Power electronics module for a vehicle power converter and vehicle power converter

Abstract

A power electronics module (10) for a power converter (11) of a vehicle has a power electronic component (12) mounted on a thermally conductive carrier (14). The thermally conductive carrier (14) is arranged on a heat sink (16) for cooling the power electronic component (12), so that a primary heat dissipation path is formed that extends from the power electronic component (12) via the thermally conductive carrier (14) to the heat sink (16). Furthermore, a thermal storage assembly (30) is mounted on the power electronic component (12), comprising a thermal storage element (32) and a connecting layer (34) that is thermally conductive and electrically insulating and connects the power electronic component (12) to the thermal storage element (32).

Description

[0001] The invention relates to a power electronics module for a vehicle power converter and a vehicle power converter.

[0002] In vehicles that are at least partially electrically powered, such as electric and hybrid vehicles, power converters with one or more power electronic components, like power semiconductor switches, are used. During operation, these power electronic components generate waste heat, which can cause them to heat up beyond a permissible upper temperature limit, at which point damage to the components is likely.

[0003] For this reason, heat sinks are used in conventional power electronics modules. These heat sinks are thermally connected to the power electronic components via a heat dissipation path and dissipate the heat generated during operation. The maximum heat that can be dissipated by the heat sink per unit of time is limited by factors such as the materials forming the heat dissipation path and the available installation space. Consequently, the power electronic components can only be operated at a fixed maximum current for a limited time, and / or the maximum current at which the power electronic components operate must be reduced. This is disadvantageous in application scenarios where short-term load spikes and associated temperature peaks are expected, such as during a vehicle acceleration process lasting several seconds.

[0004] German patent DE 10 2021 106 008 B3 describes a power electronics module for a vehicle's power converter, in which a power electronic component is arranged in a hermetically sealed housing filled with a dielectric working fluid that absorbs waste heat from the power electronic component by evaporating. The evaporated working fluid is then condensed back into a liquid in a condenser, releasing heat in the process. However, such a design is associated with considerable costs and complexity and requires a large amount of installation space. Furthermore, there is a risk of the working fluid leaking out if the housing is damaged.

[0005] The object of the invention is to provide a power electronics module for a vehicle power converter and a vehicle power converter that provides efficient cooling even when temperature peaks occur and is particularly cost-effective and space-optimized.

[0006] The problem is solved by a power electronics module for a vehicle's power converter, wherein the power electronics module comprises a power electronic component mounted on a thermally conductive substrate, the thermally conductive substrate being arranged on a heat sink for cooling the power electronic component, such that a primary heat dissipation path is formed extending from the power electronic component via the thermally conductive substrate to the heat sink. Furthermore, a thermal storage assembly is attached to the power electronic component, comprising a thermal storage element and a thermally conductive and electrically insulating interconnect layer that connects the power electronic component to the thermal storage element.

[0007] The invention is based on the fundamental idea of ​​providing, in addition to the primary heat dissipation path, a further means by which heat can be dissipated from the power electronic component and stored, at least temporarily, when load or temperature peaks occur. In this way, the temperature increase to which the power electronic component is exposed during the load or temperature peak is limited, so that the power electronic component can be operated for a longer period at the same maximum current, or the maximum current can be increased at the same load duration, without having to fear that the power electronic component will heat up beyond a permissible upper temperature limit.

[0008] According to the invention, a thermal storage element is provided for this purpose, which absorbs the generated heat. Thus, during peak loads or temperature periods, the amount of heat transferred to the thermal storage element does not have to be routed via the primary heat dissipation path.

[0009] The heat absorbed by the thermal storage element can be released back to the power electronic component after the end of the load or temperature peak and dissipated via the primary heat dissipation path and / or via an additional heat dissipation path.

[0010] The thermal storage element is connected to the power electronic component via the interconnect layer, ensuring a reliable mechanical and thermal connection between the thermal storage element and the power electronic component.

[0011] Because the interconnect layer is electrically insulating, the thermal storage element can also be made of an electrically conductive material such as metal without the risk of short circuits with the power electronic component. This expands the selection of possible materials for the thermal storage element, allowing the material to be chosen specifically for high thermal conductivity and / or high specific heat capacity.

[0012] The thermal storage element can be a metal plate.

[0013] The metal plate comprises or consists of, for example, copper or aluminum.

[0014] Alternatively, the thermal storage assembly is arranged on a surface of the power electronic component facing away from the thermally conductive substrate. This effectively decouples the heat transfer to the thermal storage element from the primary heat conduction path.

[0015] The bonding layer can comprise a thermally conductive adhesive or a thermally conductive paste. In particular, the bonding layer consists of the thermally conductive adhesive or the thermally conductive paste.

[0016] In this context, the term "thermally conductive" refers to an adhesive or paste that has a thermal conductivity of at least 0.5 W / mK, for example a thermal conductivity in the range of 0.5 to 5.0 W / mK.

[0017] The thermal conductivity of the interconnect layer is specifically tailored to the temperature peaks expected during the operation of the respective power electronics module in order to optimize heat transfer to the thermal storage element.

[0018] A bonding layer made of thermally conductive adhesive or thermally conductive paste is particularly easy to apply during the assembly process of the power electronics module. This reduces the effort and costs involved in manufacturing the power electronics module.

[0019] To achieve even better cooling of the power electronic component, the thermal storage assembly can further include a cover that is thermally connected to the thermal storage element and the heat sink, thus creating a secondary heat dissipation path extending from the power electronic component, through the thermal storage element, to the heat sink. This secondary heat dissipation path serves as an additional route for heat removal. In this way, the thermal storage element can dissipate at least some of the heat absorbed during a temperature peak, even during the peak itself. This allows the power electronic component to be operated at a higher maximum current, enables a longer operating time at maximum current, and / or allows the thermal storage element to be designed smaller than would be possible without the secondary heat dissipation path.

[0020] Because the cover is thermally connected to the same heat sink that also forms the endpoint of the primary heat dissipation path, no additional means is required to remove the heat dissipated via the cover from the power electronics module.

[0021] Furthermore, the lid provides a simple and reliable way to dissipate heat from the thermal storage element, so that in particular liquid or gaseous working media for cooling the thermal storage element can be dispensed with, apart from any cooling fluids already intended in the heat sink.

[0022] The lid is made primarily of metal. This ensures high thermal conductivity of the lid, resulting in particularly effective cooling of the thermal storage element.

[0023] In particular, both the thermal storage element and the lid are made of the same metal. This prevents corrosion effects between metals with different electronegativity.

[0024] It is also possible for the thermal storage element and the cover to be manufactured as a single piece. This increases the mechanical stability of the components involved in the secondary heat dissipation path and further simplifies the assembly of the power electronics module.

[0025] The cover also serves as a cover for the power electronics module. In other words, the cover in this case performs a combined function as a cover for the power electronics module, for example as protection against environmental influences, and as part of the secondary heat dissipation path.

[0026] In a further embodiment, the power electronics module comprises several power electronic components, and the thermal storage assembly comprises several thermal storage elements, each assigned to one of the power electronic components. Specifically, each power electronic component is assigned a thermal storage assembly. The thermal storage assemblies serve to dissipate heat from their respective assigned power electronic component, as previously described for a single thermal storage assembly. Thus, even for a large number of power electronic components, it can be ensured that none of the power electronic components is heated above a permissible upper temperature limit in the event of load or temperature peaks.

[0027] Naturally, the thermal storage assemblies can be designed identically or at least partially differently from one another.

[0028] For example, thermal storage assemblies associated with power electronic components that are less effectively cooled via the primary heat dissipation paths associated with these power electronic components than other power electronic components of the power electronics module may exhibit higher thermal conductivity and / or thermal heat capacity than thermal storage assemblies associated with other power electronic components of the power electronics module. This results in a design optimized with regard to the existing heat dissipation paths.

[0029] Several of the power electronic components can be connected via the interconnect layer. This simplifies the application of the interconnect layer. Furthermore, heat exchange between the connected power electronic components can occur via the shared interconnect layer, resulting in an even more uniform temperature distribution within the power electronics module.

[0030] For example, the bonding layer is designed as a potting compound that at least partially covers several power electronic components.

[0031] It is also possible that the interconnect layer is formed as a film, for example as an adhesive film that extends over several of the power electronic components.

[0032] If several power electronic components are present in the power electronics module and the thermal storage assembly includes the cover described above, the cover is thermally connected to several of the power electronic components. In other words, the cover is thermally connected to several thermal storage elements, resulting in a secondary heat dissipation path from each power electronic component via its associated thermal storage element and the common cover to the heat sink. This design simplifies the design and assembly process of the power electronics module while simultaneously ensuring efficient cooling of several power electronic components connected to the cover.

[0033] It is understood that in this variant the size and thermal conductivity of the lid can be adapted to the amount of heat to be dissipated per unit of time via the secondary heat dissipation path.

[0034] In particular, the cover is thermally connected to all power electronic components. Therefore, only a single cover for the power electronics module is required.

[0035] The object of the invention is further achieved by a vehicle power converter with a power electronics module as described above.

[0036] The features and characteristics of the power electronics module apply accordingly to the vehicle power converter and vice versa.

[0037] The type of power converter is not fundamentally restricted. In particular, the power converter is an inverter designed to convert direct current from a vehicle's traction battery (in which the vehicle's power converter is used) into alternating current for the vehicle's electric drive motor.

[0038] Further features and characteristics will become apparent from the following description of exemplary embodiments, which are not to be understood in a restrictive sense, as well as from the drawings. These show: - Fig. 1 a schematic cross-sectional view of a first embodiment of a power electronics module according to the invention, - Fig. 2 a schematic cross-sectional view of a second embodiment of the power electronics module made of Fig. 1, and - Fig. 3 a schematic cross-sectional view of a third embodiment of the power electronics module made of Fig. 1.

[0039] Fig. Figure 1 shows a schematic cross-sectional view through selected parts of a power electronics module 10 according to the invention.

[0040] The power electronics module 10 is part of a vehicle power converter 11, which is not shown further and is in particular an inverter.

[0041] The power electronics module 10 comprises several power electronic components 12, for example, power semiconductor switches. The power electronic components 12 are connected to a heat sink 16 via a carrier 14 for heat transfer.

[0042] It is understood that the number of power electronic components may be 12 lower or higher than in Fig. 1 shown.

[0043] The carrier 14 is thermally conductive and has a multilayer structure, in the embodiment shown comprising a first material layer 18, a second material layer 20 and a third material layer 22, which are arranged one below the other in this order starting from the power electronic components 12 in the direction of the heat sink 16.

[0044] For example, the first material layer 18 is a copper layer to which the power electronic components 12 are attached, e.g., by means of solder. The second material layer 20 is, for example, a ceramic layer, while the third material layer 22 is a copper layer analogous to the first material layer 18. Naturally, a different structure of the substrate 14 is also possible, as long as heat transfer from the power electronic components 12 to the heat sink 16 is ensured.

[0045] In Fig. The first material layer 18, the second material layer 20, and the third material layer 22 are only schematically indicated. It is understood that these layers may have different thicknesses and cover different sized portions of the surface of the heat sink 16.

[0046] A cooling device 24, designed as a cooling coil through which a cooling fluid 26 flows, is arranged in the heat sink 16. This allows heat emitted by the heat sink 16 to be transferred to the cooling fluid 26 and dissipated.

[0047] Thus, a primary heat dissipation path is formed, which leads into Fig. The primary heat dissipation path for one of the power electronic components 12 is illustrated by an arrow W1. It extends from the power electronic component 12 across the substrate 14, specifically across the first material layer 18, the second material layer 20, and the third material layer 22, to the heat sink 16.

[0048] Each of the power electronic components 12 has a corresponding primary heat dissipation path.

[0049] The amount of heat that can be transferred per unit of time via the primary heat dissipation path is specifically tailored to the amount of heat generated by the power electronic components 12 during normal operation of the power electronics module 10. This ensures that continuously occurring heat losses from the power electronic components 12 do not cause them to heat up beyond an upper temperature limit.

[0050] A thermal storage assembly 30 is attached to a surface 28 of the power electronic components 12 facing away from the thermally conductive support 14.

[0051] The thermal storage assembly 30 comprises several thermal storage elements 32, each of which is attached to the power electronic component 12 associated with the respective thermal storage element 32 by means of a connecting layer 34.

[0052] The bonding layer 34 is thermally conductive and electrically insulating. For example, the bonding layer 34 consists of a thermally conductive adhesive or a thermally conductive paste, which in particular has a thermal conductivity of at least 0.5 W / mK.

[0053] Thus, the interconnect layer 34 enables good heat transfer from the power electronic component 12 to the thermal storage element 32.

[0054] To further optimize heat transfer, the thickness of the interconnect layer 34 is kept as small as possible, yet sufficiently large to reliably fix the thermal storage element 32 to the power electronic component 12. For example, the thickness of the interconnect layer 34 is equal to or less than 0.5 mm. In particular, the thickness of the interconnect layer 34 is in the range of 0.2 to 0.5 mm.

[0055] The thermal storage element 32 is a metal plate, for example a metal plate made of a metal with high thermal conductivity such as copper or aluminum.

[0056] The following section explains in more detail the functionality of the power electronics module 10 according to the invention.

[0057] As previously described, the waste heat generated during the operation of the power electronics module 10 at the power electronic components 12 is transferred to the heat sink 16 via the primary heat dissipation path during normal operation and can then be dissipated via the cooling fluid 26.

[0058] However, if a load or temperature peak occurs in which the heat loss accruing at the power electronic components 12 is greater than the amount of heat that can be dissipated via the primary heat dissipation path, this would lead to heating of the power electronic component 12, possibly up to a permissible upper limit temperature.

[0059] A load or temperature peak is represented in particular by an operation of the power electronic components 12 lasting for several seconds at a maximum current of the power electronic components 12, as can occur, for example, during an acceleration process of a vehicle that is at least partially electrically powered, in which the power electronics module 10 is used.

[0060] For example, such a load or temperature peak has a duration of at least 5 to 10 seconds.

[0061] In this case, according to the invention, an additional possibility exists in the form of the thermal storage assemblies 30, through which heat can be dissipated from the respective power electronic component 12.

[0062] In other words, heat is transferred to the thermal storage element 32 via the connection layer 34, i.e. via a shorter path compared to the primary heat dissipation path.

[0063] Thus, the thermal storage element 32 serves as a thermal buffer during the load or temperature peak to prevent the power electronic component 12 from overheating and to keep it below a permissible upper limit temperature.

[0064] Once the load or temperature peak has ended, the amount of heat dissipated per unit of time directly by the power electronic component 12 via the primary heat dissipation path decreases again. This allows the heat absorbed in the thermal storage element 32 to be released back to the power electronic component 12 and transferred to the heat sink 16 via the primary heat dissipation path. In other words, the temporarily stored heat is dissipated via the same heat dissipation path that is also used during normal operation of the power electronics module 10.

[0065] The thermal storage assembly 30 thus ensures that the power electronic components 12 are not heated above the permissible upper limit temperature even during load or temperature peaks, without having to increase the amount of heat that can be dissipated per unit of time via the primary heat dissipation path, for example by enlarging the heat sink 16.

[0066] Fig. Figure 2 shows a second embodiment of the power electronics module 10 according to the invention.

[0067] The second embodiment is essentially identical to the first, so only the differences will be discussed below. Identical reference numerals denote identical or functionally equivalent components, and reference is made to the explanations above.

[0068] In the second embodiment, several of the power electronic components 12 are interconnected via a common interconnect layer 34. Thus, the common interconnect layer 34 connects several power electronic components 12 to their respective associated thermal storage elements 32.

[0069] In this way, several groups of power electronic components 12 are formed in which heat exchange between the power electronic components 12 and the associated thermal storage elements 32 is enabled via the common interconnect layer 34.

[0070] Furthermore, the assembly process of the power electronics module 10 is simplified.

[0071] In the Fig. In the embodiment shown in Figure 2, the bonding layer 34 is designed as an adhesive film applied to the surface 28 of the power electronic components 12 facing away from the conductive support 14. However, alternative configurations of the bonding layer 34 are also possible, for example as a potting compound that partially or completely covers several of the power electronic components 12.

[0072] Naturally, fewer or more power electronic components 12 can be interconnected via the same interconnection layer 34 than in Fig. 2 is shown.

[0073] Fig. Figure 3 shows a third embodiment of the power electronics module 10 according to the invention.

[0074] The third embodiment essentially corresponds to the embodiments described above, so only the differences will be discussed below. Identical reference numerals denote identical or functionally equivalent components, and reference is made to the explanations above.

[0075] In the third embodiment, an additional cover 36 is provided, which thermally connects the thermal storage elements 32 to the heat sink 16. For this purpose, the cover 36 has a contact section 38, which is attached to a projection 40 of the heat sink 16. However, the cover 36 can also be connected to the heat sink 16 in another way, as long as direct heat transfer from the cover 36 to the heat sink 16 is ensured.

[0076] In this way, a secondary heat dissipation path is formed, which leads into Fig. 3 is indicated by an arrow W2 for one of the power electronic components 12 and extends from the respective power electronic component 12 via the connection layer 34, the thermal storage element 32 and the cover 36 to the heat sink 36.

[0077] Thus, each of the power electronic components 12 has a corresponding secondary heat dissipation path in addition to the primary heat dissipation path.

[0078] The lid 36, for example, is made of metal, in particular the same metal is used as the thermal storage elements 32 that are in contact with the lid.

[0079] Alternatively to the one in Fig. In the variant shown in 3, it is also possible that the thermal storage elements 32 and the cover 36 are made in one piece.

[0080] In Fig.Figure 3 also shows that several covers 36 are present, each connected to a portion of the power electronic components 12 in the power electronics module 10. It is also possible that only a single cover 36 is provided, which contacts all the power electronic components 12 of the power electronics module 10, or that only selected power electronic components 12 are connected to the cover 36.

[0081] The secondary heat dissipation path makes it possible to transfer at least some of the heat buffered in the thermal storage element 32 to the heat sink 16 during a load or temperature peak, without having to resort to the primary heat dissipation path.

[0082] After the load or temperature peak in the thermal storage element 32, the heat contained therein can subsequently be dissipated via both the primary heat dissipation path and the secondary heat dissipation path, thereby achieving a particularly fast temperature equalization and making the thermal storage element 32 available again more quickly with full capacity as a thermal intermediate storage for a subsequent load or temperature peak.

[0083] The power electronics module 10 according to the invention is characterized by excellent temperature control of the power electronic components 12, thereby enabling reliable and performance-optimized operation of the power electronics module 10. Furthermore, it is a cost-effective and space-saving design that allows for efficient cooling of the power electronic components 12. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 106 008 B3

[0004]

Claims

[1] Power electronics module (10) for a power converter (11) of a vehicle, wherein the power electronics module (10) comprises a power electronic component (12) mounted on a thermally conductive support (14), the thermally conductive support (14) being arranged on a heat sink (16) for cooling the power electronic component (12), such that a primary heat dissipation path is formed extending from the power electronic component (12) via the thermally conductive support (14) to the heat sink (16), and furthermore, a thermal storage assembly (30) is attached to the power electronic component (12), comprising a thermal storage element (32) and a connecting layer (34) which is thermally conductive and electrically insulating and connects the power electronic component (12) to the thermal storage element (32). [2] Power electronics module (10) according to claim 1, wherein the thermal storage element (32) is a metal plate. [3] Power electronics module (10) according to claim 1 or 2, wherein the thermal storage assembly (30) is arranged on a surface (28) of the power electronic component (12) facing away from the thermally conductive support (14). [4] Power electronics module (10) according to any of the preceding claims, wherein the interconnect layer (34) comprises a thermally conductive adhesive or a thermally conductive paste. [5] Power electronics module (10) according to one of the preceding claims, wherein the thermal storage assembly (30) further comprises a cover (36) which is thermally connected to the thermal storage element (32) and the heat sink (16) such that a secondary heat dissipation path is formed which extends from the power electronic component (12) via the thermal storage element (32) to the heat sink (16). [6] Power electronics module (10) according to claim 5, wherein the cover (36) is made of metal. [7] Power electronics module (10) according to one of the preceding claims, wherein the power electronics module (10) comprises several power electronic components (12) and the thermal storage assembly (30) comprises several thermal storage elements (32), each of which is assigned to one of the power electronic components (12). [8] Power electronics module (10) according to claim 7, wherein several of the power electronic components (12) are connected by means of the interconnect layer (34). [9] Power electronics module (10) according to claim 7 or 8, if referred back to claim 5 or 6, wherein the cover (36) is thermally connected to several of the power electronic components (12). [10] Vehicle power converter (11) with a power electronics module (10) according to one of the preceding claims.

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