Power module

Abstract

Title of the invention: Power module. The present invention relates to a power module (1) for a motor vehicle, comprising at least one electronic component (4), a metallic power bar (10, 10A, 10B, 10C), heat exchange means (26), and a cooling system comprising at least one conduit (24) configured for the circulation of a dielectric fluid. The metallic power bar (10, 10A, 10B, 10C) has a first face on which the electronic component (4) rests and a second opposite face. The heat exchange means (26) are integral with the second face. Abstract figure: Figure 1

Description

Title of the invention: Power module

[0001] The present invention relates to the field of power electronics, and more particularly to power modules.

[0002] Power electronics is implemented in motor vehicles, notably through power modules which are used in power electronic devices to generate alternating current from direct current. These power electronic devices thus form voltage converters which can be integrated into motor vehicles, particularly hybrid or electric vehicles, in order to convert the direct current supplied by the vehicle's batteries into alternating current to power the vehicle's electric motor.

[0003] Within an inverter, for example, the power modules are capable of cutting the current supplied by the energy source, i.e., the vehicle's battery, before sending it to the motor. These power modules are thus capable, based on control signals sent by the power electronics device, in particular of controlling the type and quantity of energy transferred from the vehicle's battery to the electric motor.

[0004] Power modules for this purpose include assemblies of electronic components through which the energy intended to power the electric motor flows. Such electronic components include chips comprising a plurality of electronic switches, for example, semiconductor transistors. By changing the position of the transistors, that is, by switching them from an open position to a closed position or vice versa, it is thus possible to vary the power supply to the different phases of the electric motor.

[0005] Depending on the applications for which the power module is intended to be used, the chips may operate at high voltages, for example, voltages on the order of 1000 to 1200 V. It is then necessary to control the chip temperature to prevent overheating and, consequently, chip malfunction. For this purpose, the chips can be placed on a cooling system such as a heatsink. Such a cooling system generally uses water, which is conductive, to cool the chip.

[0006] To prevent short circuits within the power module, it is known to use an isolation device within the power module. This isolation device, composed of different layers, is interposed between the chip and the cooling system. The isolation device is, for example, formed of two copper layers with a ceramic layer between them, the chip being secured. One of the copper layers is positioned opposite the insulation device. The ceramic layer provides thermal insulation between the chip and the water in the cooling system.

[0007] However, such a solution leads to a deterioration in the heat dissipation performance within the power module. Thermal resistance is indeed dependent on the number of layers within the power module; the greater its thickness, the less efficient the heat dissipation. It is therefore necessary to limit the chip's operation to ensure that it is sufficiently cooled.

[0008] The present invention falls within this context by proposing a power module in which the thermal resistance is improved by removing at least the ceramic layer of the insulation device and replacing the conductive water with a dielectric fluid.

[0009] The present invention thus has as its main object a power module of a motor vehicle, comprising at least one electronic component, a metallic power bar, heat exchange means and a cooling system comprising at least one conduit configured for the circulation of a dielectric fluid, the metallic power bar having a first face on which the electronic component rests and a second opposite face, the heat exchange means being attached to the second face.

[0010] The power module according to the invention is intended to equip a motor vehicle, for example by being integrated into an electronic power device of said motor vehicle. The power module comprises at least one electronic component corresponding to a chip capable of receiving high voltages, for example voltages between 1000 and 1200 V.

[0011] In order to cool the electronic component when operating at high voltages, the power module includes a cooling system configured for the circulation of a dielectric fluid, for example, oil, air, or purified water. Because of the presence of this dielectric, and therefore non-conductive, fluid, the electronic component is mounted on a metallic power bar of the power module. Here, "metallic" means that the power bar is made entirely of metal; in particular, it is devoid of ceramic. Compared to prior art insulation devices, which are generally composed of successive layers of copper, ceramic, and copper, the power module according to the invention eliminates the need for ceramic as an insulator by using a dielectric fluid.The use of a metallic power bar, compared to prior art insulation devices, allows... to improve the thermal resistance of the power module by limiting the number of layers that compose it and avoiding the use of ceramics.

[0012] Heat exchange between the electronic component on the one hand and the dielectric fluid on the other is ensured by means of heat exchangers which extend at least partially within the dielectric fluid circulation conduit. Depending on the embodiment, the heat exchangers are either integrated into the metallic power bar or separate from it.

[0013] According to an optional feature of the invention, the metallic power bar is a single layer.

[0014] In other words, the metal power bar is made in one piece. Thus, the first face and the second face of the metal power bar delimit a single-piece metal layer between the electronic component and the cooling system.

[0015] According to an optional feature of the invention, the metallic power bar is made of copper.

[0016] According to an optional feature of the invention, the metallic power bar is made of aluminum.

[0017] According to an optional feature of the invention, the heat exchange means comprise a plurality of fins extending at least partially within the cooling system.

[0018] The presence of fins increases the heat exchange surface area of ​​the heat exchange means. These fins extend at least partially within the dielectric fluid circulation conduit so as to be in contact with this dielectric fluid.

[0019] According to an optional feature of the invention, the metallic power bar and the heat exchange means are formed as a single unit.

[0020] This is a first embodiment in which the second face of the metallic power bar forms the heat exchange means. This second face then has projections that form the fins extending into the dielectric fluid circulation channel.

[0021] By way of example, the heat exchange means have a height, that is to say a dimension perpendicular to the stacking of the electronic component and the metallic power bar, which corresponds to at least 50% of the height of a main body of the metallic power bar. The main body of the metallic power bar here corresponds to the metallic power bar without the heat exchange means.

[0022] According to an optional feature of the invention, the heat exchange means comprise a plate in contact with the second face of the metallic power bar.

[0023] This corresponds to a second embodiment of the invention in which the heat exchange means are integrated into a radiator forming part of the power module. This radiator is formed of a plate extending along the metallic power bar and fins extending at least partially into the dielectric fluid circulation channel.

[0024] According to an optional feature of the invention, the power module includes at least one capacitor, the capacitor being at least partly disposed within the cooling system.

[0025] The capacitor allows for voltage smoothing within the power module. The capacitor can be implemented using individual components soldered onto a printed circuit board located within the cooling system, this printed circuit board being connected to the metallic power bar. Positioning the capacitor within the cooling system improves the compactness of the power module and reduces parasitic inductance between the capacitors and the other components of the power module.

[0026] According to an optional feature of the invention, the electronic component is secured to the first face of the metallic power bar by brazing.

[0027] Where appropriate, a layer of solder is intercalated between the electronic component and the first face of the metallic power bar.

[0028] According to an optional feature of the invention, the metallic power bar comprises a plurality of side walls connecting the first face and the second face, the power module comprising a housing made of plastic material surrounding at least partially the side walls.

[0029] When multiple metallic power bars are present, the plastic housing isolates them from one another. The plastic housing also contributes to ensuring the mechanical strength and sealing of the power module.

[0030] Depending on the embodiment, the metal power bar can be overmolded into the plastic housing or clipped into it. When the metal power bar is attached to the plastic housing before the electronic component is soldered, this necessitates choosing a plastic material resistant to the soldering temperature of the electronic component, unless sintering is used.

[0031] In the case of overmolding, the electronic component is brazed onto the metal power bar beforehand, and there is then no constraint relating to the choice of the plastic material of the housing.

[0032] According to an optional feature of the invention, the power module includes power connections to the metallic power bar arranged within the dielectric fluid circulation conduit.

[0033] The power connections allow the metallic power bar to be connected to a power source. Their arrangement within the dielectric fluid circulation channel saves space within the power module.

[0034] The invention further relates to an electronic power device of a motor vehicle, comprising a power module as previously mentioned.

[0035] The power electronic device is, for example, a voltage converter capable of transforming a direct current or voltage source into an alternating current or voltage. This makes it possible to power components of the motor vehicle that operate with alternating current or voltage, in particular an electrical machine of the motor vehicle.

[0036] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings on the other hand, in which:

[0037] [Fig-1] schematically illustrates a power module in a cross-sectional view, the power module including in particular an electronic component, a power bar and a cooling system;

[0038] [Fig.2] illustrates, schematically, a close-up cross-sectional view of the electronic component and the power bar.

[0039] The features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0040] In the figures, the elements common to several figures retain the same reference.

[0041] Figures 1 and 2 schematically illustrate a power module 1 according to the invention. This power module 1 is intended to equip a motor vehicle, for example by being integrated within a power electronics device such as a voltage converter. The power module 1 can thus contribute to transforming direct current into alternating current, in particular for the purpose of electrically powering an electric motor of the motor vehicle.

[0042] The power module 1 is controlled by means of a printed circuit board 2, for example a microprocessor. The printed circuit board 2 is more specifically used to drive at least one electronic component 4 or electronic chip of the power module 1, this electronic component 4 being used within power module 1 to manage the conversion of direct voltage to alternating voltage.

[0043] In an inverter application, the electronic component 4 is configured to operate at voltages between 60 and 1200 V. Structurally, the electronic component 4 is a wafer having an upper face 6 and a lower face 8 opposite each other in a vertical direction perpendicular to the printed circuit board 2. The upper face 6 and lower face 8 are particularly visible in [Fig. 2]. The upper face 6 of the electronic component 4 is a free face, while its lower face 8 rests on another component of the power module 1. More specifically, the electronic component 4 is positioned, via this lower face 8, on a metallic power bar 10 of the power module 1.

[0044] The metal power bar 10 provides physical connections between the various components of the power module 1, particularly in the presence of a plurality of electronic components 4 that can be aligned along a larger dimension of the metal power bar 10. The power module 1 can comprise a plurality of metal power bars 10. In other words, the power module 1 can comprise several electronic components 4 on the same metal power bar 10, as well as several metal power bars 10. As illustrated in [Fig. 1], the power module 1 here has a first metal power bar 10A and a second metal power bar 10B.The first metallic power bar 10A is, for example, associated with a positive current, while the second metallic power bar 10B is, for example, associated with a phase of an electric motor of the motor vehicle in which the power module 1 is integrated. The power module 1 of [Fig. 1] also includes a third power bar 10C, which is devoid of electronic component 4 and which is, for example, associated with a negative current.

[0045] The metal power bar 10 is made entirely of metal, for example copper or aluminum. More specifically, here, the metal power bar 10 is single-layered, that is to say, made of a single layer of a single metallic material.

[0046] The metal power bar 10 is delimited in the vertical direction by a first face 12 and a second face 14. The first and second faces 12, 14 are particularly visible in [Fig. 2]. The first face 12 of the metal power bar 10 is in contact with the lower face 8 of the electronic component 4. More precisely, and as illustrated in [Fig. 2], the electronic component 4 and the metal power bar 10 are joined by brazing such that a braze 16 forms a junction between the electronic component 4 and the metallic power bar 10.

[0047] The first face 12 and the second face 14 are connected to each other by side walls 18 of the metal power bar 10. As is particularly visible in [Fig. 1], at least some of these side walls 18 are surrounded by a plastic housing 20. The plastic housing 20 notably ensures that the metal power bars 10 are held within the power module 1. The metal power bars 10 are arranged here side by side within the plastic housing 20.

[0048] Within the power module 1, a connection is made between a given electronic component 4 and a given metal power bar 10 by means of at least one metal wire 22. In the example illustrated in [Fig. 1], the electronic component 4 carried by the first metal power bar 10A is connected by a metal wire 22 to the second metal power bar 10B, and the electronic component 4 carried by the second metal power bar 10B is connected by a metal wire 22 to the third metal power bar 10C. Each metal wire 22 extends more precisely between a given electronic component 4 and the first face 12 of the adjacent metal power bar 10.

[0049] The power module 1 includes a cooling system to ensure thermal regulation of the electronic components 4. This cooling system includes at least one circulation conduit 24 for a cooling fluid. More specifically, the circulation conduit 24 is configured here for the circulation of a dielectric fluid, for example, but not limited to, oil. The use of a dielectric fluid contributes to ensuring electrical insulation within the power module 1.

[0050] The cooling system is arranged opposite the second face 14 of the metal power bar 10. It follows from the above that the power module 1 is formed by a vertical stack of the circulation duct 24, the metal power bar 10 and the electronic component 4. The circulation duct 24 extends over one dimension of the plastic housing 20 which encloses the metal power bars 10 so as to ensure the simultaneous cooling of the electronic components 4 carried by these metal power bars 10.

[0051] Heat exchange between an electronic component 4 on the one hand and the dielectric fluid on the other hand is ensured via the associated metallic power bar and by heat exchange means 26 of the power module 1. These heat exchange means 26 are fins or thermal pins which extend mainly in the vertical direction towards the circulation duct 24. More specifically, the heat exchange means 26 are at least partially disposed within the circulation duct 24 in order to be in contact with the dielectric fluid which is channeled in said circulation duct 24.

[0052] In the embodiment shown in Figures 1 and 2, the heat exchange means 26 are formed as a single unit with the metal power bar 10; in other words, the heat exchange means 26 and the metal power bar 10 form a single unit. In this embodiment, the heat exchange means 26 correspond to projections formed in the second face 14 of the metal power bar 10.

[0053] However, without departing from the scope of the invention, one could imagine embodiments in which the heat exchange means 26 would be supported by a radiator of the power module 1. Such a radiator would then be interposed between the metallic power bar 10 and the circulation duct 24 of the cooling system. More precisely, the radiator would have a plate extending into contact with the second face 14 of the metallic power bar 10, this plate being the carrier of the heat exchange means 26.

[0054] In addition to its function of channeling the dielectric fluid, the circulation conduit 24 of the cooling system constitutes a housing for various components and connections of the power module 1. As such, the circulation conduit 24 contains in particular at least one capacitor 28. This capacitor 28 has a function of smoothing the voltage between the vehicle battery and the electronic components 4.

[0055] In this respect, the capacitors are electrically connected by power connections 30 which extend at least partially within the circulation duct 24 of the cooling system. These power connections 30 allow a connection between a DC power source on the one hand and at least one of the metallic power bars 10 on the other. In the example illustrated in [Fig. 1], the power module 1 comprises two power connections 30 which are respectively connected to the first power bar 10A and the third power bar 10C.

[0056] The present invention thus proposes a power module formed by a stack of an electronic component, a metallic power bar, and a cooling system configured for the circulation of a dielectric fluid. The presence of an exclusively metallic power bar improves the thermal resistance of the power module, the use of such a metallic power bar being permitted by the use of a dielectric fluid and therefore isolated within the cooling system.

[0057] The present invention is not limited to the means and configurations described and illustrated herein and also extends to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Demands

1. Power module (1) of a motor vehicle, comprising at least one electronic component (4), a metallic power bar (10, 10A, 10B, 10C), heat exchange means (26) and a cooling system comprising at least one conduit (24) configured for the circulation of a dielectric fluid, the metallic power bar (10, 10A, 10B, 10C) having a first face (12) on which rests the electronic component (4) and a second opposite face (14), the heat exchange means (26) being integral with the second face (14).

2. Power module (1) according to the preceding claim, wherein the metallic power bar (10, 10A, 10B, 10C) is a single layer.

3. Power module (1) according to any one of the preceding claims, wherein the metallic power bar (10, 10A, 10B, 10C) is made of copper.

4. Power module (1) according to any one of claims 1 and 2, wherein the metallic power bar (10, 10A, 10B, 10C) is made of aluminium.

5. Power module (1) according to any one of the preceding claims, wherein the heat exchange means (26) comprise a plurality of fins extending at least partly within the cooling system.

6. Power module (1) according to any one of the preceding claims, wherein the metallic power bar (10, 10A, 10B, 10C) and the heat exchange means (26) are formed as a single unit.

7. Power module (1) according to any one of claims 1 to 6, wherein the heat exchange means (26) comprise a plate in contact with the second face (14) of the metallic power bar (10, 10A, 10B, 10C).

8. Power module (1) according to any one of the preceding claims, comprising at least one capacity (26), the capacity (26) being at least partly disposed within the cooling system.

9. Power module (1) according to any one of the preceding claims, wherein the electronic component (4) is fixed to the first face (12) of the metallic power bar (10, 10A, 10B, 10C) by brazing.

10. Power module (1) according to any one of the preceding claims, wherein the metallic power bar (10, 10A, 10B, 10C) comprises a plurality of side walls (18) connecting the first face (12) and the second face (14), the power module (1) comprising a plastic material housing (20) at least partially surrounding the side walls (18).

11. Power module (1) according to any one of the preceding claims, comprising power connections (30) to the metallic power bar (10, 10A, 10B, 10C) arranged within the dielectric fluid circulation conduit (24).

12. Electronic power device (4) of a motor vehicle, comprising a power module (1) according to any one of the preceding claims.

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