Electronic power module cooled by immersion in a dielectric liquid

Abstract

The present invention relates to an electronic power module (2) configured to be immersed in a flow of cooling dielectric fluid (3), such that the flow of dielectric fluid (3) dissipates heat, the power module (2) comprising: - a first conductive substrate (4); - an electronic component (6) mounted on a first face of the first substrate (4); - an electrical connector (8) connected to the electronic component (6) by a connecting element (10); - a cover (12) configured to encapsulate at least the first substrate (4) and the connecting element (10); the electronic power module (2) being characterized in that the cover (12) comprises at least one opening configured such that the dielectric fluid (3) dissipates directly, by thermal convection, the heat generated by the first substrate (4) and by the electrical connector (8).

Description

DESCRIPTION Title of the invention: Power electronic module cooled by immersion in a dielectric liquid TECHNICAL FIELD

[0001] The present invention relates to the technical field of electrical equipment, in particular configured to be installed on board a vehicle, for example a hybrid or electric vehicle.

[0002] More particularly, the invention relates to the cooling of such electrical equipment by immersion in a dielectric fluid. STATE OF THE ART

[0003] To cool electrical equipment such as a voltage converter, in particular of an electric or hybrid vehicle, it is known from the prior art to provide a conduit through a housing of the electrical equipment, the conduit being configured to circulate a fluid such as water, making it possible to dissipate by thermal conduction the heat generated inside the housing. However, certain electronic components such as electrical connectors, commonly referred to in English by the term "busbar", conduct very high intensity currents and generate a quantity of heat that cannot be dissipated satisfactorily in such electrical equipment.

[0004] It is known in the technical field of computers, particularly supercomputers, to fully immerse supercomputer electronic components in a pool of phase-change dielectric fluid, allowing the heat generated by said components to be dissipated by thermal conduction, which results in the formation of bubbles within the phase-change fluid. This cooling method is commonly referred to in English as "immersive cooling". However, the electrical currents circulating in a supercomputer are lower than those circulating in the components of electrical equipment in a motor vehicle, and therefore generate less heat than the components of electrical equipment in a motor vehicle. Furthermore, the architecture of immersion in a pool of phase-change dielectric fluid is not transposable to cooling within a vehicle.

[0005] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing electrical equipment cooled by immersion in a dielectric fluid whose cooling performance is significantly improved. PRESENTATION OF THE INVENTION

[0006] More specifically, the subject of the invention is an electronic power module configured to be at least partially immersed in a flow of dielectric cooling fluid, so that the flow of dielectric fluid dissipates heat generated by the electronic power module, the electronic power module comprising: - a first electrically conductive substrate; - at least one electronic component mounted on a first face of the first substrate; - at least one electrical connector electrically connected to the electronic component by a connecting element and configured to be connected to external equipment; - a coating configured to encapsulate at least the first substrate and the bonding element;

[0007] The power electronic module is notable in that the coating comprises at least one opening configured such that the dielectric fluid directly dissipates by thermal convection heat generated by the first substrate and by the electrical connector.

[0008] Thanks to such a combination of characteristics, the constituent elements of a power module are immersed in the flow and cooled directly upon contact with the dielectric fluid. The overall cooling of such a power module is then significantly improved, improving the reliability and efficiency of said power module. In addition, the assembly of such a power module is simplified, the function of electrically insulating the electronic components from each other being ensured by the dielectric fluid, in particular in place of layers of electrically insulating materials such as silicon nitride ceramics.

[0009] Advantageously, the coating only and entirely encapsulates the connecting element. In such a configuration, the connecting element is isolated from the dielectric fluid, and from any thermal expansion that could be caused by contact between the dielectric fluid and the connecting element.

[0010] Advantageously, the connecting element is a wiring wire. A wiring wire is commonly referred to in English as “bonding”. More preferably, the wiring wire is formed from aluminum.

[0011] Advantageously, the coating is a plastic overmolding. Thus, the opening of the coating is preferably made by means of a cutout made in the coating. Alternatively, the opening is achieved during the formation of the coating overmolding operation.

[0012] Advantageously, the electronic component is a semiconductor chip. Preferably, the electronic component is a semiconductor chip formed from silicon carbide.

[0013] Advantageously, the first substrate and the electrical connector are formed from the same material. Preferably, the first substrate and the electrical connector are formed from copper.

[0014] Advantageously, the dielectric fluid is a single-phase dielectric liquid. Thus, in the absence of a phase change, the flow of the liquid without disturbance is substantially uniform in the power module.

[0015] According to another aspect of the invention, it relates to electrical equipment, comprising: - a housing delimiting a housing configured to receive a flow of dielectric fluid; - at least one power electronic module as described above, the power electronic module being immersed in the dielectric fluid; - at least one electrical connector electrically connected to the electronic component by a connecting element and configured to be connected to external equipment;

[0016] According to another aspect of the invention, it relates to an electric or hybrid vehicle, comprising electrical equipment as described above. PRESENTATION OF THE FIGURES

[0017] The invention will be better understood on reading the following description, given solely by way of example, and referring to the appended drawings given as non-limiting examples, in which identical references are given to similar objects and in which:

[0018] Figure 1 is a schematic representation in top view of electrical equipment comprising a power module according to a first embodiment of the invention;

[0019] Figure 2 is a schematic representation in top view of a power module according to the same embodiment as Figure 1, in the position removed from a covering;

[0020] Figure 3 is a schematic isometric perspective representation of a covering of the power module of Figure 2.;

[0021] Figure 4 is a top view schematic representation of the power module of Figure 2 in a position encapsulating the coating of Figure 3;

[0022] Figure 5 is a schematic cross-sectional representation of the power module of Figure 2.

[0023] It should be noted that the figures set out the invention in detail to enable the invention to be implemented; although not limiting, said figures serve in particular to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0024] The invention relates to an electrical equipment 2, in particular configured to be carried by an electric or hybrid vehicle. The electrical equipment 2 is for example a voltage converter such as an inverter, as illustrated in FIG. 1.

[0025] The electrical equipment 1 comprises a housing delimiting a housing configured to receive a flow of dielectric fluid 3 in which a flow of dielectric fluid 3 flows. For reasons of readability, the housing and the dielectric fluid 3 are not illustrated in FIG. 1. The dielectric fluid 3 is preferably a dielectric single-phase liquid. Thus, in the absence of a phase change, the flow of the liquid without disturbance is substantially uniform in the housing.

[0026] The electrical equipment 1 comprises in particular an electronic power module 2. The electronic power module 2 is configured to be at least partially immersed in the flow of dielectric fluid 3, so that the dielectric fluid 3 dissipates heat generated by the electronic power module 2.

[0027] The power electronic module comprises a first electrically conductive substrate 4, as illustrated in FIG. 2. The first substrate 4 is substantially planar and is commonly referred to by the abbreviation “SMI” (Insulated Metal Substrate). The first substrate 4 comprises a first face on which at least one electronic component 6 is mounted. The electronic component 6 is preferably a semiconductor such as a silicon carbide-based semiconductor chip.

[0028] The electronic power module 2 also comprises at least one electrical connector 8 electrically connected to the electronic component 6 via a connection 10. The electrical connector 8 is configured to be connected to equipment external to the power electronic module 2 and external to the electrical equipment 1, for example to the phases of a rotating electrical machine. Here, the first substrate 4 and the electrical connector 8 are formed from the same material, for example copper. Thus, the convection thermal resistance of the electrical connector 8 and the first substrate 4 are identical, allowing uniform heat dissipation. Alternatively, the first substrate 4 and the electrical connector 8 may be formed from a different material, for example when the first substrate 4 is formed from aluminum.

[0029] The power electronic module 2 further comprises a coating 12 illustrated alone in FIG. 3. The coating 12 is configured to encapsulate at least the first substrate 4 and the connecting element 10 as illustrated in FIG. 4. The coating 12 comprises at least one opening configured so that the dielectric fluid 3 directly dissipates by thermal convection the heat generated by the first substrate 4. The term “encapsulate” is understood to mean that here, portions of the first substrate 4 and portions of the connecting element 10 are isolated from the dielectric fluid 3. In other words, said portions of the first substrate 4 and the connecting element 10 are not directly in contact with the dielectric fluid. The dielectric fluid also directly dissipates the heat generated by the electrical connector 8.Thanks to such an opening in the coating 12, the constituent elements of an electronic power module 2 are immersed in the flow and cooled directly in contact with the dielectric fluid 3. The general cooling of such an electronic power module 2 is then significantly improved, improving the reliability and efficiency of said electronic power module 2, and therefore of the electrical equipment 1.

[0030] The coating 12 is here formed from a plastic overmolding, the opening is preferably provided in the coating 12 by means of a cutout. Alternatively, the opening is obtained during the formation of the coating 12, that is to say during the overmolding operation. The coating 12 is illustrated here in a single piece, but can alternatively be in several pieces, depending on the elements that one wishes to encapsulate.

[0031] The implementation of the encapsulation by the coating 12 is schematically illustrated in Figure 5 and described below. The electronic component 6 is fixed on the first face of the first substrate 4 by means of a sintering 14, for example a silver sintering. The connecting element 10 is soldered onto the electronic component 6 by means of a solder 16. The opening in the coating 12 is then such that the electronic component 6 is immersed in the dielectric fluid. Thus, the assembly of such a power electronic module 2 is simplified and differs from a traditional power electronic module in that the function of electrically insulating the electronic components from each other is ensured by the dielectric fluid 3, in particular in place of a layer of electrically insulating material such as a silicon nitride ceramic.

[0032] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiment described above, in light of the teaching which has just been disclosed to them.

[0033] In one embodiment (not shown), the coating 12 only fully encapsulates the bonding element 10. In such a configuration, the bonding element 10 is isolated from the dielectric fluid, and is protected from any thermal expansion that could be caused by contact between the dielectric fluid 3 and the bonding element 10. In this embodiment, the bonding element 10 is preferably a wiring wire, commonly referred to in English as "bonding", "wire bonding" or "bonding ribbons".

[0034] In the detailed presentation of the invention given above, the terms used should not be interpreted as limiting the invention to the embodiment set forth in the present description, but should be interpreted to include all equivalents the prediction of which is within the reach of a person skilled in the art by applying his general knowledge to the implementation of the teaching just disclosed to him.

Claims

CLAIMS 1. Power electronic module (2) configured to be at least partially immersed in a flow of cooling dielectric fluid (3), such that the flow of dielectric fluid (3) dissipates heat generated by the power electronic module (2), the power electronic module (2) comprising: - a first electrically conductive substrate (4); - at least one electronic component (6) mounted on a first face of the first substrate (4); - at least one electrical connector (8) electrically connected to the electronic component (6) by a connecting element (10) and configured to be connected to external equipment; - a coating (12) configured to encapsulate at least the first substrate (4) and the connecting element (10); the power electronic module (2) being characterized in that the coating (12) comprises at least one opening configured so that the dielectric fluid (3) directly dissipates by thermal convection the heat generated by the first substrate (4) and by the electrical connector (8).

2. Power electronic module (2) according to claim 1, in which the coating (12) only and entirely encapsulates the connecting element (10).

3. Power electronic module (2) according to claim 2, wherein the connecting element (10) is a wiring wire.

4. Electronic power module (2) according to any one of the preceding claims, in which the coating (12) is a plastic overmolding.

5. Power electronic module (2) according to any one of the preceding claims, in which the electronic component (6) is a semiconductor chip.

6. Power electronic module (2) according to any one of the preceding claims, in which the first substrate (4) and the electrical connector (8) are formed from the same material.

7. Power electronic module (2) according to any one of the preceding claims, in which the dielectric fluid (3) is a single-phase dielectric liquid.

8. Electrical equipment (1), comprising: - a housing delimiting a housing configured to receive a flow of dielectric fluid (3); - at least one power electronic module (2) according to any one of claims 1 to 7, the power electronic module (2) being immersed in the dielectric fluid (3); - at least one electrical connector (8) electrically connected to the electronic component (6) by a connecting element (10) and configured to be connected to external equipment; 9. Electric or hybrid vehicle, comprising electrical equipment (1) according to claim 8.

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