Switching cell with additional bracket

Abstract

To cool a power module in a switching cell further efficiently.SOLUTION: The switching cell includes at least one power module that is mounted on a support and extends in a plane, a spring device, and a metal plate. The metal plate presses the spring device on the power module downward in the vertical direction perpendicular to the plane. The metal plate covers only a part of the power module in the plane.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to the field of electronics and electrical engineering, more particularly to the field of switching cells. [Background technology]

[0002] A switching cell is a power electronic device that can generate alternating current from direct current. They are integrated in automobiles, especially hybrid and electric vehicles, to convert the direct current provided by the battery into alternating current to power the electric motor.

[0003] The switching cell comprises at least one power module mounted on a heat sink, at least two bus bars each connected to a power module to supply a DC voltage to said module, and at least one DC link capacitor electrically connected to the bus bars via electrical terminals. The power module includes various power components. Meanwhile, the DC link capacitor can be used as a buffer and balance the fluctuations.

[0004] Power modules are components that can get hot up to 150 degrees Celsius and need to be cooled by at least 30 degrees Celsius to improve efficiency.

[0005] There is a need to cool power modules more efficiently.

[0006] The present invention meets this situation by providing a switching cell in which a metal plate covering only a part of the top surface of the power module is used to press downwards on the bottom surface of the power module on the heat sink. The power module is thus efficiently cooled both by thermal conduction between the top surface of the power module and the metal plate and by the fact that a part of the power module is not covered by the metal plate. Moreover, the bottom surface of the power module improves its cooling since the metal plate keeps the power module on the heat sink efficiently. Summary of the Invention

[0007] A switching cell according to the present invention comprises at least one power module mounted on a support, the power module extending in a plane, a spring device and a metal plate, the metal plate pressing the spring device on the power module downwards in a vertical direction perpendicular to the plane, the metal plate covering only a portion of the power module in the plane.

[0008] The switching cell according to the invention is intended to be mounted in a vehicle, for example a hybrid or electric vehicle, to power an electric motor thereof. According to an optional feature of the invention, the metal plate covers a central area of ​​the power module in said plane.

[0009] The pressure is therefore located in the center of the power module. With this simpler solution, the pins of the power module do not need to be set on the outside of the power module.

[0010] According to an optional feature of the invention, the metal plate comprises at least one leg extending beyond the power module in the plane, the leg comprising at least one means for attaching the metal plate to the support.

[0011] This ensures that the metal plate is fastened to a support, such as a cooling device.

[0012] According to an optional feature of the invention, the clearance distance between a pin extending from the power module and the metal plate is in the range of 2mm to 6mm, and is advantageously 4mm.

[0013] According to an optional feature of the invention, the creepage distance between a pin extending from the power module and the metal plate is in the range 3mm to 7mm, advantageously 5mm.

[0014] According to an optional feature of the invention, the metal plate includes at least one dome extending vertically from a top surface of the metal plate.

[0015] The dome is a support for the control panel.

[0016] According to an optional feature of the invention, at least two power modules are arranged longitudinally in the plane, and the dome is positioned longitudinally between the power modules.

[0017] According to an optional feature of the invention, the spring means is integrally formed with the metal plate, the spring means and the metal being of the same material.

[0018] According to an optional feature of the invention, the spring device comprises at least one blade pressing downwards on the power module, the blade having a U-shape with a central arm and two legs, the blade being adapted such that when the metal plate presses against the tip end of the central arm, an intermediate portion of the central arm presses downwards on the power module.

[0019] According to an optional feature of the invention, the switching cell comprises at least two bus bars, each bus bar electrically connected to the power module, and at least one DC link capacitor electrically connected to the bus bars, the power modules and the DC link capacitors being positioned side-by-side.

[0020] Other characteristics, details and advantages of the invention will emerge more clearly from reading the following description on the one hand and a number of non-limiting examples given with reference to the attached schematic drawings on the other hand. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a schematic diagram of a switching cell according to the present invention; [Diagram 2]1 shows the upper metal plate of the power module. [Diagram 3] FIG. 2 is a cutaway view of a flat switching cell. [Figure 4] Shows a U-shaped blade pressing the power module downwards with a metal plate. [Diagram 5] FIG. 2 is a view of the underside of the metal plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The features, variants, and different aspects of the embodiments of the invention may be associated in various combinations, provided they are not mutually inconsistent or exclusive. In particular, variants of the invention that include only a selection of the features described below from other features described may be envisioned, where such selection of features is sufficient to confer technical advantage and / or to differentiate the invention from the prior art.

[0023] Like numbers refer to like elements throughout the drawings.

[0024] Figure 1 shows a schematic representation of a switching cell 1 according to the invention. The switching cell 1 is adapted to be installed in a motor vehicle, such as an electric or hybrid vehicle, in order to generate an alternating current suitable for powering the motor of the vehicle. For this purpose, the switching cell 1 comprises at least one power module 2 housing various power components connected to a DC link capacitor 6 in which energy can be stored. The switching cell shown and disclosed herein comprises three power modules 2a, 2b, 2c.

[0025] As shown in the drawings, in this embodiment the power module and DC link capacitor 6 are positioned side-by-side as shown in FIG.

[0026] The switching cell 1 further includes an electronic control board 7 for controlling the power modules. The electronic control board 7 extends, for example, above the power modules 2a, 2b, 2c.

[0027] The DC link capacitor 6 comprises a body having a capacitive element and two electrical terminals. Each of the electrical terminals is arranged to electrically connect to one bus bar 60. The bus bars are connected to a DC voltage U DC Both bus bars 60 connect to each of the power modules 2a, 2b, 2c to distribute the DC voltage to the power modules.

[0028] Each power module is connected to, for example, a DC voltage U DC and the respective AC voltage, which may for example be the phase voltage of the electric machine. Each power module has, for example, two external AC connectors 21a and 21b designed to present this AC voltage, as shown. Besides the external AC connectors 21a and 21b, each power module also comprises an external connector called positive 22 and an external connector called negative 23, designed to connect to the positive busbar and the negative busbar, respectively. In the example shown, two negative external connectors 23 are provided for each power module. These external connectors 21a, 21b, 22, 23 have for example a flat bar shape.

[0029] To perform the voltage conversion, each power module comprises at least one switching arm, and therefore contains two switches in a housing 24, which are connected to each other at a midpoint. The midpoint is connected to the external AC connectors 21a, 21b to present an AC voltage. The switching arms are connected between the external connectors 22, 23 and present a DC voltage U DC Present the following.

[0030] Each switch is preferably a semiconductor controllable switch, for example 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).

[0031] Each power module also has a control pin 25, enabling inter alia the control board 7 to control the switching of the switches.

[0032] The switching cell 1 further includes a heat sink 5 for cooling the power modules 2a, 2b, and 2c. The power modules 2a, 2b, and 2c are mounted to the heat sink 5. The heat sink 5 includes a cooling chamber 50 that defines a coolant flow path. The cooling chamber 50 has an upper surface 50a and a lower surface 50b, both of which are cooled by the coolant flow.

[0033] In the following description, the power module has a rectangular cross section in the plane in which it extends. The external AC connector 21 and the external DC connectors 22, 23 extend from opposite sides of the rectangle. The control pins 25 are also aligned along opposite sides of the rectangle. The central area 20 of the power module is defined as the area around the intersection of the diagonals of the rectangle.

[0034] In the following description, the designations "longitudinal", "lateral" and "vertical" refer to the orientation of the switching cells according to the invention. The longitudinal direction corresponds to the direction in which the power modules 2a, 2b, 2c are positioned laterally in the common extension plane of the power modules. This longitudinal direction is parallel to the longitudinal axis L of the illustrated coordinate system L, V, T. The lateral direction corresponds to the direction in which each power module 2a, 2b, 2c extends between the side of the external AC connector 21 and the side of the external AC connectors 22, 23. This lateral direction is parallel to the lateral axis T of the coordinate system L, V, T and perpendicular to the longitudinal axis L. Finally, the vertical direction corresponds to the vertical axis V of the coordinate system L, V, T. The vertical axis V is perpendicular to the longitudinal axis L and to the lateral axis T. The vertical direction is perpendicular to the extension plane of the power modules 2a, 2b, 2c.

[0035] 2, the switching cell 1 includes a metal plate 4 that covers only a portion of the power modules 2a, 2b, 2c. As shown in FIG. 3, the metal plate extends between the control board 7 and the power modules 2a, 2b, 2c.

[0036] The metal plate 4 is attached to the heat sink 5, for example by means of screws, as disclosed below. In a variant, the metal plate can be attached to another support 5 of the power module.

[0037] A spring device 3 is mounted between the metal plate 4 and the power module. The spring device is, for example, fixed to the metal plate. The spring device presses the power module downwards towards the upper surface 50a of the heat sink. For example, the spring system includes a flexible blade 30a, 30b, 30c for each power module 2a, 2b, 2c, which is compressed between the metal plate 4 and the power module. The flexible blades may be fixedly attached to the metal plate in a preferred embodiment.

[0038] In a variant not disclosed here, the spring device 3 may comprise a single blade which presses downwards on the three power modules.

[0039] The blades may be arranged at an angle relative to the longitudinal direction, as shown in FIG.

[0040] The power modules 2a, 2b, 2c are pressed against the upper surface 50a of the heat sink, which improves cooling. Additionally, the thermal contact between the metal plate 4 and the power modules 2a, 2b, 2c via the spring system 3 provides additional calorie drainage to the power modules.

[0041] With reference to Fig. 2, the metal plate 4 comprises a body 40 extending along the longitudinal direction. This body comprises a transverse cutout 41. The cutout is adapted to form, for each power module, a clearance zone around the control pin 25, in which the power module is not covered by the metal plate. The metal plate 4 only locally covers the central region 20 of the power module.

[0042] 2, above each power module there are two cutouts on either longitudinal edge of the plate, laterally opposite each other. The cutouts 41 are arranged so that the lateral dimension of the metal plate is reduced in the central region 20 of the power module. The cutouts are typically U- or V-shaped.

[0043] The plate comprises at least one leg 42 which extends beyond the power module 2 in the extension plane of the power module. The leg comprises means 43 as through holes for attaching the metal plate 4 to the heat sink 5 by means of screws.

[0044] The clearance distance between the pins from the power module and the metal plate must be respected as the minimum distance in air between these two parts. This distance must be in the range of 2 mm to 6 mm, preferably 4 mm. The creepage distance through the non-conductive parts (through the power module) between the pins from the power module and the metal plate must be in the range of 3 mm to 7 mm, preferably 5 mm.

[0045] 5, the metal plate includes a dome 44 extending vertically from the upper surface of the main body 4a of the metal plate. The dome is used to hold the control panel 7.

[0046] In a preferred embodiment, the domes are aligned longitudinally. The domes are positioned longitudinally between the power modules. This positioning provides rigidity to the control panel to prevent deformation due to vibration.

[0047] In a preferred embodiment, the dome may also extend from the underside of the body portion 4b of the metal plate, so that the dome has a sufficient length to guide the screw through the metal plate.

[0048] 5 shows a specific embodiment in which the blade has a U-shape with a central arm 31 and two legs 32. A metal plate 4 presses downwards the tips of the central arms which approach each other along the longitudinal direction, so that the middle part of the central arm is pressed against the power module.

[0049] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. It is to be understood, therefore, that the invention is not to be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms have been employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. one power module (2) mounted on a support (5), the power module (2) extending in a plane, a spring device (3), a metal plate (4), A switching cell (1) for an automobile comprising at least The metal plate (4) presses the spring device (3) on the power module (2) downward in a vertical direction perpendicular to the plane, The metal plate (4) covers only a portion of the power module (2) on the plane. Switching cell (1).

2. The metal plate covers a central region of the power module in the plane. The switching cell of claim 1 .

3. the metal plate comprises at least one leg (42) extending beyond the power module (2) in the plane; said legs comprise at least one means (43) for attaching said metal plate (4) to said support (5); A switching cell according to claim 1 or 2.

4. The clearance distance between the pin extending from the power module and the metal plate is in the range of 2 mm to 6 mm, and is preferably 4 mm. A switching cell according to any one of claims 1 to 3.

5. The creepage distance between the pin extending from the power module and the metal plate is in the range of 3 mm to 7 mm, and is preferably 5 mm. A switching cell according to any one of claims 1 to 4.

6. The metal plate includes at least one dome (44) extending vertically from an upper surface of the metal plate. A switching cell according to any one of claims 1 to 5.

7. The switching cell includes at least two power modules (2A, 2B) arranged along a longitudinal direction in the plane, The dome (44) is positioned along the longitudinal direction between the power modules. A switching cell according to claim 6.

8. The spring device (3) is integrally formed with the metal plate (4). A switching cell according to any one of claims 1 to 7.

9. The spring device (3) comprises at least one blade (30) that presses the power module downward; The blade has a U-shape with a central arm (31) and two legs (32), The blade is configured such that when the metal plate (4) presses against the tip of the central arm, the middle part of the central arm (31) presses downward against the power module (2). A switching cell according to any one of claims 1 to 7.

10. The switching cell comprises at least two bus bars, each bus bar electrically connected to the power module, and at least one DC link capacitor electrically connected to the bus bars; The power module and the DC link capacitor are positioned side-by-side. A switching cell according to any one of claims 1 to 9.

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