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] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a power conversion unit. [Background technology]

[0002] 2. Description of the Related Art 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 is known in which the semiconductor module is mounted on a heat sink so as to be cooled. However, as the packaging density of components increases with the miniaturization of equipment, natural cooling systems have issues such as poor convection and susceptibility to the effects of heat from other components. In particular, there is a demand for a configuration that can suppress the effects of heat from capacitors on semiconductor modules mounted on heat sinks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-216409 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a power conversion unit capable of cooling a semiconductor module with a heat sink and suppressing the influence of heat from a capacitor. [Means for solving the problem]

[0005] A power conversion unit according to an embodiment includes a semiconductor module, a heat sink, a capacitor, a conductor, and a thermally conductive member. The heat sink mounts the semiconductor module on a module mounting surface. The capacitor is disposed outside the heat sink when viewed from a normal direction to the module mounting surface. The conductor connects the semiconductor module and the capacitor. The thermally conductive member extends from the heat sink toward the capacitor when viewed from the normal direction to the module mounting surface, and is disposed opposite the capacitor. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a perspective view of the power conversion unit according to the embodiment, seen obliquely from above. [Diagram 2] FIG. 2 is a perspective view of the power conversion unit according to the embodiment, seen obliquely from below. [Diagram 3] FIG. 2 is a side view of the power conversion unit according to the embodiment. [Figure 4] Cross section AA of Figure 3. [Diagram 5] 3 is an explanatory diagram showing the configuration of a capacitor and a pressing member of the power conversion unit. FIG. [Figure 6] 5A is an explanatory diagram showing a connection portion between a heat sink and a metal plate of the power conversion unit, and FIG. 5B is an explanatory diagram showing another example of the connection portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, a power conversion unit 1 according to an embodiment will be described with reference to the drawings. Note that the same or corresponding components will be denoted by the same reference numerals and the description thereof will be omitted.

[0008] (Power conversion unit 1) FIG. 1 is a perspective view of a power conversion unit 1 according to an embodiment, as viewed obliquely from above, and FIG. 2 is a perspective view of the power conversion unit 1 according to an embodiment, as viewed obliquely from above. The power conversion unit 1 of the embodiment includes a semiconductor module 2 including a semiconductor element such as an IBGT, a heat sink 6, for example water-cooled, on which the semiconductor module 2 is mounted, for example a plurality (pair) of smoothing capacitors, a heat conductive member 16 extending from the heat sink 6 toward the capacitors, a pressing member 21 that fixes the capacitor 11 to the heat conductive member 16, and a conductor 26 that connects the semiconductor module 2 to the capacitor 11.

[0009] For convenience of explanation, the arrow Y in the drawings indicates the front-rear direction, the arrow X indicates the left-right direction, and the arrow Z indicates the up-down direction. Also, in the drawings, the arrow FR indicates the forward direction in the Y direction, the arrow LH indicates the left direction in the X direction, and the arrow UP indicates the upward direction in the Z direction. The orientations such as front-rear, left-right, etc. in 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 as viewed from the left and right direction, and FIG. 4 is a cross-sectional view taken along line AA in FIG. 3 and 4, the semiconductor module 2 includes a flat base 3 having a reduced thickness in the front-rear direction, and a conductor connection portion 4 protruding from one side surface in the front-rear direction of the base 3. An example of the semiconductor module 2 is 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 base 3 is arranged such that the upper and lower sides 3a, 3b of the rectangular shape when viewed from the front-rear direction are aligned along the left-right direction, and the left and right sides 3c, 3d are aligned along the up-down direction. The base 3 is arranged such that the thickness direction is aligned along the front-rear direction. The base 3 is arranged such that both front-rear sides are perpendicular to the front-rear direction. The four corners of the base 3 are provided with fixing parts 3g that are fixed to the heat sink 6 with screws or the like. The conductor connection parts 4 are provided in a plurality of rows in the vertical direction, for example, in the left-right central portion of one front-rear side surface of the base part 3. A conductor 26 for connection to the capacitor 11 is fixed to each conductor connection part 4 with a screw or the like.

[0012] The heat sink 6 includes a heat sink body 7 formed of a metal material such as an aluminum alloy having high thermal conductivity (thermal conductivity rate). The heat sink body 7 has a rectangular flat plate shape that is slightly larger 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 upper and lower sides 7a, 7b of the rectangular shape when viewed from the front-rear direction aligned along the left-right direction, and with left and right side sides 7c, 7d aligned along the up-down direction. The heat sink body 7 is arranged with its thickness direction aligned along the front-rear direction. The heat sink body 7 is arranged with both front-rear sides perpendicular to the front-rear direction.

[0013] One side surface in the front-rear direction of the heat sink body 7 is made into a module mounting surface (module mounting area) 8 on which the semiconductor module 2 is mounted, leaving a certain width on the outer periphery. The heat sink body 7 is, for example, a water-cooled type that circulates cooling water. A water supply nozzle 7g for introducing cooling water into a 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 provided protruding from one of the left and right sides 7c, 7d of the heat sink body 7 (for example, the left side 7c). The heat sink 6 is not limited to being water-cooled, and may be one that flows a coolant (including gas) other than cooling water, or may be air-cooled.

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

[0015] FIG. 5 is a cross-sectional view taken along line BB of FIG. Capacitor 11 is disposed below semiconductor module 2. Capacitor 11 includes, for example, a cylindrical capacitor body 12 whose axial direction is aligned in the up-down direction. In Fig. 1 and Fig. 2, capacitor 11 is configured by arranging a pair of capacitor bodies 12 on the left and right. This ensures the capacitance of capacitor 11 while reducing the thickness in the front-to-rear direction. The line in the figure indicates the central axis C1 of capacitor body 12. 4 and 5, capacitor 11 may be configured to include a single cylindrical capacitor body 12. Furthermore, capacitor body 12 is not limited to having a cylindrical outer shape.

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

[0017] The pressing member 21 has a rectangular parallelepiped outer shape that overlaps with the heat conductive member 16 when viewed from the front-rear direction. The pressing member 21 is formed of, for example, an aluminum alloy, which is a metal material with high thermal conductivity, similar to the heat conductive member 16. The pressing member 21 is in the shape of a case that covers the entire capacitor 11. The pressing member 21 exposes only the terminal portion 13 of the capacitor 11 to the outside, allowing a conductor 26 to be connected thereto. The pressing member 21 forms a cylindrical accommodation space 21a that can accommodate, for example, the capacitor body 12.

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

[0019] The pressing member 21 is in surface contact with the capacitor body 12 and the thermally conductive member 16, so that heat generated by the capacitor body 12 is easily transferred to the pressing member 21 and further to the thermally conductive member 16. The heat transferred to the thermally conductive member 16 is efficiently dissipated in the heat sink 6. This improves the cooling performance of the capacitor 11 and therefore the cooling performance of the entire power conversion unit 1. Thermally conductive grease may be applied to each of the contact surfaces 23a, 23b to improve adhesion.

[0020] Pressing member 21, which covers the entire capacitor 11, also functions as a shielding member that blocks radiation noise generated by capacitor 11. This makes it easier to protect items arranged around the capacitor (for example, board 24 attached to the front surface of pressing member 21, etc.).

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

[0022] For example, pressing member 21 may be formed only by rear divided body 23 on the thermal conductive member 16 side, and may have a first contact surface 23a in contact with the outer peripheral surface of the front half of capacitor 11 and a second contact surface 23b in contact with front surface 16e of thermal conductive member 16. Pressing member 21 and thermal conductive member 16 may be integrally formed from the same material. The thermally conductive material used in the embodiment refers to a substance having high thermal conductivity that is used to dissipate heat from a target portion. In particular, the pressing member is preferably made of a material having high thermal conductivity, electrical conductivity, and high strength.

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

[0024] Further, the upper end surface of the thermally conductive member 16 is joined to a second joint surface 9b (a second joint surface intersecting with the module mounting surface 8) perpendicular to the rear surface 7f of the recess 9. The thermally conductive member 16 and the heat sink 6 are connected to each other by fastening using, for example, bolts or the like. Thermally conductive grease may be applied to each of the joint surfaces 9a, 9b to improve adhesion. The thermally conductive member 16 and the heat sink 6 may also be connected to each other by welding.

[0025] In this way, by joining the heat conductive member 16 and the heat sink 6 at two mutually intersecting joining surfaces 9a, 9b, the joining area is increased compared to the case where they are joined at a single joining surface, and therefore it is possible to improve the thermal conductivity between the heat conductive member 16 and the heat sink 6. The rear surface 16f of the heat conductive member 16 and the rear surface 7f of the heat sink 6 are flush with each other, and it is possible to suppress an increase in the thickness in the front-to-rear direction due to the heat conductive member 16.

[0026] Furthermore, by joining the heat conductive member 16 and the heat sink 6 at the two joining surfaces 9a, 9b that intersect with each other, it is possible to increase the joining strength between the heat conductive member 16 and the heat sink 6. Increasing the joining strength is particularly effective in a configuration such as the embodiment in which the capacitor 11 is supported by the heat conductive member 16.

[0027] 6(b) shows an example in which no recess 9 is formed in the heat sink 6, and the upper end surface (upper side 16a) of the thermally conductive member 16 is butted against the lower end surface of the heat sink 6 for connection. In this case, the bonding area between the thermally conductive member 16 and the heat sink 6 is reduced, but the heat dissipation capacity of the heat sink 6 can be increased as much as possible by, for example, expanding the refrigerant flow path in the heat sink 6.

[0028] As described above, the power conversion unit 1 in the above embodiment comprises a semiconductor module 2, a heat sink 6 for mounting the semiconductor module 2 on the module mounting surface 8, a capacitor 11 arranged outside the heat sink 6 when viewed from the normal direction of the module mounting surface 8, and a thermally conductive member 16 extending from the heat sink 6 towards the capacitor when viewed from the normal direction of the module mounting surface 8 and arranged opposite the capacitor 11. According to this configuration, by extending the thermally conductive member 16 from the heat sink 6 for cooling the semiconductor module 2 and arranging the thermally conductive member 16 facing the capacitor 11, the heat of the capacitor 11 is transferred to the heat sink 6 via the thermally conductive member 16. Therefore, the heat sink 6 can also be used to cool the capacitor 11, improving the cooling performance of the entire unit. Furthermore, by bringing the heat sink 6 (and the semiconductor module 2) and the thermally conductive member 16 (and the capacitor 11) into close proximity, the capacitor 11 can be arranged in a compact manner. By shortening the conductor path between the semiconductor module 2 and the capacitor 11, it is possible to improve electrical performance, such as by reducing the inductance of the conductor 26. By arranging the capacitor 11 on the outer side of the module mounting surface 8 of the heat sink 6, an increase in the thickness of the unit caused by the capacitors 11 overlapping 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-mentioned power conversion unit 1, the heat conduction member 16 has a planar opposing surface (front surface 16e) that overlaps with the capacitor 11 when viewed from the normal direction of the module mounting surface 8, and 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, and a second heat conduction member (pressing member 21) is provided between the heat conduction member 16 and the capacitor 11, the second heat conduction member having a first contact surface 23a that runs along the front surface 16e and a second contact surface 23b that runs along the outer peripheral surface. According to this configuration, by providing a second heat conductive member (pressing member 21) between heat conductive member 16 and capacitor 11 in surface contact with them, the thermal conductivity between heat conductive member 16 and capacitor 11 is improved. Therefore, heat from capacitor 11 is easily transferred to heat sink 6 via heat conductive member 16, and the cooling performance of the entire unit can be further improved.

[0030] In the power conversion unit 1, the pressing member 21 is conductive and has a case shape that covers the entire capacitor 11. According to this configuration, the conductive pressing member 21 covers the entire capacitor 11, thereby suppressing the emission of unnecessary electromagnetic waves generated by the capacitor 11. In this way, the shielding properties of the capacitor 11 are ensured, and noise reduction measures for peripheral devices can be implemented.

[0031] In the power conversion unit 1, the thermally conductive 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 intersecting with the module mounting surface 8. According to this configuration, the thermally conductive member 16 and the heat sink 6 are joined at two mutually intersecting joining surfaces 9a, 9b, which increases the joining area compared to when they are joined at a single joining surface. This increases the thermal conductivity between the thermally conductive member 16 and the heat sink 6, and also increases the joining strength between the thermally conductive member 16 and the heat sink 6. Increasing the joining strength is particularly effective when the capacitor 11 is supported by the thermally conductive member 16.

[0032] According to at least one of the embodiments described above, by providing the heat sink 6 for mounting the semiconductor module 2 on the module mounting surface 8, the capacitor 11 disposed outside the heat sink 6 as viewed from the normal direction of the module mounting surface 8, and the thermally conductive member 16 extending from the heat sink 6 toward the capacitor as viewed from the normal direction of the module mounting surface 8 and disposed opposite the capacitor 11, the heat sink 6 can also be used to cool the capacitor 11, thereby improving the cooling performance of the entire unit. By providing the case-shaped pressing member 21 that is conductive and covers the entire capacitor 11, the shielding performance of the capacitor 11 can be ensured, and noise countermeasures for peripheral devices can be implemented.

[0033] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[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 conductive material 16e...Front (opposite side) 21...Pressing member (second heat conductive 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 in a normal direction of the module mounting surface; a thermal conductive member extending from the heat sink towards the capacitor when viewed from the normal direction of the module mounting surface and disposed opposite the capacitor.

2. the heat conducting member has a planar opposing surface overlapping the capacitor when viewed from the normal direction, the capacitor has a cylindrical outer circumferential surface that overlaps with the opposing surface when viewed from the normal direction, 2. The power conversion unit according to claim 1, wherein a second heat conductive member having a first contact surface along the opposing surface and a second contact surface along the outer circumferential surface is provided between the heat conductive member and the capacitor.

3. The power conversion unit according to claim 2 , wherein the second thermal conductive member is electrically conductive and has a case shape that covers the entire capacitor.

4. 4. The power conversion unit according to claim 1, wherein the thermal 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.

Images