Assembly comprising an electrical transformer and additional means of heat dissipation

Abstract

Assembly (100) for an electrical circuit comprising: - An electrical transformer (20) comprising a magnetic core (22) and windings (21), the windings (21) being wound around the magnetic core (22), and - A heat sink (40), characterized in that the assembly (100) comprises a heat-conducting element (30), this element (30) being fixed on one side to at least one winding (21) of the transformer (20) and on the other side to the heat sink (40). [Fig. 2]

Description

Title of the invention: Assembly comprising an electrical transformer and additional heat dissipation means

[0001] The present application refers to an assembly comprising an electrical transformer, this transformer comprising a magnetic core and windings, the windings being wound around the magnetic core, and a heat sink, this assembly being able to be used within a DC-DC voltage converter.

[0002] Cooling such a transformer is essential to ensure optimal performance during operation. Traditionally, the transformer's magnetic core is in contact with a heat sink and conducts heat from the windings to this heat sink. This solution is imperfect because it favors the cooling of the windings physically closest to the point of contact between the magnetic core and the heat sink.

[0003] There is a need to improve such an assembly.

[0004] The invention aims to meet this need and achieves this, in one aspect, by means of an assembly for an electrical circuit comprising

[0005] -An electrical transformer comprising a magnetic core and windings, the windings being wound around the magnetic core, and

[0006] -A heat sink,

[0007] Characterized in that the assembly comprises a heat-conducting element, this element being fixed on one side to at least one winding of the transformer and on the other side to the heat sink.

[0008] Thanks to this heat-conducting element, it is possible to achieve a more efficient transfer of heat between the at least one winding to which the heat-conducting element is attached and the heat sink, and thus improve the overall performance of the assembly.

[0009] By heat sink we mean a part, which may be metallic, that conducts heat and is in contact with the ambient air, or the surface of a duct in a cooling fluid circuit.

[0010] The heat-conducting element can be attached to all the windings of the transformer.

[0011] The heat-conducting element can be a plate, for example a metal plate, in particular made of aluminium, copper or steel.

[0012] Alternatively, the heat-conducting element can be a ceramic plate or a graphite plate.

[0013] Alternatively, the component may comprise metal wires and be in the form of a flexible grid. For example, the metal wires may be single-strand or multi-strand copper wires.

[0014] The heat-conducting element may include a fold.

[0015] The organ may alternatively comprise several folds. In particular, the organ may comprise two folds, or even three folds.

[0016] The fold(s) can improve the resistance of the component to external disturbances, particularly vibrations. The fold(s) can also help to absorb any play that occurs during assembly or during thermal expansion of the components.

[0017] The heat-conducting element may include a U-shaped fold; such a fold improves the flexibility of the heat-conducting element and reduces the risk of degradation of the element itself or of degradation of its attachment to at least one winding or to the heat sink.

[0018] The heat-conducting element can be attached to at least one of the transformer windings by means of an adhesive material, for example, an adhesive thermal interface material. In known examples, this material can be a thermal adhesive, or one or more thermal pads.

[0019] The application of the adhesive material to the heat-conducting element can define a zone for fixing the element to the transformer.

[0020] According to one embodiment, the adhesive material can be applied continuously to the component within the area of ​​attachment of the component to the transformer.

[0021] Alternatively, the adhesive material can be applied non-continuously within the area of ​​attachment of the component to the transformer, for example in the form of points distributed homogeneously or not within the area.

[0022] The heat-conducting element can be fixed to the heat sink by at least one of its ends.

[0023] The heat-conducting element can be fixed to the heat sink by means of an adhesive material, for example an adhesive thermal interface material.

[0024] Alternatively, the heat-conducting element can be attached to the heat sink by screwing, brazing, or welding. In this case, a means of electrically isolating the heat-conducting element from the heat sink can be provided.

[0025] The heat sink may include a cavity, one end of the heat-conducting element attached to the heat sink being disposed in the cavity, this cavity being filled with a potting material.

[0026] The potting material may include thermal conduction properties, for example include a thermal interface material.

[0027] The magnetic core of the transformer can be fixed to the heat sink, for example by means of an adhesive thermal interface material.

[0028] The heat-conducting element and the magnetic core can be attached to the heat sink by the same means.

[0029] The assembly may include two heat-conducting elements, each of which may include all or part of what has been described previously, these elements being identical or different.

[0030] In this case, the heat-conducting elements can be arranged symmetrically with respect to a central axis of the transformer's magnetic core.

[0031] The transformer windings can be electrical wires and / or flat conductors.

[0032] The invention also relates, according to one of its aspects, to a DC-DC voltage conversion circuit intended for use in a vehicle comprising

[0033] - A first interface intended to be connected to a DC voltage source,

[0034] - A second interface intended to be connected to an energy storage unit electric,

[0035] - An assembly comprising all or part of what has been described previously, and

[0036] - A first and a second switching circuit, each comprising at least a switching bridge comprising switches arranged on either side of a midpoint, the first circuit and the second switching circuit being connected on the one hand to the first interface, respectively to the second interface, and on the other hand to respective windings of the transformer by the midpoint of at least one switching bridge.

[0037] The switches of the switching circuits may be semiconductor controllable switches, including for example N-type MOSFET transistors, bipolar transistors, or including IGBT transistors.

[0038] The invention will be better understood by reading the following description of non-limiting examples of its implementation. Brief description of the figures

[0039] Figure 1 is a schematic representation of an example of a DC-DC voltage converter comprising an assembly according to the invention,

[0040] Figure 2 is a schematic representation of a first example of the implementation of an assembly according to the invention,

[0041] Figure 3 is a schematic representation of a second example of an implementation of an assembly according to the invention,

[0042] Figure 4 is a schematic representation of a third example of an implementation of an assembly according to the invention, and

[0043] Fig. 5 is a schematic representation of a fourth example of implementation of an assembly according to the invention. Detailed description of the invention

[0044] Figure 1 shows an electrical diagram of a DC-DC voltage converter 1, for example intended to be integrated into an electric vehicle.

[0045] This converter 1 includes a first interface 10 comprising two terminals. This interface 10 is suitable for being connected to a DC voltage source, for example from a rectifier device.

[0046] The terminals of the first interface 10 are connected to a respective switch of two switching bridges 12, 13 of a switching circuit 11. The switches of the same switching bridge 12, 13 are arranged on either side of a midpoint 12a, 13a, these midpoints being connected to primary windings 21a of the electrical transformer 20.

[0047] The converter 1 also includes a second interface 17, comprising two terminals. This interface 17 is suitable for connection to an electrical energy storage unit.

[0048] The terminals of interface 17 are connected to a respective switch of two switching bridges 15, 16 of a switching circuit 14. The switches of the same switching bridge 15, 16 are arranged on either side of a midpoint 15a, 16a, these midpoints being connected to secondary windings 21b of the electrical transformer 20.

[0049] In this example, the switching circuits 11 and 14 of the DC-DC voltage converter 1 comprise controllable semiconductor switches, in particular N-type MOSFETs. Thus, the voltage converter 1 is capable of transferring energy from the first interface 10 to the second interface 17, with the switching circuit 11 acting as an inverter and the circuit 14 acting as a rectifier. The voltage converter 1 is also capable of transferring energy from the second interface 17 to the first interface 10, with the switching circuit 11 acting as a rectifier and the switching circuit 14 acting as an inverter.

[0050] Figure 2 shows a first example of the implementation of an assembly 100, comprising the electrical transformer 20 of the DC-DC voltage converter 1 of Figure 1.

[0051] In this first example and in all the following ones, the windings 21 of the electrical transformer can be either the primary windings 21a and secondary windings 21b of the converter circuit 1. Each winding 21 of the transformer 20 can be for example one or more electrical wires and / or flat conductors.

[0052] The transformer 20 of the assembly 100 also includes a magnetic core 22. The windings 21 are wound around the magnetic core 22. This magnetic core 22 may be composed of one or more sub-cores, include one or more air gaps, and be composed mainly of ferromagnetic ceramic (or ferrite). In the example shown, the windings 21 are wound around a portion of the core 22, which is not shown in its entirety.

[0053] This assembly 100 includes in particular a heat sink 40. In the example shown in [Fig.2], the transformer 20 and the heat sink 40 are fixed to each other by a fixing material 50.

[0054] The heat sink 40 can be a metallic part in contact with the ambient air, or the surface of a duct in a cooling fluid circuit.

[0055] In this example, the fastening material 50 can be a thermal interface material (or "TIM") improving the thermal conductivity between the magnetic core 22 of the transformer 20 and the heat sink 40, and having fastening properties. This material can be, in a known example, a thermal adhesive, but can also be a thermal pad.

[0056] The assembly 100 also includes a heat-conducting element 30. This element 30 is in this example a metal plate, for example made of aluminum, copper or steel.

[0057] In the example shown, an adhesive material 37 is applied to the component 30, defining a fixing zone 38 of the component 30 to the transformer 20. In this example, the material 37 is applied continuously along the fixing zone 38. In [Fig. 2], the component 30 is fixed to the entirety of the windings 21 of the transformer 20. In the example of [Fig. 2], a first end 31 of the component 30 is included in the fixing zone 38.

[0058] For example, the adhesive material 37 is a thermal interface material identical or different from the fixing material 50. This material 37 is ideally electrically non-conductive.

[0059] The heat-conducting element 30 of [Fig.2] is also fixed to the heat sink, more particularly by the same fixing material 50 which allows the magnetic core 22 to be fixed to the heat sink 40. In particular, a second end 32 of the heat-dissipating element is fixed to the heat sink 40 by the fixing material 50.

[0060] Attaching the heat-conducting element 30 on one side to the windings 21 of the transformer 20 and on the other side to the heat sink 40 improves the transfer of heat from the windings 21 to the heat sink 40,

[0061] More particularly, the presence of this heat-conducting element 30 makes it possible to connect more efficiently, to the heat sink, the windings 21 furthest from the heat sink 40. In particular, it is possible to choose a heat-conducting element 30 having a better heat conduction capacity than the magnetic core 22.

[0062] In the example shown in [Fig.2], the heat-conducting element 30 includes folds 33, 34.

[0063] The first fold 33 of the component 30 forms a U-shape, meaning that the portions of the heat-conducting component 30 around this fold 33 are parallel, or nearly parallel. This fold 33 is located between the attachment zone 38 of the component 30 to the transformer 20 and the attachment zone of the component 30 to the heat sink 40.

[0064] This fold 33 forming a U shape makes it possible to ensure that the attachment between the member 30, the windings 21 and the heat sink 40 is more robust to external disturbances, for example vibrations, thanks to the deformation of the heat-conducting member 30 around this fold 33 during said disturbances.

[0065] The second fold 34 makes it possible to delimit the contact area of ​​the heat element 30 with the heat sink 40 through the fixing material 50. In the example of [Fig.2], this fold 34 makes a right angle, or almost a right angle.

[0066] A second example of the implementation of an assembly 100, comprising the electrical transformer 20 of the DC-DC voltage converter 1 of [Fig.1], has been shown in [Fig.3].

[0067] In the example of [Fig.3], the transformer 20 is identical to the transformer 20 of [Fig.2].

[0068] In the embodiment of assembly 100 in [Fig. 3], the heat-conducting element 30 is a metal plate, without any folds. In this example, the element has, in the view shown in [Fig. 3], a general shape of I.

[0069] In the example of [Fig.3], the heat-conducting element 30 is fixed to all the windings 21 of the transformer 20 by an adhesive material 37 defining a fixing zone 38 of the element 30 to the transformer 20. In particular, an end 31 of the element 30 is included in the fixing zone 38.

[0070] The heat sink 40 of the assembly 100 includes in [Fig. 3] a cavity 41 in which a part of the member 30 is disposed, particularly the end 32 of the member 30. The cavity 41 is filled with a potting material, which makes it possible to fix the heat-conducting member 30 to the heat sink 40. In the example shown, the potting material is identical to the fixing material 50 used to fix the magnetic core 22 to the heat sink 40.

[0071] A third example of the implementation of an assembly 100, comprising the electrical transformer 20 of the DC-DC voltage converter 1 of [Fig.1], has been shown in [Fig.4].

[0072] The transformer 20 shown in [Fig.4] is fixed to a surface not shown in the figure by its magnetic core 22, for example the transformer 20 is fixed to the surface of another heat sink, or to the surface of a housing in which the converter 1 of [Fig.1] is housed.

[0073] In the example of [Fig. 4], the assembly 100 comprises a heat-conducting element 30. The element 30 is a metal plate. In this example, the element has a general crenellated shape in the view shown in [Fig. 4].

[0074] An adhesive material 37 is applied to the member 30, defining a fixing area 38 of the member 30 to the transformer 20. More specifically in the example shown, the member 30 is fixed to the set of windings 21 of the transformer 20.

[0075] In the example shown in [Fig.4], the fixation area 38 of the organ 30 is located in a central area of ​​the organ 30. More specifically, neither the end 31 nor the end 32 are included in the fixation area 38.

[0076] The component 30 is fixed to the heat sink 40 by a fixing material 50, for example a "TIM". More particularly, the two ends 31 and 32 of the component 30 are fixed to the heat sink 40.

[0077] The organ 30 comprises two folds 33. These two folds 33 are U-shaped and arranged on either side of the heat-conducting organ 30. In this example, the folds are located around the areas of attachment of the organ 30 to the heat sink 40.

[0078] A fourth example of an assembly 100 comprising the transformer 20 of the DC-DC voltage converter 1 of [Fig.1] has been shown in [Fig.5].

[0079] The transformer 20 shown in [Fig.4] is not fixed to the heat sink 40, but is fixed to a surface not shown in the figure by its magnetic core 22.

[0080] In the example of [Fig.5], the assembly 100 comprises two heat-conducting elements 30. The elements 30 are arranged on either side of the windings 21 of the transformer 20 with respect to a central axis X of the magnetic core 22.

[0081] In the example shown, the components 30 pass through the magnetic core 22 of the transformer 20.

[0082] In this example, the components 30 are fixed to the heat sink by means of a fastening means 50, which may be a "TIM". In particular, the ends 32 of the components 30 are fixed to the heat sink 40. The components 30 are also fixed to a respective winding by means of an adhesive material 37 defining a fixing zone 38 of the organs 30. The adhesive materials 37 may be identical between the two organs 30 and may be identical or different from the means of fixation 50.

[0083] The members 30 of [Fig.5] are in this example identical and arranged symmetrically with respect to the central axis X of the magnetic core 22 of the transformer 20. The two members 30 comprise a first fold 33 in the shape of a U, and a second fold 34 at a right angle, or almost right angle, allowing the area of ​​attachment of the members 30 with the heat sink 40 to be delimited by the attachment means 50.

[0084] The invention is not limited to what has been described with reference to the figures.

[0085] In the embodiments of assembly 100 shown in Figures 2 to 4, the components 100 may not be attached to all the windings. For example, component 30 may be attached to only one winding 21 of the transformer 20.

[0086] In the embodiment examples of assembly 100 shown in Figures 2 to 5, the heat-conducting elements can be a ceramic or graphite plate.

[0087] In the embodiments of assembly 100 shown in Figures 2 to 5, the heat-conducting elements can be in the form of a flexible grid comprising metal wires, for example single-strand or multi-strand copper wires.

[0088] In the embodiment examples of assembly 100 shown in Figures 2, 4 or 5, the heat-conducting elements may include an additional fold, for example similar to folds 33.

[0089] In the example shown in [Fig.2], the organ 30 may only include the fold 34. In this example, the organ 30 may have a general I-shape between the fold 34 and its end 31.

[0090] In the example shown in [Fig.3], the organ 30 may include one or more folds.

[0091] In the examples shown in Figures 2 and 5 the heat sink 40 may include a cavity, the organ 30 may have its end 32 disposed within this cavity, this cavity being filled with a potting material.

[0092] In the example shown in [Fig. 4], the heat sink 40 may comprise at least one cavity, the component 30 having its end 31 and / or its end 32 disposed within this at least one cavity, this at least one cavity being filled with a potting material.

[0093] The folds 33, 34 of the organs 30 may have shapes other than U-shaped or right-angled. A V-shaped fold may be envisaged, such that the parts of the organ 30 around the fold are not parallel.

[0094] It is also possible to consider, in the case where the magnetic core 21 of the transformer 20 and the heat-conducting element 30 are both fixed to the heat sink 40, using a first fixing material 50 between the magnetic core 21 and the heat sink 40 and a second fixing material different from the first to achieve the fixing of the heat-conducting element 30 to the heat sink 40.

[0095] The assembly 100 shown in [Fig.5] may include two heat-conducting elements 30, these two heat-conducting elements 30 being different and / or arranged asymmetrically with respect to the central axis X of the magnetic core 22.

[0096] The adhesive material 37 can be applied non-continuously along the fixing area 38 of the member 30 to the transformer 20. For example, the material 37 can be applied to the member 30 in the form of points distributed homogeneously or not within the fixing area 38.

Claims

Demands

1. Assembly (100) for an electrical circuit comprising - An electrical transformer (20) comprising a magnetic core (22) and windings (21), the windings (21) being wound around the magnetic core (22), and - A heat sink (40), Characterized in that the assembly (100) comprises a heat-conducting element (30), this element (30) being fixed on one side to at least one winding (21) of the transformer (20) and on the other side to the heat sink (40).

2. Assembly (100) according to any one of the preceding claims, characterized in that the heat-conducting element (30) is fixed to all windings (21) of the transformer (20).

3. Assembly (100) according to any one of the preceding claims, characterized in that the heat-conducting element (30) is a plate, for example a metal plate.

4. Assembly (100) according to any one of claims 1 to 2, characterized in that the heat-conducting element (30) comprises metal wires and is in the form of a flexible grid.

5. Assembly (100) according to any one of claims 3 or 4, characterized in that the heat-conducting element (30) comprises at least one fold (33, 34).

6. Assembly (100) according to any one of the preceding claims, characterized in that the heat-conducting element (30) is fixed to at least one of the windings (22) of the transformer by an adhesive material (37), for example an adhesive thermal interface material.

7. Assembly (100) according to any one of the preceding claims, characterized in that the heat-conducting element (30) is fixed to the heat sink (40) by at least one of its ends (31, 32).

8. Assembly (100) according to the preceding claim, characterized in that the heat sink (40) comprises a cavity (41), one of the ends (31, 32) of the heat-conducting element (30) fixed to the heat sink (40) being disposed in the cavity (41), this cavity being filled with a potting material.

9. Assembly (100) according to any one of the preceding claims, characterized in that the magnetic core (22) of the transformer is fixed to the heat sink (40).

10. Assembly (100) according to the preceding claim, characterized in that the heat-conducting element (30) and the magnetic core (22) are fixed to the heat sink by the same means (50).

11. A DC-DC voltage conversion circuit (1) for use in a vehicle comprising: - A first interface (10) for connection to a DC voltage source, - A second interface (17) for connection to an electrical energy storage unit, - An assembly (100) according to any one of the preceding claims, and - A first and a second switching circuit (11, 14), each comprising at least one switching bridge (12, 13, 15, 16), comprising switches arranged on either side of a midpoint (12a, 13a, 15a, 16a), the first and second switching circuits (11, 14) being connected on the one hand to the first interface (10), respectively to the second interface (17), and on the other hand to respective windings (21) of the transformer (20) via the midpoint (12a, 13a, 15a, 16a). 16a) of at least one switching bridge (12, 13, 15, 16).

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