Power converter, specifically configured for installation in a motor vehicle

Abstract

Power converter, in particular configured for installation in a motor vehicle. The invention relates to a power converter comprising: A capacitive filtering device (110), At least one power module connected to the capacitive filtering device by a positive busbar and a negative busbar, A control board disposed on the capacitive filtering device and / or the power module for controlling the power module, the control board including a mounting hole, A metallic heat sink housing the capacitive filtering device and the power module, and including a mounting stud extending between the positive busbar (121) and the negative busbar (122), the mounting stud including a cavity aligned with the mounting hole of the control board, A means for attaching the control board to the heat sink.An electrical insulation device (160) is interposed between the bus bars and the fixing block. (Figure 4)

Description

Title of the invention: Power converter, in particular configured for installation in a motor vehicle

[0001] The present invention relates to the field of electrical equipment, such as inverters, equipped with a power module and a capacitive filtering device, intended to be associated with an electrical machine, for example an electric or hybrid vehicle motor.

[0002] In an electric or hybrid motor vehicle, the electric motor system is powered by a high-voltage battery that enables the propulsion of the motor vehicle. More specifically, in order to control the electric motor that drives the vehicle's wheels, a power converter, such as an inverter, is used to convert the direct current voltage supplied by the high-voltage battery into alternating current voltage.

[0003] Such a power converter typically comprises a power module and a capacitive filtering device. The capacitive filtering device, also called a link capacitor and more commonly known by its English term "DC-link capacitor," smooths the DC voltage supplied to the power module. The power module is connected to the capacitive filtering device and generates an alternating voltage from the smoothed DC voltage to supply electrical energy to the electric machine. The connection between the capacitive filtering device and the power module is made by means of at least two busbars, specifically one positive and one negative busbar. For high power handling, one positive and one negative busbar per phase are required, i.e., six busbars in total.

[0004] For proper operation of the power module, the power module is located near the capacitive filtering device. The assembly is housed in a metallic enclosure, typically made of aluminum, called a heat sink, one of whose roles is to contribute to the thermal integrity of the converter components.

[0005] Prior art power converters generally have so-called multi-board architectures. They include a so-called PU (Power Unit) board for driving the power module on the one hand, and a so-called CU (Control Unit) board for controlling the overall operation of the converter (checking temperature data, transmitting signals, etc.) on the other. As a result, the so-called PU board is small in size and is simply attached to the power module.

[0006] However, the coexistence of these two cards requires additional parts to connect them, for example, ribbon cables clipped onto connectors and / or interconnect pins. This implies additional steps in the manufacturing process and generates some bulk in the product.

[0007] One solution is to use a larger control board that combines the functions and components of the so-called PU board and the so-called CU board. This type of control board is advantageous because there is no longer any interconnection between boards to be made.

[0008] However, because this control board is large, it is more sensitive to mechanical stresses and can suffer from vibrational resonance, particularly when used in the automotive sector. It is therefore essential to provide several mounting points for the control board distributed across its surface to avoid any large unsupported areas.

[0009] One of the particularly sensitive areas is located above the capacitive filtering device. However, as mentioned previously, to ensure optimal operation of the power module, it must be positioned close to the capacitive filtering device. Since it is difficult to create mounting points above the capacitive filtering device, this solution presents the problem of leaving a large area of ​​the control board unsupported. A necessary solution is to position a mounting block between the power module and the capacitive filtering device. But the increasing number of bus bars leaves even less space for placing a mounting block in this location.

[0010] Another issue in such a converter is electrical isolation. The mounting points for the control board are formed by the heatsink. In other words, protrusions on the heatsink form the mounting points, for example, cylindrical in shape, i.e., having an outer wall shaped like the lateral surface of a cylinder and an inner wall defining a cavity for inserting a mounting screw. Since the heatsink is grounded to the chassis, it must be positioned at a sufficient distance from the bus bars to prevent arcing. This necessitates placing mounting points near the capacitive filtering device to ensure proper support for the control board, but at a distance from the bus bars to maintain electrical isolation distances and counteract the effects of creepage lines.

[0011] The present invention falls within this context and aims to provide a suitable control board mounting system within a power converter, allowing for the attachment of a large control board in an environment constrained by the available space while meeting electrical insulation requirements.

[0012] To this end, the invention relates to a power converter, in particular configured to be installed in a motor vehicle, characterized in that it comprises: - A capacitive filtering device capable of smoothing a DC voltage from a DC voltage source, the capacitive filtering device being delimited by a casing, - At least one power module connected to the capacitive filtering device by a positive busbar and a negative busbar, the busbars extending along a first horizontal axis, the power module being capable of generating an alternating voltage from the smoothed direct current voltage, and vice versa, - A control card mounted on the capacitive filtering device and / or the power module, intended to control the power module, the control card including a mounting hole, - A metallic heat sink forming a housing for the capacitive filtering device and the power module, and comprising a mounting stud extending along a first vertical axis between the positive busbar and the negative busbar, the mounting stud comprising an external wall and an internal wall delimiting a cavity at the mounting hole of the control board, - A means of attaching the control board to the heatsink arranged through the mounting hole and the cavity of the mounting stud, - An electrical insulation device, preferably made of plastic, inserted between the bus bars and the fixing point.

[0013] Thanks to these features, it is possible to mount a large control board in a highly compact power converter while protecting it from the mechanical stresses to which it is subjected. Furthermore, despite the limited free space available in such a power converter, the invention addresses the issue of electrical insulation between components and ensures that the necessary insulation distances are maintained between the mounting block and the positive and negative bus bars adjacent to the mounting block. The result is a compact high-voltage power converter that respects insulation distances.

[0014] According to an optional feature of the invention, the electrical insulation device forms an enclosure with an internal dimension greater than the external width of the mounting stud. In addition to surrounding the mounting stud to form a shield between the bus bars and the fixing post, this feature facilitates the insertion of the electrical insulation device around the fixing post.

[0015] According to an optional feature of the invention, the outer wall of the fixing block is generally cylindrical in shape and the casing of the electrical insulation device is cylindrical, the inner dimension of the casing being its diameter.

[0016] According to an optional feature of the invention, the electrical isolation device has an upper end connected to a lower surface of the control board. In such a variant, the electrical isolation device is connected to the control board. It is installed at the same time as the control board is placed on the capacitive filtering device and / or the power module. There are no additional parts to handle, and the electrical isolation device is inserted around the mounting stud when the control board is installed.

[0017] According to an optional feature of the invention, the electrical isolation device is integral with the housing of the filtering device. In such a variant, the electrical isolation device is connected to the capacitive filtering device. When the capacitive filtering device is installed in the heat sink, the protrusion forming the electrical isolation device surrounds the mounting stud, thereby providing protection and extending the isolation distance between the bus bars and the mounting stud.

[0018] The housing of the filtering device is, for example, made of plastic.

[0019] According to an optional feature of the invention, the power module being Housed in a casing, the electrical isolation device is integral to the power module casing. In this variant, the electrical isolation device is connected to the power module. As before, when the power module is installed in the heatsink, the electrical isolation device is positioned around the mounting stud, between the stud and the bus bars.

[0020] The power module housing is for example made of plastic.

[0021] According to an optional feature of the invention, the outer wall of the fixing block comprises a first flat, and preferably a second flat extending on either side of the cavity.

[0022] According to an optional feature of the invention, the outer wall comprises a third flat, and preferably a fourth flat, distinct from the first and second flats, extending on either side of the cavity.

[0023] The presence of one or more flat surfaces on the outer wall of the mounting block allows its cross-section to be reduced. This results both in an increased distance between the outer wall of the mounting block and the adjacent busbar and in easier insertion of the electrical insulation device around the mounting block, despite the existence of variation in the cross-section of the fixing block due to tolerances associated with the manufacturing process.

[0024] The invention also relates to a motor vehicle comprising such a power converter.

[0025] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given by reference to the accompanying schematic drawings on the other hand, in which:

[0026] [Fig-1] represents a view of a heat sink integrating a power module of the power converter according to the invention,

[0027] [Fig.2] represents a view of the heat sink of [Fig.1] also incorporating the capacitive filtering device,

[0028] [Fig.3] shows a view of the heat sink of [Fig.2] which also incorporates the control board,

[0029] [Fig.4] shows a view of the housing of the capacitive filtering device,

[0030] [Fig.5] shows a view of an embodiment of a mounting block for the power converter according to the invention,

[0031] [Fig.6] schematically represents a cross-sectional view of a mounting block of the power converter control board of the invention with two variants of electrical isolation device.

[0032] The features, variants, and different embodiments of the invention, as described or as they will be presented in the detailed description that follows, can be combined in various ways, provided that 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.

[0033] For the sake of clarity, the same elements are designated by the same references in the different figures.

[0034] Before detailing the principle of the invention, the main elements of the power converter 100 will be introduced on the basis of figures 1 to 3.

[0035] Fig. 1 represents a view of a heat sink integrating a power module of the power converter according to the invention.

[0036] The power converter 100 according to the invention is specifically configured for installation in a motor vehicle. The power converter 100 includes a metallic heat sink 140. As will be seen in the following figures, The metallic heat sink 140 forms a housing for a capacitive filtering device and the power module 120. A control board 130 (not shown in [Fig. 1]) is then mounted on the capacitive filtering device 110 and / or the power module 120 to control the power module 120. The capacitive filtering device 110 is capable of smoothing a DC voltage from a DC voltage source. The power module 120 is capable of generating an AC voltage from the smoothed DC voltage, and vice versa.

[0037] We take as an arbitrary reference the fact that the power module 120 extends in a horizontal plane, which is also the main plane along which the power converter extends.

[0038] The metal heat sink 140 includes a mounting stud 141 extending along a first vertical axis Z, perpendicular to the previously mentioned horizontal plane. It can already be noted that the mounting stud 141 comprises an outer wall 142 and an inner wall 143 defining a cavity 144. The mounting stud 141, detailed below, serves to allow the control board 130 to be attached to the metal heat sink 140.

[0039] Figure 2 shows a view of the heat sink of Figure 1, which also incorporates the capacitive filtering device 110. The capacitive filtering device 110 is enclosed by a plastic housing 111. Busbars 121, 122 extend along a first horizontal axis X, perpendicular to the first vertical axis Z, and parallel to the horizontal plane, from the capacitive filtering device 110 to the power module 120. The power module 120 is connected to the capacitive filtering device 110 by at least the positive busbar 121 and at least the negative busbar 122. The power module is generally located close to the capacitive filtering device 110 to allow their connection in a small space, thus creating a compact power converter.

[0040] As shown in [Fig. 2], the mounting post 141 extends between the positive busbar 121 and the negative busbar 122. In other words, on each side of the mounting post 141 is a busbar: the positive busbar on one side and the negative busbar on the other. As mentioned in the introduction, the metal heat sink 140 is grounded to the chassis. The busbars are not electrically insulated. Without taking special measures, there is a risk of electrical interference between the busbars and the mounting post due to the short distance between them. This interference is undesirable and can damage the converter. The power converter of the invention provides a solution, explained below, which allows for adequate creepage and clearance distances between the mounting post and each busbar adjacent to the mounting post.

[0041] The clearance distance corresponds to the shortest distance in air separating the electrical components, while the leakage distance corresponds to the shortest distance measured along an insulating surface arranged between these components. These distances are governed, in particular, by industry standards such as IEC 60664. Typically, the higher the operating voltage of the components, the greater the leakage and clearance distances must be to prevent arcing between these components. The converter of the invention solves the problem of having to place mounting pads near the capacitive filtering device to ensure good support for the control board, but at a distance from the bus bars to maintain electrical insulation distances and counteract the effects of creepage distances.

[0042] Figure 3 shows a view of the heat sink of Figure 2, which also incorporates the control board 130. In this non-limiting example, the control board 130 is positioned on the power module 120 and the capacitive filtering device 110. It completely covers the power module 120 and partially covers the capacitive filtering device 110. Other configurations are possible without departing from the scope of the invention: the control board 130 can cover either the power module and the capacitive filtering device, or the control board can only partially cover one of them. Given the trend towards combining the functions of a CU board and a PU board on the same control board, it follows that the control board has a certain size that necessitates at least partial coverage of the power module and the capacitive filtering device.

[0043] The control board 130 includes a mounting hole 131 to allow its attachment to the metal heat sink.

[0044] The cavity 144 of the mounting stud is located opposite the mounting hole 131 of the control board 130. In other words, the cavity 144 is directly opposite the mounting hole 131 of the control board 130. The power converter 100 includes a means 150 for attaching the control board 130 to the heatsink 140. This means is positioned through the mounting hole 131 and the cavity 144 of the mounting stud 141. The means 150 may be a screw. The means 150 passes through the mounting hole 131 of the control board 130 and is inserted into the cavity 144 of the mounting stud. Thus, the control board 130 is rigidly attached to the metal heatsink. The power converter 100 may further include additional fixing devices 151, for example arranged at the four corners of the control board 130, for fixing the control board to the heat sink.

[0045] In summary, the power converter 100 includes the capacitive filtering device 110 capable of smoothing a DC voltage from a voltage source The power module 120 is connected to the capacitive filtering device 110 by the positive busbar 121 and the negative busbar 122. It can be noted that the converter 100 can include several power modules.

[0046] The power converter 100 includes the metal heat sink 140 which houses the capacitive filtering device 110 and the power module 120. It also includes the control board 130 for controlling the power module 120. The control board 130 is attached to the metal heat sink 140 by means of the mounting stud 141 of the heat sink 140, for example by a screw 150 which passes through the hole 131 of the control board and is inserted into the cavity 144 of the mounting stud 141.

[0047] In the prior art, and given the compactness of the power converters, electrical interference is possible between the bus bars 121, 122 on the one hand and the mounting block on the other. Indeed, the distance between each bus bar and the mounting block may be too short and cause this electrical interference.

[0048] According to the invention, the power converter 100 includes an electrical insulation device 160, made of electrically insulating material, preferably plastic, interposed between the bus bars 121, 122 and the fixing block 141. The electrical insulation device 160 is visible in [Fig.2].

[0049] Thanks to this feature, the power converter of the invention makes it possible to fix the control board in a compact environment while ensuring the distances required to increase clearance and leakage distances in order to meet electrical insulation requirements.

[0050] The electrical insulation device 160 is disposed on one side between the omnibus bar 121 and the fixing stud 141 and on the other side between the omnibus bar 122 and the fixing stud 141. The electrical insulation device 160 is interposed between the omnibus bar adjacent to the fixing stud and the fixing stud and aims to lengthen the insulation distance between the omnibus bar and the fixing stud.

[0051] The electrical insulation device 160 surrounds the mounting stud 141, thus blocking any direct line between the adjacent busbar and the mounting stud. Thanks to the electrical insulation device 160, the insulation distances between the mounting stud and the adjacent busbars are increased. The path to be traveled between each busbar and the mounting stud must bypass the electrical insulation device 160, as will be explained in the detailed description of the electrical insulation device variants.

[0052] Figure 4 shows a view of the housing 111 of the capacitive filtering device 110. The bus bars 121, 122 extending along the X-axis are visible. In this embodiment, the electrical isolation device 160 is integral with the plastic housing of the filtering device. The electrical isolation device 160 can The electrical isolation device 160 can be seen as an extension of the housing 111 of the capacitive filtering device 110, or it can be an additional part added to and connected to the housing 111 of the capacitive filtering device 110. The electrical isolation device 160 has a hollow shape. In other words, the electrical isolation device 160 includes a through-hole extending along the Z-axis. The through-hole allows the electrical isolation device 160 to fit around the mounting stud 141 and provides an opening for the insertion of the mounting means 150 into the mounting stud in order to attach the control board to the mounting stud 141.

[0053] The electrical insulation device forms an enclosure with an internal dimension 161 greater than an external width 145 of the mounting stud 141. This internal dimension 161 corresponds to the internal dimension of the penetration. It can, for example, be the width of a section perpendicular to the Z-axis of the penetration if the penetration has a rectangular or square cross-section.

[0054] In [Fig. 4], the electrical isolation device 160 is associated with the capacitive filtering device 110. Alternatively, the electrical isolation device 160 can be associated with the power module 120. This variant is not shown, but based on a principle analogous to that described previously, it is understood that, since the power module is housed in a casing, the electrical isolation device is connected to the power module casing. In this case, the electrical isolation device can be an extension of the power module casing or it can be an additional element added and fixed to the power module casing, in order to form a through-hole arranged around the mounting stud 141 of the metal heat sink 140, on the same principle as that explained above for the capacitive filtering device.

[0055] Figure 5 shows a view of an embodiment of a mounting block 141 of the power converter according to the invention. In this embodiment, the mounting block has a squircle-shaped cross-section in the PI plane perpendicular to the Z-axis. A squircle is a mathematical shape intermediate between a square and a circle; it is a contraction of "square" and "circle." It is also referred to as a rounded square or a square with the same curvature at each of its vertices. Alternatively, the cross-section of the mounting block in the PI plane can be circular or polygonal, for example, rectangular or square. In the case of a squircle-shaped cross-section, the outside width 145 of the mounting block is the distance between two opposite sides of the squircle. In the case of a circular cross-section, the outside width 145 is the diameter of the cross-section.

[0056] According to an optional feature of the invention, the outer wall of the mounting block comprises a first flat 146, and preferably a second flat 147, both extending on either side of the cavity 144. In other words, the flat(s) is / are located on the outer wall of the mounting block and extends / extends onto the minus a portion of its height, measured from its upper surface. The presence of a flat 146 reduces the cross-section of the mounting block. The presence of flats 146 and 147 opposite each other with respect to the Z-axis further reduces the cross-section of the mounting block.

[0057] In another embodiment, the outer wall may include a third flat, and preferably a fourth flat, distinct from the first and second flats, extending on either side of the cavity 144. The third and fourth flats may be identical to the first and second flats; they are offset around the Z-axis relative to the positioning of the first and second flats. The third and fourth flats reduce the cross-section of the mounting stud.

[0058] The flats on the mounting block allow the dimension of the mounting block to be reduced along a section perpendicular to the Z-axis. In other words, machining the flats reduces the width of the mounting block (or the diameter in the case of a circular section of the mounting block). This reduction in width has a dual effect: it increases the distance between the mounting block and the adjacent busbar, and it facilitates the insertion of the mounting block into the through-hole of the electrical isolation device.

[0059] Figure 6 schematically represents a cross-sectional view of a mounting block 141 of the control board 130 of the power converter of the invention with two variants of the electrical isolation device. One variant is illustrated on the left side of the figure and another variant is illustrated on the right side of the figure.

[0060] In what follows, we will refer to an external wall of the mounting block that is generally cylindrical in shape, in which case the casing of the electrical insulation device is cylindrical, and the internal dimension of the casing is its diameter. However, the same principle applies in the case of an external wall of the mounting block with a polygonal cross-section, for example, rectangular or square.

[0061] In the variant illustrated on the left of the figure, the electrical isolation device 160 is arranged between the busbar adjacent to the mounting stud and the mounting stud. It may be an extension of the capacitive filtering device or of the power module as explained previously.

[0062] In the variant illustrated on the right of the figure, the electrical isolation device 160 has an upper end 162 connected to a lower surface 132 of the control board 130. In this variant, the electrical isolation device 160 is fixed to the control board 130, at its lower surface 132. When the control board 130 is put in position to be fixed to the metal heat sink, the electrical isolation device 160 is put in position around the fixing pad, it surrounds the latter so as to form an envelope all around the upper part of the fixing pad.

[0063] Regardless of the variant, the electrical isolation device 160 is interposed between a bus bar close to the fixing stud and the fixing stud.

[0064] The busbar 121 is a positive busbar; it can be high voltage, for example between 400 and 800V. The busbar 122 is a negative busbar. The heat sink 111 is metallic.

[0065] The dashed arrows represent the creepage distance obtained between the bus bars and the heat sink mounting stud. It can be seen that, thanks to the insertion of the electrical isolation device, the creepage distance is greater than without the electrical isolation device. In other words, the electrical isolation device 160 makes it possible to increase the isolation distance between a bus bar and the mounting stud, even though these two elements are adjacent and physically separated by a small distance. This is referred to as an extended creepage distance. The electrical isolation device is made of an electrically insulating material, preferably plastic. It forms a shield between the mounting stud and the bus bars 121, 122.

[0066] Thanks to the invention, it is thus possible to integrate a large control board into a compact power converter and, despite everything, to maintain the required isolation distances between the fixing block and the bus bars adjacent to the fixing block arranged between a positive bus bar and a negative bus bar.

[0067] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, the features of different embodiments of the invention can be combined to carry out the invention, provided that these embodiments are not incompatible with each other.

Claims

Demands

1. A power converter (100), in particular configured for installation in a motor vehicle, characterized in that it comprises: - A capacitive filtering device (110) capable of smoothing a DC voltage from a DC voltage source, the capacitive filtering device (110) being delimited by a housing (111), - At least one power module (120) connected to the capacitive filtering device (110) by a positive busbar (121) and a negative busbar (122), the busbars (121, 122) extending along a first horizontal axis (X), the power module (120) being capable of generating an AC voltage from the smoothed DC voltage, and vice versa, - A control card (130) disposed on the capacitive filtering device (110) and / or the power module (120) and intended to control the power module (120), the card control (130) including a fixing hole (131),- A metallic heat sink (140) forming a housing for the capacitive filtering device (110) and the power module (120), and comprising a mounting stud (141) extending along a first vertical axis (Z) between the positive busbar (121) and the negative busbar (122), the mounting stud (141) comprising an outer wall (142) and an inner wall (143) defining a cavity (144) aligned with the mounting hole (131) of the control board (130), - A means for attaching the control board (130) to the heat sink (140) disposed through the mounting hole (131) and the cavity (144) of the mounting stud (141), - An electrical insulation device (160), preferably made of plastic, interposed between the busbars (121, 122) and the mounting stud (141).,

2. Power converter (100) according to claim 1, wherein the electrical insulation device (160) forms an enclosure of internal dimension (161) greater than an external width (145) of the fixing block (141).

3. Power converter (100) according to claim 2, wherein the outer wall (142) of the mounting block (141) is generally cylindrical in shape and the enclosure of the electrical insulation device (160) is cylindrical, the inner dimension of the enclosure being its diameter.

4. Power converter (100) according to any one of claims 1 to 3, wherein the electrical isolation device (160) has an upper end (162) connected to a lower surface (132) of the control board (130).

5. Power converter (100) according to any one of claims 1 to 3, wherein the electrical isolation device (160) is integral with the housing (111) of the filtering device (110).

6. Power converter (100) according to any one of claims 1 to 3, the power module (120) being housed in a casing, in which the electrical isolation device (160) is integral with the casing of the power module.

7. Power converter (100) according to any one of claims 1 to 6, wherein the outer wall (142) of the mounting block (141) comprises a first flat (146), and preferably a second flat (147) extending on either side of the cavity (144).

8. Power converter (100) according to claim 7, wherein the outer wall (142) comprises a third flat, and preferably a fourth flat, distinct from the first and second flats, extending on either side of the cavity (144).

9. Motor vehicle comprising a power converter (100) according to any one of claims 1 to 8.

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