Power conversion unit

Abstract

To provide a power conversion unit that cools a semiconductor module with a heat sink and suppresses the effects of heat on a capacitor.SOLUTION: The power conversion unit includes a semiconductor module, a heat sink, a capacitor, a conductor, and a heat conduction member. The heat sink mounts the semiconductor module on a module mounting surface. The capacitor is arranged outside the heat sink when viewed from the normal direction of the module mounting surface. The conductor connects the semiconductor module and the capacitor. The heat conduction member extends from the heat sink to the capacitor side when viewed from the normal direction of the module mounting surface and is arranged opposite the capacitor.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Embodiments of the present invention relate to a power conversion unit.

Background Art

[0002] Conventionally, in a power conversion unit including a semiconductor module such as an IGBT (Insulated Gate Bipolar Transistor) module and a smoothing capacitor, a configuration in which the semiconductor module is mounted on a heat sink for cooling has been known. However, when the mounting density of components increases due to miniaturization of the device, there is a problem that in the case of self-cooling, it is likely to be affected by deterioration of convection and heat from other components. In particular, a configuration for suppressing the influence of the heat of the capacitor on the semiconductor module mounted on the heat sink has been demanded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a power conversion unit that can cool a semiconductor module with a heat sink and suppress the influence of the heat of a capacitor.

Means for Solving the Problems

[0005] The power conversion unit of the embodiment includes a semiconductor module, a heat sink, a capacitor, a conductor, and a heat conduction member. The heat sink mounts the semiconductor module on the module mounting surface. The capacitor is disposed outside the heat sink when viewed from the normal direction of the module mounting surface. The conductor connects the semiconductor module and the capacitor. The heat conduction member extends from the heat sink toward the capacitor side when viewed from the normal direction of the module mounting surface and is disposed opposite to the capacitor.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0007] Hereinafter, the power conversion unit 1 of the embodiment will be described with reference to the drawings. In some cases, the same or corresponding components may be denoted by the same reference numerals and repeated descriptions may be omitted.

[0008] (Power Conversion Unit 1) FIG. 1 is a perspective view of the power conversion unit 1 of the embodiment as viewed obliquely from above, and FIG. 2 is a perspective view of the power conversion unit 1 of the embodiment as viewed obliquely from above. The power conversion unit 1 of the embodiment includes a semiconductor module 2 containing a semiconductor element such as an IGBT, a heat sink 6 such as a water-cooled one on which the semiconductor module 2 is mounted, a plurality (a pair) of smoothing capacitors, a heat conduction member 16 extending from the heat sink 6 to the capacitor side, a pressing member 21 for fixing the capacitor 11 to the heat conduction member 16, and a conductor 26 for connecting the semiconductor module 2 to the capacitor 11.

[0009] For convenience of explanation, in the figures, the arrow Y is in the front-rear direction, the arrow X is in the left-right direction, and the arrow Z is in the up-down direction. Also, in the figures, the arrow FR indicates the front in the Y direction, the arrow LH indicates the left in the X direction, and the arrow UP indicates the up in the Z direction. The directions such as front, rear, left, and right of the embodiment do not limit the arrangement of the power conversion unit 1.

[0010] FIG. 3 is a side view of the power conversion unit 1 viewed from the left-right direction, and FIG. 4 is a cross-sectional view taken along line A-A of FIG. 3. Referring to FIGS. 3 and 4 together, the semiconductor module 2 includes a flat base 3 with a reduced thickness in the front-rear direction, and a conductor connection portion 4 protruding from one side surface of the base 3 in the front-rear direction. The semiconductor module 2 is exemplified by, for example, an IGBT (Insulated Gate Bipolar Transistor) module.

[0011] The base 3 has a rectangular flat plate shape when viewed from the front-rear direction. The upper and lower sides 3a and 3b of the rectangular shape when viewed from the front-rear direction of the base 3 are arranged along the left-right direction, and the left and right sides 3c and 3d are arranged along the up-down direction. The base 3 is arranged with the thickness direction along the front-rear direction. The front and rear surfaces of the base 3 are arranged perpendicular to the front-rear direction. Fixing portions 3g for fixing to the heat sink 6 with screws or the like are provided at the four corners of the base 3. The conductor connection portions 4 are provided in a plurality in the up-down direction, for example, at the left-right center portion on one side surface of the base 3 in the front-rear direction. Conductors 26 for connection to the capacitor 11 are fixed to each conductor connection portion 4 with screws or the like.

[0012] The heat sink 6 includes a heat sink body 7 formed of a metal material such as an aluminum alloy with high thermal conductivity (thermal conductivity). The heat sink body 7 has a rectangular flat plate shape that is slightly larger in size than the base 3 of the semiconductor module 2 when viewed from the front-rear direction. The heat sink body 7 has a flat shape with a reduced thickness in the front-rear direction. The heat sink body 7 is arranged with the upper and lower sides 7a, 7b of the rectangular shape viewed from the front-rear direction along the left-right direction, and the left and right sides 7c, 7d along the up-down direction. The heat sink body 7 is arranged with the thickness direction along the front-rear direction. The front and rear surfaces of the heat sink body 7 in the front-rear direction are arranged perpendicular to the front-rear direction.

[0013] One side surface of the heat sink body 7 in the front-rear direction, leaving a certain width on the outer peripheral side, is a module mounting surface (module mounting area) 8 for mounting the semiconductor module 2. The heat sink body 7 is, for example, a water-cooled type in which cooling water circulates. On one of the left and right sides 7c, 7d of the heat sink body 7 (for example, the left side 7c), a water supply nozzle 7g for introducing cooling water into the flow path in the heat sink body 7 and a drain nozzle 7h for discharging cooling water from the flow path in the heat sink body 7 are respectively projected. The heat sink 6 is not limited to water cooling, and may flow a refrigerant (including gas) other than cooling water, or may be air-cooled.

[0014] The conductor 26 has a rectangular flat plate shape that is longer downward than the base 3 of the semiconductor module 2 when viewed from the front-rear direction. The conductor 26 is configured by, for example, overlapping a pair of metal plates 27 that are thinner than the base 3 of the semiconductor module 2 and the heat sink 6 in the front-rear direction. At the lower end portion of the conductor 26, a connection portion 28 connected to the terminal portion 13 of the capacitor 11 is formed by bending. The connection portion 28 is connected to the terminal of the upper end portion 17 of the capacitor 11.

[0015] Figure 5 is a cross-sectional view taken along line B-B of Figure 4. The capacitor 11 is disposed below the semiconductor module 2. The capacitor 11 includes, for example, a columnar capacitor body 12 with its axial direction along the vertical direction. In FIGS. 1 and 2, the capacitor 11 is configured by arranging a pair of capacitor bodies 12 side by side left and right. Thereby, while ensuring the capacitance of the capacitor 11, the thickness in the front-rear direction is suppressed. The center line in the figure indicates the central axis C1 of the capacitor body 12. Note that, as shown in FIGS. 4 and 5, the capacitor 11 may be configured to include a single columnar capacitor body 12. Further, the capacitor body 12 is not limited to a columnar outer shape.

[0016] The heat conduction member 16 has a rectangular flat plate shape that continues below the heat sink 6 when viewed from the front-rear direction. The heat conduction member 16 is arranged with the upper and lower sides 16a and 16b of the rectangular shape viewed from the front-rear direction along the left-right direction and the left and right sides 16c and 16d along the vertical direction. The upper end portion 17 of the heat conduction member 16 is detachably coupled to the lower end portion (recess 9 described later) of the heat sink 6 by fastening or the like. The heat conduction member 16 may be non-detachably coupled to the heat sink 6 by welding or the like. The heat conduction member 16 is formed of an aluminum alloy as a metal material with high thermal conductivity. The heat conduction member 16 may be integrally formed of the same material as the heat sink 6. The heat conduction member 16 is arranged close to the heat sink 6 from the rear. The heat conduction member 16 is arranged to face the heat sink 6 from the rear.

[0017] The pressing member 21 has a rectangular parallelepiped outer shape that overlaps the heat conduction member 16 when viewed from the front-rear direction. The pressing member 21 is formed of an aluminum alloy as a metal material with high thermal conductivity, for example, similar to the heat conduction member 16. The pressing member 21 has a case shape that covers the entire capacitor 11. The pressing member 21 exposes only the terminal portion 13 of the capacitor 11 to the outside, enabling the connection of the conductor 26. The pressing member 21 forms, for example, a columnar accommodation space 21a capable of accommodating the capacitor body 12.

[0018] The rear surface 21f of the pressing member 21 is a first contact surface 23a that is in surface contact with the front surface 16e of the heat conduction member 16. The front surface 16e of the heat conduction member 16 is a planar opposing surface that overlaps the entire capacitor 11 when viewed from the normal direction of the module mounting surface 8 (see FIG. 4). The inner surface that forms the accommodation space 21a of the pressing member 21 is a second contact surface 23b that is in surface contact with the outer peripheral surface of the capacitor body 12. The cylindrical outer peripheral surface of the capacitor body 12 overlaps the front surface 16e of the heat conduction member 16 when viewed from the normal direction of the module mounting surface 8.

[0019] When the pressing member 21 is in surface contact with the capacitor body 12 and the heat conduction member 16 respectively, the heat generated by the capacitor body 12 is easily transmitted to the pressing member 21 and further easily transmitted to the heat conduction member 16. The heat transmitted to the heat conduction member 16 is radiated well in the heat sink 6. Therefore, the cooling performance of the capacitor 11 and thus the cooling performance of the entire power conversion unit 1 are improved. Heat conduction grease may be applied to each of the contact surfaces 23a, 23b to enhance the adhesion.

[0020] The pressing member 21 that covers the entire capacitor 11 also functions as a shield member that blocks the radiated noise generated by the capacitor 11. This makes it easier to protect the supplies arranged around the capacitor (for example, the substrate 24 attached to the front surface of the pressing member 21, etc.).

[0021] The pressing member 21 is divided into front and rear divided bodies 22, 23 along, for example, a dividing surface 21b along the axis of the accommodation space 21a, making the capacitor body 12 detachable. The pressing member 21 is attached so as to sandwich the capacitor 11 and is fixed to the heat conduction member 16 by fastening or the like in a state where the capacitor 11 is fixed. The pressing member 21 may be detachably coupled to the heat conduction member 16 (or the heat sink 6) by welding or the like. The pressing member 21 may be integrally formed of the same material as the heat conduction member 16 (and thus the heat sink 6).

[0022] For example, the pressing member 21 may be composed only of the rear split body 23 on the side of the heat conduction member 16, and may have a first contact surface 23a that contacts the outer peripheral surface of the front half circumference of the capacitor 11 and a second contact surface 23b that contacts the front surface 16e of the heat conduction member 16. The pressing member 21 and the heat conduction member 16 may be integrally formed of the same material. The heat conduction material used in the embodiment refers to a substance with high heat conductivity that is used to release heat from the target site. In particular, for the pressing member, a material with high heat conductivity, conductivity, and high strength is desirable.

[0023] Referring to FIGS. 3 and 6(a), the connection portion 18 between the heat conduction member 16 and the heat sink 6 is formed, for example, with a stepped recess 9 that is recessed toward the front surface 7e side by the thickness of the heat conduction member 16 on the rear surface 7f side of the lower end portion of the heat sink 6, and the upper end portion 17 of the heat conduction member 16 is fitted into this recess 9. Thereby, the front surface 16e of the upper end portion 17 of the heat conduction member 16 is joined to a first joint surface (the first joint surface along the module mounting surface 8) 9a that is parallel to the rear surface 7f in the recess 9.

[0024] Also, the upper end surface of the heat conduction member 16 is joined to a second joint surface (the second joint surface that intersects the module mounting surface 8) 9b that is orthogonal to the rear surface 7f in the recess 9. The connection between the heat conduction member 16 and the heat sink 6 is made, for example, by fastening using bolts or the like. Heat conduction grease may be applied to each of the joint surfaces 9a and 9b to enhance the adhesion. The connection between the heat conduction member 16 and the heat sink 6 may be made by welding.

[0025] In this way, by joining the heat conduction member 16 and the heat sink 6 with two joint surfaces 9a and 9b that intersect each other, the joint area increases compared to the case of joining with a single joint surface, so the heat conductivity between the heat conduction member 16 and the heat sink 6 can be enhanced. The rear surface 16f of the heat conduction member 16 and the rear surface 7f of the heat sink 6 can be flush, and an increase in the thickness in the front-rear direction due to the heat conduction member 16 can be suppressed.

[0026] In addition, by joining the heat conduction member 16 and the heat sink 6 at two joint surfaces 9a and 9b that cross each other, the joint strength between the heat conduction member 16 and the heat sink 6 can be increased. Increasing the joint strength is particularly effective in a configuration such as the embodiment in which the capacitor 11 is supported by the heat conduction member 16.

[0027] The connection portion 18' shown in FIG. 6(b) shows an example in which the recess 9 is not formed in the heat sink 6, and the upper end surface (upper side 16a) of the heat conduction member 16 is abutted against the lower end surface of the heat sink 6 for joining. In this case, although the joint area between the heat conduction member 16 and the heat sink 6 decreases, the heat dissipation capacity of the heat sink 6 can be increased as much as possible, such as by expanding the refrigerant flow path in the heat sink 6.

[0028] As described above, the power conversion unit 1 in the above embodiment includes a semiconductor module 2, a heat sink 6 on which the semiconductor module 2 is mounted on the module mounting surface 8, a capacitor 11 disposed outside the heat sink 6 when viewed from the normal direction of the module mounting surface 8, and a heat conduction member 16 that extends from the heat sink 6 toward the capacitor side when viewed from the normal direction of the module mounting surface 8 and is disposed opposite to the capacitor 11. According to this configuration, by extending the heat conduction member 16 from the heat sink 6 for cooling the semiconductor module 2 and disposing the heat conduction member 16 opposite to the capacitor 11, the heat of the capacitor 11 is transmitted to the heat sink 6 through the heat conduction member 16. Therefore, the heat sink 6 can also be used for cooling the capacitor 11, and the cooling performance of the entire unit can be improved. In addition, since the heat sink 6 (and the semiconductor module 2) and the heat conduction member 16 (and the capacitor 11) are close to each other, the capacitor 11 can be arranged in a compact manner. By shortening the conductor path between the semiconductor module 2 and the capacitor 11, the electrical performance such as reducing the inductance of the conductor 26 can be improved. By disposing the capacitor 11 outside the module mounting surface 8 of the heat sink 6, an increase in the thickness of the unit due to the overlap of the capacitor 11 in the normal direction of the module mounting surface 8 can be suppressed, and the unit can be made more compact.

[0029] In the above power conversion unit 1, the heat conduction member 16 has a planar facing surface (front surface 16e) that overlaps with the capacitor 11 when viewed from the normal direction of the module mounting surface 8. The capacitor 11 has a cylindrical outer peripheral surface that overlaps with the front surface 16e when viewed from the normal direction of the module mounting surface 8. Between the heat conduction member 16 and the capacitor 11, a second heat conduction member (pressing member 21) having a first contact surface 23a along the front surface 16e and a second contact surface 23b along the outer peripheral surface is provided. According to this configuration, by providing the second heat conduction member (pressing member 21) that is in surface contact with the heat conduction member 16 and the capacitor 11 between them, the heat conductivity between the heat conduction member 16 and the capacitor 11 is enhanced. Therefore, the heat of the capacitor 11 is easily transmitted to the heat sink 6 through the heat conduction member 16, and the cooling performance of the entire unit can be further improved.

[0030] In the above power conversion unit 1, the pressing member 21 has conductivity and has a case shape that covers the entire capacitor 11. According to this configuration, by covering the entire capacitor 11 with the conductive pressing member 21, the emission of unnecessary electromagnetic waves emitted by the capacitor 11 is suppressed. In this way, the shielding property of the capacitor 11 can be ensured and noise countermeasures can be taken against peripheral devices.

[0031] In the above power conversion unit 1, the heat conduction member 16 and the heat sink 6 are joined to each other at a first joint surface 9a along the module mounting surface 8 and a second joint surface 9b that intersects the module mounting surface 8. According to this configuration, by joining the heat conduction member 16 and the heat sink 6 at two joint surfaces 9a and 9b that intersect each other, the joint area increases compared to the case of joining with a single joint surface. Therefore, the heat conductivity between the heat conduction member 16 and the heat sink 6 can be enhanced, and the joint strength between the heat conduction member 16 and the heat sink 6 can be enhanced. Enhancing the joint strength is particularly effective when the capacitor 11 is supported by the heat conduction member 16.

[0032] According to at least one embodiment described above, by providing a heat sink 6 for mounting the semiconductor module 2 on the module mounting surface 8, a capacitor 11 disposed outside the heat sink 6 when viewed from the normal direction of the module mounting surface 8, and a heat conduction member 16 that extends from the heat sink 6 toward the capacitor side when viewed from the normal direction of the module mounting surface 8 and is disposed opposite to the capacitor 11, the heat sink 6 can also be used for cooling the capacitor 11, and the cooling performance of the entire unit can be enhanced. By providing a case-shaped pressing member 21 having conductivity and covering the entire capacitor 11, the shielding property of the capacitor 11 can be ensured and noise countermeasures can be taken against peripheral devices.

[0033] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0034] 1... Power conversion unit 2... Semiconductor module 6... Heat sink 8... Module mounting surface 9a... First joint surface 9b... Second joint surface 11... Capacitor 16... Heat conduction member 16e... Front surface (opposing surface) 21... Pressing member (second heat conduction member) 23a... First contact surface 23b... Second contact surface

Claims

1. A semiconductor module, a heat sink for mounting the semiconductor module on a module mounting surface, a capacitor disposed outside the heat sink when viewed from the normal direction of the module mounting surface, and a heat conduction member extending from the heat sink toward the capacitor side when viewed from the normal direction of the module mounting surface and disposed opposite to the capacitor. The power conversion unit comprises: The heat conduction member and the heat sink are joined to each other at a first joint surface along the module mounting surface and a second joint surface intersecting the module mounting surface.

2. The heat conduction member has a planar facing surface that overlaps the capacitor when viewed from the normal direction, the capacitor has a cylindrical outer peripheral surface that overlaps the facing surface when viewed from the normal direction, and a second heat conduction member having a first contact surface along the facing surface and a second contact surface along the outer peripheral surface is provided between the heat conduction member and the capacitor. The power conversion unit according to claim 1.

3. The second heat conduction member has conductivity and has a case shape covering the entire capacitor. The power conversion unit according to claim 2.

Images