Power converter

Abstract

A comprehensive power converter: a cooling element (6) with a cooling surface (10) formed therein; a semiconductor module (4) provided on the cooling surface (10); and a capacitor module (5) comprising a capacitor module main body (50) opposite the cooling surface (10), at a distance from the cooling surface (10), and a heat conduction element (54) provided in the capacitor module main body (50), wherein - the capacitor module main body (50) is connected to the semiconductor module (4) via a busbar (7,8), wherein - the heat conduction element (54) has a heat radiation section (541), - the heat radiating section (541) is thermally connected to the cooling surface (10) at a position that is further away from the semiconductor module (4) than an end section of the capacitor module main body (50) that is closer to the semiconductor module (4), - the main body of the capacitor module (50) comprises a capacitor housing (51), a capacitor element (53) arranged in the capacitor housing (51), and a filler element (52) formed from a resin and covering the capacitor element (53) in the capacitor housing (51); and - the busbar (7,8) extends through the filler element (52) to be connected to the capacitor element (53), while the latter is held in the capacitor housing (51) above the filler element (52), - the heat conduction element (54) has an attachment section (542) which is arranged within the filling element (52); and - between the mounting section (542) and at least the capacitor element (53) and / or the busbar (7,8), an insulating element (56) with a thermal conductivity greater than that of the filling element (52) is placed.

Description

Background of the invention; Field of the invention

[0001] The present invention relates to a power converter comprising a semiconductor module and a capacitor module. Description of the state of the art

[0002] Up to this point, a power converter was known in which a semiconductor module, acting as a heat-generating component, is connected to a capacitor module via a busbar (sliding conductor). In this prior art power converter, heat generated in the semiconductor module is transferred to it via the busbar. Consequently, the temperature of a capacitor element within the capacitor module increases, and the capacitor module therefore tends to have a shorter lifespan.

[0003] Meanwhile, up to this point a power converter has been proposed in which a common cooling element is attached to both the semiconductor module and the capacitor module in order to prevent a temperature increase in both the semiconductor module and the capacitor module (see, for example, JP 2013-146179A).

[0004] DE 10 2011 104 928 A1 discloses the cooling structure of a capacitor comprising a snubber capacitor in which conductor terminals are connected to external electrodes of a laminated ceramic electronic component, a circuit board for arranging the snubber capacitor and semiconductor switching elements, and a heat-dissipating plate. The plate is made of a metal that dissipates the heat generated in the circuit board. The cooling structure of the capacitor is designed such that an insulating element with high thermal conductivity engages between the snubber capacitor and the heat-dissipating plate.

[0005] KR 10 1 541 181 B1 discloses a power converter device for an electric vehicle in which an inverter and a converter used for the motor control of an electric vehicle are integrated in one housing.

[0006] US 2010 / 0 155 158 A1 discloses a capacitor module in which the structure of a connecting element is highly resistant to vibration and exhibits low inductance. The capacitor module comprises a plurality of capacitors and a laminate consisting of a first wide conductor and a second wide conductor, which are connected in a layered form with an insulating film placed between the first and second wide conductors. Summary of the invention

[0007] In a power converter, it is preferred that a capacitor module be positioned closer to a semiconductor module and that the inductance of a current rail be reduced to improve the converter's performance. However, in the prior art power converter disclosed in Japanese patent publication JP 2013-146179A, when the capacitor module is positioned closer to the semiconductor module, the capacitor module is located within an area of ​​the cooling element where the temperature is elevated due to heat generation from the semiconductor module. As a result, in the prior art power converter, it is less likely that the capacitor module will be cooled by the cooling element.

[0008] The present invention was developed to solve the problem described above. One object of the present invention is to provide a power converter suitable for improving its performance and also enabling more reliable cooling of both a semiconductor module and a capacitor module.

[0009] The problem is solved by a power converter with the features according to claim 1 or 2. Advantageous embodiments result from the dependent claims.

[0010] The power converter according to at least one embodiment of the present invention is suitable for improving its performance and also enables the semiconductor module and the capacitor module to be cooled more reliably. Brief description of the characters Fig. Figure 1 is a circuit diagram for representing a power converter according to a first embodiment of the present invention; Fig. Figure 2 is a top view showing the power converter. Fig. 1; Fig. 3 is a cross-sectional view taken along line III-III from Fig. 2 is taken; Fig. Figure 4 is a cross-sectional view to illustrate a power converter according to a second embodiment of the present invention; Fig. Figure 5 is a cross-sectional view to illustrate a power converter according to a third embodiment of the present invention; Fig. Figure 6 is a cross-sectional view illustrating a power converter according to a fourth embodiment of the present invention; and Fig. Figure 7 is a cross-sectional view to illustrate a power converter according to a fifth embodiment of the present invention. Description of the embodiments

[0011] With reference to the figures, embodiments of the present invention are described below. First embodiment

[0012] Fig. Figure 1 is a circuit diagram for representing a power converter according to a first embodiment of the present invention. Fig. Figure 2 is a top view showing the power converter. Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III from Fig. 2 is taken. A power converter 1 is designed to convert electrical energy between a power source and a consumer. In this example, a vehicle power converter, which is to be installed in a vehicle, such as a hybrid vehicle or an electric vehicle, is used as power converter 1.

[0013] The power converter 1 comprises a plurality of semiconductor modules 4, a capacitor module 5, and a cooling element 6. In this example, the three semiconductor modules 4, which individually belong to three phases, are included in the power converter 1.

[0014] Capacitor module 5 is electrically connected to a battery 2 as a DC power source. A DC voltage from battery 2 is smoothed by capacitor module 5.

[0015] For the capacitor module 5, N-side busbars 7 and P-side busbars 8 are provided as a multitude of busbars. Each of the N-side busbars 7 and the P-side busbars 8 is made of a conductive material such as copper. The capacitor module 5 is individually electrically connected to each semiconductor module 4 via the N-side busbar 7 and the P-side busbar 8. The capacitor module 5 is thermally connected to each semiconductor module 4 via the N-side busbar 7 and the P-side busbar 8.

[0016] Each semiconductor module 4 converts the DC voltage, smoothed by the capacitor module 5, into an AC voltage. As in Fig. As shown in Figure 1, each semiconductor module 4 comprises a plurality of switching elements 41. In this example, the two switching elements 41 connected in series are included in each of the semiconductor modules 4. Of the two switching elements 41 of the semiconductor module 4, one is connected to the N-side busbar 7 and the other is connected to the P-side busbar 8.

[0017] Each of the switching elements 41 individually performs a switching operation under the control of a control device (not shown). Accordingly, each semiconductor module 4 is a generating component that produces heat as a result of the switching operation performed by each of the switching elements 41. The DC voltage smoothed by the capacitor module 5 is converted into a three-phase AC voltage by the switching operation performed by each of the switching elements 41.

[0018] Each of the semiconductor modules 4 is electrically connected to a motor 3, which serves as a load. The motor 3 is operated by a supply of three-phase alternating voltage from each of the semiconductor modules 4 to the motor 3.

[0019] The cooling element 6 is designed to cool the semiconductor modules 4 and the capacitor module 5. In the cooling element 6, as shown in Fig. As shown in Figure 3, a cooling surface 10 is formed. Furthermore, a flow channel (not shown) is formed in the cooling element 6, through which a coolant flows. The coolant enters the flow channel of the cooling element 6 from a flow channel inlet of the cooling element 6. The coolant flowing through the flow channel of the cooling element 6 is ejected outwards from the cooling element 6 through a flow channel outlet of the cooling element 6.

[0020] The cooling surface 10 is cooled by the coolant flowing through the cooling element 6. Water, oil, air, or a similar substance can be used as the coolant. In this example, an air-cooled cooling element is used with air as the coolant.

[0021] The semiconductor modules 4 are positioned on the cooling surface 10. An outer surface of each semiconductor module 4 has a section in contact with the cooling surface 10. Thus, each semiconductor module 4 is thermally connected to the cooling surface 10. Heat generated in the semiconductor module 4 is radiated to the cooling surface 10, thereby cooling the semiconductor module 4. The heat transferred to the cooling surface 10 is then radiated into the coolant flowing in the cooling element 6.

[0022] The capacitor module 5 comprises a capacitor module main body 50 and a variety of heat conduction elements 54 provided in the capacitor module main body 50.

[0023] The capacitor module body 50 is spaced apart from each of the semiconductor modules 4. Furthermore, the capacitor module body 50 is electrically and thermally connected to each of the semiconductor modules 4 via the N-side busbar 7 and the P-side busbar 8. The capacitor module body 50 is also spaced apart from the cooling surface 10. Additionally, the capacitor module body 50 is positioned opposite the cooling surface 10. As a result, a space (distance) is formed between the capacitor module body 50 and the cooling surface 10.

[0024] The capacitor module main body 50 comprises a capacitor housing 51, a plurality of capacitor elements 53 arranged in the capacitor housing 51, and a filler element 52 formed from a resin, which covers the plurality of capacitor elements 53 in the capacitor housing 51.

[0025] As in Fig. As shown in Figure 2, the capacitor housing 51 is provided with a plurality of fixed sections 55. Each of the fixed sections 55 is attached to the cooling surface 10. This maintains a condition in which the capacitor module main body 50 is spaced from the cooling surface 10. When the power converter 1 is viewed along a direction perpendicular to the cooling surface 10, the distance between each of the semiconductor modules 4 and each of the fixed sections 55 is greater than the distance between each of the semiconductor modules 4 and the capacitor module main body 50.

[0026] An opening is formed in the capacitor housing 51. In this example, the capacitor housing 51 is arranged such that the opening faces the cooling surface 10. Additionally, an outer surface of the capacitor housing 51 is exposed to the outside air. The capacitor housing 51 is made of a metal with a thermal conductivity of [value missing in original text]. The thermal conductivity of the capacitor housing 51 is greater than the thermal conductivity of the filling element 52.

[0027] Each of the N-side busbars 7 and the P-side busbars 8 is inserted into the capacitor housing 51 through the opening of the capacitor housing 51. Each of the N-side busbars 7 and the P-side busbars 8 then extends through the filler element 52 to be connected to the corresponding capacitor element 53. Each of the N-side busbars 7 and the P-side busbars 8 is then held in the capacitor housing 51 by the filler element 52.

[0028] The filling element 52 fills the interior of the capacitor housing 51. A portion of each of the N-side busbars 7, a portion of each of the P-side busbars 8, and each of the capacitor elements 53 are embedded in the filling element 52. Thus, the filling element 52 seals the capacitor elements 53 within the capacitor housing 51. The resin used as the material for the filling element 52 is a material with thermal transfer properties.

[0029] A portion of the heat generated in each of the semiconductor modules 4 is transferred through the N-side current rail 7 and the P-side current rail 8, respectively, and reaches the capacitor module main body 50. The portion of the heat transferred from each semiconductor module 4 and reaching the capacitor module main body 50 is transferred through the filler element 52 and radiated to the outer surface of the capacitor housing 51 and into the outside air.

[0030] Each of the heat conduction elements 54 is made of a material with a heat transfer capacity. In this example, each of the heat conduction elements 54 is made of a metal, for example, copper. Each of the heat conduction elements 54 has a thermal conductivity that is greater than the thermal conductivity of the filler element 52. In this example, the heat conduction elements 54 are arranged at positions away from the N-side busbars 7, the P-side busbars 8, the capacitor housing 51, and the capacitor elements 53.

[0031] Each of the heat conduction elements 54 has a plate-shaped heat radiating section 541 in contact with the cooling surface 10, a plate-shaped mounting section 542 attached to the capacitor module main body 50, and a connecting section 543 connecting the heat radiating section 541 to the mounting section 542.

[0032] The mounting section 542 is arranged in the main body of the capacitor module 50, which is embedded in the filling element 52. Thus, each of the heat conduction elements 54 is held in the capacitor housing 51 via the filling element 52.

[0033] The connecting section 543 extends from the mounting section 542 outwards from the capacitor housing 51 through the opening of the capacitor housing 51. The connecting section 543 also extends from the inside of the filling element 52 to the outside of the filling element 52 in the direction of the cooling surface 10. Thus, heat is transferred from the main body of the capacitor module 50 to the outside of the main body of the capacitor module 50 via the mounting section 542 and the connecting section 543, respectively. The connecting section 543 is also connected to the heat dissipation section 541 at the cooling surface 10.

[0034] The heat-radiating section 541 is positioned away from the main body of the capacitor module 50. The heat-radiating section 541 is also in contact with the cooling surface 10, thus forming a thermal connection with it. This allows heat to be radiated from the main body of the capacitor module 50 to the cooling surface 10 via the heat-conducting elements 54.

[0035] Furthermore, the heat-radiating section 541 is in contact with the cooling surface 10 at a position that is further away from each of the semiconductor modules 4 than an end section of the capacitor module main body 50, which is closer to the semiconductor module 4. In other words, when the power converter 1 is viewed along a direction perpendicular to the cooling surface 10, the distance between each of the semiconductor modules 4 and the heat-radiating section 541 is greater than the distance between each of the semiconductor modules 4 and the capacitor module main body 50.

[0036] Furthermore, the heat-radiating section 541 extends from the connecting section 543 to the opposite side of each of the semiconductor modules 4 along the cooling surface 10. Consequently, the heat-radiating section 541 has a portion that reaches a position further away from the semiconductor module 4 than a region of the cooling surface 10 that faces the capacitor module main body 50. In other words, when the power converter 1 is viewed along the direction perpendicular to the cooling surface 10, the heat-radiating section 541 has a portion that protrudes from the region of the capacitor module main body 50 into the opposite side of the semiconductor module 4, as shown in Fig. 2 shown.

[0037] The capacitor module main body 50 and each of the semiconductor modules 4 are arranged in the direction of the coolant flow within the cooling element 6. The heat-radiating section 541 is in contact with the cooling surface 10 at a position upstream of the associated semiconductor module 4 in the coolant flow. In other words, the heat-radiating section 541 is in contact with the cooling surface 10 at a position closer to the flow channel inlet of the cooling element 6 than the position of the associated semiconductor module 4. Accordingly, the coolant flowing in the cooling element 6 absorbs heat from the heat-radiating section 541 and then absorbs heat from the associated semiconductor module 4.

[0038] Reducing the length of each N-side busbar 7 and P-side busbar 8 by moving the capacitor module body 50 closer to each of the semiconductor modules 4 reduces the inductance of both the N-side busbars 7 and the P-side busbars 8. This improves the performance of the power converter 1. Accordingly, it is preferred that the position of the capacitor module body 50 is closest to each of the semiconductor modules 4.

[0039] On the other hand, the temperature of the cooling surface 10 around each of the semiconductor modules 4 is increased by the heat generated in each semiconductor module 4. In particular, if an air-cooling element with a lower cooling capacity than the cooling element 6 is used, the temperature of the cooling surfaces 10 tends to be higher around each of the semiconductor modules 4. Accordingly, if the capacitor module body 50 is brought into contact with the cooling surface 10 at a position close to the semiconductor modules 4, the capacitor module body 50 comes into contact with the cooling surface 10 at the elevated temperature. In this case, heat cannot be efficiently radiated from the capacitor module body 50 to the cooling surface 10.

[0040] However, in the first embodiment of the power converter 1, the capacitor module main body 50 is located away from the cooling surface 10. This prevents the transfer of heat generated in each of the semiconductor modules 4 to the capacitor module main body 50 via the cooling surface 10. Consequently, the position of the capacitor module main body 50 can be moved closer to each of the semiconductor modules 4. Therefore, it is possible to reduce the inductance of both the N-side current rails 7 and the P-side current rails 8, thus improving the efficiency of the power converter 1.

[0041] Additionally, the heat dissipation section 541 is in contact with the cooling surface 10 at a position that is further away from each of the semiconductor modules 4 than the end section of the capacitor module main body 50, which is closer to the semiconductor module 4. Thus, the heat dissipation section 541 can be brought into contact with the cooling surface 10 at a position where the cooling surface 10 is less likely to be affected by the heat from each of the semiconductor modules 4. As a result, it is possible to efficiently dissipate the heat in the capacitor module main body 50 from the heat dissipation section 541 to the cooling surface 10. Therefore, it is possible to cool not only each semiconductor module 4, but also the capacitor module 5 more reliably.

[0042] Furthermore, the heat dissipation section 541 is in contact with the cooling surface 10 at the position upstream of each of the semiconductor modules 4 in the flow of the coolant cooling the cooling surface 10. This allows the heat dissipation section 541 to be brought into contact with the cooling surface 10 at a position where the coolant flows before heat is absorbed by each of the semiconductor modules 4. Consequently, it is possible to maintain the cooling surface 10 at a low temperature in the position where the heat dissipation section 541 is in contact with it, and to allow heat to be radiated more efficiently from the heat dissipation section 541 to the cooling surface 10 within the capacitor module main body 50. Therefore, it is possible to cool the capacitor module 5 more reliably.

[0043] Each of the heat conduction elements 54 has a mounting section 542, which is located in the capacitor module main body 50. Accordingly, heat within the capacitor module main body 50 can be efficiently transferred to the outside via the heat conduction elements 54. This allows for more reliable cooling of the capacitor module 5. Furthermore, the heat conduction elements 54 can be integrated with the capacitor module main body 50. Consequently, for the manufacture of the power converter 1, the capacitor module main body 50 and the heat conduction elements 54 can be treated as a single component. This simplifies the manufacturing process of the power converter 1.

[0044] Each of the N-side busbars 7 and the P-side busbars 8 is connected to the capacitor element 53 by the filler element 52. Additionally, each of the N-side busbars 7 and the P-side busbars 8 is also held in the capacitor housing 51 by the filler element 52. Accordingly, the filler element 52 is able to transfer some of the heat from each of the semiconductor modules 4, via the N-side busbar 7 and the P-side busbar 8, to the capacitor housing 51. This allows the heat to be dissipated from the capacitor housing 51 to the outside air, thus reliably preventing a temperature increase in the capacitor module 5. Second embodiment

[0045] Fig. Figure 4 is a cross-sectional view illustrating a power converter according to a second embodiment of the present invention. An insulating sheet of paper 56, distinct from the filler element 52, is positioned between each of the N-side busbars 7 and the mounting section 542. As a result, the mounting section 542 of each of the heat conduction elements 54 is located below the N-side busbar 7, above the insulating sheet of paper 56, within the capacitor housing 51. The insulating sheet of paper 56 has a thermal conductivity greater than that of the filler element 52. The insulating sheet of paper 56 is an insulating element with a higher electrical insulation performance than that of the filler element 52.

[0046] A portion of the heat transferred from each of the N-side busbars 7 is transferred to the mounting section 542 via the insulating paper sheet 56. The heat transferred from the N-side busbar 7 to the mounting section 542 is radiated to the cooling surface 10 by the connecting section 543 and the heat-radiating section 541, respectively. The other configurations are identical to those of the first embodiment.

[0047] In the power converter 1 thus formed, the insulating paper sheet 56, with a thermal conductivity greater than that of the filling element 52, is placed between the mounting section 542 of each of the heat conduction elements 54 and the associated N-side busbar 7. This facilitates the transfer of heat from the N-side busbar 7 to the heat conduction element 54. Therefore, it is possible to dissipate the heat more efficiently from the capacitor module main body 50 to the cooling surface 10.

[0048] In the example described above, the insulating element placed between the mounting section 542 and the N-side busbar 7 is the insulating sheet of paper 56. However, the insulating element placed between the mounting section 542 and the N-side busbar 7 need not be the insulating sheet of paper 56, as long as the insulating element has a thermal conductivity greater than that of the filler element 52. Similarly, a heat-conducting arc formed from a resin, a ceramic plate, or something similar can also be used as the insulating element.

[0049] Furthermore, in the example described above, the insulating paper sheet 56 is placed between the mounting section 542 and the N-side busbar 7. However, it is also possible to arrange the mounting section 542 in the capacitor housing 51 such that it faces the associated P-type busbar 8, and the insulating paper sheet 56 is placed between the mounting section 542 and the P-side busbar 8. Alternatively, it is also possible to arrange the mounting section 542 in the capacitor housing 51 such that it faces the associated capacitor element 53, and the insulating paper sheet 56 is placed between the mounting section 542 and the capacitor element 53. Such configurations also allow the heat in the capacitor module main body 50 to be radiated more efficiently to the cooling surface 10.Thus, by interposing the insulating paper sheet 56 between the mounting section 542 and at least the N-side busbar 7, the P-side busbar 8 and / or the capacitor element 53, it is possible to dissipate the heat in the capacitor module main body 50 to the cooling surface 10 more efficiently. Third embodiment

[0050] Fig. Figure 5 is a cross-sectional view illustrating a power converter according to a third embodiment of the present invention. A thermal insulation element 57 is positioned between the capacitor module main body 50 and the cooling surface 10. Additionally, the capacitor module main body 50 is supported by the cooling surface 10 via the thermal insulation element 57.

[0051] The thermal insulation element 57 is made of a material with a thermal conductivity lower than that of the capacitor module main body 50. In other words, the thermal insulation element 57 is made of a material with a thermal conductivity lower than that of the capacitor housing 51, the filler element 52, and the capacitor elements 53. A resin, rubber, or similar material is used as the material forming the thermal insulation element 57. Other configurations are identical to those of the second embodiment.

[0052] In the power converter 1 thus configured, the thermal insulation element 57, made of a material with a lower thermal conductivity than that of the capacitor module body 50, is positioned between the capacitor module body 50 and the cooling surface 10. This allows the thermal insulation element 57 to more reliably prevent heat transfer from the cooling surface 10 to the capacitor module body 50. Consequently, each of the semiconductor modules 4 and the capacitor module 5 can be cooled more reliably. This also allows the thermal insulation element 57 to provide stable support to the capacitor module body 50 with respect to the cooling surface 10. As a result, it is possible to improve the vibration resistance of the power converter 1 and prevent failures in the power converter 1. Fourth embodiment

[0053] Fig. Figure 6 is a cross-sectional view illustrating a power converter according to a fourth embodiment of the present invention. The mounting section 542 of each heat conduction element 54 is attached to an outer surface of the capacitor module main body 50. The mounting section 542 is also in contact with the outer surface of the capacitor module main body 50. Through this contact with the outer surface of the capacitor module main body 50, the mounting section 542 is thermally connected to the outer surface of the capacitor module main body 50. In this example, the mounting section 542 is in contact with the outer surface of the capacitor housing 51. Accordingly, in this example, the heat conduction elements 54 are not inserted into the capacitor module main body 50.

[0054] The capacitor housing 51 is arranged with its opening such that it faces the semiconductor modules 4. Consequently, the outer surface of the capacitor housing 51 has a section that faces the cooling surface 10.

[0055] Each of the mounting sections 542 is attached to a portion of the outer surface of the capacitor housing 51 that faces the cooling surface 10. The heat in the capacitor module main body 50 is radiated from the capacitor housing 51 to the cooling surface 10 by means of the heat conduction elements 54. Other configurations are identical to those of the first embodiment.

[0056] Even if the mounting section 542 of each of the heat conduction elements 54 is thus attached to the outer surface of the capacitor module main body 50, it is possible to allow the heat in the capacitor module main body 50 to be efficiently transferred to the heat conduction element 54. This allows the capacitor module main body 50 to be cooled more reliably.

[0057] In the example described above, each of the mounting sections 542 is in contact with the outer surface of the capacitor module main body 50. However, the mounting section 542 can also be attached to the outer surface of the capacitor module main body 50 via an adhesive element with heat transfer capability. In this case, the adhesive element is in close contact with both the outer surface of the capacitor module main body 50 and the mounting section 542, with no gap between them. Furthermore, in this case, the mounting section 542 is attached to the outer surface of the capacitor module main body 50 via the adhesive element to be thermally bonded to the outer surface of the capacitor module main body 50. The adhesive medium is a heat radiation field, a heat conduction arc formed from a resin, or something similar.It is preferred that the adhesive has a thermal conductivity greater than that of the capacitor housing 51 and the heat conduction elements 54. However, the thermal conductivity of the adhesive can be equal to or less than that of the corresponding thermal conductivities of the capacitor housing 51 and the heat conduction elements 54. This allows the adhesive to fill any gap formed between the outer surface of the capacitor module main body 50 and each of the mounting sections 542, and enables more efficient heat transfer from the capacitor module main body 50 to each of the heat conduction elements 54. As a result, the capacitor module main body 50 can be cooled more reliably.

[0058] In the example described above, the capacitor module main body 50 is arranged with the opening of the capacitor housing 51 facing each of the semiconductor modules 4. However, the opening of the capacitor housing 51 can also face the cooling surface 10. Fifth embodiment

[0059] Fig.Figure 7 is a cross-sectional view illustrating a power converter according to a fifth embodiment of the present invention. Each heat conduction element 54 is integrally formed with the capacitor housing 51. Additionally, the capacitor housing 51 is formed from the same material as the heat conduction elements 54. In particular, a single element has one section that serves as the capacitor housing 51 and another section that serves as the heat conduction elements 54. A metal with high thermal conductivity, such as aluminum, is used as the material for forming the capacitor housing 51 and the heat conduction elements 54. The element in which the capacitor housing 51 and the heat conduction elements 54 are integrated has a thermal conductivity that is greater than the thermal conductivity of the filler element 52.

[0060] Each of the heat conduction elements 54 projects from an edge section of the opening of the condenser housing 51 towards the cooling surface 10. The heat conduction element 54 has the plate-shaped heat-radiating section 541 in contact with the cooling surface 10 and the connecting section 543, which connects the heat-radiating section 541 to the condenser housing 51. The corresponding configurations of the heat-radiating section 541 and the connecting section 543 are identical to those in the first embodiment. The other configurations are also identical to those of the first embodiment.

[0061] In the power converter 1 thus formed, the heat conduction elements 54 are integrally formed with the capacitor housing 51. Accordingly, it is possible to treat the capacitor housing 51 and the heat conduction elements 54 as a single component and reduce the number of components. This can simplify the operation for manufacturing the power converter 1.

[0062] In the example described above, the filler element 52 is placed between the capacitor housing 51 and each of the N-side busbar 7, the P-side busbar 8, and the capacitor element 53. However, it is also possible to place an insulating element, different from the filler element 52, between the capacitor housing 51 and at least the N-side busbar 7, the P-side busbar 8, and / or the capacitor element 53. In this case, an element with a thermal conductivity greater than that of the filler element 52 is used as the insulating element. Furthermore, in this case, the element with an electrical insulation performance greater than that of the filler element 52 is used as the insulating element. The insulating element could be an insulating sheet of paper, a heat-conducting arc made of resin, a ceramic plate, or something similar.This enables simple heat transfer from at least the N-side busbar 7, the P-side busbar 8 and / or the capacitor element 53 to the capacitor housing 51 and the heat conduction element 54. Accordingly, it is possible to dissipate the heat in the capacitor module main body 50 more efficiently to the cooling surface 10.

[0063] The third embodiment is obtained by applying the thermal insulation element 57 to the power converter 1 of the second embodiment. However, it is equally possible to apply the thermal insulation element 57 to the power converter 1 of the first, fourth, or fifth embodiment.

[0064] In each of the embodiments described above, the heat-radiating section 541 is in contact with the cooling surface 10. However, the heat-radiating section 541 can also be arranged above the cooling surface 10 via a heat-conducting material with a heat transfer capacity of . In this case, the heat-radiating section 541 is thermally connected to the cooling surface 10 via the heat-conducting material. Furthermore, in this case, the heat-conducting material is positioned between the heat-radiating section 541 and the cooling surface 10, while maintaining close contact with both the heat-radiating section 541 and the cooling surface 10 without a gap between them. A heat-radiating grease, a heat-conducting arc formed from a resin, or something similar is used as the heat-conducting material. It is preferred that the heat-conducting material has a thermal conductivity greater than that of the respective heat-conducting elements 54.However, the thermal conductivity of the heat-conducting material can be equal to or less than the thermal conductivity of the individual heat-conducting elements 54. By adjusting the thermal conductivity of the heat-conducting material, it is possible to fill a gap formed between the heat-radiating section 541 and the cooling surface 10 with the heat-conducting material, thus allowing heat to be transferred more efficiently from the heat-radiating section 541 to the cooling surface 10. As a result, it is possible to dissipate heat more efficiently from the main body 50 of the capacitor module to the cooling surface 10.

[0065] Furthermore, in each of the embodiments described above, the heat-radiating section 541 is thermally connected to the cooling surface 10 at a position upstream of the position of the associated semiconductor module 4 in the flow of the cooling medium. However, the position of the heat-radiating section 541 is not limited to the position upstream of the position of the associated semiconductor module 4 in the flow of the cooling medium. For example, it is also possible for the heat-radiating section 541 to be thermally connected to the cooling surface 10 at a position displaced from the position of the associated semiconductor module 4 in a direction perpendicular to the direction of the flow of the cooling medium.

[0066] Furthermore, in each of the embodiments described above, the heat-radiating section 541 has a section that is arranged at a position further away from each of the semiconductor modules 4 than the area of ​​the cooling surface 10 that faces the capacitor module main body 50. However, it is also possible to arrange the entire heat-radiating section 541 at a position that is further away from the semiconductor modules 4 than the area of ​​the cooling surface 10 that faces the capacitor module main body 50.

Claims

[1] A power converter comprising: a cooling element (6) with a cooling surface (10) formed therein; a semiconductor module (4) provided on the cooling surface (10); and a capacitor module (5) comprising a capacitor module main body (50) opposite the cooling surface (10), at a distance from the cooling surface (10), and a heat conduction element (54) provided in the capacitor module main body (50), wherein - the capacitor module main body (50) is connected to the semiconductor module (4) via a busbar (7,8), wherein - the heat conduction element (54) has a heat radiation section (541), - the heat radiating section (541) is thermally connected to the cooling surface (10) at a position that is further away from the semiconductor module (4) than an end section of the capacitor module main body (50) that is closer to the semiconductor module (4), - the main body of the capacitor module (50) comprises a capacitor housing (51), a capacitor element (53) arranged in the capacitor housing (51), and a filler element (52) formed from a resin and covering the capacitor element (53) in the capacitor housing (51); and - the busbar (7,8) extends through the filler element (52) to be connected to the capacitor element (53), while the latter is held in the capacitor housing (51) above the filler element (52), - the heat conduction element (54) has an attachment section (542) which is arranged within the filling element (52); and - between the mounting section (542) and at least the capacitor element (53) and / or the busbar (7,8), an insulating element (56) with a thermal conductivity greater than that of the filling element (52) is placed. [2] A power converter, comprising: a cooling element (6) with a cooling surface (10) formed therein; a semiconductor module (4) provided on the cooling surface (10); and a capacitor module (5) comprising a capacitor module main body (50) opposite the cooling surface (10), at a distance from the cooling surface (10), and a heat conduction element (54) provided in the capacitor module main body (50), wherein - the capacitor module main body (50) is connected to the semiconductor module (4) via a busbar (7,8), wherein - the heat conduction element (54) has a heat radiation section (541), - the heat radiating section (541) is thermally connected to the cooling surface (10) at a position that is further away from the semiconductor module (4) than an end section of the capacitor module main body (50) that is closer to the semiconductor module (4), - the main body of the capacitor module (50) comprises a capacitor housing (51), a capacitor element (53) arranged in the capacitor housing (51), and a filler element (52) formed from a resin and covering the capacitor element (53) in the capacitor housing (51); and - the busbar (7,8) extends through the filler element (52) to be connected to the capacitor element (53), while the latter is held in the capacitor housing (51) above the filler element (52), - the capacitor housing (51) is made of the same material as that of the heat conduction element (54); and - the heat conduction element (54) is formed integrally with the capacitor housing (51), - an insulating element with a thermal conductivity greater than that of the filling element (52) is placed between the capacitor housing (51) and at least the capacitor element (53) and / or the busbar (7,8). [3] Power converter according to claim 1 or 2, wherein: the cooling surface (10) is cooled by a cooling medium flowing in the cooling element (6); and the heat radiating section (541) is thermally connected to the cooling surface (10) at a position that is upstream of a position of the semiconductor module (4) in a flow of the cooling medium. [4] Power converter according to claim 1 or 2, wherein a thermal insulation element (57) is placed between the capacitor module main body (50) and the cooling surface (10), the thermal insulation element being made of a material having a thermal conductivity lower than that of the capacitor module main body (50).

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