JP2006013094A - Transformer structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transformer structure capable of controlling internal temperature rise. <P>SOLUTION: Flux passing through a core 5 interlinks with a secondary winding 11 to induce a voltage on the secondary of a transformer, and flux not interlinking with the secondary winding 11, i.e. leakage flux, forms a leakage inductance. Since the primary winding 10 and the secondary winding 11 are arranged alternately and wound directly around the core 5 in the inventive transformer structure, magnetic coupling between the primary winding 10 and the secondary winding 11 is improved and leakage inductance can be controlled. The secondary winding 11 extending to the outside of the transformer functions as heat dissipation fins to dissipate heat efficiently thus controlling temperature rise in the transformer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transformer suitable for, for example, a large-capacity switching power supply device, and more particularly to a transformer structure using a wire as a primary winding and a plate-like member as a secondary winding.

  Since a large current flows in the secondary side of the transformer used in the large-capacity switching power supply device, as disclosed in Patent Document 1, a metal plate is used for the secondary winding. Normally, linear wires are used for both the primary and secondary windings in the transformer. In Patent Document 1, however, the resistance value of the secondary winding through which a large current flows is reduced. A large area metal plate winding is used.

7 and 8 show such a conventional transformer structure. The plastic bobbin 1 includes a cylindrical winding frame portion 2 having hooks at both ends, and support portions 3 and 3 that are provided at the lower portion of the flange and support the winding frame portion 2. The core 5 is formed of an iron core or a ferrite core, and has an E-shaped core 6 having an E-shaped section having a central main leg 6a and a pair of side legs 6b, 6b located on both sides, and an I-shaped section. And a core 7. A primary winding 10 made of a three-layer insulated wire and a secondary winding 11 made of copper foil are sequentially wound on the winding frame 2 in layers so as to form a so-called sandwich winding. The part 6a is inserted through the inside. FIG. 8 is a longitudinal sectional view as seen from the longitudinal direction of the winding frame part 2, and is wound a plurality of times (multiple turns) so that the primary winding 10 forms a layer along the outer periphery of the winding frame part 2. Then, the secondary winding 11 is wound two turns through the insulating sheet 12 from above, the surface of the secondary winding 11 wound outside is covered with the insulating sheet 12, and the primary winding 10 is further layered A plurality of turns are wound so as to form the last, and finally, the outermost layer surface of the primary winding 10 is sandwiched with the insulating sheet 12 covered. An end portion 10a of the primary winding 10 is tangled and soldered to a plurality of connection pins 4 provided on the support portion 3, while the end portion of the secondary winding 11 is connected to the secondary portion. One end of the side lead wire 12 is soldered and connected to the outside. When mounting the transformer on a printed circuit board or output board (not shown), the connection pin 4 is inserted into the plated through hole and then soldered, and the other end of the secondary lead wire 12 is screwed with a screw or the like. It will be connected by doing.
Japanese Patent Laid-Open No. 2003-151834

  However, in the conventional transformer structure, since the primary winding 10 and the secondary winding 11 are wound around the plastic bobbin 1, the heat generated in these windings is accumulated, There was a problem of high temperatures. Since the bobbin 1 is made of plastic, heat dissipation is poor, and heat inside the transformer cannot be efficiently released. When the temperature inside the transformer becomes high, the bobbin 1, the coating of the primary winding 10, the insulating sheet 12, etc. may be deformed or melted. Therefore, in the conventional transformer, these members are dealt with by using a high heat-resistant material.

  Further, there is a problem that the leakage inductance formed by the leakage magnetic flux decreases the conversion efficiency and increases the switching noise. This is because there is a gap between the primary winding 10 and the secondary winding 11 and the core 5 (there is a distance), and the magnetic coupling between the primary winding 10 and the secondary winding 11 is good. This is due to the absence.

  In view of the above problems, it is a first object of the present invention to provide a transformer structure with improved magnetic coupling between a primary winding and a secondary winding.

  A second object is to provide a transformer structure capable of suppressing an internal temperature rise.

  The transformer structure according to claim 1 of the present invention includes a core, a primary winding made of a winding body wound around the core, and a secondary winding made of a metal plate material having a single turn structure. The plate material is provided with a through hole for inserting and holding the core, and a pair of terminal portions are formed across the through hole, and the winding body and the metal plate material are alternately arranged with respect to the core. It is configured to be placed.

  In this way, the secondary winding does not wind around the core, but is configured to insert and hold the core in the through hole provided in the metal plate material, and thus a simple transformer structure that does not require a bobbin, Easy to manufacture. In addition, it is possible to directly connect to the substrate using the terminal portion. Further, the winding body constituting the primary winding and the metal plate material constituting the secondary winding are directly wound around the core, and are alternately arranged with respect to the core, whereby the primary winding and 2 Magnetic coupling with the next winding is improved, and leakage inductance can be reduced.

  In a transformer structure according to a second aspect of the present invention, a heat radiating portion projecting outside the core is provided integrally with the metal plate.

  The present invention has been made by paying attention to the fact that the metal plate material constituting the secondary winding used in the transformer for large current output is excellent in heat dissipation. By providing it integrally with the plate material, the metal plate material itself can have the role of a heat radiating fin, that is, a cooling effect, so that the temperature rise inside the transformer can be suppressed. In addition, by alternately arranging the winding body constituting the primary winding and the metal plate material constituting the secondary winding, the cooling effect of the secondary winding is distributed throughout the transformer, so that the inside of the transformer A structure in which a hot spot is difficult to be formed can be obtained.

  In the transformer structure according to the third aspect of the present invention, the metal plate member is provided with a connection portion to which a heat radiator can be connected.

  If it does in this way, since the thermal radiation body connected to the metal plate material which comprises a secondary winding acts as a thermal radiation fin, the temperature rise inside a transformer can be suppressed. Since the radiator is provided separately from the metal plate material, the shape and material of the radiator can be freely selected according to the specifications of the transformer and the user needs. In addition, by alternately arranging the winding body constituting the primary winding and the metal plate material constituting the secondary winding, the cooling effect of the secondary winding is distributed throughout the transformer, so that the inside of the transformer A structure in which a hot spot is difficult to be formed can be obtained.

  According to the first aspect of the present invention, since the leakage inductance is reduced, the conversion efficiency can be improved and the switching noise can be reduced. In addition, the number of components can be reduced, and mounting on the board becomes easy.

  According to the second aspect of the present invention, in addition to the effect of the first aspect, the temperature rise inside the transformer can be effectively suppressed.

  According to the third aspect of the present invention, in addition to the effect of the first aspect, the temperature rise inside the transformer can be effectively suppressed, and the cooling effect can be optimized according to the transformer specifications and user needs. Can do.

  Hereinafter, preferred embodiments of a transformer structure according to the present invention will be described together with manufacturing methods with reference to the accompanying drawings. Note that, in these embodiments, the same portions as those in the conventional example are denoted by the same reference numerals, and description of common portions will be omitted as much as possible.

  FIG. 1 is a perspective view showing a transformer structure in this embodiment, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. The core 5 is made of a high magnetic permeability member such as an iron core or a ferrite core, for example, and has an E-shaped core 6 with an E-shaped cross section having a central main leg 6a and a pair of side legs 6b, 6b located on both sides. The cross section is composed of an I-shaped core 7 having an I-shaped cross section. Of course, the core 5 is not limited to the EI core, and various shapes such as an ET core and an EE core can be used. The primary winding 10 is formed of a three-layer insulated wire similar to the conventional one, while the secondary winding 11 is formed of a flat metal plate such as a copper plate. An insulating sheet 12 is provided to insulate the primary winding 10 and the secondary winding 11 or between the transformer main body and a mounting target (not shown).

  The secondary winding 11 will be described in detail with reference to FIG. The secondary winding 11 includes a beam portion 22 as a heat radiating portion, a pair of holding portions 23 and 23 for holding the main leg portion 6a and the side leg portion 6b of the E-shaped core 6 at predetermined positions, A pair of column portions 21 and 21 for connecting and supporting the holding portions 23 and 23 respectively, and a pair of terminal portions 24 for taking out current from the secondary winding 11 formed at the lower end portions of the column portions 21 and 21, respectively. Consists of 24 and constitutes one turn which is the minimum number of windings. One pillar part 21, holding part 23, terminal part 24 and the other pillar part 21, holding part 23, terminal part 24 are provided symmetrically across a through hole 20 formed in the center of the secondary winding 11. The secondary winding 11 as a whole has a symmetrical shape with respect to the central axis in the vertical direction passing through the through hole 20. Cutout portions 25 and 25 are formed at the center of both side portions of the secondary winding 11, and the beam portion 22 and the holding portion 23 are projected to the outside of the E-shaped core 6. In this way, by increasing the surface area of the secondary winding 11, the heat inside the transformer generated by the copper loss of the primary winding 10 and the secondary winding 11 can be radiated efficiently, and the radiating fin The cooling effect can be enhanced. Therefore, the holding part 23 also acts as a heat radiating part in the same manner as the beam part 22. The holding portion 23 also protrudes inward so that the through hole 20 is constricted.

  As a modification of the secondary winding 11, there are those shown in FIGS. In the modification of FIG. 4, a rectangular plate-like heat sink 31 as a heat sink excellent in heat dissipation is formed separately from the secondary winding 11 shown in FIG. 2. The beam portion 22 and the heat radiating plate 31 of the secondary winding 11 are respectively provided with screw taps 30 and 32 as connecting portions, and the heat radiating plate 31 is screwed to the secondary winding 11 with a screw 33 to The cooling effect of the next winding 11 is enhanced. In addition, it is preferable that the heat radiating plate 31 is formed of an insulating member having excellent heat radiating properties because no eddy current is generated. On the other hand, in the modification of FIG. 5, a secondary connection winding 36 is configured in which the beam portions 22 of the two secondary windings 11 are connected to each other by a bridging portion 35. The secondary connection winding 36 has the U-shaped cross section because the ends of the two secondary windings 11 are connected by the bridging portion 35, and the primary winding 10 has two secondary windings. The magnetic coupling can be improved by sandwiching with the wire 11. In addition, since the bridging portion 35 acts as a heat radiator, the heat dissipation is improved and the cooling effect of the secondary winding 11 can be enhanced.

  In any of the secondary windings 11 (or the secondary connection winding 36) shown in FIGS. 2, 4, and 5, the magnetic flux interlinking with the secondary winding 11, that is, the magnetic flux passing through the through hole 20 changes. As a result, a voltage is induced, and a current associated therewith is taken out from the terminal portions 24 and 24. Therefore, the main leg portion 6 a of the E-shaped core 6 is inserted into the through hole 20. At that time, the side legs 6b and 6b of the E-shaped core 6 are inserted into the notches 25 and 25, respectively, and are surrounded by the beam part 22, the column part 21 and the holding part 23 together with the main leg part 6a. Held in place. That is, the main leg portion 6a is retained by the constriction of the through hole 20 formed by the holding portion 23 projecting inward, so that the main leg portion 6a is held in the through hole 20, while the side leg portion 6b is Since it is locked from above and below by the beam portion 22 and the holding portion 23 protruding in the vertical direction, the beam portion 22 is held in the notch portion 25. The through hole 20 and the cutout portion 25 are preferably sized to fit the main leg portion 6a and the side leg portion 6b, respectively, in order to fix the through hole 20 and the cutout portion 25 so as not to rattle due to vibrations generated in the transformer.

  The terminal portion 24 is preferably solder-plated so that it can be directly soldered to a printed circuit board or an output board (not shown). The shape of the terminal portion 24 is, for example, a pin shape that can be inserted into a plated through hole or a surface mountable. What is necessary is just to set it as various shapes according to mounting aspects, such as the SMD shape formed by bending. In addition, a dedicated socket may be manufactured and mounted on the substrate via the dedicated socket.

  Next, a method for manufacturing a transformer having a transformer structure in the present embodiment will be described with reference to FIGS. First, the secondary winding 11 is formed by punching the through-hole 20, the notches 25, 25, and the like from one rectangular copper plate by, for example, press working. The main leg 6a of the E-shaped core 6 and the through hole 20 of the secondary winding 11 are aligned with the side leg 6b and the notch 25, respectively, and the main leg 6a and the side of the secondary winding 11 are aligned. By inserting the leg 6b, the secondary winding 11 is wound around the main leg 6a. After the insulating sheet 12 is mounted on the main leg 6a, the primary winding 10 is wound around the main leg 6a. The primary winding 10 is wound around a jig in advance by a plurality of turns so as to obtain a desired turns ratio, and the winding state is maintained with, for example, an adhesive. Similarly, the E-core 6 is wound so that the primary winding 10 and the secondary winding 11 are alternately arranged. When all the windings have been wound, the I-shaped core 7 is connected to the E-shaped core 6 to form the core 5. In the transformer structure, the secondary winding 11 is configured not to be wound around the core 5 but to be held by inserting the core 5 through the through hole 20, so that the bobbin 2 is not required, Easy to manufacture. As in the past (see FIGS. 7 and 8), the sandwich winding in which the primary winding 10 and the secondary winding 11 made of a plate-shaped metal plate are stacked on the bobbin 2 and wound is complicated and manufactured. However, in the transformer structure in this embodiment, the primary winding 10 and the secondary winding 11 are simply mounted on the main leg portion 6a of the E-shaped core 6 so that the manufacturing is greatly facilitated. become.

  As the wiring of the transformer, the primary windings 10 are connected in series, and the secondary windings 11 are connected in parallel. By wiring in this way, a large current can be taken out while suppressing the voltage across the secondary side. In addition, an output means (not shown) may be connected to each secondary winding 11 to obtain a multi-channel output.

  Hereinafter, the operation of the transformer structure in this embodiment will be described.

  When a current is intermittently passed through the primary winding 10, a magnetic flux passing through the core 5 having a high magnetic permeability is generated and changed. When the magnetic flux passing through the core 5 is linked to the secondary winding 11, a voltage is induced on the secondary winding 11, that is, the secondary side of the transformer. The magnetic flux that is not interlinked with the secondary winding 11, that is, the leakage magnetic flux forms a leakage inductance, but in the transformer structure in this embodiment, the primary winding 10 and the secondary winding 11 are alternately arranged. In addition, since it is directly wound around the core 5, the magnetic coupling between the primary winding 10 and the secondary winding 11 is improved, and leakage inductance can be suppressed. Therefore, the conversion efficiency can be improved and the switching noise caused by the leakage inductance can be reduced. When current flows through the primary winding 10 and the secondary winding 11, heat is generated due to copper loss, but the secondary winding 11 that protrudes to the outside of the transformer acts as a radiating fin, so that the heat is efficient. It is well radiated and can suppress the temperature rise inside the transformer. In particular, in this embodiment, the primary windings 10 and the secondary windings 11 are alternately arranged so that the cooling effect of the secondary windings 11 is distributed throughout the transformer. It has a structure that is difficult to complete.

  Further, since the secondary winding 11 can hold the core 5 through the through-hole 20, it does not require a bobbin as in the prior art, and is directly connected to the printed circuit board using the terminal portion 24. It is also possible. Therefore, the number of parts can be reduced, and mounting on a printed circuit board becomes easy.

  As described above, the present embodiment includes the core 5, the primary winding 10 formed of the winding body wound around the core 5, and the secondary winding 11 formed of the metal plate material having a single turn structure, The metal plate is provided with a through hole 20 for inserting and holding the core 5, and a pair of terminal portions 24, 24 are formed across the through hole 20, and the winding body and the metal are formed with respect to the core 5. It is comprised so that a board | plate material may be arrange | positioned alternately.

  In this way, the secondary winding 11 is not wound around the core 5, but is configured to be inserted and held in the through hole 20 provided in the metal plate, so that the bobbin 2 is not required. The transformer structure is easy to manufacture. In addition, it is possible to directly connect to the substrate using the terminal portion 24. Further, the winding body constituting the primary winding 10 and the metal plate material constituting the secondary winding 11 are directly wound around the core 5 and are alternately arranged with respect to the core 5 to thereby make the primary winding. The magnetic coupling between the winding 10 and the secondary winding 11 is improved, and the leakage inductance can be reduced. As described above, since the leakage inductance is reduced, conversion efficiency can be improved and switching noise can be reduced. In addition, the number of components can be reduced, and mounting on the board becomes easy.

  Further, in the present embodiment, the beam portion 22 and the holding portion 23 as heat radiating portions projecting outside the core 5 are integrally provided on the metal plate material constituting the secondary winding 11.

  The present invention has been made by paying attention to the fact that the metal plate material constituting the secondary winding 11 used in the transformer for outputting a large current is excellent in heat dissipation. By providing the metal plate member 22 and the holding part 23 integrally with the metal plate material, the metal plate material itself can have a role of a heat radiating fin, that is, a cooling effect, so that an increase in temperature inside the transformer can be suppressed. Further, by alternately arranging the winding body constituting the primary winding 10 and the metal plate material constituting the secondary winding 11, the cooling effect of the secondary winding 11 is distributed throughout the transformer. A structure in which a hot spot is difficult to be formed inside the transformer can be obtained. Therefore, the temperature rise inside the transformer can be effectively suppressed.

  Furthermore, in this embodiment, a screw tap 30 as a connecting portion to which a heat radiating plate 31 as a heat radiating member can be connected is provided on the metal plate material constituting the secondary winding 11.

  If it does in this way, since the heat sink connected to the metal plate material which comprises the secondary winding 11 acts as a heat radiating fin, the temperature rise inside a transformer can be suppressed. Since the heat radiating plate 31 is provided separately from the metal plate material, the shape and material of the heat radiating plate 31 can be freely selected according to the specifications of the transformer and the user needs. Further, by alternately arranging the winding body constituting the primary winding 10 and the metal plate material constituting the secondary winding 11, the cooling effect of the secondary winding 11 is distributed throughout the transformer. A structure in which a hot spot is difficult to be formed inside the transformer can be obtained. Therefore, the temperature rise inside the transformer can be effectively suppressed, and the cooling effect can be optimized according to the specifications of the transformer and user needs.

  In addition, this invention is not limited to the said Example, It can change in the range which does not deviate from the meaning of this invention. The secondary winding 11 is formed by making each secondary winding 11 independent so as to have one turn which is the minimum number of turns, but the terminal portions 24 are connected in series to form a plurality of turns. It may be. In addition, the constituent member of the secondary winding 11 is not limited to a metal plate, and may be any material as long as it has high conductivity, strength, and heat dissipation.

  The transformer structure in the present invention can be used for a transformer which is a main component of a power supply device, and can also be used for various transformers such as a current transformer.

1 is a perspective view of a transformer having a transformer structure in a first embodiment of the present invention. It is AA 'sectional drawing of a transformer same as the above. It is a front view of the secondary winding which comprises a transformer same as the above. It is an exploded perspective view showing the 1st modification of the secondary winding which constitutes a transformer same as the above. It is a perspective view which shows the 2nd modification of the secondary winding which comprises a transformer same as the above. It is a principal part exploded perspective view of a transformer same as the above. It is a perspective view of a transformer having a transformer structure in a conventional example. It is the longitudinal cross-sectional view seen from the longitudinal direction of the transformer same as the above.

Explanation of symbols

5 cores
10 Primary winding (winding body)
11 Secondary winding (metal plate material)
20 Through hole
22 Beam (heat radiation part)
23 Holding part (heat radiation part)
24 Terminal section
30 Screw tap (connection)
31 Heat sink (heat sink)

Claims (3)

A core, a primary winding made of a winding body wound around the core, and a secondary winding made of a metal plate material having a single turn structure, the metal plate material being inserted and held by the core A transformer structure characterized in that a through hole is provided, a pair of terminal portions are formed across the through hole, and the winding body and the metal plate material are alternately arranged with respect to the core. The transformer structure according to claim 1, wherein a heat radiating portion projecting outside the core is provided integrally with the metal plate. The transformer structure according to claim 1, wherein the metal plate member is provided with a connection portion to which a radiator can be connected.

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