Condenser with direct oil cooling and a component group incorporating this

Abstract

In various embodiments, a capacitor (10) with direct oil cooling is provided, comprising: a multilayer capacitor having at least two electrodes (2) separated from each other by a dielectric (3), each of which is coupled to a terminal electrode (21, 22), wherein the dielectric (3) is a polymer dielectric; wherein at least a portion of the multilayer capacitor is surrounded by a cooling housing (5) having an inlet and an outlet and being configured to be supplied with cooling oil (6) during operation; and wherein the multilayer capacitor surrounded by the cooling housing (5) is not surrounded by a potting material (4). Furthermore, a component assembly comprising the capacitor (10) with direct oil cooling is provided.

Description

[0001] The present invention relates to a direct oil-cooled condenser and a component assembly comprising the same. The condenser may preferably be a multilayer condenser.

[0002] Inverters are a key component of electric drives, as they are responsible for energy conversion between the traction battery, which can provide direct current, and the electric motor, which is typically supplied with a three-phase alternating current. A capacitor is connected in parallel between the traction battery and the power electronics output stage, essentially acting as an energy buffer. To date, inverters have almost exclusively used wound film capacitors. For example, multilayer capacitors such as NanoLam™, which are constructed with a polymer dielectric, can also be used. When these capacitors are used, particularly in the drivetrains of high-performance electric vehicles, they must be efficiently cooled to ensure reliable operation at high drive power levels.

[0003] The basic structure of a wound or film capacitor is known, for example, from US 2014 / 286064 A1 or EP 3 239 218 A1. Furthermore, DE 100 30 605 A1 discloses a switching power supply with a transformer and a capacitor integrated into the transformer by a multilayer foil winding. The transformer has at least one multilayer foil winding consisting of flat, conductive electrodes stacked alternately with an insulating dielectric foil to form an electrode stack.

[0004] The object of the present invention can be found in providing an efficient cooling system for a capacitor, in particular for an intermediate circuit capacitor in an inverter.

[0005] This object is achieved by means of the subject matter of the independent patent claims. Further preferred embodiments can be found in the dependent patent claims.

[0006] According to the invention, a capacitor with direct oil cooling is provided, which comprises a multilayer capacitor or multilayer capacitor having at least two electrodes separated from one another by a dielectric, each of which is coupled to an electrode, wherein the dielectric comprises a polymer dielectric. At least a portion of the multilayer capacitor is surrounded by a cooling housing, which has an inlet and an outlet and is configured to be traversed by cooling oil during operation. The multilayer capacitor surrounded by the cooling housing is not surrounded by a potting material. The capacitor can preferably have a plurality of electrode layers separated from one another by dielectric layers and can be provided, for example, as a wound capacitor or as a layer capacitor.

[0007] The capacitor used in the present invention is used without the conventional resin formulation with which the capacitor core - i.e. the electrode layers with the dielectric layers arranged between them - is usually potted. This potting compound surrounding the capacitor normally fulfills several functions: It ensures leak-free operation and electrical insulation, and also protects the component from moisture. In other words, the part of the capacitor arranged in the cooling housing is in an unpotted form, so that the arrangement of electrode and dielectric layers is directly exposed to the interior volume of the cooling housing. When the capacitor is in operation in an associated component group, the arrangement of electrode and dielectric layers is then exposed to the cooling oil flowing through the cooling housing or can come into direct contact with it.The cooling oil is an insulating or dielectric cooling fluid. The polymer dielectric can be adapted to the cooling oil used (or vice versa) so that it does not chemically react with the cooling oil used, and in particular, is not decomposed by it. In other words, the capacitor used is an oil-resistant capacitor.

[0008] Conventional wound film capacitors are not oil-resistant due to the polypropylene films used in them and would therefore require complex sealing for oil-cooled applications. Within the scope of the present invention, multilayer capacitors such as NanoLam™ can be used. These capacitors are constructed with a polymer dielectric, thereby achieving oil resistance. In oil-cooled applications according to the present invention, e.g., in inverters, multilayer capacitors of this type can be used.

[0009] The present invention has the advantage that a higher capacitance density can be achieved by omitting the potting material in the multilayer capacitor used. Furthermore, a multilayer capacitor without potting material can be cooled more effectively, since the potting material typically has a relatively poor thermal conductivity coefficient and therefore acts as a thermal barrier during the dissipation of waste heat. Direct contact of the cooling oil with the capacitor core, i.e., without any potting material in between, allows the waste heat to be dissipated more efficiently, allowing higher temperature limits to be used, or allowing the capacitor to be operated at higher power.

[0010] In addition, the service life of the multilayer capacitor can be improved by storing it in oil, as this prevents moisture from entering the capacitor via atmospheric humidity.

[0011] According to further embodiments of the capacitor, the multilayer capacitor can be arranged essentially in its entirety in the cooling housing. For the purpose of electrical contact, the connecting electrodes can be led out of the cooling housing.

[0012] According to further embodiments of the condenser, the multi-layer condenser can be divided into at least two units, so that the cooling oil can flow around a larger outer surface of the multi-layer condenser during operation. In other words, depending on the power density of the component group in which the condenser is installed, the multi-layer condenser can be divided into several smaller sub-units with the aim of optimizing the cooling performance of the cooling oil. The sub-units can be spaced apart from one another so that the cooling oil can flow between them. The spaces between the sub-units of the condenser can form cooling channels within the cooling housing.

[0013] The invention further provides a component assembly comprising a plurality of electronic and / or electronic components, wherein the component assembly comprises at least one capacitor with direct oil cooling as described above. The cooling housing of the capacitor is connected to the cooling circuit within the component assembly so that cooling oil can flow through it during operation. This also includes the case where the cooling housing corresponds to the housing of the component assembly in the case where the entire inner housing of the component assembly is directly cooled with oil.

[0014] According to further embodiments of the component group, it may comprise an inverter which is configured to convert an input voltage into a plurality of output voltages, each of which corresponds to a phase.

[0015] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0016] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. Fig. Figure 1 illustrates a multilayer capacitor according to the prior art. Fig. Figure 2 illustrates a multilayer capacitor according to the present invention.

[0017] In Fig. 1 shows a conventional multilayer capacitor 1. This has a plurality of planar electrodes 2, one part of which is coupled to a first terminal electrode 21 and the other part to a second terminal electrode 22. Between the electrodes 2, a polymer dielectric is arranged (not explicitly shown in Fig. 2). The electrodes 2, together with the dielectric layers arranged therebetween, are encapsulated with a potting material 3, which protects the capacitor core comprising the electrodes 2 and the dielectric layers from environmental influences and simultaneously functions as a housing.

[0018] Fig. 2 illustrates an embodiment of a multilayer capacitor 10 according to the invention. With regard to its internal structure, this corresponds to the usual Fig. 1 and consequently has a plurality of planar electrodes 2, one part of which is coupled to a first terminal electrode 21 and the other part to a second terminal electrode 22. Between the electrodes 2, a polymer dielectric is arranged (not explicitly shown in Fig. 2). However, the capacitor 10 according to the invention does not have a potting material 3 surrounding the electrodes 3. Rather, the capacitor core is exposed and arranged in a cooling housing 4. During operation of the capacitor 10 according to the invention, a cooling oil 5 flows through the interior of the cooling housing 3 and around the capacitor core, thereby cooling it. The cooling oil can come into direct contact with the surface of the capacitor core, and the heat to be dissipated does not have to be conducted through a potting material, which can improve the cooling performance. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2014 / 286064 A1

[0003] EP 3 239 218 A1

[0003] DE 100 30 605 A1

[0003]

Claims

[1] Condenser (10) with direct oil cooling, comprising: a multilayer capacitor comprising at least two electrode layers (2) separated from each other by a dielectric (3), each of which is coupled to a terminal electrode (21, 22), wherein the dielectric (3) comprises a polymer dielectric; wherein at least a part of the multilayer capacitor is surrounded by a cooling housing (5) which has an inlet and an outlet and is arranged to be supplied with cooling oil (6) during operation; and wherein the multilayer capacitor surrounded by the cooling housing (5) is not surrounded by a potting material (4). [2] Capacitor (10) according to claim 1; wherein the multilayer capacitor is arranged substantially as a whole in the cooling housing (5). [3] Capacitor (10) according to claim 1 or 2, wherein the multilayer capacitor is divided into at least two units, so that a larger outer surface area of ​​the multilayer capacitor can be exposed to the cooling oil (6) during operation. [4] Component group comprising several electronic and / or electronic components, wherein the component group comprises at least one oil-direct cooling capacitor (10) according to any one of the preceding claims. [5] Component group according to claim 4, wherein the component group comprises an inverter which is configured to convert an input voltage into several output voltages, each of which corresponds to a phase.

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