COOLER FOR COOLING POWER ELECTRONICS

Description

State of the art

[0001] The present invention relates to a cooler for cooling power electronics. Furthermore, the invention shows an assembly comprising the cooler and the power electronics.

[0002] Power semiconductors in power electronics carry high electrical currents. Combined with switching losses, the resulting conduction losses cause high heat losses, which must be dissipated within a relatively small area. The maximum permissible semiconductor temperature is critical to failure, which is why minimizing the thermal resistance between the semiconductor and the coolant is of key importance. For efficient cooling, the power electronics considered here are applied to fluid-flow coolers. These coolers typically contain cooling fin arrangements through which the fluid flows.

[0003] Known coolers for power electronics are disclosed in WO 2019 / 210413 A1, WO 2019 / 189477 A1, US 2015 / 189791 A1, and JP 2010 203694 A. Disclosure of the invention

[0004] The cooler according to the invention enables quick and easy production, wherein in particular the cooling fin arrangement can be manufactured quickly and inserted without errors due to its one-piece design. Furthermore, the cooler according to the invention enables very efficient cooling of the power electronics. The cooler according to the invention is designed in particular for cooling power electronics. This power electronics has one or more power semiconductors, which are usually arranged in a substrate. The cooler comprises a housing designed for mounting the power electronics. Preferably, the housing is plate-shaped, for example with two cooling plates, which define a cooling channel between them through which cooling fluid can flow. The cooling channel forms a cavity. In this cavity there is a cooling fin arrangement with a plurality of cooling fins.The cooling fin arrangement is, in particular, an insert that is placed between the two cooling plates. The cooling channel and the cooling fin arrangement are designed to conduct the cooling fluid. Cooling is, in particular, carried out with a fluid in the liquid state.

[0005] The cooling fin arrangement is designed so that the fluid can flow through it along a longitudinal axis. A transverse axis is defined perpendicular to the longitudinal axis and thus also perpendicular to the flow direction. A vertical axis is defined perpendicular to the transverse axis and perpendicular to the longitudinal axis.

[0006] In particular, the cooling fin arrangement extends significantly further along the longitudinal axis and the transverse axis than along the vertical axis. The power electronics are positioned above or below the cooling fin arrangement along the vertical axis. Several heat sources of the power electronics, in particular several of the power semiconductors, can be positioned along the longitudinal axis and partly also along the transverse axis. The cooling fin arrangement has several cooling fin sections.

[0007] In particular, there are two to ten different cooling fin sections. Each two adjacent cooling fin sections have different fin geometries. As will be explained in more detail, the cooling fin arrangement can include an intermediate section between two cooling fin sections. The intermediate section can also have cooling fins. The entire cooling fin arrangement is a single component that is inserted. Accordingly, all cooling fin sections of the cooling fin arrangement are firmly connected to one another. Adjacent cooling fin sections can be firmly connected to one another directly or via the aforementioned intermediate sections.

[0008] Preferably, the cooler described here has only one cooling fin arrangement. However, it is also possible to insert additional cooling fin arrangements in addition to the cooling fin arrangement described here with the multiple cooling fin sections.

[0009] The fixed connection of all cooling fin sections of the cooling fin arrangement has the advantage that only one component needs to be inserted. Furthermore, the fixed connection of the cooling fin sections to one another also determines the distance between the cooling fin sections, for example through the intermediate sections, and this distance can no longer be incorrectly changed during assembly. The individual cooling fin sections can no longer be swapped or rotated during assembly because their mutual alignment is determined by the fixed connection. The material used for the cooling fin arrangement is preferably aluminum or another material with correspondingly high thermal conductivity or a corresponding coating. Furthermore, it is provided that the fins are set at an angle to the longitudinal axis and that the angle of incidence differs in at least two adjacent cooling fin sections.The angle of incidence increases from one cooling fin section to the next along the flow direction. Each cooling fin section preferably has several rows of fins arranged one behind the other. The rows of fins extend, as described in the context of the turbulence plate, along the transverse axis and lie directly adjacent to one another along the longitudinal axis. The fins in adjacent rows of fins are preferably angled at different angles relative to the longitudinal axis, so that, for example, the fins in one row are angled at 10° and the fins in the next row at -10° relative to the longitudinal axis. By alternating the fins, the flow resistance is deliberately increased in order to achieve the highest possible heat transfer coefficient.

[0010] The subclaims show preferred developments of the invention.

[0011] In principle, it is possible to firmly connect the individual cooling fin sections or even the intermediate sections after their manufacture. However, it is particularly preferred that the cooling fin arrangement be manufactured from a single part. In particular, the cooling fin arrangement is manufactured by forming a sheet metal into a turbulence plate. In this process, all the cooling fin sections and, if applicable, the intermediate sections of the cooling fin arrangement are created from the single sheet metal, so that after the sheet metal has been formed, a cooling fin arrangement is produced that is manufactured from a single part, namely the single sheet metal, and in which all the cooling fin sections are firmly connected to one another, either directly or via the intermediate sections.

[0012] The turbulence plate, in particular, has a plurality of rows of ribs. Each row of ribs extends perpendicular to the longitudinal axis along the transverse axis. Each row of ribs has a plurality of ribs. In particular, the row of ribs has a wave shape. This wave shape connects two adjacent ribs to each other via a peak or valley section of the wave shape. The peak or valley section of the wave shape or the row of ribs, in particular, extends essentially in a plane spanned by the longitudinal axis and the transverse axis.

[0013] The intermediate sections preferably extend substantially shorter in the longitudinal direction than the cooling fin sections. The individual intermediate section can preferably be formed by a row of fins. It is preferably provided that in at least one cooling fin section, the fins have a first length, measured parallel to the longitudinal axis, and the adjacent intermediate section has a second length, also measured parallel to the longitudinal axis. The second length is greater than the first length; the entire intermediate section is thus longer than a single fin of the adjacent cooling fin section.

[0014] For the production of the cooling fin arrangement, particularly by forming a sheet metal into a turbulence plate, the geometry of the individual cooling fin sections is preferably taken into account. It is advantageous if the cooling fin arrangement has a constant material thickness and / or a constant fin height and / or a constant period length across all cooling fin sections and intermediate sections. The material thickness is determined by the thickness of the processed sheet metal. The fin height is measured along the vertical axis. The period length is measured along the transverse axis within a row of fins.

[0015] When designing the cooler, it was taken into account that the coolant is heated in the direction of flow by the heat loss from the power semiconductors. As a result, the power semiconductor located at the rear in terms of flow direction is cooled less effectively than the one at the front, leading to different service lives and, above all, different electrical behavior. Therefore, the various cooling fin sections are preferably arranged one behind the other along the longitudinal direction and thus along the flow direction, so that the geometries of the fins change along the flow direction. This allows the heat transfer coefficient between the fins and the coolant to be adjusted.

[0016] There are various ways to increase the flow resistance from one fin section to the next, thereby also increasing the heat transfer coefficient: In addition to increasing the angle of incidence from one fin section to the next, the flow resistance can also be increased by reducing the length of the individual fin, measured along the longitudinal axis. This is particularly interesting in combination with the alternating angle of incidence of the individual fin rows described above, since with this alternating angle of incidence and correspondingly short fins (measured parallel to the longitudinal axis), the flow resistance is correspondingly high.

[0017] The invention further comprises an arrangement. This arrangement, in turn, combines the described cooler and the associated power electronics with at least one power semiconductor. As described, the power electronics are arranged on the cooler. Short description of the drawing

[0018] An embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing: Figure 1 shows a schematic sectional view of an arrangement according to the invention with a cooler according to the invention according to an embodiment, Figure 2 shows a schematic plan view of the cooler according to the invention according to the embodiment, Figure 3 shows a plan view of a cooling fin arrangement of the cooler according to the invention according to the embodiment, Figure 4 shows a partial view of the cooling fin arrangement from Figure 3 and Figure 5 shows a multi-part design of a cooling fin arrangement. Embodiment of the invention

[0019] In the following, an arrangement 100 with a cooler 1 is described using the Figures 1 to 4 described in detail. The arrangement 100 comprises, according to the schematic sectional view in Figure 1 a power electronics unit 101 located on the cooler 1. The power electronics unit 101 includes one or more power semiconductors 102, which are considered here as primary heat sources.

[0020] According to the Figures 1 to 4 A longitudinal axis 30, a transverse axis 31, and a vertical axis 32 are defined on the cooler 1. The three axes 30, 31, and 32 are perpendicular to each other.

[0021] Furthermore, Figure 1that the cooler 1 is plate-shaped, with two interconnected and parallel arranged cooling plates 3, 5, which together form a housing 2 of the cooler 1. Between the cooling plates 3, 4 there is a cooling channel 6. The two cooling plates 3, 4 are connected to each other via a solder layer 5.

[0022] In the cooling channel 6 there is a cooling fin arrangement 7 as an insert, which can also be connected to the housing 2 via the solder layer.

[0023] Figure 2 shows a top view of the cooler 1. The upper cooling plate 3 is hidden for the sake of clarity, so that the lower cooling plate 4 with the cooling fin arrangement 7 accommodated therein can be seen.

[0024] The housing 2 is designed to conduct a cooling fluid along a flow direction 34. The flow direction 34, which extends parallel to the longitudinal axis 30, is the main flow direction from the housing-side inlet to the housing-side outlet of the fluid. Within the cooling fin arrangement 7, the fluid can also flow with a directional component parallel to the transverse axis 31.

[0025] Figure 3 shows the cooling fin arrangement 7, which is composed of a first cooling fin section 71, a second cooling fin section 72, and a third cooling fin section 73 along the longitudinal axis 30 or along the flow direction 34. Adjacent cooling fin sections 71 to 73 are firmly connected to one another via an intermediate section 74. The two intermediate sections 74 are also part of the cooling fin arrangement 7.

[0026] The entire cooling fin arrangement 7 with all three cooling fin sections 71 to 73 and the two intermediate sections 74 is made of a sheet metal that is formed into a turbulence plate. Figure 5 a multi-part design of the cooling fin arrangement 7. How Figure 5 As shown, in this configuration, the individual turbulence plates must be inserted into the cooling plate 3 with a gap 50 between them. Care must be taken to ensure that the individual turbulence plates are not interchanged or twisted. Furthermore, the gap 50 must be maintained.

[0027] In the illustrated embodiment according to the Figures 1 to 4 The cooling fin arrangement 7 is composed of a plurality of rows of fins 8. Each row of fins 8 extends along the transverse axis 31. The plurality of rows of fins 8 are arranged one behind the other along the longitudinal axis 30, directly adjacent to one another. Figure 4shows a detailed view of three of these rib rows 8. Each individual rib row 8 is wave-shaped, with two adjacent ribs 9 connected by a peak or valley section 10 of the waveform. Parallel to the transverse axis 31, a distance 11 results between two adjacent ribs 9. A period length 16 is measured in the same direction.

[0028] The individual fin 9 extends parallel to the longitudinal axis 30 over a first length 12. A height 15 of the fins 9 or the rows of fins 8 is defined along the vertical axis 32. This height 15 also corresponds to the total height of the cooling fin arrangement 7. The sheet metal used results in a material thickness of 17.

[0029] Figure 3shows a detailed view of the three cooling fin sections 71, 72, and 73. An angle of attack 14 of each individual fin 9 relative to the longitudinal axis 30 is shown. The direction of the angle of attack 14 changes from one row of fins 8 to the next adjacent row of fins 8 within a cooling fin section 71, 72, 73.

[0030] In order to increase the flow resistance along the flow direction 34, it is provided that the angle of attack 14 increases from the first cooling fin section 71 to the second cooling fin section 72 and from the second cooling fin section 72 to the third cooling fin section 73.

[0031] Additionally or alternatively, it is also provided that the first length 12, which describes the extension of the fins 9 parallel to the longitudinal axis 30, decreases from the first cooling fin section 71 to the second cooling fin section 72 and from the second cooling fin section 72 to the third cooling fin section 73.

[0032] The individual cooling fin sections 71, 72, 73 extend along the longitudinal axis 30 preferably substantially longer than the two intermediate sections 74. The respective intermediate section 74 is preferably formed by only one row of fins 8. A second length 13, which describes the extension of the intermediate section 74 along the longitudinal axis 30, is preferably longer than the first length 12 in the adjacent cooling fin sections 71, 72, 73.

[0033] To change the flow resistance from one cooling fin section to the next, in addition to the angle of attack 14 and the first length 12, other geometries of the fins 9, for example, the spacing 11 or the height 15, can also be changed. However, for manufacturing reasons during the production of the turbulence plate by forming, it is preferably provided that the period length 16 and thus the spacing 11, the height 15, and the material thickness 17 are kept constant across the entire cooling fin arrangement 7, which is manufactured from a single part.

Claims

1. Cooler (1) for cooling power electronics (101), comprising • a housing (2) for attaching the power electronics (101) • and a cooling fin arrangement (7) having a multiplicity of fins (9) in a cooling channel (6) of the housing (2), • wherein the cooling fin arrangement (7) is able to be flowed through by a fluid along a longitudinal axis (30), • wherein the cooling fin arrangement (7) has a plurality of cooling fin sections (71, 72, 73), wherein adjacent cooling fin sections have different geometries of the fins (9) and wherein the cooling fin sections (71, 72, 72) are fixedly connected to one another, characterized in that the fins (9) are set at an angle of incidence (14) with respect to the longitudinal axis (30) and the angle of incidence (14) differs in at least two adjacent cooling fin sections (71, 72, 73), wherein the angle of incidence (14) increases along the flow direction from one cooling fin section (71, 72, 73) to the next cooling fin section (71, 72, 73).

2. Cooler according to Claim 1, wherein the cooling fin arrangement (7) is produced from one part.

3. Cooler according to Claim 2, wherein the cooling fin arrangement (7) is produced by shaping a metal sheet to form a turbulence sheet.

4. Cooler according to one of the preceding claims, wherein in each case two adjacent cooling fin sections (71, 72, 73) are fixedly connected to one another by means of an intermediate section (74) of the cooling fin arrangement (7).

5. Cooler according to Claim 4, wherein in at least one cooling fin section (71, 72, 73) the fins (9) have a first length (12), measured parallel to the longitudinal axis (30), and the adjacent intermediate section (74) has a second length (13), measured parallel to the longitudinal axis (30), wherein the second length (13) is greater than the first length (12).

6. Cooler according to one of the preceding claims, wherein the cooling fin arrangement (7) has a constant material thickness (17) and / or a constant fin height (15) and / or a constant period length (16).

7. Cooler according to one of the preceding claims, wherein the fins (9) have a first length (12) parallel to the longitudinal axis (30) and the first length (12) decreases from one cooling fin section (71, 72, 73) to the next cooling fin section (71, 72, 73).

8. Arrangement (100) comprising a cooler (1) according to one of the preceding claims and power electronics (101) having a plurality of power semiconductors (102) which are arranged on the housing (2).