Isolation transformer

Abstract

To provide an isolation transformer capable of being miniaturized.SOLUTION: An isolation transformer 100 according to a certain embodiment includes: a transformer body 70 that has a primary coil 82 and a plurality of secondary coils 86; a primary-side connection terminal 84 that is connected to a terminal of the primary coil 82 and that protrudes in a first direction from the transformer body 70; a plurality of secondary-side connection terminals 88 that is connected to terminals of the plurality of secondary coils 86 and that protrudes in the first direction from the transformer body 70; and a first insulation wall part 11 that increases an extended surface distance between the primary-side connection terminal 84 and the secondary-side connection terminal 88.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention is an insulating transformer. Su Regarding. [Background technology]

[0002] Patent Document 1 describes an isolation transformer having an insulated primary winding and a secondary winding. In this transformer, a first insulated wire is wound around a bobbin to form a primary winding, a second insulated wire is wound around the bobbin to form a secondary winding, and a magnetic core is attached to the bobbin. The transformer also includes a first group of connection terminals to which both ends of the first insulated wire are connected, and a second group of connection terminals to which both ends of the second insulated wire are connected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-28023 Summary of the Invention [Problem to be solved by the invention]

[0004] It is possible to provide multiple isolation transformers to supply power to multiple circuits. However, this requires a large amount of space, which is disadvantageous for miniaturizing the device in which the isolation transformers are installed. It is also possible to provide multiple secondary windings on a single isolation transformer to supply power to multiple circuits. However, as the number of secondary windings increases, the number of connection terminals connected to each secondary winding also increases. In this case, the distance between the connection terminals must be set wide to achieve the desired insulation characteristics, which is disadvantageous for miniaturizing the isolation transformer.

[0005] The present invention has been made in view of the above problems, and one of its objects is to provide an isolation transformer that can be made smaller. [Means for solving the problem]

[0006] In order to solve the above problems, an isolation transformer according to one embodiment of the present invention includes: a transformer body having a primary coil and a plurality of secondary coils; a primary-side connection terminal connected to an end of the primary coil and protruding in a first direction from the transformer body; a plurality of secondary-side connection terminals connected to terminals of the plurality of secondary coils and protruding in the first direction from the transformer body; and a first insulating wall portion that increases the extension distance between the primary-side connection terminal and the secondary-side connection terminal.

[0007] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, systems, etc., are also valid aspects of the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an isolation transformer that can be made compact. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view schematically illustrating an example of an isolation transformer according to an embodiment. [Figure 2] FIG. 2 is a bottom view showing the isolation transformer of FIG. [Figure 3] FIG. 2 is a perspective view showing the connection terminal holding member of FIG. [Figure 4] FIG. 4 is an enlarged front view showing the periphery of an insulating wall portion. [Figure 5] FIG. 4 is an enlarged bottom view showing the periphery of the insulating wall portion. [Figure 6] FIG. 4 is an enlarged front view showing the periphery of an insulating wall portion when mounted on a substrate. [Figure 7] FIG. 4 is an enlarged bottom view showing the periphery of an insulating wall portion when mounted on a substrate. [Figure 8] FIG. 2 is a block diagram showing an example of a power supply circuit including the isolation transformer of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure will be outlined below. For example, a switching power supply may be configured to switch external or internal power (e.g., DC 24 V) and supply it to the primary side (low-voltage system) of an isolation transformer, and the voltage output to the secondary side (high-voltage system) is used as a power source to control a power module. In this case, it is important for the isolation transformer to ensure creepage distance and clearance distance to achieve a predetermined insulation performance between the primary side (low-voltage system) and the secondary side (high-voltage system). An example of the predetermined insulation performance is the insulation performance specified in standards such as CE (registered trademark) and UL (registered trademark). However, simply increasing the creepage distance and clearance distance increases the distance between the terminals, which is detrimental to the miniaturization of the transformer.

[0011] In particular, in a configuration that includes multiple secondary coils to control multiple power modules and ensures insulation performance between each secondary coil, the distance between each terminal of the multiple secondary coils also becomes large, which is even more disadvantageous in terms of miniaturizing the transformer.

[0012] Based on these findings, the inventors focused on a configuration that includes a first insulating wall portion that increases the surface distance between the primary connection terminal and the secondary connection terminal. By providing a first insulating wall portion between the primary connection terminal and the secondary connection terminal, it is possible to increase the creepage distance and clearance distance even if the linear distance between these terminals is the same. In other words, the linear distance between the terminals can be shortened to ensure the desired creepage distance and clearance distance, which is advantageous for miniaturizing the transformer.

[0013] Furthermore, when multiple secondary coils are provided, a second insulating wall portion may be provided to increase the surface distance between the connection terminals of the multiple secondary coils. For the same reasons as above, this allows the linear distance between the connection terminals of the secondary coils to be short when ensuring the desired creepage distance and clearance distance, which is advantageous for miniaturizing the transformer. Hereinafter, the configuration of the present disclosure will be described in detail with reference to embodiments.

[0014] The present disclosure will be described below based on preferred embodiments with reference to the drawings. In the embodiments and modified examples, identical or equivalent components and members are designated by the same reference numerals, and redundant explanations will be omitted where appropriate. Furthermore, the dimensions of the members in each drawing are enlarged or reduced as appropriate for ease of understanding. Furthermore, some members that are not important for explaining the embodiments are omitted from the drawings.

[0015] Furthermore, terms including ordinal numbers such as first and second are used to describe various components, but these terms are used only to distinguish one component from another and do not limit the components.

[0016] [First embodiment] The overall configuration of an isolation transformer 100 according to a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a front view schematically illustrating an example of an isolation transformer 100 according to the first embodiment. This view is partially cut away. FIG. 2 is a bottom view of the isolation transformer 100. For ease of explanation, an XYZ Cartesian coordinate system is defined, with the X-axis representing a horizontal direction, the Y-axis representing a horizontal direction perpendicular to the X-axis direction, and the Z-axis representing a direction perpendicular to both directions, i.e., the vertical direction. The positive directions of the X-axis, Y-axis, and Z-axis are defined as the directions indicated by the arrows in each figure, and the negative directions are defined as the directions opposite the arrows. Note that the X-axis direction is sometimes referred to as the "left-right direction," the Y-axis direction as the "front-back direction," and the Z-axis direction as the "up-down direction." These directional notations do not limit the configuration of the isolation transformer 100; the isolation transformer 100 can be used in any orientation depending on the application.

[0017] The isolation transformer 100 can be used in power supply devices such as AC / DC converters and DC / DC converters. In particular, the isolation transformer 100 can supply AC power to a plurality of power modules (not shown) while being isolated from each other. The isolation transformer 100 may also be mounted on a printed circuit board.

[0018] The isolation transformer 100 includes a transformer body 70, a primary-side connection terminal 84, a plurality of secondary-side connection terminals 88, a first insulating wall portion 11, a second insulating wall portion 12, and a third insulating wall portion 13. The primary-side connection terminal 84 and the secondary-side connection terminal 88 are collectively referred to as "connection terminals 80." The first insulating wall portion 11, the second insulating wall portion 12, and the third insulating wall portion 13 are collectively referred to as "insulating wall portion 10."

[0019] The transformer body 70 includes a core 72, a bobbin 17, a terminal holder 16, a case 78 that covers a portion of the core 72, a primary coil 82, and multiple secondary coils 86. The core 72 is formed into a predetermined shape (e.g., an EI shape) from a soft magnetic material such as ferrite. The bobbin 17 has a shape that surrounds the core 72 and functions as a winding frame for the coil. The terminal holder 16 is connected to the lower end of the bobbin 17 and is a member that is approximately rectangular in plan view. The terminal holder 16 supports a primary side connection terminal 84 and a secondary side connection terminal 88, which will be described later.

[0020] The primary coil 82 and the multiple secondary coils 86 can be made of electric wire coated with a resin or other material having a predetermined insulating property. The primary coil 82 and the multiple secondary coils 86 are wound around the core 72 via a bobbin 17. The primary coil 82 and the multiple secondary coils 86 are magnetically coupled to each other and electrically insulated from each other. In this embodiment, the multiple secondary coils 86 include four mutually insulated secondary coils 86a, 86b, 86c, and 86d (see also FIG. 8). The transformer body 70 is configured to output AC power input to the primary coil 82 to the multiple insulated secondary coils 86. The transformer body 70 may perform voltage transformation.

[0021] The primary side connection terminal 84 is connected to the terminals 82a, 82b of the primary coil 82 and protrudes downward from the transformer body 70. In this embodiment, the primary side connection terminal 84 includes a pair of primary side connection terminals 84a, 84b that are connected to a pair of terminals of the primary coil 82, respectively.

[0022] The secondary side connection terminals 88 are connected to the terminals of the multiple secondary coils 86 and protrude downward from the transformer body 70. In this embodiment, the secondary side connection terminals 88 include a pair of secondary side connection terminals 88a, 88b connected to a pair of terminals 87a, 87b of the secondary coil 86a, a pair of secondary side connection terminals 88c, 88d connected to a pair of terminals 87c, 87d of the secondary coil 86b, a pair of secondary side connection terminals 88e, 88f connected to a pair of terminals 87e, 87f of the secondary coil 86c, and a pair of secondary side connection terminals 88g, 88h connected to a pair of terminals 87g, 87h of the secondary coil 86d.

[0023] The primary-side connection terminal 84 and the secondary-side connection terminal 88 are, for example, pin members having a circular cross section or rectangular end faces, and are made of a conductive material such as copper. As shown in Fig. 2, the primary-side connection terminal 84 and the secondary-side connection terminal 88 are supported by the terminal holder 16 by being embedded and fixed in the terminal holder 16 at their upper portions, and protrude downward from the terminal holder 16 at their lower portions. For example, the primary-side connection terminal 84 and the secondary-side connection terminal 88 may be fixed to the terminal holder 16 by insert molding.

[0024] 1 and 2, the terminals of the primary coil 82 and the secondary coil 86 are housed in guide grooves 16g provided on the outer peripheral surface of the terminal holder 16 and extend from the upper surface to the lower surface of the terminal holder 16. The terminals extended to the lower surface of the terminal holder 16 are wound around the bases of the primary-side connection terminal 84 and the secondary-side connection terminal 88, respectively, and are electrically connected by soldering or the like. A plurality of guide grooves 16g are provided corresponding to the terminals of the primary coil 82 and the secondary coil 86. As shown in FIG. 2, the guide grooves 16g are recessed inward (in the Y-axis direction) from the outer peripheral surface to the bottom of the terminal holder 16 in a bottom view, and the bottoms of the guide grooves 16g are located inside the connection terminals 80.

[0025] The connection terminal holding member 15 will be described with reference to FIG. 3 as well. FIG. 3 is a perspective view of the connection terminal holding member 15. This figure shows the connection terminal holding member 15 in a state in which the primary side connection terminal 84 and the secondary side connection terminal 88 are fixed. The connection terminal holding member 15 of this embodiment includes a bobbin 17, a terminal holding portion 16, a first insulating wall portion 11, a second insulating wall portion 12, and a third insulating wall portion 13. The bobbin 17 has a cylindrical portion 17a around which the primary coil 82 and the multiple secondary coils 86 are wound, and a flange portion 17b. In this example, the bobbin 17, the terminal holding portion 16, the first insulating wall portion 11, the second insulating wall portion 12, and the third insulating wall portion 13 are integrally formed from an insulating material such as bakelite resin.

[0026] (insulating wall) The first insulating wall portion 11 has a shape that increases the extension distance between the primary side connection terminal 84 and the secondary side connection terminal 88. The second insulating wall portion 12 increases the extension distance between the secondary side connection terminals 88 connected to each terminal of one of the multiple secondary coils 86 and the secondary side connection terminals 88 connected to the terminals of the other secondary coils 86. The third insulating wall portion 13 is connected to the first insulating wall portion 11 and the second insulating wall portion 12.

[0027] (First insulating wall portion) The first insulating wall portion 11 includes an insulating wall portion 11a and an insulating wall portion 11b. The insulating wall portion 11a is provided between the primary side connection terminal 84a and the secondary side connection terminal 88a. The insulating wall portion 11b is provided between the primary side connection terminal 84b and the secondary side connection terminal 88h. The following mainly describes the insulating wall portion 11a, but this description also applies to the insulating wall portion 11b, which has the same shape.

[0028] 1, the insulating wall portion 11a is located between the primary connection terminal 84a and the secondary connection terminal 88a and has a shape that protrudes downward from the terminal holding portion 16. In this example, the insulating wall portion 11a has an outer shape whose longitudinal direction extends vertically. The insulating wall portion 11a has a substantially rectangular main surface along a plane perpendicular to the X-axis direction.

[0029] (Second insulating wall) The second insulating wall portion 12 includes an insulating wall portion 12a and an insulating wall portion 12b. The insulating wall portion 12a is provided between the secondary side connection terminal 88b and the secondary side connection terminal 88c. The insulating wall portion 12b is provided between the secondary side connection terminal 88f and the secondary side connection terminal 88g. The following mainly describes the insulating wall portion 12a, but this description also applies to the insulating wall portion 12b, which has the same shape.

[0030] 1, insulating wall portion 12a has a shape that protrudes downward from terminal holding portion 16 between secondary-side connection terminal 88b and secondary-side connection terminal 88c. In this example, insulating wall portion 12a has an outer shape whose longitudinal direction extends vertically. Insulating wall portion 12a has a substantially rectangular main surface along a plane perpendicular to the X-axis direction.

[0031] (Third insulating wall) 2, the third insulating wall portion 13 includes insulating wall portion 13a and insulating wall portion 13b that are spaced apart from each other in the Y-axis direction. Insulating wall portions 13a and 13b extend between both ends of the terminal holder 16 in the X-axis direction. Insulating wall portion 11a and insulating wall portion 12a are connected to insulating wall portion 13a and extend outward from insulating wall portion 13a in the Y-axis direction. Insulating wall portion 11b and insulating wall portion 12b are connected to insulating wall portion 13b and extend outward from insulating wall portion 13b in the Y-axis direction.

[0032] 1, insulating wall portions 13a and 13b are located between secondary-side connection terminals 88a and 88h and protrude downward from terminal holder 16. In this example, insulating wall portions 13a and 13b have rectangular cross sections with their longitudinal directions extending vertically. Insulating wall portions 13a and 13b have substantially rectangular main surfaces aligned along a plane perpendicular to the Y-axis direction.

[0033] As shown in FIG. 2 , when projected onto a plane perpendicular to the up-down direction (illustrated as the first direction), the first insulating wall 11 and the third insulating wall 13 are perpendicular to each other and have an L-shaped configuration surrounding the primary-side connection terminal 84. Similarly, when projected onto a plane perpendicular to the up-down direction, the second insulating wall 12 and the third insulating wall 13 are perpendicular to each other and surround the secondary-side connection terminal 88 in an L-shaped configuration. With this configuration, the third insulating wall 13 can increase the surface distance and spatial distance of the path around the side surfaces of the first insulating wall 11 and the second insulating wall 12. Furthermore, the third insulating wall 13 can reinforce the first insulating wall 11 and the second insulating wall 12.

[0034] 1, the first insulating wall portion 11, the second insulating wall portion 12, and the third insulating wall portion 13 protrude downward beyond the protruding ends of the primary-side connection terminal 84 and the secondary-side connection terminal 88. In this case, the height of the insulating wall portion 10 increases the surface distance and the spatial distance between the connection terminals 80. This reduces the linear distance between the connection terminals 80, making it easy to miniaturize the isolation transformer 100. Furthermore, because the insulating wall portion 10 protrudes beyond the connection terminals 80, the insulating wall portion 10 acts as a guard, reducing the possibility of the connection terminals 80 coming into contact with production equipment or other components and being deformed.

[0035] Next, the surface distance and clearance distance of the isolation transformer 100 alone will be described.

[0036] The front-view projection distance and spatial distance will be described with reference to Fig. 4. Fig. 4 is an enlarged front view of the periphery of the insulating wall portion 10. As shown in Fig. 4, the front-view projection distance Dm1 and spatial distance Ds1 between the primary-side connection terminal 84a and the secondary-side connection terminal 88a when the insulating wall portion 11a is provided are longer than the front-view projection distance Dx1 and spatial distance Dy1 when the insulating wall portion 11a is not provided.

[0037] Furthermore, the front-view surface distance Dm2 and spatial distance Ds2 between the secondary side connection terminal 88b and the secondary side connection terminal 88c when the insulating wall portion 12a is present are longer than the front-view surface distance Dx2 and spatial distance Dy2 when the insulating wall portion 12a is not present.

[0038] The spatial distance as viewed from below will be described with reference to Fig. 5. Fig. 5 is a bottom view showing an enlarged view of the periphery of the insulating wall portion 10. As shown in Fig. 5, the spatial distance Ds3 as viewed from below between the primary-side connection terminal 84a and the secondary-side connection terminal 88a when the insulating wall portion 11a is present is longer than the spatial distance Dy3 when the insulating wall portion 11a is not present. Furthermore, the spatial distance Ds4 as viewed from below between the secondary-side connection terminal 88b and the secondary-side connection terminal 88c when the insulating wall portion 12a is present is longer than the spatial distance Dy4 when the insulating wall portion 12a is not present.

[0039] Next, the surface distance and the clearance distance in the printed circuit board 50 on which the isolation transformer 100 is mounted will be described.

[0040] The front-view projection distance and clearance distance will be described with reference to Figure 6. Figure 6 is a front view showing a printed circuit board 50 on which an isolation transformer 100 is mounted. Connection terminals 80 penetrate the printed circuit board 50, protrude onto the pattern-forming surface 50b, and are soldered to predetermined lands 50d. The insulating wall portion 10 penetrates a through-hole 50h formed in the printed circuit board 50, and protrudes downward from the pattern-forming surface 50b.

[0041] 6, because the insulating wall portion 11a protrudes downward beyond the primary-side connection terminal 84a and the secondary-side connection terminal 88a, the projected distance Dm5 and the spatial distance Ds5 between the primary-side connection terminal 84a and the secondary-side connection terminal 88a in a front view are longer than the projected distance Dx5 and the spatial distance Dy5 when the insulating wall portion 11a does not protrude. Also, because the insulating wall portion 12a protrudes downward beyond the secondary-side connection terminals 88b and 88c, the projected distance Dm6 and the spatial distance Ds6 between the secondary-side connection terminal 88b and the secondary-side connection terminal 88c in a front view are longer than the projected distance Dx6 and the spatial distance Dy6 when the insulating wall portion 12a does not protrude.

[0042] The spatial distance as viewed from below will be described with reference to FIG. 7. FIG. 7 is a bottom view showing a printed circuit board 50 on which an isolation transformer 100 is mounted. As shown in FIG. 7, because of the presence of insulating wall portion 11a, a spatial distance Ds7 as viewed from below between land 50d of primary-side connection terminal 84a and land 50d of secondary-side connection terminal 88a is longer than a spatial distance Dy7 in the absence of insulating wall portion 11a. Furthermore, because of the presence of insulating wall portion 12a, a spatial distance Ds8 as viewed from below between land 50d of secondary-side connection terminal 88b and land 50d of secondary-side connection terminal 88c is longer than a spatial distance Dy8 in the absence of insulating wall portion 12a.

[0043] Next, an example of a power supply circuit including an isolation transformer 100 will be described. Fig. 8 is a block diagram showing an example of a power supply circuit 51 including an isolation transformer 100. In addition to the isolation transformer 100, the power supply circuit 51 includes a primary power supply 52, a switching circuit 53, a first power module 55, a second power module 56, a third power module 57, a fourth power module 58, and a feedback circuit 59. As an example, the first to fourth power modules 55 to 58 may be circuit modules that drive the U, V, W, and N phases of an IPM (Interior Permanent Magnet) motor.

[0044] The primary power supply 52 is, for example, a 24V DC power supply. The switching circuit 53 repeatedly turns on and off the current flowing from the primary power supply 52 to the primary coil 82 using the transistor T53 in a short cycle. By turning on and off the current flowing through the primary coil 82, a secondary voltage is output to the secondary coils 86a, 86b, 86c, and 86d. The first to fourth power modules 55, 56, 57, and 58 are controlled by the secondary voltage output to the secondary coils 86a, 86b, 86c, and 86d. The feedback circuit 59 rectifies the secondary voltage output to the secondary coil 86d and feeds it back to the switching circuit 53. The feedback circuit 59 has a photocoupler (not shown) to ensure insulation between the secondary coil 86d and the switching circuit 53. The switching circuit 53 can adjust the switching timing based on the signal from the feedback circuit 59.

[0045] The features of the isolation transformer 100 configured as described above will be described below. The isolation transformer 100 includes a transformer body 70 having a primary coil 82 and multiple secondary coils 86, a primary-side connection terminal 84 connected to an end of the primary coil 82 and protruding in a first direction from the transformer body 70, multiple secondary-side connection terminals 88 connected to ends of the multiple secondary coils 86 and protruding in the first direction from the transformer body 70, and a first insulating wall portion 11 that increases the extension distance between the primary-side connection terminal 84 and the secondary-side connection terminal 88.

[0046] According to this configuration, the surface distance between the two connection terminals can be increased, and therefore the linear distance between the two connection terminals can be reduced accordingly, thereby enabling the transformer to be made smaller.

[0047] This embodiment includes a second insulating wall portion 12 that increases the extension distance between a secondary side connection terminal 88 connected to each terminal of one of the multiple secondary coils 86 and a secondary side connection terminal 88 connected to the terminal of another of the multiple secondary coils 86. In this case, the extension distance between the two connection terminals can be increased, which shortens the linear distance between the two connection terminals and thereby reduces the size of the transformer.

[0048] This embodiment includes a third insulating wall portion 13 connected to the first insulating wall portion 11 and the second insulating wall portion 12. In this case, the extending distance of the path around the side surfaces of the first insulating wall portion 11 and the second insulating wall portion 12 can be increased. The first insulating wall portion 11 and the second insulating wall portion 12 can be reinforced.

[0049] In this embodiment, when projected onto a plane perpendicular to the first direction, the first insulating wall 11 and the third insulating wall 13 surround the primary connection terminal 84 in an L-shape. In this case, by surrounding the primary connection terminal 84 in an L-shape, the extension distance of the path around the side surface of the first insulating wall 11 can be increased.

[0050] In this embodiment, when projected onto a plane perpendicular to the first direction, the second insulating wall 12 and the third insulating wall 13 surround the secondary connection terminal 88 in an L-shape. In this case, by surrounding the secondary connection terminal 88 in an L-shape, the extension distance of the path around the side surface of the second insulating wall 12 can be increased.

[0051] In this embodiment, the first insulating wall portion 11, the second insulating wall portion 12, and the third insulating wall portion 13 protrude in the first direction beyond the protruding ends of the primary-side connection terminals 84. In this case, when the isolation transformer 100 is mounted on the printed circuit board 50, the extension distance between the connection terminals 80 in the areas protruding from the printed circuit board 50 can be increased.

[0052] [Second embodiment] A second embodiment of the present disclosure is a connection terminal holding member 15 for an isolation transformer. The connection terminal holding member 15 is provided in an isolation transformer 100 having one coil (primary coil 82) and another coil (secondary coil 86) that are insulated from each other, and is a connection terminal holding member that holds one connection terminal (primary side connection terminal 84) connected to an end of the one coil (primary coil 82) and another connection terminal (secondary side connection terminal 88) connected to an end of the other coil (secondary coil 86), and includes an insulating wall portion (first insulating wall portion 11) that increases the extension distance between the one connection terminal (primary side connection terminal 84) and the other connection terminal (secondary side connection terminal 88).

[0053] According to this embodiment, the same actions and effects as those of the first embodiment are achieved.

[0054] The above describes in detail examples of embodiments of the present invention. The above-described embodiments merely illustrate specific examples of implementing the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes, such as changes, additions, and deletions of components, are possible within the scope of the inventive concept defined in the claims. In the above-described embodiments, content that allows such design changes is described using notations such as "in the embodiment" or "in the embodiment," but this does not mean that design changes are not permitted in content that does not have such notations.

[0055] (Variation) The following describes the modified examples. In the drawings and descriptions of the modified examples, the same components and members as those in the first embodiment are denoted by the same reference numerals. Explanations that overlap with those in the first embodiment will be omitted as appropriate, and the following description will focus on the configurations that differ from those in the first embodiment.

[0056] In the description of the first embodiment, an example in which four secondary coils 86a to 86d are provided is shown, but the number of secondary coils may be one to three, or five or more.

[0057] In the description of the first embodiment, an example was shown in which the connection terminal holding member 15 is integrally formed with the bobbin 17, the terminal holding portion 16, the first insulating wall portion 11, the second insulating wall portion 12, and the third insulating wall portion 13, but these may also be formed separately.

[0058] In the description of the first embodiment, an example was shown in which the primary side connection terminal 84 and the secondary side connection terminal 88 are fixed to the terminal holding portion 16 by insert molding, but these connection terminals may also be fixed to the terminal holding portion 16 by another fixing method, such as press-fitting or bonding.

[0059] These modifications each provide the same functions and effects as the first embodiment.

[0060] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present disclosure. A new embodiment resulting from the combination has the combined effects of the combined embodiments and modifications. [Explanation of symbols]

[0061] 11 First insulating wall portion, 12 Second insulating wall portion, 13 Third insulating wall portion, 15 Connection terminal holding member, 50 Printed circuit board, 70 Transformer body, 82 Primary coil, 84 Primary side connection terminal, 86 Secondary coil, 88 Secondary side connection terminal, 100 Isolation transformer.

Claims

1. a transformer body having a primary coil and a plurality of secondary coils wound on a bobbin; a primary side connection terminal connected to an end of the primary coil and protruding from the transformer body in a first direction; a plurality of secondary side connection terminals connected to terminals of the plurality of secondary coils and protruding from the transformer body in a first direction; a terminal holding portion extending along a plane perpendicular to the first direction and projecting outward from a base of the bobbin, the terminal holding portion being disposed adjacent to a printed circuit board on which the isolation transformer is mounted, the terminal holding portion having the primary side connection terminals and the secondary side connection terminals embedded therein; a first insulating wall portion formed integrally with the bobbin and the terminal holding portion and protruding from the terminal holding portion in a first direction beyond a protruding end of the primary side connection terminal; Equipped with the first insulating wall portion increases a creepage distance between the primary side connection terminal and the secondary side connection terminal, a second insulating wall portion that increases a creepage distance between a secondary side connection terminal connected to each terminal of one of the plurality of secondary coils and a secondary side connection terminal connected to each terminal of another of the plurality of secondary coils, a third insulating wall portion connected to the first insulating wall portion and the second insulating wall portion; When projected onto a plane perpendicular to a first direction, the first insulating wall portion and the third insulating wall portion are perpendicular to each other and have an L-shaped shape surrounding the primary side connection terminal.

2. 2 . The isolation transformer according to claim 1 , wherein the second insulating wall portion and the third insulating wall portion surround the secondary side connection terminal in an L-shape when projected onto a plane perpendicular to the first direction.

3. 3. The isolation transformer according to claim 1, wherein the second insulating wall portion and the third insulating wall portion protrude in the first direction beyond the protruding end of the primary side connection terminal.

4. 2. The isolation transformer according to claim 1, wherein the first insulating wall portion penetrates a through-hole formed in a printed circuit board on which the isolation transformer is mounted and protrudes toward a pattern formation surface on a first direction side, thereby increasing a creepage distance between the primary connection terminal and the secondary connection terminal on the pattern formation surface.

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