Patent Application
20250132099
The invention relates to a cylindrical capacitor, consisting of a plurality of cylindrical winding elements which are stacked one above the other in the longitudinal direction of the cylinder axis, which have electrical contact surfaces on their end faces, which are connected to switching strips which are guided over the cylinder jacket surface, and at least one connecting terminal according to the preamble of claim 1.
A contact assembly for end faces of capacitor windings is already known from DE 10 2018 117 283 B3.
The solution there is primarily concerned with the solderless construction of single-phase or multi-phase bucket capacitors, consisting of an electrically conductive spring element with a connection surface for a switching strip and/or a switching or fuse wire. The switching strips shown there can be made of a copper or aluminum material or another electrically conductive and weldable material. The spring element used there can be electrically and mechanically connected to the respective switching strip by welding. The capacitor coils used have contact surfaces on the end faces that are connected to the switching strip. A capacitor of this type can be inserted into a hollow cylindrical, cup-like housing and closed with a lid that has a corresponding connecting terminal. As an example, three capacitor windings are arranged on top of each other. The capacitor windings consist of a dielectric made of plastic film and two corresponding contact layers.
The upper ends of the switching strips are angled and guided onto an insulating disc. Furthermore, these ends of the switching strips are electrically connected to a switching or fuse wire.
In the capacitor with at least two winding elements according to DE 10 2018 103 166 A1, the capacitor comprises at least a first and a second busbar.
The first busbar and the second busbar connect the winding elements stacked next to each other on their lateral surfaces in parallel. The first busbar and the second busbar are arranged so that they overlap each other.
A corresponding winding element can be a capacitance unit. Each winding element of the known capacitor may have the same capacitance and may have a first pole of a first polarity and a second pole of a second polarity. The busbar is formed as a metallic strip or metallic bar and is configured for a local heavy current power distribution. Due to the overlapping of the first or second busbar, there is a small inductance of the connection of the busbars and between the winding elements of the capacitor stacked next to each other on their jacket surfaces.
A filter capacitor is already known from CN 104766722 A, in which the necessary electrical connections between the individual capacitors of a cylindrical assembly are realized via cylindrical surface segments. The aim here is to achieve the lowest possible inductive electrical connection. The connection segments mentioned must be manufactured as three-dimensional molded parts and are therefore tool-bound and must be adapted to the specific winding geometry. Universal use with regard to variable winding heights and diameters and with regard to the number of stacked windings is not possible with this prior art.
From the foregoing, it is the object of the invention to provide a further developed cylindrical capacitor which has very low inductive properties and which permits a structure consisting of a parallel connection of several winding elements stacked over their end faces, wherein the necessary internal circuitry is to be realized in a space-saving manner and with optimized electrical properties.
The object of the invention is solved by a cylindrical capacitor according to claim 1, consisting of a plurality of cylindrical winding elements which are stacked one above the other in the direction of the cylinder axis, i.e. axially one above the other, each of which has a winding capacitance.
The winding elements have electrical contact surfaces on their end faces, which are electrically connected to switching strips guided over the cylindrical surface. Furthermore, the cylindrical capacitor has at least one connecting terminal for each polarity.
According to the invention, two substantially circular first and second connecting discs adapted to the cylinder diameter are provided, which are electrically and mechanically separated from or by an insulating element.
The first, and therefore lower, of the connecting discs is electrically connected directly to a contact surface of an upper cylindrical winding element in the direction of the connecting terminal.
Furthermore, starting from the first connecting disc, a plurality of first switching strips are formed which are distributed over the cylinder jacket surface and extend substantially parallel, and which are each connected to a contact surface facing away from the connecting terminal of the number of winding elements.
Starting from the second of the connecting discs, a plurality of second switching strips are formed which are distributed over the cylinder jacket surface and extend congruently over the first switching strips.
These second switching strips lead to the other contact surfaces of the mutually stacked winding elements for the purpose of electrically connecting them in parallel, wherein an insulating layer or insulating sheath is provided at least in the overlapping area of the first and second switching strips.
The connecting discs are each connected to at least one connecting terminal or have at least one connecting terminal integrally formed therewith.
The surface shape of the switching strips is adapted to the cylinder radius or cylinder circumference in the area where they extend along the cylinder jacket surface. In other words, the switching strips fit snugly against the cylindrical circumferential surface of the respective winding elements.
The switching strips are preferably arranged symmetrically on the cylinder circumference side, for example in a group of two or four.
Furthermore, according to the invention, the switching strips are designed as a separate component and can be connected to the respective connecting disc, for example by welding or soldering.
The connecting discs have a substantially identical shape and size.
In one embodiment of the invention, the insulating element has a cap shape or the shape of a lid, wherein the edge of the cap or lid extends over a partial section of the upper winding element and the first switching strips connected thereto.
In one design of the invention, the number of stackable winding elements is between two and twelve.
The number of respective first or second switching strips, which are guided circumferentially over the jacket surface of the cylinder, is between two and six, preferably between two and four.
The first and second switching strips are arranged with maximum overlap.
The assembly according to the invention can be inserted into a cup in a known manner and closed with an integral or separate cup base or a cup lid, wherein the cup lid has openings to the connecting terminals, which are designed as screw terminals, for example.
The invention will be explained in more detail below with reference to an exemplary embodiment and with the aid of figures.
The polarity described in the drawings and in the exemplary embodiment is exemplary and could also be reversed, wherein:
The cylindrical capacitor shown in the figures consists of, for example, two cylindrical winding elements 1, which are arranged one above the other in a stack. A first connecting disc 3 is electrically connected directly to a contact surface 5 of the upper of the cylindrical capacitor windings 1, which is located in the direction of the connecting terminal 4.
Starting from this first connecting disc 3, the first switching strips 7 are distributed across the cylinder jacket surface and extend substantially parallel. In the example shown, there are four switching strips 7.
The switching strips 7 are surrounded by an insulating sheath 71 in the area where they extend in the longitudinal direction of the cylinder.
The lower end of the switching strips 7 is electrically connected to the lower contact surface of the lower of the cylindrical winding elements 1 facing away from the connecting terminal 4.
The connection of the two winding elements 1 is polarization-correct from the negative terminal pole of the upper winding to the negative terminal pole of the lower winding.
The contact surfaces 9 and 10 of the winding elements are located opposite each other in the quasi central area of the capacitor assembly and are also contacted there, as shown in the illustration according to
The contact surface of the lower coil 1 facing away from the connecting terminal 4 is marked with the reference sign 100 to distinguish it from the contact surface of the upper coil.
The switching strips 7 are angled over the end faces of the corresponding winding elements and connected to the connecting disc 3 by soldering or welding at points 30 or electrically contacted accordingly in the area of the lower contact surface 100.
The illustration according to
In the illustration according to
The other switching strips 8, which also have the necessary electrical connection in areas 31, are now routed to this second connecting disc 2.
The second connecting disc 2 has positive polarity, which therefore also applies to the connecting terminals 41.
The second switching strips 8 lead to the middle area between the stacked winding elements 1, specifically to the contact surfaces 9 and 10 there (see also
The connection is made in such a way that an electrical parallel connection of the exemplary two stacked cylindrical winding elements 1 is obtained.
According to the exemplary embodiment, a cylindrical capacitor with two to twelve winding elements stacked in the direction of the cylinder axis is thus realized. The capacitor assembly has a first and a second, preferably circular, connecting disc. These each comprise one or two terminals. The switching strips or strip conductors are not an integral part of the connecting discs, but are connected to the connecting discs on the outside.
One of the two connecting discs is directly connected to a first contact surface of the upper of the winding elements.
The overlapping and mutually electrically insulated switching strips are installed symmetrically on the outside, preferably in two to four copies, and alternately contact the touching upper contact surfaces 9 and the lower contact surfaces 10 of the winding elements 1. Each upper contact surface of each winding element and each lower contact surface of each winding element is alternately connected to an electrical potential of the connecting discs, so that the necessary parallel connection results.
An exemplary setup has shown that the example capacitor with two windings and a capacitance of approx. 500 μF has a self-inductance of only approx. 6.5 nH when using the described multi-band circuit with overlapping switching strips. This is well below the values that can be achieved with a standard connection of the same capacitor windings within a cylindrical capacitor without overlapping switching strips.
When the example capacitor was set up with the same capacitance, but with four winding elements, a self-inductance of approx. 5 nH was achieved.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 2021 106 503.6 | Nov 2021 | DE | national |
| 20 2022 100 064.6 | Jan 2022 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/078659 | 10/14/2022 | WO |
