JP5288109B2 - Coil, transformer, switching power supply - Google Patents

Description

  The present invention relates to a coil wound along a plane, and a transformer element and a switching power supply device including such a coil.

  Conventionally, various DC-DC converters have been proposed as switching power supply devices and put into practical use. Many of them adopted a method in which the DC input voltage was switched by the switching operation of the switching circuit connected to the primary coil of the power conversion transformer (transformer element) and the switching output was taken out to the secondary coil of the power conversion transformer. Is. With the switching operation of the switching circuit, the voltage appearing in the secondary coil is rectified by the rectifier circuit, then converted into direct current by the smoothing circuit and output.

  Recently, there has been a demand for downsizing of such a switching power supply apparatus, and accordingly, the transformer elements have been made smaller and thinner. For this reason, a thin-film (or thin-plate) coil provided on a resin substrate is employed as the primary coil and the secondary coil (see Patent Document 1).

As related to the coil as described above, Patent Documents 2 and 3 disclose an inductor in which a conductive pattern is provided on an insulating substrate.
Japanese Patent Laid-Open No. 9-326316 JP 2000-232019 A JP-A-8-107018

  By the way, when a higher transformation ratio is required, it is necessary to increase the ratio (turn ratio) between the number of turns of the primary side coil and the number of turns of the secondary side coil. The number of turns must be increased. However, if the number of turns of the coil is increased while increasing the cross-sectional area of the coil in a limited formation area, the width of each turn of the coil is inevitably narrowed. In such a case, the thin film (or thin plate) coil provided on the resin substrate as described above is likely to be warped or distorted due to a stress accompanying a temperature change during manufacture or use.

  Specifically, when placed in a high temperature environment, the coil made of metal mainly extends in the winding direction. FIG. 10A is a schematic view of a coil 130 provided on a resin substrate (not shown) as viewed from above, and FIG. 10B is a cross-sectional view taken along line XIB-XIB in FIG. FIG. Further, FIG. 10C shows a state in which the section from the position P101 to the position P102 in the winding bodies 131T1 to 131T3 constituting the coil 130 shown in FIG. Corresponds to a normal temperature before driving, and a broken line corresponds to a high temperature during driving (after). In FIG. 10C, the horizontal direction of the paper surface along the winding direction R corresponds to the distance along the coil 130 from the position P101 to the position P102 on the surface of the resin substrate, and the vertical direction of the paper surface is orthogonal to the surface of the resin substrate. This corresponds to the displacement of the coil 130 in the direction (thickness direction). When such a coil 130 attempts to thermally expand in its winding direction, the coil 130 is in close contact with the resin substrate and cannot be displaced alone. Therefore, when there is a large difference between the coefficient of thermal expansion of the coil 130 and the coefficient of thermal expansion of the resin substrate, stress is generated in the vicinity of the bonding interface between the substrate and the coil 130. In particular, when the number of windings of the coil 130 is increased so that the widths of the winding bodies 131T1 to 131T3 of the coil 130 are reduced and the total length is increased, the stress along the winding direction R in a high temperature environment is significantly increased. . In order to relieve such stress, the coil 130 is moved together with the resin substrate from a predetermined position parallel to the substrate surface indicated by a solid line to a position indicated by a broken line as shown in FIGS. 10 (B) and 10 (C). It will be displaced. As a result, warpage is generated in the entire coil substrate in which the resin substrate and the coil are integrated.

  Such warpage of the coil substrate becomes a factor that hinders downsizing of a transformer element and the like on which the coil substrate is mounted. In this type of coil substrate, a cooling substrate with high thermal conductivity such as aluminum may be brought into contact with the back surface of the resin substrate on which the coil is provided to cool the coil. If warpage occurs, a gap is generated between the resin substrate and the cooling substrate, and cooling efficiency is lowered.

  The present invention has been made in view of such a problem, and a first object of the invention is to provide a coil that has a larger number of turns and is thin, and is less likely to be warped or distorted. A second object of the present invention is to provide a transformer element suitable for obtaining a larger transformation ratio and a switching power supply device including the transformer element while having a compact configuration.

The coil of the present invention includes a plurality of conductor patterns and includes a pair of conductor forming layers facing each other with an insulating layer interposed therebetween. Here, a plurality of conductor patterns in one conductor forming layer and a plurality of conductor patterns in the other conductor forming layer are alternately connected by a plurality of connecting portions penetrating the insulating layer to be integrated, and as a whole, a set of conductors It is wound along the forming layer. In each of the pair of conductor forming layers, the plurality of conductor patterns are wound in the same direction so as to be adjacent to each other, and the ends on the winding center side and the ends on the winding outer peripheral side in the plurality of conductor patterns The parts are connected to each other. Each of the plurality of conductor patterns has a winding amount of less than one turn, and one conductor pattern in one of the conductor formation layers, and one conductor pattern in the other conductor formation layer connected thereto 1 or more times , and includes a portion where the line width gradually increases from the winding center side toward the winding outer periphery side.

  The transformer element of the present invention includes a magnetic core, and a primary side coil and a secondary side coil that are wound around the magnetic core, and as at least one of the primary side coil and the secondary side coil, The coil of the present invention is used. Furthermore, the switching power supply device of the present invention includes a switching circuit that switches a DC input voltage to generate an input AC voltage, a primary side coil that winds around the magnetic core, and a secondary side coil. And a rectifying circuit that generates a DC output voltage by performing a rectifying operation of the output AC voltage connected in parallel to the secondary side of the transformer element. The coil of the present invention is used as at least one of the primary side coil and the secondary side coil.

  In the coil of the present invention, a plurality of conductor patterns provided in each of the one conductor formation layer and a plurality of conductor patterns provided in each of the other conductor formation layers are alternately connected by a plurality of connecting portions, Since it is wound in an integrated manner, even when heated, it is a stress that tends to expand along the entire winding direction compared to a single continuous coil wound only in one conductor forming layer. Is reduced. This is because the distortion of each of the conductor patterns divided into a plurality is difficult to be transmitted to other conductor patterns.

  In the coil of the present invention, in each of the pair of conductor forming layers, the plurality of conductor patterns are wound in the same direction so as to be adjacent to each other, the ends on the winding center side in the plurality of conductor patterns and the winding outer peripheral side It is preferable that the ends of the two are connected to each other. By doing so, the coil is divided by a relatively short section, and the stress component that tends to expand along the winding direction is difficult to accumulate in the winding direction, and the ratio of the area occupied by the conductor in the predetermined region, that is, This is advantageous in improving the line area ratio and the total number of turns (or the amount of turns). Further, each of the plurality of conductor patterns has a winding amount of less than one turn, and one conductor pattern in one conductor formation layer and one conductor pattern in the other conductor formation layer connected thereto When it is wound more than once, it is more advantageous to improve the line area ratio and the total number of turns (or the amount of turns) while effectively suppressing the warpage and distortion as a whole.

  In the coil of the present invention, the winding amount of the conductor pattern in one conductor formation layer may be different from the winding amount of the conductor pattern in the other conductor formation layer. Moreover, it is preferable that the plurality of connection portions are evenly arranged along a set of conductor formation layers. This is because warpage and distortion as a whole are reduced more uniformly.

According to the coil of the present invention, a plurality of conductor patterns including a portion in which the line width gradually increases from the winding center side to the winding outer periphery side provided in each of the set of conductor forming layers includes a plurality of connection portions. As a whole, they are wound together along a set of conductor forming layers, so that when heated, the stress that tends to expand along the winding direction as a whole is reduced. Can do. Therefore, as compared with the case of winding only with one conductor forming layer, it is possible to further increase the number of turns and reduce the thickness while suppressing the occurrence of warping and distortion. Further, in each conductor forming layer, a plurality of conductor patterns are wound in the same direction so as to be adjacent to each other, and the ends on the winding center side and the ends on the winding outer peripheral side are connected to each other. Therefore, the stress generated between the insulating layer and the conductor pattern due to thermal expansion can be divided in a short section, and the stress can be more effectively prevented from accumulating in the winding direction. Furthermore, both the line product ratio and the number of turns (or the amount of turns) as a whole can be improved. Further, each of the plurality of conductor patterns has a winding amount of less than one turn, and one conductor pattern in one conductor formation layer and one conductor pattern in the other conductor formation layer connected thereto Therefore, the linear product ratio and the overall number of turns can be improved while more effectively suppressing the warpage and distortion as a whole.

  According to the transformer element and the switching power supply device of the present invention, since the coil of the present invention is provided, further downsizing can be realized while improving the transformation ratio.

  Hereinafter, the best mode for carrying out the present invention (hereinafter simply referred to as an embodiment) will be described in detail with reference to the drawings.

  FIG. 1 shows a circuit configuration of a switching power supply device as an embodiment of the present invention. This switching power supply device functions as a DC-DC converter that converts a high-voltage DC input voltage Vin supplied from the high-voltage battery 10 into a lower DC output voltage Vout and supplies the voltage to a low-voltage battery (not shown) to drive the load 6. Is. The transformer element according to the present embodiment will also be described below.

  This switching power supply device includes a switching circuit 1 and an input smoothing capacitor 2 provided between a primary side high voltage line L1H and a primary side low voltage line L1L, a primary side coil 31, and secondary side coils 32A and 32B. And a transformer 3 as a transformer element. A DC input voltage Vin output from the high voltage battery 10 is applied between the input terminal T1 of the primary high voltage line L1H and the input terminal T2 of the primary low voltage line L1L. The switching power supply device further includes a rectifier circuit 4 provided on the secondary side of the transformer 3 and a smoothing circuit 5 connected to the rectifier circuit 4.

  The switching circuit 1 has a full-bridge circuit configuration including four switching elements S1 to S4. Specifically, one ends of the switching elements S1 and S2 are connected to each other, and one ends of the switching elements S3 and S4 are connected to each other. Further, the other ends of the switching elements S1 and S3 are connected to each other and the other ends of the switching elements S2 and S4 are connected to each other, and these other ends are connected to the input terminals T1 and T2, respectively. With such a configuration, the switching circuit 1 converts the DC input voltage Vin applied between the input terminals T1 and T2 into an input AC voltage in accordance with a drive signal supplied from a drive circuit (not shown). . In addition, as these switching elements, switch elements, such as a field effect transistor (MOS-FET; Metal Oxide Semiconductor-Field Effect Transistor) and IGBT (Insulated Gate Bipolor Transistor), are used, for example.

  The input smoothing capacitor 2 is for smoothing the DC input voltage Vin input from the input terminals T1 and T2.

  The pair of secondary coils 32A and 32B of the transformer 3 are connected to each other at the connection portion C, and the connection portion C is led to the output terminal T3 via the output line LO. That is, this switching power supply device is of a center tap type. The transformer 3 transforms the input AC voltage generated by the switching circuit 1 and outputs output AC voltages that are 180 degrees out of phase with each other from the end portions A and B of the pair of secondary coils 32A and 32B. It has become. In this case, the transformation ratio is determined by the turn ratio between the primary coil 31 and the secondary coils 32A and 32B.

  The rectifier circuit 4 is a single-phase full-wave rectifier type composed of a pair of rectifier diodes 4A and 4B. The cathode of the rectifier diode 4A is connected to the end A of the secondary coil 32A of the transformer 3, and the cathode of the rectifier diode 4B is connected to the end B of the secondary coil 32B of the transformer 3. The anodes of these rectifier diodes 4A and 4B are connected to each other and connected to the ground line LG. That is, the rectifier circuit 4 has a center tap type anode common connection configuration, and each half wave period of the output AC voltage from the transformer 3 is individually rectified by the rectifier diodes 4A and 4B to generate a DC voltage. To get.

  The smoothing circuit 5 includes a choke coil 51 and an output smoothing capacitor 52. The choke coil 51 is inserted and arranged in the output line LO, one end of which is connected to the connection portion C, and the other end is connected to the output terminal T3 of the output line LO. The choke coil 51 has a structure in which a wiring made of a highly conductive material such as copper (Cu) or aluminum (Al) is wound around a magnetic core made of a magnetic material such as ferrite. The output smoothing capacitor 52 is connected between the output line LO (specifically, the other end of the choke coil 51) and the ground line LG. An output terminal T4 is provided at the end of the ground line LG. With such a configuration, the smoothing circuit 5 generates the DC output voltage Vout by smoothing the DC voltage rectified by the rectifying circuit 4, and supplies this to the low voltage battery (not shown) from the output terminals T3 and T4. It has become.

  Next, the transformer 3 will be described in more detail with reference to FIGS.

  FIG. 2 is a perspective view showing a main part configuration of the transformer 3, and FIG. 3 is an exploded perspective view thereof. Further, FIG. 4 is an exploded perspective view showing the configuration of only the primary side coil 31 and the secondary side coils 32A and 32B, and FIGS. 5 (A) and 5 (B) constitute the primary side coil 31. FIG. FIG. 5 shows the planar configurations of the conductor pattern groups 34 and 35 (described later) viewed from the direction of the arrow V shown in FIG.

  As shown in FIGS. 2 and 3, the transformer 3 has an upper core 30A and a lower core 30B in addition to the primary coil 31 and the secondary coils 32A and 32B. The upper core 30A is called a so-called E-type core, and is provided with projections 301 to 303 at both ends and the center of a flat plate member made of a magnetic material such as ferrite. On the other hand, the lower core 30B is a flat plate member made of a magnetic material such as ferrite. The lower core 30 </ b> B is in contact with the protrusions 301 to 303 and is disposed to face the upper core 30 </ b> A so as to secure a space between the protrusion 301 at the center and the protrusions 302 and 303 at both ends.

  The primary coil 31 includes an insulating substrate 33 made of a resin such as epoxy and provided with an opening 33K, and a pair of conductor forming layers 34 and 35 facing each other with the substrate 33 interposed therebetween. The conductor formation layers 34 and 35 are wound around the opening 33K in the same direction so that the plurality of conductor patterns 341 to 344 and 351 to 354 are adjacent to each other with a predetermined gap therebetween. In the conductor formation layer 34, an insulating resist (not shown) is provided so as to fill the gaps between the conductor patterns 341 to 344 and cover the conductor patterns 341 to 344. The same applies to the conductor forming layer 35. The primary coil 31 is disposed such that the opening 33K of the substrate 33 is penetrated by the protrusion 301 of the upper core 30A. For this reason, the conductor patterns 341 to 344 and 351 to 354 in the conductor forming layers 34 and 35 are wound around the protrusion 301.

  When viewed from above (in the direction of the arrow V shown in FIG. 4), each of the conductor patterns 341 to 344 in the conductor forming layer 34 is wound from the winding outer peripheral side as shown in FIG. Winding clockwise toward the center. On the other hand, each of the conductor patterns 351 to 354 in the conductor forming layer 35 is wound counterclockwise from the winding outer periphery side toward the winding center side as shown in FIG. The conductor patterns 341 to 344 and the conductor patterns 351 to 354 are integrated by connecting the ends on the winding center side and the ends on the winding outer peripheral side alternately by connecting portions 361 to 367 penetrating the substrate 33, It is comprised so that it may function as one conducting wire. Specifically, the end 341E on the winding center side of the conductor pattern 341 is connected to the end 351S on the winding center side of the conductor pattern 351 by the connecting portion 361, and the end 351E on the winding outer periphery side of the conductor pattern 351. Is connected to the end portion 342S on the winding outer periphery side of the conductor pattern 342 by the connection portion 362, and the end portion 342E on the winding center side of the conductor pattern 342 is connected to the end portion 352S on the winding center side of the conductor pattern 352 and the connection portion 363. The end portion 352E on the winding outer periphery side of the conductor pattern 352 is connected to the end portion 343S on the winding outer periphery side of the conductor pattern 343 by the connection portion 364, and the end portion 343E on the winding center side of the conductor pattern 343 is The end portion 353S on the winding center side of the conductor pattern 353 is connected to the end portion 353E on the winding outer periphery side of the conductor pattern 353 by the connection portion 365. The end portion 344S on the winding outer periphery side of the conductor pattern 344 is connected to the connection portion 366, and the end portion 344E on the winding center side of the conductor pattern 344 is connected to the end portion 354S on the winding center side of the conductor pattern 354 and the connection portion 367. Are connected (FIG. 4). Further, the end 341S on the winding outer periphery side of the conductor pattern 341 is connected to the lead line L1P, and the end 354E on the winding outer periphery side of the conductor pattern 354 is connected to the lead line L2P.

  Each of the conductor patterns 341 to 344 and the conductor patterns 351 to 354 may have a winding amount of less than one turn (a case where the number of turns is 0.75 is illustrated in FIGS. 3 to 5). Further, it is desirable that one or more turns are wound around one conductor pattern in the conductor formation layer 34 and one conductor pattern in the conductor formation layer 35 connected thereto. For example, the conductor pattern 341 and the conductor pattern 351 make one or more turns (1.5 turns). 3-5, the connection parts 361-367 are arrange | positioned equally along the conductor formation layers 34 and 35, and all the winding amount of each of the conductor patterns 341-344 and the conductor patterns 351-354 is 0.75. Although it was set as the circumference, the winding amount may be different from each other.

  The secondary side coils 32A and 32B are respectively provided on different surfaces of the substrate 32C made of a resin such as epoxy and provided with the opening 32K. In FIG. 3, the secondary coil 32B is provided on the lower surface of the substrate 32C (the side facing the primary coil 31), but the secondary coil 32A is disposed on the lower surface of the substrate 32C. It may be provided on the surface. Here, the opening 32K of the substrate 32C is penetrated by the protrusion 301 of the upper core 30A. Accordingly, the secondary coils 32A and 32B are both wound around the protrusion 301. In the present embodiment, the number of turns of the secondary coils 32A and 32B is one. Further, the secondary side coil 32A and the secondary side coil 32B have one end portions 32A1 and 32B1 electrically connected to each other by a connecting portion C (FIG. 4) penetrating the substrate 32C and connected to the lead line LO. It is comprised so that. The other end portions 32A2 and 32B2 are connected to the lead lines L1S and L2S, respectively.

  The above-described conductor patterns 341 to 344 and 351 to 354 and the secondary side coils 32A and 32B are printed coils made of a highly conductive material such as copper or aluminum.

  When the primary coil 31 having such a configuration is formed, for example, the following may be performed. First, a base provided with copper foil on both surfaces of an insulating substrate 33 made of epoxy or the like is prepared, and through holes are formed at predetermined positions of the base by drilling or the like. Next, copper plating is performed on the wall surface of the through hole by electrolytic plating, electroless plating, or the like to form connection portions 361 to 367 that connect the conductor patterns 341 to 344 and the conductor patterns 351 to 354. Furthermore, the conductive patterns 341 to 344 and 351 to 354 are formed on both sides of the substrate 33 by covering both surfaces of the substrate with a photosensitive material, selectively removing and coppering by wet etching after selective exposure and development. Form. Finally, the primary coil 31 is completed by forming the conductor formation layers 34 and 35 by covering necessary portions with a resist.

  Next, the operation of the switching power supply device configured as described above will be described.

  In the switching circuit 1, the DC input voltage Vin supplied from the input terminals T 1 and T 2 is switched to generate an input AC voltage, and this input AC voltage is supplied to the primary coil 31 of the transformer 3. The transformer 3 transforms the input AC voltage, and the transformed output AC voltage is output from the secondary coils 32A and 32B.

  In the rectifier circuit 4, this output AC voltage is rectified by the rectifier diodes 4A and 4B. As a result, a rectified output is generated between the center tap C (output line LO) and the connection point D1 between the rectifier diodes 4A and 4B.

  In the smoothing circuit 5, the rectified output generated between the center tap C (output line LO) and the connection point D1 of the rectifying diodes 4A and 4B is smoothed and output as the DC output voltage Vout from the output terminals T3 and T4. . The DC output voltage Vout is fed to a low-voltage battery (not shown) to be charged, and the load 6 is driven.

  Here, in this switching power supply device, in the switching circuit 1, the period in which the switching elements S1, S4 are turned on and the period in which the switching elements S2, S3 are turned on are alternately repeated. . Hereinafter, the operation of the switching power supply apparatus will be described in more detail with reference to FIGS. 6 and 7.

  First, as shown in FIG. 6, when the switching elements S1 and S4 of the switching circuit 1 are turned on, the primary loop current Ia1 flows from the switching element S1 to the switching element S4. Then, the voltages VOA and VOB appearing on the secondary windings 32A and 32B of the transformer 3 are in the reverse direction with respect to the rectifier diode 4B, and are in the forward direction with respect to the rectifier diode 4A. For this reason, the output current Ix flows from the rectifier diode 4A to the secondary coil 32A and the output line LO. As a result, the DC output voltage Vout is supplied to a low voltage battery (not shown) and the load 6 is driven.

  At this time, the secondary loop current Ia2 that sequentially passes through the rectifier diode 4A, the secondary coil 32A of the transformer 3, the choke coil 51, and the output smoothing capacitor 52 also flows. Accumulation) is performed.

  On the other hand, as shown in FIG. 7, when the switching elements S1 and S4 of the switching circuit 1 are turned off and the switching elements S2 and S3 are turned on, the primary loop in the direction from the switching element S3 to the switching element S2 is performed. Current Ib1 flows. Then, the voltages VOA and VOB appearing in the secondary side coils 32A and 32B of the transformer 3 are in the reverse direction with respect to the rectifier diode 4A, and are in the forward direction with respect to the rectifier diode 4B. For this reason, the output current Ix flows from the rectifier diode 4B to the secondary coil 32B and the output line LO. As a result, the DC output voltage Vout is supplied to a low voltage battery (not shown) and the load 6 is driven.

  At this time, the secondary loop current Ib2 that sequentially passes through the rectifier diode 4B, the secondary coil 32B of the transformer 3, the choke coil 51, and the output smoothing capacitor 52 also flows. Accumulation) is performed.

  Next, the operation of the primary side coil 31 will be described. In this switching power supply, during the operation, the primary loop currents Ia1 and Ib1 flow through the primary coil 31 (conductor forming layers 34 and 35) as described above. Therefore, the temperature of the conductor formation layers 34 and 35 themselves may increase. In that case, stress is generated at the bonding interface between the substrate 33 and the conductor forming layers 34 and 35 due to the difference in thermal expansion coefficient between the substrate 33 and the conductor forming layers 34 and 35. However, in this switching power supply device, the conductor patterns 341 to 344 in the conductor formation layer 34 and the conductor patterns 351 to 354 in the conductor formation layer 35 are alternately connected by the connection portions 361 to 367 and are integrally wound. . With such a configuration, when the temperature of the conductor forming layers 34 and 35 is increased, the individual strains of the conductor patterns 341 to 344 and 351 to 354 divided into a plurality of parts are not easily transmitted to other conductor patterns, and the conductor Since a part of the stress generated in each of the forming layer 34 and the conductor forming layer 35 is canceled out, the stress that tends to expand along the entire winding direction is reduced. Therefore, compared with the case where the primary side coil 31 consists only of the conductor pattern wound on one side of the substrate 33, it is possible to further increase the number of turns and reduce the thickness while suppressing the occurrence of warping and distortion. .

  In particular, the conductor patterns 341 to 344 are wound in the same direction so as to be adjacent to each other in the conductor forming layer 34, and the conductor patterns 351 to 354 are wound in the same direction so as to be adjacent to each other in the conductor forming layer 35. Since the patterns 341 to 344 and the conductor patterns 351 to 354 are alternately connected to each other, the stress generated between the substrate 33 and the conductor patterns 341 to 344 and 351 to 354 due to thermal expansion is relatively short. It becomes difficult to accumulate in the winding direction. In addition, both the line product ratio and the overall number of turns can be improved. Therefore, it is possible to further increase the number of turns and reduce the thickness while suppressing the warpage and distortion of the primary coil 31 as a whole. Therefore, in the transformer 3 provided with the primary side coil 31, further downsizing can be realized while improving the transformation ratio.

  In the present embodiment, the winding amount of each of the conductor patterns 341 to 344 and 351 to 354 is less than one turn (0.75 turn), and one of the conductor patterns 341 to 344 and this Since one or more turns are wound with one of the conductor patterns 351 to 354 connected to each other (that is, two continuous conductor patterns are combined), the warpage and distortion as a whole can be more effectively suppressed. However, the line product ratio and the overall number of turns can be improved. Here, if any one of the conductor patterns 341 to 344 and 351 to 354 has a winding amount of one or more turns, warping and distortion of the primary coil 31 as a whole is likely to occur. In addition, when the two continuous conductor patterns are combined and the winding amount is less than one turn, the line area ratio is lowered, and it is difficult to make the system compact.

  Moreover, in this Embodiment, since the connection parts 361-367 were arrange | positioned equally along the conductor formation layers 34 and 35, the curvature and distortion as the primary side coil 31 whole are reduced more uniformly. can do.

<Modification 1>
Next, a first modification example (modification example 1) in the present embodiment will be described with reference to FIG. FIG. 8 is an exploded perspective view showing a primary side coil 70 as a modification of the primary side coil 31.

  As shown in FIG. 8, the primary coil 70 has four different conductor formation layers 71 to 74, and the conductor formation layers 71 to 74 include conductor patterns 711 to 714, 721 to 724, respectively. 731 to 734 and 741 to 744 are provided. Each of the conductor patterns 711 to 714 is insulated from each other in the conductor formation layer 71. The same applies to the conductor patterns 721 to 724, 731 to 734, 741 to 744. Insulating layers (not shown) are provided between the four conductor forming layers 71 to 74, respectively. Here, the conductor forming layer 71 and the conductor forming layer 72 make a pair, and the conductor forming layer 73 and the conductor forming layer 74 also make a pair. That is, in the conductor formation layers 71 and 72, the conductor patterns 711 to 714 and the conductor patterns 721 to 724 are alternately connected and integrated by connecting portions 751 to 757 that penetrate through an insulating layer (not shown). Similarly, in the conductor formation layers 73 and 74, the conductor patterns 731 to 734 and the conductor patterns 741 to 744 are alternately connected and integrated by connecting portions 771 to 777 that penetrate through an insulating layer (not shown). Furthermore, one end of the conductor pattern 724 in the conductor forming layer 72 and one end of the conductor pattern 731 in the conductor forming layer 73 are connected by the connecting portion 76, so that the conductor patterns 711 to 714, 721 to 724, 731 to 734 are connected. 741-744 are comprised so that it may function as one conducting wire.

  In this case as well, the occurrence of distortion and warpage of the entire primary coil 31 can be suppressed as in the above embodiment.

<Modification 2>
Next, with reference to FIG. 9, the 2nd modification (modification 2) in this Embodiment is demonstrated. FIG. 9 is an exploded perspective view showing a primary side coil 80 as a modification of the primary side coil 31.

  As shown in FIG. 9, the primary coil 80 has four different conductor formation layers 81 to 84, and the conductor formation layers 81 to 84 include conductor patterns 811 to 814, 821 to 824, respectively. 831 to 834 and 841 to 844 are provided. Note that each of the conductor patterns 811 to 814 is insulated from each other in the conductor formation layer 81. The same applies to the conductor patterns 821 to 824, 831 to 834, 841 to 844. In addition, insulating layers (not shown) are provided between the four conductor formation layers 81 to 84, respectively. Here, the conductor forming layer 81 and the conductor forming layer 82 make a pair, and the conductor forming layer 83 and the conductor forming layer 84 sandwiched between them also form a pair. That is, in the conductor formation layers 81 and 82, the conductor patterns 811 to 814 and the conductor patterns 821 to 824 are alternately connected and integrated by connecting portions 851 to 857 that penetrate through an insulating layer (not shown). Similarly, in the conductor formation layers 83 and 84, the conductor patterns 831 to 834 and the conductor patterns 841 to 844 are alternately connected and integrated by connecting portions 871 to 877 that penetrate through an insulating layer (not shown). Furthermore, one end of the conductor pattern 824 in the conductor formation layer 82 and one end of the conductor pattern 831 in the conductor formation layer 83 are connected by the connecting portion 86, so that the conductor patterns 811 to 814, 821 to 824, 831 to 834 are connected. 841-844 are comprised so that it may function as one conducting wire.

  In this case as well, the occurrence of distortion and warpage of the entire primary coil 31 can be suppressed as in the above embodiment.

  Although the present invention has been described with reference to the embodiment and the modification examples, the present invention is not limited to the embodiment and the like, and various modifications can be made.

  For example, in the above-described embodiment and the like, the case where the coil of the present invention is applied to the primary coil 31 of the transformer 3 has been described, but the present invention is not limited to this. For example, the present invention can be applied to the secondary side coils 32 </ b> A and 32 </ b> B of the transformer 3 and the choke coil 51 of the smoothing circuit 5. In addition, the shape of the conductor and the outline of the gap in the coil of the present invention is not limited to that described in the above embodiment. In the above embodiment and the like, the contours are continuous curves, but may be bent discontinuous lines. That is, those outlines only need to have vector components other than the winding direction of the conductor. Moreover, in the said embodiment etc., although the conductor to wind was provided on both surfaces of the board | substrate, you may make it provide only in any one surface.

It is a circuit diagram showing the structure of the switching power supply device which concerns on one embodiment of this invention. It is a perspective view showing the external appearance structure of the trans | transformer shown in FIG. FIG. 2 is an exploded perspective view of the transformer illustrated in FIG. 1. FIG. 2 is an exploded perspective view illustrating a detailed configuration of a primary coil and a secondary coil in the transformer illustrated in FIG. 1. FIG. 5 is a plan view illustrating a planar configuration of a primary side coil illustrated in FIG. 4. It is a circuit diagram for demonstrating the basic operation | movement of the switching power supply device shown in FIG. It is a circuit diagram for demonstrating the basic operation | movement of the switching power supply device shown in FIG. FIG. 10 is a plan view illustrating a planar configuration of a primary coil as a first modification of the transformer illustrated in FIG. 1. FIG. 10 is a plan view illustrating a planar configuration of a primary coil as a second modification of the transformer illustrated in FIG. 1. It is the top view in a conventional coil, sectional drawing, and the conceptual diagram which represented typically the mode of the displacement by a temperature change.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... High voltage battery, 1 ... Switching circuit, 2 ... Input smoothing capacitor, 3 ... Transformer, 30A ... Upper core, 30B ... Lower core, 301-303 ... Projection part, 31, 70, 80 ... Primary coil, 33 ... Substrate, 34, 35, 81-84 ... conductor forming layer, 341-344, 351-354 ... conductor pattern, 32A, 32B ... secondary coil, 32C ... substrate, 4 ... rectifier circuit, 4A, 4B ... rectifier diode, DESCRIPTION OF SYMBOLS 5 ... Smoothing circuit, 51 ... Choke coil, 52 ... Output smoothing capacitor, 6 ... Load, L1P, L2P, L1S, L2S ... Leader, OL1-OL6 ... Contour, S1-S4, S5, S6 ... Switching element, C1, C2 ... Capacitor, L1H ... Primary side high voltage line, L1L ... Primary side low voltage line, LO ... Output line, LG ... Ground line, T1, T2 ... Input terminal, T3 T4: Output terminal, A, B: End (extraction end), C, 361-367, 751-757, 76, 771-777, 851-857, 871-877 ... Connection (extraction end), Vin: DC Input voltage, Vout ... DC output voltage, Ia1, Ib1, ... primary loop current, Ia2, Ib2, ... secondary loop current, Ix ... output current.

Claims (5)

Each of which has a plurality of conductor patterns and includes a pair of conductor forming layers facing each other with an insulating layer interposed therebetween,
The plurality of conductor patterns in one of the conductor formation layers and the plurality of conductor patterns in the other conductor formation layer are alternately connected by a plurality of connection portions penetrating the insulating layer, and integrated as a whole. Winding along a set of conductor forming layers,
In each of the set of conductor formation layers, the plurality of conductor patterns are wound in the same direction so as to be adjacent to each other,
The ends on the winding center side and the ends on the winding outer periphery side of the plurality of conductor patterns are connected to each other,
Each of the plurality of conductor patterns has a winding amount of less than one turn, and one conductor pattern in one of the conductor formation layers and one conductor pattern in the other conductor formation layer connected thereto. And a portion of which the wire width gradually increases from the inner winding side to the outer winding side. The coil according to claim 1, wherein the plurality of conductor patterns have the same shape and size. The coil according to claim 1 or 2 , wherein the plurality of connection portions are evenly arranged along the set of conductor formation layers. A magnetic core,
A primary coil and a secondary coil wound around the magnetic core;
At least one of the primary side coil and the secondary side coil is:
Each of which has a plurality of conductor patterns and includes a pair of conductor forming layers facing each other with an insulating layer interposed therebetween,
The plurality of conductor patterns in one of the conductor formation layers and the plurality of conductor patterns in the other conductor formation layer are alternately connected by a plurality of connection portions penetrating the insulating layer, and integrated as a whole. Winding along a set of conductor forming layers,
In each of the set of conductor formation layers, the plurality of conductor patterns are wound in the same direction so as to be adjacent to each other,
The ends on the winding center side and the ends on the winding outer periphery side of the plurality of conductor patterns are connected to each other,
Each of the plurality of conductor patterns has a winding amount of less than one turn, and one conductor pattern in one of the conductor formation layers and one conductor pattern in the other conductor formation layer connected thereto. 1 or more times, and includes a portion in which the line width gradually increases from the winding inner circumference side toward the winding outer circumference side. A switching circuit that switches a DC input voltage to generate an input AC voltage;
A transformer element having a primary coil and a secondary coil wound around a magnetic core, transforming the input AC voltage and outputting an output AC voltage;
A rectifier circuit connected in parallel to the secondary side of the transformer element and generating a DC output voltage by performing a rectification operation of the output AC voltage;
At least one of the primary side coil and the secondary side coil in the transformer element is:
Each of which has a plurality of conductor patterns and includes a pair of conductor forming layers facing each other with an insulating layer interposed therebetween,
The plurality of conductor patterns in one of the conductor formation layers and the plurality of conductor patterns in the other conductor formation layer are alternately connected by a plurality of connection portions penetrating the insulating layer, and integrated as a whole. Winding along a set of conductor forming layers,
In each of the set of conductor formation layers, the plurality of conductor patterns are wound in the same direction so as to be adjacent to each other,
The ends on the winding center side and the ends on the winding outer periphery side of the plurality of conductor patterns are connected to each other,
Each of the plurality of conductor patterns has a winding amount of less than one turn, and one conductor pattern in one of the conductor formation layers and one conductor pattern in the other conductor formation layer connected thereto. And a portion where the line width gradually increases from the winding inner periphery side toward the winding outer periphery side.

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