Transformer and converter

Abstract

Provided are a transformer and a converter that are capable of suppressing voltage drop. The transformer comprises: a primary coil 211 to 214 in which each layer is constituted by all or a part of an annular shape having an open end; a secondary coil 221 to 224 which is stacked on the primary coil 211 to 214 with an insulator therebetween and in which each layer is constituted by all or a part of an annular shape having an open end; and a compensation portion 215 which is connected to one of the primary coil 211 to 214 and the secondary coil 221 to 224, the one generating less magnetic flux. The compensation portion 215 is able to generate a magnetic flux that compensates a difference between the generated magnetic flux of the primary coil 211 to 214 and the generated magnetic flux of the secondary coil 221 to 224, and forms a primary- or secondary-side circuit integrally with the one coil.

Description

Transformers and Converters

[0001] The present invention relates to a transformer and a converter.

[0002] In a circuit that performs AC / DC conversion or DC / DC conversion, a transformer may be used to connect two circuits (for example, see Patent Document 1).

[0003] Patent No. 6180083

[0004] The transformer connecting the two circuits described above contains parasitic inductance and leakage inductance, which may result in a voltage drop due to voltage being applied to the parasitic inductance and leakage inductance.

[0005] The present invention has been made to solve such problems, and has an object to provide a transformer and a converter that suppress voltage drops.

[0006] A transformer according to one embodiment of the present invention comprises a primary coil, each layer of which is made up of all or part of a ring having an open end; a secondary coil, which is stacked with the primary coil via an insulator and each layer of which is made up of all or part of a ring having an open end; and a compensation unit, which is connected to one of the primary and secondary coils that generates less magnetic flux and is capable of generating a magnetic flux that compensates for the difference between the magnetic flux generated by the primary coil and the magnetic flux generated by the secondary coil, and which is integrated with one of the coils to form a primary or secondary side circuit.

[0007] A converter according to one aspect of the present invention uses the transformer according to the above aspect for connection between circuits.

[0008] According to a transformer and converter of one aspect of the present invention, by providing a compensator connected to the primary coil or secondary coil, whichever generates the smaller magnetic flux, the amounts of magnetic flux generated in the primary and secondary circuits of the transformer can be equalized. In this configuration, by making the current flow in the primary and secondary circuits opposite each other, the generated magnetic fluxes can be canceled out. As a result, voltage drops due to parasitic inductance and leakage inductance can be suppressed.

[0009] 1 is a schematic diagram of a transformer according to a first embodiment; FIG. 2 is a schematic diagram of the surface of a substrate constituting the transformer; FIG. 3 is a diagram illustrating the relationship between primary and secondary side circuits; FIG. 4 is a schematic explanatory diagram of the primary and secondary side circuits; FIG. 5 is an exploded view of a primary coil and a compensation section; (A) to (C) are diagrams illustrating an example of wiring of laminated wiring of a coil; FIG. 6 is a diagram illustrating a part of the wiring part of a prototype of a transformer according to a second embodiment; FIG. 7 is a cross-sectional view of a part of the wiring part of the transformer; FIG. 8 is a development view of the primary and secondary side circuits; FIG. 9 is an explanatory diagram illustrating the process of folding and configuring the primary and secondary side circuits; FIG. 10 is a structural diagram of an AC / DC converter using the transformer according to the present embodiment; and FIG. 11 is a structural diagram of a DC / DC converter using the transformer according to the present embodiment.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] 1 is a schematic diagram of a transformer 1 according to an embodiment of the present invention. In the explanation of each figure, the directions of up, down, left, right, front and back are used in the figure, but this does not limit the arrangement direction of the transformer 1, and the transformer 1 can be arranged in any direction.

[0012] The transformer 1 is composed of five stacked substrates 2A to 2E. Each of the substrates 2A to 2E has two rectangular transformer holes 3A and 3B spaced a predetermined distance apart, and an iron core 4 passes through the transformer holes 3A and 3B. In this example, the substrates 2A to 2E are stacked via an adhesive layer 5.

[0013] The iron core 4 is configured in a ring shape by connecting the transformer holes 3A, 3B of the substrates 2A to 2E in the stacking direction and connecting both connecting portions on the upper side of the top substrate 2A and the lower side of the bottom substrate 2E. For example, the adhesive layer 5 is an insulating layer made of copper foil laminated with an insulator, and the substrate 2 and adhesive layer 5 can both be approximately 70 μm thick, or approximately 50 μm and 35 μm thick, respectively. However, the optimal values ​​vary depending on the withstand voltage specifications and rated current command of the transformer 1, so the present invention is not limited to the above thicknesses.

[0014] Wiring that surrounds each of the transformer holes 3A and 3B is provided on the front and back surfaces of the substrates 2A to 2D. The wiring on each of the five front surfaces of the substrates 2A to 2D is connected to each other to form the primary circuit of the transformer 1, and the wiring on each of the four back surfaces of the substrates 2A to 2D is connected to each other to form the secondary circuit.

[0015] In this embodiment, the circuit formed by the wiring on the upper surfaces of the substrates 2A to 2D is referred to as the primary coil, and the circuit formed by the wiring on the lower surfaces of the substrates 2A to 2D is referred to as the secondary coil. The secondary coils formed by the substrates 2A to 2D are longer than the primary coils. Furthermore, the wiring on the upper surface of the substrate 2E is referred to as the compensation section, which is connected to the primary coil and is used to compensate for the difference in circuit length between the secondary coil and the primary coil. The compensation section may be provided on the back surface of the substrate 2E instead of the front surface. The primary coils and secondary coils of adjacent substrates 2A to 2D are insulated from each other.

[0016] 2 shows the configuration of one surface (front surface) of substrate 2, representing one of substrates 2A to 2E. The front and back surfaces of substrates 2A to 2D, and the front surface of substrate 2E, are configured similarly. Note that this figure omits the illustration of the connecting conductors between the wiring that forms the coil used to interconnect substrates 2A to 2E and vias 23 and 24 that connect the wiring between substrates 2A to 2E.

[0017] Two transformer holes 3A and 3B are provided spaced apart on the substrate 2, and wiring 21A and 21B are provided to surround the transformer holes 3A and 3B. In the illustrated example, the wiring 21A and 21B are shown as rectangles, but as will be described later, they can be designed in any pattern with open ends.

[0018] This figure shows wiring 21A, 21B that constitute the primary coil provided on the surface of the substrate 2, but wiring 22A, 22B (not shown in Figure 2) that constitute the secondary coil is also provided on the back surface of the substrate 2.

[0019] Vias 23A and 23B are provided around the wiring 21A at relatively close positions on the left and right, and via 24A is provided below at a relatively distant position. Vias 23A and 23B each have four connection portions 231A to 234A, and via 24A has three connection portions (not numbered). Similarly, vias 23C and 23D are provided around the wiring 21B at the left and right, and via 24B is provided below. Note that the back surface of substrate 2A also has a configuration similar to vias 23A to 23D, 24A, and 24B. These configurations are used to mutually connect wiring 21A and 21B of substrates 2A to 2F.

[0020] 3 is a schematic diagram of the wiring 21 on the front surface and the wiring 22 on the back surface of each of the substrates 2A to 2D in the transformer 1 of this embodiment. In this embodiment, the wiring 21 constituting the primary side circuit and the wiring 22 constituting the secondary side circuit are arranged adjacent to each other, and the currents flowing in the wirings 21 and 22 are configured to face each other. With this configuration, magnetic fluxes generated by the currents flowing in the wirings 21 and 22 cancel each other out, thereby reducing leakage magnetic flux. In this embodiment, the primary and secondary side circuits are arranged opposite each other throughout the transformer 1, as described below, thereby reducing leakage magnetic flux throughout the transformer 1.

[0021] 4 is an explanatory diagram of the primary-side circuit (primary coil and compensation unit) and the secondary-side circuit (secondary coil). The primary coil of the transformer 1 is composed of wiring 211-214 provided on the surfaces of the substrates 2A-2D, and is further connected to wiring 215 (compensation unit) on the surface of the substrate 2E. The primary coil (wiring 211-214) and wiring 215 (compensation unit) are integrated to form the primary-side circuit of the transformer 1. Note that current flows counterclockwise in the wiring 211-215, and clockwise in the wiring 221-224.

[0022] The secondary coil is made up of wires 221 to 224 provided on the back surfaces of the substrates 2A to 2D. In this embodiment, the secondary coil alone constitutes the secondary circuit of the transformer 1. For the sake of explanation, the wires on the right side of the wires 211 to 214 in the drawing will be referred to as the first side, the wires on the far side as the second side, the wires on the left side as the third side, and the wires on the near side as the fourth side.

[0023] The primary coil (wiring 211-214) and the compensation section (wiring 215) are connected to each other via connecting sections 31-34. The connecting sections 31-34 correspond to the connecting sections 234A-231A of the via 23A in FIG. 2. Specifically, the connecting sections 234A-231A of the via 23A are used to connect adjacent layers of the wiring 211-215 of the substrates 2A-2E, starting from the top in the stacking direction. Therefore, the connecting sections 31-34 are shifted in position from the front to the back of the drawing on the third side, starting from the top, which prevents the primary coil of the transformer 1 from becoming thick. The detailed configuration of the primary coil will be described later using FIG. 5.

[0024] The secondary coils (wires 221 to 224) are separated at the center of the first side. The following description will be given using wire 221 as an example, but the other wires 222 to 224 have the same configuration.

[0025] For the purpose of explaining magnetic flux cancellation, it is assumed that the wiring 221 has one end 221A and the other end 221B. A rectangular connection terminal 221C that protrudes outward is connected to the other end 221B. The connection terminal 221C is connected to one end of a secondary coil in another layer. For example, one end 221A of the wiring 221 is connected to the connection terminal 222C of the wiring 222.

[0026] In this figure, the connection terminals 221C to 224C of the secondary coil wiring 221 to 224 are arranged in the same position within the plane of the board, but this arrangement is not limited to this. The connection terminals 221C to 224C can be arranged in any position within the plane of the boards 2A to 2D (not shown in Figure 4). The connection terminals 221C to 224C may be offset within the plane of the board. This reduces interference between the terminals, making it easier to connect the wiring on each layer and preventing the secondary coil from becoming thick. Here, offset refers to shifting the positions of the connection terminals 221C to 224C horizontally.

[0027] Figure 5 is an exploded view of the primary coil and compensation unit. The left side of this figure shows the primary coil (wiring 211-214) and compensation unit (wiring 215) provided on the surfaces of the substrates 2A-2E shown in Figure 1. The right side explains that by partially combining the wiring 211-215, each layer has the same circuit length as the wiring 221-224 of the secondary coil. In this figure, the wiring 211-215 will be referred to as the first to fourth sides, from top right to bottom left in the figure.

[0028] As shown on the left, the first layer wiring 211 has a wiring region consisting of the first and second sides and a part of the third side above the connection part 31 (including the width of the connection part 31). Similarly, the fifth layer wiring 215 has a wiring region consisting of the fourth side and a part of the third side below the connection part 34 (excluding the width of the connection part 34).

[0029] In contrast, the second layer wiring 212 has a first wiring region 212A consisting of a portion below the connection portion 31 of the third side (excluding the width of the connection portion 31) and the fourth side, and a second wiring region 212B consisting of a portion above the connection portion 32 of the first side, second side, and third side (including the width of the connection portion 32).

[0030] Similar to the second layer, the wiring 213 of the third layer includes a first wiring region 213A consisting of a portion below the connection portion 32 of the third side (excluding the width of the connection portion 32) and the fourth side, and a second wiring region 213B consisting of a portion above the connection portion 33 of the first, second, and third sides (including the width of the connection portion 33). The wiring 214 of the fourth layer includes a first wiring region 214A consisting of a portion below the connection portion 33 of the third side (excluding the width of the connection portion 33) and the fourth side, and a second wiring region 214B consisting of a portion above the connection portion 35 of the first, second, and third sides (including the width of the connection portion 34).

[0031] When the regions of the wiring 211 to 215 of each layer of the primary circuit are combined and compared with the wiring lengths of the wiring 221 to 224 of the secondary circuit (secondary coil), the results are as follows.

[0032] As shown at the top right of the figure, consider a rectangular circuit combining first-layer wiring 211 and first wiring region 212A of second-layer wiring 212. This combination forms a portion with first to fourth sides in the first and second layers of the primary coil, making the circuit length equal to that of the first-layer wiring 221 (not shown in FIG. 4 ) of the secondary coil. Furthermore, the first-layer wiring 221 of the secondary side exists between the first-layer wiring 211 of the primary side and the first wiring region 212A of the second layer. That is, the first-layer wiring 211 of the primary side and the first wiring region 212A of the second layer are each adjacent to the first-layer wiring 221 of the secondary side. As a result, the magnetic flux generated by the secondary coil (wiring 221) can be canceled out by passing currents in opposite directions through the adjacent primary coils (wiring 211, first wiring region 212A). The magnetic flux on the primary side is also canceled out by the magnetic flux on the secondary side, meaning that the magnetic fluxes on the primary and secondary sides can cancel each other out.

[0033] Furthermore, consider a rectangular circuit combining the second wiring region 212B of the second layer of the primary coil and the first wiring region 213A of the third layer, as shown in the second figure from the top. With this combination, the second wiring region 212B of the second layer of the primary coil and the first wiring region 213A of the third layer form a portion having first to fourth sides, and the circuit length is equal to that of the second layer wiring 222 of the secondary coil (not shown in FIG. 4 ). Furthermore, the second layer wiring 222 of the secondary side is located between the second wiring region 212B of the primary side and the first wiring region 213A of the third layer. That is, the second layer wiring region 212B of the primary side and the first wiring region 213A of the third layer are each adjacent to the second layer wiring 222 of the secondary side. As a result, the magnetic flux generated by the secondary coil (wiring 222) can be canceled by passing current in the opposite direction through the adjacent primary coils (second wiring region 212B, first wiring region 213A). The magnetic flux on the primary side is also cancelled out by the magnetic flux on the secondary side, that is, the magnetic fluxes on the primary side and the secondary side can cancel each other out.

[0034] Similarly, if we consider a rectangular circuit combining the second wiring region 213B of the third layer of the primary coil and the first wiring region 214A of the fourth layer, as shown in the third figure from the top, these are adjacent to the wiring 223 of the third layer of the secondary coil (not shown in Figure 4), and the magnetic flux generated by the secondary coil (wiring 223) can be configured to cancel out by passing current in opposite directions through the adjacent primary coils (second wiring region 213B, first wiring region 214A).

[0035] Furthermore, as shown at the bottom, if we consider a rectangular circuit combining the second wiring region 214B of the fourth layer of the primary coil and the wiring 215 of the fifth layer of the compensation section, these are adjacent to the wiring 224 of the fourth layer of the secondary coil (not shown in Figure 4), and the magnetic flux created by the secondary coil (wiring 224) can be configured to cancel out by passing current in the opposite direction through the adjacent primary coil (second wiring region 214B, wiring 215 of the compensation section).

[0036] In this way, by providing the primary coils (wirings 211 to 214) with the wiring 215 that serves as a compensation section, it is possible to provide an adjacent primary coil for each secondary coil (wirings 221 to 224) in all layers. As a result, the magnetic flux generated by the secondary coil can be canceled out by passing a current in the opposite direction through the adjacent primary coil. The magnetic flux on the primary side is also canceled out by the magnetic flux on the secondary side, meaning that the magnetic flux on the primary side and the magnetic flux on the secondary side can cancel each other out.

[0037] The primary coil is shorter than the secondary coil (wiring 221-224), and the length of the wiring 215, which serves as the compensation section, corresponds to this difference and is connected to the primary coil to compensate for this difference. As a result, the primary coil (wiring 211-214) and the compensation section (wiring 215) are integrated to form the primary side circuit, and the circuit length is equal to that of the secondary coil (wiring 221-224). In this configuration, if currents flow in opposite directions in the primary coil, compensation section, and secondary coil, the generated magnetic fluxes can be canceled out, preventing voltage drops due to leakage inductance and parasitic inductance. This cancellation of generated magnetic fluxes due to currents flowing in opposite directions in the wiring of the primary coil and secondary coil is sometimes referred to as the proximity effect.

[0038] In the above example, it is assumed that the thickness of the wiring between the primary coil and the compensation unit is the same as that between the secondary coil and the compensation unit, and that the amount of magnetic flux generated per unit length (also referred to as the magnetic flux generation rate) is the same. Therefore, we have considered partially combining the primary coils (wirings 211 to 214) and compensation unit (wiring 215) located above and below the wiring 221 to 224 of each layer of the secondary coil to achieve the same circuit length, but other configurations are also possible.

[0039] When the currents in the primary and secondary coils almost overlap due to the proximity effect, the thickness of the wiring for the primary coil, compensation section, and secondary coil does not need to be the same. Even if the wiring thicknesses are different, leakage inductance and parasitic inductance can be reduced as long as the magnetic fluxes generated in the primary and secondary circuits can cancel each other out.

[0040] According to the transformer 1 of this embodiment, the wiring 211 and the first wiring region 212A constituting the primary coil are both located between them and are disposed in close proximity to the wiring 221 constituting the secondary coil. Current flows in the opposite direction to the wiring 221 constituting the secondary coil, and the magnetic flux generated by the secondary coil (wiring 221) can be canceled by flowing current in the opposite direction through the adjacent primary coil (wiring 211, first wiring region 212A). The magnetic flux on the primary side is also canceled out by the magnetic flux on the secondary side. As a result, the magnetic fluxes on the primary coil side (wiring 211, first wiring region 212A) and the secondary coil side (wiring 221) can cancel each other out.

[0041] Similarly, the second wiring region 212B and the first wiring region 213A constituting the primary coil are arranged close to the wiring 222 constituting the secondary coil, and currents flow in opposite directions. As a result, the magnetic fluxes on the primary coil side (second wiring region 212B, first wiring region 213A) and the secondary coil side (wiring 222) cancel each other out.

[0042] The second wiring region 213B and the first wiring region 214A constituting the primary coil are arranged close to the wiring 223 constituting the secondary coil, and currents flow in opposite directions. As a result, the magnetic fluxes on the primary coil side (second wiring region 213B, first wiring region 214A) and the secondary coil side (wiring 223) cancel each other out.

[0043] The second wiring region 214B and the compensation section (wiring 215) that constitute the primary coil are disposed close to the wiring 224 that constitutes the secondary coil, and currents flow in opposite directions. As a result, the magnetic fluxes on the primary coil side (second wiring region 214B, wiring 215) and the secondary coil side (wiring 224) cancel each other out.

[0044] In this way, by providing the compensation section (wiring 215), the amounts of magnetic flux generated are equal and cancel each other out in the entire circuits on the primary side (wiring 211 to 215) and the secondary side (wiring 221 to 224), thereby reducing the effects of leakage inductance and parasitic inductance.

[0045] In the transformer 1 of this embodiment, as shown in FIGS. 4 and 5 , the wiring 211 that forms the primary coil is composed of a portion of a loop with an open end, and the wirings 212 to 214 that form the primary coil are composed of the entire loop with an open end. Furthermore, each layer of the wirings 221 to 224 that form the secondary coil is composed of the entire loop with an open end. The secondary coil may also be composed of a portion of a loop. The primary coils 212 to 214 and the secondary coils 221 to 224 are laminated with an insulating adhesive layer 5 interposed between them. In this embodiment, the magnetic flux generated by the wirings 211 to 214 that form the primary coil does not completely cancel out the magnetic flux generated by the wirings 221 to 224 that form the secondary coil. This state or configuration is referred to herein as having a low magnetic flux generation. Therefore, if the magnetic flux generated by the wirings 211 to 214 that form the primary coil is less than that of the wirings 221 to 224 that form the secondary coil, then it can be expressed as "the wiring 215 that forms the compensation section is connected to the wirings 211 to 214 that form the primary coil with the low magnetic flux generation."

[0046] In this configuration, the primary-side wiring of the two layers (e.g., the entire wiring 211 that forms the primary coil and the first wiring region 212A that is a portion of the wiring 212) is adjacent to the secondary-side wiring (e.g., wiring 221) that exists between them. As a result, the magnetic flux generated by the secondary coil (wiring 221) can be canceled out by passing currents in opposite directions through the adjacent primary coils (wiring 211, first wiring region 212A). The magnetic flux on the primary side is also canceled out by the magnetic flux on the secondary side, i.e., the magnetic flux on the primary side and the magnetic flux on the secondary side can cancel each other out. In this way, by providing the compensating unit 215, the difference between the magnetic flux generated by the primary coil and the magnetic flux generated by the secondary coil can be compensated for.

[0047] Furthermore, according to the transformer 1 of this embodiment, the connection parts 31 to 34 of each layer are arranged offset within the plane of each layer, as shown in Fig. 4. As a result, interference between the connection parts 31 to 34 in the vertical direction can be suppressed, and therefore, the thickness of the transformer 1 can be prevented from increasing.

[0048] Furthermore, according to the transformer 1 of this embodiment, the connection terminals 221C to 224C of the wiring 221 to 224 on the secondary coil side may be arranged offset within the plane of the substrates 2A to 2E. This arrangement reduces interference between the connection terminals 221C to 224C, making it easier to connect the wiring 221 to 224 on the secondary coil side and also reducing the overall thickness of the transformer 1.

[0049] (Example of connection of laminated circuit in transformer 1) Figure 6 is a diagram showing an example of wiring of wires 21A, 22A that form the left and right primary coils of transformer 1. As shown in Figure 6(A), transformer 1 is configured by stacking multiple substrates 2 with adhesive layers 5 interposed therebetween. In the example shown, the laminated circuit is configured of nine substrates 2, but the number of laminated substrates is arbitrary. Furthermore, transformer 1 includes a first laminated section 6 on the left side of the figure that is configured of multiple wires 21A, 21B through which iron core 4 passes, and a second laminated section 7 on the right side of the figure that is configured of multiple wires 22A, 22B through which iron core 4 passes.

[0050] The primary coil wiring between the first laminate 6 and the second laminate 7 can be arbitrarily performed using, for example, vias 24A and 24B shown at the bottom of FIG. 2 . As shown in FIG. 6B , the first laminate 6 and the second laminate 7 may be connected in series on the top surface. This is effective for applications requiring a high voltage ratio between the primary coil and the secondary coil. On the other hand, as shown in FIG. 6C , two transformers 1 may be stacked one above the other, and the first laminate 6 and the second laminate 7 may be connected in parallel. This has the advantage of reducing inductance. The wiring between the first laminate 6 and the second laminate 7 within the transformer 1 is not limited to this, and the wiring between two or more transformers 1 may be arbitrarily connected to each other.

[0051] Second Embodiment In the first embodiment, the primary coil, the compensation section, and the secondary coil are configured using the wiring 21, 22 provided on the front and back surfaces of the substrates 2A to 2E, but this is not limiting. In the second embodiment, an example will be described in which the transformer 1 is configured by folding a film substrate provided with wiring.

[0052] 7 is a diagram showing a portion of the wiring portion of a prototype of the transformer 1 of the second embodiment. This diagram shows one of the laminated wiring layers excluding the iron core 4 of the transformer 1. As shown in the figure, the transformer 1 of this embodiment is constructed by folding a film substrate on which wiring is provided. By using a film substrate in this manner, the laminated density can be increased compared to when the substrate 2 is used as in the first embodiment.

[0053] 8 is a cross-sectional view of a portion of the wiring portion of the transformer 1 shown in FIG. 7. As shown in this figure, the wiring 21 (hatched downwards to the right) that constitutes the primary circuit is folded while surrounded by a film-like insulating member 41 (hatched upwards to the right, also referred to as an insulating layer). Similarly, the wiring 22 (hatched in a grid pattern) that constitutes the secondary circuit is folded while surrounded by the film-like insulating member 41. The folded wirings 21 and 22 are then stacked on top of each other and fixed by an adhesive layer 42 (hatched in dots). As an example, the wirings 21 and 22 are approximately 100 μm thick, the insulating member 41 is 25 μm thick, and the adhesive layer 42 is 25 μm thick.

[0054] FIG. 9 is a diagram showing the wiring of the primary coil and secondary coil before folding. In this figure, the insulating member 41 and adhesive layer 42 are not shown, but only the wiring 21 and 22 are shown. The left side shows the wiring 211-214 that constitutes the primary coil, and the right side shows the wiring 221-224 that constitutes the secondary coil. Note that the wiring 221-224 that constitutes the secondary coil have the same pattern, so only one wiring is shown as a representative. The wiring 211-214 of the primary coil shown in this way is folded while overlapping with the wiring 221-224 of the secondary coil, thereby forming the laminated wiring shown in FIGS. 7 and 8. Note that the arrows shown in the figure indicate the direction of current flow.

[0055] 10 is a diagram showing how the first layer wiring 211 of the primary coil and the first layer wiring 221 of the secondary coil shown in FIG. 9 are folded. The wiring 211 is composed of sides labeled A to H between arrowed ends. In the example shown, the wiring 211 has multiple bends formed in the direction from A to H, including a 90-degree clockwise rotation (end (arrow) to A), a 90-degree counterclockwise rotation (A to B), a 90-degree clockwise rotation (B to C), a 90-degree clockwise rotation (C to D), a 90-degree clockwise rotation (D to E), a 90-degree counterclockwise rotation (E to F), a 90-degree counterclockwise rotation (F to G), a 90-degree counterclockwise rotation (G to H), and a 90-degree clockwise rotation (H to end (arrow)).

[0056] The wiring 212 is composed of sides labeled I to P between both ends with arrows. Specifically, the wiring 212 has a plurality of bends in the direction from I to P, including a straight line (end (arrow) to I), a 90-degree counterclockwise rotation (I to J), a 90-degree counterclockwise rotation (J to K), a 90-degree clockwise rotation (K to L), a 90-degree clockwise rotation (L to M), a 90-degree counterclockwise rotation (M to N), a 90-degree counterclockwise rotation (N to O), a 90-degree counterclockwise rotation (O to P), and a 90-degree clockwise rotation (P to end (arrow)).

[0057] The folding methods for the primary and secondary coils are shown in (1) to (3) and (X) to (Z) in the figure. First, as shown in (1), the primary coil is arranged so that the wiring A to B forms a plane. Then, as shown in (X), secondary coils I to K are arranged on top of the primary coil so that secondary coils J and K overlap primary coils A and B.

[0058] Next, as shown in (2), the primary coil is bent between B and C, and the primary coils C to E are placed on top of the secondary coils I to K. At this time, the primary coils D and E are placed on top of the secondary coils I and J. After that, as shown in (Y), the secondary coil is bent between K and L, and the secondary coils L and M are placed on top of the primary coils C and D.

[0059] Next, as shown in (3), the primary coil is bent between E and F, and F to H of the primary coil are placed on top of L and M of the secondary coil. At this time, G and H of the primary coil are placed on top of L and M of the secondary coil. After that, as shown in (Z), the secondary coil is bent between M and N, and N to P of the secondary coil are placed on top of F to H of the primary coil so that O and P of the secondary coil are placed on top of F and G of the primary coil.

[0060] With this configuration, as shown by the hatching slanting upward to the right, I to K of the first layer of the secondary coil are adjacent to A and B of the first layer of the primary coil and D of the second layer, and they share the same line length of three-quarters of a turn. As shown by the grid hatching, L and M of the second layer of the secondary coil are adjacent to C of the second layer of the primary coil and H of the third layer of the primary coil, and they share the same line length of two-quarters of a turn. Furthermore, as shown by the hatching slanting downward to the right, N to P of the third layer of the secondary coil are adjacent to E of the second layer of the primary coil and F and G of the third layer of the primary coil, and they share the same line length of three-quarters of a turn.

[0061] With this configuration, the primary coils A to H and the secondary coils I to P are arranged adjacent to each other with three layers and the same line length between each layer. As a result, by passing current in the primary coil and the secondary coil in opposite directions as shown in Figure 3, the magnetic flux generated by the secondary coil can be canceled out by passing current in the opposite direction through the adjacent primary coil. The magnetic flux on the primary side is also canceled out by the magnetic flux on the secondary side, meaning that the magnetic flux on the primary side and the magnetic flux on the secondary side can cancel each other out.

[0062] In this embodiment, both the primary coil and the secondary coil are configured with three layers, but in the primary circuit, for example, the first and second layers A to E can be considered to correspond to the primary coil, and the third layer F to H can be considered to correspond to the compensation section. Therefore, by providing such a compensation section, the circuit lengths of the primary and secondary sides can be made equal. Furthermore, in this configuration, by flowing currents in opposite directions in the primary and secondary coils, magnetic fluxes between adjacent primary and secondary coils can be canceled out.

[0063] In this way, with the transformer 1 of the second embodiment, by making the circuit lengths of the primary and secondary sides equal, magnetic fluxes can be canceled out when currents flow in opposite directions. Furthermore, compared to the transformer 1 of the first embodiment, a film substrate is used instead of the substrate 2, which allows for a higher lamination density and therefore improves the conversion efficiency of the transformer 1.

[0064] (Application Example of Transformer) The transformer 1 of the first and second embodiments can be applied to various devices. For example, Fig. 11 discloses an AC / DC (Alternating Current / Direct Current) converter 50 that uses the transformer 1. In the AC / DC converter 50, a DC circuit 51 and an AC circuit 52 are connected using the transformer 1. A capacitor 53 is provided between the terminals on the DC circuit 51 side.

[0065] In the example shown in the figure, the DC circuit 51 has a two-leg configuration, with each upper and lower arm consisting of one switch element, and the AC circuit 52 has a two-leg configuration, with each upper and lower arm consisting of two switch elements. In this AC / DC converter 50, power generated by controlling the DC circuit 51 can be transmitted to the AC circuit 52 side via the transformer 1.

[0066] 12 , it is also possible to configure a DC / DC (Direct Current / Direct Current) converter 60 by connecting two DC circuits 61 and 62 via a transformer 1. In the DC / DC converter 60, the DC circuits 61 and 62 are connected using the transformer 1. Capacitors 63 and 64 are provided between the terminals of the DC circuits 61 and 62.

[0067] Each of the DC circuits 61 and 62 has a two-leg configuration, with each of the upper and lower arms being configured with one switch element. In particular, the DC / DC converter 60 can improve its operating efficiency by using the transformer 1, which can reduce voltage drops caused by parasitic inductance and leakage inductance.

[0068] Converters such as the AC / DC converter 50 and DC / DC converter 60 using the transformer 1 can be used in various power systems and products. For example, they can be used in converters used in SSTs (Solid State Transformers). They are also expected to be applied to various devices, such as data center power supplies, solar power conditioning systems (PCSs), battery PCSs, and converters / inverters for railcars. In these products, voltage drops due to parasitic inductance and leakage inductance are suppressed in the transformer 1 used to couple the circuits, thereby improving overall energy efficiency.

[0069] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to explain the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0070] The following additional notes are provided regarding the above-described embodiments.

[0071] (Additional Item 1) A transformer comprising: a primary coil, each layer of which is made up of all or part of a ring having an open end; a secondary coil, which is stacked with the primary coil via an insulator, each layer of which is made up of all or part of a ring having an open end; and a compensating unit, which is connected to one of the primary and secondary coils that generates less magnetic flux, is capable of generating magnetic flux that compensates for the difference between the magnetic flux generated by the primary coil and the magnetic flux generated by the secondary coil, and is integrated with one of the coils to form a primary or secondary side circuit.

[0072] (Supplementary Item 2) The transformer described in (Supplementary Item 1), wherein the primary coil, the secondary coil, and the compensation unit have the same magnetic flux generation rate per unit length, and the compensation unit is connected to one of the primary coil and the secondary coil, which has a shorter circuit length, and has a circuit length corresponding to the difference between the circuit length of the primary coil and the circuit length of the secondary coil.

[0073] (Supplementary Item 3) The transformer according to (Supplementary Item 1) or (Supplementary Item 2), wherein one of the layers of the primary coil and the secondary coil, which generates less magnetic flux, and the other of the layers of the compensation section, which generates more magnetic flux, are disposed between the layers of the primary coil and the secondary coil.

[0074] (Supplementary Item 4) The transformer according to any one of (Supplementary Item 1) to (Supplementary Item 3), wherein the open ends provided in each layer of at least one of the primary coil and the secondary coil are offset within the plane of the each layer.

[0075] (Supplementary Item 5) The transformer according to any one of (Supplementary Item 1) to (Supplementary Item 4), wherein the circuit formed integrally by connecting one of the primary coil and the secondary coil, which generates less magnetic flux, to the compensation unit has the in-plane positions of each layer at both ends being approximately the same.

[0076] (Supplementary Item 6) The transformer described in any one of (Supplementary Item 1) to (Supplementary Item 5) is configured with one or more substrates on both sides of which circuits can be formed, the primary coil is configured on one side of the substrate, the secondary coil is configured on the other side of the substrate, and the compensation unit is configured on any side of the substrate.

[0077] (Supplementary Item 7) A transformer described in any one of (Supplementary Item 1) to (Supplementary Item 6), wherein the primary coil is formed by folding a first film substrate, the secondary coil is formed by folding a second film substrate so as to overlap the first film substrate, and the compensation section is integrally formed on one of the film substrates of the primary coil and the secondary coil which generates less magnetic flux, and is folded so as to overlap the other film substrate.

[0078] (Supplementary Item 8) A converter using the transformer according to any one of (Supplementary Item 1) to (Supplementary Item 7) for connecting circuits.

[0079] REFERENCE SIGNS LIST 1 transformer 2, 2A to 2F substrate 4 iron core 5 adhesive layer 21, 22 wiring 211 to 214 primary coil 215 compensation section 221 to 224 secondary coil 31 to 35, 231A to 234A connection section AC / DC converter 50 DC / DC converter 60

Claims

1. A transformer comprising: a primary coil, each layer of which is made up of all or part of an annular shape with an open end; a secondary coil, layered with the primary coil via an insulator, each layer of which is made up of all or part of an annular shape with an open end; and a compensating unit, connected to one of the primary and secondary coils which generates less magnetic flux, capable of generating magnetic flux that compensates for the difference between the magnetic flux generated by the primary coil and the magnetic flux generated by the secondary coil, and which is integrated with one of the coils to form a primary or secondary side circuit.

2. The transformer according to claim 1, wherein the transformer is configured with one or more substrates on which a circuit can be formed, and the primary coil, the secondary coil, and the compensation section are configured on the substrates.

3. A transformer as described in claim 1, wherein the primary coil, the secondary coil, and the compensation section have the same magnetic flux generation rate per unit length, and the compensation section is connected to the one of the primary coil and the secondary coil which has the shorter circuit length, and has a circuit length equivalent to the difference between the circuit length of the primary coil and the circuit length of the secondary coil.

4. A transformer as claimed in claim 1, wherein one of the layers of the primary coil and the secondary coil, which generates less magnetic flux, is disposed between the other of the layers of the primary coil and the secondary coil, which generates more magnetic flux, and the other of the layers of the compensating section.

5. The transformer according to claim 1, wherein one of the primary coil and the secondary coil which generates less magnetic flux, and the connection sections between the layers of the compensation section connected to said one, are arranged at different positions within the lamination plane.

6. A transformer according to claim 1, wherein the open ends provided on each layer of at least one of the primary coil and the secondary coil are offset within the plane of the layer.

7. A transformer as claimed in claim 1, wherein the circuit formed by connecting one of the primary coil and the secondary coil, which generates less magnetic flux, to the compensation section is located at approximately the same position in the plane of each layer at both ends.

8. The transformer according to claim 1, wherein the transformer is configured with one or more substrates on both sides of which circuits can be formed, the primary coil is configured on one side of the substrate, the secondary coil is configured on the other side of the substrate, and the compensation section is configured on any side of the substrate.

9. A transformer as described in claim 1, wherein the primary coil is formed by folding a first film substrate, the secondary coil is formed by folding a second film substrate so as to overlap the first film substrate, and the compensation section is integrally formed on one of the film substrates of the primary coil and the secondary coil which generates less magnetic flux, and is folded so as to overlap the other film substrate.

10. A transformer having: a primary coil, each layer of which is made up of all or part of an annular shape with an open end; a secondary coil, which is stacked with the primary coil via an insulator, each layer of which is made up of all or part of an annular shape with an open end, and which has a secondary cancellation winding section whose current direction is opposite to that of the primary cancellation winding section of the primary coil and which cancels out generated magnetic flux; and a compensation section connected to one of the primary and secondary coils whose generated magnetic flux is canceled out by the cancellation, and which compensates for generated magnetic flux in a portion of the other of the primary and secondary coils that is different from the cancellation winding section.

11. A converter using the transformer according to claim 1 or 10 for connection between circuits.

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