Power conversion device

Abstract

To suppress a change of a gap caused by resin pressure when a secondary molded body is formed in a power conversion device having a magnetic material core provided with the gap.SOLUTION: A power conversion device includes: magnetic material cores 30 having gaps G formed by cutting out parts of annular shapes; a primary molded body 21 made of resin, which covers first end parts 31 and second end parts 32 of the magnetic material cores 30, which are arranged to face each other with the gap G therebetween from an outer side in a radial direction of the magnetic material cores 30 and holds the magnetic material cores 30; and a secondary molded body 22 made of resin, which has exposure parts 22b for exposing a surface of an upper wall part 21a which covers the first end parts 31 and the second end parts 32 of the primary molded body 21 and contains the primary molded body 21.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power conversion device.

Background Art

[0002] In vehicles such as electric vehicles, a power conversion device (PCU: Power Control Unit) is provided between a battery and a motor. Such a power conversion device includes a plurality of semiconductor power chips and a power module case that houses these power chips. The power module case contains a bus bar that serves as an electric transmission path. Patent Document 1 discloses a power conversion device including a current sensor for detecting a current flowing through such a bus bar.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the above-described current sensor includes a magnetic core. The magnetic core is formed in a C-shaped annular shape provided with a gap for arranging a Hall element. When manufacturing a power conversion device, for example, it is conceivable to perform insert molding in which the magnetic core is held by a resin primary molded body and a resin secondary molded body is formed so as to enclose the primary molded body holding the magnetic core. However, when the secondary molded body is injection molded, the gap distance of the magnetic core may change due to the pressure received from the molten resin. If the gap distance of the magnetic core changes with respect to the design value, the performance of the current sensor will deteriorate.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to prevent a gap from changing due to resin pressure during the formation of a secondary molded body in a power conversion device having a magnetic core provided with a gap.

Means for Solving the Problems

[0006] As means for solving the above problems, the present invention adopts the following configuration.

[0007] A first aspect is a power conversion device including a magnetic core having a gap formed by cutting out a part of an annular shape, and a resin-made primary molded body that covers the first end portion and the second end portion of the magnetic core disposed to face each other with the gap therebetween from the radially outer side of the magnetic core to hold the magnetic core, and a resin-made secondary molded body that has an exposed portion that exposes the surfaces of the portions covering the first end portion and the second end portion of the primary molded body and encloses the primary molded body.

[0008] A second aspect is, in the first aspect, the configuration in which the primary molded body has groove portions that expose a first end face exposed in the gap of the first end portion and a second end face exposed in the gap of the second end portion.

[0009] A third aspect is, in the second aspect, the configuration in which the secondary molded body has a fitting wall portion extending from an inner wall surface on the first end face side of the groove portion to an inner wall surface on the second end face side in a state where the first end face and the second end face are exposed.

[0010] A fourth aspect is, in the second or third aspect, the configuration in which the secondary molded body has claw portions that are locked from the radially outer side to the radially inner side on the surface of the primary molded body.

[0011] According to a fifth aspect, in any one of the first to fourth aspects, a fastening structure to which an end portion of a bus bar inserted radially inward of the magnetic core is fastened is provided, and the fastening structure is held by the primary molded body and disposed adjacent to the magnetic core.

Advantages of the Invention

[0012] In the power conversion device of the present invention, the primary molded body has a portion that covers the first end portion and the second end portion of the magnetic core from the radially outer side of the magnetic core. Further, in the secondary molded body, the secondary molded body that encloses the primary molded body has an exposed portion that exposes the surface of the portion. Therefore, according to the present invention, when the secondary molded body is formed, the molten resin does not hit the portion of the primary molded body that covers the first end portion and the second end portion. Therefore, it is possible to prevent the pressure of the molten resin from acting on the first end portion and the second end portion of the magnetic core, and it is possible to prevent the gap provided between the first end portion and the second end portion from being deformed. Therefore, according to the present invention, in a power conversion device having a magnetic core provided with a gap, it is possible to prevent the gap from changing due to the resin pressure during the formation of the secondary molded body.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0014] Hereinafter, with reference to the drawings, an embodiment of a power conversion device according to the present invention will be described.

[0015] (First Embodiment) FIG. 1 is an exploded perspective view showing a schematic configuration of a power conversion device 1 according to this embodiment. The power conversion device 1 is mounted on a vehicle such as an electric vehicle and is provided between a motor (load) (not shown) and a battery. As shown in FIG. 1, such a power conversion device 1 includes an intelligent power module 2, a capacitor 3, a reactor 4, a DCDC converter 5, and a main body case 6.

[0016] The intelligent power module 2 includes a power module 10, a circuit board 11, etc. The power module 10 includes a plurality of power devices 10a having power semiconductor elements, a resin-made power module case 10b that houses these power devices 10a, and a bus bar 10c connected to the power devices 10a. Further, the power module 10 includes a water jacket for cooling or the like. This power module 10 will be described in more detail later.

[0017] The circuit board 11 is a board provided with a gate driver that generates drive signals for a buck-boost converter or an inverter formed by the power device 10a, an ECU (Electronic Control Unit) that controls the gate driver, etc. Such a circuit board 11 is laminated on the power module 10. Note that a plurality of hall elements (not shown), which are part of a current sensor for measuring the current flowing through the bus bar 10c, are mounted on the circuit board 11. Each hall element is disposed in a gap G of a magnetic core 30, which will be described later, held by the power module case 10b.

[0018] The capacitor 3 is connected to the intelligent power module 2 and is arranged on the side of the power module 10. The reactor 4 of the present embodiment is arranged below the intelligent power module 2. The configuration of the reactor 4 of the present embodiment will be described in detail later. The DCDC converter 5 is on the side of the reactor 4 and is arranged below the intelligent power module 2. The DCDC converter 5 converts the battery power into a voltage suitable for surrounding electronic components (such as electronic components mounted on the circuit board 11).

[0019] The main body case 6 is a case that houses the intelligent power module 2, the capacitor 3, the reactor 4, and the DCDC converter 5, and includes an upper case 6a, a central case 6b, and a lower case 6c. These upper case 6a, central case 6b, and lower case 6c are connected so as to be dividable in the stacking direction of the power module 10 and the circuit board 11. The upper case 6a covers the intelligent power module 2 from the circuit board 11 side and is fastened to the central case 6b. The central case 6b covers the periphery of the intelligent power module 2, the capacitor 3, the reactor 4, and the DCDC converter 5. The lower case 6c covers the reactor 4 and the DCDC converter 5 from below, and is provided with a connection connector for connecting the intelligent power module 2 and a motor (not shown), and is fastened to the central case 6b.

[0020] Subsequently, the power module 10 will be described in more detail. FIG. 2 is a plan view showing a part of the power module 10. In FIG. 2, the bus bar 10c of the power module 10 is omitted from the illustration. FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2. FIG. 4(a) is a cross-sectional view taken along line B-B of FIG. 3, and FIG. 4(b) is a cross-sectional view taken along line C-C of FIG. 3.

[0021] As shown in these figures, the power module case 10b of the power module 10 includes a primary molded body 21 and a secondary molded body 22. The primary molded body 21 is a molded body formed of resin, and holds, for example, a magnetic core 30, a reinforcing resin part 40, and a fastening nut 50 (fastening structure) as shown in FIG. 3.

[0022] Here, the magnetic core 30 is an annular member formed of a magnetic material. More specifically, the magnetic core 30 is formed in a C shape having a gap G formed by cutting out a part of the annular shape as shown in FIG. 3. This magnetic core 30 forms part of a current sensor together with a hall element (not shown) disposed in the gap G.

[0023] In such a magnetic core 30, the gap G is provided so as to penetrate the magnetic core 30 in the radial direction. Further, the magnetic core 30 is formed in a shape having a first end portion 31 and a second end portion 32 disposed to face each other with the gap G interposed therebetween. Note that the surface of the first end portion 31 facing the gap G is referred to as a first end face 33, and the surface of the second end portion 32 facing the gap G is referred to as a second end face 34. That is, the magnetic core 30 is formed in an annular shape with the gap G provided between the first end face 33 of the first end portion 31 and the second end face 34 of the second end portion 32.

[0024] A plurality of magnetic cores 30 are provided by arranging one magnetic core 30 for each bus bar 10c. Each magnetic core 30 is arranged such that the gap G faces the circuit board 11 side when viewed from the direction along the axial center of the annular shape (the direction perpendicular to the paper surface of FIG. 3).

[0025] The reinforcing resin part 40 is a resin member having higher rigidity than the primary molded body 21, and is provided at each of the first end portion 31 and the second end portion 32 of the magnetic core 30. The reinforcing resin part 40 provided for the first end portion 31 is provided so as to cover the first end portion 31 in a state where the first end face 33 is exposed. The reinforcing resin part 40 provided for the second end portion 32 is provided so as to cover the second end portion 32 in a state where the second end face 34 is exposed.

[0026] As shown in FIG. 3, the fastening nut 50 is arranged adjacent to the side of the magnetic core 30. A plurality of fastening nuts 50 are provided by being arranged for each magnetic core 30 (that is, the bus bar 10c). The end of the bus bar 10c is fastened to these fastening nuts 50 by bolts (not shown). Each fastening nut 50 is a nut made of metal with higher rigidity than the primary molded body 21 and the secondary molded body 22.

[0027] As shown in FIG. 3, the primary molded body 21 holds the magnetic core 30 so as to cover it from the radial direction. Such a primary molded body 21 has an upper wall portion 21a that covers the first end portion 31 and the second end portion 32 of the magnetic core 30 from the outside in the radial direction. This upper wall portion 21a is a portion that covers the first end portion 31 and the second end portion 32 of the primary molded body 21. The outer wall surface 21b of the upper wall portion 21a faces the circuit board 11 side and is formed flat. The outer wall surface 21b of this upper wall portion 21a is an exposed surface where a large range is not covered by the secondary molded body 22.

[0028] Further, the upper wall portion 21a of the primary molded body 21 has a plurality of groove portions 21c provided in accordance with the gap G of the magnetic core 30. These groove portions 21c are formed to a depth that reaches the gap G from the outer wall surface 21b, and expose the first end surface 33 and the second end surface 34 of the magnetic core 30. Hall elements (not shown) mounted on the circuit board 11 are inserted into each of these groove portions 21c.

[0029] In addition, such a primary molded body 21 is provided with a plurality of pads to which the power device 10a is connected and conductive members (not shown) such as connection pins for connecting the pads and the circuit board 11. Such a primary molded body 21 is enclosed in the secondary molded body 22 and provided integrally with the secondary molded body 22. Such a primary molded body 21 is formed by injection molding in which molten resin is injected into the mold and cooled. For example, a primary molded body 21 having recesses for fitting the magnetic core 30, the reinforcing resin portion 40, and the fastening nut 50 is formed by injection molding, and after molding, the magnetic core 30, the reinforcing resin portion 40, and the fastening nut 50 are fitted into these recesses.

[0030] The secondary molded body 22 is a resin molded body that encloses the primary molded body 21. As shown in FIG. 2, it has a plurality of accommodation recesses 22a and the like for accommodating the power device 10a. Further, the secondary molded body 22 has a fixing portion (not shown) and the like that is fixed to the main body case 6. Further, in the present embodiment, the secondary molded body 22 has an exposed portion 22b, a claw portion 22c, and a fitting wall portion 22d, for example, as shown in FIG. 2.

[0031] The exposed portion 22b is a portion that exposes the outer wall surface 21b of the upper wall portion 21a provided on the primary molded body 21. That is, in the present embodiment, the secondary molded body 22 encloses the primary molded body 21 with a large range of the outer wall surface 21b being exposed.

[0032] The claw portion 22c is a portion that is locked to the outer wall surface 21b of the upper wall portion 21a provided on the primary molded body 21, and a plurality of claw portions 22c are provided. Each claw portion 22c is locked so as to abut from the radially outer side to the radially inner side of the magnetic core 30 on the outer wall surface 21b which is the surface of the primary molded body 21.

[0033] Although the contact area between the primary molded body 21 and the secondary molded body 22 is reduced by providing the exposed portion 22b, the joining strength between the primary molded body 21 and the secondary molded body 22 can be maintained by locking the claw portion 22c to the upper wall portion 21a of the primary molded body 21.

[0034] The fitting wall portion 22d is a wall portion arranged so as to fit into the groove portion 21c of the primary molded body 21. As shown in FIG. 4(b), the fitting wall portion 22d is arranged in the groove portion 21c with the first end face 33 of the magnetic core 30 being exposed. Similarly, the fitting wall portion 22d is arranged in the groove portion 21c with the second end face 34 of the magnetic core 30 being exposed.

[0035] Further, as shown in FIGS. 2 and 3, the fitting wall portion 22d is formed with a width dimension extending from the inner wall surface on one side of the groove portion 21c to the inner wall surface on the other side. That is, the fitting wall portion 22d has a width dimension extending from the inner wall surface on the first end face 33 side to the inner wall surface on the second end face 34 side.

[0036] Although the contact area between the primary molded body 21 and the secondary molded body 22 is reduced by providing the exposed portion 22b, the fitting wall portion 22d is fitted into the groove portion 21c, so that the bonding strength between the primary molded body 21 and the secondary molded body 22 can be maintained.

[0037] Such a secondary molded body 22 is formed by injection molding in which the primary molded body 21 holding the magnetic core 30 or the like is disposed inside a mold, and a molten resin is injected into the mold and cooled. That is, the power module case 10b having the primary molded body 21 and the secondary molded body 22 is formed by insert molding.

[0038] The power conversion device 1 according to the present embodiment as described above includes a magnetic core 30 having a gap G formed by cutting out a part of an annular shape. The power conversion device 1 also includes a resin primary molded body 21 and a resin secondary molded body 22. The primary molded body 21 covers the first end portion 31 and the second end portion 32 of the magnetic core 30 disposed to face each other with the gap G therebetween from the radially outer side of the magnetic core 30 to hold the magnetic core 30. The secondary molded body 22 has an exposed portion 22b that exposes the outer wall surface 21b of the upper wall portion 21a that covers the first end portion 31 and the second end portion 32 of the primary molded body 21, and encloses the primary molded body 21.

[0039] Such a power conversion device 1 of the present embodiment has an upper wall portion 21a in which the primary molded body 21 covers the first end portion 31 and the second end portion 32 of the magnetic core 30 from the outside in the radial direction of the magnetic core 30. Further, in the secondary molded body 22, the secondary molded body 22 that encloses the primary molded body 21 has an exposed portion 22b that exposes the outer wall surface 21b of the upper wall portion 21a. Therefore, according to the power conversion device 1 of the present embodiment, when forming the secondary molded body 22, the molten resin does not hit the upper wall portion 21a of the primary molded body 21 that covers the first end portion 31 and the second end portion 32.

[0040] Therefore, in the power conversion device 1 of the present embodiment, it is possible to prevent the pressure of the molten resin from acting on the first end portion 31 and the second end portion 32 of the magnetic core 30. For this reason, it is possible to prevent the gap G provided between the first end portion 31 and the second end portion 32 from deforming. Therefore, according to the power conversion device 1 of the present embodiment, in the power conversion device having the magnetic core 30 provided with the gap G, it is possible to prevent the gap G from changing due to the resin pressure during the formation of the secondary molded body 22.

[0041] Further, in the power conversion device 1 of the present embodiment, the primary molded body 21 has a groove portion 21c that exposes the first end surface 33 exposed to the gap G of the first end portion 31 and the second end surface 34 exposed to the gap G of the second end portion 32. According to such a power conversion device 1 of the present embodiment, by inserting a Hall element into the groove portion 21c, it becomes possible to arrange the Hall element and the end surfaces (the first end surface 33 and the second end surface 34) of the magnetic core 30 in close proximity without any obstacles.

[0042] Also, in the power conversion device 1 of the present embodiment, the secondary molded body 22 has a fitting wall portion 22d extending from the inner wall surface on the first end surface 33 side to the inner wall surface on the second end surface 34 side of the groove portion 21c with the first end surface 33 and the second end surface 34 exposed. In such a power conversion device 1 of the present embodiment, the contact area between the primary molded body 21 and the secondary molded body 22 is reduced by providing the exposed portion 22b. On the other hand, the claw portion 22c is locked to the upper wall portion 21a of the primary molded body 21, so that the joining strength between the primary molded body 21 and the secondary molded body 22 can be maintained.

[0043] Also, in the power conversion device 1 of the present embodiment, the secondary molded body 22 has a claw portion 22c that is locked from the outside in the radial direction to the inside in the radial direction of the magnetic core 30 on the surface of the primary molded body 21. In such a power conversion device 1 of the present embodiment, the contact area between the primary molded body 21 and the secondary molded body 22 is reduced by providing the exposed portion 22b. However, since the fitting wall portion 22d is fitted into the groove portion 21c, the joining strength between the primary molded body 21 and the secondary molded body 22 can be maintained.

[0044] Also, the power conversion device 1 of the present embodiment has a fastening nut 50 to which the end portion of the bus bar 10c inserted into the inner side in the radial direction of the magnetic core 30 is fastened. Further, the fastening nut 50 is held by the primary molded body 21 and is arranged adjacent to the magnetic core 30. According to such a power conversion device 1 of the present embodiment, the fastening nut 50 having higher rigidity than the primary molded body 21 is held by the primary molded body 21. Therefore, it is possible to reinforce the rigidity near the magnetic core 30 of the primary molded body 21 with the fastening nut 50. Therefore, according to the power conversion device 1 of the present embodiment, it is possible to more reliably suppress the change in the gap G due to the resin pressure during the formation of the secondary molded body 22.

[0045] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 5. In the description of the present embodiment, the description of the same parts as those in the first embodiment above will be omitted or simplified.

[0046] FIG. 5 is a cross-sectional view at the same position as FIG. 3 of the power module included in the power conversion device of the present embodiment. As shown in this figure, in the power conversion device of the present embodiment, the fastening nut 50 provided in the power conversion device 1 of the first embodiment is not provided.

[0047] It is also possible to adopt a configuration that does not include such a fastening nut 50. Even when such a configuration is adopted, the primary molded body 21 has an upper wall portion 21a that covers the first end portion 31 and the second end portion 32 of the magnetic core 30 from the outside in the radial direction of the magnetic core 30. Further, the secondary molded body 22 has an exposed portion 22b where the secondary molded body 22 that encloses the primary molded body 21 exposes the outer wall surface 21b of the upper wall portion 21a. Therefore, according to the power conversion device of the present embodiment, as in the power conversion device 1 of the first embodiment, when the secondary molded body 22 is formed, the molten resin does not hit the upper wall portion 21a of the primary molded body 21 that covers the first end portion 31 and the second end portion 32.

[0048] Therefore, also in the power conversion device of the present embodiment, it is possible to prevent the pressure of the molten resin from acting on the first end portion 31 and the second end portion 32 of the magnetic core 30, and it is possible to prevent the gap G provided between the first end portion 31 and the second end portion 32 from deforming.

[0049] As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings. Needless to say, the present invention is not limited to the above embodiments. The various shapes and combinations of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention.

[0050] For example, in the above embodiment, the configuration in which the secondary molded body 22 has the claw portion 22c and the fitting wall portion 22d has been described. However, the present invention is not limited to this. The present invention can also adopt a configuration in which the secondary molded body 22 does not include either or both of the claw portion 22c and the fitting wall portion 22d.

[0051] In addition, in the above embodiment, the configuration including the reinforcing resin portion 40 has been described. By providing such a reinforcing resin portion 40, deformation of the gap G of the magnetic core 30 can be suppressed. However, the present invention is not limited to this, and a configuration without the reinforcing resin portion 40 can also be adopted.

Explanation of Reference Numerals

[0052] 1... Power conversion device, 10... Power module, 10a... Power device, 10b... Power module case, 10c... Bus bar, 11... Circuit board, 21... Primary molded body, 21a... Upper wall portion (part), 21b... Outer wall surface (surface), 21c... Groove portion, 22... Secondary molded body, 22a... Accommodating recess, 22b... Exposed portion, 22c... Claw portion, 22d... Fitting wall portion, 30... Magnetic core, 31... First end portion, 32... Second end portion, 33... First end face, 34... Second end face, 40... Reinforcing resin portion, 50... Fastening nut (fastening structure), G... Gap

Claims

1. A power conversion device comprising: a magnetic core having a gap formed by cutting out a part of an annular shape; a resin primary molded body that covers the first end portion and the second end portion of the magnetic core disposed to face each other with the gap therebetween from the radially outer side of the magnetic core to hold the magnetic core; and a resin secondary molded body that has an exposed portion for exposing the surfaces of the portions covering the first end portion and the second end portion of the primary molded body and encapsulates the primary molded body provided with: the primary molded body has a wall portion that is a portion covering the first end portion and the second end portion; the exposed portion exposes an outer wall surface of the wall portion of the primary molded body when viewed from the radially outer side of the magnetic core A power conversion device characterized by the above.

2. The power conversion device according to claim 1, wherein the primary molded body has a groove portion for exposing a first end surface exposed in the gap of the first end portion and a second end surface exposed in the gap of the second end portion.

3. The power conversion device according to claim 2, wherein the secondary molded body has a fitting wall portion extending from an inner wall surface on the first end surface side to an inner wall surface on the second end surface side of the groove portion with the first end surface and the second end surface exposed.

4. The power conversion device according to claim 2 or 3, wherein the secondary molded body has a claw portion that is locked from the radially outer side to the radially inner side of the surface of the primary molded body.

5. having a fastening structure to which an end portion of a bus bar inserted radially inside the magnetic core is fastened; the fastening structure is held by the primary molded body and disposed adjacent to the magnetic core A power conversion device according to any one of claims 1 to 4, characterized by the above.

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