Coolers and power converters

Abstract

To provide a cooler and a power converter which efficiently cool each of a plurality of semiconductor packages.SOLUTION: A cooler includes: a first header having a lead-in port and a lead-out port of a coolant with a barrier which divides the inside into a first space communicating to the lead-in port and a second space communicating to the lead-out port; at least one upstream side cooling pipe internally having at least one first flow channel in which the coolant flows and which communicates with the first space; at least one downstream side cooling pipe internally having at least one second flow channel in which the coolant flows and which communicates with the second space; and a second header which leads out the coolant, led in from the first flow channel, to the second flow channel. The total sum of the cross sectional areas of second flow channel parts in which the coolant flows is smaller than the total sum of the cross sectional areas of first flow channel parts in which the coolant flows.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a cooler and a power converter. [Background technology]

[0002] Devices for cooling electronic components are known.

[0003] Patent document 1 discloses a semiconductor device in which the lower arm, which has a lower thermal resistance, is positioned downstream of the refrigerant flow, thereby mitigating the rise in semiconductor chip temperature downstream compared to the upstream side, thereby more effectively cooling the semiconductor chips positioned upstream and downstream.

[0004] Patent Document 2 discloses a cooler for semiconductor modules that can cool semiconductor elements uniformly and stably by adjusting the flow velocity distribution of the refrigerant based on the drift that occurs in the flow path and the heat generation distribution of the semiconductor elements, thereby eliminating the temperature rise of only some of the semiconductor elements.

[0005] Patent Document 3 discloses a power conversion device that suppresses variations in the cooling performance of a cooler for a plurality of semiconductor elements in the direction of coolant flow by increasing the flow rate of the coolant on the downstream side.

[0006] Patent Document 4 discloses a cooling device in which one flow path is formed alongside the other flow path in the thickness direction of the cooling pipe, and a protrusion is formed that protrudes in the thickness direction of the cooling pipe, thereby making it possible to partially reduce the dimension of the cooling pipe in the thickness direction while maintaining the cooling effect. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-228638 [Patent Document 2] International Publication No. 2013 / 054887 [Patent Document 3] Japanese Patent Application Publication No. 2018-121494 [Patent Document 4] Japanese Patent Application Publication No. 2018-006688 Summary of the Invention [Problem to be solved by the invention]

[0008] 2. Description of the Related Art Power converters that include a plurality of semiconductor packages are known. In the case of power converters that include a plurality of semiconductor packages, it is necessary to efficiently cool each of the plurality of semiconductor packages.

[0009] The present disclosure provides a cooler and a power converter that efficiently cools each of a plurality of semiconductor packages. [Means for solving the problem]

[0010] According to one aspect of the present disclosure, there is provided a cooler comprising: a first header having an inlet and an outlet for a refrigerant and having a partition wall dividing the interior into a first space communicating with the inlet and a second space communicating with the outlet; at least one first flow path through which the refrigerant flows, at least one upstream cooling pipe which communicates with the first space with the first flow path; at least one downstream cooling pipe having at least one second flow path through which the refrigerant flows, at least one second flow path which communicates with the second space with the second flow path; and a second header which discharges the refrigerant introduced from the first flow path to the second flow path, wherein the sum of the cross-sectional areas of the portions of the second flow paths through which the refrigerant flows is smaller than the sum of the cross-sectional areas of the portions of the first flow paths through which the refrigerant flows. [Effects of the Invention]

[0011] According to each embodiment of the present invention, it is possible to provide a cooler and a power converter that efficiently cools each of a plurality of semiconductor packages. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a power converter according to a first embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the power converter of the first embodiment. [Figure 3] FIG. 3 is a top view of the semiconductor package of the power converter according to the first embodiment. [Figure 4] FIG. 4 is a bottom view of the semiconductor package of the power converter according to the first embodiment. [Figure 5] FIG. 5 is a perspective view of a cooler of the power converter of the first embodiment. [Figure 6] FIG. 6 is an exploded perspective view of the cooler of the power converter of the first embodiment. [Figure 7] FIG. 7 is a perspective view of a header of a cooler of the power converter of the first embodiment. [Figure 8] FIG. 8 is a side view of the cooling pipe of the cooler of the power converter of the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view of the power converter of the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view of the power converter of the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view of a first modified example of the power converter of the first embodiment. [Figure 12] FIG. 12 is a cross-sectional view of a first modified example of the power converter of the first embodiment. [Figure 13] FIG. 13 is a cross-sectional view of a second modified example of the power converter of the first embodiment. [Figure 14] FIG. 14 is a cross-sectional view of a second modified example of the power converter of the first embodiment. [Figure 15] FIG. 15 is a cross-sectional view of a third modified example of the power converter of the first embodiment. [Figure 16] FIG. 16 is a cross-sectional view of a fourth modified example of the power converter of the first embodiment. [Figure 17] FIG. 17 is a cross-sectional view of a fifth modified example of the power converter of the first embodiment. [Figure 18] FIG. 18 is a cross-sectional view of the power converter of the second embodiment. [Figure 19] FIG. 19 is a cross-sectional view of a first modified example of the power converter of the second embodiment. [Figure 20] FIG. 20 is a cross-sectional view of a second modified example of the power converter of the second embodiment. [Figure 21] FIG. 21 is a cross-sectional view of a third modified example of the power converter of the second embodiment. [Figure 22] FIG. 22 is a cross-sectional view of the power converter of the third embodiment. [Figure 23] FIG. 23 is a cross-sectional view of a modified example of the power converter of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings. Note that in the description of each embodiment and in the drawings, components having substantially the same or corresponding functional configurations may be designated by the same reference numerals, and redundant description may be omitted. For ease of understanding, the scale of each part in the drawings may differ from the actual scale. Directions such as parallel, right-angled, orthogonal, horizontal, vertical, up / down, left / right, etc., are permitted to a degree that does not impair the effects of the embodiments. The shape of corners is not limited to right angles and may be rounded like an arch. Parallel, right-angled, orthogonal, horizontal, and vertical may include approximately parallel, approximately right-angled, approximately orthogonal, approximately horizontal, and approximately vertical.

[0014] <<First Embodiment>> <Power Converter 1> Fig. 1 is a perspective view of a power converter 1 according to the first embodiment. Fig. 2 is an exploded perspective view of the power converter 1 according to the first embodiment. The power converter 1 supplies power to, for example, each phase of a three-phase motor by converting direct current into alternating current using two semiconductor packages 20.

[0015] For ease of explanation, an XYZ Cartesian coordinate system may be set in the figures. For coordinate axes perpendicular to the plane of the drawing, a cross in a circle indicates that the direction toward the back of the plane of the drawing is positive, and a black circle in a circle indicates that the direction toward the front of the plane of the drawing is positive. However, this coordinate system is defined for the purpose of explanation and does not limit the orientation of the power converter 1, etc. In this disclosure, unless otherwise specified, the X-axis is the extension direction of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 of the cooler 30. The Y-axis is the direction in which the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 of the cooler 30 are adjacent to each other. The Y-axis direction may also be referred to as the up-down direction. The Z-axis is the direction perpendicular to the X-axis and Y-axis.

[0016] The power converter 1 includes a plurality of semiconductor packages 20 and a cooler 30.

[0017] The power converter 1 of this embodiment includes six semiconductor packages 20. Specifically, the power converter 1 includes a semiconductor package 21, a semiconductor package 22, a semiconductor package 23, a semiconductor package 24, a semiconductor package 25, and a semiconductor package 26. In the following description, when there is no need to distinguish between the semiconductor package 21, the semiconductor package 22, the semiconductor package 23, the semiconductor package 24, the semiconductor package 25, and the semiconductor package 26, they may be collectively referred to as the semiconductor package 20.

[0018] The semiconductor packages 20 are arranged and held in three rows and two columns between a first cooling pipe 30b1, a second cooling pipe 30b2, and a third cooling pipe 30b3 (described later) of the cooler 30. A coolant, for example, cooling water, is introduced into the cooler 30 through a coolant inlet 30ap1. The coolant introduced into the cooler 30 is discharged through a coolant outlet 30ap2. The semiconductor packages 20 are cooled by exchanging heat with the cooling water flowing through the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3.

[0019] Between the first cooling pipe 30b1 and the second cooling pipe 30b2, a semiconductor package 21, a semiconductor package 22, and a semiconductor package 23 are arranged in order from the first header 30a side. In addition, between the second cooling pipe 30b2 and the third cooling pipe 30b3, a semiconductor package 24, a semiconductor package 25, and a semiconductor package 26 are arranged in order from the first header 30a side.

[0020] The semiconductor package 20 and the cooler 30 of the power converter 1 will now be described in detail.

[0021] <Semiconductor Package 20> Fig. 3 is a top view of the semiconductor package 20 of the power converter 1 of the first embodiment. Fig. 4 is a bottom view of the semiconductor package 20 of the power converter 1 of the first embodiment.

[0022] The semiconductor package 20 is, for example, a so-called 2-in-1 semiconductor package in which two semiconductor elements constituting upper and lower arms for one phase are packaged. The semiconductor package 20 is also a so-called double-sided cooling type semiconductor package. The semiconductor package 20 contains semiconductor elements such as power transistors, for example, an IGBT (Insulated Gate Bipolar Transistor) and an FET (Field-Effect Transistor).

[0023] The semiconductor package 20 includes a case 20d that is substantially rectangular and made of resin, such as epoxy resin, etc. The case 20d has an upper surface 20dA and a lower surface 20dB opposite to the upper surface 20dA.

[0024] Semiconductor package 20 has current terminals 20a1, 20a2, and 20a3, and control terminals 20b1, 20b2, 20b3, and 20b4 on the side surface of case 20d. Current terminals 20a1, 20a2, and 20a3, and control terminals 20b1, 20b2, 20b3, and 20b4 are provided to protrude from the side surface of case 20d of semiconductor package 20.

[0025] Current terminal 20a1, current terminal 20a2, and current terminal 20a3 are, for example, terminals for passing current to a load. Current terminal 20a1, current terminal 20a2, and current terminal 20a3 are formed of a conductive material. Control terminal 20b1, control terminal 20b2, control terminal 20b3, and control terminal 20b4 are terminals for controlling the current passed through the load. Control terminal 20b1, control terminal 20b2, control terminal 20b3, and control terminal 20b4 are formed of a conductive material.

[0026] The semiconductor package 20 also has heat sinks 20c1 and 20c2. For example, a power transistor built into the semiconductor package 20 is a heat-generating element and therefore needs to be cooled. The heat sinks 20c1 and 20c2 are provided to dissipate heat from the heat-generating element. The heat sinks 20c1 and 20c2 are made of a material with high thermal conductivity, for example, a metal such as copper. The heat sinks 20c1 and 20c2 are thermally connected to the heat-generating element. The heat sink 20c1 is provided on an upper surface 20dA of the case 20d. The heat sink 20c2 is provided on a lower surface 20dB of the case 20d.

[0027] <Cooler 30> Fig. 5 is a perspective view of the cooler 30 of the power converter 1 of the first embodiment. Fig. 6 is an exploded perspective view of the cooler 30 of the power converter 1 of the first embodiment.

[0028] The cooler 30 cools the semiconductor package 20. A refrigerant flows through the inside of the cooler 30. The cooler 30 cools the semiconductor package 20 by exchanging heat between the refrigerant (e.g., cooling water) flowing through the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 and the semiconductor package 20. The refrigerant is not limited to water, and may be a liquid including antifreeze.

[0029] The cooler 30 includes a first header 30a, a first cooling pipe 30b1, a second cooling pipe 30b2, a third cooling pipe 30b3, and a second header 30c. The second header 30c is provided spaced apart from the first header 30a in the X-axis direction. The first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are provided at predetermined intervals in the Y-axis direction, i.e., a direction intersecting the X-axis direction, specifically, at intervals that can hold the semiconductor package 20.

[0030] The first header 30a is connected to one end of each of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3. Specifically, the first header 30a is connected to the -X side end of each of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3. The second header 30c is connected to the other end of each of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3. Specifically, the second header 30c is connected to the +X side end of each of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3.

[0031] [First header 30a] First, the first header 30a will be described. Fig. 7 is a perspective view of the first header 30a of the cooler 30 of the power converter 1 of the first embodiment. The first header 30a introduces the refrigerant into the inside of the cooler 30 and discharges it to the outside of the cooler 30. The first header 30a has a hollow cubic shape and is composed of wall portions 30aA, 30aB, 30aC, 30aD, 30aE, and 30aF.

[0032] A portion of wall 30aE, which is the wall on the +X side of first header 30a, is exposed. Specifically, first header 30a has openings 30ah1, 30ah2, and 30ah3 in wall 30aE. One ends of first cooling pipe 30b1, second cooling pipe 30b2, and third cooling pipe 30b3 are inserted into and fixed to openings 30ah1, 30ah2, and 30ah3 of first header 30a, respectively. The first header 30a and the first cooling pipe 30b1, second cooling pipe 30b2, and third cooling pipe 30b3 are fixed by brazing, for example, to ensure watertightness.

[0033] The first header 30a has a refrigerant inlet 30ap1 and a refrigerant outlet 30ap2 in the wall portion 30aF. The refrigerant inlet 30ap1 is introduced from an external cooling device. The refrigerant outlet 30ap2 is discharged to the external cooling device. The first header 30a has a partition wall therein, which will be described later. The partition wall separates the refrigerant introduced into the first header 30a from the refrigerant discharged from the first header 30a. The partition wall will be described in detail later.

[0034] [First cooling pipe 30b1, second cooling pipe 30b2, third cooling pipe 30b3] Next, the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 will be described. Fig. 8 is a side view of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 of the cooler 30 of the power converter 1 of the first embodiment. The first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are pipes with open longitudinal ends through which a refrigerant flows. Furthermore, the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 cool the semiconductor package 20 by exchanging heat with the refrigerant flowing through the cooling pipes.

[0035] The cross sections of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 in the short side direction have an outer shape that is approximately rectangular. The first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are so-called microchannels having divided flow paths 30bc inside.

[0036] The first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 have flow paths 30bc that are rectangular microchannels that are long in the Y-axis direction (vertical direction). The flow paths 30bc may be divided into two or more stages in the Y-axis direction.

[0037] The first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 have cooling surfaces 30bA and 30bB. When the semiconductor package 20 is cooled by the cooler 30, the semiconductor package 20 to be cooled is provided in contact with the cooling surface 30bA or the cooling surface 30bB. Specifically, the cooling surface 30bA or the cooling surface 30bB is thermally joined to the heat sink 20c1 or the heat sink 20c2 of the semiconductor package 20 by soldering, thermally conductive grease, or the like.

[0038] The flow paths 30bc of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 each have a uniform cross-sectional area in the extension direction of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3. The extension direction of the flow paths 30bc of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 and the refrigerant flow direction coincide with each other in the X-axis direction. In this disclosure, the cross-sectional area of the flow path 30bc refers to the cross-sectional area of a plane perpendicular to the extension direction of the flow path 30bc, i.e., the refrigerant flow direction.

[0039] In at least one of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3, the refrigerant flows in the direction from the first header 30a to the second header 30c, and in the remaining cooling pipes, the refrigerant flows in the direction from the second header 30c to the first header 30a. In the following description, the cooling pipe through which the refrigerant flows in the direction from the first header 30a to the second header 30c may be referred to as the upstream cooling pipe, and the cooling pipe through which the refrigerant flows in the direction from the second header 30c to the first header 30a may be referred to as the downstream cooling pipe.

[0040] [Second header 30c] The second header 30c guides the refrigerant introduced from at least one of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 to the remaining cooling pipes of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3. In other words, the second header 30c guides the refrigerant introduced from the upstream cooling pipe to the downstream cooling pipe.

[0041] The second header 30c is hollow and open on one side. Specifically, the second header 30c has openings 30ch1, 30ch2, and 30ch3 on the -X side. The other ends of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are inserted into and fixed to the open side of the second header 30c. Specifically, the other end of the first cooling pipe 30b1 is inserted into and fixed to the opening 30ch1. The other end of the second cooling pipe 30b2 is inserted into and fixed to the opening 30ch2. The other end of the third cooling pipe 30b3 is inserted into and fixed to the opening 30ch3. The second header 30c and the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are fixed by brazing, for example, to ensure watertightness.

[0042] <Bulkhead of the first header 30a> Here, the partition walls provided in the first header 30a will be described. First, the conditions for determining the positions of the partition walls provided in the first header 30a will be described.

[0043] The refrigerant introduced into the cooler 30 from an external cooling device absorbs heat from the semiconductor package 20 and is discharged from the cooler 30. Therefore, the refrigerant flowing through the cooler 30 is at its lowest temperature immediately after being introduced, and gradually increases in temperature as it absorbs heat. In other words, the temperature of the refrigerant flowing through the downstream cooling pipe is higher than the temperature of the refrigerant flowing through the upstream cooling pipe. Therefore, there is a possibility that temperature variations will occur between when the semiconductor package 20 is cooled by the upstream cooling pipe and when the semiconductor package 20 is cooled by the downstream cooling pipe.

[0044] In the power converter 1 of this embodiment, the flow rate of the refrigerant flowing through the downstream cooling pipe is made faster than the flow rate of the refrigerant flowing through the upstream cooling pipe, thereby suppressing variations in cooling of the semiconductor package 20. More specifically, in order to make the flow rate of the refrigerant flowing through the downstream cooling pipe faster than the flow rate of the refrigerant flowing through the upstream cooling pipe, the sum of the cross-sectional areas of the portions of the flow paths of the downstream cooling pipe through which the refrigerant flows is made smaller than the sum of the cross-sectional areas of the portions of the flow paths of the upstream cooling pipe through which the refrigerant flows. By making the sum of the cross-sectional areas of the portions of the flow paths of the downstream cooling pipe through which the refrigerant flows smaller than the sum of the cross-sectional areas of the flow paths of the upstream cooling pipe, the flow rate of the refrigerant flowing through the downstream cooling pipe can be made faster than the flow rate of the refrigerant flowing through the upstream cooling pipe.

[0045] If the temperature difference between the semiconductor package 20 and the refrigerant flowing through the cooler 30 is ΔT and the area of thermal contact between the semiconductor package 20 and the cooler 30 is A, the amount of heat transferred from the semiconductor package 20 to the cooler 30, Q, is expressed by Equation 1.

[0046] Q=K·A·ΔT (Equation 1)

[0047] Here, K represents the overall heat transfer coefficient.

[0048] In the upstream cooling pipe, the temperature of the refrigerant is low, and a large temperature difference can be achieved with the semiconductor package 20. In other words, the logarithmic mean temperature difference ΔT can be increased. Therefore, by increasing the logarithmic mean temperature difference ΔT, the amount of heat transferred from the semiconductor package 20 to the cooler 30 can be increased. Furthermore, by increasing the amount of heat transferred from the semiconductor package 20 to the cooler 30, the semiconductor package 20 can be cooled efficiently.

[0049] Furthermore, the temperature of the refrigerant is high in the downstream flow path, and the temperature difference with the semiconductor package 20 is smaller than in the upstream flow path. Therefore, in the power converter 1 of this embodiment, the flow velocity of the downstream cooling pipe is increased. Increasing the flow velocity increases the overall heat transfer coefficient K. Therefore, by increasing the overall heat transfer coefficient K, the amount of heat transferred from the semiconductor package 20 to the cooler 30 can be increased. Furthermore, by increasing the amount of heat transferred from the semiconductor package 20 to the cooler 30, the semiconductor package 20 can be cooled efficiently.

[0050] Next, the position of the partition wall provided in the first header 30a will be described.

[0051] In the power converter 1 of the first embodiment, the partition wall 30aw of the first header 30a is formed so that the flow velocity of the downstream cooling pipe is faster than that of the upstream cooling pipe. Specifically, two cooling pipes, the first cooling pipe 30b1 and the second cooling pipe 30b2, are defined as upstream cooling pipes. Furthermore, one cooling pipe, the third cooling pipe 30b3, is defined as downstream cooling pipe. That is, in the power converter 1 of the first embodiment, the number of cooling pipes is made greater than that of the upstream cooling pipes, so that the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the downstream cooling pipes is made smaller than that of the portions of the flow paths through which the refrigerant flows in the upstream cooling pipes. Furthermore, by making the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the downstream cooling pipes smaller than that of the portions of the flow paths through which the refrigerant flows in the upstream cooling pipes, the flow velocity of the downstream cooling pipes is made faster than that of the upstream cooling pipes.

[0052] 9 and 10 are cross-sectional views of the power converter 1 of the first embodiment. Specifically, FIG. 9 is a cross-sectional view of the power converter 1 taken along a plane perpendicular to the X-axis direction at the first header 30a. Specifically, FIG. 10 is a cross-sectional view of the power converter 1 taken along a plane perpendicular to the Z-axis direction at the center of the power converter 1 in the Z direction. Note that the semiconductor package 20 is shown as a uniform cross section, with internal details omitted.

[0053] In the power converter 1 of the first embodiment, the partition wall 30aw is provided so that the first cooling pipe 30b1 and the second cooling pipe 30b2 are upstream cooling pipes and the third cooling pipe 30b3 is downstream cooling pipe. The partition wall 30aw extends in the X-axis direction from the wall portion 30aF to the wall portion 30aE of the first header 30a.

[0054] The first cooling pipe 30b1 and the second cooling pipe 30b2 communicate with a space SPin surrounded by a part of the wall 30aA, the wall 30aB, a part of the wall 30aC, the partition wall 30aw, the wall 30aE, and the wall 30aF. A refrigerant is introduced into the space SPin from the refrigerant inlet 30ap1. The refrigerant introduced into the space SPin is discharged from the first cooling pipe 30b1 and the second cooling pipe 30b2 which communicate with the space SPin.

[0055] On the other hand, the third cooling pipe 30b3 communicates with a space SPout surrounded by a part of the wall 30aA, the partition wall 30aw, a part of the wall 30aC, the wall 30aD, the wall 30aE, and the wall 30aF. A refrigerant is introduced from the third cooling pipe 30b3 communicating with the space SPout. The refrigerant introduced into the space SPout is discharged from the refrigerant outlet 30ap2.

[0056] In the power converter 1 of the first embodiment, the cross-sectional areas of the refrigerant flowing through the flow paths of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are equal. Therefore, in the power converter 1 of the first embodiment, the number of upstream cooling pipes and the number of downstream cooling pipes are changed so that the sum of the cross-sectional areas of the refrigerant flowing through the flow paths of the first cooling pipe 30b1 and the second cooling pipe 30b2, which are the upstream cooling pipes, is smaller than the sum of the cross-sectional areas of the refrigerant flowing through the flow paths of the third cooling pipe 30b3, which is the downstream cooling pipe. In this case, the sum of the cross-sectional areas of the refrigerant flowing through the flow paths of the first cooling pipe 30b1 and the second cooling pipe 30b2, which are the upstream cooling pipes, is twice the sum of the cross-sectional areas of the refrigerant flowing through the flow paths of the third cooling pipe 30b3, which is the downstream cooling pipe. Note that "twice the sum" is not limited to being exactly doubled, but may include being doubled within the range of, for example, manufacturing tolerances.

[0057] The space SPin is an example of a first space, and the space SPout is an example of a second space. The flow paths 30bc of the first cooling pipe 30b1 and the second cooling pipe 30b2 are an example of a first flow path, and the flow path 30bc of the third cooling pipe 30b3 is an example of a second flow path.

[0058] <Actions and Effects> In the power converter 1 of the first embodiment, the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the first cooling pipe 30b1 and the second cooling pipe 30b2, which are upstream cooling pipes, is made smaller than the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the third cooling pipe 30b3, which is the downstream cooling pipe. Furthermore, in the power converter 1 of the first embodiment, the flow velocity of the refrigerant in the third cooling pipe 30b3, which is the downstream cooling pipe, is made faster than the flow velocity of the refrigerant in the first cooling pipe 30b1 and the second cooling pipe 30b2, which are upstream cooling pipes. By making the flow velocity of the refrigerant in the downstream cooling pipe faster than the flow velocity of the refrigerant in the upstream cooling pipe, it is possible to suppress variations in the cooling efficiency between the upstream cooling pipe and the downstream cooling pipe.

[0059] In the power converter 1 of the first embodiment, the cooling pipe at the end in the Y direction (third cooling pipe 30b3) is set as the downstream cooling pipe. For example, when the gravity direction is set to the -Y direction, it is possible to easily discharge air bubbles contained in the refrigerant.

[0060] <<First Modification of First Embodiment>> 11 and 12 are cross-sectional views of a first modified example of the power converter 1 of the first embodiment. Specifically, FIG. 1 is a cross-sectional view of the first modified example of the power converter 1 taken along a plane perpendicular to the X-axis direction at the first header 31a portion. Specifically, FIG. 10 is a cross-sectional view of the first modified example of the power converter 1 taken along a plane perpendicular to the Z-axis direction at the center portion in the Z direction. Note that the semiconductor package 20 is shown as a uniform cross section, with internal details omitted.

[0061] In addition, components having substantially the same or corresponding functional configurations may be assigned the same reference numerals and redundant description may be omitted. The same applies to the following modified examples and embodiments.

[0062] In the first modification of the power converter 1 of the first embodiment, the partition wall 31aw of the first header 31a is provided so that the first cooling pipe 30b1 and the third cooling pipe 30b3 are upstream cooling pipes and the second cooling pipe 30b2 is downstream cooling pipe. The partition wall 31aw extends in the X-axis direction from the wall portion 31aF to the wall portion 31aE of the first header 31a.

[0063] The cooler 31 includes a first header 31a, a first cooling pipe 30b1, a second cooling pipe 30b2, a third cooling pipe 30b3, and a second header 30c.

[0064] The first cooling pipe 30b1 and the third cooling pipe 30b3 communicate with a space SPin surrounded by part of the wall 31aA, part of the wall 31aB, part of the wall 31aC, the partition wall 31aw, and the wall 31aE and the wall 31aF. A refrigerant is introduced into the space SPin from the refrigerant inlet 31ap1. The refrigerant introduced into the space SPin is discharged from the first cooling pipe 30b1 and the third cooling pipe 30b3 which communicate with the space SPin.

[0065] On the other hand, the second cooling pipe 30b2 communicates with a space SPout surrounded by a part of the wall 31aA, the partition wall 31aw, a part of the wall 31aC, the wall 31aD, the wall 31aE, and the wall 31aF. A refrigerant is introduced from the second cooling pipe 30b2 communicating with the space SPout. The refrigerant introduced into the space SPout is discharged from the refrigerant outlet 31ap2.

[0066] <Actions and Effects> In the first modified example of the power converter 1 of the first embodiment, the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the first cooling pipe 30b1 and the third cooling pipe 30b3, which are upstream cooling pipes, is made smaller than the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the second cooling pipe 30b2, which is the downstream cooling pipe. Furthermore, in the first modified example of the power converter 1 of the first embodiment, the flow velocity of the refrigerant in the second cooling pipe 30b2, which is the downstream cooling pipe, is made faster than the flow velocity of the refrigerant in the first cooling pipe 30b1 and the third cooling pipe 30b3, which are upstream cooling pipes. By making the flow velocity of the refrigerant in the downstream cooling pipe faster than the flow velocity of the refrigerant in the upstream cooling pipe, it is possible to suppress variations in the cooling efficiency between the upstream cooling pipe and the downstream cooling pipe.

[0067] Furthermore, by arranging the first cooling pipe 30b1 and the third cooling pipe 30b3, which are upstream cooling pipes, symmetrically with respect to the second cooling pipe 30b2, which is the downstream cooling pipe, the flow of the refrigerant can be made uniform.

[0068] <<Second Modification of First Embodiment>> 13 and 14 are cross-sectional views of a second modified example of the power converter 1 of the first embodiment. Specifically, FIG. 13 is a cross-sectional view of the second modified example of the power converter 1 taken along a plane perpendicular to the X-axis direction at the first header 32a. Specifically, FIG. 14 is a cross-sectional view of the second modified example of the power converter 1 taken along a plane perpendicular to the Z-axis direction at the center in the Z direction. Note that the semiconductor package 20 is shown as a uniform cross section, with internal details omitted.

[0069] In the second modification of the power converter 1 of the first embodiment, the partition wall 32aw of the first header 32a is provided so that the second cooling pipe 30b2 is the upstream cooling pipe and the first cooling pipe 32b1 and the third cooling pipe 32b3 are the downstream cooling pipes. The partition wall 32aw extends in the X-axis direction from the wall portion 32aF to the wall portion 32aE of the first header 32a.

[0070] The cooler 32 includes a first header 32a, a first cooling pipe 32b1, a second cooling pipe 32b2, a third cooling pipe 32b3, and a second header 30c.

[0071] The first cooling pipe 32b1 has a different flow path shape from the first cooling pipe 30b1 of the first embodiment. Specifically, the first cooling pipe 32b1 has a flow path formed on the -Y side from the center. The cross-sectional area of the portion of the flow path of the first cooling pipe 32b1 through which the refrigerant flows is less than half of that of the second cooling pipe 30b2. Similarly, the third cooling pipe 32b3 has a different flow path shape from the third cooling pipe 32b3 of the first embodiment. Specifically, the third cooling pipe 32b3 has a flow path formed on the +Y side from the center. The cross-sectional area of the portion of the flow path of the third cooling pipe 32b3 through which the refrigerant flows is less than half of that of the second cooling pipe 30b2.

[0072] The second cooling pipe 30b2 communicates with a space SPin surrounded by part of the wall 32aA, part of the wall 32aB, part of the wall 32aC, the partition wall 32aw, and the wall 32aE and the wall 32aF. A refrigerant is introduced into the space SPin from the refrigerant inlet 32ap1. The refrigerant introduced into the space SPin is discharged from the second cooling pipe 30b2 which communicates with the space SPin.

[0073] Meanwhile, the first cooling pipe 32b1 and the third cooling pipe 32b3 communicate with a space SPout surrounded by a part of the wall 32aA, the partition wall 32aw, a part of the wall 32aC, the wall 32aD, the wall 32aE, and the wall 32aF. A refrigerant is introduced from the first cooling pipe 32b1 and the third cooling pipe 32b3, which communicate with the space SPout. The refrigerant introduced into the space SPout is discharged from the refrigerant outlet 32ap2.

[0074] <Actions and Effects> In the second modified example of the power converter 1 of the first embodiment, the sum of the cross-sectional areas of the portions of the flow path through which the refrigerant flows in the second cooling pipe 30b2, which is the upstream cooling pipe, is made smaller than the sum of the cross-sectional areas of the portions of the flow path through which the refrigerant flows in the first cooling pipe 32b1 and the third cooling pipe 32b3, which are the downstream cooling pipes. Furthermore, in the second modified example of the power converter 1 of the first embodiment, the flow rate of the refrigerant in the first cooling pipe 32b1 and the third cooling pipe 32b3, which are the downstream cooling pipes, is made faster than the flow rate of the refrigerant in the second cooling pipe 30b2, which is the upstream cooling pipe. By making the flow rate of the refrigerant in the downstream cooling pipe faster than the flow rate of the refrigerant in the upstream cooling pipe, it is possible to suppress variations in the cooling efficiency between the upstream cooling pipe and the downstream cooling pipe.

[0075] <<Third Modification of First Embodiment>> Fig. 15 is a cross-sectional view of a third modified example of the power converter 1 of the first embodiment. Specifically, Fig. 15 is a cross-sectional view of the third modified example of the power converter 1 taken along a plane perpendicular to the Z-axis direction at the center in the Z direction. Note that the semiconductor package 20 is shown as a uniform cross section, with internal details omitted.

[0076] The third modification of the power converter 1 of the first embodiment includes two cooling pipes, namely, a first cooling pipe 33b1 and a second cooling pipe 33b2. In the third modification, the first cooling pipe 33b1 is the upstream cooling pipe and the second cooling pipe 33b2 is the downstream cooling pipe.

[0077] The cross-sectional area of the first cooling pipe 33b1, which is the upstream pipe, is different from the cross-sectional area of the second cooling pipe 33b2, which is the downstream pipe. Specifically, the cross-sectional area of the second cooling pipe 33b2 is smaller than that of the first cooling pipe 33b1. Because the cross-sectional area of the second cooling pipe 22b2 is smaller than that of the first cooling pipe 33b1, the flow rate of the refrigerant flowing through the second cooling pipe 22b2 is faster than the flow rate of the refrigerant flowing through the first cooling pipe 33b1.

[0078] The cooler 33 includes a first header 33a, a first cooling pipe 33b1, a second cooling pipe 33b2, and a second header 33c.

[0079] In the third modification, the flow rate of the refrigerant in the first cooling pipe 33b1, which is the upstream cooling pipe, is faster than the flow rate of the refrigerant in the second cooling pipe 33b2, which is the downstream cooling pipe. Specifically, the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the first cooling pipe 33b1, which is the upstream cooling pipe, is larger than the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the second cooling pipe 33b2, which is the downstream cooling pipe.

[0080] <Actions and Effects> In the third modified example of the power converter 1 of the first embodiment, the sum of the cross-sectional areas of the portions of the flow path through which the refrigerant flows in the first cooling pipe 33b1, which is the upstream cooling pipe, is made smaller than the sum of the cross-sectional areas of the portions of the flow path through which the refrigerant flows in the second cooling pipe 33b2, which is the downstream cooling pipe. Furthermore, in the third modified example of the power converter 1 of the first embodiment, the flow velocity of the refrigerant in the second cooling pipe 33b2, which is the downstream cooling pipe, is made faster than the flow velocity of the refrigerant in the first cooling pipe 33b1, which is the upstream cooling pipe. By making the flow velocity of the refrigerant in the downstream cooling pipe faster than the flow velocity of the refrigerant in the upstream cooling pipe, it is possible to suppress variations in the cooling efficiency between the upstream and downstream cooling pipes.

[0081] <<Fourth Modification of First Embodiment>> Fig. 16 is a cross-sectional view of a fourth modified example of the power converter 1 of the first embodiment. Specifically, Fig. 16 is a cross-sectional view of the fourth modified example of the power converter 1 taken along a plane perpendicular to the Z-axis direction at the center in the Z direction. Note that the semiconductor package 20 is shown as a uniform cross section, with internal details omitted.

[0082] The fourth modification of the power converter 1 of the first embodiment includes four cooling pipes, namely, a first cooling pipe 34b1, a second cooling pipe 34b2, a third cooling pipe 34b3, and a fourth cooling pipe 34b4. In the fourth modification, the first cooling pipe 34b1 and the second cooling pipe 34b2 are upstream cooling pipes, and the third cooling pipe 34b3 and the fourth cooling pipe 34b4 are downstream cooling pipes.

[0083] The sum of the cross-sectional areas of the first cooling pipe 34b1 and the second cooling pipe 34b2, which are upstream pipes, is different from the sum of the cross-sectional areas of the third cooling pipe 34b3 and the fourth cooling pipe 34b4, which are downstream pipes. Specifically, the cross-sectional area of the fourth cooling pipe 34b4 is smaller than the cross-sectional areas of the first cooling pipe 34b1, the second cooling pipe 34b2, and the third cooling pipe 34b3. Therefore, the sum of the cross-sectional areas of the third cooling pipe 34b3 and the fourth cooling pipe 34b4, which are downstream pipes, is smaller than the sum of the cross-sectional areas of the first cooling pipe 34b1 and the second cooling pipe 34b2, which are upstream pipes. Because the sum of the cross-sectional areas of the downstream pipes is smaller than the sum of the cross-sectional areas of the upstream pipes, the flow velocity of the refrigerant flowing through the downstream pipes is faster than the flow velocity of the refrigerant flowing through the upstream pipes.

[0084] The cooler 33 includes a first header 34a, a first cooling pipe 34b1, a second cooling pipe 34b2, a third cooling pipe 34b3, a fourth cooling pipe 34b4, and a second header 34c.

[0085] In the fourth modification, the flow rate of the refrigerant in the first cooling pipe 34b1 and the second cooling pipe 34b2, which are the upstream cooling pipes, is faster than the flow rate of the refrigerant in the third cooling pipe 33b3 and the fourth cooling pipe 34b4, which are the downstream cooling pipes. Specifically, the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the first cooling pipe 34b1 and the second cooling pipe 34b2, which are the upstream cooling pipes, is larger than the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the third cooling pipe 34b3 and the fourth cooling pipe 34b4, which are the downstream cooling pipes.

[0086] <Actions and Effects> In the fourth modification of the power converter 1 of the first embodiment, the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the first cooling pipe 34b1 and the second cooling pipe 34b2, which are upstream cooling pipes, is made smaller than the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the third cooling pipe 34b3 and the fourth cooling pipe 34b4, which are downstream cooling pipes. Furthermore, in the fourth modification of the power converter 1 of the first embodiment, the flow velocity of the refrigerant in the third cooling pipe 34b3 and the fourth cooling pipe 34b4, which are downstream cooling pipes, is made faster than the flow velocity of the refrigerant in the first cooling pipe 34b1 and the second cooling pipe 34b2, which are upstream cooling pipes. By making the flow velocity of the refrigerant in the downstream cooling pipe faster than the flow velocity of the refrigerant in the upstream cooling pipe, it is possible to suppress variations in the cooling efficiency between the upstream cooling pipe and the downstream cooling pipe.

[0087] <<Fifth Modification of First Embodiment>> Fig. 17 is a cross-sectional view of a fifth modified example of the power converter 1 of the first embodiment. Specifically, Fig. 17 is a cross-sectional view of the fifth modified example of the power converter 1 taken along a plane perpendicular to the Z-axis direction at the center in the Z direction. Note that the semiconductor package 20 is shown as a uniform cross section, with internal details omitted.

[0088] In the fifth modified example of the power converter 1 of the first embodiment, a second cooling pipe 35b2 is used instead of the second cooling pipe 30b2 of the power converter 1 of the first embodiment. The second cooling pipe 35b2 is thicker in the Y direction than the second cooling pipe 30b2. Because the second cooling pipe 35b2 is thicker in the Y direction, the cross-sectional area of the portion of the flow path through which the refrigerant flows is larger than that of the second cooling pipe 30b2.

[0089] The cooler 35 includes a first header 35a, a first cooling pipe 30b1, a second cooling pipe 35b2, a third cooling pipe 30b3, and a second header 35c.

[0090] <Actions and Effects> In the fifth modification of the power converter 1 of the first embodiment, the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the first cooling pipe 30b1 and the second cooling pipe 35b2, which are upstream cooling pipes, is made smaller than the sum of the cross-sectional areas of the portions of the flow paths through which the refrigerant flows in the third cooling pipe 30b3, which is the downstream cooling pipe. In the fifth modification of the power converter 1 of the first embodiment, the flow velocity of the refrigerant in the third cooling pipe 30b3, which is the downstream cooling pipe, is made faster than the flow velocity of the refrigerant in the first cooling pipe 30b1 and the second cooling pipe 35b2, which are upstream cooling pipes. By making the flow velocity of the refrigerant in the downstream cooling pipe faster than the flow velocity of the refrigerant in the upstream cooling pipe, it is possible to suppress variations in the cooling efficiency between the upstream cooling pipe and the downstream cooling pipe.

[0091] Furthermore, the cooling capacity of the second cooling pipe 35b2 is increased by thickening the second cooling pipe 35b2, which is in contact with the semiconductor package 20 on both sides. By increasing the cooling capacity of the second cooling pipe 35b2, it is possible to reduce variations in cooling efficiency.

[0092] <<Second embodiment>> In the power converter of the second embodiment, the second header rectifies the flow of the refrigerant that flows in. By rectifying the flow of the refrigerant that flows in the second header, the variation in the amount of refrigerant that flows in between the multiple cooling pipes is reduced.

[0093] Fig. 18 is a cross-sectional view of the power converter of the second embodiment. Specifically, Fig. 18 is a cross-sectional view of the power converter taken along a plane perpendicular to the Z-axis direction at the center of the power converter in the Z direction. Fig. 18 shows an enlarged view of the vicinity of the second header 36c.

[0094] The cooler 36 of the second embodiment includes a first header 30a (not shown), a first cooling pipe 30b1, a second cooling pipe 30b2, a third cooling pipe 30b3, and a second header 36c.

[0095] The second header 36c of the power converter of the second embodiment has a rectifying wall 36cw. The rectifying wall 36cw has an L-shaped cross section. The rectifying wall 36cw is provided inside the second header 36c. The rectifying wall 36cw is provided at a position facing the refrigerant outlet of the second cooling pipe 30b2. That is, the rectifying wall 36cw is provided extending in the Z direction, and the end of the Z direction is joined to the inner surface of the second header 36c by brazing or the like. Furthermore, the end of the rectifying wall 36cw in the -X direction is joined to the inner surface of the second header 36c by brazing or the like.

[0096] The flow straightening wall 36cw sends the refrigerant introduced from the second cooling pipe 30b2, which is the upstream cooling pipe, toward the third cooling pipe 30b3, which is the downstream cooling pipe. Furthermore, the flow straightening wall 36cw separates the refrigerant flow from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flow from the second cooling pipe 30b2 to the third cooling pipe 30b3 inside the second header 36c. The refrigerant in the second cooling pipe 30b2 is sent toward the third cooling pipe 30b3, and the refrigerant flow from the first cooling pipe 30b1 to the third cooling pipe 30b3 is separated from the refrigerant flow from the second cooling pipe 30b2 to the third cooling pipe 30b3, allowing the refrigerant in the upstream cooling pipe to flow smoothly into the downstream cooling pipe.

[0097] Furthermore, by separating the flow of refrigerant from the first cooling pipe 30b1 to the third cooling pipe 30b3 from the flow of refrigerant from the second cooling pipe 30b2 to the third cooling pipe 30b3, the variation in the flow rate of refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 is reduced.

[0098] <Actions and Effects> In the power converter of the second embodiment, by providing the flow straightening wall 36cw in the second header 36c, it is possible to suppress variations in the flow rate of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2.

[0099] For example, without the flow straightening wall 36cw, the refrigerant introduced from the second cooling pipe 30b2 may obstruct the flow of the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3. Furthermore, the refrigerant from the first cooling pipe 30b1 and the refrigerant from the second cooling pipe 30b2 may mix, generating a vortex. As described above, the flow of the refrigerant introduced from the first cooling pipe 30b1 may be disrupted by the refrigerant introduced from the second cooling pipe 30b2 or by the generated vortex, causing the flow rate of the refrigerant flowing through the first cooling pipe 30b1 to be less than the flow rate of the refrigerant flowing through the second cooling pipe 30b2. If the flow rate of the refrigerant flowing through the first cooling pipe 30b1 is reduced, the semiconductor package 20 cooled by the first cooling pipe 30b1 may not be sufficiently cooled.

[0100] In the power converter of the second embodiment, the provision of the flow straightening wall 36cw allows the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly. By allowing the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly, the flow rates of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 can be made uniform.

[0101] <<First Modification of Second Embodiment>> Fig. 19 is a cross-sectional view of a first modified example of the power converter of the second embodiment. Specifically, Fig. 19 is a cross-sectional view of the power converter taken along a plane perpendicular to the Z-axis direction at the center of the power converter in the Z direction. Fig. 19 shows an enlarged view of the vicinity of the second header 37c.

[0102] The cooler 37 of the first modified example of the second embodiment includes a first header 30a (not shown), a first cooling pipe 30b1, a second cooling pipe 30b2, a third cooling pipe 30b3, and a second header 37c.

[0103] In the first modified example of the power converter of the second embodiment, the shape of the rectifying wall is different. The second header 37c has a rectifying wall 37cw. The rectifying wall 37cw has an arc-shaped cross section. The rectifying wall 37cw is provided inside the second header 37c. The rectifying wall 37cw is provided at a position facing the refrigerant outlet of the second cooling pipe 30b2. The rectifying wall 37cw is provided extending in the Z direction, and the end portion in the Z direction is joined to the inner surface of the second header 37c by brazing or the like. Furthermore, the end portion in the -X direction of the rectifying wall 37cw is joined to the inner surface of the second header 37c by brazing or the like.

[0104] The flow straightening wall 37cw separates the refrigerant flow from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flow from the second cooling pipe 30b2 to the third cooling pipe 30b3 inside the second header 37c. By separating the refrigerant flow from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flow from the second cooling pipe 30b2 to the third cooling pipe 30b3, variation in the flow rate of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 is reduced.

[0105] <Actions and Effects> In the first modified example of the power converter of the second embodiment, by providing the flow straightening wall 37cw in the second header 37c, it is possible to suppress variations in the flow rate of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2.

[0106] In the first modified example of the power converter of the second embodiment, the provision of the flow straightening wall 36cw allows the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly. By allowing the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly, the flow rates of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 can be made uniform.

[0107] <<Second Modification of Second Embodiment>> Fig. 20 is a cross-sectional view of a second modified example of the power converter of the second embodiment. Specifically, Fig. 20 is a cross-sectional view of the power converter taken along a plane perpendicular to the Z-axis direction at the center of the power converter in the Z direction. Fig. 20 shows an enlarged view of the vicinity of the second header 38c.

[0108] The cooler 38 of the second modified example of the second embodiment includes a first header, a first cooling pipe 30b1, a second cooling pipe 30b2, a third cooling pipe 30b3, and a second header 38c.

[0109] In the first modified example of the power converter of the second embodiment, the shape of the rectifying wall is different. The second header 38c has a rectifying wall 38cw. The rectifying wall 38cw has a rectangular cross section. The rectifying wall 38cw is provided inside the second header 38c. The rectifying wall 38cw is provided at a position facing the refrigerant outlet of the second cooling pipe 30b2. The rectifying wall 38cw is provided to extend in the Z direction, and its end in the Z direction is joined to the inner surface of the second header 38c by brazing or the like. The rectifying wall 38cw is provided away from the inner wall on the -X side of the second header 38c.

[0110] The flow straightening wall 38cw directs the flow of refrigerant that has flowed in from the first cooling pipe 30b1 toward the third cooling pipe 30b3 inside the second header 38c. By directing the flow of refrigerant that has flowed in from the first cooling pipe 30b1 toward the third cooling pipe 30b3, the variation in the flow rate of refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 is reduced.

[0111] <Actions and Effects> In the first modified example of the power converter of the second embodiment, by providing the flow straightening wall 38cw in the second header 38c, it is possible to suppress variations in the flow rate of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2.

[0112] In the first modified example of the power converter of the second embodiment, the provision of the flow straightening wall 36cw allows the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly. By allowing the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly, the flow rates of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 can be made uniform.

[0113] <<Third Modification of Second Embodiment>> Fig. 21 is a cross-sectional view of a third modified example of the power converter of the second embodiment. Specifically, Fig. 21 is a cross-sectional view of the power converter taken along a plane perpendicular to the Z-axis direction at the center of the power converter in the Z direction. Fig. 23 shows an enlarged view of the vicinity of the second header 39c.

[0114] In the third modified example of the power converter of the second embodiment, the location of the flow straightening wall is different. The second header 39c has a flow straightening wall 39cw that connects the +X side surface and the -Y side surface. The flow straightening wall 39cw is provided at a position facing the refrigerant outlet of the first cooling pipe 30b1. The flow straightening wall 39cw is provided to extend in the Z direction.

[0115] The flow straightening wall 39cw directs the flow of the refrigerant that has flowed in from the first cooling pipe 30b1 toward the third cooling pipe 30b3 inside the second header 39c. By directing the flow of the refrigerant that has flowed in from the first cooling pipe 30b1 toward the third cooling pipe 30b3, the variation in the flow rate of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 is reduced.

[0116] <Actions and Effects> In the third modified example of the power converter of the second embodiment, by providing the flow straightening wall 39cw in the second header 39c, it is possible to suppress variations in the flow rate of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2.

[0117] In the third modified example of the power converter of the second embodiment, the provision of the flow straightening wall 39cw allows the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly. By allowing the refrigerant flowing from the first cooling pipe 30b1 to the third cooling pipe 30b3 and the refrigerant flowing from the second cooling pipe 30b2 to the third cooling pipe 30b3 to flow smoothly, the flow rates of the refrigerant flowing through the first cooling pipe 30b1 and the second cooling pipe 30b2 can be made uniform.

[0118] <<Third Embodiment>> In the power converter of the third embodiment, the semiconductor package 20 is mounted in consideration of the heat generation state of the semiconductor package 20 and the heat generating surface of the semiconductor package 20.

[0119] Fig. 22 is a cross-sectional view of the power converter of Embodiment 3. Specifically, Fig. 22 is a cross-sectional view of the power converter cut at the center in the Z direction along a plane perpendicular to the Z-axis direction.

[0120] As shown in Fig. 22, the semiconductor package 20 has a higher temperature on one side in the Y direction and a lower temperature on the other side depending on the heat dissipation direction. In Fig. 22, the high-temperature portion is shown as a high-temperature region HS. When multiple semiconductor packages 20 are attached to the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3, they are attached so that the high-temperature region HS is not biased toward any one of the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3.

[0121] 22, the first cooling pipe 30b1 is provided so as to be in contact with the high temperature regions of two semiconductor packages 20. Specifically, the first cooling pipe 30b1 is provided so as to be in contact with the high temperature regions of the semiconductor package 21 (first semiconductor package) and the semiconductor package 23 (third semiconductor package).

[0122] The second cooling pipe 30b2 is provided so as to be in contact with the high temperature regions of the two semiconductor packages 20. Specifically, the second cooling pipe 30b2 is provided so as to be in contact with the high temperature regions of the semiconductor package 22 (second semiconductor package) and the semiconductor package 24 (fourth semiconductor package).

[0123] The third cooling pipe 30b3 is provided so as to be in contact with the high temperature regions of the two semiconductor packages 20. Specifically, the third cooling pipe 30b3 is provided so as to be in contact with the high temperature regions of the semiconductor package 25 (fifth semiconductor package) and the semiconductor package 26 (sixth semiconductor package).

[0124] Note that, for example, the orientation of the semiconductor package 20 may be changed to position the high temperature region HS of the semiconductor package 20 on the upper or lower side. For example, the high temperature region HS of the semiconductor package 20 can be positioned on the upper or lower side of FIG. 22 by turning the semiconductor package 20 upside down. Note that when the semiconductor package 20 is turned upside down, the orientations of the current terminals 20a1, 20a2, and 20a3 and the control terminals 20b1, 20b2, 20b3, and 20b4 may differ from those shown in FIG. 1, for example. When the orientations of the terminals differ from those shown in FIG. 1, the terminals are connected to an external device in accordance with the orientations.

[0125] Furthermore, for example, multiple types of semiconductor packages may be used to position the high temperature region HS on the upper or lower side of the semiconductor package 20. That is, by changing the internal heat transfer structure of the semiconductor package 20, it is possible to provide a semiconductor package in which the upper side of FIG. 22 is the high temperature region HS and a semiconductor package in which the lower side is the high temperature region HS.

[0126] For example, a heat-generating element provided inside semiconductor package 20 may be thermally connected to heat sink 20c1 and thermally isolated from heat sink 20c2, with heat sink 20c1, i.e., the lower side, being the high-temperature region. Alternatively, a heat-generating element provided inside semiconductor package 20 may be thermally isolated from heat sink 20c1 and thermally connected to heat sink 20c2, with heat sink 20c2, i.e., the upper side, being the high-temperature region.

[0127] Therefore, the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are all provided so that the high temperature regions of the two semiconductor packages 20 are in contact with each other. This allows the semiconductor packages 20 to be cooled uniformly.

[0128] The first cooling pipe 30b1 is an example of a first upstream cooling pipe, and the second cooling pipe 30b2 is an example of a second upstream cooling pipe.

[0129] <Actions and Effects> In the power converter of the third embodiment, the semiconductor package 20 can be efficiently cooled by attaching the semiconductor package to a cooler in consideration of the heat generation state of the semiconductor package 20.

[0130] <<Modification of the Third Embodiment>> Fig. 23 is a cross-sectional view of a modified example of the power converter of Embodiment 3. Specifically, Fig. 23 is a cross-sectional view of the power converter cut at the center in the Z direction along a plane perpendicular to the Z-axis direction.

[0131] The cooler 40 of the modified example of the third embodiment includes a first header 40a, a first cooling pipe 30b1, a second cooling pipe 30b2, a third cooling pipe 30b3, and a second header 40c.

[0132] In the modified example of the power converter of the third embodiment, the refrigerant flows from the first header 40a to the second header 40c in the first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3.

[0133] The plurality of semiconductor packages 20 are arranged in the central second cooling pipe 30b2 such that the high temperature regions of two semiconductor packages 20 are in contact with each other on both sides of the upstream side, and the high temperature regions are arranged not to be in contact with each other on both sides of the downstream side.

[0134] Specifically, the first cooling pipe 30b1 is provided so as to be in contact with the high temperature regions of the semiconductor package 22 (second semiconductor package) and the semiconductor package 23 (third semiconductor package).

[0135] The second cooling pipe 30b2 is provided so as to be in contact with the high temperature regions of the semiconductor package 21 (first semiconductor package) and the semiconductor package 24 (fourth semiconductor package).

[0136] The third cooling pipe 30b3 is provided so as to be in contact with the high temperature regions of the semiconductor package 25 (fifth semiconductor package) and the semiconductor package 26 (sixth semiconductor package).

[0137] The first cooling pipe 30b1, the second cooling pipe 30b2, and the third cooling pipe 30b3 are all provided so as to be in contact with the high temperature regions of the two semiconductor packages 20. Therefore, the semiconductor packages 20 can be uniformly cooled.

[0138] In the modified example of the third embodiment, as described above, in order to position the high temperature region HS of the semiconductor package 20 on the upper or lower side, for example, the orientation of the semiconductor package 20 may be changed, or multiple types of semiconductor packages may be used.

[0139] <Actions and Effects> In the modified example of the power converter of the third embodiment, the semiconductor package 20 can be efficiently cooled by attaching the semiconductor package to a cooler in consideration of the heat generation state of the semiconductor package 20. In particular, the semiconductor package 21 (first semiconductor package) and the semiconductor package 24 (fourth semiconductor package) provided on the upstream side (first header 40a side) of the second cooling pipe 30b2 can be efficiently cooled.

[0140] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0141] 1 Power converter 20, 21, 22, 23, 24, 25, 26 Semiconductor パッケージ 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 Coolers 30a, 31a, 32a, 40a 1st ヘッダ 30ap1, 31ap1, 32ap1 refrigerant inlet 30ap2, 31ap2, 32ap2 refrigerant outlet 30aw, 31aw, 32aw next door 30b1, 32b1, 33b1, 34b1 1st cooling pipe 30b2, 33b2, 34b2, 35b2 Second cooling pipe 30b3, 32b3, 33b3, 34b3 3rd cooling pipe 34b4 4th cooling pipe 30bc flow path 30c, 36c, 37c, 38c, 39c, 40c 2nd ヘッダ 36cw, 37cw, 38cw, 39cw rectifier wall HS high temperature field SPin Space SPout Space

Claims

1. a first header having a cavity inside thereof constituting a first internal space, the first header having an inlet and an outlet for a refrigerant, and a partition wall dividing the first internal space into a first space communicating with the inlet and a second space communicating with the outlet; at least one upstream cooling pipe having at least one first flow path therein through which the refrigerant flows, the first flow path communicating with the first space; at least one downstream cooling pipe having at least one second flow path therein through which the refrigerant flows, the second flow path communicating with the second space; a second header having a hollow interior that forms a second internal space, the second header directing the refrigerant introduced from the first flow path into the second internal space from the second internal space to the second flow path, the second header is provided with a flow straightening wall, which is located at a position facing the refrigerant outlet of any of the upstream cooling pipes, and which causes the refrigerant to flow in a direction toward the downstream cooling pipe, between a first wall portion to which the upstream cooling pipe and the downstream cooling pipe are connected and a second wall portion which is provided facing the first wall portion and which forms the second internal space, a sum of cross-sectional areas of the portions of the second flow paths through which the refrigerant flows is smaller than a sum of cross-sectional areas of the portions of the first flow paths through which the refrigerant flows; cooler.

2. A first header having a cavity inside constituting a first internal space, having an inlet and an outlet for a refrigerant, and having a partition wall dividing the first internal space into a first space communicating with the inlet and a second space communicating with the outlet; at least one upstream cooling pipe having at least one first flow path therein through which the refrigerant flows, the first flow path communicating with the first space; at least one downstream cooling pipe having at least one second flow path therein through which the refrigerant flows, the second flow path communicating with the second space; a second header having a hollow interior that forms a second internal space, the second header directing the refrigerant introduced from the first flow path into the second internal space from the second internal space to the second flow path, the second header is provided at a position facing the refrigerant outlet of any of the upstream cooling pipes, and is provided at a second wall portion facing a first wall portion to which the upstream cooling pipe and the downstream cooling pipe are connected, the second wall portion forming the second internal space, the second header including a flow straightening wall provided at an incline so as to cause the refrigerant to flow in a direction toward the downstream cooling pipe, a sum of cross-sectional areas of the portions of the second flow paths through which the refrigerant flows is smaller than a sum of cross-sectional areas of the portions of the first flow paths through which the refrigerant flows; cooler.

3. a sum of cross-sectional areas of the first flow paths through which the refrigerant flows is twice as large as a sum of cross-sectional areas of the second flow paths through which the refrigerant flows; The cooler according to claim 1 or 2.

4. The cooling system includes two upstream cooling pipes and one downstream cooling pipe. The cooler according to any one of claims 1 to 3.

5. A power converter comprising a cooler and at least one semiconductor package, The cooler is a first header having a cavity inside thereof constituting a first internal space, the first header having an inlet and an outlet for a refrigerant, and a partition wall dividing the first internal space into a first space communicating with the inlet and a second space communicating with the outlet; at least one upstream cooling pipe having at least one first flow path therein through which the refrigerant flows, the first flow path communicating with the first space; at least one downstream cooling pipe having at least one second flow path therein through which the refrigerant flows, the second flow path communicating with the second space; a second header having a hollow interior that forms a second internal space, the second header directing the refrigerant introduced from the first flow path into the second internal space from the second internal space to the second flow path, the second header is provided with a flow straightening wall, which is located at a position facing the refrigerant outlet of any of the upstream cooling pipes, and which causes the refrigerant to flow in a direction toward the downstream cooling pipe, between a first wall portion to which the upstream cooling pipe and the downstream cooling pipe are connected and a second wall portion which is provided facing the first wall portion and which forms the second internal space, a sum of cross-sectional areas of the portions of the second flow paths through which the refrigerant flows is smaller than a sum of cross-sectional areas of the portions of the first flow paths through which the refrigerant flows, each of the semiconductor packages is held between any two of the upstream cooling pipe and the downstream cooling pipe; Power converter.

6. A power converter comprising a cooler and at least one semiconductor package, The cooler is a first header having a cavity inside thereof constituting a first internal space, the first header having an inlet and an outlet for a refrigerant, and a partition wall dividing the first internal space into a first space communicating with the inlet and a second space communicating with the outlet; at least one upstream cooling pipe having at least one first flow path therein through which the refrigerant flows, the first flow path communicating with the first space; at least one downstream cooling pipe having at least one second flow path therein through which the refrigerant flows, the second flow path communicating with the second space; a second header having a hollow interior that forms a second internal space, the second header directing the refrigerant introduced from the first flow path into the second internal space from the second internal space to the second flow path, the second header is provided at a position facing the refrigerant outlet of any of the upstream cooling pipes, and is provided at a second wall portion facing a first wall portion to which the upstream cooling pipe and the downstream cooling pipe are connected, the second wall portion forming the second internal space, the second header including a flow straightening wall provided at an incline so as to cause the refrigerant to flow in a direction toward the downstream cooling pipe, a sum of cross-sectional areas of the portions of the second flow paths through which the refrigerant flows is smaller than a sum of cross-sectional areas of the portions of the first flow paths through which the refrigerant flows, each of the semiconductor packages is held between any two of the upstream cooling pipe and the downstream cooling pipe; Power converter.

7. a sum of cross-sectional areas of the first flow paths through which the refrigerant flows is twice as large as a sum of cross-sectional areas of the second flow paths through which the refrigerant flows; 7. The power converter according to claim 5 or 6.

8. The cooling system includes two upstream cooling pipes and one downstream cooling pipe. The power converter according to any one of claims 5 to 7.

9. six semiconductor packages including a first semiconductor package, a second semiconductor package, a third semiconductor package, a fourth semiconductor package, a fifth semiconductor package, and a sixth semiconductor package; the cooler includes two upstream cooling pipes, i.e., a first upstream cooling pipe and a second upstream cooling pipe, and one downstream cooling pipe, which are arranged in order; the first semiconductor package, the second semiconductor package, and the third semiconductor package are held between the first upstream cooling pipe and the second upstream cooling pipe, in this order from the first header side; the fourth semiconductor package, the fifth semiconductor package, and the sixth semiconductor package are held between the second upstream cooling pipe and the one downstream cooling pipe, in this order from the first header side; high-temperature regions of the first semiconductor package and the third semiconductor package contact the first upstream cooling pipe; high-temperature regions of the second semiconductor package and the fourth semiconductor package contact the second upstream cooling pipe; high-temperature regions of the fifth semiconductor package and the sixth semiconductor package contact the one downstream cooling pipe; The power converter according to claim 5 .

Images