Method for connecting the heat sink of a fluid-cooled high-voltage power electronics arrangement

Abstract

Method for connecting a heat sink (22) of a fluid-cooled high-voltage power electronics arrangement (20), wherein the fluid-cooled high-voltage power electronics arrangement (20) comprises: a cooling body (22) through which a cooling fluid flows, which has a cooling plate (23) which is fluidically arranged between a first cooling fluid connection (24) and a second cooling fluid connection (26), which are connected to a cooling fluid inlet (44) and a cooling fluid outlet (46), and at least three power semiconductor modules (31 - 36) which are arranged serially one behind the other on the cooling plate (23) between the first cooling fluid connection (24) and the second cooling fluid connection (26), wherein a power semiconductor module (H) has the highest power loss of all power semiconductor modules (31 - 36), wherein the heat sink (22) is fluidically flow-symmetrically constructed such that the local cooling performance at the cooling plate (23) is identical in the two possible flow directions of the cooling fluid between the first cooling fluid connection (24) and the second cooling fluid connection (26), and the heat sink (22) with its two cooling fluid connections (24, 26) is fluidically connected to a cooling fluid inlet (44) and a cooling fluid outlet (46) in such a way that the power semiconductor module (H) with the highest power loss is arranged no closer to the cooling fluid outlet (46) than to the cooling fluid inlet (44), with the procedural steps: Determining the power semiconductor module (H) with the highest power loss in a test operation, Determine the cooling plate position of the power semiconductor module (H) with the highest power loss, and Connecting the first cooling fluid connection (24) and the second cooling fluid connection (26) to the cooling fluid inlet (44) and to the cooling fluid outlet (46) such that the power semiconductor module (H) with the highest power loss is arranged no closer to the cooling fluid outlet (46) than to the cooling fluid inlet (44).

Description

[0001] The invention relates to a method for fluidically connecting the heat sink of the fluid-cooled high-voltage power electronics arrangement.

[0002] A high-voltage power electronics assembly serves in a high-voltage application with operating voltages above 100 V, for example, as a pulse-controlled inverter or as the power electronics of an electric high-voltage vehicle traction motor. The high-voltage power electronics assembly comprises several power semiconductor modules, each consisting of a large number of power semiconductor elements connected in parallel in order to be able to switch correspondingly high electrical powers. The power semiconductor modules are arranged on a fluid-cooled cooling plate of a heat sink through which a cooling fluid flows. Naturally, the power semiconductor modules mounted further upstream on the cooling plate are cooled better than those arranged downstream on the cooling plate.Such high-voltage power electronics arrangements are known, for example, from DE 11 2008 000 452 B4, JP 2012- 110 093 A, JP 2017- 17 105 A, US 2021 265 239 A1 and JP 2012- 210 095 A.

[0003] Since the switching times of the individual power semiconductor elements differ from one another, power semiconductor modules with a greater spread of the switching times of the respective power semiconductor elements have higher power losses than power semiconductor modules in which the switching times of their power semiconductor elements are closer together. The switching voltage of the individual elements varies, which results in different switch-on times and thus an uneven current distribution during switch-on. This is due to the unavoidable fluctuations in the production of the elements. The distribution of the current among the elements and thus the uneven heating depends on the extent of the deviation of one element from all the other power semiconductor elements connected in parallel. Since the elements in a module are typically connected in parallel, the modules heat up to different degrees.

[0004] From JP 2021-103 932 A, a power electronics system is known in which the power semiconductor modules with high power dissipation are arranged upstream in the cooling path.

[0005] Against this background, the object of the invention is to provide a simple method for connecting the heat sink of a fluid-cooled high-voltage power electronics arrangement with high cooling effectiveness and operational reliability.

[0006] This object is achieved according to the invention with a method for connecting the heat sink of the fluid-cooled high-voltage power electronics arrangement having the features of claim 1.

[0007] The fluid-cooled high-voltage power electronics assembly comprises a heat sink through which a cooling fluid flows, which has a cooling plate arranged fluidically between a first cooling fluid connection and a second cooling fluid connection. The cooling path, which is not necessarily linear, thus extends between the two cooling fluid connections. One cooling fluid connection is connected to a cooling fluid inlet, and the other cooling fluid connection is connected to a cooling fluid outlet. On the cooling fluid-free side of the cooling plate, at least three power semiconductor modules are arranged in series between the two cooling fluid connections. In principle, these can also be three rows, each containing several power semiconductor modules.

[0008] Naturally, a power semiconductor module of all power semiconductor modules has the highest power loss that can be determined in test operation.

[0009] The heat sink through which the cooling fluid flows is fluidically symmetrical in such a way that the local cooling performance at the cooling plate is largely identical in both possible flow directions of the cooling fluid between the first cooling fluid connection and the second cooling fluid connection through the heat sink, so that both orientations of the heat sink with respect to the cooling fluid inlet and the cooling fluid outlet of an active cooling circuit are equivalent from a fluidic point of view or with respect to the local cooling performance.

[0010] The heat sink is fluidically oriented with its two cooling fluid connections to the cooling fluid inlet and the cooling fluid outlet in such a way that the power semiconductor module with the highest power loss is not arranged closer to the cooling fluid outlet than to the cooling fluid inlet.

[0011] This requires that a test has been carried out to determine which power semiconductor module of all power semiconductor modules has the greatest power loss, which is expressed almost exclusively in heat losses. For an even number of rows, each with one or more power semiconductor modules, the power semiconductor module with the greatest power loss is always arranged in the upstream half of the fluid-cooled heat sink or cold plate. For an odd number of rows, each with one or more power semiconductor modules, the power semiconductor module with the greatest power loss is, in the worst case, arranged exactly in the center of the heat sink between the two cooling fluid connections. In any case, the power semiconductor module with the greatest power loss is never located downstream of the center of the heat sink between the two cooling fluid connections.This ensures that the power semiconductor module with the highest power dissipation is not located on the heat sink where the lowest cooling capacity is available. This allows the entire cooling circuit to be dimensioned and adjusted relatively precisely. Furthermore, this fundamentally increases service life and operational reliability.

[0012] According to the method according to the invention for connecting the heat sink of the fluid-cooled high-voltage power electronics arrangement, the following method steps are provided: First, the power semiconductor module with the highest thermal power dissipation is determined in a test run. The test run can be carried out, for example, with power semiconductor modules already mounted on the cooling plate of the heat sink, by measuring all power semiconductor modules for their electrical and thermal power dissipation. Furthermore, the cooling plate position of the power semiconductor module with the highest measured power dissipation is determined and saved.

[0013] Finally, the heat sink, with its first cooling fluid connection and its second cooling fluid connection, is fluidically connected to the cooling fluid inlet and outlet of the cooling circuit in such a way that the power semiconductor module with the highest power dissipation is positioned no closer to the cooling fluid outlet than to the cooling fluid inlet. To enable this configuration, the heat sink must be able to be rotated by 180° if necessary. Since the heat sink is designed to be flow-symmetrical, the heat sink provides the same local cooling performance on the cold plate in both flow directions.

[0014] Preferably, the power semiconductor module with the highest power loss is determined during test operation using a thermal camera aimed at the power semiconductor modules mounted on the cooling plate while they are electrically activated. Particularly preferably, the heat sink is not subjected to cooling fluid flow or is free of cooling fluid during test operation.

[0015] In this way, the power semiconductor module with the greatest heat loss can be determined using simple means.

[0016] Outside the flow space defined by the cooling plate, the heat sink can be constructed asymmetrically, so that there can be a left and a right version of the arrangement.

[0017] The power semiconductor modules preferably form the power electronics of a high-voltage automotive traction motor. Therefore, three or six power semiconductor modules, or a multiple thereof, are preferably arranged on the cooling plate. For example, six rows of two power semiconductor modules each can be arranged on the cooling plate. Since efficiency and reliability are highly important in many aspects of automotive applications, the demand-based fluidic orientation of the heat sink is particularly advantageous for automotive applications.

[0018] An embodiment of the invention is explained in more detail below with reference to the drawings. They show: Fig. 1 schematically shows a fluid-cooled high-voltage power electronics arrangement with a heat sink arranged in a cooling circuit, on whose cooling plate six rows of two power semiconductor modules each are arranged, and Fig. 2 a schematic longitudinal section of the high-voltage power electronics arrangement of the Fig. 1.

[0019] In the Fig. 1 schematically shows a fluid-cooled high-voltage power electronics arrangement 20 with a heat sink 22 through which a liquid cooling fluid flows, which is part of a closed cooling circuit 10. In addition to the heat sink 22 through which the liquid cooling fluid flows, the cooling circuit 10 has a cooling fluid pump 12 and a cooling fluid cooler 14 in which the cooling fluid is cooled. The fluid-tight heat sink 22 is connected by its two cooling fluid connections 24, 26 to a cooling fluid inlet 44 and a cooling fluid outlet 46 of the cooling circuit 10. The liquid cooling fluid flows through the cooling fluid inlet 44 into the first cooling fluid connection of the heat sink 22 and flows through the second cooling fluid connection 26 into the cooling fluid outlet 46 of the cooling circuit 10.

[0020] In the present embodiment, six rows of two identical power semiconductor modules 31-36 are arranged on the metal cooling plate 23, which in the present embodiment lies at the top in a horizontal plane xy and forms an upper wall of the heat sink 22. These modules together form a power semiconductor arrangement 30. The power semiconductor modules 31-36 are connected to the cooling plate 23 with low thermal resistance, for example, thermally connected to the cooling plate 23 via a corresponding heat conducting medium.

[0021] The power semiconductor arrangement 30 forms the power electronics of a three-phase automotive high-voltage traction motor 60. The electrical connections between the power semiconductor modules 31-36 and the traction motor 60 are not shown here for the sake of clarity. The twelve identical power semiconductor modules 31-36 are controlled by an electronic commutation controller 50.

[0022] As in the Fig. 2 is only shown schematically, the heat sink 22 through which the cooling fluid flows is constructed in a flow-symmetrical manner, so that the local cooling performance at the cooling plate 23 is practically identical in both possible flow directions of the cooling fluid between the two cooling fluid connections 24, 26. Although the Fig. 2 is only a schematic representation, but it is intended to clarify that the interior of the heat sink 22, which carries the cooling fluid, is constructed practically mirror-symmetrically with respect to its geometric center line 100y between the two cooling fluid connections 24, 26. The half 22c facing the cooling fluid inlet 44 forms the upstream and cooler part, and the half of the heat sink 22 facing the cooling fluid outlet 46 forms the downstream and warmer part 22w of the heat sink 22.

[0023] Before the heat sink 22 is fluidically connected to the cooling fluid inlet 44 and the cooling fluid outlet 46, the power semiconductor module H with the greatest power loss of all power semiconductor modules 31-36 is determined in a test operation. For this purpose, the heat sink 22 is not fluidically connected to the cooling circuit 10. The commutation control 50 is activated so that the power semiconductor module with the greatest heat emission can be determined using a thermal camera 90, which is the power semiconductor module H with the greatest electrical power loss.

[0024] Subsequently, the heat sink 22 is oriented such that the power semiconductor module H with the greatest power loss is arranged no closer to the cooling fluid outlet 46 than to the cooling fluid inlet 44. In the present exemplary embodiment, the power semiconductor module H with the greatest power loss is arranged even closer to the cooling fluid inlet 44 than to the cooling fluid outlet 46, since in this case there is an even number of (six) rows, each with two power semiconductor modules 31-36.

Claims

[1] Method for connecting a heat sink (22) of a fluid-cooled high-voltage power electronics arrangement (20), wherein the fluid-cooled high-voltage power electronics arrangement (20) comprises: a cooling body (22) through which a cooling fluid flows, which has a cooling plate (23) which is fluidically arranged between a first cooling fluid connection (24) and a second cooling fluid connection (26), which are connected to a cooling fluid inlet (44) and a cooling fluid outlet (46), and at least three power semiconductor modules (31 - 36) which are arranged serially one behind the other on the cooling plate (23) between the first cooling fluid connection (24) and the second cooling fluid connection (26), wherein a power semiconductor module (H) has the highest power loss of all power semiconductor modules (31 - 36), wherein the heat sink (22) is fluidically flow-symmetrically constructed such that the local cooling performance at the cooling plate (23) is identical in the two possible flow directions of the cooling fluid between the first cooling fluid connection (24) and the second cooling fluid connection (26), and the heat sink (22) with its two cooling fluid connections (24, 26) is fluidically connected to a cooling fluid inlet (44) and a cooling fluid outlet (46) in such a way that the power semiconductor module (H) with the highest power loss is arranged no closer to the cooling fluid outlet (46) than to the cooling fluid inlet (44), with the procedural steps: Determining the power semiconductor module (H) with the highest power loss in a test operation, Determine the cooling plate position of the power semiconductor module (H) with the highest power loss, and Connecting the first cooling fluid connection (24) and the second cooling fluid connection (26) to the cooling fluid inlet (44) and to the cooling fluid outlet (46) such that the power semiconductor module (H) with the highest power loss is arranged no closer to the cooling fluid outlet (46) than to the cooling fluid inlet (44). [2] Method according to claim 1, wherein the power semiconductor module (H) with the highest power loss is determined using a thermal camera (90) directed at the power semiconductor modules (31 - 36) mounted on the cooling plate (23). [3] Method according to claim 1 or 2, wherein three or six power semiconductor modules (31 - 36) or a multiple thereof are arranged on the cooling plate (23), wherein the power semiconductor modules (31 - 36) form the power electronics of a motor vehicle high-voltage traction motor (60). [4] Method according to one of the preceding claims, wherein the heat sink (22) is part of a closed cooling circuit (10) with a coolant pump (12) and a coolant cooler (14).

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