Switch unit with additional bracket

Abstract

The invention relates to a switching unit for a motor vehicle, comprising at least one power module and a DC support capacitor, which extend side by side in an extension plane and are electrically connected to each other in a transverse direction in the extension plane, the switch unit also includes a metal bracket mounted on top of the DC support capacitor in a vertical direction perpendicular to the extension plane, the metal bracket being in thermal contact with the DC support capacitor.

Description

Technical Field

[0001] The present invention relates to the field of electronics and electrical engineering, and in particular to the field of a switch unit of a power converter as an inverter. Background Art

[0002] Switching units are power electronic devices that are able to generate alternating current from direct current. Switching units can be integrated into motor vehicles, in particular hybrid or electric vehicles, to convert direct current provided by the battery into alternating current to power the electric motor.

[0003] The switch unit includes at least one power module mounted on a heat sink, at least two bus bars, each bus bar being electrically connected to the power module to provide a DC voltage to the module, and at least one DC link capacitor being electrically connected to the bus bars through electrical terminals.

[0004] The power module contains various power components, while the DC link capacitor acts as a buffer and can balance fluctuations.

[0005] In some switch units, the power modules and the DC link capacitors are stacked, with the power modules mounted on heat sinks placed on top of the DC link capacitors.

[0006] Newer versions of the switch unit have been developed in which the power module and the DC link capacitor are positioned side by side, for example parallel to the floor of the vehicle. In these embodiments, new problems such as cooling the DC link capacitor have been raised due to the different relative positioning of the power module and the DC link capacitor. Summary of the invention

[0007] In this case, the present invention relates to a switch unit for a motor vehicle, comprising at least one power module and a DC support capacitor, which extend side by side in an extension plane and are electrically connected to each other along a lateral direction in the extension plane, and the switch unit also includes a metal bracket installed on top of the DC support capacitor along a vertical direction perpendicular to the extension plane, and the metal bracket is in thermal contact with the DC support capacitor.

[0008] The metal bracket provides a heat sink for the DC link capacitor without increasing the size of the switch unit. In addition, the metal bracket provides shielding around the DC link capacitor in the switch unit.

[0009] The switch unit according to the invention is intended to be implemented in a vehicle, such as a hybrid or electric vehicle, in order to power its electric motor. According to an optional feature of the invention, the metal support comprises at least one dome extending vertically.

[0010] According to an optional feature of the invention, the metal bracket comprises at least a first vertical wall extending at least partially along the transverse direction.

[0011] According to an optional feature of the invention, the metal bracket comprises at least a second vertical wall extending transversely to the first wall.

[0012] According to an optional feature of the invention, the switch unit comprises a gap filler between the metal support and the DC link capacitor, thermally connecting the support with the DC link capacitor.

[0013] According to an optional feature of the invention, the switch unit comprises a housing, the switch unit comprising a second gap filler below the DC link capacitor in a vertical direction, thermally connecting the DC link capacitor to the housing.

[0014] According to an optional feature of the invention, the DC link capacitor comprises a housing and a metal layer, the metal layer contacting the second gap filler through an opening in a base of the housing of the DC link capacitor.

[0015] According to an optional feature of the invention, the dome is comprised in the first vertical wall.

[0016] The invention also relates to an assembly comprising a switch unit and further comprising a control board, the control board being fixed to the switch unit by means of fixing the control board to the dome.

[0017] According to an optional feature of the invention, the dome is adapted to receive the attachment means, the control plate comprising an opening through which the attachment means is inserted, the attachment means being inserted into the dome. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, details and advantages of the invention will become more apparent on the one hand by reading the following description and on the other hand by referring to the accompanying drawings, which give several implementation examples by way of indication and not limitation, in which:

[0019] Figure 1 is a schematic diagram of a switch unit according to the present invention, the switch unit comprising a power module, a DC support capacitor and a connecting device, the DC support capacitor and the power module being positioned side by side;

[0020] Figure 2 is a cross-sectional view of the switch unit.

[0021] Figure 3 The brackets on the DC link capacitors are shown.

[0022] Figure 4 The control board is shown mounted on the switch unit.

[0023] Figure 5 is a cross-sectional view of a switch unit including a housing. DETAILED DESCRIPTION

[0024] The features, variations and different implementation modes of the present invention can be associated with each other in various combinations, as long as they do not contradict or exclude each other. In particular, it is possible to envision a variant of the present invention that only includes the selection of the features described later from the other features described, if this feature selection is sufficient to confer technical advantages and / or distinguish the present invention from the prior art.

[0025] Like numbers refer to like elements throughout the drawings.

[0026] Figures 1 to 5 A switch unit 1 according to the invention is schematically shown. The switch unit 1 is configured to be installed in a motor vehicle, such as an electric or hybrid vehicle, with the purpose of generating alternating current suitable for powering the motor of the vehicle. To this end, the switch unit 1 comprises three power modules 2 mounted on a heat sink, the power modules housing various power components connected to a DC link capacitor 6 in which energy can be stored. The three power modules and the DC link capacitor are positioned side by side and embedded in a metal housing 10, which can be a unique housing or a combination of the power module housings and the DC link capacitor housings.

[0027] A connection arrangement extends between the power module and the DC link capacitor in the space between their respective bodies.

[0028] The switch unit includes a high potential component and a low potential component. The high potential component is usually a DC support capacitor component, a power module or an active discharge component, and the low potential component is usually a microcontroller, a chip, and a signal connector.

[0029] In the following description, the terms "longitudinal", "transverse" and "vertical" refer to the orientation of the switch unit according to the invention. The longitudinal direction corresponds to the direction of spatial alignment between the power modules, the DC support capacitors and their bodies, the power modules and the DC support capacitors being positioned side by side, parallel to the longitudinal axis L of the coordinate system L, V, T shown in the figure. The transverse direction corresponds to the direction in which the connecting device extends mainly in the space between the bodies, parallel to the transverse axis T of the coordinate system L, V, T and perpendicular to the longitudinal axis L. In the figure, the three power modules are aligned along the transverse direction. Finally, the vertical direction corresponds to the vertical axis V of the coordinate system L, V, T, perpendicular to the longitudinal axis L and the transverse axis T. The vertical direction is perpendicular to the extension plane of the DC support capacitors.

[0030] The power converter further comprises an electronic control board 7 for controlling the power modules of the switching units. The electronic control board 7 extends above the power modules and above the DC link capacitors.

[0031] The DC link capacitor 6 comprises a body having a capacitive element and two electrical terminals. Each electrical terminal is connected to a bus bar to receive a DC voltage. These DC link capacitors are designed to smooth the DC voltage UDC and are generally referred to as "DC link capacitors".

[0032] The switch unit may comprise a plurality of individual DC link capacitors connected in parallel.For example, the switch unit may comprise a single DC link capacitor that is substantially identical.

[0033] The bus bars are connected to the power modules 2 to distribute the DC voltage to the power modules.

[0034] Each power module is designed, for example, to implement a DC voltage U DC The AC voltage can be a phase voltage of a motor. For example, each power module has two external AC connectors, which are designed to provide the AC voltage. In addition to the external AC connectors, each power module also includes an external connector called positive and an external connector called negative, which are designed to be connected to the positive bus bar and the negative bus bar, respectively. In the example shown in the figure, two negative external connectors are provided for each power module. These external connectors are, for example, in the form of flat bars.

[0035] To perform voltage conversion, each power module comprises at least one switching arm, thus comprising two switches connected to each other at a midpoint. The midpoint is connected to an external AC connector to provide an AC voltage. The switching arms are connected between the external connectors to provide a DC voltage U DC .

[0036] Each switch is preferably a semiconductor controllable switch, such as a transistor switch, such as a metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) or a gallium nitride field effect transistor (GaNFET).

[0037] The body 60 of the DC support capacitor includes, for example, a capacitive element and an insulating element covering the capacitive element. The capacitive element is the part of the capacitor that stores electrical energy. For example, the capacitive element is a wound metallized plastic film. The insulating element may be an overmolding. The insulating element is made of, for example, resin.

[0038] The DC link capacitor further comprises a housing 61, for example of plastic, or it may be metal. Typically, the body 60 is glued / potted to the housing.

[0039] Additional thermal components are added to cool the DC link capacitors. Figure 5As shown, the thermal component 52 is a thermally conductive gap filler arranged between the DC support capacitor and the housing of the switch unit 10. The housing 61 includes an opening 610 at its base, and the gap filler 52 is in contact with the DC support capacitor and the housing 10 through the opening 610. The DC support capacitor advantageously includes a metal layer 62, such as aluminum, on the bottom side of the capacitor body. The metal layer 62 is insulated from the busbars by an insulating layer, but is in thermal contact with the body. The metal layer 62 is in contact with the gap filler 52 to remove heat from the DC support capacitor through the housing 10.

[0040] The metal housing 10 is advantageously cooled by the heat sink of the power module. Thus, the thermal contact through the gap filler between the DC link capacitor and the housing increases the cooling efficiency of the DC link capacitor.

[0041] The material of the gap filler 52 is a silicone-based liquid gap filler, whose thermal conductivity is between 3 and 4 W / mK, and typically about 3.6 W / mK.

[0042] A metal bracket is mounted on top of the DC support capacitor. The bracket may be a conductive metal, such as copper or steel. The bracket covers at least part of the DC support capacitor. The bracket is attached to the housing 10, for example, by screws.

[0043] The support comprises a plate portion extending above the DC link capacitor. The plate portion has a shielding function between high potential components from the DC link capacitor and low voltage components from the switch unit.

[0044] Reference Figure 2 A thermally conductive gap filler 51 is also arranged between the DC link capacitor and the bottom surface of the bracket. The gap filler is also a liquid gap filler, for example based on silicone, with a thermal conductivity between 3 and 4 W / mK, typically about 3.6 W / mK. The gap filler improves the thermal conductivity between the bracket and the DC link capacitor to discharge heat through the bracket. The gap filler fills the space between the resin of the DC link capacitor and the plate of the bracket. The DC link capacitor may also include a cooling plate at its top surface to transfer heat mainly from the bus bars of the DC link capacitor to the gap filler and then to the bracket.

[0045] Reference Figure 2 Or 3, the bracket includes a dome 41 extending vertically from the top surface of the plate. The electronic control board is mounted on the dome. The dome 41 is usually 20mm high.

[0046] For example, Figure 4 As shown, the electronic control board is screwed on the dome. In one embodiment, at least one dome is a hollow tube equipped with a thread. Screws 70 pass through the electronic board 7 and are then introduced into the dome 41 to fix the control board 7 on the bracket 4.

[0047] Advantageously, there is also a dome 20 extending vertically from the additional piece partially covering the power module. Thus, the domes 20 on both sides of the switch unit are advantageously of the same height and the electronic control board is mounted on the dome.

[0048] This assembly for carrying the control board avoids deformation of the control board under vibration.

[0049] The two domes extending from the top surface of the support plate are advantageously separated by a minimum distance in the plane of extension of the plate to avoid vertical bending of the control plate between the two domes exceeding 0.5 mm. The distance between the two domes in this plane is typically 50 to 70 mm.

[0050] The domes are also positioned close to heavy components such as transformers, active discharge components or resistors.

[0051] Reference Figure 2 Or 3, the bracket also includes a wall extending vertically from the plate.

[0052] The first vertical wall 42a extends in the transverse direction. The first wall extends along the connection means above the DC link capacitor. This wall 42a creates a shield between the power modules of the high potential components and the low potential components from the control board.

[0053] Another vertical wall 42b extends transversely to the first vertical wall. This second wall creates a shield between high and low potentials, acting as a signal connector or component of the control board. This second wall crosses the first wall at an angle in the plane of the board comprised within the range [75°-105°], advantageously at an angle equal to 90°.

[0054] The second wall 42 b intersects the first wall 42 a in the middle of the first wall 42 a along the lateral direction.

[0055] The support including the walls and the dome is advantageously cast.

[0056] Some domes 41 are included in the walls 42a, 42b, simplifying the casting process. Other domes are not included in the walls. The height of the walls is typically between 15 mm and 20 mm.

[0057] Many modifications and other embodiments of the invention set forth herein will occur to those skilled in the art having the benefit of the teachings given in the foregoing description and the associated drawings. Therefore, it should be understood that the invention is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are used herein, they are used in a general and descriptive sense only and not for the purpose of limitation.

Claims

1. A switch unit (1) for a motor vehicle, comprising at least one power module (2) and a DC link capacitor (6), which extend side by side in an extension plane and are electrically connected to each other along a transverse direction in the extension plane, The switch unit further comprises a metal bracket (4) mounted on the top of the DC support capacitor in a vertical direction perpendicular to the extension plane, the metal bracket being in thermal contact with the DC support capacitor.

2. Switching unit (1) according to the preceding claim, wherein: The metal support comprises at least one dome (41) extending vertically.

3. Switching unit (1) according to the preceding claim, wherein: The metal bracket comprises at least a first vertical wall (42a) extending at least partially along the transverse direction.

4. Switching unit (1) according to the preceding claim, wherein: The metal bracket includes at least a second vertical wall (42b) extending transversely to the first wall (42a).

5. Switchgear unit (1) according to the preceding claim, comprising a gap filler (51) between the metal support and the DC link capacitor, which thermally connects the support with the DC link capacitor.

6. The switch unit (1) according to the preceding claim, comprising a housing (10), the switch unit comprising a second gap filler (52) below the DC link capacitor in the vertical direction, which thermally connects the DC link capacitor to the housing.

7. The switch unit (1) according to claim 6, wherein: The DC link capacitor comprises a housing (61) and a metal layer (62) which contacts the second gap filler (52) through an opening (610) in a base of the housing (61) of the DC link capacitor.

8. The switch unit (1) according to the preceding claim in combination with claims 2 and 3, wherein: The dome (41) is included in the first vertical wall (42a).

9. An assembly comprising a switch unit according to any of the preceding claims in combination with claim 2, the assembly further comprising a control board (7) secured to the switch unit by means of securing the control board to the dome (41).

10. The assembly according to claim 9, wherein: The dome (41) is adapted to receive an attachment device (70), the control panel (7) comprising an opening through which the attachment device (70) is inserted, the attachment device being inserted into the dome (41).

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