Intermediate circuit capacitor for an electric vehicle, with a cooling element and power electronics with this intermediate circuit capacitor

Abstract

The present invention relates to an intermediate circuit capacitor (1) for power electronics of an electric vehicle with a first electric motor and a second electric motor, with a capacitor housing (2), a first and a second electrode (3, 4) arranged in the capacitor housing (2), wherein the first electrode (3) has a plurality of first contact elements (5) for connecting the first electric motor and the second electrode (4) has a plurality of second contact elements (6) for connecting the second electric motor, and a separately formed cooling element (7) which has a cooling interface (8) for coupling a cooling channel.The surface of the capacitor housing (2) has a plurality of rib elements (9), and the cooling element (7) has a plurality of comb elements (10), which are designed such that they can engage with one another or engage with one another when the intermediate circuit capacitor (1) is in the assembled state. The cooling element (7) has a base element (11), in particular a cuboid-shaped one, with a side surface from which the comb elements (10) extend parallel to one another, and the cooling interface (8) for coupling the cooling channel is designed flatly on a side surface of the base element (11), which is arranged opposite the side surface from which the comb elements (10) extend. Furthermore, the invention also relates to power electronics of an electric vehicle having an intermediate circuit capacitor (1) according to the invention.

Description

The present invention relates to an intermediate circuit capacitor for power electronics of an electric vehicle according to the preamble of claim 1.Electric drive systems, in particular hybrid systems with two electric motors, have high-temperature environments with components which are under thermal load during operation of the drive systems. Above all, the conventional power electronics of these systems have intermediate circuits with intermediate circuit capacitors / intermediate circuit capacitances for the energetic coupling of a plurality of electrical networks to one another on a common DC voltage level, over which the entire power flow of the electrical drive systems runs. Conventionally, regions of the power electronics can reach temperatures of up to 120° C., which is why an intermediate circuit capacitor arranged therein, which is a component with (thermal) losses, can reach even higher temperatures. In order to prevent critical component temperatures, possibilities for sufficient heat dissipation must thus be provided.For example, DE 10 2021 108 168 A1 discloses an intermediate circuit capacitor for a vehicle, having a capacitor housing and at least two electrodes for connecting electric motors. In addition, the intermediate circuit capacitor has further contact elements which are in electrical connection with the electrodes. For the heat dissipation, a component formed separately from the capacitor housing is provided with a cooling channel or cooling liquid, with which one of the contact elements is in contact. Nevertheless, these cooling fluids can likewise reach high temperatures of, for example, 85° C. after prolonged operation, with the result that, in the case of an exemplary temperature requirement of at most 100° C., only approximately 15° C. of temperature difference is available for the cooling for the intermediate circuit capacitors. In particular, the heat dissipation by natural convection is not sufficient in such intermediate circuit capacitors, which is why additional (passive) measures are necessary for the heat dissipation.EP 3 836 175 A1 discloses an intermediate circuit capacitor according to the preamble of claim 1.With regard to further prior art, reference is made to U.S. Pat. No. 5,470,671.It is the object of the present invention to avoid or at least to alleviate the disadvantages from the prior art.This object is achieved by an intermediate circuit capacitor for power electronics of an electric vehicle according to the features of claim 1, namely that the intermediate circuit capacitor is formed in multiple parts from a capacitor housing and a cooling element and that the surface of the capacitor housing has a plurality of rib elements and the cooling element has a plurality of comb elements which are formed in such a way that they can be engaged in one another or engage in one another in an assembled state of the intermediate circuit capacitor. This makes it possible to provide an intermediate circuit capacitor, with the aid of which the criticality of heating the respective components is reduced.The invention accordingly relates to an intermediate circuit capacitor / intermediate circuit capacitor for power electronics of an electric vehicle, having a first electric motor (electric motor) and a second electric motor, having a capacitor housing, a first and a second electrode arranged in / on the capacitor housing, wherein the first electrode has a plurality of first contact elements / contact connections for connecting / connecting the first electric motor and the second electrode has a plurality of second contact elements for connecting the second electric motor, and a separately formed cooling element which has a cooling interface for coupling a cooling duct. The surface of the capacitor housing has a plurality of rib elements and the cooling element has a plurality of comb elements / fins which are designed such that they can be engaged in one another or engage in one another or nest together in an assembled state of the intermediate circuit capacitor.In other words, the intermediate circuit capacitor has a capacitor housing, preferably of cuboidal design, and a separate cooling element / cooling body, which can be connected or is connected to the capacitor housing. The connection / mounting can be effected via a comb plug principle between rib elements of the capacitor housing and correspondingly formed comb elements / fins of the cooling element. That is, the connection of the capacitor housing to the cooling element may result from an intermeshing of the fin elements of the capacitor housing into or between the comb elements of the cooling element, thereby forming an interleaved dual comb structure. The cooling element serves as a connection point for a cooling channel, preferably with a cooling liquid.Due to this multipart design of the intermediate circuit capacitor and in particular due to the cooling fin structure which is connected to the capacitor housing, the heat can be dissipated better from the capacitor housing, in particular due to the heat spreading and the surface enlargement via the fin elements on the capacitor housing. Advantageously, the surface area of the capacitor housing itself is thus increased by the formation of the rib structures, as a result of which heat dissipation can be made possible even more efficiently. Furthermore, the heat in / on the capacitor housing can be optimally absorbed by the longitudinally formed comb elements of the cooling element and preferably removed axially. The advantageous arrangement of the rib elements and the comb elements relative to one another improves the heat (removal) transport to the interface to the cooling channel.Advantageous embodiments are the subject matter of the dependent claims and are explained in more detail below.According to an advantageous embodiment, the rib elements of the capacitor housing and the comb elements of the cooling element engage alternately in one another in the assembled state of the intermediate circuit capacitor in such a way that each of the comb elements can be arranged between two of the rib elements or each of the rib elements can be arranged between two of the comb elements.In other words, the rib elements of the capacitor housing and the comb elements of the cooling element can be arranged parallel to one another in such a way that they alternately engage one another in the assembled state of the intermediate circuit capacitor. That is to say that a rib element is preferably followed by a comb element, which is then followed again by a rib element. Preferably, rib elements are arranged on the edge of the connected rib structure, i.e. in the assembled state of the intermediate circuit capacitor. Alternatively, the comb elements of the cooling element can also be arranged on the edge of the rib structure. In other words, either the rib elements or the comb elements can form the first edge elements of the plugged-together structure. Preferably, the fin elements and the comb elements extend along the entire length of the intermediate circuit capacitor.This alternating arrangement of the fin elements and the comb elements ensures that the heat can be distributed relatively uniformly and dissipated in an optimum manner.According to the invention, the cooling element is a base element, in particular a rectangular or rectangular basic element, having a side face from which the comb elements extend parallel to one another, in particular over the entire length of the capacitor housing. This means that the comb elements of the cooling element run in particular parallel to one another and can all run together on a common side surface of the base element or strike a common surface of the base element.According to the invention, the cooling interface for coupling the cooling channel is configured in a planar manner on a side surface of the base element, which side surface is arranged opposite the side surface from which the comb elements extend.This makes it possible to ensure that there is an optimum thermal transition to the cooling medium, for example to the cooling liquid / fluid. Because the plurality of comb elements strike the base element, which is preferably solid, and thus remove the heat from the condenser housing to the base element or the heat flows are joined together centrally there, the heat can be collected / removed better from the cooling channel. Furthermore, a base element formed in this way has large side surfaces which serve as optimum interfaces for the connection of the cooling duct. As a result, a further large-area element, in which the cooling channel is arranged, can advantageously be connected / placed to the respective cooling interface of the cooling element, such that effective heat can be dissipated via the large connecting surface.In a further advantageous aspect of the invention, the first and second electrodes can be rail-shaped and formed integrally with the respective first and second contact elements / contact connections. The respective contact elements are designed as alternating current connections which are connected to the respective electric motors. The two electrode(rails) / busbars can be partially accommodated in the capacitor housing.In a further preferred embodiment, the first and second electrodes can each have at least one further contact element for connecting / connecting a DC-DC converter / DC-DC converter of a battery. These contact elements thus serve for recharging / charging the battery of the electric vehicle.In a further advantageous embodiment, the capacitor housing and the rib elements can be formed integrally from a plastic.In a further advantageous embodiment, the cooling element and the comb elements can be formed, in particular in one piece, from a metallic material, in particular aluminum.The one-piece construction of the capacitor housing makes it easily possible to produce it with the rib elements, since the entire (plastic) capacitor housing can be cast in one step. Moreover, this makes it possible to easily modify the capacitor housing. Generally, the use of inexpensive plastic for the capacitor housing and the use of aluminum for the cooling element is inexpensive and simple. Furthermore, simple structural adaptations to the respective elements are possible on account of the passive cooling, for example no redesign of the cooling duct is necessary for corresponding adaptations.In a further advantageous aspect of the invention, the intermediate circuit capacitor can have a plurality of copper cooling angles for additional heat dissipation from an interior of the capacitor housing, which are arranged partially in the interior of the capacitor housing and partially protrude / project out of the capacitor housing.The arrangement of these copper cooling angles represents an additional possibility for the, in particular local, heat dissipation / heat dissipation of the interior of the capacitor housing.The invention further relates to power electronics of an electric vehicle having the aforementioned intermediate circuit capacitor.The invention and the technical field are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and / or figures. In particular, it should be pointed out that the figures and in particular the size relationships illustrated are only schematic. Like features are referenced by the same reference numerals. It is also pointed out that the features of the individual embodiments can be interchanged with one another and can occur in a specific combination. FIG. 1 is a perspective side view of the outer side of a power electronics housing for an electric (motor) vehicle, with an indicated intermediate circuit capacitor according to an advantageous embodiment. FIG. 2 is a perspective isometric view of a capacitor housing of an intermediate circuit capacitor according to the advantageous embodiment. FIG. 3 is a perspective isometric view of a cooling element of the intermediate circuit capacitor according to the advantageous embodiment. FIG. 4 is a perspective isometric view of the assembled intermediate circuit capacitor with the capacitor housing shown in FIG. 2 and the cooling element shown in FIG. 3.The present invention and one of the advantageous embodiments are described below with reference to the figures.FIG. 1 shows a perspective side view of the outer side of a power electronics housing for an electric (motor) vehicle, with an indicated intermediate circuit capacitor 1 according to an advantageous embodiment. The housing of the power electronics has a first (upper) housing half 15 and a second (lower) housing half 16, which are screwed or riveted to one another via a connecting surface provided on the revolutions of the housing halves 15, 16. The power electronics housing has the power electronics of the drive unit in the interior and an intermediate circuit capacitor 1, which is indicated by dashed lines in FIG. 1. Furthermore, a plurality of coupling elements 17 are arranged on the underside of the power electronics housing, which elements transmit a power flow between the drive unit and the power electronics.FIG. 2 shows a perspective isometric view of a capacitor housing 2 of an intermediate circuit capacitor 1 according to the advantageous embodiment. The capacitor housing 2, which is preferably formed from plastic, is of cuboidal design and has, on the inside, a multiplicity of foil capacitors (not shown here) and a first and a second rail-like electrode 3, 4. Preferably, these electrodes 3, 4 are cast with the top side of the capacitor housing 2. In this case, two sections of the respective electrodes 3, 4 project out in each case on the upper side of the potting compound or of the capacitor housing 2, in particular parallel to the longitudinal side faces of the capacitor housing 2. The protruding portions are arranged such that the two protruding portions of the respective electrodes 3, 4 are opposed in parallel. Furthermore, the sections of the first electrode 3 have a plurality of first contact elements 5, preferably three, and the sections of the second electrode 4 have a plurality of second contact elements 6, preferably three. The first contact elements 5 are designed and provided as alternating current (AC) connections for the first electric motor and the second contact elements 6 are designed and provided as alternating current (AC) connections for the second electric motor of the electric vehicle. The capacitor housing 2 further has, on the lateral surfaces of the casing, i.e. the surfaces opposite which the protruding electrode sections are arranged in parallel, and on the underside / base, a multiplicity of uniformly arranged and uniformly formed rib elements 9. The rectangular-parallelepiped rib elements 9 extend along the entire length of the capacitor housing 2 and are arranged in such a way that an approximately equally wide gap is always provided between two of the rib elements 9. The cross sections of the rib elements 9 are formed as rectangles. Furthermore, the electrodes 3, 4 have further contact elements 12 protruding from the capacitor housing 2, which are arranged in the region of one of the side surfaces of the capacitor housing 2 and are designed as direct current (DC) connections for a DC-DC converter of a battery. In addition, the capacitor housing 2 has on the opposite side face, in particular two protruding copper cooling brackets 14, which serve for the additional dissipation of the heat from the interior of the capacitor housing 2.FIG. 3 is a perspective isometric view of a cooling element 7 of the intermediate circuit capacitor 1 according to the advantageous embodiment. The cooling element 7 has a (solid) cuboidal base element 11, one side face of which extends a multiplicity of elongate cuboidal comb elements 10, in particular in the same number as the number of gaps between the rib elements 9, in particular parallel to one another. In this case, the comb elements 10 have approximately the same geometries as the rib elements 9 of the capacitor housing 2, so that they can engage in a fitting and flush manner between the rib elements 9, into the gaps located therebetween, or can be nested with these. Furthermore, the base element 11 of the cooling element 7 has a protruding rectangular cooling interface 8 on the side surface which is opposite to the side surface from which the comb elements 10 extend. The cooling interface 8 is provided as a connection point or contact surface for a further (external) element having a cooling channel, so that heat can be discharged from the base element 11 to the cooling channel or to the cooling liquid.FIG. 4 is a perspective isometric view of the assembled intermediate circuit capacitor 1 with the capacitor housing 2 shown in FIG. 2 and the cooling element 7 shown in FIG. 3 The flush engagements of the comb elements 10 of the cooling element 7 in the gaps which are arranged between the rib elements 9 of the capacitor housing 2 can be clearly seen. The base member 11 also abuts one of the side surfaces of the capacitor case 2. Advantageously, the comb elements 10 and the rib elements 9 form planar lateral jacket surfaces or a planar underside of the intermediate circuit capacitor 1 in the plugged-together / nested state.List of reference characters1 Intermediate circuit capacitor 2 capacitor housing 3 first electrode 4 second electrode 5 first contact element 6 second contact element 7 cooling element 8 cooling interface 9 rib element 10 comb element 11 base element 12, 13 further contact element 14 copper cooling bracket 15 first housing half 16 second housing half 17 coupling element

Claims

Intermediate circuit capacitor (1) for power electronics of an electric vehicle, having a first electric motor and a second electric motor, having a capacitor housing (2), a first and a second electrode (3, 4) arranged in the capacitor housing (2), wherein the first electrode (3) has a plurality of first contact elements (5) for connecting the first electric motor and the second electrode (4) has a plurality of second contact elements (6) for connecting the second electric motor, and a separately formed cooling element (7) which has a cooling interface (8) for coupling a cooling duct, characterized in that the surface of the capacitor housing (2) has a plurality of rib elements (9) and the cooling element (7) has a plurality of comb elements (10) which are formed in such a way, The cooling element (7) has a base element (11), in particular a rectangular basic element, with a side surface from which the comb elements (10) extend parallel to one another, in order to be able to engage one another or engage one another in an assembled state of the intermediate circuit capacitor (1), and the cooling interface (8) for coupling the cooling channel is configured flat on a side surface of the base element (11), which side surface is arranged opposite the side surface from which the comb elements (10) extend.Intermediate circuit capacitor (1) according to Claim 1, characterized in that the rib elements (9) of the capacitor housing (2) and the comb elements (10) of the cooling element (7) in the mounted state of the intermediate circuit capacitor (1) alternately engage one another in such a way that each of the comb elements (10) is arranged between two of the rib elements (9) or each of the rib elements (9) is arranged between two of the comb elements (10).Intermediate circuit capacitor (1) according to Claim 1 or 2, characterized in that the first and second electrodes (3, 4) are rail-shaped and formed integrally with the respective first and second contact elements (5, 6).Intermediate circuit capacitor (1) according to one of Claims 1 to 3, characterized in that the first and second electrodes (5, 6) each have at least one further contact element (12, 13) for connecting a DC-DC converter of a battery.Intermediate circuit capacitor (1) according to one of Claims 1 to 4, characterized in that the capacitor housing (2) and the rib elements (9) are formed integrally from a plastic.Intermediate circuit capacitor (1) according to one of Claims 1 to 5, characterized in that the cooling element (7) and the comb elements (8) are formed from a metallic material, in particular aluminium.Intermediate circuit capacitor (1) according to one of Claims 1 to 6, characterized bya plurality of copper cooling brackets (14) for additional heat dissipation from an interior of the capacitor housing (2), which brackets are arranged partly in the interior of the capacitor housing (2) and project partly from the capacitor housing (2).Power electronics of an electric vehicle having an intermediate circuit capacitor (1) according to one of Claims 1 to 7.

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