Drive inverter with cooler and motor vehicle

Abstract

Cooler (12) for a drive inverter (10) in a motor vehicle for arrangement on at least one power module (14), comprising a carrier (16) with at least one heat-conducting element (18), wherein the heat-conducting element (18) is arranged in a recess (20) of the carrier (16) and wherein the heat-conducting element (18) is fluid-tight and firmly connected to the carrier (16), wherein the heat-conducting element (18) has a base plate (24) which is designed for the arrangement of a power module (14), wherein a material thickness of the carrier (16) is less than a material thickness of the base plate (24). In addition, a drive inverter (10) with such a cooler (12, 12a) and a motor vehicle with such a drive inverter (10) are explained.

Description

[0001] The invention relates to a drive inverter with a cooler and a motor vehicle.

[0002] Inverters, also known as drive inverters, are used to operate electric vehicles, especially battery-powered ones. These convert direct current into alternating current to drive one or more electric motors. The inverter's power modules generate large amounts of heat during operation, which must be dissipated. Active liquid cooling systems are well known in the art. In particular, two-sided cooling enables effective heat dissipation and high power density. To ensure good thermal integration, sintered and soldered joints are used between the cooler and the power module, although these require high tolerances.Accordingly, in the prior art, such thermally highly conductive connections are formed only on one side of the power module, with thermal pads or thermal pastes being formed on the other side, the thermal conductivity of which is lower but can compensate for larger tolerances.

[0003] Various drive inverters with power modules cooled on one side are known from US 5 369 879 A, ​​which proposes an axial preload of a power module on a cooler to improve the heat transfer with thermal pads, as well as from DE 11 2016 005 528 T5, which describes several modularly designed and mutually attached liquid coolers for one-sided cooling of power modules in a compact structure.

[0004] Accordingly, the task is to provide a drive inverter with a cooler and an inverter that is connected to the power modules with high thermal conductivity and also enables improved tolerance compensation.

[0005] This object is achieved by a drive inverter with a cooler according to claim 1. Advantageous embodiments of the drive inverter with a cooler are described in the following claims. The drive inverter according to claim 1 is suitable for a motor vehicle and comprises several power modules and a cooler, wherein each power module is firmly connected to an associated heat-conducting element with high thermal conductivity, wherein the cooler has - a carrier and several heat conducting elements, - wherein the heat-conducting elements are arranged in a recess of the carrier and - the heat-conducting elements are fluid-tight and firmly connected to the carrier, - wherein the heat-conducting element has a base plate which is designed to accommodate the power module, - where the material thickness of the support is less than the material thickness of the base plate, - wherein the power module (14) is designed for two-sided cooling, wherein a further cooler (12a) is designed opposite the cooler (12).

[0006] A connection with high thermal conductivity is created, for example, by a sintered connection or a soldered connection. In contrast, lower thermal conductivity is provided, for example, by thermal pads or thermal pastes.

[0007] The cooler serves to dissipate heat generated in the power modules. Specifically, the cooler is designed as a liquid cooler, which absorbs the heat from the power module and transfers it to a cooling fluid. The cooler defines a cooling channel partially (also called an open cooler), or completely (also called a closed cooler). An open cooler is connected to one or more other components, such as a housing, in a liquid-tight manner, so that together with this or these other components, a cooling channel is formed. The cooling channel has an inlet and an outlet, and a cooling fluid flows through it.

[0008] A drive inverter is used to drive an electrically powered, particularly battery-powered, motor vehicle. Advantageously, it is designed to control the current flow between the battery and the electric motor. The inverter advantageously converts between direct current and single-phase or multi-phase alternating current, preferably three-phase alternating current.

[0009] A motor vehicle is, for example, a passenger car, car, or a truck, truck.

[0010] The carrier provides a kind of housing for the cooler. In particular, the carrier serves to define the cooling channel. The carrier advantageously elastically absorbs the forces acting on the cooler, for example, the pressure exerted by the coolant during operation. The heat-conducting elements serve to arrange and secure the power modules. Independently of this, the heat-conducting elements provide a highly thermally conductive connection to the corresponding power module. Likewise, the heat-conducting element serves to dissipate heat from the heat source and transfer this heat to a coolant.

[0011] The recesses accommodate the heat-conducting elements. The connection between the carrier and the heat-conducting element is advantageously designed to be liquid-tight. The recesses are formed, for example, by holes. The heat-conducting element and the carrier are fastened, for example, by a welded connection, soldered connection, and / or adhesive connection. The fixed connection between the heat-conducting element and the carrier can be made, for example, in an overlap area or a joint area. The former, in particular, places lower tolerance requirements and also enables simpler and more flexible positioning of the heat-conducting element.

[0012] The base plate of the thermal element provides a stable base body that can absorb the acting forces. Furthermore, the base plate provides a surface for the highly thermally conductive connection of a power module. Furthermore, the base plate, which acts as a base body, enables the formation of one or more cooling structures. These cooling structures are formed, for example, by pin fins.

[0013] The thinner material thickness of the support compared to the material thickness of the base plate offers many advantages. On the one hand, the thinner material thickness of the support reduces the mass of the cooler. The thinner material thickness of the support also allows for greater elasticity, which ensures tolerance compensation. The thicker material thickness of the base plate ensures stable mounting of the power module. In particular, this design allows for tolerance compensation. For example, the position of a heat-conducting element is determined by the position and tolerance of a power module within the cooler.Due to tolerances such as different height positions or tilting of the power module connection surfaces, multiple power modules require appropriate compensation through a corresponding arrangement of the heat-conducting elements. This corresponding arrangement and the compensation of the tolerances are provided by the elasticity of the carrier. This allows highly thermally conductive connections between the heat-conducting element and the power module, such as soldered or sintered connections, to be used even if the existing tolerances are larger than the tolerance that can be compensated for by the connection type. Such highly thermally conductive connections can usually only compensate for very small tolerances, although in the described design, these are compensated for by the carrier. Such a cooler enables the compensation of tolerances.

[0014] The material thickness of the support is advantageously substantially uniform across the entire support. Advantageously, several heat-conducting elements are formed on the cooler. The number of recesses and the number of heat-conducting elements are preferably identical.

[0015] In addition, the power module is designed for two-sided cooling, with another cooler being designed opposite the cooler.

[0016] Advantageous design variants of such a cooler are explained below.

[0017] Advantageously, the material thickness of the support corresponds to a maximum of 50% of the material thickness of the base plate, preferably a maximum of 30%.

[0018] This provides, on the one hand, sufficient stability through the heat-conducting element and, on the other hand, optimal elasticity of the carrier.

[0019] Advantageously, the carrier has a material thickness of approximately 1 mm or a material thickness between 0.7 mm - 1.5 mm or a material thickness between 0.6 mm - 1.2 mm.

[0020] These material thicknesses are particularly advantageous for a lightweight cooler. Furthermore, these material thicknesses provide the support with high elasticity, allowing for comparatively large tolerance compensation.

[0021] The base plate preferably has a material thickness between 2 mm - 4 mm.

[0022] This material thickness has proven to be particularly advantageous in terms of stability and heat transfer from the power module to the coolant.

[0023] The carrier is preferably made of copper, aluminum or steel.

[0024] These materials enable easy manufacturing, good bondability, high elasticity and low weight.

[0025] The heat conducting element is advantageously made of copper.

[0026] This ensures good heat transfer between the power module and the coolant.

[0027] Advantageously, the carrier and the heat-conducting element are fastened to each other by a welded joint, a soldered joint or an adhesive joint.

[0028] Such a connection is preferably designed to be liquid-tight. Such a connection is preferably formed in an overlap area between the carrier and the heat-conducting element. Such an overlap area is preferably circular and self-contained.

[0029] Advantageously, the carrier is open or the carrier is closed.

[0030] An open cooler is connected to one or more other components, for example a housing, and arranged in a liquid-tight manner, so that together with this or these other components a cooling channel is formed.

[0031] It is advantageous to arrange a cooler on both sides of a power module. It is particularly advantageous to have highly thermally conductive connections, such as sintered or soldered joints, on both sides of the power module. This allows the heat generated in the power module to be dissipated particularly quickly. This allows a correspondingly high power density to be achieved within the power module.

[0032] Advantageous design variants of the drive inverter are explained below.

[0033] It is advantageous to have a cooler on one or both sides of the power module.

[0034] This provides better heat dissipation of the power module.

[0035] Advantageously, the additional cooler is firmly connected to the power module via a high-thermal-conductivity connection. In particular, the cooler provides tolerance compensation through elastic deformation of the support, so that a high-thermal-conductivity connection can be formed on both sides. Particularly advantageously, both or all of the connection points between a power module and the associated coolers are formed by high-thermal-conductivity connections, soldered connections, or sintered connections.

[0036] Advantageously, one cooler or both coolers are formed by a cooler according to at least one of the embodiments of claims 1 to 7 or one of the embodiments of the description.

[0037] Both connections between the power module and the two coolers are advantageously formed by solder joints. Both connections between the power module and the two coolers are advantageously formed by sintered joints.

[0038] The cooler supports compensate for tolerances through elastic deformation.

[0039] The above-mentioned object is also achieved by a motor vehicle according to claim 8.

[0040] A motor vehicle with such an inverter is capable of providing high performance due to the effective cooling of the power modules by one or two coolers.

[0041] The cooler, the inverter, and the motor vehicle are explained in detail below using several examples. They show: Fig. 1 an inverter with several power modules and a cooler in a side view; Fig. 2 an inverter with at least one power module and a cooler in cross section; Fig. 3 a top view of the cooler Fig. 1 and / or 2; Fig. 4 an inverter with coolers arranged on both sides in a side view; Fig. 5 an inverter with at least one power module with coolers arranged on both sides in cross section;

[0042] In the Fig. 1 shows an inverter 10 in a schematic side view in cross section. Such an inverter is designed to drive an electric motor vehicle, in particular a battery-powered motor vehicle. The inverter 10 is arranged between an electric motor and a battery. The inverter 10 enables the extraction of energy from the battery to drive the electric motor and / or the supply of energy from the electric motor to the battery. In particular, the inverter is designed to convert a provided direct current into a single-phase or multi-phase alternating current, preferably three-phase.

[0043] The inverter 10 comprises a cooler 12 on which several power modules 14 are arranged. A power module 14 has one or more power semiconductors that control the current flow for operating the electric motor. The energy generated in the power module 14 by the power semiconductors is delivered to the cooler 12.

[0044] The cooler 12 has a carrier 16 and a plurality of heat-conducting elements 18. The heat-conducting elements 18 are accommodated within recesses 20 on the carrier 16. The heat-conducting elements 18 are firmly connected to the carrier 16.

[0045] Here, a recess 20 is formed smaller than a corresponding dimension of the heat-conducting element 18, so that the carrier 16 and the heat-conducting element 18 overlap. The recess 20 and the corresponding dimension of the heat-conducting element 18 are rectangular in this embodiment. The heat-conducting element 18 is firmly connected to the carrier 16 within the overlap region 22. The overlap region 22 is shown, for example, in Fig. 3. The connection is preferably fluid-tight. For example, the connection is formed by a welded connection, a soldered connection, and / or an adhesive connection. In principle, the fixed connection between carrier 16 and heat-conducting element 18 can also be formed in other ways. A configuration with an overlap region 22 is chosen merely as an example; alternatively, a connection can be formed at a joint between heat-conducting element 18 and carrier 16, for example.

[0046] The heat-conducting element 18 has a base plate 24 and cooling structures 26. The base plate 24 serves for thermal contact with the power module 14. The power module is firmly connected to the heat-conducting element 18, for example, via a soldered connection or a sintered connection. In the figures, this is illustrated by a sintered layer 28. The cooling structures 26 protrude into a cooling channel 30 of the cooler 12 and are surrounded by a cooling liquid, for example, water or a glycol-water mixture. The heat generated in the power module 14 is transferred via the sintered layer 28 to the base plate 24 of the heat-conducting element 18 and then conducted into the cooling structures 26. The cooling structures 26 transfer the heat to the cooling liquid. For example, the cooling structures 26 are formed by pin fins. The cooling channel 30 has an inlet and an outlet. Fig. 1, the inlet is designed, for example, on the left and the outlet on the right, so that the cooling fluid flows through the cooling channel 30 from left to right. The cooling channel 30 is at least partially delimited by the radiator 12.

[0047] In the version according to Fig. In Figure 1, the cooler 12 is shown open, but can also be designed as a closed unit. In this case, the cooler is inserted into another component, such as a housing of the inverter, which is connected to the cooler in a fluid-tight manner, thus providing a closed cooling channel 30. In a further embodiment according to Fig. 2, the cooling channel 30 is defined in a fluid-tight manner by the carrier 16. In this case, the carrier 16 comprises, for example, an upper part 16a and a lower part 16b, which are fluid-tightly and firmly connected to one another.

[0048] Due to the schematic representation of the Fig. 2, this can be viewed both as a separate version with a single power module and as a cross-sectional view through Fig. 1. In the latter case, the cooler 12 is Fig. 1 closed design.

[0049] The heat-conducting element 18 is comparatively solid compared to the carrier 16. In particular, the base plate 18 has a greater material thickness than the carrier 16. The carrier 16 is designed, for example, as a sheet metal part. The carrier 16 preferably has a low material thickness, which allows material and weight to be saved. The material thickness of the sheet metal is preferably approximately 1 mm, in particular the sheet metal has a material thickness between 0.7 mm - 1.5 mm, particularly advantageously between 0.6 - 1.2 mm. Such a wall thickness is significantly thinner than in known coolers from the prior art. Such a low material thickness enables easier production. The base plate 18 of the heat-conducting element 18 preferably has a material thickness between 2 - 4 mm. As a result, it is sufficiently stable to accommodate the cooling structures 26.Since the base plate 18 of a heat-conducting element 18 has a surface area corresponding to the associated power module 14, the increased material thickness is minimized to the necessary level. The heat-conducting element 18 is preferably made of copper. The carrier 18 is preferably made of copper or, alternatively, of aluminum or steel.

[0050] If the inverter 10 is equipped with two-sided cooling on the power modules 14, as shown in Fig. 4 and Fig. 5, the cooler 12 has particular advantages. Fig. 4 the coolers 12 are open and in Fig. 5 is shown closed to illustrate the different design variants. Fig. 5, however, represents in particular a cross-section of the Fig. 4.

[0051] With two-sided cooling, a cooler 12 is attached to the power module 14 on both the top and bottom. However, all components have different tolerances. Adjacent power modules 14 can therefore have slightly different thicknesses, and the coolers 12 also have tolerances at the connection areas with the power modules 14. However, the carrier 16 of the cooler 12 has an elasticity that compensates for such tolerances. Accordingly, the connection between the power module and the two coolers can be formed on both sides by a soldered connection or on both sides by a sintered connection. Compared to the prior art, in which a thermal pad or thermal paste for thermal connection is formed on at least one side to compensate for tolerances, a significantly higher thermal conductivity is provided.In addition, manufacturing is simplified due to the ability to better compensate for tolerances. For example, different thicknesses of the power modules, inconsistencies in the parallelism of the opposing contact surfaces of the power modules, and even tilting of the power modules relative to each other can be compensated.

[0052] In principle, in the case of two-sided cooling, only one of the two coolers can be designed as a cooler according to the invention, with the other being designed as a classic cooler. List of reference symbols 10 drive inverters 12, a cooler 14 Power module 16 carriers 16a upper part 16b Lower part 18 Heat conducting element 20 recess 22 Overlap area 24 Base plate 26 Cooling structure 28 sintered layer 30 cooling channel

Claims

[1] Drive inverter (10) for a motor vehicle comprising a plurality of power modules (14) and a cooler (12), wherein a respective power module (14) is firmly connected with a high thermal conductivity to an associated heat-conducting element (18), wherein the cooler (12) has - a carrier (16) and several heat-conducting elements (18), - wherein the heat-conducting elements (18) are arranged within recesses (20) of the carrier (16) and - wherein the heat-conducting elements (18) are fluid-tight and firmly connected to the carrier (16), - wherein the heat-conducting element (18) has a base plate (24) which is designed to accommodate the power module (14), - wherein a material thickness of the carrier (16) is less than a material thickness of the base plate (24), - wherein the power module (14) is designed for two-sided cooling, wherein a further cooler (12a) is designed opposite the cooler (12). [2] Drive inverter (10) according to the preceding claim, characterized by that the material thickness of the support (16) corresponds to a maximum of 50% of the material thickness of the base plate (24), preferably a maximum of 30%. [3] Drive inverter (10) according to one of the preceding claims, characterized by that the carrier (16) has a material thickness of approximately 1 mm or a material thickness between 0.7 mm - 1.5 mm or a material thickness between 0.6 mm - 1.2 mm. [4] Drive inverter (10) according to one of the preceding claims, characterized by that the base plate (24) has a material thickness between 2 mm - 4 mm. [5] Drive inverter (10) according to one of the preceding claims, characterized by that the carrier (16) is made of copper, aluminum or steel. [6] Drive inverter (10) according to one of the preceding claims, characterized by that the heat-conducting element (18) is made of copper. [7] Drive inverter (10) according to one of the preceding claims, characterized by that the carrier (16) is open or that the carrier (16) is closed. [8] Motor vehicle comprising a drive inverter (10) according to one of claims 1 to 7.

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