safe side winding, that is, the power supply side, the sub-intrinsically safe side and the intrinsically safe side three terminals. This embodiment needs to meet the intrinsically safe explosion-proof and solid insulation requirements. The principle block diagram of the three-terminal isolated planar transformer is as follows Figure 1 The requirements to be achieved are shown in Table 1.

[0040] Table 1

[0041]

[0042]

[0043] The starting and ending points of each winding are different, which can be obtained by referring to Table 2.

[0044] Table 2

[0045] step Starting foot End foot Enameled wire or tape material Number of turns N1 power supply side 2 1 18mil line width PCB trace 10 N2 non-intrinsically safe side 4 3 9mil line width PCB routing 10 N3 non-intrinsically safe side 5 4 9mil line width PCB routing 10 N4 intrinsically safe side 7 6 9mil line width PCB routing 10 N5 intrinsically safe side 8 7 9mil line width PCB routing 10

[0046] See also Figure 2 , the power side winding is obtained by the routing in the upper top plate and the lower bottom plate and the first pin and the second pin connected thereto. Specifically, in the power side winding, the second pin is the starting pin, and the routing in the upper top plate first goes around the second pin for 5 turns in a counterclockwise direction and then is electrically connected to the metallized via of the upper top plate. Then the routing passes through the metallized via of the lower bottom plate, and then goes around for 5 turns in a counterclockwise direction and is connected to the first pin in the lower bottom plate. Among them, the routing in the upper top plate and the lower bottom plate is a 18mil line width PCB routing. In this embodiment, the shortest distance from the seventh pin to the above peripheral PCB routing is 3.4mm.

[0047] See also Figure 3 and Figure 4 , the non-intrinsically safe side winding is obtained by the routing in the first middle plate and the second middle plate and the third pin, the fourth pin and the fifth pin connected thereto. Specifically, the non-intrinsically safe side winding can be divided into two parts. First, the fifth pin is the starting pin. The routing on the lower end face of the second middle plate starts from the fifth pin, first wraps around 5 turns in a counterclockwise direction, and then is electrically connected to the metallized via of the second middle plate. Then, the routing wraps around 5 turns in a counterclockwise direction on the upper end face of the second middle plate and is connected to the fourth pin. Second, the routing on the lower end face of the first middle plate starts from the fourth pin, first wraps around 5 turns in a counterclockwise direction, and then is electrically connected to the metallized via of the first middle plate. Then, the routing wraps around 5 turns in a counterclockwise direction on the upper end face of the first middle plate and is connected to the third pin. Among them, the routing in the first middle plate and the second middle plate is a 9mil line width PCB routing. In this embodiment, the shortest distance from the seventh pin to the above peripheral PCB routing is 3.7mm.

[0048] See also Figure 5 and Figure 6 , the intrinsically safe side winding is obtained by the routing in the third middle plate and the fourth middle plate and the sixth pin, the seventh pin and the eighth pin connected thereto. Specifically, the intrinsically safe side winding can be divided into two parts. First, the eighth pin is the starting pin. The routing on the lower end face of the fourth middle plate starts from the eighth pin, first wraps around 5 turns in the counterclockwise direction, and then is electrically connected to the metallized via of the fourth middle plate. Then, the routing is connected to the seventh pin after wrapping around the upper end face of the fourth middle plate in the counterclockwise direction for 5 turns. Second, the routing on the lower end face of the third middle plate starts from the seventh pin, first wraps around 5 turns in the counterclockwise direction, and then is electrically connected to the metallized via of the third middle plate. Then, the routing is connected to the sixth pin after wrapping around the upper end face of the third middle plate in the counterclockwise direction for 5 turns. Among them, the routing in the third middle plate and the fourth middle plate is a 9mil line width PCB routing. In this embodiment, the shortest distance between the above-mentioned peripheral PCB routing and the third pin is 4.2mm, and the distance between the inner peripheral PCB routing and the inner board edge is 1.1mm.

[0049] See also Figure 8 In this embodiment, the upper and lower magnetic cores are bonded by using fast-curing anaerobic adhesive, and the magnetic core and the printed circuit board are fixed by epoxy resin. The half-hole design can meet the needs of the patch process.

[0050] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. An intrinsically safe planar transformer for an isolated safety barrier, characterized in that: include: A PCB board, wherein the PCB board comprises an upper top board, at least one middle board and a lower bottom board stacked in sequence from top to bottom; A plurality of metallized hole pads are provided on each of the PCB boards, and the metallized hole pads on adjacent PCB boards are electrically connected one by one; The upper top plate and the lower bottom plate are provided with winding grooves on one side facing outward, and the middle plate is provided with winding grooves on both sides, and the winding grooves are provided with wiring to form windings; The PCB boards are all provided with metallized vias penetrating the PCB boards, the wiring of the upper top board is electrically connected to the wiring in the lower bottom board through the metallized vias of the upper top board and the lower bottom board in sequence, and the wiring on the upper and lower surfaces of the middle board is electrically connected to each other through the corresponding metallized vias; The plurality of metallized hole pads include a first pin, a second pin, a third pin, a fourth pin, a fifth pin, a sixth pin, a seventh pin and an eighth pin, and the above pins of the PCB boards are electrically connected one by one; The windings include a power supply side winding, a non-intrinsically safe side winding and an intrinsically safe side winding; The power supply side winding is obtained by the wiring in the upper top plate and the lower bottom plate and the first pin and the second pin connected thereto; The non-intrinsically safe side winding is obtained by the wiring in the middle board and the third pin, the fourth pin and the fifth pin connected thereto; The intrinsically safe side winding is obtained by the wiring in the middle board and the sixth pin, the seventh pin and the eighth pin connected thereto.

2. The intrinsically safe planar transformer for an isolated safety barrier according to claim 1, characterized in that: A spacing insulating plate is also arranged between each of the PCB boards, and the spacing insulating plates are sequentially inserted and arranged in adjacent PCB boards.

3. The intrinsically safe planar transformer for an isolated safety barrier according to claim 1, characterized in that: The middle plate comprises a first middle plate, a second middle plate, a third middle plate and a fourth middle plate arranged from top to bottom; The third pin, the wiring of the first middle board, the fourth pin, the wiring of the second middle board and the fifth pin which are electrically connected in sequence constitute the non-intrinsically safe side winding; The sixth pin, the wiring of the third middle board, the seventh pin, the wiring of the fourth middle board and the eighth pin which are electrically connected in sequence constitute the intrinsically safe side winding.

4. The intrinsically safe planar transformer for an isolated safety barrier according to claim 1, characterized in that: The second pin, the wiring of the upper top plate, the wiring of the lower bottom plate and the first pin which are electrically connected in sequence constitute the power supply side winding.

5. The intrinsically safe planar transformer for an isolated safety barrier according to claim 3, characterized in that: In the non-intrinsically safe side winding, the fifth pin is the starting pin, and the routing in the second middle board is connected to the fourth pin after circling 10 turns counterclockwise from the fifth pin through the corresponding metallized via hole; the routing in the first middle board is connected to the third pin after circling 10 turns counterclockwise from the fourth pin through the corresponding metallized via hole; wherein, the routing in the first middle board and the second middle board is a 9 mil line width PCB routing.

6. The intrinsically safe planar transformer for an isolated safety barrier according to claim 3, characterized in that: In the intrinsically safe side winding, the eighth pin is the starting pin, and the routing in the fourth middle board is connected to the seventh pin after circling 10 turns counterclockwise from the eighth pin through the corresponding metallized via hole; the routing in the third middle board is connected to the sixth pin after circling 10 turns counterclockwise from the seventh pin through the corresponding metallized via hole; wherein, the routing in the third middle board and the fourth middle board is 9 mil line width PCB routing.

7. The intrinsically safe planar transformer for an isolated safety barrier according to claim 4, characterized in that: In the power side winding, the second pin is the starting pin, and the routing in the upper top plate is connected to the first pin in the lower bottom plate after 10 turns counterclockwise from the second pin through the corresponding metallized via; wherein the routing in the upper top plate and the lower bottom plate is 18 mil line width PCB routing.

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